WO2018028111A1

WO2018028111A1 - Foam pad and preparation method therefor

Info

Publication number: WO2018028111A1
Application number: PCT/CN2016/111474
Authority: WO
Inventors: 王衍萍
Original assignee: 江苏锦厚新材料科技有限公司
Priority date: 2016-08-12
Filing date: 2016-12-22
Publication date: 2018-02-15
Also published as: FR3054974A1; FR3054974B1; CN106317550A; GB2552865B; CN106317550B; GB2552865A; GB201704539D0; DE112016000112T5

Abstract

Provided are a foam pad and a preparation method therefor. The foam pad comprises a base layer and film layers covering the upper surface and the lower surface of the base layer. The base layer is a foam body and is a uniform porous body, wherein the average pore size of the pores is 1-100 μm. The film layers are uniform and dense. The preparation method for the foam pad comprises a supercritical foaming process and a filming process. The foam pad has good flexibility, softness and elasticity, is a food-grade plastic sheet, and has good tightness when being used for a bottle cap gasket. The preparation method is simple and can be easily industrialized.

Description

Foaming pad and preparation method thereof

Technical field

The invention belongs to the technical field of high safety fields such as food packaging and pharmaceutical packaging, and relates to a foaming pad and a preparation method thereof, in particular to a sealing gasket for a bottle cap and a preparation method thereof.

Background technique

The cap gasket is a material that uses rubber, copper or paper to be placed between the two planes to enhance the seal and to prevent fluid leakage. With the continuous development of the economy, cap gaskets are widely used in the wine, food, cosmetics, pharmaceutical and other industries.

According to relevant news reports, the demand for cap gaskets in China's wine packaging and beverage packaging is increasing, and the cap gaskets used in alcohol packaging account for more than 70% of the total use of cap gaskets. With the rapid development of China's wine and beverage industry, the cap gasket industry has gradually emerged. In 2014, the total production of cap gaskets in China increased by 14% compared with 2013. This huge demand not only drove the price of cap gaskets, but also increased the number of cap gasket manufacturers. At present, China has become the world's largest consumer and exporter of cap gaskets.

There are hundreds of products in the cap gasket market in China, and various types of specifications and types of cap gaskets are filled with the food packaging container market. At present, the gaskets used in food packaging are PVC (polyvinyl chloride), PE (polyethylene), rubber backing pad, aluminum foil composite gasket, paper-plastic aluminum composite gasket, etc., among which PVC and PE are the main materials. .

CN 104250404A discloses a can cap gasket granule and a preparation method thereof, the can cap gasket granules being formulated in mass parts, comprising 30-50 parts of polypropylene, 30-50 parts of polyethylene, thermoplastic 10-30 parts of the elastomer, 0.4-5 parts of the processing aid, the above raw materials are mixed by a high-mixer, extruded by an extruder, cooled, and diced to obtain canned bottle gasket pellets. The canned cap gasket pellets are completely safe and non-toxic. It does not add plasticizers such as o-benzene which are harmful to the human body, which not only satisfies the need for safe and non-toxic pellets for food cans, but also has excellent sealing properties.

CN 1465507A discloses a bottle inner pad material and its use in a hot-filled beverage plastic bottle cap, modified EVA (ethylene-vinyl acetate copolymer), SEBS (hydrogenated styrene diene copolymer) by maleic acid ), a combination of hydrogenated paraffin oil, branched low density polyethylene, polypropylene, polystyrene and low molecular lubricant, containing EVA with a VA (vinyl acetate) content of 18%, weight ratio of 5-60%, added The ethylene-α-olefin copolymer has a weight ratio of 90-35%. This material is not found in conventional cover gasket materials. The inner cushion material prepared by the blending has superior performance compared with the inner cushion material of the existing beverage packaging plastic bottle cap, and the gasket material is not only low in price, but also has a material than the traditional hot-filled plastic bottle cap inner pad material. The effect is good.

However, the sealing properties of the existing cap gaskets have yet to be further improved.

Summary of the invention

In view of the deficiencies of the prior art, the object of the present invention is to provide a foaming pad and a preparation method thereof, which are soft, flexible and elastic, and are food-grade plastic sheets for cap gaskets. It has excellent sealing properties, and its preparation method is simple and convenient for industrial application.

1 bar = 0.1 MPa.

To this end, the present invention employs the following technical solutions:

One of the objects of the present invention is to provide a foaming mat comprising a base layer and a film layer covering the upper surface and the lower surface of the base layer, the base layer being a foam and having uniform capillary pores The average pore diameter of the capillary is 1-100 μm, such as 2 μm, 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 80 μm, 90 μm or 95 μm, etc.; The layer is even and dense;

The base layer is mainly prepared from the following raw materials in terms of mass percentage:

PE (polyethylene) 0-90%, such as 2%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% or 85%;

PP (polypropylene) 0-90%, such as 2%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% or 85%;

Any one or a combination of at least two of POE (ethylene-octene copolymer), SBS (block copolymer of styrene and butadiene) or SEBS (hydrogenated styrene-butadiene block copolymer) 0-20% (excluding 0), such as 0.5%, 1%, 2%, 3%, 5%, 6%, 8%, 10%, 12%, 15% or 18%;

The release agent is 0.2-1.0%, such as 0.3%, 0.5%, 0.6%, 0.7%, 0.8% or 0.9%;

Nucleating agent 0.1-2.5%, such as 0.3%, 0.5%, 0.8%, 1.0%, 1.2%, 1.5%, 1.8%, 2.0% or 2.3%;

Color masterbatch 0-2.0%, such as 0.1%, 0.5%, 0.8%, 1.0%, 1.2%, 1.3%, 1.5%, 1.7% or 1.9%;

Wherein, the mass percentage of at most one of PE and PP is 0; the combination of POE, SBS or SEBS, such as POE and SBS, POE and SEBS, POE, SBS and SEBS.

The film layer is mainly prepared from the following raw materials in terms of mass percentage:

PE 0-93%, such as 2%, 3%, 5%, 10%, 20%, 30%, 50%, 60%, 70%, 80% or 90%;

PP 0-95%, such as 1%, 3%, 5%, 8%, 10%, 20%, 30%, 50%, 60%, 80% or 90%;

POE 0-93%, such as 2%, 3%, 5%, 10%, 20%, 30%, 50%, 60%, 70%, 80% or 90%;

Tackifier 0-30%, such as 1%, 3%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 23%, 25% or 28%, etc.;

The release agent is 0.2-1.1%, such as 0.3%, 0.5%, 0.8% or 1.0%;

The opening agent is 0.1-3.0%, such as 0.3%, 0.5%, 0.8%, 1.0%, 1.2%, 1.5%, 1.8%, 2.0%, 2.1%, 2.3%, 2.5% or 2.8%;

Among them, the mass percentage of at most one of PE, PP and POE is zero.

The fact that the base layer is a uniform capillary pore means that the base layer contains a plurality of uniformly distributed capillary pores.

As a preferred technical solution, the base layer is prepared by massing the following materials:

Preferably, the release agent is selected from any one or a combination of at least two of a masterbatch made of oleic acid amide, erucic acid amide or oleic acid amide and erucic acid amide, which is a carrier of PE or PP. A typical but non-limiting combination such as a combination of oleic acid amide and erucamide, a combination of oleic acid amide and oleic acid amide with a erucamide amide or a masterbatch based on PE or PP, erucamide and oleic acid amide A combination of a masterbatch made of erucamide or a carrier based on PE or PP.

Preferably, the nucleating agent is selected from the group consisting of sodium bicarbonate and citric acid as main active ingredients, and PE or PP or EVA as a carrier.

As a preferred technical solution, the film layer is mainly prepared from the following raw materials by mass percentage:

Preferably, the tackifier is selected from any one or a combination of at least two of EEA (ethylene ethyl acrylate), polyester or maleic anhydride graft resin. Typical but non-limiting combinations are combinations of EEA and polyester, combinations of EEA with maleic anhydride grafted resins, combinations of EEA, polyester and maleic anhydride grafted resins.

Preferably, the opening agent is selected from the group consisting of erucamide.

The base layer has a thickness of 0.5 to 10.0 mm, such as 0.8 mm, 1.0 mm, 1.5 mm, 2.0 mm, 3.0 mm, 4.0 mm, 5.0 mm, 6.0 mm, 8.0 mm, or 9.0 mm. If it is too thick, the application performance such as material sealing performance is not guaranteed; if it is too thin, the flexibility of the material and the compensation performance are insufficient.

Preferably, the base layer has a density of 100-800 kg/m ³ , such as 150 kg/m ³ , 200 kg/m ³ , 300 kg/m ³ , 400 kg/m ³ , 500 kg/m ³ , 600 kg/m ³ or 700 kg/ m ³ and so on.

The base layer is excellent in cross-linking sealing property due to supercritical physical foaming.

Preferably, the film layer has a thickness of from 0.02 to 0.15 mm, such as 0.05 mm, 0.08 mm, 0.10 mm, 0.12 mm or 0.14 mm, and the like. If the film is too thick, the flexibility of the material will not be sufficient to compensate for the performance. If the film is too thin, the application performance such as material sealing performance is not guaranteed. The thickness of the film layer is 0.02-0.15 mm means The thickness of the upper surface film layer of the base layer and the thickness of the lower surface film layer are independently 0.02 to 0.15 mm.

The film layer allows the foam pad to have good flexibility and meet the sealing functional requirements.

Another object of the present invention is to provide a method for preparing a foaming mat as described above, which comprises the following steps:

(1) feeding the formulated amount of the base layer raw material into the hopper of the single-screw extruder, simultaneously charging the central portion of the single-screw extruder with supercritical carbon dioxide, and extruding and foaming to obtain a base layer, the supercritical carbon dioxide Supercritical carbon dioxide at a pressure of 50-220 bar, such as supercritical carbon dioxide at a pressure of 60 bar, 80 bar, 90 bar, 100 bar, 120 bar, 150 bar, 180 bar or 200 bar;

(2) The formulated amount of the film raw material is fed into a single-screw extruder hopper, and a film is deposited on the surface of the base layer to obtain the foamed mat.

The single-screw extruder of the step (1) is a single-screw extruder having heating and cooling withstand characteristics, and a typical but non-limiting single-screw extruder such as a foaming machine manufactured by Berstorff Co., Ltd.: 150 -ISO-PAC.

In the extrusion process of the step (1), the host temperature of the single-screw extruder is ≤65 ° C, such as 63 ° C, 60 ° C, 58 ° C, 55 ° C, 50 ° C, 45 ° C or 30 ° C, etc., the host temperature is too high, This will result in damage to the unit.

Preferably, the extrusion temperature in the step (1) is 90-210 ° C, such as 100 ° C, 110 ° C, 130 ° C, 150 ° C, 180 ° C, 190 ° C or 200 ° C, etc., and the extrusion temperature is high, then the film formability Poor, uneven thickness, uneven foaming; low extrusion temperature, film foaming uneven or unable to foam.

Preferably, the rotation speed of the screw during the extrusion in the step (1) is 1-100 rpm, such as 2 rpm, 3 rpm, 5 rpm, 10 rpm, 20 rpm, 30 rpm, 40 rpm, 50 rpm, 60 rpm, 70 rpm, 80 rpm or 90 rpm, and the like.

Preferably, the single screw extruder of step (1) has a pressure range of 0-250 bar, such as 2 bar, 5 bar, 10 bar, 20 bar, 50 bar, 100 bar, 120 bar, 150 bar, 180 bar, 200 bar, 220 bar or 240 bar, and the like.

The flow rate of the supercritical carbon dioxide in the step (1) is 0.10-2.50 kg/h, such as 0.3 kg/h, 0.5 kg/h, 0.8 kg/h, 1.0 kg/h, 1.2 kg/h, 1.5 kg/h, 1.8kg / h, 2.0kg / h or 2.3kg / h, etc., the flow rate of carbon dioxide is high, the film foaming is uneven, excessive foaming, material elasticity failure; low flow, foaming is too low, flexibility is not enough.

Preferably, the thickness of the base layer in the step (1) is 0.5-10.0 mm, such as 0.8 mm, 1.0 mm, 1.5 mm, 2.0 mm, 3.0 mm, 4.0 mm, 5.0 mm, 6.0 mm, 8.0 mm or 9.0 mm, etc. .

Preferably, the density of the base layer in the step (1) is 100-800 kg/m ³ , such as 150 kg/m ³ , 200 kg/m ³ , 300 kg/m ³ , 400 kg/m ³ , 500 kg/m ³ , 600 kg/m. ³ or 700kg/m ³ and so on.

The temperature of the extrusion in the step (2) is 80-250 ° C, such as 85 ° C, 90 ° C, 95 ° C, 100 ° C, 120 ° C, 130 ° C, 150 ° C, 180 ° C, 200 ° C, 210 ° C, 220 ° C or 240 ° C and so on.

Preferably, the rotation speed of the screw during the extrusion in the step (2) is 1-100 rpm, such as 2 rpm, 3 rpm, 5 rpm, 10 rpm, 20 rpm, 30 rpm, 40 rpm, 50 rpm, 60 rpm, 70 rpm, 80 rpm or 90 rpm, and the like.

The thickness of the base layer coating in the step (2) is 0.02-0.15 mm, such as 0.05 mm, 0.08 mm, 0.10 mm, 0.12 mm or 0.14 mm.

The coating in step (2) can be made into a functional film according to the needs of downstream applications.

As a preferred technical solution, the preparation method comprises the following steps:

(1) The formulated amount of the base layer raw material is fed into the hopper of the single-screw extruder, and the supercritical carbon dioxide under the pressure of 50-220 bar is charged into the middle of the single-screw extruder, and the flow rate of the supercritical carbon dioxide is 0.10-2.50. Kg/h, after extrusion, to obtain a substrate layer having a density of 100-800 kg/m ³ and a thickness of 0.5-10.0 mm, wherein the main screw temperature of the single-screw extruder during the extrusion process is ≤65 ° C; The temperature is 90-210 ° C; the speed of the screw during extrusion is 1-100 rpm; the pressure range of the single-screw extruder is 0-250 bar;

(2) The film material of the formula amount is sent into the hopper of the single-screw extruder, and the film is coated on the surface of the substrate layer to obtain a foaming pad with a film thickness of 0.02-0.15 mm, wherein the extrusion temperature is 80- 250 ° C; the speed of the screw during extrusion is 1-100 rpm.

Compared with the prior art, the beneficial effects of the present invention are:

The foaming mat provided by the invention comprises a base layer and a film layer, the base layer is obtained by foaming, has good cross-linking sealing property, and has better flexibility, flexibility and elasticity, and the surface covered film layer makes the The foaming pad has good flexibility and meets the sealing functional requirements. Its Shore A hardness is 35-50. It has excellent sealing property and good opening performance for the cap gasket. And the effect of improving the flatness, in addition, it is a food grade plastic sheet;

The foaming mat provided by the invention has a simple preparation method and is convenient for industrial application.

detailed description

The technical solution of the present invention will be further described below by way of specific embodiments.

In the preparation method of the following examples, the single-screw extruder of the step (1) is a single-screw extruder having heating, cooling and pressure resistance characteristics - a foaming machine manufactured by Berstorff Co., Ltd.: 150- ISO-PAC.

The thickness of the film layer described in the following examples is a numerical value means that the thickness of the upper surface film layer of the base layer and the thickness of the lower surface film layer are independently a certain value.

Example 1

A foaming mat comprising a base layer and a film layer covering the upper surface and the lower surface of the base layer, the base layer being a foam and being a uniform capillary pore-shaped body, an average diameter of the capillary pores a film thickness of 1 to 30 μm; the film layer is uniform and dense; the thickness of the substrate layer is 0.5 mm; The thickness is 0.02 mm;

The release agent is selected from the group consisting of oleic acid amide;

The nucleating agent is selected from the group consisting of sodium bicarbonate and citric acid as main active ingredients, and PE or PP or EVA as a carrier.

The tackifier is selected from the group consisting of EEA (ethylene acrylate).

The release agent is selected from oleic acid amides.

The opening agent is selected from the group consisting of erucamide.

The preparation method of the foaming pad comprises the following steps:

(1) The formulated amount of the base layer raw material is fed into the hopper of the single-screw extruder, and the supercritical carbon dioxide under the pressure of 50 bar is charged into the middle of the single-screw extruder, and the flow rate of the supercritical carbon dioxide is 2.50 kg/h. After extrusion foaming, a base layer is obtained, wherein the single screw extruder in the extrusion process has a host temperature of 65 ° C; an extrusion temperature of 210 ° C; and a screw rotation speed of 1 rpm during extrusion; The screw extruder has a pressure range of 250 bar;

(2) feeding the formulated amount of the film raw material into the hopper of the single-screw extruder, and coating the surface of the substrate layer to obtain a foaming pad having a film thickness of 0.02 mm, wherein the extrusion temperature is 80 ° C; The speed of the screw during the exit was 100 rpm.

Example 2

A foaming mat comprising a base layer and a film layer covering the upper surface and the lower surface of the base layer, the base layer being a foam and being a uniform capillary pore-shaped body, an average diameter of the capillary pores a film layer of 50-100 μm; the film layer is uniform and dense; the thickness of the substrate layer is 10.0 mm; the thickness of the film layer is 0.15 mm;

The release agent is selected from the group consisting of oleic acid amides and erucamides.

The tackifier is selected from the group consisting of EEA and polyester.

The release agent is selected from the group consisting of oleic acid amide and erucamide, and a masterbatch based on PE or PP.

The opening agent is selected from the group consisting of erucamide.

The preparation method of the foaming pad comprises the following steps:

(1) The formulated amount of the base layer raw material is fed into the hopper of the single-screw extruder, and the supercritical carbon dioxide under the pressure of 220 bar is charged into the middle of the single-screw extruder, and the flow rate of the supercritical carbon dioxide is 0.10 kg/h. After extrusion foaming, a base layer is obtained, wherein the single screw extruder in the extrusion process has a host temperature of 50 ° C; an extrusion temperature of 90 ° C; and a screw rotation speed of 100 rpm during extrusion; The screw extruder has a pressure range of 100 bar;

(2) feeding the film material of the formula amount into the hopper of the single-screw extruder, and coating the surface of the substrate layer to obtain a foaming pad with a film thickness of 0.15 mm, wherein the extrusion temperature is 250 ° C; The speed of the screw during the exit was 1 rpm.

Example 3

A foaming mat comprising a base layer and a film layer covering the upper surface and the lower surface of the base layer, the base layer being a foam and being a uniform capillary pore-shaped body, an average diameter of the capillary pores a film thickness of 30-80 μm; the film layer is uniform and dense; the thickness of the substrate layer is 5.0 mm; the thickness of the film layer is 0.10 mm;

The release agent is selected from the group consisting of erucamide.

The tackifier is selected from the group consisting of maleic anhydride graft resins.

The opening agent is selected from the group consisting of erucamide.

The preparation method of the foaming pad comprises the following steps:

(1) The formulated amount of the base layer raw material is fed into the hopper of the single-screw extruder, and the supercritical carbon dioxide under the pressure of 100 bar is charged into the middle of the single-screw extruder, and the flow rate of the supercritical carbon dioxide is 1.00 kg/h. After extrusion foaming, a base layer is obtained, wherein the single screw extruder in the extrusion process has a host temperature of 60 ° C; an extrusion temperature of 120 ° C; and a screw rotation speed of 20 rpm during extrusion; The screw extruder has a pressure range of 120 bar;

(2) feeding the film material of the formula amount into the hopper of the single-screw extruder, and coating the surface of the substrate layer to obtain a foaming pad with a film thickness of 0.10 mm, wherein the extrusion temperature is 100 ° C; The speed of the screw during the exit was 20 rpm.

Example 4

A foaming mat comprising a base layer and a film layer covering the upper surface and the lower surface of the base layer, the base layer being a foam and being a uniform capillary pore-shaped body, an average diameter of the capillary pores The film layer is a laminating layer, the film layer is uniform and dense; the thickness of the substrate layer is 3.0 mm; the thickness of the film layer is 0.05 mm;

Preferably, the tackifier is selected from the group consisting of EEA, polyester and maleic anhydride graft resin in terms of mass ratio A 1:1:1 combination.

The release agent is selected from oleic acid amides.

The opening agent is selected from the group consisting of erucamide.

The preparation method of the foaming pad comprises the following steps:

(1) The formulated amount of the base layer raw material is fed into the hopper of the single-screw extruder, and the supercritical carbon dioxide under the pressure of 150 bar is charged into the middle of the single-screw extruder, and the flow rate of the supercritical carbon dioxide is 2.0 kg/h. After extrusion foaming, a base layer is obtained, wherein the single screw extruder in the extrusion process has a host temperature of 55 ° C; an extrusion temperature of 170 ° C; and a screw rotation speed of 80 rpm during extrusion; The screw extruder has a pressure range of 150 bar;

(2) feeding the film material of the formula amount into the hopper of the single-screw extruder, and coating the surface of the substrate layer to obtain a foaming pad with a film thickness of 0.05 mm, wherein the extrusion temperature is 180 ° C; The speed of the screw during the exit was 90 rpm.

Example 5

A foaming mat comprising a base layer and a film layer covering the upper surface and the lower surface of the base layer, the base layer being a foam and being a uniform capillary pore-shaped body, an average diameter of the capillary pores a film thickness of 1-100 μm; the film layer is uniform and dense; the thickness of the substrate layer is 3.0 mm; the thickness of the film layer is 0.05 mm;

The release agent is selected from oleic acid amides.

The opening agent is selected from the group consisting of erucamide.

The preparation method of the foaming pad comprises the following steps:

Comparative example 1

The comparative example 1 is the base layer obtained in Example 3.

Comparative example 2

The comparative example 2 is a commercially available PE gasket (manufacturer: Shanghai Mingyuan Plastic Products Co., Ltd.).

Comparative example 3

A foaming pad and a preparation method thereof are the same as those in Embodiment 5 except that the flow rate of supercritical carbon dioxide is 0.08 kg/h.

Comparative example 4

A foaming pad and a preparation method thereof are the same as in the embodiment 5 except that the flow rate of the supercritical carbon dioxide is 2.60 kg/h.

The products obtained in Examples 1-5 and Comparative Examples 1-4 were tested for performance. The density test method was GB1033, the flexibility test method was the inductive test, the Shore hardness test method was GB2411, and the seal test method was Self-made oil-infiltration method (the bottle cap made of foaming pad is sealed with glass bottle filled with edible oil, placed on the platform with white paper on the side, and after 10 days, it is observed whether there is oil leakage on the white paper, the oil seepage is unqualified, no The oil seepage is acceptable). The test results are shown in Table 1 below:

Table 1

	密度density	柔韧性Flexibility	邵氏A硬度Shore A hardness	用于瓶盖垫片的密封性Sealing for cap gaskets
实施例1Example 1	300g/L300g/L	优良excellent	5050	合格qualified
实施例2Example 2	288g/L288g/L	良好good	5151	合格qualified
实施例3Example 3	425g/L425g/L	优良excellent	4545	合格qualified
实施例4Example 4	403g/L403g/L	良好good	4848	合格qualified
实施例5Example 5	389g/L389g/L	优良excellent	3535	合格qualified

对比例1Comparative example 1	305g/L305g/L	一般general	5757	合格qualified
对比例2Comparative example 2	297g/L297g/L	一般general	6060	合格qualified
对比例3Comparative example 3	412g/L412g/L	一般general	6565	合格qualified
对比例4Comparative example 4	263g/L263g/L	一般general	6262	合格qualified

It can be seen that the foaming pad provided by the invention has excellent performance and excellent sealing performance for the cap gasket. In addition, the foaming pad provided by the invention meets food grade requirements and can be widely used in high security fields such as food packaging and pharmaceutical packaging.

The Applicant declares that the present invention is described by the above-described embodiments, but the present invention is not limited to the above detailed methods, that is, it does not mean that the present invention must be implemented by the above detailed methods. It should be apparent to those skilled in the art that any modifications of the present invention, equivalent substitution of the various materials of the products of the present invention, addition of auxiliary components, selection of specific means, and the like, are all within the scope of the present invention.

Claims

A foaming mat, comprising: a base layer and a film layer covering the upper surface and the lower surface of the base layer, the base layer being a foam and being a uniform capillary body, The average pore diameter of the pores is 1-100 μm;

The base layer is mainly prepared from the following raw materials in terms of mass percentage:

Wherein, the mass percentage of at most one of the PE and the PP is 0;

The film layer is mainly prepared from the following raw materials in terms of mass percentage:

Among them, the mass percentage of at most one of PE, PP and POE is zero.
The foaming mat according to claim 1, wherein the base layer is prepared in a mass percentage from the following materials:
The foaming pad according to claim 1 or 2, wherein the releasing agent is selected from the group consisting of oleic acid amide, erucic acid amide or oleic acid amide and erucamide, and a masterbatch based on PE or PP. Any one or a combination of at least two.
A foaming mat according to any one of claims 1 to 3, wherein the nucleating agent is selected from the group consisting of sodium bicarbonate and citric acid as main active ingredients, and a masterbatch based on PE or PP or EVA.
The foaming mat according to any one of claims 1 to 4, characterized in that the film layer is mainly prepared from the following raw materials by mass percentage:

Preferably, the tackifier is selected from any one or a combination of at least two of EEA, polyester or maleic anhydride graft resin;

Preferably, the release agent is selected from the group consisting of oleic acid amide, erucic acid amide or oleic acid amide with erucamide and any combination of at least two of a masterbatch based on PE or PP;

Preferably, the opening agent is selected from the group consisting of erucamide.
The foaming pad according to any one of claims 1 to 5, wherein the base layer has a thickness of 0.5 to 10.0 mm;

Preferably, the base layer has a density of 100-800 kg/m 3 ;

Preferably, the film layer has a thickness of from 0.02 to 0.15 mm.
The method for preparing a foaming mat according to any one of claims 1 to 6, wherein the preparation method comprises the following steps:

(1) feeding the formulated amount of the base layer raw material into the hopper of the single-screw extruder, simultaneously charging the central portion of the single-screw extruder with supercritical carbon dioxide, and extruding and foaming to obtain a base layer, the supercritical carbon dioxide Supercritical carbon dioxide at a pressure of 50-220 bar;

(2) The formulated amount of the film raw material is fed into a single-screw extruder hopper, and a film is deposited on the surface of the base layer to obtain the foamed mat.
The preparation method according to claim 7, wherein the main screw temperature of the single-screw extruder in the extrusion process in the step (1) is ≤ 65 ° C;

Preferably, the extrusion temperature in step (1) is 90-210 ° C;

Preferably, the speed of the screw in the extrusion process in the step (1) is 1-100 rpm;

Preferably, the single screw extruder of step (1) has a pressure range of 0-250 bar.
The preparation method according to claim 7 or 8, wherein the flow rate of the supercritical carbon dioxide in the step (1) is 0.10-2.50 kg / h;

Preferably, the thickness of the base layer in step (1) is 0.5-10.0 mm;

Preferably, the density of the base layer in the step (1) is from 100 to 800 kg/m 3 .
The preparation method according to any one of claims 7-9, characterized in that the temperature of the extrusion in the step (2) is 80-250 ° C;

Preferably, the rotation speed of the screw during the extrusion in the step (2) is 1-100 rpm.
The preparation method according to any one of claims 7 to 10, wherein the base layer coating film has a thickness of 0.02 to 0.15 mm in the step (2).
The preparation method according to any one of claims 7 to 11, characterized in that the preparation method comprises the following steps:

(1) The formulated amount of the base layer raw material is fed into the hopper of the single-screw extruder, and the supercritical carbon dioxide under the pressure of 50-220 bar is charged into the middle of the single-screw extruder, and the flow rate of the supercritical carbon dioxide is 0.10-2.50. Kg/h, after extrusion foaming, to obtain a substrate layer having a density of 100-800 kg/m 3 and a thickness of 0.5-10.0 mm, wherein the host temperature of the single-screw extruder during the extrusion process is ≤65 ° C The extrusion temperature is 90-210 ° C; the speed of the screw during extrusion is 1-100 rpm; the pressure range of the single-screw extruder is 0-250 bar;

(2) The film material of the formula amount is sent into the hopper of the single-screw extruder, and the film is coated on the surface of the substrate layer to obtain a foaming pad with a film thickness of 0.02-0.15 mm, wherein the extrusion temperature is 80- 250 ° C; the speed of the screw during extrusion is 1-100 rpm.