Patent ID: 6334970
Filing Date: 2002-01-01
Classification: B29C,C08L

Abstract:
A method for producing a foamed resin article comprising a melting step of feeding a thermoplastic resin into an extruder and heating it to melt, a kneading step of mixing an inorganic gas with the thermoplastic resin in the extruder to produce a kneaded material, and a foaming step of discharging the kneaded material from a mold having a tubular channel mounted to the end of the extruder to form the foamed article,wherein extrusion molding is carried out within the range where a numeric X, which is defined by the following expression: X=100P+3.5H where a resin feeding pressure of the thermoplastic resin from the extruder to the mold is represented by H (kgf/cm2) and an expansion ratio is represented by P, and the resin feeding pressure H satisfy the following expressions simultaneously: 780&lE;X&lE;4000, and80&lE;H&lE;1000, wherein a numeric Y, which is defined by the following expression: Y=100P+3.5(Hâˆ’10G) where the amount of the inorganic gas supplied to 100 g of the thermoplastic resin is represented by G g, satisfies the following expression: 760&lE;Y&lE;4000, wherein the mold comprises a tubular channel having a tip (lip) with a shape that satisfies the following expressions simultaneously: 0.1&lE;L&lE;1; â€ƒ0.1&lE;tan &thgr;&lE;6;and5&lE;T&lE;500 where a lip gap, a taper angle, and a taper land are represented by L (mm), &thgr;, and T (mm), respectively.