Process for producing laminated foam sheet and extruded laminated foam sheet

A process for producing a laminated foam sheet having a polyethylene-based resin foam layer and a polyethylene-based resin antistatic layer laminated on at least one side of the foam layer, comprising the steps of:

• providing a first melt containing a polyethylene-based resin (PE-1) and a physical blowing agent,
• providing a second melt containing a polyethylene-based resin (PE-2), an ionomer resin as a polymeric antistatic agent, and a volatile plasticizer, and
• coextruding the first and second melts to form the laminated foam sheet in which the polyethylene-based resin foam layer and the polyethylene-based resin antistatic layer are formed from the first and second melts, respectively,
• wherein the volatile plasticizer is composed of a blend of a component (A) which is at least one alcohol having a boiling point of 120° C. or less and a component (B) which is at least one selected from the group consisting of saturated hydrocarbons having 3 to 5 carbon atoms and dialkyl ethers in which each alkyl has 1 to 3 carbon atoms,
• wherein a molar ratio of the component (A) to the component (B) is 5:95 to 95:5,
• wherein the volatile plasticizer is present in the second melt in an amount of 0.1 to 10 mols per kg of the total weight of the polyethylene-based resin (PE-2) and the ionomer resin,
• wherein the ionomer resin has a melt flow rate of 7 g/10 min or less at a temperature of 190° C. and a load of 2.16 kg, and
• wherein the second melt comprises 3% by weight or less of a styrene-based resin.