Patent GB-781019-A (GB)
Title: An improved method of preparing a vulcanized natural or synthetic rubber composition containing lignin
IPC: C08L21/00
Filed: 1955-04-27
Abstract: A vulcanized synthetic rubber composition having a high abrasion resistance and low torsional hysteresis and hardness is prepared by heat-treating at a temperature of at least 300 DEG  F. a substantially water-free mixture comprising synthetic rubber and lignin co-precipitated from a latex and aqueous alkali lignate, and dried as completely as possible at a temperature of at least 160 DEG F., e.g. 160 DEG  to 210 DEG  F., masticating the mixture either during, alternately with, or subsequent to the heat treatment, incorporating vulcanizing and other ingredients, shaping, and vulcanizing.  The mixture is preferably masticated on a mill or in a Banbury mixer for at least 5 minutes at a temperature of 300 DEG  to 350 DEG  F., and vulcanizing and other ingredients are added to the masticated mixture at a temperature below 250 DEG  F.  A master-batch comprising a precipitated mixture of 70 to 100 parts of lignin to 100 parts of rubber may be prepared, and a mixture suitable for use in tyre manufacture may be prepared by reducing the proportion of lignin to 30 to 60 parts by masticating the master-batch with rubber at a temperature not exceeding 240 DEG  F. prior to the heat treatment at 300 DEG  F. or above.  The synthetic rubber may comprise neoprene or a polymer of a diolefine, e.g. butadiene or isoprene, or a copolymer of a diolefine and styrene, acrylonitrile, methyl acrylate or methacrylate, ethyl acrylate, or a vinyl pyridine. The mixture subjected to the heat treatment may contain a softener, e.g. a hydrocarbon oil, and filler such as carbon black, titanium dioxide, calcium carbonate, clay, zinc oxide, calcium silicate, and silica. The fillers are preferably incorporated as dispersions in the latex-lignin mixture.  Examples describe the preparation of vulcanizates from a master-batch comprising 40 parts by weight of lignin and 100 parts of GRS synthetic rubber. U.S.A. Specifications 2,118,601, 2,239,639, 2,572,884 and 2,608,537 are referred to. Reference has been directed by the Comptroller to Specification 633,725.ALSO:A vulcanized natural or synthetic rubber composition having a high abrasion resistance and low torsional hysteresis and hardness is prepared by heat-treating at a temperature of at least 300 DEG F. a substantially water-free mixture comprising natural or synthetic rubber and lignin co-precipitated from a latex and aqueous alkali lignate, and dried as completely as possible at a temperature of at least 160 DEG F., e.g., 160 DEG  to 210 DEG F., masticating the mixture either during, alternately with, or subsequent to the heat treatment, incorporating vulcanizing and other ingredients, shaping, and vulcanizing.  The mixture is preferably masticated on a mill or in a Banbury mixer for at least 5 minutes at a temperature of 300 DEG to 350 DEG F., and vulcanizing and other ingredients are added to the masticated mixture at a temperature below 250 DEG F.  A masterbatch comprising a precipitated mixture of 70 to 100 parts of lignin to 100 parts of rubber may be prepared, and a mixture suitable for use in tyre manufacture may be prepared by reducing the proportion of lignin to 30 to 60 parts by masticating the masterbatch with rubber at a temperature not exceeding 240 DEG F. prior to the heat treatment at 300 DEG F. or above. The synthetic rubber may comprise neoprene or a polymer of a diolefine, e.g. butadiene or isoprene, or a copolymer of a diolefine and styrene, acrylonitrile, methyl acrylate or methacrylate, ethyl acrylate or a vinyl pyridine.  The mixture subjected to the heat treatment may contain a softener, e.g. a hydrocarbon oil, and filler such as carbon black. titanium dioxide, calcium carbonate, clay, zinc oxide, calcium silicate, and silica. The fillers are preferably incorporated as dispersions in the latex-lignin mixture.  Examples are described illustrating the preparation of vulcanizates from a masterbatch comprising 40 parts by weight of lignin and 100 parts of GRS synthetic rubber.  U.S.A. Specifications 2,118,601, 2,239,639, 2,572,884 and 2,608,537 are referred to.  Reference has been directed by the Comptroller to Specification 633,725.