Primer composition and curtain wall unit

Abstract

Provided are a primer composition that can adhere well to a variety of adherends and ensures a long workable time together with excellent durability, and a curtain wall unit. A primer composition comprising: (A) 100 parts by mass of an organosiloxane polymer having a three-dimensional network structure comprising R 3 SiO 1/2 units (R independently represents a C1-6 substituted or unsubstituted monovalent hydrocarbon group) and SiO 4/2 units, the molar ratio of R 3 SiO 1/2 units to SiO 4/2 units being 0.6-1.2; (B) 300-1,000 parts by mass of a mixture of organo-oxy-group-containing titanium compounds containing 75 mol % or more of an organo-oxy-group-containing titanium compound represented by formula ( 1 ) Ti(OR 1 ) 3 (R 2 CH 2 COCH 2 COOCH 2 R 2 ) 1   ( 1 ) (R 1 may be the same or different and are substituted or unsubstituted monovalent hydrocarbon groups, R 2 may be the same or different and are hydrogen atoms and/or substituted or unsubstituted monovalent hydrocarbon groups); and (C) 1,000-8,000 parts by mass of a solvent.

1 . A primer composition effective for improving the adhesion between a substrate selected from organic resins, metals and resin-painted metals and a cured product of a room temperature curable organopolysiloxane composition, the primer composition comprising:
 (A) 100 parts by weight of an organosiloxane polymer of three-dimensional network structure comprising R 3 SiO 1/2  units and SiO 4/2  units, a molar ratio of R 3 SiO 4/2  units to SiO 4/2  units being 0.6 to 1.2, wherein R is each independently a substituted or unsubstituted monovalent hydrocarbon group of 1 to 6 carbon atoms,   (B) 300 to 1,000 parts by weight of a titanium compound having the formula (1) or a mixture of organooxy-containing titanium compounds containing at least 75 mol % of a titanium compound having the formula (1):
   Ti(OR 1 ) 3 (R 2 CH 2 COCH 2 COOCH 2 R 2 ) 1    (1)
 
   
       wherein R 1  which may be the same or different is a substituted or unsubstituted monovalent hydrocarbon group, and R 2  which may be the same or different is hydrogen and/or a substituted or unsubstituted monovalent hydrocarbon group, and
 (C) 1,000 to 8,000 parts by weight of a solvent. 
 
     
     
         2 . The primer composition of  claim 1  wherein component (B) is a mixture of reaction products which are formed by mixing (B1) a tetraorganooxytitanium and/or partial hydrolytic condensate thereof and (B2) an acetoacetate in a ratio of from 0.8 mole to less than 1.2 moles of acetoacetate (B2) per mole of titanium atoms in (B1). 
     
     
         3 . The primer composition of  claim 1  wherein component (B) is a mixture of reaction products which are formed by mixing (B1) a tetraorganooxytitanium and/or partial hydrolytic condensate thereof and (B3) an organooxy-containing titanium chelate compound having two acetoacetate chelates per titanium atom, in a ratio of from 0.8 mole to less than 1.2 moles of the organooxy-containing titanium chelate compound having two acetoacetate chelates per titanium atom (B3) per mole of titanium atoms in (B1). 
     
     
         4 . The primer composition of any one of  claims 1  to  3  which is free of an amino-containing silane coupling agent, epoxy-containing silane coupling agent, and isocyanurate ring-containing silane. 
     
     
         5 . The primer composition of  claim 1  which has a working life of at least 20 minutes after it is transferred from a closed container to an open container in an environment of temperature 23° C. and relative humidity 50%. 
     
     
         6 . In connection with a curtain wall unit for securing glass, comprising a frame of metal and/or resin-painted metal and a silicone rubber layer disposed on the surface of the frame and composed of a cured product of a two-part dealcoholization type room temperature-curable organopolysiloxane composition,
 the primer composition of  claim 1  which is used as a primer to the metal and/or painted metal surface.   
     
     
         7 . A curtain wall unit wherein a cured product layer of a room temperature-curable organopolysiloxane composition is bonded to a metal and/or painted metal surface through a coating layer of the primer composition of  claim 6 .