Bonding thermoplastic resins

Bonding between thermoplastic resins and inorganic oxide substrates is improved by providing to the resin/inorganic oxide interface as an adhesion promoter a combination of (a) a copolymer of an ethylenically unsaturated organic monomer and an unsaturated organosilane containing hydrolyzable groups; and (b) a monomeric hydrolytically reactive organosilane.

BACKGROUND OF THE INVENTION 
A relatively recent development in the field of coatings and adhesives has 
been the development of a class of materials which we shall refer to as 
polymeric organosilanes. These materials comprise organic polymer 
backbones having hydrolytically reactive silyl groups pendent therefrom. 
These types of compounds can be conveniently produced by copolymerizing 
ethylenically unsaturated organic monomers, e.g. ethyl acrylate, vinyl 
acetate, and the like, with ethylenically unsaturated organosilane 
monomers having hydrolytically reactive groups bonded to the silicon, e.g. 
vinyltrimethoxysilane, .gamma.-methacryloxypropyltrimethoxysilane and the 
like. Examples of such copolymerized organosilanes are found in U.S. Pat. 
Nos. 3,408,420; 3,306,800; 3,542,585; 3,962,471; 3,062,242; and 3,577,399. 
The polymeric organosilanes described above have been used as coating 
materials which displayed improved adhesion to inorganic oxide substrates 
by comparison to similar organic polymers containing no silyl groups. It 
has also been suggested that polymeric organosilanes be employed as 
adhesion promoters (i.e. coupling agents) to improve the bonding between a 
resinous medium and an inorganic substrate or filler (see, e.g., U.S. Pat. 
No. 3,306,800 and Inoue et al., J. Applied Polymer Sci., Vol. 19, pp. 
1939-1954(1). 
It has been further suggested that such polymeric organosilanes might 
impart bonding strength which is superior to that imparted by conventional 
monomeric silane coupling agents when employed in conjunction with 
non-reactive thermoplastic resins. Conventional monomeric silane coupling 
agents generally consist of silanes containing at least one reactive 
organic group and at least one hydrolyzable group bonded to the silicon 
atom. The monomeric silane coupling agents rely largely on the reactivity 
of their organic groups with coreactive organic groups in the resin matrix 
to provide bonding, hence, they do not function well in conjunction with 
resins such as thermoplastics containing no reactive groups. Polymeric 
organosilanes would be expected to provide improved bonding with 
thermoplastic resins due to the compatibility of the organic polymer 
portion with the thermoplastic resin matrix. 
While polymeric organosilanes indeed provide improved bonding between 
thermoplastic resins and inorganic oxide substrates, it is clear that 
relatively high levels of silane monomer, on the order of 20 to 25 mole %, 
must be copolymerized in the polymeric organosilane in order to achieve 
optimum bond strength. Employing these high levels of silane, however, can 
cause problems for a number of reasons. From an economic standpoint, the 
silane is a relatively costly material, thus, considerable economic 
benefit would be obtained if the silane content of the polymeric 
organosilane could be reduced without loss of adhesive strength. Moreover, 
high levels of silane in the polymeric organosilane tend to make it 
unstable and reduce its potlife. This latter phenomenon is due to 
hydrolytic crosslinking reactions which occur at the silyl groups of the 
polymeric organosilane and can cause unacceptable increases in viscosity 
and even gelation when the material is exposed to ambient moisture. The 
high levels of silane which have been required in the prior art to 
optimize bond strength when the polymeric organosilane is employed as an 
adhesion promoter unfortunately increase the likelihood of premature 
cross-linking of the polymeric organosilane. 
SUMMARY OF THE INVENTION 
This invention relates to improved methods of bonding thermoplastic resins 
to inorganic oxide substrates using polymeric organosilanes. In accordance 
with the teachings of this invention, excellent wet bond strength can be 
achieved using relatively low levels of silane in the polymeric 
organosilane. In addition to the improved methods of this invention there 
are provided improved thermoplastic resin compositions which are 
applicable to inorganic oxide substrates to form composites exhibiting 
outstanding wet bond strength. 
This invention is based on the discovery that when a monomeric 
hydrolytically reactive silane is employed in conjunction with the 
polymeric organosilane as an adhesion promoter additive in a thermoplastic 
resin, excellent wet bond strength was obtained at much lower overall 
levels of silane than were necessary when using the polymeric organosilane 
alone as an adhesion promoter. 
There is provided, in accordance with the teachings of this invention, a 
thermoplastic resin composition which displays outstanding wet bond 
strength to inorganic oxide substrates which comprises: (a) a 
thermoplastic resin, (b) a polymeric organosilane and (c) a monomeric 
hydrolytically reactive organosilane. 
There are also provided herein improved methods of bonding a thermoplastic 
resin to an inorganic oxide substrate. In one embodiment of the invention 
a polymeric organosilane and a monomeric hydrolytically reactive 
organosilane are admixed with a thermoplastic resin and the composition 
thus formed is then applied to an inorganic oxide substrate. In another 
embodiment, a primer composition containing the polymeric organosilane and 
monomeric hydrolytically reactive organosilane is first applied to an 
inorganic oxide substrate and the thermoplastic resin is thereafter 
applied to the inorganic oxide substrate having the primer on its surface. 
DETAILED DESCRIPTION OF THE INVENTION 
The polymeric organosilane employed in the compositions of this invention 
is a copolymer having polymerized therein: 
(1) at least one ethylenically unsaturated organic monomer containing at 
least one group of the formula &gt;C.dbd.C&lt;; and 
(2) at least one unsaturated organosilane monomer of the formula RSiX.sub.n 
R'.sub.(3-n) wherein R is a monovalent organic radical containing a vinyl 
group, i.e. CH.sub.2 .dbd.C&lt;, X is a hydrolyzable group, R' is a 
monovalent hydrocarbon radical containing up to 10 carbon atoms and is 
preferably alkyl, and n is an integer from 1 to 3, preferably 3. The 
hydrolyzable groups represented by X in the formula above are chosen from 
the group consisting of alkoxy of 1 to 4 carbon atoms, alkoxyalkoxy 
containing up to about 6 carbon atoms, acryloxy of 2 to about 4 carbon 
atoms, phenoxy, and oxime. Illustrative unsaturated organosilane monomers 
are gamma-methacryloxypropyltrimethoxysilane, vinyl triethoxysilane, vinyl 
tris(2-methoxyethoxy) silane, and the like. 
The ethylenically unsaturated organic monomer is preferably chosen to 
provide compatibility between the polymeric organosilane and the 
thermoplastic resin. In terms of producing polymeric organosilanes, having 
the desired compatibility with a fairly broad range of thermoplastic 
resins, preferred ethylenically unsaturated organic monomers are alkyl 
esters or alpha, beta-ethylenically unsaturated carboxylic acids, e.g. 
alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, 
butyl acrylate, hexyl acrylate, and 2-ethylhexyl acrylate and alkyl 
methacrylates such as methyl methacrylate, butyl methacrylate, 
2-ethylhexyl methacrylate, and lauryl methacrylate; vinyl aromatic 
hydrocarbons such as styrene, vinyl toluene, alpha-methyl styrene, and the 
like; vinyl halides and vinylidene halides such as vinyl chloride and 
vinylidene chloride; and vinyl esters of saturated fatty acids such as 
vinyl propionate, vinyl acetate, and the like. 
The polymeric organosilane can contain anywhere from about 75 to 95 mole 
percent, preferably 80 to 95 mole percent, of the ethylenically 
unsaturated organic monomer polymerized therein and from about 5 to 25 
mole percent, preferably 5 to 20 mole percent, of the unsaturated 
organosilane polymerized therein. It is an object of this invention, 
however, to provide excellent bond strength at relatively low levels of 
silane. In this regard, it is preferred to use as little of the 
organosilane as is consistent with good bond strength. 
The second component, which is employed in conjunction with the polymeric 
organosilane as an adhesion promoter, is the monomeric hydrolytically 
reactive organosilane. The monomeric hydrolytically reactive organosilane 
can be the same as or different from the unsaturated organosilane monomer 
which is copolymerized with the ethylenically unsaturated organic monomer 
to produce the polymeric organosilane. 
For example, the polymeric organosilane can be a copolymer of methyl 
methacrylate and gamma-methacryloxypropyltrimethoxysilane and the 
monomeric hydrolytically reactive organosilane 
gamma-methacryloxypropyltrimethoxysilane; or the polymeric organosilane 
can be a copolymer of methyl methacrylate and 
gamma-methacryloxypropyltrimethoxysilane and the monomeric hydrolytically 
reactive organosilane ethyltriethoxysilane. 
The monomeric hydrolytically reactive organosilane has the formula 
R".sub.(4-x) SiX.sub.x wherein X is a hydrolyzable group, R" is a 
monovalent organic radical of from 1 to 12 carbon atoms, which may or may 
not contain a functional organic group, and x is an integer having a value 
from 1 to 4, and is preferably 3 or 4. R" can be, merely by way of 
example, alkyl, aryl, alkenyl, cycloalkyl, aralkyl, acryloxy, 
methacryloxy, amino, or epoxy. The hydrolyzable group represented by X can 
be any of those previously mentioned as hydrolyzable groups in the 
unsaturated organosilane. While the X groups, i.e. hydrolyzable groups, of 
the monomeric hydrolytically reactive organosilane can be different from 
the X groups of the polymeric organosilane, it is preferred that the 
respective X groups be selected to have similar hydrolytic reactivity, 
that is, rates of hydrolysis. Those skilled in the art are familiar with 
the relative rates of hydrolysis of hydrolyzable groups or they can be 
determined without undue experimentation. For example, it is known that 
methoxy groups are more readily hydrolyzed than ethoxy groups. Most 
preferably, the X groups of the monomeric hydrolytically reactive 
organosilane and the X groups of the polymeric organosilane are the same. 
As merely illustrative of suitable monomeric hydrolytically reactive 
organosilane one can mention the following: 
CH.sub.3 CH.sub.2 Si(OCH.sub.2 CH.sub.3).sub.3 
CH.sub.2 .dbd.CHSi(OCH.sub.2 CH.sub.3).sub.3 
##STR1## 
(CH.sub.3).sub.2 Si(OCH.sub.2 CH.sub.3).sub.2 CH.sub.3 Si(OCH.sub.3).sub.3 
CH.sub.3 Si(OCH.sub.2 CH.sub.3).sub.3 
CH.sub.2 .dbd.Si(OCH.sub.3).sub.3 
##STR2## 
H.sub.2 NCH.sub.2 CH.sub.2 CH.sub.2 Si(OCH.sub.2 CH.sub.3).sub.3 H.sub.2 
NCH.sub.2 CH.sub.2 NHCH.sub.2 CH.sub.2 Si(OCH.sub.3).sub.3 
As disclosed in our copending application, U.S. Ser. No. 925,844, filed 
July 17, 1978, we have found that the polymeric organosilanes used herein 
may be stabilized against gelation prior to use by the presence of 
monomeric hydrolytically reactive organosilane and an alkyl alcohol. While 
the alkyl alcohol is not necessary to improve the bonding of the 
thermoplastic resin in accordance with the present invention, its presence 
as a stabilizing additive to the polymeric organosilane in no way hinders 
the adhesion promoting effect. Hence, it is within the scope of this 
invention to have alkyl alcohol present in addition to the polymeric 
organosilane and monomeric hydrolytically reactive organosilane. 
In accordance with the teachings of this invention, improved bonding 
between a thermoplastic resin and an inorganic oxide substrate is achieved 
by providing the polymeric organosilane and the monomeric hydrolytically 
reactive organosilane to the thermoplastic resin/inorganic oxide 
interface. 
In one embodiment of the invention the polymeric organosilane and monomeric 
hydrolytically reactive organosilane are supplied directly to the 
thermoplastic resin, whereby a significant portion thereof migrates 
through the resin to the resin/inorganic oxide interface. If desired, the 
polymeric organosilane and monomeric hydrolytically reactive organosilane 
can be provided to the resin as a solution in an inert organic solvent 
such as toluene. Usually, it is desirable that the resin be in the form of 
a solution in an organic solvent or that the resin be in the melt stage at 
the time of mixing with the polymeric organosilane and monomeric 
hydrolytically reactive organosilane in order to facilitate mixing. 
The thermoplastic resin containing the polymeric organosilane and monomeric 
hydrolytically reactive organosilane therein as an adhesion promoter is 
applied to an inorganic oxide surface. The inorganic oxide surface may be, 
by way of example, a continuous surface or it may be in the form of a 
particulate or fibrous filler. 
In bonding the resin composition containing the polymeric organosilane and 
monomeric hydrolytically reactive organosilane to the inorganic oxide 
substrate the resin is applied to the inorganic oxide substrate while the 
resin is in a flowable, i.e. plastic, condition. This condition can be 
achieved either by heating the resin composition to a temperature above 
the melting point of the resin or by providing the resin in the form of a 
solution in any conventional organic solvent, e.g. toluene, methyl ethyl 
ketone, and the like. After the resin composition has been applied to the 
inorganic oxide material, the resin is then solidified, either by cooling 
the resin below its melting point or by evaporating the solvent. 
Another convenient method providing the polymeric organosilane and 
monomeric hydrolytically reactive organosilane to the thermoplastic 
resin/inorganic oxide interface is by applying them as a primer coating to 
the inorganic oxide surface prior to bringing the inorganic oxide into 
contact with the thermoplastic resin. Normally, the polymeric organosilane 
and monomeric hydrolytically reactive organosilane will be provided as a 
primer in the form of a solution in a conventional inert organic solvent 
such as toluene, methyl ethyl ketone, etc. 
The amount of polymeric organosilane and monomeric hydrolytically reactive 
organosilane which is provided to the thermoplastic resin/inorganic oxide 
interface to improve bonding can vary considerably. When the polymeric 
organosilane and monomeric hydrolytically reactive organosilane are 
applied to the inorganic oxide surface as a primer, a thin coating is 
preferred in order to prevent the formation of a weak boundary layer. When 
the polymeric organosilane and monomeric hydrolytically reactive 
organosilane are supplied directly to the thermoplastic resin, it is 
preferred that the polymeric organosilane be provided in an amount which 
is equal to at least about 0.05 weight percent, based on the weight of 
the resin. 
There is no strict upper limit on the amount of polymeric organosilane 
which can be employed. However, there is in no event any particular 
advantage to be gained in employing the polymeric organosilane at a 
concentration exceeding about 10% by weight of the thermoplastic resin. 
The amount of monomeric hydrolytically reactive organosilane used in 
conjunction with the polymeric organosilane is that which will enhance the 
ability of the polymeric organosilane to impart wet bonding strength. 
Typically, we employ the monomeric hydrolytically reactive organosilane at 
concentrations of at least 5 mole percent, based on the number of moles of 
polymerized unsaturaged organosilane which are present in the polymeric 
organosilane, however, it is within the scope of the invention to employ 
as little as 0.1 mole percent of the monomeric hydrolytically reactive 
organosilane, based on the number of moles of polymerized unsaturated 
organosilane which are present in the polymeric organosilane. 
It is preferred not to employ the monomeric hydrolytically reactive 
organosilane at concentrations exceeding about 100 mole percent, based on 
the number of moles of polymerized unsaturated organosilane present in the 
polymeric organosilane. We have found that when the concentration of 
monomeric hydrolytically reactive organosilane is increased beyond this 
level, bonding strength becomes erratic and, at concentrations 
substantially in excess of 100% wet bonding strength drops off to 
virtually nil. 
The concentration of monomeric hydrolytically reactive organosilane which 
is employed in conjunction with the polymeric organosilane is specified 
above as a mole percentage of the polymerized unsaturated organosilane 
which is present in the polymeric organosilane. For example, if one 
employs, as the polymeric organosilane, a copolymer which is produced by 
copolymerizing 4 mol. parts methyl methacrylate (formula molecular 
weight=100) and 1 mol. part gamma-methacryloxypropyltrimethoxysilane 
(formula molecular weight=248), then a concentration of monomeric 
hydrolytically reactive organosilane which is specified as 100% indicates 
that 1 gram-mole of monomeric hydrolytically reactive organosilane is 
employed for each 648 grams of polymeric organosilane; a concentration of 
10% indicates that 0.1 gram mole of monomeric hydrolytically reactive 
organosilane is employed for each 648 grams of polymeric organosilane; 
etc. Similarly, if the polymeric organosilane is a copolymer of 9 mol. 
parts methyl methacrylate and 1 mol. part 
gamma-methacryloxypropyltrimethoxysilane, then a concentration of 
monomeric hydrolytically reactive organosilane specified as 100% indicates 
that 1 gram-mole of monomeric hydrolytically reactive organosilane is 
employed for each 1,148 grams of polymeric organosilane. 
The polymeric organosilane and monomeric hydrolytically reactive 
organosilane can be employed in conjunction with any convention 
thermoplastic resin with which the polymeric organosilane is compatible. 
As will be recognized by those skilled in the art, a thermoplastic resin 
is any organic polymer, copolymer, terpolymer, etc., which can be heated 
above its melting point and then resolidified by cooling below its melting 
point without undergoing any substantial change in properties. 
Merely by way of example, one can mention as useful thermoplastic resins 
polyolefins such as polyethylene, polypropylene, polyisobutylene and the 
like; polymers of alkyl esters of alpha, beta ethylenically unsaturated 
carboxylic acids such as methyl acrylate, methyl methacrylate, ethyl 
acrylate, ethyl methacrylate, and the like; vinyl esters of saturated 
fatty acids such as vinyl acetate, vinyl propionate, and the like; 
polyvinyl halides and polyvinylidene halides such as polyvinyl chloride 
and polyvinylidene chloride; polystyrene; polymers of conjugated dienes 
such as polybutadiene; cellulose ethers and esters; thermoplastic 
polyesters; polyvinyl ethers; polyvinyl acetal; styrenebutadiene 
copolymers, etc. 
While it is contemplated that the benefits of this invention will be 
realized primarily in conjunction with thermoplastic resins, some 
advantages may be obtained by using the monomeric hydrolytically reactive 
organosilane and the polymeric organosilane as adhesion promoting 
additives in thermosetting resins such as unsaturated polyesters, epoxies, 
and crosslinked polyurethanes. 
By "inorganic oxide" substrate is meant any inorganic solid material which 
possesses either oxygen (chemisorbed or covalently bonded) or hydroxyl 
(bonded or free) at its exposed surface. Specific illustrations of 
suitably employed inorganic oxide materials are, for example, iron, 
aluminum, or steel (oxidized at its surface), alumina, alumina trihydrate, 
brass (oxidized at its surface), copper metal (oxidized at its surface), 
siliceous materials such as fumed silica, hydrated silica (precipitated 
silica), silica, silica aerogels, silica xerogels, aluminum silicates, 
calcium magnesium silicate, asbestos, glass fibers, clays, molecular 
sieves, Wallostonite, calcium carbonate, titanium dioxide, calcium 
sulphate, magnesium sulfate, and the like. 
It was quite a surprising finding that the use of a monomeric 
hydrolytically reactive organosilane in conjunction with the polymeric 
organosilane caused excellent wet bond strength to be achieved at 
relatively low overall concentration levels of silane. When a polymeric 
organosilane consisting of a copolymer of methyl methacrylate and 
gamma-methacryloxypropyltrimethoxysilane was employed as the sole adhesion 
promoter additive in a vinyl acetate/vinyl chloride copolymer, the wet 
bond strength of the resin to aluminum underwent a steady decrease as the 
proportion of silane in the polymeric organosilane was decreased. When 
monomeric hydrolytically reactive organosilane was employed in conjunction 
with the polymeric organosilane, the proportion of silane copolymerized in 
the polymeric organosilane could be reduced without significantly 
adversely affecting wet bond strength. 
The degree of improvement in bonding strength which is achieved by using 
the monomeric hydrolytically reactive organosilane in conjunction with the 
polymeric organosilane varies somewhat depending on the particular 
thermoplastic resin and inorganic oxide substrate employed. For example, 
in thermoplastic vinyl resins, such as vinyl acetate/vinyl chloride 
copolymers, the use of monomeric hydrolytically reactive organosilane and 
polymeric organosilane together produced significantly better wet bond 
strength than the polymeric organosilane alone. Moreover, the improvement 
in bond strength was noted for all the polymeric organosilanes employed, 
regardless of their silane content. 
By comparison, with a thermoplastic polyurethane, the observed improvement 
in wet bond strength which resulted from having the monomeric 
hydrolytically reactive organosilane present was only significant when the 
polymeric organosilane contained a rather low level of polymerized silane. 
Nevertheless, a primary objective of this invention is achieved by 
allowing the obtainment of good bond strength using a polymeric 
organosilane which has a relatively low silane level, since the lower 
silane level renders the polymeric organosilane more stable against 
hydrolytic crosslinking.

The examples which follow are intended to further illustrate the invention 
and are not intended to limit its scope in any way 
EXAMPLE 1 
In order to illustrate the effect of the silane level in a polymeric 
organosilane on bond strength, a series of four polymeric organosilanes 
were prepared by copolymerizing, in toluene, methyl methacrylate and 
gamma-methacryloxypropyltrimethoxysilane to an approximate weight average 
molecular weight of 20,000 (56% solids). The proportion of 
gamma-methacryloxypropyltrimethoxysilane in the copolymer varied from 5 
mole percent to 20 mole percent. The polymeric organosilanes were each 
blended with a solution copolymer of 86 wt. % vinyl chloride, 14 wt. % 
vinyl acetate (20% solids in methyl ethyl ketone, viscosity 50 cps. at 
25.degree. C.) at concentrations of 1% and 2% by weight polymeric 
organosilane. The resins containing the various polymeric organosilanes 
were employed as adhesives to bond canvas to aluminum. The canvas/aluminum 
laminates were soaked in water at 25.degree. C. for one week. While the 
laminates were still wet they were tested for 180.degree. peel strength. 
The results appear in the following table. 
______________________________________ 
Polymeric organosilane 
Wet bond strength, lb./in.** 
MMA/A-174 mole ratio* 
1% 2% 
______________________________________ 
4/1 9 29 
9/1 8 17 
15/1 5 10 
19/1 0.1 -- 
______________________________________ 
*MMA = methyl methacrylate 
A174 = 
**Average of four repetitive tests ane- 
The above date illustrates the strong relationship between the amount of 
silane polymerized in the polymeric organosilane and the wet bond strength 
when the polymeric organosilane alone is employed as an adhesion promoter. 
The following examples illustrate the effect of using a monomeric 
hydrolytically reactive organosilane in conjunction with a polymeric 
organosilane as an adhesion promoter in the thermoplastic resin. 
A series of canvas to aluminum bonds were prepared and tested in a manner 
similar to the previous examples, using 1% polymeric organosilane, based 
on the weight of the resin, except that varying amounts of 
gamma-methacryloxypropyltrimethoxysilane monomer were also blended into 
the resin. Wet bond strengths of the canvas/aluminum composites are given 
in the table below. 
______________________________________ 
Polymeric organosilane, 
MMA/A-174 A-174 Wet bond strength 
mole ratio monomer, %* 
lb./in.** 
______________________________________ 
4/1 13 18 
9/1 23 25 
15/1 35 22 
19/1 43 27 
______________________________________ 
*Mole %, based on moles of A174 in the polymeric organosilane (equals 5 
wt. %, based on wt. of polymeric 
**Average of four repetitive tests 
The results of these examples are in dramatic contrast to the previous 
examples in which the polymeric organosilane was employed as the sole 
adhesion promoter. When the monomeric hydrolytically reactive 
organosilanes were employed in conjunction with the polymeric 
organosilane, the amount of silane in the polymeric organosilane could be 
substantially reduced without loss of bond strength. Moreover, the total 
amount of A-174, both in the form of monomeric A-174 and in the polymeric 
organosilane, could be substantially reduced without loss of bond 
strength. The ability to reduce the silane content of the polymeric 
organosilane without loss of bonding performance represents a considerable 
advance in the art, since a 19/1 mole ratio MMA/A-174 copolymer presents 
less viscosity stability problems than a 4/1 mole ratio MMA/A-174 
copolymer and, therefore, is expected to be more shelf-stable and have a 
longer potlife. 
For purposes of comparison, A-174 monomer alone was employed at a 1% level 
in the same vinyl chloride/vinyl acetate resin system used above and 
tested for wet bonding strength in canvas/aluminum composites. Wet bond 
strength, in four repetitive tests, averaged 0.2 lb./in. This confirms 
that monomeric reactive silanes, which are excellent coupling agents in 
reactive thermosetting polymer systems, do not provide good wet bonding 
when employed as coupling agents in non-reactive thermoplastic resin 
systems. 
EXAMPLE 2 
A series of polymeric organosilanes were produced by copolymerizing methyl 
methacrylate and A-174 in toluene to a molecular weight of 20,000 (56% 
solids). The molar ratio of methyl methacrylate to A-174 in the polymer 
varied as indicated in the table below. The polymeric organosilanes were 
blended with a solution copolymer of 86 wt.% vinyl chloride, 14 wt.% vinyl 
acetate (20% solids in methyl ethyl ketone, viscosity 50 cps. at 
25.degree. C.) at a concentration of 1% by weight polymeric organosilane. 
There were also blended with the solution copolymer varying amounts of 
A-174 monomer as indicated in the table below. The resins containing the 
polymeric organosilane and A-174 were employed as adhesives to bond canvas 
to aluminum. The canvas/aluminum laminates were soaked in water at 
25.degree. C. for one week. The laminates were removed from the water and 
tested for 180.degree. peel strength while still wet. Results, which 
represent average values for four repetitive tests, are represented in the 
table. 
______________________________________ 
Polymeric organosilane 
MMA/A-174 A-174 added, 
Wet bond strength 
mole ratio mole %.sup.1 
lb./in. 
______________________________________ 
4/1 0 9.5 
4/1 13 17.8 
4/1 33 15.3 
4/1 65 21.8 
4/1 131 0.1 
9/1 0 7.9 
9/1 23 25.1 
9/1 58 22.9 
9/1 116 8.0 
15/1 0 6.0 
15/1 35 22.5 
15/1 88 14.5.sup.2 
15/1 176 18.2.sup.3 
19/1 0 0.1 
19/1 43 27.6 
19/1 108 0.1 
19/1 216 0.1 
______________________________________ 
.sup.1 Based on moles of A174 in the polymeric 
.sup.2 Values ranged from 7-25 lb./in. 
.sup.3 Values ranged from 7-30 lb./in. 
EXAMPLE 3 
In this example, a polymeric organosilane and a monomeric hydrolytically 
reactive organosilane were applied in the form of a primer coating to 
aluminum preparatory to the application of a hot melt adhesive. The 
polymeric organosilane employed was a copolymer of 15 mol. parts methyl 
methacrylate and 1 mol. part gamma-methacryloxypropyltrimethoxysilane. A 
primer solution was prepared consisting of toluene; 0.5 weight percent, 
based on the weight of the toluene, of the polymeric organosilane; 10 
p.p.m. of dibutyltin dilaurate catalyst to catalyze reaction of the 
polymeric organosilane with the metal surface; and 6 weight percent A-174 
monomer, based on the weight of polymeric organosilane (equivalent to 42 
mole percent A-174 monomer when calculated on the basis of total moles of 
polymerized A-174 in the polymeric organosilane). As a control, a second 
primer solution was prepared in a similar manner with the exception that 
no A-174 monomer was present in the solution. 
A group of 3 in. by 4 in. annodized aluminum plates were dipped in each 
primer solution for several seconds. The primed plates were allowed to 
stand for 5 days at room temperature. The plates were then dipped in 
toluene to remove any unreacted material from the surface and allowed to 
dry. There was then applied to each plate a 10-mil film of a thermoplastic 
adhesive consisting of equal parts of rosin ester (supplied commercially 
under the trade name Stabilyte Ester Ten) and ethylene/ethyl acrylate 
copolymer (23 wt. % ethyl acrylate). The adhesive was applied at 
175.degree. C. and was pressed between the aluminum plate and a strip of 
canvas at a pressure of 200 p.s.i. Half the samples were subjected to 
pressure for 30 seconds and the remaining samples for one minute. 
When the adhesive had cooled to room temperature, the canvas/aluminum 
laminates were immersed in tap water for 5 days. The laminates were then 
tested, while still wet, for 180.degree. peel strength. The results appear 
in the table below. The letters A and C following the peel strengths, 
indicate adhesive and cohesive modes of failure, respectively. The ranges 
given represent ranges of peel strength in a series of four repetitive 
tests. For the samples which were bonded using one minute of bonding 
pressure, the results show clearly that the samples containing A-174 
monomer in addition to the polymeric organosilane imparted greater wet 
bond strength than the control samples which did not contain A-174. For 
the samples which were bonded using 30 seconds of bonding pressure, those 
samples which contained A-174 monomer in the priming solution more 
consistently produced bond strengths exceeding 12 lb./in. than those which 
did not contain A-174 in the priming solution. Further, in all instances 
where A-174 monomer was present in the priming solution, bond failure was 
in the cohesive mode; that is, failure did not occur at the 
aluminum/adhesive interface, but rather, failure occurred in the resin 
matrix itself. In instances where there was no A-174 in the priming 
solution in addition to the polymeric organosilane, failure was 
predominantly in the adhesive mode, that is, at the aluminum/adhesive 
interface. 
______________________________________ 
A-174 
Bonding pressure 
Silane monomer 
Peel strength, 
time, min. added lb./in. 
______________________________________ 
0.5 No 13-15(C),3-10(A*) 
0.5 Yes 12-16(C) 
1.0 No 2-10(A) 
1.0 Yes 12-20(C) 
______________________________________ 
*Failure was partially adhesive, partially cohesive