A SEBS / EVA foamed material, its preparation method and uses

Abstract

The present invention provides an SEBS / EVA foaming material, a preparation method and uses thereof, belonging to the field of foaming materials. The SEBS / EVA foaming material provided by the present invention has good foaming morphology, uniform pore size and moderate density, and can meet the requirement of comfortable wearing when used as shoe materials. The SEBS / EVA foaming material provided by the present invention can not only be used for preparing shoe materials, but also has broad application prospects in the fields of cosmetic packaging, sports goods, aerospace and the like.

Description

Technical Field

[0001] The present invention belongs to the field of foaming materials, and particularly relates to a SEBS / EVA foaming material, a preparation method thereof and uses thereof. Background Art

[0002] The retail industry is one of the fastest-growing and most vibrant industries in China in recent years. At present, the retail industry in China's retail market almost includes all retail formats in the world, with rich and diverse sales channels. The personalized and branded sales terminals have adapted to the new consumption trends of consumers, creating a good market environment for shoe enterprises and also providing convenience for the development of shoe material manufacturing enterprises. After a certain period of rapid development and expansion, China's shoe industry has entered a relatively stable development stage and has formed a complete and mature industrial chain, fully meeting the needs of upstream and downstream connection and supporting production.

[0003] Compared with traditional shoe-making technologies, the foaming technology can reduce the material consumption of the same volume due to the presence of pores in the foaming material, reduce the weight of plastic parts and save materials, showing high cost performance and good specific strength. However, at present, there is not enough attention paid to the microporous structure of foaming materials. Most of the foaming materials obtained by supercritical nitrogen foaming have poor morphology, large pore diameters and serious pore overlapping phenomena, resulting in poor mechanical properties of the foaming materials.

[0004] Elastomer materials have been widely used in fields such as films, wires and cables, adhesives and foamed products due to their excellent resilience, high mechanical strength, good impact resistance, chemical stability, environmental protection and wide temperature range of use. Among them, elastomer foaming materials are widely used in the shoe material field due to their advantages such as buffering and shock absorption, light weight and high elasticity. Ethylene-vinyl acetate copolymer (EVA) is a thermoplastic elastomer with excellent flexibility, elasticity and good processability, and has been widely used in the field of foamed products. However, EVA foaming materials have disadvantages such as slipping, poor wear resistance, large deformation and hardening at low temperatures, which limit their application as shoe materials. Styrene-ethylene / butylene-styrene copolymer (SEBS) is a new type of modified thermoplastic elastomer obtained by selectively hydrogenating the unsaturated double bonds of the rubber segment polybutadiene in the thermoplastic styrene-butadiene-styrene block copolymer (SBS). SEBS has excellent aging resistance, thermal stability, oxidation resistance, flexibility, and also has good compatibility and blendability, and is an ideal elastomer for modifying EVA foaming materials.

[0005] Patent application CN114773771A discloses a SEBS-modified EVA elastomer foaming material, which is prepared by a supercritical foaming process using ethylene-vinyl acetate copolymer, styrene-ethylene / butene-styrene copolymer, vulcanizing agent and foaming promoter as raw materials. The SEBS-modified EVA elastomer foaming material has no color deviation, and at the same time has excellent foaming ratio, hardness and elongation at break, and can meet the requirements of high hardness and high toughness. However, the SEBS-modified EVA elastomer foaming material has a low cell uniformity and a high density, and the shoe material is heavy, which does not meet the requirement of wearing comfort. Summary of the Invention

[0006] The purpose of the present invention is to provide a SEBS / EVA foaming material, its preparation method and use.

[0007] The present invention provides a foaming material, which is prepared by a supercritical foaming process using the following components in parts by weight as raw materials:

[0008] 20-28 parts of ethylene-vinyl acetate copolymer, 30-38 parts of styrene-ethylene / butene-styrene copolymer, 0.30-2.00 parts of vulcanizing agent, 0.20-1.50 parts of foaming promoter.

[0009] Further, the raw materials include the following components in parts by weight: 25 parts of ethylene-vinyl acetate copolymer, 35 parts of styrene-ethylene / butene-styrene copolymer, 1.11 parts of vulcanizing agent, 0.75 parts of foaming promoter.

[0010] Further, the vinyl acetate content in the ethylene-vinyl acetate copolymer is 33%;

[0011] And / or, the vulcanizing agent is one or a mixture of two of ditert-butyl peroxide diisopropylbenzene and dicumyl peroxide;

[0012] And / or, the foaming promoter includes a main foaming promoter and a co-foaming promoter.

[0013] Further, the vulcanizing agent is a mixture of ditert-butyl peroxide diisopropylbenzene and dicumyl peroxide, and the mass ratio of ditert-butyl peroxide diisopropylbenzene to dicumyl peroxide is 1:2;

[0014] And / or, the main foaming promoter is zinc oxide, the co-foaming promoter is zinc stearate, and the mass ratio of the main foaming promoter to the co-foaming promoter is 1:2.

[0015] Further, the supercritical foaming process includes the following steps:

[0016] (1) Weigh the raw materials, melt and blend them, extrude and pelletize them, and mold them to obtain a semi-finished product;

[0017] (2) Place the semi-finished product into a foaming kettle, inject a gas foaming agent for supercritical foaming to obtain a foamed material.

[0018] Further, in step (1), the molding method is injection molding. The temperature during the injection molding process is 165 - 185 °C, and the vulcanization time during the injection molding process is 300 - 400 s.

[0019] In step (2), the gas foaming agent is nitrogen. During the supercritical foaming, the temperature at the upper part of the foaming kettle is 135 - 165 °C, the temperature at the lower part of the foaming kettle is 145 - 175 °C, the pressure is 10 - 20 MPa, and the pressure holding time is 10 - 50 min.

[0020] Further, in step (1), the temperature during the injection molding process is 175 ± 5 °C, and the vulcanization time during the injection molding process is 350 s.

[0021] In step (2), during the supercritical foaming, the temperature at the upper part of the foaming kettle is 145 °C, the temperature at the lower part of the foaming kettle is 155 °C, the pressure is 16 MPa, and the pressure holding time is 40 min.

[0022] Further, in step (2), the position where the semi-finished product is placed is the lower part of the foaming kettle.

[0023] The present invention also provides a process for preparing the above-mentioned foamed material, which is characterized in that: the process includes the following steps:

[0024] (1) Weigh raw materials, melt and blend them, extrude and pelletize them, and mold to obtain a semi-finished product.

[0025] (2) Place the semi-finished product into a foaming kettle, inject a gas foaming agent for supercritical foaming to obtain a foamed material.

[0026] The present invention also provides the use of the above-mentioned foamed material in the preparation of shoe materials, cosmetic packaging, sports goods, and aerospace products.

[0027] The SEBS / EVA foamed material provided by the present invention has good foaming morphology, uniform pore size, and moderate density. When used as a shoe material, it can meet the requirement of comfortable wearing. Among them, the SEBS / EVA foamed materials prepared in Examples 7 - 9 have the best foaming effect.

[0028] The SEBS / EVA foamed material provided by the present invention can not only be used to prepare shoe materials, but also has broad application prospects in the fields of cosmetic packaging, sports goods, aerospace, etc.

[0029] Obviously, based on the above content of the present invention, according to the common general technical knowledge and conventional means in the art, without departing from the above basic technical idea of the present invention, various other forms of modifications, substitutions or changes can be made.

[0030] The following is a further detailed description of the above content of the present invention through specific embodiments in the form of examples. However, this should not be understood as limiting the scope of the above subject matter of the present invention to the following examples. All technologies implemented based on the above content of the present invention fall within the scope of the present invention. Brief Description of the Drawings

[0031] Figure 1 :(A, B) SEM images of the sample of Example 8 of the invention and (C, D) Comparative Sample 14 and the normal distribution diagrams of the cell uniformity. Detailed Description of the Invention

[0032] The raw materials and equipment used in the present invention are all known products, obtained by purchasing commercially available products.

[0033] Styrene-ethylene / butylene-styrene copolymer (SEBS), YH-535, Sinopec Baling Petrochemical Co., Ltd.

[0034] Ethylene-vinyl acetate copolymer (EVA): 3315 (VA: 33%), Taisox Co., Ltd., Taiwan, China.

[0035] Vulcanizing agent dicumyl peroxide (DCP), chemically pure, Shanghai Chemical Reagent Co., Ltd., China National Pharmaceutical Group.

[0036] Vulcanizing agent bis(tert-butylperoxyisopropyl)benzene (BIBP), analytically pure, Fangruida Chemical Co., Ltd.

[0037] Main foaming agent zinc oxide (ZnO), analytically pure, Chengdu Kelong Chemical Reagent Factory.

[0038] Auxiliary foaming agent zinc stearate (ZnSt), analytically pure, Chengdu Kelong Chemical Reagent Factory.

[0039] Foaming kettle, model: 20203002 type, manufacturer: Sichuan Yejing Chemical Equipment Co., Ltd.

[0040] Examples 1-12: Preparation of SEBS / EVA foamed shoe materials by supercritical foaming process

[0041] (1) Weigh each raw material according to the formula shown in Table 1, melt and blend them, extrude and pelletize, and injection mold to obtain a sample bar; when injection molding, control the temperature at 175 ± 5 °C and the vulcanization time at 350 s;

[0042] (2) Place the spline into the foaming kettle, inject nitrogen, with the nitrogen pressure being 16 MPa. Control the kettle temperature, pressure holding time, and the placement position of the sample according to Table 2, then release the pressure and open the kettle to obtain the SEBS / EVA foamed shoe material.

[0043] Table 1. Formulations of SEBS / EVA foamed shoe materials in Examples 1 - 12

[0044]

[0045] Table 2. Process parameters, cell diameter, and shoe material density of each SEBS / EVA foamed shoe material

[0046]

[0047]

[0048] Note: There are three upper, middle, and lower shelves inside the foaming kettle from top to bottom for placing foaming samples; the upper and lower temperatures of the foaming kettle are set before the reaction.

[0049] The beneficial effects of the preparation of the present invention are demonstrated by the following experimental examples.

[0050] Experimental Example 1: Cell diameter and shoe material density of SEBS / EVA foamed shoe material

[0051] 1. Experimental samples

[0052] The SEBS / EVA foamed shoe materials prepared in Examples 1 - 12 of the present invention.

[0053] According to the formulations of Examples 4, 5, and 6 shown in Table 1 of CN114773771A, prepare splines according to the method described therein, then place the splines into the foaming kettle (i.e., the high-pressure kettle), inject nitrogen, with the nitrogen pressure being 20 MPa, control the kettle temperature, pressure holding time, and the placement position of the sample according to Table 2 of the present invention, then release the pressure and open the kettle to obtain Comparative Samples 13, 14, and 15.

[0054] 2. Experimental methods

[0055] 2.1 Cell diameter test

[0056] A scanning electron microscope (SEM) is used to observe the microscopic morphology of the experimental samples, and the Nano Measurer software is used to analyze the cell diameter and cell uniformity of the samples.

[0057] 2.2 Density test

[0058] The test is carried out in accordance with GB / T6343 - 2009.

[0059] 3. Experimental results

[0060] The results are shown in Table 2 and Figure 1 as follows. It can be seen that the density of the shoe materials of Comparative Samples 13-15 is too high, the shoe materials are heavy, which does not meet the requirement of wearing comfort; moreover, the pore uniformity thereof is low.

[0061] However, the pores of the SEBS / EVA foamed shoe materials prepared in Examples 1-12 of the present application are uniform, the density is moderate, which meets the requirement of wearing comfort. Among them, the foaming effect of the SEBS / EVA foamed shoe materials prepared in Examples 7-9 is the best.

[0062] In summary, the present invention provides a SEBS / EVA foaming material, a preparation method and a use thereof. The SEBS / EVA foaming material provided by the present invention has good foaming morphology, uniform pore size and moderate density, and can meet the requirement of wearing comfort when used as a shoe material. The SEBS / EVA foaming material provided by the present invention can not only be used for preparing shoe materials, but also has broad application prospects in the fields of cosmetic packaging, sports goods, aerospace and the like.

Claims

1. A foaming material, characterized in that: It is prepared by a supercritical foaming process using the following components in the specified weight parts: 20 - 28 parts of ethylene - vinyl acetate copolymer, 30 - 38 parts of styrene - ethylene / butene - styrene copolymer, 0.30 - 2.00 parts of vulcanizing agent, 0.20 - 1.50 parts of foaming promoter; The supercritical foaming process includes the following steps: (1) Weigh the raw materials, melt - blend them, extrude and pelletize, and form them into semi - finished products; (2) Place the semi - finished products into a foaming kettle, inject a gas foaming agent for supercritical foaming to obtain a foamed material; In step (1), the forming method is injection molding. The temperature during the injection molding process is 165 - 185 °C, and the vulcanization time during the injection molding process is 300 - 400 s; In step (2), the gas foaming agent is nitrogen. During supercritical foaming, the temperature at the upper part of the foaming kettle is 135 - 165 °C, the temperature at the lower part of the foaming kettle is 145 - 175 °C, the pressure is 10 - 20 MPa, and the pressure - holding time is 10 - 50 min.

2. The foamed material according to claim 1, wherein: The raw materials include the following components in weight parts: 25 parts of ethylene - vinyl acetate copolymer, 35 parts of styrene - ethylene / butene - styrene copolymer, 1.11 parts of vulcanizing agent, 0.75 parts of foaming promoter.

3. The foamed material according to claim 1 or 2, characterized in that: The vinyl acetate content in the ethylene - vinyl acetate copolymer is 33%; And / or, the vulcanizing agent is one or a mixture of two of bis - tert - butylperoxy diisopropylbenzene and dicumyl peroxide; And / or, the foaming promoter includes a main foaming promoter and a co - foaming promoter.

4. The foamed material according to claim 3, characterized in that: The vulcanizing agent is a mixture of bis - tert - butylperoxy diisopropylbenzene and dicumyl peroxide, and the mass ratio of bis - tert - butylperoxy diisopropylbenzene to dicumyl peroxide is 1:2; And / or, the main foaming promoter is zinc oxide, the co - foaming promoter is zinc stearate, and the mass ratio of the main foaming promoter to the co - foaming promoter is 1:

2.

5. The foamed material according to any one of claims 1-4, characterized in that: In step (1), the temperature during the injection molding process is 175 ± 5 °C, and the vulcanization time during the injection molding process is 350 s; In step (2), during supercritical foaming, the temperature at the upper part of the foaming kettle is 145 °C, the temperature at the lower part of the foaming kettle is 155 °C, the pressure is 16 MPa, and the pressure - holding time is 40 min.

6. The foamed material according to claim 5, characterized in that: In step (2), the position where the semi - finished products are placed is the lower part of the foaming kettle.

7. A process for preparing the foamed material according to any one of claims 1-6, characterized in that: The process includes the following steps: (1) Weigh the raw materials, melt - blend them, extrude and pelletize, and form them into semi - finished products; (2) Place the semi - finished products into a foaming kettle, inject a gas foaming agent for supercritical foaming to obtain a foamed material.

8. Use of the foamed material according to any one of claims 1 - 6 in the preparation of shoe materials, cosmetic packaging, sports goods, and aerospace goods.

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