Solventless release coating

Some additional requirements of the release coating may include the ability to write, print, or paint onto it, to provide quiet or smooth unwind, or to exhibit low coefficient of friction. There is also a trend towards the use of solventless release materials in the form of waterbased or 100% solids coatings. 

Silicone coatings represent about one-quarter of tape release coatings (in area) but completely dominate the release liner field. The most common liner substrate is kraft paper or, to a limited extent, polyethylene-coated paper. Silicone vehicles may be either solutions (by far the most common), or emulsions of selfcrosslinking poly(dimethylsiloxane) polymers which are coated and oven dried in a continuous operation. Solventless or 100% solids coatings have also been developed. Electron beam cured coatings, also solventless, may be accepted in the future but at present represent a very small part of the market. In-house production of release liners is conducted by many PSA tape and label manufacturers but most purchase liner stock from paper companies. 

Sihcone products dominate the pressure-sensitive adhesive release paper market, but other materials such as Quilon (E.I. du Pont de Nemours Co., Inc.), a Werner-type chromium complex, stearato chromic chloride [12768-56-8] are also used. Various base papers are used, including polyethylene-coated kraft as well as polymer substrates such as polyethylene or polyester film. Sihcone coatings that cross-link to form a film and also bond to the cellulose are used in various forms, such as solvent and solventless dispersions and emulsions. Technical requirements for the coated papers include good release, no contamination of the adhesive being protected, no blocking in roUs, good solvent holdout with respect to adhesives appHed from solvent, and good thermal and dimensional stabiUty (see Silicon COMPOUNDS, silicones). 

Ihe barrier mechanism not only decreases water permeating to the coatlng/metal interface but litewise retards the release of solvents from a coating. In order to avoid delayed film formation for this combination solventless paint systems are most suitable. 

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