Thermoplastic vulcanized rubber and preparation method thereof

Abstract

The invention provides thermoplastic vulcanized rubber and a preparation method thereof. The thermoplastic vulcanized rubber comprises a base material and an additive, the base material comprises rubber and thermoplastic polyurethane, and the additive comprises a vulcanizing agent, a compatibilizer and a reinforcing filler; wherein the content of the vulcanizing agent is 3 to 10 parts, the content of the compatibilizer is 0.5 to 5 parts, and the content of the reinforcing filler is 0 to 20 parts based on 100 percent of the weight of the base material; and the compatibilizer comprises epoxidized butyl rubber and maleic anhydride grafted thermoplastic polyurethane. The compatibility of rubber and thermoplastic polyurethane in the thermoplastic vulcanized rubber is excellent, and the thermoplastic vulcanized rubber has a fine microphase structure. And the thermoplastic vulcanized rubber has excellent mechanical properties, excellent elasticity and slip resistance, and excellent wear resistance. The preparation method of the thermoplastic vulcanizate is simple and easy to implement, raw materials are easy to obtain, and the thermoplastic vulcanizate is suitable for mass production.

Description

Technical Field

[0001] The invention relates to a thermoplastic vulcanizate and a preparation method thereof, and belongs to the field of polymer material processing. Background Art

[0002] Thermoplastic vulcanizates are a type of thermoplastic elastomer prepared by dynamic vulcanization reaction blending technology. They are formed by blending incompatible or poorly compatible rubber and thermoplastic resin. Under the action of high shear force and temperature, the rubber is selectively vulcanized in situ to form a blend with a high content of cross-linked rubber particles as the dispersed phase and a small amount of thermoplastic resin as the continuous phase.

[0003] The physical properties and elasticity of thermoplastic vulcanizates at room temperature are similar to those of traditional rubber. At high temperatures, they can be processed and formed as quickly and economically as thermoplastics. They can be recycled and reused after being discarded. They have lower processing costs and can replace thermosetting rubber, fundamentally solving the problem that traditional cross-linked rubber is difficult to recycle and reuse. They can also greatly improve the elasticity of plastic products.

[0004] In order to meet market demand, thermoplastic elastomers with many different properties, functions and uses can be developed by regulating the thermoplastic vulcanizate system and composition. The various properties of thermoplastic elastomers mainly depend on the properties of the substrate material and its microstructure. And as far as thermoplastic elastomers are concerned, due to the thermodynamic incompatibility of the two-phase system, in order to make its mechanical properties and elasticity more similar to those of traditional rubber, it is necessary to develop corresponding compatibilizers for the system, and complete dynamic vulcanization process regulation during the preparation process, which is a feature and difficulty in the existing technology.

[0005] Butyl rubber is the fourth largest synthetic rubber in the world. It is a highly saturated rubber obtained by cationic copolymerization of isobutylene and a small amount of isoprene. It has good air tightness, shock absorption, heat resistance, aging resistance and anti-slip properties. Thermoplastic polyurethane has excellent low temperature and impact strength, high durability, flexibility, good wear resistance and scratch resistance, and is easy to process. Butyl rubber / thermoplastic polyurethane thermoplastic vulcanizate has the excellent properties of butyl rubber and thermoplastic polyurethane, with the advantages of softness, wear resistance and aging resistance, especially excellent elasticity, sealing and anti-slip properties, simple production process, can be widely used in automotive sealing strips, medical plugs, sole materials, sports equipment and other fields, providing solutions for energy conservation and carbon reduction in the automotive industry, medical industry and footwear manufacturing industry.

[0006] However, butyl rubber and thermoplastic polyurethane have poor compatibility, and the rubber is not easily sheared and broken to form uniform and tiny dispersed phase particles in the thermoplastic polyurethane matrix, which ultimately leads to the microscopic phase structure of the thermoplastic vulcanizate formed being not fine enough, thereby affecting its mechanical properties and processing properties. In summary, for thermoplastic vulcanizates prepared from butyl rubber / thermoplastic polyurethane, solving the compatibility of the two substrates has always been a difficult point in research.

[0007] Reference 1 discloses a thermoplastic vulcanizate composition, a preparation method thereof and a shoe material, wherein the thermoplastic vulcanizate composition comprises a plastic phase and a rubber phase. The plastic phase comprises a thermoplastic polyurethane, and the rubber phase comprises a rubber, a free radical bridging initiator and an additive. The total weight of the rubber is 100 parts by weight, the content of the free radical bridging initiator is 0.02 parts by weight to 5.0 parts by weight, and the content of the additive is 0.1 parts by weight to 20 parts by weight. The plastic phase and the rubber phase are mixed evenly, and the weight ratio of the plastic phase to the rubber phase is 80:20 to 20:80. From the molecular structure analysis of the two substrate materials (butyl rubber and polyurethane), the main chain molecular structures are greatly different, and there must be thermodynamic incompatibility problems.

[0008] Reference 1: CN115073912A Summary of the invention

[0009] Problem that the invention aims to solve

[0010] In view of the technical problems existing in the prior art, for example, the compatibility between rubber and thermoplastic polyurethane is poor, the rubber is not easily sheared and crushed to form uniform and tiny particles dispersed in the thermoplastic polyurethane matrix, which ultimately leads to the microscopic phase structure of the formed thermoplastic vulcanizate being not fine enough, thereby affecting its mechanical properties and processing properties, etc., the present invention first provides a thermoplastic vulcanizate.

[0011] The thermoplastic vulcanizate of the present invention has excellent compatibility between the rubber and the thermoplastic polyurethane and has a fine microphase structure. The thermoplastic vulcanizate also has excellent mechanical properties, excellent elasticity and anti-slip properties, and excellent wear resistance.

[0012] The invention also provides a method for preparing a thermoplastic vulcanizate. The method is simple and easy to implement, the raw materials are easy to obtain, and the method is suitable for mass production.

[0013] Solutions for solving problems

[0014] The present invention provides a thermoplastic vulcanizate, which comprises a base material and an additive; the base material comprises rubber and thermoplastic polyurethane, and the additive comprises a vulcanizing agent, a compatibilizer and a reinforcing filler; wherein,

[0015] Based on 100% by weight of the substrate, the content of the vulcanizing agent is 3 to 10 parts, the content of the compatibilizer is 0.5 to 5 parts, and the content of the reinforcing filler is 0 to 20 parts; and,

[0016] The compatibilizers include epoxidized butyl rubber and maleic anhydride grafted thermoplastic polyurethane.

[0017] According to the thermoplastic vulcanizate of the present invention, the content of the rubber is 10 to 90 parts, and the content of the thermoplastic polyurethane is 10 to 90 parts, based on 100% by weight of the substrate;

[0018] Preferably, the rubber includes one or a combination of two or more of butyl rubber, chlorinated butyl rubber and brominated butyl rubber; and / or, the thermoplastic polyurethane includes a thermoplastic polyether polyurethane elastomer and / or a thermoplastic polyester polyurethane elastomer.

[0019] According to the thermoplastic vulcanizate of the present invention, the mass ratio of the epoxidized butyl rubber to the thermoplastic polyurethane grafted with maleic anhydride is 1:1 to 1:10;

[0020] Preferably, the weight average molecular weight of the epoxidized butyl rubber is 5000-100000 Da; and / or, in terms of molar percentage, the grafting rate of maleic anhydride in the maleic anhydride-grafted thermoplastic polyurethane is 1-5%.

[0021] According to the thermoplastic vulcanizate of the present invention, the preparation method of the epoxidized butyl rubber comprises the following steps:

[0022] The xylene solution of liquid butyl rubber is mixed with a mixed solution of hydrogen peroxide and formic acid, and subjected to epoxidation reaction to obtain the epoxidized butyl rubber;

[0023] Preferably, the temperature of the epoxidation reaction is 30 to 50° C., and the time of the epoxidation reaction is 3 to 8 hours.

[0024] According to the thermoplastic vulcanizate of the present invention, wherein the mass fraction of the liquid butyl rubber in the xylene solution of the liquid butyl rubber is 10 to 30%; and / or,

[0025] In the mixed solution of hydrogen peroxide and formic acid, the molar ratio of formic acid to hydrogen peroxide is (1-2):(1-2); preferably, the mixed solution of hydrogen peroxide and formic acid comprises a mixture of a hydrogen peroxide aqueous solution with a mass fraction of 20-40% and a formic acid aqueous solution with a mass fraction of 80-95%.

[0026] According to the thermoplastic vulcanizate of the present invention, the vulcanizing agent includes one or a combination of two or more of phenolic resin, stannous chloride, 2,5-dimethyl-2,5-bis(tert-butyl peroxide)-3-hexyne, zinc oxide, stearic acid, and zinc stearate.

[0027] According to the thermoplastic vulcanizate of the present invention, the reinforcing filler comprises one or a combination of two or more of modified nanocellulose, modified white carbon black, carbon black, and modified biomass powder.

[0028] According to the thermoplastic vulcanizate of the present invention, the additive further comprises an antioxidant; preferably, based on 100% by weight of the substrate, the content of the antioxidant is 0.1 to 3 parts;

[0029] More preferably, the antioxidant is a hindered phenol antioxidant and / or a phosphite antioxidant.

[0030] The present invention also provides a method for preparing the thermoplastic vulcanizate according to the present invention, which comprises the steps of mixing the components of the thermoplastic vulcanizate and then subjecting the mixture to dynamic vulcanization treatment; preferably, the preparation method comprises the following steps:

[0031] The rubber and the reinforcing filler are mixed in an internal mixer to obtain a mixed rubber;

[0032] The mixed rubber and thermoplastic polyurethane are mixed in an internal mixer, kept warm, and a compatibilizer and an optional antioxidant are added and continued to mix to obtain a mixed product;

[0033] The mixed product is mixed with a vulcanizing agent in an open mill to obtain a rubber-plastic premix;

[0034] The rubber-plastic premix is ​​subjected to dynamic vulcanization treatment in a twin-screw extruder to obtain a thermoplastic vulcanizate.

[0035] According to the preparation method of the present invention, the temperature of mixing the rubber compound and the thermoplastic polyurethane is 170-260° C.; and / or,

[0036] The temperature of the dynamic vulcanization is 170° C. to 260° C., and the rotation speed of the dynamic vulcanization is 300 to 800 rpm.

[0037] Effects of the Invention

[0038] The thermoplastic vulcanizate of the present invention has excellent compatibility between the rubber and the thermoplastic polyurethane and has a fine microphase structure. The thermoplastic vulcanizate also has excellent mechanical properties, excellent elasticity and anti-slip properties, and excellent wear resistance.

[0039] The preparation method of the thermoplastic vulcanizate of the invention is simple and easy to implement, the raw materials are easy to obtain, and it is suitable for mass production. DETAILED DESCRIPTION

[0040] Various exemplary embodiments, features and aspects of the present invention will be described in detail below. The word "exemplary" used here means "used as an example, embodiment or illustrative". Any embodiment described here as "exemplary" is not necessarily interpreted as being superior or better than other embodiments.

[0041] In addition, in order to better illustrate the present invention, numerous specific details are provided in the following specific embodiments. It should be understood by those skilled in the art that the present invention can be implemented without certain specific details. In other examples, methods, means, equipment and steps well known to those skilled in the art are not described in detail in order to highlight the subject matter of the present invention.

[0042] Unless otherwise stated, the units used in this specification are all international standard units, and the numerical values ​​and numerical ranges appearing in the present invention should be understood to include the inevitable systematic errors in industrial production.

[0043] In this specification, the word "may" means both performing a certain process and not performing a certain process.

[0044] In this specification, the references to "some specific / preferred embodiments", "other specific / preferred embodiments", "embodiments", etc., mean that the specific elements (e.g., features, structures, properties and / or characteristics) described in connection with the embodiments are included in at least one embodiment described herein, and may or may not exist in other embodiments. In addition, it should be understood that the elements may be combined in various embodiments in any suitable manner.

[0045] In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints A and B.

[0046] In this specification, when "normal temperature" or "room temperature" is used, it means 15 to 30°C.

[0047] <First aspect>

[0048] The first aspect of the present invention provides a thermoplastic vulcanizate, which includes a base material and an additive; the base material includes rubber and thermoplastic polyurethane, and the additive includes a vulcanizer, a compatibilizer and a reinforcing filler; wherein,

[0049] Based on 100% by weight of the substrate, the content of the vulcanizing agent is 3 to 10 parts, the content of the compatibilizer is 0.5 to 5 parts, and the content of the reinforcing filler is 0 to 20 parts; and,

[0050] The compatibilizers include epoxidized butyl rubber and maleic anhydride grafted thermoplastic polyurethane.

[0051] The base rubber in the thermoplastic vulcanizate of the invention has excellent compatibility with thermoplastic polyurethane, has a fine microphase structure, excellent mechanical properties, excellent elasticity and anti-slip properties, and excellent wear resistance.

[0052] Substrate

[0053] In the present invention, the substrate includes rubber and thermoplastic polyurethane.

[0054] The thermoplastic vulcanizate of the present invention is obtained by dispersing cross-linked rubber phase (rubber) particles in a plastic phase (thermoplastic polyurethane). The rubber phase provides high elasticity, and the plastic phase provides high-temperature reproducibility. The combination of the two realizes the thermoplastic vulcanizate's high elasticity at room temperature and high-temperature reproducibility.

[0055] In some specific embodiments, based on the weight percentage of the substrate being 100%, the content of the rubber is 10 to 90 parts, for example, 15 parts, 25 parts, 35 parts, 45 parts, 55 parts, 65 parts, 75 parts, 85 parts, etc.; the content of the thermoplastic polyurethane is 10 to 90 parts, for example, 15 parts, 25 parts, 35 parts, 45 parts, 55 parts, 65 parts, 75 parts, 85 parts, etc. In the present invention, if the content of the rubber is too low, the content of the thermoplastic polyurethane is too high, and its high elasticity at room temperature cannot be achieved. If the content of the rubber is too high, the content of the thermoplastic polyurethane phase is too low, and it is difficult to successfully prepare and achieve high-temperature repeatable processing.

[0056] Specifically, in the present invention, the rubber includes butyl rubber or a derivative of butyl rubber; specifically, the rubber includes one or a combination of two or more of butyl rubber, chlorinated butyl rubber and brominated butyl rubber; the present invention preferably uses butyl rubber or a derivative of butyl rubber, which can provide excellent anti-slip properties, while thermoplastic polyurethane provides wear resistance. The thermoplastic polyurethane includes thermoplastic polyether polyurethane elastomer and / or thermoplastic polyester polyurethane elastomer.

[0057] Compatibilizer

[0058] The inventors of the present invention have found that by using the compatibilizer of the present invention, the compatibility between the rubber of the substrate and the thermoplastic polyurethane can be effectively improved, and further combined with the dynamic vulcanization technology to prepare a thermoplastic vulcanizate with a fine microphase structure, excellent mechanical properties, excellent elasticity and anti-slip properties, and excellent wear resistance.

[0059] In some specific embodiments, the weight average molecular weight of the epoxidized butyl rubber is 5000-100000Da, for example: 8000Da, 10000Da, 20000Da, 40000Da, 60000Da, 80000Da, etc. When the weight average molecular weight of the epoxidized butyl rubber is 5000-100000Da, during the blending preparation process, the compatibilizer easily migrates to the interface of the two phases, and an interfacial entanglement reaction occurs, thereby improving the compatibilization efficiency.

[0060] In some specific embodiments, the method for preparing the epoxidized butyl rubber comprises the following steps: mixing a xylene solution of liquid butyl rubber with a mixed solution of hydrogen peroxide and formic acid, and subjecting the mixture to an epoxidation reaction to obtain the epoxidized butyl rubber.

[0061] Specifically, in the present invention, in the xylene solution of the liquid butyl rubber, the mass fraction of the liquid butyl rubber is 10-30%, for example: 12%, 15%, 18%, 20%, 22%, 25%, 28%, etc.

[0062] In the preparation of the epoxidized butyl rubber of the present invention, formic acid can be used as a catalyst to promote the reaction of hydrogen peroxide with the double bonds of butyl rubber to generate epoxy functional groups, which can enable the reaction to proceed successfully. The epoxy functional groups are further used to react with thermoplastic polyurethane grafted with maleic anhydride to generate butyl rubber grafted thermoplastic polyurethane. The use of formic acid as a compatibilizer can promote the interfacial compatibility between the substrate butyl rubber and the thermoplastic polyurethane, thereby improving various performance indicators of the thermoplastic vulcanizate.

[0063] In the mixed solution of hydrogen peroxide and formic acid, the molar ratio of formic acid to hydrogen peroxide is (1-2):(1-2), for example: 1:1, 1:1.2, 1:1.5, 1:1.8, 1:2, 2:1, 1.2:1, 1.5:1, 1.8:1, 2:1, etc. When the molar ratio of formic acid to hydrogen peroxide is (1-2):(1-2), the catalytic effect of formic acid can be effectively exerted, and the reaction of hydrogen peroxide and butyl rubber can be promoted to proceed better.

[0064] Furthermore, in the present invention, the mixed solution of hydrogen peroxide and formic acid is obtained by mixing a hydrogen peroxide aqueous solution with a mass fraction of 20 to 40% and a formic acid aqueous solution with a mass fraction of 80 to 95%. Of course, the mixed solution of hydrogen peroxide and formic acid can also be prepared by other methods, and the present invention does not make any specific restrictions here.

[0065] In some specific embodiments, in the maleic anhydride grafted thermoplastic polyurethane, the grafting rate of maleic anhydride is 1-5% by mole percentage, for example: 1.1%, 1.3%, 1.5%, 1.7%, 1.9%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, etc. When the grafting rate of maleic anhydride is 1-5%, the reaction efficiency with the epoxy group on the epoxidized butyl rubber is higher.

[0066] In some specific embodiments, the epoxidation reaction temperature is 30-50°C, for example: 32°C, 35°C, 38°C, 40°C, 42°C, 45°C, 48°C, etc.; the epoxidation reaction time is 3-8 hours, for example: 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 7.5 hours, etc. When the epoxidation reaction temperature is 30-50°C and the epoxidation reaction time is 3-8 hours, the reaction can be further completed, and the purity of the obtained epoxidized butyl rubber is higher.

[0067] Furthermore, in the present invention, after the epoxidation reaction, a step of removing the solvent is also included, and the solvent can be removed by rotary evaporation using a rotary evaporator.

[0068] In the present invention, maleic anhydride grafted thermoplastic polyurethane and epoxidized butyl rubber react to generate an ester compound. The inventors of the present invention have found that one end of the ester compound is similar to the molecular chain structure of the rubber in the substrate, and the other end is physically compatible with the thermoplastic polyurethane, thereby improving the compatibility of the rubber in the substrate with the thermoplastic polyurethane.

[0069] In the present invention, the mass ratio of the epoxidized butyl rubber to the thermoplastic polyurethane grafted with maleic anhydride can be 1:1 to 1:10, for example, 1:2, 1:4, 1:6, 1:8, etc.; if the mass ratio of the epoxidized butyl rubber to the thermoplastic polyurethane grafted with maleic anhydride is 1:1 to 1:10, when the epoxidized butyl rubber and the thermoplastic polyurethane grafted with maleic anhydride are used as compound compatibilizers, the compatibilization efficiency is higher.

[0070] In the present invention, based on the weight of the substrate as 100%, the content of the compatibilizer is 0.5 to 5 parts, for example: 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, etc. When the content of the compatibilizer is 0.5 to 5 parts, the compatibilization effect is better. In the present invention, if the content of the compatibilizer is less than 0.5 parts, it will not have a compatibilization effect and will not promote the interface interaction between the rubber and the thermoplastic polyurethane in the substrate; if the content of the compatibilizer exceeds 5 parts, the low molecular weight compatibilizer will reduce the mechanical properties of the material and the cost is relatively high.

[0071] Vulcanizing agent

[0072] In the present invention, the vulcanizing agent promotes the chemical reaction between the molecular chains of the rubber phase, forms a three-dimensional cross-linked structure in the process of shearing and crushing, and realizes phase inversion to prepare the thermoplastic vulcanizate.

[0073] In the present invention, based on 100% by weight of the substrate, the content of the vulcanizing agent is 0.5 to 3 parts, for example, 0.8 parts, 1 part, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, 2.2 parts, 2.5 parts, 2.8 parts, etc. In the present invention, if the content of the vulcanizing agent is too little, the degree of crosslinking is insufficient; if the content of the vulcanizing agent is too much, the degree of crosslinking is too high, and the crosslinking speed is too fast to achieve phase inversion.

[0074] Specifically, in the present invention, the vulcanizing agent includes one or a combination of two or more of phenolic resin, stannous chloride, 2,5-dimethyl-2,5-bis(tert-butyl peroxide)-3-hexyne, zinc oxide, stearic acid, and zinc stearate.

[0075] Reinforcement filler

[0076] The invention increases the rigidity, strength and wear resistance of the thermoplastic vulcanizate by making the reinforcing filler interact with the rubber in the base material, and improves the processing performance and service life of the rubber in the base material.

[0077] In some specific embodiments, based on 100% by weight of the substrate, the content of the reinforcing filler is 0 to 20 parts, preferably 1 to 20 parts; for example: 2 parts, 5 parts, 8 parts, 10 parts, 12 parts, 15 parts, 18 parts, etc.; when the content of the reinforcing filler is greater than 20 parts, agglomerates will be formed in the substrate and cannot be evenly dispersed, resulting in a decrease in the performance of the thermoplastic vulcanizate.

[0078] Specifically, in the present invention, the reinforcing filler includes one or a combination of two or more of modified nanocellulose, modified silica, carbon black, and modified biomass powder.

[0079] Other additives

[0080] In the present invention, the additive may further include an antioxidant; by adding an antioxidant, the antioxidant performance of the thermoplastic vulcanizate can be improved. Preferably, based on 100% by weight of the substrate, the content of the antioxidant is 0.1 to 3 parts, for example: 0.5 parts, 1 parts, 1.5 parts, 2 parts, 2.5 parts, etc. If the content of the antioxidant is too high, the antioxidant performance cannot be further increased, and other properties of the thermoplastic vulcanizate may be affected.

[0081] The antioxidant includes a hindered phenol antioxidant and / or a phosphite antioxidant; specifically, the antioxidant includes one or a combination of two or more of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol ester (antioxidant 1010), tris[2.4-di-tert-butylphenyl] phosphite (antioxidant 168), and 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione.

[0082] <Second Aspect>

[0083] The second aspect of the present invention provides a method for preparing the thermoplastic vulcanizate according to the first aspect of the present invention, comprising the steps of mixing the components of the thermoplastic vulcanizate and then subjecting the mixture to dynamic vulcanization treatment; preferably, the preparation method comprises the following steps:

[0084] The rubber and the reinforcing filler are mixed in an internal mixer to obtain a mixed rubber;

[0085] The mixed rubber and thermoplastic polyurethane are mixed in an internal mixer, kept warm, and a compatibilizer and an optional antioxidant are added and continued to mix to obtain a mixed product;

[0086] The mixed product is mixed with a vulcanizing agent in an open mill to obtain a rubber-plastic premix;

[0087] The rubber-plastic premix is ​​subjected to dynamic vulcanization treatment in a twin-screw extruder to obtain a thermoplastic vulcanizate.

[0088] In some specific embodiments, the temperature of mixing the rubber compound and the thermoplastic polyurethane is 170-260°C, for example, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, etc. In the present invention, in the rubber-plastic premixing process, the compatibilizer is directly mixed with the rubber compound at a temperature of 170-260°C to perform high-temperature reaction and volume expansion, thereby obtaining a rubber-plastic premix.

[0089] The temperature of the dynamic vulcanization is 170°C to 260°C, for example, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, etc. The rotation speed of the dynamic vulcanization is 300 to 800 rpm, for example, 350 rpm, 400 rpm, 450 rpm, 500 rpm, 550 rpm, 600 rpm, 650 rpm, 700 rpm, 750 rpm, etc.

[0090] Specifically, the preparation method comprises the following steps:

[0091] (1) Accurately weigh the rubber and reinforcing filler, and mix them evenly in an internal mixer at a temperature of 15 to 30°C to obtain a rubber compound.

[0092] (2) Rubber and plastic premixing: The rubber compound and thermoplastic polyurethane are put into an internal mixer at 170°C to 260°C and mixed evenly. The mixture is kept warm and epoxidized butyl rubber, thermoplastic polyurethane grafted with maleic anhydride and an optional antioxidant are added. After the mixture is evenly mixed, the mixture is discharged and cooled to room temperature to obtain a mixed product.

[0093] (3) At room temperature, the mixed product and the vulcanizing agent are mixed evenly using an open mill to obtain a rubber-plastic premix.

[0094] (4) The rubber-plastic premix is ​​placed in a twin-screw extruder and subjected to dynamic vulcanization at a temperature of 170° C. to 260° C. and a rotation speed of 300 to 800 rpm to obtain a thermoplastic vulcanizate.

[0095] The present invention first obtains a rubber-plastic premix by premixing. Then the rubber-plastic premix is ​​put into a high-temperature high-shear device for dynamic vulcanization reaction. The main reaction process of dynamic vulcanization is as follows: rubber and additives undergo cross-linking reaction under high temperature to form a three-dimensional network structure, and are sheared and broken into particles dispersed in the plastic phase under high shear. The dynamic vulcanization of the present invention is different from the common static vulcanization process, which only provides high temperature to cross-link the rubber phase.

[0096] The preparation method of the present invention has the following beneficial effects: 1. The thermoplastic polyurethane in the substrate is thermodynamically incompatible with the rubber. The preparation method of the present invention can significantly improve the degree of crushing and dispersion of the rubber phase in the thermoplastic vulcanizate, thereby improving the performance of the thermoplastic vulcanizate. 2. In the preparation method of the present invention, the reaction mechanism of the compatibilization reaction is clear. 3. The preparation method of the present invention can give maleic anhydride and epoxy functional groups sufficient reaction time, thereby improving the degree of reaction.

[0097] Example

[0098] The embodiments of the present invention will be described in detail below in conjunction with the examples, but those skilled in the art will appreciate that the following examples are only used to illustrate the present invention and should not be considered to limit the scope of the present invention. If no specific conditions are specified in the examples, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0099] In the examples and comparative examples, the thermoplastic polyurethane grafted with maleic anhydride was purchased from Shenzhen Huixin Plastic Chemical Co., Ltd. with a brand number of 6851. In terms of molar percentage, the grafting rate of maleic anhydride was 1.2%.

[0100] Thermoplastic polyester polyurethane elastomer was purchased from Zhejiang Huafeng Thermoplastic Polyurethane Co., Ltd.

[0101] Thermoplastic polyether polyurethane elastomer was purchased from BASF (China) Co., Ltd.

[0102] Modified nanocellulose was purchased from Jinan Shengquan Group Co., Ltd., brand: NFC-5L1.

[0103] Liquid butyl rubber was purchased from Shanghai Yuanxiang Industrial Co., Ltd.

[0104] Xylene was purchased from Beijing Tongguang Fine Chemical Company.

[0105] The hydrogen peroxide aqueous solution was purchased from Tianjin Oubok Chemical Co., Ltd., and the mass fraction of hydrogen peroxide was 30%.

[0106] The formic acid aqueous solution was purchased from Tianjin Oubok Chemical Co., Ltd., and the mass fraction of formic acid was 88%.

[0107] The modified biomass powder was purchased from Hebei Zhongpi Dongming Technology Co., Ltd., brand: AT-012.

[0108] Modified silica was purchased from Evonik Degussa (China) Co., Ltd., AEROSIL A200.

[0109] The preparation method of epoxidized butyl rubber comprises the following steps:

[0110] 1. Dissolve 200 g of liquid butyl rubber (weight average molecular weight 10,000 Da) in 800 g of xylene to prepare a xylene solution of liquid butyl rubber.

[0111] 2. Weigh 3.66 g of 30% aqueous hydrogen peroxide solution and 1.68 g of 88% aqueous formic acid solution, mix them, and slowly drip them into the xylene solution of the above liquid butyl rubber, and react at 40° C. for 5 hours.

[0112] 3. The epoxidized butyl rubber (EIIR) was obtained by removing the solvent by rotary evaporation using a rotary evaporator.

[0113] Examples 1-5

[0114] According to the formulations in Table 1 below, the thermoplastic vulcanizates of Examples 1-5 were prepared using the following preparation method.

[0115] (1) accurately weighing the rubber and the reinforcing filler, and mixing them uniformly in an internal mixer at 23° C. to obtain a rubber compound;

[0116] (2) Rubber and plastic premixing: the rubber compound and thermoplastic polyurethane are put into an internal mixer according to the temperature of the rubber and plastic premixing in Table 1 and mixed evenly, and the epoxidized butyl rubber, maleic anhydride grafted thermoplastic polyurethane and antioxidant are added while keeping the temperature. After the mixture is evenly mixed, the mixture is discharged and cooled to room temperature to obtain a mixed product;

[0117] (3) at room temperature, mixing the mixed product and the vulcanizing agent using an open mill to uniformly obtain a rubber-plastic premix;

[0118] (4) The rubber-plastic premix is ​​placed in a twin-screw extruder for dynamic vulcanization, wherein the vulcanization temperature and rotation speed are carried out according to the data in Table 1 to obtain a thermoplastic vulcanizate.

[0119] Comparative Example 1

[0120] According to the formulation in Table 1 below, the thermoplastic vulcanizate of Comparative Example 1 was prepared using the preparation methods of Examples 1-5.

[0121] Table 1

[0122]

[0123] Performance Testing

[0124] 1. Mechanical properties testing

[0125] The thermoplastic vulcanizate was pressed into a 2 mm thick sheet according to the standard, and then the tensile strength and elongation at break were measured according to the following standards GB / T528-2009 and GB / T528-2009, and the wear resistance, dry anti-slip coefficient and wet anti-slip coefficient were measured according to DIN53516, ASTM D1894 and ASTM D1894. The results are shown in Table 2.

[0126] 2. Appearance

[0127] The results were observed with the naked eye and are shown in Table 2.

[0128] Table 2

[0129]

[0130] As can be seen from Table 2, compared with Example 1, Comparative Example 1 does not add epoxidized butyl rubber and maleic anhydride grafted thermoplastic polyurethane. The results show that the combination of epoxidized butyl rubber and maleic anhydride grafted thermoplastic polyurethane can make the tensile strength and elongation at break of the thermoplastic vulcanizate more excellent, indicating that epoxidized butyl rubber and maleic anhydride grafted thermoplastic polyurethane can play a role in increasing the volume. In addition, the thermoplastic vulcanizate without adding a compatibilizer has a slightly rough appearance.

[0131] Both Example 4 and Example 5 have good mechanical properties, wear resistance and anti-slip properties. Compared with Example 4 without adding modified nanocellulose, Example 5 has slightly lower properties, indicating that the addition of modified nanocellulose has a certain effect on improving the properties of thermoplastic vulcanizate.

[0132] Compared with Example 3 and Example 4, the higher the content of brominated butyl rubber is, the higher the dry anti-slip coefficient and the wet anti-slip coefficient are, indicating that the anti-slip performance is improved.

[0133] It should be noted that, although the technical solution of the present invention is introduced with specific examples, those skilled in the art will appreciate that the present invention should not be limited thereto.

[0134] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or technical improvements in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A thermoplastic vulcanizate, characterized in that: It includes a base material and additives; the base material includes rubber and thermoplastic polyurethane, and the additives include a vulcanizer, a compatibilizer and a reinforcing filler; wherein, Based on 100% by weight of the substrate, the content of the vulcanizing agent is 3 to 10 parts, the content of the compatibilizer is 0.5 to 5 parts, and the content of the reinforcing filler is 0 to 20 parts; and, The compatibilizers include epoxidized butyl rubber and maleic anhydride grafted thermoplastic polyurethane.

2. The thermoplastic vulcanizate according to claim 1, characterized in that Based on 100% by weight of the substrate, the content of the rubber is 10 to 90 parts, and the content of the thermoplastic polyurethane is 10 to 90 parts; Preferably, the rubber includes one or a combination of two or more of butyl rubber, chlorinated butyl rubber and brominated butyl rubber; and / or, the thermoplastic polyurethane includes a thermoplastic polyether polyurethane elastomer and / or a thermoplastic polyester polyurethane elastomer.

3. The thermoplastic vulcanizate according to claim 1 or 2, characterized in that: The mass ratio of the epoxidized butyl rubber to the thermoplastic polyurethane grafted with maleic anhydride is 1:1 to 1:10; Preferably, the weight average molecular weight of the epoxidized butyl rubber is 5000-100000 Da; and / or, in terms of molar percentage, the grafting rate of maleic anhydride in the maleic anhydride-grafted thermoplastic polyurethane is 1-5%.

4. The thermoplastic vulcanizate according to any one of claims 1 to 3, characterized in that: The preparation method of the epoxidized butyl rubber comprises the following steps: The xylene solution of liquid butyl rubber is mixed with a mixed solution of hydrogen peroxide and formic acid, and subjected to epoxidation reaction to obtain the epoxidized butyl rubber; Preferably, the temperature of the epoxidation reaction is 30 to 50° C., and the time of the epoxidation reaction is 3 to 8 hours.

5. The thermoplastic vulcanizate according to claim 4, characterized in that In the xylene solution of the liquid butyl rubber, the mass fraction of the liquid butyl rubber is 10 to 30%; and / or, In the mixed solution of hydrogen peroxide and formic acid, the molar ratio of formic acid to hydrogen peroxide is (1-2):(1-2); preferably, the mixed solution of hydrogen peroxide and formic acid comprises a mixture of a hydrogen peroxide aqueous solution with a mass fraction of 20-40% and a formic acid aqueous solution with a mass fraction of 80-95%.

6. The thermoplastic vulcanizate according to any one of claims 1 to 5, characterized in that: The vulcanizing agent includes one or a combination of two or more of phenolic resin, stannous chloride, 2,5-dimethyl-2,5-bis(tert-butyl peroxide)-3-hexyne, zinc oxide, stearic acid, and zinc stearate.

7. The thermoplastic vulcanizate according to any one of claims 1 to 6, characterized in that: The reinforcing filler includes one or a combination of two or more of modified nanocellulose, modified white carbon black, carbon black, and modified biomass powder.

8. The thermoplastic vulcanizate according to any one of claims 1 to 7, characterized in that: The additive further includes an antioxidant; preferably, based on 100% by weight of the substrate, the content of the antioxidant is 0.1 to 3 parts; More preferably, the antioxidant is a hindered phenol antioxidant and / or a phosphite antioxidant.

9. A method for preparing a thermoplastic vulcanizate according to any one of claims 1 to 8, characterized in that: The method comprises the steps of mixing the components of the thermoplastic vulcanizate and then subjecting it to dynamic vulcanization treatment; preferably, the preparation method comprises the following steps: The rubber and the reinforcing filler are mixed in an internal mixer to obtain a mixed rubber; The mixed rubber and thermoplastic polyurethane are mixed in an internal mixer, kept warm, and a compatibilizer and an optional antioxidant are added and continued to mix to obtain a mixed product; The mixed product is mixed with a vulcanizing agent in an open mill to obtain a rubber-plastic premix; The rubber-plastic premix is ​​subjected to dynamic vulcanization treatment in a twin-screw extruder to obtain a thermoplastic vulcanizate.

10. The preparation method according to claim 9, characterized in that: The temperature of mixing the rubber compound and the thermoplastic polyurethane is 170-260° C.; and / or, The temperature of the dynamic vulcanization is 170° C. to 260° C., and the rotation speed of the dynamic vulcanization is 300 to 800 rpm.

Images