Composition for preparing thermoplastic elastomer, thermoplastic elastomer as well as preparation method and application of thermoplastic elastomer

Abstract

The invention relates to the field of thermoplastic elastomers, and discloses a composition for preparing a thermoplastic elastomer, the thermoplastic elastomer as well as a preparation method and application of the thermoplastic elastomer. The composition provided by the invention contains ethylene propylene diene monomer, reclaimed rubber powder, polypropylene, a vulcanizing agent, an antioxidant and nano kaolin, wherein relative to 100 parts by weight of the ethylene propylene diene monomer, the content of the reclaimed rubber powder is 2 to 60 parts by weight, the content of the polypropylene is 40 to 120 parts by weight, the content of the vulcanizing agent is 0.5 to 15 parts by weight, the content of the antioxidant is 0.05 to 8 parts by weight, and the content of the nano kaolin is 0.5 to 30 parts by weight. The thermoplastic elastomer prepared from the composition provided by the invention has the advantages of good physical and mechanical properties and low cost.

Description

Technical Field

[0001] The present invention relates to the field of thermoplastic elastomers, and in particular, to a composition for preparing a nano kaolin modified ethylene propylene diene monomer / reclaimed rubber powder / polypropylene thermoplastic elastomer, the nano kaolin modified ethylene propylene diene monomer / reclaimed rubber powder / polypropylene thermoplastic elastomer, and its preparation method and application. Background Art

[0002] A large amount of waste tires are generated globally every year, causing great pollution to the environment. The recycling of waste tires has attracted great attention from people. Among them, reclaimed rubber (powder) is the main product of waste tire treatment. However, due to the poor strength of reclaimed rubber powder itself, it cannot be widely used in rubber products and tires. The existing technology only adds reclaimed rubber powder to tires and rubber products to reduce costs.

[0003] The thermoplastic elastomer (TPV) prepared by the dynamic vulcanization technology, which is a rubber-plastic composite, is increasingly widely used in fields such as automobiles, construction, and household appliances. Dynamic vulcanization means that under high temperature and high shear conditions, the rubber undergoes vulcanization while being broken and dispersed into the plastic continuous phase under the action of a crosslinking agent, and finally forms a micron-sized vulcanized rubber phase in the plastic continuous phase. TPV successfully combines some characteristics of vulcanized rubber, such as heat resistance and low compression set performance, with the easy processing characteristics of thermoplastic plastics. Moreover, it is green and environmentally friendly, recyclable, and has a wide range of applications. Among them, the TPV product with the highest output and the most extensive application is ethylene propylene diene monomer / polypropylene thermoplastic elastomer. Replacing part of the ethylene propylene diene monomer with reclaimed rubber powder for preparing TPV is an effective way to reduce costs, and at the same time provides a solution to the problem of waste tire recycling. However, the performance of reclaimed rubber powder is poor, and the TPV prepared with it has defects in mechanical properties. Summary of the Invention

[0004] The purpose of the present invention is to overcome the problems existing in the prior art that the performance of reclaimed rubber powder is poor and the TPV prepared with it has defects in mechanical properties, and to provide a composition for preparing a nano kaolin modified ethylene propylene diene monomer / reclaimed rubber powder / polypropylene thermoplastic elastomer, the nano kaolin modified ethylene propylene diene monomer / reclaimed rubber powder / polypropylene thermoplastic elastomer, and its preparation method and application. The thermoplastic elastomer prepared by using the composition of the present invention has the advantages of good physical and mechanical properties and low cost.

[0005] The inventors of the present invention have found through in-depth research that by using the specific composition for preparing thermoplastic elastomers of the present invention and carrying out mixing and dynamic vulcanization, the obtained thermoplastic elastomer can have the advantages of good physical and mechanical properties and low cost, thus completing the present invention.

[0006] Accordingly, on the one hand, the present invention provides a composition for preparing a thermoplastic elastomer, characterized in that the composition contains ethylene-propylene-diene monomer (EPDM) rubber, recycled rubber powder, polypropylene, vulcanizing agent, antioxidant and nano kaolin; wherein, relative to 100 parts by weight of the ethylene-propylene-diene monomer (EPDM) rubber, the content of the recycled rubber powder is 2-60 parts by weight, the content of the polypropylene is 40-120 parts by weight, the content of the vulcanizing agent is 0.5-15 parts by weight, the content of the antioxidant is 0.05-8 parts by weight, and the content of the nano kaolin is 0.5-30 parts by weight.

[0007] Preferably, relative to 100 parts by weight of the ethylene-propylene-diene monomer (EPDM) rubber, the content of the recycled rubber powder is 5-50 parts by weight, the content of the polypropylene is 50-100 parts by weight, the content of the vulcanizing agent is 1-10 parts by weight, the content of the antioxidant is 0.1-5 parts by weight, and the content of the nano kaolin is 1-20 parts by weight.

[0008] Preferably, the vulcanizing agent is an organic peroxide.

[0009] Preferably, the organic peroxide is one or more of dicumyl peroxide, bis(tert-butylperoxyisopropyl)benzene, tert-butylcumyl peroxide, 2,5-bis(tert-butylperoxy)-2,5-dimethyl-3-hexyne, 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane, benzoyl peroxide, tert-butyl perbenzoate and di-tert-butyl peroxide.

[0010] Preferably, the antioxidant is one or more of pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2,6-di-tert-butyl-p-cresol, 2,2'-methylenebis(4-methyl-6-tert-butylphenol) and 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane.

[0011] Preferably, the nano kaolin is kaolin nanoparticles with a lamellar thickness in the range of 20-50 nm and a lamellar size in the range of 300-500 nm.

[0012] Preferably, the polypropylene has a weight-average molecular weight of 20,000-900,000 g / mol, a molecular weight distribution of 2.5-4, and an isotacticity of greater than 95 wt%.

[0013] According to the second aspect of the present invention, there is provided a thermoplastic elastomer, which is prepared by using the composition for preparing a thermoplastic elastomer described in the first aspect of the present invention.

[0014] According to the third aspect of the present invention, there is provided a method for preparing a thermoplastic elastomer, which uses the composition for preparing a thermoplastic elastomer described in the first aspect of the present invention, and the method includes the following steps

[0015] 1) The components in Component A are successively kneaded and first pelletized to obtain kneaded material pellets. Component A contains polypropylene, an antioxidant, ethylene-propylene-diene monomer (EPDM) rubber, and recycled rubber powder.

[0016] 2) The kneaded material pellets are dynamically vulcanized and second pelletized with the components in Component B to obtain thermoplastic vulcanizate particles. Component B contains a vulcanizing agent and nano kaolin.

[0017] Preferably, the conditions for the kneading include: a rotation speed of 60 - 90 rpm and a kneading temperature of 160 - 220 °C.

[0018] Preferably, in step 1), the kneading is carried out in a mixer.

[0019] Preferably, in step 1), the first pelletizing is carried out in a single-screw extruder.

[0020] Preferably, in step 1), the conditions for the first pelletizing include: a screw rotation speed of 50 - 200 rpm and an extrusion temperature of 160 - 220 °C.

[0021] Preferably, in step 2), the dynamic vulcanization is carried out in a co-rotating twin-screw extruder.

[0022] Preferably, in step 2), the conditions for the dynamic vulcanization include: a screw rotation speed of 50 - 200 rpm, a head temperature of 170 - 200 °C, a temperature of the screw feeding section of 120 - 170 °C, and a temperature of the molten kneading section of 180 - 220 °C.

[0023] According to the fourth aspect of the present invention, there is provided a thermoplastic elastomer, which is prepared by using the method described in the third aspect of the present invention.

[0024] According to the fifth aspect of the present invention, there is provided the use of the thermoplastic elastomer described in the fourth aspect of the present invention as a tire.

[0025] For the nano kaolin-modified EPDM rubber / recycled rubber powder / polypropylene thermoplastic elastomer according to the present invention, a dynamic vulcanization processing method is adopted, which has the advantages of simple process operation, easy control of production conditions, less scrap, energy saving, and high productivity.

[0026] In addition, using recycled rubber powder to replace part of the EPDM rubber can reduce costs and reduce environmental pollution caused by waste tires. The prepared nano kaolin-modified EPDM rubber / recycled rubber powder / polypropylene thermoplastic elastomer has good physical and mechanical properties, a simple process, and is easy to process, and can be used in fields such as automobiles and construction. Detailed Embodiments

[0027] The endpoints and any values in the ranges disclosed herein are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0028] In the present invention, "reclaimed rubber powder" refers to waste rubber processed into powdery particles of various different finenesses under the action of machinery, and those with a size less than 1.5 mm are called rubber powder. The preparation of reclaimed rubber powder mainly includes three main parts: pulverization, desulfurization, and refining. Among them, pulverization and refining are mechanical treatments, and desulfurization is a chemical treatment. "Reclaimed rubber powder" can be prepared by conventional methods in the art or obtained through commercial purchase.

[0029] Preferably, the particle size of the reclaimed rubber powder is 0.075 - 1.5 mm, and more preferably 0.3 - 0.5 mm.

[0030] According to the first aspect of the present invention, there is provided a composition for preparing a thermoplastic elastomer, characterized in that the composition contains ethylene-propylene-diene monomer rubber, reclaimed rubber powder, polypropylene, vulcanizing agent, antioxidant, and nano kaolin; wherein, relative to 100 parts by weight of the ethylene-propylene-diene monomer rubber, the content of the reclaimed rubber powder is 2 - 60 parts by weight, the content of the polypropylene is 40 - 120 parts by weight, the content of the vulcanizing agent is 0.5 - 15 parts by weight, the content of the antioxidant is 0.05 - 8 parts by weight, and the content of the nano kaolin is 0.5 - 30 parts by weight.

[0031] According to the present invention, preferably, relative to 100 parts by weight of the ethylene-propylene-diene monomer rubber, the content of the reclaimed rubber powder is 5 - 50 parts by weight, the content of the polypropylene is 50 - 100 parts by weight, the content of the vulcanizing agent is 1 - 10 parts by weight, the content of the antioxidant is 0.1 - 5 parts by weight, and the content of the nano kaolin is 1 - 20 parts by weight.

[0032] Specific examples of the content of the recycled rubber powder relative to 100 parts by weight of the ethylene-propylene-diene monomer rubber can be, for example: 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 18 parts by weight, 19 parts by weight, 20 parts by weight, 21 parts by weight, 22 parts by weight, 23 parts by weight, 24 parts by weight, 25 parts by weight, 26 parts by weight, 27 parts by weight, 28 parts by weight, 29 parts by weight, 30 parts by weight, 31 parts by weight, 32 parts by weight, 33 parts by weight, 34 parts by weight, 35 parts by weight, 36 parts by weight, 37 parts by weight, 38 parts by weight, 39 parts by weight, 40 parts by weight, 41 parts by weight, 42 parts by weight, 43 parts by weight, 44 parts by weight, 45 parts by weight, 46 parts by weight, 47 parts by weight, 48 parts by weight, 49 parts by weight, 50 parts by weight, 51 parts by weight, 52 parts by weight, 53 parts by weight, 54 parts by weight, 55 parts by weight, 56 parts by weight, 57 parts by weight, 58 parts by weight, 59 parts by weight, 60 parts by weight, etc., and ranges formed by any two of the above.

[0033] Specific examples of the content of the polypropylene relative to 100 parts by weight of the ethylene-propylene-diene monomer rubber can be, for example: 40 parts by weight, 45 parts by weight, 50 parts by weight, 55 parts by weight, 60 parts by weight, 65 parts by weight, 70 parts by weight, 75 parts by weight, 80 parts by weight, 85 parts by weight, 90 parts by weight, 95 parts by weight, 100 parts by weight, 105 parts by weight, 110 parts by weight, 115 parts by weight, 120 parts by weight, etc., and ranges formed by any two of the above.

[0034] Specific examples of the content of the vulcanizing agent relative to 100 parts by weight of the ethylene-propylene-diene monomer rubber can be, for example: 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight, 1 part by weight, 1.2 parts by weight, 1.4 parts by weight, 1.6 parts by weight, 1.8 parts by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, 15 parts by weight, etc., and ranges formed by any two of the above.

[0035] Specific examples of the content of the antioxidant relative to 100 parts by weight of the ethylene-propylene-diene rubber may include, for example: 0.1 part by weight, 0.2 part by weight, 0.3 part by weight, 0.4 part by weight, 0.5 part by weight, 0.6 part by weight, 0.7 part by weight, 0.8 part by weight, 0.9 part by weight, 1 part by weight, 1.2 parts by weight, 1.4 parts by weight, 1.6 parts by weight, 1.8 parts by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, etc., and ranges formed by any two of the above.

[0036] Specific examples of the content of the nano kaolin relative to 100 parts by weight of the ethylene-propylene-diene rubber may include, for example: 1 part by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 18 parts by weight, 19 parts by weight, 20 parts by weight, etc., and ranges formed by any two of the above.

[0037] According to the present invention, preferably, the weight-average molecular weight of the polypropylene is 20,000 - 900,000 g / mol, the molecular weight distribution is 2.5 - 4, and the isotacticity is greater than 95 wt%; more preferably, the weight-average molecular weight of the polypropylene is 300,000 - 400,000 g / mol, the molecular weight distribution is 3 - 4, and the isotacticity is greater than 96 wt%.

[0038] According to the present invention, preferably, the vulcanizing agent is an organic peroxide.

[0039] Specific examples of the organic peroxide may include, for example: dicumyl peroxide, bis(tert-butylperoxyisopropyl)benzene, tert-butylcumyl peroxide, 2,5-bis(tert-butylperoxy)-2,5-dimethyl-3-hexyne, 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane, benzoyl peroxide, tert-butyl perbenzoate, and di-tert-butyl peroxide. One of them can be used, or two or more of them can be used.

[0040] In a preferred embodiment of the present invention, the vulcanizing agent is selected from at least one of dicumyl peroxide, bis(tert-butylperoxyisopropyl)benzene, tert-butylcumyl peroxide, 2,5-bis(tert-butylperoxy)-2,5-dimethyl-3-hexyne, 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane, benzoyl peroxide, tert-butyl perbenzoate, and di-tert-butyl peroxide. Thus, a nano kaolin-modified ethylene-propylene-diene rubber / reclaimed rubber powder / polypropylene thermoplastic elastomer having more excellent physical and mechanical properties can be obtained by using the composition.

[0041] According to the present invention, preferably, the antioxidant is one or more of pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2,6-di-tert-butyl-p-cresol, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), and 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane.

[0042] According to the present invention, preferably, the nano kaolin is kaolin nanoparticles with a lamellar thickness of 20 - 50 nm and an average lamellar size of 300 - 500 nm.

[0043] In a preferred embodiment of the present invention, the nano kaolin has a lamellar thickness of 20 - 50 nm, an average lamellar size of 300 nm, a specific surface area of 32 m 2 / g, and a bulk density of 0.05 - 0.07 g / cm 3 .

[0044] As the above nano kaolin, for example, it can be purchased from Shandong Zaozhuang Sanxing High-Tech Materials Co., Ltd.

[0045] The inventors found that by using the above composition of the present invention, the components with specific contents in the composition cooperate with each other, and a thermoplastic elastomer can be prepared, and the prepared thermoplastic elastomer has the advantages of good physical and mechanical properties and low cost.

[0046] According to the second aspect of the present invention, there is provided a thermoplastic elastomer, wherein it is prepared by using the composition for preparing a thermoplastic elastomer described in the first aspect of the present invention.

[0047] According to the third aspect of the present invention, there is provided a method for preparing a thermoplastic elastomer, wherein this method uses the composition for preparing a thermoplastic elastomer described in the first aspect of the present invention, and this method includes the following steps,

[0048] 1) Mix and first granulate each component in component A in sequence to obtain kneaded material particles, and component A contains polypropylene, an antioxidant, ethylene-propylene-diene monomer rubber, and recycled rubber powder;

[0049] 2) Dynamically vulcanize and second granulate the kneaded material particles with each component in component B to obtain thermoplastic vulcanizate rubber particles, and component B contains a vulcanizing agent and nano kaolin.

[0050] In the method described in the third aspect of the present invention, the types and amounts of polypropylene, antioxidant, ethylene propylene diene monomer (EPDM) rubber, and recycled rubber powder in Component A, and the types and amounts of vulcanizing agent and nano kaolin in Component B are the same as those of the polypropylene, antioxidant, EPDM rubber, recycled rubber powder, vulcanizing agent, and nano kaolin in the composition described in the first aspect above, and will not be elaborated herein one by one.

[0051] Preferably, in step 1), the conditions for mixing include: a rotational speed of 60 - 90 rpm and a mixing temperature of 160 - 220 °C.

[0052] Preferably, in step 1), the mixing is carried out in an internal mixer.

[0053] Preferably, in step 1), the first pelletizing is carried out in a single-screw extruder.

[0054] Preferably, in step 1), the conditions for the first pelletizing include: a screw rotational speed of 50 - 200 rpm and an extrusion temperature of 160 - 220 °C.

[0055] Preferably, in step 2), the dynamic vulcanization is carried out in a co-rotating twin-screw extruder.

[0056] Preferably, in step 2), the conditions for the dynamic vulcanization include: a screw rotational speed of 50 - 200 rpm, a die head temperature of 170 - 200 °C, a screw feeding section temperature of 120 - 170 °C, and a melting and mixing section temperature of 180 - 220 °C.

[0057] According to a particularly preferred specific embodiment, the method for preparing the thermoplastic elastomer includes:

[0058] 1) Add polypropylene and antioxidant to an internal mixer. After the polypropylene melts, add EPDM rubber and recycled rubber powder, and carry out high-temperature melting and mixing to obtain a mixed material. The mixing conditions include: a rotational speed of 60 - 90 rpm and a mixing temperature of 160 - 220 °C; carry out the first pelletizing of the mixed material through a single-screw extruder to obtain mixed material pellets. The conditions for the first pelletizing include: a screw rotational speed of 50 - 200 rpm and an extrusion temperature of 160 - 220 °C;

[0059] 2) Carry out dynamic vulcanization and second pelletizing of the mixed material pellets prepared in step 1) with a vulcanizing agent and nano kaolin in a co-rotating twin-screw extruder to obtain vulcanized rubber particles; the conditions for the dynamic vulcanization include: a screw rotational speed of 50 - 200 rpm, a die head temperature of 170 - 200 °C, a screw feeding section temperature of 120 - 170 °C, and a melting and mixing section temperature of 180 - 220 °C.

[0060] According to the fourth aspect of the present invention, there is provided a thermoplastic elastomer, which is prepared by using the method described in the third aspect of the present invention.

[0061] According to the fifth aspect of the present invention, there is provided the use of the thermoplastic elastomer described in the fourth aspect of the present invention as a tire.

[0062] The present invention will be described in detail below by way of examples, but the present invention is not limited to the following examples.

[0063] In the following examples, unless otherwise specified, the raw materials used are commercially available products.

[0064] In the following examples, the recycled rubber powder is from waste rubber, with a particle size of 0.075 - 1.5 mm, and is purchased from Jiangsu Zhonghong Environmental Protection Technology Co., Ltd.

[0065] In the following examples, the properties involved are tested by the following methods:

[0066] (1) Hardness: Tested according to the standard GB / T 531.1 - 2008;

[0067] (2) Tensile strength: Tested according to the standard GB / T 6344 - 2008;

[0068] (3) Elongation at break: Tested according to the standard GB / T 6344 - 2008.

[0069] In the following examples, unless otherwise specified, each part by weight (or each portion) represents 1 g.

[0070] Example 1

[0071] (1) At 180 °C, 80 parts by weight of polypropylene (purchased from Sinopec Yangzi Petrochemical Co., Ltd., grade F401, weight - average molecular weight of 350,000 g / mol, molecular weight distribution of 3.57, isotacticity of 97%) and 0.5 part by weight of antioxidant 1010 (pentaerythritol tetrakis [β - (3,5 - di - tert - butyl - 4 - hydroxyphenyl) propionate]) are added to a Banbury mixer. After the polypropylene is melted, 100 parts by weight of ethylene - propylene - diene monomer rubber (purchased from Shanghai Sinopec Mitsui Chemical Co., Ltd., grade 3092PM) and 10 parts by weight of recycled rubber powder are added, and high - temperature melting and mixing are carried out to obtain a mixed material. The mixing conditions include: rotation speed of 75 rpm, mixing temperature of 180 °C; the mixed material is granulated for the first time through a single - screw extruder to obtain mixed - material particles. The conditions for the first granulation include: screw rotation speed of 100 rpm, extrusion temperature of 200 °C.

[0072] (2)Mix the masterbatch granules prepared in step (1) with 10 parts by weight of nano kaolin (sheet thickness 20 - 50 nm, average sheet size 300 nm, specific surface area 32 m 2 / g, bulk density 0.05 - 0.07 g / cm 3 , purchased from Sanxing High - tech Materials Co., Ltd., Zaozhuang, Shandong, the same hereinafter) and 2 parts by weight of vulcanizing agent (dicumyl peroxide) in a co - rotating twin - screw extruder for dynamic vulcanization and secondary pelletizing to obtain thermoplastic vulcanized rubber particles. The conditions for the dynamic vulcanization include: screw speed 200 rpm, head temperature 180 °C, temperature of the screw feeding section 150 °C, temperature of the melt mixing section 180 °C.

[0073] Example 2

[0074] (1) At 160 °C, add 50 parts by weight of polypropylene (purchased from Yangzi Petrochemical Co., Ltd., Sinopec, grade F401, weight - average molecular weight 350,000 g / mol, molecular weight distribution 3.57, isotacticity 97%) and 0.1 part by weight of antioxidant 2246 (2,2 - methylenebis(4 - methyl - 6 - tert - butylphenol)) into a Banbury mixer. After the polypropylene melts, add 100 parts by weight of ethylene - propylene - diene monomer rubber (purchased from Shanghai SINOPEC Mitsui Chemicals Co., Ltd., grade 3092PM) and 5 parts by weight of recycled rubber powder, and conduct melt mixing at high temperature to obtain a masterbatch. The mixing conditions include: rotation speed 60 rpm, mixing temperature 160 °C; pelletize the masterbatch through a single - screw extruder to obtain masterbatch granules. The conditions for the first pelletizing include: screw speed 50 rpm, extrusion temperature 160 °C.

[0075] (2) Mix the masterbatch granules prepared in step (1) with 1 part by weight of nano kaolin and 1 part by weight of vulcanizing agent (bis(tert - butylperoxyisopropyl)benzene) in a co - rotating twin - screw extruder for dynamic vulcanization and secondary pelletizing to obtain thermoplastic vulcanized rubber particles. The conditions for the dynamic vulcanization include: screw speed 150 rpm, head temperature 170 °C, temperature of the screw feeding section 120 °C, temperature of the melt mixing section 220 °C.

[0076] Example 3

[0077] (1) At 200 °C, 100 parts by weight of polypropylene (purchased from Sinopec Yangzi Petrochemical Co., Ltd., grade F401, weight-average molecular weight of 350,000 g / mol, molecular weight distribution of 3.57, isotacticity of 97%) and 5 parts by weight of antioxidant 1010 were added to a Banbury mixer. After the polypropylene was melted, 100 parts by weight of ethylene-propylene-diene monomer rubber (purchased from Shanghai Sinopec Mitsui Chemicals Co., Ltd., grade 3092PM) and 50 parts by weight of recycled rubber powder were added, and they were mixed by high-temperature melting to obtain a mixed material. The mixing conditions included: a rotation speed of 90 rpm and a mixing temperature of 200 °C; the mixed material was granulated for the first time through a single-screw extruder to obtain mixed material particles. The conditions for the first granulation included: a screw rotation speed of 200 rpm and an extrusion temperature of 220 °C.

[0078] (2) The mixed material particles prepared in step (1) were dynamically vulcanized and granulated for the second time with 20 parts by weight of nano kaolin and 10 parts by weight of a vulcanizing agent (dicumyl peroxide) in a co-rotating twin-screw extruder to obtain thermoplastic vulcanized rubber particles. The conditions for the dynamic vulcanization included: a screw rotation speed of 50 rpm, a head temperature of 200 °C, a screw feeding section temperature of 170 °C, and a melting and mixing section temperature of 200 °C.

[0079] Example 4

[0080] (1) At 220 °C, 60 parts by weight of polypropylene (purchased from Sinopec Yangzi Petrochemical Co., Ltd., grade F401, weight-average molecular weight of 350,000 g / mol, molecular weight distribution of 3.57, isotacticity of 97%) and 0.5 parts by weight of antioxidant 1010 were added to a Banbury mixer. After the polypropylene was melted, 100 parts by weight of ethylene-propylene-diene monomer rubber (purchased from Shanghai Sinopec Mitsui Chemicals Co., Ltd., grade 3092PM) and 20 parts by weight of recycled rubber powder were added, and they were mixed by high-temperature melting to obtain a mixed material. The mixing conditions included: a rotation speed of 75 rpm and a mixing temperature of 220 °C; the mixed material was granulated for the first time through a single-screw extruder to obtain mixed material particles. The conditions for the first granulation included: a screw rotation speed of 100 rpm and an extrusion temperature of 200 °C.

[0081] (2) The mixed material particles prepared in step (1) were dynamically vulcanized and granulated for the second time with 5 parts by weight of nano kaolin and 2 parts by weight of a vulcanizing agent (dicumyl peroxide) in a co-rotating twin-screw extruder to obtain thermoplastic vulcanized rubber particles. The conditions for the dynamic vulcanization included: a screw rotation speed of 200 rpm, a head temperature of 190 °C, a screw feeding section temperature of 130 °C, and a melting and mixing section temperature of 210 °C.

[0082] Example 5

[0083] (1) At 180 °C, 80 parts by weight of polypropylene (purchased from Sinopec Yangzi Petrochemical Co., Ltd., grade F401, weight-average molecular weight of 350,000 g / mol, molecular weight distribution of 3.57, isotacticity of 97%) and 1 part by weight of antioxidant 1010 were added to a Banbury mixer. After the polypropylene was melted, 100 parts by weight of ethylene-propylene-diene monomer rubber (purchased from Shanghai Sinopec Mitsui Chemicals Co., Ltd., grade 3092PM) and 40 parts by weight of recycled rubber powder were added, and they were melt-mixed at a high temperature to obtain a mixed material. The mixing conditions included: a rotation speed of 75 rpm and a mixing temperature of 180 °C. The mixed material was pelletized for the first time through a single-screw extruder to obtain mixed material pellets. The conditions for the first pelletization included: a screw rotation speed of 150 rpm and an extrusion temperature of 190 °C.

[0084] (2) The mixed material pellets prepared in step (1) were dynamically vulcanized and pelletized for the second time with 15 parts by weight of nano kaolin and 5 parts by weight of a vulcanizing agent (dicumyl peroxide) in a co-rotating twin-screw extruder to obtain thermoplastic vulcanizate particles. The conditions for the dynamic vulcanization included: a screw rotation speed of 200 rpm, a head temperature of 200 °C, a screw feeding section temperature of 120 °C, and a melting and mixing section temperature of 220 °C.

[0085] Comparative Example 1

[0086] It was carried out in a similar method to Example 1, except that: the weight part of the added nano kaolin was 0, and the rest were the same as in Example 1, to obtain thermoplastic vulcanizate particles.

[0087] Comparative Example 2

[0088] It was carried out in a similar method to Example 1, except that: the weight part of the added recycled rubber powder was 0, and the rest were the same as in Example 1, to obtain thermoplastic vulcanizate particles.

[0089] Comparative Example 3

[0090] It was carried out in a similar method to Example 1, except that: the weight part of the added recycled rubber powder was 80, and the rest were the same as in Example 1, to obtain thermoplastic vulcanizate particles.

[0091] Test Example

[0092] The physical and mechanical properties of the thermoplastic vulcanizates prepared in the above examples were tested respectively, and the specific results are shown in Table 1.

[0093] Table 1

[0094]

[0095] It can be seen from Table 1 that the thermoplastic elastomer obtained by using the composition of the present invention has excellent comprehensive properties and significantly reduced costs.

[0096] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should equally be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A composition for preparing a thermoplastic elastomer, characterized in that, The composition contains ethylene-propylene-diene monomer (EPDM) rubber, recycled rubber powder, polypropylene, vulcanizing agent, antioxidant, and nano kaolin; wherein, relative to 100 parts by weight of the EPDM rubber, the content of the recycled rubber powder is 2 - 60 parts by weight, the content of the polypropylene is 40 - 120 parts by weight, the content of the vulcanizing agent is 0.5 - 15 parts by weight, the content of the antioxidant is 0.05 - 8 parts by weight, and the content of the nano kaolin is 0.5 - 30 parts by weight.

2. The composition according to claim 1, wherein, Relative to 100 parts by weight of the EPDM rubber, the content of the recycled rubber powder is 5 - 50 parts by weight, the content of the polypropylene is 50 - 100 parts by weight, the content of the vulcanizing agent is 1 - 10 parts by weight, the content of the antioxidant is 0.1 - 5 parts by weight, and the content of the nano kaolin is 1 - 20 parts by weight.

3. The composition according to claim 1, wherein The vulcanizing agent is an organic peroxide; Preferably, the organic peroxide is one or more of dicumyl peroxide, bis(tert-butylperoxyisopropyl)benzene, tert-butylcumyl peroxide, 2,5-bis(tert-butylperoxy)-2,5-dimethyl-3-hexyne, 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane, benzoyl peroxide, tert-butyl perbenzoate, and di-tert-butyl peroxide.

4. The composition according to any one of claims 1-3, wherein The antioxidant is one or more of pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2,6-di-tert-butyl-p-cresol, 2,2-methylenebis(4-methyl-6-tert-butylphenol), and 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane.

5. The composition according to any one of claims 1-3, wherein, The nano kaolin is kaolin nanoparticles with a lamellar thickness in the range of 20 - 50 nm and a lamellar size in the range of 300 - 500 nm.

6. The composition according to any one of claims 1-3, wherein, The polypropylene has a weight-average molecular weight of 20,000 - 900,000 g / mol, a molecular weight distribution of 2.5 - 4, and an isotacticity greater than 95 wt%.

7. A thermoplastic elastomer, characterized in that, It is prepared by using the composition for preparing a thermoplastic elastomer described in any one of claims 1 - 6.

8. A preparation method of a thermoplastic elastomer, characterized in that, This method uses the composition for preparing a thermoplastic elastomer described in any one of claims 1 - 6, and this method includes the following steps. 1) Mix and granulate the components in component A in sequence to obtain mixed granule materials. Component A contains polypropylene, antioxidant, EPDM rubber, and recycled rubber powder. 2) Perform dynamic vulcanization and second granulation on the mixed granule materials with the components in component B to obtain thermoplastic vulcanizate particles. Component B contains a vulcanizing agent and nano kaolin.

9. The method according to claim 8, wherein, In step 1), the conditions for mixing include: a rotation speed of 60 - 90 rpm and a mixing temperature of 160 - 220 °C. Preferably, in step 1), the mixing is carried out in a Banbury mixer. Preferably, in step 1), the first granulation is carried out in a single-screw extruder. Preferably, in step 1), the conditions for the first granulation include: a screw rotation speed of 50 - 200 rpm and an extrusion temperature of 160 - 220 °C.

10. The method according to claim 9, wherein In step 2), the dynamic vulcanization is carried out in a co-rotating twin-screw extruder. Preferably, in step 2), the conditions for dynamic vulcanization include: the screw speed is 50 - 200 rpm, the head temperature is 170 - 200 °C, the temperature of the screw feeding section is 120 - 170 °C, and the temperature of the melting and mixing section is 180 - 220 °C.

11. A thermoplastic elastomer, characterized in that, It is prepared by using the method described in any one of claims 8 - 10.

12. Use of the thermoplastic elastomer according to claim 11 in a tire.

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