Laminated polymeric articles and process for the production thereof

A process is provided for bonding otherwise incompatible resin systems to form laminated resinous articles. A first resin layer is coated with a solvated coating which forms a surface solution with the surface of the first layer. Thereafter, a second resin layer is bonded to the coating. The coating contains a butadiene resin, a portion of the resin used in the second layer, and curing agent for the resin. The process is particularly adapted to bonding polyvinyl chloride pipe cores to epoxy-impregnated glass fiber overwrap to form improved laminated plastic pipe.

BACKGROUND OF THE INVENTION 
Field of the Invention 
This invention relates to the bonding of two dissimilar polymeric resin 
composition surfaces. In a particular embodiment, the invention relates to 
a process for bonding an epoxy resin matrix reinforced with glass fibers 
to the surface of polyvinyl chloride pipe whereby the pipe is reinforced 
and withstands high pressures without rupture of the interface bond 
between the epoxy resin and the polyvinyl chloride surface. 
For some time plastic pipe made of one or more layers each of polyvinyl 
chloride and epoxy-impregnated glass fibers has been widely used in the 
construction and plumbing industries. Light weight and resistance to 
corrosion have been among the desirable properties of this type of pipe. 
This pipe conventionally consists of an inner hollow cylinder of polyvinyl 
chloride overlaid with a wrapping of epoxy-impregnated glass fibers. In 
some cases only a single layer of each material is used; in other cases, 
however, the first layer of epoxy-impregnated glass fibers is overlaid 
with a second polyvinyl chloride layer, which is itself then overlaid with 
a second layer of epoxy-impregnated glass fiber. Any number of such 
multiple alternating layers may be thus built up. 
Bonding between each pair of dissimilar surfaces of the alternating layers 
of epoxy-impregnated glass fiber and polyvinyl chloride has, however, been 
a serious problem, often reaching critical dimensions where the pipe 
consists solely of a relatively thin polyvinyl chloride inner cylinder 
overlaid with only one or two layers of an epoxy-impregnated glass fiber 
wrapping. Since polyvinyl chloride and epoxy do not substantially 
chemically bond with each other, mechanical forces were depended upon to 
maintain the integrity between the layers of the pipe. However, these 
mechanical forces were insufficient to withstand the countervailing forces 
produced by the fluid pressure within the pipe, and the layers of the pipe 
would become separated. This was particularly aggravated whenever it was 
necessary to cut into the pipe, as with a conventional pipe joint, thereby 
exposing the interface in the cut cross-section of the pipe to the full 
line pressure carried within the pipe. 
Description of the Prior Art 
Pipe manufacturers have for some time attempted to overcome the 
above-mentioned problem by seeking various means for creating a strong 
bond between the alternating layers of polyvinyl chloride and 
epoxy-impregnated glass fiber. These attempts have been substantially 
hindered, however, by the characteristic inertness and chemical resistance 
of polyvinyl chloride and related resins. The chemical reactions of these 
materials are generally substantially confined to those of degradation in 
heat or strong radioactive environments. Conventional attempts to achieve 
chemical bonds of epoxy resins, directly or indirectly, to polyvinyl 
chloride or related resins have been substantially ineffective and have 
failed to overcome the problems noted. 
Typical of the conventional and/or prior adhesives and surface treatments 
which have heretofore proven to be unsatisfactory are those described in 
U.S. Pat. Nos. 2,815,043; 3,002,534; and 3,447,572; as well as British 
Pat. No. 907,763. 
Recently in U.S. Pat. No. 3,628,991 a process was described in which an 
acrylonitrile-.[.butadinestypene.]..Iadd.butadiene-styrene .Iaddend.(ABS) 
copolymer dissolved in a mutual solvent for polyvinyl chloride and ABS was 
applied to the surface of the polyvinyl chloride pipe to form a surface 
solution. The epoxy-impregnated glass fiber layer was then overwrapped in 
contact with this ABS-containing surface solution and bonded to the ABS. 
This approach achieved a notable measure of success in creating a 
satisfactory bond between the polyvinyl chloride inner cylinder and the 
epoxy-impregnated glass fiber overwrap. 
BRIEF SUMMARY OF THE INVENTION 
The invention herein is an improvement in a process for bonding together a 
first resinous layer containing .Iadd.as .Iaddend.a major component a 
first polymeric resin and a second resinous layer containing as a major 
component a second polymeric resin, the second polymeric resin being 
.Iadd.liquid, .Iaddend.thermosetting, dissimilar to and substantially 
chemically unbondable directly to the first polymeric resin; the process 
comprising forming a surface solution, on the surface of the first 
resinous layer, of the first polymeric resin and a coating comprising a 
third polymeric resin and a mutual solvent for the first and third 
polymeric resins, where the third polymeric resin is substantially curable 
to the second polymeric resin and substantially chemically unbondable 
directly to and substantially .[.imcompatible.]. .Iadd.incompatible 
.Iaddend.with the first polymeric resin other than in a solvated state; at 
least partially fusing the surface solution; applying to the coating the 
second resinous layer containing the second polymeric resin in a 
substantially uncured form; and curing the second polymeric resin and 
simultaneously bonding the second resinous layer to the coating. The 
improvement herein comprises incorporating into the coating .[.the second 
polymeric.]. .Iadd.a solid thermosetting epoxy, phenolic or polyester 
.Iaddend.resin and a curing agent .[.for the second polymeric resin, and 
during the curing step bonding the second polymeric resin in the coating 
to the second polymeric resin in the second resinous layer.]. 
.Iadd.therefor. .Iaddend. 
In a preferred embodiment, the invention comprises an improvement in a 
process for bonding together a polyvinyl chloride layer and .[.an.]. 
.Iadd.a liquid .Iaddend.epoxy-impregnated fiber glass layer, the process 
comprising forming a surface solution, on the surface of the polyvinyl 
chloride layer, of polyvinyl chloride and a coating containing a butadiene 
resin and a mutual solvent for the polyvinyl chloride and the butadiene 
resin; at least partially fusing the surface solution; applying to the 
coating the epoxy-impregnated fiber glass layer containing the epoxy resin 
in a substantially uncured form; and curing the epoxy resin and 
simultaneously bonding the epoxy-impregnated fiber glass layer to the 
coating. The improvement of this preferred embodiment comprises 
incorporating .Iadd.a solid .Iaddend.epoxy resin and a curing agent 
therefor into the coating .[.and during the curing step bonding the epoxy 
resin in the coating to the epoxy resin in the epoxy-impregnated fiber 
glass layer.].. 
The invention also contemplates an improved laminated article, particularly 
a multilayer pipe, produced and bonded in the manner .[.discribed.]. 
.Iadd.described .Iaddend.herein. Consequently the invention also 
encompasses a laminated article having improved bonding between the 
laminae comprising a first resinous layer containing as a major component 
a first polymeric resin and a second resinous layer containing as a major 
component a second polymeric resin, the second polymeric resin being a 
.Iadd.liquid .Iaddend.thermosetting resin which is dissimilar to and 
substantially chemically unbondable directly to the first polymeric resin; 
the first and second polymeric resins being bonded into a laminate by a 
coating therebetween and in intimate contact therewith, the coating 
initially comprising (1) a third polymeric resin, which is thermoplastic, 
substantially curable to the second polymeric resin and substantially 
chemically unbondable directly to and substantially incompatible with the 
first polymeric resin other than in a solvated state; (2) .[.the second 
polymeric.]. .Iadd.a solid thermosetting epoxy, phenolic or polyester 
.Iaddend.resin; (3) a mutual solvent for at least the first and third 
polymeric resins; and (4) a curing agent for the .[.second polymeric.]. 
.Iadd.solid thermosetting .Iaddend.resin; the coating and the first 
polymeric resin forming a fused surface solution on the surface of the 
first resinous layer and the coating and the second resinous layer being 
chemically bonded. 
In a preferred embodiment, the invention also encompasses a laminated 
article, having a superior bond between the laminae, which consists 
essentially of a polyvinyl chloride layer and an .Iadd.initially liquid 
.Iaddend.epoxy resin impregnated fiber glass layer, the layers being 
bonded into a laminate by a coating therebetween and in intimate contact 
therewith, the coating initially comprising: (1) an 
acrylonitrile-butadiene-styrene resin; (2) .Iadd.solid .Iaddend.epoxy 
resin; (3) a mutual solvent for at least the polyvinyl chloride and the 
acrylonitrile-butadiene-styrene resin; and (4) a curing agent for the 
.Iadd.solid .Iaddend.epoxy resin; with the coating and the polyvinyl 
chloride forming a surface solution on the surface of the polyvinyl 
chloride layer and the coating and the epoxy-impregnated fiber glass layer 
being chemically bonded. In a particularly preferred embodiment, the 
laminated article having the improved bond between the laminae comprises a 
polyvinyl chloride hollow inner cylinder, an outer layer thereupon of an 
epoxy resin matrix reinforced with glass fibers, and a coating bonding the 
inner cylinder and the outer layer which initially comprises 
acrylonitrile-butadiene-styrene resin, epoxy resin, methyl ethyl ketone, 
and an equimolar complex of diacetoneacrylamide and diethylenetriamine.

DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS 
This invention is a novel method of bonding two dissimilar and otherwise 
unbondable resinous compositions. While the process of this invention is 
widely applicable to bonding any two such materials in any field of 
application, the process finds a particularly important use in the bonding 
of alternate layers of polyvinyl chloride and related resins to layers of 
epoxy and related polymeric materials. An important specific application 
of this process lies in a method for producing plastic pipe composed of 
alternating layers of polyvinyl chloride resin and epoxy-impregnated glass 
fibers. 
The process of this invention enables strong bonds to be formed between 
layers of dissimilar and otherwise generally unbondable resinous 
compositions. Pipe produced by the method described herein has good 
integrity and substantial resistance to separation at the interfaces 
within the pipe wall. Further, where it is necessary to cut into or 
through the pipe wall and expose one or more of the interfaces, the method 
of this invention can be used quite effectively to seal the cut surface 
and prevent exposure of the interface to the line pressure within the 
pipe, thereby preventing separation of the pipe wall at that interface. 
The "first polymeric resin," as defined herein, may be any of a wide 
variety of substantially chemically inert polymeric resins which can form 
surface solutions with the coatings described herein. Typical of the first 
polymeric resins suitable for use in this invention are poly(vinyl 
acetate), poly(methyl methacrylate), polystyrene, polybutene, poly(vinyl 
butyral), and the polymeric olefinic chlorides, notably poly(vinylidene 
chloride), poly(vinyl chloride) and copolymers thereof. The polymeric 
olefinic chlorides (which are referred to herein collectively as 
"polyvinyl chloride") are the preferred "first polymeric resin." 
The "second polymeric resin" is .[.a.]. .Iadd.an initially liquid 
.Iaddend.thermosetting resin selected from the group consisting of epoxy 
resins, polyester resins and phenolic resins. Of these, the epoxy resins 
are preferred. These are reaction products of epoxide compounds with 
compounds having available hydrogen atoms linked to carbon atoms by oxygen 
atoms. Examples of the latter are the polyhydric phenols and the 
polyhydric alcohols. A typical epoxy resin useful in this invention is the 
reaction product of epichlorohydrin and a polyhydric phenol such as 
bisphenol-A. Other illustrative epoxy resins typically include reaction 
products of epihalohydrins and polyhydric alcohols such as ethylene 
glycol, propylene glycol, trimethylene glycol, and the like. Also quite 
satisfactory in the process of this invention are the epoxy silanes; these 
are often used as the binding matrix for glass fibers as described, for 
instance, in U.S. Pat. No. 3,391,052. 
Other suitable epoxy resins include the epoxy novalak resins such as the 
epoxy phenol novalak resins. These are basically novalak resins whose 
phenolic hydroxyl groups have been converted to glycidyl ethers. Other 
suitable epoxy resin types include p-amine phenol epoxies, as well as 
cycloaliphatics in which the epoxide group are directly attached to the 
cycloaliphatic ring and epoxy ethers. 
The phenolic resins include those produced by reacting phenol with an 
aldehyde. The commercial phenols used are phenol, cresols, xylenols, 
p-tert.-butylphenol, p-phenyl-phenol, bisphenols and resorcinol. The most 
important aldehydes are formaldehyde and furfural. Preferred among the 
phenolic resins are those formed by the reaction of phenol and 
formaldehyde. The phenolic resin may be formed by either addition or 
condensation reactions in the presence of either acid or base. 
The polyester resins are formed by the reaction of polyfunctional acids or 
anhydrides and alcohols. A typical polyester resin is prepared by reacting 
phthalic anhydride, maleic anhydride, and propylene glycol. 
The "third polymeric resin" used in the process of this invention must be a 
butadiene resin. This may include polybutadiene itself or any of a variety 
of copolymers or terpolymers such as butadiene-styrene resin, 
acrylonitrile-butadiene resin, acrylonitrile-butadiene-styrene resin 
(ABS), mixtures thereof and the like. In the process of this invention it 
is required that the third polymeric resin be a butadiene resin; other 
materials have found not to be equivalent. 
Preparation methods for all the resins mentioned in the preceding 
paragraphs are well known and amply described in the art. Any of the known 
preparation methods are suitable to prepare the resins for use in this 
invention. 
The particular solvent used in process of this invention will depend upon 
the nature of the three polymeric resins which are being used. The 
particular solvent chosen must be one in which the first and the third 
polymeric resins are mutually soluble and preferably one in which all 
three resin components are soluble. Those solvents in which the second 
resin component is not readily soluble should still be such that the 
resinous material may be dispersed in the solvent in comminuted form. 
Typical solvents include tetrahydrofuran, methyl ethyl ketone, 
cyclohexanone, methylene chloride, acetone, ethyl acetate, isophorone, and 
the like. When the first polymeric resin is a polyvinyl chloride and the 
third is ABS, the preferred solvents are tetrahydrofuran and methyl ethyl 
ketone. 
The curing agents for the epoxy resins are commonly the aliphatic and 
aromatic polyamines or anhydrides. Typical of these are 
diethylenetriamine, triethylenetetramine, m-phenylenediamine, methylene 
dianiline or mixtures thereof; the principal anhydrides are phthalic, 
tetrahydrophthalic, hexahydrophthalic, "Nadic Methyl," and trimellitic. 
Other curing agents such as amides (e.g., diacetoneacrylamide) are also 
known. 
The exact composition and concentration of the components in the first and 
the second resinous layers are not critical. Each component will be 
selected primarily because of the particular properties desired in the 
finished material. Thus, in a typical pipe composition the inner polyvinyl 
chloride cylinder will be composed essentially all (i.e., usually about 90 
percent or greater) of polyvinyl chloride with a small amount of 
conventional additive material such as stabilizers, anti-oxidants, 
colorants, etc. Similarly, the layer of epoxy-impregnated glass fiber will 
consist of a range of concentrations of continuous filament glass fibers 
in an epoxy matrix and may also include materials such as colorants, 
anti-oxidants, stabilizers, curing agents, etc. in small amounts. The 
various concentrations of epoxy and glass will depend on the properties 
desired in the finished pipe. In these cases as in all others involving 
the various materials which may be in the first and/or second resinous 
layer, there is much prior art describing the various materials and their 
properties. Those skilled in the art will find no difficulty in selecting 
suitable compositions from the prior art for use in the process of this 
invention. 
For the purposes of this invention, therefore, first and second resinous 
layers are considered suitable if they are not generally bondable to each 
other (for if they are, they may be bonded by means other than the process 
of this invention) and if they each contain the respective first and 
second polymeric resins as principal components. "Principal component" as 
used herein is defined to mean a component which is present in sufficient 
quantity so as to contribute substantially to the bonding process of this 
invention. Generally this will mean that the particular components will 
comprise 40 to 50 percent or more, up to 100 percent, of the particular 
polymeric composition being considered. Such a component may, however, be 
present in a smaller concentration if the other components are relatively 
inert and/or the component in question provides a major part of the 
bonding function. Thus, for instance, in an epoxy-impregnated glass fiber 
layer, the epoxy resin may vary over a wide range of concentration and yet 
be considered a principal component, for the other important component in 
the system, glass fiber, is inert and does not participate in the bonding 
process. It is, of course, important that a "principal component" be 
present in sufficient amount to materially participate in the bonding 
function; small or trace amounts of a component which provide only a small 
amount of bonding are not considered to be within the scope of this 
invention. 
The novel coating layer initially consists essentially of four components: 
.[.the same resinous component which is found in the second polymeric 
resin composition, i.e., the second polymeric resin which is the.]. 
.Iadd.a solid thermosetting .Iaddend.epoxy, polyester or phenolic resin; 
the third (butadiene) polymeric resin; a curing agent for the .[.second 
polymeric.]. .Iadd.solid thermosetting .Iaddend.resin; and a solvent which 
is a mutual solvent for both the first and third polymeric resins and 
preferably also a solvent for the .[.second polymeric.]. .Iadd.solid 
thermosetting .Iaddend.resin. All components are dissolved in or dispersed 
in this solvent in the coating layer. During the process herein the 
solvent will evaporate. Consequently, the final laminae will be bound by a 
three-component coating containing the two resins and the curing agent. 
The second and third polymeric resins should be present in the coating in a 
weight ratio of from 1:10 to 5:1, preferably 1:6 to 3:1. The overall 
concentration of both resins will total from 5 to 60 weight percent of the 
total coating composition, preferably 10-50 weight percent. The 
concentration of the solvent will range from 40 to 95 weight percent, 
preferably 60-85 weight percent. The curing agent will be present as from 
5 to 35, preferably 11-25 phr (parts by weight per 100 parts by weight of 
second polymeric resin in the coating composition). 
While the theory by which the novel coating herein operates to produce the 
superior bonding properties has not been experimentally proved, it is 
believed that the curing agent present may be in effect less than the 
stoichiometric amount required to completely cure the second resin 
component of the coating. There thus may be some uncured resin available 
to bond with the second resin in the second layer and be cocured therewith 
in the final curing step. By "in effect less than stoichiometric" is meant 
that whatever amount of curing agent is added, there may still be 
incomplete reaction with the second resin; i.e., the stoichiometric 
reaction may not have occurred. On the other hand, since the degree of 
cure of the resin cannot be readily measured, the above theory is not 
intended to be limiting. It is recognized that there may be a complete 
curing of the second resin in the coating and then subsequent bonding of 
the second resin components of the coating and the second layer by one or 
more other mechanisms. 
The coating will be placed on the underlying first resinous layer (e.g., 
the polyvinyl chloride resin) in a quantity sufficient to dissolve the 
outer surface portion of the first resinous layer and to form a surface 
solution of that portion with the coating. Care should be taken, however, 
that the quantity of coating used is not so great as to dissolve a major 
portion of the first resinous layer and thereby to weaken or materially 
change the properties of that composition. Those skilled in the art of 
adhesion and bonding will be well aware of the proper amount of coating to 
be used on a particular resin composition substrate to achieve a good bond 
without seriously diminishing the desirable properties of that substrate. 
The quantity of coating is such as to normally penetrate the surface of 
the first polymeric resin composition to a depth of about 0.5 to about 3 
mils and to form a surface coating thickness of up to about 7 mils. 
In the practice of the process of this invention the underlying first 
resinous substrate is first cleaned of any foreign matter which might 
detrimentally affect the formation of a good bond. The coating composition 
containing the second and third polymeric resins and curing agent (all 
dissolved and dispersed in the solvent) is wiped, painted, sprayed or 
otherwise placed on the cleaned surface of the first polymeric resin 
composition substrate, and generally then worked into the surface to form 
a relatively homogeneous surface solution having the characteristics 
described above. 
The coated first layer is then heated to a temperature of 
100.degree.-200.degree. F., preferably 100.degree.-150.degree. F., and 
held for 1-10 hours. This heating serves to precondition the first layer 
and the coating for the final curing step. In addition, the surface 
solution is at least partially fused at this time. Some degree of curing 
of the second resin in the coating is also believed to take place 
simultaneously. 
Thereafter a second layer which consists of a second polymeric resin 
composition is applied to and placed in contact with the surface of the 
coating. The second polymeric resin in the second polymeric resin 
composition will be in a substantially uncured state. It is believed that 
this uncured resin subsequently cocures with any uncured portion of second 
polymeric resin present in the first coating, or otherwise bonds with 
cured portions of the coating resin. The concentration of the second 
polymeric resin in the layer may, as noted above, vary over quite a wide 
range, particularly where the layer also contains inert materials such as 
glass fibers. The layer may be sprayed, painted, wiped or otherwise 
applied to the surface solution, preferably in a wet form. In a preferred 
embodiment the layer is in the form of a tape or wrapping which is laid or 
wrapped on or around the substrate and surface solution. .[.This,.]. 
.Iadd.Thus, .Iaddend.when pipe is to be formed by the process of this 
invention, the inner cylinder (e.g., polyvinyl chloride) is first coated 
on its outer surface with the solvated coating, thus dissolving a small 
amount of that outer surface. Thereafter, following heating of the surface 
solution, coating and inner cylinder, an epoxy-impregnated 
fiberglass-containing tape is wrapped continuously and tightly around the 
cylinder bringing the tape into intimate contact with surface solution. 
Following the application of the outer layer the second polymeric resin is 
cured by conventional curing means. Generally this involves heating the 
entire assemblage so as to thermally cure the second polymeric resin. At 
the same time any uncured portion of the second polymeric resin in the 
surface solution is cured. The heat applied will, of course, be kept 
sufficiently low such that the other polymeric resins in the entire 
assemblage as well as any fillers or additives or other materials which 
may be present will be not detrimentally affected. Such curing techniques 
are well known to those skilled in the art and need not be exemplified 
here. I have found that for the compositions exemplified below, cure 
temperatures of about 130.degree.-180.degree. F. for 1-10 hours produce 
entirely satisfactory bonds. 
Although the details above have been described in terms of a single layer 
of each of the two polymeric resin compositions, it is evident that the 
process of this invention is also fully applicable to multiple layer 
compositions in which the first and second resinous layers alternate. 
The following examples will illustrate the process of this invention. In 
each case the first polymeric composition was a 4 in. O.D. polyvinyl 
chloride hollow cylindrical pipe core. Each core was brushcoated with the 
particular experimental coating solution, heated about 6 hours at 
145.degree. F., and then overwrapped with 1/2-inch fiberglass cloth tape 
saturated with an epichlorohydrin-Bisphenol A type .[.solid.]. 
.Iadd.liquid .Iaddend.epoxy resin .[.(commercially available from Shell 
Chemical Company under the name "Epon Resin 1001").].. The glass tape was 
applied in a single layer. The final assemblage was then cured for about 8 
hours at 150.degree. F. Curing agents, solvents and the like are as 
described below. 
Coatings were prepared containing a mixture of ABS resin (commercially 
available from Marbon Chemical Company as "Marbon E-1000 ABS") and 
.[."Epon Resin 1001" epoxy.]. .Iadd.a solid epoxy resin (commercially 
available from Shell Chemical Company under the name "Epon Resin 1001") 
.Iaddend.dissolved in methyl ethyl ketone. The curing agent was an 
equimolar complex of diacetoneacrylamide and diethylenetriamine 
(commercially available from the Lubrizol Corporation as "Lubrizol 
CA-21"). The methyl ethyl ketone solvent was generally present as 
approximately 50 to 80 weight percent of the coating; the curing agent was 
present in a concentration of approximately 12-14 phr. 
In the table below the results of various experiments performed to measure 
the adhesion of the different bonding systems are recorded. The degree of 
adhesion was measured by bonding the two surfaces in accordance with this 
invention and then simply pulling them apart. The relative degree of 
difficulty of separation of the bonded materials was rated (in part 
subjectively) on a scale of 0 to 4. A rating of 0 indicates that no 
significant bond was formed. A rating of 4 indicates that an excellent 
bond was formed, i.e., that the bonded materials were separated only with 
extreme difficulty and that it was the bonding coating itself which 
separated cohesively; its adhesive bond to either of the polyvinyl 
chloride or the epoxy-impregnated glass fibers did not separate. Since the 
tensile strength of the bonding coating is on the order of 2,000 psi, a 
bond rated 4 will have an adhesive strength of at least that value. The 
bonds rated 1, 2, and 3 represent intermediate degrees of adhesion of the 
coating. A bond rated 1 was one which could be separated with fairly 
little difficulty; a bond rated 2 was one which could be separated only 
with some difficulty; a bond rated 3 was one which could be separated only 
with considerable difficulty. Quantitative values were not assigned to 
these three ratings. 
TABLE 
______________________________________ 
Example Epoxy: ABS Curing Agent Adhesion 
No. Weight Ratio Conc., phr Rating 
______________________________________ 
1 0 (no epoxy) 0 0 
2 0.05 12 0 
3 0.10 12 1 
4 0.175 12 2-3 
5 0.25 12 2-4 
6 0.25 13.8 3 
7 0.33 12 3-4 
8 0.35 13.8 3-4 
9 0.43 12 3 
10 0.45 13.8 3-4 
11 0.55 13.8 3 
12 0.65 12 3 
13 0.65 13.8 2 
14 0.70 12 3 
15 0.75 13.8 1-2 
16 4.0 12 1 
______________________________________ 
It will be seen from these data that the process of this invention permits 
formation of strong bonds between otherwise incompatible resin systems. 
This in turn permits the production of laminated resinous materials, such 
as pipe, which have a heretofore unattainably high degree of integrity. It 
will also be seen that this invention produces a product with a bond 
significantly better than products with only the ABS and solvent in the 
coating, as are disclosed in aforesaid U.S. Pat. No. 3,628,991.