Hydrogenated diblock copolymers for adhesives and sealants with improved resistance to degradation

Abstract

Adhesive and sealant compositions having improved resistance to a degradation which comprises: (a) a hydrogenated triblock, multiblock, radial, or star block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene, (b) from 3 to 50 percent by weight of the total composition of a hydrogenated diblock copolymer of a vinyl aromatic hydrocarbon and a conjugated diene wherein the overall molecular weight of the diblock ranges from 8000 to 100,000, the molecular weight of the poly vinyl aromatic hydrocarbon block ranges from 4000 to 32,000, the molecular weight of the poly conjugated diene block ranges from 3000 to 90,000, and the vinyl aromatic hydrocarbon content ranges from 30 to 70 percent by weight of the diblock copolymer, and (c) 20 to 400 parts by weight per 100 parts by weight of total block copolymers of a tackifying resin.

I claim: 
     
       1. An adhesive composition having improved resistance to degradation which comprises: (a) a hydrogenated triblock, multiblock, radial, or star block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene,   (b) from 3 to 50 percent by weight of the total composition of a hydrogenated diblock copolymer of a vinyl aromatic hydrocarbon and a conjugated diene wherein the overall molecular weight of the diblock ranges from 8000 to 100,000, the molecular weight of the poly vinyl aromatic hydrocarbon block ranges from 4000 to 32,000, the molecular weight of the poly conjugated diene block ranges from 3000 to 90,000, and the vinyl aromatic hydrocarbon content ranges from 30 to 70 percent by weight of the riblock copolymer, and   (c) 20 to 400 parts by weight per 100 parts by weight of total block copolymers of a tackifying resin.   
     
     
       2. The adhesive composition of claim 1 wherein the diblock comprises from 8 to 20 percent by weight of the total block copolymer composition. 
     
     
       3. An sealant composition having improved resistance to degradation which comprises: (a) a hydrogenated triblock, multiblock, radial, or star block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene,   (b) from 3 to 50 percent by weight of the total composition of a hydrogenated diblock copolymer of a vinyl aromatic hydrocarbon and a conjugated diene wherein the overall molecular weight of the diblock ranges from 8000 to 100,000, the molecular weight of the poly vinyl aromatic hydrocarbon block ranges from 4000 to 32,000, the molecular weight of the poly conjugated diene block ranges from 3000 to 90,000, and the vinyl aromatic hydrocarbon content ranges from 30 to 70 percent by weight of the diblock copolymer, and   (c) 20 to 400 parts by weight per 100 parts by weight of total block copolymers of a tackifying resin.   
     
     
       4. The sealant composition of claim 3 wherein the diblock comprises from 8 to 20 percent by weight of the total block copolymer composition.