A process for the preparation of a high flow dynamic vulcanized elastomer for thin walled products

Abstract

The embodiment of the application provides a preparation method of a high-flow dynamic vulcanized elastomer for a thin-walled product, comprising the following steps: putting EPDM and mineral oil into a banbury mixer for banburying; then adding super-high-melt-index low-styrene-content SEBS and continuing banburying; continuing to add a cross-linking aid, an antioxidant and a silicon-based lubricant for banburying; finally, adding high-melt-index polypropylene and banburying to obtain a preformed material; mixing, surface grinding, hot cutting and granulating the preformed material to obtain a vulcanized masterbatch; uniformly mixing the vulcanized masterbatch, high-viscosity polypropylene and a vulcanizing agent to obtain a mixture; and putting the mixture into a double-screw extruder for extrusion granulation to obtain a high-flow dynamic vulcanized thermoplastic elastomer with a melt flow rate (MFR) of more than 100 g / 10 min. The dynamic vulcanized thermoplastic elastomer obtained by the application not only has high flowability and formability, but also has excellent mechanical properties, so that it can meet the processing requirements of thin-walled products.

Description

A method for preparing a high-flow dynamic vulcanized elastomer for thin-walled products Technical Field

[0001] This application relates to the field of polymer materials technology, and in particular to a method for preparing a high-flow dynamic vulcanized elastomer for thin-walled products. Background Technology

[0002] Dynamically vulcanized thermoplastic elastomers are polymeric materials obtained by melting and blending plastics and rubber at high temperatures, followed by dynamic vulcanization. Before dynamic vulcanization, the plastic is the dispersed phase and the rubber is the continuous phase. During dynamic vulcanization, the rubber undergoes a cross-linking reaction with the vulcanizing agent and is simultaneously broken into tiny particles under strong shear force, which are uniformly dispersed in the plastic system. Ultimately, this forms a polymeric material with a "sea-island" two-phase structure, where the plastic is the continuous phase and the rubber is the dispersed phase.

[0003] Due to limitations in rubber properties, dynamically vulcanized thermoplastic elastomers (VTLEs) exhibit poor flowability. Typically, at 230℃ and 2.16 kg, their melt flow index (MFR) is only 0.2–3 g / 10 min. Even some specially modified VTLEs only achieve 10–20 g / 10 min under these conditions. This level of flowability makes these materials suitable only for producing thicker products. When manufacturing large-area products with a thickness of less than 2 mm, such as automotive dashboards, they exhibit surface defects like flow marks and wavy lines, and are difficult to mold during production. Summary of the Invention

[0004] This application aims to address the technical problem that the poor flowability of dynamic vulcanized thermoplastic elastomers in the prior art prevents their effective application in thin-walled products with a thickness of less than 2 mm. It proposes a method for preparing a high-flow dynamic vulcanized elastomer for thin-walled products, effectively improving the flowability and moldability of the dynamic vulcanized thermoplastic elastomer, resulting in thin-walled products with excellent appearance and processing performance.

[0005] To achieve the above objectives, this application adopts the following technical solution:

[0006] A method for preparing a high-flow dynamic vulcanized elastomer for thin-walled products includes the following steps:

[0007] Place EPDM and mineral oil into a mixer and mix at 100℃~150℃ for 2~5 minutes;

[0008] Add ultra-high melt flow index (MFR) low styrene content SEBS to an internal mixer and continue mixing at 100℃~150℃ for 4~7 minutes; the ultra-high melt flow index (MFR) low styrene content SEBS at 230℃×2.16kg has a melt flow index (MFR) >150g / 10min and a styrene content of 15%~25%;

[0009] Add crosslinking agent, antioxidant, and silicone-based lubricant to the internal mixer, and continue mixing at 100℃~150℃ for 2~3 minutes;

[0010] Add high melt flow index polypropylene to the internal mixer and continue mixing at 160℃~165℃ for 2~3 minutes to obtain the preform; the high melt flow index polypropylene has a melt flow index (MFR) > 100 g / 10 min at 230℃×2.16 kg.

[0011] The preformed material is put into a single screw extruder for mixing, grinding and hot cutting granulation to obtain vulcanized masterbatch;

[0012] The vulcanizing masterbatch, high-viscosity polypropylene, and vulcanizing agent are mixed evenly to obtain a mixture; the high-viscosity polypropylene has a melt flow index (MFR) of <1.5 g / 10min at 230℃ × 2.16 kg.

[0013] The mixture is fed into a twin-screw extruder for extrusion granulation to obtain a high-flow dynamic vulcanized thermoplastic elastomer. The high-flow dynamic vulcanized thermoplastic elastomer has a melt flow index (MFR) > 100 g / 10 min under the condition of 230℃ × 2.16 kg.

[0014] Furthermore, the mineral oil is a high-viscosity mineral oil, with a viscosity greater than 90 mmHg at 40°C. 2 / s.

[0015] Furthermore, the crosslinking agent is one of triallyl isocyanate and N,N-m-phenylbismaleimide.

[0016] Furthermore, the antioxidant comprises a primary antioxidant and a secondary antioxidant, wherein the mass ratio of the primary antioxidant to the secondary antioxidant is (1:1) to (1:3).

[0017] Furthermore, the primary antioxidant is one of hindered phenolic antioxidants or hindered amine antioxidants, and the secondary antioxidant is one of phosphite antioxidants, thioester antioxidants, or thiodipropionate antioxidants.

[0018] Furthermore, the silicone-based lubricant is one of silicone, alkyl silicone wax, or phenyl silicone oil.

[0019] Furthermore, the vulcanizing agent is one of dicumyl peroxide, tert-butyl cumyl peroxide, and benzoyl peroxide.

[0020] Furthermore, the temperatures of each heating zone from the feed port to the die head in the twin-screw extruder are set sequentially as follows: 140℃, 200℃, 200℃, 190℃, 190℃, 180℃, 180℃, 160℃, 160℃, 150℃, 150℃, and the rotation speed is 300~500rpm.

[0021] Furthermore, the components of the high-flow dynamic vulcanized elastomer are as follows, by weight:

[0022] EPDM 20 ~ 35 copies

[0023] Ultra-high melt index, low styrene content SEBS, 15-25 parts

[0024] 5-10 parts of high-viscosity polypropylene

[0025] 10-20 parts of high melt index polypropylene

[0026] 15-30 parts mineral oil

[0027] Crosslinking agent 0.5 to 3 parts

[0028] Vulcanizing agent 1 to 5 parts

[0029] Antioxidant 0.1 ~ 0.4 parts

[0030] Silicon-based lubricant: 0.5 to 2 parts.

[0031] The beneficial effects of this application are:

[0032] This application introduces ultra-high melt flow index (UMI) low-styrene content polystyrene rubber and high melt flow index polypropylene into a vulcanizing masterbatch during the EPDM mixing stage. Then, by adding high-viscosity polypropylene during the vulcanization stage, it effectively improves the flowability and moldability of dynamically vulcanized thermoplastic elastomers (TPVs) while maintaining excellent mechanical properties, making them suitable for the processing requirements of thin-walled products. Specifically, the UMI low-styrene content polystyrene rubber is compatible with EPDM rubber during the mixing stage, improving the flowability of the rubber phase without affecting the phase inversion of EPDM during dynamic vulcanization. This phase inversion results in good elasticity and weather resistance for the TPV. While high melt flow index polypropylene is introduced during the EPDM mixing stage to form a highly mobile phase, its low viscosity prevents limited phase inversion during dynamic vulcanization. Therefore, using high-viscosity polypropylene during dynamic vulcanization allows for better phase inversion between the EPDM and polypropylene phases, forming a "sea-island" structure.

[0033] This application utilizes high-viscosity mineral oil to further improve the system's fluidity and processability, as well as its mechanical properties. Specifically, high-viscosity mineral oil exhibits superior compatibility with EPDM and SEBS rubber phases, enabling uniform bulk swelling of the rubber phase during the internal mixing process. This fully disentangles the entanglement of rubber molecular chains, fundamentally reducing the flow resistance of the rubber phase. Compared to the surface-wetting plasticization of low-viscosity mineral oil, its plasticizing and resistance-reducing effect on the rubber phase is more thorough and durable. Furthermore, due to the high degree of molecular chain entanglement and strong binding force with rubber, high-viscosity mineral oil exhibits no migration or precipitation during subsequent internal mixing heating and twin-screw high-shear vulcanization processes. This maintains the low-viscosity viscous flow stability of the rubber phase, preventing viscosity rebound caused by the loss of the low-viscosity mineral oil phase. This ensures stable system fluidity throughout the processing, guaranteeing uniform filling of thin-walled mold cavities without material shortages or shrinkage marks. Furthermore, due to the strict phase selectivity of high-viscosity mineral oil, it is only compatible with the rubber phase and does not penetrate into the continuous polypropylene phase. This fully leverages its plasticizing and drag-reducing effect on the rubber phase without interfering with the flow advantages of high melt index polypropylene, forming a synergistic effect of "low-resistance dispersion of the rubber phase + low-resistance flow of the polypropylene phase". At the same time, it forms an internal and external dual lubrication system with silicone-based lubricants, further reducing melt shear resistance. Ultimately, the melt flow rate of the system is significantly better than that of conventional low-viscosity mineral oil systems, making it suitable for the high-flow processing requirements of thin-walled products. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. In the description of this application, the experimental methods, unless otherwise specified, are conventional methods; the reagents and materials, unless otherwise specified, are all commercially available.

[0035] The following disclosure provides many different implementations or examples for carrying out this application. To simplify the disclosure of this application, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the scope of this application. Those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0036] The sources of the main raw materials in the following embodiments and comparative examples of the present invention are as follows:

[0037] EPDM grade 3072, purchased from Mitsui, Japan;

[0038] The mineral oil, grade P500, was purchased from Xiamen Kunrun and has a viscosity of 98 mmHg at 40°C.2 / s;

[0039] The ultra-high melt flow index (MFR) and low styrene content SEBS grade 1648 was purchased from Kraton, USA. It has a melt flow index (MFR) of 220 g / 10 min at 230℃ × 2.16 kg and a styrene content of 22%.

[0040] The standard styrene content SEBS grade is 6151, purchased from TSRC. It does not flow without oil filling and cannot be processed, with a styrene content of 32%.

[0041] The high melt flow index polypropylene grade was BX3920, purchased from SK, with a melt flow index (MFR) of 120 g / 10 min at 230℃ × 2.16 kg.

[0042] The high-viscosity polypropylene grade B1101 was purchased from Formosa Chemicals & Fibre, and its melt flow index (MFR) was 0.4 g / 10min at 230℃ × 2.16 kg.

[0043] Triallyl isocyanate (TAIC) was purchased from Maclean's.

[0044] N,N-m-phenylbismaleimide HVA-2 was purchased from Suqian Huaxing;

[0045] The hindered phenolic antioxidant was Ciba 1010, purchased from BASF.

[0046] The sulfur ester antioxidant, brand name DLTDP, was purchased from Saint-Lecter.

[0047] The phenyl silicone oil, grade SIC 6422, was purchased from Guangzhou Sloco.

[0048] The alkyl silicone wax, grade SIC 6061P, was purchased from Guangzhou Sloco.

[0049] Dicumyl peroxide (DCP) was purchased from Merck.

[0050] Benzoyl peroxide (BPO) was purchased from Merck.

[0051] The testing methods used in the performance testing of the corresponding products in the various embodiments and comparative examples of this invention are as follows:

[0052] The tensile strength of the material was tested using a universal testing machine.

[0053] Tensile strength was determined according to ISO 37 standard, using type I specimens, at a test speed of 500 mm / min;

[0054] The melt flow index (MFR) test standard is ISO 1133-1, and the test conditions are 230℃ × 2.16kg;

[0055] The hardness test standard is ISO 48-4, with a reading of 15 seconds.

[0056] Example 1

[0057] A method for preparing a high-flow dynamic vulcanized elastomer for thin-walled products includes the following steps:

[0058] Weigh each component according to the following parts by weight:

[0059] EPDM 25 parts, SEBS with ultra-high melt index and low styrene content 20 parts, high viscosity polypropylene 7 parts, high melt index polypropylene 18 parts, mineral oil 25 parts, triallyl isocyanate 1.5 parts, dicumyl peroxide 2 parts, 1010 hindered phenolic antioxidant 0.1 parts, Saint-Gobain DLTDP thioester antioxidant 0.2 parts, phenyl silicone oil 1.2 parts.

[0060] Weigh out the EPDM and mineral oil and put them into a mixer and mix them at 140°C for 4 minutes.

[0061] Add the weighed ultra-high melt index, low styrene content SEBS to the internal mixer and continue mixing at 120°C for 5 minutes.

[0062] Add the weighed triallyl isocyanate, 1010 hindered phenol antioxidant, Saint-Lecter DLTDP thioester antioxidant and phenyl silicone oil to the internal mixer, and continue to mix at 120°C for 2 minutes.

[0063] Add the weighed high melt index polypropylene to the internal mixer and continue mixing at 160°C for 2 minutes to obtain the preform.

[0064] The preformed material is fed into a single-screw extruder for mixing, grinding, hot cutting, and granulation to obtain vulcanized masterbatch. The temperatures of each heating zone from the feed port to the die head of the single-screw extruder are set as follows: 140℃, 190℃, 190℃, 180℃, 180℃, 170℃, 170℃, 170℃, 170℃, 150℃, 150℃, and the rotation speed is 300 rpm.

[0065] The vulcanized masterbatch, weighed high-viscosity polypropylene and dicumyl peroxide are mixed evenly to obtain a mixture.

[0066] The high-flow dynamic vulcanized thermoplastic elastomer can be obtained by extruding and granulating the mixture in a twin-screw extruder. The temperatures of the heating zones from the feed inlet to the die head in the twin-screw extruder are set sequentially as follows: 140℃, 200℃, 200℃, 190℃, 190℃, 180℃, 180℃, 160℃, 160℃, 150℃, 150℃, with a rotational speed of 350 rpm.

[0067] Example 2

[0068] A method for preparing a high-flow dynamic vulcanized elastomer for thin-walled products includes the following steps:

[0069] Weigh each component according to the following parts by weight:

[0070] EPDM 20 parts, SEBS with ultra-high melt index and low styrene content 25 parts, high viscosity polypropylene 10 parts, high melt index polypropylene 20 parts, mineral oil 20 parts, triallyl isocyanate 1.5 parts, benzoyl peroxide 2.1 parts, hindered phenolic antioxidant 0.1 parts, thioester antioxidant 0.3 parts, alkyl silicone wax 1 part.

[0071] Place the weighed EPDM and mineral oil into a mixer and mix at 150°C for 5 minutes.

[0072] Add the weighed ultra-high melt index, low styrene content SEBS to the internal mixer and continue mixing at 130°C for 7 minutes.

[0073] Add the weighed triallyl isocyanate, hindered phenolic antioxidant, thioester antioxidant and alkyl silicone wax to the internal mixer, and continue to mix at 120°C for 2 minutes.

[0074] Add the weighed high melt index polypropylene to the internal mixer and continue mixing at 160°C for 3 minutes to obtain the preform.

[0075] The preformed material is fed into a single-screw extruder for mixing, grinding, hot cutting, and granulation to obtain vulcanized masterbatch. The temperatures of each heating zone from the feed port to the die head of the single-screw extruder are set as follows: 140℃, 190℃, 190℃, 180℃, 180℃, 170℃, 170℃, 170℃, 170℃, 150℃, 150℃, and the rotation speed is 300 rpm.

[0076] The vulcanized masterbatch, weighed high-viscosity polypropylene, and benzoyl peroxide are mixed evenly to obtain a mixture.

[0077] The high-flow dynamic vulcanized thermoplastic elastomer can be obtained by extruding and granulating the mixture in a twin-screw extruder. The temperatures of the heating zones from the feed inlet to the die head in the twin-screw extruder are set sequentially as follows: 140℃, 200℃, 200℃, 190℃, 190℃, 180℃, 180℃, 160℃, 160℃, 150℃, 150℃, with a rotational speed of 350 rpm.

[0078] Example 3

[0079] A method for preparing a high-flow dynamic vulcanized elastomer for thin-walled products includes the following steps:

[0080] Weigh each component according to the following parts by weight:

[0081] EPDM 35 parts, SEBS with ultra-high melt index and low styrene content 15 parts, high viscosity polypropylene 10 parts, high melt index polypropylene 12 parts, mineral oil 22 parts, triallyl isocyanate 1.2 parts, dicumyl peroxide 3 parts, 1010 hindered phenolic antioxidant 0.1 parts, Saint-Gobain DLTDP thioester antioxidant 0.2 parts, phenyl silicone oil 1.5 parts.

[0082] Weigh out the EPDM and mineral oil and put them into a mixer and mix them at 140°C for 4 minutes.

[0083] Add the weighed ultra-high melt index, low styrene content SEBS to the internal mixer and continue mixing at 150°C for 5 minutes.

[0084] Add the weighed triallyl isocyanate, hindered phenolic antioxidant, thioester antioxidant and phenyl silicone oil to the internal mixer, and continue to mix at 110°C for 2 minutes.

[0085] Add the weighed high melt index polypropylene to the internal mixer and continue mixing at 165°C for 3 minutes to obtain the preform.

[0086] The preformed material is fed into a single-screw extruder for mixing, grinding, hot cutting, and granulation to obtain vulcanized masterbatch. The temperatures of each heating zone from the feed port to the die head of the single-screw extruder are set as follows: 140℃, 190℃, 190℃, 180℃, 180℃, 170℃, 170℃, 170℃, 170℃, 150℃, 150℃, and the rotation speed is 300 rpm.

[0087] The vulcanized masterbatch, weighed high-viscosity polypropylene and dicumyl peroxide are mixed evenly to obtain a mixture.

[0088] The high-flow dynamic vulcanized thermoplastic elastomer can be obtained by extruding and granulating the mixture in a twin-screw extruder. The temperatures of the heating zones from the feed inlet to the die head in the twin-screw extruder are set sequentially as follows: 140℃, 200℃, 200℃, 190℃, 190℃, 180℃, 180℃, 160℃, 160℃, 150℃, 150℃, with a rotational speed of 350 rpm.

[0089] Comparative Example 1

[0090] Commercially available Celanese TPV 201-73.

[0091] Comparative Example 2

[0092] A method for preparing a dynamically vulcanized thermoplastic elastomer includes the following steps:

[0093] Weigh each component according to the following parts by weight:

[0094] EPDM 48 parts, high viscosity polypropylene 25 parts, mineral oil 22 parts, triallyl isocyanate 1.5 parts, dicumyl peroxide 2 parts, hindered phenolic antioxidant 0.1 parts, thioester antioxidant 0.2 parts, phenyl silicone oil 1.2 parts.

[0095] Weigh out the EPDM and mineral oil and put them into a mixer and mix them at 140°C for 4 minutes.

[0096] Add the weighed triallyl isocyanate, hindered phenolic antioxidant, thioester antioxidant and phenyl silicone oil to the internal mixer, and continue to internally mix at 120°C for 2 minutes to obtain the preform.

[0097] The preformed material is fed into a single-screw extruder for mixing, grinding, hot cutting, and granulation to obtain vulcanized masterbatch. The temperatures of each heating zone from the feed port to the die head of the single-screw extruder are set as follows: 140℃, 190℃, 190℃, 180℃, 180℃, 170℃, 170℃, 170℃, 170℃, 150℃, 150℃, and the rotation speed is 300 rpm.

[0098] The vulcanized masterbatch, weighed high-viscosity polypropylene and dicumyl peroxide are mixed evenly to obtain a mixture.

[0099] The dynamically vulcanized thermoplastic elastomer can be obtained by extruding and granulating the mixture in a twin-screw extruder. The temperatures of the heating zones from the feed inlet to the die head in the twin-screw extruder are set sequentially as follows: 140℃, 200℃, 200℃, 190℃, 190℃, 180℃, 180℃, 160℃, 160℃, 150℃, 150℃, with a rotational speed of 350 rpm.

[0100] The difference between Comparative Example 2 and Example 1 is that it does not contain ultra-high melt index, low styrene content SEBS and high melt index polypropylene.

[0101] Comparative Example 3

[0102] A method for preparing a dynamically vulcanized thermoplastic elastomer includes the following steps:

[0103] Weigh each component according to the following parts by weight:

[0104] EPDM 45 parts, high viscosity polypropylene 8 parts, mineral oil 22 parts, high melt index polypropylene 20 parts, triallyl isocyanate 1.5 parts, dicumyl peroxide 2 parts, hindered phenolic antioxidant 0.1 parts, thioester antioxidant 0.2 parts, phenyl silicone oil 1.2 parts.

[0105] Weigh out the EPDM and mineral oil and put them into a mixer and mix them at 140°C for 4 minutes.

[0106] Add the weighed triallyl isocyanate, hindered phenolic antioxidant, thioester antioxidant and phenyl silicone oil to the internal mixer, and continue to mix at 120°C for 2 minutes.

[0107] Add the weighed high melt index polypropylene to the internal mixer and continue mixing at 160°C for 2 minutes to obtain the preform.

[0108] The preformed material is fed into a single-screw extruder for mixing, grinding, hot cutting, and granulation to obtain vulcanized masterbatch. The temperatures of each heating zone from the feed port to the die head of the single-screw extruder are set as follows: 140℃, 190℃, 190℃, 180℃, 180℃, 170℃, 170℃, 170℃, 170℃, 150℃, 150℃, and the rotation speed is 300 rpm.

[0109] The vulcanized masterbatch, weighed high-viscosity polypropylene and dicumyl peroxide are mixed evenly to obtain a mixture.

[0110] The dynamically vulcanized thermoplastic elastomer can be obtained by extruding and granulating the mixture in a twin-screw extruder. The temperatures of the heating zones from the feed inlet to the die head in the twin-screw extruder are set sequentially as follows: 140℃, 200℃, 200℃, 190℃, 190℃, 180℃, 180℃, 160℃, 160℃, 150℃, 150℃, with a rotational speed of 350 rpm.

[0111] The difference between Comparative Example 3 and Example 1 is that no ultra-high melt index, low styrene content SEBS was added.

[0112] Comparative Example 4

[0113] A method for preparing a dynamically vulcanized thermoplastic elastomer includes the following steps:

[0114] Weigh each component according to the following parts by weight:

[0115] EPDM 25 parts, SEBS with conventional styrene content 20 parts, high viscosity polypropylene 7 parts, high melt index polypropylene 18 parts, mineral oil 25 parts, triallyl isocyanate 1.5 parts, dicumyl peroxide 2 parts, hindered phenolic antioxidant 0.1 parts, thioester antioxidant 0.2 parts, phenyl silicone oil 1.2 parts.

[0116] Weigh out the EPDM and mineral oil and put them into a mixer and mix them at 140°C for 4 minutes.

[0117] Add the weighed amount of SEBS with conventional styrene content to the internal mixer and continue mixing at 120°C for 5 minutes;

[0118] Add the weighed triallyl isocyanate, hindered phenolic antioxidant, thioester antioxidant and phenyl silicone oil to the internal mixer, and continue to mix at 120°C for 2 minutes.

[0119] Add the weighed high melt index polypropylene to the internal mixer and continue mixing at 160°C for 2 minutes to obtain the preform.

[0120] The preformed material is fed into a single-screw extruder for mixing, grinding, hot cutting, and granulation to obtain vulcanized masterbatch. The temperatures of each heating zone from the feed port to the die head of the single-screw extruder are set as follows: 140℃, 190℃, 190℃, 180℃, 180℃, 170℃, 170℃, 170℃, 170℃, 150℃, 150℃, and the rotation speed is 300 rpm.

[0121] The vulcanized masterbatch, weighed high-viscosity polypropylene and dicumyl peroxide are mixed evenly to obtain a mixture.

[0122] The dynamically vulcanized thermoplastic elastomer can be obtained by extruding and granulating the mixture in a twin-screw extruder. The temperatures of the heating zones from the feed inlet to the die head in the twin-screw extruder are set sequentially as follows: 140℃, 200℃, 200℃, 190℃, 190℃, 180℃, 180℃, 160℃, 160℃, 150℃, 150℃, with a rotational speed of 350 rpm.

[0123] The difference between Comparative Example 4 and Example 1 is that the ultra-high melt index, low styrene content SEBS is replaced with conventional styrene content SEBS.

[0124] Performance testing

[0125] To better verify the performance of the dynamically vulcanized thermoplastic elastomers obtained in the above embodiments and comparative examples, the dynamically vulcanized thermoplastic elastomer samples obtained in Examples 1-3 and Comparative Examples 1-4 were injection molded into 90mm×90mm×2mm pieces for testing the hardness, tensile strength, and hot air aging of the samples obtained in each embodiment and comparative example. After the sample pieces were prepared, they were placed at 23℃ for 24 hours before testing. The test environment temperature was 23℃ and the relative humidity was 50%. The test results of each embodiment and comparative example are shown in Table 1 below:

[0126] Table 1 Performance test results of samples obtained from each embodiment and comparative example

[0127] ;

[0128] As can be seen from the test results of Examples 1-3 in Table 1 above, the dynamically vulcanized thermoplastic elastomers prepared by the method of this application have excellent flowability and weather resistance, and can be formulated to produce different hardness levels, exhibiting a good soft touch. Comparative Example 1 uses a common TPV material on the market with a melt index of only 0.3 g / 10 min; Comparative Example 2 does not introduce ultra-high melt index low styrene content SEBS and high melt index polypropylene, with a melt index of only 4.4 g / 10 min, which is within the normal range; Comparative Example 3 does not introduce ultra-high melt index low styrene content SEBS, and Comparative Example 4 replaces ultra-high melt index low styrene content SEBS with conventional styrene content SEBS. In Comparative Examples 3 and 4, while the flowability decreased, the hot air aging performance at 125℃×504Hr also showed a significant decrease, verifying that the ultra-high melt index low styrene content SEBS formed micro-crosslinked regions.

[0129] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0130] The preparation method of a high-flow dynamic vulcanized elastomer for thin-walled products provided in the embodiments of this application has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for preparing a high-flow dynamic vulcanized elastomer for thin-walled products, characterized in that, The components of the high-flow dynamic vulcanized elastomer, by weight, are as follows: EPDM 20-35 parts, ultra-high melt index low styrene content SEBS 15-25 parts, high viscosity polypropylene 5-10 parts, high melt index polypropylene 10-20 parts, mineral oil 15-30 parts, crosslinking agent 0.5-3 parts, vulcanizing agent 1-5 parts, antioxidant 0.1-0.4 parts, and silicone-based lubricant 0.5-2 parts. The preparation method includes the following steps: placing EPDM and mineral oil in a mixer and mixing at 100℃-150℃ for 2-5 minutes. The mineral oil is a high viscosity mineral oil with a viscosity greater than 90 mmHg at 40℃. 2 / s; Add ultra-high melt index, low styrene content SEBS to the internal mixer and continue mixing at 100℃~150℃ for 4~7 minutes; the ultra-high melt index, low styrene content SEBS has a melt index (MFR) > 150g / 10min at 230℃×2.16kg and a styrene content of 15%~25%; Add a crosslinking agent, antioxidant, and silicone-based lubricant to the internal mixer and continue mixing at 100℃~150℃ for 2~3 minutes; Add to the internal mixer... High melt flow index polypropylene is mixed at 160℃~165℃ for 2~3 minutes to obtain a preform; the high melt flow index polypropylene has a melt flow rate (MFR) > 100 g / 10 min at 230℃×2.16 kg; the preform is then placed in a single-screw extruder for mixing, grinding, and hot-cutting granulation to obtain a vulcanizing masterbatch; the vulcanizing masterbatch, high viscosity polypropylene, and vulcanizing agent are mixed evenly to obtain a mixture; the high viscosity polypropylene has a melt flow rate (MFR) < 1.5 g / 10 min at 230℃×2.16 kg; the mixture is then placed in a twin-screw extruder for extrusion granulation to obtain a high flow dynamic vulcanizing thermoplastic elastomer, the high flow dynamic vulcanizing thermoplastic elastomer having a melt flow rate (MFR) > 100 g / 10 min at 230℃×2.16 kg.

2. The method for preparing a high-flow dynamic vulcanized elastomer for thin-walled products as described in claim 1, characterized in that: The crosslinking agent is one of triallyl isocyanate and N,N-m-phenylbismaleimide.

3. The method for preparing a high-flow dynamic vulcanized elastomer for thin-walled products as described in claim 1, characterized in that: The antioxidant includes a primary antioxidant and a secondary antioxidant, and the mass ratio of the primary antioxidant to the secondary antioxidant is (1:1) to (1:3).

4. The method for preparing a high-flow dynamic vulcanized elastomer for thin-walled products as described in claim 3, characterized in that: The primary antioxidant is either a hindered phenolic antioxidant or a hindered amine antioxidant.

5. The method for preparing a high-flow dynamic vulcanized elastomer for thin-walled products as described in claim 3, characterized in that: The auxiliary antioxidant is one of phosphite antioxidants, thioester antioxidants, or thiodipropionate antioxidants.

6. The method for preparing a high-flow dynamic vulcanized elastomer for thin-walled products as described in claim 1, characterized in that: The silicone-based lubricant is one of silicone, alkyl silicone wax, or phenyl silicone oil.

7. The method for preparing a high-flow dynamic vulcanized elastomer for thin-walled products as described in claim 1, characterized in that: The vulcanizing agent is one of dicumyl peroxide, tert-butyl cumyl peroxide, and benzoyl peroxide.

8. The method for preparing a high-flow dynamic vulcanized elastomer for thin-walled products as described in claim 1, characterized in that: The temperatures of each heating zone from the feed inlet to the die head in the twin-screw extruder are set sequentially as follows: 140℃, 200℃, 200℃, 190℃, 190℃, 180℃, 180℃, 160℃, 160℃, 150℃, 150℃, and the rotation speed is 300~500rpm.