Method for reducing volatile organic compounds in composite resin particles, and composite resin particles

1. A method of reducing a volatile organic compound of composite resin particles comprising:

blowing a gas from a bottom part of a container in order to fluidize composite resin particles containing a polyolefin-based resin and a polystyrene-based resin in the container until an amount of volatile organic compounds contained in the whole composite resin particles becomes 50 ppm or less,

wherein the gas has a temperature of (T−40) to (T−10)° C. when a softening temperature of the composite resin particles is defined as T° C.

2. A method of reducing a volatile organic compound of composite resin particles according to claim 1 , wherein the polyolefin-based resin is a polyethylene-based resin, and the gas is blown at a temperature of (T−30)° C. to (T−10)° C.

3. A method of reducing a volatile organic compound of composite resin particles according to claim 1 , wherein the polyolefin-based resin is a polypropylene-based resin, and the gas is blown at a temperature of (T−40)° C. to (T−15)° C.

4. A method of reducing a volatile organic compound of composite resin particles according to claim 1 , wherein the composite resin particles are put into the container with the gas being blown from a bottom part of the container.

5. A method of reducing a volatile organic compound of composite resin particles according to claim 1 , wherein the composite resin particles contain 100 parts by weight of the polyolefin-based resin and 100 to 500 parts by weight of the polystyrene-based resin.

6. A method of reducing a volatile organic compound of composite resin particles according to claim 1 , wherein the composite resin particles are polyolefin-modified styrene -based resin particles that are obtained by impregnating a styrene-based monomer into the polyolefin-based resin particles and performing a polymerization.

7. Composite resin particles having reduced a volatile organic compound and produced by the method of claim 1 .

8. Composite resin particles comprising, for producing an expanded molded article, the composite resin particles containing 100 parts by weight of a polyolefin-based resin and 100 to 500 parts by weight of a polystyrene-based resin,

wherein the composite resin particles:

(1) have a co-continuous structure or a granular dispersion structure in which an average area occupied by the polystyrene-based resin is 35 to 80 μm 2 in a TEM photograph obtained by photographing a portion of 10 μm×10 μm of a cross-section surface at its central part with a magnification of 12800; and

(2) contain a volatile organic compounds of an amount of 50 ppm or less.

9. Composite resin particles according to claim 8 , wherein the composite resin particles have a co-continuous structure in which a band made of a polystyrene-based resin having an average width of 0.2 to 1.5 μm is continuous, or a granular dispersion structure having a granular polystyrene-based resin of 0.01 to 1.5 μm.

10. Expandable composite resin particles formed by impregnating a blowing agent into the composite resin particles of claims 7 .

11. Pre-expanded particles formed by pre-expanding the expandable composite resin particles of claim 10 .

12. An expanded molded article produced by allowing the pre-expanded particles of claim 11 to be subject to an in-mold forming.

13. An automobile interior material derived from the expanded molded article of claim 12 .

14. Expandable composite resin particles formed by impregnating a blowing agent into the composite resin particles of claims 8 .

15. Pre-expanded particles formed by pre-expanding the expandable composite resin particles of claim 14 .

16. An expanded molded article produced by allowing the pre-expanded particles of claim 15 to be subject to an in-mold forming.

17. An automobile interior material derived from the expanded molded article of claim 16 .