Patent GB-766419-A (GB)
Title: Improved acid-resistant cements
IPC: C04B24/42
Filed: 1955-02-25
Abstract: An acid-resistant cement consists of a solution of sodium or potassium silicate and from 3 to 30 per cent by weight of the alkali metal silicate of an aliphatic hydrocarbonoxy-substituted siloxane wherein at least a major portion of the silicon atoms are connected by SiOSi linkages and any remaining linkages are SiSi and/or SiR1Si, where R1 is a divalent hydrocarbon radical, the remaining valencies of the silicon atoms being satisfied by an average of 1 to 1.5 monovalent hydrocarbon radicals per silicon atom and of 0.03 to 2 OR11 radicals per silicon atom, where R11 is an aliphatic hydrocarbon radical. The siloxane may be one in which all the silicon atoms are connected by SiOSi linkages and prepared by partially hydrolysing the product obtained by partially alkoxylating a halosilane. Alternatively the cement may contain a mixture of complex materials containing silicon bonded alkoxy groups including the three substituted siloxanes in which the silicon atoms are linked both by SiOSi linkages and (a) SiSi, (b) SiR1Si, and (c) SiSi and SiR1Si linkages, respectively.  This mixture is prepared by partially alkoxylating, by treatment with an alcohol, and subsequently partially hydrolysing, by adding water, the residue obtained when methyl chloride is reacted with silicon, and methyl-chloro-silanes boiling below 75 DEG  C. at atmospheric pressure removed.  The cement may also contain less than 50 per cent by weight based on the total weight of the siloxanes of a completely hydrolysed siloxane of the formula <FORM:0766419/IV(a)/1> where R is a monovalent hydrocarbon radical and x has a value of from 1 to 2, and a siliceous filler such as diatomaceous earth or sand.  In examples the siloxane comprises (a) a mixture of 85 per cent by weight of a liquid alkoxylated polysiloxane having methyl, ethyl, propyl, and butyl radicals of a total number providing about 1.1 per silicon atom, and 15 per cent by weight of a non-alkoxylated polysiloxane resin consisting of a copolymer of SiO2 and Me3SiO0.5 having about 1.2 methyl groups per silicon atom, and (b) 67 per cent of phenylmethylsiloxane molecules and 33 per cent monophenylsiloxane molecules and containing 20 per cent by weight of silicon-bonded isopropoxy groups.  Specification 749,799 and 749,938, [both in Group IV (b)], are referred toALSO:An acid-resistant cement consists of a solution of sodium or potassium silicate and from 3 to 30 per cent by weight of the alkali metal silicate of an aliphatic hydrocarbonoxy-substituted siloxane wherein at least a major portion of the silicon atoms are connected by SiOSi linkages and any remaining linkages are SiSi and/or SiR1Si where R1 is a divalent hydrocarbon radical, the remaining valencies of the silicon atoms being satisfied by an average of 1 to 1,5 monovalent hydrocarbon radicals per silicon atom and of 0,03 to 2 OR11 radicals per silicon atom where R11 is an aliphatic hydrocarbon radical.  The siloxane may be one in which all the silicon atoms are connected by SiOSi linkages and prepared by partially hydrolysing the product obtained by partially alkoxylating a halosilane.  Alternatively the cement may contain a mixture of complex materials containing silicon-banded alkoxy groups including the three substituted siloxanes in which the silicon atoms are linked both by SiOSi linkages and (a) SiSi, (b) SiR1Si, and (c) SiSi and SiR1Si linkages, respectively.  This mixture is prepared by partially alkoxylating, by treatment with an alcohol, and subsequently partially hydrolysing, by adding water, the residue obtained when methyl chloride is reacted with silicon, and methyl-chloro-silanes boiling below 75 DEG C. at atmospheric pressure removed.  The cement may also contain less than 50 per cent by weight based on the total weight of the siloxanes of a completely hydrolysed siloxane of the formula: <FORM:0766419/V/1> where R is a monovalent hydrocarbon radical and x has a value of from 1 to 2, and a siliceous filler such as diatomaceous earth or sand. In examples the siloxane comprises (a) a mixture of 85 per cent by weight of a liquid alkoxylated polysiloxane having methyl, ethyl, propyl, and butyl radicals of a total number providing about 1,1 per silicon atom, and 15 per cent by weight of a non-alkoxylated polysiloxane resin consisting of a copolymer of SiO2 and Me3SiO0.5 having about 1,2 methyl groups per silicon atom, and (b) 67 per cent of phenylmethylsiloxane molecules and 33 per cent monophenylsiloxane molecules and containing 20 per cent by weight of silicon bonded isopropoxy groups.  Specifications 749,799 and 749,938 [both Group IV(b)] are referred to.