Thermoplastic polymer powder

Abstract

A thermoplastic polymer powder which (i) consists mainly of an acrylic block copolymer comprising one or more acrylic ester polymer blocks (A) and bonded thereto at least one polymer block selected among methacrylic ester polymer blocks (B) and acrylic ester polymer blocks (C) differing in structure from the blocks (A); (ii) has a complex dynamic viscosity η*(5) of 5.0×103 Pa.s or lower as measured under the conditions of a temperature of 250° C. and an oscillation frequency of 5 rad / sec; (iii) has a Newtonian viscosity index n represented by the equation n=log η*(5)-log η*(50) [wherein η*(5) and η*(50) indicate the complex dynamic viscosities (unit, Pa.s) as measured under the conditions of a temperature of 250° C. and oscillation frequencies of 5 and 50 rad / sec, respectively] of 0.50 or smaller; and (iv) has an average particle diameter of 1 mm or smaller. The thermoplastic polymer powder is suitable for use in molding techniques employing a powder, such as slush molding and in powder coating. A molding, skin material, and the like which are excellent in weatherability, flexibility, mechanical strength, low-temperature properties, adhesion to polar resins, rubber elasticity, safety, etc. can be smoothly produced from the powder.

Description

TECHNICAL FIELD [0001] The present invention relates to a thermoplastic polymer powder, a molded product produced by use of the same, and a process for producing the molded product. More specifically, the present invention relates to a thermoplastic polymer powder which can be used suitably for molding techniques and coating techniques employing a powder, such as slush molding, rotational molding, powder flame spraying, extrusion molding, calendaring, compression molding and powder coating, a molded product produced by use of the same, and a process for producing the molded product. When the thermoplastic polymer powder of the present invention is used to perform any one of the above-mentioned molding and coating techniques, it is possible to produce smoothly a molded product, a skin material, a painted film, a composite product having the skin material or painted film, and so on which cause a lower degree of environmental pollution based on halogen or the like, have good safety, an...

AI Technical Summary

Benefits of technology

[0052] In the case that the thermoplastic polymer powder of the invention is made of an acrylic block copolymer (I) composition which comprises the acrylic block copolymer (I) and a different polymer, the content by percentage of the different polymer can be varied by the kind of the different polymer and so on and generally the content is preferably 40% by mass or less of the acrylic block copolymer (I) composition since the advantageous effects which the thermoplastic polymer powder of the invention has are not taken away from. The content is more preferably 20% by mass or less.

[0053] Examples of the different polymer, which the thermoplastic polymer powder of the invention may comprise together with the acrylic block copolymer (I), include olefin resins such as polyethylene, polypropylene, polybutene-1, poly-4-methylpentene-1, and polynorbornene; ethylene-based ionomers; styrene-based resins such as polystyrene, styrene / maleic anhydride copolymer, high impact polystyrene, AS resin, ABS resin, AES resin, AAS resin, ACS resin, and MBS resin; acrylic resins such as polymethyl methacrylate; methyl methacrylate / styrene copolymer; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polyamides such as nylon 6, nylon 66, and polyamide elastomer; polycarbonate, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene / vinyl alcohol copolymer, polyacetal, polyvinylidene fluoride, polyurethane, modified polyphenyleneether, polyphenylenesulfide, silicone rubber modified resin; acrylic rubbers; silicone rubbers; styrene-based thermoplastic rubbers such as SEPS, SEBS and SIS; and rubbers such as IR, EPR and EPDM. The powder may comprise one or more out of these polymers. Of these polymers, acrylic resins are preferably used since they are excellent in compatibility with the acrylic block copolymer (I), which is a constituent of the thermoplastic polymer powder.

[0054] Examples of the additive, which may be contained in the thermoplastic polymer powder of the invention if necessary, include a lubricant, a fluidity improver, a plasticizer (softener), a thermal stabilizer, a weatherability improver, an antioxidant, a light stabilizer, an antistatic agent, a flame retardant, an adhesive agent, a tackifier, a foaming agent, a pigment, a dye, a filler, and a reinforcing agent. More specific examples thereof include mineral oil softeners, such as paraffin oil and naphthene oil, for improving the fluidity when the powder is molded; inorganic fillers, such as calcium carbonate, talc, carbon black, titanium oxide, silica, clay, barium sulfate, and magnesium carbonate, for attaining an improvement in heat resistance, weatherability or the like, an increase in weight, and other objects; and inorganic or organic fibers, such as glass fiber and carbon fiber, for reinforcement. In order to make the heat resistance and the weatherability better, it is practically preferred that the thermoplastic polymer powder of the invention comprises a thermal stabilizer, an antioxidant or the like among these additives.

[0055] Even if the acrylic block copolymer (I) alone does not satisfy the (ii) or (iii), the incorporation of a fluidity improver or plasticizer may make it possible to yield a powder exhibiting good fluidity. In particular, the incorporation of a fluidity improver or plasticizer having an SP value close to the SP value of the monomers which are polymer block constituent units which constitute the acrylic block copolymer (I) makes it possible to yield, in many cases, a powder which satisfies the requirements (ii) and (iii) and is excellent in melt fluidity while preventing bleed-out and fogging. Examples of the fluidity improver or plasticizer that is preferably used at this time include phosphoric acid derivatives such as tricresyl phosphate (21.4); citric acid derivatives such as acetyl tri(n-butyl) citrate (20.1); sebacic acid derivatives such as di(2-ethylhexyl) sebacate (18.1); adipic acid derivatives such as diisononyl adipate (18.2); phthalic acid derivatives such as diisononyl phthalate (19.2); and polyester oligomers and poly(meth)acrylic ester oligomers [the values inside the parentheses are SP values]. The use of acetyl tri(n-butyl) citrate out of these is more preferred from the viewpoint of bleed-out resistance and safety. When the fluidity improver or plasticizer is incorporated, the incorporated amount thereof is preferably 300 parts or less by mass, more preferably 150 parts or less by mass for 100 parts by mass of the acrylic block copolymer (I).

[0056] In the case that the thermoplastic polymer powder is made only of the acrylic block copolymer (I) without containing any different polymer or additive, the process for producing the thermoplastic polymer powder of the invention is, for example, a process of making the acrylic block copolymer (I) obtained by polymerization directly into a powder in an appropriate manner, and optionally classifying the powder by use of a sieve or the like.

[0057] In the case that the thermoplastic polymer powder of the present invention is made of an acrylic block copolymer (I) composition comprising the acrylic block copolymer (I) together with a different polymer and / or an additive, the mixing may be the respective components constituting the composition collectively or separately, and the kneading may be the resultant mixture by use of a conventional kneading machine such as a single screw extruder, a twin screw extruder, a Banbury mixer, a Brabender, an open roll or kneader, so as to prepare, for example, a pellet-form acrylic block copolymer (I), next making the resultant into a powder in an appropriate manner, and optionally classifying the powder with a sieve or the like.

Problems solved by technology

However, polyvinyl chloride resin generates harmful substances such as dioxin when the resin is incinerated, and further it is suspected that a plasticizer used therein acts as environmental disrupter, carcinogens, or the like.

Thus, the resin has problems about environmental pollution and safety.

There are also caused problems, such as bleed-out and fogging resulting from the plasticizer.

However, the thermoplastic elastomer powder for slush molding described in the JP-A-5-5050 is a nonpolar resin; therefore, the powder is low in adhesion to polar resins such as polyurethane resin and ABS resin, and thus a composite body or the like which is composed of the elastomer and a polar resin is not easily produced.

A molded product obtained from this thermoplastic elastomer powder is not sufficiently satisfactory in flexibility.

However, this material for slush molding has a problem that the plasticizer, which is used to keep low-temperature properties, melt fluidity, flexibility and others, causes bleed-out or fogging in the same manner as the flexible polyvinyl chloride resin powder, and other problems.

This material for slush molding is also low in weatherability since the base thereof is the polyurethane elastomer.