GB401674A - Improvements in or relating to adhesive films - Google Patents

Abstract

Films or sheets of materials adapted to act as adhesives in the presence of humidity either in the materials to be joined or in the films or sheets themselves are manufactured by mixing adhesives such as caseinous or albuminous matters, glues or gums (either in the natural or hydrolysed state) with solutions or pastes of cellulose or cellulose derivatives and drying the mixture is such a manner as to furnish an adhesive film or sheet. Thus viscose solution may be mixed with a solution of casein or an albumen or hydrolysed glue or gum arabic, or a cellulose acetate or celluloid solution may be mixed with a non-aqueous solution of an adhesive or gum obtainable, for example, by dissolving casein p in a suitable solvent such as diluted pyridine or other organic or inorganic base and diluting the solution with a solvent such as acetone. For admixture with viscose solutions there is preferably used casein dissolved in an ammoniacal solution of urea or thiourea, but there may also be used solid or soaked casein or a casein extract from caseinous fruits such as the soya bean, also blood- or vegetable-albumin solutions, advantageously with the addition of glucose or treacle, and also with the addition of urea or thiourea if the mixture becomes too doughy. Hygroscopic materials may be added to the adhesive components of the films or to their supports, whilst other admixtures may be made to impart special properties to the films. The surfaces of materials to be joined may be treated with waterproofing agents such as formaldehyde, tanning or hardening matters such as tannic acid, alum, aluminium sulphate or lead salts, or fireproofing agents such as sodium phosphate. Specification 333,194, [Class 121, Starch &c.], is referred to. Reference has been directed by the Comptroller to Specifications 319,001, [Class 121, Starch &c.], and 345,222.