GB2068833A

GB2068833A - Releasable, self-detackifying laminate construction

Info

Publication number: GB2068833A
Application number: GB8103701A
Authority: GB
Original assignee: Kimberly Clark Corp
Current assignee: Kimberly Clark Corp
Priority date: 1980-02-08
Filing date: 1981-02-06
Publication date: 1981-08-19
Also published as: FR2475459A1; IT8167167A0; DE3102850A1; JPS56127446A; NL8100594A; AU6669281A

Abstract

A laminated construction having differential release characteristics which will yield a self-detackifying adhesive surface upon delamination is produced by coating a film of a polymeric material (14) onto one side of a face stock material (10), optionally impregnated or coated with a release additive (12), and then laminating this construction to an adhesive (16) which has been coated onto a release liner (18). The release liner (18) is removed and the remaining portion of the laminate is affixed to a suitable substrate utilizing the exposed adhesive surface. The polymeric material (14) is chosen so that upon delamination of the face stock (10) from the substrate, it remains affixed to the adhesive coating. This results in a self-detackified adhesive surface on the substrate. The laminate construction is useful for tags, labels, stickers, and for sending credit, business, or membership cards on preprinted mailers to ultimate users. <IMAGE>

Description

SPECIFICATION Releasable, self-detackifying laminate construction This invention relates to a laminated construction having differential release characteristics, and more particularly to a laminated construction having a self-detackifying adhesive surface.

The use of multilayer, laminated paper or other foil stocks having a removable top lamina as tags, stickers, labels, and the like has become widespread in the art. One type of laminated construction presently used in produced by coating one side of a face stock with a release agent, such as a silicone based release agent. This coated stock is then laminated, release coated side down, to a paper base stock which has been coated on both sides with a pressure sensitive adhesive. The outer adhesive layer is protected by a silicone-coated release liner until the laminate is used.

By peeling off the release liner and affixing the outer adhesive layer to a suitable substrate, the laminated construction can serve a variety of purposes. Ultimately, the face stock can be delaminated from the rest of the construction by peeling it away from the adhesive layer on the base stock. The coating of the release agent on the face stock enables this separation.

However, problems have been encountered with this type of construction. Silicone-based release coating agents are difficult to apply to porous face materials to uniform thicknesses. This results in varying release characteristics and the splitting and transfer of a portion or all of the adhesive layer to the face stock when the face stock is attempted to be peeled away from the base stock. Moreover, since both the face stock and the release liners of conventional laminate constructions are coated with the same release agent, difficulties are encountered in removing the release liner from the construction without prematurely delaminating the face stock.

Finally, once the face stock is peeled off of the prior art laminate, a tacky, pressure sensitive adhesive surface is exposed on the base stock, face stock, or both. This tackiness makes further processing of the face and/or base stocks by automated equipment next to impossible.

Likewise, the problems associated with further processing by hand and ultimate disposal are enhanced by the tendency of the face and/or base stocks to stick to other documents, containers, and the like.

As can be seen, the need exists in the art for a laminated construction having controllable and predictable differential release capabilities. The need also exists for a laminated construction which does not result in the exposure and/or transfer of a tacky pressure sensitive adhesive layer when the face stock is peeled away from the base of the laminate.

The present invention meets that need by providing a self-detackifying adhesive laminated construction. According to one aspect of the present invention, a self-detackifying laminate construction is presented which includes a face stock sheet, a layer of polymeric material coating one side of said face stock sheet and adherent thereto, and a layer of adhesive material laminated to said layer of polymeric material and adapted to be adhered to a substrate, said face stock sheet including means for releasing said face stock sheet from said layer of polymeric material upon the application of a delaminating force less than the force required to separate said polymeric layer from said adhesive layer or said adhesive layer from said substrate, whereby upon the removal of said face stock sheet from said laminate construction, the polymeric layer is adhered to the substrate by the adhesive layer and a detackified adhesive surface is presented.

The laminated construction of the present invention is produced by coating a film of a polymer onto one side of a face stock and then laminating this construction to an adhesive which has been coated onto a release liner. The polymers should have differential release capabilities with respect to the face stock and adhesive.

By differential release capabilities, it is meant that while the polymer film will initially adhere both to the face stock on one side thereof and the adhesive on the other side thereof, upon delamination of the construction, the polymer film will have a greater affinity for the adhesive layer. That is, when the face stock is peeled away, the polymer film will delaminate from the face stock and remain permanently affixed to the adhesive coating. It is also differential with regard to the respective adhesive forces between the face stock and the polymer on the one hand and the adhesive layer and the release liner on the other hand. That is, the release liner should be less strongly adhered to the adhesive layer than the polymer is to the face stock.

In use, the release liner protecting the adhesive is removed, and the remaining portion of the preprinted laminated construction is affixed to a substrate by the exposed adhesive for use as a label, tag, sticker, business, membership, or credit card, or the like. When it is desired to remove the face stock from the remainder of the construction, such as for example the removal of a preprinted card from a larger substrate, the polymer will delaminate from the face stock and permanently remain on the adhesive coating.

This results in a substrate having a detackified adhesive surface (because only the polymer is exposed) which can be further used or processed either by hand or by automated equipment.

Moreover, the removed face stock is free from adhesive and can also be used or further processed. For example, a face stock can be preprinted as a business, membership, or credit card, affixed to a preprinted substrate, and sent to a customer. The customer can then remove the card by peeling it away from the remainder of laminated construction. The substrate surface now has a detackified surface which can be returned, by mail or otherwise, to the sender. The customer has a clean, nontacky card which can be placed in a wallet or purse and used as needed. Such uses would be impossible with prior art laminated structures since either the card, or the substrate, or both, would be covered with an exposed, tacky adhesive surface.

Accordingly, it is an object of the present invention to provide a laminated construction having a removable facestock which does not result in the exposure and/or transfer of a tacky adhesive layer when the face stock is peeled away from the base of the laminate. This and other objects and advantages of the invention will become apparent from the following description, the accompanying drawings, and the appended claims.

In the accompanying drawings Figures la-d are cross-sectional views of the laminate construction of the present invention illustrating the various layers of the laminate during manufacture and use.

In accordance with the present invention and with reference to Figs. 1 a-d, the laminated construction is produced by first coating a film of polymeric material 14 onto one side of a face stock 10 to produce a first subassembly 100. The face stock 10 may be made from such diverse materials as paper; plastic films, sheets, and foils; textiles; glass; and metal foils and sheets. If paper or other porous material is used as the face stock material, then it is desirable to incorporate into or coat onto such paper or other material a release additive 1 2.

Preferably, this release additive 1 2 is also a polymeric material which can be either incorporated into the stock or coated onto it as shown in Fig. 1 a. Many different polymeric materials may be utilized. The only limitation is that the polymer chosen must be able to release the face stock from the film of a second polymeric material which is interposed between the face stock and adhesive when a delaminating force is applied. That is, the combination of polymers chosen must adhere to the face stock and adhesive layer, respectively, better than they adhere to each other.

An example of such a release system which has found to be suitable in the practice of the present invention is polyethylene and polyvinylidene chloride. By coating a paper stock with a film of polyethylene and then overcoating that film with a film of polyvinylidence chloride prior to laminating the face stock with an adhesive, a release system is produced which will delaminate at the polyethylene-polyvinylidence chloride interface when the face stock is peeled away. Because the film of the second polymer, in this case polyvinylidence chloride, remains adhered to the adhesive layer, a detackified adhesive surface is produced when the face stock is peeled away.

Other examples of suitable release systems include polystyrene coated paper having a polyvinylbutyral film overcoated thereon, polyvinylchloride coated paper having a polyvinylalcohol film overcoated thereon, and polyester coated paper having a polyacrylate film overcoated thereon. Of course, other release systems can be readily devised by one skilled in the art. The coating weights of the polymers utilized can vary over a wide range of from less than 0.453 kg/ream (306.6 sq m) (1 Ib/ream (330 sq. ft.)) to 6.8 or more kg/ream (15 or more Ib/ream).

The lower end of the range is determined by the ability to achieve a continuous, uniform coating at a low coating weight while the upper end of the range is principally determined by material costs. If a non-porous face stock is utilized, then coating its surface with a first polymeric material may be eliminated. But as in the case of a coated paper face stock, the face stock must be less adherent to the polymer than the polymer is to the adhesive layer.

The adhesive 1 6 used in the present invention can be any pressure sensitive type adhesive, a heat activated adhesive, a water remoistenable adhesive, or a thermosetting type adhesive.

Preferably, solution, water based or hot melt pressure sensitive type adhesives are utilized because of their ease of handling and application. Examples of pressure sensitive adhesives useful in the practice of the present invention include styrene isoprene block copolymers, acrylic ester-vinyl acetate copolymers, ethylene-vinyl acetate copolymers, suitably plasticized vinyl acetate homopolymers, rubber-latex resin emulsion systems, and acrylic copolymers which are composed of the various acrylate ester monomers known to produce pressure sensitive adhesives.

The solids content of the adhesives when coated may vary from about 35 to 100%. The viscosity of the adhesives may be adjusted by temperature variation or by suitable solvents, thinning with water or using compatible thickeners to give the optimum flow properties for smooth, uniform coatings. Preferably, the adhesive 1 6 is coated onto a release liner 18 to form a second sub-assembly 200 and the laminated to the polymer bearing side of the face stock sub-assembly 1 00. However, it is possible to coat the adhesive directly onto the polymer bearing side of the face stock assembly and then apply the protective release liner over it. The adhesive is generally applied to give a resultant coat weight of between 4.5 and 1 5.8 kg/ream (10 and 35 Ib/ream (3300 sq. ft.)).

The protective release liner 1 8 can be selected from a number of known and available papers having a release material coated onto one side of the paper web. The base paper of the release liner may be selected from krafts, super-calendered krafts, clay coated krafts, glassines, parchments, and other papers and films which have a suitable undercoating for release coating hold-out. The release coating may be any of the known materials used for their release properties for adhesives. Preferred types are silicones and modified silicones, the modification including both copolymerization of silicones with other nonrelease chemical agents or by adding nonsilicone materials to the silicone coating solution prior to application to the release base paper.Other release agents such as polyethylene, fluorocarbons, the Werner-type chromium complexes, and polyvinyl octadecyl carbamate may also be used. The choice of release coating is dependent on the tack, adhesion level and chemical nature of the adhesive.

The only requirement of the release liner 1 8 is that it be released from the adhesive layer 1 6 by a force much less than the force required to delaminate the face stock 10-12 from the polymer layer 1 4. This requirement is necessary to avoid premature delamination of the face stock when the protective release liner is peeled away. It has been found that a laminate construction having suitable release characteristics will be produced if the force required to delaminate the face stock from the polymer layer is at least 80 grams greater than the force required to peel off the release liner as measured by a Standard Tag and Label Manufacturers' Institute (TLMI) release and adhesive tester using a 50.8 mm (2 inch) width laminate and a 180 peel angle.

The present invention has the advantage that the face stock may be preprinted on one or both sides prior to lamination, or the outside face of the stock can be printed even after lamination to a substrate. Moreover, the substrate may be preprinted, including the area to be covered by the laminated construction, and that area will become visible and readable after removal of the face stock as long as a transparent or translucent polymer and adhesive are used.

The unique chemical divergence of the differential release system of the present invention (e.g., a face stock coated with a first polymer release agent and a second polymer layer interposed between the face stock and adhesive) permits easy and accurate control of the delaminating properties of the structure as opposed to prior art silicone release systems.

However, a significant major advantage of the present invention is that upon removal of the face stock as shown in Fig. 1 d, the adhesive layer 1 6 affixed to substrate 20 is permanently detackified. Thus, both the face stock sub-assembly 101 and substrate sub-assembly 201 can be further used or processed either by hand or by automated equipment.

The following nonlimiting example is provided to illustrate a method of making the laminated construction of the present invention.

Example An 8 point (49.8 kg/ream or 110 Ib/ream 3300 sq. ft.) tag face stock from the Union Camp Corporation was coated on one side with low density polyethylene by an extrusion process known in the art. A coat weight of 2.26 kg (5 lb) polyethylene per 306.6 sq m (3300 sq. ft.) ream was used. Next, a coating of polyvinylidence chloride having the following composition (all percentages by weight) was coated onto the polyethylene-coated side of the face stock from a water dispersed system.

Polyvinylidene chloride latex, Geon 652 from B.F. Goodrich Company 46.0% Wetting agent, Triton GR-7M, from Rohm and Haas Company 1.7% Thickening agent, Acrysol GS, from Ultra Adhesives, Inc. 0.3% Defoamer, Dee Foo 97-2, from Ultra Adhesives, Inc. 0.1% balance water 51.9% The viscosity of the coating was approximately 1400 cps, and it was applied at a coating weight of 2.26 kg/306.6 sq m (5 Ib/3300 sq. ft.) ream. The coating was applied by a wire wound rod directly to the low density polyethylene coating on a production coater using a #10 Mayer Rod and drying in an air circulating oven for 1-2 minutes at approx. 80"C (175"F). The coated stock was then wound on itself into a roll.

A pressure sensitive adhesive comprising a styrene-isoprene block copolymer, a terpene tackifying resin, hydrocarbon process oil, and an antioxidant was extrusion coated from a hot melt system onto a silicone coated release liner at a coating weight of 5.66-6.56 kg/306.6 sq m (12.5-14.5 lb/3300 sq. ft.) ream. The adhesive coated release liner was then laminated to the polyvinylidene chloride side of the face stock. The roll was then trimmed and slit into smaller rolls. Alternatively, if desired, the laminate could be cut into sheets.

Release values were determined using a TLMI release and adhesion tester. The silicone-coated release liner has a release value of 10-20 grams/50.8 mm (i.e. 2 inch) width when peeled from the adhesive layer at an angle of 180 at 762 cm (300 inches) per minute. After removal of the silicone-coated release liner, the adhesive coated stock was laminated to a substrate. The release value of the polyvinylidene chloride coating from the face stock was 100-120 grams/50.8 mm width when peeled at an angle of 180 at 762 cm per minute. The polyvinylidene chloride coating adhered to the adhesive coating resulting in a permanently detackified surface.

Claims

1. A self-detackifying laminate construction including, a face stock sheet, a layer of polymeric material coating one side of said face stock sheet and adherent thereto, and a layer of adhesive material laminated to said layer of polymeric material and adapted to be adhered to a substrate, said face stock sheet including means for releasing said face stock sheet from said layer of polymeric material upon the application of a delaminating force less than the force required to separate said polymeric layer from said adhesive layer of said adhesive layer from said substrate, whereby upon the removal of said face stock sheet from said laminate construction, the polymeric layer is adhered to the substrate by the adhesive layer and a detackified adhesive surface is presented.

2. A laminate as claimed in claim 1 in which said polymeric material is polyvinylidene chloride and said releasing means comprises a coating of polyethylene on said face stock.

3. A laminate as claimed in claim 1 in which said polymeric material is polyvinylbutyral and said releasing means comprises a coating of polystyrene on said face stock.

4. A laminate as claimed in claim 1 in which said polymeric material is polyvinylalcohol and said releasing means comprises a coating of polyvinylchloride on said face stock.

5. A laminate as claimed in claim 1 in which said polymeric material is a polymer of acrylic acid and said releasing means comprises a coating of a polyester on said face stock.

6. A laminate construction including a face stock sheet, a substrate, and a layer of adhesive therebetween, characterized by means interposed between said face stock sheet and said layer of adhesive for releasing said face stock sheet from said adhesive when a delaminating force is applied to said face stock sheet, said interposed means including means for permanently detackifying the surface of said layer of adhesive.

7. A laminate as claimed in claim 6 in which said detackifying means comprises a film of a first polymeric material covering said adhesive layer and said interposed means comprises a layer of a second polymeric material coated onto said face stock sheet.

8. A self-detackifying laminate construction comprising, a face stock sheet, a layer of adhesive, a release liner adhered to said layer of adhesive, and means interposed between said face stock sheet and said layer of adhesive for releasing said face stock sheet from said adhesive when a delaminating force is applied to said face stock sheet, the delaminating force required to remove said face stock sheet from said layer of adhesive being at least 80 grams/50.8 mm width greater than the force required to remove said release liner from said layer of adhesive.

9. A laminate as claimed in claim 8 in which said interposed means include means for permanently detackifying the surface of said layer of adhesive upon delamination of said face stock sheet.

1 0. A laminate as claimed in claim 9 in which said interposed means comprises a layer of polymeric material.

11. A self-detackifying laminate construction substantially as hereinbefore described with reference to the accompanying drawings.