Patent GB-507247-A (GB)
Title: Improvements in the production of dressings or stiffenings
IPC: D06M15/333
Filed: 1938-01-08
Abstract: 507,247. Polyvinyl acetal resin compositions. WACKER GES - FUR ELEKTROCHEMISCHE INDUSTRIE GES., DR. A. Jan. 8, 1938, No. 625. Convention date, Jan. 9,1937. [Class 2 (iii)] Materials, e.g. for hats, are stiffened by treatment with a composition comprising a water-insoluble polyvinyl alcohol ester-acetal resin which is prepared from a polyvinyl alcohol or ester having a viscosity of 100 or lower and which contains 50-70 per cent acetal groups, 10 to 30 per cent ester groups, and 10 to 25 per cent hydroxyl groups or having a viscosity above 100 and which contains 40 to 60 per cent acetal groups, 25-50 per cent ester groups, and 5-15 per cent hydroxyl groups. (The viscosity is expressed as the time in seconds taken by a steel ball of 3 mm. diameter to descend 25 cms. through a 50 per cent solution in ethyl acetate, at 20‹ C.) The resins may be prepared by simultaneous saponification of a polyvinyl ester, e.g. acetate, and acetalization, e.g. with acetaldehyde ; or by acetalization of polyvinyl alcohol in the presence of a carboxylic acid, e.g. a volatile aliphatic acid such as acetic acid. Alternatively, water-insoluble polyvinyl alcoholester-acetals in general may be used, in conjunction with ethanol-soluble urea-formaldehyde resins, acetylated polyglycols or polyglycerols, bleached shellac, or interpolymers of vinyl compounds (e.g. esters) with drying or semidrying oils, or mixtures thereof. In examples : (1) mottled plait is treated with a solution in ethanol and ethyl acetate of a resin prepared from polyvinyl acetate of viscosity 100 and containing 52À5 per cent acetal, 27'2 per cent acetate, and 20À3 per cent hydroxyl groups ; (2) natural bleached straw plait is treated with a solution in ethanol, ethyl acetate, and toluene of a resin prepared from polyvinyl acetate of viscosity 5 and containing 67 per cent acetal, 15 per cent acetate, and 18 per cent hydroxyl groups ; (3) hats of viscose plait are treated with a solution in ethanol, ethyl acetate, and toluene of a resin prepared from polyvinyl acetate of viscosity about 100 and containing 47À5 per cent acetal, 43À7 per cent acetate, and 8À8 per cent hydroxyl groups; (4) a hat of felt braiding is treated with a solution in ethanol and ethyl acetate of bleached shellac and a resin prepared from polyvinyl acetate of viscosity about 1500 and containing 50 per cent acetal, 40 per cent acetate, and 10 per cent hydroxyl groups; (5) hats of viscose straw substitute are treated with a solution in ethanol, ethyl acetate, and toluene of polyglycerin acetate and a resin prepared from polyvinyl acetate of viscosity about 30 and containing 62À3 per cent acetal, 25À8 acetate, and 11À9 hydroxyl groups; (6) a hat of pedalin plait is treated with a solution in ethanol, ethyl acetate, and toluene of an ethanol-soluble urea-formaldehyde resin and a resin prepared from, polyvinyl acetate of viscosity about 70 and containing 40 per cent acetal, 40 per cent acetate, and 20 per cent hydroxyl groups ; (7) straw hats are treated with a solution in ethanol, ethyl acetate, and toluene of polyglycerol acetate and a resin prepared from polyvinyl acetate of viscosity about 500 and containing 65 per cent acetal, 25 per cent ester, and' 10 per cent hydroxyl groups.