A two-part adhesive composition useful for bonding various materials including plastic or thermoplastic substrates. The first part of the adhesive contains an epoxy compound and an acrylate-terminated polyurethane while the second part of the adhesive contains an amine hardener. The presence of the acrylate-terminated polyurethane allows the adhesive composition to be applied to unprepared substrates to form a bond having high strength.

FIELD OF THE INVENTION 
The present invention relates to structural adhesive compositions useful 
for bonding various substrates. More particularly, the present invention 
relates to two-part epoxy adhesive compositions which contain an 
acrylate-terminated polyurethane and which can be utilized to form 
high-strength, flexible bonds with a variety of unprepared substrates. 
BACKGROUND OF THE INVENTION 
The utilization of plastic and thermoplastic substrates in various 
industries typically requires the use of curable adhesive compositions to 
affix or bond the substrate to another structural component. The bond 
formed between the plastic or thermoplastic substrate and the structural 
component must meet certain requirements of adhesive strength depending on 
the particular application. One example of an industrial utilization of 
plastic substrates involves the use of rigid fiber-reinforced plastic 
composite materials in the form of sheet molding compound (SMC) in the 
automobile industry as an alternative to steel automotive body panels in 
an effort to reduce weight and corrosion susceptibility of an automobile, 
van, truck or the like. Sheet molding compound is typically comprised of 
various resin compositions such as a polyester resin reinforced with, for 
example, glass fibers. The sheet molding compound is molded under heat and 
pressure in order to prepare a rigid, self-supporting, fiber-reinforced 
structure. 
One example of an adhesive composition which has previously been described 
as being useful for bonding sheet molding compounds and other substrates 
is disclosed in U.S. Pat. No. 4,578,424. The adhesive is a two-component 
adhesive wherein the first component of the adhesive contains an epoxy 
resin and an additive selected from the group consisting of a 
polyisocyanate, a carboxylic anhydride, and molecules with unsaturated 
carbon-carbon bonds capable of undergoing Michael addition reaction with 
amines. The second component of the adhesive is a hardener component for 
curing the first component and contains a mixture of amido amines, primary 
and secondary amines having tertiary amine groups or ether groups in their 
backbone, and bis-phenol A. Maleic or fumeric groups are given as examples 
of molecules with unsaturated carbon-carbon bonds capable of undergoing 
Michael addition reaction with amines. 
Another adhesive composition previously described in the patent literature 
as being useful for bonding sheet molding compounds and other substrates 
is described in U.S. Pat. No. 4,803,232. This adhesive composition is a 
two-component system wherein the first component contains an epoxy resin 
and an acrylate or methacrylate ester of an aliphatic polyhydric alcohol. 
The second component of the adhesive composition contains an 
amine-terminal butadiene-acrylonitrile rubber, at least one aliphatic or 
aromatic polyamine, and at least one polyamido-amine. 
Previously developed structural adhesive compositions such as those 
described above are more effective when the surface of the substrate to be 
bonded is specially prepared prior to application and curing of the 
adhesive. Typical surface preparation techniques involve solvent wiping, 
abrading or priming, all of which can be cumbersome, expensive and 
time-consuming. Another disadvantage associated with many traditional 
structural adhesive compositions is that they often require the addition 
of a rubber component, such as a carboxylic acid group- or amine 
group-terminated butadiene/acrylonitrile copolymer rubber, to the epoxy 
resin in order to impart needed flexibility to the resulting bond. 
Furthermore, many structural adhesives lack versatility in that they can 
only be utilized to bond a specific type of substrate. 
A need therefore exists for a structural adhesive composition that can be 
applied to a variety of unprepared substrates so as to produce a flexible 
adhesive bond without the need for an additional rubber component. It 
would also be desirable for such an adhesive composition to cure at a 
reasonably rapid rate and to produce a bond which exhibits a high degree 
of strength. 
SUMMARY OF THE INVENTION 
The present invention is a structural adhesive composition that can be 
bonded to unprepared substrates so as to form, at a high cure rate, a 
flexible adhesive bond that exhibits high strength. The present invention 
is based on the discovery that the utilization of certain 
acrylate-terminated polyurethanes in a two-part adhesive composition 
results in enhanced bonding activity which allows the adhesive composition 
to be applied to unprepared substrates. Specifically, the present 
invention relates to a two-part adhesive composition comprising a 
Component A and a Component B, wherein Component A comprises an epoxy 
compound and an acrylate-terminated polyurethane and Component B comprises 
an amine hardener.

DETAILED DESCRIPTION OF THE INVENTION 
Component A of the present invention comprises an epoxy compound and an 
acrylate-terminated polyurethane. The epoxy compound of the invention can 
be any monomeric or polymeric compound or mixtures of compounds having an 
epoxy equivalency greater than one, that is, wherein the average number of 
epoxy groups per molecule is greater than one, with monomeric epoxides 
having two epoxy groups being currently preferred. Epoxy compounds are 
well known and are described in, for example, U.S. Pat. Nos. 2,467,171; 
2,615,007; 2,716,123; 3,030,336; and 3,053,855 which are incorporated 
herein by reference. Useful epoxy compounds include the polyglycidyl 
ethers of polyhydric polyols, such as ethylene glycol, triethylene glycol, 
1,2-propylene glycol, 1,5-pentanediol, 1,2,6-hexanetriol, glycerol and 
2,2-bis(4-hydroxy cyclohexyl) propane; the polyglycidyl esters of 
aliphatic or aromatic polycarboxylic acids, such as oxalic acid, succinic 
acid, glutaric acid, terephthalic acid, 2,6-naphthalene dicarboxylic acid 
and dimerized linoleic acid; the polyglycidyl ethers of polyphenols, such 
as 2,2-bis(4-hydroxyphenyl) propane (commonly known as bis-phenol A), 
1,1-bis(4-hydroxyphenyl) ethane, 1,1-bis(4-hydroxyphenyl) isobutane, 
4,4'-dihydroxybenzophenone, 2,2-bis(4-hydroxyphenyl) butane, 
bis(2-dihydroxynaphthyl) methane, phloroglucinol, bis(4-hydroxyphenyl) 
sulfone, 1,5-dihydroxynaphthalene, and novolak resins; with the 
polyglycidyl ethers of polyphenols being currently preferred. Generally 
the preferred epoxy compounds are resins having an epoxide equivalent 
weight of about 100 to 2000, preferably about 110 to 500. The presently 
preferred epoxy compound is a polyglycidyl ether of a polyphenol, such as 
the polyglycidyl ether of bis-phenol A supplied by Shell Chemical Company 
under the trade name EPON 828. The epoxy compound is utilized in an amount 
ranging from about 5 to 80, preferably from about 20 to 60, percent by 
weight of the essential components of Component A. The essential 
components of Component A herein refer to the epoxy compound and the 
acrylate-terminated polyurethane. 
The acrylate-terminated polyurethanes of the present invention comprise the 
reaction product of at least one polyisocyanate, at least one monomeric or 
polymeric organic compound characterized by the presence of at least two 
isocyanate-reactive active hydrogen, and at least one acrylate compound. 
While the acrylate-terminated polyurethanes of the present invention can 
be prepared by any one of several known reaction routes, the polyurethanes 
of the present invention are typically prepared by reacting an excess of a 
polyisocyanate with an acrylate compound to form an NCO-functional 
acrylate/isocyanate prepolymer which is then reacted with an active 
hydrogen-containing material to form the final acrylate-terminated 
polyurethane. 
The polyisocyanates which can be employed in forming the 
acrylate-terminated polyurethanes in accordance with the present invention 
can be any organic isocyanate compound having at least two isocyanate 
groups, including mixtures of such compounds. Included within the purview 
of suitable polyisocyanates are aliphatic, cycloaliphatic, and aromatic 
polyisocyanates, as these terms are generally interpreted in the art. Thus 
it will be appreciated that any of the known polyisocyanates such as alkyl 
and alkylene polyisocyanates, cycloalkyl and cycloalkylene 
polyisocyanates, aryl and arylene polyisocyanates, and combinations such 
as alkylene, cycloalkylene and alkylene arylene polyisocyanates, can be 
employed in the practice of the present invention. 
Suitable polyisocyanates for purposes of the present invention include, 
without limitation, toluene-2,4-diisocyanate, 
4,4'-methylene-bis(cyclohexyl isocyanate), polymethylene polyphenylene 
isocyanate, 2,2,4-trimethylhexamethylene-1,6-diisocyanate, 
hexamethylene-1,6-diisocyanate, diphenylmethane-4,4'-diisocyanate, 
triphenyl-methane-4,4',4"-triisocyanate, m-phenylene diisocyanate, 
p-phenylene diisocyanate, 2,6-toluene diisocyanate, 1,5-naphthalene 
diisocyanate, naphthalene-1,4-diisocyanate, diphenylene-4,4'-diisocyanate, 
3,3'-bi-toluene-4,4'-diisocyanate, 1,4-cyclohexylene dimethylene 
diisocyanate, xylene-1,4-diisocyanate, xylene-1,3-diisocyanate, 
cyclohexyl-1,4-diisocyanate, 
3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, isophorone diisocyanate, 
m-tetramethyl xylene diisocyanate, the product obtained by reacting 
trimethylol propane and 2,4-toluene diisocyanate in a molar ratio of 1:3, 
and the like. It is presently preferred to use toluene-2,4-diisocyanate, 
4,4'-methylene-bis(cyclohexyl isocyanate), or polymethylene polyphenylene 
isocyanate as the polyisocyanate of the invention. The polyisocyanate is 
utilized in an amount ranging from about 15 to 40, preferably from about 
20 to 30, percent by weight of the total ingredients utilized to prepare 
the acrylate-terminated polyurethane. 
The active hydrogen-containing materials can be essentially any of the 
known polymeric materials having two or more isocyanate-reactive active 
hydrogen groups selected from hydroxyl, primary amine, secondary amine and 
mixtures of such groups. The active hydrogen groups are preferably 
hydroxyl or secondary amine groups. Suitable active hydrogen-containing 
polymeric compounds include polyether polyols such as polyethylene glycol, 
polypropylene glycol and polytetramethylene glycol; hydroxy-terminated 
polyalkylene esters of aliphatic, cycloaliphatic and aromatic diacids; 
esters of polyhydric alcohols and hydroxylated fatty acid resins; 
hydroxyl-terminated polybutadiene resins; hydroxylated acrylic and 
substituted acrylic resins, hydroxyl-terminated vinyl resins, and 
polycaprolactones. Generally, polymeric materials having two active 
hydrogen groups are preferred. 
Polyester polyols are useful as the active hydrogen-containing materials of 
the present invention. Typical polyester polyols useful in the invention 
include those formed by the reaction of lactones or carboxylic acids with 
multi-functional hydroxy compounds. The carboxylic acid-based polyester 
polyols of the invention can be prepared according to methods known in the 
art by reacting carboxylic acids such as succinic acid, adipic acid, 
suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid 
or terephthalic acid with multi-functional hydroxy compounds such as 
ethylene glycol, diethylene glycol, 1,4-butane diol, 1,3-propane diol, 
1,6-hexane diol, trimethylol propane, glycerol, erythritol, 
pentaerythritol, poly(ethylene oxide) diol, poly(ethylene oxide/propylene 
oxide) diol and poly(tetra-methylene oxide) diol in various combinations 
well known in the art. Presently preferred carboxylic acid-based polyester 
polyols include 1,6-hexane diol-isophthalate diol, 1,6-hexane dioladipate 
diol, 1,6-hexane diol-ethylene glycol-adipate diol, and mixtures thereof. 
The present lactone-based polyester polyols are prepared according to 
methods known in the art by reacting a lactone such as caprolactone with a 
multi-functional hydroxy compound as defined immediately above. A 
particularly preferred lactone-based polyester polyol is a 
polycaprolactone triol prepared from the reaction of caprolactone and 
trimethylol propane. The molecular weight of the polyester polyol is 
typically in the range from about 250 to 3000, preferably from about 350 
to 1000. 
Presently most preferred for use in the present invention are poly(alkylene 
oxide) polyols. The poly(alkylene oxide) polyols are normally obtained 
from the polymerization, including block copolymerization, of cyclic 
ethers such as alkylene oxides, dioxolane and tetrahydrofuran, the 
condensation of glycols, or the condensation of cyclic ethers with 
glycols. They are well-known articles of commerce, and are also called 
polyalkylene ether glycols, polyalkylene glycols, polyalkylene oxide 
glycols, polyglycols and polyoxyalkylene glycols. They may be represented 
by the formula HO(RO).sub.n H, in which R is an alkylene radical and n is 
at least 2. The alkylene radical can be a single chain or can consist of 
two or more alkylene chains separated from each other by an ether oxygen 
atom. Preferred poly(alkylene oxide) polyols have from 1 to 9, preferably 
1 to 6, carbon atoms in the alkylene chain separating each pair of oxygen 
atoms and have a number average molecular weight in the range of from 
about 100 to about 4,000, preferably about 100 to about 2,500. Not all the 
alkylene units need be the same. Poly(alkylene oxide) polyols formed by 
the copolymerization or condensation of mixtures of different cyclic 
ethers, glycols, or glycols and cyclic ethers can be used; as can 
poly(alkylene oxide) polyols derived from cyclic ethers such as dioxolane, 
which affords a polyol having the formula HO(CH.sub.2 OCH.sub.2 CH.sub.2 
O).sub.n H, where n is greater than 1. The alkylene unit can be a straight 
or a branched chain, as in poly(propylene oxide) polyol. In the case where 
the alkylene unit is ethylene, it can be advantageous to incorporate the 
unit into a copolymer, for example, as a copolymer of ethylene oxide and 
propylene oxide, with up to 80 percent of such copolymer comprising 
ethylene oxide. The number of hydroxyl groups of the poly(alkylene oxide) 
polyols depends on the functionality of the glycol utilized to prepare the 
polyol. For example, difunctional and trifunctional glycols result in 
poly(alkylene oxide) diols and triols, respectively, and so forth for 
glycols with higher functionality. Thus, the poly(alkylene oxide) polyols 
will generally have from 2 to 6 hydroxyl groups, with such polyols having 
2 hydroxyl groups being currently preferred. 
Representative poly(alkylene oxide) polyols for use in the present 
invention include poly(ethylene oxide) polyols, poly(propylene oxide) 
polyols, poly(tetramethylene oxide) polyols, poly(nonamethylene oxide) 
polyols, poly(oxymethylene-ethylene oxide) polyols, poly(ethylene 
oxide-propylene oxide copolymer) polyols, and 
poly(pentaerythritol-ethylene oxide) polyols. Preferred poly(alkylene 
oxide) polyols are poly(propylene oxide) polyols, poly(tetramethylene 
oxide) polyols, poly(ethylene oxide-propylene oxide) polyols, and 
poly(ethylene oxide) polyols, with poly(propylene oxide) diol and 
poly(tetramethylene oxide) diol being most preferred. 
Mixtures of active hydrogen-containing materials such as a combination of 
polyester polyols and poly(alkylene oxide) polyols may also be employed in 
the present invention. A preferred combination comprises poly(propylene 
oxide) diol, and 1,6-hexane diol/isophthalate-diol-type polyester polyols 
in a ratio of former to latter ranging from about 1:3 to 1:4. The active 
hydrogen-containing material or mixture thereof is utilized in an amount 
ranging from about 10 to 90, preferably from about 20 or 70, percent by 
weight of the total ingredients utilized to prepare the 
acrylate-terminated polyurethane. 
The acrylate compounds utilized to prepare the acrylate-terminated 
polyurethanes of the present invention can be essentially any organic 
compound containing an acrylate moiety and containing a single 
isocyanate-reactive active hydrogen-containing group such as hydroxyl, 
primary amine or secondary amine. Typical acrylate compounds useful in the 
present invention include, without limitation, 2-hydroxyethyl acrylate, 
2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, 4-hydroxybutyl 
acrylate, 8-hydroxyoctyl acrylate, 12-hydroxydodecanyl acrylate, 
6-hydroxyhexyl oleate, diethylene glycol monoacrylate, hydroxy neopentyl 
acrylate, hydroxyneopentyl linoleate, hydroxyethyl-3-cinnamyloyloxypropyl 
acrylate, hydroxyethyl vinyl ether, allyl alcohol, mixtures thereof and 
the like. Acrylate-lactone adducts may also be utilized as the acrylate 
compound of the invention. An example of an acrylate-lactone adduct 
preferred for use in the invention is a 2-hydroxyethyl 
acrylate-caprolactone adduct such as TONE M-100 supplied by Union Carbide 
Corporation. It is presently preferred to utilize 2-hydroxyethyl acrylate, 
2-hydroxypropyl acrylate, or a mixture of 2-hydroxyethyl acrylate and a 
2-hydroxyethyl acrylate-caprolactone adduct as the acrylate compound of 
the invention. The acrylate compound or mixture of compounds is typically 
utilized in an amount ranging from about 5 to 70, preferably from about 10 
to 50, percent by weight of the total ingredients utilized to prepare the 
acrylate-terminated polyurethane. 
As indicated above, it is preferred to prepare the present 
acrylate-terminated polyurethanes by forming an isocyanate/acrylate 
prepolymer which is then reacted with an active hydrogen-containing 
compound such as a polyol to form the final polyurethane. Both of these 
reactions are typically carried out at temperatures ranging from about 
50.degree. C. to 90.degree. C. In forming the acrylate-terminated 
polyurethanes according to this invention, the polyisocyanate compounds 
are employed in an amount sufficient to afford an NCO:OH ratio, with 
respect to the amount of active hydrogen-containing material in excess of 
2:1, and preferably in the range of 2.5-5:1. The amount of acrylate 
compound characterized by the presence of a single isocyanate-reactive 
active hydrogen group will be sufficient to react with at least one 
unreacted isocyanate group, and is preferably an amount sufficient to 
afford an active hydrogen group:NCO ratio, with respect to the amount of 
excess polyisocyanate, of at least 1:1, with a slight excess of active 
hydrogen being presently preferred. 
The acrylate-terminated polyurethane is utilized in an amount ranging from 
about 5 to 95, preferably from about 40 to 80, percent by weight of the 
essential components of Component A. 
Component B of the present invention is an amine hardener which acts as a 
curing agent for the adhesive of the present invention. Component B can 
essentially be any amine or amide compound, or combination of such 
compounds including polyamidoamines, aliphatic polyamines, alicyclic 
polyamines, aromatic polyamines, and tertiary amines. Of the amine 
compounds useful in the present invention, aliphatic polyamines are 
preferred and contain at least two, preferably two to five, primary or 
secondary amine groups. Examples of such amines are polyalkylene 
polyamines, e.g. diethylene triamine, triethylene tetramine, tetraethylene 
pentamine, pentaethylene hexamine, ethylene diamine, tetramethyl diamine, 
hexamethylene diamine, polyether diamine, bis-hexamethylene triamine, 
diethylamino-propylene triamine, trimethylhexamethylene diamine, 
oleylamine, di-propylene triamine, 1,3,6-tris-aminomethyl-hexane, 
3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxaspiro-(5,5)-undecane, 
1,3-bis-aminomethyl-cyclohexane, bis(4-aminocyclohexyl)methane, 
bis(4-amino-3-methylcyclohexyl)-methane, isophorone diamine, 
N-aminoethyl-piperazine, menthene diamine, diaminophenylmethane, 
anilineformaldehyde low molecular weight condensate, m-phenylene diamine, 
diaminodiphenyl-sulfone, dimethylaminomethylphenol, 
tris(dimethyl)aminoethyl-phenol and the like, with diethylene triamine, 
triethylene teramine and tetraethylene pentamine being presently 
preferred. Aromatic polyamines wherein the amine groups are directly 
attached to the aromatic ring, such as xylene diamine and the like, can 
also be used in the practice of the invention but are less preferred to 
their aliphatic counterparts. 
The amide compounds which can be used in the amine hardener of the present 
invention are preferably polyamide or polyamidoamine compounds prepared by 
reacting aliphatic amines with dimerized fatty acids of 12 to 28 carbon 
atoms or other dicarboxylic acids as is known in the art. The polyamide 
and polyamidoamine compounds useful in the present invention are well 
known and commercially available. For example, a polyamide of dimerized 
linoleic acid preferred for use in the present invention is supplied by 
Henkel USA under the trade name VERSAMID 140. 
Component B of the present invention preferably comprises a mixture of an 
aliphatic primary polyamine and a polyamide in a ratio of amine 
functionality to amide functionality ranging from about 1:3 to 1:5. 
Specifically, it is presently preferred to utilize triethylene tetramine 
in combination with a polyamide such as VERSAMID 140. 
When it is desired to enhance the non-sag characteristics of the adhesive 
compositions of the invention the compositions may optionally include a 
mixture of a polyol and activated silica such as fumed silica or colloidal 
silica. The activated silica is believed to combine with the polyol via 
hydrogen-bonding to provide the thixotropic properties necessary to 
enhance non-sag characteristics of the adhesive composition. 
The polyols that may be included in combination with the activated silica 
can be any of the poly(alkylene oxide) polyols described above with 
respect to the active hydrogen-containing materials utilized in preparing 
the present acrylate-terminated polyurethanes. The poly(alkylene oxide) 
polyols will generally have from 2 to 6 hydroxyl groups, with polyols 
having 2 hydroxyl groups being currently preferred. Particularly preferred 
are poly(ethylene oxide) diols such as diethylene glycol. 
When employed, the mixture of activated silica and polyol generally form 
part of Component A. The polyol and the activated silica are usually added 
in respective amounts of about 1.0 to 5.0 parts per 100 parts by weight of 
Component A. 
Although optional, it is preferred to include along with the amine hardener 
a hydroxy, ring-substituted, aromatic hydrocarbon such as phenol, 
polyphenol or the like so as to increase the cure rate of the epoxy 
adhesive as is known in the art. When employed, the hydroxy-substituted 
aromatic compound is utilized in an amount ranging from about 5 to 25, 
preferably from about 8 to 15, parts by weight per 100 parts by weight of 
Component B. 
The adhesive compositions of the invention can also contain conventional 
additives normally found in epoxy adhesives, such as talc, metal powders, 
titanium dioxide, wetting agents, and the like. Such additives are 
incorporated in current ratios well known to practitioners in the art of 
epoxy adhesives. 
In production, the adhesives are provided as two-part compositions, i.e., a 
Component A and a Component B. The parts are metered and mixed together 
immediately before use in a weight ratio of Component A:Component B 
ranging from about 0.5:1 to 10:1, preferably from about 0.8:1 to 2:1. 
After mixing, the adhesive is sufficiently viscous to form a discrete bead 
when extruded onto a surface and has a pot life of at least 30 minutes at 
ambient temperature. The adhesives are curable at ambient temperatures but 
are preferably cured at temperatures in the range from about 70.degree. C. 
to 190.degree. C. at which temperature cure is effected within a time 
period ranging from about 1 minute to 1 hour, typically from about 5 
minutes to 40 minutes, depending on temperature. 
Although capable of bonding any substrate or surface capable of receiving 
an adhesive, the adhesives of this invention are especially suited to 
bonding fiber reinforced unsaturated resin sheet molding compound (SMC) 
parts to other SMC parts or metals. The present adhesive compositions also 
exhibit an affinity for a surprisingly large variety of thermoplastic 
substrates such as acrylonitrile-butadiene-styrene, polybutylene 
terephthalate-modified polycarbonate, polycarbonate, and polyphenylene 
oxide. A bead of adhesive is applied to at least one of the surfaces which 
are to be bonded, the parts are mated together and the assembly is heated 
at a temperature in the range from about 70.degree. C. to 190.degree. C. 
for about 1 minute to 1 hour, preferably from about 5 to 40 minutes. At 
times, a post-bake at temperatures in the range from about 100.degree. C. 
to 205.degree. C. for about 5 to 30 minutes can be beneficial in enhancing 
properties such as heat and environmental resistance. While the adhesives 
can be applied by any conventional method such as by roll coater, brush, 
curtain coater, extrusion or hand roller, robotic dispensing machines are 
preferred. 
The following examples are provided for purposes of specifically 
illustrating the invention and are not intended to limit in any manner the 
scope of the present invention. 
Preparation of Acrylate-Terminated Polyurethanes 
In Examples 1-3 below, three acrylate-terminated polyurethanes are 
prepared. The polyurethanes prepared are designated acrylated 
polyurethanes A, B, and C, corresponding to Examples 1, 2, and 3, 
respectively. 
EXAMPLE 1 
To a 5000 ml reaction flask fitted with a nitrogen purge is added 800 g of 
4,4'-methylene-bis(cyclohexyl isocyanate) [DESMODUR W-Mobay Corporation] 
and 1376 g of a mixture of 2-hydroxyethyl acrylate (30%) and an adduct of 
2-hydroxyethyl acrylate and caprolactone (70%) [TONE M-100 - Union Carbide 
Corporation], and the resulting mixture is allowed to react for three 
hours at 74.degree. C., during which the NCO value drops to 3.99. To the 
reacted mixture is then added 998 g of poly(tetramethylene oxide) diol (MW 
1000). The temperature is maintained at 80.degree. C. for an additional 
four hours to achieve a final NCO value of 0.27. 
EXAMPLE 2 
To a 5000 ml reaction flask fitted with a nitrogen purge is added 724 g of 
4,4'-methylene-bis(cyclohexyl isocyanate) [DESMODUR W-Mobay Corporation] 
and 1247 g of a mixture of 2-hydroxyethyl acrylate (30%) and an adduct of 
2-hydroxyethyl acrylate and caprolactone (70%) [TONE M-100 - Union Carbide 
Corporation], and the resulting mixture is allowed to react at 77.degree. 
C. for four hours until the NCO value drops to 4.0. To the reacted mixture 
is then added 128 g of poly(propylene oxide) diol (MW 385), followed by 
527 g of a mixture of RUCOFLEX polyester polyols (1,6-hexane 
diol/isophthalate-type polyester polyols) (RUCO Corporation). This mixture 
of polyester polyols is identified as IC-4724-12. The temperature is 
maintained at 77.degree. C. for an additional six hours to achieve a final 
NCO value of 0.01. 
EXAMPLE 3 
To a 2000 ml reaction flask fitted with a nitrogen purge is added 174 g of 
toluene-2,4-diisocyanate and 110 g of 2-hydroxyethyl acrylate and the 
resulting mixture is allowed to react at 60.degree. C. for one hour, until 
the NCO value drops to 16.1. To the reacted mixture is then added 501 g of 
poly(propylene oxide) diol (MW 501). The reaction temperature is 
maintained at 65.degree. C. for 90 minutes after which the final NCO value 
is determined to be 0.16. 
EXAMPLES 4-7 
Urethanes A, B, and C prepared as above are utilized to prepare two-part 
adhesive compositions along with other ingredients in the gram amounts 
shown below: 
______________________________________ 
Component A 
Example Example Example 
Example 
Ingredient 4 5 6 7 
______________________________________ 
Acrylated 40.00 0.00 0.00 0.00 
Polyurethane A 
Acrylated 0.00 40.00 0.00 0.00 
Polyurethane B 
Acrylated 0.00 0.00 40.00 30.00 
Polyurethane C 
Diglycidyl Ether 
20.00 20.00 20.00 30.00 
of bis-phenol A.sup.a 
Diethylene Glycol 
1.39 1.39 1.39 1.39 
Colloidal Silica 
2.71 2.71 2.71 2.71 
Titanium Dioxide 
0.70 0.70 0.70 0.70 
Talc 35.20 35.20 35.20 35.20 
100.00 100.00 100.00 100.00 
______________________________________ 
.sup.a EPON 828 Shell Chemical Company 
______________________________________ 
Component B 
Ingredient Examples 4-6 
Example 7 
______________________________________ 
ANCAMINE AD.sup.b 
19.0 0.0 
VERSAMID 140.sup.c 
47.0 57.0 
Triethylene Tetramine 
0.0 5.0 
Colloidal Silica 3.5 3.0 
Aluminum Powder 0.0 17.0 
Talc 30.5 18.0 
100.0 100.0 
______________________________________ 
.sup.b A trademarked material of Pacific Anchor Chemical Corp. comprised 
of approximately 55-60/40-45 blend of phenol/aliphatic amine. 
.sup.c A trademarked material of Henkel USA prepared by condensing a 
dimerized linoleic acid with a polyamine. 
Adhesive Testing 
For each of examples 4-6 above, Component A and Component B are metered and 
mixed together in an A:B weight ratio of 0.87:1. The adhesives so prepared 
are utilized to bond five sets of 4".times.4" SMC parts (DSM-950--Budd 
Company). The surfaces of the SMC parts are wiped with a dry rag, 
otherwise none of the surfaces are prepared or treated in any manner 
before bonding. The adhesive film thickness applied is 30 mils. The 
bonding assemblies are cured at 93.3.degree. C. for 10 minutes and at 
148.9.degree. C. for 30 minutes and tested with the OCF wedge test (SAE 
Test J 1882), using a 30" wedge with compressive load being applied at a 
crosshead speed of 0.5" per minute. The results of the tests are shown 
below in Table 1. 
The mode of failure described below is described as either fiber tear (FT) 
or cohesive failure (COH). A high level of fiber tear is desired since 
this indicates that the adhesive bond is stronger than the substrate 
itself. The energy to break is also given below and describes the pounds 
of force required to separate the SMC parts. 
TABLE 1 
__________________________________________________________________________ 
Example 4 Example 5 Example 6 
Energy to 
Mode of Energy to 
Mode of 
Energy to 
Mode of 
Break (lbs.) 
Failure Break (lbs.) 
Failure 
Break (lbs.) 
Failure 
__________________________________________________________________________ 
115.52 90 FT/10 COH 
149.28 
100 FT 
184.86 
100 FT 
162.09 50 FT/50 COH 
157.74 
100 FT 
156.53 
100 FT 
161.77 80 FT/20 COH 
146.24 
100 FT 
141.36 
100 FT 
168.68 80 FT/20 COH 
173.75 
100 FT 
188.29 
100 FT 
168.06 100 FT 119.31 
100 FT 
182.26 
100 FT 
Avg. Avg. Avg. 
155.22 149.27 170.86 
__________________________________________________________________________ 
For Example 7, Component A and Component B are mixed together in an A:B 
weight ratio of 1.11:1.0. The adhesives so prepared are used to construct 
lap shear assemblies of various thermoplastics according to ASTM procedure 
D-1002. The surfaces of the thermoplastic substrates are wiped with a dry 
rag to remove dust before bonding. An adhesive film thickness of 30 mils 
is utilized. The assemblies are fixtured, and cured at 93.3.degree. C. for 
30 minutes. The assemblies are then tested on a tensile tester at a head 
speed of 0.5 inches per minute. The results of the tests are shown below 
in Table 2. 
TABLE 2 
______________________________________ 
Example 7 
Mode of 
Substrate Energy to Break (lbs.) 
Failure 
______________________________________ 
Acrylonitrile- 606 100 FT 
Butadiene/Styrene.sup.a 
Polybutylene Terephthalate- 
852 100 FT 
modified Polycarbonate.sup.b 
Polycarbonate.sup.c 
690 100 FT 
Polyphenylene Oxide.sup.d 
664 100 FT 
______________________________________ 
.sup.a CYCOLAC General Electric Co. 
.sup.b ZENOY General Electric Co. 
.sup.c LEXAN General Electric Co. 
.sup.d GTX 910 General Electric Co. 
As can be seen from the above data, the adhesive compositions of the 
present invention can be utilized with a variety of essentially unprepared 
substrates to produce an adhesive bond of high strength.