High-temperature-resistant foaming material for shoe body

Abstract

The invention relates to the technical field of foaming materials, and discloses a high-temperature-resistant foaming material for shoes, and the foaming material comprises the following raw materials: an ethylene-vinyl acetate copolymer, an ethylene-octylene random copolymer, a cross-linking agent, a high-temperature-resistant filler and talcum powder. According to the present invention, the prepared foaming material can form the winding cross-linked network structure with the ethylene-vinyl acetate copolymer matrix molecular chain, and extends to each region of the matrix material, such that the prepared foaming material has characteristics of excellent wear resistance, excellent mechanical property and excellent high temperature resistance, and can effectively avoid the shrinkage or deformation of the foaming material in the high temperature environment, stable shape, size and performance can be maintained, so that the service life of the shoe body is prolonged, and the application range of the foaming material for the shoe body is widened.

Description

Technical Field

[0001] The invention relates to the technical field of foaming materials, and in particular to a high-temperature resistant foaming material for a shoe body. Background Art

[0002] Shoes play an indispensable role in people's daily lives. Among them, foam shoe materials have low density, are relatively light, and have excellent cushioning capacity. They can absorb and disperse the impact force received by the feet, so that the knees and feet can bear less pressure during movement and reduce the risk of injury. At the same time, they are relatively soft and can fit the feet, reduce pressure and friction, and are more comfortable to wear. They can also be made into a variety of styles through molds to meet the different needs of consumers and are widely favored by consumers. Currently, commonly used foam shoe materials include ethylene-vinyl acetate copolymer (EVA), thermoplastic polyurethane elastomer (TPU), polyvinyl chloride (PVC), polyurethane (PU), polyethylene (PE) and ethylene acrylate copolymer foam, etc.

[0003] Among them, shoes made of ethylene-vinyl acetate copolymer (EVA) foam material have excellent softness, elasticity, chemical stability and anti-aging performance, and are widely popular in the market. However, in a high temperature environment, the molecular chain of ethylene-vinyl acetate copolymer (EVA) foam material is prone to thermal motion, and it is easy to soften, expand or even shrink and deform, resulting in dimensional instability, affecting the appearance, comfort, wearing experience and service life of the shoes. Therefore, the improvement of the high temperature resistance of ethylene-vinyl acetate copolymer (EVA) foam material is of great practical significance. The patent with publication number CN112778621B discloses a method for making The invention discloses a composition of a high-elastic memory EVA composite foam material for sports shoe soles and a preparation method thereof, comprising the following raw materials: ethylene-vinyl acetate copolymer, polyolefin elastomer, olefin block copolymer, hydrogenated styrene elastomer, isotactic polybutene, ethylene propylene diene monomer rubber, an active agent, a crosslinking agent, a foaming agent, and a crosslinking auxiliary agent. The composition can be used to obtain an ideal foam material, which has the advantages of excellent recovery performance, excellent anti-buffering performance, etc., and is durable and comfortable to wear. However, the patent still has shortcomings in practical applications, and the instability of the foam material in a high-temperature environment is not taken into account. Therefore, the invention provides a high-temperature resistant foam material, which can be used for shoe body manufacturing, thereby broadening the application range of the foam material for shoe bodies. Summary of the invention

[0004] In order to solve the problems in the background technology, an object of the present invention is to provide a high temperature resistant foaming material for a shoe body.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A high temperature resistant foaming material for a shoe body comprises the following raw materials in parts by weight: 45-65 parts of ethylene-vinyl acetate copolymer, 15-35 parts of ethylene-octene random copolymer, 0.5-2 parts of a cross-linking agent, 3-6 parts of a high temperature resistant filler, and 2-5 parts of talc.

[0007] Furthermore, the cross-linking agent is 1,4-di-tert-butyl peroxyisopropylbenzene or diisopropylbenzene peroxide.

[0008] Furthermore, the preparation method of the high temperature resistant filler is as follows:

[0009] Add glycidyl ether POSS to toluene, and form a uniform and stable suspension after ultrasonic dispersion. Then add terminal hydroxyl liquid styrene butadiene rubber to the suspension, stir and mix evenly, increase the temperature to 65-85°C, add a catalyst, stir and react for 6-8h, remove the solvent under reduced pressure, separate the product, wash, and dry to obtain a high temperature resistant filler.

[0010] By adopting the above technical scheme, the epoxy group contained in the glycidyl ether-based POSS can react with the hydroxyl group in the hydroxyl-terminated liquid styrene-butadiene rubber under the action of a catalyst to obtain a high-temperature resistant filler. The high temperature resistant filler prepared by the present invention contains POSS, has a cage-type skeleton structure, high bond energy, high structural symmetry, is difficult to be destroyed at high temperature, has excellent high temperature resistance, and is added to an ethylene-vinyl acetate copolymer matrix to effectively improve the high temperature resistance of the matrix. In addition, the high temperature resistant filler has a branched structure and an unsaturated olefin group, and can form an entangled cross-linked network structure with a matrix molecular chain under the action of a cross-linking agent. A large number of branching points and flexible branches can extend to various regions of the material, thereby enhancing the interface bonding force with the matrix. The POSS is fixed in the ethylene-vinyl acetate copolymer matrix, and a large amount of energy can be absorbed and dispersed when impacted by external force, so that the high strength advantage of the POSS can be fully utilized and the mechanical properties of the material can be improved. In addition, the styrene-butadiene rubber also has excellent wear resistance. After forming a cross-linked network with the matrix, the compactness of the matrix molecular chain is enhanced, and the high temperature resistance and wear resistance of the material can be further enhanced, thereby effectively avoiding the shrinkage or deformation of the foaming material, and the original shape, size and performance can be maintained for a long time, thereby extending the service life of the shoe body.

[0011] Furthermore, the ultrasonic dispersion frequency is 40-50kHz, the power is 80-100W, and the time is 3-6min.

[0012] Furthermore, the catalyst is boron trifluoride etherate.

[0013] Furthermore, the average relative molecular mass of the hydroxyl-terminated liquid styrene-butadiene rubber is 2500.

[0014] A method for preparing a high temperature resistant foam material for a shoe body comprises the following steps:

[0015] Step 1: adding ethylene-vinyl acetate copolymer, ethylene-octene random copolymer, crosslinking agent, high temperature resistant filler and talcum powder into a twin-screw extruder, blending at 100-130° C., and granulating by melt extrusion to obtain a mixed base material;

[0016] Step 2: Add the mixed base material into the mold, close the mold, heat and pressurize, the molding temperature is 150-175°C, after 15-30 minutes, cool to room temperature to obtain the mixed base material blank;

[0017] Step 3: Move the mixed base material blank to a high-pressure reactor, introduce a supercritical fluid, increase the temperature and pressure, perform supercritical foaming, and then quickly release the pressure to obtain a foamed material.

[0018] Furthermore, in step three, the supercritical fluid is a mixed gas of one or both of carbon dioxide and nitrogen, with a temperature of 180-200° C., a pressure of 15-30 MPa, and a pressure release rate of 10-20 MPa.

[0019] Beneficial effects of the present invention:

[0020] The present invention prepares high-temperature resistant fillers and adds them into the preparation process of the foaming material, so that the prepared foaming material has excellent wear resistance and mechanical properties, wherein the best wear scar length in the wear resistance test is 8.2 mm, the best compression permanent deformation rate is 10%, and the best tensile strength is 4.2 MPa. At the same time, the high-temperature resistance is excellent, which can prevent the foaming material from shrinking or deforming in a high-temperature environment, so that the foaming material can maintain a stable shape, size and performance, thereby extending the service life of the shoe body and broadening the application range of the foaming material for the shoe body.

[0021] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0023] Figure 1 This is a thermal gravimetric curve of the glycidyl ether-based POSS and the high temperature resistant filler in Example 1 of the present invention. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Example 1

[0026] Preparation of high temperature resistant filler

[0027] 6 g of glycidyl ether POSS was added to toluene, and ultrasonic dispersion was carried out at a frequency of 45 kHz and a power of 90 W for 5 minutes to form a uniform and stable suspension. Then, 3.4 g of terminal hydroxyl liquid styrene butadiene rubber with an average relative molecular mass of 2500 was added to the suspension. After stirring and mixing evenly, the temperature was raised to 80°C, 0.6 g of boron trifluoride ether was added, and the mixture was stirred for 8 hours. The solvent was removed under reduced pressure, the product was separated, washed, and dried to obtain a high temperature resistant filler.

[0028] Weigh 0.5 g of glycidyl ether-based POSS and high temperature resistant filler, and use TA-50 thermogravimetric analyzer to perform thermogravimetric test. Figure 1 Figure 3 is the thermal weight loss curve of glycidyl ether POSS and high temperature resistant filler. Analysis shows that glycidyl ether POSS shows obvious weight loss at around 400°C, and high temperature resistant filler shows relatively obvious weight loss at around 250°C and 380°C. This is probably due to the decomposition of the terminal hydroxyl liquid styrene butadiene rubber grafted with glycidyl ether POSS at high temperature.

[0029] Example 2

[0030] Preparation of foaming materials

[0031] Step 1: Add 45g of ethylene-vinyl acetate copolymer, 15g of ethylene-octene random copolymer, 0.5g of dicumyl peroxide, 3g of the high temperature resistant filler prepared in Example 1, and 2g of talcum powder into a twin-screw extruder, blend at 100°C, and granulate by melt extrusion to obtain a mixed base material;

[0032] Step 2: Add the mixed base material into the mold, close the mold, heat and pressurize, the molding temperature is 150°C, after 15 minutes, cool to room temperature to obtain the mixed base material blank;

[0033] Step 3: Move the mixed base material into a high-pressure reactor, introduce supercritical fluid carbon dioxide, increase the temperature to 180°C and the pressure to 15MPa, perform supercritical foaming, and then quickly release the pressure at a rate of 10MPa to obtain a foamed material.

[0034] Example 3

[0035] Preparation of foaming materials

[0036] Step 1: Add 50g of ethylene-vinyl acetate copolymer, 20g of ethylene-octene random copolymer, 1g of dicumyl peroxide, 4g of the high temperature resistant filler prepared in Example 1, and 3g of talcum powder into a twin-screw extruder, blend at 110°C, and granulate by melt extrusion to obtain a mixed base material;

[0037] Step 2: Add the mixed base material into the mold, close the mold, heat and pressurize, the molding temperature is 160°C, after 20 minutes, cool to room temperature to obtain the mixed base material blank;

[0038] Step 3: Move the mixed base material into a high-pressure reactor, introduce supercritical fluid carbon dioxide, increase the temperature to 190°C and the pressure to 20MPa, perform supercritical foaming, and then quickly release the pressure at a rate of 15MPa to obtain a foamed material.

[0039] Example 4

[0040] Preparation of foaming materials

[0041] Step 1: Add 55g of ethylene-vinyl acetate copolymer, 25g of ethylene-octene random copolymer, 1.5g of dicumyl peroxide, 5g of the high temperature resistant filler prepared in Example 1, and 4g of talc powder into a twin-screw extruder, blend at 120°C, and granulate by melt extrusion to obtain a mixed base material;

[0042] Step 2: Add the mixed base material into the mold, close the mold, heat and pressurize, the molding temperature is 170°C, after 25 minutes, cool to room temperature to obtain the mixed base material blank;

[0043] Step 3: Move the mixed base material to a high-pressure reactor, introduce supercritical fluid carbon dioxide, increase the temperature to 195°C and the pressure to 25MPa, perform supercritical foaming, and then quickly release the pressure at a rate of 15MPa to obtain a foamed material.

[0044] Example 5

[0045] Preparation of foaming materials

[0046] Step 1: Add 65g of ethylene-vinyl acetate copolymer, 35g of ethylene-octene random copolymer, 2g of dicumyl peroxide, 6g of the high temperature resistant filler prepared in Example 1, and 5g of talcum powder into a twin-screw extruder, blend at 130°C, and granulate by melt extrusion to obtain a mixed base material;

[0047] Step 2: Add the mixed base material into the mold, close the mold, heat and pressurize, the molding temperature is 175°C, after 30 minutes, cool to room temperature to obtain the mixed base material blank;

[0048] Step 3: Move the mixed base material blank to a high-pressure reactor, introduce supercritical fluid carbon dioxide, increase the temperature to 200°C and the pressure to 30MPa, perform supercritical foaming, and then quickly release the pressure at a rate of 20MPa to obtain a foamed material.

[0049] Comparative Example 1

[0050] Preparation of foaming materials

[0051] Step 1: Add 50g of ethylene-vinyl acetate copolymer, 20g of ethylene-octene random copolymer, 1g of diisopropylbenzene peroxide, 4g of glycidyl ether POSS, and 3g of talc into a twin-screw extruder, blend at 110°C, and granulate by melt extrusion to obtain a mixed base material;

[0052] Step 2: Add the mixed base material into the mold, close the mold, heat and pressurize, the molding temperature is 160°C, after 20 minutes, cool to room temperature to obtain the mixed base material blank;

[0053] Step 3: Move the mixed base material into a high-pressure reactor, introduce supercritical fluid carbon dioxide, increase the temperature to 190°C and the pressure to 20MPa, perform supercritical foaming, and then quickly release the pressure at a rate of 15MPa to obtain a foamed material.

[0054] Comparative Example 2

[0055] Preparation of foaming materials

[0056] Step 1: Add 50g of ethylene-vinyl acetate copolymer, 20g of ethylene-octene random copolymer, 1g of dicumyl peroxide, and 3g of talc into a twin-screw extruder, blend at 110°C, and granulate by melt extrusion to obtain a mixed base material;

[0057] Step 2: Add the mixed base material into the mold, close the mold, heat and pressurize, the molding temperature is 160°C, after 20 minutes, cool to room temperature to obtain the mixed base material blank;

[0058] Step 3: Move the mixed base material into a high-pressure reactor, introduce supercritical fluid carbon dioxide, increase the temperature to 190°C and the pressure to 20MPa, perform supercritical foaming, and then quickly release the pressure at a rate of 15MPa to obtain a foamed material.

[0059] Performance Testing

[0060] The foamed materials prepared in Examples 2 to 5 and Comparative Examples 1 to 2 were prepared into samples that met the test specifications, and the high temperature resistance of the samples was tested by the following method: the samples were placed in a vacuum oven at 120° C. for 6 hours, and the appearance changes of the samples were observed; the wear resistance of the samples was tested according to the standard GB / T 3903.2-2017; the compression performance of the samples was tested according to the standard GB / T 6669-2008; the tensile strength of the samples was tested according to the standard GB / T 6344-2008; the test results of each test are shown in the following table:

[0061]

[0062] It can be seen from the analysis of the above table that the foamed materials prepared by Examples 2 to 5 of the present invention have excellent wear resistance, mechanical properties and high temperature resistance. Comparative Example 1 adds a glycidyl ether-based POSS, which cannot be cross-linked with the ethylene-vinyl acetate copolymer matrix material, and has poor improvement effects on high temperature resistance and mechanical properties, and cannot utilize terminal hydroxy-butadiene styrene rubber to enhance the wear resistance of the foamed material. Comparative Example 2 does not add high temperature resistant filler, so the wear resistance, mechanical properties and high temperature resistance test results are all poor.

[0063] The above contents are merely examples and explanations of the concept of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A high temperature resistant foam material for a shoe body, characterized in that: The invention comprises the following raw materials in parts by weight: 45-65 parts of ethylene-vinyl acetate copolymer, 15-35 parts of ethylene-octene random copolymer, 0.5-2 parts of crosslinking agent, 3-6 parts of high temperature resistant filler and 2-5 parts of talc powder.

2. The high temperature resistant foam material for shoe body according to claim 1, characterized in that: The cross-linking agent is 1,4-di-tert-butyl peroxyisopropylbenzene or diisopropylbenzene peroxide.

3. The high temperature resistant foam material for a shoe body according to claim 1, characterized in that: The preparation method of the high temperature resistant filler is as follows: Add glycidyl ether POSS to toluene, and form a uniform and stable suspension after ultrasonic dispersion. Then add terminal hydroxyl liquid styrene butadiene rubber to the suspension, stir and mix evenly, increase the temperature to 65-85°C, add a catalyst, stir and react for 6-8h, remove the solvent under reduced pressure, separate the product, wash, and dry to obtain a high temperature resistant filler.

4. The high temperature resistant foam material for shoe body according to claim 3, characterized in that: The ultrasonic dispersion frequency is 40-50kHz, the power is 80-100W, and the time is 3-6min.

5. The high temperature resistant foam material for shoe body according to claim 3, characterized in that: The catalyst is boron trifluoride etherate.

6. The high temperature resistant foam material for shoe body according to claim 3, characterized in that: The average relative molecular mass of the hydroxyl-terminated liquid styrene-butadiene rubber is 2500.

7. The method for preparing a high temperature resistant foam material for a shoe body according to claim 1, characterized in that: The following steps are involved: Step 1: adding ethylene-vinyl acetate copolymer, ethylene-octene random copolymer, crosslinking agent, high temperature resistant filler and talcum powder into a twin-screw extruder, blending at 100-130° C., and granulating by melt extrusion to obtain a mixed base material; Step 2: Add the mixed base material into the mold, close the mold, heat and pressurize, the molding temperature is 150-175°C, after 15-30 minutes, cool to room temperature to obtain the mixed base material blank; Step 3: Move the mixed base material blank to a high-pressure reactor, introduce a supercritical fluid, increase the temperature and pressure, perform supercritical foaming, and then quickly release the pressure to obtain a foamed material.

8. The method for preparing a high temperature resistant foam material for a shoe body according to claim 7, characterized in that: In step three, the supercritical fluid is a mixed gas of one or both of carbon dioxide and nitrogen, with a temperature of 180-200° C., a pressure of 15-30 MPa, and a pressure release rate of 10-20 MPa.

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