Composite resin particles, process for producing same, expandable beads, expanded beads, foamed molded object, and automotive interior trim

Patent metadata

Field	Value
Publication number	US-10066072-B2
Application number	US-201515512222-A
Country	US
Kind code	B2
Filing date	Aug 31, 2015
Priority date	Sep 26, 2014
Publication date	Sep 4, 2018
Grant date	Sep 4, 2018

Abstract

Composite resin particles comprising 50 to 800 parts by mass of a polystyrene-based resin with respect to 100 parts by mass of a polyolefin-based resin, wherein: when transmission electron microscope (TEM) images obtained by photographing cross-sections of the composite resin particles using a TEM at a magnification of 1,000 are subjected to a binarization processing and areas in the obtained binarized images which correspond to a cross-sectional area of 437.584 μm 2 of the composite resin particles are subjected to image analysis, the polystyrene-based resin satisfies the following requirements: (1) the number of dispersed particles is 180 or more; (2) the maximum of the areas of dispersed particles is 200 μm 2 or less; and (3) the coefficient of variation in dispersion is 100% or more, and the composite resin particles exhibit an inner morphology that includes a mixture of sea-island structure regions and co-continuous structure regions.

First claim

The invention claimed is:

1. Composite resin particles comprising 50 to 800 parts by mass of a polystyrene-based resin with respect to 100 parts by mass of a polyolefin-based resin, wherein:
when transmission electron microscope (TEM) images obtained by photographing cross-sections of the composite resin particles using a TEM at a magnification of 1,000 are subjected to a binarization processing and areas in the obtained binarized images which correspond to a cross-sectional area of 437.584 μm 2 of the composite resin particles are subjected to image analysis, the polystyrene-based resin satisfies the following requirements:
(1) the number of dispersed polystyrene-based resin particles is 180 or more;
(2) the maximum of the areas of dispersed polystyrene-based resin particles is 200 μm 2 or less; and
(3) the coefficient of variation in dispersion of the polystyrene-based resin particles is 100% or more, and
the composite resin particles exhibit an inner morphology that includes a mixture of sea-island structure and co-continuous structure regions in which particles of the polystyrene-based resin are dispersed in the polyolefin-based resin.

2. Expandable particles obtained by immersing a blowing agent in the composite resin particles according to claim 1 .

3. Expanded particles obtained by expansion of the expandable particles according to claim 2 .

4. An expanded molded article obtained by expansion molding in a cavity the expanded particles according to claim 3 .

5. An automotive interior trim formed by the expanded molded article according to claim 4 .

6. A method for producing the composite resin particles according to claim 1 , comprising the steps of:
(A) dispersing, in an aqueous suspension containing a dispersant, particles of a polyolefin-based resin having at least two melting peaks in a differential scanning calorimetry (DSC) curve obtained by DSC; a styrene-based monomer; and 0.1 to 0.9 parts by mass of a polymerization initiator per 100 parts by mass of the styrene-based monomer to form a dispersion;
(B) heating the resulting dispersion at a temperature at which the styrene-based monomer does not substantially polymerize and immersing the styrene-based monomer in the particles of the polyolefin-based resin; and
(C) carrying out a first polymerization of the styrene-based monomer at a temperature in the range of T2 to (T2+35)° C., wherein T2° C. is the highest melting peak temperature among peaks, or the at least two melting peaks of the polyolefin-based resin, and
(D) following the first polymerization, adding additional styrene-based monomer and 0.1 to 0.9 parts by mass of an additional polymerization initiator per 100 parts by mass of the additional styrene-based monomer and carrying out immersion of the additional styrene-based monomer in the particles of the polyolefin-based resin and a second polymerization at a temperature in the range of (T1−10) to (T2+5)° C., wherein T1 is the lowest melting peak temperature among the at least two melting peaks of the polyolefin-based resin.

7. The method for producing the composite resin particles according to claim 6 , wherein a temperature difference between the melting peak temperature T2 and the melting peak temperature T1 is 10 to 50° C.

8. The method for producing the composite resin particles according to claim 6 , wherein the melting peak temperature T1 is 90° C. or higher.

9. The method for producing the composite resin particles according to claim 6 , wherein the polyolefin-based resin has at least two crystallization peaks in the DSC curve among which a crystallization peak at the highest temperature has a maximum peak area.

10. The method for producing the composite resin particles according to claim 6 , wherein the polyolefin-based resin contains a component selected from a polyethylene resin and an ethylene-acryl copolymer resin.

Assignees

• Sekisui Plastics

Inventors

• Owaki Hiroki

Classifications

• C08L25/06

  Polystyrene · CPC title

• C08J2323/02

  not modified by chemical after treatment · CPC title

• C08J2325/06

  Polystyrene · CPC title

• C08J2203/182

  of physical blowing agents, e.g. acetone and butane · CPC title

• C08L23/06

  Polyethylene · CPC title