MEMBRANES IMPERMEABILISANTES

WATERPROOFING MEMBRANES

Abrégé anglais

ABSTRACT OF THE DISCLOSURE
Improved waterproofing membranes of the pressure-sensitive or self-
adhesive bituminous type particularly useful in roofing and for waterproofing
substrates in general are described. The membranes are in the form of
pre-formed, flexible, sheet-like laminates of (a) a layer of waterproofing
pressure-sensitive bituminous adhesive such as a rubberized asphalt
composition, and, (b) a flexible support sheet having an adhesive-promoting
coating on one or both surfaces to improve its bonding to the bituminous
adhesive to which it is laminated and/or to the bituminous adhesive layer
of a like overlapping waterproofing membrane. The adhesion-promoting coating
contains a polymer having a plurality of pendant carboxylate groups from its
backbone (e.g. an acrylic polymer such as polymethylmethacrylate, or a polymer
of a vinyl ester such as polyvinylacetate). Adhesion between such coating
and the bituminous adhesive is promoted by subjecting the contacting portions
to elevated temperature. The membrane is preferably provided further with
a layer of removable protective material such as siliconized "release" paper
placed adjacent the adhesive layer in order that the membrane is able to be
transported to the job site.

Revendications

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A pre-formed, flexible pressure-sensitive adhesive waterproofing
laminate comprising (a) a waterproofing layer of pressure-sensitive adhesive
bituminous composition; (b) a layer of flexible support material non-releas-
ably adhered to said layer (a); and (c) an adhesion-promoting coating layer
upon at least a portion of the surface of said support material (b) remote
from said adhesive layer (a) and/or between said support material (b) and
said adhesive layer (a), said adhesion-promoting coating layer containing a
polymer having a plurality of carboxylate groups COOR wherein R is alkyl of
1 to about 10 carbon atoms pendant from its polymeric backbone, said adhesion-
promoting coating layer acting to enhance the adhesive bond between the sup-
port material (b) and the adhesive layer (a) upon subjection of such adhesive
bond to elevated temperature.
2. The laminate of Claim 1 wherein said waterproofing layer comprises
a mixture of bitumen and polymer.
3. The laminate of Claim 2 wherein said polymer in said mixture is
thermoplastic.
4. The laminate of Claim 2 wherein said polymer in said mixture is
elastomeric.
5. The laminate of Claim 1 wherein said layer (a) comprises a mixture
of asphalt, rubber and mineral oil.
6. The laminate of Claim 1 wherein said support material is a film of
organic polymer, a metallic foil, or a woven or non-woven fabric or mesh.
7. The laminate of Claim 1 wherein said pendant carboxylate groups
14

are linked to said polymeric backbone by bonds between either a carbon atom
or an oxygen atom in said groups and the polymeric backbone.
8. The laminate of Claim 1 wherein said polymer having pendant car-
boxylate groups is an acrylic polymer, a polymer of a vinyl ester, or mixture
thereof.
9. The laminate of Claim 1 wherein said layer (b) comprises a plurality
of layers of differing materials.
10. The laminate of Claim 1 wherein said waterproofing layer (a) is at
least 0.010 inch thick.
11. The laminate of Claim 1 wherein said layer (b) is at least 0.001
inch thick.
12. The laminate of Claim 1 wherein the surface of the waterproofing
pressure-sensitive adhesive layer remote from said layer (b) has a protective
coating or covering which can be physically separated therefrom without sub-
stantially damaging the adhesive layer.
13. A pre-formed, flexible, pressure-sensitive adhesive waterproofing
laminate comprising (a) a waterproofing layer at least 0.010 inch thick of
pressure-sensitive adhesive composition containing bitumen and an elastomeric
polymer, the amount of said polymer present being from about 1 to 50 percent
by weight of said bitumen, (b) a layer of flexible support material at least
0.001 inch thick non-releasably adhered to one surface of said waterproofing
adhesive layer, said support material comprising one or more layers of mater-
ial selected from the group consisting of synthetic polymer films, metallic
foils, and woven or non-woven fabric; and (c) an adhesion-promoting coating
layer located upon at least a portion of the surface of said support layer

(b) remote from said adhesive layer (a), said adhesion-promoting coating layer
containing a polymer having a plurality of carboxylate groups COOR wherein R
is alkyl of 1 to about 10 carbon atoms pendant from its polymeric backbone,
said adhesive-promoting coating layer acting to enhance the adhesive bond
between the support material and the adhesive (a) of a like, overlapping water-
proofing membrane upon subjection of said adhesive bond to elevated tempera-
ture.
14. The laminate of Claim 13 wherein said adhesive layer (a) comprises
a mixture of asphalt, rubber and mineral oil.
15. The laminate of Claim 14 wherein said rubber is a copolymer of
styrene and butadiene.
16. The laminate of Claim 14 wherein said support of layer (b) is com-
prised of a polyester film.
17. The laminate of Claim 16 wherein said film is opaque.
18. The laminate of Claim 16 wherein said film comprises biaxially-
oriented polyethylene terephthalate.
19. The laminate of Claim 13 wherein said support layer (b) comprises
cross-laminated polyolefin film.
20. The laminate of Claim 13 wherein said adhesion-promoting coating
layer contains a polymer of one or more monomers having the structural for-
mula:
<IMG>
wherein R1 is hydrogen or alkyl of 1 to about 10 carbon atoms and R2 is alkyl
16

of 1 to about 10 carbon atoms.
21. The laminate of Claim 14 wherein said adhesion-promoting coating
layer is a dried adherent deposit from a solution, dispersion or emulsion of
said polymer containing said pendant carboxyl groups.
22. The laminate of Claim 14 wherein said polymer containing said pen-
dant carboxy groups is selected from the group consisting of acrylate and
methacrylate polymers, polymers of vinyl esters, and mixtures thereof.
23. The laminate of Claim 14 wherein said adhesion-promoting coating
layer contains a filler rendering it opaque.
24. The laminate of Claim 14 wherein said polymer in said adhesion-
promoting coating layer is a polymer of a polymerizable vinyl ester.
25. The laminate of Claim 24 wherein said polymer is polyvinyl acetate.
26. The laminate of Claim 20 wherein said alkyl contains, 1 to about 5
carbon atoms.
27. The method of waterproofing a substrate comprising the steps of ap-
plying a plurality of the laminates of Claim 1 to said substrate and subject-
ing the contacting portions of said adhesive and said adhesion-promoting
coating layers to elevated temperature.
28. The method of Claim 27 wherein said overlapped portion is heated to
temperature in excess of 70°F.
29. The method of Claim 27 wherein said overlapping portion is heated
to temperature of from about 120 to 200°F.
17

Description

143
Background Of The Inventi on
This invention relates to laminates of pressure-sensitive-adhesive
bituminous waterproofing layers adapted for waterproofing and sealing struc-
tures. More particularly, this invention relates to improved pre-formed
flexible sheet-like laminates of ~a3 a pressure-sensitive or "self-adhesive"
bituminous waterproofing adhesive layer and (b) a flexible supporting or
carrying layer of sheet-like material or film non-releasable adhered thereto,
which laminates are particularly useful as waterproofing membranes for sub-
strates such as roofs and decks of buildings, concrete bridge decks and the
like.
In United States Patent Nos. 3,741,856, 3,853,682 and 3,900,102 to
John ~lurst, there are described flexible pre-formed laminates of a water-
proofing pressure-sensitive bituminous adhesive layer and a flexible support
layer of e~g. plastic film or metallic film. The pre-formed laminates are
idealiy suited for forming waterproofing layers, for example upon or between
substrates such as concrete buildings and road decks, in place of the conven-
tionally utilized "built-up" waterproofing laminates constructed at the job-
site from layers of bitumen-impregnated "felts" which are typically "plied"
together by hot-applied layers of bitumen adhesive. As discussed in particular
20 in United States Patent No. 3,900,102, such laminates may ideally be construc-
ted in the plant in the form of a roll with a releasable layer of protective
material such as siliconiæed paper applied against the pressure-sensitive
bituminous adhesive, transported to the job site, and thereafter applied to
the substrate adhesive side down, each laminate strip overlapping the edge
of the previously-applied strip of laminate to insure a continuous waterproof
seal.
The present invention concerns an improved waterproofing laminate
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of the type described in *he aforementioned }lurst pa~ents. The improved
waterproofing laminate is a preformed flexible laminate of ~a) a layer of
waterproofing pressure-sensitive bituminous adhesive composition and ~b) a
flexible support sheet non-releasably adhered to the bituminous adhesive
layer having a coating or layer ~a) on at least one edge portion of its upper
surface remote from the adhesive and/or ~b) on its surface contacting such
adhesive which coating or layer promotes the adhesion of the support sheet
to the bituminous adhesive layer. The adhesion-promoting coa~T~s used herein
contain polymers having a plurality of pendant carboxylate groups from their
polymer backbone, for example acrylic polymers and polymers of vinyl esters.
It has been found that such coatings promote improved bondings to the bitumi-
nous adhesive after the contacting portions have been subjected to elevated
temperature.
DESCRIPTION OF T}IE DRAWINGS
Figure 1 is a perspective cross-sectional view of a waterproofing
laminate according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
In Figure 1, the inventive laminate is shown as comprised of four
layers, A flexible support sheet 1 is non-removably adhered to a layer of
pressure-sensitive waterproofing bituminous adhesive 2, and has on its upper
surface remote from adhesive 2, an adhesion-promoting coating or layer 3. A
removable protective layer 4, e.g. siliconized paper, is shown releasably-
adhered to adhesive 2. The laminate as shown has a width ~"w"), e.g. 36
inches, less than its length ~t'l"), e.g. 30 fee~, and can conveniently be
packaged in the form of a roll which is simply unrolled at the job-site, there-
after layer 4 removed, and the exposed surface or adhesive 2 placed adjacent
the substrate to be waterproofed. Another like strip of waterproofing
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4.3
laminate ~not shown) is then placed adjacent the laminate, care being taken
to overlap the laminate shown e.g. a distance "a" or "b" shown in Figure 1
in a manner such that the exposed surface of the adhesive layer of the like
laminate is in contact with the surface of layer 3 along the area defined by
width "a" or "b". Instead of fully covering the upper surface of sheet 1 with
layer 3 as shown in Figure 1, one or more edges of the sheet 1, e.g. the areas
"a" and/or "b" along the lateral edges of sheet 1 may be provided with coating
3 only, to promote adhesion between sheet 1 and the adhesive surface of the
next-applied like laminate strip. Also coating 3 may be positioned between
sheet 1 and adhesive 2.
The pressure-sensitive bituminous waterproofing adhesive layer 2
useful herein is of the type described in the aforementioned United States
patents to John Hurst. The adhesive composition comprises a mixture of ~a)
a bituminous material and ~b) natural or synthetic polymer preferably a rub-
ber or other elastomeric polymer. The amount of polymer employed in such
compositions is typically from about 1 to 100, preferably about 20 to 50,
percent by weight of the bituminous material. The term "bituminous material"
as used herein includes compositions containing asphalt, tar, or pitch. The
adhesive may be reinforced with fibers and/or particulate fillers. The ad-
hesive composition may also contain a conventional extender component suchas mineral oil. Suitable polymers include thermoplastic polymers such as
polyethylene and the like. As aforementioned, the preferred polymer component
is rubber which may be a virgin rubber or reclaimed rubber which is blended
into the bitumen and optionally the extender component preferably at elevated
temperature to form a smooth mix. Generally, suitable adhesive compositions
have softening points ~measured by the Ring and Ball method) of 70 to 120C.,
preferably 75 to 100C., and penetration valuec~ Of 50 to 400, preferably
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443
50 to 100 dmm. at 25C.(150 g/5 secs-ASTM-D217).
In order to give optimum sealin~ and waterproofing performance es-
pecially where the substrate to be waterprooed is concrete, the adhesive
layer should be at least 0.010 inch thick, preferably about 0.025 to about
0.200 inch thicX. The adhesive layer can be comprised of one or more layers
of the aforemen~ioned bituminous adhesive, not necessarily of the same compo-
sition, to give an adhesive layer within the overall aforementioned thickness
range. Further, the adhesive layer can have a reinforcement such as an open
weave fabric, gauze, scrim or the like located therein to strengthen it. The
adhesive layer 2 at least at its surface remote from support sheet 1 is pres-
sure-sensitive and tacky at normal ambient temperature in order that it be
self-adhesive to the substrate.
A wide variety of materials can be used as the sheet-like support 1.
It is generally desirable that the support be substantially impermeable to
water. For many purposes it is desirable that the support should be such that
after application of the laminate to a substrate it is capable of stretching
with movement of the substrate, e.g. as a result of shrinkage, with main-
tenance of a moisture and moisture-vapor-proof seal. However, where stretch-
ability and flexibility are less important than other properties, supports
not fulfilling these requirements can be utilized. For example, it is de-
sirable for some purposes to use a metallic foil, particularly of copper or
aluminum, as the support 1~
The preferred sheet supports 1 are films of synthetic organic poly-
mer such as polyethylene, polypropylene or other polyolefin, polyamide, poly-
ester, e.g. polyethylene terephthalate, polyurethane, polyvinyl chloride, a
copolymer of vinyl chloride and vinylidene chloride, synthetic rubber such
as polychloroprene or butyl rubber, etc.
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Other sheet-like supports include woven and non-woven fabrics of
inorganic or organic natural or synthetic fibers ~staple fibers or continuous
filaments), e.g. a woven fabric or fabrics of one of the synthetic organic
polymers already referred to: glass, tissue, hessian, cotton or other fiber
scrim, or bituminous roofing felt.
In applications where the laminate of the invention is to be exposed
to the weather, for example where strips of the laminate are to be applied so
as to form a continuous waterproofing membrane at the exposed surface of roofs
of buildings and the like, it is desirable that the support sheet 1 have op-
timum weatherabilîty characteristics. Thus the support sheet may be renderedopaque, for example by the incorporation therein of a material such as carbon
black to render the support sheet non-translucent. Alternatively, a trans-
lucent support sheet, e.g. a clear synthetic polymer film may be rendered
opaque by a top-coating of non-trans~cent material, for example a carbon black
containing coating. The support sheet may be a single sheet or film layer,
or may itself comprise a plurality of such layers, not necessarily identical,
laminated together to form a unitary support sheet layer 1. The support sheet
1 preferably is at least 0.001 inch in thickness, more preferably at least
about 0.004 inch thick. As in the case of the adhesive layer 2 described
above, the support sheet layer may have a fabric, gau~e or scrim reinforce-
ment therein to strengthen it.
Cross-laminated polymeric films and biaxially oriented polymeric
films are desirable support sheets 1 for use herein. As mentioned in
Canadian Patent No. 1,008,738 to Everett R. Davis, support sheets for lamin-
ates of the type herewith concerned comprised for example of cross-laminated
high-density polyethylene and biaxially-oriented polypropylene are desirable
support sheets to avoid wrinkling when the laminate is applied to a substrate
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and exposed to direct sunlight. Any film-forming synthetic polymer or copoly-
mer which can be oriented ~biaxially or cross-laminated) is useful. Biaxially
oriented films of such polymers as polyolefins, e.g. high and low density
polyethylene, vinylidene chloride, polystyrene, polyvinyl chloride~ rubber
hydrochloride, polyethylene terephthalate, etc. are commercially available.
Particularly useful films are biaxially oriented polyolefin and cross-lamin-
ated polyolefins. Preferred polymeric films for use as the flexible support
material in the invention are cross-laminated high density polyethylene film
and biaxially oriented polyesters such as polyethylene terephthalate desirably
containing a filler such as carbon black to render such opaque. Another pre-
ferred oriented film for use as the support sheet 1 in the invention is
biaxlally oriented polypropylene.
The adhesion-promoting coating or layer is of a material different
from that constituting sheet 1 and is employed herein to enhance the bonding
between bituminous adhesive 2 and support sheet 1. In the drawing, the sur-
face of sheet 1 remote from adhesive layer 2 is coated with such adhesion-
promoting layer (3) to improve bonding with an overlapping like membrane.
However, the adhesion-promoting coating 3 may be applied to the opposite sur-
face of sheet 1 to improve the bond between sheet 1 and adhesive layer 2 of
the laminate shown in the drawing. In another preferred embodiment (not
shown), both the upper and lower surfaces of sheet 1 are provided with coating
or layer 3.
The adhesion-promoting coatings used herein contain polymers found
to effect strong adhesive bondings between the bituminous waterproofing ad-
hesive and the support sheet upon subjection of the contacting bonded sur-
faces to elevated temperature. Such polymers contain a plurality of carboxy-
late groups COOR ~R being alkyl of for example, 1 to about 10 carbon atoms)
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pending from ~heir polymeric backbone. Such polymers include for example,
acrylate type polymers which have pending carboxylate groups linked to the
polymer backbone by way of carbon atoms (-COOR), and polymers of vinyl esters
such as polyvinylacetate which have pendant carboxylate groups linked to the
polymer backbone by way of oxygen atoms (-OOCR). In such polymers the car-
boxylate groups form part of substituent entities pendant from the backbone
or skeletal structure of the polymer, as opposed to polymers such as poly-
esters wherein the carboxylate groups are components of the skeletal struc-
ture.
Suitable acrylic type polymers useful in the adhesion-promoting
coatings herein include homopolymers and copolymers of monomers having the
structural formula CH2 C (Rl) COOR2, wherein Rl is hydrogen or alkyl con-
taining 1 to about 10 carbon atoms and R2 is alkyl containing 1 to about 10
carbon atoms. Exemplary acrylic polymers include homopolymers and copolymers
of methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate,
ethyl methacrylate, butyl methacrylate, etc., and mixtures thereof. Prefer-
red acrylic polymers or resins for use in the adhesion-promoting layer are
polymers and copolymers of monomers which are esters having the above struc-
tural formula wherein Rl is hydrogen or methyl and R2 is an alkyl group
containing 1 to about 5 carbon atoms, and mixtures of such. Exemplary poly-
mers of vinyl esters suitable for use in the adhesion-promoting layer include
polymers and copolymers of vinyl esters of carboxylic acids such as monocar-
boxylic acids containing for example 2 to about 20 carbon atoms such as
vinyl acetate, vinyl propionate, vinyl butyrate, etc., as well as mixtures
thèreof. Layers containing such polymers are preferably applied to the sur-
face of sheet 1 in the form of fluid adherent coatings of the aforementioned
polymers. Thus a fluid solution, dispersion or emulsion of the polymer e.g.
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3443
a solvent solution or a colloidal dispersion or emulsion of the polymer in
water, can be deposi~ed upon the surface of the support sheet 1 followed by
drying or otherwise removing the solvent or medium in which the polymer is
dispersed or emulsified. To promote bonding of the polymeric adhesion-pro-
moting layer to the surface of the support sheet, it may be desirable to in-
terpose between the coating and the sheet a layer of material having good
bonding characteristics to both the support sheet surface and the adhesion-
promoting polymeric coating, or to mix such a material in the adhesion-pro-
moting coating itself.
The thickness of the adhesion-promoting coating 3 will generally
range between about 0.05 mils and about 5 mils. The adhesion-promoting
polymeric layer further may contain one or more optional additives such as
particulate fillers, for example finely divided carbon black to enhance the
weatherability of the coating and/or to reduce the passage of ultraviolet
light therethrough. Further, the adhesion-promoting layer may contain ad-
ditives such as plasticizers, etc. to modify or enhance the physical proper-
ties thereof such as flexibility and elongation.
The enhanced bonding between the bituminous adhesive, the adhesion-
promoting coating, and the support sheet is achieved by subjecting the con-
tacting surfaces of such to elevated temperature, that is to a temperaturegreater than about 70F, and preferably greater than about 100F. Good
results have been obtained by heating the contacting portions to a tempera-
ture range of about 120F to 200F over a time period of about 1 to 30 days.
In practice, successive strips of the laminate of the invention may be ap-
plied to a substrate for example in overlapping fashion, and heat thereafter
applied to the portions of sheet 1 having coating 3 and in contact with the
adhesive layer 2. When the laminate is to be utili~ed in an environment
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443
where it will be exposed to elevated temperature, for example in the forma-
tion of a continuous waterproofing membrane on the tops of roofs of buildings
and the like, the requisite heating is supplied by exposure of the laminates
to the heat from the sun which can cause the laminates to be heated to tem-
peratures as high as 170F.
The waterproofing laminates of the invention as aforementioned are
conveniently produced in the factory9 stored and transported to the job site
preferably in the form of a roll comprising alternate layers of the adhesive
layer 2, support mate~al 1, adhesion-promoting coating 3 and a protective
layer 4. A wide variety of materials can be used to provide the protective
layer. Paper having a release coating thereon, e.g. siliconized paper, or
paper having a coating thereon of a vinyl chloride polymer, is satisfactory.
Other materials include films of organic polymers such as vinyl chloride
polymers.
The following detailed examples further illustrate the invention:
EXAMPLE I
Several laminates of ~a) a layer of rubberiæed-asphalt pressure-
sensitive waterproofing adhesive, and (b) differing support films were pre-
pared for testing of the strength of overlap bonds formed between like
laminates according to a "lap peel" adhesion test procedure. In the test,
two like laminates are superposed (exposed adhesive side of one laminate is
placed over the exposed surface of the support film of another like laminate).
The two superposed laminates are rolled with a 26 lb. weight four times to
bond the two together. The bonded laminates are then stored at a constant
temperature and after a recorded period of time removed from storage and
pulled apart by the jaws of an "Instron" test device at room temperature.
The Instron device separates the laminates at an angle of 180 to each other
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1~4''~4~3
at a rate of 2 inches per minute. The force required to separate the adhesive
surface of one laminate from the surface of the support film of the like lam-
inate is recorded in pounds per inch of overlapped width of the test sample.
In the test results recorded in Table I below, the laminates tested were pre-
pared by adhering a layer of rubberized asphalt in an approximate thickness
of between 40 and 60 mils to one side of rectangular-shaped support films
measuring approximately three inches by six inches. One of the support films
~Film "D" in Table I) had a polymeric coating on its surface overlapped by
the like laminate. The rubberized asphalt pressure-sensitive adhesive com-
position used contained approximately 45 to 52 parts by weight of asphalt,
16 to 20 parts by weight of styrene-butadiene rubber, 26 parts by weight of
mineral oil and 6 to 13 parts by weight of filler. The laminates tested
and the results of the tests are given in Table I.
TABLE I
LAP PEEL ADHESION
~Samples stored at 120F)
~Pounds per inch)
SUPPORT FILM
Stored A~l) B~2) C~3) D~4)
0 4-5 4-5 4-5 4-5
7 2~3 2-3 2-3 5-6
14 2-3 2-3 2-3
1-2 2-3 2-3 6-7
)Uncoated polymeric film ~film having no coating applied tO its
overlapped surface).
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4~`3
)Clear biaxially-oriented polyester (polyethylene terephthalate)
film having no coating applied to its overlapped surface.
~3)Carbon black-filled biaxially oriented polyester film having no
coating applied to its overlapped surface.
(4)Same as ~3) above, except that the overlapped surface of the film
Y ~ had an acrylic resin coating deposited thereon ("Elvacite"
methacrylate polymer hydrosol, product of E. I. DuPont de
Nemours ~ Co.~ in an amount of about 10-14 milligrams per
square decimeter of film. A vinylidene chloride resin under-
coating was employed for the acrylic resin.
The test results shown in Table I evidence that whereas the strength
of the heat-treated overlap bonds of the uncoated films "A-C" decreased over
a period of time, the strength of the overlap bonds to the acrylic-coated
film "D" improved with time.
EXAMPLE II
Various coatings were applied to aluminum foil and also to the films
"A" and "B" of Table I to investigate the effect of such coatings on "lap
peel" adhesion of the coated surfaces to a rubberized-asphalt pressure sen-
sitive adhesive as in Example I. The coatings were obtained by depositing
and drying each of the following on the film surfaces;
~1) Solvent solution of polymethylmethacrylate resin ~"Elvacite
2041")
~2) Solvent solution of polyethylmethacrylate resin ~"Elvacite
2042")
(3) Solvent solution of methacrylate copolymer resin ("Elvacite
2013")
(4) Solvent solution of acrylonitrile rubber
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~ rr&lcle ~n~rk

~5) Solvent solution of styrene/butadiene rubber ~40/60)
~6) Polyvinylidene chloride aqueous latex
(7) Polyvinyl acetate aqueous dispersion
(8) Solvent solution of rubberized asphalt composition.
The overlap bond strengths between the surfaces coated with tha
above coatings 1-8 and the rubberized-asphalt waterproofing adhesive layer
were tested as in Example I. Prior to testing in the Instron device, the
lapped surfaces were first stored at elevated temperatures (120F. and
higher). The acrylic coated films (coatings 1-3) and the films coated with
polyvinyl acetate (coating 7) showed a marked increase in lap adhesion as
did the films coated with the solvent solution of rubberized asphalt (coating
8). The latter coating ~8) is impractical as an adhesion-promoting coating
in the present invention however as it is tacky after deposition upon the
film and would require an additional protective coating during shipping.
The acrylonitrile rubber coated surfaces, the surfaces coated with polyviny-
lidene chloride, and the surfaces coated with styrene-butadiene rubber
~coatings 4, 5 and 6) showed no major improvement in lap bond strength. In
addition to the laboratory coated films tested above, commercially coated
films were also tested. A polypropylene film commercially coated with acrylic
resin showed marked increase in lap bond strength. A film commercially
coated with polyvinylidene chloride did not show increased lap-bond strength.
EXA~IPLE III
Coatings 1J 7 and 8 f.om Example II were deposited upon samples of
the support film "A" of Table I and the "lap Peel" adhesion tests of Example
I performed on overlap bonds of the coated surfaces to a rubberized asphalt
pressure-sensitive adhesive composition as in Example I. The tests were
performed at 72F. after storage of the test samples for 24 hours at (a)
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70F.; ~b) 120F.; and ~c) 138F. The results are shown in Table II below.
TABLE II
ADHESION-
PROMOTING LAP PEEL ADHESION
COATING (Pounds per Inch)
NO. 70F 120F 138F
None 2.7 2.7 2.3
7 2.7 6.7 6.7
1 2.7 3.0 5.7
8 1.7 3.0 4.0
The test results shown in Table II evidence that all three coatings
enhanced lap-bond strengths after storage at elevated temperatures.
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