GB1344006A - Process for the manufacture of organopolysiloxane compositions which cure at room temperature to give elastomers - Google Patents

Abstract

1344006 Organopolysiloxane compositions WACKER-CHEMIE GmbH 19 April 1971 [16 Feb 1970] 21893/71 Headings C3T and C3R A composition which cures to an elastomer on exposure to moisture at room temperature is made by mixing (1) a diorganopolysiloxane having reactive end groups preferably hydroxyl groups, with (2) a silicon compound having at least one nitrogen atom and three hydrolysable groups, (3) reinforcing fillers having a surface area of at least 50 m.<SP>2</SP>/g. and (4) a polyglycol which can be etherified and/or esterified, with the proviso that the said polyglycol is not etherified by a silyl radical containing an acyloxy, ketoximo, keto-oximato, amino- or aminoxy group and (5) optional conventional ingredients. Examples of (2) are silanes of formula R a Si(ON = X) 4-a , R a Si(NRR<SP>3</SP>) 4-a , where R is a hydrocarbon (h.c.) or substituted h.c., X is RR<SP>1</SP>C=, or R<SP>2</SP>C= where R<SP>1</SP>=H or R, R<SP>a</SP>h.c., a=0 or 1. Further examples include R a SiY 4-a where Y= ONR 2 , ONR<SP>2</SP>, NCO, NCS; organopolysiloxanes where m = 0-20, e =0-3; where d is at least 1. Component (2) is preferably used in amounts of 0À2-15% wt. of the total composition. Examples of component (3) are fillers having a surface area greater than 50 m.<SP>2</SP>/g. such as pyrogenic SiO 2 , SiO 2 aerogel, precipitated SiO 2 , metal oxides, e.g. TiO 2 , Fe 2 O 3 , Al 2 O 3 and ZnO. Component (3) is preferably used in amounts of 1-15% wt. relative to the total weight of all organo-silicon compounds in the composition. Examples of component (4) are polyglycol ethers of formula RO[(CHR<SP>6</SP>) p O) s H where R<SP>6</SP> is H or alkyl, p = 2-5, s = 2-100; polypropylene oxidepolyethylene oxide condensation products; organopolysiloxane-polyoxyalkylene copolymers of general formulµ A(R) 2 Si[OSi(R)A] p OSi(R) 2 A where A is [(CHR<SP>6</SP>) p O] s R<SP>7</SP> where R<SP>7</SP> is hydrogen, a monovalent h.c., an acyl radical, a triorganosilyl radical, a diorgano-(hydrocarbonoxy)silyl radical or a radical of the formula where p<SP>1</SP> is 1-50 and B is SiR 3 , A, or OSi(R) 2 A. The polyglycols are preferably used in amounts of 0À5-30% wt. relative to the diorganopolysiloxanes (1). In Example 1 the composition comprises an OH-terminated dimethylpolysiloxane of 18,800 cP/25‹ C., trimethylsiloxy-end-blocked dimethylpolysiloxane of 35 eP/25‹ C., pyrogenic SiO 2 , an organopolysiloxanepolyoxyalkylene block copolymer and methyl-tris-(cyclohexyl-amino)- silane. In Example 2 the silane of Example 1 is replaced by a mixture of and dibutyl tin dilaurate. In Example 3 the composition comprises OH-terminated dimethylpolysiloxanes of 350,000 cP/25‹ C. and 19,000 cP/25‹ C., a trimethylsiloxy-terminated dimethylpolysiloxane of 1000 cP/25‹ C., a tributyl phenol etherified with a polyethylene glycol of 13 ethylene oxide units, pyrogenic SiO 2 , calcined aluminium silicate and a mixture of a silane of the formula and methyl - tris - (cyclohexylamino) - silane, and dibutyl tin dilaurate. Uses.-Sealing joints and cavities; protective coatings; and electrical insulation.