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
1997-10-10
1998-12-22
Niland, Patrick D.
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...
524196, 524507, 524589, 524590, 524591, 524840, C08J 300, C08K 320, C08L 7500
Patent
active
058521119
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a novel highly emulsifiable polyisocyanate composition, and a cold crosslinkable, two-pack aqueous urethane coating composition, which comprises an aqueous polyol and the highly emulsifiable polyisocyanate composition. More particularly, the present invention is concerned with a novel highly emulsifiable and stable polyisocyanate composition, which comprises (a) a hydrophilic polyisocyanate comprising at least one base polyisocyanate having a nonionic hydrophilic group bonded thereto, wherein the base polyisocyanate is selected from an aliphatic and/or an alicyclic diisocyanate, and a polyisocyanate derived therefrom, and (b) a substantially water-free ionic surfactant. The present invention is also concerned with a cold crosslinkable, two-pack aqueous urethane coating composition, which comprises an aqueous polyol as a main agent, and the above-mentioned novel polyisocyanate composition as a curing agent. The aqueous coating composition of the present invention has not only excellent pot life characteristics, but also is capable of forming a coating which has excellent properties, such as excellent water resistance. Therefore, the aqueous coating composition of the present invention can be advantageously used as an aqueous paint for building materials or automobiles, an aqueous paint for domestic use, an adhesive, a building material, and various other coating materials and sealing materials. Further, the aqueous coating composition of the present invention can also be used as a crosslinking agent for use in a vehicle for an ink, a curing agent for use in cast molding, a crosslinking agent for a resin component such as an elastomer and for a urethane foam or the like, and a finish coating agent for a fiber and a textile fabric.
PRIOR ART
In recent years, guidelines on volatile organic compounds have been becoming strict increasingly, and in countries including the United States and Germany, the use of volatile organic compounds has already been restricted. Therefore, it has been desired to develop a cold crosslinkable, two-pack aqueous urethane coating composition as a substitute for conventional cold crosslinkable, two-pack non-aqueous urethane coating compositions which contain an organic solvent. However, a polyisocyanate which is used as a curing agent in a 2-pack urethane coating composition has problems in that it has poor dispersibility in water and is likely to react with water to generate carbon dioxide.
For this reason, in Examined Japanese Patent Application Publication No. 55-7472 (corresponding to U.S. Pat. No. 3,996,154) and Unexamined Japanese Patent Application Laid-Open Specification No. 5-222150 (corresponding to U.S. Pat. No. 5,252,696), for obtaining a highly emulsifiable polyisocyanate, it is proposed to introduce a nonionic hydrophilic group into a polyisocyanate. In order to improve the dispersibility of a polyisocyanate, Unexamined Japanese Patent Application Laid-Open Specification No. 6-17004 proposes the use of a modified aqueous polyol as a main component for a coating composition, wherein the modified polyol has, introduced therein, a specific carboxylic acid group or a sulfonic acid group which can impart emulsifiability to a polyisocyanate. In Unexamined Japanese Patent Application Laid-Open Specification No. 7-48429 (corresponding to U.S. Pat. No. 5,373,050) and Unexamined Japanese Patent Application Laid-Open Specification No. 7-113005, a polyisocyanate having introduced therein both a nonionic hydrophilic group and a nonionic oleophilic group, is proposed in order to prolong the pot life of a urethane coating composition.
However, since the above-mentioned conventional polyisocyanates have only a nonionic hydrophilic group as a hydrophilic group, not only is there a problem that when these polyisocyanates are dispersed in water, a reactivity between an isocyanate group and water cannot be satisfactorily suppressed, but also a coating composition having a pot life at a practically employable level, cannot be obtained. Fu
REFERENCES:
patent: 4663377 (1987-05-01), Hombach et al.
patent: 5252696 (1993-10-01), Laas et al.
Ibuki Ichiro
Watanabe Shinichiro
Asahi Kasei Kogyo Kabushiki Kaisha
Niland Patrick D.
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