Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Patent
1986-01-29
1989-03-28
Hoke, Veronica P.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
524425, 524590, 524875, 4284258, C08K 340, C08K 326, C08K 322, C08K 304
Patent
active
048165093
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a water-swellable moisture-curing one-package polyurethane sealant of which storage stability is improved.
More particularly, the present invention relates to a water-swellable moisture-curing one-package polyurethane sealant which has a rapid curing rate, take a short time to become tack free, exhibits excellent mechanical strength in its cured form, and exhibits excellent water-sealing effects.
DESCRIPTION OF THE PRIOR ART
A one package type polyurethane sealant has conventionally been widely used for sealing material, binder material, and caulking material in the field of public and construction works. Recently, use of water-swellable material has gradually become popular in order to improve the water-sealing effect for joint sealing or on hume pipies. A water-swellable one-package sealant is very much required in the public and construction works because of its easy workability and excellent water-sealing effect.
Japanese patent (examined) No. 49-30209 discloses a fairly good polyurethane sealant. It has, however, insufficient storage stability in the case that a filler is added in order to adapte the sealant to practical use. This is caused by an increase in the viscosity or partial curing induced by the reaction of the water in the filler and the urethanprepolymer.
SUMMARY OF THE INVENTION
The inventors studied the storage stability of the sealant and discovered that a mixture of a specific water-swellable polyurethane prepolymer and a non water-swellable polyurethane prepolymer produces a water-swellable moisture-curing one-package polyurethane prepolymer which possesses remarkably improved storage stability.
The water-swellable moisture-curing one-package polyurethane sealant of the present invention essentially comprises,
(1) water-swellable polyurethane prepolymer having a content of 1.5-10% of terminal NCO groups which is obtained by reacting polyisocyanate with one or more polyetherpolyols having the following general formula, polyoxyalkylene chain comprising 50-90 weight % of oxyethylene units and 50-10 weight % of oxyalkylene units having 3-4 carbon atoms; n is the number which represents the polymerization degree of said polyoxyalkylene chain, such that n restricts the hydroxy group equivalent of the said polyetherpolyol in the range 500-4000; and p is a number selected from 2-8
(2) A non water-swellable polyurethane prepolymer having terminal NCO groups obtained by reacting polyisocyanate with one or more polyetherpolyols, having the following general formula, polyoxyalkylene chain comprising oxyalkylene 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 in the range 500-4000; and
q is a number selected from 2-8 and (3) a filler.
DETAILED DESCRIPTION OF THE INVENTION
The preferred examples of the polyhydric alcohols which correspond to R in the above general formula (I) are aliphatic dihydric alcohols (ethylene glycol, propylene, glycol, 1,4-butylene glycol, neopentyl glycol etc.), aliphatic trihydric alcohols, (glycerol, trioxyisobutane, 1,2,3-butanetriol, 2-methyl-1,2,3-propanetriol, 2-ethyl-1,2,3-butanetriol, 2,3,4-pentanetriol, 2,3,4-hexanetriol, 4-propyl-3,4,5-heptanetriol, 2,4-dimethyl-2,3,4-pentanetriol, pentamethylglycerol, pentaglycerol, 1,2,4-butanetriol, 1,2,4-pentanetriol, trimethylolpropane etc.), aliphatic tetrahydric alcohols (erythrite, pentaerythrite, 1,2,3,4-pentanetetrol, 2,3,4,5-hexanetetrol, 1,2,3,5-pentanetetrol, 1,3,4,5-hexanetetrol etc.), aliphatic pentahydric alcohols (adonite, arabit, xylit etc.), aliphatic hexahydric alcohols (sorbit, mannit, idite etc.). The preferred polyhydric alcohols are di, tri, or tetrahydric alcohols, particularly propylene glycol and glycerol.
Polyetherpolyols represented by the above general formula (I) can be obtained by adducting ethylene oxide and alkylene oxides having 3-4 carbon atoms to the above-noted polyhydric alcohols usin
REFERENCES:
patent: 3094495 (1963-06-01), Gemeinhardt
patent: 3730927 (1973-05-01), Schloss
patent: 4513112 (1985-04-01), Ernst et al.
Fukushima Takuo
Hayashida Yasumasa
Omi Jinichi
Asahi Denka Kogyo K.K.
Hoke Veronica P.
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