Patent GB-497788-A (GB)
Title: Improvements in shaped bodies, such as thin sheets, threads or the like, composed essentially of rubber hydrochloride and methods of producing such bodies
IPC: D01F6/24
Filed: 1937-04-26
Abstract: 497,788. Halogenated rubber ; compound sheet materials ; yarns etc.; catgut substitutes. MINICH, H. D. April 26, 1937, No. 11922. Convention date, April 30, 1936. [Class 70] [Also in Groups VIII, IX, and XXV] Rubber hydrochloride bodies, particularly in the form of thin sheets or threads, are heated to a temperature at which they are plastic (150-230‹ F.), stretched in one or more directions, and cooled while stretched to solidification temperature ; this makes them stronger, more resilient, more tear-resistant, lustrous and crackly. A film may be stretched to 2-6 times its original length. The process may be repeatedly applied to a sheet or to a plurality of sheets. Transparent strips 21 and narrow red strips 22 are assembled in a funnel 30, passed over a heating cylinder 32, under an auxiliary heater 41, and through a cooler 34, and stretched by rollers 35 which rotate faster than rollers 31. The strips fuse into a homogeneous strip. The slots 28 in the assembly plate 27 and the exit end of the funnel 30 may be narrower than the widest sheet fed therethrough, so that the edges of the said sheet are rolled over and beads are formed on the finished article. The surface of the cylinder 32 may be grained or ribbed, and the surface of one or both of the idler rollers 42, 43 may be provided with ornamental or other designs. One or more of the intermediate layers may be imprinted or perforated. The relative speeds of the sheets may be varied, e.g. by rotating the upper of the rollers 35 or 31 at a higher or lower speed than the lower. The drive of the heating cylinder 32 may be correlated with the drive of the rollers 31 or 35 or both. In making laminated coalesced films coloured films may be placed above, below or between other films, e.g. between transparent films ; opaque films may be placed under or between one or more coloured or transparent layers. Several films which have been stretched laterally and longitudinally are superposed in crosswise grain directions and again stretched and fused together under pressure ; longitudinal ribs may be produced in such laminations by inserting between the films, before stretching, narrow unstretched strips. A sheet is obtained by coalescing superposed layers of stretched and unstretched material while they are being stretched and heated to a plastic state and releasing them while they are plastic ; a strip having a crinkled central surface and ruffled edges may be obtained by thus treating two narrow pre-stretched strips enclosed between two wider unstretched strips. Compound sheet or strip material may be used in making shower curtains, raincoats, table covers, umbrella coverings, wall covering, packing material and dress goods. Narrow untreated strips may be rolled back and forth as they are moved over a heated surface and stretched as they are drawn away from it ; the thread so produced may be used as a substitute for gut for surgical sutures, musical strings, stringing racquets, leaders in angling and fishing lines and nets. Several ribbons of the rolled stretched material may be twisted together while being heated and stretched. A strip of untreated material may be twisted with a strip of pre-stretched material while the two are heated and stretched. The rubber hydrochloride may be made by dissolving 5 to 7 parts of rubber in 100 parts (by weight) of a solvent, e.g. benzene, and maintaining the solution at 50‹ F. for 6 hours while dry HC1 gas is passed through it. The treated solution is left for 24 hours at room temperature and the solvent and excess HC1 are then driven off by steam distillation or by passing nitrogen or air through the solution. The mass is washed with ammonia solution and water and the residual mass of rubber hydrochloride and ammonium hydrochloride is dried under vacuum. A film is obtained by making a 5 per cent by weight solution in, e.g. chloroform, which may contain a dye (or opaque, insoluble colouring matter) and an age-resister, e.g. cyclohexylamine formaldehyde, running the solution on to a moving belt surfaced with cellulose acetate or celluloid, removing the solvent by passing a stream of air over the surface and continuously stripping the film from the belt. Alternatively the rubber hydrochloride may be made by subjecting thin sheets of washed, milled, pale crepe rubber to the action of dry HCl gas at pressures up to 8 atmospheres at 180‹ F. for 12 to 48 hours, releasing the residual free HC1 and removing all traces of HC1 by heating under vacuum. In a third method, washed, milled, crepe rubber is treated with dry, liquid HC1 at low temperature, the required high pressure effecting hydrochlorination almost instantaneously. The Specification as open to inspection under Sect. 91 comprises also the application of the invention to bodies made of halogenated and hydrohalogenated butadiene bodies in general, e.g. the products of the reaction of HBr, HI, chlorine, bromine and iodine with rubber, guttapercha, balata, isoprene, erythiene, " chloroprene '' and the substance known under the Registered Trade Mark " Duprene." This subject-matter does not appear in the Specification as accepted.