GB748836A - Improvements in or relating to formaldehyde polymers - Google Patents

Abstract

Solid formaldehyde polymers having an inherent viscosity of at least 1.0 measured as a 0.5 per cent solution at 60 DEG C. in p-chlorophenol containing 2 per cent alphapinene and a "degree of toughness" at least 1 are made by continuously passing, e.g. dropwise, substantially anhydrous monomeric formaldehyde into an inert liquid reaction medium and allowing the formaldehyde to polymerize continuously as it introduced. The polymerization may be effected at temperatures from -50 DEG to +170 DEG C., in the presence of a dispersing agent and a polymerization catalyst. "Degree of toughness" is the number of creasing cycles which a film will withstand before breaking, the creasing cycle consisting of folding a film through 180 degrees and creasing, then folding in the reverse direction through 360 degrees and creasing again, the test film being one which has been maintained at 105 DEG C. for seven days. The formaldehyde may be obtained from the pyrolysis of alpha-polyoxymethylene. Liquid media exemplified are decahydronaphthalene, benzene, cyclohexane, pentane, carbon tetrachloride. Other media mentioned are propane, butane, hexane, heptane, octane, decane, cyclopentane, methylcyclohexane, 1,4-dimethylcyclohexanes, toluene, xylene, nitriles, acetals and ethers. The dispersing agent may be the reaction product of ethylene glycol with wool wax alcohols, the long chain fatty di-esters of polyethylene glycols and polypropylene glycols, e.g. the di-oleic acid ester of polyethylene glycol, glycols of molecular weight above 200, silicone oils, alkylarylpolyoxymethylene glycol ethers, the reaction product of rosin and olefin oxides, sodium oleate, lead stearate, or sodium caprylate. Catalysts mentioned are methyl, ethyl, butyl, octyl, dodecyl, octadecyl, dibutyl, ethyloctyl, tributyl, trihexyl, dimethyloctadecyl and didodecylmethylamine, aniline, toluidine, triphenylphosphine, tritolylphosphine, trixylylphosphine, trinaphthylarsine, tributylphosphine, triethylstibine, methyldioctylarsine, hydrazine and substituted hydrazines, morpholines and substituted morpholines, piperidines, N-alkylpiperidines, N,N-diethylaminoethanol and mixtures. The dispersions may include a stabilizer such as alpha-pinene and also an antioxidant. The polymers may be mixed with pigments, fillers, plasticizers and stabilizers and made into sheets, films, fibres, filaments and bristles.