GB965854A - Production of expanded plastics - Google Patents

Abstract

An expanded plastic is produced by reacting at least one polyisocyanate and water, with a copolymer derived from (a) at least one olefinically unsaturated polymerizable monomer containing at least one tertiary nitrogen atom and at least one group which will react with isocyanate, the proportion of this monomer being at least 0.25% by weight of the copolymer and (b) at least one other olefinically unsaturated polymerizable monomer. Copolymer formation may be carried out in bulk, solution, emulsion or suspension, between 0 and 300 DEG C., using as catalysts: peroxides, e.g. benzoyl and cyclohexanone peroxides, hydroperoxides, e.g. tert.-butyl hydroperoxide, azo compounds, e.g. azodiisobutyronitrile or redox systems. The copolymer should have a K value of 15-50, and an OH number of less than 125 for soft foams and 125-300 for rigid foams. The foaming reaction is carried out at 0-100 DEG C. 1-1.5 moles of isocyanate per mole of isocyanate reactive groups and 1 mole of water per mole of unreacted isocyanate group are required. Stabilizers and plasticizers may be added, e.g. silicones, tin octoate, dibutyltin diethyl hexoate or metal chelates. Isocyanate reactive groups specified are hydroxyl, carboxyl, carbonamide, thiocarbonyl, thioamide, sulphhydryl, primary and secondary amino and active hydrogen attached to carbon. Compounds of type (a) specified are heterocycles with at least one tertiary nitrogen atom in the ring system; e.g. hydroxy and hydroxyalkyl, vinyl and allyl derivatives of a pyridine, quinoline, isoquinoline, acridine, pyrimidine, indazole, imidazole, pyrazole, triazole, benzoxazole and oxazole such as 5-hydroxymethyl-2-vinyl-pyridine, hydroxymethylvinyl-benzoxazole, N-vinyl-2-methylol-imidazole and N-vinyl-2-hydroxyethyl-imidazole and compounds of the formula: <FORM:0965854/C3/1> where X=NH or O; R1=H, alkyl, hydroxyalkyl or halogen; R2= -CH2-, -C2H4- or -C4H8- optionally branched or hydroxylated and R3 and R4 may be alkyl, aryl or aralkyl optionally branched or hydroxylated, at least one of R2, R3 or R4 containing a hydroxyl group, preferably b to the nitrogen atom, e.g. di-(b -hydroxyethyl)-aminomethylene methacylamide and substituted amides and esters of maleic, fumaric, and itaconic acids. Compounds of type (b) may or may not contain tertiary nitrogen atoms or isocyanate reactive groups. Specified compounds include: acrylic esters, methacrylic esters, maleic esters, fumaric esters, itaconic esters, vinyl esters, vinyl halides, vinylidine halides, vinyl aromatic hydrocarbons, halostyrenes, N-substituted amides, acrylonitrile, N-vinyl lactams, N-vinyl pyridine, vinyl ethers, dienes and allyl compounds. The esters may be wholly or partly saponified. Several polyisocyanates are specified. In examples copolymer formation is carried out under N2 in the presence of tertiary dodecyl mercaptan and azodiisobutyronitrile and in Examples (1-3 and 5) using CH2Cl2 as solvent. Monomers of type (a) are N-vinyl-2 methylol-imidazole (1, 2 and 4-8), diethanolaminomethylene methacrylate (3) and N-vinyl-2-hydroxyethyl-imidazole (9). Monomers of type (b) are n-butyl acrylate (2 and 6-9), isobutyl acrylate (1 and 3-5), butane-1, 4-diol monoacrylate (4, 5 and 8), propylene glycol monoacrylate (6) and ethylene glycol monoacrylate (7). Butane-1, 4-diol is used in Example (5). Foaming is by adding tolylene diisocyanate, silicone oil, water and the sodium salt of a sulphonated sperm oil/ethylene oxide adduct.