Patent GB-1366702-A (GB)
Title: Stabilisation of polymeric materials
IPC: C08J7/043
Filed: 1971-05-22
Abstract: 1366702 Water-sensitive coating R J W REYNOLDS 22 May 1972 [22 May 1971] 16498/71 Heading B2E [Also in Division B5] Polymeric material is provided with an adherent water-sensitive coating comprising a film-forming material and an ultra-violet absorber. The term "water-sensitive" includes water soluble coatings and coatings swollen by or broken down by water. Preferably an ultraviolet accelerator is also incorporated into the mass of the polymeric material. Examples of film-forming materials are polyvinyl alcohol, beta-hydroxy-ethyl cellulose, hydroxy propyl cellulose, salts of carboxy methyl cellulose, methyl cellulose, methyl starch, dextrin, gelatin, solubilised casein and soya protein, and salts of polyacrylic acid or styrene-maleic acid copolymers, partly hydrolised polyvinyl acetate, partly hardened gelatin; organic filmforming mixed with water-soluble additives such as monoacetin, polyethylene glycol or soluble organic or inorganic salts; inorganic materials, e.g. sodium silicate. The ultra-violet absorber may be or may be derived from 2- hydroxy-benzophenone, 2-(2-hydroxy phenyl) benzotriazole, substituted acrylate or substituted salicylate, and specific examples are given. The ultra-violet degradation accelerator may be an aromatic ketone, rosin, fluorescin aldol-naphthylamine condensates, salts of transition metals such as nickel, iron, copper, manganese and cobalt, e.g. nickel and iron dithiocarbonates, manganese or cobalt oleate and stearate and transition metal halides. The polymeric materials may be polyolefins, polymers and copolymers of styrene, polyacrylates and polymethacrylates, saturated and unsaturated polyesters, formaldehyde polymers and condensates, polyamides and vinyl chloride polymers. The coating may be applied as a solution or dispersion by dipping or spraying, brushing or flooding to, e.g. polyolefin bottles. Alternatively the coating may be in the form of a paste, viscose solution, dough or fusible solid compound which is spread, calendered or coextruded onto the polymeric material, e.g. polyolefin or vinyl chloride polymer film for heavy duty fertiliser sacks. The coating may also be applied as a pre-formed film, e.g. to polyvinyl chloride sheet or to polypropylene wrapping film. The method enables polymeric material to be prepared so that its useful life is unimpaired but so that it will be rapidly destroyed when its useful life is over and it is described. Protection and breakdown can be suitably balanced by suitable choice of the ultraviolet absorber and by the use of the ultra-violet degradation accelerator. In the examples: 1) a film for heavy-duty sacks of low-density polyethylene is coated by a roller with an aqueous solution of polyvinyl alcohol containing 2 - hydroxy - 4 - methoxy - 5 -  sulpho - benzophenone UV - absorber; 2) dispersion of polyvinyl alcohol containing 2,4 - dihydroxy - benzophenone and a surface active agent is applied to blow-moulded polyethylene bottles by spraying; 3) a polyethylene wrapping film is coated with an aqueous dispersion of methyl cellulose containing 2 - hydroxy 4 - methoxy - 5 - sulpho benzophenone; 4) plasticised polyvinyl chloride sheet is sprayed with a water/alcohol solution of partly hydrolised polyvinyl acetate containing 2,4 - dihydroxy benzophenone; 5) sodium carboxy methyl cellulose aqueous dispersion containing 2-(2-4- dihydroxy phenyl) benzotriazole is applied by dipping to a polystyrene container; 6) an aqueous dispersion of a vinyl acetate-2-ethyl hexyl acrylate copolymer, polyvinyl alcohol, 2,4-dihydroxy benzophenone is applied to a film of fabric prepared from unstabilised polypropylene, or vinyl chloride-vinyl acetate copolymer.