Patent GB-722822-A (GB)
Title: Organosilicon resins
Filed: 1952-01-14
Abstract: Thermosetting resins are made by reacting (1) one or more organo silicon compounds of the average general formula <FORM:0722822/IV (a)/1> where R is a monovalent hydrocarbon radical, n is 1 to 3, a is 0.2 to 3 and X is alkoxy, chlorine or bromine; (2) phenol, resorcinol, p-p1bis-hydroxyphenyldimethylmethane, a monoalkyl or mono aryl substituted phenol, cresylic acid or a mixture of such compounds; and (3) an aldehyde in proportions such that the ratio of silicon linked X substituents to hydroxy groups in the phenolic compound is from 1 : 10 to 10 : 1 and the molecular ratio of aldehyde to phenolic compound is from 0.1 : 1 to 6 : 1.  The compound (1) may be reacted with (2) and the product, which may be regarded as an alternative starting material, reacted, with or without the addition of further phenolic compound within the limits stated, with (3), or the product of (2) and (3) may be reacted with (1).  The phenolic compound reacts at the hydroxyl group with the silicon compound with elimination of HX, and with the aldehyde at the positions on the ring o and p to the oxygen atom.  The silicon compound (as indicated by the range of values for a) may be monomeric or polymeric.  Aldehydes referred to are formaldehyde (and generators thereof), gaseous or in alcohol solution, acetaldehyde and furfural.  The aldehyde reaction may be catalysed with acid or alkali, e.g. hydrochloric and oxalic acids, potassium and sodium hydroxides, hexamine and triethanolamine. The resins are similar to phenol-aldehyde resins but have improved heat stability.  In examples; (1) resorcinol was reacted with phenylmethyl diethoxysilane and the product reacted with formaldehyde dissolved in n-propanol.  The resulting resin eventually thermoset; (2) phenylmethyldiethoxysilane was reacted with p-p1-bis-hydroxyphenyldimethylmethane and the product reacted with formaldehyde to give a thermosetting resin; (3) resorcinol reacted with phenylmethyl diethoxysilane and the product with formaldehyde in methanol; (4) p-p1-bis-hydroxyphenyldimethylmethane reacted with a partially hydrolysed isopropoxy siloxane containing methyl and phenyl groups and the product reacted with formaldehyde in methanol; (5) phenyldimethylethoxysilane reacted with resorcinol and the product with paraformaldehyde; (6) phenol reacted with butyltrichlorosilane and the product with formaldehyde; (7) phenylmethyldi-o-phenylphenoxysilane was reacted with paraformaldehyde; (8) phenylmethyl-di-m-cresoxysilane reacted with paraformaldehyde; (9) diphenyldi-o-cresoxysilane and paraformaldehyde; (10) o- or p-isopropylphenoxy-, p-tertiary-butyl-phenoxy-, p-tertiaryamylphenoxy- and a mixture of om-, and p-cresoxy substituted phenylmethylsilanes reacted separately with paraformaldehyde; (11) phenylmethyldi-o-cresoxysilane reacted with paraformaldehyde and hexamine for one hour at 200 DEG  C.  The resin was cooled, powdered and mixed with additional paraformaldehye and hexamine and the composition moulded at 175 DEG  C. under 10 p.s.i. pressure to give a hard heat-stable resin; (12) phenyltriphenoxysilane reacted with paraformaldehyde; (13) dimethyldicresoxysilane was prepared from dimethyldichlorosilane and cresylic acid and reacted with formaldehyde in butanol to give a thermosetting resin; (14) phenol was reacted with aqueous formaldehyde in alkaline solution, the product neutralized and acid sodium sulphite added thereto.  The resin was separated and dried, mixed with phenylmethyldimethoxysilane and heated to remove methanol, 2-ethylhexanol being added as required to reduce viscosity.  A film cast from the solution and cured at 175 DEG  C. for 2 hours was flexible and tack-free; (15) o-cresol was reacted in alkaline solution with aqueous formaldehyde at room temperature, pure 2-4-dimethylol-o-cresol isolated and reacted with phenylmethyldimethoxysilane; (16) cresylic acid was reacted with dimethyldichlorosilane to give dimethyldicresoxysilane which was reacted with 2.4-dimethylol-o-cresol prepared as in (15).  The resin was heated for 6 hours at 175 DEG  C. to a flexible thermoset state. The resin showed no signs of degradation after heating at 250 DEG  C. for 7 days.ALSO:2.4 - Dimethylol - o - cresol is prepared by allowing a mixture of 108 grams o-cresol, 162 grams of a 37 per cent aqueous formaldehyde solution and 120 grams of an aqueous 20 per cent sodium hydroxide solution to stand for 2 days at room temperature. The reaction product is neutralized with acetic acid, a white crystalline product precipitating which is recrystallized from chloroform. Organo-silicon compounds which may be reacted with aldehydes to give resins are obtained by reacting resorcinol, p.p1-bishydroxyphenyldimethylmethane, phenol, cresylic acid, monoalkyl substituted phenols and mono-aryl substituted phenols, e.g. o- and p-phenylphenol, o- and p-isopropyl phenol and p-tertiary butyl- and p-tertiaryamylphenol, with organosilicon compounds of the formula <FORM:0722822/IV (b)/1> where R is a monovalent hydrocarbon radical free from aliphatic unsaturation, X is an alkoxy radical, chlorine or bromine, n has a value from 1-3 inclusive, and a has a value from 0.2 to 3 inclusive.  The hydroxyphenyl compound reacts at the hydroxy group with the alkoxy group, chlorine or bromine.  In examples, (1) and (3), 110 grams resorcinol were reacted with 210 grams phenylmethyldiethoxysilane.  About 85 per cent of the theoretical amount of ethanol was removed; (2) 2 gram mols. phenylmethyl-diethoxysilane were reacted with 1 gram mol. of p.p1-bis-hydroxyphenyl dimethylmethane by heating up to 200 DEG  C. until 85 per cent of the theoretical amount of ethyl alcohol was removed; (4) 114 grams p.p.1-bis-hydroxyphenyldimethylmethane were reacted with 246 grams of a partially hydrolysed isopropoxy siloxane containing 28 per cent of silicon-bonded isopropoxy groups, 70 mol. per cent of phenylmethylsiloxane units and 30 mol. per cent of phenyl siloxane units, by heating to 210 DEG  C. in the presence of hydrochloric acid; (5) 360 grams of phenyldimethylethoxysilane were reacted with 110 grams resorcinol at from 90 to 130 DEG  C.; (6) 1 gram mol. of phenol was reacted with 0.3 gram mol. butyltrichlorosilane; (7) phenylmethyl-di-o-phenylphenoxysilane is referred to; (8) phenylmethyldi-m-cresoxysilane is referred to; (9) diphenyldi-o-cresoxysilane is referred to; (10) o- and p-isopropyl-phenoxy-, p - tertiarybutyl - phenoxy -, p - tertiaryamyl - phenoxy-substituted phenylmethylsilanes and a mixture of o-, m- and p-cresoxy-substituted silanes are referred to; (11) phenylmethyldi-o-cresoxysilane is referred to; (12) phenyltriphenoxysilane is referred to; (13) dimethyldicresoxy silane is prepared from dimethyldichlorosilane and cresylic acid.