A soft thermoplastic elastomer composition and a preparation method thereof

Abstract

This application relates to the technical field of polymer materials, and particularly relates to a soft thermoplastic elastomer composition and a preparation method thereof. A soft thermoplastic elastomer composition comprises the following components in parts by weight: 20 parts of SEBS, 40 - 60 parts of EVM, 10 - 15 parts of compatibilizer, 10 - 20 parts of white oil, 0 - 15 parts of filler, 0.1 - 1 part of lubricant, 0.5 part of antioxidant, 0.5 part of anti-UV agent, and 0.5 - 3 parts of colorant. The compatibilizer comprises SEBS-g-MAH and POE-g-MAH. This application uses SEBS-g-MAH and POE-g-MAH as compatibilizers and combines them with other components such as SEBS and EVM to prepare a thermoplastic elastomer composition, which can effectively improve the adhesion performance while maintaining its elasticity, and thus is more suitable for preparing the end sealing ring of a PVC corrugated hose.

Description

Technical Field

[0001] This application relates to the technical field of polymer materials, and particularly relates to a soft thermoplastic elastomer composition and a preparation method thereof. Background Art

[0002] PVC corrugated hoses are widely used in household appliances such as vacuum cleaners and washing machines due to their good flexibility and corrosion resistance. In order to ensure a tight and stable connection between the PVC corrugated hose and other parts of the device, the use of a sealing ring at the end of the PVC corrugated hose is particularly important.

[0003] Currently, the mainstream injection molding material for the sealing ring at the end of PVC corrugated hoses in the market is soft PVC. Since both soft PVC and PVC corrugated hoses are PVC materials generated by the polymerization reaction of vinyl chloride monomers, soft PVC and PVC corrugated hoses have similar chemical structures and physical properties, with good compatibility and a certain bonding effect. During actual use, due to the strongly polar chlorine atoms in the PVC molecular chain, there are strong intermolecular forces between the PVC molecular chains, which makes the PVC material rigid. Although soft PVC is modified by adding plasticizers, soft PVC still retains a certain degree of rigidity, so the elasticity of soft PVC is relatively poor, and it is difficult to maintain a tight sealing state during long-term use or under greater pressure.

[0004] In view of the above-mentioned prior art, the inventor believes that thermoplastic elastomers have excellent elasticity and flexibility, which makes them not easily lose their elastic effect due to deformation, and they are a good alternative material for soft PVC. However, since thermoplastic elastomers are copolymerized from multiple monomers, their molecular chains contain non-polar or weakly polar segments, and the number and distribution of polar functional groups are relatively uneven, resulting in the overall non-polar or weakly polar nature of thermoplastic elastomers. The molecular chain of PVC contains strongly polar chlorine atoms, which makes its molecular chain show strong polarity. The polarity difference between the two is large. According to the principle of like dissolves like, the intermolecular force between the two is weak, resulting in poor bonding performance between the thermoplastic elastomer and PVC. Summary of the Invention

[0005] In order to solve the problem of poor bonding performance between the thermoplastic elastomer and PVC, this application provides a soft thermoplastic elastomer composition and a preparation method thereof, and this soft thermoplastic elastomer composition has excellent bonding performance with PVC.

[0006] In the first aspect, this application provides a soft thermoplastic elastomer composition, adopting the following technical solution:

[0007] A soft thermoplastic elastomer composition, comprising the following components in parts by weight: 20 parts of SEBS, 40 - 60 parts of EVM, 10 - 15 parts of compatibilizer, 10 - 20 parts of white oil, 0 - 15 parts of filler, 0.1 - 1 part of lubricant, 0.5 part of antioxidant, 0.5 part of anti-UV agent, 0.5 - 3 parts of colorant, wherein the compatibilizer comprises SEBS-g-MAH and POE-g-MAH.

[0008] By adopting the above technical solution, SEBS is a thermoplastic elastomer with a special structure. Its molecular chain contains a hard segment (styrene block) and a soft segment (ethylene-butene block), and the soft segment endows SEBS with good elasticity; ethylene-vinyl acetate rubber (EVM) is a polar rubber, and its molecular chain contains vinyl acetate groups. The vinyl acetate groups are similar in polarity to those of PVC, which can increase the polar interaction force between EVM and PVC, thereby improving the interfacial compatibility; SEBS-g-MAH is obtained by grafting maleic anhydride onto the SEBS molecular chain. Maleic anhydride is a functional group with strong polarity, which can form hydrogen bonds or dipole-dipole interactions with the chlorine atoms in the PVC molecular chain, thereby enhancing the interfacial compatibility between SEBS and PVC. At the same time, the similar hydrocarbon main chains between the POE chain and EVM make POE-g-MAH and EVM also compatible with each other.

[0009] When the molten thermoplastic elastomer composition contacts the end of the PVC corrugated hose, the PVC corrugated hose receives heat and shows a slight melting phenomenon; the vinyl acetate groups in EVM can form polar interactions with the chlorine atoms in the PVC molecular chain, increasing the intermolecular force at the interface; at the same time, SEBS-g-MAH can act as a "bridge" to enhance the interaction between SEBS and PVC; POE-g-MAH can act as a "bridge" to further enhance the interaction between EVM and PVC, significantly improving the bonding strength between them.

[0010] Optionally, the mass ratio of SEBS to SEBS-g-MAH is 20:8 - 10.

[0011] By adopting the above technical solution, when the content of SEBS-g-MAH is too low, the effect of SEBS-g-MAH acting as a "bridge" to enhance the interaction between SEBS and PVC is weak, and the improvement effect on the bonding performance is not obvious; while when the content of SEBS-g-MAH is too high, the content of SEBS-g-MAH is already sufficient to achieve the connection between SEBS and PVC, and there is no need to continue adding; therefore, after a large amount of research and experimental verification by the applicant, it is finally determined that the mass ratio of SEBS to SEBS-g-MAH in this application is preferably the above-mentioned ratio.

[0012] Optionally, the compatibilizer further includes catechol.

[0013] By adopting the above technical solution, the hydroxyl groups in the catechol molecular structure can undergo an esterification reaction with the anhydride groups in SEBS-g-MAH and POE-g-MAH to form ester bonds, realizing the connection between catechol and maleic anhydride. At the same time, due to the structural similarity between the benzene ring in catechol and the styrene block of SEBS, the compatibility between catechol and SEBS is good; meanwhile, the hydroxyl groups in the catechol molecular structure can absorb the hydrogen chloride gas generated during the degradation of PVC, thereby delaying the degradation of PVC.

[0014] Optionally, the mass ratio of SEBS to catechol is 20:0.1 - 0.3.

[0015] By adopting the above technical solution, when the content of catechol is too low, the number of hydroxyl groups in the thermoplastic elastomer composition is limited and cannot fully react with the anhydride groups in SEBS-g-MAH and POE-g-MAH, resulting in poor dispersion of catechol in SEBS and having a weak impact on the compatibility of the thermoplastic elastomer composition. At the same time, the inhibitory effect of the hydroxyl groups of catechol molecules on PVC degradation is not obvious;

[0016] Although catechol can improve the compatibility between SEBS and other components in the thermoplastic elastomer composition, when the content of catechol is too high, the introduced hydroxyl groups in the thermoplastic elastomer composition are already sufficient to fully react with the anhydride groups, and excessive catechol will also reduce the economy of the thermoplastic elastomer composition; for this reason, after a large number of studies and experimental verifications, the applicant finally determined that the mass ratio of SEBS to catechol in this application is preferably as above.

[0017] Optionally, the VA content of the EVM is in the range of 50 - 65 wt%.

[0018] By adopting the above technical solution, when the vinyl acetate (VA) content in EVM is relatively high, the polar VA side groups in the EVM molecular chain endow the material with good elasticity and flexibility; as the VA content increases, the polarity in the EVM molecular chain increases, and due to the similar polarity between EVM and PVC, the compatibility between EVM and PVC is further improved; however, excessive VA will destroy the crystalline regions formed by the polyethylene segments, resulting in a decrease in crystallinity and thus a decline in the elastic properties of EVM; for this reason, after a large number of studies and experimental verifications, the applicant finally determined that the VA content of the EVM in this application is preferably within the above range.

[0019] Optionally, the filler is activated calcium carbonate.

[0020] By adopting the above technical solution, as an inorganic filler, the surface of the activated calcium carbonate is modified to carry active groups such as hydroxyl and carboxyl groups. These active groups, such as hydroxyl, can form hydrogen bonds with the maleic anhydride groups in the compatibilizer, thereby enhancing the compatibility between the filler and each component of the thermoplastic elastomer composition. The long hydrocarbon chains on the surface of the activated calcium carbonate particles may also undergo physical entanglement with the soft segment part of the SEBS molecular chain. At the same time, the polar groups such as hydroxyl and carboxyl groups on the surface of the activated calcium carbonate particles can form hydrogen bonds with the polar electron clouds near the polar chlorine atoms of the PVC molecules, thereby significantly improving the binding force between the calcium carbonate and the PVC molecular chain and further enhancing the adhesion performance between the thermoplastic elastomer composition and the PVC corrugated hose.

[0021] Optionally, the particle size of the activated calcium carbonate is in the range of 2000 - 2500 mesh.

[0022] By adopting the above technical solution, when the particle size of the activated calcium carbonate is small, it can be more uniformly dispersed in the thermoplastic elastomer composition, reducing the stress concentration points caused by particle agglomeration, which helps to improve the overall uniformity and compatibility of the thermoplastic elastomer composition. At the same time, the uniform dispersion of the activated calcium carbonate also helps to form a denser interfacial layer between the thermoplastic elastomer composition and PVC, reducing the voids and defects at the interface and further improving the tightness and stability of the adhesion.

[0023] However, when the particle size of the activated calcium carbonate is too small, it may cause agglomeration of the activated calcium carbonate in the thermoplastic elastomer composition, instead reducing the overall uniformity and compatibility of the thermoplastic elastomer composition. Therefore, after a large amount of research and experimental verification by the applicant, it is finally determined that the particle size of the activated calcium carbonate in this application is preferably within the above range.

[0024] In the second aspect, this application provides a preparation method of a soft thermoplastic elastomer composition, adopting the following technical solution:

[0025] A preparation method of a soft thermoplastic elastomer composition for preparing the above soft thermoplastic elastomer composition, including the following steps: adding the formulated amount of SEBS, compatibilizer, EVM and other processing aids into a mixer, mixing evenly, then accurately metering through a loss-in-weight scale, and then feeding into a twin-screw extruder for extrusion granulation, and obtaining the soft thermoplastic elastomer composition after pelletizing.

[0026] By adopting the above technical solution, this application prepares the soft thermoplastic elastomer composition by a mixing method. This preparation method is simple, accurately measures the content of each component, and thus enables the prepared soft thermoplastic elastomer composition to have excellent adhesion performance with PVC.

[0027] Optionally, the main machine speed of the twin-screw extruder is 400 - 600 rpm.

[0028] By adopting the above technical solution, the twin-screw extruder can effectively mix SEBS, compatibilizer, EVM and other processing aids through its special screw design and speed control; when the speed is too low, the mixing of each component may be uneven, and when the speed is too high, the structure of the material may be damaged due to excessive shearing.

[0029] Optionally, the granulation temperature range of the twin-screw extruder is 160 - 180 °C.

[0030] By adopting the above technical solution, temperature is an important parameter in plastic processing, which directly affects the melting state, fluidity and viscosity of the material. When the temperature is too low, SEBS-g-MAH cannot be fully melted, making it difficult to fully exert the effect of the compatibilizer, resulting in uneven mixing and even problems such as irregular particles and breakage;

[0031] When the temperature is too high, the polymer is prone to thermal degradation and oxidation reactions, leading to problems such as molecular chain breakage and performance decline; for the compatibilizer, too high a temperature will cause its decomposition, affecting its bonding effect with PVC.

[0032] In summary, the present application has the following beneficial effects:

[0033] 1. The present application uses SEBS-g-MAH and POE-g-MAH as compatibilizers in combination with other components such as SEBS and EVM to prepare a thermoplastic elastomer composition, which can effectively improve the bonding performance while maintaining its elasticity, and is thus more suitable for preparing the end seal ring of a PVC corrugated hose;

[0034] 2. Catechol is added to the compatibilizer in the present application, which can form an ester bond with the maleic anhydride group in the compatibilizer and thus be evenly dispersed in SEBS, further improving the compatibility between SEBS and other components. At the same time, catechol can also absorb hydrogen chloride gas and delay the degradation of PVC. Detailed implementation mode

[0035] The raw materials in the present application include the following parts:

[0036] SEBS: A commercially available product is used. In the present application, SEBS of Shanghai Baling Petrochemical Co., Ltd., model YH-502T is taken as an example for illustration;

[0037] EVM: This application takes Levapren 450 (VA content 45 wt%), Levapren 500 (VA content 50 wt%), Levapren 600 (VA content 60 wt%), Levapren 650 VP (VA content 65 wt%), Levapren 700 (VA content 70 wt%) produced by LANXESS High Performance Elastomers (Changzhou) Co., Ltd. as examples for illustration;

[0038] SEBS-g-MAH: Commercially available product with the grade of Taipol-7126 is used;

[0039] POE-g-MAH: Commercially available product with the grade of M2265 is used;

[0040] Catechol: Commercially available product with the CAS number of 120 - 80 - 9 is used;

[0041] Filler: This application takes active calcium carbonate with the grades of Js-1500 (particle size 1500 mesh), Js-2000 (particle size 2000 mesh), HX-2500 (particle size 2500 mesh), BR-3000 (particle size 3000 mesh), silica powder with the grade of FSCJZX-2000, and talcum powder with the grade of KH-206 as examples for illustration;

[0042] White oil: Commercially available product with the CAS number of 8042 - 47 - 5 is used in this application;

[0043] Lubricant: Polyethylene waxes, fatty acids and their salts, etc. are all acceptable. This application takes polyethylene wax, and commercially available product with the CAS number of 9002 - 88 - 4 is used as an example for illustration;

[0044] Antioxidant: This application takes antioxidant 1010 as an example for illustration;

[0045] UV-resistant agent: This application takes UV-resistant agent UV-944 as an example for illustration;

[0046] Colorant: Carbon black, color powder, etc. are all acceptable. This application takes carbon black, and commercially available product with the CAS number of 1333 - 86 - 4 is used as an example for illustration;

[0047] The following further elaborates this application in combination with examples and comparative examples.

[0048] Example 1

[0049] A preparation method of a soft thermoplastic elastomer composition, comprising the following steps:

[0050] Add 20 kg of SEBS, 50 kg of EVM (Levapren600), 5 kg of SEBS-g-MAH, 8 kg of POE-g-MAH, 8 kg of active calcium carbonate (Js-2000), 15 kg of white oil, 0.5 kg of lubricant, 0.5 kg of antioxidant, 0.5 kg of anti-UV agent and 1.5 kg of colorant into a high-speed mixer and mix at 600 rpm for 10 min to obtain a uniform mixture.

[0051] Add the mixture into a twin-screw extruder for melt mixing, and then extrude the molten material. The main machine speed of the twin-screw extruder is 500 rpm, and the extrusion temperature is 170 °C. After the extruded molten material is cooled and pelletized, a soft thermoplastic elastomer composition is obtained.

[0052] Example 2-3

[0053] Based on the preparation method of Example 1, the content of each component of the soft thermoplastic elastomer composition in Example 2-3 was adjusted, and the specific adjustment is shown in Table 1.

[0054] Comparative Examples 1-3

[0055] Based on the preparation method of Example 1, the content of each component of the soft thermoplastic elastomer composition in Comparative Examples 1-3 was adjusted, and the specific adjustment is shown in Table 1.

[0056] Table 1 Formulation and performance test table of each component of the soft thermoplastic elastomer composition in Examples 1-3 and Comparative Examples 1-3

[0057]

[0058] Performance detection test

[0059] Prepare samples of the soft thermoplastic elastomer compositions of Examples 1-3 and Comparative Examples 1-3 for analysis. The preparation and testing methods are as follows:

[0060] (1) Tensile strength and elongation at break

[0061] Weigh the above-prepared soft thermoplastic elastomer compositions respectively and put them into a rectangular mold frame with a thickness of 4 mm. Place the mold frame between the upper and lower plates of a rubber flat vulcanizing machine. The temperature of the upper and lower plates is set at 210 °C. After maintaining the pressure at 10 MPa for 5 min, take out the mold frame and let it cool naturally to obtain soft thermoplastic elastomer composition samples with a thickness of 4 mm respectively.

[0062] According to ISO37 standard, test the tensile strength and elongation at break of the soft thermoplastic elastomer compositions provided in Examples 1-3 and Comparative Examples 1-3 of this application. The test results are shown in Table 1. Specimen size: 80mm * 10mm * 4mm, dumbbell shape, tensile speed is 500mm / min.

[0063] (2)PVC Adhesive Peel Strength

[0064] At one end of the surface of a PVC test piece with a thickness of 2mm, within a region with a width of 50mm, evenly apply a layer of silicone oil as a release agent. Place the PVC test piece coated with silicone oil in a rectangular mold frame with a thickness of 3mm. Weigh the soft thermoplastic elastomer compositions prepared above respectively, and inject them on the surface of the test piece. Set the injection temperature at 210°C to make the injection material evenly cover the surface of the test piece, forming an injection layer with a thickness of 1mm. Place the injected test piece in the laboratory environment, adjust the environmental temperature and keep it for 12h, and then cut it into test samples with a specification of 150mm * 10mm.

[0065] Separate the soft thermoplastic elastomer composition samples provided in Examples 1-3 and Comparative Examples 1-3 of this application from the end coated with the release agent. Clamp the samples on both sides of the release agent to the upper and lower fixtures of a universal testing machine respectively. Start the universal testing machine to apply a peeling force until the specimen is damaged. Calculate the ratio of the peeling force to the sample width to obtain the PVC adhesive peel strength. The test results are shown in Table 1.

[0066] Referring to Table 1, SEBS-g-MAH has an impact on the adhesion performance between the soft thermoplastic elastomer composition and PVC. This may be because the SEBS chain and MAH chain of SEBS-g-MAH interact with SEBS and PVC respectively, connecting the two; POE-g-MAH has an impact on the adhesion performance between the soft thermoplastic elastomer composition and PVC. This may be because POE-g-MAH interacts with EVM and PVC respectively, strengthening the connection between the two;

[0067] In addition, by comprehensively comparing Examples 1-3 and Comparative Examples 1-3, it is found that the soft thermoplastic elastomer composition in Example 1 has the best elasticity and adhesion performance with PVC. Therefore, Example 1 is preferred.

[0068] Examples 4-5

[0069] Based on the preparation method of Example 1, adjust the content of SEBS-g-MAH in Examples 4-5. The specific adjustment is shown in Table 2.

[0070] Comparative Examples 4-5

[0071] On the basis of the preparation method of Example 1, the content of SEBS-g-MAH was adjusted for Comparative Examples 4-5, and the specific adjustment is shown in Table 2.

[0072] The soft thermoplastic elastomer compositions of Examples 4-5 and Comparative Examples 4-5 were subjected to the above performance tests, and the test results are shown in Table 2.

[0073] Table 2 Data table of the addition amount of SEBS-g-MAH and performance test of Example 1, Examples 4-5 and Comparative Examples 4-5

[0074]

[0075] Referring to Table 2, by comparing Example 1, Examples 4-5 and Comparative Examples 4-5, it can be seen that as the addition amount of SEBS-g-MAH in the soft thermoplastic elastomer composition increases, the adhesion performance of the soft thermoplastic elastomer composition to PVC is continuously enhanced. This may be because the interaction between SEBS-g-MAH, SEBS and PVC is continuously enhanced with SEBS-g-MAH, improving the compatibility between the soft thermoplastic elastomer composition and PVC. And in Example 1, the interaction between SEBS-g-MAH, SEBS and PVC reached saturation.

[0076] Examples 6-8

[0077] On the basis of the preparation method of Example 1, the content of catechol was adjusted for Examples 6-8, and the specific adjustment is shown in Table 3.

[0078] Comparative Examples 6-7

[0079] On the basis of the preparation method of Example 1, the content of catechol was adjusted for Comparative Examples 6-7, and the specific adjustment is shown in Table 3.

[0080] The soft thermoplastic elastomer compositions of Examples 6-7 and Comparative Examples 6-7 were sampled and analyzed. The preparation and test methods are as follows:

[0081] On one end of the surface of a PVC test piece with a thickness of 2 mm and in a region with a width of 50 mm, a layer of silicone oil was evenly applied as an isolating agent. The PVC test piece coated with silicone oil was placed in a rectangular mold frame with a thickness of 3 mm. The soft thermoplastic elastomer compositions prepared above were weighed respectively and injection molded on the test piece surface. The injection molding temperature was set at 210 °C to make the injection molding material evenly cover the test piece surface, forming an injection molding layer with a thickness of 1 mm. The injection molded test piece was placed in the laboratory environment, and the environmental temperature was adjusted and maintained for 12 h, and then it was cut into test samples with a specification of 150 mm * 10 mm.

[0082] According to the national standard GB / T16422.2-2022, place the above test samples in a xenon lamp aging test chamber. The temperature of the test chamber is set to 60±3°C during illumination and 50±3°C in the dark, and the humidity is set to 50%±5% during illumination and 70%±5% in the dark. The exposure cycle is 8 hours of illumination and 4 hours of darkness. After 48 hours, take samples and conduct the above-mentioned PVC adhesion peel strength test, and calculate the change rate of the PVC adhesion peel strength before and after aging treatment.

[0083] Perform the above performance tests on the soft thermoplastic elastomer compositions of Example 1, Examples 6-7 and Comparative Examples 6-7. The test results are shown in Table 3.

[0084] Table 3 Data table of catechol addition amounts and performance test results of Example 1, Examples 6-8 and Comparative Examples 6-7

[0085]

[0086] Referring to Table 3, by comparing Example 1, Examples 6-8 and Comparative Examples 6-7, it can be seen that as the addition amount of catechol continuously increases, the elastic properties of the soft thermoplastic elastomer and its adhesion performance with PVC show a trend of increasing first and then leveling off. This may be because as the content of catechol continuously increases, catechol continuously reacts with anhydride groups, strengthening the compatibility between the components of the thermoplastic elastomer composition; when the addition amount of catechol exceeds a certain range, the reaction between anhydride groups and catechol is sufficient, and the effect of improving compatibility approaches saturation.

[0087] In addition, as the addition amount of catechol continuously increases, the numerical values of the change rate of the PVC adhesion peel strength of the soft thermoplastic elastomer continuously decrease. This may be because catechol continuously absorbs hydrogen chloride gas generated by PVC degradation, thus delaying the degradation of the PVC injection surface.

[0088] Furthermore, by comprehensively comparing Example 1, Examples 6-8 and Comparative Examples 6-7, it is found that the soft thermoplastic elastomer composition of Example 8 has the best elasticity and adhesion performance with PVC. Therefore, Example 8 is preferred.

[0089] Examples 9-10

[0090] Based on the preparation method of Example 8, in Example 9, change the model of EVM from Levapren600 (VA content 60%) to Levapren500 (VA content 50%).

[0091] Based on the preparation method of Example 8, in Example 10, change the model of EVM from Levapren600 (VA content 60%) to Levapren650VP (VA content 65%).

[0092] Comparative Examples 8 - 9

[0093] Based on the preparation method of Example 8, for Comparative Example 8, the type of EVM was changed from Levapren 600 (VA content 60%) to Levapren 450 (VA content 45%).

[0094] Based on the preparation method of Example 8, for Comparative Example 9, the type of EVM was changed from Levapren 600 (VA content 60%) to Levapren 700 (VA content 70%).

[0095] The soft thermoplastic elastomer compositions of Examples 9 - 10 and Comparative Examples 8 - 9 were subjected to the above performance tests, and the test results are shown in Table 4.

[0096] Table 4 Performance test data of Example 8, Examples 9 - 10 and Comparative Examples 8 - 9

[0097]

[0098] Referring to Table 4, by comparing Example 8, Examples 9 - 10 and Comparative Examples 8 - 9, it can be seen that as the VA content of EVM increases continuously, the tensile strength and elongation at break of the soft thermoplastic elastomer composition first increase and then decrease. This may be because the presence of excessive VA destroys the crystalline regions formed by the polyethylene segments, resulting in a decrease in crystallinity, thus affecting the tensile strength and elongation at break of the soft thermoplastic elastomer composition; at the same time, the adhesion performance of the soft thermoplastic elastomer composition with PVC continuously improves, which may be because the increase in the polar VA side groups in the EVM molecular chain further enhances the compatibility between EVM and PVC.

[0099] Comparative Examples 10 - 11

[0100] Based on the preparation method of Example 8, for Comparative Example 10, the active calcium carbonate was replaced with silicon micropowder.

[0101] Based on the preparation method of Example 8, for Comparative Example 11, the active calcium carbonate was replaced with talc powder.

[0102] The soft thermoplastic elastomer compositions of Comparative Examples 10 - 11 were subjected to the above performance tests, and the test results are shown in Table 5.

[0103] Table 5 Performance test data of Example 8 and Comparative Examples 10 - 11

[0104]

[0105] Referring to Table 5, by comparing Example 8 with Comparative Examples 10 - 11, it can be seen that compared with the soft thermoplastic elastomer composition of Example 1, the elasticity and adhesion properties of the soft thermoplastic elastomer compositions of Comparative Examples 10 - 11 are lower than those of the soft thermoplastic elastomer composition of Example 1. This shows that active calcium carbonate is a preferred filler for the soft thermoplastic elastomer composition.

[0106] Example 11

[0107] Based on the preparation method of Example 8, in Example 11, the grade of active calcium carbonate was changed from Js - 2000 (particle size 2000 mesh) to Hx - 2500 (particle size 2500 mesh).

[0108] Comparative Examples 12 - 13

[0109] Based on the preparation method of Example 8, in Comparative Example 12, the grade of active calcium carbonate was changed from Js - 2000 (particle size 2000 mesh) to Js - 1500 (particle size 1500 mesh).

[0110] Based on the preparation method of Example 8, in Comparative Example 13, the grade of active calcium carbonate was changed from Js - 2000 (particle size 2000 mesh) to BR - 3000 (particle size 3000 mesh).

[0111] The soft thermoplastic elastomer compositions of Example 11 and Comparative Example 12 were subjected to the above performance tests, and the test results are shown in Table 6.

[0112] Table 6 Performance test data table of Example 8, Example 11 and Comparative Examples 12 - 13

[0113]

[0114] Referring to Table 6, by comparing Example 8, Example 11 and Comparative Examples 12 - 13, it can be seen that as the particle size of the active calcium carbonate continuously decreases, the elasticity and adhesion properties of the soft thermoplastic elastomer composition first increase and then decrease. This may be because the active calcium carbonate with a small particle size can be more uniformly dispersed in the soft thermoplastic elastomer, thus strengthening the adhesion effect between the soft thermoplastic elastomer composition and PVC; when the particle size of the active calcium carbonate is less than a certain range, the active calcium carbonate begins to agglomerate in the soft thermoplastic elastomer composition, thus affecting the adhesion performance between the soft thermoplastic elastomer composition and PVC.

[0115] Examples 12 - 13

[0116] Based on the preparation method of Example 1, in Examples 12 - 13, the main machine speed of the twin - screw extruder was adjusted, and the specific adjustment is shown in Table 7.

[0117] Comparative Examples 14 - 15

[0118] On the basis of the preparation method of Example 1, the main machine speed of the twin-screw extruder was adjusted for Comparative Examples 14-15, and the specific adjustments are shown in Table 7.

[0119] The soft thermoplastic elastomer compositions of Examples 12-13 and Comparative Examples 14-15 were subjected to the above performance tests, and the test results are shown in Table 7.

[0120] Table 7 Data table of main machine speed and performance test of Example 1, Examples 12-13 and Comparative Examples 14-15

[0121]

[0122] Referring to Table 7, by comparing Example 1, Examples 12-13 and Comparative Examples 14-15, it can be seen that compared with the soft thermoplastic elastomer compositions of Example 1 and Examples 12-13, the elastic properties and the adhesion properties to PVC of the soft thermoplastic elastomer compositions of Comparative Examples 14-15 are much lower than those of the soft thermoplastic elastomers of Example 1 and Examples 12-13; this may be because when the main machine speed is too slow, the components are not evenly mixed, and when the main machine speed is too high, the structure of the thermoplastic composition is damaged by excessive shearing, resulting in a decrease in the adhesion properties of the thermoplastic elastomer composition to PVC.

[0123] Examples 14-15

[0124] On the basis of the preparation method of Example 1, the extrusion temperature of the twin-screw extruder was adjusted for Examples 14-15, and the specific adjustments are shown in Table 8.

[0125] Comparative Examples 16-17

[0126] On the basis of the preparation method of Example 1, the extrusion temperature of the twin-screw extruder was adjusted for Comparative Examples 16-17, and the specific adjustments are shown in Table 8.

[0127] The soft thermoplastic elastomer compositions of Examples 14-15 and Comparative Examples 16-17 were subjected to the above performance tests, and the test results are shown in Table 8.

[0128] Table 8 Data table of extrusion temperature and performance test of Example 1, Examples 14-15 and Comparative Examples 16-17

[0129]

[0130] Referring to Table 8, by comparing Example 1, Examples 14 - 15 and Comparative Examples 16 - 17, it can be seen that, compared with the soft thermoplastic elastomer compositions of Example 1 and Examples 14 - 15, the adhesion properties of the soft thermoplastic elastomer compositions of Comparative Examples 16 - 17 to PVC are much lower than those of the soft thermoplastic elastomers of Example 1 and Examples 16 - 17.

[0131] This may be because when the extrusion temperature is too low, some components in the soft thermoplastic elastomer composition are not completely melted, resulting in non-uniform mixing among the components; when the extrusion temperature is too high, some components in the soft thermoplastic elastomer composition decompose, thus affecting the elasticity of the soft thermoplastic elastomer composition and its adhesion property to PVC.

[0132] This specific embodiment is only an interpretation of the present application, and it is not a limitation to the present application. Those skilled in the art can make modifications to this embodiment without creative contributions according to needs after reading this specification, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A soft thermoplastic elastomer composition, characterized in that: The invention comprises the following components in parts by weight: 20 parts of SEBS, 40-60 parts of EVM, 10-15 parts of compatibilizer, 10-20 parts of white oil, 0-15 parts of filler, 0.1-1 parts of lubricant, 0.5 parts of antioxidant, 0.5 parts of anti-UV agent and 0.5-3 parts of colorant; The compatibilizer includes SEBS-g-MAH and POE-g-MAH; The VA content of the EVM is in the range of 50-65wt%; The filler is activated calcium carbonate, and the particle size of the activated calcium carbonate is in the range of 2000-2500 mesh; The method for preparing a soft thermoplastic elastomer composition comprises the following steps: Adding the formulated amount of SEBS, EVM, compatibilizer, white oil, filler, lubricant, antioxidant, UV inhibitor, and colorant into a mixer, mixing evenly, accurately measuring with a loss-in-weight scale, and then feeding into a twin-screw extruder for extrusion granulation, and obtaining the soft thermoplastic elastomer composition after pelletizing; The main engine speed of the twin-screw extruder is 400-600rpm; The granulation temperature range of the twin-screw extruder is 160-180°C.

2. The soft thermoplastic elastomer composition according to claim 1, characterized in that: The mass ratio of the SEBS to the SEBS-g-MAH is 20:8-10.

3. The soft thermoplastic elastomer composition according to claim 1, characterized in that: The compatibilizer also includes catechol.

4. The soft thermoplastic elastomer composition according to claim 3, characterized in that: The mass ratio of SEBS to catechol is 20:0.1-0.3.

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