Composite sheet and manufacturing method for a foamed decorative sheet free of PVC and plasticizers
A composite sheet and a method for producing a decorative sheet using the composite sheet are provided. The composite sheet has a base layer and a foamable layer bonded to the base layer. The foamable layer includes 100 parts by weight of a polyolefin material having an elastic modulus of <0.1 GPa, 0.1-10 parts by weight of a foaming agent, and 0-200 parts by weight of additives. The foamable layer has a thickness of 0.05 to 0.3 mm.
1. A method for producing a foamed decorative sheet, the method comprising:
melt processing a foamable layer on a base layer to form a curling-free composite sheet, the base layer being made of a paper or non-woven material, the paper or non-woven material having a first thickness of 0.1 mm, a first elastic modulus of >1 GPa, and showing a change of dimensions of less than 2% when heated from 0° C. to 220° C. and subsequently cooled to 0° C., the foamable layer having a second thickness of 0.15 mm, being made of components mixed at 140° C., 60 RPM, and subsequently being laminated on the paper or non-woven material at 140° C., the components consisting of 100 parts by weight of an Ethylene-octene copolymer, having a melt flow index of 5, and a second elastic modulus of 0.011 GPa, 5 parts by weight of Azodicarbonamide, and 1 part by weight of ZnO;
printing on the curling-free composite sheet; and
foaming of the curling-free composite sheet.
2. The method of claim 1 , wherein a ratio of the second elastic modulus of the foamable layer and the first elastic modulus of the base layer is less than 0.05 to prevent curling of the curling-free composite sheet during heating-cooling circles in a wall cover production process.
3. The method of claim 1 , further comprising:
performing cross-linking of the foamable layer with at least one of ionizing radiation and employing a cross-linking agent,
wherein the ionizing radiation is conducted by an electron beam with 100 to 300 kV voltage and a dosage of 10 to 200 kGy, and
wherein the cross-linking agents decompose to radicals at an elevated temperature.
4. The method of claim 1 , wherein printing on the curling-free composite sheet includes at least one of gravure printing, flexo screen printing, inkjet printing, and coronary treatment.
5. The method of claim 1 , wherein foaming of the curling-free composite sheet is performed at a temperature between 120° C. and 210° C., and
wherein the temperature depends on the foaming agent.
6. The method of claim 1 , wherein the curling-free composite sheet is produced in a continuous mode with a width between 0.5 and 3.0 meters.
7. The method of claim 1 , wherein the foamable layer further includes additives selected from the group consisting of catalysts, pigments, fillers, matting agents, microbial agents, UV stabilizers, fire retardants and release compounds.
8. The method of claim 7 , wherein the additives include a catalyst, and
wherein the catalyst is selected from the group consisting of barium ricinoleate, tin methoxy maleate, hydrated calcium silicate, calcium stearate, zinc stearate, lead acetate, zinc laurate, zinc octonoate, and cadmium amyl phosphite.
9. The method of claim 1 , wherein the foamed decorative sheet is a wall cover.