ArmorThane Pu 104 a polyurethane sealants, adhesives, and binders

Polyurethane Sealants,
Adhesives and Binders
PU 104A
James M. O’Connor

SynUthane International
James M. O'Connor, Ph. D, President and co-founder of SynUthane International Inc., a Consulting
/ Contract Research Training Organization dedicated to the Polyurethane Industry. SynUthane
International Inc. was founded in 1998 and is a continuing and growing resource for the
polyurethane industry. SynUthane International has brought together a group of experts in the
polyurethane field who have the background, knowledge, and experience to help companies find
technical and business solutions to the many new developments in Polyurethane and other
growing technologies. SynUthane has consulted for and performed contract research with many
large International Chemical Corporations directly involved in the Polyurethane Industry.
SynUthane has also worked with many other large or medium sized non Urethane related
companies who need urethanes expertise to consider establishing new business platforms .
Prior to the formation of SynUthane, Jim had led R & D in the polyurethane and chemical industry
for over 30 years. Jim's experience and research background covers all segments of the
polyurethane industry from polyols to isocyanates, TPU's to coating as well as surfactants,
polymers and other specialty chemicals.
After achieving a Ph.D. from Purdue University, Jim worked for Goodyear Corp, NDM Corp., Olin
Chemicals, Olin Hunt (Electronics), and ARCO Chemical Chemical and has authored over 50 U.S.
patents and publications.

The information provided in this seminar is believed to be technically current
and accurate, however, ACC and the instructors make no warranty,
expressed or implied,
1. Of merchantability or as to correctness of any specific information herein
2. Of fitness or suitability of that information for a particular purpose
3. With respect to freedom from infringement of third party patents or rights, or
4. With respect to the commercial utility of technology discussed

The designation “CASE” encompasses a very
broad spectrum of applications, chemistries, uses
and forms.
• At one end of the spectrum of properties are
very soft rubbery joint sealants or soft tacky
adhesives
• At another end are very hard abrasion and
scratch resistant automotive coatings or hard
structural adhesives
• One can apply a one component liquid or paste
that cures with ambient moisture, heat or UV
radiation
• Or apply 2 components neat or dissolved in
solvent and mixed before application
• CASE urethanes can be applied with
sophisticated mixing equipment, a brush or
trowel or spray gun or mixed in a bucket prior
to application
CASE Polyurethanes

• The hardness of urethanes can easily
be measured.
• Hardness in itself is not a good
indicator of performance.
• Sealants are generally very low
durometer materials.
• Adhesives can range across a broad
range of durometer reading
depending upon the application.
• Coatings can also be formulated
across a broad durometer range.
• Typical urethane elastomers can be
soft (shore A =30-40) to very hard
(shore D = 75) and also be produce
as full density solid elastomers to
very low density microcellular
foams.
TPU’s
Sealants
Adhesives
Coatings
Hardness Scales Used for
Urethanes

Polyurethanes Applications Grid
Today we’ll concentrate on
74.9
68.6
62.4
56.2
49.9
43.7
37.4
31.2
25.0
18.7
12.5
6.2
5.6
5.0
4.4
3.7
3.1
2.5
1.9
1.3
0.6
Density,lbs/ft3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.09
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0.01
SpecificGravity,gms/cc
0 10 20 30 40 50 60 70 80 90 40 50 60 70 80
Shore A Hardness Shore D Hardness
Sealants

CASE Polyurethanes Come in a
Number of Different Forms / Types
Form Type Cure Characteristics
100% Solids One Component Moisture Cure
UV/E-Beam
Powder - Blocked Isocyanate
Powder- Non-Emissive (internally blocked)
Two Component Isocyanate - Polyol Reactive Cure
Isocyanate - Amine Reactive Cure
Solvent Borne One Component Moisture Cure
Air Drying Alkyds
Blocked Isocyanates
Non Reactive (Laquer)
Water Borne One Component Non Reactive - Polyurethane Dispersion (PUD)
One Component with crosslinker added

Urethane Form / Type Advantages* Disadvantages*
100% Solids no solvent emissions not generally applicable for thin appearance applications
rapid cure easy achieved direct handling of isocyanates may be required
direct injection of components into mold may require more sophisticated equipment to apply
less waste
potentially low investment for mixing and molds
easier to manufacture
Moisture Cure no solvent emissions for many types too high humidity will give bubbling
excellent properties achievable no cure at very low humidity
everything there in one container potential shelf life and storage issues
urea groups give improved properties more difficult to manufacture
Solvent Borne controllable pot life solvent emissions
easier handling for many types direct handling of isocyanates required
excellent surface characteristics achievable not applicable for thick cross sections
Waterborne solvent emissions significantly reduced property deficiencies versus solvent based
easy handling
less toxicity for one component
Powder no solvent emissions only certain thicknesses possible
less waste can't use on many plastics because of high temperature
UV/E-Beam no solvent emissions high investment
rapid cure not applicable for all geometries
no waste
* What may be an advantage in one form may be a disadvantage in another
AdvantagesandDisadvantagesoftheDifferent
Forms/Types
By no means is this an exhaustive list of advantages or disadvantages, one needs to evaluate the
specific form or type for each CASE application.

or
coating
Sealant
(lb/in2)
Stress Strain Plots for Polymeric Materials

Polymers are viscoelastic materials that show features of a
glassy material, a brittle solid, an elastic rubber or a
viscous liquid depending upon temperature, i.e. a polymer
may be glass like at low temperature, a rubber at room
temperature and a viscous liquid at high temperature
• the temperature where a polymer passes from a glassy state to a
rubbery (or crystalline) material is the glass transition
temperature (TG )
• depending on the specific material, the TG may occur well below
room temperature or much higher, and consequently will largely
define the useful range of polymer properties.
• the temperature where a polymer transitions from a crystalline
material to a viscous liquid is (TM )
Polymer Structure Property
Relationships

The effect of temperature on the
total volume of a polymer
The TG signifies a transition of the
polymer from a glassy to a
rubbery state.
As the temperature of a
polymer is raised above its TG,
the effective distance
between molecular segments
is increased.
This is evident by an increase
in the slope of the polymer's
specific volume as a function
of temperature (See Figure).
The polymer chains have also
less restrictions to movement.
Flexibility, toughness, and
solvent penetration increase
at temperatures above the TG,
tensile strength and elastic
modulus decrease.

Tg Region - cooperative motions
of segments now occur, but the
motions are sluggish ( a
maximum in tan δ curves are
observed in DMA experiments)
Rubbery Plateau – without
crosslinking the time to melt
becomes shorter, but is still
longer than the time scale for
disentanglement. (The higher
the molecular weight, the
greater the chain entanglements)
Terminal Flow – as the time scale for disentanglement
becomes shorter, the melt becomes more fluid like in its behavior
glassy state
confirmational changes
severely limited
The change in modulus versus
temperature of a polymer

Since polymers are high molecular weight consisting of long
molecules that are intimately mixed and highly intertwined or
entangled
Below the glass transition temperature TG, the glassy high
molecular weight molecules are essentially immobile
• the polymer will exhibit stiffness or brittleness in this “plastic”
region
Above the TG, “the rubbery region”, the movement of the
chains is less restricted
• the polymer will be softer, more flexible and less brittle in the
“rubbery” region
• at higher temperature, in order for the rubbery polymer to
transition to a viscous liquid , the chains must first un-entangle
• this phenomenon extends the usable temperature range of the
rubbery region (rubbery plateau)
• The temperature at which the rubbery material becomes a viscous
liquid may be increased by cross-linking the individual polymer
chains
What Determines the Polymer Properties

All Polyurethanes are high molecular weight polymers with an
extremely broad range of properties due to wide range of formulation
variables:
• Polyol type, functionality and molecular weight
• Polyisocyanate type, functionality and molecular weight
• Potential to use an extensive number of different chain extenders,
cross-linkers or other active hydrogen containing compounds to modify
the hard and soft segment content and properties of the polymer
• Use of many different types of additives, fillers, catalysts and
surfactants to change physical properties
• Utilization of different reaction or process conditions to change
properties i.e. prepolymer verses one shot processes etc.
By manipulating these variables, polymers with a very broad range of
properties and products are possible!
How do these variables affect polymer properties?
Polyurethane Structure Property
Relationships

Polyurethane Structure Property
Relationships
•The molecular structure of polyurethanes can vary from
rigid polymeric (cross-linked), to linear, elastomeric flexible
chains
•Flexible foams and TPU elastomers have segmented
structures, made up of long flexible chains (polyols) linked
by polyurethane and polyurea aromatic hard segments
– Their character depend largely on hydrogen bonds
between polar groups of the polymeric chain, mainly
among N-H groups (electron acceptors) and carbonyl
groups (electron donors) of urea and urethane groups
– Hydrogen bonds can also be formed among N-H groups
and polyester carbonyl groups and, more difficultly, with
polyether oxygen atoms (weak bonds)
•As a result of the very high functionality components that
are utilized, rigid PU foams are highly cross-linked
structures that don't show the segmented structures
present in elastomeric and flexible polyurethanes.
Hydrogen Bonding in Polyurethanes

Chain Extender & Cross-linker
With a chain extender (f =2), the polymer chains remains
linear and because the polymer is linear, it is thermoplastic
and can be processed via extrusion, injection molding etc.
With a cross-linker (f >2) branch points are
introduced which will ultimately lead to an
infinite network. The polymer is
thermosetting and cannot be further
processed without polymer degradation
branch or
Cross-linking
sites
Linear extension

By introducing chemical cross-linking into the polyurethane
different effects are realized.
Chemical cross-links are introduced -
• by the reaction of the excess isocyanate with urea or urethane
groups yielding biuret or allophanate cross-linking i.e. flexible
foam
• by using tri or poly-functional alcohols or amines as chain
extenders i,e. cast elastomers
Properties change in a different way than seen with hard
segment cross-linking.
Cross-linked Polyurethanes

Polyurethane properties are influenced by the segmented two phase morphology (structure)
that exits on the micro-scale.
While chemically similar materials mix uniformly, chemically different materials will separate
much like water and oil leading to two different phases.
Since urethanes are made up of relatively non polar polyols - either polyether or ester, (soft
segment) and units of relatively polar - diisocyanate / low molecular weight chain extenders
(hard segment) in the same polymer, phase separation occurs between these two dissimilar
types of materials.
Segmented Structure
Note : the soft segment consists almost exclusively of polyol but two
or more of these polyols can be joined together by a diisocyanate
depending on the overall stoichiometry of the formulation.
urethane
group
rest of
extender
rest of diisocyanate
rest of
polyol

hard segment(s)
soft segment(s)
note: both the hard and
soft segments tend to
align with each other rather
than mix, thus behaving
like a blend of incompatible
polymers
AVisual Representation of theTwo Phase
Behavior

Essentially all of the constituents in the
polyurethane will influence the phase
separation and consequently the final
properties. In general:
• increasing polyol molecular weight lowers the polymer TG and
increases phase separation
• increasing hard segment content will (may) increase phase
separation, increase TM and also TG and also room temperature
modulus.
• unsymmetrical isocyanates or chain extenders will increase the
mixing of the phases (increase TG and lower the TG or TM of the
hard segment) and minimize the rubbery region
• amine extenders will increase the phase separation (decrease
TG and increase the TG or TM of the hard segment)
• added chemical cross-linker will increase TG and the ultimate
use temperature but will also increase the TG or TM of the hard
segment
• The rubbery plateau region will gradually disappear as the
overall functionality of the system increases (2 – 6+) and/or the
polyol molecular weight approaches that of the chain extender.
• The type of polyol, ether or ester determines many of the end
use properties.

The main difference between adhesives and
sealants is that sealants typically have lower
strength and higher elongation than do adhesives.
However, there appears to be a lack of
consistency from supplier to supplier as to what is
or is not a sealant.
• Some products called sealants are in fact adhesives.
• While some that are called adhesives are actually sealants.
• There are no standards on how to classify a product that has
both adhesion and sealing capabilities.
Defining a Sealant /Adhesive
CONFUSION!

What is anAdhesive? What is a
Sealant? How Do They Differ?
An adhesive is a material that joins two surfaces together by bonding them. It is
usually applied as a thin layer between two surfaces or substrates.
A sealant is a material designed only to fill up a space. The spaces
can be joints, gaps or cavities that occur between two substrates.

Defining a Sealant /Adhesive
Confusion!
The overall difficulties
in defining exactly
what constitutes a
sealant / adhesive is
seen with the different
volumes shown in
several market studies.
Is this a sealant, a rigid foam
or an adhesive?

ChemQuest Group, Cincinnati, Ohio, estimates the 2008 global
adhesives and sealants market at $29.2 billion.
• Europe accounting for $11.9 billion
• North America $10.1 billion
• Japan $3.2 billion
• Rest of the world $4.0 billion.
On a ten year outlook ChemQuest estimates that the global
adhesives and sealants market will average 4.4 percent growth.
• The US will see 3.8 percent growth
• Europe, 3.6 percent
• Japan, 3.0
• the rest of the world, 8.9 percent.
Adhesives and Sealant Market

The Consulting firm Kusumgar, Nerlfi & Growney (KN&G), report the global consumption of
formulated adhesives was 16.6 billion pounds in 2009 worth $20.6 billion.
• Volume was down 5% compared to 2008
• North America took 27% of the 2009 adhesive dollars
• Volume in North America declined 10% from 2008.
• Largest end use market decline was automotive OEM, followed by construction and woodworking
• Aerospace, disposable products and consumer adhesives and sealants end uses came out the best in
2009.
• Europe experienced an 8% fall. (Europe consumed 32% of the global adhesive dollars in 2009)
• Poundage was up slightly in the Asia-Pacific region as growth in China and India offset the
declines in most other countries.
• South American consumption was down 3% in 2009.
• The Asia-Pacific region led in dollars in 2009 with its consumption of just over $7 billion,
representing 34% of the global total.
• China was an outlet for nearly one-half of the region’s dollars and is forecast to expand at a
9% annual rate through 2014.
• Japan was one-fifth of the region’s value and is a mature market. India represented only 5%
of the Asia-Pacific dollars but is the fastest growing country for adhesives.
This shift to low-VOC technologies has had a major impact and may offer new opportunities.
“These alternatives are gaining acceptance in other parts of the country and are pushing higher
VOC products into decline that much faster.”

Kusumgar, Nerlfi & Growney (KN&G) 2011

The figure summarizes the four major adhesive
technologies in value for 2009.
 Water-based adhesives are the leading type, with
$6.7 billion consumed.
• (33% of the global adhesive sales dollars).
• Water-based adhesives are generally lower in cost and they
represented over one-half of the 2009 pounds.
 Solvent-based technology is second in dollars, with
its $5.7 billion (28%) of the value.
 Hot-melts were third, representing one-fifth of the
dollars, with packaging and disposable products
leading outlets.
 The 100% reactive category was slightly behind
hot-melts in dollars, with a 19% share. These products
are generally the highest priced adhesives, and they
captured only 4% of the volume.
Epoxy, polyurethane, cyanoacrylate, anaerobic,
structural acrylic, etc. products are included.
Source: Kusumgar, Nerlfi & Growney (KN&G) 2011

Adhesives employ a host of polymer types in their
formulation.
Acrylics are topmost, with their $3.6 billion in sales
representing a 17% share.
• Acrylic emulsion-based formulations were 72%
of the dollars and solvent-based acrylics
accounted for 23%.
• Smaller amounts of structural acrylics and
radiation-cured hot-melts are used.
Water-based polyvinyl acetate (PVAC) and vinyl
acetate-ethylene (VAE) adhesives comprised 14% of the
adhesive dollars. Woodworking and packaging are the
larger outlets.
Polyurethane adhesives were 12% of the sales and are
formulated using each of the four major technologies.
• Solvent-based formulations were one-half of the
polyurethane dollars, with flexible packaging
and footwear the largest applications. The 100%
reactive polyurethanes were about one-third of
the dollars, with flexible packaging and
automotive its major outlets. Hot-melt
polyurethanes were 10% of the sales and water-
based formulations another 7%.
Kusumgar, Nerlfi & Growney (KN&G) 2011

Global Adhesives And Sealants
Industry
$36 billion in 2006
4% growth over 2005
grow at 3.8% to 2008
Source: ASI- April 2007
Asia is growing 2-2½
times faster than
developed regions
Polyurethanes
constitute only
about 10% of the
adhesive and
sealants market

NAFTAPolyurethane Market
CPI Market Study 2009

Polyurethane Markets

Raw Material Demand

A sealant is a viscous material that changes state to become solid,
once applied, and is used to prevent the penetration of air, gas,
noise, dust, fire, smoke or liquid from one location through a barrier
into another.
Typically, sealants are used to close small openings that are difficult
to shut with other materials, such as concrete, drywall, etc.
Desirable properties of sealants include insolubility, corrosion
resistance, and adhesion.
Uses of sealants vary widely and sealants are used in many industries,
for example, construction, automotive and aerospace industries.
Sealants

Frost & Sullivan defines a sealant as a liquid, paste or foam material, that,
when applied to a joint or orifice, forms a tight seal against liquids (water) or
gases.
Sealants are materials that are used where elastomeric as well as structural
strength properties may be needed.
According to DIN 52460 sealants are plastic/elastic compounds based on
certain polymers.
• They are applied for the sealing of joints, hems, areas or openings.
• The sealants build a bridge between
the surfaces of work pieces out of
equal or different materials.
• Their function is largely influenced by the
following items:
• By surface bonding of the sealant to
the subject (adhesion)
• By strength inside the sealant (cohesion)
Defining a Sealant

The main difference between adhesives and sealants is that sealants typically have lower strength and
higher elongation than do adhesives.
 Since the main objective of a sealant is to seal assemblies and joints, sealants need to have
sufficient adhesion to the substrates
 Resistance to environmental conditions to remain bonded over the required life of the assembly
 Sealants between substrates having different thermal coefficients of expansion or differing
elongation under stress, need to have adequate flexibility and elongation
 Sealants generally contain inert filler material and have a paste-like consistency to allow filling of
gaps between substrates
 Low shrinkage after application is often required
Sealants fall between higher-strength adhesives at one end and extremely low-strength putties and
caulks at the other
 Putties and caulks serve only one function – i.e., to take up space and fill voids.
Sealants, on the other hand, despite not having great strength, do convey a number of properties.
 Seal the substrate at the glue line
 Effective in keeping moisture in or out of the components in which they are used
 Provide thermal and acoustical insulation and may serve as fire barriers
 Sometimes they possess certain electrical properties
 They may also be used for smoothing or filleting
Sealants are often called upon to perform several of these functions at once.
Sealants

Sealants are generally chosen for their ability to fill gaps, resist relative movement of
the substrates, and exclude or contain another material.
A sealant has three basic functions:
1. it fills a gap between two or more substrates,
2. it forms a barrier by the physical properties of the sealant itself and by adhesion to the
substrate, and
3. it maintains sealing properties for the expected lifetime, service conditions, and
environments.
Sealants are generally lower in strength than adhesives, but have better flexibility.
1. Usually, a sealant must effectively bond to a substrate in order to perform these
functions.
2. Sealants are like adhesives in many ways.
3. They are often considered together because some formulations can perform as either an
adhesive or as a sealant, and some formulations actually provide both functions.
Sealants, however, must perform distinctive tasks that stand them in a separate
category from adhesives.
Defining a Sealant

Nine Basic Types Of Sealants
1. Silicones
2. Polyurethanes
3. Bituminous
4. Acrylics
5. Polysulfides
6. Polyvinyl chloride (PVC)
plastisol types
7. Butyls
8. Oleoresinous
9. All other types
All Other Types
•styrene-butadiene rubber
•ethylene-propylene-diene-
monomer (EPDM)
•neoprene (polychloroprene)
•nitrile (acrylonitrile-butadiene)
•fluoroelastomers
•chlorosulfonated polyethylene
•anaerobics
•all other thermoplastic
elastomers (TPEs)
•modified silane polymers.

Chemical Family or Curing Type Strengths Weaknesses
Silicones, one component (moisture initiated
condensation) and two components
(condensation or addition)
Best weathering, highest flexibility, good
adhesion and heat resistance
High moisture vapor transmission, low depth
of cure, slow curing
Polyurethanes, one component (moisture
initiated condensation) and two component
(condensation)
Good weathering, best adhesion, high
flexibility
Weak UV resistance, weak heat resistance,
some types show hydrolytic degradation
Polysulfides, one component (moisture
initiated condensation) and two component
(condensation)
Low moisture vapor transmission rate, fuel
resistant, good flexibility
Slow curing, low depth of cure
Acrylic latex (water evaporation) Easy to use, easy clean-up High shrinkage, poor weathering, fair flexibility
Butyls (sulfur vulcanization) Lowest moisture vapor transmission rate,
good flexibility
Fair weathering
Vinyl plastisols Good adhesion, low cost Fair flexibility, fair weathering
Asphalts / coal tar resins (cooling oxidation) Low cost, fuel resistant Poor weathering
Oleoresinous (oil- and resin-based) sealants Low cost, easy application Poor joint movement, limited adhesion, cracks
on aging
Hot melts (butyl, polypropylene, etc.) Low cost, expandable Limited adhesion, fair flexibility
Polyvinylacetate latex (water evaporation) Low cost, good adhesion to wood, usable
as filler
Rigid, not recommended for exterior
applications, high shrinkage, yellows with age
Epoxy, two component Good adhesion and chemical resistance,
fast cure, low degree of shrinkage
Rigid, limited movement capability, requires
metering and mixing of two parts
Strengths and Weaknesses of the
Different Sealants
SpecialChem online paper

Classification of Sealants by
Performance
Performance Classification Sealant Characteristics Example Types
Low performance  Typically 0-5% movement
capability
 2-10 years service life
 Low cost
 Oil and resin based sealants
 Asphaltic and bituminous
mastics
 Polyvinyl acetate
 Epoxy
 Polyvinyl chloride plastisol
Medium performance  5-12% movement capability
 Medium cost
 Hydrocarbon rubber based
sealants
 Acrylic
 Chlorosulfonated polyethylene
 Hot melt sealants based on
synthetic rubber
High performance  Greater than 12% movement
capability
 High cost
 Polyurethane
 Silicone
 Fluoropolymers
 Styrene butadiene copolymers
 Polychloroprene (neoprene)
 Polyethers

2008 NAFTASealants Production
CPI - 2009

Expansion joints in concrete constructions
Control joints in floor slabs
Joints between window frames and masonry
Joints between panels
Joints around penetrations
The joints between the corrugated
Boards around bathtubs
Joints in glass assemblies
The dry construction boards
Boards of swimming pools - water tanks (under the hydrostatic
pressure)
- Floor Boards in chemical plants, etc (resistance chemicals
required)
Construction Sealants

Polyurethane sealants are primarily used in transportation applications for automotive
window glazing (both OEM and aftermarket) and in trucks etc.
 seal and bond windshields to the frame of the automobile
 provides support and rigidity to the roof
Typically, to improve glass adhesion, organo functional silane coupling agents are
included in the formulation
Transportation Sealants
Organo Functional Silane Coupling Agents
Trade Name Chemical Name
A 151 vinyltriethoxysilane
Z 6030 gamma-methacryloxypropyl trimethoxysilane
A 186 beta-(3,4-epoxycyclohexyl) ethyltrimethoxysilane
Z 6020 N-(2-aminoethyl)-3-aminopropyltrimethoxysilane
A 1100 3-aminopropyltriethoxysilane
Some blocked systems are used as seam sealants
and applied before the body goes through the paint ovens

Silicone and polyurethane sealants account for nearly 51%
of the US sealant market.
Hybrid construction sealants have increased in
prevalence.
As a group, hybrid sealants represent only about 9% of the
market by volume and MS sealants represent only 1.6%
although they are growing faster than their more
conventional counterparts.
Sealant Market

Seam Sealing Sealing of Joints or
Overlaps
Surface Sealing
Surface Sealing on Motors,
Gearings, Housings and Flanges
Sealing
Breakthroughs
Sealing Application Examples

Advantages
All PU sealants have :
• good elongation at break 250 to 600 %,
• low to high modulus = 0.25 to 1 MPa
according to formulations,
• excellent elastic recovery higher than 90 %
• Low shrinkage
• Generally Overpainted
• excellent abrasion resistance and tear
strength,
• their resistance to indentation makes
them the best sealants for floor joints,
• service elongation range from 12 to 25 %
according to formulations, ( they meet the
standard ISO 11600-F class 25 LM or 12.5
LM ),
All have excellent adhesion to a wide variety
of substrates: concrete, metals (preferably
with a primer), wood, PVC,
Excellent aging resistance, a 20 years
durability can be achieved or expected.
Polyurethane Sealants
Disadvantages
The only drawbacks are:
– a slow cure ( skin over time 5 to
20 minutes at 20 °C and 50 %
RH, (moisture cure system)
– complete cure after 2 to 7 days
at a speed of 2 mm / day )
moisture cure system)
– resistance to UV is only fair,
– moderate resistance to
chemicals, oils, solvents, acids
and alkalis,
– moderate resistance to
hydrolysis. (some formulations
may be sensitive to hydrolysis).
General Properties

One Component Types
• moisture cure
• blocked isocyanate
• hybride sealants
Advantages
• Everything there in one cartridge for
immediate use
• ease of application and excellent general
characteristics
• Moisture cure generates stronger urea
linkages that improve properties
Disadvantages
• More demanding to manufacture, i.e., need
to completely remove water in all
components
• Package stability issues
• Much slower cure
• Depends on ambient moisture to cure
• too humid – bubbling
• too dry – excessively long or insufficient
cure
Both OneAnd Two Component
Polyurethane SealantsAre Sold Today
Two-Component Types
• conventional –NCO and –OH
reaction to cure
• Blocked Reactive sealants
Advantages
• Ease of manufacture
• Essentially non-bubbling
• Rapid through cure
Disadvantages
• More time consuming for the
applicators

The chemistry for polyurethane sealants is similar to that of
elastomers or flexible foams with no blowing agents
Sealants are high molecular weight polymers with a broad
range of properties due to wide range of variables:
• Polyols
• Diisocyanates
• Other Key Components in the formulation
Besides the conventional reaction of an isocyanate group with a
polyol, many sealants are produced from other different
chemistries.
• Reaction with water – moisture cure
• Blocked isocyanates
• Hybrid modified sealants
Polyurethane Sealants

Typical Polyol Structures
Polyether PolyolsPolyester Polyols
(CH2)4 O
(CH2)4
O
OHO-(H2C)4 (
O)X H
Polybutanediol Adipate
O
O
O
O
O
O
O OH
OH
OH
Castor Oil
Castor oil Polyols
H2C
C C
CH2
HC C
CH2H3C CH2 CH
CHH2C
OH
HO
n
0.2 0.2
0.6
Poly Bd Polyol

Hardness of polyurethanes as a function of humidity exposure. (1) Polyester urethane, (2) Polyester urethane, (3)
Polycaprolactone, (4) Polyether urethane, (5) Polyether urethane, (6) Polybutadiene polyol urethane, (7) Polybutadiene
polyol urethane. [8]
Effect of Polyol Type on Sealant
Hydrolytic Stability
Ester
Ether polybutadiene

Polyisocyanate type, functionality and molecular weight
• For most sealants, either TDI or an MDI variant is the isocyanate of choice
• Aliphatic isocyanates are used if a non yellowing sealant is required (isocyanates not attached to an aromatic
ring)
Either prepolymers or “monomeric” isocyanate are used to produce 2 component sealants while only
prepolymers are used for 1 component sealants
Polyisocyanates
80/20 TDI
OH + ROCN NCO
ROCN NH
HO
O
O O
O
NH R NCO
ROCN HN
O
O O
O
NH R NH O
O
NH R NCO
O
O
X
ROCN NCO
where x = 1,2,3 ...
perfect product
oligomeric
products
unreacted
free isocyanate
Conventional Prepolymer Process
1 equivalent 2 equivalent
+
+
Depending upon the specific properties
desired, these prepolymers will typically
have a residual -NCO content of 1 – 3%
(% NCO = weight of unreacted –NCO / total
weight of all the constituents in the
prepolymer

There is the potential to use an extensive number of different chain
extenders, cross-linkers or other active hydrogen containing compounds to
modify the properties of the polymer
• since most sealants are low on the hardness scale chain extenders are not
extensively used
• higher temperature properties achieved through chemical cross-linking
Use of many different types of additives – solvent, plasticizers, thixotropes
fillers, catalysts and surfactants to change physical properties
• Solvent – sometimes up to 10% solvent is added to a sealant to improve
processability but high levels will lead to bubbling and other problems
• Plasticizers or Hydrocarbon Extenders – used to soften, minimize bubbling,
potentially improve hydrophobicity or lower cost of the sealant
• Thixotropes – things such as bentonite clay (2 conponent only), microballons or
organic coated fumed silica or calcium carbonate are added to improve
leveling and to minimize sag
• Fillers – Calcium carbonate and other fillers are used to improve some
properties and also lower cost
OtherKeyComponents

The reaction of an isocyanate (–NCO) with water, followed by the
reaction with the amine that is generated is the basis for a moisture
cured systems)
One component moisture cure sealants are generally formulated
from a prepolymer rather than the basic isocyanate
One Component Moisture Cure
Chemistry

Components % by weight
Isocyanate prepolymer prepared by reacting:
Polypropylene glycol diol EW 1000 68 parts
Polypropylene glycol diol EW 1600 19 parts
Toluene diisocyanate 13 parts
Dibutyl tin dilaurate 0.1 part
32.0
Titanium dioxide, rutile 2.0
Calcium carbonate 35
Precipitated Silica 6.0
Molecular sieve ( humidity scavenger ) 1.0
Phtalate plasticizer 20.0
Organosilane epoxy functional ( adhesion promoter ) 1.0
UV absorber 0.5
Toluene 2.0
Typical Formulation
% NCO = 2.9

Raw Materials,
parts by weight
Slow curing formula Fast curing formula
NCO prepolymer, equivalent weight 1272, slow curing 400 ---
NCO prepolymer, equivalent weight 1355, fast curing --- 450
Carbon black 300 30
Titanium dioxide 20
Silica 20 50
Toluene 10 10
Properties
Tack free time, hrs at 21C and 50% RH, 13-24
Cure time, days 5-10
Hardness, Shore A 20-30
Tensile strength, psi 300-400
Elongation, % 500-600
Single Component,
Gun Grade Moisture Cure
Polyurethane Sealant Formulation
Higher mol wt
but also higher
functionality
(kN/m2)
(2070-2760)

3M Commercial Moisture Cure
Polyurethane Sealant

Dymonic® is a high-performance,
low-modulus, one-component,
moisture-curing, polyurethane joint sealant.

The majority of polyurethane sealants are produced from polyols derived from propylene
oxide.
Until fairly recently, all propylene oxide based polyols were produced with potassium
hydroxide as the catalyst for the reaction.
• There is a side reaction with propylene oxide when KOH is used to produce polyols.
• The side reaction is the rearrangement of propylene oxide to allyl alcohol.
• Formation of allyl alcohol results in a decrease in the desired functionality of the polyol.
Propylene oxide based Polyols
O
CH3
R OHHO +
OH
O O H
H O O R O O H
starter
propylene
oxide
polyol
allyl ether monol
allyl
alcohol
base catalyzed
isomerization
+ propylene
oxide
Monol Formation From KOH Catalysts
x y
z
preferred reaction
undesired
side reaction
There is an OH
group on each
side so the
functionality is
the desired two.
The side reaction
produces a polyol
with an OH group
on one side and an
allyl double bond
on the other side.
The functionality
here is one rather
than two

Other Catalysts for PPG Polymerization
• Ba(OH)2 and CsOH can substantially reduce unsaturation of polyols
(unsaturation ~ 0.02 meq/g for a 2000 equivalent weight polyol – a 5-
fold reduction)
• Double metal cyanide catalysts (DMC) produce polyols with very low
unsaturation (<<0.01 meq/g for a 2000 equivalent weight polyol)
Polyols produced with DMC catalysts have:
• Extremely low unsaturation
• Nearly true functionality
• Very narrow molecular weight distribution
• Much higher molecular weights possible
“New” Polyol Technology

EffectofMonolFormationonFunctionality
Bayer Material Science LLC

Bayer, API 2003
Sealants derived from Prepolymers based on
polyether polyols produced from DMC catalysts
& polyols derived from KOH catalysis

Sealants from DMC Polyols
•Sealants based on DMC polyols consistently show higher elongation and lower 100% modulus
values while maintaining tensile and tear strengths.
•Higher molecular weights obtained from DMC polyols allow for the use of less prepolymer
while maintaining not only tensile properties, but also maintaining weathering and mechanical
durabilities.
•DMC polyether polyols give the formulator the ability to decrease costs per cartridge by 3 –
5% on volume.
•KOH prepolymers show appreciable elongation as prepolymer levels are decreased, but suffer
from insufficient tensile and tear strength below 50% prepolymer.
•The use of DMC-catalyzed polyols affords the formulator the widest range of diol/triol ratios
possible and allows for the maximum amount of products that can be developed with the least
number of polyols.
Bayer, API 2003

Latent or Blocked Isocyanates
Another reaction utilized extensively in many urethane applications entails
blocking the isocyanate with a labile blocking agent followed by the liberation
of this group via heat or by displacement by another nucleophile.
R N
H
B
O
OCN-R-NCO + 2BH
AH = any active hydrogen containing compound: some typical blocking agents
are shown below.
-
N
H
B
O
H3C
C2H5
N
O H N
O
H
BH =
Methyl Ethyl Ketoxime (MEKO) Caprolactam (eCap)
OH
phenol

H2N
R
NH2
'R R"
O
+
'R
"R R'
R"
N
R
N
H2O
ketamine
One Component Sealants with a Blocked
Isocyanate and a Reactive Diluent
(Ketamine)
•Ketamines are the reaction product of a ketone with an amine with the
elimination of water
•The reaction is reversible and the amine is regenerated in the presence of
water

R N
H
B
O
N
H
B
O
+ R-NH2 R N
H
NH-R
O
N
H
R-HN
O
amine displaces the blocking group off the urethane
R-N=CR1R2 + H2O
One Component Sealants with a Blocked
Isocyanate and Reactive Diluent (Ketamine)
• When a isocyanate terminated prepolymer is mixed directly with a ketamine, the resulting product
could have poor package stability.
• To resolve this problem, the prepolymer can be blocked with a phenol and in the presence of
moisture the diamine is produced by the hydrolysis of the ketamine which then displaces the phenol
blocking group to cure the system.
• The shelf stability of this system can be improved even further by incorporating an amino silane and
substantial amounts of trimethoxy silane into the system. This serves several purposes:
1. The amino silane reacts with any of the isocyanate groups that were not blocked or have become
unblocked.
2. The RSi(OCH3)3 that is formed will improve the bond strength as well as act as a curing agent.
3. The trimethoxy silane will scavenge up any remaining water by reacting with the water to produce
methanol.

A blocked one component sealant,
moisture cured with a ketamine and
stabilized with a silane
Modified Sealant
Material Weight Equivalence
Prepolymer
PPG glycol 2000 0.93
toluene 200
TDI 166 1.91
nonyl phenol 209 0.95
Ketamine
Jeffamine 400 400 2
methyl isobutyl ketone 200 2
Sealant
above prepolymer 100 0.038
Thixcin R (castor oil) 15
Benzoflex 9-88 (plasticizer) 26
CaCO3 60
paraffin wax 2.2
process oil 4.4
above ketamine 10.7 0.036
Adhesion Promoter
epoxy silane or ketimino silane 0.2
Non-Reactive Silane Sealant Properties
Property Control Epoxy Ketoimino
Silane Silane
% elongation 943 975 887
Tensile MPa (psi) 1.35 (196) 1.10 (160) 1.78 (258)
Peel Adhesion N/cm(pli)
Glass 1.76 (10) 9.45 (57) 8.75 (50)
Aluminum (anodized) 1.05 (6) 8.75 (50) 7.0 (40)
Aluminum (milled) 0.35 (2) 1.75 (10) 1.4 (8)

These are the most successful
sealants since the seventies because
they display a combination of many
excellent and important features:
• excellent resistance to water,
chemicals, weathering, aging,
heat, temperature cycles ( heat
and cold ), and consequently an
excellent durability up to 40
years,
• modulus may be low or higher
according to the formulations,
elongation at break is very high,
up to 500 %, so that the service
elongation may reach 25 to 50 %
which are the best values
achievable for all sealants,
• price is now very moderate
because they are produced in
very large quantities ( 200 000
tons per year now for the total
world production ).
Silicone Sealants

Property Silicone Polyurethane
Recovery from stress ++ ++
UV resistance ++ +
Cure rate (one
component sealant)
++ - to ++
Low temperature
gunnability
++ -
Tear resistance - ++
Cost - ++
Paintability -- ++
Available in colors - ++
Unprimed adhesion to
concrete
- ++
Resistance to hydrolysis ++ -
Non-bubbling ++ -
Self-leveling formulations - ++
Polyurethane and silicone sealants are often referred to as "high performance" sealants in that they
provide significant adhesion, movement capability, and durability. However, even these adhesives have
certain disadvantages that can limit their use. Comparison of common properties of these sealants is
shown below.
Scale: -- very poor, - poor, + moderate, ++ good
Specialchem
Online paper
Polyurethane Versus Silicone Sealants

Silicone Urethane
Hybrid Sealants

There is a Non Urethane sealant technology developed over 25
years ago in Japan (MS Polymer Sealants).
• These are relatively new products in Europe or USA, but they have
been used for over 25 years in Japan.
• These are polyethers (NOT POLYURETHANES) terminated with silyl
groups.
• Most of these sealants are one component that cure by reaction
with the ambient air humidity.
The MS sealants have high performance capabilities with many
of the same characteristics as a urethane sealant, however, the
one-part MS sealants cure much faster than a one-part
urethane sealant and find use in the construction industry
where property development speed is important.
Silicone Hybrid Sealants

The structure of an MS polymer consists of a polyether backbone and
methyl-dimethoxysilyl terminal functionality.
• It does not have urethane, urea, or other functional groups that are
typical in polyurethane sealants.
• MS polymer's polyether main chain provides low viscosity, low glass
transition temperature, flexibility over a wide temperature range, and low
odor.
MS sealants are suitable for a wide range of applications, except for
glazing. The initial adhesion of MS sealants onto glass is good, but its
exposure to sunlight or UV over a long period of time generates bond
strength deterioration.
MS sealants, like polyurethane sealants, should not be used at
temperatures greater than 85°C but they cure at 3 mm/day, faster than
one component PU.
The chemistry is shown in the next slides.

No urethane groups present in the polymer
H O O R O O H
x y
KOH
Cl
O O R O O
x y
O O R O O
x y
Si(OCH3)3
Pt Catalyst
H
Si
OCH3
OCH3
OCH3
(H3CO)3Si
+
MS Polymer Sealant Chemistry

MS Polymer Sealants
Typical Formulation
Components % by weight
KANEKA MS Polymer 5203 H
(propylene oxide polyether terminated with dimethoxysilyl group)
100
Plasticizer 55
Titanium oxide 20
Thixotropic agent 2
UV absorber 1
Dehydration agent 2
Adhesion promoter 3
Hardening catalyst dibutyl tin diacetyl acetonate 2

Kaneka Bulletin
MS Polymer Sealants

MS sealants have well balanced properties and performance. Some of
the unique properties of MS sealants are:
• Solvent free
• Low temperature gunnability: the viscosity of MS sealants is less
dependent on temperature changes
• Storage stability: shelf life is excellent although sealant must be
protected from moisture
• Weather resistance and durability: MS sealant shows no cracking,
splitting, discoloration or adhesion failure after seven years of testing
in desert climate
• Stain resistance: MS sealants do not stain as some silicone sealants do
because of low molecular weight silicon materials that bleed from the
surface of sealed joints
• Paintability: MS sealants provide good paintability unlike silicone
sealants
• Adhesion: MS sealants provide adhesion to various substrates including
metals, plastics, wood, and ceramics.

OCN NCO + CH3CH2-NH-CH2-CH-CH2-Si(OCH3)3
H
N
H
N
N-CH2-CH-CH2-Si(OCH3)3
O O
CH3CH2
N(CH3O)3Si-CH2-CH-CH2
CH3 CH3
CH2CH3
ASilylated Urethane (SPUR) One
Component Moisture Cured Sealant
•The MS Polymer Technology has been extended to hybrid Silicon Polyurethane Sealants
(SPUR).
–Silane-terminated polyurethanes (SPUR+ prepolymers) have become increasingly appealing to
adhesives, sealants and coatings manufacturers due to the synergy between the silane-curing
mechanism and the polyurethane backbone properties.
•The basic chemistry is based on the reaction of secondary aminosilanes and urethane
prepolymers
•Formulations developed using this technology:
– offer fast room-temperature cure
– good durability
– adhesives or sealants are free of unreacted isocyanates
– also no bubbling during cure
– a broadened formulation latitude compared to conventional polyurethane technologies.
Polyurethane prepolymer secondary aminosilane

SPUR prepolymers allow the formulator to use a wide variety of additives and
adhesion promoters. Formulations based on SPUR polymers offer fast room
temperature cure and good durability.
Other than being isocyanate- and solvent-free, their benefits include the
following:
• Good elasticity and durability
• Primerless adhesion to both organic and inorganic, porous and non-porous
substrates
• Superior chemical resistance, such as to automotive fluids
• Minimal shrinkage
• Improved tack free time and deep section cure
• Excellent weatherability, non-yellowing
• Immediate paintability
• Non-staining of porous substrates
• Possibility of clear formulations
Urethane – Silicone Hybrid Sealants

Property Comparison
Property MS Polymer Polyurethane Silicone
Environmental
friendliness
10 5 9
Non-bubbling 10 6 10
Low temperature
gunnability
10 8 10
Slump resistance 10 10 10
Quick cure 10 7 10
Storage stability 10 7 9
Body (tooling) 8 10 8
Weather resistance 8 6 10
Adhesion to various
substrates
10 5 8
Mechanical
properties
10 10 10
Heat resistance,
mechanical stability
9 8 10
Non-dirt pickup 10 10 5
Stain resistance 8 8 5
Paintability with
water-based paint
10 10 3 10 is excellent, 1 is poor

Silylated polyurethane sealants have excellent adhesion to conventional
construction construction substrates and good durability. These sealants have
excellent adhesion characteristics and bond well to plastic surfaces including PVC,
ABS, polystyrene, and acrylic .
The table shows that silylated polyurethane offers generally superior adhesive peel
strength on all but the acrylic substrate in comparison to the four conventional
polyurethane sealants.
Peel Strength,
lb/in, to
substrate:
MS Sealant
RTV Silicone
Sealant
Silylated
Polyurethane
Sealant
Polyvinyl
chloride
7 2 23
ABS 2 10 20
Polystyrene 1.5 3 23
Acrylic 1.5 17 3
Urethane – Silicone Hybrid Sealants

Component parts Physical Properties Level of adhesion promoter
2.0 1.5 0.8
SPUR Polymer* 100
calcium carbonate(3.5μ)
6 0 T a c k F r e e T i m e ( h r ) 3 . 5 3 . 3 3 . 3
calcium carbonate (0.07μ)
4 0 H a r d n e s s ( s h o r e A ) A S T M C - 6 6 1 2 6 . 0 2 4 . 0 2 8 . 0
SiO2 6 Elongation % ASTM D-412 296.0 324.0 366.0
TiO2 2 Tensile Strength (psi) ASTM D-412 197.0 190.0 182.0
diisodecyl phthalate 40 100% Modulus (psi) ASTM D-412 79.0 67.0 57.0
Tinuvin 231 1 200% Modulus (psi) ASTM D-413 136.0 119.0 103.0
Tinuvin 622 1 Tear (lb/in) ASTM D-624 28.0 27.0 25.0
Organofunctional silane Sealant Viscosity (cps x 1000) 415.0 422.4 435.2
(adhesion promoter)** 2.0,1.5, 0.8
Silquest A-171 silane Adhesion Properties ASTM C-794
(dehydrating agent) 1 Aluminum 18 C 21 C 16 C
DBTDL 0.063 Glass 20 C/A 23 C 20 C
PVC 18 C/A 23 C 21 C
* MDI/PPG-4000; NCO/OH = 1.5 ABS 19 C 20 C/A 17 C/A
capped with Silquest A-1120 (aminosilane) Polystyrene 20 C 23 C 3A
** different levels to evaluate adhesion where C= 80% cohesive failure, C/A=60-80% cohesive failure
A=<50% cohesive failure
A Silylated Urethane (SPUR) One
Witco Data
Phenylaminopropyl trimethoxysilane

Example: Silylated Urethane
Structure versus Reactivity
Skin-formation begins after just a few seconds when α-trimethoxysilane is used, as
compared to about 25 minutes in the case of γ-trimethoxysilane.
Wacker Bulletin

Example: Silylated Urethane
Structure versus Reactivity
The key advantages of Wacker GENIOSIL® α-silanes are:
Faster hydrolysis and condensation of the Si-alkoxy groups
Faster production processes
Better chemical and mechanical product properties
A wider range of applications for organofunctional silanes

Silylated Urethane Structure
versus Reactivity
The tensile strength of STP-E based on difunctional α-NCO-silane is significantly higher
compared to the trifunctional γ-NCO-silane.
In addition, a higher elongation at break is achievable with the α-system. The fact that
α-silanes cure faster than γ-NCO-silane means the products display altogether better
mechanical properties and curing characteristics.
α-silane
ß-silane

Recently Momentive Performance Materials introduced a
further improvement to this technology (US
7,365,145)
1. Prepare silane with 50/50 wt % 2,4/4,4-MDI
2. Blend “normal” polyols with the SPUR
3. Facilitate cure with tin catalyst
4. The free polyol cures along with the SPUR and becomes part
of the sealant backbone
Depending on what polyol is used as the diluent, the Spur
has:
1. A Lower viscosity
2. Increased functionality (sucrose polyol blend)
3. Mixed backbone (polyester polyol blend)
4. Slightly lower cure rate but still cures completely
New Improved SPUR Technology

New Improved SPUR Technology
Momentive Patent - US 7,365,145

This work (SPUR) has been extended by using
isocyanate silanes (US 5,990,257).
The advantage here is that there is no need for a
prepolymer
• the dual functionality – isocyanate / silane is
reacted directly with the high molecular weight
polyol to introduce the silane end – group.
Silylated Urethane (SPUR)
(CH3O)3Si-CH2-CH2-CH2--NCO
Silquest A-Link 35

Witco Data
Formulation and Properties of SPUR Sealants
Components Low Medium High
Modulus Modulus Modulus
Acclaim 8200/IPDI (NCO/OH = 0.7
capped with A-Link 35 100 100
Acclaim 4200/Fomrez ER431(70/30)/MDI
(NCO/OH = 0.7) capped with A-Link-35 100
DIDP 80 80 40
CaCO3 240 240 90
SiO2 thixotrope 5 5 5
UV Stabilizer 2 2 2
TiO2 Whitner 5 5 5
Desicant Silquest A-171 1.5 1.5 1
Adhesion Promoter Silquest A-1120 0 2.5 2
Silquest Y-11637 2.5 0 0
tin catalyst 0.2 0.2 0.15
Sealant Properties
viscosity at 25C in cps 128,000 134,400 131,200
Tear strength (lb/in) 35.4 39.5 42.2
Tensile strength (lb/in2) 203 169.7 295.9
Elongation % 741 536 222
100% Modulus (lb/in2) 50.8 79.8 210.3
Hardness Shore A 27 31 44
A Silylated Urethane (SPUR) One

Construction sealants based on these hybrid polymers:
• Have better weathering characteristics than conventional
polyurethane sealants, but without the odor and unpaintability
problems of conventional silicone sealants.
• They also provide better adhesion, abraision resistance and low
temperature extrudability than silicone sealants.
• Both MS and SPUR silyl terminated sealant systems are also isocyanate
and solvent-free systems.
• The absence of isocyanate broadens the range of formulation
possibilities.
• The lack of isocyanates result in improved shelf life and stability along
with reduced tendency for bubbling during cure.
• Silyl terminated sealant formulations allow the use of aminosilane
adhesion promoters and hindered amine light stabilizers which are not
otherwise employed .
• They are claimed to combine the strength of polyurethanes with the
weathering resistance of silicones.
Silicon Containing Hybrid Sealants

R-NCO + HS-R'-SH R' N S
R
SH
O
H
O2
R' N S
R
S
O
H
S
R
S N
H
R'
O
Other Types Of (1K) Hybrid Sealants
Based on mercaptan end groups
Cure mechanism the same as polysulfide sealants -
oxidative cure

R'OH Urethane
R'O N
H
O
R
RNCO +
Two Component Sealant (2K) Reactive/
Ambient Cure
•The isocyanate is generally in the form of a prepolymer
•The PO based polyols are primarily capped with EO to facilitate fast reaction
•Primary reaction is that of an isocyanate and polyol although some moisture cure can occur
•Amines can also be used but they generally react too fast to process
– The amine can be partially replaced with blocked amines (ketamines) to give sufficient working
time
– The free amine reacts directly followed by the hydrolysis of the ketamine generating the rest of
the amine
R
R'
N
RR
R'
OR NH2
++ H2O
ketamine

In addition to extender oils and fillers common to rubber processing, asphalt modification provides the
basis for formulating many low-cost elastomeric caulks, sealants and coatings.
These data indicate that, while the tensile strength of the elastomers is only moderately affected, the
elongation changes significantly with the level of asphalt and the isocyanate functionality.
Two Component Sealant (2K) Reactive/
Ambient
PAPI 27 – f=2.6; PAPI 901 – f=2.3; ISONATE 2143 – f=2+
Sartomer Bulletin

The quantity of oil which can be incorporated into a Poly bd resin system is a
function of the oil and the type of filler, if present.
Cured Poly bd resin systems may be formulated which incorporate in excess
of 100 parts oil per 100 parts Poly bd resin and do not "bleed" oil in the final
product.
Oil extension provides many other advantages such as further improvement in
hydrolytic stability, control of premix viscosities, gel time, cure time, and the
ability to attain higher filler loading.
The use of materials such as chlorinated waxes and oils also incorporates fire
retardant properties into the finished product.
In most cases, non-black fillers contribute less reinforcement to Poly bd resin
based elastomers than carbon black fillers. However, there are several
advantages inherent in using nonblack fillers.
1. Ease of dispersion
2. Lower viscosity build-up
3. Light color
4. High loadings
5. lower cost
TwoComponentSealant(2K)Reactive/Ambient
Sartomer Bulletin

Poly bd Expansion Joint or Crack Filling Compound Formulation and Properties
Ingredients Quantity Comments Typical Properties of Formulation
Viscosity Part A @ 85F 18,500 cps
Part A: Resin @ 70F 44,500 cps
@ 50F 200,000 cps
Poly bd R-45HTLO 100 polyol Hardness (14 sec)
2-ethyl-1,3-hexanediol 15 short chain diol chain extender to improve @ 72F 28 Shore A
properties and mixing ratio @-14F 45 Shore A
Asphalt 120-150 Pen. 150 soft grade used in road construction Elongation at Break
CaCO3 150 filler @ 73F 345%
dibutyltin dilaurate 0.1 catalyst @ 14F 307%
Process oil 100 used to reduce viscosity @-22F 232%
100% Modulus
Part B: Hardener @ 73F 122 psi
@ 14F 461 psi
polymeric MDI @-22F 1,040 psi
mixing ratio - A/B 100/7.3 cures polyols Tensile Strength
@ 73F 300 psi
@ 14F 810 psi
@-22F 1,190 psi
Tear Strength
@ 73F 60 pli
@ 14F 160 pli
@-22F 280 pli
From data on Poly bd® resins, from Elf Atochem

Dymeric® 240 FC is a gun grade, multi-component, chemically
curing, polyurethane sealant that includes a tintable base,
curative packet, and a choice of 70 standard colors. A
Limestone Pretinted version is available.
Dymeric 240 FC applications range from pre-cast tilt-up
concrete, masonry, and exterior insulating and finishing systems
(EIFS), to metal curtain walls, and perimeter joints around doors
and windows. It can also be used in certain water immersion
applications.

Tremco THC-900 and 901 are multi-component, chemically
curing polyurethane joint sealants that include a tintable
base, curative packet, and a choice of 70 standard colors.
Tremco THC-900 is a self-leveling joint sealant for use in any
traffic rated horizontal expansion or control joint. THC-901
is a semi self-leveling joint sealant that can handle sloped
traffic areas up to 10%. Both sealants can be used in parking
garages, plazas, terrace decks, floors and sidewalk joints.

Characteristics of polyurea technology that can prove
useful in adhesives and sealants include:
• Fast, consistent reactivity and cure
• Moisture and temperature insensitivity during processing
• Excellent physical properties / elastomeric qualities
• Very low water absorption qualities
• Hydrolytic stability
• Thermal stability
• Good UV and color stability (with aliphatic isocyanate
types)
• No solvents or VOCs required for thin coatings.
Polyurea Sealants

Characteristics of Polyurea,
Polyurethane, and Polyurea/
Polyurethane Hybrids
Chemistry Characteristics
polyurea
A polyurea provides a chemical backbone containing amine
linkages. Polyurea has been used as an industrial coating and
sealant in severe environments with good chemical
resistance. For example, it is resistant to hydrocarbons and
hydrogen sulfide gas and immersed sewage application.
polyurethane
Usually these formulations have no amines in the polymer
backbone. All functionality is considered to be
hydroxyl. Polyurethanes show good longevity and are
relatively inexpensive.
Polyurea/polyurethane Hybrid
This hybrid is the result of a chemical reaction between an
isocyanate and a mixture of polyol and amine
reactants. Hybrid formation can display some of the negative
problems associated with polyurethane chemistry (less
resistance to immersion or extreme application temperature
conditions).

Performance Comparison of Polyurea
to Other Common PolymersPerformance Polyurea Poly-urethane Epoxy Acrylic Polysulfide
Physical strength Low-High Low-Mid High Mid-High Low-Mid
Elongation High High Low Low-Mid Mid-High
Impact resistance High Mid-High Mid Mid-High Mid
Abraision
Resistance
High Mid-High Mid-High Mid-High Mid
Adhesion to
concrete
Low-High Low-Mid High Low-Mid Low-Mid
Cure shrinkage Low Low Low High Low
Permeability Low Mid-High Low Low-Mid Mid-High
UV resistance Mid-High Low-High Low High High
Creep Low High Low-Mid Low-Mid High
Temperature limit Low-High Mid Mid-High Mid Low-Mid
Chemical
resistance:
 Mineral acid Low-Mid Low-Mid Mid-High Mid Low-Mid
 Organic acid Mid Low-Mid Mid Mid Low-Mid
 Alkali Mid-High Low-Mid High High Low-Mid
 Chlorinated
solvent
Low-Mid Low-Mid Low-High Low-Mid Low-Mid
 Oxygenated
solvent
Low-Mid Low-Mid Low-High Low-Mid Low-Mid
 Hydrocarbon
solvent
Low-Mid Low-Mid Mid-High Low-High Low-Mid
 Salts High Mid-High High High Mid-High
 Water High Low-High Mid-High Mid-High Low-High

Polyurea properties can range over a significant degree depending on the formulation
employed. For example, typical polyurea sealant properties range in hardness from 20-95 Shore
A, 180-1600 psi tensile strength, 150-1000% elongation, and 100-180 pli tear strength. The
Table shows the properties of two optimized polyurea formulations.
Components Formulation 1 Formulation 2
Part A:
Desmodur E 210 100.00 100.00
Part B:
Jeffamine D-2000 41.28 38.00
Desmophen NH 1420 47.67 51.75
Tinuvin 292 0.24 0.25
Tinuvin 1130 0.24 0.25
Irganox 1135 0.49 0.50
Kronos TiO2 9.82 5.00
Properties: (Mix Ratio: 1:1 by
Volume)
Gel time, mins 6.1 9.5
Hardness, Shore A 91 91
Tensile strength, psi 1218 714
100% Modulus, psi 689 502
200% Modulus, psi 876 611
300% Modulus, psi 1091 720
Maximum elongation, % 352 450
Tear resistance, pli 341 288
For Desmophen NH 1420, R =

OCN-R-NCO +
O
HO
O
O
R'(NH2)2
R-NHCO
OH
CH2O
HO
H2C O CONHRNH-R-NH
O
CONH-R-NHCO
x
prepolymer glycidol epoxy terminated urethane prepolymer
urethane epoxy hybrid sealant polymer (Dimeric)
OtherTypesOf(2K)HybridSealants

Physical Property
Test Methods
The tests typically used for other rubbers and plastics are also used for urethane
sealants, adhesives and binders. i.e. tensile, tear, elongation etc.
Urethane adhesives, sealants and binders are chosen as high quality substitutes
for many other materials serving these markets and the specific physical tests
developed for these materials are also used for these urethanes.
Some of the testing for both adhesives and sealants can very different or unique
compared to the testing requirements for other types of products.
Some of the specific tests are listed in the Appendix at the end of this section.

An adhesive is defined (DIN 16 920) a non-metallic material which is capable
of joining together substances by means of surface adhesion and inner
strength. The effectiveness of adhesives is based on surface adhesion
(adhesion) and the power of attraction of the adhesive molecules exerted
between themselves (cohesion).
• It is a mixture in a liquid or semi-liquid state that adheres or bonds items
together.
• Adhesives may come from either natural or synthetic sources.
• The types of materials that can be bonded are vast but they are especially
useful for bonding thin materials.
• Adhesives cure (harden) by either evaporating a solvent or by chemical
reactions that occur between two or more constituents.[
• Adhesives are advantageous for joining thin or dissimilar materials, minimizing
weight, and when a vibration dampening joint is needed.
• A disadvantage to adhesives is that they do not form an instantaneous joint,
unlike most other joining processes, because the adhesive needs time to cure.
Defining anAdhesive

Examples of Cohesive and Adhesive
Failure
Failure Mode Inference
Adhesive failure (interfacial) Cohesive strength > interfacial strength
Cohesive failure (bulk) Interfacial strength > cohesive strength
Adhesive / cohesive (mixed failure mode) Interfacial strength ~ cohesive strength
Failure Modes as an Inference to Bond Quality

Mechanisms of Adhesion
Adhesion, the attachment between adhesive and substrate may occur
either by mechanical means, in which the adhesive works its way into
small pores of the substrate, or by one of several chemical mechanisms.
The strength of adhesion depends on many factors, including the means
by which it occurs.
• An actual chemical bond may occur between adhesive and substrate.
• electrostatic forces could hold the substances together.
• Van der Waals forces between molecules could occur.
• Diffusion of the glue into the substrate, followed by hardening.
In order for optimal bonding to be obtained, certain prerequisites must
be met:
• Suitability for use on the substrates to be bonded
• Wetting of the surfaces
• Suitability to meet the specification
• Precise application of the adhesive
Defining anAdhesive

Non-reactive Adhesives
• Drying adhesives
• adhesives that harden by drying, either solvent based or as an emulsion.
• Pressure sensitive adhesives
• form a bond by the application of light pressure to marry the adhesive with the adherend
• Contact adhesives
• Contact adhesives are used in strong bonds with high shear-resistance like laminates and
in footware (attaching outsoles to uppers).
• Contact adhesives must be applied to both surfaces and allowed some time to dry before
the two surfaces are pushed together.
• Hot adhesives
• hot melt adhesives, are simply thermoplastics applied in molten form (in the 65-180 0C
range) which solidify on cooling to form strong bonds between a wide range of materials.
Reactive Adhesives
• Multi-part adhesives
• Multi-component adhesives harden by mixing two or more components which chemically
react. This reaction causes polymers to cross-link into acrylics, urethanes, and epoxies.
• One-part adhesives
• One-part adhesives harden via a chemical reaction with an external energy source, such
as radiation, heat and moisture.
Types ofAdhesives

Polyurethane adhesives -- these are available as a single pack or two pack
adhesive. These adhesives are strong but are more flexible than epoxies.
Silicone adhesives -- these can be single pack or two pack. Single pack silicone
adhesives are called room temperature vulcanising silicones and they cure by
reacting to the moisture in the air. Two pack silicone adhesives are higher
performing and are good for bonding metal, glass, and ceramics.
Epoxies -- these are made up of a base resin and a hardener. Most epoxies will
set fully at room temperature but some require heat to do so.
Acrylic adhesives -- there are two types of acrylic adhesives – two part acrylic
adhesives or acrylic adhesives that require exposure to UV light in order to
cure fully. Acrylic adhesives are good for creating bonds that have very good
peel strengths as well as good shear and impact strengths.
Cyanoacrylate adhesives -- commonly called superglue, set extremely quickly.
These only require a very small amount to be used in order to achieve strong
bonds.
Anaerobic adhesives -- these are designed to be used in situations where no
oxygen is present. Because they set when no oxygen is present they come in
containers that are designed to “breathe” so that the adhesive cannot set
before it is used.
Types ofAdhesives

Typical measurements include:
• Adhesiveness/Stickiness
(Quick Stick)
• Tackiness
• Cohesiveness
• Shear Strength
• Stringiness/Tailing/
• Legginess
• Extensibility
• Peel strength
• Hardness
1“Stainless
Ball Probe
Loop Tape
Test System
Small Peel
Strength Rig
Large Peel
Strength Rig
Some Test Methods for Adhesives
More details are included in the Appendix

Various types of stresses in a bonded
joint according to the design of the parts

Unlike Polyurethane Sealants which tend to be very low Durometer materials,
polyurethane adhesives run the range from very soft, tacky low Durometer materials (non
structural) to extremely rigid, very high Durometer structural materials.
• Non-structural adhesives - bond decorative materials, such as floor and wall
coverings, and other materials which do not need very high strength (some
panels, fiber and particle boards, trim, some interior doors...
• These adhesives may be emulsion or dispersion adhesives, contact adhesive
and solvent based adhesives,
• Structural adhesives give at least 5 to 8 MPa in tensile shear strength and are
required for structural parts such as bonding of concrete to concrete, ceramic
tiles to concrete, masonry, construction panels, outside doors, sealing metal parts
into concrete, civil engineering, composite bonding (FRP panels), metal bonding,
structural glass...
Based on their outstanding properties, their simple and economical processing and their
high strength, polyurethane adhesives have found broad use in many application areas.
The segments in which polyurethane adhesives are used most are: footwear industry,
construction, woodworking, transportation, packaging and assembly operations.
However, in certain areas of application, such as indirect food contact, approvals for use
need to be obtained from appropriate regulatory authorities.
PolyurethaneAdhesives

Urethane adhesives make good adhesives for a number of reasons:
 They effectively wet the surface of most substrates.
 They can interact with the substrate through polar interactions
(e.g. hydrogen bonding).
 Their relatively low molecular weight/ small molecular size allows
them to permeate porous substrates (for reactive adhesives).
 They can form covalent bonds with substrates that have active
hydrogen atoms (for reactive adhesives).
 Through molecular composition the adhesive stiffness, elasticity
and crosslinking can be tailored to suit specific needs.

The figure illustrates general trends of some adhesive properties
related to temperature or molecular mobility.
Polyurethane Adhesives

Advantages and Disadvantages of
Polyurethane Adhesives
Advantages Disadvantages
Highly versatile chemistry Moisture sensitivity during storage and application
Flexible, tou gh, or rigid formulations available Only average bond strength to metal without a primer
Low surface energy so wets most plastics well
Precise mix ratio required for multi -component
products
Ca be formulated as a one - or two-component
adhesive (single component)
Requires good mixing
Formulations are available with slow to fast curing
times
Short gel times but long ultimate cure time
Good low temperature properties
Maximum temperature of 100 -150C for specialty
formulated polyurethanes
Good environme ntal resistance
Air entrainments and foaming due to CO2 bubbles
can weaken adhesive film
Good chemical, oil resistance below 50C Certain polyols exhibit hydrolytic instability

2008 NAFTAAdhesives Production
CPI - 2009

The choice of starting materials is broader for adhesives than sealants because of
these broader property requirements.
A variety of polyol types with different molecular weight and functionalities can be
used
• Propylene and ethylene oxide polyols are used extensively because of cost, hydrolytic
stability and broad product range
• When higher tensile strength is required the adipic acid or caprolactone based
polyester or PTMEG polyols are used
• If a very hydrophobic adhesive is required, then the polybutadiene polyols are chosen
Crystalline polyester polyols are often the preferred raw materials for adhesive
applications.
• The crystalline polyester polyols (i.e butane or hexanediol adipates) produce adhesive
dispersions with high initial peel strength and excellent plasticizer resistance.
• These dispersions are favored for heat activation bonding applications and show
excellent adhesion to substrates.
Soft, tacky adhesives will use lower functionality (f = 2-3), higher molecular weight
polyols (1000-6000) and relatively low levels (if any) of chain extender.
Hard, structural type adhesives will use higher functionality (3 or >), lower
molecular weight (300- 1000) polyols, even some high functionality acrylic polyol,
higher amounts of either OH or NH2 containing chain extender or cross-linker.
Obviously, adhesives with intermediate property requirements will formulate polyol
and chain extenders somewhere in between the extremes.
Key Raw Materials
- Polyols

Typical Polyol
Structures
Polyether PolyolsPolyester Polyols
(CH2)4 O
(CH2)4
O
OHO-(H2C)4 (
O)X H
Polybutanediol Adipate
O
O
O
O
O
O
O OH
OH
OH
Castor Oil
Castor oil Polyols
H2C
C C
CH2
HC C
CH2H3C CH2 CH
CHH2C
OH
HO
n
0.2 0.2
0.6
Poly Bd Polyol

Polyisocyanate type, functionality and molecular weight
• For most adhesives, either TDI or an MDI variant is the isocyanate of choice
• Aliphatic isocyanates are used if a non yellowing sealant is required (isocyanates not attached to an
aromatic ring)
Either prepolymers or “monomeric” isocyanate are used to produce 2 component adhesives while
only prepolymers are used for 1 component adhesives.
Key Raw Materials –
Polyisocyanates
80/20 TDI
OH + ROCN NCO
ROCN NH
HO
O
O O
O
NH R NCO
ROCN HN
O
O O
O
NH R NH O
O
NH R NCO
O
O
X
ROCN NCO
where x = 1,2,3 ...
perfect product
oligomeric
products
unreacted
free isocyanate
Conventional Prepolymer Process
1 equivalent 2 equivalent
+
+
Depending upon the specific properties
desired, these prepolymers will typically
have a residual -NCO content of 1 – 3%
(% NCO = weight of unreacted –NCO / total
weight of all the constituents in the
prepolymer

Aliphatic isocyanates are used if a non yellowing adhesive is required
(isocyanates not attached to an aromatic ring).
Monomeric isocyanate, or isocyanate adducts are used to produce adhesives.
Key Raw Materials - Polyisocyanates
HDI Trimer
Monomeric aliphatic isocyanates Trimer adduct of HDI

The popularity of solvent free systems has been growing for years. Nevertheless,
solventborne systems are still strongly represented in the manufacture of
laminated films for medium and maximum requirements. The reasons for this
must be understood.
• Solventborne systems can be applied in thicker layers. At layer thicknesses of >3
g/m2, solvent free systems often have poorer optical properties (orange peel).
• Prepolymers with high molecular weight can be used in solventborne adhesives
without causing viscosity problems.
• The solvent also allows the use of higher portions of high viscosity aromatic
polyester diols which lend greater strength to the crosslinking adhesive film.
• Facilitate the use of slow reacting aliphatic isocyanates.
• Any viscosity problems can be corrected by the choice and amount of solvent used.
Solvent-based adhesives cover the widest range of applications, from general
purpose to high performance.
 Their main advantages are strong initial tack and final bond strength with good
flexibility, and good optical properties.
Other Key Components - Solvent
Rhein Chemie – CPI 2010

Fillers are used in structural adhesive formulations to improve properties and to lower
cost. Properties that can be selectively improved include both the processing
properties of the adhesive as well as its performance properties in a cured joint.
The use of fillers can also impair certain properties. Typically, the formulator has to
balance the expected improvements against possible property decline.
The advantages and disadvantages of filler addition is shown below
Other Key Components -Fillers
Advantages Disadvantages
Advantage or Disadvantage (Depending on
Application)
 Lower cost of product
 Reduced shrinkage on curing
 Decreased exothermic temperature on
curing
 Improved tensile-shear strength
 Increased surface hardness
 Improved abrasion resistance
 Improved heat aging properties
 Increased compressive strength
 Increased electrical strength
 Improved toughness if fibrous fillers are
used
 Increased weight
 Increased water absorption (depending
on filler)
 Loss of transparency
 Difficulty in machining hard fillers
 Increased viscosity
 Increased thermal and electrical
conductivity
 Reduced thermal expansion coefficient

Many different types of additives are used in adhesive formulations to
change physical properties
• Tactifiers – A material such as rosin ester added to synthetic
resins or adhesives to improve the initial tack (the property of
a pressure-sensitive adhesive which causes it to adhere to a
surface instantly with a minimum of pressure) of the adhesive
film.
• Thixotropes – things such as bentonite clay (2 conponent only),
microballons or organic coated fumed silica or calcium
carbonate are added to improve leveling and to minimize
penetration of adhesive into absorbant materials
Other Key Components

Primers are also used in conjunction with a surface treatment to improve adhesion
• Isocyanates have been used for over 50 yr as primers on substrates such as rubber, plastic,
fibers and wood by reacting with the polar groups on the surface
• Silane coupling agents are commonly used as primers on glass, fiber composites, mineral-filled
plastics and cementacious surfaces
• They add a new, usually organic, layer at the interface.
• The new layer is generally bifunctional and bonds well to both the substrate and the
adhesive or sealant.
• One end of the molecule is an alkoxysilane that condenses with the silanol groups
on the surface and the other end is amino, mercapto etc. that will react with the
isocyanate moieity in the adhesive.
• The new layer is also very thin so that it provides improved interfacial bonding
characteristics.
• Yet it is not thick enough so that its bulk properties significantly affect the overall
physical characteristics of the joint.
Other Key Components (continued)

Effect of substrate type on silane
adhesion promotion

Ways toApply PolyurethaneAdhesives
Hand Spray Gun

According to IAL Consultants, Europe, the Middle East and Africa
are the most important regions for the production of PUDs,
output in these regions amounts to about 103,000 tons in 2009.
• Despite rising competition from Asian and Latin American sources, these are
still the leading regions for the production of PUDs for leather and textile
applications, with Italy and Turkey being key markets.
• In Europe, there has been a trend towards consolidation in the PUDs
segment.
In the Americas, the emphasis on PUD production is very strongly
geared towards industrial coatings, which account for 43,300
tons out of a total market of 66,900 tons in 2009.
• Leather and textile PUD output tends to be concentrated more in South
America and Mexico.
In the Asia-Pacific region, the balance between leather and
textile applications and industrial coatings is almost equal.
• China is the single most important driving force in this region; but it is fairly
fragmented as an industry,
 China is currently the source of many PUD manufacturing expansion plans for the region.
• The Japanese industry supplies to other parts of Asia, Europe and North
America.
Polyurethane Dispersions
(PUD)

 Applications for PUD’s include, but are not limited to:
 Maintenance coatings, including anti-graffiti.
 Coil coatings
 Wood coatings
 Carpet backing
 Automotive OEM coatings
 Plastic coatings
 Textile and fiber coatings
 Pressure sensitive adhesives
 Flexible packaging adhesives
 Footwear adhesives
 Adhesives for auto interior trim
 Modifier for laminated facings for MDF kitchen units and other furniture
 Fiberglass sizing agent
PUD’s

How are PUD’s Produced?
Hydrophilic or salt forming groups are incorporated into the urethane backbone to
make the polymer self dispersible
Reactive group
that allows for
the incorporation
of the hydrophilic
moiety into
the urethane
polymer
anionic
anionic
cationic
non ionic

Hydrophilic Structures
Characterisation of hydrophilic structures:
nonionic:
 large amounts necessary, often, not chemically bonded, slippery
surfaces,
 polar character remains, ease attack of water
cationic:
 resins bears tertiary amine groups, neutralized with acids.
 After evaporation of acid loss of ionic character of the coating.
Disadvantage: yellowing, weather-ability (tertiary amine). Important
application: CED
anionic:
 resins bear carboxylic groups, neutralized with tertiary amines.
 After evaporation of amine loss of ionic character of the coating.
~Approx. 90 % of all PUD's are anionic !!!!

CASE Chemistry - One Component
Polyurethane Dispersions (PUD) – example
with DMPA
Traditional manufacture of a waterborne polyurethane dispersion

PUD’S
The degree of coalescence and the interpenetration of the polymer chains leading to further
gradual coalescence of the particles are reported to be much higher for typical polyurethane
than for a typical acrylic latex particle.
Critical to the superior film formation are two factors. First is the presence of water within the
particle. Moisture content of the particle plays the roll of plasticizer in that it softens the
particle thus making it easier to coalesce, The second critical factor involves the nano-particle
size of most polyurethane dispersions. During the coalescing process, particles are driven
together by the evaporation of water from the coating. This "hydrostatic vacuum" forces the
particles together the same way evacuating air between two surfaces binds them.

HO OH OCN NCO
CH3
CO2H
CH2OHHOCH2+ +
OCN( NHCO2 O2CNH)x NHCO2CH2
CH3
CH2O2CNH
CO2H
(NHCO2 O2CNH )yNCO
R3N
OCN( NHCO2 O2CNH)x NHCO2CH2
CH3
CH2O2CNH
CO2
-
NHR3
+
(NHCO2 O2CNH )yNCO
H2N-R'-NH2
H(HN-'R-HNOCHN( NHCO2 O2CNH)x NHCO2CH2
CH3
CH2O2CNH
CO2
-
NHR3
+
(NHCO2 O2CNH )yNHCO)zNH-R'-NH2
CASE Chemistry - One Component Polyurethane
Dispersions (PUD) – example with DMPA
•A prepolymer is prepared from polyols (essentially difunctional esters and ethers primarily),
an isocyanate (primarily an aliphatic isocyanate) and DMPA
– The acid group of the DMPA is hindered allowing for almost exclusive reaction of an isocyanate with the 2 hydroxyl groups
– The acid functionality is neutralized with a tertiary amine to form the prepolymer salt
•The prepolymer salt is then chain extended with diamines in water
– The reactivity of isocyanates with amines is so fast that chain extension occurs almost exclusively rather than reaction with
water
– The chain extension reaction is carried out under fairly intensive mixing and the pendant salt groups serve to disperse the
growing polymer chains
– A high molecular weight polyurethane dispersion results

DMPA is a solid and very insoluble in most solvents. (It is very soluble in
N-methyl pyrrolidone a material that may be banned because of it
toxicity).
The salt of DMPA is much more soluble in polyols than DMPA itself.
This broadens the number of suitable solvents for the polyurethane
prepolymer to include acetone.
Using the salt allows one to use the acetone process and leads to
products with no cosolvent.
Materials with high hard segment content will require a coalescing
solvent to make a continuous film; however, the range of acceptable
coalescing solvents is much larger than acceptable PMP process solvents.
• It includes hydroxy functional materials like diethylene glycol
monobutylether (BDG).
The tertiary amine is also a good catalyst for the urethane reaction so
that the prepolymer reaction occurs much faster. This makes the
manufacturing process more efficient.
PUD’s - DMPASolubility

Acrylic Urethane Hybrid Dispersions
• Dispersions of PUD’s and acrylic dispersions can be produced by three
different processes.
1. Straight blending of a PUD and a acrylic dispersion.
2. Type 1 Hybrid Dispersion: A PUD is first formed, acrylic monomers are added then
polymerized in the presence of the PUD.
3. Type 2 Hybrid Dispersion : A polyurethane prepolymer is formed, the acrylic
monomers are added to the prepolymer, the mixture is dispersed in water and the
urethane and acrylic polymerizations are completed concurrently.
Air Products Bulletin

•The urethane acrylic hybrids exhibit
improved molecular compatibility
verses the simple blending as seen in
the DMA.
•The simple blend shows 2 distinct tan
δ peaks (separate glass transition
temperatures of each polymer).
•The type 1 hybrid shows 2 TG’s but
the peaks are broader indicative of
some molecular mixing.
•The type 2 hybrid exhibits only one
very broad tan δ peak, consistent with
an IPN. Air Products Bulletin

•The rational of the hybrids is to improve performance and this is seen below for
the tensile strength.
The tensile strength of
The type 2 hybrid is the
Same as the base urethane
This process appears to result in acrylic and polyurethane chains which are intimately mixed at the molecular level and
presumably held together with numerous entanglements and secondary intermolecular bonding forces.
Air Products Bulletin

Journal of Coatings Technology 68 (1996)

Acrylic Urethane
Hybrid Dispersions
Journal of Coatings Technology 68 (1996)
In many cases, this allows a compromise between the superior performance properties
of the polyurethane and the lower cost of the acrylic. Typically, standard Polyurethane/
Acrylic Hybrid Dispersions have an average particle size higher than PUD’s and are
in the range of 75 to 120 nanometres with the appearance exhibiting the expected
milky white color.

Although 1K waterborne urethanes are used extensively
for markets such as textile leather coatings and a variety
of adhesives, typically, the properties are not used in the
high performance markets.
The original one component PUD technology can be
improved via cross-linking.
.
One Component Polyurethane
Dispersions (PUD)

Non Reactive – either through solvent or water evaporation or
cooling, a polymer film is deposited between the two substrates to
be bonded.
• No chemical reaction takes place
• All are one component systems
Types of Non Reactive Adhesives
• Solvent – Borne Adhesives
• High mol wt OH terminated polyurethane (mol wt ~ 100,000)
• The polymer solutions are applied to both surfaces to be bonded. Some time is allowed for the
solvents to evaporate and the surfaces are then pressed together, at which point interdiffusion of
the polymer chains will occur.
• Hot Melt Adhesives
• High mol wt OH terminated polyurethane
• most commonly applied as adhesive film in lamination type of applications. These adhesives form
the adhesive bond by cooling from the molten state.
• Polyurethane Dispersions (PUD)
• High Molecular weight urethane amine chain extended and dispersed in water
• The water carrier is eliminated during use, leaving the precipitated and coalesced polymer to form
the adhesive bond
PolyurethaneAdhesives can be
classified as Non Reactive or Reactive

Reactive – a chemical reaction takes place on the
interface between the surfaces to be bonded
Types of Reactive Adhesives
• Two Component Adhesives
• Conventional –NCO and –OH reaction to cure (both solvent and water based).
• One component polyurethane dispersions cured with added cross-linkers
• Dispersable isocyanates
• Polyfunctional aziridines
• Polyfunctional carbodiimides
• Epoxies and epoxy silanes
• One Component Adhesives
• Moisture cure (typically a “low” molecular weight prepolymer)
• UV Curable Hybrid Adhesive
• Blocked Isocyanate / -OH, -NH2 functional resin
• Hybrid – SPUR and MS Polymer
• Reactive Hot Melt Adhesives
• Highly viscous or solid prepolymers (low free NCO) with a low melting point
(generally from crystalline polyester polyols)
• Latent Reactive Polyurethane Adhesives
can be classified as Non Reactive
or Reactive

The non reactive adhesives are all linear (no cross-links) polymers with
relatively high molecular weights
Solvent Borne
• By necessity the solvent borne versions will be relatively low solids to have a
workable viscosity with the high molecular weight thermoplastic urethane.
• high solvent level (VOC) creates environmental issues
• evaporation requirements of high levels of solvent limit the potential applications
• not a growing area for polyurethane adhesives and there will be no detailed
discussion.
Hot Melt
• Structurally similar to the solvent borne versions, they are applied hot, in the
melted state, and rely on the inherent polymer strength upon cooling and Van
Der Waals interaction with the substrates to achieve its adhesive properties.
• need special applicators to apply adhesive, but other hot melt adhesives need the
same equipment.
• urethanes relatively expensive compared to other hot melt polymers.
• not a major polyurethane application area.
Non Reactive PolyurethaneAdhesives

– Hot Melt

In elastomeric polyurethanes (TPUs) the crystalline fraction of the polymer is formed
by the hard segments.
There is a peculiar type of polyurethanes in which the hard segment content is very
low and the long-chain diol is very crystalline and therefore their crystalline fraction is
formed by the soft segments instead of the hard segments.
These polyurethanes are white and crystalline at room temperature and when the soft
segments melt, their modulus decreases dramatically, acquiring adhesive properties.
Therefore they are used as high performance adhesives.
Only polycaprolactone and polyester are used in these crystalline polyurethanes
because of the low crystallinity of polyethers.
– Hot Melt
Merquinsa literature

– Hot Melt
•Crystallization strongly influences adhesive
performance of polyurethane hot melt adhesives
– Slow crystallizing polyurethanes allow the
formation of adhesives with optimum tack
properties
– Fast crystallizing polyurethanes allow for fast
setting bonds
Bayer paper

Polyurethane Dispersions
• PUD’s are available in higher solids than the solvent borne urethanes,
and possess a different range of properties because of the polyurea
content of the polymer.
- environmentally more friendly than solvent based adhesives
- non flammable
- longer drying times than solvent based.
- useful on substrates sensitive to solvents
• PUD’s are more expensive than the solvent borne systems since the
more expensive aliphatic isocyanates are used almost exclusively to
prepare these dispersions.
• PUD’s can be blended with other dispersion polymers such as acrylics
to reduce cost and modify properties.
• Since conventional non reactive PUD’s are not cross-linked, some of
the properties are deficient compared to the reactive polyurethane
systems.
- PUD

Typical performance characteristics of aqueous
polyurethane dispersions are:
• High initial and final bond strength
• Good resistance to moisture and plasticizers
• Good adhesion to difficult to bond substrates
• Ability to blend with other aqueous systems
• Good heat resistance
• Ease of application via wet bonding or heat activation process
• Heat activation at low temperature

Drying and film formation of a PUD
Bayer paper

Monomers such as methyl methacrylate are added to a reactor containing
the aqueous polyurethane and given time to swell.
Any dispersion agents needed are then added, followed by a catalyst to
initiate the polymerization.
Chemical reaction between the two different polymer types in a
polyurethane hybrid produces tough, chemically resistant adhesives.
The radical reaction used in the emulsion polymerisation process provides
a basic level of grafting between the two via hydrogen abstraction.
Hybrid adhesive makers have extended this concept by adding further
chemical functionality to the polyurethane prepolymer that plays a more
active role in the radical polymerisation.
They do this by adding chain extenders with unsaturated groups that
participate in the radical reaction, such as polyethylene glycol
methacrylates.
PolyurethaneAcrylic Hybrid
Dispersion

Dispersion
Polyethyleneglycol
Methacrylate Polyurethane prepolymer

Among the patented uses for hybrid systems are binders in adhesives, and
heat-seal adhesives in lamination applications. For heat-seal lamination the
adhesive is applied to a substrate, dried, applied, attached to a second
substrate and heated to form the final seal.
Dispersion
Impact of polyurethane : acrylate ratio on
performance of heat seal

Reactive Two Component Adhesives
• The adhesion process is the same as
the one component system however,
mixing the two components together
initiates the reaction.
• Monomeric or oligomeric (prepolymer)
A and B sides are used.
• The reaction only starts when the two
components have been mixed.
Reactive PolyurethaneAdhesives
•Reactive One Component Adhesives
– Are applied to one of the two substrates
without any prior mixing.
– The other substrate is then pressed onto the
applied adhesive for pre determined press
time.
– After this time the two substrates will be
bonded.
– The speed at which the reaction occurs can
be varied to suit the requirements of a
specific manufacturing process.
Rhein Chemie - Utech 2009

Two Component Solvented Adhesives
• Basically the reaction of an A side isocyanate with a B side polyol
• Solvent added to reduce the viscosity and facilitate the application
• typically with a solids content of 40 % or 55%
• the adhesive is sprayed onto one substrate which is to be bonded.
• This is useful for high speed continuous lamination lines as the two
substrates need only be nip rolled.
• Substrates typically bonded are textiles, foam and scrim.
• Advantages
• Batch pressing is not required.
• A soft flexible bond line is produced.
• High speed production lines are possible.

Two Component Polyurethane Dispersions
• The property deficiencies (heat, solvent, water resistance and even
bond strength) of uncross-linked PUD’s can be minimized by using the
cross-linkers
- Dispersable isocyanates
- Polyfunctional aziridines
- Polyfunctional carbodiimides
• PUD’s may have pendant carboxyl groups, residual OH and NH groups,
and prior to the deposition of the dispersion upon the substrate, a
cross-linker can be added.
– cross-linking occurs on the substrate
– aziridines and carbodiimides react primarily with acid groups
– the dispersable isocyanates react primarily with OH or NH groups
• The cross-linkers now make these two component reactive adhesive
systems

Cross-linkable PUD’s
Dispersible Isocyanates
(CH2)6NCO
N
N
N
O
O O
N O
O
H
(CH2CH2O)n CH3
n = 6 to 9
(CH2)6NCO
Dispersible Isocyanate Desmodur DA
(A hydrophilically modified HDI trimer)
Cross-linked PUDs
+

Cross-linkable PUD’s
PolyfunctionalAziridine
Bayer Polyfunctional Aziridine XAMA 7
Increases cohesive strength
Faster cure time
Improves adhesion to difficult substrate
The addition level for most applications is 1-3% based on resin solids.
Higher levels (5%) may yield higher solvent resistence and adhesive properties..
Optimun results occur when the pH = 9.0-9.5. A lower pH may cause the aziridine to react
Prematurely in the pot.

Cross-linkable PUD’s Polycarbodiimide
Picassian
Brochure

Additionally carbodiimides are recognized to improve the hydrolytic
stability of many polymers like polyester polyol based polyurethanes.
The service life of a hydrolysis sensitive polymer containing a
hydrolysis stabilizer such as a carbodiimide can be prolonged up to
three times longer than unprotected products.
Carbodiimides act as acid and water scavengers. The reaction with
acids is highly preferred. Through these reactions they convert and
neutralize both water and acids into non-hazardous urea structures.
Cross-linkable PUD’s -
Polycarbodiimide
Rhein Chemie CPI 2010

Polyisocyanate cross-linkers are recommended for use at a level of 1-5%
based on the dispersion (40-60% solids).
The polyisocyanates are dispersed in the aqueous polymer with rapid stirring.
The following process is used to disperse the polyisocyanate.
• Add polyurethane dispersion to mixing vessel
• Start stirrer apparatus with the necessary stirring speed
• Add polyisocyanate portion-wise
• Stir until a homogeneous mixture is achieved (at least 5-10 minutes)
The typical improvements achieved upon using these polyisocyanate cross-
linkers are listed below.
• Improved initial bond strength
• Better cohesion strength
• Higher heat resistance (softening temperature)
• Better resistance to solvents, plasticizers, oil and grease
• Better resistance to hydrolysis and chemical degradation
Cross-linkable PUD’s – Dispersible Isocyanate

Bayer paper
Improvement in Heat and
Hydrolysis Resistance

There are three types of reactive one component adhesives.
• Solvated – Because of VOC issues, this segment is shrinking at
the expense of PUD’s and 100% solids systems
• Non-solvated
• Water borne latent reactive
These adhesives are used for manufacturing Insulated panels, Plastic
Doors, Roofing, Architectural Panels, Pan Scourers, Raised Access
Flooring, Caravans and Textile Lamination.
One Component

Non-solvented Adhesives
These adhesives are solvent free and can be applied in many different ways such
as by spraying (automatic or manual), hand roller coating or bead.
Advantages
• One component, no mixing.
• The lack of solvent minimizes the environmental impact.
• The adhesives can be spray applied which is very fast.
• The adhesive gives excellent penetration into porous surfaces and can be used to
gap fill behind the bond line.
Types
• Moisture Cure Adhesives
• UV Curable
• Blocked isocyanate
• Silicon modified polyurethane (polyethers) were discussed in the sealant section and
will not be covered here.
• Hot Melt Polyurethane Adhesives (HMPUR) are non-solvented one component
moisture cure systems
• unlike the earlier types of moisture cure systems, these are higher molecular weight
polymers
• inherently have sufficient physical properties that they are applied hot to a substrate
• they solidify almost immediately and have reasonable initial strength
Reactive PolyurethaneAdhesives -
One Component

Dow web seminar
Reactive Polyurethane Adhesives
One Component – Moisture Cure

Dow Voractiv Polyols
Catalytic tertiary amine
catalyst built into the
Backbone of the polyol
O
CH3
+
tertiary amine triol starter
propylene
oxide
H O
CH3 CH3
O H
x y
CH3
O H
z
Voractiv Triol
HO-R
C
R-OH
R-OH
N(CH3)3
O-R
C
R-O
R-O
N(CH3)2

+ O=C=N-R-N=C=O
CO-N-R-N=C=OO=C=N-R-N-CO
CO-N-R-N=C=O
Echelon Prepolymer
Voractiv Polyol MDI
Reactive Polyurethane Adhesives
One Component – Moisture Cure

Example: Reactive Polyurethane Adhesives

ArmorThane Pu 104 a polyurethane sealants, adhesives, and binders

ArmorThane Pu 104 a polyurethane sealants, adhesives, and binders

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