Thermoplastic vulcanizate and preparation method therefor

Abstract

The present invention provides a thermoplastic vulcanizate and a preparation method therefor. The thermoplastic vulcanizate comprises a matrix and additives; the matrix comprises rubber and thermoplastic polyurethane, and the additives include a vulcanizing agent, a compatibilizer, and a reinforcing filler; based on 100 parts by weight of the matrix, the content of the vulcanizing agent is 3-10 parts, the content of the compatibilizer is 0.5-5 parts, and the content of the reinforcing filler is 0-20 parts; and the compatibilizer comprises epoxidized butyl rubber and maleic anhydride-grafted thermoplastic polyurethane. The thermoplastic vulcanizate of the present invention exhibits excellent compatibility between rubber and thermoplastic polyurethane, and has a fine micro-phase structure. In addition, the thermoplastic vulcanizate has excellent mechanical properties, outstanding elasticity and slip resistance, and excellent wear resistance. The preparation method for the thermoplastic vulcanizate of the present invention is simple and easy to implement, features readily available raw materials, and is thus suitable for large-scale production.

Description

Thermoplastic vulcanizates and their preparation methods Technical Field

[0001] This invention relates to a thermoplastic vulcanizate and its preparation method, belonging to the field of polymer material processing. Background Technology

[0002] Thermoplastic vulcanizates are a type of thermoplastic elastomer prepared using dynamic vulcanization reaction blending technology. They are blends of incompatible or poorly compatible rubber and thermoplastic resin, which are selectively vulcanized in situ under high shear force and temperature 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] Thermoplastic vulcanizates have similar physical properties and elasticity to traditional rubber at room temperature. At high temperatures, they can be processed and molded as quickly and economically as thermoplastic plastics. They can also be recycled and reused after they are old and discarded, resulting in lower processing costs. They can replace thermosetting rubber, fundamentally solving the problem of traditional cross-linked rubber being difficult to recycle and reuse, and can also significantly improve the elasticity of plastic products.

[0004] To meet market demands, thermoplastic elastomers with various properties, functions, and applications can be developed by adjusting the thermoplastic vulcanizate system and its composition. The properties of thermoplastic elastomers primarily depend on the properties and microstructure of the base material. Furthermore, due to the thermodynamic incompatibility of the two-phase system, to make the mechanical and elastic properties of thermoplastic elastomers more closely resemble those of traditional rubber, it is necessary to develop appropriate compatibilizers for the system and to achieve dynamic vulcanization process control during preparation. This is a characteristic and challenge of current technology.

[0005] Butyl rubber, the world's fourth largest synthetic rubber, is a highly saturated rubber obtained through cationic copolymerization of isobutylene and a small amount of isoprene. It possesses excellent airtightness, shock absorption, heat resistance, aging resistance, and anti-slip properties. Thermoplastic polyurethane exhibits excellent low-temperature and impact strength, high durability, flexibility, good abrasion and scratch resistance, and is easy to process. Butyl rubber / thermoplastic polyurethane thermoplastic vulcanizates combine the superior properties of both butyl rubber and thermoplastic polyurethane, offering advantages such as softness, abrasion resistance, and aging resistance. Its elasticity, sealing, and anti-slip properties are particularly outstanding. The production process is simple, and it can be widely used in automotive sealing strips, medical rubber stoppers, shoe sole materials, and sporting goods, providing energy-saving and carbon-reducing solutions for the automotive, medical, and footwear manufacturing industries.

[0006] However, butyl rubber and thermoplastic polyurethane have poor compatibility. The rubber is not easily sheared and broken down to form uniform, tiny dispersed phase particles within the thermoplastic polyurethane matrix, ultimately resulting in a less refined microstructure of the formed thermoplastic vulcanizate, which in turn affects its mechanical and processing properties. In summary, solving the compatibility issue between the two substrates has always been a research challenge for thermoplastic vulcanizates prepared from butyl rubber and thermoplastic polyurethane.

[0007] Reference 1 discloses a thermoplastic vulcanizate composition and its preparation method for footwear materials. 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 crosslinking initiator, and an additive. With 100 parts by weight of the total rubber content, the free radical crosslinking initiator content is 0.02 to 5.0 parts by weight, and the additive content is 0.1 to 20 parts by weight. The plastic phase and rubber phase are uniformly mixed, and the weight ratio of the plastic phase to the rubber phase is 80:20 to 20:80. Analysis of the molecular structures of the two base materials (butyl rubber and polyurethane) reveals significant differences in their main chain molecular structures, inevitably leading to thermodynamic incompatibility.

[0008] Reference 1: CN115073912A Summary of the Invention

[0009] The problem the invention aims to solve

[0010] In view of the technical problems existing in the prior art, such as poor compatibility between rubber and thermoplastic polyurethane, rubber is not easy to be sheared and broken into uniform and tiny particles dispersed in the thermoplastic polyurethane matrix, which ultimately results in the microstructure of the formed thermoplastic vulcanizate not being fine enough, thus affecting its mechanical properties and processing properties, the present invention first provides a thermoplastic vulcanizate.

[0011] The thermoplastic vulcanizate of this invention exhibits excellent compatibility between the rubber and thermoplastic polyurethane, and possesses a fine microphase structure. Furthermore, the thermoplastic vulcanizate exhibits excellent mechanical properties, superior elasticity and anti-slip properties, and excellent wear resistance.

[0012] The present invention also provides a method for preparing thermoplastic vulcanizates, which is simple and easy to implement, uses readily available raw materials, and is suitable for mass production.

[0013] Solution for solving the problem

[0014] This invention provides a thermoplastic vulcanizate comprising a substrate and additives; the substrate comprises rubber and thermoplastic polyurethane, and the additives comprise a vulcanizing agent, a compatibilizer, and reinforcing fillers; wherein,

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

[0016] The compatibilizer comprises 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 comprises one or more of butyl rubber, chlorinated butyl rubber, and brominated butyl rubber; and / or, the thermoplastic polyurethane comprises thermoplastic polyether type polyurethane elastomer and / or thermoplastic polyester type polyurethane elastomer.

[0019] According to the thermoplastic vulcanizate of the present invention, the mass ratio of the epoxidized butyl rubber to the maleic anhydride-grafted thermoplastic polyurethane 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 molar percentage, the maleic anhydride grafting rate in the maleic anhydride-grafted thermoplastic polyurethane is 1-5%.

[0021] According to the thermoplastic vulcanizate of the present invention, the method for preparing the epoxidized butyl rubber includes the following steps:

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

[0023] Preferably, the epoxidation reaction is carried out at a temperature of 30–50°C for 3–8 hours.

[0024] According to the thermoplastic vulcanizate of the present invention, wherein the mass fraction of the liquid butyl rubber in the xylene solution is 10-30%; 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 is obtained by mixing an aqueous solution of hydrogen peroxide with a mass fraction of 20-40% with an aqueous solution of formic acid with a mass fraction of 80-95%.

[0026] According to the thermoplastic vulcanizate of the present invention, the vulcanizing agent comprises one or more of phenolic resin, stannous chloride, 2,5-dimethyl-2,5-bis(tert-butylperoxide)-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 more of modified nanocellulose, modified silica, carbon black, and modified biomass powder.

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

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

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

[0031] Rubber and reinforcing fillers are mixed in an internal mixer to obtain a compound;

[0032] The compound is mixed with thermoplastic polyurethane in a mixer and kept at a constant temperature. Compatibilizer and optional antioxidant are added and the mixture is continued to be mixed to obtain a mixed product.

[0033] The mixture is mixed with a vulcanizing agent in a two-roll 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 at which the compound is mixed with the thermoplastic polyurethane is 170–260°C; and / or,

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

[0037] The effects of the invention

[0038] The thermoplastic vulcanizate of this invention exhibits excellent compatibility between the rubber and thermoplastic polyurethane, and possesses a fine microphase structure. Furthermore, the thermoplastic vulcanizate exhibits excellent mechanical properties, superior elasticity and anti-slip properties, and excellent wear resistance.

[0039] The method for preparing the thermoplastic vulcanizate of the present invention is simple and easy to implement, the raw materials are readily available, and it is suitable for mass production. Detailed Implementation

[0040] Various exemplary embodiments, features, and aspects of the present invention will be described in detail below. The term "exemplary" as used herein means "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as superior to or better than other embodiments.

[0041] Furthermore, to better illustrate the present invention, numerous specific details are set forth in the following detailed embodiments. Those skilled in the art should understand that the present invention can be practiced without certain specific details. In other instances, methods, means, apparatus, and steps well known to those skilled in the art have not been described in detail in order to highlight the spirit of the present invention.

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

[0043] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0044] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "implementation," etc., refer to specific elements (e.g., features, structures, properties, and / or characteristics) related to that embodiment, which are included in at least one of the embodiments described herein and may or may not be present in other embodiments. Furthermore, it should be understood that these elements may be combined in any suitable manner in various embodiments.

[0045] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0046] In this instruction manual, if "normal temperature" or "room temperature" is used, it means 15-30℃.

[0047] <First Aspect>

[0048] A first aspect of the present invention provides a thermoplastic vulcanizate comprising a substrate and additives; the substrate comprising rubber and thermoplastic polyurethane, and the additives comprising a vulcanizing agent, a compatibilizer, and a reinforcing filler; wherein...

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

[0050] The compatibilizer comprises epoxidized butyl rubber and maleic anhydride-grafted thermoplastic polyurethane.

[0051] The base rubber in the thermoplastic vulcanizate of the present 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 this invention, the substrate comprises rubber and thermoplastic polyurethane.

[0054] The thermoplastic vulcanizate of the present invention disperses cross-linked rubber phase (rubber) particles in a plastic phase (thermoplastic polyurethane). The rubber phase provides high elasticity, while the plastic phase provides high-temperature repeatability; the combination of these two properties achieves the thermoplastic vulcanizate's high elasticity at room temperature and high-temperature repeatability.

[0055] In some specific embodiments, based on 100% by weight of the substrate, the rubber content is 10-90 parts, for example: 15 parts, 25 parts, 35 parts, 45 parts, 55 parts, 65 parts, 75 parts, 85 parts, etc.; the thermoplastic polyurethane content is 10-90 parts, for example: 15 parts, 25 parts, 35 parts, 45 parts, 55 parts, 65 parts, 75 parts, 85 parts, etc. In this invention, if the rubber content is too low, the thermoplastic polyurethane content will be too high, making it impossible to achieve its high elasticity at room temperature; if the rubber content is too high, the thermoplastic polyurethane phase content will be too low, making it difficult to successfully prepare a material that can be repeatedly processed at high temperatures.

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

[0057] Compatibilizer

[0058] The inventors of this invention have discovered that by using the compatibilizer of this invention, the compatibility between the rubber of the substrate and the thermoplastic polyurethane can be effectively improved. Furthermore, by combining dynamic vulcanization technology, a thermoplastic vulcanizate with a fine microphase structure, excellent mechanical properties, superior elasticity and anti-slip properties, and excellent wear resistance can be prepared.

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

[0060] In some specific embodiments, the preparation method of the epoxidized butyl rubber includes the following steps: mixing a xylene solution of liquid butyl rubber with a mixed solution of hydrogen peroxide and formic acid, and then performing an epoxidation reaction to obtain the epoxidized butyl rubber.

[0061] Specifically, in this invention, the mass fraction of liquid butyl rubber in the xylene solution of 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 act as a catalyst to promote the reaction of hydrogen peroxide with the double bond of butyl rubber to generate epoxy functional groups, which enables the reaction to proceed successfully. Furthermore, the epoxy functional groups are used to react with maleic anhydride-grafted thermoplastic polyurethane to generate butyl rubber-grafted thermoplastic polyurethane. Its use as a compatibilizer can promote the interfacial compatibility between the substrate butyl rubber and thermoplastic polyurethane, thereby improving the 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 it can promote the reaction between hydrogen peroxide and butyl rubber better.

[0064] Furthermore, in this invention, the mixed solution of hydrogen peroxide and formic acid is obtained by mixing an aqueous solution of hydrogen peroxide with a mass fraction of 20-40% with an aqueous solution of formic acid with a mass fraction of 80-95%. Of course, the mixed solution of hydrogen peroxide and formic acid can also be prepared by other methods, and this invention does not impose specific limitations on this.

[0065] In some specific embodiments, the maleic anhydride grafting rate in the maleic anhydride-grafted thermoplastic polyurethane is 1-5% by molar 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 maleic anhydride grafting rate is 1-5%, the reaction efficiency with the epoxy groups on the epoxide 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 this invention, after the epoxidation reaction, a solvent removal step is included, which is preferably achieved by using a rotary evaporator to remove the solvent through rotary evaporation.

[0068] In this invention, maleic anhydride-grafted thermoplastic polyurethane and epoxidized butyl rubber react to form ester compounds. The inventors of this invention have discovered that one end of these ester compounds is similar in molecular chain structure to the rubber in the substrate, while the other end is physically compatible with the thermoplastic polyurethane, thereby improving the compatibility between the rubber in the substrate and the thermoplastic polyurethane.

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

[0070] In this invention, the compatibilizer content is 0.5 to 5 parts per 100% of the substrate, for example: 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, etc. The compatibilizing effect is better when the compatibilizer content is 0.5 to 5 parts. In this invention, if the compatibilizer content is less than 0.5 parts, it will not have a compatibilizing effect and will not promote the interfacial interaction between the rubber and thermoplastic polyurethane in the substrate; if the compatibilizer content exceeds 5 parts, the low molecular weight compatibilizer will reduce the mechanical properties of the material and also increase the cost.

[0071] vulcanizing agent

[0072] In this invention, the vulcanizing agent promotes the chemical reaction between the molecular chains of the rubber phase, forming a three-dimensional cross-linked structure during the shearing and crushing process, thereby achieving phase inversion to prepare thermoplastic vulcanizates.

[0073] In this invention, the content of the vulcanizing agent is 0.5 to 3 parts per 100% of the base material, 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 this invention, if the content of the vulcanizing agent is too low, the degree of crosslinking is insufficient; if the content of the vulcanizing agent is too high, the degree of crosslinking is too high, and the crosslinking speed is too fast to achieve the reverse inversion.

[0074] Specifically, in this invention, the vulcanizing agent includes one or more of the following: phenolic resin, stannous chloride, 2,5-dimethyl-2,5-bis(tert-butylperoxide)-3-hexyne, zinc oxide, stearic acid, and zinc stearate.

[0075] Reinforcing filler

[0076] This invention increases the rigidity, strength, and abrasion resistance of thermoplastic vulcanizates by enabling reinforcing fillers to interact with the rubber in the substrate, while also improving the processing performance and service life of the rubber in the substrate.

[0077] In some specific implementations, the content of the reinforcing filler is 0 to 20 parts by weight of the substrate, 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, it will form agglomerates in the substrate and cannot be uniformly dispersed, resulting in a decrease in the performance of the thermoplastic vulcanizate.

[0078] Specifically, in this invention, the reinforcing filler includes one or more of the following: modified nanocellulose, modified silica, carbon black, and modified biomass powder.

[0079] Other additives

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

[0081] The antioxidants include hindered phenolic antioxidants and / or phosphite antioxidants; specifically, the antioxidants include one or more of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (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] A second aspect of the present invention provides a method for preparing a thermoplastic vulcanizate according to the first aspect of the present invention, comprising the step of mixing the components of the thermoplastic vulcanizate and then performing a dynamic vulcanization treatment; preferably, the preparation method comprises the following steps:

[0084] Rubber and reinforcing fillers are mixed in an internal mixer to obtain a compound;

[0085] The compound is mixed with thermoplastic polyurethane in a mixer and kept at a constant temperature. Compatibilizer and optional antioxidant are added and the mixture is continued to be mixed to obtain a mixed product.

[0086] The mixture is mixed with a vulcanizing agent in a two-roll 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 mixing temperature of 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 this invention, during the rubber-plastic premixing process, directly mixing the compatibilizer with the rubber compound at a temperature of 170–260°C can perform a high-temperature reaction compatibilization, thereby obtaining the rubber-plastic premix.

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

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

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

[0092] (2) Rubber-plastic premix: The compound rubber and thermoplastic polyurethane are put into a mixer at 170℃~260℃ and mixed evenly. The mixture is kept warm and epoxidized butyl rubber, maleic anhydride-grafted thermoplastic polyurethane and optional antioxidants are added. After the mixture is evenly mixed, it is discharged and cooled to room temperature to obtain the mixed product.

[0093] (3) At room temperature, the mixture 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 dynamically vulcanized at a temperature of 170℃~260℃ and a speed of 300~800rpm to obtain thermoplastic vulcanizate.

[0095] This invention first obtains a rubber-plastic premix through premixing. Then, the rubber-plastic premix is ​​fed into a high-temperature, high-shear apparatus for dynamic vulcanization. The main reaction process of dynamic vulcanization involves the rubber and additives undergoing a cross-linking reaction under high temperature to form a three-dimensional network structure, while simultaneously being sheared and broken into particles dispersed in the plastic phase under high shear. The dynamic vulcanization of this invention differs from the common static vulcanization process, which only provides high temperature to cause cross-linking of the rubber phase.

[0096] The preparation method of this invention has the following beneficial effects: 1. The thermoplastic polyurethane and rubber in the substrate are thermodynamically incompatible. The preparation method of this invention significantly improves the degree of fragmentation and dispersion of the rubber phase in the thermoplastic vulcanizate, thereby improving the performance of the thermoplastic vulcanizate. 2. In the preparation method of this invention, the reaction mechanism of the compatibilizing reaction is clear. 3. The preparation method of this invention allows maleic anhydride and epoxy functional groups sufficient reaction time, thereby increasing the degree of reaction.

[0097] Example

[0098] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0099] In the examples and comparative examples, the maleic anhydride-grafted thermoplastic polyurethane was purchased from Shenzhen Huixin Plastics & Chemical Co., Ltd., with the grade 6851; the grafting rate of maleic anhydride was 1.2% by molar percentage.

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

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

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

[0103] The 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 Oubokai Chemical Co., Ltd., and the hydrogen peroxide mass fraction was 30%.

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

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

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

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

[0110] 1. Dissolve 200g of liquid butyl rubber (weight average molecular weight 10000Da) in 800g of xylene to prepare a xylene solution of liquid butyl rubber.

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

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

[0113] Examples 1-5

[0114] The thermoplastic vulcanizates of Examples 1-5 were prepared according to the formulations in Table 1 below and the preparation methods described below.

[0115] (1) Accurately weigh the rubber and reinforcing filler, and mix them evenly in a mixer at 23°C to obtain the compound;

[0116] (2) Rubber-plastic premix: The compound rubber and thermoplastic polyurethane are put into the internal mixer at the temperature of rubber-plastic premix in Table 1 and mixed evenly. The mixture is kept warm and epoxidized butyl rubber, maleic anhydride grafted thermoplastic polyurethane and antioxidant are added. After the mixture is evenly mixed, the mixture is discharged and cooled to room temperature to obtain the mixed product.

[0117] (3) At room temperature, the mixture and the vulcanizing agent are mixed evenly using an open mill to 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 speed are as shown in Table 1, to obtain thermoplastic vulcanizate.

[0119] Comparative Example 1

[0120] The thermoplastic vulcanizate of Comparative Example 1 was prepared according to the formulation in Table 1 below and the preparation methods of Examples 1-5.

[0121] Table 1

[0122] Performance testing

[0123] 1. Mechanical property testing

[0124] The thermoplastic vulcanizate was pressed into 2mm thick sheets according to the standard. Then, the tensile strength and elongation at break were determined according to the following standards GB / T528-2009 and GB / T528-2009, respectively. The abrasion resistance, dry anti-slip coefficient and wet anti-slip coefficient were determined according to DIN53516, ASTM D1894 and ASTM D1894. The results are shown in Table 2.

[0125] 2. Appearance

[0126] The results were observed with the naked eye and are shown in Table 2.

[0127] Table 2

[0128] Table 2 shows that Comparative Example 1, compared to Example 1, did not include epoxidized butyl rubber and maleic anhydride-grafted thermoplastic polyurethane. The results indicate that the combination of epoxidized butyl rubber and maleic anhydride-grafted thermoplastic polyurethane significantly improves the tensile strength and elongation at break of the thermoplastic vulcanizate, demonstrating that the epoxidized butyl rubber and maleic anhydride-grafted thermoplastic polyurethane act as compatibilizers. Additionally, the thermoplastic vulcanizate without compatibilizers has a slightly rougher appearance.

[0129] Both Examples 4 and 5 exhibit good mechanical properties, wear resistance, and anti-slip properties. Compared to Example 4 without the addition of modified nanocellulose, the properties of Example 5 are slightly lower, indicating that the addition of modified nanocellulose has a certain effect on improving the performance of thermoplastic vulcanizates.

[0130] Compared with Example 4, the higher the content of brominated butyl rubber, the higher the dry anti-slip coefficient and wet anti-slip coefficient, indicating that the anti-slip performance is better.

[0131] It should be noted that although the technical solution of the present invention has been described with specific examples, those skilled in the art will understand that the present invention should not be limited thereto.

[0132] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A thermoplastic vulcanizate, characterized in that, It includes a substrate and additives; the substrate includes rubber and thermoplastic polyurethane, and the additives include vulcanizing agents, compatibilizers, and reinforcing fillers; wherein, Based on 100% by weight of the substrate, the content of the vulcanizing agent is 3-10 parts, the content of the compatibilizer is 0.5-5 parts, and the content of the reinforcing filler is 0-20 parts; and, The compatibilizer comprises 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 comprises one or more of butyl rubber, chlorinated butyl rubber, and brominated butyl rubber; and / or, the thermoplastic polyurethane comprises thermoplastic polyether type polyurethane elastomer and / or thermoplastic polyester type 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 maleic anhydride-grafted thermoplastic polyurethane is 1:1 to 1:

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

4. The thermoplastic vulcanizate according to any one of claims 1-3, characterized in that, The preparation method of the epoxidized butyl rubber includes the following steps: A xylene solution of liquid butyl rubber is mixed with a mixed solution of hydrogen peroxide and formic acid, and then subjected to an epoxidation reaction to obtain the epoxidized butyl rubber. Preferably, the epoxidation reaction is carried out at a temperature of 30–50°C for 3–8 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 10-30%; 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 is obtained by mixing an aqueous solution of hydrogen peroxide with a mass fraction of 20-40% with an aqueous solution of formic acid with a mass fraction of 80-95%.

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

7. The thermoplastic vulcanizate according to any one of claims 1-6, characterized in that, The reinforcing filler includes one or more of the following: modified nanocellulose, modified silica, carbon black, and modified biomass powder.

8. The thermoplastic vulcanizate according to any one of claims 1-7, characterized in that, The additive also includes an antioxidant; preferably, the antioxidant content is 0.1 to 3 parts per 100% of the base material. More preferably, the antioxidant is a hindered phenolic antioxidant and / or a phosphite antioxidant.

9. A method for preparing a thermoplastic vulcanizate according to any one of claims 1-8, characterized in that, The method includes the step of mixing the components of the thermoplastic vulcanizate and then performing dynamic vulcanization treatment; preferably, the preparation method includes the following steps: Rubber and reinforcing fillers are mixed in an internal mixer to obtain a compound; The compound is mixed with thermoplastic polyurethane in a mixer and kept at a constant temperature. Compatibilizer and optional antioxidant are added and the mixture is continued to be mixed to obtain a mixed product. The mixture is mixed with a vulcanizing agent in a two-roll 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 mixing temperature of the compound and the thermoplastic polyurethane is 170–260°C; and / or, The temperature of the dynamic vulcanization is 170℃~260℃, and the rotation speed of the dynamic vulcanization is 300~800rpm.

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