Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2000-08-16
2003-03-11
Nutter, Nathan M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S240000
Reexamination Certificate
active
06531545
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an olefin-based thermoplastic elastomer composition for powder molding, powder for powder molding, and a molded article. More particularly, the present invention relates to an olefin-based thermoplastic elastomer composition for powder molding, which makes the best use of the merit of an olefin-based material such as no generation of poisonous gas at incineration, and is hardly whitened on bending and excellent in flexibility; powder for powder molding prepared from said composition; and a molded article obtained by powder molding said powder.
BACKGROUND ARTS
Hitherto, molded articles having complicated patterns such as leather grains, stitches and the like on its surface have been used as the molded articles of interior parts of automobiles, and the like. As such skin material, vinyl chloride-based resin molded articles are widely known. However, the vinyl chloride-based resin molded articles had a problem of requiring a special incineration facility because hydrogen chloride gas and the like are generated at incineration disposal after use.
The molded article of a composition composed of a polyolefin-based resin and an ethylene-&agr;-olefin-based copolymer is proposed as that solving the problem (Japanese Patent Publication (Kokai) Hei Nos. 5-1183 and 5-5050). However, since the molded article has a property of being easily whitened on bending in comparison with the vinyl chloride-based resin molded article, and therefore, when said molded article is removed from a mold after production or when said molded article is preliminarily formed in a desired shape or the like after production, the portion bent is whitened and appearance inferiority tends to occur. Additionally, there has been a problem of being inferior in the touch because of being poor in flexibility.
Under these circumstances, the subject to be solved by the present invention is to provide an olefin-based thermoplastic elastomer composition for powder molding. which makes the best use of the merit of an olefin-based material such as no generation of poisonous gas at incineration and is hardly whitened on bending and excellent in flexibility; powder for powder molding prepared from said composition; and a molded article obtained by powder molding said powder.
DISCLOSURE OF THE INVENTION
Namely, the first invention among the present invention relates to an olefin-based thermoplastic elastomer composition for powder molding which contains 5 to 93% by weight of (a) and 7 to 95% by weight of (b) {(a)+(b)=100% by weight} described below, and is prepared from an olefin-based thermoplastic elastomer composition having a complex dynamic viscosity &eegr;*(1) at 250° C. of 1.5×10
5
poise or less as measured at an vibration frequency of 1 radian/sec. and a Newtonian viscosity index n of 0.67 or less as calculated by the equation [I] described below:
(a): a polyolefin-based resin; and
(b): at least one of (b1) and (b2) described below:
(b1): a propylene-1-butene-based copolymer rubber having a Shore A hardness of 70 or less as measured in accordance with ASTM D2240 and an intrinsic viscosity [&eegr;] of 0.3 dl/g or more as measured at a temperature of 70° C. in xylene, and
(b2): a propylene-&agr;-olefin-ethylene-based copolymer rubber having a Shore A hardness of 70 or less as measured in accordance with ASTM D2240 and an intrinsic viscosity [&eegr;] of 0.3 dl/g or more as measured at a temperature of 70° C. in xylene and comprising propylene, an &agr;-olefin having 4 to 20 carbon atoms and ethylene.
n
={log &eegr;*(1)−log &eegr;*(100)}/2 Equation [I]
(in the above-mentioned equation, &eegr;*(1) represents a complex dynamic viscosity at 250° C. measured at a vibration frequency of 1 radian/sec., and &eegr;*(100) represents a complex dynamic viscosity at 250° C. measured at a vibration frequency of 100 radian/sec.)
Further, the second invention among the present invention relates to powder for powder molding prepared from the olefin-based thermoplastic elastomer composition of the above-mentioned first invention.
Further, the third invention among the present invention relates to a molded article obtained by powder molding the powder for powder molding of the above-mentioned second invention.
BEST MODE FOR PRACTICING THE INVENTION
The polyolefin-based resin (a) used in the present invention includes a crystalline polymer or copolymer obtained by polymerizing or copolymerizing one or more of olefins (for example, a propylene homopolymer, a copolymer of propylene with ethylene and/or an &agr;-olefin other than propylene, an ethylene homopolymer, a copolymer of ethylene with an &agr;-olefin other than ethylene, and the like), a copolymer obtained by copolymerizing one or more of olefins at 2 steps or more (for example, a propylene-ethylene block copolymer which is obtained by carrying out the homopolymerization of propylene in the first step and carrying out the copolymerization of propylene with ethylene in the second step, a propylene-olefin copolymer which is obtained by carrying out the copolymerization of propylene with an olefin in the first step, in the second step and in successive steps, respectively and has different copolymerization compositions at respective steps, and the like). Preferable (a) is a propylene-based polymer, namely, a propylene homopolymer or a propylene-based copolymer mainly containing propylene.
(b) of the present invention is (b1): a propylene-1-butene-based copolymer rubber having a Shore A hardness of 70 or less as measured in accordance with ASTM D2240 and an intrinsic viscosity [&eegr;] of 0.3 dl/g or more as measured at a temperature of 70° C. in xylene, and/or (b2): a propylene-&agr;-olefin-ethylene-based copolymer rubber having a Shore A hardness of 70 or less as measured in accordance with ASTM D2240 and an intrinsic viscosity [&eegr;] of 0.3 dl/g or more as measured at a temperature of 70 in xylene and comprising propylene, an &agr;-olefin having 4 to 20 carbon atoms and ethylene.
The Shore A hardness measured in accordance with ASTM D2240 is 70 or less and preferably 60 or less in (b1) and (b2). When the hardness is too high, the thermoplastic elastomer obtained is inferior in flexibility.
The intrinsic viscosity [&eegr;] measured at 70° C. in xylene is 0.3 dl/g or more and preferably 0.5 dl/g or more in (b1) and (b2). When the intrinsic viscosity is too low, the tensile elongation property of the thermoplastic elastomer obtained is poor.
The measurement of the intrinsic viscosity [&eegr;] is carried out at 70° C. in xylene using a Ubbelohde viscometer. A sample of 300 mg is dissolved in 100 ml of xylene to prepare a solution having a concentration of 3 mg/ml. Said solution is further diluted to concentrations of 1/2, 1/3 and 1/5, and each of the solutions is measured in a constant-temperature water bath of 70° C. (±0.1° C.). The measurement is repeated three times at the respective concentrations, and an average of the values obtained is used. Herein, the intrinsic viscosity [&eegr;] is the extrapolated value of the reduced viscosity at a concentration of zero when values obtained by setting reduced viscosity (a value determined by ((&eegr;/&eegr;
0
)−1)/C when the viscosity of a solution is &eegr;, the viscosity of a solvent is &eegr;
0
, and the concentration of the solution is C) to an axis of ordinate, and setting the concentration to an axis of abscissa, are plotted, and an approximate straight line is drawn from these points.
In (b1) and (b2), those having neither crystal-melting peak nor crystallization peak at measurement by a differential scanning calorimeter (DSC) are preferable. When the conditions are not satisfied, the thermoplastic elastomer obtained happens to be inferior in flexibility. As the differential scanning calorimeter, for example, DSC220C manufactured by Seiko Electronics Industry, Co, Ltd. is used and both of the measurements at temperature-elevatin
Nakatsuji Yoshihiro
Ohtani Kohsuke
Sugimoto Hiroyuki
Birch & Stewart Kolasch & Birch, LLP
Nutter Nathan M.
Sumitomo Chemical Company Limited
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