Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
2000-05-17
2001-09-04
Cooney, Jr., John M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C521S172000, C521S173000, C528S080000, C528S083000, C560S025000, C560S026000, C560S076000, C560S091000, C560S115000, C560S158000, C560S330000, C560S336000
Reexamination Certificate
active
06284811
ABSTRACT:
TECHNICAL FIELD
The present invention is directed to a process for preparing a polyurethane foam. More specifically, the present invention is directed to a process for preparing a polyurethane foam which has high mechanical strength and can be suitably used as shoe soles, to a process for preparing an isocyanate prepolymer used as a starting material of the polyurethane foam, and to a polyester-polyol used as a starting material of the polyurethane foam.
BACKGROUND ART
When preparing a polyurethane foam, it is desirable that the density of the polyurethane foam to be decreased, because the cost of preparing becomes less. However, the mechanical strength of the polyurethane foam is lowered when its density is decreased because the amount of a resin per unit volume is reduced.
In order to improve the mechanical strength of the polyurethane foam, there has been proposed to use additives such as a cross-linking agent, a polyfunctional polyol and an aromatic polyol together with the starting polyol.
The above proposal, however, has some problems. That is, the use of the cross-linking agent and the polyfunctional polyol in the preparation of an isocyanate prepolymer tends to cause gelation. Also, when a prepolymer which is made from the aromatic polyol is used as a starting material for a polyurethane foam, it is difficult to adjust the viscosity and melting point of the prepolymer to a level suitable for the preparation of a polyurethane foam because the aromatic polyol has a remarkably high viscosity and a high melting point.
One object of the present invention is to provide a process for preparing a polyurethane foam which has a low density, acceptable appearance and texture, and excellent mechanical strength, such as tensile strength and tear strength.
The above and other objects of the present invention will be apparent from the following description.
DISCLOSURE OF INVENTION
The present invention is directed to:
(1) a polyester-polyol being liquid at 40° C. and having a viscosity of not more than 10,000 mPa·s at 60° C., prepared by polycondensation of:
(A) an acid component comprising at least one phthalic acid component selected from phthalic anhydride and o-phthalic acid, and an aliphatic polybasic acid, with
(B) a polyhydric alcohol;
(2) a process for preparing a polyurethane foam comprising reacting a polyisocyanate component with a polyol component comprising the polyester-polyol according to item (1) to foam; to produce a polyurethane foam;
(3) a process for preparing an isocyanate prepolymer which comprises reacting (a) a polyol comprising a polyester-polyol being liquid at 40° C. and having a viscosity of not more than 10,000 mPa·s at 60° C., prepared by polycondensation of (A) an acid component comprising at least one phthalic acid component selected from phthalic anhydride and o-phthalic acid, and an aliphatic polybasic acid, with (B) a polyhydric alcohol; with (b) a polyisocyanate; and
(4) a process for preparing a polyurethane foam comprising reacting an isocyanate prepolymer prepared according to the process of item (3) with a polyol component to foam; to produce a polyurethane foam.
BEST MODE FOR CARRYING OUT THE INVENTION
The polyester-polyol of the present invention is useful as a starting material for preparing a polyurethane foam.
The polyester-polyol of the present invention is prepared by the polycondensation of:
(A) an acid component comprising at least one phthalic acid component selected from phthalic anhydride and o-phthalic acid, and an aliphatic polybasic acid; with
(B) a polyhydric alcohol.
As the phthalic acid component, at least one phthalic acid component selected from phthalic anhydride and o-phthalic acid is used. Therefore, phthalic anhydride and o-phthalic acid may be used alone or in admixture thereof.
Aliphatic polybasic acids include, for example, saturated aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic -acid, suberic acid, azelaic acid, sebacic acid, nonamethylenedicarboxylic acid, decamethylenedicarboxylic acid, undecamethylenedicarboxylic acid, dodecamethylenedicarboxylic acid, tridecamethylenedicarboxylic acid, tetradecamethylenedicarboxylic acid, pentadecamethylenedicarboxylic acid, hexadecamethylenedicarboxylic acid, heptadecamethylenedicarboxylic acid, octadecamethylenedicarboxylic acid, nonadecamethylenedicarboxylic acid, eicosamethylenedicarboxylic acid, heneicosamethylenedicarboxylic acid, docosamethylenedicarboxylic acid, tetracosamethylenedicarboxylic acid, octacosamethylenedicarboxylic acid, and dotriacontamethylenedicarboxylic acid. The aliphatic polybasic acids can be used alone or in admixture thereof. Among them, adipic acid can be favorably used from the viewpoints of providing a polyurethane foam having excellent hydrolysis resistance and excellent tensile strength in good balance, having high safety and being inexpensive.
The acid component comprises a phthalic acid component and-an aliphatic polybasic acid. With respect to the acid component, the term “comprising” means that the acid component is composed of the phthalic acid component and the aliphatic polybasic acid, or may contain other acid components than the phthalic acid component and the aliphatic polybasic acid, so long as the other acid components do not hinder the achievement of the object of the present invention. Other acid components include, for example, unsaturated aliphatic dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid; halogen-containing dicarboxylic acids such as tetrabromophthalic acid; phthalic acid derivatives represented by the formula:
wherein R
1
is an alkyl group having 1 to 4 carbon atoms; an aryl group having 6 to 12 carbon atoms; an aralkyl group having 7 to 13 carbon atoms; a halogen atom; an alkoxy group having 1 to 4 carbon atoms; hydroxyl group; or an aryloxy group having 6 to 12 carbon atoms which may have a substituent;
terephthalic acid; isophthalic acid; naphthalene derivatives represented by the formula:
wherein R
2
is hydrogen atom, an alkyl group having 1 to 4 carbon atoms; an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 13 carbon atoms; a halogen atom; an alkoxy group having 1 to 4 carbon atoms; hydroxyl group; or an aryloxy group having 6 to 12 carbon atoms which may have a substitutent. The present invention is not limited to the exemplified ones.
The content of other acid components is preferably not more than 10% by weight, more preferably not more than 5% by weight, and it is most desirable that the acid component be composed of the phthalic acid component and the aliphatic polybasic acid.
With respect to the acid component, it is desired that the molar ratio of the phthalic acid component/aliphatic polybasic acid is adjusted to not less than 0.05, preferably not less than 0.08, in order to avoid that the solidification point of the acid component does not become too high, and that the acid component is liquid under employed molding conditions (molding temperature: about 40° C.). Also, it is desired that the molar ratio is adjusted to not more than 0.2, preferably not more than 0.15, from the viewpoint of easy injection and pouring during molding. When the polyester-polyol is included in the polyol component used in the preparation of a polyurethane foam, it is desired that the molar ratio of the phthalic acid component/aliphatic polybasic acid is not more than 0.15, preferably not more than 0.12.
The polyhydric alcohol includes, for example, ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and the like. Those polyhydric alcohols can be used alone or in admixture thereof. Among them, ethylene glycol and 1,4-butanediol can be suitably used in order to obtain a polyurethane foam having excellent physical properties such as tensile strength. Either ethylene glycol or 1,4-butanediol can be used singularly or in admixture thereof.
The polyester-polyol of the pr
Miyamoto Ken'ichi
Mori Masahiro
Okubo Makoto
Sawai Minoru
Takemura Kazunari
Birch & Stewart Kolasch & Birch, LLP
Cooney Jr. John M.
Kao Corporation
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