Patent GB-1489890-A (GB)
Title: Moisture curable sealant composition
IPC: C08G75/14
Filed: 1974-11-26
Abstract: 1489890 Polymeric sealants ALBRIGHT & WILSON Ltd 26 Nov 1974 51117/74 Addition to 1396698 Heading C3R An anhydrous moisture-curable sealant composition containing unreacted SH groups and containing no peroxides or tin compounds or other compounds capable of curing SH terminated polysulphides under the reaction conditions specified below in the absence of moisture, the sealant comprising the product of reacting under anhydrous conditions a polysulphide of the formula HS[(CH 2 (R<SP>1</SP>) b CH 2 S a ) c (R<SP>11</SP>S a ) d (SH) f ] CH 2 (R<SP>1</SP>) b CH 2 SH where a is 1-5, b is 0 or 1, c is 1-200, d is 0 up to 0À05c, f is subject to the condition 0À05c # f # d, 1 # f and f = d Î (No. of free valencies in R<SP>11</SP>-2), R<SP>1</SP> is -O-, -S- or an organic divalent radical free of aliphatic unsaturation consisting of C and H and optionally O in the form of OH and/or in a environment in the molecule and/or S in a environment in the molecule, R<SP>11</SP> is an organic radical free of aliphatic unsaturation and having at least 3 free valencies and consisting of C and H and optionally O in the form of OH and/or in a environment in the molecule and/or S in a environment in the molecule, and the free valencies being for carrying all the f SH groups, and the CH 2 R<SP>1</SP> b CH 2 S a  and R<SP>11</SP>S a  groups being in any order, with a silane of the formula Q n SiX (4-n)  where n is 1 or 2, Q is an organic group having a mercapto or an epi-sulphide group, and at least 2 X's are organic hydrolysable groups and the remaining group X, if any, is a C 1 -C 6  alkyl or chloroalkyl group, the silane having a total of only 1 or 2 groups which react with SH in the polysulphide under the reaction conditions, the reaction being carried out to react 3-30% of the SH groups of the polysulphide with the silane in the presence of a base of pK a  at least 9. An anhydrous waterimpermeable pack comprises the above sealant composition preferably in an amount of 10- 60% wt., and a filler generally in an amount of 30-40% wt., and optionally a plasticizer, a curing catalyst, pigments, an hydrolysis inhibitor and/or thixotropic agents. Preferred polysulphides are those of the formula Preferred silanes are those of the formula QSiX 3  where Q is HS(CH 2 ) m+1  or where m = 0-3, and the 3 X groups are trialkoxy or alkyl dialkoxy groups. Preferred bases are tertiary amines of the formula NR 16 R 17 R 18  wherein at least one of R 16 -R 18  is an alkyl group of at least 6 carbon atoms, a cyclohexyl or aralkyl group, the remainder if any being C 1 -C 5  alkyl groups, provided that the amine contains at least 9 carbon atoms, or R 16  and R 17  together with the N atom to which they are attached form a heterocyclic ring, optionally with at least one N, S or O atom in the ring. Suitable fillers are chalk, lithopone, CaCO 3 , silica, ZnO, clay, TiO 2 , slate powder, carbon black and BaO; suitable pigments are TiO 2  and carbon black; suitable plasticizers are nitrated aromatic compounds, chlorinated liquid paraffins, chlorinated polyphenyls and phthalates. Suitable thixotropic agents are colloidal SiO 2 , bentone (Registered Trade Mark), carbon black and chrysotile asbestos. Suitable inhibitors are silanes of the formula Z n Si(OZ<SP>1</SP>) 4-n , where n = 0-2, Z is hydrogen, alkyl or aryl, and Z<SP>1</SP> is as defined for Z or C 1 -C 8  acyl. Suitable catalysts are titanium compounds of the formula Ti(OR) 4  where R is a C 1 -C 18  alkyl group or a phenyl group, or one or two OR groups represent enolate groups from beta-dicarbonyl or betahydroxy-carbonyl compounds, or at least one pair of R groups combined represents a C 1 -C 18  alkylene radical or an alkylene radical interrupted by at least one of O, N, NR 5  and S atoms, or 3 or 4 of the R groups combined represent an aliphatic tri- or tetra-radical, which consists of saturated hydrocarbyl groups optionally interrupted by at least one of O, N, NR 5  and S atoms, and R 5  = H or C 1 -C 6  alkyl; or polymers of such compounds. The cured products can have an extensibility of 50- 200% and a recovery after 5 minutes extension by 50-200% of at least 75% measured 1 hour after release of the extending force. In the example a sealant formulation is prepared by reacting a polysulphide of the above preferred formula where c = 50 and d = 0À1 in toluene with HS(CH 2 ) 3 Si À (OCH 3 ) 3  in the presence of 2,4,6 - tris - (dimethyl aminomethyl)phenol, then removing the toluene and compounding the resulting polymer with titanium dioxide, CaCO 3  particles coated with stearic acid, fumed silica, a chlorinated polyphenyl and di-isopropyltitaniun diacetyl acetonate, and is cured at room temperature.