Ethylene-butadiene rubber / polypropylene thermoplastic vulcanizate and preparation method of thermoplastic vulcanizate

Abstract

The invention relates to the technical field of high polymer materials, in particular to ethylene-butadiene rubber / polypropylene thermoplastic vulcanized rubber and a preparation method of the thermoplastic vulcanized rubber. According to the invention, the ethylene-butadiene rubber and the polypropylene are used, a compatibilizer does not need to be additionally added to improve the compatibility of the ethylene-butadiene rubber and the polypropylene, and then the thermoplastic vulcanized rubber with a fine microscopic phase structure, excellent physical and mechanical properties and low-temperature-resistant elasticity is prepared through rubber and plastic premixing and dynamic vulcanization. According to the invention, a vulcanization mode of silane grafting and water-adding cross-linking is adopted, and a one-step preparation process is adopted, so that silane grafting and silane dynamic vulcanization are carried out in the same process; compared with peroxide vulcanization, the prepared TPV product is better in tensile strength, elongation at break and normal-temperature and low-temperature compression permanent deformation performance. The problem that traditional EPDM / PP TPV is weak in low-temperature elasticity is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials. Further, it relates to an ethylene-butene rubber / polypropylene thermoplastic vulcanizate and a preparation method thereof. Background Art

[0002] Thermoplastic vulcanized rubber (abbreviation: TPV) is a kind of blend-type thermoplastic elastomer. It is a new type of elastomer material prepared by the phase inversion of a large amount of rubber and a small amount of plastic through a dynamic vulcanization reaction blending technology, and finally forms a "sea-island" structure with a small amount of plastic phase as the continuous phase and a large number of cross-linked rubber particles as the dispersed phase. The characteristics that the TPV material can simultaneously meet the processing performance of plastics and the elasticity of rubber fundamentally solve the problems of traditional rubber materials such as non-repeatable processing, high pollution, and high energy consumption. It has great application potential in the fields of automotive industry, aerospace, electronic appliances, construction, medical treatment, etc., and has become a new generation of low-carbon green and environment-friendly elastomer materials.

[0003] Research shows that for the existing EPDM / PP type TPV sealing strips, at low temperatures, their elasticity decreases with the decrease of temperature, the hardness increases greatly, and the elastic attenuation is large. When the temperature reaches -20°C, the compression set reaches 83%. That is, when the temperature is low in winter, the sealing strips become very hard, greatly reducing the service performance. Therefore, it is necessary to develop a special TPV material with better low-temperature resistance and elastic properties than traditional EPDM / PP TPV, and does not affect the performance of other comprehensive properties, which is suitable for use in low-temperature harsh weather conditions. Summary of the Invention

[0004] Aiming at the technical problem of the existing EPDM / PP type TPV that "at low temperatures, its elasticity decreases greatly with the decrease of temperature" - poor low-temperature resistance, the present invention provides a matrix material for TPV, ethylene-butene rubber and polypropylene, which can make the TPV have excellent low-temperature resistance, and provides a one-step silane dynamic cross-linking technology with a simpler processing process, and prepares an ethylene-butene rubber / polypropylene special thermoplastic vulcanizate with a fine microscopic phase structure, excellent physical and mechanical properties, excellent low-temperature resistance and elasticity.

[0005] One object of the present invention is to provide an ethylene-butene rubber / polypropylene thermoplastic vulcanizate.

[0006] The ethylene-butene rubber / polypropylene thermoplastic vulcanizate is prepared from raw materials containing the following components; the components and their parts by weight are as follows:

[0007]

[0008] Among them, the total amount of ethylene-butene rubber and polypropylene is 100 parts by weight.

[0009] The present invention uses ethylene-butene rubber and polypropylene as matrix materials. The ethylene-butene rubber and polypropylene have good compatibility, and there is no need to additionally add a compatibilizer to improve the compatibility problem between the two.

[0010] The ethylene-butene rubber: is a terpolymer synthesized by a metallocene catalyst using ethylene, butene and ENB as raw materials, abbreviated as EBT. Among them, ENB is used as the third monomer. The Mooney viscosity of the ethylene-butene rubber affects the processing performance and mechanical properties of the prepared thermoplastic vulcanizate. The higher the content of the third monomer in the ethylene-butene rubber, the more positions available for grafting reaction. Specifically, the Mooney viscosity ML(1+4)125°C of the ethylene-butene rubber is 30 or 50; the mass content of the third monomer ENB in the ethylene-butene rubber is 5%-10%. For example, one of K9330M and K3870EM can be selected, and an oil-filled grade can also be selected according to requirements.

[0011] The polypropylene is selected from at least one of ethylene-propylene block copolymerized polypropylene (PP-B), ethylene-propylene random copolymerized polypropylene (PP-R) and ethylene-propylene isotactic copolymerized polypropylene (PP-H). The molecular weight of polypropylene affects the cold resistance, processability and mechanical properties of the prepared thermoplastic vulcanizate. When the molecular weight of polypropylene is low, the processing performance and cold resistance are better; when the molecular weight of polypropylene is high, the mechanical properties are better. In specific implementation, it can be selected according to product requirements.

[0012] The silane coupling agent can be selected from at least one of vinyltriethoxysilane and vinyltrimethoxysilane. Among them, the steric hindrance of vinyltrimethoxysilane is lower than that of vinyltriethoxysilane, and it has higher grafting activity, but it is prone to pre-crosslinking with moisture in the air. In order to improve efficiency and avoid excessive pre-crosslinking reaction, vinyltriethoxysilane is preferably selected.

[0013] The peroxide initiator can be selected from at least one of dicumyl peroxide (DCP), 2,5-dimethyl-2,5-di-tert-butylperoxyhexane and benzoyl peroxide (BPO). According to the embodiments disclosed in the present invention, compared with using other peroxide initiators, using a compound system of dicumyl peroxide (DCP) and benzoyl peroxide (BPO) as the initiator, the properties of the prepared thermoplastic vulcanizate are better, manifested in that the tensile strength and elongation at break are significantly increased, and the compression set at -20°C is significantly reduced. Specifically, the mass ratio of dicumyl peroxide (DCP) to benzoyl peroxide (BPO) can be 1±0.1:1.

[0014] The change in the weight ratio of the silane coupling agent to the peroxide initiator will affect the properties of the prepared thermoplastic vulcanizate. According to the embodiments disclosed in the present invention, the weight ratio of the silane coupling agent to the peroxide initiator can be 5-25:1, preferably 10-20:1.

[0015] The antioxidant is selected from at least one of phenolic antioxidants. Phenolic antioxidants have the characteristics of good antioxidant effect, high thermal stability, no pollution to plastics, no coloring, and good compatibility with plastics. Using it can effectively prevent the degradation and aging of plastics and improve the mechanical properties of products. For example, it can be selected from at least one of antioxidant 1010, antioxidant 126, and antioxidant 1035.

[0016] The crosslinking catalyst is a catalyst that has a catalytic effect on the hydrolysis and condensation reaction of alkoxy groups; preferably, the crosslinking catalyst is selected from at least one of organotin and organoantimony catalysts; more preferably, the crosslinking catalyst is dibutyltin dilaurate (DBTL).

[0017] The present invention can also add various commonly used fillers and additives in the art according to processing needs, such as titanium dioxide, paraffin oil, etc. Their dosages are conventional dosages, and those skilled in the art can choose to add them according to the actual situation.

[0018] The second object of the present invention is to provide a method for preparing a thermoplastic vulcanizate.

[0019] The method for preparing the thermoplastic vulcanizate includes the following steps;

[0020] (1) Rubber-plastic premixing: Rubber, plastic, and antioxidant are mixed evenly to obtain a rubber-plastic premix.

[0021] (2) Silane grafting: A silane coupling agent, a peroxide initiator, and a crosslinking catalyst are added to the rubber-plastic premix, and stirred until the rubber phase fully undergoes a grafting reaction to obtain a silane grafting system.

[0022] (3) Silane crosslinking: Water is added to the silane grafting system, and stirred until the rubber is fully crosslinked to obtain a thermoplastic vulcanizate.

[0023] In step (1), the microstructure of the rubber-plastic premix is that the rubber phase is the continuous phase and the plastic phase is the dispersed phase. If the premixing step is skipped and all the materials are added at once and the temperature is raised to 170-200 °C, the plastic and rubber will start to melt but will not be completely melted immediately. At this time, because the rubber and plastic are not mixed evenly, the position where the silane coupling agent grafts will occur randomly on the plastic or rubber, and it cannot be ensured that the grafting reaction mainly occurs in the rubber phase. The grafting of the rubber phase is insufficient, and the subsequent crosslinking is also insufficient. It may not be possible to achieve a phase inversion, making the crosslinked rubber the dispersed phase and the plastic the continuous phase, and thus it is impossible to prepare a thermoplastic vulcanizate.

[0024] In step (1), the addition of an antioxidant has a protective effect on the plastic, prevents the plastic from thermal degradation at high temperatures, and stabilizes the properties of the plastic, thereby making the prepared thermoplastic vulcanizate have better tensile strength, elongation at break, and impact strength.

[0025] In step (2), the rubber undergoes a grafting reaction. After the rubber is fully grafted, the rubber phase aggregates to form a continuous phase of rubber and plastic. At the same time, the coupling agent acts on the plastic, reducing the interfacial energy between the rubber and plastic, making the rubber easier to graft and crosslink. After the rubber and plastic are premixed, there is no water in the internal mixer at high temperature. Adding the catalyst in this step can save steps and improve production efficiency. In addition, mixing the catalyst with the silane coupling agent and peroxide and adding them together also facilitates the third step of quickly adding water to directly perform dynamic crosslinking.

[0026] In step (2), if the grafting reaction time is too long, the probability of thermal degradation of the plastic phase increases, which is detrimental to performance. If the grafting reaction time is too short, the grafting is insufficient, and subsequent crosslinking is even less sufficient, resulting in poor performance. Therefore, "sufficient grafting of the rubber phase" is sufficient. "Sufficient grafting of the rubber phase" can be determined based on the final product performance and infrared characteristic peak characterization. This determination method is a conventional technical means in the art.

[0027] In step (2), the silane coupling agent, peroxide initiator, and cross-linking catalyst may be mixed in advance to form a silane mother liquor, and the silane mother liquor is added to an internal mixer.

[0028] In step (3), the rubber crosslinking occurs under the action of water and a catalyst. Water acts as a crosslinking agent. Compared to other crosslinking agents, using water as a crosslinking agent does not degrade polypropylene and reduces the use of chemicals.

[0029] In step (3), if the crosslinking time is too long, there is a risk of thermal degradation of the plastic; if the crosslinking time is too short, the crosslinking is insufficient. Therefore, "fully crosslinked rubber" is sufficient. "Fully crosslinked rubber" means that more than 90% of the rubber is crosslinked. Whether more than 90% of the rubber is crosslinked can be determined by testing the gel content of the product. This determination method is conventional in the art.

[0030] In step (3), the phases are reversed under stirring. Initially, the rubber phase is more continuous. After crushing, the plastic phase becomes a continuous phase, and the rubber particles are dispersed in the continuous plastic phase, showing a phase reversal between the rubber and plastic phases, giving the product thermoplastic properties that can be repeatedly processed.

[0031] The preparation method can adopt any existing internal mixer used for preparing thermoplastic vulcanizate.

[0032] The rubber used in the preparation method can be selected from rubbers having double bonds on the main chain or the third monomer that can be grafted and crosslinked. Specifically, ethylene-butene rubber can be selected.

[0033] The temperature of rubber-plastic premixing, the temperature of silane grafting, the temperature of silane crosslinking, the stirring speed of silane grafting, and the rotation speed of silane crosslinking are all determined according to the types of raw materials selected.

[0034] In the case where the rubber is selected from ethylene-butene rubber and the plastic is selected from polypropylene:

[0035] The temperature of rubber-plastic premixing can be 170 - 190 °C, preferably 170 °C - 200 °C;

[0036] The temperature of silane grafting is 170 °C - 200 °C, preferably 175 °C - 190 °C;

[0037] The stirring speed of silane grafting is 30 - 80 rpm;

[0038] The temperature of silane crosslinking is 170 °C - 200 °C, preferably 180 °C - 200 °C;

[0039] The rotation speed of silane crosslinking is 80 - 120 rpm.

[0040] One specific scheme of a preparation method of thermoplastic vulcanizate is as follows:

[0041] The raw materials adopt the following components in parts by weight:

[0042] 30 - 90 parts by weight of ethylene-butene rubber, preferably 55 - 70 parts by weight; 70 - 10 parts by weight of polypropylene, preferably 45 - 30 parts by weight; 0.05 - 0.3 parts by weight of antioxidant, preferably 0.05 - 0.1 parts by weight; 1 - 10 parts by weight of silane coupling agent, preferably 2 - 5 parts by weight; 0.01 - 0.5 parts by weight of peroxide initiator, preferably 0.1 - 0.4 parts by weight; 0.05 - 0.5 parts by weight of crosslinking catalyst, preferably 0.1 - 0.2 parts by weight; 1 - 15 parts by weight of water, preferably 5 - 10 parts by weight; wherein, the total amount of ethylene-butene rubber and polypropylene is 100 parts by weight;

[0043] It includes the following steps:

[0044] (1) Rubber-plastic premixing: Ethylene-butene rubber, polypropylene, and antioxidant are kneaded evenly in a mixer at 170 °C - 200 °C;

[0045] (2) Silane grafting: After step (1) is completed, add silane coupling agent, peroxide initiator, and crosslinking catalyst to the mixer, and carry out grafting reaction at 170 °C - 200 °C for 5 - 10 min; preferably, the grafting reaction temperature is 175 °C - 190 °C, and the rotation speed of the mixer is 30 - 80 rpm;

[0046] (3) Silane crosslinking: After step (2) is completed, water is added to the internal mixer, and crosslinking reaction is carried out at 170°C - 200°C for 4 - 8 min to produce ethylene-butylene rubber / polypropylene thermoplastic vulcanizate; preferably, the crosslinking reaction temperature is 180°C - 200°C, and the rotational speed of the internal mixer is 80 - 120 rpm.

[0047] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0048] One of the advantages of the present invention is that ethylene-butylene rubber and polypropylene are used as the rubber-plastic system. The compatibility between ethylene-butylene rubber and polypropylene is good, and there is no need to additionally add compatibilizers to improve their compatibility problem. Then, through rubber-plastic premixing and dynamic vulcanization, a thermoplastic vulcanizate with a fine microscopic phase structure, excellent physical and mechanical properties, and low-temperature elasticity is prepared.

[0049] Another advantage of the present invention is that a vulcanization method of silane grafting and crosslinking with water is adopted, and a one-step preparation process is used. The silane grafting and silane dynamic vulcanization are placed in the same process, which greatly improves the production efficiency. And using silane crosslinking greatly reduces the use of chemical drugs. Compared with the traditional peroxide vulcanization method, it not only reduces the use of vulcanizing agents and is more environmentally friendly, but also avoids the degradation of polypropylene by a large amount of peroxide vulcanizing agents. The prepared TPV products have better tensile strength, elongation at break, and compression set performance at normal and low temperatures compared with peroxide vulcanization, and the microscopic phase is also finer. Description of the Drawings

[0050] Figure 1 Atomic force logarithm modulus diagram of the thermoplastic vulcanizate prepared in Example 2; in the figure, the dark phase (dark part) is the low-modulus rubber phase, and the bright phase (light part) is the high-modulus plastic phase;

[0051] Figure 2 Atomic force logarithm modulus diagram of the thermoplastic vulcanizate prepared in Example 7; in the figure, the dark phase (dark part) is the low-modulus rubber phase, and the bright phase (light part) is the high-modulus plastic phase. Detailed Embodiments

[0052] The present invention will be specifically described below in conjunction with the drawings and specific embodiments. It is necessary to point out here that the following embodiments are only for further illustration of the present invention and cannot be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention still fall within the protection scope of the present invention.

[0053] In the following examples and comparative examples, the reagents used are all conventional commercially available products.

[0054] Example 1

[0055] The selected raw materials and their parts by weight are as follows:

[0056]

[0057] According to the above formula, first conduct rubber-plastic premixing. Melt polypropylene and antioxidant in a mixer at 170 °C and 100 rpm for 4 min until torque balance. Then add ethylene-butylene rubber into the mixer for blending for 3 min until torque balance. After continuing to blend for 2 min, pour the previously prepared silane mother liquor (vinyltriethoxysilane, dicumyl peroxide, dibutyltin dilaurate mixed evenly in proportion) into the mixer, maintain the temperature at 190 °C and the rotation speed at 40 rpm for silane grafting for 6 min. Finally, quickly add water into the mixer, maintain the rotation speed at 100 rpm to complete dynamic vulcanization for 5 min, and obtain a low-temperature resistant and highly elastic thermoplastic vulcanizate.

[0058] The obtained thermoplastic vulcanizate is pressed into a 2-mm-thick sheet according to the standard and its properties are tested. The properties are shown in Table 1. The atomic force logarithmic modulus diagram of the obtained thermoplastic vulcanizate is Figure 1 similar.

[0059] Example 2

[0060] The selected raw materials and their parts by weight are as follows:

[0061]

[0062]

[0063] According to the above formula, first conduct rubber-plastic premixing. Melt polypropylene and antioxidant in a mixer at 170 °C and 100 rpm for 4 min until torque balance. Then add ethylene-butylene rubber into the mixer for blending for 3 min until torque balance. After continuing to blend for 2 min, pour the previously prepared silane mother liquor (vinyltriethoxysilane, dicumyl peroxide, dibutyltin dilaurate mixed evenly in proportion) into the mixer, maintain the temperature at 190 °C and the rotation speed at 40 rpm for silane grafting for 6 min. Finally, quickly add water into the mixer, maintain the rotation speed at 100 rpm to complete dynamic vulcanization for 5 min, and obtain a low-temperature resistant and highly elastic thermoplastic vulcanizate.

[0064] The obtained thermoplastic vulcanizate is pressed into a 2-mm-thick sheet according to the standard and its properties are tested. The properties are shown in Table 1. The atomic force logarithmic modulus diagram of the obtained thermoplastic vulcanizate is as Figure 1 shown (the dark phase is the low-modulus rubber phase, and the bright phase is the high-modulus plastic phase).

[0065] Example 3

[0066] The selected raw materials and their parts by weight are as follows:

[0067]

[0068] According to the above formula, first conduct rubber-plastic premixing. Melt polypropylene and antioxidant in a mixer at 170 °C and 100 rpm for 4 min until torque balance. Then add ethylene-butylene rubber into the mixer for blending for 3 min until torque balance. After continuing to blend for 2 min, pour the pre-prepared silane mother liquor (vinyltriethoxysilane, dicumyl peroxide, dibutyltin dilaurate mixed evenly in proportion) into the mixer, maintain the temperature at 190 °C and the rotation speed at 40 rpm for silane grafting for 6 min. Finally, quickly add water into the mixer, maintain the rotation speed at 100 rpm to complete dynamic vulcanization for 5 min, and obtain a low-temperature resistant and highly elastic thermoplastic vulcanizate.

[0069] The obtained thermoplastic vulcanizate is pressed into a 2-mm-thick sheet according to the standard and its properties are tested. The properties are shown in Table 1. The atomic force logarithmic modulus diagram of the obtained thermoplastic vulcanizate is similar to Figure 1 Approximate.

[0070] Example 4

[0071] The selected raw materials and their weight parts are as follows:

[0072]

[0073] According to the above formula, first conduct rubber-plastic premixing. Melt polypropylene and antioxidant in a mixer at 170 °C and 100 rpm for 4 min until torque balance. Then add ethylene-butylene rubber into the mixer for blending for 3 min until torque balance. After continuing to blend for 2 min, pour the pre-prepared silane mother liquor (vinyltriethoxysilane, dicumyl peroxide, dibutyltin dilaurate mixed evenly in proportion) into the mixer, maintain the temperature at 190 °C and the rotation speed at 40 rpm for silane grafting for 6 min. Finally, quickly add water into the mixer, maintain the rotation speed at 100 rpm to complete dynamic vulcanization for 5 min, and obtain a low-temperature resistant and highly elastic thermoplastic vulcanizate.

[0074] The obtained thermoplastic vulcanizate is pressed into a 2-mm-thick sheet according to the standard and its properties are tested. The properties are shown in Table 1. The atomic force logarithmic modulus diagram of the obtained thermoplastic vulcanizate is similar to Figure 1 Approximate.

[0075] Example 5

[0076] The selected raw materials and their weight parts are as follows:

[0077]

[0078]

[0079] Among them, the mass ratio of dicumyl peroxide (DCP) to benzoyl peroxide (BPO) is 1:1.

[0080] According to the above formula, first conduct rubber-plastic premixing. Melt polypropylene and the antioxidant in a mixer at 170 °C and 100 rpm for 4 min until torque balance. Then add ethylene-butylene rubber to the mixer for blending for 3 min until torque balance. After continuing to blend for 2 min, pour the previously prepared silane mother liquor (vinyltriethoxysilane, dicumyl peroxide, and dibutyltin dilaurate mixed evenly in proportion) into the mixer, maintain the temperature at 190 °C and the rotation speed at 40 rpm for silane grafting for 6 min. Finally, quickly add water to the mixer, maintain the rotation speed at 100 rpm to complete dynamic vulcanization for 5 min, and obtain a low-temperature-resistant and highly elastic thermoplastic vulcanizate.

[0081] The obtained thermoplastic vulcanizate is pressed into a 2-mm-thick sheet according to the standard and its properties are tested. The properties are shown in Table 1. The atomic force logarithmic modulus diagram of the obtained thermoplastic vulcanizate is Figure 1 approximate.

[0082] Example 6

[0083] The selected raw materials and their weight parts are as follows:

[0084]

[0085] According to the above formula, first conduct rubber-plastic premixing. Melt polypropylene and the antioxidant in a mixer at 170 °C and 100 rpm for 4 min until torque balance. Then add ethylene-butylene rubber to the mixer for blending for 3 min until torque balance, and continue to blend for 2 min.

[0086] Pour the previously prepared silane mother liquor (vinyltriethoxysilane, dicumyl peroxide, and dibutyltin dilaurate mixed evenly in proportion) into the mixer, maintain the temperature at 190 °C and the rotation speed at 40 rpm to continue silane grafting for 6 min to obtain a thermoplastic vulcanizate.

[0087] The obtained thermoplastic vulcanizate is molded into a 2-mm-thick sheet, placed in 90 °C hot water for water bath crosslinking for 2 h, and its properties are tested. The properties are shown in Table 1.

[0088] Example 7

[0089] The selected raw materials and their weight parts are as follows:

[0090]

[0091] According to the above formula, first conduct rubber-plastic premixing. Melt polypropylene and antioxidant in a mixer at 170 °C and 100 rpm for 4 min until torque balance. Then add ethylene-butylene rubber into the mixer for blending for 3 min until torque balance. After continuing to blend for 2 min, pour the pre-prepared silane masterbatch (vinyltriethoxysilane, dicumyl peroxide, dibutyltin dilaurate mixed evenly in proportion) into the mixer, maintain the temperature at 190 °C and the rotation speed at 40 rpm for silane grafting for 6 min. Finally, quickly add water into the mixer, maintain the rotation speed at 100 rpm to complete dynamic vulcanization for 5 min, and obtain a low-temperature resistant and high-elastic thermoplastic vulcanizate.

[0092] The obtained thermoplastic vulcanizate is pressed into a 2-mm-thick sheet according to the standard and its properties are tested. The properties are shown in Table 1.

[0093] Comparative Example 1

[0094] The raw materials selected and their parts by weight are as follows:

[0095]

[0096]

[0097] According to the above formula, first conduct rubber-plastic premixing. Melt polypropylene and antioxidant in a mixer at 180 °C and 100 rpm until fully melted, then add ethylene-butylene rubber for blending until torque balance and discharge. Add the peroxide vulcanization system to the rubber-plastic premix in an open mill at room temperature and mix evenly to obtain a blend containing the vulcanization system. Finally, put the blend added with the vulcanization system into a mixer at 180 °C and 100 rpm for dynamic vulcanization for 5 min to complete, and obtain a thermoplastic vulcanizate.

[0098] The obtained thermoplastic vulcanizate is pressed into a 2-mm-thick sheet according to the standard and its properties are tested. The atomic force logarithmic modulus diagram of the obtained thermoplastic vulcanizate is as Figure 2 shown (the dark phase is the low-modulus rubber phase, and the bright phase is the high-modulus plastic phase).

[0099] Table 1

[0100]

[0101] In Table 1, the tensile strength, elongation at break and high-temperature compression set properties are measured according to the following standards GB / T528-2009, GB / T528-2009, GB / T7759-1996 respectively. Among them, the test conditions for compression set are: temperature -20 °C, time 22 h, compression ratio 10%.

[0102] Examples 1 - 3 only differ in the weight ratio of the silane coupling agent to the peroxide initiator. The data in Table 1 show that changes in the weight ratio of the silane coupling agent to the peroxide initiator will cause changes in the properties of the prepared thermoplastic vulcanizate, and there is an optimal ratio between the silane coupling agent and the peroxide initiator. Under the raw material ratios of Examples 1 - 3, when the ratio of the silane coupling agent to the initiator is 15 / 1, the comprehensive performance is better.

[0103] Examples 2 and 4 only differ in the rubber - plastic ratio. The data in Table 1 show that increasing the rubber - plastic ratio results in a decrease in the mechanical properties and hardness grade of the TPV, but the elastic properties are further improved.

[0104] Examples 2 and 5 only differ in the peroxide initiator used. The data in Table 1 show that the method of using a peroxide initiator in a compounded manner can greatly increase the efficiency of silane grafting and further enhance the properties.

[0105] Examples 2 and 6 differ in the preparation method. Example 6 uses the "traditional silane grafting plus static cross - linking" method. The data in Table 1 show that compared with the "traditional silane grafting plus static cross - linking" method, the method of the present invention saves a large amount of time required for static vulcanization, improves production efficiency, also improves the tensile strength and elongation at break of the product, and greatly reduces the permanent deformation rate.

[0106] Examples 2 and 7 differ in the rubber used. Example 7 uses "EPDM". The data in Table 1 show that on the premise of using the preparation method of the present invention, the tensile strength and elongation at break of the TPV prepared using traditional EPDM are weaker than those using EBT, and the low - temperature elasticity is even inferior to that of the TPV prepared using EBT.

[0107] The difference between Example 2 and Comparative Example 1 is that Comparative Example 1 uses the "traditional peroxide vulcanization formula and complete pre - dispersion dynamic vulcanization process". The data in Table 1 show that the method of the present invention avoids the problem of peroxide degrading polypropylene, reduces the usage amount of chemical agents, simplifies the production process of dynamic vulcanization, greatly improves production efficiency and environmental protection, and also greatly improves the low - temperature resistance and elasticity of the product at the same hardness grade. Relative to Figure 2 , Figure 1 the dispersed particle size of the rubber phase in Figure 1 and Figure 2 is reduced by more than about 100 nm; therefore, by comparing

[0108] In summary, the present invention uses ethylene-butylene rubber with excellent low-temperature performance and polypropylene material with excellent comprehensive performance, or adopts a one-step silane grafting and direct water addition dynamic vulcanization process to prepare an ethylene-butylene rubber / polypropylene thermoplastic vulcanizate with a fine microscopic phase structure and excellent low-temperature high elasticity, solving the problem of weak low-temperature elasticity of traditional EPDM / PP TPV.

Claims

1. A butyl rubber / polypropylene thermoplastic vulcanizate, characterized in that, The thermoplastic vulcanizate is prepared from raw materials comprising the following components; the components and their parts by weight are as follows: Wherein, the total amount of ethylene-butene rubber and polypropylene is 100 parts by weight; Preferably, the weight ratio of the silane coupling agent to the peroxide initiator is 5-25:1, more preferably 10-20:

1.

2. The ethylene-butene rubber / polypropylene thermoplastic vulcanizate according to claim 1, wherein the mass content of the third monomer of the ethylene-butene rubber is 5%-10%; or / and, the polypropylene is selected from at least one of ethylene-propylene block copolymerized polypropylene, ethylene-propylene random copolymerized polypropylene, and ethylene-propylene isotactic copolymerized polypropylene.

3. The ethylene-butene rubber / polypropylene thermoplastic vulcanizate according to claim 1, wherein the silane coupling agent is selected from at least one of vinyltriethoxysilane and vinyltrimethoxysilane; or / and, the antioxidant is selected from at least one of phenolic antioxidants.

4. The ethylene-butene rubber / polypropylene thermoplastic vulcanizate according to claim 1, wherein the peroxide initiator is selected from at least one of dicumyl peroxide, 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, and benzoyl peroxide; Preferably, the peroxide initiator is a mixture of dicumyl peroxide and benzoyl peroxide.

5. The ethylene-butene rubber / polypropylene thermoplastic vulcanizate according to claim 1, wherein the crosslinking catalyst is a catalyst that has a catalytic effect on the hydrolysis condensation reaction of alkoxy groups; Preferably, the crosslinking catalyst is selected from at least one of organotin and organoantimony catalysts; More preferably, the crosslinking catalyst is dibutyltin dilaurate.

6. The ethylene-butene rubber / polypropylene thermoplastic vulcanizate according to claim 1, wherein It is prepared by the following method: (1) Rubber-plastic premixing: Ethylene-butene rubber, polypropylene, and antioxidant are kneaded evenly in a mixer at 170°C - 200°C; (2) Silane grafting: After step (1) is completed, a silane coupling agent, a peroxide initiator, and a crosslinking catalyst are added to the mixer, and a grafting reaction is carried out at 170°C - 200°C for 5 - 10 min; preferably, the grafting reaction temperature is 175°C - 190°C, and the mixer speed is 30 - 80 rpm; (3) Silane crosslinking: After step (2) is completed, water is added to the mixer, and a crosslinking reaction is carried out at 170°C - 200°C for 4 - 8 min to produce the ethylene-butene rubber / polypropylene thermoplastic vulcanizate; preferably, the crosslinking reaction temperature is 180°C - 200°C, and the mixer speed is 80 - 120 rpm.

7. A method for preparing a thermoplastic vulcanizate, characterized in that, The preparation method comprises the following steps; (1) Rubber-plastic premixing: Rubber, plastic, and antioxidant are kneaded evenly to obtain a rubber-plastic premix; (2) Silane grafting: A silane coupling agent, a peroxide initiator, and a crosslinking catalyst are added to the rubber-plastic premix, and stirred until the rubber phase fully undergoes a grafting reaction to obtain a silane grafting system; (3) Silane crosslinking: Water is added to the silane grafting system, and stirred until the rubber is fully crosslinked to obtain a thermoplastic vulcanizate.

8. The method for preparing a thermoplastic vulcanizate according to claim 7, wherein the preparation method uses a mixer; or / and, In step (2), a silane coupling agent, a peroxide initiator, and a crosslinking catalyst are premixed in advance to form a silane mother liquor, and the silane mother liquor is added to a mixer; or / and, The temperature of the rubber and plastic premixing is 170 - 190 °C, preferably 170 °C - 200 °C; or / and, The temperature of the silane grafting is 170 °C - 200 °C, preferably 175 °C - 190 °C; or / and, The stirring speed of the silane grafting is 30 - 80 rpm; or / and, The temperature of the silane crosslinking is 170 °C - 200 °C, preferably 180 °C - 200 °C; or / and, The rotation speed of the silane crosslinking is 80 - 120 rpm.

9. The method for preparing a thermoplastic vulcanizate according to claim 7, wherein The rubber is selected from ethylene-butene rubber; or / and, The plastic is selected from polypropylene.

10. The method for preparing a thermoplastic vulcanizate according to claim 7, wherein The weight parts of the rubber, plastic, antioxidant, silane coupling agent, peroxide initiator, crosslinking catalyst, and water are: 30 - 90 weight parts of rubber, preferably 55 - 70 weight parts; 70 - 10 weight parts of plastic, preferably 45 - 30 weight parts; 0.05 - 0.3 weight parts of antioxidant, preferably 0.05 - 0.1 weight parts; 1 - 10 weight parts of silane coupling agent, preferably 2 - 5 weight parts; 0.01 - 0.5 weight parts of peroxide initiator, preferably 0.1 - 0.4 weight parts; 0.05 - 0.5 weight parts of crosslinking catalyst, preferably 0.1 - 0.2 weight parts; 1 - 15 weight parts of water, preferably 5 - 10 weight parts; wherein the total amount of the rubber and the plastic is 100 weight parts.

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