Polyurethane resin type composition for slush molding

Details Polyurethane resin type composition for slush molding Polyurethane resin type composition for slush molding

1999-09-27

2003-05-13

Seldleck, Jamas J. (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...

C528S079000, C528S080000, C528S083000, C524S366000

Reexamination Certificate

active

06562933

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a composition for slush molding, more particularly to a slush molding composition capable of producing molded articles suitable for automotive trims such as instrument panels.
BACKGROUND OF THE INVENTION
Slush molding process has been widely practiced for molding various articles as interior component parts of motor vehicles. In this molding, there have been proposed modifications of PVC with flexible thermoplastic polyurethane resin as materials to provide soft touch without a low molecular weight plasticizer, as disclosed in Examined Japanese Patent Publication Nos. S53-29705, S59-39464 and S60-30688.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a molded article of improved compatibility of plasticizer and soft feel even at low temperature. It is another object of the present invention to provide a molded article of little or reduced fogging problem (formation of oil film of evaporated plasticizer on the automotive front windshield) and suitable for automotive instrument panels. It is a further object of the present invention to provide a molded article having improved pigment dispersibility without causing uneven color even in light color. It is still another object of the present invention to provide a molded article having improved durability such as resistance to chemicals. It is yet another object of the present invention to provide a slush molding composition and a process, capable of producing a molded article as above.
Briefly, these and other objects of this invention as hereinafter will become more readily apparent have been attained broadly by a slush molding composition, comprising a thermoplastic polyurethane elastomer (A) mainly comprised of a diol component including an aromatic ring-containing diol and a non-aromatic diisocyanate, and a plasticizer (B). The thermoplastic polyurethane elastomer (A) usually has a number average molecular weight (measured by GPC, hereinafter referred to as Mn) of about 10,000 to about 50,000.
DETAILED DESCRIPTION OF THE INVENTION
Suitable thermoplastic urethane elastomers (A) according to the present invention include, for example, those desclosed in U.S. Pat. No. 5,906,704, herein incorporated by reference. Illustrative of (A) are ones obtainable by reacting an NCO-terminated urethane prepolymer (a) with a non-aromatic diamine (b1) and an aliphatic monoamine (b2). Said prepolymer (a) is derived from an excess non-aromatic diisocyanate (a1) and a high-molecular diol (a2) having a number average molecular weight of 500 to 10,000 with, optionally, a low-molecular diol (a3). At least a part of the diol component comprising (a2) and optionally (a3) should be aromatic ring-containing diols so as to attain the durability required as slush molding composition.
Suitable non-aromatic diisocyanates (al) include, for example, {circle around (1)} aliphatic diisocyanates with 2 to 18 carbon atoms (except the carbon atoms in the NCO groups, 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 and mixtures of two or more of those compounds.
As the aforesaid polyester diol can be cited: {circle around (1)} polycondensates between a dihydric alcohol 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 dihydric alcohol as initiator; and mixtures of two or more of those compounds.
Suitable dihydric alcohols include low molecular weight diols and polyether diols. Examples of low molecular weight diols include: aliphatic dihydric alcohols [linear diols 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 diols 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]; alicyclic dihydric alcohols [1,4-bis(hydroxymethyl)cyclohexane diol, 2,2-bis(4-hydroxycyclohexyl)propane and the like]; aromatic ring-containing dihydric alcohols [m-xylylene glycol, p-xylylene glycol, alkylene oxide adduct (molecular weight: less than 500) of bisphenols such as bisphenol A, bisphenol S or bisphenol F. alkylene oxide adduct (molecular weight: less than 500) of dihydroxynaphthalene and bis(2-hydroxyethyl)terephthalate]. Suitable polyether diols include the same ones as described below. Mixtures of two or more of these diols may also be used.
Of these compounds preferable are aromatic ring-containing dihydric alcohols(particularly alkylene oxide adducts of bisphenol A), and combinations thereof with aliphatic dihydric alcohols or alicyclic dihydric alcohols.
Examples of the dicarboxylic acid or its ester-forming derivative in aforesaid {circle around (1)} include: aliphatic dicarboxylic acids with 4 to 15 carbon atoms such as succinic, adipic, sebacic, glutaric, azelaic, maleic and fumaric acids; aromatic dicarboxylic acids with 8 to 12 carbon atoms such as terephthalic and isophthalic acids; their ester-forming derivatives such as acid anhydrides, lower alkyl esters (e.g., dimethyl ester, diethyl ester), acid halides (e.g., acid chloride); and mixtures of two or more of these compounds. It is preferable to use aromatic dicarboxylic acids of these compounds in order to introduce an aromatic-ring into (A).
Examples of the lactone monomer in aforesaid {circle around (2)} include &ggr;-butyrolactone, &egr;-caprolactone, &ggr;-valerolactone and mixtures of two or more of these compounds.
As the aforesaid polyether diol can be cited alkylene oxide adducts of dihydric phenols.
Among the dihydric phenols are bisphenols, e.g., bisphenol A bisphenol F and bisphenol S, and monocyclic phenols e.g., catechol and hydroquinone.
Suitable alkylene oxides include ones containing 2-8 carbon atoms, for example, ethylene oxide (hereafter, referred to as “EO”), propylene oxide (hereafter, referred to as “PO”), 1,2-butylene oxide, 1,3-butylene oxide, 1,4-butylene oxide, 2,3-butylene oxide, styrene oxide, &agr;-olefin oxide with 5 to 10 or more carbon atoms, epichlorohydrin, and combinations of two or more of these compounds, which may be added blockwise and/or randomwise.
Of those polyether diols, preferable are oxyalkylated dihydric phenols, and particularly oxyethylated bisphenols.
Of those high molecular weight diols (a2), preferable are polyester diols, more preferable condensed polyester diols derived from at least one aromatic ring-containing dihydric alcohol and at least one aromatic dicarboxylic acid, particularly preferable

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