A NBR / TPU dynamic vulcanized material and its preparation method and application

Abstract

The present invention relates to a NBR / TPU dynamic vulcanization material, which comprises the following components in parts by weight: 60-80 parts of acrylonitrile rubber, 10-20 parts of styrene-butadiene rubber, 10-20 parts of styrene-acrylonitrile copolymer, 7-10 parts of copper sulfate, 1-5 parts of vulcanizing agent, 30-50 parts of thermoplastic polyurethane elastomer and 3-10 parts of compatibilizer. The dynamic vulcanization material has both the performance of NBR after vulcanization and the elasticity of elastomer, and is recyclable, halogen-free and environmentally friendly, has good colorability, excellent anti-slip property, wear resistance, fatigue resistance and weather resistance, and still has excellent performance after foaming.

Description

Technical Field

[0001] The invention relates to the technical field of NBR / TPU composite materials, and in particular to an NBR / TPU dynamic vulcanization material and a preparation method and application thereof. Background Art

[0002] Nitrile rubber (NBR) is a copolymer formed by the polymerization of acrylonitrile and butadiene monomers. It has good oil resistance, water resistance, wear resistance, heat resistance and adhesion. Its disadvantages are low temperature resistance, ozone resistance, poor insulation and elastic properties. TPU has good wear resistance, high elastic modulus, flexibility, and can maintain its elastic properties in a wide temperature range. It can maintain good winding properties even under low temperature conditions. TPU is also easy to process and manufacture, has a high degree of flexibility, and can adapt to various molding requirements.

[0003] If NBR and TPU are directly mixed and vulcanized, the processing performance of NBR is poor because of its narrow molecular weight distribution, high polarity, poor molecular chain flexibility, and difficulty in plasticizing. During mixing, it generates large processing heat and even rolls off. In addition, the vulcanization speed is slow, and NBR needs a long time to complete the vulcanization process, which may increase production costs and reduce production efficiency. NBR is prone to tearing in high temperature environments or when subjected to external forces, which limits its use in certain high temperature or high force application scenarios. NBR may face certain difficulties during processing, such as uneven mixing and difficult molding, which may also affect the quality and performance of the final product. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide an NBR / TPU dynamic vulcanization material and a preparation method and application thereof, which combines the properties of NBR after vulcanization and has the elasticity of rubber, is recyclable, halogen-free and environmentally friendly, has good colorability, excellent anti-slip properties, wear resistance, fatigue resistance and weather resistance, and still has excellent performance after foaming.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] In a first aspect, the present invention provides an NBR / TPU dynamic vulcanization material, comprising the following raw materials in parts by weight: 60-80 parts of nitrile rubber (NBR), 10-20 parts of styrene-butadiene rubber (SBS), 10-20 parts of styrene-acrylonitrile copolymer (SAN), 7-10 parts of copper sulfate, 1-5 parts of a vulcanizing agent, 30-50 parts of a thermoplastic polyurethane elastomer (TPU) and 3-10 parts of a compatibilizer.

[0007] The present invention selects to add styrene-acrylonitrile copolymer (SAN) and copper sulfate (CuSO4) as reinforcing agents for NBR and TPU. Specifically, SAN is a polymer copolymerized by styrene and acrylonitrile, and its molecular structure contains benzene rings and polar groups, which makes SAN have certain polarity and rigidity; NBR, as a nitrile rubber, contains acrylonitrile components and has certain polarity; and TPU is a thermoplastic polyurethane, which contains polar groups in its molecules and therefore also has certain polarity. Since SAN, NBR and TPU all contain polar groups, their intermolecular interactions are relatively strong, which contributes to their compatibility and mixing uniformity during the blending process. SAN and NBR both contain cyano groups (CN-), which can react with copper ions (Cu 2+ ) forms coordination bonds, and through dynamic vulcanization and in-situ interface expansion induced by metal ligand coordination, thermoplastic vulcanizate (TPV) materials with balanced stiffness and toughness can be prepared. Copper sulfate (CuSO4) is used as a metal ligand. 2+ The CuSO4 particles are refined into nanoparticles during the dynamic vulcanization process and migrate to the SAN / NBR interface, where they interact with SAN and NBR to achieve in-situ compatibilization and effectively toughen SAN without sacrificing its stiffness. After adding an appropriate amount of CuSO4, TPV exhibits excellent impact toughness.

[0008] As a toughening agent, SBS improves the impact resistance and toughness of composite materials by blending with TPU and NBR. The addition of SBS can reduce the viscosity of the composite material, improve its processing fluidity, and make the material easier to be formed by thermoplastic processing methods such as extrusion and injection molding.

[0009] Preferably, the compatibilizer is ethylene-methyl acrylate copolymer (EMA).

[0010] Preferably, the vulcanizing agent is diisopropylbenzene di-tert-butylperoxide (odorless DCP) and / or dipentadienyl peroxide (DBPH), preferably odorless DCP.

[0011] Preferably, the mass ratio of nitrile rubber to thermoplastic polyurethane elastomer is (1.5-2):1.

[0012] Preferably, the mass content of acrylonitrile in the nitrile rubber is 48-52%.

[0013] Preferably, the mass content of acrylonitrile in the styrene-acrylonitrile copolymer is 25-30 wt %.

[0014] Preferably, the NBR / TPU dynamic vulcanization material further comprises 1 to 5 parts of an antioxidant. More preferably, the antioxidant is antioxidant 1010 and / or antioxidant 168.

[0015] In a second aspect, the present invention provides a method for preparing the NBR / TPU dynamically vulcanized material, comprising the following steps:

[0016] S1, firstly, the nitrile rubber, styrene-butadiene rubber, a compatibilizer and a vulcanizing agent are banburyed at 60-80° C., and granulated to obtain an NBR / SBS composition;

[0017] S2, mixing the NBR / SBS composition with a thermoplastic polyurethane elastomer, a styrene-acrylonitrile copolymer and copper sulfate, adding the mixture into an extruder for dynamic vulcanization at 150-200° C., and then sequentially extruding, drawing, air cooling and pelletizing to obtain the NBR / TPU dynamic vulcanized material.

[0018] NBR / TPU dynamic vulcanized material belongs to thermoplastic vulcanizate (TPV), which is prepared by thermoplastic plastic matrix and rubber under dynamic full vulcanization process. Among them, NBR phase as dispersed phase has high elasticity, strong recovery ability after force deformation, and has certain strength and hardness. TPU as continuous phase has excellent processing performance. Thermoplastic vulcanized rubber has the characteristics of non-Newtonian fluid and combines the properties of TPU and NBR. Therefore, it can be extruded, injection molded, molded and blow molded like thermoplastic plastics. At the same time, it has a certain recovery ability after force deformation, and its good recyclability makes it an environmentally friendly polymer material.

[0019] Preferably, in step S1, the banburying temperature is 60-80°C for 10-20 min; and the granulation temperature is 20-30°C.

[0020] Preferably, in step S2, the aspect ratio of the extruder is (40-60):1, and the rotation speed is 300-450 rpm.

[0021] More preferably, in step S2, the temperature of dynamic vulcanization is 170-190°C.

[0022] Preferably, in step S2, the extrusion time is 10 to 15 minutes.

[0023] In a third aspect, the present invention provides the use of the NBR / TPU dynamic vulcanization material in the preparation of shoe materials.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The present invention selects to add styrene-acrylonitrile copolymer (SAN) and copper sulfate (CuSO4) as reinforcing agents for NBR and TPU. The cyanide (CN) in SAN and NBR can react with the copper ion (Cu 2+ ) forms coordination bonds, which can enhance the interaction between NBR and TPU, thereby promoting crosslinking. In addition, the three-dimensional network structure of NBR / TPU / SAN formed by the coordination crosslinking reaction can also significantly improve the physical and mechanical properties of the material. 2+ The coordination interaction with -CN solidifies the NBR phase, improves the processing performance of NBR, improves the co-continuous structure of TPVs, and increases the strength of the cross-linked network of NBR and TPU. This dynamic vulcanized material combines the performance of NBR after vulcanization, and has the elasticity of rubber, recyclable, halogen-free and environmentally friendly, good colorability, anti-slip, wear resistance, fatigue resistance and weather resistance, and still has excellent performance after foaming.

[0026] (2) The present invention combines NBR with TPU by means of dynamic vulcanization. Dynamic vulcanization is carried out during the process of melt blending of rubber and thermoplastics. The rubber is vulcanized while blending to form vulcanized rubber particles at the micron level, which are evenly dispersed in the plastic matrix. Conventional vulcanization (static vulcanization) usually uses a flat vulcanizer, and the raw rubber starts the vulcanization reaction after being heated to a certain temperature in the mold cavity. Dynamic vulcanization can enhance the mechanical strength of the material, and the entire vulcanization process does not exceed 20 minutes. Compared with static vulcanization, it can reduce the molding cooling time, shorten the molding cycle, and improve production efficiency. Therefore, the self-adhesiveness of the material obtained by the formula and preparation method of the present invention is improved, it is not easy to stick to the mold, the compression permanent deformation is reduced, and the shrinkage rate is also reduced. DETAILED DESCRIPTION

[0027] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0028] The sources of the raw materials used in the following examples and comparative example 1 are as follows:

[0029] Nitrile rubber (NBR): manufacturer is Zeon Corporation, brand name is DN003, acrylonitrile content is 50%;

[0030] Styrene-butadiene rubber (SBS): The manufacturer is Baling Petrochemical Co., Ltd., the brand is YH-792E;

[0031] Thermoplastic polyurethane elastomer (TPU): manufacturer is Covestro Polymer (China) Co., Ltd., brand number 9380A;

[0032] Styrene-acrylonitrile copolymer (SAN): manufacturer is Zhenjiang Chimei Chemical Co., Ltd., brand name is PN-128L150, acrylonitrile content is 28wt%;

[0033] Polyvinyl chloride (PVC): The manufacturer is Shanghai MacLean Biochemical Technology Co., Ltd., the brand is P815909, and the purity is K-value 72-71;

[0034] Copper sulfate: The manufacturer is Tianjin Xiensi Biochemical Technology Co., Ltd., the brand is C-11397, the purity is 98% anhydrous;

[0035] Diisopropyl ditert-butyl peroxide (odorless DCP): manufacturer is Akzo Nobel Peroxide (Ningbo) Co., Ltd., brand name is BC-FF, content is 99.6%;

[0036] Dipentadienyl sulfide (DBPH): manufacturer is Vanderbilt Chemicals, LLC, brand name is DBPH-50;

[0037] Ethylene-methyl acrylate copolymer (EMA): The manufacturer is Shandong Jinyueyuan New Materials Co., Ltd., with a purity of 99.5%.

[0038] Unless otherwise specified, other materials, reagents, etc. used in the examples and comparative examples can be obtained from commercial sources.

[0039] Example 1

[0040] A NBR / TPU dynamic vulcanization material comprises the following raw materials in parts by weight: 72 parts of nitrile rubber (NBR), 14 parts of styrene-butadiene rubber (SBS), 15 parts of styrene-acrylonitrile copolymer (SAN), 8 parts of copper sulfate, 4 parts of vulcanizing agent, 45 parts of thermoplastic polyurethane elastomer (TPU), 6 parts of compatibilizer and 4 parts of antioxidant; wherein the compatibilizer is ethylene-methyl acrylate copolymer, the vulcanizing agent is di-tert-butyl diisopropyl peroxide (odorless DCP), the mass ratio of nitrile rubber to thermoplastic polyurethane elastomer is 1.6:1, and the antioxidant is antioxidant 1010.

[0041] The preparation method of the NBR / TPU dynamic vulcanized material comprises the following steps:

[0042] S1, first add nitrile rubber, styrene-butadiene rubber, compatibilizer, antioxidant, and vulcanizer into an internal mixer, and perform internal mixing at 75° C. for 15 minutes to make the materials between the components evenly dispersed and tightly combined, and then perform granulation at 25° C. to obtain an NBR / SBS composition;

[0043] S2. The NBR / SBS composition is then mixed with a thermoplastic polyurethane elastomer, a styrene-acrylonitrile copolymer, and copper sulfate, and added to a twin-screw extruder with a length-to-diameter ratio of 50:1, an extrusion temperature of 180°C, and a rotation speed of 400 rpm for melt mixing and plasticization. Dynamic vulcanization is completed in this process, and then the NBR / TPU dynamic vulcanization material is obtained after extrusion, drawing, air cooling, pelletizing, and drying steps in sequence, wherein the extrusion time is 12 min.

[0044] Example 2

[0045] A NBR / TPU dynamic vulcanization material comprises the following raw materials in parts by weight: 60 parts of nitrile rubber (NBR), 10 parts of styrene-butadiene rubber (SBS), 10 parts of styrene-acrylonitrile copolymer (SAN), 7 parts of copper sulfate, 1 part of vulcanizing agent, 30 parts of thermoplastic polyurethane elastomer (TPU), 3 parts of compatibilizer and 1 part of antioxidant; wherein the compatibilizer is ethylene-methyl acrylate copolymer, the vulcanizing agent is dipentadienyl vulcanizer (DBPH), the mass ratio of nitrile rubber to thermoplastic polyurethane elastomer is 2:1, and the antioxidant is antioxidant 168.

[0046] The preparation method of the NBR / TPU dynamic vulcanized material comprises the following steps:

[0047] S1, first add nitrile rubber, styrene-butadiene rubber, compatibilizer, antioxidant, and vulcanizer into an internal mixer, and perform internal mixing at 60° C. for 20 min to make the materials between the components evenly dispersed and tightly combined, and then perform granulation at 20° C. to obtain an NBR / SBS composition;

[0048] S2. The NBR / SBS composition is then mixed with a thermoplastic polyurethane elastomer, a styrene-acrylonitrile copolymer and copper sulfate, and added into a twin-screw extruder with a length-to-diameter ratio of 40:1, an extrusion temperature of 160°C and a rotation speed of 450 rpm for melt mixing and plasticization. Dynamic vulcanization is completed in this process, and then the NBR / TPU dynamic vulcanization material is obtained after extrusion, drawing, air cooling, pelletizing and drying steps in sequence, wherein the extrusion time is 15 minutes.

[0049] Example 3

[0050] A NBR / TPU dynamic vulcanization material comprises the following raw materials in parts by weight: 80 parts of nitrile rubber (NBR), 20 parts of styrene-butadiene rubber (SBS), 20 parts of styrene-acrylonitrile copolymer (SAN), 10 parts of copper sulfate, 5 parts of vulcanizing agent, 50 parts of thermoplastic polyurethane elastomer (TPU), 10 parts of compatibilizer and 5 parts of antioxidant; wherein the compatibilizer is ethylene-methyl acrylate copolymer, the vulcanizing agent is di-tert-butyl diisopropyl peroxide (odorless DCP), the mass ratio of nitrile rubber to thermoplastic polyurethane elastomer is 1.6:1, and the antioxidant is antioxidant 1010.

[0051] The preparation method of the NBR / TPU dynamic vulcanized material comprises the following steps:

[0052] S1. First, add nitrile rubber, styrene-butadiene rubber, compatibilizer, antioxidant and vulcanizing agent into an internal mixer, and perform internal mixing at 80° C. for 10 min to make the materials between the components evenly dispersed and tightly combined, and then perform granulation at 30° C. to obtain an NBR / SBS composition;

[0053] S2. The NBR / SBS composition is then mixed with a thermoplastic polyurethane elastomer, a styrene-acrylonitrile copolymer and copper sulfate, and added into a twin-screw extruder with a length-to-diameter ratio of 60:1, an extrusion temperature of 200°C and a rotation speed of 300 rpm for melt mixing and plasticization. Dynamic vulcanization is completed in this process, and then the NBR / TPU dynamic vulcanization material is obtained after extrusion, drawing, air cooling, pelletizing and drying steps in sequence, wherein the extrusion time is 10 minutes.

[0054] Example 4

[0055] The difference between Example 4 and Example 1 is that: 72 parts of nitrile rubber (NBR) and 48 parts of thermoplastic polyurethane elastomer (TPU), that is, the mass ratio of nitrile rubber to thermoplastic polyurethane elastomer is 1.5:1.

[0056] Example 5

[0057] The difference between Example 5 and Example 1 is that: the difference between Example 5 and Example 1 is that: 72 parts of nitrile rubber (NBR) and 36 parts of thermoplastic polyurethane elastomer (TPU), that is, the mass ratio of nitrile rubber to thermoplastic polyurethane elastomer is 2:1.

[0058] Example 6

[0059] The difference between Example 6 and Example 1 is that: the difference between Example 6 and Example 1 is that: 72 parts of nitrile rubber (NBR) and 50 parts of thermoplastic polyurethane elastomer (TPU), that is, the mass ratio of nitrile rubber to thermoplastic polyurethane elastomer is 1.44:1.

[0060] Example 7

[0061] The difference between Example 7 and Example 1 is that: the difference between Example 7 and Example 1 is that: 63 parts of nitrile rubber (NBR) and 30 parts of thermoplastic polyurethane elastomer (TPU), that is, the mass ratio of nitrile rubber to thermoplastic polyurethane elastomer is 2.1:1.

[0062] Example 8

[0063] The difference between Example 8 and Example 1 is that the extrusion temperature of step S2 in the preparation method of the NBR / TPU dynamic vulcanization material of Example 8 is 160°C.

[0064] Example 9

[0065] The difference between Example 9 and Example 1 is that the extrusion temperature of step S2 in the preparation method of the NBR / TPU dynamic vulcanization material of Example 9 is 170°C.

[0066] Example 10

[0067] The difference between Example 10 and Example 1 is that the extrusion temperature of step S2 in the preparation method of the NBR / TPU dynamic vulcanization material of Example 10 is 190°C.

[0068] Embodiment 11

[0069] The difference between Example 11 and Example 1 is that the extrusion temperature of step S2 in the preparation method of the NBR / TPU dynamic vulcanization material of Example 11 is 200°C.

[0070] Comparative Example 1

[0071] The difference between Comparative Example 1 and Example 1 is that SBS is not added in Comparative Example 1.

[0072] Comparative Example 2

[0073] The difference between Comparative Example 2 and Example 1 is that no SAN is added in Comparative Example 2.

[0074] Comparative Example 3

[0075] The difference between Comparative Example 3 and Example 1 is that in Comparative Example 3, SAN is replaced by polyvinyl chloride (PVC).

[0076] Comparative Example 4

[0077] The difference between Comparative Example 4 and Example 1 is that: Comparative Example 4 does not add copper sulfate.

[0078] Comparative Example 5

[0079] The difference between Comparative Example 5 and Example 1 is that the amount of vulcanizing agent added in Comparative Example 5 is 0.5 parts.

[0080] Comparative Example 6

[0081] The difference between Comparative Example 6 and Example 1 is that the amount of vulcanizing agent added in Comparative Example 6 is 6 parts.

[0082] Comparative Example 7

[0083] The difference between Comparative Example 7 and Example 1 is that all the raw materials are directly put into a twin-screw extruder for dynamic vulcanization without mixing and granulation.

[0084] Comparative Example 8

[0085] The difference between Comparative Example 8 and Example 1 is that step S2 of the preparation method of Comparative Example 8 selects a static vulcanization step, and the NBR / SBS composition, thermoplastic polyurethane elastomer, styrene-acrylonitrile copolymer, and copper sulfate are placed in a flat vulcanizer, pressed into a sheet at 170° C. and a pressure of 10 MPa for 20 minutes, and then cold-pressed at room temperature for 5 minutes to set.

[0086] Comparative Example 9

[0087] The difference between Comparative Example 9 and Example 1 is that the extrusion temperature of step S2 in the preparation method of the NBR / TPU dynamically vulcanized material is 210°C.

[0088] Performance Testing

[0089] The samples of Examples 1 to 11 and Comparative Examples 1 to 9 were tested as follows:

[0090] (1) Tensile test

[0091] According to the standard GB / T 528-2009, the injection-molded samples were cut into standard dumbbell-shaped specimens with a length of 25.0 mm ± 1.0 mm, a thickness of 2.0 mm ± 0.2 mm, and a width of 4.0 mm ± 0.1 mm using a punching machine, and tested using a universal testing machine. The data are shown in Table 1.

[0092] (2) Compression set test

[0093] According to the standard GB / T 7759.1-2015, the injection molded samples were cut into cylindrical standard B-type samples with a diameter of 13.0 mm ± 0.5 mm and a height of 6.3 mm ± 0.3 mm using a punching machine. Each group of samples had 5 samples. The aging box temperature was 40 °C and the test time was 22 h. The data is shown in Table 1.

[0094] (3) Hardness test

[0095] According to the standard GB / T2411-2008, the sample was cut with a punching machine, the thickness was 6mm, and the hardness was measured with a Shore A hardness tester. The data is shown in Table 1.

[0096] (4) Melt flow rate test

[0097] According to the standard ASTM D1238, the fluidity of each group of samples was tested using a melt index tester, the test temperature was 190°C, and the nominal weight load was 10kg. Before the test, the sample pellets were placed in a drying oven and dried at 80°C for 4 hours. The data are shown in Table 1.

[0098] Table 1 Experimental data of each group of samples

[0099]

[0100]

[0101] As can be seen from Table 1, Examples 1 and 4 to 7 are intended to explore the effect of the mass ratio of NBR and TPU on product performance. It can be seen from the data that when the mass ratio of nitrile rubber to thermoplastic polyurethane elastomer is (1.5 to 2): 1, the fluidity and formability during processing such as extrusion and injection molding are good, thereby significantly improving the mechanical strength and compression permanent deformation performance of the product.

[0102] Example 1, Example 8 to 11 and Comparative Example 9 are used to explore the effect of vulcanization temperature on product performance. When the vulcanization temperature is 160°C, the vulcanization temperature is low, and its performance is poor compared with 170 to 190°C, and the tensile properties are poor. When the vulcanization temperature ranges from 170 to 190°C, as the dynamic vulcanization temperature increases, the viscosity of the system decreases, the molecular thermal motion intensifies, and the distance between the molecular chains increases, which is conducive to the movement of the rubber molecular chains, thereby making the dispersion of the rubber phase more uniform. At the same time, the increase in temperature also increases the cross-linking rate of silicone rubber, the degree of rubber cross-linking, and the cross-linking network is more perfect, which is manifested as an increase in the tensile strength and elongation at break of TPV. However, when the temperature is higher than 200°C, the viscosity of TPU decreases significantly, which is not conducive to the shear dispersion of cross-linked silicone rubber during mixing, and too high a temperature will also cause the cross-linking bonds of silicone rubber to crack, which will cause the breakage of the internal molecular chains of TPU, leading to the degradation of TPU, thereby causing a significant decrease in the tensile properties of the product.

[0103] In Comparative Example 1, no SBS is added, so the mechanical strength and processing performance of the product are significantly reduced, indicating that SBS is a toughening agent, which improves the impact resistance and toughness of the composite material by blending with TPU and NBR. The addition of SBS can reduce the viscosity of the composite material, improve its processing fluidity, and make the material easier to be molded by thermoplastic processing methods such as extrusion and injection molding.

[0104] In Comparative Example 2, no SAN is added, and its mechanical properties and melt flow rate are significantly reduced, indicating that SAN can be used as a reinforcing agent for NBR and TPU. At the same time, the cyanide group (CN-) it contains can also form a coordination bond with copper ions (Cu2+), and the three-dimensional network structure formed by the coordination cross-linking reaction can also significantly improve the physical and mechanical properties of the material.

[0105] In Comparative Example 3, SAN is replaced by PVC. Although PVC has good compatibility with TPU, it has poor compatibility with NBR. PVC also has an island structure with NBR, which cannot solve the technical problem of poor interface compatibility between TPU and NBR. In addition, it does not contain cyanide (CN-) and cannot react with copper ions (Cu 2+ ) forms a coordination bond, so it is verified that SAN is the hub for improving the compatibility of NBR and TPU, and also forms a coordination bond with copper ions (Cu 2+ ) form coordination bonds to further promote cross-linking.

[0106] In Comparative Example 4, copper sulfate is not added, and the lack of copper ions to form coordination bonds with cyanide (CN-) in both SAN and NBR significantly reduces the mechanical properties of the material. 2+ The coordination interaction with -CN solidifies the NBR phase, improves the processing properties of NBR, improves the co-continuous structure of TPVs, and increases the strength of the cross-linked network of NBR and TPU.

[0107] Example 1 and Comparative Examples 5 to 6 are to explore the effect of the amount of vulcanizing agent on product performance. The amount of vulcanizing agent added in Comparative Example 5 is too low, resulting in insufficient vulcanization. The cross-linked network density formed by cross-linking the rubber particles by the vulcanizing agent is low, and the fluidity of the rubber in the molten state increases, but the mechanical properties of the material are significantly reduced. The amount of vulcanizing agent added in Comparative Example 6 is too high, which accelerates the vulcanization rate, intensifies shear heat generation, and cracks the cross-linked bonds under the action of thermal oxygen, destroys the cross-linked network, and significantly reduces the mechanical strength of the product. Because the entanglement between the molecular chains is reduced, the molecular chains are more likely to slip, so the melt flow rate becomes larger. It can be seen that the amount of vulcanizing agent added in the product is 1-5 parts, which is a reasonable range, which can take into account both fluidity and molding, and has good mechanical strength.

[0108] The performance of Comparative Example 7 is also significantly reduced without internal mixing. Because the internal mixer can complete the mixing process in a shorter time, the production efficiency is improved. The rotor design of the internal mixer and the strong mechanical action in the mixing chamber help to accelerate the mixing and plasticization of the materials, thereby shortening the subsequent vulcanization cycle.

[0109] Comparative Example 8 is treated by static vulcanization, which is a process in which the prepared raw rubber is fixed in the rubber mold cavity in a flat vulcanizer, and the vulcanization reaction begins after heating to a certain temperature. After high-temperature pressing, it is usually necessary to cool and then perform secondary pressing, and the molding cycle is relatively long. Compared with static vulcanization, the dynamic vulcanization selected in Example 1 can reduce the molding cooling time, shorten the molding cycle, improve production efficiency, and enhance the mechanical strength and processing performance of the material.

[0110] And each material is a homogeneous material in the traditional vulcanization, wherein crosslinking occurs in the whole rubber matrix, rather than in the dispersed rubber phase. And the material prepared by the dynamic vulcanization adopted by the present invention, wherein NBR is used as the dispersed phase, and TPU is used as the continuous phase. In the dynamic vulcanization process, the rubber phase is vulcanized into micron-sized particles in the thermoplastic matrix, and these particles are evenly dispersed in the plastic matrix. This structure gives the material the characteristics of combining the high elasticity of traditional vulcanized rubber and the processing convenience of thermoplastics.

Claims

1. A NBR / TPU dynamic vulcanized material, characterized in that: The invention comprises the following raw materials in parts by weight: 60-80 parts of nitrile rubber, 10-20 parts of styrene-butadiene rubber, 10-20 parts of styrene-acrylonitrile copolymer, 7-10 parts of copper sulfate, 1-5 parts of vulcanizing agent, 30-50 parts of thermoplastic polyurethane elastomer and 3-10 parts of compatibilizer; The preparation method of NBR / TPU dynamic vulcanized material comprises the following steps: S1, firstly, the nitrile rubber, styrene-butadiene rubber, a compatibilizer and a vulcanizing agent are banburyed at 60-80° C., and granulated to obtain an NBR / SBS composition; S2, mixing the NBR / SBS composition with a thermoplastic polyurethane elastomer, a styrene-acrylonitrile copolymer and copper sulfate, adding the mixture into an extruder for dynamic vulcanization at 150-200° C., and then sequentially extruding, drawing, air cooling and pelletizing to obtain the NBR / TPU dynamic vulcanized material.

2. The NBR / TPU dynamically vulcanized material according to claim 1, characterized in that: The compatibilizer is ethylene-methyl acrylate copolymer.

3. The NBR / TPU dynamically vulcanized material according to claim 1, characterized in that: The vulcanizing agent is di-tert-butyl peroxide diisopropylbenzene and / or dipentadienyl vulcanizing agent.

4. The NBR / TPU dynamically vulcanized material according to claim 1, characterized in that: The mass ratio of nitrile rubber to thermoplastic polyurethane elastomer is (1.5-2):

1.

5. The NBR / TPU dynamically vulcanized material according to claim 1, characterized in that: The mass content of acrylonitrile in the nitrile rubber is 48-52%.

6. The NBR / TPU dynamically vulcanized material according to claim 1, characterized in that: The mass content of acrylonitrile in the styrene-acrylonitrile copolymer is 25-30wt%.

7. The NBR / TPU dynamically vulcanized material according to claim 1, characterized in that: The NBR / TPU dynamic vulcanization material also includes 1 to 5 parts of antioxidant.

8. The NBR / TPU dynamically vulcanized material according to claim 1, characterized in that: In step S2 of the preparation method, the aspect ratio of the extruder is (40-60):1, and the rotation speed of the dynamic vulcanization is 300-450 rpm.

9. Use of the NBR / TPU dynamic vulcanization material according to any one of claims 1 to 8 in the preparation of shoe materials.

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