Thermoplastic elastomer composition with hardness changing along with temperature and product thereof

Abstract

The invention provides a thermoplastic elastomer composition with hardness changing along with temperature, which comprises an alpha-olefin copolymer accounting for 23-40 wt% of the total weight of the thermoplastic elastomer composition, and the alpha-olefin copolymer comprises alpha-olefin monomer units with carbon number of 3-10; a first hydrogenated styrene / butadiene block copolymer and a second hydrogenated styrene / butadiene block copolymer, the first hydrogenated styrene / butadiene block copolymer being different from the second hydrogenated styrene / butadiene block copolymer; a non-hydrogenated styrene / isoprene block copolymer; an ethylene-[alpha]-olefin copolymer, the ethylene-[alpha]-olefin copolymer being different from the [alpha]-olefin copolymer; an ethylene vinyl acetate copolymer; and a thermoplastic polyolefin different from the alpha-olefin copolymer and also different from the ethylene-alpha-olefin copolymer wherein the alpha-olefin copolymer is present in a greater amount by weight than the first hydrogenated styrene / butadiene block copolymer, the second hydrogenated styrene / butadiene block copolymer, and the ethylene-alpha-olefin copolymer is present in a greater amount by weight than the first hydrogenated styrene / butadiene block copolymer. And the total weight content of the non-hydrogenated styrene / isoprene block copolymer.

Description

Technical Field

[0001] The present invention relates to a thermoplastic elastomer whose hardness varies with temperature, particularly a thermoplastic elastomer containing a hydrogenated styrene / butadiene block copolymer. Background Art

[0002] Hydrogenated styrene / butadiene block copolymers belong to styrenic thermoplastic elastomers. Compared with other types of thermoplastic elastomers, styrenics have good room-temperature resilience, non-absorbency, softness, and low-temperature toughness. One of the hydrogenated styrene / butadiene blocks, SEBS, is derived from SBS by hydrogenating the unsaturated carbon double bonds in the middle segment of the original SBS to form saturated single bonds, which can enhance weather resistance and high-temperature performance. Hydrogenated styrene / butadiene block copolymers are environmentally friendly and safe. They usually have characteristics such as high strength, oxygen resistance, ozone resistance, ultraviolet resistance, good thermal stability, high service temperature, and are easy to process. They are widely used in mixing, plastic modification, elastic films, and formulating adhesives. In the application of plastic modification, hydrogenated styrene / butadiene block copolymers can be blended and modified with various plastics, significantly improving the comprehensive performance of plastics. Summary of the Invention

[0003] Based on the excellent properties of hydrogenated styrene / butadiene block copolymers, the present invention aims to develop new uses of hydrogenated styrene / butadiene block copolymers in plastic modification. The present invention unexpectedly discovers a thermoplastic elastomer formulation containing a hydrogenated styrene / butadiene block copolymer, which can exhibit the characteristic of hardness varying with temperature. PVC is a material with hardness varying with temperature commonly used in the prior art, but PVC material cannot decompose naturally and will also produce toxic substances when burned. Therefore, the present invention has the advantage of replacing PVC material.

[0004] Through multiple experimental studies, the present invention carefully designs various thermoplastic elastomer formulations, so that its products not only have the characteristic of hardness varying with temperature, but also have slow rebound performance. Especially for products that need to be in contact with the body during use, such as backpacks, yoga mats, etc., it can meet the need for different touch sensations generated with the change of human body temperature. In addition, the thermoplastic elastomer formulation of the present invention can further expand its application to the field of shape memory materials with temperature-variable properties.

[0005] On the one hand, the present invention provides a thermoplastic elastomer composition whose hardness varies with temperature, comprising: an α-olefin copolymer, accounting for 23 wt% to 40 wt% of the total weight of the thermoplastic elastomer composition, the α-olefin copolymer comprising α-olefin monomer units with 3 to 10 carbon atoms and not comprising ethylene monomer units; a first hydrogenated styrene / butadiene block copolymer and a second hydrogenated styrene / butadiene block copolymer, the first hydrogenated styrene / butadiene block copolymer being different from the second hydrogenated styrene / butadiene block copolymer; a non-hydrogenated styrene / isoprene block copolymer; an ethylene-α-olefin copolymer, the ethylene-α-olefin copolymer being different from the α-olefin copolymer; an ethylene vinyl acetate copolymer; and a thermoplastic polyolefin, the thermoplastic polyolefin being different from the α-olefin copolymer and also different from the ethylene-α-olefin copolymer, wherein the weight content of the α-olefin copolymer is greater than the total weight content of the first hydrogenated styrene / butadiene block copolymer, the second hydrogenated styrene / butadiene block copolymer, and the non-hydrogenated styrene / isoprene block copolymer.

[0006] In one embodiment, the present invention provides the thermoplastic elastomer composition as described above, wherein the first hydrogenated styrene / butadiene block copolymer accounts for 3 wt% to 8 wt% of the total weight of the thermoplastic elastomer composition.

[0007] In one embodiment, the present invention provides the thermoplastic elastomer composition as described above, wherein the second hydrogenated styrene / butadiene block copolymer accounts for 3 wt% to 8 wt% of the total weight of the thermoplastic elastomer composition.

[0008] In one embodiment, the present invention provides the thermoplastic elastomer composition as described above, wherein the weight average molecular weight of the first hydrogenated styrene / butadiene block copolymer is greater than the weight average molecular weight of the second hydrogenated styrene / butadiene block copolymer.

[0009] In one embodiment, the present invention provides the thermoplastic elastomer composition as described above, wherein the weight average molecular weight of the first hydrogenated styrene / butadiene block copolymer ranges from 95,000 to 125,000.

[0010] In one embodiment, the present invention provides the thermoplastic elastomer composition as described above, wherein the weight average molecular weight of the second hydrogenated styrene / butadiene block copolymer ranges from 60,000 to 80,000.

[0011] In one embodiment, the present invention provides the thermoplastic elastomer composition as described above, wherein the styrene content range of the first hydrogenated styrene / butadiene block copolymer and the styrene content range of the second hydrogenated styrene / butadiene block copolymer are both between 25 wt% and 33 wt%.

[0012] In one embodiment, the present invention provides the thermoplastic elastomer composition as described above, wherein the styrene content of the first hydrogenated styrene / butadiene block copolymer and the styrene content of the second hydrogenated styrene / butadiene block copolymer are substantially the same.

[0013] In one embodiment, the present invention provides the thermoplastic elastomer composition as described above, wherein the weight content of the first hydrogenated styrene / butadiene block copolymer and the weight content of the second hydrogenated styrene / butadiene block copolymer in the total weight of the thermoplastic elastomer composition are substantially the same.

[0014] In one embodiment, the present invention provides the thermoplastic elastomer composition as described above, wherein the weight content of the non-hydrogenated styrene / isoprene block copolymer is not greater than the combined weight content of the first hydrogenated styrene / butadiene block copolymer and the second hydrogenated styrene / butadiene block copolymer.

[0015] In one embodiment, the present invention provides the thermoplastic elastomer composition as described above, wherein the non-hydrogenated styrene / isoprene block copolymer accounts for 5 wt% to 10 wt% of the total weight of the thermoplastic elastomer composition.

[0016] In one embodiment, the present invention provides the thermoplastic elastomer composition as described above, wherein the weight average molecular weight range of the non-hydrogenated styrene / isoprene block copolymer is between 90,000 and 140,000.

[0017] In one embodiment, the present invention provides the thermoplastic elastomer composition as described above, wherein the ethylene-α-olefin copolymer accounts for 10 wt% to 15 wt% of the total weight of the thermoplastic elastomer composition.

[0018] In one embodiment, the present invention provides the thermoplastic elastomer composition as described above, wherein the ethylene vinyl acetate copolymer accounts for 10 wt% to 15 wt% of the total weight of the thermoplastic elastomer composition.

[0019] In one embodiment, the present invention provides the thermoplastic elastomer composition as described above, wherein the thermoplastic polyolefin accounts for 10 wt% to 15 wt% of the total weight of the thermoplastic elastomer composition.

[0020] In one embodiment, the present invention provides the thermoplastic elastomer composition as described above, further comprising at least one of the following items: processing oil, tackifying resin, and inorganic filler.

[0021] In one embodiment, the present invention provides the thermoplastic elastomer composition as described above, wherein the weight content of the processing oil is less than the total weight content of the first hydrogenated styrene / butadiene block copolymer and the second hydrogenated styrene / butadiene block copolymer.

[0022] In one embodiment, the present invention provides the thermoplastic elastomer composition as described above, wherein the weight content of the tackifying resin is less than the weight content of the first hydrogenated styrene / butadiene block copolymer or less than the weight content of the second hydrogenated styrene / butadiene block copolymer.

[0023] In one embodiment, the present invention provides the thermoplastic elastomer composition as described above, wherein the weight content of the inorganic filler is less than the total weight content of the first hydrogenated styrene / butadiene block copolymer and the second hydrogenated styrene / butadiene block copolymer.

[0024] In one embodiment, the present invention provides the thermoplastic elastomer composition as described above, wherein the weight content of the processing oil is greater than the weight content of the tackifying resin.

[0025] In one embodiment, the present invention provides the thermoplastic elastomer composition as described above, wherein the weight content of the inorganic filler is greater than the weight content of the tackifying resin.

[0026] In one embodiment, the present invention provides the thermoplastic elastomer composition as described above, wherein the α-olefin copolymer contains 4-methyl-1-pentene monomer units.

[0027] In one embodiment, the present invention provides the thermoplastic elastomer composition as described above, wherein the ethylene-α-olefin copolymer contains α-olefin monomer units having 4 to 10 carbon atoms.

[0028] In one embodiment, the present invention provides the thermoplastic elastomer composition as described above, wherein the thermoplastic polyolefin is low density polyethylene, linear low density polyethylene, or polypropylene.

[0029] In one embodiment, the present invention provides the thermoplastic elastomer composition as described above, wherein the inorganic filler is calcium carbonate.

[0030] On the other hand, the present invention provides an article whose hardness varies with temperature, the article being made of any one of the thermoplastic elastomer compositions of the above embodiments.

[0031] In one embodiment, the present invention provides an article with a temperature-dependent hardness as described above, wherein the hardness of the article at 23 °C ranges from HS 40C to HS 50C.

[0032] In one embodiment, the present invention provides an article with a temperature-dependent hardness as described above, wherein the finger pressure recovery time of the article is from 10 seconds to 20 seconds.

[0033] In one embodiment, the present invention provides an article with a temperature-dependent hardness as described above, wherein the resilience of the article is less than 20%.

[0034] The present invention also includes other technical means and effects, which are specifically described in the following paragraphs. Detailed Description of the Invention

[0035] To avoid confusion of the content of the present invention, well-known components, related materials and their related processing techniques are omitted in the following description.

[0036] The thermoplastic elastomer composition with a temperature-dependent hardness of the present invention mainly comprises the following components: an α-olefin copolymer; a first hydrogenated styrene / butadiene block copolymer and a second hydrogenated styrene / butadiene block copolymer, wherein the first hydrogenated styrene / butadiene block copolymer is different from the second hydrogenated styrene / butadiene block copolymer; a non-hydrogenated styrene / isoprene block copolymer; an ethylene-α-olefin copolymer, wherein the ethylene-α-olefin copolymer is different from the α-olefin copolymer; an ethylene vinyl acetate copolymer; and a thermoplastic polyolefin, wherein the thermoplastic polyolefin is different from the α-olefin copolymer and also different from the ethylene-α-olefin copolymer. The thermoplastic elastomer composition may optionally contain a processing oil, a tackifying resin and an inorganic filler as required.

[0037] α-olefin copolymer

[0038] The α-olefin copolymer is an olefin copolymer obtained by polymerizing at least two α-olefins having 3 to 10 carbon atoms as monomers, and does not contain ethylene monomer units. The preferred linear α-olefin monomers are propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene. The preferred branched α-olefin monomers are 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4,4-dimethyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 4-methyl-1-pentene. More preferably, it is a copolymer of propylene and 4-methyl-1-pentene. The α-olefin copolymer preferably has a melt flow index greater than 5 g / 10 min, and more preferably has a melt flow index of 5 to 15 g / 10 min. The melt flow index is measured according to ASTM D1238 using a 2.16 kg weight at a test temperature of 230 °C. The trade name of the α-olefin copolymer is ABSORTOMER TM EP-1001。

[0039] The first hydrogenated styrene / butadiene block copolymer and the second hydrogenated styrene / butadiene block copolymer

[0040] The first hydrogenated styrene / butadiene block copolymer is different from the second hydrogenated styrene / butadiene block copolymer. The first hydrogenated styrene / butadiene block copolymer and the second hydrogenated styrene / butadiene block copolymer can be respectively selected from styrene-ethylene-butene-styrene block copolymer (SEBS), styrene-[ethylene-(ethylene-propylene)]-styrene block copolymer (SEEPS), styrene-ethylene-butene block copolymer (SEB), or a combination thereof. The first hydrogenated styrene / butadiene block copolymer and the second hydrogenated styrene / butadiene block copolymer can be combinations with different numbers of blocks. The first hydrogenated styrene / butadiene block copolymer and the second hydrogenated styrene / butadiene block copolymer can also be combinations with the same number of blocks but different molecular weights. In a preferred example, both are SEBS, wherein the weight-average molecular weight of the first hydrogenated styrene / butadiene block copolymer is greater than the weight-average molecular weight of the second hydrogenated styrene / butadiene block copolymer. In this preferred example, the styrene content of the first hydrogenated styrene / butadiene block copolymer is substantially the same as the styrene content of the second hydrogenated styrene / butadiene block copolymer. The so-called substantially the same styrene content means that the difference in styrene content between the two is within 2%. In a preferred example, the weight content of the first hydrogenated styrene / butadiene block copolymer in the total weight of the thermoplastic elastomer composition is substantially the same as the weight content of the second hydrogenated styrene / butadiene block copolymer. The so-called substantially the same weight content means that the difference in weight content between the two is within 2%. In a preferred example, the weight-average molecular weight of the first hydrogenated styrene / butadiene block copolymer ranges from 95,000 to 125,000. In a preferred example, the weight-average molecular weight of the second hydrogenated styrene / butadiene block copolymer ranges from 60,000 to 80,000. In a preferred example, the styrene content ranges of both the first hydrogenated styrene / butadiene block copolymer and the second hydrogenated styrene / butadiene block copolymer are between 25 wt% and 33 wt%. In a preferred example, the vinyl content ranges of both the first hydrogenated styrene / butadiene block copolymer and the second hydrogenated styrene / butadiene block copolymer are between 36% and 40%.

[0041] Non-hydrogenated styrene / isoprene block copolymer

[0042] The non-hydrogenated styrene / isoprene block copolymer can be selected from styrene-isoprene diblock copolymer (SI) or styrene-isoprene-styrene triblock copolymer (SIS). Preferably SIS, with the trade name HYBRAR 5127.

[0043] The manufacturing method of the above non-hydrogenated styrene / isoprene block copolymer or hydrogenated styrene / butadiene block copolymer can be carried out by various known methods. For example, reference can be made to patent document US7612148B2. In addition, commercially available hydrogenated copolymers can be used. For example, styrene-ethylene-butene-styrene (SEBS) of Kraton G series of Kraton Company, Septon 8 series of Kuraray Company, SEBS series of Taiping Rubber Company, SEBS2 series of Polymeri Company, Calprene H series of Dynasol Company, and TuftecH series of Asahi Company can be used as materials for hydrogenated block series copolymers of styrene and 1,3-butadiene. Furthermore, for example, styrene-[ethylene-(ethylene-propylene)]-styrene (SEEPS) of Septon 4 series of Kuraray Company can be used as materials for hydrogenated block copolymers of styrene and a mixture of isoprene and 1,3-butadiene. Commercially available non-hydrogenated copolymers include, for example, SIS series of Taiping Rubber Company, Kraton D series of Kraton Company, Hybrar series of Kuraray Company, Calprene C series of Dynasol Company, and TR / SIS series of JSR Company.

[0044] Ethylene-α-olefin copolymer

[0045] Ethylene-α-olefin copolymer is a copolymer of ethylene and α-olefin. Preferred embodiments are ethylene-α-olefin copolymers composed of ethylene and α-olefins having 4 to 10 carbon atoms, and particularly preferred are ethylene-α-olefin copolymers composed of ethylene and 1-butene or 1-octene. The ethylene-α-olefin copolymer preferably has a melt flow index greater than 0.5 g / 10 min, and more preferably has a melt flow index of 0.5 to 5 g / 10 min. The melt flow index is measured according to ASTM D1238 using a 2.16 kg weight at a test temperature of 190 °C. The preferred trade name of the ethylene-α-olefin copolymer is TAFMER TM DF640.

[0046] Ethylene vinyl acetate copolymer

[0047] Ethylene vinyl acetate copolymer is a copolymer of ethylene and vinyl acetate, and the content of vinyl acetate is usually between about 2 wt% and about 40 wt%, and more preferably the content of vinyl acetate is between about 20 wt% and about 40 wt%. The ethylene vinyl acetate copolymer preferably has a melt flow index greater than 2 g / 10 min, and more preferably has a melt flow index of 12 to 30 g / 10 min. The melt flow index is measured according to ASTM D1238 using a 2.16 kg weight at a test temperature of 190 °C. The preferred trade name of the ethylene vinyl acetate copolymer is EVA-33121.

[0048] Thermoplastic polyolefin

[0049] The thermoplastic polyolefin is a polyolefin different from α-olefin copolymers and ethylene-α-olefin copolymers. Preferred embodiments are polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), polybutene (PB), where polyethylene (PE) includes high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and ultra-high molecular weight polyethylene (UHMWPE). Preferred thermoplastic polyolefins are LDPE, LLDPE, and PP.

[0050] In addition to the above components, suitable additives that can be added to the thermoplastic elastomer composition of the present invention include processing oil, tackifying resin, inorganic filler, etc. The processing oil is selected from paraffinic white oil, naphthenic oil, aromatic oil, naphthenic oil, polybutene, and polyisobutylene or a combination thereof. In a preferred embodiment, paraffin oil is selected. The tackifying resin can be an aliphatic hydrocarbon resin, alicyclic resin, aromatic resin, aromatic-modified aliphatic resin, aromatic-modified alicyclic resin, hydrogenated aliphatic hydrocarbon resin, hydrogenated alicyclic resin, hydrogenated aromatic-modified aliphatic resin, terpene, modified terpene, hydrogenated terpene, rosin, colophony, hydrogenated colophony, rosin ester, hydrogenated rosin ester, coumarone resin, phenolic resin, polyterpene resin, modified alicyclic hydrocarbon, polymerized rosin, oligomer (Oligomer), or a combination of the above. The monomers used to form the oligomer can be ethylene, butene, styrene, or a combination of the above, and the weight-average molecular weight of the oligomer is less than 10,000. In a preferred embodiment, the tackifying resin is an aliphatic hydrocarbon resin with a softening point between 100°C and 110°C. The inorganic filler is selected from one or a mixture of talc, calcium carbonate, silica, carbon black, titanium dioxide, mica, and jade powder. In a preferred embodiment, heavy calcium carbonate (hereinafter referred to as heavy calcium) is selected.

[0051] Analysis method

[0052] Styrene content: Measured using a nuclear magnetic resonance analyzer, which is a measurement method well-known to those skilled in the art. If a hydrogenated polymer is used, the polymer before hydrogenation is taken to calculate the content of the vinyl structure.

[0053] Weight-average molecular weight (Mw): Analyzed using a gel permeation chromatography (GPC). A Waters 1525 binary HPLC pump and a Waters 2414 refractive index detector are used. The eluent is tetrahydrofuran, and the eluent flow rate is 1 ml / min.

[0054] Melt flow index of the polymer: Measured according to ASTM D1238 using a 2.16 kg weight at a test temperature of 190 °C or 230 °C.

[0055] Hardness: Measured using an Asker C durometer.

[0056] Resilience: That is, the falling ball rebound value, measured at room temperature using a falling ball vertical rebound tester according to ASTM D2632 standard.

[0057] Finger pressure recovery time: Press the test piece with a 1 kg force at room temperature, observe the time required for the test piece to return to its original state after finger pressure, and time it with a stopwatch.

[0058] Examples of thermoplastic elastomer compositions and their products with hardness varying with temperature

[0059] Example 1

[0060] Thermoplastic elastomer composition with hardness varying with temperature

[0061] Take 5 wt% of SEBS-1 (styrene content 29 wt%, weight average molecular weight 110,000, the first hydrogenated styrene / butadiene block copolymer) and 5 wt% of SEBS-2 (styrene content 29 wt%, weight average molecular weight 70,000, the second hydrogenated styrene / butadiene block copolymer), and add 5 wt% of paraffin oil (150N white oil, processing oil). After the above mixture is left standing for 8 hours, add 23 wt% of EP1001 (α-olefin copolymer), 10 wt% of HYBRAR 5127 (SIS, non-hydrogenated styrene / isoprene block copolymer), 15 wt% of ethylene-1, butene copolymer (ethylene-α-olefin copolymer), 15 wt% of EVA (ethylene-vinyl acetate copolymer), 15 wt% of LDPE (low density polyethylene, thermoplastic polyolefin), 2 wt% of tackifying resin (Regalite TM R1125), and 5 wt% of inorganic filler (800-mesh heavy calcium). Knead and extrude into pellets at 160 - 200 °C using a twin-screw extruder.

[0062] Product with hardness varying with temperature

[0063] Knead the above particles on an open mill, and simultaneously add auxiliary materials such as a foaming agent (azodicarbonamide AC3000) and a crosslinking agent (1,3(1,4)-bis(tert-butylperoxyisopropyl)benzene BIPB (purity 40%)). Set the temperature at 90 - 110 °C for about 10 - 15 minutes. Put the kneaded material into an injection / molding press for molding, with the conditions set at 175 °C / 260S. Take out the molded test piece for various analyses. Cut the test piece into 10 cm × 10 cm square shape and then place it in a constant temperature water bath to test the hardness change value with temperature.

[0064] The product whose hardness varies with temperature in Example 1 has the following characteristics: the hardness range at 23 °C is HS 40C to HS 50C, the finger pressure recovery time is 10 seconds to 20 seconds, and the resilience of the product is less than 20%.

[0065] Tables 1, 2, and 3 show other examples and comparative examples of the present invention. The procedures are similar to those of Example 1 above, except that other types are substituted for the ethylene-α-olefin copolymer and the thermoplastic polyolefin, and the contents of each component are different. The conditions of each example and comparative example are clearly listed in the table.

[0066] Table 1

[0067]

[0068]

[0069] Table 1 shows that the products of Examples 1 to 5 have the following characteristics: the hardness range at 23 °C is HS 40C to HS 50C, the finger pressure recovery time is 10 seconds to 20 seconds, and the resilience of the product is less than 20%. In Comparative Example 1, the content of EP1001 (α-olefin copolymer) is less than 23 wt% and not greater than the total weight content of SEBS-1, SEBS-2, and HYBRAR (SIS). Comparative Example 1 exhibits poor hardness, resilience, and finger pressure recovery time at 23 °C. In Comparative Example 2, the content of the α-olefin copolymer is higher than 40 wt%, and it exhibits poor hardness, resilience, and finger pressure recovery time at 23 °C.

[0070] Table 2

[0071]

[0072]

[0073]

[0074] Table 2 shows that the products of Examples 5 to 11 have the following characteristics: the hardness range at 23 °C is HS 40C to HS 50C, the finger pressure recovery time is 10 seconds to 20 seconds, and the resilience of the product is less than 20%. The content of HYBRAR (SIS) (non-hydrogenated styrene / isoprene block copolymer) in Comparative Example 3 is less than 5 wt%, and Comparative Example 3 shows poor hardness, resilience, and finger pressure recovery time at 23 °C. The content of HYBRAR (SIS) (non-hydrogenated styrene / isoprene block copolymer) in Comparative Example 4 is higher than 10 wt%, and the weight content of EP1001 is lower than the total weight content of SEBS-1, SEBS-2, and HYBRAR (SIS), and the weight content of HYBRAR (SIS) is greater than the total weight content of SEBS-1 and SEBS-2 combined. Comparative Example 4 shows poor hardness, resilience, and finger pressure recovery time at 23 °C. The content of LDPE (thermoplastic polyolefin) in Comparative Example 5 is less than 10 wt%, and Comparative Example 5 shows poor hardness, resilience, and finger pressure recovery time at 23 °C. The content of LDPE (thermoplastic polyolefin) in Comparative Example 6 is higher than 15 wt%, and Comparative Example 6 shows poor hardness, resilience, and finger pressure recovery time at 23 °C.

[0075] Table 3

[0076]

[0077]

[0078]

[0079] Table 3 shows that the products of Examples 5 and 12 to 17 have the following characteristics: the hardness range at 23 °C is HS 40C to HS 50C, the finger pressure recovery time is 10 seconds to 20 seconds, and the resilience of the product is less than 20%. The content of ethylene-α-olefin copolymer (ethylene-1-butene copolymer) in Comparative Example 7 is less than 10 wt%, and Comparative Example 7 shows poor hardness, resilience, and finger pressure recovery time at 23 °C. The content of ethylene-α-olefin copolymer (ethylene-1-butene copolymer) in Comparative Example 8 is higher than 15 wt%, and Comparative Example 8 shows poor hardness, resilience, and finger pressure recovery time at 23 °C. The content of EVA in Comparative Example 9 is less than 10 wt%, and Comparative Example 9 shows poor hardness, resilience, and finger pressure recovery time at 23 °C. The content of EVA in Comparative Example 10 is higher than 15 wt%, and Comparative Example 10 shows poor hardness, resilience, and finger pressure recovery time at 23 °C.

[0080] The above are only the preferred embodiments of the present invention, and are not intended to limit the scope of patent protection of the present invention; any other equivalent changes or modifications made without departing from the spirit disclosed by the present invention shall be included in the scope of patent protection of the present application.

Claims

1. A thermoplastic elastomer composition whose hardness varies with temperature, comprising: An α-olefin copolymer, accounting for 23 wt% to 40 wt% of the total weight of the thermoplastic elastomer composition, and the α-olefin copolymer contains α-olefin monomer units with 3 to 10 carbon atoms; A first hydrogenated styrene / butadiene block copolymer and a second hydrogenated styrene / butadiene block copolymer, and the first hydrogenated styrene / butadiene block copolymer is different from the second hydrogenated styrene / butadiene block copolymer; A non-hydrogenated styrene / isoprene block copolymer; An ethylene-α-olefin copolymer, and the ethylene-α-olefin copolymer is different from the α-olefin copolymer; An ethylene vinyl acetate copolymer; and A thermoplastic polyolefin, and the thermoplastic polyolefin is different from the α-olefin copolymer and also different from the ethylene-α-olefin copolymer, wherein the weight content of the α-olefin copolymer is greater than the total weight content of the first hydrogenated styrene / butadiene block copolymer, the second hydrogenated styrene / butadiene block copolymer, and the non-hydrogenated styrene / isoprene block copolymer.

2. The thermoplastic elastomer composition according to claim 1, wherein the first hydrogenated styrene / butadiene block copolymer accounts for 3 wt% to 8 wt% of the total weight of the thermoplastic elastomer composition.

3. The thermoplastic elastomer composition according to claim 1, wherein the second hydrogenated styrene / butadiene block copolymer accounts for 3 wt% to 8 wt% of the total weight of the thermoplastic elastomer composition.

4. The thermoplastic elastomer composition according to claim 1, wherein the weight content of the first hydrogenated styrene / butadiene block copolymer in the total weight of the thermoplastic elastomer composition is substantially the same as the weight content of the second hydrogenated styrene / butadiene block copolymer.

5. The thermoplastic elastomer composition according to claim 1, wherein the non-hydrogenated styrene / isoprene block copolymer accounts for 5 wt% to 10 wt% of the total weight of the thermoplastic elastomer composition.

6. The thermoplastic elastomer composition according to claim 1, wherein the weight content of the non-hydrogenated styrene / isoprene block copolymer is not greater than the total weight content of the first hydrogenated styrene / butadiene block copolymer and the second hydrogenated styrene / butadiene block copolymer.

7. The thermoplastic elastomer composition according to claim 1, wherein the ethylene-α-olefin copolymer accounts for 10 wt% to 15 wt% of the total weight of the thermoplastic elastomer composition.

8. The thermoplastic elastomer composition according to claim 1, wherein the ethylene-vinyl acetate copolymer accounts for 10 wt% to 15 wt% of the total weight of the thermoplastic elastomer composition.

9. The thermoplastic elastomer composition according to claim 1, wherein the thermoplastic polyolefin accounts for 10 wt% to 15 wt% of the total weight of the thermoplastic elastomer composition.

10. The thermoplastic elastomer composition according to claim 1, wherein the weight average molecular weight of the first hydrogenated styrene / butadiene block copolymer is greater than that of the second hydrogenated styrene / butadiene block copolymer.

11. The thermoplastic elastomer composition according to claim 1, wherein the styrene content ranges of both the first hydrogenated styrene / butadiene block copolymer and the second hydrogenated styrene / butadiene block copolymer are between 25 wt% and 33 wt%.

12. A product whose hardness changes with temperature, wherein, The article is made of the thermoplastic elastomer composition according to any one of claims 1 to 11.

13. The article with hardness varying with temperature according to claim 12, wherein the hardness range of the article at 23 °C is HS 40C to HS 50C.

14. The article with hardness varying with temperature according to claim 12, wherein the finger pressure recovery time of the article under a force of 1 kgf is from 10 seconds to 20 seconds.

15. The article with hardness varying with temperature according to claim 12, wherein the resilience of the article is less than 20%.

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