Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From reactant having at least one -n=c=x group as well as...
Reexamination Certificate
1999-06-15
2001-07-03
Gorr, Rachel (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From reactant having at least one -n=c=x group as well as...
C528S059000, C528S073000, C524S267000, C524S443000
Reexamination Certificate
active
06255433
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a one-package thixotropic polyurethane resin composition excellent in storage stability and curability and having low modulus and controlled foaming.
BACKGROUND OF THE INVENTION
Urethane prepolymers having terminal free isocyanate groups can be cured with moisture contained in the air or a substrate at room temperature, and have been employed for sealants, waterproofing materials, floor covering materials, wall covering materials, paving materials, coatings, adhesives and the like because of their excellent properties such as physical properties of the cured products obtained therefrom and adhesiveness. However, drawbacks to deteriorate their physical properties and appearance by foaming caused by generation of carbon dioxide gas associated with curing have been pointed out.
For the purpose of preventing foaming caused by the generation of carbon dioxide gas when the curing of such urethane prepolymers proceeds, AU-B-20324/88, U.S. Pat. No. 3,743,626, U.S. Pat. No. 5,473,043 and Japanese unexamined patent publication No. 293821/1994 and the like propose to use oxazolidine compounds.
In general, the use of the oxazolidine compounds for preparing urethane prepolymers causes the increase in crosslinking density of the cured products due to the act of the oxazolidine compounds as a crosslinking agent. The modulus of the cured products also increases with the increase in the crosslinking density. Heretofore, the use of such oxazolidine compounds for urethane prepolymers for the sealants has a problem that joint following-up properties of sealants are deteriorated due to the excessively high modulus of the cured products.
Although many sealants usually include thixotropic agents such as fine powder silica and surface-treated calcium carbonate, the hydrophilic fine powder silica, which has much moisture attaching thereon, causes a problem that sealants become viscous during storage. The surface-treated calcium carbonate is problematic in that the surface-treating agent elutes during storage and then coheres to form solid which deteriorates the appearance of the sealants.
SUMMARY OF THE INVENTION
The present inventors have intensively studied to find that a one-package thixotropic polyurethane resin composition comprising a urethane prepolymer having a terminal free isocyanate group(a) which is obtained by reacting a polyisocyanate(b), a compound having two or more active hydrogen(c), a monool(d) and an N-hydroxyalkyl-oxazolidine compound(e), hydrophobic fine powder silica(f) and an oxazolidine-ring opening accelerator(g) excels in storage stability and curability, and is suitable as a low modulus-type sealant having low modulus and controlled foaming, and have accomplished the present invention on the basis of that finding. Namely, the present invention provides:
1. A one-package thixotropic polyurethane resin composition comprising 10 to 90% by weight of a urethane prepolymer having a terminal free isocyanate group(a) which is obtained by reacting a polyisocyanate(b) with a compound having two or more active hydrogens(c), a monool(d) and an N-hydroxyalkyl-oxazolidine compound(e), 0.1 to 20% by weight of hydrophobic fine powder silica(f) and 0.01 to 3.0% by weight of an oxazolidine-ring opening accelerator(g).
2. The one-package thixotropic polyurethane resin composition according to 1, wherein the component(f) has a hydrophobic degree of 30% or more.
3. The one-package thixotropic polyurethane resin composition according to 1, wherein the component(d) has an average molecular weight of 100 to 3000.
4. The one-package thixotropic polyurethane resin composition according to 1, wherein the component(a) has an isocyanate group content of 0.5 to 5.0% by weight based on the whole composition.
5. The one-package thixotropic polyurethane resin composition according to 1, wherein the component(a) is obtained in 1.3 to 5.0 of an NCO/H equivalent ratio of an NCO group in the component(b) relative to an active hydrogen in the component(c), 2 to 50 of an NCO/OH equivalent ratio of an NCO group in the component(b) relative to an OH group in the component(d) and 2 to 10 of an NCO/OH equivalent ratio of an NCO group in the component(b), excepting that for reacting with the active hydrogen in the component(c) and the OH group in the component(d), relative to an OH group in the component(e).
6. The one-package thixotropic polyurethane resin composition according to 1, wherein the component(e) is a compound represented by the formula (I):
wherein R
1
represents a C
2-5
alkylene group, R
2
represents a hydrogen or a C
1-3
alkyl group, R
3
and R
4
are identical of different and represent a hydrogen or a C
1-20
hydrocarbon group.)
7. The one-package thixotropic polyurethane resin composition according to 1, which is a sealant.
DETAILED DESCRIPTION OF THE INVENTION
Examples of the polyisocyanate(b) used in the present invention include, but are not limited to, polyisocyanates conventionally used in production of polyurethane resin including aromatic diisocyanates such as m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4- or 2,6-tolylene diisocyanate, 4,4′-toluidine diisocyanate, 4,4′-diphenyl ether diisocyanate, aromato aliphatic diisocyanates such as 1,3- or 1,4-xylylene diisocyanate or a mixture thereof, aliphatic diisocyanates such as trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate and 2,6-diisocyanatomethyl caproate, alicyclic diisocyanates such as 1,3-cyclopentene diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 4,4′-methylenebis(cyclohexylisocyanate), methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate and 1,4-bis(isocyanatomethyl)cyclohexane, their carbodiimide-modified forms, biuret-modified forms, allophanate-modified forms, dimers and timers. These may be used alone or in combination with two or more of them.
Examples of the compounds having two or more active hydrogens(c) used in the present invention include low molecular weight diols with molecular weight of 350 of less such as an alkylene (C2-22) glycol, e. g., ethylene glycol, propylen glycol, 1,4-butylene glycol, 1,3-butylene glycol, 1,2-butylene glycol, 1,6-hexanediol, neopentyl glycol; poly(alkylene(C2-15) glycol), e.g., diethylene glycol, triethylene glycol, dipropylene glycol; other glycols such as cyclohexane dimethanol, hydrogenated bisphenol A, 1,4-dihydroxy-2-butene, 2,6-dimethyl-1-octene-3,8-diol, bishydroxyethoxybenzene, xylene glycol, bishydroxyethylene terephthalate; low molecular weight triols with molecular weight of 350 of less such as glycerin, 2-methyl-2-hydroxymethyl-1,3-propanediol, 2,4-dihydroxy-3-hydroxymethyl-pentane, 1,2,6-hexanetriol, 1,1,1-tris(hydroxymethyl)propane, 2,2-bis(hydroxymethyl)-3-butanol and other aliphatic triols (C8-20); low molecular weight diamines with molecular weight of 350 of less such as ethylenediamine, propylenediamine, hexamethylenediamine, hydrazine, 1,2-diaminoethane, 1,2-diaminopropane, 1,3-diaminopentane, 1,6-diaminohexane diaminotoluene, bis-(4-aminophenyl)methane and bis-(4-amino-3-chlorophenyl)methane; low molecular weight polyamines with molecular weight of 350 of less having a functionality of three or more such as diethylenetriamine, triethylene-tetramine, tetraethylenepentamine, pentaethylenehexamine and 2,2′-diaminodiethylamine; polyoxyalkylene polyols obtained by addition reactions of the foregoing low molecular weight diols, triols, diamines, polyamines having a functionality of three or more with alkylene oxides such as ethylene oxide and propylene oxide; polytetramethylene glycols obtained by a ring-opening polymerization of tetrahydrofuran; polyesterpolyol
Kuroda Kenji
Miwa Masahiro
Miyagawa Masamitsu
Gorr Rachel
Takeda Chemical Industries Ltd.
Wenderoth , Lind & Ponack, L.L.P.
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