Preparation of foam particles of ethylenic resin and foam moldings prepared therefrom

Claim 2

Foam particles of a linear, uncrosslinked ethylenic resin which can be expansion molded by heating in its uncrosslinked state, said ethylenic resin having a molecular weight distribution of at least 15, as defined by the ratio Mw/Mn, wherein Mw is the weight average molecular weight and Mn is the number average molecular weight, as measured by gel permeation chromatography, said ethylenic resin also having a bimodal wave form in the curve of molecular weight distribution, said weight average molecular weight being at least 2×10 5 and the density of said resin being at least 0.920 g/cm 3 , wherein said linear ethylenic resin is selected from the group consisting of a high density polyethylene, a linear low density polyethylene produced by low and medium pressure methods and a linear crystalline copolymer containing at least 50 mol % of ethylenic units.

Claim 3

The foam particles according to claim 1 wherein the linear ethylenic resin is a high density polyethylene.

Claim 4

The foam particles according to claim 1 wherein at least 60% of the cells in the particles are closed cells.

Claim 5

The foam particles according to claim 1 wherein the cells in the particles have an average size of 0.05 to 1.0 mm.

Claim 6

The foam particles according to claim 1 wherein the density of the foam particles is 15 to 100 Kg/m 3 .

Claim 7

An in-mold foam molding of an uncrosslinked ethylenic resin, comprising as the base resin a linear ethylenic resin having a molecular weight distribution of at least 15 as defined by the ratio Mw/Mn, wherein Mw is the weight average molecular weight and Mn is the number average molecular weight as measured by gel permeation chromatography, said ethylenic resin also having a bimodal wave form in the curve of molecular weight distribution, said weight average molecular weight being at least 2×10 5 and the density of said resin being at least 0.920 g/cm 3 said foam molding having a density (D) (Kg/m 3 ) after molding and a stress (F) (Kg/cm 2 ) required for 25% compression of the molded product, which satisfy the relation presented by the following formula: 1.3 log(D)-1.87≦log(F)≦1.3 log(D)-1.61 (wherein D is 15 to 100 Kg/M 3 ), said linear ethylenic resin is selected from the group consisting of a high density polyethylene, a linear low density polyethylene produced by low and medium pressure methods and a linear crystalline copolymer containing at least 50 mol % of ethylenic units.

Claim 8

An in-mold foam molding of an uncrosslinked ethylenic resin, comprising as the base resin a linear ethylenic resin having a molecular weight distribution of at least 15 as defined by the ratio Mw/Mn, wherein Mw is the weight average molecular weight and Mn is the number average molecular weight as measured by gel permeation chromatography, said ethylenic resin also having a bimodal wave form in the curve of molecular weight distribution, said weight average molecular weight being at least 2×10 5 and the density of said resin being at least 0.920 g/cm 3 said foam molding having a density (D) (Kg/m 3 ) after molding and a stress (F) (Kg/cm 2 ) required for 25% compression of the molded product, which satisfy the relation presented by the following formula: 1.3 log(D)-1.87≦log(F)≦1.3 log(D)-1.61 (wherein D is 15 to 100 Kg/M 3 ), said linear ethylenic resin is selected from the group consisting of a high density polyethylene, a linear low density polyethylene produced by low and medium pressure methods and a linear crystalline copolymer containing at least 50 mol % of ethylenic units.

Claim 9

The in-mold foam molding of an uncrosslinked ethylenic resin according to claim 6 comprising foam particles having a particle size of 2 to 10 mm in diameter.

Claim 10

The in-mold foam molding of an uncrosslinked ethylenic resin according to claim 6 wherein the linear ethylenic resin is a high density polyethylene.

Claim 11

The in-mold foam molding of an uncrosslinked ethylenic resin according to claim 6 wherein at least 60% of the cells in the particles are closed cells, wherein the cells in the particles have an average size of 0.05 to 1.0 mm and wherein the foam particles have a particle size of 2 to 10 mm in diameter.