| 摘要 |
1,227,868. Cleaning moulding surfaces. GOODYEAR TIRE & RUBBER CO. 17 Sept., 1968 [17 Sept., 1968], No. 44048/68. Heading B5A. [Also in Divisions C3, C5 and C7] Surfaces of moulds for shaping articles of synthetic polymers are cleaned from deposits formed by contacting the surface in the presence of water and CO 2 with at least one substituted methylamine compound as hereinafter defined, by treating the surface with at least one of formic acid, acetic acid and propionic acid and drying the surface. The methylamine compound is defined as being characterized by forming a turbidity within 60 minutes when 11. per minute of CO 2 at 25‹ C. is passed through 1 1. of a solution of 10 to 20 parts of the methylamine compound per 100 parts by weight of methyl ethyl ketone, which solution has been aged for 8 hours at 25‹ C. and then warmed to 40‹ C. The process is particularly directed to cleaning moulds used for polyurethane and epoxy resin reaction mixtures. The mould may be made of a metal preferably coated with a release agent, or a cured millable gum silicone rubber, a cured natural rubber or synthetic rubber-like polymer, or a thermoplastic or thermoset polymeric material. Suitable release agents are polyethylene and polypropylene waxes and emulsions, natural and synthetic waxes, dimethyl silicone fluids, greases and higher polymers, soya bean fatty acids, vegetable lecithin and cephalin, soaps, fluorocarbons polyvinyl alcohol and fluorosilicones. The mould material may contain fillers such as pyrogenic silica, silica aerogels, organo-silane modified silicas, barium and cadmium titanates, zirconates and stannates, diatomaceous earth, clays, calcium carbonate, finely ground quartz, barites, iron oxide, zinc oxide, and titanium dioxide. The cleaning acids may be employed separately or together, or may be dissolved in an inert organic solvent. Particularly for cleaning silicone rubber moulds, they are preferably used successively in decreasing order of molecular weight. The cleaning process is said to restore the release properties of the mould and rejuvenate the surface definition. |
