CA1127017A - Pressure sensitive products and adhesive formulation - Google Patents

Abstract

Abstract of the Disclosure A pressure sensitive product is disclosed which comprises: (a) a plastic film; (b) a layer of pressure sensitive adhesive attached to the film, optionally, with a backing material therebetween, said layer of adhesive containing non-leafing metallic flakes; and (c) optionally, a release liner attached to the surface of the adhesive. After application of bonding pressure, the product exhibits superior ad-hesion as compared to a control product not containing the metallic flakes.

Description

CIP of C-5016 AND ADHESIVE FORMULATION

Background of the Invention Field of the_Invention The present invention is a pressure sensitive plastic film product which exhibits superior adhesion after being bonded to a desired substrate with the appli-cation of pressure. The invention also relates to the pressure sensitive adhesive composition used in said product.
Description of the Prior Art Pressure sentitive products which can be bonded to a desired substrate with the application of pressure are a well-known type of product. In order to insure a more permanent bonding of such products to the substrate, it is desirable for such products to exhibit the highest possible adhesion values~ Although it is possible to achieve a greater degree of adhesion by chemical modification of the polymers which normally constitute the pressure sensitive adhesive layer, such an appro~ach requires some degree of sophisticated chem-ical capability which might not be possessed by some of the ultimate end users of those conventional pressure sensitive adhesives which are commercially available.
Hence, a need exists for a simple means to increase the ~ CIP of C-5016 adheslon values of pressure sensiti~e products without a need to resort to actual modification o the polymPric constituents of the pressure sensitive adhesive.

Summary of the Present Invention The present invention is a pressure sensiti~e product which comprises: ~a) a plastic film; (b) a layer of pressure sensitive adhesive attached to the film, optionally, with a backing material therebetween, said layer of adhesive containing non-leafing metallic flakes;
and (c) optionally, a release liner attached to the adhesive layer. 5uch a pressure sensitive product ex-hibits superior adhesion as compared to a control product not containing the metallic flakes after it is bonded to a substrate by application o pressure. Also included within the scope of the present invention is the pressure sensitive adhesive/non-leafing metallic flake subcom-bination used in such a product.

~D~ P~
CIP of C-5016 Brief Description of the Drawings The Drawings which are attached hereto and which form a portion of the specification are intended to illustrat~ certain embodiments of the invention where-in:
Figure 1 is an enlarged cross-sectional view of one type of pressure sensitive product made in accordance with the present invention; and Figure 2 is an en}arqed cross-sectional view, partially brokent of another pressure sensitive product made in accordance with the present invention which con-tains a backing material between the adhesive layer and the film.

Detailed Descri~tion of Preferred Embodiments The pressure sensitive product of the present invention will be more fully understood by referring to the Drawings which form a portion of this application.
In Figure 1, one preferred embodiment of the present invention is shown in cross-section, wherein a plastic film 1 has a layer of pressure sensitive adhesive 2, containing non-leafing metallic flaXes 3, laminated to one of its sides. A release liner 4 covers the side of the adhesive layer ~ which is opposite to the side attached to film 1 in order to protect the adhesive from contamination from dirt or other solid or liquid contaminants.
The plastic film 1 may be any conventional, flexible film known to persons of ordinary skill in the ~ .

CIP of C-5016 art of fabrica-ting pressure sensitiV0 p.roducts. If de-sired, it can be a "substantiall~ transparent" film if A
decorative product is clesired. The ter~l "substantially transparent" as used herein is intended to enco.mpass those plastic ilms which are -transparent enough to allow a viewer ta perceive the decorative effect generated by the metallic flakes 3 in the adhesive 2. The fil.m thickness in either a decorative or non-decorative product will generally range from about 0.05 mm. to about 0.5 mm., and the film can be a homopolymer or copolymer of vinyl chloride, the preferred film material, a polyester resin, a cellulose resin, an acrylic resin, a urethane resin, a polyolefin resin, ox the like, and compatible blends there-of. Films of this type are well known to the art and have been used heretofore in forming pressure sensitive products which differ in construction from the product shown in Figure 1.
The layer of pressure sensitive adhesive 2 which is used in the present laminate may also be formed using any of the pressure sensitive adhesives which are known and conventionally used in the art. Such an adhes-ive may be based upon any elastomeric adhesive material, such as: (1) natural rubber; (2) synthetic rubbers in-cluding, for example, styrene-butadiene copolymers, poly-isobutylene, butadiene-a~crylonitrile copolymers, pol.y-chloxoprene, and polyisoprene; t3) acrylic copolymers con-taining at least 50 percent, by weight, of a C.~-C1 2 alkyl acrylate ester together with a hardening comonomer, for example, vinyl acetate, styrene, methyl methacrylate, methyl acrylate, ethyl acrylate, ethyl methacrylate, and vinyl çhloride, and (4) polymers of alkyl vinyl ethers such as, for example, polymethyl vinyl ether and polyethyl vinyl ether. ~crylic pressure sensitive adhesives are most preferred since they have the best balance of adhesive 7f~

CIP of C-5016 and cohesive properties for the present laminate. The thickness of the adhesive layer 2 will generally be in the range of from about 0.013 mm. to about 0.05 m~.
The pressure sensitive adhesive layer 2 used in the product of the present invention contains an e-fective amount of non-leafing metallic flakes 3 to sur-prisingly increase the adhesion oE the product after it has been bonded with pressure to a de-sired substrate and, in the case of a product containing a "substantially transparent" film 1, to also produce a decorative effect in the product by being visible through the plastic film 1. These flakes 3 are homogeneously dis-persed throughout the adhesive layer 2 by means of con-ventional mixing techniques. The term "non-leafing me-tallic flakes" is well kno~n, and such products can be formed by means well known to persons of ordinary skill in the art. For purposes of the present invention, non-leafing aluminum flakes are preferred, and the following description of its method of manufacture and properties will sufficiently apprise a person of ordinary skill in the art as to how this metallic component might be formed`.
The aluminum flake which can be employed in the preparation of the laminate product of the instant inven-tion can be prepared in several ways. The most common means of obtaining aluminum flake is to atomize molten aluminum and subsequently grind it or hammer it in the presence of various lubricants. If the lubricant is a long chain saturated fatty acid, the prepared flake is not easily wetted by a resinous adhesive vehicle and tends to float to the surface subsequent to application, giving a more or less continuous layer of aluminum flakes. This phenomenon is called "leafing". Such leafing flakes are not suitable for use in the product of the present in~en-tion. It is therefore desirable to remove the long chain fatty acid or to grind or hammer the atomized aluminum in , CIP of C-5016 -the presence of other materials s~ch as, for example, the short chain fatty acids. The ~lake~ thus produced are more easily wetted by the resinous adhesive vehicle and tend to become randomly dispersed, rahter than to float~
Tney are, thereore, less likely to layer at the surface during the curing or drying o the adhesive.
The aluminum flake can, i~ desired, be sub-jected to various treatments which impaxt a gloss or pol-ish thereto. These polished aluminum flakes may then be utilized when a highly reflective decorative effect is to be generated by the product of the present invention.
These non-leafing aluminum flake particles are platelike in appearance but have a ragged edge which fol-lows no geometrical design. Tha flatness or platelike appearance of the flake is generally determined by the method by which the flakes were prepared. Hammered flakes, for example, tend to be more flat than those that are ball milled. However, both types may be used in the present invention. For a more complete de~oription of non-lea~ing aluminum flake and the methods of preparation of such flakes, reference is made to "Organic Coating Techlology"
by Payne, Vol. II, 1961.
The particle size of the flakes should be pre-dominantly from about 100 mesh to about 200 mesh ~U.S.
Standard Sieve) although a certain proportion may be above 100 mesh and up to 60 mesh. A predominant number, pref-erably about 80 percent of the flakes, should be from about 200 to about 60 mesh. Excellent compositions may be made using ~lake having as much as 15 percent below 325 mesh in size which aids suspension, although as a sub stantial number of the particles approach a smaller size (below 325 mesh), there may be an insufficient number of large planer surfaces provided in the adhesive to yive the desired degree-of opacity needed when a decorative product is desired. One suitable non-leaing aluminum flake CIP of C-5016 which is commercially available from Alcan Metal Powder, Inc. is known under the grade deslgnation l'Grade MD-3100".
The aluminum flake particles are employed in amounts of at least about 5%, by welght of the adhesive layer, with a maximum of about 20%, by weight. optimum effects have been obtained when amount of flake is pres-ent at about 12%, by weight. Use of too little flake will not give the desired effects, whereas amounts higher than described above will weaken the adhesive/substrate bond.
It is most preferred that from about 10% to about 15%, by weight, of flake be used.
If desired, a tinting pigment may be added to the flake-containing adhesive composition or to the flakes themselves prior to their incorporation in the ad-hesive layer when a decorative product is desired. Ex-amples of such pigments which may be used include phtha-locyanine green, phthalocyanine blue, indanthrene yellow, burnt sienna, indo orange, phthalocyanine blue green tone, carbon black, phthalocyanine blue red shade, quinacridone red and hydrated iron oxide.
If the product of the present invention shown in Figure 1 is to be manufactured at one location and used at another location, a release liner 4 is preferably affixed to the side of the pressure sensitive layer 2 which is furthest removed from film 1. The release liner 4 may be any of the release liners known to persons of ordinary skill in the art of making pressure sensitive products in-cluding removable, water soluble protective coatings, and the like. One preferred liner material is silicone coated release paper having a thickness of from about 0.05 mm. to about 0.3 mm. Of course, if the film/adhesive composite is to be m~anufactured and applied to a desired substrate at the same manufacturing location, a release liner may not be needed.

~i7~
CIP of C-5016 g _ The laminate product o~ the present invention can be formed by any of the conventional techniques used to form pressure sensitive films. In a pre~erred embodi-ment, when a release liner, such aa release paper, is to be used, the adhesive formulation ln solvent form con-taining the non-leafing metallic ~lakes is applied to the release liner, and the adhesive/release liner composite is then heated to dry the adhesive layer. This combina-tion is laminated to the plastic film to form the final product. In those few applications wherein the product is not intended to have a release llner, the adhesive/
metallic flake composite can be ca8t onto the vinyl film, and the adhesive layer in the resulting laminate can then be dried.
Another embodiment of the claimed invention i.s shown in Figure 2 wherein a backed pressure sensitive product is shown. Component Nos. 11, 16, 17 and 19 in Figure 2 are meant to indicate the same materials which are used for Component Nos. 1, 2, 3 and 4 in Figure 1, re-spectively. The backing material 13, which can comprise synthetic fibers 15 needle punched into a thin layer of foam 14, is the added component in this article and can be attached to the film 11 by a suitable adhesive layer 12, if desired.
The backing 13 can be selected from a wide var-iety of conventional backing materials, such as non-woven, woven, knit, or composite ma~erials (non-woven/foam com-binations, non-woven/knit combinations, non-woven/woven/
knit combinations, etc.) to provide a sufficiently thick layer for the intended purpose. For example, in Figure 2, the ~acking (which is sho~n in broken form) will aid in camouflaging any surface irregularities that may exist on the substrate to which the composite article is attached.
If the intended use of th~ product is as an exterior roof-ing material for motor vehicles, for example, its weight "7~
CIP of C-5016 will range ~rom about 68 to about 680 gm./m. 2, and its density from about 32 to about 320 kg./m. 3. The thick-ness of such a backing and film camposite will generall~
range from about 0.5 mm. to about 5.1 mm., preferably from about 1.4 mm. to about 2.2 mm.
The backing material 13 shown in Figure 2 is a commercially available backing oE a non-woven fabric of synthetic fibers 15 which have bean needle punched into a thin layer 14 of foam. Some preferred examples of fibers which can be used in such a backing include: polypropyl-ene, rayon, polyester, acrylonitrile, nylon, polyphenylene sul~ide, and mixtures thereof. Suitable foam materials which can be used include urethane and polyvinyl chloride foams. The denier of such fibers in this type of backing can range from about l to about 20. "Denier" is defined as a unit of fineness equal to the fineness of a yarn weighing one gram for each 9000 meters. The foam in such a backing can have a thickness of from about 0.25 mm. to about 2.5 mm.
The backing 13 if intended for outdoor use can be made water repellent by treatment with an effective amount of at least one conventional water repellent agent.
Fluorocarbon emulsions, which are available under the trademarks "Zepel" (from E.I. DuPont de Nemours Co.) or "Scotchguard" (from 3M Co.), are representative types of materials which can be used to confer such water repel-lency. In order to treat the selected type of backing material, it can, for example, be placed in a fluorocarbon bath, dried, and the resulting product can be cured. The product that results from either this or alternative con-ventional treating procedures will resist being wetted by water, oil and other contaminants. Further information on how backing 13 might be rendered water repellent can be ascertained from "Waterproofing and Water Repellency", CIP of C-5016 Kirk-Othmer Encyclopedia of Chemi~l Technology, 2nd Edl-tion, Vol. 22, pp. 135-156 (1970).
If desired, one or more corrosion inhibitors can be used to treat the backing 13, i~ the article is to have exterior uses, in order to coner o~ enhance corrosion pro-tection on the article/substrate combination. The corro-sion inhibitor can be any compatible inhibitor and can be applied in conjunection with the a~orementioned water re-pellent agent. For example, when a fluorocarbon bath treatment is ~mployed, such known corrosion inhibitors as the nitrites, phosphates, chromates and sulfates might be present in the bath to act as a corrosion inhibitor when the article is subjected to exterior use in the final article/substrate combination that will be produced. One corrosion inhibitor which is preferred for economic rea-sons is sodium nitrite. Further information on how the backing 13 might be treated to render the article/sub-strate combination corrosion resistant can be ascertained from "Corrosion Inhibitors", Kirk-Othmer Encyclopedia of Chemical Technology, 2nd Edition, Vol. 6, pp. 317-346 (1965).
The composite article of film 11 and backing 13 which is known to the prior art can be formed by a number of well-known processes such as direct calender lamination or extrusion coating, post lamination or casting.
Direct calender lamination or extrusion coating produce a composite article without the use of adhesive layer 12. The plastic film 11 acts as the adhesive because it is brought in contact with the backing 13 shortly after formation while the film 11 is still hot and sticky.
Post lamination is another well known method and differs from the extrusion coating or direct calender lam-ination techniques in that the plastic film 11 is not us-ually formed just prior to the bonding step, and an ad-hesive layer 12 is applied directly by known coating ?r;fC~ r~

CIP of C-5016 techniques (gravure cylinder, kniEe, roller, reverse rol-ler, etc.) to the film before the film is contac-ted with the backing 13. A roll of preEormed film is generall~
the source of the film, and a thin layer of adhesive is applied to the side of the film which is to be bonded to the backing. The adhesive is applied by a suitable means usually in an amount in the range of ~rom about 34 gm./
m.2 to about 170 gm./m.2 depending upon the adhesive. The coated film then is contactea with the backing to form lO the composite article known to the prior art.
Adhesives suitable for use in the post lamina-tion technique are well known in the art. Some examples include plastisol, epoxy, acrylic, and urethane adhesives.
Plastisols are one of the best known materials. These 15 are dispersions of finely divided polymeric materials in nonvolatile organic liquids and low melting solids, gen-erally referred to as plastici~ers. Suitable plasticizers include phthalate, adipate and sebaccate esters and poly-ols such as ethylene glycol and its derivatives. A typi-20 cal plastisol composition is 50 parts of polymer material and 50 parts o~ plasticizer which forms a paste as a re-sult of solvation of the resin particles by the plastici-zer. This paste gels and fuses when heated to about 300F.
If a volatile solvent is included in the plastisol, then 25 the adhesive generally is referred to as an organosol, which also is suitable for US2 in the invention.
In order to form the final pressure sensitive, composite article of the present invention, the exposed side of backing 13 is coated with a substantially contin-30 uous layer 16 of a suitable tacky, pressure sensitive ad-hesive~comprising adhesive 18 and metallic flakes 17, such as described above in connection with Component No. 2 in Figure 1.
The product shown in Figure 2 can find utility CIP of C-5016 without the presence of release liner 19, for e~ample, if it is used shor-tly aEtex application of the adhesive lay-er, and care is taken to avoid contamination of the ex-posed surface of the adhesive layer 16 with foreign matt~r.
If this embodiment of the invention is desired, the adhes-ive in the form of a viscous fluid can be cast onto the backing 13 and dried by the application o~ heat. In most - end uses however, -the composite article will be manufac-tured with a suitable release liner 19 by a manufacturer, and the product will be sent to a customer for use.
The release liner 19 may be any of the release liners known to persons of ordinary skill in the art of making pressure sensitive products. One preferred liner material is silicone coated release paper having a thick-ness of from about Q.05 mm. to about 0.25 mm. Polyole-finic ~e.g., ethylene), ethylene/vinyl acetate copolymer, ethylene/acrylic copolymer, and ethylene/chlorinated poly-ethylene blends which have been suitably release coated, e.g., with a silicone release agent, may also be employed as release liners.
A preferred process for affixing the film 11/
backing 13 combination and the pressure sensitive adhes-ive layer 16 and release liner 19 comprises transfer lam-ination~ In such a process, a solvent solution, an aque-ous dispersion, or a hot melt of the adhesive layer 16 is applied to the release liner 19, and the resulting compos-ite (except when a hot melt technique is used3 is heated to dry the adhesive layer 16. The adhesive side of this adhesive/linex laminate is then lamina~ed to the exposed sur~ace of the backing 13, preferably at a heat lamination nip,~to form the product shown in Figure 2. The use of a heated nip insures good bonding between the adhesive layer 16 and the backing 13 which may have been treated with water repellents and/or corrosion inhibitors.

.7 CIP of C-5016 Besides transfer laminatlon, the adhesive layer 16 can be applied to the backing by use of conventional direct application methods using either knife, roller, reverse roller or extrusion coating techniques provided a substantially continuous and uniform coating of pres-sure sensitive adhesive results.
The Examples which follow will illustrate cer-tain embodiments of the present invention:

This Example illustrates a procedure for form-ing a decorative pressure sensitive product in accordance with the present invention.
A transparent, plasticized polyvinyl chloride (PVD) film was heat laminated to itself on a lamination machine by passing two layers of such film over a series of hot drums in order to achieve a heat seal temperature of about 149C. The PVC film was simultaneously embossed on one side with a brushed silk pattern at the lamination point. The film that resulted had a thickness of about 0.2 mm.
An adhesive formulation was then prepared which comprised 100 gm. of a 30%, by weight, solids acrylic pressure sensitive adhesive polymer and 3 gm. of a non-leafing, finely divided aluminum flake. The adhesive that was used was a high molecular we~ght thermoplastic acrylic terpolymer available as "Durotak 80-1053" from National Starch and Chemical Corp. The aluminum flake that was used is commercially available from Alcan Metal Powderr Inc. as "Grade MD-3100"~
The adhesive and aluminum flake were mlxed to-gether for from about 5 to about 10 min. at high speed to effectively disperse the aluminum flake particles. Th~

,~ , 70 ~.7 CIP of C-5016 adhesive/aluminum flake composition was then coated onto silicone coated release paper usin~ a laboratory coating blade. Removal of -the volatiles from this coated layer was accomplished by drying the layer for 2 mirlutes at 121C. in an oven. The dried adhe~ive thickness was about 0.03 mm.
The resultant adhesive coated release paper was then laminated to the unembossed side of the transparent PVC film by passing both the film and release paper through a laboratory nip roller at sufficient pressure to insure intimate contact of the adhesive with the film.
This PVC film/adhesive/release liner laminate was then conditioned for 16 hours at laboratory ambient conditions to allow the adhesive to form a strong bond to the film.
The opacity and aesthetics of the laminate were judged to be satisfactoxy~
Peel adhesion of the product was then deter-mined by bonding 2.5~ cm. strips of the PVC/adhesive lam-inate (after removal of the release liner) to a stainless steel panel using the standard Pressure Sensitive Tape Council 2.04 kg. roller. Peel adhesion at 180 was then measured after a 24 hour wetout or "dwell" period on a Thwing-Albert type tester. The value achieved was about 1.34 kg. per linear cm. ~irtually all of the adhesive remained on t:he film thereby demonstrating both high ad-hesive strength to the film and high cohesive strength, the former being of more importance when the product is to be used as a permanent decorative film on a desired substrate.
A Control laminate, lacking the aluminum flake, yield~ed a peel adhesion of only 0.9~ kg. per linear cm.
One advantage of the aluminum flake containing laminate as compared to the control laminate was the greater ease of repositionability that it exhibited. r~'he Y

~l~lZ';~7 .

CIP of C-5016 presence of the flake reduced the "quick grab" of the ad-hesive allowing or initial repositioning of the l~mlna~e.

In another experiment, two other lea~iny, rath-er than non-leafing, aluminum flakes ("Grade MD-2100" and "Grade MD-5100" from Alcan Metal Powder, Inc.) were tried in similar amounts but they produced poor adhesion of the adhesive to the vinyl film when tested as above after 20 min. and 2~ hr. dwell times on the substrate. Th~ results of all tests are set forth in the Table which follows. All values are given in kg. per linear (abbreviated "1".) cm.

Stainles_ Steel Adhesion No. Metallic Flakes 20 min. Dwell 24 hr. Dwell l. None (control) 0.43 0.82

2. Non-leafingl 0.58 1.61

3. Leafing 0.58 0.8 ~. Leafing 0.82 1.07 1) "Grade MD-3100" from Alcan Metal Powder, Inc.
2) "Grade MD-2100" from Alcan Metal Powder, Inc.
3) "Grade MD-5100" from Alcan Metal Powder, Inc.
Each of the above samples had the following peel adhesions ~in kg./l.cm.) after one minute: No. l:
0~63; No. 2: 0.23; No. 3: 0.43; and No. 4: 0.52. No. 2, the product of this invention, has the lowest initial tack but the highest adhesion after 24 hr. dwell times.
After 20 minutes, when the film/adhesive lam-inates were peeled back from the panel, product Nos. l and 2 showed no transfer of adhesive to the plate from the ~film whereas products Nos. 3 and 4 showed transer of adhesive. After 24 hours, product No. l showed no transfer, product No. 2 showed cohesive failure of the adhesive as illustrated by adhesive remaining on both film and panel, and products Nos. 3 and 4 showed fail-ure of the adhesive to the film as illustrated by most 7r~

CIP of C-5016 of the adhesive being left on the panel. In those end uses where the product is to be left permanently on the object, these observations are merely of interest as to how the in-ternal strength of the adhesive (cohesive strength) and bond strength of aclhesive to film and/or substrate (adhesive strength) are related. Adhesion strength would be unquestionably the most important property.

Approximately 1835 mete~s of a 0.01 mm. trans-parent PVC film was heat laminated to itself and was simultaneously embossed on one side with a shallow brushed silk roll.
An adhesive formulation was prepared by mixing 300 gm. of the acrylic adhesive used in Example 1, 15 gm.
of ethyl acetate, 15 gm. of toluene and 12 gm. of the non-leafing aluminum flake used in Example 1. The mix-ing was performed at high speed on a Cowles type dis-solver until the flake was completely dispersed in th adhesive solution. The viscosity of the formulation after mixing was about 2000 cps. (Brookfield viscosity 25C., No. 2 spindle,20 rpm~).
The adhesive formulation containing the alum-inum flakes was then applied to 90 pound basis weight, bleached kraft, silicone coated release paper using a re-verse roll coater. A streak-free, uniform coating of ad-hesive on the release paper was produced, and the adhes-ive coating was dried by passing the adhesive/release paper laminate through an oven at ~0C. for 40 seconds followed by passage through a second oven at 132C. for 45 seconds.
` This adhesive/release paper laminate was then laminated- to the unembossed side of the transparent PVC
film as described in Example 1.

CIP of C-5016 The resulting product was then tested against a control product that did not contain aluminum flakes in the adhesive using the test procedures described in Ex-ample 1. The adhesion at 180 was measured on stainless steel and lacquered panels using the same test method as described in Exampl~ 1. The results are given below in kilograms per linear centimeter:

Stainless Steel Adhesion Film 20 min. Dwell 24 hr. Dwell Film of this Invention 0.75 1.84 Control 0.61 1.18 The 20 min. dwell readings showed no adhesive transfer from the film to the substrate, whereas both 24 hour dwell readinys showed slight transfer using the same units given above:

Lacquer Painted Panel Adhesion Film 30 min. Dwell 24 hr. Dwell Film of this Invention 1.0 2.04 Control 1.0 1.16 At 30 minutes no adhesive transfer was noted for the film o~ this invention as compared to slight trans-fer for the control film. After 24 hours on the panels, both films showed cohesive failure as evidenced by trans-fer of substantial amounts of adhesive to the panel.
The films were also tested to determine the re-sistance by the adhesive to shrinkage of the vinyl film.
This~was evaluated by bonding a 2.54 cm. x 25.4 cm. ad-hesive coated film cut in the direction of travel of the film in the iaminator to an aluminum panel with a stand-ard 2.04 k~. roller. The ends of the film were scored ~L 12~ 7 CIP of C-5ol6 with a razor blade and a~ter a 2 hour wet out period at room tempera-ture the assembly was placed in a 121C. oven for 30 minutes. Growth o~ the razor cu~ was measu~ed with a magnifier after the film was cooled to room temper-ature. The film o this invention had a mounted shrink-age of only 0.0~ cm., whereas the control ~ilm had a shrinkage of 0.08 cm.

This Example compares the adhesion of a film of the present invention (Film A) to that exhibited by the type of decorative film known to the prior art (Film B).
Film A was an 0.2 mm. transparent polyvinyl chloride film that had been prepared by laminating two 1.0 mm. films togather followed by application of adhes-ive containing non-leafing aluminum flakes as described in Example l.
Film B was a 0.174 mm. transparent polyvinyl chloride film made by laminating a 0.075 mm. transpar-ent film to the vinyl side of a 0.10 mm. film that had previously ~een printed on one side with a silver ink for decorative purposes. The!same adhesive used in mak-ing Film A was applied to the silver ink side of the 0.175 mm. film without the presence of the aluminum flakes.
Both films were applied to lacquer painted stainless steel panels and the peel adhesion was mea-sured after the two films had been subjected to various environmental conditions for various len~ths of time.
The procedure described in Example l was employed to mount the films and measure the peel adhesion. The Table that is given below sets forth the results that were obtained in kg./linear centimeter:

3~

CIP of C~5016 - 20 ~

Adhesion of Film Condition Time A B
Room Temperature 72 hrs. 1.88 0.98 70C. 7 days 1.84 1.16 70C. 30 days 1.66 0.95 37.8C. ) 7 days 1.88 1.21 100% Relative) Humidity) These data demonstrate the uniformly highex ad-hesion values for the film of the present invention as compared to the type of film known to the prior art.

This Example illustrates the present invention with a plastic film/adhesive laminate containing an opaque plastic film.
The laminate of the present invention was first formed by initially forming the following adhesive formu-lation containing non~leafing aluminum flakes-IngredientParts by Wei~ht Acrylic Pressure Sensi-tive Adhesive Solution* lO0 Ethyl acetate 25 Isopropyl alcohol 25 Non-leafing aluminum flakes** 2 * ''GELVA RA 1753" from Monsanto Co.
** "Grade MD-3100" from Alcan Metal Powder, Inc.
The adhesive solution was knife coated onto re lease paper, was dried at 121C. and the release paper/
adhesive layer was laminated to an opaque polyvinyl chlor-ide film.- The adhesive layer was 0.02 mm. thick.
A similar proce~s was used to ~orm ~he Control film with the exception that the non-leafing aluminum CIP of C-5016 flakes were not used.
The two products were tested for 180D peel ad-hesion to stainless steel (as described in Example 1) after having been allowed to remain for 1 minute, 10 min-utes and 24 hours, respectively, on the substrate. The following values (in kg./linear cm.) were obtained with higher values being more desirable:
Film of the Peel Adhesion After Control Invention lO1 min. applied --- 0.51 lO min. applied 0.41 0.60 24 hrs. applied 0.60 1.14 The static creep resistance of each film was also measured. This is expressed as the time (in minutes) for the film/adhesive laminate to fall from the stainless steel substrate when a 1000 gm. load is attached to a sample having an area of 1.61 cm2. Higher numbers are more desirable. The film of the present invention had a value of 2493 min., whereas the control film only had a value of 520.1 min.
The 180 peel adhesion and static creep re-sistance were also measured after both laminates had been aged for 7 days at 70C. The following results were obtained. The peel adhesion values are given in units of 25 kg./linear cm. and the creep resistance value in minutes:
Peel Adhesion Film of this at 180 After ControlInvention 1 min. applied --- 0.04 10 min. applied 0.24 0.06 24 hrs. applied 0.~2 0.09 30Static CreeP
Resistance 47.7 342 The above Examples merely illustrate certain preferred embodiments of ~he present invention and should not be construed in a limiting sense. The scope of pro-tection which is sought is set forth in the appended claims.

Claims (19)

What is Claimed:

1. Pressure sensitive product having increased adhesion characteristics which comprises:
(a) a plastic film; and (b) a layer of pressure sensitive adhesive contain-ing non-leafing metallic flakes attached to the film, the amount of said metallic flakes in the adhesive being from about 5%, by weight, to about 20%, by weight of the adhesive layer.

2. A product as claimed in Claim 1 wherein the plastic film is a vinyl film.

3. A product as claimed in Claim 1 wherein the plastic film has a thickness of from about 0.05 mm.
to about 0.5 mm.

4. A product as claimed in Claim 1 wherein the pressure sensitive adhesive is an acrylic pressure sensitive adhesive.

5. A product as claimed in Claim 1 wherein the thickness of the adhesive is from about 0.013 mm. to about 0.05 mm.

6. A product as claimed in Claim 1 wherein the metallic flakes are aluminum flakes.

7. A product as claimed in Claim 1 which further comprises a release liner.

Cl of C-5016

8. A product as claimed in Claim 1 wherein the film is a vinyl film, the adhesive is an acrylic pressure sensitive adhesive and the product further comprises a release liner.

9. A product as claimed in Claim 1 wherein the flakes are aluminum flakes.

10. A product as claimed in Claim 1 which further comprises a backing material between the layer of pressure sensitive adhesive and film.

11. In combination, a pressure sensitive ad-hesive and non-leafing metallic flakes homogeneously dispersed throughout said adhesive, said metallic flakes being present at from 5%, by weight, to about 20%, by weight, of the adhesive and sufficient to confer increased adhesion on a plastic film laminate containing a layer of said adhesive after sufficient pressure is applied to the laminate to bond it to a substrate.

12. The combination of Claim 11 wherein the metallic flakes are aluminum flakes.

13. The combination of Claim 11 wherein the pressure sensitive adhesive is an acrylic pressure sen-sitive adhesive.

14. The combination of Claim 12 wherein the metallic flakes are present at from about 5%, by weight, to about 20%, by weight, of the adhesive.

15. The combination of Claim 11 wherein the metallic flakes are present at from about 10%, by weight, to about 15%, by weight, of the adhesive.

16. The combination of Claim 12 wherein the metallic flakes are present at from about 10%, by weight, to about 15%, by weight, of the adhesive.

CIP of C-5016

17. The combination of Claim 11 wherein the adhesive is an acrylic pressure sensitive adhesive and the metallic flakes are aluminum.

18. The combination of Claim 17 wherein the metallic flakes are present at from 5%, by weight, to about 20%, by weight, of the adhesive.

19. The combination of Claim 17 wherein the metallic flakes are present at from about 10%, by weight, to about 15%, by weight, of the adhesive.