Release coating compositions are well-known in the art and are used extensively to coat substrates such as paper to provide release surfaces to which adhesive elements, such as labels or tapes can be adhered and from which said adhesive elements can be peeled or separated without damage to the adhesive or to the release surface or to the substrate. The release substrates and adhesive elements are united in order to prevent the adhesive elements, such as adhesive labels, adhesive tapes, adhesive floor tiles, or the like, from adhering to each other or to other surfaces from which they cannot be separated without tearing or breaking of the substrate or damage to the adhesive layer. The adhesive element-release substrate unit can be shipped, stored and handled without damage to the sticky adhesive layer, and they can be separated easily and cleanly by the ultimate user to permit the adhesive element to be permanently bonded to another surface.
Release coating compositions are known which are based upon curable organosilicon resins. Most commonly, such known compositions contain volatile organic solvents and are dried and cured by means of heating to elevated temperatures to evaporate the solvents and cure the organosilicon resins.
In order to reduce the cost and pollution inherent in the use of organic solvents, it has been proposed to use liquid vinyl containing organosilicon compositions which require no volatile solvent to form release coatings which are thermally-cured at elevated temperatures (reference is made to U.S. Pat. No. 4,216,252). Such coatings require relatively long dwell times and/or relatively hot ovens in order to produce a satisfactory cure of the release coatings, resulting in a waste of energy and/or a reduction in the line speed of the coating and curing operation.
It is also known to produce liquid vinyl organosilicon release compositions which do not require the presence of volatile organic solvents, and which are curable by means of exposure to radiation in the absence of applied heat. Reference is made to U.S. Pat. No. 4,052,529 which involves the use of siloxanes containing mercapto groups. Such release coatings are highly objectionable because of their bad odor. Moreover, they have slow curing rates and produce release coatings which are not suitable for use with strong adhesives. Reference is also made to U.S. Pat. No. 4,064,027 which relates to similar vinyl siloxane compositions which also have slow curing rates.
Examples of silicone release coatings which overcome the above-described disadvantages can be found in my commonly assigned and co-pending U.S. patent application Ser. Nos. 230,789, filed Feb. 2, 1981 and 230,475 filed Feb. 2, 1981.
USPTO Backgrounds
USPTO Backgrounds