GB369194A - Improvements in or relating to the manufacture of rayon - Google Patents

Abstract

In the manufacture of artificial threads of low denier, a number of such threads are united to form a single heavy thread, which is subjected as such to washing and like treatment, and then divided into its component threads. Thus, a cuprammonium solution containing 3,5-4 per cent of cellulose may be pumped through a double spinnerette into a caustic bath to produce two threads of 50 deniers, which are stretched on leaving the bath by passage over two drawing wheels of different sizes running at the same speed, or of the same size running at different speeds. The two threads then pass through guides to a cap-twisting device which imparts a twist to each thread, twists the two threads together to a single thread, and lays the compound thread on a spool. When the spool is filled, the thread is unwound and passed through an acid bath to remove copper, the spool being sprayed meanwhile with mildly caustic water. The thread is drawn through the acid bath by a large cylinder on which it is wound, the cylinder preferably revolving partly in the acid bath. Preferably, also, the thread is laid on the cylinder with a traverse motion, to produce a cake with tapered edges. The thread collected on the cylinder is washed with water, suitably by revolving the cylinder and causing a jet of water to travel along it. The cylinder is then placed in an oven, and the thread dried. To divide the thread into its component threads, the thread is wound on to a bobbin, which is then placed in a horizontal position in a support revolving about a vertical axis. The thread is led through a guide and over feeding rolls, and an end is then broken off, so that the two component threads can be easily parted, each thread being led through a guide to an ordinary cap-twister. The mounting of the bobbin as described above causes the twist previously imparted to the compound thread to disappear. A reciprocating finger may be arranged between the final cap-twisters and the feeding rolls, to facilitate separation of the component threads. The compound thread may contain more than two component threads, and reference is made to the use of the compound thread as such.