Expandable thermoplastic resin molded product, method of producing expandable thermoplastic resin molded product and thermoplastic resin foam

A method for manufacture of an expandable thermoplastic resin product comprising the steps of:

• superimposing an elastic thermoplastic material or the like on a surface of an expandable thermoplastic resin sheet to provide a laminate sheet;
• providing a pair of couterrotating shaping rolls spaced from each other by a clearance smaller in dimension than a thickness of said laminate sheet, a plurality of recesses being provided in a distributed manner on a periphery of at least one of said rolls;
• introducing the laminate sheet while its surface is in a molten state into said clearance between said pair of shaping rolls and then withdrawing the laminate sheet from the pair of rolls so that the laminate sheet is shaped to define, on at least one surface thereof, projections corresponding to the recesses defined on the periphery of the shaping roll;
• and
• cooling an expandable thermoplastic resin product having said projections.

A thermoplastic resin foam including:

• a foam sheet composed of a thermoplastic resin and having a relative low expansion ratio;
• a plurality of basic raised portions integrally provided on at least one surface of said foam sheet in a distributed manner and comprising a thermoplastic resin foam having a relatively high expansion ratio;
• a low foamed layer having a relatively low expansion ratio and disposed to cover areas of the basic raised portions that exclude those in contact with the foam sheet so that the low foamed layer and the basic raised portions together constitute raised portions;
• and
• a layer of elastic thermoplastic material disposed to cover the at least one surface of the foam sheet and the raised portions and also fill spaces between the raised portions.

A thermoplastic resin foam including:

• a foam sheet-having a relatively low expansion ratio and composed of a thermoplastic resin;
• a plurality of basic raised portions integrally provided on at least one surface of said foam sheet in a distributed manner and comprising a thermoplastic resin foam having a relatively high expansion ratio;
• a low foamed layer having a relatively low expansion ratio and disposed to cover areas of the basic raised portions that exclude those in contact with the foam sheet so that the low foamed layer and the basic raised portions together constitute raised portions;
• and
• a second foam layer disposed to cover the at least one surface of the foam sheet and said plurality of raised portions and also fill spaces between the raised portions.