Patent GB-568504-A (GB)
Title: Improvements relating to the treatment of materials of regenerated cellulose to improve their adhesion to rubber
IPC: C08J5/06
Filed: 1943-01-29
Abstract: Regenerated cellulose fibres, yarns, or fabrics are treated to improve their adhesion to rubber by coating the fibres with rubber applied in solution in a hydrophobe liquid which is subsequently removed, the conditions of treatment being such that the individual fibres are not stuck together, and the moisture content of the material is reduced immediately before or during the treatment.  The rubber solution employed should preferably have a viscosity at 25 DEG C. not greater than 15 centistokes.  Instead of using natural rubber there may be used gutta percha, balata, rubber hydrochloride, chlorinated rubber, cyclised rubber, e.g. that obtained by treating rubber with p-phenol sulphonic acid, polyisobutylene, co-polymers of isobutylene with butadiene or isoprene, and other rubber-like polymers of mono-olefinic hydrocarbons and of conjugated di-olefinic compounds.  Since the treatment improves the adhesion of regenerated cellulose materials to rubber, it may be employed in the production of tyre cords and fabrics.  Preferably the moisture content of the regenerated cellulose material is reduced to below 2 per cent.  In an example, a tyre-fabric, in which the cords are built up from regenerated cellulose yarn formed by saponifying steam-stretched cellulose acetate yarn, is passed over steam-heated drying rolls and its moisture is reduced to 2 per cent.  The fabric passes through a bath of hot xylene and its moisture is further reduced.  It is passed between squeeze rolls into a bath containing a 2 per cent solution of rubber in xylene.  The fabric is passed out of the bath and the xylene is removed by evaporation.  It is passed to a calender where it receives a skim coating of rubber containing vulcanizing agents. The preliminary bath of hot xylene or toluene may be dispensed with and the rubber solution may be heated so as to reduce the moisture of the fabric.  Instead of using very dilute rubber solutions, there may be used rather more concentrated solutions of rubber which has undergone degradation to obtain the desired viscosity.  This may be effected by prolonged heating, milling, or mastication, by exposing the rubber to oxidising agents such as air, oxygen, ozone, peroxides, per-acetic acid, oxides of nitrogen, or halogens, or by exposing the rubber to ultra-violet light.  Benzene, coal-tar solvent naphtha, petroleum spirit, ethylene dichloride, tetrachloroethane, or perchlorethylene, may be used as hydrophobe liquid or as solvent for the rubber in the coating bath.  Reduction in the moisture content of the regenerated cellulose material, if this has not been done at an earlier stage in the process, may occur during evaporation of the hydrophobe liquid from the material at an elevated temperature.  The rubber solution may contain sulphur, zinc oxide, vulcanising accelerators, carbon black, and anti-oxidants.  The materials may contain other fibres in admixture with the regenerated cellulose fibres e.g. cotton or linen.  The treated materials may subsequently be rubberised to obtain water-proof or gas-proof fabrics.  The Provisional Specifications refer also to the use of polyvinyl compounds and polyacrylic compounds instead of rubber.