Patent GB-717928-A (GB)
Title: Improvements in or relating to expanded resinous cellular products
IPC: C08J9/02
Filed: 1951-10-25
Abstract: Expanded, cellular resinous products are prepared by reacting at 150-250 DEG C. a polyepoxy compound and sufficient aconitic acid to provide 0.7-2 carboxyl groups for each epoxy group in the polyepoxy compound.  The polyepoxy compound may be vinyl cyclohexene dioxide, a polyglycidyl ether of a polyhydric phenol or of a polyhydric alcohol or a diepoxide of a glycol bis-exo-dihydrodicyclopentadienyl ether of the formula <FORM:0717928/IV (a)/1> in which R is an aliphatic radical containing carbon, hydrogen and if desired oxygen.  If desired part of the aconitic acid may be replaced by another polycarboxylic acid containing 3-6 carboxyl groups, the aconitic acid being 2-90 per cent. of the total weight of acids.  Suitable polycarboxylic acids for use with the aconitic acid are citric, tricarballylic, hemimellitic, trimellitic and pyromellitic acid and half-ester-half-acids formed from dicarboxylic acids, such as phthalic, maleic, succinic, glutaric, adipic, pimelic, saberic or azelaic acid, or their anhydrides and polyhydric alcohols such as glycerol, pentaerythritol, dipenta erythritol, mannitol or sorbitol. Such compounds are pentaerythrityl tetracid maleate phthalate and glyceryl triacid maleate phthalate.  Preferably R in the above formula is alkylene with 1-12 carbon atoms or -(R1O)xR1-in which R1 is alkylene with 2-4 carbon atoms and X is 1-8.  Thus R may be a residue of ethylene glycol, diethylene glycol, butylene glycol, hexamethylene glycol or an isomer thereof, 1,2- or 1,8-dihydroxyoctane, triethylene glycol, tetrapropylene glycol, dibutylene glycol, hexabutylene glycol or octaethylene glycol. The polyglycidyl ethers for use in the invention may be prepared from resorcinol, catechol, hydroquinone, bis-(4-hydroxy-phenyl)-2, 2-propane. 4, 41-dihydroxybenzophenone, bis-(4-hydroxy-phenyl)-1, 1-ethane, bis-(4-hydroxyphenyl)-1, 1-isobutane bis-(4-hydroxyphenyl), 2- 2-butane, bis-(4-hydroxy-2-methylphenyl)-2, 2-propane, bis-(4-hydroxy-2-tert.-butylphenyl)-2,2-propane, bis-(2-dihydroxynaphthyl) methane or 1,5-dihydroxynaphthalene, or from ethylene glycol, propylene glycol, trimethylene glycol, butylene glycol, diethylene glycol, triethylene glycol, glycerol, dipropylene glycol, pentaerythritol, mannitol, sorbitol or polyvinyl alcohol. The ingredients are mixed and heated together up to 140 DEG C. and may then be cooled for future use or poured into moulds and expanded by heating at a higher temperature immediately.  Conventional additives may be compounded with the moulding composition, e.g. pigments, fillers, dyes, or plasticizers such as dibutyl phthalate, tricresyl phosphate or epoxidized vegetable oils and a curing catalyst, e.g. butyl or cresyl diacid phosphate may also be included. In the examples thermoset foams are prepared from (1) aconitic acid and the diepoxide of the bis-exo-dihydrodicyclopentadivinyl ether of diethylene glycol, (2) and (3) and (4) and (7)-(14) the same mixture with the addition of pentaerythrityl tetraacid trimaleate monophthalate.  Examples (5) and (6) are similar using ethers of ethylene glycol and propylene glycol respectively.  Example (15) is similar but employs citric acid admixed with the aconitic acid. In example (16) the foam is prepared from the diglycidyl ether of bis-(4-hydroxyphenyl-)2, 2-propane, aconitic acid and pentaerythrityl tetraacid trimaleate monophthalate.  Example (17) a set cellular mass is obtained from vinyl cyclohexene dioxide, and aconitic acid alone or mixed with pentaerythrityl tetraacid trimaleate monophthalate. Example (18) a polyglycidyl ether of glycerol was used together with aromatic acid alone and mixed with various proportions of other polycarboxylic acids.  Specification 714,080 is referred to.