GB1602233A

GB1602233A - Pressure-sensitive composite

Info

Publication number: GB1602233A
Application number: GB21665/78A
Authority: GB
Original assignee: Stauffer Chemical Co
Current assignee: Stauffer Chemical Co
Priority date: 1977-07-28
Filing date: 1978-05-23
Publication date: 1981-11-11
Also published as: JPS5425982A; DE2832343A1; YU183178A; IT7850476A0; DD137554A5; NO782577L; AU519508B2; AR221594A1; FR2398603A1; BR7804091A; NL7806262A; AU3632778A; SE7805814L; IL54748A; FR2398603B1; CA1144009A; IL54748A0

Description

(54) PRESSURE-SENSITIVE COMPOSITE (71) We, STAUFFER CHEMICAL COMPANY, a corporation organised under the laws of the State of Delaware, United States of America, of Westport, Connecticut 06880, United States of America; do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a pressure-sensitive composite; more particularly, it relates to a pressure-sensitive, plastic film/flexible backing composite article useful as, for example, a vehicle roof material, to the method of application thereof to a desired substrate and to the resulting substrate/article combination.

Plastic film, flexible backing composite articles suitable, for example, as a roofing material on vehicles, e.g. automobiles, are knwon. Such composite materials have other uses, for example as padded vinyl wallcoverings, and lining materials for automobile trunks, but will be described herein particularly in connection with the primary commercial use thereof as a roofing material for motor vehicles, such as automobiles.

Such composite articles for use as vehicle roof materials have conventionally been sold to the vehicle manufacturers without a layer of adhesive and the manufacturers would spray the exposed side of the backing material with a solution of a contact adhesive in the vehicle manufacturing plant and then affix the sprayed composite article to the vehicle substrate which had also been covered with the same adhesive (see U.S. Patent No. 3,935,353 Col. 1, lines 31-45). "Contact adhesives" are adhesives which must be applied to both surfaces that are to be bonded together. They cannot be considered to be "pressure-sensitive" adhesives as that term is employed herein. Such a technique has a number of serious disadvantages.

Spraying of solvent-based adhesives in the vehicle plant may give rise to potentially serious environmental/safety/health problems. The technique is rather time consuming and involves the use of greater amounts of manpower than desired. The spraying of adhesive onto the backing may also result in a non-uniform and discontinuous adhesive coverage of the backing leading to formation of voids between the backing and vehicle roof which may permit corrosion problems when the finished vehicle is placed in actual service.

An alternative to this conventional procedure is described in U.S. Patent Nos. 3,846,200 and 3,935,353. According to these references, a plastic film/flexible backing product containing a layer of non-pressure-sensitive, heat-activatable adhesive is proposed. Such a product, although overcoming some of the shortcomings of conventional in-plant spraying techniques also has certain drawbacks. One of the most serious is the need for heating means in the automobile assembly area to heat the adhesive to its heat-activatable temperature at which tackification occurs. This may require an additional undesirable capital investment fot the vehicle manufacturer. In addition, plastic film material in such a technique must be preformed in a press with heat prior to application in order to ensure the proper fit.

The present invention relates to a pressure-sensitive composite article suitable for use, e.g., as a roofing material on vehicles, which, when used to provide such a roofing material, overcomes the shortcomings noted above for solvent-sprayed, contact adhesive constructions and constructions containing a heat-activatable adhesive. The present composite comprises a plastic film which is attached to a non-woven fabric backing material which has a substantially continuous and uniform coating of a pressure-sensitive adhesive on the side thereof which is remote from the plastic film and, in a preferred embodiment, which also has the exposed surface of the adhesive layer covered with a release liner to protect this layer from contamination.The present invention also relates to a method of affixing such a laminate to a desired substrate, e.g., a vehicle, by application of pressure only, and it further relates to the resulting substrate/composite article combination.

The composite article according to the present invention, when used as a vehicle roof material, has the following major advantages over the prior art use of sprayed solvent adhesives: elimination of the potential environmental/safety/health hazards involved with spraying potentially toxic solvents in the workplace; a reduction in the time and manpower needed to apply the article to the vehicle; and a greater degree of protection from corrosion in the composite article/vehicle combination due to the presence of a substantially continuous and uniform layer of adhesive in the present article to provide a substantially continuous and uniform surface for contact with the substrate.

The article according to the present invention has the following major advantages, when used as a vehicle roof material, over the use of a heat-activatable adhesive such as shown in U.S. Patent Nos. 3,846,200 and 3,935,353: heating of the article after its application to a vehicle is not necessary to affect an adhesive bond between the article and the vehicle substrate; and performing the article in a heated press is not needed.

Referring to the accompany drawings: Figure I is an enlarged, cross-sectional view of the closest known prior art article showing the discontinuous layer 6 of non-pressure-sensitive, contact adhesive after the adhesive has been sprayed onto the backing 3 in a vehicle assembly plant; and Figure 2 is an enlarged, cross-sectional view of a preferred embodiment of the present invention as release liner 8 is being removed from the substantially continuous and uniform layer of pressure-sensitive adhesive 7 preparatory to affixing the composite article to a desired substrate, e.g. a vehicle roof.

The composite article according to the present invention comprises some elements which are known, namely, plastic film 1, as well as flexible backing 3, which is attached to film 1.

As suitable adhesive 2, e.g. a plastisol adhesive, may be used to attach plastic film 1 to backing 3, if desired, and this adhesive layer is also sometimes used in film 1/backing 3 articles known in the prior art. Those skilled in the art would be able to select appropriate materials for making such a film/backing subcombination (optionally joined with adhesive) from the description which follows.

The plastic film 1 may be formed of a thermoplastic or thermosetting synthetic polymer which is resistant to weathering and ultra-violet light so as to provide a long, useful life for the composite article should it be intended to be affixed to a vehicle and used as a roofing material. Representative plastic film materials include the vinyl and vinylidene, acrylic, urethane, polyester, fluorocarbon and polyolefin polymers and compatible blends thereof.

Vinyl chloride polymers are economically preferred. Preferred vinyl chloride polymers include the conventional polyvinyl chloride resins that have hitherto been used in such applications in formulation with, for example, desired and suitable plasticizers, fillers, stabilizers, pigments, fungicides, and process aids. If desired, internally plasticized vinyl chloride polymers may be used instead of the combination of conventional vinyl chloride polymers and external plasticizers. The thickness of this plastic film will generally be from 5 to 25 mils (from 0.13 to 0.7 mm.) although thinner, as well as thicker films may be used, if desired. The film may be formed by known fabrication techniques and is generally embossed with a suitable decorative pattern.It may be covered with a thin protective polymeric topcoat (not shown), such as a urethane, acrylic or vinyl polymer or compatible blends thereof, to protect it from degradation due to mechanical, chemical and environmental factors.

The film 1 is attached to a non-woven fabric backing which is broadly indicated by reference numeral 3 in the Figures. The attachment of backing 3 to film 1 may be made by means of a thin adhesive layer 2 or the film 1 may be directly attached to the backing 3 (e.g.

by extrusion or calendering of hot plastic film 1 onto the backing 3) so that the attachment is made without the need for an intermediate adhesive layer.

The backing 3 may be selected from a wide variety of backing materials comprising non-woven fabric, such as non-woven or composite materials (e.g. non-woven/foam combinations, non-woven/knit combinations and non-woven/woven/knit combinations) to provide a sufficiently thick layer which will aid in camouflaging surface irregularities that may exist on the substrate, e.g. vehicle roof, when the composite article is in position on the substrate. The term "backing" as used herein is to be construed as relating to such non-woven fabric backing materials which are well known in the art of making film/backing composite articles which are useful, for example, as exterior roofing materials for vehicles.

Generally the weight of the backing material will be from 2 to 20 oz/yd2 (from 68 to 680 gm./m2) and its density from 2 to 20 lbs/ft3 (from 32 to 320 kg/m3). The thickness of the backing and film composite will generally be from 20 to 200 mils (from 0.5 to 5.1 mm.), preferably from 55 to 85 mils (from 1.4 to 2.2 mm.).

A preferred backing material for reasons of improved tailorability of the finished product are the commercially available backings of a none-woven fabric of synthetic fibres which have been needle punched into a thin layer of foam. Some preferred examples of fibers which may be used in such a packing include: polypropylene, rayon, polyester, acrylonitrile, nylon, polyphenylene sulphide mixures thereof. Suitable foam materials which may be used include urethane and polyvinyl chloride foams. The denier of such fibres in this type of backing may be from 1 to 20. "Denier" is defined as a unit of fineness equal to the fineness of a yarn weighing one gram for each 9000 metres.The foam in such a backing may have a thickness of from 10 to 150 mils (from 0.25 to 2.5 mm.).The non-woven fabric backing 3 is preferably made water-repellent by treatment with an effective amount of at least one water-repellent agent when the present composite article is to have an exterior use, e.g. as a vehicle roof material. 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 may be used to confer such water-repellency. In order to treat the selected type of backing material, it may, for example. be placed in a fluorocarbon bath, dried and the resulting product may be cured.

The resulting product will resist being wetted by water, oil and other contaminants. Further information on how backing 3 might be rendered water-repellent may be ascertained from "Waterproofing and Water Repellency'', Kirk-Othmer Encyclopedia of Chemical Technology, 2nd Edition, Vol. 22, pp. 135-156 (1970).

If desired, one or more corrosion inhibitors may be used to treat the backing 3, if the article is to have exterior uses, in order to confer or enhance corrosion protection on the article/substrate combination. The corrosion inhibitor may be a known compatible inhibitor and may be applied in conjunction with the aforementioned water-repellent agent. For example, when a flurocarbon bath treatment is employed, known corrosion inhibitors, such as the nitrites, phosphates, chromates and sulphates, might be present in the bath to act as a corrosion inhibitor when the article is subjected to exterior use for the final article/substrate product combination. One corrosion inhibitor which is preferred for economic reasons is sodium nitrite.Further information on how the backing 3 might be treated to render the article/substrate combination corrosion resistant may be ascertained from "Corrosion Inhibitors", Kirk-Othmer Encyclopedia of Chemical Technology, 2nd Edition, Vol. 6, pp.

317-346 (1965).

The known composite article of film 1 and backing 3 may 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 2. The plastic film 1 acts as the adhesive because it is brought in contact with the backing 3 shortly after formation while the film 1 is still hot and sticky.

Post lamination is another well known method and differs from the extrusion coating or direct calender lamination techniques in that the plastic film 1 is not usually formed just prior to the bonding step and an adhesive layer 2 is applied directly by known coating techniques (e.g. gravure cylinder, knife, roller or reverse roller) to the film before the film is contacted with the backing 3. A roll of preformed film is generally 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 of from 1 to 5 oz./yd.- (from 34 to 170 g/m2) depending upon the adhesive. The coated film is then contacted with the backing to form the known composite article.

Adhesives suitable for use in the post lamination 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 are dispersions of finely divided polymeric materials in non-volatile organic liquids and low melting solids, generally referred to as plasticizers.

Suitable plasticizers include phthalate, adipate and sebaccate esters and polyols, such as ethylene glycol and derivatives thereof. A typical plastisol composition is 50 parts polymeric material and 50 parts plasticizer, forming a paste which gels and fuses when heated to about 300"F. as a result of solvation of the resin particles by the plasticizer. If a volatile solvent is included in the plastisol, then the adhesive is generally referred to as an organosol which also is suitable for use in accordance with the first invention.

In order to form the final pressure-sensitive, composite article according to the present invention, the exposed side of non-woven fabric backing 3 is coated with a substantially continuous layer 7 of a suitable tacky, pressure-sensitive adhesive. Pressure-sensitive adhesives are a well known class of adhesives and develop maximum adhesive bonding with the application of pressure alone. Preferred adhesives of this class are those which exhibit good adhesion and, when the article is to be used in exterior applications, outdoor durability. Self-cross-linking thermosetting acrylic pressure-sensitive adhesives are one preferred class which may be used in the forming of the laminate according to the present invention. Illustrative references describing adhesives of this type are U.S. Patent No.

3,269,994; 3,579,490 and 4,005,247. Preferred formulations are available under the trademarks "Aroset 1085" (Ashland Chemical Company), "Bostik 7525" (USM Corp.) and "DC-7025 (Daubert Chemical Co.). These adhesives have, moreover, shown to have especially good compatibility to backings containing the water-repellent and/or corrosion inhibitor agents described above. The thickness of the adhesive layer in the present composite article may be from 0.5 to 10 mils (from 0.01 to 0.25 mm.). The layer is deposited on backing 3 so that it forms a substantially continuous coating which is also substantially free of voids or channels. The presence of such a layer affords a barrier between the substrate and the atmosphere to moisture and other environmental factors which are prone to cause corrosion when the article is used in exterior applications in the substrate/article combination.

The composite article according to the present invention may find utility without the presence of release liner 8, for example, if it is used shortly after application of the adhesive layer and care is taken to avoid contamination of the exposed surface of the adhesive layer 7 with foreign matter. If this embodiment of the present invention is desired, the adhesive in the form of a viscous fluid may be cast onto the non-woven fabric backing 3 and dried by the application of heat. In most end uses however, the composite article will be produced having a suitable release liner 8 by a manufacturer and the product will be sent to a customer for use.

The release liner 8 may be one of the known release liners including removable, water-soluble protective coatings. One preferred liner material is silicone-coated release paper having a thickness of from 2 to 10 mils (from 0.05 to 0.25 mm.) Polyolefinic (e.g.

ethylene), ethylene/vinyl acetate copolymer, ethylene/acrylic copolymer and ethylene/ chlorinated polyethylene 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 1/backing 3 combination and the pressuresensitive adhesive 7 and release liner 8 comprises transfer lamination. In such a process a solvent solution, aqueous dispersion or hot melt of the adhesive 7 is applied to the release liner 8 and the resulting composite (except when a hot melt technique is used) is heated to dry the adhesive layer 7. The adhesive side of this adhesive/linear laminate is then laminated to the exposed surface of the non-woven fabric backing 3, preferably at a heated lamination nip, to form the product shown in Figure 2. The use of a heated nip ensures good bonding between the adhesive layer 7 and the backing 3 which may have been treated with water-repellents and/or corrosion inhibitors.

Besides transfer lamination, the adhesive may 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 pressure-sensitive adhesive results.

When the composite article according to the present invention is to be used, the adhesive layer 7 is brought into contact with the vehicle substrate and, when properly positioned, pressure is applied to securely affix it to the vehicle. This process is performed in the absence of spraying solvent based adhesives or heating the laminate/vehicle substrate combination. r The following Examples illustrate the present invention.

Example 1 This Example illustrates how one preferred composite article in accordance with the present invention was made.

The first step in forming the desired product was calendering at a temperature of about 335 C. a film formulation containing the following ingredients to a thickness of about 14.5 mils (0.36 mm.): Ingredient Percent, by Weight Polyvinyl Chloride Homo polymer Resin ........................................ 47.745 Calcium carbonate filler ...................................... 14.328 Normal alkyl phthalate plasticizer ........................................ 31.194 Fungicide/Plasticizer Stabilizer ........................................ 1.197 Epoxidized Soya Oil ........................................ 2.385 Colloidal Silica ........................................ 0.477 Heat stabilizer (Metallic soap) ............ ............ ............ 0.100 Pigment ........................................ 0.900 Barrium/Cadmium/Zinc Stabilizer ........................................ 1.197 Liquid Phosphite Stabiliser ....... ........................................ 0.477 To the calendered film was then applied via a roller knife technique a polymeric solution topcoat at a rate of 0.105 Ibs/yd2 (0.57 kg/m2). The volatile solvent in the topcoat solution was flashed off in a drying oven at a temperature of about 1600F. (71.1 C.) and recovered without release to the environment.The following ingredients formed the topcoat: Ingredient Percent, by Weight Methyl ethyl ketone . . 89.11 PVC Homopolymer Resin ................................... 7.61 Acrylic Resin ....... ......... ......... 2.70 Colloidal Silica ........................................ 0.58 The topcoated vinyl film was then laminated to a non-woven substrate with a plastisol adhesive and was in-line embossed with a decorative grain at a temperature of about 320 F.

(160 C.) which also cured the plastisol adhesive. The non-woven substrate was an all-polyester blend of 60%, by weight, 3 denier, 4 inch (10.2 cm.) staple fibres; 20%, by weight, 6 denier, 3 inch (7.6 cm.) staple fibres; and 20%, by weight, 6 denier, 6 inch )15.2 cm.) staple fibres; which had been needle punched into a polyester urethane foam having a thickness of 30 mils (0.8 cm.) and a density of 2.0 Ibs/ft (32 kg/m3). The composite non-woven/foam construction had been fluorocarbon treated. It is a commercially available product from Foss Manufacturing and had a weight of 6.5 oz/sq. yd. (0.22 kg/m2). The 30 mils (0.8 cm.) of foam was primarily on the one side of the substrate, and it was this side which was laminated to the vinyl film.

The pressure-sensitive adhesive formulation comprised these ingredients: Ingredient Percent by Weight Self-Cross-linkable Acrylic Pressure-Sensitive Adhesive Solution ("Aroset 1085") .................................... 77.77 Ethyl acetate solvent ........................................ 16.67 Toluene Solvent ........................................ 5.56 The composition was reverse roll coated at 0.3 lbs/yd2 (0.16 kg/m2) onto 94 Ibs/ream (43 kg/ream), polyethylene-coated, Kraft release paper from H.P. Smith, Inc. The solvent was flashed off in a drying oven at from 150 to 300 F. (from 65 to 1500C.) and recovered. After drying, the release paper/adhesive composite was laminated to the non-woven side of the non-woven/vinyl film construction.In order to achieve the desired degree of penetration of the adhesive into the non-woven backing, the steep nip roll at the lamination station was heated to about 185 F. (85 C.) and placed against the release paper.

Example 2 The same procedure as used in Example 1 was employed to make a composite article using as the pressure-sensitive adhesive a commercially available adhesive from Daubert Chemical Company ("DC-7025") which was used without dilution by addition of further solvent.

Example 3 The same procedure as used in Example 1 was employed to make a composite article using as the pressure-sensitive adhesive a commercially available adhesive from USM Corp.

("Bostik 7525") which was used without dilution by addition of further solvent.

WHAT WE CLAIM IS: 1. A pressure-sensitive composite which comprises: (a) a plastic film formed of a thermoplastic or thermosetting synthetic polymer which is resistant to weathering and ultra-violet light; (b) a backing comprising a non-woven fabric attached to the film on one side thereof; and (c) a substantially continuous and uniform layer of a pressure-sensitive adhesive bonded to the side of the backing which is remote from the plastic film.

2. A composite as claimed in Claim 1 wherein the film is a vinyl chloride polymer.

3. A composite as claimed in Claim 1 or Claim 2 wherein the film is from 5 to 25 mils thick.

4. A composite as claimed in any of Claims 1 to 3 wherein the film is attached to the backing by a layer of adhesive.

5. A composite as claimed in Claim 4 wherein the adhesive is a plastisol adhesive.

6. A composite as claimed in any of Claims 1 to 5 wherein the non-woven fabric backing also comprises a foam layer.

7. A composite as claimed in any of Claims 1 to 6 wherein the weight of the backing is from 2 to 20 oz/yd2.

8. A composite as claimed in any of Claims 1 to 7 wherein the density of the backing is from 2 to 20 Ibs/ft3.

9. A composite as claimed in any of Claims 1 to 8 wherein the pressure-sensitive adhesive is an acrylic pressure-sensitive adhesive.

10. A composite as claimed in any of Claims 1 to 9 wherein the adhesive layer from 0.5 to 10 mils thick.

11. A composite as claimed in any of Claims 1 to 10 further comprising a release liner.

12. A composite as claimed in any of Claims 1 to 11 wherein the backing has been treated with a water-repellent agent and/or corrosion inhibitor.

13. A composite as claimed in any of Claims 1 to 12 wherein the film and backing is from 20 to 200 mils thick.

14. A composite as claimed in Claim 1 substantially as herein described.

15. A composite as claimed in Claim 1 substantially as herein described with reference to the Examples and/or Figure 2 of the accompanying drawings.

16. A process for the production of a composite as claimed in Claim 1 which comprises attaching a backing to one side of a plastic film, optionally using an intermediate adhesive layer, and bonding a substantially continuous and uniform layer of a pressure-sensitive adhesive to the side of the backing which is remote from the plastic film.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. The pressure-sensitive adhesive formulation comprised these ingredients: Ingredient Percent by Weight Self-Cross-linkable Acrylic Pressure-Sensitive Adhesive Solution ("Aroset 1085") .................................... 77.77 Ethyl acetate solvent ........................................ 16.67 Toluene Solvent ........................................ 5.56 The composition was reverse roll coated at 0.3 lbs/yd2 (0.16 kg/m2) onto 94 Ibs/ream (43 kg/ream), polyethylene-coated, Kraft release paper from H.P. Smith, Inc. The solvent was flashed off in a drying oven at from 150 to 300 F. (from 65 to 1500C.) and recovered. After drying, the release paper/adhesive composite was laminated to the non-woven side of the non-woven/vinyl film construction.In order to achieve the desired degree of penetration of the adhesive into the non-woven backing, the steep nip roll at the lamination station was heated to about 185 F. (85 C.) and placed against the release paper. Example 2 The same procedure as used in Example 1 was employed to make a composite article using as the pressure-sensitive adhesive a commercially available adhesive from Daubert Chemical Company ("DC-7025") which was used without dilution by addition of further solvent. Example 3 The same procedure as used in Example 1 was employed to make a composite article using as the pressure-sensitive adhesive a commercially available adhesive from USM Corp. ("Bostik 7525") which was used without dilution by addition of further solvent. WHAT WE CLAIM IS:

1. A pressure-sensitive composite which comprises: (a) a plastic film formed of a thermoplastic or thermosetting synthetic polymer which is resistant to weathering and ultra-violet light; (b) a backing comprising a non-woven fabric attached to the film on one side thereof; and (c) a substantially continuous and uniform layer of a pressure-sensitive adhesive bonded to the side of the backing which is remote from the plastic film.

14. A composite as claimed in Claim 1 substantially as herein described.

17. A process as claimed in Claim 16 substantially as herein described.

18. A process as claimed in Claim 17 substantially as herein described with reference to the Examples and/or Figure 2 of the accompanying drawings.

19. A composite as claimed in Claim 1 when produced by a process as claimed in any of Claims 16 to 18.

20. A method of affixing a pressure-sensitive composite to a substrate which comprises: (a) placing a composite as claimed in any of Claims 1 to 15 or 20 in contact with the substrate; and (b) affixing the composite to the substrate by the application of pressure only.

21. A method a claimed in Claim 20 substantially as herein described.

22. A method as claimed in Claim 20 substantially as herein described with reference to the Examples and/or Figure 2 of the accompanying drawings.

23. A substrate having a composite as claimed in any of Claims 1 to 15 or 20 affixed thereto by a method as claimed in any of Claims 20 to 22.