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
2001-10-17
2003-10-14
Woodward, Ana (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...
C525S065000, C525S066000, C525S080000
Reexamination Certificate
active
06632913
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for producing a liquid urethane prepolymer and to a resin composition using the same. More precisely, it relates to a method for producing an isocyanate group-blocked urethane prepolymer which is used for artificial leathers, synthetic leathers, paints, coating agents, adhesives, sealants, pressure sensitive adhesives, films, sheets, cast articles, and the like, and is liquid even without solvent. The present invention also relates to a resin composition using the same.
BACKGROUND OF THE INVENTION
Recently, it is required to reduce organic solvents from solution type resins such as paints wherein organic solvents are used, from the viewpoint of global environmental regulations. In particular, by the enforcement of PRTR Law, revised Industrial Safety and Health Law, and the like, the reduction of organic solvents and the like becomes a very important theme. The same applies to solution-type urethane resins which are used for synthetic leathers, artificial leathers, adhesives, films, and the like, and thus, there has been carried out researches for developing solvent-free urethane resins containing no organic solvent. In general, urethane resins have very large molecular weight and therefore, without solvent, they becomes rubbery solid which does not flow at all at room temperature, so that it is impossible to subject them to processing such as coating, impregnation, and the like. In some cases, lowering the molecular weight improves flowability and thus enables processing such as coating, impregnation, and the like, but the resulting resin exhibits poor mechanical strength and durability owing to the small molecular weight and is unsuitable for use.
As methods for improving the above, there are proposed methods wherein a liquid substance having a low molecular weight is used at processing such as coating, impregnation, and the like for enabling the processing even without solvent, and is subjected to thermal treatment after the processing to form a substance having a high molecular weight. For example, JP-B-1-21190 (The term “JP-B” used herein means an examined Japanese patent publication.) discloses a method wherein an isocyanate group-blocked urethane prepolymer (an oligomer obtained by reacting excess molar amount of polyfunctional isocyanate with a polyol and further blocking the isocyanate group) and a diamine as a chain extending agent or a crosslinking agent are blended and processing such as coating and the like is carried out, then the blockage is removed by thermal treatment, and the resulting substance is reacted with the diamine to form a substance having a high molecular weight substance. In the patent publication, it is described that a polyether having 2 to 3 hydroxyl groups and a molecular weight of 500 to 10000 and/or a polyester having 2 to 3 hydroxyl groups and a molecular weight of 1000 to 6000 can be used as the polyol. Furthermore, according to the patent publication, a liquid substance without solvent can be formed only in the case that a propylene oxide-type polyether is used as the polyol, and liquid substance is not formed in the case of combined use of the polyether and a polyester or sole use of a polyester. That is, in the conventional technology, for obtaining a liquid isocyanate group-blocked urethane prepolymer without solvent, only a propylene oxide-type polyether can be used as the polyol. However, a polyurethane polyurea resin prepared by using a prepolymer made from a propylene oxide-type polyether has serious defects that thermal resistance, light resistance, mechanical resistance, and the like are poor, and therefore, is practically problematic.
SUMMARY OF THE INVENTION
In view of the circumstances as described above, an object of the invention is to provide an isocyanate group-blocked urethane prepolymer which is liquid without solvent and which may be used as a main material for polyurethane resins excellent in durability such as thermal resistance and light resistance and in mechanical strength.
Other objects and effects of the present invention will become apparent from the following description.
As a result of extensive studies on the above problems, the present inventors found that an isocyanate group-blocked urethane prepolymer, which is obtained by adding a lactone monomer to a diol selected from a polyalkylene ether diol, a polyester diol and a polycarbonate diol to form a lactone-modified diol and reacting it with a polyfunctional isocyanate, becomes liquid even without solvent. Furthermore, they also found that a polyurethane resin prepared by using the prepolymer has extremely excellent durability such as thermal resistance and light resistance and has extremely excellent mechanical strength as compared with a resin wherein a propylene oxide-type polyether is used. Based on the findings, the present invention has been accomplished.
That is, the present invention relates to a method for producing an isocyanate group-blocked liquid urethane prepolymer which comprises:
reacting a lactone-modified diol (3) with a polyfunctional isocyanate (4) to form an isocyanate group-having urethane prepolymer (5), wherein said lactone-modified diol (3) is obtainable by ring-opening addition polymerization of a lactone monomer (2) with a diol (1) selected from the group consisting of a polyalkylene ether diol, a polyester diol and a polycarbonate diol; and then
reacting said urethane prepolymer with a blocking agent (6).
The present invention also relates a resin composition comprising a liquid urethane prepolymer obtained by the above-described production method and a compound having two or more active hydrogens.
DETAILED DESCRIPTION OF THE INVENTION
The polyalkylene ether diol for use in the invention generally includes products of homopolymerization of any of intramolecular cyclic ether compounds such as ethylene oxide, 1,2- and 1,3-propylene oxide, 1,2-, 2,3- and 1,4-butylene oxide and an alkyltetrahydrofuran, and products of random or block copolymerization of two or more of them, and the like. Particularly preferred are ring opening polymerization products and addition polymerization products, of 1,4-butylene oxide (tetrahydrofuran) alone or of two or more alkylene oxides including the same.
The polyester diol for use in the invention includes reaction products of a dihydric alcohol with a dibasic carboxylic acid. Instead of a free dicarboxylic acid, a corresponding acid anhydride, a diester of a lower alcohol, or a mixture thereof may be used for the production of the polyester.
The dihydric alcohol is not especially limited, and includes ethylene glycol, 1,3- and 1,2-propylene glycol, 1,4- and 1,3- and 2,3-butylene glycol, 1,5-pentanediol, 1,6-hexane glycol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, neopentyl glycol, cyclohexanedimethanol, 1,4-bis-(hydroxymethyl)-cyclohexane, 2-methyl-1,3-propanediol, 2,2,4-trimethyl-1,3-pentanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, dibutylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and the like.
The dibasic carboxylic acid may be aliphatic, alicyclic, aromatic and/or heterocyclic, may be saturated or unsaturated, and may be substituted by, for example, a halogen atom. Examples of the carboxylic acid include, though not limited thereto, succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, trimesic acid, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, tetrahydroisophthalic anhydride, hexahydroisophthalic anhydride, endomethylenetetrahydrophthlic anhydride, glutaric anhydride, maleic anhydride, maleic acid, fumaric acid, dimeric fatty acid, e.g., oleic acid, dimethyl terephthalate, and mixed terephthalate.
Among them, particularly preferred is a polyester diol obtained from an alkylene glycol having 2 to 10 carbon atoms and adipic acid.
The polycarbonate diol for use in the invention includes reaction products of a diol such as ethylene glycol, 1,3- and
Matsumoto Yasuhiro
Takeuchi Hideyuki
Tanaka Hiroki
Armstrong Westerman & Hattori, LLP
Dainippon Ink and Chemicals Inc.
Woodward Ana
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