Composition for producing foamed layer of sheet, sheet containing the same, and production method thereof

1. A sheet, comprising: a foamed layer, a first solid layer and a second solid layer, the first solid layer and the second solid layer being directly formed on two sides of the foamed layer via co-extruding with the foamed layer; wherein,

the foamed layer is prepared from a first composition, and the first composition consists of polyvinyl chloride, calcium carbonate, a first regulator, a first stabilizer, a first lubricant and a foaming agent; in parts by weight,

the polyvinyl chloride 75 parts;

the calcium carbonate 75-80 parts;

the first regulator 6-8 parts;

the first stabilizer 3-5 parts;

the first lubricant 0.7-1.4 parts; and

the foaming agent 0.2-0.7 parts;

each of the first and second solid layers is prepared from a second composition, and the second composition comprises a second primary component and a second auxiliary component; the second primary component is composed of polyvinyl chloride and calcium carbonate, and the second auxiliary component comprises a second regulator, a second stabilizer and a second lubricant; in parts by weight,

the polyvinyl chloride 50 parts;

the calcium carbonate 50-55 parts;

the second regulator 2-7 parts;

the second stabilizer 2-4 parts; and

the second lubricant 0.5-1.1 parts; and

the sheet does not contain glue-like component.

2. The sheet according to claim 1 , wherein the first lubricant comprises a first internal lubricant and a first external lubricant, and a mass ratio of the first internal lubricant to the first external lubricant is 2:1 to 3:1; the second lubricant comprises a second internal lubricant and a second external lubricant; and a mass ratio of the second internal lubricant to the second external lubricant is 2:1 to 3:1.

3. The sheet according to claim 2 , wherein the first internal lubricant and the second internal lubricant are one or more of stearic acid, polyol stearic acid and oxidized polyethylene wax; and the first external lubricant and the second external lubricant are polyethylene wax.

4. The sheet according to claim 2 , wherein the foaming agent comprises a white foaming agent and a yellow foaming agent, and a mass ratio of the white foaming agent to the yellow foaming agent is 1:1 to 3:1.

5. The sheet according to claim 1 , wherein an anti-slip layer is provided on a surface of the first solid layer facing away from the foamed layer.

6. The sheet according to claim 5 , wherein a color film layer is provided on a surface of the second solid layer facing away from the foamed layer.

7. The sheet according to claim 6 , wherein a wear-resistant layer is provided on a surface of the color film layer.

8. The sheet according to claim 7 , wherein,

the second solid layer has a thickness of 1 mm to 1.5 mm;

the first solid layer has a thickness of 0.3 mm to 0.5 mm;

the foamed layer has a thickness of 2.5 mm to 3.5 mm;

the anti-slip layer has a thickness of 0.15 mm to 0.3 mm;

the wear-resistant layer has a thickness of 0.15 mm to 0.5 mm, and

the color film layer has a thickness of 0.07 mm to 0.08 mm.

9. The sheet according to claim 1 , wherein the second composition further comprises a plasticizer, and the plasticizer accounts for 1% to 8% of a total mass of the second composition.

10. The sheet according to claim 9 , wherein the plasticizer is dioctyl phthalate, epoxidized soybean oil or dioctyl terephthalate.

11. The sheet according to claim 1 , wherein a density of the sheet is within 0.9 T/m 3 to 1.2 T/m 3 , and shrinkage of the sheet at 80° C. is less than or equal to 0.5%.

12. The sheet according to claim 3 , wherein the first internal lubricant and the second internal lubricant are one or two of polyol stearic acid and oxidized polyethylene wax.

13. The sheet according to claim 1 , wherein the sheet is produced from a method comprising following steps:

(1) blending: blending the first composition for producing the foamed layer of the sheet, and the second composition for producing the first and second solid layers of the sheet, respectively, hotly blending first, and then cooling and stirring at a temperature of 105° C. to 120° C.;

(2) melting: when temperatures of the first and second compositions are decreased to 30° C. to 40° C., loading the blended first and second compositions to a hopper of an extruder which is preheated to 150° C. to 180° C., respectively; and heating and extruding the first and second compositions to obtain a first melt of the first composition and a second melt of the second composition, respectively;

(3) distributing and molding: feeding, by a distributor, the first and second melts of the first and second compositions into a mold at 160° C. to 180° C. for molding, so that the first solid layer and the second solid layer are directly formed on two sides of the foamed layer;

(4) shaping and combining: cooling and flattening the first and second solid layers and the foamed layer at 20° C. to 50° C.

14. The sheet according to claim 13 , wherein the method further comprises following steps:

(5) gradually rising the temperature, placing respectively a color film layer(s) to be combined and/or an anti-slip layer to be combined on two sides of the two solid layers by a conveyor device(s), and then compressing and combining at 130° C. to 180° C.; and finally, placing a wear-resistant layer on a surface of the color film layer by a conveyor device, and then compressing and combining at 130° C. to 180° C. to form the sheet; and

(6) cutting: cooling and then cutting the sheet.