阅读说明：本技术 多层共挤eva树脂发泡并交联的合成革 (Multilayer co-extrusion EVA resin foamed and crosslinked synthetic leather ) 是由 李民 李庆北 蔡相成 于 2019-10-23 设计创作，主要内容包括：本发明公开了一种多层共挤EVA树脂发泡并交联的合成革,该合成革从上到下依次包括聚氨酯层、多层共挤EVA树脂层和贴合在树脂层上的基底层。其中多层共挤EVA树脂层经交联处理且包括至少一层发泡层和至少一层改性层。本发明制备的多层共挤EVA树脂发泡并交联的合成革,经交联后耐温性优异、柔软且回弹性好、耐老化性和耐溶剂性能优异,EVA树脂层采用多层共挤方式,生产工艺简单,基底层与多层共挤EVA树脂层层间粘合力良好,层间粘合力可达到5N/cm以上。(The invention discloses a synthetic leather foamed and crosslinked by multilayer co-extrusion EVA resin. Wherein the multi-layer co-extrusion EVA resin layer is subjected to cross-linking treatment and comprises at least one foaming layer and at least one modified layer. The synthetic leather foamed and crosslinked by the multilayer co-extrusion EVA resin prepared by the invention has excellent temperature resistance, softness, good resilience, aging resistance and solvent resistance after crosslinking, the EVA resin layer adopts a multilayer co-extrusion mode, the production process is simple, the interlayer adhesive force between the substrate layer and the multilayer co-extrusion EVA resin layer is good, and the interlayer adhesive force can reach more than 5N/cm.)

1. The utility model provides a synthetic leather that multilayer is crowded EVA resin altogether and is foamed and crosslinked which characterized in that, synthetic leather from the top down include polyurethane layer, multilayer crowded EVA resin layer altogether and the laminating is in multilayer crowded EVA resin layer on the stratum basale altogether in proper order, multilayer crowded EVA resin layer altogether through foaming and cross-linking treatment and including at least one deck modified layer and at least one deck foaming layer, the modified layer is hugged closely on the polyurethane layer.

2. The multilayer co-extrusion EVA resin foamed and crosslinked synthetic leather according to claim 1, wherein the foamed layer comprises 100 parts of EVA resin, 1-15 parts of foaming agent, 0-4 parts of crosslinking agent, 0-100 parts of elastomer, 0-200 parts of filler, 0-10 parts of foaming promoter, 0-5 parts of lubricant and 0-20 parts of colorant.

3. The multilayer co-extrusion EVA resin foamed and crosslinked synthetic leather according to claim 1, wherein the modified layer comprises 100 parts of EVA resin, 0-100 parts of elastomer, 0-200 parts of filler, 0-4 parts of crosslinking agent, 0-4 parts of auxiliary crosslinking agent and 0-20 parts of colorant.

4. A synthetic leather foamed and crosslinked with multi-layer co-extruded EVA resins according to claim 2 or 3, characterised in that the crosslinking agent includes but is not limited to one or more of dicumyl peroxide, di-tert-butylperoxy-dicumyl, 1-bis (tert-butylperoxy) -3,3, 5-trimethylcyclohexane, 2, 5-di (tert-butylperoxy) -2, 5-dimethylhexane or n-butyl-4, 4-di (tert-butylperoxy) valerate.

5. The synthetic leather foamed and crosslinked by the multilayer co-extruded EVA resin according to claim 1, wherein the crosslinking degree of the multilayer co-extruded EVA resin layer is 3-95%.

6. The multilayer co-extruded EVA resin foamed and cross-linked synthetic leather of claim 1, characterised in that the foaming and cross-linking treatment is free foaming and cross-linking by a cross-linking agent and/or cross-linking by radiation.

7. The multilayer co-extruded EVA resin foamed and crosslinked synthetic leather of claim 1, wherein the polyurethane layer is a solvent-based, water-based or solvent-free polyurethane coating.

8. The synthetic leather foamed and crosslinked by the multilayer co-extrusion EVA resin of claim 1, wherein the total thickness of the synthetic leather is 0.21-5.3 mm, the thickness of the base layer is 0.1-2.2 mm, the thickness of the multilayer co-extrusion foamed EVA resin layer is 0.1-3.0 mm, the thickness of the modification layer is 0.01-1.0 mm, and the thickness of the polyurethane layer is 0.01-0.10 mm.

Technical Field

The invention relates to the technical field of synthetic leather, in particular to a multilayer co-extruded EVA resin foamed and crosslinked synthetic leather.

Background

With the increasing living standard of people, people put forward higher and higher quality requirements on living goods. Leather, as an article of daily use, has been increasingly demanded not only in the market but also in various requirements (including environmental protection performance, inherent physical strength requirement, durability requirement, solvent resistance requirement, etc.) of customers in recent years. Because the genuine leather can produce a large amount of pollution in the manufacturing process, and meanwhile, the production cost is higher, the durability is relatively poor, the surface physical property is relatively low, the maintenance is difficult and other inherent defects exist, and the potential requirement of high quality of people cannot be met. Synthetic leather has been developed to the present, and because of its advantages such as relatively excellent performance and relatively low cost, it has been used in the manufacture of shoes, bags, sofas, and garments in a large quantity, and the synthetic leather industry has become the support industry of the light industry.

At present, the structure of the whole synthetic leather is built on a base layer which takes Polyurethane (PU) or polyvinyl chloride (PVC) as a main body, a large amount of organic solvents and plasticizers, such as dimethylformamide, methyl ethyl ketone, acetone, toluene, ethyl acetate, o-benzene plasticizers and the like, are used in the production process, and the materials have great harm to human bodies or the environment.

Synthetic leather with EVA as a base material structure has no practical application at present and has few reports. The EVA resin has the advantages of good rebound resilience, flexibility, aging resistance and the like, environmental friendliness, simple process, low cost and the like. This is because EVA is a rubber-like thermoplastic, and has excellent flexibility, low-temperature flexibility, elasticity, stress crack resistance, and good moldability, processability, etc., and is widely used. Ethylene vinyl acetate copolymer (EVA) is a thermoplastic plastic with rubber elasticity, in EVA molecules, due to the existence of a Vinyl Acetate (VA) structural unit, the regularity of a polyethylene molecular chain is greatly reduced, and the crystallinity of the polyethylene molecular chain is reduced, so that the internal rotation movement capability of the molecular chain in thermal movement is greatly improved, the flexibility of the molecular chain is improved, and the ethylene vinyl acetate copolymer (EVA) has high elasticity macroscopically. But because the melting point of the EVA resin is lower than 100 ℃, the EVA resin can hardly be used in the synthetic leather neighborhood if not crosslinked and modified.

Meanwhile, because the hardness of the EVA material is slightly higher than that of the leather material, the EVA material needs to be foamed to reduce the hardness of the EVA material. The foamed EVA can be used for manufacturing high-magnification independent bubble type room temperature foamed plastics, and the material has the advantages of light density, high elasticity, excellent bending resistance and high shock absorption, sound insulation and heat insulation performance, so the foamed EVA is widely used for manufacturing sports equipment, seat cushions, child floors, synthetic leather and the like, is particularly widely applied to sports shoes, case liners and the like, and becomes a hotspot of light material research. However, some disadvantages of the EVA foaming material also limit its application in synthetic leather base materials, such as low temperature hardening, poor mechanical properties, poor resilience, unsatisfactory wear resistance, and the like. Therefore, it is necessary to develop an EVA foamed composite film that can meet the performance requirements of synthetic leather.

Disclosure of Invention

The invention aims to overcome the defects of the technology and provides the synthetic leather foamed and crosslinked by the multi-layer co-extrusion EVA resin, which sequentially comprises a polyurethane layer, a multi-layer co-extrusion EVA resin layer and a substrate layer attached to the resin layer from top to bottom. Wherein the multi-layer co-extrusion EVA resin layer is subjected to cross-linking treatment and comprises at least one foaming layer and at least one modified layer, and the polyurethane layer is tightly attached to the modified layer. The synthetic leather foamed and crosslinked by the multilayer co-extrusion EVA resin prepared by the invention has excellent temperature resistance after crosslinking, softness, good rebound resilience, excellent aging resistance and excellent solvent resistance, the EVA resin layer adopts a multilayer co-extrusion mode, the production process is simple, the interlayer adhesive force between the substrate layer and the multilayer co-extrusion EVA resin layer is good, and the interlayer adhesive force can reach more than 5N/cm.

In order to achieve the purpose, the synthetic leather foamed and crosslinked by the multilayer co-extrusion EVA resin is mainly characterized by comprising a polyurethane layer, a multilayer co-extrusion EVA resin layer and a base layer attached to the resin layer from top to bottom in sequence. The multilayer co-extruded EVA resin layer is foamed and cross-linked and comprises at least one foaming layer and at least one modified layer, and the polyurethane layer is tightly attached to the modified layer.

Preferably, the base layer is any one of knitted elastic napped fabric, plain-knitted napped fabric, knitted plain fabric, woven polyester fabric, nylon fabric, microfiber base fabric, polyester filament elastic fabric, non-woven fabric, various other non-woven fabrics, and various papers.

Preferably, the multilayer co-extruded resin layer with EVA resin as main component includes at least one foaming layer and one modifying layer.

Preferably, the base resin in the foaming layer is EVA, and the foaming layer comprises 100 parts of EVA resin, 1-15 parts of foaming agent, 0-4 parts of cross-linking agent, 0-100 parts of elastomer, 0-200 parts of filler, 0-10 parts of foaming promoter, 0-5 parts of lubricant and 0-20 parts of colorant.

Preferably, the foaming agent in the foaming layer can be a physical foaming agent, a chemical foaming agent and a microsphere foaming agent, and the physical foaming agent includes but is not limited to N₂、CO₂Pentane, hexane, trichlorotrifluoroethane, and the like. Chemical blowing agents include, but are not limited to, Azodicarbonamide (ADC), azobisisobutyronitrile, N-Dinitrosopentamethylenetetramine (DPT), 4-disulfonylhydrazide diphenyl ether (OBSH), p-benzenesulfonylhydrazide, and the like.

Preferably, the blowing agents are ADC blowing agents, OBSH blowing agents and microsphere blowing agents.

Preferably, the filler in the foaming layer is talcum powder, calcium carbonate, titanium dioxide and the like.

Preferably, the foaming aid is a metal oxide such as zinc oxide.

Preferably, the lubricant is stearic acid or zinc stearate, or the like.

Preferably, the elastomer includes rubber elastomers such as Natural Rubber (NR), Ethylene Propylene Diene Monomer (EPDM), hydrogenated styrene butadiene block copolymer (SEBS), styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), and polyolefin elastomers. Polyolefin elastomers such as ethylene-octene copolymers (POE) and the like.

Preferably, the crosslinking agent includes, but is not limited to, dicumyl peroxide, di-tert-butylperoxy-dicumyl peroxide, 1-bis (tert-butylperoxy) -3,3, 5-trimethylcyclohexane, 2, 5-di (tert-butylperoxy) -2, 5-dimethylhexane, or n-butyl 4, 4-di (tert-butylperoxy) valerate.

Preferably, the modified layer comprises 100 parts of EVA resin, 0-100 parts of elastomer, 0-200 parts of filler, 0-4 parts of crosslinking agent, 0-4 parts of auxiliary crosslinking agent and 0-20 parts of colorant. The modified layer is a modified layer with special performances such as adhesion, rebound resilience, wear resistance, flexibility and the like.

The polyurethane layer is closely attached to the modified layer, and the polyurethane layer can be a solvent type, water-based or solvent-free polyurethane coating.

Preferably, the polyurethane layer adopts an environment-friendly solvent-free or water-based polyurethane coating.

Preferably, the multi-layer co-extruded EVA resin layer is subjected to foaming and crosslinking treatment, the foaming multiplying power of the multi-layer co-extruded EVA resin layer is 1.2-10 times, the crosslinking degree is 3-95%, and the foaming and crosslinking treatment is free foaming and crosslinking through a crosslinking agent and/or radiation crosslinking treatment. The crosslinking agent can be used for crosslinking in the foaming process, the crosslinking agent can be not used for crosslinking in the foaming process, the crosslinking agent is used for radiation crosslinking after foaming, a certain crosslinking degree exists in the foaming process, and then the crosslinking degree is further improved through radiation crosslinking, or the crosslinking agent is used for radiation crosslinking before foaming.

Preferably, the total thickness of the synthetic leather is 0.21-5.3 mm, the thickness of the base layer is 0.1-2.2 mm, the thickness of the multi-layer co-extrusion foaming EVA resin layer is 0.1-3.0 mm, the thickness of the modified layer is 0.01-1.0 mm, the thickness of the polyurethane layer is 0.01-0.10 mm, and the thickness of each layer inside can be adjusted according to needs.

Detailed Description

In order to more clearly describe the technical contents of the present invention, the following further description is given in conjunction with specific embodiments.

Example 1

In this embodiment, the polyurethane layer in the synthetic leather foamed and crosslinked by the multi-layer co-extrusion EVA resin is a conventional solvent-free polyurethane slurry formula, the multi-layer co-extrusion EVA resin layer includes a foaming layer and a modification layer, wherein the foaming layer is in contact with the base fabric layer, and the raw material ratios of the foaming layer, the modification layer and the polyurethane layer slurry are respectively:

foaming layer

Ethylene vinyl acetate copolymer (EVA)100 parts

ADC foaming agent 1 part

Modified layer

Polyurethane layer

100 parts of solvent-free polyurethane prepolymer

66.5 parts of curing agent

Catalyst 1.7 parts

Wherein the isocyanate ester content of the polyurethane prepolymer is 2.3 percent, and the hydroxyl value of the curing agent is 40 mgKOH/g;

the invention also provides a preparation method of the multilayer co-extruded EVA resin foamed and crosslinked synthetic leather, which comprises the following steps:

1) preparing related raw materials of a foaming layer and a modification layer;

2) fully mixing the raw materials of the foaming layer and the modification layer, respectively adding the raw materials into an extruder, extruding the mixture to form a film, casting the film on a substrate, and rolling the film to form the film, wherein the thickness of the substrate layer is 0.1 mm;

3) foaming the multilayer co-extruded EVA resin in a high-temperature furnace, wherein the foaming temperature range is 100-230 ℃, the total thickness after foaming is 0.1mm, and the thickness of the modified layer is 0.01 mm;

4) and coating a polyurethane layer on the foamed multi-layer co-extruded EVA resin layer, wherein the thickness of the polyurethane layer is 0.01 mm.

Finally, the multilayer co-extruded EVA resin foamed and crosslinked synthetic leather is prepared by post-embossing and other treatments.

Example 2

In this embodiment, the ratio of the slurry for the polyurethane layer in the synthetic leather foamed and crosslinked by the multilayer co-extruded EVA resin is the same as that in embodiment 1, the multilayer co-extruded EVA resin layer includes a foaming layer and a modified layer, wherein the foaming layer is in contact with the base fabric layer, and the raw material ratios of the foaming layer and the modified layer are respectively:

foaming layer

Modified layer

The invention also provides a preparation method of the multilayer co-extruded EVA resin foamed and crosslinked synthetic leather, which comprises the following steps:

1) preparing related raw materials of a foaming layer and a modification layer;

2) fully mixing the raw materials of the foaming layer and the modification layer, respectively adding the raw materials into an extruder, extruding the mixture to form a film, casting the film on a substrate, and rolling the film to form the film, wherein the thickness of the substrate layer is 1.0 mm;

3) foaming the multilayer co-extruded EVA resin in a high-temperature furnace, wherein the foaming temperature range is 100-230 ℃, the total thickness after foaming is 1.0mm, and the thickness of the modified layer is 0.1 mm;

4) carrying out radiation crosslinking on the foamed multi-layer co-extruded EVA resin layer, wherein the radiation dose is 20 KGy;

5) and coating a polyurethane layer on the multi-layer co-extrusion EVA resin layer which is foamed and subjected to radiation crosslinking, wherein the thickness of the polyurethane layer is 0.05 mm.

Finally, the multilayer co-extruded EVA resin foamed and crosslinked synthetic leather is prepared by post-embossing and other treatments.

Example 3

In this embodiment, the ratio of the slurry for the polyurethane layer in the synthetic leather foamed and crosslinked by the multilayer co-extruded EVA resin is the same as that in embodiment 1, the multilayer co-extruded EVA resin layer includes a foaming layer and a modified layer, wherein the foaming layer is in contact with the base fabric layer, the ratio of the raw materials for the modified layer, the thickness of each layer, and the preparation method are the same as those in embodiment 2, and the ratio of the raw materials for the foaming layer is:

foaming layer

Example 4

In this embodiment, the ratio of the slurry for the polyurethane layer in the synthetic leather foamed and crosslinked by the multilayer co-extruded EVA resin is the same as that in embodiment 1, the multilayer co-extruded EVA resin layer includes a foaming layer and a modified layer, wherein the foaming layer is in contact with the base fabric layer, the ratio of the raw materials for the modified layer, the thickness of each layer, and the preparation method are the same as those in embodiment 2, and the ratio of the raw materials for the foaming layer is:

foaming layer

Example 5

In this embodiment, the ratio of the slurry for the polyurethane layer in the synthetic leather foamed and crosslinked by the multilayer co-extruded EVA resin is the same as that in embodiment 1, the multilayer co-extruded EVA resin layer includes a foaming layer and a modified layer, wherein the foaming layer is in contact with the base fabric layer, the ratio of the raw materials of the modified layer is the same as that in embodiment 2, and the ratio of the raw materials of the foaming layer is:

foaming layer

The invention also provides a preparation method of the multilayer co-extruded EVA resin foamed and crosslinked synthetic leather, which comprises the following steps:

1) preparing related raw materials of a foaming layer and a modification layer;

2) fully mixing the raw materials of the foaming layer and the modification layer, respectively adding the raw materials into an extruder, extruding the mixture to form a film, casting the film on a substrate, and rolling the film to form the film, wherein the thickness of the substrate layer is 2.2 mm;

3) foaming the multilayer co-extruded EVA resin in a high-temperature furnace, wherein the foaming temperature range is 100-230 ℃, the total thickness after foaming is 3.0mm, and the thickness of the modified layer is 1.0 mm;

4) carrying out radiation crosslinking on the foamed multi-layer co-extruded EVA resin layer, wherein the radiation dose is 90 KGy;

5) and coating a polyurethane layer on the multi-layer co-extrusion EVA resin layer which is foamed and subjected to radiation crosslinking, wherein the thickness of the polyurethane layer is 0.1 mm.

Finally, the multilayer co-extruded EVA resin foamed and crosslinked synthetic leather is prepared by post-embossing and other treatments.

Example 6

In this embodiment, the polyurethane layer in the synthetic leather foamed and crosslinked by the multi-layer co-extrusion EVA resin is a conventional aqueous polyurethane slurry formula, the multi-layer co-extrusion EVA resin layer includes a modified layer 1 (mainly playing a role of bonding with the base fabric layer), a foamed layer and a modified layer 2, wherein the modified layer 1 contacts with the base fabric layer, and the foaming layer, the modified layer and the polyurethane layer are prepared from the following raw materials in proportion:

modified layer 1

Ethylene vinyl acetate copolymer (EVA)100 parts

Foaming layer

Modified layer 2

Polyurethane layer

Wherein the water-based polyurethane is aliphatic polyurethane, and the solid content is 35 percent; the cross-linking agent is aziridine type;

the invention also provides a preparation method of the multilayer co-extruded EVA resin foamed and crosslinked synthetic leather, which comprises the following steps:

1) preparing related raw materials of a foaming layer and a modification layer;

2) fully mixing the raw materials of the foaming layer and the modification layer, respectively adding the raw materials into an extruder, extruding the mixture to form a film, casting the film on a substrate, and rolling the film to form the film, wherein the thickness of the substrate layer is 1.0 mm;

3) foaming the multilayer co-extruded EVA resin in a high-temperature furnace, wherein the foaming temperature range is 100-230 ℃, the total thickness after foaming is 1.0mm, the thickness of the modified layer 1 is 0.04mm, and the thickness of the modified layer 2 is 0.1 mm;

4) carrying out radiation crosslinking on the foamed multi-layer co-extruded EVA resin layer, wherein the radiation dose is 90 KGy;

5) and coating a polyurethane layer on the multi-layer co-extrusion EVA resin layer which is foamed and subjected to radiation crosslinking, wherein the thickness of the polyurethane layer is 0.05 mm.

Finally, the multilayer co-extruded EVA resin foamed and crosslinked synthetic leather is prepared by post-embossing and other treatments.

Example 7

In this embodiment, the ratio of the polyurethane layer slurry in the synthetic leather foamed and crosslinked by the multi-layer co-extrusion EVA resin is the same as that in embodiment 6, the thicknesses and the preparation methods of the modified layer 1, the modified layer 2 and the multi-layer co-extrusion EVA resin layer are the same as those in embodiment 6, only the formula of the modified layer 2 is adjusted, and the raw material ratio of the modified layer 2 is as follows:

modified layer 2

Example 8

In this embodiment, the ratio of the polyurethane layer slurry in the synthetic leather foamed and crosslinked by the multilayer co-extrusion EVA resin is the same as that in embodiment 6, the thicknesses of the modified layer 1, the modified layer 2 and the multilayer co-extrusion EVA resin layer are the same as those in embodiment 6, the foaming temperature in the preparation method is adjusted to 100-160 ℃, other preparation methods are the same as those in embodiment 6, the ADC foaming agent in the foaming layer is replaced by the OBSH foaming agent, and the raw material ratio of the foaming layer is as follows:

foaming layer

Example 9

In this embodiment, the ratio of the polyurethane layer slurry in the synthetic leather foamed and crosslinked by the multilayer co-extrusion EVA resin is the same as that in embodiment 6, the thicknesses of the modified layer 1, the modified layer 2 and the multilayer co-extrusion EVA resin layer are the same as those in embodiment 6, the foaming temperature in the preparation method is adjusted to 100 to 180 ℃, other preparation methods are the same as those in embodiment 6, the ADC foaming agent in the foaming layer is replaced by the microsphere foaming agent, and the raw material ratio of the foaming layer is as follows:

foaming layer

Example 10

In this embodiment, the polyurethane layer slurry ratio in the synthetic leather foamed and crosslinked by the multilayer co-extruded EVA resin is the same as that in embodiment 6, the multilayer co-extruded EVA resin layer includes a modified layer 1, a foamed layer 2 and a modified layer 2, wherein the modified layer 1 is in contact with the base fabric layer, and the raw material ratios of the foamed layer and the modified layer are respectively:

modified layer 1

Ethylene vinyl acetate copolymer (EVA)100 parts

Foaming layer 1

Ethylene vinyl acetate copolymer (EVA)100 parts

ADC foaming agent 1 part

0.2 part of cross-linking agent

Foaming layer 2

Modified layer 2

The invention also provides a preparation method of the multilayer co-extruded EVA resin foamed and crosslinked synthetic leather, which comprises the following steps:

1) preparing related raw materials of a foaming layer and a modification layer;

2) fully mixing the raw materials of the foaming layer and the modification layer, respectively adding the raw materials into an extruder, extruding the mixture to form a film, casting the film on a substrate, and rolling the film to form the film, wherein the thickness of the substrate layer is 1.0 mm;

3) foaming the multilayer co-extruded EVA resin in a high-temperature furnace, wherein the foaming temperature range is 100-230 ℃, the total thickness after foaming is 1.0mm, the thickness of the modified layer 1 is 0.04mm, and the thickness of the modified layer 2 is 0.1 mm;

4) carrying out radiation crosslinking on the foamed multi-layer co-extruded EVA resin layer, wherein the radiation dose is 90 KGy;

5) and coating a polyurethane layer on the multi-layer co-extrusion EVA resin layer which is foamed and subjected to radiation crosslinking, wherein the thickness of the polyurethane layer is 0.05 mm.

Finally, the multilayer co-extruded EVA resin foamed and crosslinked synthetic leather is prepared by post-embossing and other treatments.

Example 11

In this embodiment, the polyurethane layer slurry ratio in the synthetic leather foamed and crosslinked by the multilayer co-extruded EVA resin is the same as that in embodiment 6, the multilayer co-extruded EVA resin layer includes a modified layer 1, a foamed layer 1, a modified layer 2, a foamed layer 2 and a modified layer 3, wherein the modified layer 1 is in contact with the base fabric layer, and the foaming layer and the modified layer are prepared from the following raw materials in proportion:

modified layer 1

Ethylene vinyl acetate copolymer (EVA)100 parts

Foamed layers 1 and 2

Modified layers 2 and 3

The invention also provides a preparation method of the multilayer co-extruded EVA resin foamed and crosslinked synthetic leather, which comprises the following steps:

1) preparing related raw materials of a foaming layer and a modification layer;

2) fully mixing the raw materials of the foaming layer and the modification layer, respectively adding the raw materials into an extruder, extruding the mixture to form a film, casting the film on a substrate, and rolling the film to form the film, wherein the thickness of the substrate layer is 1.0 mm;

3) foaming the multilayer co-extruded EVA resin in a high-temperature furnace, wherein the foaming temperature range is 100-230 ℃, the total thickness after foaming is 1.5mm, the thickness of the modified layer 1 is 0.04mm, and the thicknesses of the modified layers 2 and 3 are respectively 0.1 mm;

4) carrying out radiation crosslinking on the foamed multi-layer co-extruded EVA resin layer, wherein the radiation dose is 90 KGy;

5) and coating a polyurethane layer on the multi-layer co-extrusion EVA resin layer which is foamed and subjected to radiation crosslinking, wherein the thickness of the polyurethane layer is 0.05 mm.

Finally, the multilayer co-extruded EVA resin foamed and crosslinked synthetic leather is prepared by post-embossing and other treatments.

Comparative example 1

The layer formulations and preparation were the same as in example 2, except that no foaming was present.

Comparative example 2

The layer formulations and preparation were the same as in example 6, except that no foaming was present.

The adhesive force between the base layer and the multi-layer co-extruded EVA resin layer in the multi-layer co-extruded EVA resin foamed and cross-linked synthetic leather prepared in examples 1 to 11 and comparative examples 1 and 2, the cross-linking degree and shore hardness of the multi-layer co-extruded EVA resin layer, and the wear resistance data of the synthetic leather are shown in the following table one: the interlayer adhesion force is tested according to GB/T14905-2009, the crosslinking degree of the EVA layer is tested according to GB/T29848-2018-5.5.3 xylene extraction method, the abrasion resistance is tested according to ASTM D1242-1995, and the Shore hardness is tested according to GB/T2411-2008.

Table-performance parameter table of multi-layer co-extruded EVA resin foamed and cross-linked synthetic leather

Note: in the examples, the expansion ratios of all samples were controlled in the range of 2 to 2.5 times.

As can be seen from the performance data of the synthetic leather foamed and crosslinked by the multilayer co-extruded EVA resin shown in the table, the crosslinking degree of the foamed EVA resin layer can be adjusted by adjusting the amount of the crosslinking agent, the radiation dose and the foaming time by adopting the synthetic leather foamed and crosslinked by the multilayer co-extruded EVA resin prepared by the invention.

In this specification, the invention has been described with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention. The description is thus to be regarded as illustrative instead of limiting.