Process for producing urethane resin particles for slush molding

摘要

The present invention is urethane resin particles (C) for slush mold which contain a urethane resin (D) and an additive (N), wherein the particles have a shape factor SF1 of 101 to 200, a shape factor SF2 of 120 to 240, and a central particle diameter of 20 to 500 μm. It is preferred that the urethane resin (D) has a concentration of urea groups of 0.5 to 10% by weight, a total of the concentration of urethane groups and that of the urea groups of 4 to 20% by weight, a melting point of 160 to 260° C. and a glass transition temperature of −65 to 0° C.

主权项

1. A process for producing urethane resin particles (C) for slush molding comprising a urethane resin (D) and an additive (N), the urethane resin particles (C) having a shape factor SF1 of 101 to 200, a shape factor SF2 of 120 to 240, and a central particle diameter of 20 to 500 μm,
wherein the process comprises the following step 1 and step 2-1 or 2-2 for yielding urethane resin particles (P) having particle surfaces having irregularities, in any step for yielding the urethane resin particles (P), or after the particles (P) are yielded, an additive (N) is incorporated into the (P), thereby yielding the urethane resin particles (C): Step 1: a step of producing urethane resin fine particles (G) containing a urethane resin (D), and having a central particle diameter of 1 to 100 μm, and Step 2-1: a step of heating the urethane resin fine particles (G) to a temperature of [the thermally softening temperature of the (D)−10] to [the thermally softening temperature of the (D)+10]° C. while the particles are stirred at a peripheral speed of 0.5 to 50 m/s, whereby the particles are granulated; and then cooling the particles after it is verified that the central particle diameter of the resultant particles reaches a predetermined particle diameter, whereby the resultant particles are granulated into the urethane resin particles (P), or Step 2-2: a step of heating the (G) to a temperature of 70 to [the thermally softening temperature of the (D)+10]° C. in the presence of an organic solvent (T), the difference between the solubility parameter (SP value) of the (T) and that of the urethane resin (D) being 3 or less, and the amount of the (T) being from 5 to 30% by weight based on the weight of the (G), while the particles (G) are stirred at a peripheral speed of 0.5 to 50 m/s, whereby the particles (G) are granulated; and then cooling the resultant particles after it is verified that the central particle diameter of the resultant particles reaches a predetermined particle diameter, whereby the resultant particles are granulated into the urethane resin particles (P).