Patent GB-497796-A (GB)
Title: Improvements in or relating to extensible rubber threads
IPC: B63H1/34
Filed: 1937-06-25
Abstract: 497,796. Rubber thread. AMERICAN ANODE, Inc. June 25, 1937, No. 17781. Convention date, Aug. 15, 1936. [Class 70] [Also in Groups VIII and IX] In the method of making rubber threads by passing a tension-resisting filament through latex to deposit a coating of rubber on the filament and subsequently destroying the tension resisting filament to leave the coating of rubber as an extensible rubber thread, the filament is passed through the latex in a catenary-like sweep without contacting any supporting or guiding means while in contact with the latex or until the deposited rubber coating is set sufficiently to prevent deformation during subsequent handling. The tension resisting filaments may be cotton, wool, silk, or artificial silk, and they may be destroyed mechanically or chemically. The method may be carried out in the apparatus shown. A number of tension resisting filaments F are passed in succession through a bath C of coagulant for the latex, a wiping device B, a bath L of latex, a heater H, a washer W, a device P for applying adhesion preventing powder, a dryer D, a vulcanizer V, and a roller device R for breaking the internal filaments to leave tubular rubber threads T. The wiping device B comprises a pair of positively driven diverging endless rubber belts 12, 12, the lower ends of the belts being immersed in baths 13, 13 of cleaning solution. The latex bath L is constructed so that there may be a steady flow of the main body of the latex in the direction of travel of the filaments to ensure uniform coating of the filaments. The latex flows lengthwise of the main deposition tank 36, spills over a header 37 into a return chamber 38 underneath the tank 36 and then flows through a channel 40 into a sump 34 whence it is returned by a centrifugal pump 33 up the ramp 35 into the tank 36. The filaments guided by the guide member 45 and apertures 43 in a header 42 forming the end of the tank 36 enter the tank 36 horizontally and below the normal level of the latex therein. A minor proportion of the latex escapes through the apertures 43 into a sump 44, whence it flows into the channel 40 and the main sump 33. In order to maintain the desired catenary sweep of the filaments the speed of the feed rollers 17, 17 on the outlet side of the heater H may be varied with respect to that of the feed roller 14 on the inlet side of the latex bath and this variation may be controlled by a photoelectric device 22. The heating of the coated filaments in the heater H should be sufficient to firmly set the surface but not to dry the deposit completely. The roller breaking device comprises a pair of rotating steel rollers 55 driven at a surface speed substantially the same as the rate of travel of the coated filaments. The coagulant may be a solution of calcium nitrate in acetone or alcohol containing a small proportion of lactic acid. To the coagulant there may be added a chemical which will slowly weaken or even completely destroy the filament, e.g. if a cellulose ester filament is used there may be added to the coagulant a small proportion of a solvent for the cellulose ester such as ethyl acetate, methyl aceto-acetate, ethyl aceto-acetate, 2 ethyl-butyl acetate, or isopropyl acetate.