GB819324A - Stretching rubber hydrochloride film - Google Patents

Abstract

<PICT:0819324/IV (a)/1> <PICT:0819324/IV (a)/2> A method of stretching rubber hydrochloride film containing 5 to 10 parts by weight of ester plasticizer per 100 parts of rubber hydrochloride, comprises first heating the film to 205 DEG to 220 DEG F. and then immediately stretching it to double its length, and then stretching it to double its width whilst heating it to and maintaining it at a temperature of 170 DEG to 190 DEG F. The film is fed from a roll 1 or 2 (or if a laminated product is required from both rolls 1 and 2) and passes over a rotating drum 9, heated to a temperature of 205 DEG to 220 DEG F., and under a roll 12 which is rotated at a higher surface speed than the drum 9 to stretch the film longitudinally. The edges of the film are folded over pins 20 carried by tentering chains 15 as the pins pass into grooves 22 near the ends of the roll 12, and are held against the pins by endless belts 23 as the tentering chains 15 stretch the film laterally. During the lateral stretching the film is heated to a temperature of about 170 DEG to 190 DEG F. by a plate 30, beneath and spaced from the film.