WO2020143686A1

WO2020143686A1 - Ethylene-vinyl acetate synthetic leather substrate, ethylene-vinyl acetate synthetic leather, and surface grafting treatment agent for ethylene-vinyl acetate synthetic leather

Info

Publication number: WO2020143686A1
Application number: PCT/CN2020/070979
Authority: WO
Inventors: 李民; 李庆北; 蔡相成
Original assignee: 上海海优威应用材料技术有限公司
Priority date: 2019-01-09
Filing date: 2020-01-08
Publication date: 2020-07-16

Abstract

Disclosed are an ethylene-vinyl acetate (EVA) synthetic leather substrate, an EVA synthetic leather, and a surface grafting treatment agent for the EVA synthetic leather. The EVA synthetic leather substrate comprises a radiation crosslinking EVA layer and a base layer. No hazardous chemicals such as a phthalate plasticizer and an organic solvent are used in the production process in the present application to eliminate organic contamination from the source, and performances such as good pattern retention, resilience, flexibility, temperature resistance, and aging resistance are provided after performing radiation crosslinking.

Description

Ethylene-vinyl acetate copolymer synthetic leather base material, ethylene-vinyl acetate copolymer synthetic leather and surface grafting treatment agent for ethylene-vinyl acetate copolymer synthetic leather

Cross-reference of related applications

This application claims the priority of the Chinese patent application 201910018270.8 entitled "New Synthetic Leather Base Material and Corresponding Preparation Method and Synthetic Leather" filed on January 9, 2019. The entire contents of this application are incorporated herein by reference.

This application claims the priority of the Chinese patent application 201910125306.2 entitled "Surface Treatment Agent for EVA Synthetic Leather, EVA Synthetic Leather and Preparation Method" filed on February 20, 2019. The entire content of this application is incorporated by reference Incorporated in this article.

This application requires the priority of the Chinese patent application 201910125326.X entitled "Environmentally Friendly Surface Grafted EVA Synthetic Leather and its Preparation Method" filed on February 20, 2019. The entire content of this application is incorporated by reference and Into this article.

This application claims the priority of the Chinese patent application 201920214936.2 entitled "New Synthetic Leather Structure" filed on February 20, 2019, the entire contents of which are incorporated herein by reference.

This application claims the priority of the Chinese patent application 201920227380.0 entitled "New EVA Synthetic Leather Structure" filed on February 20, 2019, the entire content of which is incorporated herein by reference.

This application claims the priority of the Chinese patent application 201910547678.4 filed on June 24, 2019, entitled "Environmentally Friendly EVA Fill Paper", the entire content of which is incorporated herein by reference.

This application claims the priority of Chinese patent application 201911012102.4 entitled "Multilayer Coextruded EVA Resin Foamed and Crosslinked Synthetic Leather" filed on October 23, 2019. The entire contents of this application are incorporated herein by reference in.

Technical field

This application relates to the technical field of synthetic leather, in particular to an ethylene-vinyl acetate copolymer (EVA) synthetic leather substrate, EVA synthetic leather, and a surface grafting treatment agent for EVA synthetic leather.

Background technique

With the improvement of people's living standards, people are gradually pursuing high-quality daily necessities, and the demand for leather products is increasing. At present, synthetic leather products have gradually become a popular trend in the future, and have been widely used in the production of luggage, clothing, footwear, furniture, sports goods and other fields. The synthetic leather industry has become a pillar industry in the light industry.

At present, the production and processing of the entire synthetic leather industry are mostly based on polyurethane (PU) or polyvinyl chloride (PVC) as the main layer. In the production process, a large number of organic solvents and plasticizers such as dimethylformamide, methyl ethyl ketone, Acetone, toluene, ethyl acetate, o-benzene plasticizers, etc., these materials are extremely harmful to the human body or the environment.

General PVC synthetic leather will become very hard when the temperature is low, and the ability to absorb heat is insufficient. It is easy to crack at a low temperature for a long time, resulting in a short service life. PVC synthetic leather itself is a non-toxic material, but the residual vinyl chloride monomer in the synthetic leather and the additives used in processing (especially plasticizers) have certain toxicity. Not only contact with human skin will cause health The impact of the above, and such toxic products can not be recycled and reused, is a major killer of environmental pollution. Therefore, my country has included "PVC general synthetic leather production line" as a restricted development project, and countries such as Europe, America, Japan and other "green barriers" have also greatly restricted the consumption of PVC synthetic leather.

Generally, the solid content of polyurethane for synthetic leather is about 30%, and the amount of organic solvent is up to 70%, and a certain amount of organic solvent will be added during the processing of synthetic leather, so the amount of organic solvent used in actual production is very large. Solvents that cannot be recovered in production are discharged into the environment in the form of gas and waste water, causing great harm to the environment and human bodies.

Using waterborne polyurethane to replace traditional solvent-based polyurethane is an effective way to eliminate organic solvent pollution from the source and improve the ecological grade of synthetic leather. However, the coating made by water-based polyurethane wet film formation is relatively thin, and a large amount of heat energy is required to evaporate water, and the water resistance of water-based polyurethane synthetic leather is relatively poor. At the same time, its wear resistance can only be relatively relative due to molecular weight. Poor condition; more critically, the cost of its materials is relatively high, and the production and manufacturing are more difficult, which greatly limits the development of water-based synthetic leather.

In recent years, solvent-free polyurethane synthetic leather has developed rapidly, but due to the application of thick-coated reactive polyurethane, whether it is the production process cost, the stability of the process, and the cost of the material itself, it is greatly limited. Widely used.

There are few reports on the application of polyolefin materials to synthetic leather. At present, the modified polyolefin synthetic leather mainly based on SEBS, but it has the disadvantages of complicated preparation process and too high cost, so it cannot be popularized.

Therefore, looking for a more environmentally friendly and low-cost raw material to replace PU, PVC and SEBS synthetic leather has become a research hotspot.

Summary of the invention

A first aspect of the present application provides an ethylene-vinyl acetate copolymer (EVA) synthetic leather substrate, which includes a radiation-crosslinked ethylene-vinyl acetate copolymer (EVA) layer and a base layer.

The inventor found that EVA resin is a rubber-like thermoplastic, which has excellent flexibility, low-temperature flexibility, resilience, stress crack resistance, aging resistance, and good plasticity, workability and other properties. In the EVA molecule, due to the presence of vinyl acetate (VA) structural units, the regularity of the polyethylene molecular chain is greatly reduced, and its crystallinity is also reduced, so that the molecular chain has a great ability to rotate within the thermal motion. The improvement of the molecular chain, the flexibility of the molecular chain is improved, and the macroscopic performance is very high elasticity. In particular, the radiation-crosslinked EVA layer has good properties such as resilience, flexibility, temperature resistance and aging resistance, so that the synthetic leather substrate and the synthetic leather using the synthetic leather substrate can obtain corresponding beneficial effects . More preferably, the embossed synthetic leather contains a radiation-crosslinked EVA layer, and better pattern retention can also be obtained.

An exemplary test method for pattern retention may include: placing the embossed synthetic leather under normal pressure, a temperature of 85°C, and a humidity of 85% for 168 hours, and observing whether the pattern can be maintained.

The synthetic leather substrate of the present application also has the advantages of low cost and simple manufacturing process. In particular, the production process of the synthetic leather substrate does not use o-benzene plasticizers, organic solvents and other harmful chemicals, eliminating organic pollution from the source, while greatly reducing energy consumption. Therefore, the synthetic leather substrate also has the advantage of being environmentally friendly.

In the embodiment of the first aspect of the present application, the EVA content of the raw material EVA used in the EVA layer may be 9% to 40%, preferably 15% to 37%, more preferably 18% to 28%; wherein, the VA content It is based on the percentage of mass. The use of EVA with appropriate VA content can improve the processing performance of the EVA layer, especially the EVA layer after radiation crosslinking has higher wear resistance, but also has better flexibility and resilience, making synthetic leather It feels better and has a longer service life.

In the embodiment of the first aspect of the present application, the raw material EVA used in the EVA layer may have a melt flow rate of 0.9 g/10 min to 65 g/10 min at 190° C. and a load of 2.16 kg, preferably 2.5 g/10 min to 15 g /10 min, more preferably 2.5 g/10 min to 6 g/10 min. In this application, the melt flow rate can be measured with reference to the standard ISO 1133-1-2011, using a melt flow rate instrument, such as the RL-11B1 melt flow rate instrument of Shanghai Xiangjie Instrument Technology Co., Ltd. The melt flow rate of EVA is in an appropriate range, which is conducive to making the synthetic leather have good softness and resilience, and also has high strength and wear resistance.

Preferably, the raw material EVA used in the EVA layer simultaneously satisfies a VA content of 15% to 37% and a melt flow rate of 190°C and a load of 2.16 kg of 2.5 g/10min to 6 g/10min. This can better improve the performance of synthetic leather.

In the embodiment of the first aspect of the present application, the raw material of the EVA layer may further include one or more of a cross-linking aid, an antioxidant, and a colorant.

In the embodiment of the first aspect of the present application, the thickness of the EVA layer may be 0.1 mm to 3.0 mm. Preferably, the thickness of the EVA layer may be 0.25 mm to 2.0 mm.

In the embodiment of the first aspect of the present application, radiation is but not limited to high-energy electron beams, gamma rays, X-rays, and the like. The radiation dose may be 5KGY-200KGY, preferably 20KGY-150KGY, more preferably 80KGY-120KGY, such as 100KGY. By setting the radiation dose in an appropriate range, the EVA layer after radiation cross-linking can have an appropriate degree of cross-linking, which can make the synthetic leather have higher wear resistance and temperature resistance, and also have better recovery. Elasticity and softness. In particular, the proper radiation dose can also improve the pattern retention of embossed synthetic leather.

In an embodiment of the first aspect of the present application, the base layer is a paper base or base cloth. When the base layer is a base fabric, the base fabric is any one of knitted elastic fleece, plain woven fleece, knitted plain fabric, polyester filament elastic fabric, non-woven fabric, woven polyester fabric, nylon fabric and microfiber base fabric Species or a combination of at least two.

In the embodiment of the first aspect of the present application, the EVA synthetic leather substrate can be prepared by casting a raw material including EVA to the base layer and then radiation crosslinking.

Through radiation crosslinking, chemical bonds and other bonding points are formed between long polymer chains, which improves the physical and chemical properties of the polymer. During radiation crosslinking, the polymer itself has no physical contact with the radiation generating device, and the shape of the polymer has not changed before and after the reaction, but a crosslinking reaction has occurred inside. The polymer product can be directly placed in the radiation to cause cross-linking reaction, or a cross-linking aid can be added to the polymer to promote the efficiency of radiation cross-linking.

In the embodiment of the first aspect of the present application, the preparation method of the EVA synthetic leather substrate may include the following steps:

Prepare raw materials for EVA layer;

After the raw materials are fully mixed, it is added to the extruder, extruded into a film, cast onto the base layer, flattened and rolled up;

Radiation cross-linking to obtain EVA synthetic leather substrate.

In the embodiment of the first aspect of the present application, the preparation method may further include other processing steps, and the other processing steps may include one or more of surface modification, grafting, color change, surface treatment, kneading, and embossing. Other processing procedures may not limit the order. Radiation cross-linking and other processing steps may not be restricted in order. For example, the embossing treatment may be performed after radiation crosslinking or before radiation crosslinking. The inventor found that embossing the EVA synthetic leather first and then performing radiation crosslinking can further improve the pattern retention of the embossed synthetic leather.

A second aspect of the present application provides an ethylene-vinyl acetate copolymer (EVA) synthetic leather, which includes the EVA synthetic leather substrate according to the first aspect of the present application.

In the embodiment of the second aspect of the present application, the EVA synthetic leather may be shoe upper leather, luggage leather, sofa leather, or home decoration leather.

In an embodiment of the second aspect of the present application, the EVA synthetic leather may include a base fabric, a radiation-crosslinked EVA layer, and a polyurethane layer in this order from bottom to top.

The EVA synthetic leather of the present application includes a radiation-crosslinked EVA layer. The raw material EVA used is a rubber-like thermoplastic, which has excellent flexibility, low-temperature flexibility, elasticity, stress crack resistance, and good plasticity. Workability, etc. After radiation crosslinking, the comprehensive physical properties of EVA are greatly improved, such as pattern retention, resilience, flexibility, aging resistance, temperature resistance and solvent resistance. In the EVA synthetic leather, the radiation cross-linked EVA layer has high bonding strength with the base fabric. In particular, the EVA synthetic leather also includes a polyurethane layer, which makes it have excellent comprehensive properties such as good wear resistance, environmental protection, non-toxicity, and comfortable feel.

In addition, the EVA synthetic leather has the advantages of simple manufacturing process and low production cost.

In an embodiment of the second aspect of the present application, the EVA synthetic leather may be a three-layer structure composed of a base fabric, a radiation cross-linked EVA layer, and a polyurethane layer.

In the embodiment of the second aspect of the present application, the total thickness of the EVA synthetic leather may be 0.5 mm to 5.5 mm. Optionally, the total thickness of the three-layer structure composed of the base fabric, the radiation-crosslinked EVA layer, and the polyurethane layer may be 0.5 mm to 5.5 mm, preferably 0.7 mm to 4.0 mm.

In the embodiment of the second aspect of the present application, the thickness of the base fabric may be 0.3 mm to 2.2 mm, preferably 0.44 mm to 1.8 mm.

In an embodiment of the second aspect of the present application, the thickness of the radiation-crosslinked EVA layer may be 0.2 mm to 3.0 mm, preferably 0.25 mm to 2.0 mm.

In the embodiment of the second aspect of the present application, the thickness of the polyurethane layer may be 0.005 mm to 0.3 mm, preferably 0.01 mm to 0.2 mm.

In an embodiment of the second aspect of the present application, the EVA synthetic leather includes a paper base, a radiation cross-linked EVA layer, and a polyurethane layer.

The EVA synthetic leather is leather-filled paper. Among them, the EVA layer is used as the base material layer, which has better embossing property and high texture simulation degree than PU filling leather paper, strong cortex feeling, can be folded at will, beautiful gloss, high grade and good wear resistance. The production process is simple and environmentally friendly, the cost is low, and the radiation-crosslinked EVA layer has excellent resilience, flexibility, aging resistance, temperature resistance and solvent resistance, and no peroxide crosslinking agent is used in the EVA layer.

In an embodiment of the second aspect of the present application, the total thickness of the EVA synthetic leather may be 0.15 mm to 0.55 mm, wherein the thickness of the paper base may be 0.10 mm to 0.25 mm, and the thickness of the EVA layer may be 0.04 mm to 0.25 mm. The thickness of the polyurethane layer may be 0.01 mm to 0.05 mm.

In the embodiment of the second aspect of the present application, the basis weight of the paper base may be 80 g/m ² to 200 g/m ² . The paper is completely translucent, the color is saturated and bright, not easy to fade, the paper is soft, good toughness, good tear resistance, scratch resistance, easy to glue, easy to fit.

In an embodiment of the second aspect of the present application, the EVA layer includes 100 parts of the EVA resin, 0 to 100 parts of the polyolefin resin, 0 to 6 parts of the cross-linking aid, 0 to 200 parts of the filler, and 0 to 20 parts of the colorant. In this context, parts are parts by weight.

In an embodiment of the second aspect of the present application, the polyolefin resin may be ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, etc. Alpha-olefin and some cyclic olefins are prepared by single polymerization or copolymerization. Preferably, the polyolefin resin may include one or a combination of two or more of ethylene-octene copolymer, ethylene-butene copolymer and polyethylene. More preferably, the polyolefin resin may include one or a combination of two or more of ethylene-octene copolymer and ethylene-butene copolymer. Adding appropriate polyolefin resin to the EVA layer can make the synthetic leather have higher abrasion resistance, and further improve the flexibility and embossability of the synthetic leather.

In the embodiment of the second aspect of the present application, the filler may be calcium carbonate, limestone, white carbon, talc, or the like, or a combination of two or more.

In an embodiment of the second aspect of the present application, the degree of crosslinking of the EVA layer after radiation crosslinking is 1% to 90%, preferably 1% to 70%, more preferably 45% to 55%, such as 46% to 52 %. The EVA layer has an appropriate degree of radiation crosslinking, which can make the synthetic leather have higher wear resistance and further improve the synthetic leather pattern retention.

In an embodiment of the second aspect of the present application, the polyurethane layer includes functional improvements such as changing color, adjusting gloss, improving hand feel, improving temperature resistance and anti-sticking performance.

In an embodiment of the second aspect of the present application, the EVA synthetic leather is a multi-layer co-extruded EVA resin foamed and cross-linked synthetic leather. The synthetic leather includes a polyurethane layer, a multi-layer co-extruded EVA layer and A base layer laminated on the EVA layer, the multi-layer co-extruded EVA layer is foamed and cross-linked, and includes at least one modified layer and at least one foamed layer, and the polyurethane layer closely adheres to the modified layer .

The inventor found that by foaming the EVA material or/and adding a rubber elastomer or a polyolefin elastomer for modification, the hardness of the EVA material can be reduced. When foaming EVA using the existing technology, the foamed layer may have a certain thermal crosslinking, but the crosslinking degree is too low, which leads to problems such as cell collapse and poor temperature resistance in actual use. This application uses a multi-layer co-extruded EVA layer that is foamed and cross-linked and includes at least one modified layer and at least one foamed layer to improve the hardness of the synthetic leather, especially after cross-linking. Excellent temperature resistance, soft and good resilience, excellent aging resistance and solvent resistance, while suppressing cell collapse. More preferably, the synthetic leather can also have light weight, excellent flex resistance, and high shock absorption, sound insulation and heat insulation properties. It also includes a polyurethane layer, which makes the synthetic leather have excellent comprehensive properties such as good wear resistance, environmental protection, non-toxicity, and comfortable feel.

The synthetic leather can be, but not limited to, used in sports equipment, seat cushions, sports shoes, luggage pads, etc.

The EVA layer adopts multi-layer co-extrusion method, the production process is simple, the interlayer adhesion between the base layer and the multi-layer co-extrusion EVA layer is good, and the interlayer adhesion can reach more than 5N/cm.

In an embodiment of the second aspect of the present application, the foam layer contains 100 parts of EVA resin, 1 to 15 parts of foaming agent, 0 to 4 parts of crosslinking agent, 0 to 100 parts of elastomer, 0 to 200 Parts of filler, 0-10 parts of foaming accelerator, 0-5 parts of lubricant, 0-20 parts of colorant. The foam layer is modified by adding an elastomer (such as rubber elastomer, polyolefin elastomer, etc.), which can further improve the flexibility and resilience of synthetic leather. Preferably, the foam layer may contain 50 to 100 parts of elastomer.

In an embodiment of the second aspect of the present application, the foaming agent in the foaming layer may be selected from physical foaming agents, chemical foaming agents, and microsphere foaming agents. Physical foaming agents include but are not limited to N ₂ , CO _2. Pentane, hexane, trichlorotrifluoroethane, etc. Chemical blowing agents include, but are not limited to, azodicarbonamide (ADC), azobisisobutyronitrile, N,N-dinitrosopentamethylenetetramine (DPT), 4,4-disulfonyl hydrazide Diphenyl ether (OBSH), p-benzenesulfonyl hydrazide and other blowing agents. Preferably, the foaming agent includes one or more of ADC foaming agent, OBSH foaming agent and microsphere foaming agent.

In the embodiment of the second aspect of the present application, the filler in the foam layer may be selected from talc, calcium carbonate, titanium dioxide, and the like.

In an embodiment of the second aspect of the present application, the foaming aid may include metal oxides such as zinc oxide.

In the embodiment of the second aspect of the present application, the lubricant may be selected from stearic acid, zinc stearate, and the like.

In an embodiment of the second aspect of the present application, the elastomer may include a rubber elastomer and a polyolefin elastomer. Rubber elastomers such as natural rubber (NR), EPDM (EPDM), hydrogenated styrene butadiene block copolymer (SEBS), styrene-butadiene-styrene block copolymer (SBS), Styrene-isoprene-styrene block copolymer (SIS) and the like preferably include ethylene propylene diene rubber (EPDM). Polyolefin elastomers such as ethylene-octene copolymer (POE) and the like.

In the embodiment of the second aspect of the present application, the cross-linking agent includes but is not limited to dicumyl peroxide, di-tert-butyl dicumyl peroxide, 1,1-bis(tert-butylperoxy)-3 , 3,5-trimethylcyclohexane, 2,5-di(tert-butylperoxy)-2,5-dimethylhexane and 4,4-di(tert-butylperoxy)valerate One or more butyl esters.

In the embodiment of the second aspect of the present application, the modified layer contains 100 parts of EVA resin, 0 to 100 parts of elastomer, 0 to 200 parts of filler, 0 to 4 parts of crosslinking agent, 0 to 4 Parts of cross-linking agent, 0-20 parts of colorant. The modified layer is a modified layer with special properties such as adhesion, resilience, abrasion resistance, and flexibility. The modified layer is modified by adding an elastomer, which can further improve the softness and resilience of the synthetic leather. Preferably, the modified layer may contain 60 to 100 parts of elastomer. The elastomer may be the aforementioned elastomer.

In an embodiment of the second aspect of the present application, the polyurethane layer may be a solvent-based, water-based or solvent-free polyurethane coating. Preferably, the polyurethane layer may adopt an environmentally friendly solvent-free or water-based polyurethane coating.

In the embodiment of the second aspect of the present application, the degree of crosslinking of the EVA layer is 3% to 95%.

In the embodiment of the second aspect of the present application, the foaming and cross-linking treatment is foaming through radiation cross-linking treatment or radiation cross-linking treatment after foaming.

Optionally, the multi-layer co-extruded EVA layer is foamed and cross-linked. The multi-layer co-extruded EVA layer has a foaming ratio of 1.2 to 10 times and a cross-linking degree of 3% to 95%. It is foamed and cross-linked For free foaming and cross-linking treatment by radiation. In the foaming process, the crosslinking agent can be used for crosslinking without crosslinking agent, but after the foaming, there is a certain degree of crosslinking, and then the crosslinking degree can be further improved by radiation crosslinking, or the crosslinking can be performed with radiation first. Foam after connecting.

In an embodiment of the second aspect of the present application, optionally, the synthetic leather may include a modified layer between the base layer and the foam layer, and a modified layer between the foam layer and the polyurethane layer. As an example, the synthetic leather may include a first modified layer formed on the base layer, at least one foam layer formed on the first modified layer, and a foam layer formed in at least one foam layer relatively far from the base layer The second modified layer on the foam layer and the polyurethane layer formed on the second modified layer. As another example, the synthetic leather may include at least two modified layers and at least one foamed layer formed on the base layer and arranged alternately, one of the at least two modified layers being bonded to the base layer, at least two The other of the modified layers is bonded to the polyurethane layer. There is a modified layer between the base layer and the foam layer, which can further improve the interlayer adhesion of the synthetic leather.

In the embodiment of the second aspect of the present application, optionally, the total thickness of the synthetic leather is 0.21 mm to 5.3 mm, the thickness of the base layer is 0.1 mm to 2.2 mm, and the thickness of the multi-layer co-extruded EVA layer is 0.1 mm to 3.0 mm, wherein the thickness of the modified layer is 0.01 mm to 1.0 mm, and the thickness of the polyurethane layer is 0.01 mm to 0.10 mm. The thickness of each layer can be adjusted as required.

In an embodiment of the second aspect of the present application, the EVA synthetic leather may include a base fabric, a radiation-crosslinked EVA layer, a surface graft treatment layer, and a polyurethane layer in this order from bottom to top.

The EVA synthetic leather of the present application includes a radiation-crosslinked EVA layer. EVA is a rubber-like thermoplastic with excellent flexibility, low-temperature flexibility, elasticity, stress crack resistance, and good plasticity and machinability. After radiation crosslinking, the comprehensive physical properties of EVA are greatly improved, such as resilience, aging resistance, temperature resistance and solvent resistance. The EVA synthetic leather also includes a polyurethane layer, which makes it have excellent comprehensive properties such as good wear resistance, scratch resistance, environmental protection, non-toxicity, and comfortable feel. The radiation cross-linked EVA layer has a high bonding strength with the base fabric. Coating the grafting treatment layer on the surface of the EVA layer can further enhance the adhesion between the polyurethane layer and the EVA layer.

In the embodiment of the second aspect of the present application, the EVA synthetic leather has a four-layer structure composed of a base fabric, a radiation-crosslinked EVA layer, a surface graft treatment layer, and a polyurethane layer.

In the embodiment of the second aspect of the present application, the total thickness of the EVA synthetic leather may be 0.5 mm to 5.5 mm. Further, the total thickness of EVA synthetic leather may be 0.7 mm to 4.0 mm.

In the embodiment of the second aspect of the present application, the thickness of the base fabric may be 0.3 mm to 2.2 mm. Further, the thickness of the base cloth may be 0.44 mm to 1.8 mm.

In an embodiment of the second aspect of the present application, the thickness of the radiation-crosslinked EVA layer may be 0.19 mm to 3.0 mm. Further, the thickness of the radiation-crosslinked EVA layer may be 0.25 mm to 2.0 mm.

In an embodiment of the second aspect of the present application, the thickness of the surface graft treatment layer may be 0.005 mm to 0.04 mm. Further, the thickness of the surface graft treatment layer may be 0.01 mm to 0.02 mm.

In an embodiment of the second aspect of the present application, the thickness of the polyurethane layer may be 0.005 mm to 0.26 mm. Further, the thickness of the polyurethane layer may be 0.01 mm to 0.18 mm.

In an embodiment of the second aspect of the present application, the content of EVA in the EVA layer is greater than 50 wt%. Others may include one or more combinations of modifiers such as crosslinking agents, antioxidants, colorants, flame retardants, mold release agents, flame retardants, fillers and the like.

In an embodiment of the second aspect of the present application, the degree of crosslinking of the EVA layer after radiation crosslinking is greater than 20%. The degree of crosslinking of the EVA layer can be adjusted by the amount of crosslinking agent or the radiation dose.

In an embodiment of the second aspect of the present application, the surface graft treatment layer is formed of an aqueous or solvent-free polyurethane surface graft treatment agent.

In an embodiment of the second aspect of the present application, the surface grafting treatment layer is formed of a solventless polyurethane surface grafting treatment agent, and the solventless surface grafting treatment agent host resin may include an isocyanate-terminated polyether One or more of the type polyurethane prepolymer and the polyester type polyurethane prepolymer whose terminal group is isocyanate. Preferably, the main resin of the solventless surface grafting treatment agent is a polyether polyurethane prepolymer having an isocyanate terminal group.

Further, the solvent-free polyurethane surface grafting treatment agent may include 36 wt% to 80 wt% polyurethane prepolymer with isocyanate end groups, 14 wt% to 58 wt% polyol prepolymer with hydroxyl end groups, 0.1 wt % Dibutyltin dilaurate catalyst, 0.5 wt% leveling agent, 0.5 wt% wetting viscosity reducer and 4.9 wt% plasticizer.

In an embodiment of the second aspect of the present application, the surface grafting treatment layer is formed of an aqueous polyurethane surface grafting treatment agent, and the host resin of the aqueous surface grafting treatment agent may include an aqueous polyurethane having a hydroxyl group at the end and a carboxyl group at the end One or more of the water-based polyurethane and the water-based polyurethane with an amino group as the end group. Preferably, the host resin of the aqueous surface grafting treatment agent is an aqueous polyurethane having a hydroxyl group at the end.

Further, the waterborne polyurethane surface grafting treatment agent may include 40 wt% to 70 wt% of waterborne polyurethane with hydroxyl end groups, 2 wt% to 7 wt% of prepolymer crosslinking agent with isocyanate ends, 21.8 wt% to 56.8 wt % Water, 0.3 wt% thickener, 0.3 wt% wetting agent, 0.1 wt% defoamer and 0.5 wt% film-forming agent.

In an embodiment of the second aspect of the present application, the host resin of the polyurethane layer may be water-based polyurethane or solvent-free polyurethane.

In an embodiment of the second aspect of the present application, the thickness of the surface graft treatment layer may be 5 μm-40 μm.

In an embodiment of the second aspect of the present application, the thickness of the polyurethane layer may be 15 μm to 100 μm.

In an embodiment of the second aspect of the present application, the preparation method of EVA synthetic leather may include: casting an EVA-based resin raw material onto a base fabric, and producing an environmentally friendly EVA synthetic leather substrate through radiation crosslinking; Before the surface of the EVA synthetic leather substrate, a layer of environmentally friendly surface grafting treatment agent is applied; the surface of the grafting treatment layer is coated with polyurethane slurry, and after drying and aging, high adhesion strength, wear resistance and scratch resistance can be obtained Environmentally friendly EVA synthetic leather with better physical properties.

The EVA synthetic leather of the present application has the advantages of simple manufacturing process and low production cost. The EVA synthetic leather does not use environmentally friendly organic solvents and other harmful chemicals in the production process of EVA raw material casting film formation, surface grafting treatment, coating polyurethane layer, etc., eliminating organic pollution from the source.

In an embodiment of the second aspect of the present application, the preparation method of EVA synthetic leather may include the following steps:

Prepare relevant raw materials for EVA layer;

After the raw materials are fully mixed, it is added to the extruder, extruded into a film, cast onto the base fabric, and EVA synthetic leather substrate is prepared by radiation crosslinking;

The surface of the EVA synthetic leather substrate is treated with an environmentally friendly surface grafting treatment agent, and the film is formed by net transfer printing or roll coating, and then one of heating pre-crosslinking, cooling, coating, curing or peeling the film and A combination of various processes to form a surface grafting treatment layer;

The surface of the surface grafting treatment layer is coated with polyurethane slurry, and after drying and aging, an environmentally friendly EVA synthetic leather with high bonding strength and better wear resistance and scratch resistance is prepared.

In an embodiment of the second aspect of the present application, the surface grafting treatment layer is formed of a surface grafting treatment agent, and the surface grafting treatment agent includes 50 wt% to 82.4 wt% of a polyurethane prepolymer containing reactive groups at the end groups, 2.5wt% ~ 15wt% curing agent, 5wt% ~ 15wt% dimethylformamide, 10wt% ~ 19wt% butanone and 0.1wt% ~ 1wt% dibutyltin dilaurate catalyst. The EVA synthetic leather of the present application uses the surface grafting treatment agent to form a graft layer with strong adhesion on the surface of polyurethane. The surface of the grafting layer is then coated or treated to produce an EVA synthetic leather with high bonding strength and further improved physical properties such as wear resistance and scratch resistance.

In an embodiment of the second aspect of the present application, the active group in the polyurethane prepolymer having an active group at the end group is one or more of a hydroxyl group, an amino group, and a carboxyl group, preferably a hydroxyl group.

In the embodiment of the second aspect of the present application, the curing agent is a curing agent whose terminal group is a carboxyl group or an isocyanate. Preferably, the curing agent is an isocyanate-terminated curing agent. Further, the functionality of the isocyanate curing agent is 1.5 to 3.5, preferably 2.5 to 3.0.

In an embodiment of the second aspect of the present application, the content of the polyurethane prepolymer containing reactive groups at the end groups may be 60 wt% to 70 wt%.

In the embodiment of the second aspect of the present application, the content of the curing agent may be 5 wt% to 10 wt%.

In an embodiment of the second aspect of the present application, the thickness of the surface graft treatment layer may be 5 μm to 40 μm, preferably 10 μm to 25 μm.

1) Weigh according to the formula design of surface grafting treatment agent;

2) Mix the above-mentioned raw material polyurethane prepolymer, dimethylformamide (DMF) and methyl ethyl ketone (MEK) solvent and catalyst in advance, and then add the curing agent in batches in proportion to stir well;

3) The mixed paste is attached to the surface of the EVA synthetic leather substrate by means of net transfer printing or roller coating, and is dried to form a surface adhesion treatment layer with strong adhesion of polyurethane;

4) The surface grafting treatment layer is then coated or treated with polyurethane slurry, and dried and dried to produce EVA synthetic leather with high bonding strength and further improved wear resistance and scratch resistance.

The third aspect of the present application provides a surface grafting treatment agent for ethylene-vinyl acetate copolymer synthetic leather, which includes 50 wt% to 82.4 wt% polyurethane prepolymer containing reactive groups at the end groups and 2.5 wt% to 15wt% curing agent, 5wt% to 15wt% dimethylformamide, 10wt% to 19wt% butanone and 0.1wt% to 1wt% dibutyltin dilaurate catalyst. The EVA synthetic leather adopting the surface grafting treatment agent of the present application can form a graft layer with strong adhesion on the surface of polyurethane. The surface of the grafting layer is then coated or treated to produce an EVA synthetic leather with high bonding strength and further improved physical properties such as wear resistance and scratch resistance.

In an embodiment of the third aspect of the present application, the active group in the polyurethane prepolymer having an active group at the end group is one or more of a hydroxyl group, an amino group, and a carboxyl group, preferably a hydroxyl group.

In an embodiment of the third aspect of the present application, the curing agent is a curing agent whose terminal group is a carboxyl group or an isocyanate. Preferably, the curing agent is an isocyanate-terminated curing agent. Further, the functionality of the isocyanate curing agent is 1.5 to 3.5, preferably 2.5 to 3.0.

In an embodiment of the third aspect of the present application, the content of the polyurethane prepolymer containing reactive groups at the end groups may be 60 wt% to 70 wt%.

In an embodiment of the third aspect of the present application, the content of the curing agent may be 5 wt% to 10 wt%.

BRIEF DESCRIPTION

FIG. 1 shows a schematic structural diagram of an EVA synthetic leather substrate provided by an embodiment of the present application. Among them, 11, base cloth; 12, radiation cross-linked EVA layer.

FIG. 2 shows a schematic structural diagram of an EVA synthetic leather provided by another embodiment of the present application. Among them, 21, base fabric; 22, radiation cross-linked EVA layer; 23, polyurethane layer.

FIG. 3 shows a schematic structural diagram of an EVA synthetic leather provided by another embodiment of the present application. Among them, 31, base layer; 32, multi-layer co-extruded EVA layer; 321, foam layer; 322, modified layer; 33, polyurethane layer.

FIG. 4 shows a schematic structural diagram of an EVA synthetic leather provided by another embodiment of the present application. Among them, 41, base cloth; 42, radiation cross-linked EVA layer; 43, surface grafting treatment layer; 44, polyurethane layer.

detailed description

In order to make the invention, technical solutions and beneficial technical effects of the present application clearer, the present application will be further described in detail in conjunction with the following embodiments. It should be understood that the embodiments described in this specification are only for explaining this application, not for limiting this application.

FIG. 1 is a schematic structural diagram of an EVA synthetic leather substrate as an example. Referring to FIG. 1, the EVA synthetic leather substrate may be a laminated structure of a base fabric 11 and a radiation-crosslinked EVA layer 12. Wherein, the EVA synthetic leather substrate may be the base fabric 11 and the radiation cross-linked EVA layer 12 in order from bottom to top.

The EVA synthetic leather substrate of the present application can be used for various EVA synthetic leathers, such as shoe upper leather, luggage leather, sofa leather, home decoration leather or leather-filled paper, etc. The EVA synthetic leather substrate of the present application can be used as EVA synthetic leather alone or as a key component of EVA synthetic leather. The following further describes the specific embodiments in combination.

In the following embodiments, the radiation crosslinking is carried out using high-energy electron beams.

The raw material formulations used for the EVA layers of Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-5 are: based on parts by weight, 100 parts EVA, 1 part cross-linking agent TAIC, 0.2 One part antioxidant 1010 and two parts colorant black masterbatch. Among them, TAIC (triallyl isocyanurate) is T-CROS purchased from Jiangsu Huaxing New Material Technology Co., Ltd. Antioxidant 1010 (chemical name: tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester) is THANOX 1010 purchased from Tianjin Lianlong New Materials Co., Ltd. The black masterbatch is the black masterbatch HM13 of Shanghai Xinliang Plastic Products Co., Ltd.

Example 1-1

In this example, the selected EVA grade is Formosa Plastics 7130F, the VA content is 9%, the melt flow rate under 190°C and 2.16kg load is 0.9g/10min, the thickness of the EVA layer is 3.0mm, and the radiation dose is 200KGY .

The synthetic leather manufacturing method includes the following steps:

1) Ingredients are prepared according to formula design;

2) After the raw materials are fully mixed, they are added to the extruder, extruded into a film, cast onto the base fabric, flattened and rolled up;

3) Obtain semi-finished synthetic leather after radiation crosslinking;

4) The semi-finished products of synthetic leather are subjected to surface treatment, and the conventional treatment procedures such as color change and kneading are processed.

Example 1-2

In this embodiment, the selected EVA grade is DuPont Elvax 560, the VA content is 15%, the melt flow rate under 190°C and 2.16kg load is 2.5g/10min, the thickness of the EVA layer is 2.0mm, the radiation dose is 150KGY .

The manufacturing method is the same as in Example 1-1.

Examples 1-3

In this embodiment, the selected EVA grade is Elvax 260 of Japan Mitsui Chemicals Co., Ltd., the VA content is 28%, the melt flow rate under 190°C and 2.16 kg load is 6.0 g/10min, and the thickness of the EVA layer is 2.0 mm. The radiation dose is 100KGY.

The manufacturing method is the same as in Example 1-1.

Examples 1-4

In this example, the selected EVA grade is Japan Mitsui Chemicals P3307, the VA content is 37%, the melt flow rate under 190°C and 2.16kg load is 30g/10min, the thickness of the EVA layer is 0.25mm, the radiation dose 20KGY.

The manufacturing method is the same as in Example 1-1.

Examples 1-5

In this embodiment, the selected EVA grade is Japan Mitsui Chemicals Co., Ltd. Elvax 40W, the VA content is 40%, the melt flow rate under 190 ℃, 2.16kg load is 65.0g/10min, the thickness of the EVA layer is 0.1mm, The radiation dose is 5KGY.

The manufacturing method is the same as in Example 1-1.

Comparative Example 1-1

In this comparative example, the selected EVA grade is Formosa Plastics 7130F, the VA content is 9%, the melt flow rate under 190°C and 2.16kg load is 0.9g/10min, the thickness of the EVA layer is 3.0mm, and there is no radiation crosslinking .

The manufacturing method includes the following steps:

1) Ingredients are prepared according to formula design;

3) The semi-finished synthetic leather is processed through the conventional treatment process of the latter stage of synthetic leather such as color change, surface treatment and kneading.

Comparative example 1-2

In this comparative example, the selected EVA grade is DuPont Elvax 560, the VA content is 15%, the melt flow rate under 190°C and 2.16kg load is 2.5g/10min, the thickness of the EVA layer is 2.0mm, and there is no radiation crosslinking , Other processes are the same as Comparative Example 1-1.

Comparative example 1-3

In this comparative example, the selected EVA grade is Elvax 260 of Japan Mitsui Chemicals Co., Ltd., the VA content is 28%, the melt flow rate under 190°C and 2.16kg load is 6.0g/10min, and the thickness of the EVA layer is 2.0mm. No radiation crosslinking, other processes are the same as Comparative Example 1-1.

Comparative Example 1-4

In this comparative example, the selected EVA grade is Japan Mitsui Chemicals P3307, the VA content is 37%, the melt flow rate under 190°C and 2.16kg load is 30g/10min, the thickness of the EVA layer is 0.25mm, no radiation Crosslinking, other processes are the same as Comparative Example 1-1.

Comparative example 1-5

In this comparative example, the selected EVA grade is Japan Mitsui Chemicals Co., Ltd. Elvax 40W, the VA content is 40%, the melt flow rate under 190 ℃, 2.16kg load is 65.0g/10min, the thickness of the EVA layer is 0.1mm, No radiation crosslinking, other processes are the same as Comparative Example 1-1.

The properties of the new synthetic leathers obtained in Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-5 were measured. Test the resilience of synthetic leather according to hand touch. Test the abrasion resistance according to ASTM 1242-1995. The results are shown in Table 1-1.

Table 1-1 Performance data of each synthetic leather

It can be seen from the data in Table 1 that the EVA synthetic leather substrate and its manufacturing method used in this application have good resilience, flexibility, aging resistance and other properties after radiation crosslinking, and are environmentally friendly and process Simple, low cost and other advantages.

Examples 1-3 use EVA raw material with appropriate VA content and melt flow rate, and appropriate radiation dose, the prepared synthetic leather has good abrasion resistance and higher flexibility and resilience .

The synthetic leathers of Examples 1-3 have a better feel.

The EVA synthetic leather base material, EVA synthetic leather and preparation method of the present application are adopted, and the manufacturing process is simple. At the same time, o-benzene plasticizers, organic solvents and other harmful chemicals are not used in the production process, which eliminates organic pollution from the source and simultaneously Consumption is also greatly reduced, with obvious innovation and significant social and economic benefits.

Examples 1-6 to 1-10: The synthetic leathers of Examples 1-1 to 1-5 were embossed after radiation crosslinking.

Examples 1-11 to 1-15: different from Examples 1-1 to 1-5, respectively, the synthetic leather manufacturing method includes the following steps:

1) Ingredients are prepared according to formula design;

2) After the raw materials are fully mixed, they are added to the extruder, extruded into a film, cast onto the base fabric, flattened and rolled up to obtain

Semi-finished leather products;

3) Carry out conventional processing procedures such as embossing on semi-finished synthetic leather;

4) Radiation cross-linking.

Comparative Examples 1-6 to 1-10: The EVA synthetic leathers of Comparative Examples 1-1 to 1-5 were embossed.

Examples 1-6 to 1-15 and Comparative Examples 1-6 to 1-10 were tested. The test methods of resilience and abrasion resistance are as described above. The test method of pattern retention is: under normal pressure, temperature 85 ℃, humidity 85%, place it for 168h, and observe whether the pattern of synthetic leather can be maintained. The test results are shown in Table 1-2.

Table 1-2 Performance data of each synthetic leather

It can be seen from the comparison between Examples 1-6 to 1-15 and Comparative Examples 1-6 to 1-10 that radiation crosslinking can also improve the pattern retention of synthetic leather. After the synthetic leather of the present application is embossed, its pattern can be maintained for a long time, thereby improving the appearance of the synthetic leather.

It can also be seen from the results of Examples 1-11 to 1-15 and Examples 1-6 to 1-10 that by making the VA content of the raw material EVA and the melt flow rate, and the radiation dose of radiation crosslinking in the appropriate range It can further improve the pattern retention of synthetic leather.

It can be seen from the comparison between Examples 1-11 to 1-15 and Examples 1-6 to 1-10 that the EVA synthetic leather is first embossed and then radiantly cross-linked, which can further improve the pattern retention of the synthetic leather Sex, so that its pattern can be more effectively maintained for a long time.

FIG. 2 is a schematic diagram of EVA synthetic leather as an example. Referring to FIG. 2, an EVA synthetic leather provided by the present application includes a base fabric 21, a radiation cross-linked EVA layer 22, and a polyurethane layer 23 in this order from bottom to top. The following further describes the specific embodiments in combination.

In the EVA synthetic leather of the following examples 2-1 to 2-6, in terms of parts by weight,

The raw material formula used in the EVA layer is:

The raw material formula used in the polyurethane layer is:

Solvent-free polyurethane prepolymer (Zhejiang New Oriental Ink WRJ-7700) 100 copies

Curing agent (Zhejiang New Oriental Ink WRJ-8800) 66.5 copies

Catalyst (Germany Bayer Group T-12) 0.17 copies

Among them, the isocyanate content of the polyurethane prepolymer is 2.3%, and the hydroxyl value of the curing agent is 40 mgKOH/g.

The preparation method of EVA synthetic leather can specifically include the following steps:

Processing the base cloth;

Melt casting EVA resin onto the base fabric;

The EVA layer is cross-linked by irradiation treatment;

A polyurethane wear-resistant layer is coated on the other surface of the EVA layer opposite to the base fabric.

Finally, it is processed through the conventional treatment process of the latter stage of synthetic leather such as color changing and kneading. A new synthetic leather structure is obtained.

Synthetic leathers of different thicknesses shown in Table 2 were used.

Table 2

In the synthetic leather, the radiation cross-linked EVA layer has high bonding strength with the base fabric, and the manufacturing process is simple, and the production cost is low. The synthetic leather includes a radiation-crosslinked EVA layer. The EVA used is a rubber-like thermoplastic with excellent flexibility, low-temperature flexibility, elasticity, stress crack resistance, and good plasticity and workability. . After radiation crosslinking, the comprehensive physical properties of EVA are greatly improved, such as resilience, aging resistance, temperature resistance and solvent resistance.

The embodiments of the present application also provide an EVA synthetic leather, which includes a paper base, a radiation cross-linked EVA layer, and a polyurethane layer. The EVA synthetic leather is leather-filled paper. Next, the EVA synthetic leather will be described in detail with reference to specific embodiments.

In the EVA synthetic leathers of the following Examples 3-1 to 3-7 and Comparative Examples 3-1 to 3-3, the ingredients of the EVA layer are selected from:

EVA: Elvax 260 of Mitsui Chemicals Corporation, Japan;

Cross-linking agent: TAIC, which is T-CROS of Jiangsu Huaxing New Material Technology Co., Ltd.;

Filler: CaCO ₃ ;

Colorant: Black masterbatch HM13 of Shanghai Xinliang Plastic Products Co., Ltd.;

Polyolefin resin: ethylene-octene copolymer resin (LG Chemical LC670); low-density polyethylene resin (LG Chemical FB3050); ethylene-butene copolymer resin (LG Chemical LC565).

In the EVA synthetic leathers of the following Examples 3-1 to 3-7 and Comparative Example 3-1, in terms of parts by weight,

The raw material formula used in the polyurethane layer is:

Curing agent (Zhejiang New Oriental Ink WRJ-8800) 66.5 copies

Catalyst (Germany Bayer Group T-12) 0.17 copies

Example 3-1

In this embodiment, the total thickness of the environmentally friendly EVA skin paper is 0.15 mm, of which the thickness of the base paper is 0.10 mm, the grammage is 80 g/m ² , the thickness of the EVA layer is 0.04 mm, and the thickness of the polyurethane layer is 0.01 mm. The degree of crosslinking of the EVA layer after radiation crosslinking was 80%. The raw material ratio of the EVA layer is: EVA: 100 parts, cross-linking agent: 3 parts.

Example 3-2

In this embodiment, the total thickness of the environmentally friendly EVA skin paper is 0.26 mm, of which the thickness of the base paper is 0.20 mm, the grammage is 160 g/m ² , the thickness of the EVA layer is 0.04 mm, and the thickness of the polyurethane layer is 0.02 mm. The degree of crosslinking of the EVA layer after radiation crosslinking was 70%. In addition, the raw material ratio of the EVA layer is: EVA: 100 parts, cross-linking agent: 3 parts, colorant: 10 parts.

Example 3-3

In this embodiment, the total thickness of the environmentally friendly EVA skin paper is 0.32 mm, of which the thickness of the base paper is 0.20 mm, the gram weight is 160 g/m ² , the thickness of the EVA layer is 0.1 mm, and the thickness of the polyurethane layer is 0.02 mm. The degree of crosslinking of the EVA layer after radiation crosslinking was 20%. In addition, the raw material ratio of the EVA layer is: EVA: 100 parts, cross-linking agent: 1 part, filler: 50 parts, colorant: 3 parts.

Example 3-4

In this embodiment, the total thickness of the environmentally friendly EVA skin paper is 0.55 mm, of which the thickness of the base paper is 0.25 mm, the grammage is 200 g/m ² , the thickness of the EVA layer is 0.25 mm, and the thickness of the polyurethane layer is 0.05 mm. The crosslinking degree of the EVA layer after radiation crosslinking was 1.0%. In addition, the raw material ratio of the EVA layer is: EVA: 100 parts, filler: 100 parts, colorant: 3 parts.

Example 3-5

In this embodiment, the total thickness of the environmentally friendly EVA skin paper is 0.32 mm, of which the thickness of the base paper is 0.20 mm, the gram weight is 160 g/m ² , the thickness of the EVA layer is 0.1 mm, and the thickness of the polyurethane layer is 0.02 mm. The degree of crosslinking of the EVA layer after radiation crosslinking was 52%. In addition, the raw material ratio of the EVA layer is: EVA: 100 parts, ethylene-octene copolymer resin: 100 parts, cross-linking agent: 2 parts, filler: 100 parts, colorant: 6 parts.

Example 3-6

In this embodiment, the total thickness of the environmentally friendly EVA skin paper is 0.32 mm, of which the thickness of the base paper is 0.20 mm, the gram weight is 160 g/m ² , the thickness of the EVA layer is 0.1 mm, and the thickness of the polyurethane layer is 0.02 mm. The degree of crosslinking of the EVA layer after radiation crosslinking was 90%. In addition, the raw material ratio of the EVA layer is: EVA: 100 parts, low density polyethylene resin: 100 parts, cross-linking aid: 6 parts, filler: 200 parts, colorant: 20 parts.

Example 3-7

In this embodiment, the total thickness of the environmentally friendly EVA skin paper is 0.32 mm, of which the thickness of the base paper is 0.20 mm, the gram weight is 160 g/m ² , the thickness of the EVA layer is 0.1 mm, and the thickness of the polyurethane layer is 0.02 mm. The degree of crosslinking of the EVA layer after radiation crosslinking was 46%. In addition, the raw material ratio of the EVA layer is: EVA: 100 parts, ethylene-butene copolymer resin: 100 parts, cross-linking aid: 2 parts, filler: 100 parts, colorant: 6 parts.

Comparative Example 3-1

In this embodiment, the total thickness of the skin-filled paper is 0.22 mm, of which the thickness of the base paper is 0.20 mm, the grammage is 160 g/m ² , there is no EVA layer, and the thickness of the polyurethane layer is 0.02 mm.

Comparative Example 3-2

In this embodiment, the total thickness of the PVC skin paper is 0.30 mm, wherein the thickness of the base paper is 0.20 mm, the grammage is 160 g/m ² , and the thickness of the PVC layer is 0.10 mm.

Comparative Example 3-3

In this embodiment, the total thickness of the EVA skin paper is 0.30mm, of which the thickness of the base paper is 0.20mm, the grammage is 160g/m ² , the thickness of the EVA layer is 0.1mm, there is no polyurethane layer, and the EVA layer after radiation crosslinking The degree of crosslinking is 20%. In addition, the raw material ratio of the EVA layer is: EVA: 100 parts, cross-linking agent: 1 part, filler: 50 parts, colorant: 3 parts.

The test method for the degree of crosslinking in the above Examples 3-1 to 3-7 and Comparative Examples 3-1 to 3-3 is the xylene extraction method in GB/T 29848-2018-5.5.3 to test the crosslinking degree of the EVA layer .

The performance of the environmentally friendly EVA furnishing papers prepared in Examples 3-1 to 3-7 and Comparative Examples 3-1 to 3-3 was measured. Observe the fullness and clarity of the embossed lines on the surface of the filling paper. If the lines are full and clear, the embossability of the filling paper is good. Test the abrasion resistance according to ASTM 1242-1995. The results are shown in Table 3.

Table 3 Performance data sheet of each filling paper

It can be seen from the data of Examples 3-1 to 3-7 and Comparative Examples 3-1 to 3-3 that the environmentally friendly EVA leather-filled paper in this application is adopted, and the EVA layer is used as the base material layer, which is comparable to the PU leather-filled paper Better than embossing and high texture simulation, strong leather feeling, can be folded at will, beautiful gloss, high grade, good wear resistance. The production process is simple and environmentally friendly, the cost is low, and the radiation-crosslinked EVA layer has excellent resilience, aging resistance, temperature resistance and solvent resistance.

From the results of Examples 3-5 and 3-7, it can be seen that when the EVA layer contains an appropriate polyolefin resin, and the EVA layer has an appropriate degree of radiation crosslinking, the leather-filled paper has higher abrasion resistance and has a higher High flexibility.

In some embodiments, the EVA synthetic leather is a multi-layer co-extruded EVA resin foamed and cross-linked synthetic leather. FIG. 3 is a schematic diagram of a synthetic leather foamed and cross-linked by a multi-layer co-extruded EVA resin as an example. 3, an EVA synthetic leather provided by the present application includes a polyurethane layer 33, a multi-layer co-extruded EVA layer 32, and a base layer 31 attached to the multi-layer co-extruded EVA layer 32 in order from top to bottom. The co-extruded EVA layer 32 is foamed and cross-linked, and includes at least one modified layer 322 and at least one foamed layer 321, and the polyurethane layer 33 is in close contact with the modified layer 322. The following further describes the specific embodiments in combination.

In the following Examples 4-1 to 4-11 and Comparative Examples 4-1 to 4-2, EVA is Elvax260 from Mitsui Chemicals Co., Ltd.; black masterbatch is black color masterbatch HM13 from Shanghai Xinliang Plastic Products Co., Ltd.

Example 4-1

In this embodiment, the polyurethane layer in the multi-layer co-extruded EVA resin foamed and cross-linked synthetic leather is a conventional solvent-free polyurethane slurry formulation. The multi-layer co-extruded EVA layer includes a foam layer and a modified layer, in which the foam layer In contact with the base fabric layer, the raw material ratios of the foam layer, modified layer and polyurethane layer slurry are:

Foam layer

Ethylene vinyl acetate copolymer (EVA) 100 copies

ADC foaming agent (Jiangsu Thorpe DN10) 1 copy

Modified layer

Polyurethane layer

Curing agent (Zhejiang New Oriental Ink WRJ-8800) 66.5 copies

Catalyst (Germany Bayer Group T-12) 0.17 copies

The isocyanate content of the polyurethane prepolymer is 2.3%, and the hydroxyl value of the curing agent is 40mgKOH/g;

The invention also provides a method for preparing a multi-layer co-extruded EVA resin foamed and cross-linked synthetic leather. The method includes the following steps:

1) Prepare raw materials for foam layer and modified layer;

2) The raw materials of the foamed layer and the modified layer are fully mixed and added to the extruder separately, extruded into a film, cast onto the substrate and rolled into a film, and the thickness of the base layer is 0.1mm;

3) Foam the multi-layer co-extruded EVA resin in a high-temperature furnace with a foaming temperature ranging from 100 to 230°C. The total thickness after foaming is 0.1mm, and the thickness of the modified layer is 0.01mm;

4) A polyurethane layer is coated on the multi-layer co-extruded EVA layer after foaming, and the thickness of the polyurethane layer is 0.01 mm.

Finally, after the subsequent embossing and other treatments, that is, a multi-layer co-extruded EVA resin foamed and cross-linked synthetic leather is prepared.

Example 4-2

In this example, the ratio of polyurethane layer slurry in the synthetic leather foamed and cross-linked with multi-layer co-extruded EVA resin is the same as that in Example 4-1. The multi-layer co-extruded EVA layer includes a foam layer and a modified layer, in which The foam layer is in contact with the base fabric layer, and the raw material ratios of the foam layer and the modified layer are:

Foam layer

Modified layer

1) Prepare the raw materials for foam layer and modified layer;

2) The raw materials of the foamed layer and the modified layer are fully mixed and added to the extruder separately, extruded into a film, cast onto the substrate and rolled into a film, and the thickness of the base layer is 1.0 mm;

3) The multi-layer co-extruded EVA resin is foamed in a high-temperature furnace, the foaming temperature range is 100-230°C, and the total thickness after foaming is 1.0 mm, where the thickness of the modified layer is 0.1 mm;

4) Radiation cross-linking the multi-layer co-extruded EVA layer after foaming, the radiation dose is 20KGy;

5) A polyurethane layer is coated on the multi-layer coextruded EVA layer after foaming and radiation crosslinking, and the thickness of the polyurethane layer is 0.05 mm.

Example 4-3

In this example, the ratio of the polyurethane layer slurry in the synthetic leather foamed and crosslinked by the multi-layer co-extruded EVA resin is the same as that of Example 4-1. The multi-layer co-extruded EVA layer includes a foam layer and a modified layer, in which The foam layer is in contact with the base fabric layer, the raw material ratio of the modified layer, the thickness of each layer and the preparation method are the same as those in Example 4-2. The raw material ratio of the foam layer is:

Foam layer

Example 4-4

Foam layer

Example 4-5

In this example, the ratio of polyurethane layer slurry in the synthetic leather foamed and cross-linked with multi-layer co-extruded EVA resin is the same as that in Example 4-1. The multi-layer co-extruded EVA layer includes a foam layer and a modified layer, in which The foam layer is in contact with the base fabric layer, and the raw material ratio of the modified layer is the same as in Example 4-2. The raw material ratio of the foam layer is:

Foam layer

1) Prepare the raw materials for foam layer and modified layer;

2) The raw materials of the foamed layer and the modified layer are fully mixed into an extruder, extruded into a film, cast onto a substrate and rolled into a film, and the thickness of the base layer is 2.2 mm;

3) The multi-layer co-extruded EVA resin is foamed in a high-temperature furnace with a foaming temperature ranging from 100 to 230°C. The total thickness after foaming is 3.0 mm, and the thickness of the modified layer is 1.0 mm;

4) Radiation cross-linking the multi-layer co-extruded EVA layer after foaming, the radiation dose is 90KGy;

5) A polyurethane layer is coated on the multi-layer co-extruded EVA layer after foaming and radiation crosslinking, and the thickness of the polyurethane layer is 0.1 mm.

Example 4-6

In this embodiment, the polyurethane layer in the multi-layer co-extruded EVA resin foamed and cross-linked synthetic leather is a conventional water-based polyurethane slurry formulation. The multi-layer co-extruded EVA resin layer includes a modified layer 1 (mainly from the base fabric layer) Adhesion), foamed layer and modified layer 2, where modified layer 1 is in contact with the base fabric layer, the raw material ratio of foamed layer, modified layer and polyurethane layer are:

Modified layer 1

Ethylene vinyl acetate copolymer (EVA) 100 copies

Foam layer

Modified layer 2

Polyurethane layer

The waterborne polyurethane is aliphatic polyurethane with a solid content of 35%; the crosslinking agent is aziridine type;

1) Prepare the raw materials for foam layer and modified layer;

3) The multi-layer co-extruded EVA resin is foamed in a high-temperature furnace with a foaming temperature range of 100 to 230° C. The total thickness after foaming is 1.0 mm, where the thickness of the modified layer 1 is 0.04 mm and the modified layer 2 The thickness is 0.1mm;

Example 4-7

In this example, the ratio of polyurethane layer slurry in the multi-layer co-extruded EVA resin foamed and cross-linked synthetic leather is the same as that in Example 4-6, modified layer 1, modified layer 2, multi-layer co-extruded EVA layer The thickness and preparation method are the same as in Examples 4-6, only the modified layer 2 formulation is adjusted, and the raw material ratio of the modified layer 2 is:

Modified layer 2

Example 4-8

In this example, the ratio of polyurethane layer slurry in the multi-layer co-extruded EVA resin foamed and cross-linked synthetic leather is the same as that in Example 4-6, modified layer 1, modified layer 2, multi-layer co-extruded EVA layer The thickness is the same as that in Example 4-6, and the foaming temperature is adjusted to 100-160°C in the preparation method, and the other preparation methods are the same as in Example 4-6. The ADC foaming agent in the foaming layer is replaced with OBSH foaming agent. The raw material ratio is:

Foam layer

Example 4-9

In this example, the ratio of polyurethane layer slurry in the multi-layer co-extruded EVA resin foamed and cross-linked synthetic leather is the same as that in Example 4-6, modified layer 1, modified layer 2, multi-layer co-extruded EVA layer The thickness is the same as in Example 4-6, the foaming temperature is adjusted to 100-180°C in the preparation method, and the other preparation methods are the same as in Example 4-6, the ADC foaming agent in the foaming layer is replaced with a microsphere foaming agent, the foaming layer The raw material ratio is:

Foam layer

Example 4-10

In this embodiment, the ratio of the polyurethane layer slurry in the synthetic leather foamed and crosslinked by the multi-layer co-extruded EVA resin is the same as that of Examples 4-6. The multi-layer co-extruded EVA resin layer includes the modified layer 1 and the foamed layer 1 , Foam layer 2 and modified layer 2, wherein the modified layer 1 is in contact with the base fabric layer, the raw material ratio of the foam layer and the modified layer are:

Modified layer 1

Ethylene vinyl acetate copolymer (EVA) 100 copies

Foam layer 1

Ethylene vinyl acetate copolymer (EVA) 100 copies

ADC foaming agent (Jiangsu Thorpe DN10) 1 copy

Cross-linking agent (DCP) 0.2 copies

Foam layer 2

Modified layer 2

The invention also provides a method for preparing a multi-layer co-extruded EVA resin foamed and cross-linked synthetic leather, which includes the following steps:

1) Prepare the raw materials for foam layer and modified layer;

3) The multi-layer co-extruded EVA resin is foamed in a high-temperature furnace, the foaming temperature range is 100-230°C, and the total thickness after foaming is 1.0 mm, where the thickness of the modified layer 1 is 0.04 mm, and the modified layer 2 The thickness is 0.1mm;

Example 4-11

In this embodiment, the ratio of the polyurethane layer slurry in the synthetic leather foamed and crosslinked by the multi-layer co-extruded EVA resin is the same as that of Examples 4-6. The multi-layer co-extruded EVA resin layer includes the modified layer 1 and the foamed layer 1 , The modified layer 2, the foamed layer 2 and the modified layer 3, 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:

Modified layer 1

Ethylene vinyl acetate copolymer (EVA) 100 copies

Foam layers 1 and 2

Modified layers 2 and 3

1) Prepare the raw materials for foam layer and modified layer;

3) The multi-layer co-extruded EVA resin is foamed in a high-temperature furnace with a foaming temperature range of 100 to 230°C. The total thickness after foaming is 1.5 mm, where the thickness of the modified layer 1 is 0.04 mm and the modified layer 2 The thickness of and 3 are each 0.1mm;

Comparative Example 4-1

The formulation and preparation method of each layer are the same as in Example 4-2, except that there is no foaming.

Comparative Example 4-2

The formulation and preparation method of each layer are the same as in Examples 4-6, except that there is no foaming.

Examples 4-1 to 4-11 and Comparative Examples 4-1 and 4-2 made of multi-layer coextruded EVA resin foamed and crosslinked synthetic leather base layer and multi-layer coextruded EVA layer adhesion, The cross-linking degree, Shore hardness and wear resistance of synthetic leather of the multi-layer co-extruded EVA layer are shown in Table 1 below: The interlayer adhesion is tested according to GB/T 14905-2009, according to GB/T29848-2018-5.5 .3 The xylene extraction method was used to test the degree of crosslinking of the EVA layer, the abrasion resistance was tested according to ASTM D 1242-1995, and the Shore hardness was tested according to GB/T 2411-2008.

Table 4 Performance parameters of multi-layer co-extruded EVA resin foamed and cross-linked synthetic leather

Note: The expansion ratio of all samples in the examples is controlled in the range of 2 to 2.5 times.

From the performance data in Table 4, it can be seen that the use of multi-layer co-extruded EVA resin foamed and cross-linked synthetic leather improves the hardness, temperature resistance, flexibility, aging resistance and solvent resistance of synthetic leather. Synthetic leather It also has excellent comprehensive performances such as good wear resistance, environmental protection, non-toxicity, and comfortable feel. The EVA layer uses a multi-layer co-extrusion method, the production process is simple, and the adhesion between the layers is high. The degree of cross-linking of the foamed EVA resin layer can be adjusted by adjusting the amount of cross-linking agent, radiation dose, and foaming time.

Referring to FIG. 4, another EVA synthetic leather structure provided in an embodiment of the present application is, from bottom to top, a base fabric 41, a radiation-crosslinked EVA layer 42, a surface graft treatment layer 43, and a polyurethane layer 44. The following is a further description in conjunction with specific embodiments.

In Examples 5-1 to 5-6, the EVA synthetic leather is, from bottom to top, the base fabric 41, the radiation-crosslinked EVA layer 42, the surface graft treatment layer 43, and the polyurethane layer 44; wherein, the raw materials of the EVA layer The formula is:

The raw material formula of the polyurethane layer is:

Solvent-free polyurethane prepolymer (Shanghai New Oriental Ink WRJ-7700) 100 copies

Curing agent (Shanghai New Oriental Ink WRJ-8800) 66.5 copies

Catalyst (Germany Bayer Group T-12) 0.17 copies

The raw material formula of the surface grafting treatment layer is:

The isocyanate content of the polyurethane prepolymer is 15.0%, and the hydroxyl value of the curing agent is 210 mgKOH/g.

In Examples 5-1 to 5-6, the preparation method of EVA synthetic leather specifically includes the following steps:

Processing the base cloth;

Melt casting EVA resin onto the base fabric;

The EVA layer is cross-linked by irradiation treatment;

Coat a grafting treatment layer on the other surface of the EVA layer opposite to the base cloth;

A polyurethane layer is coated on the surface of the graft treatment layer.

Finally, it is processed through the conventional treatment process of the latter stage of synthetic leather such as color changing and kneading. Get a new type of EVA synthetic leather. Synthetic leathers of different thicknesses shown in Table 5 were used.

table 5

In the EVA synthetic leather of the present application, the radiation cross-linked EVA layer and the base fabric have high bonding strength, and the surface grafting treatment layer coated on the surface of the EVA layer can further enhance the adhesion between the polyurethane layer and the EVA layer, and the manufacturing process is simple , Low production costs and other advantages. The structure includes an EVA layer. The EVA used is a rubber-like thermoplastic with excellent flexibility, low-temperature flexibility, elasticity, stress crack resistance, and good plasticity and workability. After radiation crosslinking, the comprehensive physical properties of EVA are greatly improved, such as resilience, aging resistance, temperature resistance and solvent resistance.

Modification of the surface of the EVA layer through the surface grafting treatment layer can produce a leading effect, so that the subsequent coating (polyurethane layer) can produce sufficient adhesion strength on the surface, and form a guarantee basis for the improvement of the final physical properties. In addition, in the production process provided by the present application, EVA synthetic leather is produced, and no harmful chemicals such as environmentally friendly organic solvents are used in the production process of EVA raw material casting film, surface grafting treatment, coating polyurethane layer, etc. Eliminate organic pollution from the source, and have better bonding strength, wear resistance and scratch resistance.

In Examples 6-1 to 6-10 and Comparative Examples 6-1 to 6-7, the EVA synthetic leather is the base fabric 41, the radiation-crosslinked EVA layer 42, the surface graft treatment layer 43 and Polyurethane layer 44; of which, EVA is Elvax 260 of Mitsui Chemicals Corporation, Japan.

Example 6-1

In this embodiment, the surface grafting treatment agent includes the following raw materials in weight percent:

The isocyanate content of the polyurethane prepolymer is 14.5%, and the hydroxyl value of the curing agent is 80mgKOH/g;

The conventional formula of surface polyurethane slurry includes the following raw materials in weight percent:

Solvent-free polyurethane prepolymer (Zhejiang New Oriental Ink WRJ-8800) 60.0wt%

Curing agent (Zhejiang New Oriental Ink WRJ-7700) 39.9wt%

Catalyst (Germany Bayer Group T-12) 0.1wt%

The preparation of environmentally friendly EVA synthetic leather with surface grafting treatment includes the following steps:

1) Prepare the relevant raw materials of the EVA layer, where the content of EVA is 50wt%;

2) After fully mixing the raw materials, add them to the extruder, extrude into a film, cast onto the base fabric, flatten and wind up;

3) Radiation cross-linking, the degree of cross-linking of the EVA layer is 20%, and an environmentally friendly EVA synthetic leather substrate is obtained;

4) A layer of environmentally friendly surface grafting treatment agent is pre-treated on the surface of the environmentally friendly EVA synthetic leather substrate, which is formed into a film by means of net transfer printing or roller coating, and then pre-crosslinked by heating, cooling, coating, curing, In the processes such as film peeling, the thickness of the graft treatment layer is 20 μm.

5) The surface of the graft treatment layer is then coated or treated with a solvent-free polyurethane slurry. The formula is the same as the above conventional formula. After drying and aging, the thickness of the polyurethane layer is 50 μm. It can be made to have high bonding strength and resistance. Environmentally friendly EVA synthetic leather with better physical properties such as scratch resistance.

Example 6-2

The isocyanate content of the polyurethane prepolymer is 15.0%, and the hydroxyl value of the curing agent is 210mgKOH/g;

1) Prepare the relevant raw materials of the EVA layer, in which the content of EVA is 60wt%;

3) Radiation cross-linking, the cross-linking degree of the EVA layer is 72%, and an environmentally friendly EVA synthetic leather substrate is obtained;

5) The surface of the graft treatment layer is then coated or treated with a solvent-free polyurethane slurry. The formula is the same as in Example 6-1. After drying and aging, the thickness of the polyurethane layer is 50 μm, which can produce a high bonding strength. At the same time, environmentally friendly EVA synthetic leather with better physical properties such as wear resistance and scratch resistance.

Example 6-3

The isocyanate content of the polyurethane prepolymer is 10.5%, and the hydroxyl value of the curing agent is 400mgKOH/g;

1) Prepare the relevant raw materials of the EVA layer, where the content of EVA is 78wt%;

3) Radiation cross-linking, the degree of cross-linking of the EVA layer is 90%, to obtain environmentally friendly EVA synthetic leather substrate;

Example 6-4

1) Prepare the relevant raw materials of the EVA layer, where the content of EVA is 95wt%;

3) Radiation cross-linking, the cross-linking degree of the EVA layer is 34%, and an environmentally friendly EVA synthetic leather substrate is obtained;

Example 6-5

3) Radiation cross-linking, the degree of cross-linking of the EVA layer is 40%, and an environmentally friendly EVA synthetic leather substrate is obtained;

Example 6-6

4) A layer of environmentally friendly surface grafting treatment agent is pre-treated on the surface of the environmentally friendly EVA synthetic leather substrate, which is formed into a film by means of net transfer printing or roller coating, and then pre-crosslinked by heating, cooling, coating, curing, The thickness of the grafting treatment layer is 40 μm in processes such as film peeling.

5) The surface of the graft treatment layer is then coated or treated with a solvent-free polyurethane slurry. The formula is the same as in Example 6-1. After drying and aging, the thickness of the polyurethane layer is 15 μm, which can produce a high bonding strength. At the same time, environmentally friendly EVA synthetic leather with better physical properties such as wear resistance and scratch resistance.

Example 6-7

Among them, the water-based polyurethane 1 is an aliphatic polyurethane with a solid content of 35%; the cross-linking agent 1 is an isocyanate type;

The surface-coated polyurethane slurry includes the following raw materials in weight percent:

Among them, waterborne polyurethane 2 is aliphatic polyurethane with a solid content of 35%; crosslinking agent 2 is aziridine type;

4) A layer of environmentally friendly surface grafting treatment agent is pre-treated on the surface of the environmentally friendly EVA synthetic leather substrate, and the film is formed by net transfer printing or roll coating, and then subjected to heating pre-crosslinking, cooling, aging and other processes. The thickness of the branch treatment layer is 10 μm.

5) The surface of the graft treatment layer is then coated or treated with water-based polyurethane slurry, as described above, after drying and drying, the thickness of the polyurethane layer is 50 μm, which can be made to have high bonding strength and wear and scratch resistance. Environmentally friendly EVA synthetic leather with better physical properties.

Example 6-8

Among them, the waterborne polyurethane 3 is aromatic and the solid content is 40%; the crosslinking agent 1 is isocyanate type;

4) A layer of environmentally friendly surface grafting treatment agent is pre-treated on the surface of the environmentally friendly EVA synthetic leather substrate, and the film is formed by net transfer printing or roll coating, and then subjected to heating pre-crosslinking, cooling, aging and other processes. The thickness of the branch treatment layer is 5 μm.

5) The surface of the graft treatment layer is then coated or treated with water-based polyurethane slurry. The formula is the same as that in Example 6-7. After drying and aging, the thickness of the polyurethane layer is 100 μm, which can produce a high bonding strength and resistance. Environmentally friendly EVA synthetic leather with better physical properties such as scratch resistance.

Examples 6-9

Among them, the waterborne polyurethane 4 is an aliphatic polyurethane water emulsion with a solid content of 25%; the crosslinking agent 1 is an isocyanate type;

4) A layer of environmentally friendly surface grafting treatment agent is pre-treated on the surface of the environmentally friendly EVA synthetic leather substrate, and the film is formed by net transfer printing or roll coating, and then subjected to heating pre-crosslinking, cooling, aging and other processes. The thickness of the branch treatment layer is 20 μm.

5) The surface of the grafted treatment layer is then coated or treated with aqueous polyurethane slurry. The formula is the same as that in Example 6-7. After drying and aging, the thickness of the polyurethane layer is 50 μm, which can produce a high bonding strength and resistance. Environmentally friendly EVA synthetic leather with better physical properties such as scratch resistance.

Example 6-10

Among them, waterborne polyurethane 5 is acrylate modified polyurethane with solid content of 32%; crosslinking agent 1 is isocyanate type;

Comparative Example 6-1

In this comparative example, the EVA synthetic leather is not cross-linked by irradiation, and the surface is not coated with a surface graft treatment layer and a polyurethane layer, wherein the EVA content in the EVA layer is 60wt%, and other preparation methods are the same as in Examples 6-5 .

Comparative Example 6-2

In this comparative example, the EVA synthetic leather is not cross-linked by irradiation, and the surface is not coated with a surface graft treatment layer, and only a polyurethane layer is coated on the surface of the environmentally friendly EVA synthetic leather substrate, wherein the EVA content in the EVA layer is 60wt%, other preparation methods and polyurethane layer are the same as in Examples 6-5.

Comparative Example 6-3

In this comparative example, the EVA synthetic leather has irradiation crosslinking, the degree of crosslinking is 40%, and the surface is not coated with a surface graft treatment layer and a polyurethane layer, wherein the EVA content in the EVA layer is 60wt%, other methods are the same Example 6-5.

Comparative Example 6-4

In this comparative example, the EVA synthetic leather has irradiation crosslinking, the degree of crosslinking is 40%, and the surface is not coated with a surface grafting treatment layer, and only a polyurethane layer is coated on the surface of the environmentally friendly EVA synthetic leather substrate, of which EVA The content of EVA in the layer is 60wt%. Other preparation methods and polyurethane layer are the same as those in Example 6-5.

Comparative Example 6-5

In this comparative example, the EVA synthetic leather is not irradiated and cross-linked, and the surface is not coated with a polyurethane layer. The surface graft treatment layer is only coated on the surface of the environmentally friendly EVA synthetic leather substrate, with a thickness of 20 μm, of which the EVA layer The content of EVA is 60wt%, and other preparation methods and surface grafting treatment layers are the same as in Examples 6-5.

Comparative Example 6-6

In this comparative example, the EVA synthetic leather is not cross-linked by irradiation, and the surface is coated with a surface graft treatment layer and a polyurethane layer, wherein the EVA content in the EVA layer is 60 wt%, other preparation methods and surface treatment layer and polyurethane layer Same as Example 6-5.

Comparative Example 6-7

In this comparative example, the EVA synthetic leather is irradiated and cross-linked, the degree of cross-linking is 40%, and the surface is not coated with a polyurethane layer, and only the surface graft treatment layer is coated on the surface of the environmentally friendly EVA synthetic leather substrate. The thickness is 20 μm, and the content of EVA in the EVA layer is 60% by weight. Other preparation methods and surface grafting treatment layers are the same as in Examples 6-5.

The properties of the synthetic leathers obtained in Examples 6-1 to 6-10 and Comparative Examples 6-1 to 6-7 were measured, the peel strength was tested according to the provisions of GB/T8949-2008, and the abrasion resistance was tested according to ASTM D 1242-1995 The test results are shown in Table 6.

Table 6 Performance data of each synthetic leather

Note: Comparative examples 6-2 and 6-4 of the peel strength are the peel strength data of the polyurethane layer and the EVA layer. The peel strength of other examples and comparative examples is actually the peel strength data of the base fabric and the EVA layer, which shows that after passing the surface After the grafting treatment, the bonding strength between the polyurethane layer and the EVA layer is greater than the bonding strength between the EVA layer and the base fabric.

It can be seen from the data in Table 6 that the environmentally friendly EVA synthetic leather produced by surface grafting in this application and the synthetic leather produced by the corresponding preparation method are used. The EVA raw materials are cast into a film, surface grafted, and coated with a polyurethane layer. In the production process, no environmentally friendly organic solvents and other harmful chemicals are used. The organic pollution is eliminated from the source, and it has environmentally friendly EVA synthetic leather with high bonding strength, wear resistance and scratch resistance.

Another EVA synthetic leather provided by the embodiments of the present application includes a base fabric, a radiation cross-linked EVA layer, a surface grafting treatment layer, and a polyurethane layer in this order from bottom to top. The surface grafting treatment layer is formed of a surface grafting treatment agent, and the surface grafting treatment agent includes 50 wt% to 82.4 wt% polyurethane prepolymer containing active groups at the end groups, 2.5 wt% to 15 wt% curing agent, 5wt%~15wt% dimethylformamide, 10wt%~19wt% butanone and 0.1wt%~1wt% dibutyltin dilaurate catalyst. The EVA synthetic leather of the present application uses the surface grafting treatment agent to form a graft layer with strong adhesion on the surface of polyurethane. The surface of the grafting layer is then coated or treated to produce an EVA synthetic leather with high bonding strength and further improved physical properties such as wear resistance and scratch resistance. Next, the EVA synthetic leather will be further described in conjunction with specific embodiments.

In the EVA synthetic leathers of Examples 7-1 to 7-10 and Comparative Example 7-1, the EVA synthetic leather substrate includes a base fabric and a radiation-crosslinked EVA layer. The preparation method may include the following steps:

1) The ingredients are formulated according to the formula design. The formula of the EVA layer is as follows:

3) EVA synthetic leather substrate is obtained after radiation crosslinking. Among them, the radiation beam is a high-energy electron beam, and the radiation dose is 90KGY.

Example 7-1

In this embodiment, the following raw materials in weight percentage are included:

The preparation method of the EVA synthetic leather of this embodiment includes the following steps:

1) Weigh according to the formula design;

2) Mix the above-mentioned raw material polyurethane prepolymer, solvent (DMF, MEK), and catalyst in advance, and then add the curing agent in batches in proportion to stir well;

3) The mixed paste is attached to the surface of the EVA synthetic leather substrate by means of screen transfer printing or roller coating, and is dried to form a grafting layer with a strong adhesion of polyurethane on the surface, with a thickness of 10 μm.

4) The surface of the graft treatment layer is coated or treated with polyurethane slurry, and after drying and drying, the thickness of the polyurethane layer is 15 μm, which can produce EVA with high bonding strength and further improved physical properties such as wear resistance and scratch resistance. Synthetic Leather.

Example 7-2

The preparation method of the surface grafting treatment layer and the corresponding EVA synthetic leather is the same as that of Example 7-1, wherein the thickness of the surface grafting treatment layer is 10 μm.

Example 7-3

The preparation method of the surface grafting treatment layer and the corresponding EVA synthetic leather is the same as that in Example 7-1, wherein the thickness of the surface grafting treatment layer is 5 μm.

Example 7-4

Example 7-5

Example 7-6

Example 7-7

Example 7-8

Examples 7-9

The preparation method of the surface grafting treatment layer and the corresponding EVA synthetic leather is the same as that of Example 7-1, wherein the thickness of the surface grafting treatment layer is 25 μm.

Example 7-10

The preparation method of the surface grafting treatment layer and the corresponding EVA synthetic leather is the same as that of Example 7-1, wherein the thickness of the surface grafting treatment layer is 40 μm.

Comparative Example 7-1

In this comparative example, the surface graft treatment layer is not coated on the surface of the EVA synthetic leather, and the polyurethane layer is directly coated, and the thickness of the polyurethane layer is 15 μm.

The properties of the synthetic leathers prepared in Examples 7-1 to 7-10 and Comparative Example 7-1 were measured, the peel strength was tested according to GB/T8949-2008, and the abrasion resistance was tested according to ASTM D 1242-1995. The results were as follows Table 7 shows.

Table 7 Performance data of each synthetic leather

It can be seen from the data in Table 7 that the surface grafting treatment agent for EVA synthetic leather of the present application, EVA synthetic leather and the preparation method thereof are used to form a grafting treatment layer with strong adhesion on the surface of polyurethane. By coating or treating the surface of the graft treatment layer, an EVA synthetic leather with high bonding strength and further improved physical properties such as wear resistance and scratch resistance can be obtained.

Unless otherwise stated, all reagents used in the examples are commercially available or synthesized according to conventional methods, and can be used directly without further processing, and the instruments used in the examples are all commercially available.

In this specification, the present application has been described with reference to its specific embodiments. However, it is clear that various modifications and changes can still be made without departing from the spirit and scope of the present application. Therefore, the description is considered to be illustrative rather than restrictive.

The above is only the specific implementation of this application, but the scope of protection of this application is not limited to this, any person skilled in the art can easily think of various equivalents within the technical scope disclosed in this application Modifications or replacements, these modifications or replacements should be covered within the scope of protection of this application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

An ethylene-vinyl acetate copolymer synthetic leather substrate includes a radiation-crosslinked ethylene-vinyl acetate copolymer layer and a base layer.
The ethylene-vinyl acetate copolymer synthetic leather substrate according to claim 1, wherein

The VA content of the raw material ethylene-vinyl acetate copolymer used in the ethylene-vinyl acetate copolymer layer is 9% to 40%, preferably 15% to 37%; and/or,

The raw material ethylene-vinyl acetate copolymer used in the ethylene-vinyl acetate copolymer layer has a melt flow rate of 0.9 g/10 min to 65 g/10 min at 190° C. and a load of 2.16 kg, preferably 2.5 g/10 min ~15g/10min.
The ethylene-vinyl acetate copolymer synthetic leather substrate according to claim 1, wherein the raw material of the ethylene-vinyl acetate copolymer layer further includes one of a cross-linking aid, an antioxidant and a colorant One or more.
The ethylene-vinyl acetate copolymer synthetic leather substrate according to claim 1, wherein the thickness of the ethylene-vinyl acetate copolymer layer is 0.1 mm to 3.0 mm.
The ethylene-vinyl acetate copolymer synthetic leather substrate according to claim 1, wherein the radiation uses high-energy electron beams, gamma rays or X-rays, and the radiation dose is 5KGY to 200KGY, preferably 20KGY to 150KGY.
The ethylene-vinyl acetate copolymer synthetic leather substrate according to claim 1, wherein the base layer is a paper base or a base cloth;

When the base layer is a base fabric, the base fabric is a knitted elastic fleece, a plain woven fleece, a knitted plain cloth, a polyester filament elastic fabric, a non-woven fabric, a woven polyester fabric, a nylon fabric, and a microfiber base fabric Any one or a combination of at least two of them.
An ethylene-vinyl acetate copolymer synthetic leather, comprising the ethylene-vinyl acetate copolymer synthetic leather substrate according to any one of claims 1 to 6.
The ethylene-vinyl acetate copolymer synthetic leather according to claim 7, wherein the ethylene-vinyl acetate copolymer synthetic leather is shoe upper leather, luggage leather, sofa leather or home furnishing interior leather.
The ethylene-vinyl acetate copolymer synthetic leather according to claim 7, wherein the ethylene-vinyl acetate copolymer synthetic leather includes a base fabric and a radiation-crosslinked ethylene-vinyl acetate copolymer in this order from bottom to top Layer, polyurethane layer.
The ethylene-vinyl acetate copolymer synthetic leather according to claim 9, wherein the ethylene-vinyl acetate copolymer synthetic leather is an ethylene-vinyl acetate copolymer layer or a polyurethane layer cross-linked by a base fabric and radiation Composed of three-layer structure.
The ethylene-vinyl acetate copolymer synthetic leather according to claim 9, wherein the total thickness of the ethylene-vinyl acetate copolymer synthetic leather is 0.5 mm to 5.5 mm, and the thickness of the base fabric is 0.3 mm to 2.2 mm The thickness of the radiation-crosslinked ethylene-vinyl acetate copolymer layer is 0.2 mm to 3.0 mm, and the thickness of the polyurethane layer is 0.005 mm to 0.3 mm.
The ethylene-vinyl acetate copolymer synthetic leather according to claim 7, wherein the ethylene-vinyl acetate copolymer synthetic leather includes a paper base, a radiation-crosslinked ethylene-vinyl acetate copolymer layer and a polyurethane layer.
The ethylene-vinyl acetate copolymer synthetic leather according to claim 12, wherein the total thickness of the ethylene-vinyl acetate copolymer synthetic leather is 0.15 mm to 0.55 mm, and the thickness of the paper base is 0.10 mm to 0.25 mm, the thickness of the ethylene-vinyl acetate copolymer layer is 0.04 mm to 0.25 mm, and the thickness of the polyurethane layer is 0.01 mm to 0.05 mm.
The ethylene-vinyl acetate copolymer synthetic leather according to claim 12, wherein the basis weight of the paper base is 80 g/m 2 to 200 g/m 2 .
The ethylene-vinyl acetate copolymer synthetic leather according to claim 12, wherein the ethylene-vinyl acetate copolymer layer comprises 100 parts of ethylene-vinyl acetate copolymer resin, 0 to 100 parts of polyolefin resin, and 0 to 6 parts of crosslinking agent, 0 to 200 parts of filler and 0 to 20 parts of colorant.
The ethylene-vinyl acetate copolymer synthetic leather according to claim 15, wherein the polyolefin resin comprises one or more of ethylene-octene copolymer, ethylene-butene copolymer and polyethylene combination.
The ethylene-vinyl acetate copolymer synthetic leather according to claim 12, wherein the degree of crosslinking of the ethylene-vinyl acetate copolymer layer after radiation crosslinking is 1% to 90%, preferably 1% to 70 %.
The ethylene-vinyl acetate copolymer synthetic leather according to claim 7, wherein the ethylene-vinyl acetate copolymer synthetic leather is a composite of multi-layer co-extruded ethylene-vinyl acetate copolymer resin foamed and cross-linked Leather, the synthetic leather comprises a polyurethane layer, a multi-layer co-extruded ethylene-vinyl acetate copolymer layer and a base layer attached to the multi-layer co-extruded ethylene-vinyl acetate copolymer layer in order from top to bottom, The multi-layer co-extruded ethylene-vinyl acetate copolymer layer is foamed and cross-linked, and includes at least one modified layer and at least one foamed layer, and the polyurethane layer closely adheres to the modified layer.
The ethylene-vinyl acetate copolymer synthetic leather according to claim 18, wherein the foaming layer contains 100 parts of an ethylene-vinyl acetate copolymer resin, 1 to 15 parts of a foaming agent, and 0 to 4 parts Cross-linking agent, 0-100 parts of elastomer, 0-200 parts of filler, 0-10 parts of foam accelerator, 0-5 parts of lubricant, 0-20 parts of colorant.
The ethylene-vinyl acetate copolymer synthetic leather according to claim 18, wherein the modified layer contains 100 parts of ethylene-vinyl acetate copolymer resin, 0 to 100 parts of elastomer, and 0 to 200 parts Filler, 0 to 4 parts of crosslinking agent, 0 to 4 parts of auxiliary crosslinking agent, 0 to 20 parts of colorant.
The ethylene-vinyl acetate copolymer synthetic leather according to claim 19 or 20, wherein the cross-linking agent includes but is not limited to dicumyl peroxide, di-tert-butyl dicumyl peroxide, 1, 1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane and 4,4 -One or more of n-butyl di(tert-butylperoxy)valerate.
The ethylene-vinyl acetate copolymer synthetic leather according to claim 18, wherein the degree of crosslinking of the ethylene-vinyl acetate copolymer layer is 3% to 95%.
The ethylene-vinyl acetate copolymer synthetic leather according to claim 18, wherein the foaming and cross-linking treatment is foaming by radiation cross-linking treatment or radiation cross-linking treatment after foaming.
The ethylene-vinyl acetate copolymer synthetic leather according to claim 18, wherein the polyurethane layer is a solvent-based, water-based or solvent-free polyurethane coating.
The ethylene-vinyl acetate copolymer synthetic leather according to claim 18, wherein the total thickness of the synthetic leather is 0.21 mm to 5.3 mm, the thickness of the base layer is 0.1 mm to 2.2 mm, and multi-layer coextrusion foam The thickness of the ethylene-vinyl acetate copolymer layer is 0.1 mm to 3.0 mm, wherein the thickness of the modified layer is 0.01 mm to 1.0 mm, and the thickness of the polyurethane layer is 0.01 mm to 0.10 mm.
The ethylene-vinyl acetate copolymer synthetic leather according to claim 7, wherein the ethylene-vinyl acetate copolymer synthetic leather includes a base fabric and a radiation-crosslinked ethylene-vinyl acetate copolymer in this order from bottom to top Layer, surface grafting treatment layer, polyurethane layer.
The ethylene-vinyl acetate copolymer synthetic leather according to claim 26, wherein the ethylene-vinyl acetate copolymer synthetic leather is composed of a base fabric, a radiation-crosslinked ethylene-vinyl acetate copolymer layer, and a surface contact Four-layer structure consisting of branch treatment layer and polyurethane layer.
The ethylene-vinyl acetate copolymer synthetic leather according to claim 26, wherein the total thickness of the ethylene-vinyl acetate copolymer synthetic leather is 0.5 mm to 5.5 mm, and the thickness of the base fabric is 0.3 mm to 2.2 mm The thickness of the radiation-crosslinked ethylene-vinyl acetate copolymer layer is 0.19 mm to 3.0 mm, the thickness of the surface graft treatment layer is 0.005 mm to 0.04 mm, and the thickness of the polyurethane layer is 0.005 mm to 0.26 mm.
The ethylene-vinyl acetate copolymer synthetic leather according to claim 26, wherein the content of the ethylene-vinyl acetate copolymer in the ethylene-vinyl acetate copolymer layer is greater than 50 wt%.
The ethylene-vinyl acetate copolymer synthetic leather according to claim 26, wherein the degree of crosslinking of the ethylene-vinyl acetate copolymer layer after radiation crosslinking is greater than 20%.
The ethylene-vinyl acetate copolymer synthetic leather according to claim 26, wherein the surface graft treatment layer is formed of an aqueous or solvent-free polyurethane surface graft treatment agent.
The ethylene-vinyl acetate copolymer synthetic leather according to claim 26 or 31, wherein the surface graft treatment layer is formed of a solventless polyurethane surface graft treatment agent, and the solventless polyurethane surface is grafted The branching agent includes 36 wt% to 80 wt% polyurethane prepolymer with isocyanate end groups, 14 wt% to 58 wt% polyol prepolymer with hydroxyl end groups, 0.1 wt% dibutyltin dilaurate catalyst, 0.5 wt% leveling Agent, 0.5wt% wetting viscosity reducer and 4.9wt% plasticizer.
The ethylene-vinyl acetate copolymer synthetic leather according to claim 26 or 31, wherein the surface graft treatment layer is formed of an aqueous polyurethane surface graft treatment agent, and the aqueous polyurethane surface graft treatment agent includes 40 wt% ～70wt% waterborne polyurethane with hydroxyl end groups, 2wt%～7wt% prepolymer crosslinker with isocyanate ends, 21.8wt%～56.8wt% water, 0.3wt% thickener, 0.3wt% wetting agent , 0.1wt% defoamer and 0.5wt% film-forming agent.
The ethylene-vinyl acetate copolymer synthetic leather according to claim 26, wherein the main resin of the polyurethane layer is water-based polyurethane or solvent-free polyurethane.
The ethylene-vinyl acetate copolymer synthetic leather according to claim 26, wherein the thickness of the surface graft treatment layer is 5 μm to 40 μm, and the thickness of the polyurethane layer is 15 μm to 100 μm.
The ethylene-vinyl acetate copolymer synthetic leather according to claim 26, wherein the surface graft treatment layer is formed of a surface graft treatment agent, and the surface graft treatment agent includes 50 wt% to 82.4 wt% of end groups Polyurethane prepolymer containing active groups, 2.5wt% to 15wt% curing agent, 5wt% to 15wt% dimethylformamide, 10wt% to 19wt% butanone and 0.1wt% to 1wt% dibutyltin dilaurate catalyst .
The ethylene-vinyl acetate copolymer synthetic leather according to claim 36, wherein the active group in the polyurethane prepolymer containing active groups at the end groups is one or more of hydroxyl group, amino group and carboxyl group.
The ethylene-vinyl acetate copolymer synthetic leather according to claim 36, wherein the curing agent is a curing agent whose terminal group is isocyanate, and the functionality is 1.5 to 3.5.
The ethylene-vinyl acetate copolymer synthetic leather according to claim 36, wherein the content of the polyurethane prepolymer containing reactive groups at the end groups is 60wt% to 70wt%; the content of the curing agent is 5wt% to 10wt% .
The ethylene-vinyl acetate copolymer synthetic leather according to claim 36, wherein the thickness of the surface graft treatment layer is 5 μm to 40 μm.
A surface grafting treatment agent for ethylene-vinyl acetate copolymer synthetic leather, including 50 wt% to 82.4 wt% polyurethane prepolymer with active groups at the end groups, 2.5 wt% to 15 wt% curing agent, 5 wt% ~15wt% dimethylformamide, 10wt%~19wt% butanone and 0.1wt%~1wt% dibutyltin dilaurate catalyst.
The surface grafting treatment agent according to claim 41, wherein the active group in the polyurethane prepolymer containing an active group at the end group is one or more of a hydroxyl group, an amino group, or a carboxyl group.
The surface graft treatment agent according to claim 41, wherein the curing agent is a curing agent whose terminal group is an isocyanate, and the functionality is 1.5 to 3.5.
The surface grafting treatment agent according to claim 41, wherein the content of the polyurethane prepolymer containing reactive groups at the end groups is 60wt% to 70wt%; and the content of the curing agent is 5wt% to 10wt%.