A lightweight wear-resistant foaming material and its preparation process

Abstract

The present invention discloses a lightweight wear-resistant foaming material and a preparation method thereof: S1 Prepare the main material: Stir 60-80 wt% of styrene-butadiene-styrene block copolymer (SBS), 16-40 wt% of mineral oil, and 0-15 wt% of blowing agent evenly, and let it stand for 4-5 h; Put the swollen mixed material into a kneading equipment and knead at 25-100 °C, and put the kneaded material into a rubber extruder for strand pelletizing to obtain the main material; S2 Prepare the auxiliary material: Put 70-90 wt% of TPU foaming particle powder, 8-20 wt% of toughening agent, 0.1-5 wt% of dispersant, and 1-20 wt% of titanium dioxide into a kneading equipment and knead at 130-160 °C, and put the kneaded material into a rubber extruder for strand pelletizing; S3: Mix 70%-90% wt% of the main material with 10-30% wt% of the auxiliary material and put it into an injection molding machine to injection mold products.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and particularly relates to a lightweight wear-resistant foaming material and a preparation process thereof. Background Art

[0002] The polymer material foaming technology is an important technology for saving materials and reducing the weight of products at present. Due to the environmentally friendly characteristics for the entire manufacturing industry, the physical foaming process has become a research hotspot in the field of polymer material engineering applications worldwide. Currently, during the preparation process of films, sheets, and foamed injection molded products, foaming microspheres, glass microspheres, and chemical blowing agents in powder form are directly mixed into the polymer substrate, which will cause a large amount of dust and endanger the health of workers. And the screw length-diameter ratio of injection molding equipment is generally relatively small, and the foaming microspheres are unevenly mixed in the equipment, resulting in uneven foaming of the products and uneven distribution of internal pores, affecting the performance of the products. If the screw length-diameter ratio is increased, although the blowing agent can be evenly mixed, the excessively high temperature and length inside the screw will cause the foaming microspheres to foam in advance or even rupture and degrade.

[0003] The density of traditional TPR (thermoplastic rubber material) foamed soles added with an expanding agent generally reaches 0.7 - 0.8 g / cm 3 , and it is difficult to further reduce the specific gravity. Further reducing the specific gravity will cause problems such as poor material strength and reduced wear resistance. Summary of the Invention

[0004] Through research, the inventors of the present invention have prepared a lightweight, wear-resistant, elastic, and environmentally friendly material by using a kneading and injection molding process. The blowing agent in this material is evenly mixed, the process operation is simple, there is no dust hazard, and the material cost is further reduced on the basis of the traditional process. The density of the product can reach 0.4 - 0.6 g / cm 3 , and the material still has good wear resistance, tear strength, resilience, compression deformation and other properties. Customers can directly put this material into the equipment for injection molding. Based on this, the present invention protects the following technical solutions:

[0005] A preparation method of a lightweight wear-resistant foaming material, comprising the following steps:

[0006] S1. Prepare the main material: Stir 60 - 80 wt% styrene-butadiene-styrene block copolymer SBS, 16 - 40 wt% mineral oil, and 0 - 15 wt% expanding agent evenly, and let it stand for 4 - 5 h to fully swell the SBS with oil; Put the swollen mixed material into a kneading equipment and carry out kneading at 25 - 100 °C for 5 - 15 min, and put the kneaded material into a rubber extruder for strand pelletizing to obtain the main material;

[0007] S2. Preparation of auxiliary materials: Put 70-90wt% of TPU foaming granule powder, 8-20wt% of toughening agent, 0.1-5wt% of dispersant, and 1-20wt% of titanium dioxide into a kneading equipment for kneading at 130-160°C for 5-15 minutes. Then put the kneaded material into a rubber extruder for strip pelletizing to obtain the auxiliary materials; the dispersant is used to disperse the titanium dioxide; S3. Injection molding of products by an injection molding machine: Mix 70%-90%wt% of the main materials with 10-30%wt% of the auxiliary materials, stir evenly, and put them into the injection molding machine for injection molding. The screw temperature of the injection molding machine is set at 165-205°C.

[0008] In the above technical solution, the blowing agent is a thermally expandable microsphere, and the diameter of the thermally expandable microsphere is 10-40μm, with a density of 1.0-1.2g / cm 3 , preferably the thermally expandable microsphere is the microsphere blowing agent WS-606;

[0009] The mineral oil is naphthenic oil or paraffin oil, and preferably the naphthenic oil is KN4010 naphthenic oil;

[0010] The TPU foaming granule powder is a powder with a particle size of 20-50 meshes obtained by cooling and grinding TPU foaming granules, preferably 30 meshes;

[0011] The dispersant is sodium hexametaphosphate;

[0012] The toughening agent is a thermoplastic elastomer toughening agent. Preferably, the thermoplastic elastomer toughening agent includes polyurethane, styrene, polyolefin, polyester, syndiotactic 1,2-polybutadiene, and polyamide, and is preferably selected from styrene-butadiene thermoplastic elastomer (SBS), methyl methacrylate-butadiene-styrene terpolymer (MBS), acrylonitrile-butadiene-styrene copolymer (ABS), chlorinated polyethylene (CPE), ethylene-vinyl acetate copolymer (EVA).

[0013] The TPU foaming granule powder is obtained by physically foaming TPU particles with supercritical carbon dioxide, and the bubble pore size of the internal microscopic closed-cell structure of the TPU foaming granules is 10-30 microns.

[0014] In step S1, the mass percentages of SBS, mineral oil, and blowing agent are 65-75%, 25-35%, and 5-15%, preferably 70-73%, 17-20%, and 8-12%, and more preferably 71.5%, 18.5%, and 10%; the kneading temperature is 60-90°C, preferably 70-90°C.

[0015] In step S2, the mass percentages of the TPU foaming particle powder, toughening agent, dispersant, and titanium dioxide are 72 - 86%, 8 - 15%, 0.1 - 2%, and 5 - 15%, preferably 75 - 84%, 8 - 12%, 0.5 - 1.2%, and 7 - 12%, and further preferably 79%, 10.5%, 0.84%, and 9.66%.

[0016] In step S3, the mass ratio of the main material to the auxiliary material is 78 - 84%, 16 - 22%, preferably 81%, 19%.

[0017] In steps S1 and S2, the rubber extruder is a single-screw extruder with a length-diameter ratio of 17:1. The diameter of the particles obtained by strand pelletizing in the rubber extruder is 2.5 - 3.5 mm;

[0018] In steps S1 and S2, the rotational speed of the internal mixer is 100 rad / min, the rotor speed ratio of the internal mixer is 1:1.18, and the pressure of the upper ram of the internal mixer is 0.7 Mpa.

[0019] In step S3, the screw of the injection molding machine has a length-diameter ratio of 17:1, the screw rotational speed is 140 rad / min, and the feeding speed is 30 HZ.

[0020] A lightweight wear-resistant foaming material is prepared by using the preparation method described in any one of the above.

[0021] The density of the material is 0.4 - 0.6 g / cm 3 , the hardness is 40 - 60 HC, the resilience is 50% - 60%, the wear resistance is 107 mm 3 , and the compression set is 30% - 25%.

[0022] When preparing the main material, naphthenic oil or paraffin oil can adjust the hardness of the material according to the amount of oil filling, enhance the mechanical properties and cold resistance of the material, improve the anti-aging performance of the material, and reduce the cost of the material.

[0023] The blowing agent uses thermally expandable microspheres. The thermally expandable microspheres are microcapsules containing low-boiling hydrocarbons in a thermoplastic copolymer. During the subsequent injection molding process, when the material is heated to 160 - 180 °C, the low-boiling hydrocarbons inside will expand, and the thermoplastic shell will soften. This mechanism can cause the product to expand and foam rapidly, reducing the specific gravity of the material product.

[0024] When preparing auxiliary materials, the raw material TPU foamed particle powder is used. Due to its light specific gravity and the presence of bubble holes with a closed-cell structure inside, it effectively reduces the overall specific gravity of the material during the preparation of the composite material. At the same time, the addition of TPU foamed particle powder improves the elasticity, strength, wear resistance, and compression deformation of the material. Adding a toughening agent can improve the flexibility of the material; adding titanium dioxide plays the roles of coloring, strengthening, anti-aging, and filling, which can improve the anti-aging property, color stability, acid and alkali resistance, and elongation of the material products; adding a dispersant enables better dispersion of titanium dioxide.

[0025] The beneficial effects of the present invention are as follows:

[0026] The present invention provides a preparation method of a material with good light weight, wear resistance, and resilience. This material can be applied to sole materials and has the advantages of lighter specific gravity, better wear resistance, higher resilience, and lower compression set compared to traditional TPR foamed soles with an expanding agent. During the preparation process, the foaming agent is more evenly mixed, and the internal microporous structure of the foamed product is more dense and uniform. The present invention prepares the raw material through internal mixing, and customers can directly put the prepared material into an injection molding machine for molding to prepare products without adding other additives and foaming agents.

[0027] The preparation method provided by the present invention has the advantages of lighter specific gravity, better wear resistance, higher resilience, and lower compression set compared to traditional TPR foamed soles with an expanding agent. During the preparation process, the foaming agent is more evenly mixed, and the internal microporous structure of the foamed product is more dense and uniform. In the material formula of the process of the present invention, a certain proportion of TPU foamed particle powder is added. The particle size of this material is 30 mesh, and it has bubble holes with a closed-cell structure of 10 - 30 microns inside. During the preparation of the composite material, it effectively reduces the overall specific gravity of the material. At the same time, the addition of TPU foamed particle powder improves the elasticity, strength, wear resistance, and compression deformation of the material. Compared with the density of traditional TPR foamed soles of 0.7 - 0.8 g / cm 3 , the specific gravity of the material of the present invention is reduced to 0.4 - 0.6 g / cm 3 , the resilience is increased from about 50 - 55% to about 50 - 60%, the tear strength of the material is increased from 30 N·cm to 43 N·cm, and the wear resistance is increased from 120 mm 3 to 107 mm 3 , and the compression set is decreased from 35% to 30% - 25%. Specific Embodiments

[0028] The following further illustrates the present invention with reference to embodiments, but the present invention is not limited thereby.

[0029] In the experimental methods of the following examples, unless otherwise specified, they are all conventional methods; the materials and reagents used, unless otherwise specified, are all conventional materials and reagents in the art and can be obtained commercially.

[0030] The preparation method of the lightweight wear-resistant foamed material of the present invention is operated according to the following steps:

[0031] S1. Prepare the main material: Stir 60-80 wt% of styrene-butadiene-styrene block copolymer (SBS), 16-40 wt% of mineral oil, and 0-15 wt% of blowing agent evenly, and let it stand for 4-5 h to fully swell the SBS with oil; put the swollen mixed material into a kneading equipment and carry out kneading at 25-100 °C for 5-15 min, and put the kneaded material into a rubber extruder for strand pelletizing to obtain the main material;

[0032] S2. Prepare the auxiliary material: Put 70-90 wt% of foamed TPU powder, 8-20 wt% of toughening agent, 0.1-5 wt% of dispersant, and 1-20 wt% of titanium dioxide into a kneading equipment and carry out kneading at 130-160 °C for 5-15 min, and put the kneaded material into a rubber extruder for strand pelletizing to obtain the auxiliary material; the dispersant is used to disperse the titanium dioxide;

[0033] S3. Inject products with an injection molding machine: Mix 70%-90% wt% of the main material and 10-30% wt% of the auxiliary material evenly, put it into an injection molding machine to inject products, and set the screw temperature of the injection molding machine to 165-205 °C.

[0034] In the examples of the present invention, the specific main equipment parameters are as follows:

[0035] In step S1, the temperature of the kneader is controlled at 25-100 °C, the rotation speed of the kneader is 80 rad / min, the rotor speed ratio of the kneader is 1:1.18, and the pressure of the upper ram of the kneader is 0.5 Mpa.

[0036] In step S2, the temperature of the kneader is controlled at 130-160 °C, the rotation speed of the kneader is 100 rad / min, the rotor speed ratio of the kneader is 1:1.18, and the pressure of the upper ram of the kneader is 0.7 Mpa.

[0037] In steps S1 and S2, the rubber extruder is a single-screw extruder with a length-diameter ratio of 17:1, and the diameter of the pellets obtained by strand pelletizing in the rubber extruder is 2.5-3.5 mm.

[0038] In step S3, the injection molding machine has a screw length-diameter ratio of 17:1, a screw rotation speed of 140 rad / min, a feeding speed of 30 HZ, and the screw temperature is set at 165-205 °C.

[0039] The main materials used in the embodiments of the present invention are as follows:

[0040] Styrene-butadiene-styrene block copolymer (SBS) powder: obtained commercially.

[0041] The dispersant is a commercially available titanium dioxide dispersant, obtained commercially.

[0042] TPU foam particles: obtained by physically foaming TPU particles with supercritical carbon dioxide. There are a large number of closed-cell structure air pores inside the TPU foam particles, and the size of the air pores is 10 - 30 microns. The hardness of the foam particles is 40 ± 2 HC, and the density is 0.15 g / cm 3 , the particle size is 5 mm, and the material is polyether-based TPU.

[0043] TPU foam particle powder is powder with a particle size of about 30 mesh prepared by placing TPU foam particles in a cooling grinder and cooling and grinding. There are air pores with a size of 10 - 30 microns inside the powder.

[0044] Thermally expandable microspheres (alias: foaming microspheres) are a core-shell material with a thermoplastic plastic as the shell and a low-boiling alkane as the internal expansion propellant. As a foaming agent, their stable expansion performance and high resilience are widely used in various fields of national defense and commerce. The average diameter of these hollow spheres ranges from 10 to 40 μm, and the density is 1.0 - 1.2 g / cm 3 .

[0045] In the embodiments of the present invention, the thermally expandable microspheres are the microsphere blowing agent WS-606 produced by Sekisui Chemical Co., Ltd. of Japan, the mineral oil is KN4010 naphthenic oil, the toughening agent is a thermoplastic elastomer toughening agent (specifically, polyethylene PE toughening agent), and the dispersant is titanium dioxide dispersant - sodium hexametaphosphate.

[0046] The materials of Examples 1 - 4 were prepared according to the foregoing method, and the raw material ratios and process parameters are shown in Table 1:

[0047] Table 1

[0048]

[0049] The process parameters of Examples 1 - 4 are shown in Table 2:

[0050] Table 2

[0051]

[0052] Test the materials prepared in Examples 1 - 4:

[0053] Test the Shore hardness of the materials using "GB / T 3903.4-2017 Footwear - Whole Shoe Test Methods - Hardness".

[0054] The resilience of the material was detected by "GB / T 6670-2008 Determination of resilience of flexible cellular polymeric materials by the falling-ball method".

[0055] The abrasion resistance of the material was detected by "GB / T 9867-2008 Determination of abrasion resistance of vulcanized rubber or thermoplastic rubber (rotary roller abrader method)".

[0056] The compression set of the material was detected by "HG / T 2876-2009 Test method for compression set of microcellular materials of rubber and plastic shoes".

[0057] The tear strength of the material was detected by "GB / T 528-2009 Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber".

[0058] The test results are shown in Table 3 as follows:

[0059] Table 3

[0060]

Claims

1. A preparation method of a lightweight wear-resistant foaming material, characterized in that, It includes the following steps: S1. Prepare the main material: Stir 60 - 80 wt% styrene-butadiene-styrene block copolymer (SBS), 16 - 40 wt% mineral oil, and 0 - 15 wt% swelling agent evenly, and let it stand for 4 - 5 h to fully swell the SBS with oil. Put the swollen mixture into a kneading equipment and knead at 25 - 100 °C for 5 - 15 min. Put the well-kneaded material into a rubber extruder for strand pelletizing to obtain the main material; the swelling agent is microsphere swelling agent WS-606; S2. Prepare the auxiliary material: Put 70 - 90 wt% TPU foaming particle powder, 8 - 20 wt% toughening agent, 0.1 - 5 wt% dispersant, and 1 - 20 wt% titanium dioxide into a kneading equipment and knead at 130 - 160 °C for 5 - 15 min. Put the well-kneaded material into a rubber extruder for strand pelletizing to obtain the auxiliary material; the dispersant is used to disperse the titanium dioxide; the TPU foaming particle powder is obtained by physically foaming TPU particles with supercritical carbon dioxide; S3. Inject products with an injection molding machine: Mix 70% - 90% wt% of the main material and 10 - 30%wt% of the auxiliary material evenly, and put them into an injection molding machine to inject products. The screw temperature of the injection molding machine is set at 165 - 205 °C.

2. The preparation method according to claim 1, wherein: The mineral oil is naphthenic oil or paraffin oil; The TPU foaming particle powder is a powder with a particle size of 20 - 50 mesh obtained by cooling and grinding TPU foaming particles; The dispersant is sodium hexametaphosphate; The toughening agent is a thermoplastic elastomer toughening agent, and the thermoplastic elastomer toughening agent includes polyurethane, polyolefin, polyester, and polyamide; 3. The preparation method according to claim 2, characterized in that: The bubble pore size of the internal micro-closed cell structure of the TPU foaming particles is 10 - 30 microns; 4. The preparation method according to claim 1, characterized in that: In step S1, the mass percentages of SBS, mineral oil, and swelling agent are 65 - 75%, 25 - 35%, and 5 - 15%; the kneading temperature is 60 - 90 °C; 5. The preparation method according to claim 1, wherein: In step S2, the mass percentages of TPU foaming particle powder, toughening agent, dispersant, and titanium dioxide are 72 - 86%, 8 - 15%, 0.1 - 2%, and 5 - 15%; 6. The preparation method according to claim 1, characterized in that: In step S3, the mass ratio of the main material to the auxiliary material is 78 - 84%, 16 - 22%; 7. The preparation method according to claim 1, characterized in that: In steps S1 and S2, the rubber extruder is a single-screw extruder with a length-diameter ratio of 17:1, and the particle diameter obtained by strand pelletizing in the rubber extruder is 2.5 - 3.5 mm; In steps S1 and S2, the kneader speed is 100 rad / min, the kneader rotor speed ratio is 1:1.18, and the upper ram pressure of the kneader is 0.7 Mpa; 8. The preparation method according to claim 1, characterized in that: In step S3, the injection molding machine has a screw length-diameter ratio of 17:1, a screw speed of 140 rad / min, and a feeding speed of 30 HZ; 9. A lightweight and wear-resistant foamed material, characterized in that: It is prepared by using the preparation method according to any one of claims 1 to 8.

10. The light and wear-resistant foamed material according to claim 9, characterized in that: The density of the material is 0.4-0.6 g / cm 3 , hardness 40-60HC, resilience 50%-60%, wear resistance 107mm 3 , compression permanent deformation 30%-25%.

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