Water swellable sealant
AssigneeAsahi Denka Kogyo Kabushiki Kaisha
InventorsTakuo Fukushima, Yasumasa Hayashida, Jinichi Omi
Life of this patent
Estimating the term…
Abstract
Water-swellable moisture-curing one-package polyurethane sealant which includes (1) a water-swellable polyurethane prepolymer having 1.5-10% terminal NCO group content obtained by reacting polyisocyanate with polyoxyalkylenepolyol having 50-90% of oxyethylene units based on polyalkylene chain molecular weight (2) non water-swellable polyurethane prepolymer having terminal NCO groups obtained by reacting polyisocyanate with polyoxyalkylenepolyol having 3-4 carbon atom oxyalkylene units, and (3) a filler. The sealant exhibits has been improved storage stability.
Claims22
A water-swellable moisture-curing one-package polyurethane sealant comprising:
- (1) 20 to 100 parts by weight of a water-swellable polyurethane prepolymer having 1.5-10% terminal NCO group content which is obtained by a polyisocyanate with one or more polyetherpolyols having the following general formula,
- R((OR.sub.1).sub.n OH).sub.p (I)
- wherein R is a polyhydric alcohol radical;
- (OR.sub.1).sub.n is a polyoxyalkylene chain comprising 50-90 weight % of oxyethylene units and 50-10 weight % of oxyalkylene units having 3-4 carbon atoms;
- n is a number which represents the polymerization degree of said polyoxyalkylene chain, such that n restricts the hydroxy group equivalent of said polyetherpolyol (I) to the range 500-4000;
- and p is a number selected from 2-8;
- (2) 100 parts by weight of a non water-swellable polyurethane prepolymer having terminal NCO groups obtained by reacting a polyisocyanate with one or more polyetherpolyols having the following general formula,
- R.sub.2 ((OR.sub.3).sub.m OH).sub.q (II)
- wherein R.sub.2 is a polyhydric alcohol radical;
- (OR.sub.3).sub.m is a polyoxyalkylene chain comprising oxyethylene units having 3-4 carbon atoms;
- m is a number which represents the polymerization degree of said polyoxyalkylene chain, such that m restricts the hydroxy group equivalent of said polyetherpolyol (II) to the range 500-4000;
- and q is a number selected from 2-8;
- and
- (3) 2 to 100 parts by weight of a filler.
A method of preparing a water-swellable moisture-curing one-package polyurethane sealant comprising:
- (a) mixing 2 to 100 parts by weight of a filler and 100 parts by weight of a non water-swellable polyurethane prepolymer having terminal NCO groups obtained by reacting polyisocyanate with one or more polyetherpolyols having the following general formula,
- R.sub.2 ((OR.sub.3).sub.m OH).sub.8 (II)
- wherein R.sub.2 is a polyhydric alcohol radical;
- (OR.sub.3).sub.m is a polyoxyalkylene chain comprising oxyethylene units having 3-4 carbon atoms;
- m is a number which represents the polymerization degree of said polyoxyalkylene chain, such that m restricts the hydroxy group equivalent of said polyetherpolyol (II) to the range 500-4000;
- and q is a number selected from 2-8, to form a non water-swellable polyurethane composition,
- (b) adding to said non water-swellable polyurethane composition 20 to 100 parts by weight of a water swellable polyurethane prepolymer having 1.5-10% terminal NCO group content which is obtained by reacting polyisocyanate with one or more polyetherpolyols having the following general formula,
- R((OR.sub.1).sub.n OH).sub.p (I)
- wherein R is a polyhydric alcohol radical;
- (OR.sub.1).sub.n is a polyoxyalkylene chain comprising 50-90 weight % of oxyethylene units and 50-10 weight % of oxyalkylene units having 3-4 carbon atoms;
- n is a number which represents the polymerization degree of said polyoxyalkylene chain, such that n restricts the hydroxy group equivalent of said polyetherpolyol (I) to the range 500-4000;
- and p is a number selected from 2-8.
Dependencies are inferred from the claim text.