Transparentization agent composition containing sorbitol compound and method for producing polypropylene resin composition using this sorbitol compound

Abstract

A transparentization agent composition is a mixture containing 100 parts by mass of a dibenzylidene sorbitol compound represented by a general formula (I) having a particle diameter such that d97 is from 30 μm to 200 μm and 5 to 200 parts by mass of tetrakis[3(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxymethyl]methane, wherein the total for the two components is 50% by mass or more of the mixture. Also disclosed is a method for producing a polypropylene resin composition, including obtaining a polypropylene resin composition in which a dibenzylidene sorbitol compound represented by a general formula (I) having a particle diameter such that d97 is from 30 μm to 200 μm is incorporated in a polypropylene resin, by kneading a mixture containing 100 parts by mass of the polypropylene resin and 0.05 to 2 parts by mass of the dibenzylidene sorbitol compound by using a biaxial extruder at an extrusion temperature of from 220 to 250° C.

Description

TECHNICAL FIELD [0001]The present invention relates to a transparentization agent composition that can form a polypropylene resin composition that is excellent in transparency, by mixing a dibenzylidene sorbitol transparentization agent having a large particle diameter which has been conventionally considered to be not suitable for adding during processing of a polypropylene resin, with a specific phenol antioxidant in advance, prior to mixing with a resin, and adding the mixture to the resin.[0002]Furthermore, the present invention also relates to a method for the production of a polypropylene resin composition that is excellent in transparency, which has enabled incorporation of a dibenzylidene sorbitol transparentization agent having a large particle diameter which has been conventionally considered to be not suitable for adding during processing of a polypropylene resin, by selecting a specific condition for processing.BACKGROUND ART[0003]Polypropylene resins such as propylene h...

AI Technical Summary

Benefits of technology

[0010]The object of the present invention is to provide a dibenzylidene sorbitol-based transparentization agent that can form a polypropylene resin composition that is excellent in transparency, by incorporating a dibenzylidene sorbitol compound in a polypropylene resin without micropowderization.

Problems solved by technology

Among these, dibenzylidene sorbitols are excellent in an effect of improving transparency, but they have defects that they have strong odor, they have a high melting point and thus are difficult to be dispersed homogeneously in resins at a processing temperature, and the like.

Although this dibenzylidene sorbitol is excellent in an effect of improving transparency, it has problems that the flowability is decreased by forming into a micropowder, thereby handling properties such as measuring and charging are decreased, and that expected dispersibility cannot be obtained due to blocking, and the like.

Furthermore, it is actually necessary to prevent secondary aggregation of the micropulverized product by using an inorganic substance, a surface treating agent or the like, and thus the production cost is increased and components that are unnecessary for the resin are mixed.

Since mixing of unnecessary components is associated with unintended change in the physical properties of the resin and leads to decrease in the quality during recycling and limitation to the usage, micropulverization is not necessarily a satisfying solution means.

However, since a transparentization agent having other structure is daringly added to a compound that is specifically excellent in effects among dibenzylidene sorbitols, it is not a sufficient countermeasure due to that the transparentization effect is decreased, and the like.

As is described in Patent Literature 1 as Comparative Examples, even these other additive components are incorporated in a resin together with a dibenzylidene sorbitol and mixed by a Henschel mixer or the like, the dispersibility of the dibenzylidene sorbitol could not be improved.

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