Temperature-adaptive thermoplastic elastomer as well as preparation method and application thereof

Abstract

The invention discloses a temperature self-adaptive thermoplastic elastomer and a preparation method and application thereof, and the temperature self-adaptive thermoplastic elastomer comprises the following components by weight: 22-38 parts of a styrene-butadiene hydrogenated copolymer; 22-38 parts of a phase change material; and 18-38 parts of a maleic anhydride grafted polyolefin elastomer. According to the temperature self-adaptive TPE disclosed by the invention, the maleic anhydride grafted polyolefin elastomer is introduced, so that the bonding performance between the TPE and the PA is remarkably improved. Meanwhile, the phase-change material such as paraffin is introduced, and dynamic temperature balance is achieved by means of the melting heat absorption and crystallization heat release characteristics of the phase-change material. By means of the innovative design, the overheating problem of the electric tool in long-time use is effectively solved, and the interface stress failure risk caused by temperature fluctuation is remarkably reduced.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a temperature-adaptive thermoplastic elastomer, its preparation method, and its application. Background Technology

[0002] During the use of power tools, the heat generated by the motor causes the tool surface temperature to rise, affecting the user experience and operational safety. Power tool housings are typically made of nylon, and to improve feel and reduce surface temperature, thermoplastic elastomer (TPE) materials are often coated onto the tool surface. Related technologies disclose a nylon-coated TPE composite material, its preparation method, and its applications. This material combines polycaprolactam and thermoplastic polyamide elastomer, along with other components, utilizing polycaprolactam to enhance the composite's strength and coating performance. However, existing nylon coating materials suffer from functional limitations, focusing only on adhesive properties and failing to effectively address interfacial stress failure issues caused by temperature fluctuations (such as thermal expansion and contraction delamination), and also failing to mitigate the overheating problem associated with prolonged power tool use. Summary of the Invention

[0003] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. Therefore, the object of the present invention is to provide a temperature-adaptive thermoplastic elastomer, its preparation method, and its application.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A first aspect of the present invention provides a temperature-adaptive thermoplastic elastomer comprising the following components calculated in parts by weight: 22-38 parts of hydrogenated copolymer of styrene-butadiene; 22-38 parts of phase change material; 18-38 parts of maleic anhydride-grafted polyolefin elastomer.

[0005] In this invention, when thermoplastic elastomers are used to overcoat nylon (PA), maleic anhydride-grafted polyolefin elastomers (POE-g-MAH) can significantly improve the adhesion between the thermoplastic elastomer and PA. Furthermore, by utilizing the characteristics of phase change materials—melting endothermic (at high temperatures) and crystallization exothermic (at low temperatures)—dynamic temperature balance is achieved. The resulting temperature-adaptive thermoplastic elastomer, when used to encapsulate the housing of power tools, can improve the overheating problem caused by prolonged use of power tools and significantly reduce the risk of interfacial stress failure caused by temperature fluctuations. The temperature-adaptive performance further expands its application range, enabling it to be applied in fields such as wearable devices (e.g., thermostatic protective gear), medical heating (temperature buffering), and building energy conservation (dynamic temperature regulation), effectively solving the functional deficiencies of existing TPEs in temperature-sensitive scenarios.

[0006] In some embodiments of the present invention, the hydrogenated copolymer of styrene-butadiene (SEBS resin) has a viscosity of ≥100 cP at a toluene content of 10 wt% under temperature conditions of 25°C.

[0007] In some embodiments of the present invention, the viscosity of the SEBS resin with a 10wt% toluene content at 25°C is 100~3000 cP, such as 300~2500 cP.

[0008] There are no special requirements for the styrene content in the SEBS resin described in this invention. The styrene content in the SEBS resin described in this invention is 20~45wt%.

[0009] In some embodiments of the present invention, the SEBS resin has a viscosity of 200 cP to 600 cP at a temperature of 25°C with a toluene content of 10 wt%. The viscosity was tested according to standard ASTM D2196-2018.

[0010] In some embodiments of the present invention, the SEBS resin content that can achieve the purpose of the present invention, calculated by weight, can be 25-35 parts, 28-33 parts, 29-32 parts, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, 30 parts, 31 parts, 32 parts, 33 parts, 34 parts, or 35 parts.

[0011] In some embodiments of the present invention, the melting point of the phase change material is 20~60℃, such as 25~55℃, 30~50℃, 35~45℃, 28℃, 30℃, 32℃, 34℃, 36℃, 38℃, 40℃, 42℃, 44℃, 46℃, 48℃, 50℃, 52℃, 54℃, 56℃, 58℃, 60℃, etc. In this invention, the phase change material with the above melting points can meet the practical application requirements of temperature-adaptive thermoplastic elastomers. The melting point test method is performed according to GB / T 28724-2012.

[0012] In some embodiments of the present invention, the phase change material includes at least one of paraffin (melting point approximately 20-60°C, such as 25-45°C), polyethylene glycol-1000 (melting point approximately 37-41°C), n-octadecane (melting point approximately 28-30°C), n-eicosane (melting point approximately 36-38°C), and n-tetracosane (melting point approximately 49-52°C); preferably paraffin. The above-mentioned phase change material not only meets the low melting point requirement but also exhibits excellent compatibility with the matrix resin.

[0013] As used in this article, “about” actually means that the error is allowed to be within ±2%, for example, about 100 is actually 100 ± 2% × 100.

[0014] In some embodiments of the present invention, the content of phase change material, calculated by weight, to achieve the purpose of the present invention can be 25-35 parts, 28-33 parts, 29-32 parts, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, 30 parts, 31 parts, 32 parts, 33 parts, 34 parts, or 35 parts. In the present invention, an excessively high content of phase change material will lead to uneven dispersion or encapsulation of it in the matrix resin, resulting in phenomena such as phase change material leakage and phase separation, leading to a decrease in its cycling thermal performance.

[0015] In some embodiments of the present invention, the maleic anhydride-grafted polyolefin elastomer includes at least one of maleic anhydride-grafted octene-ethylene copolymer, maleic anhydride-grafted polyethylene, and maleic anhydride-grafted polypropylene.

[0016] In some embodiments of the present invention, the mass grafting rate of maleic anhydride in the maleic anhydride-grafted polyolefin elastomer is 0.2% to 3.0%, such as 0.3% to 3.0%, 0.5% to 3.0%, 0.6% to 2.8%, 0.7% to 2.5%, 0.8%, 0.9%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, etc. In the present invention, when the mass grafting rate of maleic anhydride in the maleic anhydride-grafted polyolefin elastomer is within the above range, its adhesion to the matrix resin is improved. In the present invention, the term "grafting rate" refers to the percentage of maleic anhydride by weight in the maleic anhydride-grafted POE to the total weight of the maleic anhydride-grafted POE. The grafting rate is determined by acid-base titration.

[0017] The test method for maleic anhydride content is as follows: Titration is used, with sodium hydroxide (NaOH) as the titrant. NaOH reacts with maleic anhydride to form a water-soluble sodium salt. During titration, the maleic anhydride sample is dissolved in a suitable solvent, and an indicator (such as phenolphthalein) from a methanol solution is added. The endpoint of the color change in the titrant is observed by passing the NaOH solution through the titrant, thus determining the maleic anhydride content.

[0018] In some embodiments of the present invention, the content of maleic anhydride-grafted polyolefin elastomer, calculated by weight, to achieve the objective of the present invention can be 20-35 parts, 25-33 parts, 26-32 parts, 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, 30 parts, 31 parts, 32 parts, 33 parts, 34 parts, or 35 parts. In the present invention, a too low content of maleic anhydride-grafted polyolefin elastomer will lead to a decrease in the adhesive strength of the temperature-adaptive thermoplastic elastomer.

[0019] In some embodiments of the present invention, the total mass percentage of the hydrogenated copolymer of styrene-butadiene and the phase change material is not less than 44% of the temperature-adaptive thermoplastic elastomer.

[0020] In some embodiments of the present invention, the total mass percentage of the hydrogenated copolymer of styrene-butadiene and the phase change material is not less than 50% of the temperature-adaptive thermoplastic elastomer.

[0021] In some embodiments of the present invention, the total mass percentage of the hydrogenated copolymer of styrene-butadiene and the phase change material is 50% to 70% of the temperature-adaptive thermoplastic elastomer.

[0022] In some embodiments of the present invention, the mass ratio of the hydrogenated copolymer of styrene-butadiene to the phase change material is (0.6~1.5):1, such as 0.6:1, 1:1, 1.5:1, etc. In this invention, if the SEBS resin content is too low, it is difficult to effectively disperse or encapsulate the phase change material, which can easily lead to leakage or phase separation of the phase change material during subsequent use, accelerating thermal fatigue of the material and causing a decrease in the cyclic thermal properties of the temperature-adaptive thermoplastic elastomer.

[0023] In some embodiments of the present invention, the melting point of the temperature-adaptive thermoplastic elastomer is 30~60℃, such as 35℃, 36℃, 37℃, 38℃, 39℃, 40℃, 41℃, 42℃, 43℃, 44℃, 45℃, 46℃, 47℃, 48℃, 49℃, 50℃, 51℃, 52℃, 53℃, 54℃, 55℃, 56℃, 57℃, 58℃, 59℃, and 60℃. The melting point is determined according to GB / T28724-2012.

[0024] In some embodiments of the present invention, the temperature-adaptive thermoplastic elastomer further includes inorganic fillers.

[0025] In some embodiments of the present invention, the inorganic filler content that can achieve the purpose of the present invention, calculated by weight, can be 10-20 parts, 11-18 parts, 12-15 parts, 13 parts, 14 parts, 15 parts, etc.

[0026] In some embodiments of the present invention, the inorganic filler includes at least one of calcium carbonate, talc, or kaolin, and the average particle size of the inorganic filler is 1-50 µm, such as 3-40 µm, 4-30 µm, etc. Preferably, the filler is calcium carbonate; calcium carbonate with an average particle size between 1-50 µm has good dispersibility in TPE composites, and the high specific surface area of ​​the inorganic filler combined with the TPE composite can improve its heat resistance and compression set resistance. The average particle size is tested according to GB / T19077-2016.

[0027] In some embodiments of the present invention, the temperature-adaptive thermoplastic elastomer comprises the following components calculated in parts by weight: 25-35 parts of hydrogenated copolymer of styrene-butadiene; 25-35 parts of phase change material; 20-35 parts of maleic anhydride-grafted polyolefin elastomer; 10-18 parts of inorganic filler.

[0028] In some embodiments of the present invention, the temperature-adaptive thermoplastic elastomer further includes additives; the additives include at least one of antioxidants, light stabilizers, and lubricants.

[0029] In some embodiments of the present invention, the temperature-adaptive thermoplastic elastomer comprises the following components calculated in parts by weight: 25-35 parts of hydrogenated copolymer of styrene-butadiene; 25-35 parts of phase change material; 20-35 parts of maleic anhydride-grafted polyolefin elastomer; 10-18 parts of inorganic filler; Additives: 0.2-2 parts.

[0030] In some embodiments of the present invention, the content of the adjuvant that enables the present invention to achieve its objective can be 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1.0 parts, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, 1.6 parts, 1.7 parts, 1.8 parts, 1.9 parts, or 2.0 parts.

[0031] In some embodiments of the present invention, the processing aids are present in the following proportions by weight: antioxidant 0.2-1.5 parts, light stabilizer 0-1.5 parts, and lubricant 0-0.5 parts.

[0032] In some embodiments of the present invention, the antioxidant includes at least one of hindered phenolic antioxidants, hindered amine antioxidants, phosphite antioxidants, and thioester antioxidants.

[0033] In some embodiments of the present invention, the antioxidant includes at least one of 2,6-di-tert-butyl-4-methylphenol, antioxidant 1010, antioxidant 1076, antioxidant 1790, antioxidant 168, and antioxidant 626; such as a mixture of antioxidant 1010 and antioxidant 168; such as a mixture of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:(0.8~2).

[0034] In some embodiments of the present invention, the light stabilizer is a hindered amine light stabilizer and / or a triazine light stabilizer.

[0035] In some embodiments of the present invention, the light stabilizer is a mixture of hindered amine light stabilizer and triazine light stabilizer in a weight ratio of 2:1.

[0036] In some embodiments of the present invention, the hindered amine light stabilizer includes at least one of light stabilizer 622, light stabilizer 770, light stabilizer 944, light stabilizer 783, light stabilizer 791, light stabilizer 3853, light stabilizer 292, and light stabilizer 123.

[0037] In some embodiments of the present invention, the triazine light stabilizer is one or more of UV-234, UV-236, and UV-2373.

[0038] In some embodiments of the present invention, the lubricant includes one or more of vinyl bis-stearamide, hydroxy fatty acid lubricants, erucamide, zinc stearate, magnesium stearate, or polyethylene wax.

[0039] A second aspect of the present invention provides a method for preparing the temperature-adaptive thermoplastic elastomer, comprising the following steps: S1: A premix is ​​obtained by mixing a hydrogenated copolymer of styrene-butadiene with a phase change material; S2: The premix and the remaining components are mixed and then extruded and granulated using a twin-screw extruder to obtain the temperature-adaptive thermoplastic elastomer.

[0040] In some embodiments of the present invention, in S1, the mixing temperature is 60~100℃, such as 70℃, 80℃, 90℃, 100℃, etc.

[0041] In some embodiments of the present invention, in S1, the mixing is carried out at a speed of 200 to 500 rpm, such as at 300 rpm, 350 rpm, 400 rpm, or 450 rpm.

[0042] In some embodiments of the present invention, the screw length-to-diameter ratio of the twin-screw extruder is (36~60):1, such as (48~56):1.

[0043] In some embodiments of the present invention, the barrel temperature of the twin-screw extruder is 160~230°C, such as 180~210°C.

[0044] A third aspect of the present invention provides the application of the temperature-adaptive thermoplastic elastomer described above in power tools, wearable devices, medical heating devices, or building energy-saving devices.

[0045] In some embodiments of the invention, the application includes its use in the nylon housing surface coating of the aforementioned device.

[0046] In some embodiments of the invention, the application includes application in the coating of power tool handle surfaces.

[0047] The beneficial effects of this invention are: The temperature-adaptive thermoplastic elastomer (TPE) of this invention significantly improves the adhesion between TPE and nylon (PA) by introducing a maleic anhydride-grafted polyolefin elastomer (POE-g-MAH). Simultaneously, the introduction of a phase change material such as paraffin wax utilizes its endothermic melting (at high temperatures) and exothermic crystallization (at low temperatures) properties to achieve dynamic temperature equilibrium. This innovative design not only effectively improves the overheating problem of power tools during prolonged use but also significantly reduces the risk of interfacial stress failure caused by temperature fluctuations.

[0048] The temperature-adaptive thermoplastic elastomer (TPE) of the present invention combines elasticity, adhesion to PA and temperature adaptability, with high bonding strength and high enthalpy retention after multiple cycles.

[0049] The temperature-adaptive thermoplastic elastomer of the present invention adds temperature-adaptive function on the basis of improving mechanical properties, expanding its application potential. It can be applied to wearable devices (such as constant temperature protective gear), medical hot compress (temperature buffer) and building energy conservation (dynamic temperature regulation) and other fields, effectively solving the functional deficiency problem of existing TPE in temperature-sensitive scenarios. Detailed Implementation

[0050] The present invention will be further described in detail below through specific embodiments. Unless otherwise specified, the raw materials, reagents, or apparatus used in the embodiments and comparative examples are all available from conventional commercial sources or can be obtained by existing technical methods. Unless otherwise specified, the test or experimental methods are conventional methods in the art.

[0051] 1. Raw materials and reagents: (1) SEBS: SEBS-1: Hydrogenated copolymer of styrene and butadiene, SEBS 7554, 10wt% content, toluene viscosity 400cP; Manufacturer: Li Changrong; SEBS-2: Hydrogenated copolymer of styrene and butadiene, SEBS 7551, 10wt% content, toluene viscosity 2000cP; Manufacturer: Li Changrong; (2) Phase change materials: PW: 40# paraffin wax, melting point 40℃, Shanghai Yijiu Chemical Co., Ltd. PW: 35# paraffin wax, melting point 35℃, Shanghai Yijiu Chemical Co., Ltd. n-Octadecane: Melting point 28.2℃, Shanghai Better Chemical Co., Ltd. n-Eicosane: Melting point 36.7℃, Anaiji Chemicals n-Tetracosane: Melting point 51℃, Shanghai Huayuan Biochemical Technology Co., Ltd. Polyethylene glycol 1000: PEG1000, melting point 56℃, Yisheng Biotechnology (Shanghai) Co., Ltd. (3) Maleic anhydride-grafted polyolefin elastomer POE-g-MAH: KT-906, medium grafting rate, Shenyang Ketong Plastics Co., Ltd.; POE-g-MAH: W1, high grafting rate, Cosmax Chemical Co., Ltd.; The grafting rate standards are: low <0.4%; medium 0.4%-0.8%; high ≥0.8%.

[0052] (4) Inorganic fillers: Heavy calcium carbonate: CC903, average particle size 23µm; China Kelon Powder; Talc: TYT-777A, average particle size 5.3µm; Liaoning Beihai Industry (Group) Co., Ltd. (5) Additives: Oxidizing agents: Irganox 1010, Irgafos 168, BASF; the mass ratio of Irganox 1010 and Irgafos 168 is 1:1.

[0053] 2. The temperature-adaptive thermoplastic elastomers of the various embodiments and comparative examples of the present invention were prepared by the following method: S1: SEBS and phase change material are put into a high-speed mixer and mixed at a mixing temperature of 80°C and a rotation speed of 30 rpm to obtain a premix. S2: The premix obtained in S1 is mixed with maleic anhydride-grafted polyolefin elastomer, inorganic filler and additives, and then added to a twin-screw extruder for melt extrusion to obtain a temperature-adaptive thermoplastic elastomer; wherein, the length-to-diameter ratio of the twin-screw extruder is 48:1 and the extrusion temperature is 200℃.

[0054] If there is no phase change material, SEBS is directly mixed with other components for S2.

[0055] 3. Performance Testing (1) Adhesion strength test method: According to GB / T 7760-2003 standard, the temperature-adaptive thermoplastic elastomers of each embodiment and comparative example were injected into a nylon substrate sample of PA6+30% (mass fraction relative to PA6) glass fiber using an injection molding machine on a specific mold. The dimensions of the nylon substrate sample were: thickness 2mm±0.1mm, width 25mm±0.1mm, and total length approximately 125mm; the injection temperature was 235℃. After being placed at room temperature for 24 hours, a 90° peel test was performed using a high-end tensile testing machine to measure the adhesion force between the nylon-coated TPE composite material and the nylon substrate sample. The adhesion strength grades were classified as follows: A: It can be easily peeled off, leaving a smooth peeling surface with no residue; B: The peeling force is relatively large, and the residue on the peeling surface is as high as 50%; C: Difficult to peel off at the edges and corners, with residue of 50%~99%, and relatively high peeling force; D: Difficult to peel off at the edges and corners, TPE breaks, and the peeling force is very large; The proportion of residue on the peeled surface is calculated based on the proportion of residue area.

[0056] (2) The enthalpy of fusion of the sample was tested by a differential scanning calorimeter (e.g., DSC204F1, Netzsch, heated from 30°C to 230°C at a rate of 10°C / min, and then cooled from 230°C to 30°C at a rate of 10°C / min). The enthalpy of fusion described below is the enthalpy of fusion after eliminating thermal history.

[0057] (3) Cyclic enthalpy retention rate: Differential scanning calorimeter (DSC) was used to perform DSC test at a temperature change rate of 10℃ / min. The cyclic enthalpy retention rate is equal to the melting enthalpy after 500 temperature cycles / initial melting enthalpy * 100%.

[0058] Examples 1-12 and Comparative Examples 1-4 The weights of each component of the temperature-adaptive thermoplastic elastomers in Examples 1-12 and Comparative Examples 1-4 are shown in Tables 1 and 2: Table 1

[0059] Table 2

[0060] The performance test results of the temperature-adaptive thermoplastic elastomers in each embodiment and comparative example according to the methods mentioned above are shown in Tables 3 and 4.

[0061] Table 3

[0062] Table 4

[0063] As shown in Tables 1 to 4, the adhesion between the temperature-adaptive thermoplastic elastomers and PA in Examples 1-12 all reached over 4 N / mm. The addition of phase change material not only optimized the adhesion but also improved its overheat resistance, allowing its enthalpy retention rate to remain above 94% after 500 cycles. This combined the elasticity, adhesion to nylon, and temperature-adaptive properties of the temperature-adaptive thermoplastic elastomer, improving the processability of the SEBS material. Example 2 contained more SEBS and paraffin, resulting in a higher melt enthalpy and a lower content of maleic anhydride-grafted polyolefin elastomer, leading to a slight decrease in adhesion adaptability, but still higher than the comparative example. While Comparative Example 2 had a higher melt enthalpy or cycle retention rate, its low content of maleic anhydride-grafted polyolefin elastomer caused a sharp drop in resin adhesion. Comparing Examples 1 and 5 shows that the grafting rate of the maleic anhydride-grafted polyolefin elastomer affected its adhesion; a higher grafting rate resulted in improved adhesion.

[0064] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A temperature-adaptive thermoplastic elastomer, characterized by: The temperature self-adapting thermoplastic elastomer comprises the following components in parts by weight: a hydrogenated copolymer of styrene-butadiene 22-38 parts; a phase change material 22-38 parts; a maleic anhydride grafted polyolefin elastomer 18-38 parts.

2. The temperature-adaptive thermoplastic elastomer of claim 1, wherein: The melting point of the phase change material is 20-60℃.

3. The temperature-adaptive thermoplastic elastomer according to claim 1 or 2, characterized in that: The phase change material comprises at least one of paraffin, polyethylene glycol-1000, n-octadecane, n-eicosane, n-tetracosane.

4. The temperature-adaptive thermoplastic elastomer of claim 1, wherein: The maleic anhydride grafted polyolefin elastomer comprises at least one of a maleic anhydride grafted octene ethylene copolymer, a maleic anhydride grafted polyethylene, and a maleic anhydride grafted polypropylene; and / or, the mass grafting rate of maleic anhydride in the maleic anhydride grafted polyolefin elastomer is 0.2-3.0%.

5. The temperature-adaptive thermoplastic elastomer of claim 1, wherein: The mass ratio of the hydrogenated copolymer of styrene-butadiene and the phase change material is (0.6-1.5):

1.

6. The temperature-adaptive thermoplastic elastomer of claim 1, wherein: The temperature self-adapting thermoplastic elastomer further comprises an inorganic filler; the mass fraction of the inorganic filler is 10-20 parts.

7. The temperature-adaptive thermoplastic elastomer of claim 6, wherein: The inorganic filler comprises at least one of calcium carbonate, talc, or kaolin; and / or, the average particle size of the inorganic filler is 1-50µm.

8. The temperature-adaptive thermoplastic elastomer of claim 7, wherein: The temperature self-adapting thermoplastic elastomer comprises the following components in parts by weight: a hydrogenated copolymer of styrene-butadiene 25-35 parts; a phase change material 25-35 parts; a maleic anhydride grafted polyolefin elastomer 20-35 parts; an inorganic filler 10-18 parts; an auxiliary 0.2-2 parts.

9. A preparation method of the temperature self-adapting thermoplastic elastomer according to any one of claims 1-8, comprising the following steps: S1: mixing the hydrogenated copolymer of styrene-butadiene and the phase change material to obtain a premix; S2: mixing the premix and the remaining components, and then extruding and granulating through a double-screw extruder to obtain the temperature self-adapting thermoplastic elastomer.

10. Use of the temperature self-adapting thermoplastic elastomer according to any one of claims 1-8 in electric tools, wearable devices, medical hot compress devices, or building energy-saving devices.

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