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...
Reexamination Certificate
1999-07-02
2001-01-23
Cain, Edward J. (Department: 1714)
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...
C524S231000, C524S232000, C524S813000, C524S872000, C524S873000, C528S045000
Reexamination Certificate
active
06177508
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a composition for slush molding, more particularly to a slush molding composition capable of being molded within a wide temperature range having excellent thermal meltability.
BACKGROUND OF THE INVENTION
Slush molding permits molding without difficulty of complicated forms as undercut, deep drawing or the like, with the skin thickness kept uniform and at a high yield. On the strength of those advantages, the slush molding process has been widely practiced for molding various articles as interior component parts of motor vehicles. In this molding, soft polyvinyl chloride (PVC) powder has mainly been used as exemplified by unexamined Japanese Patent Publication No. H05-279485.
One problem is, however, that because of a high content of a low molecular weight plasticizer, the softened PVC loses its soft feel at temperatures below the solidifying point of the plasticizer. Other problems are encountered in service for a long time: (1) formation of oil film of evaporated plasticizer on the automobile front windshield, (2) loss in matting effect and soft touch as a result of migration of the plasticizer to the surface of the molded article, and (3) yellowing from the degradation of PVC with passage of time.
Efforts have been made to solve those problems, and there are known some improved versions. For example, flexible thermoplastic polyurethane resin are proposed as main materials to provide soft touch without a plasticizer as disclosed in Unexamined Japanese Patent Publication No. H08-120041.
However, there has been such a problem that, when a thermoplastic polyurethane resin is used as a main resin, blocking between particles is liable to occur because the resin has flexibility and, when an inorganic filler is used for the purpose of preventing the blocking, the hot-melt viscosity becomes higher and the resin can be molded only within a very narrow temperature range.
SUMMARY OF THE INVENTION
An object of the present invention is to solve the problems described above and to provide a composition for slush molding, which can be molded within a wide temperature range. Another object of the present invention is to provide a composition for slush molding, which exhibits large elongation at low temperature. Still another object of the present invention is to provide a composition for slush molding, which is suited for a molded article such as automotive instrument panel.
To solve the problems described above, the present invention provides a polyurethane resin composition for slush molding, comprising a thermoplastic polyurethane elastomer (A) having a number average molecular weight of 10,000 to 50,000, a glass transition point of not higher than −35° C. and a heat softening initiation temperature of 100 to 160° C., a plasticizer (B), a blocked polyisocyanate (C), a pigment (D) and a blocking inhibitor (E), characterized in that (E) is a resin powder which is not heat-softened at a temperature of not higher than 160° C. and has an average particle diameter of not higher than 10 &mgr;m.
Based on the thermoplastic polyurethane elastomer (A), the composition of the present invention can reduce the content of the plasticizer unlike the prior art, thus cutting down the negative effects brought about by use of the plasticizer in a large quantity.
By adding the predetermined blocking inhibitor (E), the blocking is inhibited even when using the thermoplastic polyurethane elastomer (A), thereby making it possible to mold within a wide temperature range.
The slush molding composition of the present invention gives molded products having the following advantages:
1. It is possible to mold within a wide mold temperature and a method of controlling the temperature of the mold is not limited.
2. High elongation at low temperature as compared with the conventional PVC-type material, and therefore suitable as crack-free surface skin on an instrument panel for use in cold districts. There is no fear of breaking apart when an air bag installed inside the instrument panel for the front seat next to the driver is activated and inflated in the cold season. Thus, the composition of the present invention is useful in protecting the automobile passenger.
3. Excellent in thermal aging resistance, light aging resistance and other properties as compared with the conventional PVC-type material, and therefore suitable for long-term outdoor use.
On the strength of those advantages, the slush molding composition of the present invention is very useful as automobile interior material, for example, for instrument panel and also applicable to other molded articles such as sofa surface skin and others.
DETAILED DESCRIPTION OF THE INVENTION
The thermoplastic urethane elastomer (A) according to the present invention is formed by reacting an isocyanate group-terminated urethane prepolymer (a) derived from an excess non-aromatic diisocyanate (a1), a high-molecular weight diol (a2) having a number average molecular weight of 500 to 10,000 and, optionally, a low-molecular weight diol (a3) with a non-aromatic diamine (b1) and a mono- or di-alkanolamine (b2) containing 2 to 4 carbon atoms in the hydroxyalkyl group.
The aforesaid non-aromatic diisocyanates (a1) include {circle around (1)} aliphatic diisocyanates with 2 to 18 carbon atoms (except the carbons in the NCO group, similarly hereinafter), e.g., ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (hereinafter referred to as HDI), dodecamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2,6-diisocyanatomethyl caproate, bis(2-isocyanatoethyl)fumarate, bis(2-isocyanato ethyl)carbonate, 2-isocyanatoethyl-2,6-diisocyanatohexanoate, and the like; {circle around (2)} alicyclic diisocyanates with 4 to 15 carbon atoms, e.g., isophorone diisocyanate (hereinafter referred to as IPDI), dicyclohexylmethane-4,4′-diisocyanate (hereinafter referred to as hydrogenated MDI), cyclohexylene diisocyanate, methyl cyclohexylene diisocyanate (hereinafter referred to as hydrogenated TDI), bis(2-isocyanato ethyl)-4-cyclohexene, and the like; {circle around (3)} araliphatic isocyanate with 8 to 15 carbon atoms, e.g., m- and/or p-xylylene diisocyanate (hereinafter referred to as XDI), &agr;,&agr;,&agr;′,&agr;′-tetramethyl xylylene diisocyanate (hereinafter referred to as TMXDI), and the like; {circle around (4)} modified diisocyanates from these, e.g., diisocyanates having a carbodiimide group, an urethodione group, an urethoimine group or an urea group; and {circle around (5)} mixtures of two or more of those compounds.
Among these compounds, preferred are alicyclic diisocyanates, particularly IPDI and hydrogenated MDI.
Suitable high molecular weight diols (a2) include polyester diols, polyether diols, polyether ester diols, and mixtures of two or more of those compounds.
As the aforesaid polyester diol can be cited: {circle around (1)} condensation polymerizates between a low molecular weight diol and a dicarboxylic acid or its ester-forming derivative (acid anhydride, lower alkyl ester with one to 4 carbon atoms, acid halide, and the like); {circle around (2)} ring opening polymerizates of a lactone monomer with a low molecular weight diol as initiator; and mixtures of two or more of those compounds.
The aforesaid low molecular weight diol usually has a molecular weight of 62-about 500. Examples of such diol include: aliphatic diols with 4 to 12 or more carbon atoms [linear ones such as ethylene glycol, diethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, and the like, branched ones such as propylene glycol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2,2-diethyl-1,3-propanediol, 1,2-butanediol, 1,3-butanediol, and 2,3-butanediol]; diols that contain cyclic group such as 1,4-bis(hydroxymethyl)cyclohexane, m-xylylene glycol, and p-xylylene glycol, ethylene oxide adduct of bisphenol A having a molecular weight less than 500, and the like; and mixtures of two or more of those compounds. Of these com
Kobayashi Kazuo
Nishimura Hideo
Ohmori Hideki
Takai Eriko
Takai Yoshitsugu
Cain Edward J.
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Sanyo Chemical Industries Ltd.
Takai Eriko
Wyrozebski Katarzyna
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