NO782577L - PRESSURE SENSITIVE, COMPOSITE SHEET MATERIAL - Google Patents

Description

Pressure-sensitive, composite sheet material

The present invention relates to a compound

article of plastic film/flexible backing coating, which is pressure-sensitive and which can, for example, be used as roofing material on

cars, the method of applying it to a desired substrate and the resulting substrate/article combination.

Composite articles of plastic film and flexible backside coating which are, for example, suitable as roof material on vehicles, for example cars, are known products. Such composite materials are used for other things, for example as padded wall coverings, lining material for car trunks, etc., but will be described here in connection with their primary commercial use as roofing material for motor vehicles, such as cars.

Such composite articles are usually sold, when used as vehicle roofing materials, to the vehicle manufacturers without any adhesive layer, and the manufacturers spray contact adhesive on the exposed side of the backing material in the car factory and then attach the sprayed composite article to the vehicle underlay which is also covered with the same adhesive (see U.S. Patent 3,935,353, column 1, lines 31-45). Contact glue is glue that must be applied to both surfaces to be bonded together. They cannot be considered to be "pressure sensitive" adhesives as that term is used here. Such a technique has many serious drawbacks. Spraying solvent-based adhesives in the car factory can cause potentially serious safety/health problems in the surroundings. The technique is very time-consuming and involves the use of more labor than desired. Spraying adhesive on the backside can also result in an uneven and interrupted adhesive coating on the backside, leading to the formation of voids between the backside coating material and the vehicle roof. Which can lead to corrosion problems when the finished vehicle is put into traffic.

An alternative to this conventional method is described in U.S. Patents 3,846,200 and 3,935,353. In these patents, a plastic film/flexible backing coating product containing a layer of a non-pressure-sensitive, heat-activatable adhesive is proposed. Such a product, although it overcomes some of the shortcomings encountered in the conventional technique of spraying in the factory, also has certain disadvantages. One of the most serious is the need for heating devices in the automotive assembly area to heat the adhesive to its heat-activatable temperature at which tackiness occurs. This may require further unwanted capital investment for the car manufacturer. In addition, plastic film material in such a technique must be pre-formed in a press with heat before application to ensure correct adaptation.

The present invention relates to a pressure-sensitive, composite article suitable for use, for example, as a roof material on vehicles, which when used as such a covering material, overcomes the shortcomings indicated above with solvent-sprayed contact adhesive constructions and constructions containing a heat-activatable adhesive. It comprises a plastic film attached to a backing coating material having a substantially continuous and uniform coating of a pressure sensitive adhesive on the side furthest from the plastic film and, as in a preferred embodiment, also having the exposed surface of the adhesive layer covered by a release coating to protect this layer from contamination. The present invention also includes a method for attaching such a laminate to a desired substrate, for example a vehicle, using only pressure, and it also includes the resulting combination of substrate/composite article.

The composite article according to the invention has, when

it is used as a coating material for vehicles, the following main advantages compared to the prior art using the spraying of solvent-based adhesives: elimination of the potential safety and health hazards for the environment that occur when potentially toxic solvents are sprayed in the workshop, a reduction of time and labor which required for applying the article to the vehicle, and a greater degree of protection against corrosion in the combination article/vehicle due to the presence of an essentially continuous and even layer of adhesive in the article according to the invention, so that a mainly continuous and smooth surface for

contact with the substrate.

The article according to the invention has the following main advantages when used as covering material for vehicles,

compared to the use of heat activatable adhesive as shown in U.S. Patents 3,846,200 and 3,935,35 3: heating the article after its application to a vehicle is not required to form an adhesive bond between the article and the vehicle substrate, and preforming the article in a heat press is not necessary.

The drawings that form part of the description can be used to better understand the composite article according to the invention, where: Figure 1 shows an enlarged cross-section of the closest known article where the discontinuous layer 6 of non-pressure-sensitive contact adhesive is sprayed onto the back coating -the material 3 in an assembly factory for vehicles, and

figure 2 shows an enlarged cross-section of a preferred embodiment of the present invention in which the release coating 8 is removed from the substantially continuous and uniform layer of pressure-sensitive adhesive 7 as the article is prepared to be attached to a desired substrate, for example a vehicle roof .

The composite article according to the invention comprises some elements which are old, namely the plastic film 1 as well as the flexible backing coating 3, which is attached to the film 1. A suitable adhesive 2, for example a plastisol adhesive, can be used to attach the plastic film 1 to the backing material 3, if desired, and this adhesive layer is also sometimes used in film 1/back coating 3 articles known in the art. Any person skilled in the art will be able to select suitable materials for the production of such a film/back-coating combination (possibly combined with adhesive) from the description that follows.

The plastic film 1 can be formed from any thermoplastic or thermosetting synthetic polymer which is preferably resistant to weather and ultraviolet light, as well as providing a long useful life for the composite article if it is to be attached to a vehicle and used as a covering material. Representative plastic film materials include vinyl and vinylidene, acrylic, urethane, polyester, fluorocarbon and polyolefin polymers and compatible blends thereof. Preferred vinyl chloride polymers may be any of the conventional polyvinyl chloride resins heretofore used in such applications in combination with any desired and suitable plasticizers, fillers, stabilizers, pigments, fungicides, processing aids and the like. If desired, internally softened vinyl chloride polymers can be used instead of the combination of conventional vinyl chloride polymers and external softeners. The thickness of this plastic film will usually vary from approx. 0.13 mm to approx. 0.7 mm, although thinner as well as thicker films can be used, if desired. The film can be formed according to any technique known to those skilled in the art and usually provided with a suitable decorative pattern. It may be covered with a thin protective polymeric outer layer (not shown), such as urethane, acrylic or vinyl polymer or compatible mixtures thereof, to protect it from degradation caused by mechanical, chemical and environmental factors.

The film 1 is attached to a backing coating which is roughly indicated by the reference number 3 in the figures. The attachment of the backside coating 3 to the film 1 can be carried out with the help of a thin layer of adhesive 2 or the film 1 can be attached directly to the backside coating 3 (for example by extruding or calendering the hot plastic film 1 on the backside coating 3) so that the attachment is carried out without the need for an intermediate layer of adhesive.

The back cover 3 can be selected from a number of back cover materials, such as non-woven, woven, knitted or composite materials (non-woven/foam combinations, non-woven/knitted combinations, non-woven/woven/knitted combinations , etc.) to provide a sufficiently thick layer that will assist in camouflaging any surface irregularities that may occur on the substrate, such as the vehicle roof, when the composite article is in place on the substrate. The term "backside coating" as used here shall indicate such backside coating materials which are well known to the person skilled in the art when it comes to the production of composite film/backside coating articles which are usable, for example, as outer covering materials for vehicles. Typically, the weight of the backing coating material will vary from 68 to 680 g/m 2 and its density from 32 to 320 kg/m 3 . The thickness of composite backing coating and film will usually vary from approx. 0.5 to 5.1 mm, preferably from approx. 1.4 to approx. 2.2 mm.

A preferred backing material due to improved customization options in the finished product,

are the commercially available backings of non-woven fabric

of synthetic fibers that are needle-punched into a thin foam layer. Some preferred examples of fibers that can be used in such backing coatings include: polypropylene, rayon, polyester, acrylonitrile, nylon, polyphenylene sulfide and mixtures thereof. Suitable foam materials that can be used include urethane and polyvinyl chloride foams. The denier for such fibers in this type of backing coating can vary from approx. 1 to approx. 20. "Denier" is defined as a unit of fineness equal to the fineness of a yarn weighing one gram for every 9,000 meters. The foam in such a back coating can have a thickness of from approx. 0.25 to approx. 2.5 mm.

The back coating 3 is preferably made water-repellent

by treatment with an effective amount of at least one water-repellent agent when the composite article according to the invention is to be used externally, for example as material on vehicle roofs. Fluorocarbon emulsions available under the trade names "Zepel" (from E. I. DuPont de Nemours Co.) or "Scotchguard"

(from 3M Co.), are representative types of materials that can be used to provide such water repellency. To process it

selected type of back coating material, it can for example be placed in a fluorocarbon bath, dried and the resulting product cured. The product obtained either by this or alternative treatment methods will resist wetting by water, oil and other contaminants * Further information on how the back coating 3 can be made water repellent can be obtained from "Waterproofing and Water Repellency", Kirk-Othmer Encyclopedia of Chemical Technology 2 ed., vol. 22, pages 135-156 (1970).

If desired, one or more corrosion inhibitors can be used to treat the backside coating 3 if the article is to be used externally, to provide or increase the corrosion protection of the article/substrate combination. The corrosion inhibitor can be any compatible inhibitor and can be applied in conjunction with the aforementioned water repellent. When, for example, a treatment with a fluorocarbon bath is used, such known corrosion inhibitors as nitrites, phosphates, chromates and sulfates can be present in the bath to act as corrosion inhibitors when the article is used externally in the final article/substrate combination that is produced. A corrosion inhibitor preferred for economic reasons is sodium nitrite. Additional information on how the back cover 3

can be treated to make the article/substrate combination corrosion resistant can be obtained from "Corrosion Inhibitors",

Kirk-Othmer Encyclopedia of Chemical Technology, 2nd ed., vol. 6, pages 317-346 (1965).

The composite article of film 1 and backing coating 3, which is known to the person skilled in the art, can be formed using a number of known methods such as direct calender lamination or extrusion coating, post-lamination or casting.

Direct calender lamination or extrusion coating provides a composite article without the use of the adhesive layer 2. The plastic film 1 acts as an adhesive because it is brought into contact with the backing coating 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 calendering lamination techniques in that the plastic film 1 is not usually formed just before the bonding step and an adhesive layer 2 is applied directly by known coating techniques (engraving cylinder, knife, roller, reverse roller, etc.) on the film before contacting the film with the backcoat 3. A roll of preformed film is usually the source of the film, and a thin layer of adhesive is applied to the side of the film to be bonded to the backcoat. The adhesive is applied in a suitable manner, usually in an amount in the range from approx. ■ 34 to approx. 170 g/m2 depending on the adhesive. The coated film is then brought into contact with the backing coating so that the composite article, which is known in the art, is formed.

Adhesives suitable for use in the post-lamination technique are well known to those skilled 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, commonly referred to as

softeners. Suitable softeners include phthalate, adipate and sebacate esters and polyols such as ethylene glycol and its derivatives. A typical plastisol consists of 50 parts polymeric material and 50 parts plasticizer, which forms a paste which

gels and which melts when heated to approx. 149°C as a result of solvation of the resin particles in the plasticizer. If a volatile solvent is mixed into the plastisol, the adhesive is usually referred to as an organosol, which is also suitable for use in the invention.

To form the finished, pressure-sensitive, composite article according to the invention, the exposed side of the backing coating 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 bond only when pressure is applied. Preferred adhesives of this class are those which exhibit good adhesion and. durability, when the article is to be used externally. Self-crosslinking, heat-curing, pressure-sensitive acrylic adhesives are a preferred class that can be used in the formation of the laminate according to the invention. U.S. Patents 3,269,994, 3,579,490 and 4,005,247 describe adhesives of this type. Preferred compositions are available under the trademarks "Aroset 1085" (Ashland Chemical Co.), "Bostik 7525" (USM Corp.) and - "DC-7025" (Daubert Chemical Co.). These adhesives have also been shown to have particularly good compatibility with backside coatings containing the water-repellent and/or corrosion inhibitor agents described above. The thickness of the adhesive layer in the composite article according to the invention can vary from approx. 0.01 mm to approx. 0.25 mm. The layer is deposited on the backside coating 3 so that it forms an essentially continuous coating which is also essentially free of voids, channels and the like. The presence of such a layer forms a barrier between the substrate and the atmosphere against moisture and other environmental factors which can cause corrosion when the article is used externally in the substrate/article combination.

The composite article according to the invention can be used without the presence of the release coating 8, for example if it is used immediately after applying the adhesive layer, and care is taken to avoid contamination of the exposed surface

surface of the adhesive layer 7 with foreign substances. If this embodiment of the invention is desired, the adhesive in the form of a viscous liquid can be cast on the back coating 3 and dried by applying heat. In most end applications, however, the composite article will be prepared with a suitable release coating 8 by the manufacturer, and the product will be shipped to the customer for use.

The release coating 8 can be one of the release coatings that are

known to those skilled in the art in the field of manufacturing pressure-sensitive products, including removable, water-soluble protective coatings and the like. A preferred release coating material is silicone-coated release paper with a thickness of from approx. 0.05 to approx. 0.25 mm. Polyolefins (for example of ethylene), ethylene/vinyl acetate copolymer, ethylene/acrylic copolymer and ethylene/chlorinated

polyethylene mixtures, which are suitably release coated, for example with a silicone release agent, can also be used as release coating.

A preferred method for attaching the film 1/back coating 3 combination and the pressure-sensitive adhesive 7

and the release coating 8 comprises transfer lamination. In such a method, a solvent solution, an aqueous dispersion or a hot melt of the adhesive 7 is applied to the release coating 8, and the resulting composition (except when a hot melt technique is used) is heated to dry the adhesive layer 7. The adhesive side of the adhesive The /release coating laminate is then laminated to the exposed surface of the backing coating 3, preferably by a heated laminating clamp, so that the product in Figure 2 is formed. The use of a heated clamp ensures good bonding between the adhesive layer 7 and the backing coating 3, which may be treated with water-repellent agents and/or corrosion inhibitors.

In addition to transfer lamination, the adhesive may be applied to the backing coating by conventional direct application methods using either knife, roll, reverse roll or extrusion coating techniques provided that a substantially continuous and uniform coating of pressure sensitive adhesive is achieved.

When the composite article according to the invention is to be used, the adhesive layer 7 is brought into contact with the vehicle substrate bg when properly positioned, pressure is applied to securely attach it to the vehicle. This process is performed without spraying solvent-based adhesives or heating the laminate/vehicle substrate combination.

The examples that follow illustrate certain preferred embodiments of the invention.

Example 1

This example illustrates how a preferred composite article according to the invention is produced.

First step in the production of the desired product

is calendering at a temperature of approx. 335°C of a film composition containing the following ingredients to a thickness of approx. 0.36mm:

A top coating in the form of a polymer solution in an amount of 0.57 kg/m 2 was then applied to the calendered film via the roller knife technique. The volatile solvent in the top coating solution was evaporated in a drying oven at a temperature of approx. 71°C and recovered without being released into the environment. The following ingredients form the top coating:

The top coated vinyl film was then laminated to a non-woven substrate with a plastisol adhesive and then a decorative pattern was applied at a temperature of approx. 160°C which also hardened the plastisol adhesive. The nonwoven substrate was an all-polyester blend of 60% by weight, 3 denier, 10.2 cm staple fibers; 20% by weight, 6 denier, 7.6 cm staple fibers; and 20% by weight, 6 denier, 15.2 cm staple fibers, which were needle punched into a polyester urethane foam having a thickness of 0.8 cm and a density of 32 kg/m 3 . The composite nonwoven/foam construction was fluorocarbon treated. It is a commercially available product from Foss Manufacturing and had a weight of 0.22 kg/m 2. The 0.8 cm foam was primarily applied to one side of the substrate, and it was this side that was laminated to the vinyl film.

The pressure-sensitive adhesive composition included these ingredients:

The composition was reverse roll coated at a rate of 0.16 kg/m on 43 kg/ream of polyethylene coated "kraft" release paper from H.P. Smith, Inc. The solvent was evaporated in a drying oven at 65-150°C and recovered. After drying, the release paper/adhesive composition 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 coating, the steel pinch roller at the lamination station was heated to approx. 85°C and placed against the release paper.

Example 2

The same procedure as in Example 1 was used for the production of a composite article where a commercially available adhesive from Daubert Chemical Company ("DC-7025") was used as the pressure sensitive adhesive, and this was used without dilution by the addition of additional solvent.

Example 3

The same method as in example 1 was used for the production of a composite article where a commercially available adhesive from USM Corp. was used. ("Bostik 7525") as pressure sensitive adhesive and this was used without dilution by addition of additional solvent.

The preceding examples illustrate preferred embodiments of the present invention and should not be considered as any limitation. The protection area sought is specified in the following requirements.

Claims (43)

1. Pressure-sensitive, composite article, characterized in that it includes: a) a plastic film, b) a thick backing coating attached to one side of the film, and c) a substantially continuous and uniform layer of a pressure-sensitive adhesive bonded to the side of the backing coating opposite the plastic film. 2. Product according to claim 1, characterized in that the film is a vinyl chloride polymer. 3. Product according to claim 1, characterized in that the film has a thickness of from 0.13 to 0.7 mm. 4. Product according to claim 1, characterized in that the film is attached to the back coating by an adhesive layer. 5. Product according to claim 4, characterized in that the adhesive is a plastisol adhesive. 6. Product according to claim 1, characterized in that the back cover is made of non-woven fabric. 7. Product according to claim 6, characterized in that the non-woven fabric also comprises a foam layer. 8. Product according to claim 1, characterized in that the weight of the back coating varies between 68 and 680 g/m. 9. Product according to claim 1, characterized in that the density of the back coating varies between 32 and 320 kg/m <3>. 10. Product according to claim 1, characterized in that the pressure-sensitive adhesive is a pressure-sensitive acrylic adhesive. 11. Product according to claim 1, characterized in that the adhesive layer has a thickness of from 0.01 to 0.25 mm. 12. Product according to claim 1, characterized in that it also comprises a release coating. 13. Product according to claim 12, characterized in that the back coating has a weight of from 68 to 680 g/m and a density of from 32 to 320 kg/m 3. 14. Product according to claim 1, characterized in that the back coating is treated with a compound selected from the group consisting of a water-repellent agent and a corrosion inhibitor. 15. Product according to claim 1, characterized in that the thickness of the film and the back coating varies between 0.5 and 5.1 mm. 16. Method for attaching a pressure-sensitive, composite article to a substrate, characterized in that: a) the product according to claim 1 is placed on the substrate, and b) the product is attached to the substrate by applying pressure only. 17. Method according to claim 16, characterized in that. the film in the product is a vinyl chloride polymer. 18. Method according to claim 16, characterized in that the film in the product has a thickness of from 0.13 to 0.7 mm. 19. Method according to claim 16, characterized in that the film in the product is attached to the back coating by means of an adhesive layer. 20. Method according to claim 19, characterized in that the adhesive in the product is a plastisol adhesive. 21. Method according to claim 16, characterized in that the back coating in the product is a non-woven fabric. 22. Method according to claim 21, characterized in that the non-woven fabric in the product also comprises a foam layer. 23. Method according to claim 16, characterized in that the weight of the back coating in the product varies between 68 and 680 g/m <2> 24. Method according to claim 16, characterized. in that the density of the back coating in the product varies between 32 and 320 kg/m <3> . 25. Method according to claim 16, characterized in that the pressure-sensitive adhesive in the product is a pressure-sensitive acrylic adhesive. 26. Method according to claim 16, part a, characterized in that the adhesive layer in the product has a thickness of from 0.01 to 0.25 mm. 21. Method according to claim 26, characterized in that the back coating in the product has a weight of from 68 to 680 g/m 2 and a density of o from 32 to 320 kg/m 3. 28. Method according to claim 16, characterized in that the backside coating is treated with a compound selected from the group consisting of a water-repellent agent and a corrosion inhibitor. 29. Method according to claim 16, characterized in that the thickness of the film and the back coating varies from 0.5 to 5.1 mm. 30. Combination, characterized in that it consists of a substrate and the product according to claim 1 securely attached to the substrate. 31. Combination according to claim 30, characterized in that the film in the product is a vinyl chloride polymer. 32. Combination according to claim 30, characterized in that the film in the product has a thickness of from 0.13 to 0.7 mm. 33. Combination according to claim 30, characterized in that the film in the product is attached to the back coating by means of an adhesive layer. 34. Combination according to claim 33, characterized in that the adhesive in the product is a plastisol adhesive. 35. Combination according to claim 30, characterized in that the back coating in the product is of non-woven fabric. 36. Combination according to claim 35, characterized in that the non-woven fabric in the product also comprises a foam layer. 37. Combination according to claim 30, characterized in that the weight of the back coating in the product is from 68 to 680 g/m <3>. 38. Combination according to claim 30, characterized in that the density of the back coating in the product varies between 32 and 320 kg/m <3>. 39. Combination according to claim 30, characterized in that the pressure-sensitive adhesive in the product is a pressure-sensitive acrylic adhesive. . 40. Combination according to claim 30, characterized in that the adhesive layer in the product has a thickness of from 0.01 to 0.25 mm. 41. Combination according to claim 35, characterized in that the back coating in the product has a weight of from 68 to 680 g/m 2 and a density of o from 32 to 320 kg/m 3. 42. Combination according to claim 35, characterized in that the back coating is treated with a compound selected from the group consisting of a water-repellent agent and a corrosion inhibitor. 43. Combination according to claim 35, characterized in that the thickness of the film and the back coating varies between 0.5 and 5.1 mm.