Patent GB-636233-A (GB)
Title: Improvements in and relating to the manufacture of plastic articles
IPC: B29C48/09
Filed: 1947-08-07
Abstract: Casein or other proteinaceous plastic mass is coloured by incorporating one or more mordants prior to homogenization and hardening of the material, and the plastic is immersed in a solution of a dyestuff before or after homogenization or hardening.  Chrome, aluminium, tannin, oxalate or sulphur type of mordants may be used. The dyeing is improved if the mordanted hardened plastic article is treated with a solution of a reducing agent, such as sodium bisulphite, prior to the dyeing operation. The mordanted plastic may be dyed in the presence of sodium dichromate or the dyed plastic may be after-chromed to vary the nature or depth of the colour produced. In examples: (1) rennet casein is mixed with water, sodium dichromate and formic acid, homogenized by heat and pressure, converted to rods, discs, tubes or sheets, hardened with formaldehyde solution and dyed, if desired after pretreatment with sodium bisulphite, with Alizarine Red A.S., Chromosol Green E.E., or Eriochromal Brown G; (2) rennet casein is mixed with water and tannic acid, hardened, and dyed with Methylene Blue, Auramine O on Rhodamine B-and if desired, after-treated in a tannin bath; (3) the previous example is repeated using tannic acid and titanium phospho-oxalate as mordants; (4) rennet casein is mixed with potash alum and soda ash, hardened, and dyed with the dyestuffs of (1); and (5) two or more mixtures as in the above examples, or a mixture of a mordanted and an unmordanted plastic, are extruded together and the product hardened, immersed in sodium bisulphite solution and then dyed.ALSO:Casein or other proteinaceous plastic mass is coloured by incorporating one or more mordants prior to homogenization and hardening of the material, and the plastic is immersed in a solution of a dyestuff before or after homogenization or hardening.  Chrome, aluminium, tannin, oxalate or sulphur type of mordants may be used.  The dyeing is improved if the mordanted hardened plastic article is treated with a solution of a reducing agent, such as sodium bisulphite, prior to the dyeing operation. The mordanted plastic may be dyed in the presence of sodium dichromate or the dyed plastic may be after-chromed to vary the nature or depth of the colour produced.  In examples, (1) rennet casein is mixed with water, sodium dichromate and formic acid, homogenized by heat and pressure, converted to rods, discs, tubes or sheets, hardened with formaldehyde solution and dyed, if desired after pretreatment with sodium bisulphite, with Alizarine Red A.S., Chromosol Green E E or Eriochromal Brown G; (2) rennet casein is mixed with water and tannic acid, hardened, and dyed with Methylene Blue, Auramine O or Rhodamine B-and if desired, after-treated in a tannin bath; (3) the previous example is repeated using tannic acid and titanium phospho-oxalate as mordants; (4) rennet casein is mixed with potash alum and soda ash, hardened, and dyed with the dyestuffs of (1); and (5) two or more mixtures as in the above examples, or a mixture of a mordanted and an unmordanted plastic, are extruded together and the product hardened, immersed in sodium bisulphite solution and then dyed.