PURPOSE: To obtain a crystalline nucleus agent for polyesters useful for molded products excellent in mechanical characteristics, comprising a compound of abietic acid having a specific structure and capable of promoting crystallization speeds of the polyesters and making crystals super fine.
CONSTITUTION: This crystalline nucleus agent comprises at least one abietic acid-based compound selected from a group consisting of a compound of formula I (R1 to R3 are each H, an alkyl, a cycloalkyl or an aryl), compound of formula II and a metal salt (preferably, at least one salt selected from a sodium salt, a potassium salt and a magnesium salt) thereof. In the compound of formula I and that of formula II, preferably, R1 is isopropyl and R2 and R3 are each methyl. For example, dehydroabietic acid as a compound formula I is obtained by disproportionating or dehydrogenating a natural rosin such as gum rosin, tall oil rosin, etc., and purifying the result% product. The crystalline nucleus agent is preferably used as the crystallizing agent for polyethylene terephthalate. It is preferable to use 0.001-5 pts.wt., more preferably 0.05-2 pts. wt., of the crystalline nucleus agent for 100 pts.wt. of the polyester.
HORI HIROYUKI
KASAI TETSUSHI
UEDA KIMIO
MAEDA MASAO
MATSUMOTO HIROSHI
ARAKAWA CHEM IND