One-part room-temperature curable compositions on the basis of organosilicon compounds and titanium curing catalysts

Abstract

One-part room-temperature curable compositions (RTV-1 compositions) based on organosilicon compounds are less toxic compared to conventional compositions containing organotin compounds and, at the same time, have excellent curing properties, a skin formation time which allows proper handling and tooling, and excellent storage stability. The compositions contain: at least one organosilicon compound containing condensable groups; at least one curing agent having the formula R′Si(OOCR″)3, wherein R′ is C3-C6 alkyl, and R″ is C1-C6 alkyl; at least one organotitanium compound curing catalyst; and at least one filler.

1 .- 19 . (canceled) 
     
     
         20 . A one-part room-temperature curable composition, comprising:
 (A) at least one organosilicon compound containing condensable groups;   (B) at least one curing agent composition, comprising:
 (B)(i) at least one compound having the formula (IV):
   R′Si(OOCR″) 3   (IV)
 
 
   
       wherein 
       R′ each is the same or different and is C 3 -C 6  alkyl, and 
       R″ each is the same or different and is C 1 -C 6  alkyl, and 
       optionally,
 (B)(ii) an additional curing agent other than the compound having the formula (IV), said additional compound having the formula (III):
   Z c SiR 1   (4-c)   (III)
 
 
 
       wherein 
       R 1  each is identical or different and is a monovalent, unsubstituted or substituted hydrocarbon radical, wherein one or more carbon atoms of the hydrocarbon radical are optionally replaced with oxygen atoms, 
       Z each is identical or different and is a condensable radical, and 
       c is 2, 3 or 4;
 (C) at least one curing catalyst comprising an organotitanium compound; and 
 (D) at least one filler; 
 
       wherein curing agent composition (B) comprises at least 60 wt. % of compounds having the formula (IV), based on the total weight of the curing agent composition. 
     
     
         21 . The curable composition of  claim 20 , wherein the curable composition is free of organotin compounds. 
     
     
         22 . The curable composition of  claim 20 , wherein curing agent composition (B) is present in an amount of 2.5 wt.-% or more to 6 wt.-% or less based on the total weight of the curable composition. 
     
     
         23 . The curable composition of  claim 20 , wherein curing agent composition (B) is present in an amount of from 4 to 10 parts by weight, based on 100 parts by weight of component (A). 
     
     
         24 . The curable composition of  claim 20 , wherein component (C) is present in an amount of from 0.001 to 2 parts by weight, based on 100 parts by weight of component (A). 
     
     
         25 . The curable composition of  claim 20 , wherein component (C) is present in an amount of from 0.001 to 0.5 parts by weight, based on 100 parts by weight of component (A). 
     
     
         26 . The curable composition of  claim 20 , wherein the curable composition comprises filler(s) (D) in an amount of greater than 0 and up to 300 parts by weight, based on 100 parts by weight based of organosilicon compound (A). 
     
     
         27 . The curable composition of  claim 20 , wherein the curable composition comprises filler(s) (D) in an amount of from 5 to 150 parts by weight, based on 100 parts by weight of organosilicon compound (A). 
     
     
         28 . The curable composition of  claim 20 , wherein the curable composition contains component (D) in an amount greater than 0 wt.-% and up to 60 wt.-% based on the total weight of the curable composition. 
     
     
         29 . The curable composition of  claim 20 , wherein the organotitanium compound has the formula (V):
   Ti(OR″′) 4   (V)
   wherein R″′ each is the same or different and is C 1 -C 10  alkyl.   
     
     
         30 . The curable composition of  claim 20 , wherein R′ is n-propyl and R″ is methyl. 
     
     
         31 . The curable composition of  claim 29 , wherein R″′ is n-butyl. 
     
     
         32 . The curable composition according to  claim 20 , wherein Z is acetoxy, R′ is methyl and c is 3. 
     
     
         33 . The curable composition of  claim 20 , wherein the curing agent composition (B) further comprises condensates of two or more molecules of the compound having the formula (III), of the compound having the formula (IV)
   R′Si(OOCR″) 3   (IV)
   wherein   R′ each is the same or different and is C 3 -C 6  alkyl, and   R″ each is the same or different and is C 1 -C 6  alkyl,   or mixtures thereof.   
     
     
         34 . The curable composition of  claim 29 , wherein up to 30% of all Si atoms in the curing agent are contained in the condensates. 
     
     
         35 . The curable composition of  claim 20 , wherein the condensable groups of organosilicon compound (A) are selected from hydroxyl groups, acetoxy groups, or a combination thereof. 
     
     
         36 . The curable composition of  claim 20 , wherein the organosilicon compound (A) comprises units of the formula (I):
   R a Y b SiO (4-a-b)/2   (I)
   wherein   R each is identical or different and is a substituted or unsubstituted hydrocarbon radical, wherein one or more carbon atoms of the hydrocarbon radical are optionally replaced with oxygen atoms,   Y each is identical or different and is a hydroxy radical or acyloxy radical,   a is 0, 1, 2, or 3, and   b is 0, 1, 2, or 3,   with the proviso that the sum of a and b is less than or equal to 3 and at least two Y radicals are present per molecule of the organosilicon compound.   
     
     
         37 . The curable composition of  claim 20 , wherein the organosilicon compound (A) is a polyorganosiloxane of the formula (II):
   Y 3-f R f SiO—(SiR 2 O) e —SiR f Y 3-f   (II)
   wherein   R each is identical or different and is a substituted or unsubstituted hydrocarbon radical, wherein one or more carbon atoms of the hydrocarbon radical are optionally replaced with oxygen atoms,   Y each is identical or different and is a hydroxy radical or acyloxy radical,   e is from 30 to 3000, and   f is 1 or 2.   
     
     
         38 . The curable composition of  claim 20 , wherein the filler (D) comprises fumed silica. 
     
     
         39 . The curable composition of  claim 20 , wherein the composition further comprises one or more components selected from the group consisting of
 (E) plasticizers,   (F) coupling agents, and   (G) further additives.   
     
     
         40 . A molding produced by cross-linking a composition of  claim 20 .