GB975458A - Carbon papers - Google Patents

Abstract

Compositions used in examples comprise: (Example 4) polycarbonate, polyester sebacate and methylene chloride; (Example 5) cellulose acetate-butyrate, mineral oil, carbon black, china clay, benzoquinone and methylene chloride; and (Example 6) polycarbonate, castor oil, carbon black, china clay, an amine of the formula <FORM:0975458/C3/1> where R is a low-molecular-weight alkyl group and R1 is a long-chain alkyl group, and methylene chloride. The composition of Example 4 is used to provide a reinforcing backing layer for carbon papers, and the other two to provide the transfer composition (see Division D2). Specifications 925,701 and 945,768 are referred to.ALSO:A waxless or substantially waxless carbon paper comprises a base sheet having on one side a layer of waxless or substantially waxless pressure responsive transfer composition bonded to the sheet by an intermediate bonding layer, and on the other side a reinforcing backing layer adhered to the base sheet. The transfer composition is such that colouring matter and oil can be expressed therefrom to form an image on a suitably disposed paper sheet upon application of pressure, e.g. from a typewriter key, to the backing layer. It may be that of Specification 925,701 or 945,768 or one comprising a soft vinyl polymer, colouring matter and oil. The base sheet may be of paper, textile fabric, or foils of regenerated cellulose, polyethylene terephthalate, nylon, cellulose esters, polyvinyl chloride, polyvinylidene chloride or polyvinyl chloride/acetate copolymers. The bonding layer may be transparent or opaque, made from a vinyl polymer such as polyvinyl acetate, polyvinyl acetal, polyvinyl ether, a polymer or copolymer of vinyl chloride, or a polycarbonate, and may contain dyes or pigments. The backing layer may a polycarbonate, a vinyl polymer, e.g. polyvinyl formal, polyvinyl chloride, polyvinyl chloride/acetate, polymethyl methacrylate or polystyrene, a cellulose ester, ethylcellulose, chlorinated rubber or polyvinylidene chloride. It may include a plasticizer, but is one for which oil and/or plasticizer of the transfer coating is not a solvent or solvent-plasticizer. It may contain a colouring matter or filler to give colour or opacity. The carbon paper may be made by coating tissue paper with a solution of the material for the backing layer, then, on the other side, with the bonding layer, and finally with a solution of the composition for the transfer layer.