A lightweight, wear-resistant, high-performance micro-foam material and its preparation process

Abstract

The application discloses a kind of high-performance polymer materials and microcellular material, raw material includes main material and additive, it is with TPR material as main material, after TPR material is melted into liquid, additive is added and is obtained by blending;Additive includes TPU foaming granular powder, expanding agent, toughening agent, titanium white and dispersing agent;According to mass percentage, raw material includes the following components: 10-15% TPU foaming granular powder, 4-10% expanding agent, 1-3% toughening agent, 1-2% titanium white, 0.1-0.5% dispersing agent, the balance is TPR material.The polymer material prepared by the method of the application can be applied to shoe sole material, compared with the shoe sole foamed by traditional TPR plus expanding agent, has the advantages of lighter specific gravity, good wear resistance, high resilience, low compression permanent deformation, the foaming agent is more uniform in the preparation process, and the internal microcellular structure of foaming product is more dense and uniform.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer materials, in particular to a light and wear-resistant high-performance micro-foaming material and a preparation process thereof. BACKGROUND

[0002] The high polymer material foaming technology is an important technology for saving materials and reducing the weight of products. Due to the environment-friendly characteristics for the entire manufacturing industry, the physical foaming process has become a research hotspot in the field of high polymer material engineering applications worldwide. At present, in the preparation process of films, sheets and foaming injection products, the foaming microbeads, glass microspheres and chemical foaming agents are directly mixed into the high polymer base material, which will cause a large amount of dust to harm the health of workers. Moreover, the length-diameter ratio of the screw of the injection molding equipment is generally small, the foaming microspheres are not uniformly mixed in the equipment, which leads to uneven foaming of the products and uneven distribution of the internal cells, thereby affecting the performance of the products. If the length-diameter ratio of the screw is increased, although the foaming agent can be uniformly mixed, the high temperature and length in the screw will cause the foaming microspheres to foam and even break and degrade in advance.

[0003] The density of the traditional TPR (thermoplastic rubber material) shoe sole with an expanding agent is generally 0.7-0.8 g / cm 3 It is difficult to further reduce the specific gravity, and further reducing the specific gravity will cause problems such as poor material strength and reduced wear resistance. SUMMARY

[0004] In view of the above technical problems, the purpose of the present application is to provide a light and wear-resistant high-performance micro-foaming material with high resilience and a preparation process thereof.

[0005] The technical scheme adopted by the present application to achieve the purpose is as follows:

[0006] A high-performance high polymer material, which is prepared by blending TPR material as a main material with additives after melting the TPR material into a liquid state, wherein the additives include TPU foaming particle powder, an expanding agent, a toughening agent, titanium white powder and a dispersing agent.

[0007] The raw materials include the following components in terms of mass percentage: 10%-15% TPU foaming particle powder, 4%-10% expanding agent, 1%-3% toughening agent, 1%-2% titanium white powder, 0.1%-0.5% dispersing agent, and the balance of TPR material, wherein the dispersing agent is used for dispersing the titanium white powder.

[0008] Preferably, the high polymer material includes the following components in terms of mass percentage: 10%-12% TPU foaming particle powder, 4%-5% expanding agent, 1%-2% toughening agent, 1%-1.5% titanium white powder, 0.1%-0.18% dispersing agent, and the balance of TPR material; or,

[0009] 13%-15% TPU foam particle powder, 8%-10% expansion agent, 2.5%-3% toughening agent, 1.7%-2% titanium dioxide, 0.3%-0.5% dispersant, and the balance is TPR material; or

[0010] 12%-13% TPU foam particle powder, 5%-8% expansion agent, 2%-2.5% toughening agent, 1.5%-1.7% titanium dioxide, 0.18%-0.3% dispersant, and the balance is TPR material.

[0011] Preferably, the TPU foamed particle powder is a powder with a particle size of 20-50 mesh, preferably 30 mesh, obtained by cooling and grinding TPU foamed particles;

[0012] The expansion agent is heat-expandable microspheres, the diameter of the heat-expandable microspheres is 10-40 μm, and the density is 1.0-1.2 g / cm 3 , the preferred heat-expandable microspheres are microsphere expansion agent WS-606;

[0013] The dispersant is sodium hexametaphosphate;

[0014] The toughening agent is a thermoplastic elastomer toughening agent, preferably the thermoplastic elastomer toughening agent includes polyurethanes, styrenes, polyolefins, polyesters, syndiotactic 1,2-polybutadiene and polyamides, preferably selected from styrene-butadiene thermoplastic elastomer, methyl methacrylate-butadiene-styrene terpolymer, acrylonitrile-butadiene-styrene copolymer, chlorinated polyethylene, ethylene-vinyl acetate copolymer.

[0015] Preferably,

[0016] The melting temperature of the TPR material is 180-220°C;

[0017] The TPU foamed particle powder is obtained by physically foaming TPU particles with supercritical carbon dioxide, and the bubble size of the internal micro closed-cell structure of the TPU foamed particles is 10-30 microns;

[0018] The TPR material is a SEBS-based TPR.

[0019] The method for preparing the polymer material described in any one of the above items comprises the following steps:

[0020] S1, melt the main material TPR material into liquid;

[0021] S2. Add additives to the liquid TPR material, blend and mix evenly, and granulate to obtain the product.

[0022] The preparation method of the polymer material above is prepared by using a screw extruder, comprising the following steps:

[0023] S1, the main material TPR material is added from the main feeding inlet of the screw extruder, the screw conveying section screw temperature is set to 160-180 DEG C, the melting section temperature is set to 180-220 DEG C, and the mixing section temperature is set to 180-200 DEG C, so that the TPR material is melted into liquid;

[0024] S2, the additive is added from the side feeding inlet of the screw extruder (the side feeding inlet is located in the mixing section of the screw), the molten TPR material flows to the side feeding inlet and is mixed with the additive, and finally extruded and granulated, namely; Preferably, the granulation is carried out by underwater pelletizer after the discharge of the screw extruder.

[0025] The screw extruder is a double screw extruder or a single screw extruder, preferably a double screw extruder.

[0026] The light wear-resistant high-performance micro-foaming material provided by the application is obtained by heating and expanding the polymer material prepared by the above method at 140-210 DEG C, the initial foaming temperature is 140-150 DEG C, and the final foaming temperature is 180-210 DEG C.

[0027] The micro-foaming material has a density of 0.3-0.5 g / cm 3 , a hardness of 35-55 HC, a resilience of 52%-65%, a wear resistance of 100-110 mm 3 , a compression permanent deformation of 35%-30%, and a tear strength of 35-45 N / cm.

[0028] The preparation method of the light wear-resistant high-performance micro-foaming material above, the heating expansion is completed in an injection molding machine, and the method is step S3 after the preparation method of the aforementioned polymer material is completed.

[0029] S3, the granular polymer material obtained in step S2 is put into an injection molding machine to injection mold a product, and the micro-foaming material is obtained, the screw temperature of the injection molding machine is set to 165-200 DEG C, the nozzle temperature is set to 190-210 DEG C, and the mold temperature is set to 30-40 DEG C.

[0030] Preferably, the length-diameter ratio of the screw of the injection molding machine in step S3 is 17:1, the screw rotation speed is 140 rad / min, and the feeding speed is 30 HZ.

[0031] The expansion agent used is heat-expandable microspheres, microcapsules containing low-boiling-point hydrocarbons in a thermoplastic copolymer. During the subsequent injection molding process, when the material is heated to 160-180°C, the low-boiling-point hydrocarbons within expand, and the thermoplastic shell softens. This mechanism causes the product to rapidly expand and foam, reducing the specific gravity of the finished product. The raw material, TPU foam granules, has a light specific gravity and internal closed-cell pores, effectively reducing the overall specific gravity of the composite material during preparation. The addition of TPU foam granules also improves the material's elasticity, strength, wear resistance, and compression set. Toughening agents enhance the material's flexibility; titanium dioxide provides coloring, reinforcement, anti-aging, and filling properties, improving the product's aging resistance, discoloration resistance, acid and alkali resistance, and increasing elongation. A dispersant is added to better disperse the titanium dioxide.

[0032] The beneficial effects of the present invention are:

[0033] The polymer material prepared by the method of the present invention can be used in shoe sole materials. Compared with traditional TPR foamed with an expansion agent, it has the advantages of lighter specific gravity, better wear resistance, higher resilience, and lower compression set. The foaming agent is mixed more evenly during the preparation process, and the microporous structure within the foamed product is denser and more uniform. The raw materials are prepared using a screw extruder, and customers can directly inject the prepared materials into an injection molding machine for molding and production without the need for other additives or foaming agents.

[0034] The material formula of the present invention process adds a certain proportion of TPU foam particle powder. The particle size of the material is 30 mesh, and the bubbles in the material have a closed-cell structure of 10-30 microns. During the preparation of the composite material, the overall specific gravity of the material is effectively reduced. At the same time, the addition of TPU foam particle powder improves the elasticity, strength, wear resistance and compression deformation properties of the material. Compared with the density of traditional TPR foam soles of 0.7-0.8g / cm 3 The specific gravity of the material of the present invention is reduced to 0.3-0.5g / cm 3 The resilience is increased from about 50-55% to about 52-65%, the tear strength of the material is increased from 30N / cm to 35-45N / cm, and the wear resistance is increased from 120mm 3 Increased to 100-110mm 3 , compression permanent deformation increases from 35% to 35%-30%, and the hardness is 35-55HC. DETAILED DESCRIPTION

[0035] The present invention will be further described below with reference to the embodiments, but the present invention is not limited thereto.

[0036] The experimental methods in the following examples are conventional methods unless otherwise specified; the materials and reagents used are conventional materials and reagents in the art and are commercially available unless otherwise specified.

[0037] The main materials used in the embodiments of the present invention are as follows:

[0038] TPR material: Thermo-Plastic-Rubber material. In the embodiment of the present invention, SEBS-based TPR is used, with a particle size of 2-4 mm and a density of 0.9-1.3 g / cm 3 , TPR material with hardness of 70A, tensile strength of 10-20Mpa, and elongation at break of 500-850%. Commercially available.

[0039] The dispersant is a commercially available titanium dioxide dispersant.

[0040] TPU foamed particles: TPU particles are obtained by physical foaming with supercritical carbon dioxide. There are a large number of closed-cell bubbles inside the TPU foamed particles, and the bubble size is 10-30 microns. The hardness of the foamed particles is 40±2HC and the density is 0.15g / cm 3 , particle size 5mm, material is polyether TPU.

[0041] The TPU foamed particle powder is prepared by placing TPU foamed particles in a cooling grinder and then cooling and grinding them. The powder has a particle size of about 30 meshes and has air bubbles with a size of 10-30 microns inside.

[0042] Thermal expansion microspheres (also known as foaming microspheres) are a core-shell material with a thermoplastic outer shell and a low-boiling-point alkane as an expansion agent. As a foaming agent, their stable expansion performance and high resilience have made them widely used in various fields of defense and commerce. The average diameter of these hollow spheres ranges from 10 to 40 μm, with a density of 1.0-1.2 g / cm 3 .

[0043] In the embodiment of the present invention, the heat-expandable microspheres are microsphere expansion agent WS-606 produced by Sekisui Chemical of Japan, the toughening agent is a thermoplastic elastomer toughening agent (specifically polyethylene PE toughening agent), and the dispersant is titanium dioxide dispersant - sodium hexametaphosphate.

[0044] The micro-foam material of the present invention is prepared by following the steps:

[0045] S1. Add the main material, TPR, through the main feed port of a twin-screw extruder. Set the screw temperatures in the conveying section to 160-180°C, the melting section to 180-220°C, and the mixing section to 180-200°C until the TPR material melts into a liquid. The twin-screw extruder has an aspect ratio of 52:1.

[0046] S2. Add the additives from the side feed inlet of the twin-screw extruder (the side feed inlet is located in the mixing section of the screw). The molten TPR material flows to the side feed inlet and mixes with the additives. After being squeezed, sheared, and stirred by the screw, it is finally extruded. The output of the screw extruder is pelletized by an underwater pelletizer to obtain oval particles with a diameter of 2-4 mm, thus obtaining a high-performance polymer material.

[0047] S3, the granular polymer material obtained in step S2 is placed in an injection molding machine for injection molding (i.e., heated and expanded) to obtain a micro-foamed material. The screw temperature of the injection molding machine is set to 165-200°C, the nozzle temperature is set to 190-210°C, and the mold temperature is set to 30-40°C. The screw aspect ratio of the injection molding machine is 17:1, the screw speed is 140rad / min, and the feeding speed is 30HZ. The injection molding machine temperature is set to 165°C, which is higher than the starting foaming temperature of the thermal expansion microspheres, 140°C, to allow the material to melt softly, which is conducive to injection molding products in the injection molding machine.

[0048] The materials of Examples 1-4 were prepared according to this method. The raw material ratios and process parameters are shown in Table 1:

[0049] Table 1

[0050]

[0051] The materials obtained from Examples 1-4 were tested:

[0052] The Shore hardness of the material is tested using GB / T 3903.4-2017 Test method for hardness of whole shoes.

[0053] The material resilience is tested using GB / T 6670-2008 Determination of rebound properties of flexible foam polymeric materials by falling ball method.

[0054] The wear resistance of materials is tested using GB / T 9867-2008 Vulcanized rubber or thermoplastic rubber - Determination of wear resistance (rotating roller abrader method).

[0055] The material compression permanent deformation is tested using "HG / T 2876-2009 Test Method for Compression Deformation of Microporous Materials of Rubber and Plastic Shoes".

[0056] GB / T 528-2009 Vulcanized rubber or thermoplastic rubber - Determination of tensile stress-strain properties is used to test the tear strength of the material.

[0057] The test results are shown in Table 2.

[0058] Table 2

[0059]

Claims

1. A method for preparing a polymer material, characterized in that: The steps include: S1, melt the main material TPR material into liquid; S2. Add additives to the liquid TPR material, blend and mix evenly, and granulate to obtain; The additives include TPU foamed particle powder, an expansion agent, a toughening agent, titanium dioxide, and a dispersant; the TPU foamed particle powder is a powder with a particle size of 20-50 mesh obtained by cooling and grinding TPU foamed particles; the expansion agent is a thermal expansion microsphere, the toughening agent is a thermoplastic elastomer toughening agent, and the TPR material is TPR with a SEBS base material; The raw materials include the following components by mass percentage: 10%-15% TPU foamed particle powder, 4%-10% expansion agent, 1%-3% toughening agent, 1%-2% titanium dioxide, 0.1%-0.5% dispersant, and the balance is TPR material. The dispersant is used to disperse the titanium dioxide.

2. The preparation method according to claim 1, wherein: The preparation is carried out by a screw extruder, comprising the following steps: S1. Add the main material TPR material from the main feeding port of the screw extruder, set the screw temperature of the screw conveying section to 160-180℃, the temperature of the melting section to 180-220℃, and the temperature of the mixing section to 180-200℃, so that the TPR material melts into liquid; S2, adding additives from the side feed inlet of the screw extruder, the molten TPR material flows to the side feed inlet and mixes with the additives, is extruded, sheared and stirred by the screw, and finally extruded and granulated to obtain; The screw extruder is a twin-screw extruder or a single-screw extruder.

3. The preparation method according to claim 1, wherein: The raw materials include the following components by mass percentage: 10%-12% TPU foam particle powder, 4%-5% expansion agent, 1%-2% toughening agent, 1%-1.5% titanium dioxide, 0.1%-0.18% dispersant, and the balance is TPR material; or, 13%-15% TPU foaming particle powder, 8%-10% expansion agent, 2.5%-3% toughening agent, 1.7%-2% titanium dioxide, 0.3%-0.5% dispersant, the balance is TPR material; or, 12%-13% TPU foam particle powder, 5%-8% expansion agent, 2%-2.5% toughening agent, 1.5%-1.7% titanium dioxide, 0.18%-0.3% dispersant, and the balance is TPR material.

4. The preparation method according to claim 1, wherein: The particle size of the TPU foaming particle powder is 30 mesh; The diameter of the heat-expandable microspheres is 10-40 μm and the density is 1.0-1.2 g / cm 3 ; The dispersant is sodium hexametaphosphate.

5. The preparation method according to claim 1, wherein: The melting temperature of the TPR material is 180-220°C; The TPU foamed particle powder is obtained by physically foaming TPU particles through supercritical carbon dioxide. The bubble pore size of the internal microscopic closed-cell structure of the TPU foamed particles is 10-30 microns.

6. A polymer material, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 5.

7. A lightweight, wear-resistant, high-performance micro-foam material, characterized by: The polymer material according to claim 6 is heated and expanded at 140-210°C for foaming, wherein the initial foaming temperature is 140-150°C and the final foaming temperature is 180-210°C.

8. A method for preparing the lightweight, wear-resistant, high-performance micro-foam material according to claim 7, characterized in that: The heating expansion is completed in an injection molding machine. The method is: the polymer material according to claim 6 is placed in an injection molding machine to inject molded products to obtain a micro-foamed material, the screw temperature of the injection molding machine is set to 165-200°C, the nozzle temperature is set to 190-210°C, and the mold temperature is set to 30-40°C.

9. The preparation method according to claim 8, characterized in that: The injection molding machine has a screw length-to-diameter ratio of 17:1, a screw speed of 140 rad / min, and a feed rate of 30 Hz.

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