This invention relates to an imagable clean release laminate construction, and in particular to a construction in which a releasable adhesive secures together two or more sheets which can be imaged through the use of chemical carbonless techniques.
Numerous types of businesses produce a wide variety of labels, nameplates, identification cards tags, forms, and the like in large quantities. Each such product typically has specific indicia printed thereon by high speed printing devices. It is desirable to produce such products on a continuous web, with individual labels, forms, or the like being adhesively attached to the web.
In the past, pressure sensitive adhesives have been utilized to secure the products to a continuous web during printing. Typically, labels or the like were attached to a silicone release liner by a pressure sensitive adhesive. Customarily when the pressure sensitive adhesive label was removed from the release liner, the label was attached to another surface by means of the tacky adhesive backing on the label.
However, in some instances, it is desirable to be able to have both surfaces of a label or the like, and also the surface of the web from which the label is released, to be clean and non-tacky. Such products are known as clean release products and are typically used as sew on labels, nameplates, and identification cards.
Previously, such clean release products have been made through the use of so-called releasable or fugitive adhesives. These releasable adhesives exhibit cohesive (internal) failure instead of the usual adhesive/adherend failure exhibited by typical pressure sensitive adhesives. These releasable adhesives are compositions which form relatively weak bonds but which adhere well to paper and other surfaces. Failure occurs within the releasable adhesive film itself when a layer of a laminate is subjected to peeling forces. This class of adhesives can be formulated to provide a range of cohesive strengths.
When cohesive failure occurs in such releasable adhesives a thin film of adhesive remains on the back surface of the face sheet, on the face of the backing sheet or both. However the film does not exhibit tack and has no adverse effect on the appearance or handling characteristics of the product. Moreover the surface can be readily printed on.
In some instances it is desirable to have a product which can be imprinted and which has the added function of providing one or more duplicate copies of the printed information. For example, Singer, U.S. Pat. No. 3,383,121, teaches a self-adhesive copy label which is affixed to a backer sheet by means of a pressure sensitive adhesive. Singer utilizes a multilayer structure which includes a self-contained carbonless sheet which produces the duplicate copy when the label is subjected to printing impact forces. However, in the Singer structure, care has to be taken to isolate the carbonless reactants from the pressure sensitive adhesive layer. Moreover, the labels of Singer have a tacky surface after delamination.
Likewise, Lockhart, U.S. Pat. No. 4,277,089, teaches the use of a removable label product which is adhered to a backer sheet through the use of pressure sensitive adhesive. The backer sheet itself comprises a self-contained carbonless product which provides a duplicate copy when the face sheet is subjected to impact printing forces. Like Singer the peelable label of Lockhart has a tacky surface.
Accordingly, the need still exists in the art for a clean release product which can provide a duplicate copy of information printed onto a face sheet or label and which can be readily removed from a laminate construction resulting in both a nontacky top sheet or label and a non-tacky web or backing sheet surface.