GB546746A - Manufacture of transparent sheet material - Google Patents

Abstract

546,746. Synthetic resin compositions and articles ; films &c. DU PONT DE NEMOURS & CO., E.I. and HERSHBERGER, A. Jan. 27, 1941, No. 1042. [Classes 2 (ii) and 2 (iii)] Films or sheets are made from compositions of polyvinyl butyral resins plasticized with castor oil. The films may be made of a thickness of 0.001-0.002 inches, and the plasticizer may be used in amounts up to about 30 per cent. of the composition. The castor oil may be blown or unblown. A stabilizer may be incorporated to prevent the castor oil from going rancid. The stabilizer may be #-naphthol, phenyl salicylate, eugenol, creosole, guaiacol, syringic acid, catechol mono-lauryl ether, o-hydroxydiphenyl, diphenylamine, or tetrahydrophenyl-#-naphthylamine. The composition may be dissolved in a solvent such as methanol, acetone, ethyl formate, or a mixture of methanol and benzene, or methyl acetate and methanol. The films have good flexibility, tear resistance, and wear resistance. They may be stitched or sewn when making garments or other articles. They may be used as wrapping material or for making bags, shower curtains, bridge-table covers, umbrellas, parasols, raincoats, and mittens. The articles may be provided with perforations resistant to tearing to permit ventilation of enclosed goods or to permit access of liquid as in the case of tea infusion bags. In an example, a film is cast from a solution of polyvinyl butyral (containing hydroxyl and a small amount of acetyl), castor oil, and methanol. In another example, polyvinyl isobutyral is used. Specification 416,412 is referred to.