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 5.0×10 3 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.

1 . A thermoplastic polymer powder comprising an acrylic block copolymer (I) wherein said acrylic block copolymer comprises at least one polymer block (A) comprising structural units originating from an acrylic ester; and at least one polymer block bonded thereto and selected from polymer blocks (B) comprising structural units originating from a methacrylic ester and polymer blocks (C) comprising structural units originating from an acrylic ester different from that of the polymer block (A) wherein said thermoplastic polymer powder; 
 has a complex dynamic viscosity η*(5) of 5.0×10 3  Pa.s or less, the viscosity η*(5) being measured under conditions of a temperature of 250° C. and an angular frequency of 5 rad/sec;    has a Newtonian viscosity index n of 0.50 or less, the Newtonian viscosity index n being represented by the following equation (1):        n =log η*(5)-log η*(50)   (1)    wherein n represents the Newtonian viscosity index, η*(5) represents the complex dynamic viscosity (unit: Pa.s) measured under conditions of a temperature 250° C. and an angular frequency of 5 rad/sec, and η*(50) represents the complex dynamic viscosity (unit: Pa.s) measured under conditions of a temperature of 250° C. and an angular frequency of 50 rad/sec; and    has an average particle diameter of 1 mm or less.    
   
   
       2 . The thermoplastic polymer powder according to  claim 1 , wherein the melt viscosity measured with a rotary viscometer at 250° C. and a shear rate of 0.2 sec −1  is 3000 Pa.s or less.  
   
   
       3 . The thermoplastic polymer powder according to  claim 1 , which is obtained by an underwater cutting process or a shock pulverizing process.  
   
   
       4 . The thermoplastic polymer powder according to  claim 1 , wherein the weight average molecular weight of the acrylic block copolymer (I) is from 5,000 to 200,000.  
   
   
       5 . The thermoplastic polymer powder according to  claim 1 , wherein the weight average molecular weight of the polymer block (A) constituting the acrylic block copolymer (I) is from 1,000 to 150,000, and the weight average molecular weights of the polymer block (B) and the polymer block (C) are from 2,000 to 50,000.  
   
   
       6 . The thermoplastic polymer powder according to  claim 1 , wherein the acrylic block copolymer (I) is a triblock copolymer made of the polymer block (B)-the polymer block (A)-the polymer block (B).  
   
   
       7 . The thermoplastic polymer powder according to  claim 1 , wherein the difference between the solubility parameter σ(A) (unit: MPa 1/2 ) of the starting monomer(s) constituting the polymer block(s) (A) and the solubility parameter σ(B) or σ(C) (unit: MPa 1/2 ) of the starting monomer(s) constituting the polymer block (B) or the polymer block (C) is 2.5 or less.  
   
   
       8 . The thermoplastic polymer powder according to  claim 1 , which is for slush molding or rotational molding.  
   
   
       9 . A process comprising producing a molded product by performing slush molding or rotational molding with the thermoplastic polymer powder according to  claim 1 .  
   
   
       10 . A molded product produced with the thermoplastic polymer powder according to  claim 1 .  
   
   
       11 . The molded product according to  claim 10 , which is a toy member having a JIS-A hardness of 40 to 95.  
   
   
       12 . The molded product according to  claim 10 , which is a lighting cover having a JIS-A hardness of 95 or more.