Wear-resistant lightweight EVA foam material and its application

Abstract

The present invention relates to the field of shoe material technology, and specifically discloses a wear-resistant lightweight EVA foam material, which is formed by supercritical foaming of the following components in parts by weight: 80-100 parts of modified EVA, 10-15 parts of POE, 0.5-1.0 parts of a cross-linking agent, 2.0-3.0 parts of zinc stearate, 1.0-1.5 parts of activated zinc oxide, 0.3-0.6 parts of stearic acid, and 3-5 parts of titanium dioxide. The present invention produces a low-density lightweight material while greatly enhancing wear resistance and wear-resistant stability without increasing the amount of siloxane used; the network structure formed by the epoxysiloxane / HTPB / maleic anhydride grafted EVA in the modified EVA of the present invention and the microporous chain network structure of the EVA / POE cross-linked synergistically enhance the foam material, having excellent tensile strength and tear strength.

Description

Technical Field

[0001] The present invention relates to the technical field of shoe materials, and in particular to a wear-resistant and lightweight EVA foam material and an application thereof. Background Art

[0002] In the field of daily necessities and sports equipment, EVA (ethylene-vinyl acetate copolymer) rubber and plastic products are new environmentally friendly plastic foam materials with good cushioning, shock resistance, heat insulation, moisture resistance, chemical corrosion resistance, non-toxicity, and non-water absorption. Therefore, they are often used in slippers, insoles, cushions, seat cushions, basketballs, footballs, etc.

[0003] EVA soles are an important functional component of shoes and come into direct contact with the ground, so high requirements are placed on their wear resistance. Patent CN103242584B discloses a wear-resistant EVA sole material. This wear-resistant material includes 65-85% ethylene-vinyl acetate copolymer, 5%-10% anti-wear agent, 0.5%-5% light stabilizer, 5%-20% inorganic filler, 1%-3% foaming agent, 0.5%-2% cross-linking agent, and 1%-3% dispersing lubricant. Ultra-high molecular weight organosilicon polymers with a molecular weight between 800,000 and 1,000,000 are used as wear-resistant additives to produce an EVA sole material with excellent wear resistance. The EVA sole material has a density of 0.202 g / cm³ and a hardness of 59D, and a DIN wear resistance of 123 mm³. However, existing technologies all achieve wear resistance by adding large amounts of wear-resistant additives, which generally suffer from poor dispersibility, unstable wear resistance, surface wrinkling, and poor adhesion to other soles. Summary of the Invention

[0004] The invention aims to provide a wear-resistant and lightweight EVA foam material, which has low density, good wear resistance and mechanical properties, no wrinkles on the surface and good adhesion to the shoe upper.

[0005] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0006] The wear-resistant and lightweight EVA foam material is prepared by supercritical foaming of the following components in parts by weight: 80-100 parts of modified EVA, 10-15 parts of POE, 0.5-1.0 parts of a cross-linking agent, 2.0-3.0 parts of zinc stearate, 1.0-1.5 parts of activated zinc oxide, 0.3-0.6 parts of stearic acid and 3-5 parts of titanium dioxide.

[0007] Preferably, the cross-linking agent is di-tert-butylcumyl peroxide and dicumyl peroxide, or a mixture of both.

[0008] Preferably, the modified EVA is prepared from EVA raw material, maleic anhydride-grafted EVA, HTPB, an epoxy-modified organosiloxane emulsion, and a tertiary amine catalyst. The maleic anhydride-grafted EVA, HTPB, and epoxy-modified organosiloxane emulsion are in equal molar amounts. The maleic anhydride-grafted EVA is added in an amount of 10% to 12% of the EVA raw material, and the tertiary amine catalyst is added in an amount of 5% to 10% of the epoxy-modified organosiloxane emulsion. Preferably, the tertiary amine catalyst is pyridine.

[0009] Preferably, the preparation method of the modified EVA specifically comprises the following steps:

[0010] S11, according to the formula, put EVA material and maleic anhydride grafted EVA into an internal mixer, mix for 10 minutes to 20 minutes, add tertiary amine catalyst and continue mixing evenly to obtain a mixed EVA material;

[0011] S12, putting the mixed EVA material and HTPB obtained in step S11 into a twin-screw extruder, setting the temperature of each section to: 60°C to 80°C / 90°C to 100°C / 120°C to 140°C / 80°C to 100°C, and then putting it into the twin-screw extruder again after extrusion to cycle the reaction 2 to 3 times to complete the reaction between HTPB and maleic anhydride grafted EVA to obtain a first-grade EVA modified material;

[0012] S13, adding the first-level EVA modified material and the epoxy-modified organosiloxane emulsion into an internal mixer at a mixing temperature of 120° C. to 130° C. for 20 min to 30 min to obtain a second-level EVA modified material;

[0013] S14, refining and extruding the secondary EVA modified material in step S13 to obtain modified EVA.

[0014] The present invention also provides application of the wear-resistant and lightweight EVA foam material on the sole.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The present invention uses modified EVA and POE as the main rubber-plastic base materials of the foaming material, forms a cross-linked network during the cross-linking foaming process, and simultaneously uses a specific grafting modification process to increase the molecular branched structure of the EVA, thereby enhancing the polarity of the EVA and reducing the crystallinity, making the material surface less prone to wrinkling and generating excellent bonding strength with hydroxyl-rich upper fibers. On the other hand, maleic anhydride is grafted onto the EVA to ensure good compatibility between HTPB and EVA, while allowing the HTPB to react with the maleic anhydride-grafted EVA to generate hydroxyl groups capable of ring-opening reaction with an epoxy-modified organic silicone emulsion, thereby allowing the silicone groups to be dispersedly grafted into the EVA, thereby accelerating the carbon dioxide infiltration and saturation time and achieving a high foaming ratio during the supercritical foaming process. In combination with the supercritical foaming process, a low-density and lightweight material is produced, while greatly enhancing the wear resistance and wear-resistant stability without increasing the amount of silicone used. The network structure formed by the epoxysiloxane / HTPB / maleic anhydride grafted EVA in the modified EVA of the present invention and the EVA / POE cross-linking synergistically enhance the microporous chain network structure of the foaming material, thereby having excellent tensile strength and tear strength. DETAILED DESCRIPTION

[0017] Example 1

[0018] This embodiment provides a wear-resistant and lightweight EVA foam material, which is used as a sole material. The EVA foam material is supercritically foamed by the following components in parts by weight: 90 parts of modified EVA, 10 parts of POE, 0.5 parts of dicumyl peroxide, 2.5 parts of zinc stearate, 1.0 parts of activated zinc oxide, 0.5 parts of stearic acid and 3 parts of titanium dioxide.

[0019] The modified EVA is prepared from Formosa Plastics 7470M with a VA content of 26%, maleic anhydride-grafted EVA KT-26, hydroxy-terminated polybutadiene HTPB with an average relative molecular weight of 3000, epoxy-modified organic silicone emulsion LK-636, and pyridine. The maleic anhydride-grafted EVA, HTPB, and epoxy-modified organic silicone emulsion are in equal molar amounts. The amount of maleic anhydride-grafted EVA added is 10% of the EVA material, and the amount of tertiary amine catalyst added is 8% of the epoxy-modified organic silicone emulsion.

[0020] The supercritical foaming process of the EVA foam material specifically includes the following steps:

[0021] S1, prepare modified EVA, specifically:

[0022] S11, EVA material and maleic anhydride grafted EVA are put into an internal mixer, and after internal mixing for 20 minutes, a tertiary amine catalyst is added and continued to mix evenly to obtain a mixed EVA material;

[0023] S12, putting the mixed EVA material and HTPB obtained in step S11 into a twin-screw extruder, setting the temperature of each section to: 80°C / 100°C / 135°C / 90°C, and then putting it into the twin-screw extruder again after extrusion to cycle the reaction twice to complete the reaction between HTPB and maleic anhydride grafted EVA to obtain a first-grade EVA modified material;

[0024] S13, adding the first-level EVA modified material and the epoxy-modified organosiloxane emulsion into an internal mixer at a mixing temperature of 130° C. for 30 min to obtain a second-level EVA modified material;

[0025] S14, refining and extruding the secondary EVA modified material in step S13 to obtain modified EVA;

[0026] S2, extrusion granulation: according to the formula, the modified EVA, POE, dicumyl peroxide, zinc stearate, activated zinc oxide, stearic acid and titanium dioxide of step S1 are added into the screw extruder B, the mixture is melted, and the mixture is extruded and granulated to obtain EVA masterbatch;

[0027] S3, cross-linking reaction: adding the EVA masterbatch of step S2 into the forming mold, closing the mold, heating and pressing to obtain the EVA base;

[0028] S4. Supercritical foaming: The cooled EVA base was placed in a high-pressure reactor, supercritical fluid carbon dioxide was introduced, and the temperature and pressure were increased to perform supercritical foaming at a temperature of 165°C and a pressure of 25 MPa for 40 min. The pressure was then rapidly released at a pressure release rate of 10 MPa / s to obtain an EVA foam material.

[0029] Example 2

[0030] The present embodiment provides a wear-resistant and lightweight EVA foam material, which is used as a sole material. The EVA foam material is supercritically foamed from the following components in parts by weight: 80 parts of modified EVA, 15 parts of POE, 1.0 part of di-tert-butyl peroxide isopropyl benzene, 2.0 parts of zinc stearate, 1.5 parts of activated zinc oxide, 0.5 parts of stearic acid and 4 parts of titanium dioxide.

[0031] The modified EVA is prepared from UE3312 with a VA content of 33%, maleic anhydride grafted EVA KT-26, hydroxy-terminated polybutadiene HTPB with an average relative molecular weight of 2000, epoxy-modified organic silicone emulsion LK-636, and pyridine. The maleic anhydride grafted EVA, HTPB, and epoxy-modified organic silicone emulsion are in equal molar amounts. The amount of maleic anhydride grafted EVA added is 12% of the EVA material, and the amount of tertiary amine catalyst added is 10% of the epoxy-modified organic silicone emulsion.

[0032] The supercritical foaming process of the EVA foam material specifically includes the following steps:

[0033] S1, prepare modified EVA, specifically:

[0034] S11, EVA material and maleic anhydride grafted EVA are put into an internal mixer, and after internal mixing for 20 minutes, a tertiary amine catalyst is added and continued to mix evenly to obtain a mixed EVA material;

[0035] S12, putting the mixed EVA material and HTPB obtained in step S11 into a twin-screw extruder, setting the temperature of each section to: 70°C / 95°C / 140°C / 100°C, and then putting it into the twin-screw extruder again after extrusion to cycle the reaction twice to complete the reaction between HTPB and maleic anhydride grafted EVA to obtain a first-grade EVA modified material;

[0036] S13, adding the first-level EVA modified material and the epoxy-modified organosiloxane emulsion into an internal mixer at a mixing temperature of 125° C. for 30 min to obtain a second-level EVA modified material;

[0037] S14, refining and extruding the secondary EVA modified material in step S13 to obtain modified EVA;

[0038] S2, extrusion granulation: according to the formula, the modified EVA, POE, di-tert-butyl peroxide isopropyl benzene, zinc stearate, activated zinc oxide, stearic acid and titanium dioxide of step S1 are added into the screw extruder B, the mixture is melted, and the mixture is extruded and granulated to obtain EVA masterbatch;

[0039] S3, cross-linking reaction: adding the EVA masterbatch of step S2 into the forming mold, closing the mold, heating and pressing to obtain the EVA base;

[0040] S4. Supercritical foaming: The cooled EVA base was placed in a high-pressure reactor, supercritical fluid carbon dioxide was introduced, and the temperature and pressure were increased to perform supercritical foaming at a temperature of 165°C and a pressure of 25 MPa for 40 min. The pressure was then rapidly released at a pressure release rate of 10 MPa / s to obtain an EVA foam material.

[0041] Example 3

[0042] The present embodiment provides a wear-resistant and lightweight EVA foam material, which is used as a sole material. The EVA foam material is supercritically foamed by the following components in parts by weight: 100 parts of modified EVA, 12 parts of POE, 0.8 parts of dicumyl peroxide, 3.0 parts of zinc stearate, 1.2 parts of activated zinc oxide, 0.6 parts of stearic acid and 5 parts of titanium dioxide.

[0043] The modified EVA is prepared from Formosa Plastics 7470M with a VA content of 26%, maleic anhydride-grafted EVA KT-26, hydroxy-terminated polybutadiene HTPB with an average relative molecular weight of 3000, epoxy-modified organic silicone emulsion LK-636, and pyridine. The maleic anhydride-grafted EVA, HTPB, and epoxy-modified organic silicone emulsion are in equal molar amounts. The amount of maleic anhydride-grafted EVA added is 10% of the EVA material, and the amount of tertiary amine catalyst added is 8% of the epoxy-modified organic silicone emulsion.

[0044] The supercritical foaming process of the EVA foam material specifically includes the following steps:

[0045] S1, prepare modified EVA, specifically:

[0046] S11, EVA material and maleic anhydride grafted EVA are put into an internal mixer, and after internal mixing for 15 minutes, a tertiary amine catalyst is added and continued to mix evenly to obtain a mixed EVA material;

[0047] S12, putting the mixed EVA material and HTPB obtained in step S11 into a twin-screw extruder, setting the temperature of each section to: 80°C / 100°C / 130°C / 90°C, and then putting it into the twin-screw extruder again after extrusion to cycle the reaction three times to complete the reaction between HTPB and maleic anhydride grafted EVA to obtain a first-grade EVA modified material;

[0048] S13, adding the first-level EVA modified material and the epoxy-modified organosiloxane emulsion into an internal mixer at a mixing temperature of 130° C. for 25 min to obtain a second-level EVA modified material;

[0049] S14, refining and extruding the secondary EVA modified material in step S13 to obtain modified EVA;

[0050] S2, extrusion granulation: according to the formula, the modified EVA, POE, dicumyl peroxide, zinc stearate, activated zinc oxide, stearic acid and titanium dioxide of step S1 are added into the screw extruder B, the mixture is melted, and the mixture is extruded and granulated to obtain EVA masterbatch;

[0051] S3, cross-linking reaction: adding the EVA masterbatch of step S2 into the forming mold, closing the mold, heating and pressing to obtain the EVA base;

[0052] S4. Supercritical foaming: The cooled EVA base was placed in a high-pressure reactor, supercritical fluid carbon dioxide was introduced, and the temperature and pressure were increased to perform supercritical foaming at a temperature of 165°C and a pressure of 25 MPa for 40 min. The pressure was then rapidly released at a pressure release rate of 10 MPa / s to obtain an EVA foam material.

[0053] Comparative Example 1

[0054] The difference between this comparative example 1 and the above-mentioned embodiment 1 is only that the preparation process of the modified EVA is different, specifically: maleic anhydride grafted EVA, HTPB, epoxy-modified organosiloxane emulsion, Formosa Plastics 7470M and pyridine are added to a banbury mixer for banbury mixing, the discharged material is put into an open mixer for mixing into sheets, and then sent to a screw extruder for extrusion granulation.

[0055] Comparative Example 2

[0056] The supercritical foaming process of the EVA foam material provided in Comparative Example 2 is specifically as follows: Formosa Plastics 7470M, maleic anhydride grafted EVA, HTPB, epoxy-modified organosiloxane emulsion, pyridine, POE, diisopropylbenzene peroxide, zinc stearate, activated zinc oxide, stearic acid and titanium dioxide are directly put into a screw extruder for blending and melting, and extrusion and granulation are performed to obtain EVA masterbatch; then the EVA masterbatch is put into the forming mold, the mold is closed, heated and pressed to obtain the EVA base blank; finally, the cooled EVA base blank is placed in a high-pressure reactor, supercritical fluid carbon dioxide is introduced, and the temperature and pressurization are increased for supercritical foaming, the temperature is 165°C, the pressure is 25 MPa, and the time is 40 min, and then the pressure is quickly released at a pressure release rate of 10 MPa / s to obtain the EVA foam material.

[0057] The EVA foam materials of Examples 1-3 and Comparative Examples 1-2 were tested for the following indicators: tear strength (right-angle tear) according to GB / T 529-2008, tensile strength (according to GB / T 528-2009), and DIN abrasion resistance (according to GB / T 9867:2001). See Table 1 for detailed test results.

[0058] Table 1: Physical test results of Examples 1-3 and Comparative Examples 1-2

[0059] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Density g / cm3 0.042 0.048 0.044 0.06 0.10 DIN wear resistance mm3 98 105 102 121 142 Tear strength N / mm 7.2 6.8 7.0 5.2 4.8 Tensile strength MPa 3.8 3.4 3.6 2.5 2.6 Surface sensory Smooth and wrinkle-free Smooth and wrinkle-free Smooth and wrinkle-free Slightly wrinkled Slightly wrinkled

[0060] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which shall fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. Wear-resistant and lightweight EVA foam material, characterized by: The EVA foam material is prepared by supercritical foaming of the following components in parts by weight: 80-100 parts of modified EVA, 10-15 parts of POE, 0.5-1.0 parts of a crosslinking agent, 2.0-3.0 parts of zinc stearate, 1.0-1.5 parts of activated zinc oxide, 0.3-0.6 parts of stearic acid, and 3-5 parts of titanium dioxide. The modified EVA is prepared from EVA raw material, maleic anhydride grafted EVA, HTPB, epoxy-modified organosiloxane emulsion and tertiary amine catalyst, wherein the maleic anhydride grafted EVA, HTPB and epoxy-modified organosiloxane emulsion are in equal molar amounts, the amount of maleic anhydride grafted EVA added is 10% to 12% of the EVA raw material, and the amount of tertiary amine catalyst added is 5% to 10% of the epoxy-modified organosiloxane emulsion; The preparation method of the modified EVA specifically comprises the following steps: S11, EVA material and maleic anhydride grafted EVA are put into an internal mixer according to the ratio, and after internal mixing for 10 to 20 minutes, a tertiary amine catalyst is added and the mixing is continued to be uniform to obtain a mixed EVA material; S12, feeding the mixed EVA material and HTPB obtained in step S11 into a twin-screw extruder, setting the temperature of each section to: 60°C to 80°C / 90°C to 100°C / 120°C to 140°C / 80°C to 100°C, and then feeding the mixed EVA material into the twin-screw extruder again after extrusion to cycle the reaction 2 to 3 times to complete the reaction between the HTPB and the maleic anhydride grafted EVA to obtain a first-grade EVA modified material; S13, adding the first-level EVA modified material and the epoxy-modified organosiloxane emulsion into an internal mixer at a mixing temperature of 120° C. to 130° C. for 20 min to 30 min to obtain a second-level EVA modified material; S14, refining and extruding the secondary EVA modified material in step S13 to obtain modified EVA.

2. The wear-resistant and lightweight EVA foam material according to claim 1, characterized in that: The cross-linking agent is di-tert-butyl peroxide isopropyl benzene and dicumyl peroxide or a mixture of the two.

3. The wear-resistant and lightweight EVA foam material according to claim 1, characterized in that: The VA content of the EVA rice is 25% to 33%.

4. The wear-resistant and lightweight EVA foam material according to claim 1, characterized in that: The tertiary amine catalyst is pyridine.

5. Use of the wear-resistant lightweight EVA foam material according to any one of claims 1 to 4 on shoe soles.