Thermoplastic elastomer and preparation method and application thereof

Abstract

The application discloses a thermoplastic elastomer and a preparation method and application thereof, and belongs to the technical field of polymer materials. The application adopts a first styrene-based elastomer with a specific molecular weight and a second styrene-based elastomer with a specific molecular weight to the thermoplastic elastomer with low-density fillers, so that the first styrene-based elastomer is used to provide good mechanical properties, the second styrene-based elastomer is used to reduce the breaking degree of the low-density fillers by the melt viscosity in the material preparation process, the material has low density and processing performance, and the material maintains good mechanical properties; in addition, a specific reinforcing agent is added, so that the mechanical properties, such as elongation at break, of the material are better.

Description

Technical Field

[0001] This application relates to the field of polymer materials technology, specifically to a thermoplastic elastomer and its preparation method and application. Background Technology

[0002] In the fields of contemporary materials science and industrial design, thermoplastic elastomers (TPEs) have garnered widespread attention due to their superior performance. TPEs combine the high elasticity of rubber with the thermoplastic processing characteristics of plastics, exhibiting remarkable adaptability in production and processing, and providing excellent tactile feel and durability in the final product. However, with the market's ever-increasing demands for lightweight materials, reducing the density of TPEs has become a new direction for industry development. Adding low-density fillers, such as hollow glass microspheres, can reduce the density of TPEs. However, to obtain better mechanical properties, high molecular weight styrene-based elastomers are usually required, which results in high melt viscosity during TPE preparation. This makes the low-density fillers prone to breakage, leading to poor lightweighting. Furthermore, when the resulting material is used for overmolding, the low-density fillers tend to float at the overmolding interface, resulting in poor adhesion. Generally, increasing the oil-to-fill ratio reduces the melt viscosity during TPE preparation, but this leads to a significant decrease in mechanical properties. Therefore, there is an urgent need to develop a technology that allows TPEs to simultaneously possess low density and good mechanical, overmolding, and processing properties. Summary of the Invention

[0003] Based on the deficiencies of the existing technology, the purpose of this application is to provide a thermoplastic elastomer, its preparation method and application, which aims to enable the thermoplastic elastomer to simultaneously possess low density and good mechanical properties, overmolding properties and processing properties.

[0004] To achieve the above objectives, in a first aspect, this application provides a thermoplastic elastomer comprising the following components in parts by weight:

[0005] 7-20 parts of the first type of styrene elastomer.

[0006] 7-20 parts of the second type of styrene elastomer

[0007] Plastic 0-20 parts,

[0008]

[0009] The weight-average molecular weight of the first styrene elastomer is 150,000 to 250,000.

[0010] The weight-average molecular weight of the second styrene elastomer is 40,000 to 100,000;

[0011] The density of the low-density filler is 0.25-0.35 g / cm³.3 ;

[0012] The reinforcing agent is at least one of ethylene octene copolymer, ethylene butene copolymer, and acrylonitrile octene copolymer.

[0013] The thermoplastic elastomer contains both a first styrene-based elastomer and a second styrene-based elastomer of a specific molecular weight. The first styrene-based elastomer improves the mechanical properties of the material, such as hardness, tensile strength, and elongation at break. The second styrene-based elastomer not only reduces the melt viscosity during the thermoplastic elastomer preparation process and mitigates the breakage of low-density fillers, ensuring the material has low density and good processing performance, but also helps reduce the amount of low-density fillers suspended at the overmolding interface, improving overmolding performance. Simultaneously, it helps the material maintain good mechanical properties, such as tensile strength and elongation at break. A specific reinforcing agent is added. This reinforcing agent itself has low hardness, and its introduction will not increase the material's hardness. Furthermore, it possesses high strength and good compatibility with the styrene-based elastomer. Therefore, it can significantly improve the strength of the thermoplastic elastomer in this invention without increasing hardness.

[0014] The thermoplastic elastomer possesses low density, good mechanical properties (such as tensile strength and elongation at break), and good processing performance, making it suitable for use in lightweight applications, such as plastic parts for daily necessities, automobiles, or personal protective equipment.

[0015] The weight-average molecular weight of the first styrene elastomer is 150,000 to 250,000, such as 150,000, 160,000, 170,000, 180,000, 190,000, 200,000, 210,000, 220,000, 230,000, 240,000, 250,000, or any two of the above values.

[0016] The weight-average molecular weight of the second styrene elastomer is 40,000 to 100,000, such as 40,000, 50,000, 60,000, 70,000, 80,000, 90,000, 100,000, or any two of the above values.

[0017] The weight-average molecular weight of the first styrene elastomer and the weight-average molecular weight of the second styrene elastomer can be determined by the following method: according to the test standard GB / T 21864-2008.

[0018] Preferably, the molecular weight distribution of the first styrene elastomer is 1.00 to 1.18.

[0019] Preferably, the molecular weight distribution of the second styrene elastomer is 1.00 to 1.18.

[0020] The molecular weight distributions of the first styrene elastomer and the second styrene elastomer were measured using GPC.

[0021] Preferably, the styrene content in the first styrene-based elastomer is 28% to 32% by weight.

[0022] Preferably, the styrene content in the second styrene elastomer is 28% to 32% by weight.

[0023] The weight percentage of styrene in the first styrene-based elastomer and the weight percentage of styrene in the second styrene-based elastomer can both be determined by proton nuclear magnetic resonance spectroscopy.

[0024] The density of the low-density filler is 0.25-0.35 g / cm³. 3 For example, 0.25g / cm 3 0.27g / cm 3 0.30g / cm 3 0.32g / cm 3 0.35g / cm 3 The range formed by any two of the above values.

[0025] The density of the low-density filler was tested according to Method B in GB / T 533-2008 test standard at a test temperature of 23℃.

[0026] Preferably, the average particle size of the low-density filler is 10–45 μm. For example, the average particle size of the low-density filler is within the range of any two of the following values: 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm.

[0027] The average particle size of the low-density filler was determined by electron microscopy.

[0028] In the thermoplastic elastomer, the first styrene elastomer is 7 to 20 parts by weight, such as 7 parts by weight, 10 parts by weight, 12 parts by weight, 14 parts by weight, 16 parts by weight, 18 parts by weight, 20 parts by weight, or any two of the above values.

[0029] In the thermoplastic elastomer, the second styrene elastomer is 7 to 20 parts by weight, such as 7 parts by weight, 10 parts by weight, 12 parts by weight, 14 parts by weight, 16 parts by weight, 18 parts by weight, 20 parts by weight, or any two of the above values.

[0030] In the thermoplastic elastomer, the plastic is 0 to 20 parts by weight, such as 0 parts by weight, 2 parts by weight, 4 parts by weight, 6 parts by weight, 8 parts by weight, 10 parts by weight, 12 parts by weight, 14 parts by weight, 16 parts by weight, 18 parts by weight, 20 parts by weight, or any two of the above values.

[0031] In the thermoplastic elastomer, the low-density filler is 5 to 15 parts by weight, such as 5 parts by weight, 7 parts by weight, 10 parts by weight, 12 parts by weight, 14 parts by weight, 15 parts by weight, or any two of the above values.

[0032] In the thermoplastic elastomer, the plasticizer is 40 to 60 parts by weight, such as 40 parts by weight, 42 parts by weight, 44 parts by weight, 46 parts by weight, 48 parts by weight, 50 parts by weight, 52 parts by weight, 54 parts by weight, 56 parts by weight, 58 parts by weight, 60 parts by weight, or any two of the above values.

[0033] In the thermoplastic elastomer, the reinforcing agent is 1 to 10 parts by weight, such as 1 part by weight, 2 parts by weight, 4 parts by weight, 6 parts by weight, 8 parts by weight, 10 parts by weight, or any two of the above values.

[0034] In the thermoplastic elastomer, the additive is 0 to 1 part by weight, such as 0 part by weight, 0.2 part by weight, 0.4 part by weight, 0.6 part by weight, 0.8 part by weight, 1 part by weight, or any two of the above values.

[0035] In the thermoplastic elastomer, the weight ratio of the first styrene-based elastomer to the second styrene-based elastomer is (0.35–2.86):1, such as 0.35:1, 0.5:1, 0.7:1, 1:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1, 2:1, 2.1:1, 2.3:1, 2.5:1, 2.7:1, 2.86:1, or any two of the above values. Preferably, the weight ratio of the first styrene-based elastomer to the second styrene-based elastomer is (0.7–1.5):1, such as 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.5:1, or any two of the above values, which is more conducive to achieving a balance between melt viscosity and elongation at break.

[0036] Preferably, the crystallinity of the reinforcing agent is 4% to 26%. The crystallinity of the reinforcing agent can be selected from any two values ​​of 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, or more.

[0037] More preferably, the crystallinity of the reinforcing agent is 9% to 19%.

[0038] When the crystallinity of the reinforcing agent is 4% to 26%, especially 9% to 19%, it has higher crystallinity and molecular chain flexibility, resulting in higher tensile strength and elongation at break, and better compatibility with styrene-based elastomers.

[0039] The crystallinity of the reinforcing agent can be determined by the following method: First, the enthalpy of melting of the sample is tested using 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). Then, the crystallinity is calculated according to the following formula:

[0040] Xc=ΔH / Hm

[0041] In the formula, Xc represents the degree of crystallinity, in %.

[0042] ΔH is the enthalpy of melting of the sample, J / g;

[0043] Hm is the standard enthalpy of the sample, J / g (the standard enthalpy of vinyl elastomer is 293 J / g, and the standard enthalpy of propylene elastomer is 177 J / g).

[0044] Preferably, the first styrene-based elastomer and the second styrene-based elastomer each independently include at least one of styrene-butadiene copolymer, hydrogenated styrene-butadiene copolymer, styrene-isoprene copolymer, hydrogenated styrene-isoprene copolymer, and polystyrene-poly(ethylene / ethylene / propylene)-polystyrene copolymer.

[0045] Preferably, the low-density filler comprises hollow glass microspheres.

[0046] Preferably, the plastic comprises at least one of polypropylene and polyethylene. The melt flow rate of the plastic at 190°C / 2.16 kg can be selected to be 10–100 g / 10 min, such as 10 g / 10 min, 15 g / 10 min, 20 g / 10 min, 25 g / 10 min, 30 g / 10 min, 35 g / 10 min, 40 g / 10 min, 45 g / 10 min, 50 g / 10 min, 55 g / 10 min, 60 g / 10 min, 65 g / 10 min, 70 g / 10 min, 75 g / 10 min, 80 g / 10 min, 85 g / 10 min, 90 g / 10 min, 95 g / 10 min, 100 g / 10 min, or any two of the above values.

[0047] Preferably, the plasticizer comprises white oil.

[0048] Preferably, the additives include at least one of antioxidants, light stabilizers, and lubricants.

[0049] Preferably, the mass fraction of the first styrene-based elastomer in the thermoplastic elastomer is 6% or more, such as 6%, 8%, 10%, 12%, 15%, 18%, 20%, or any two of these values ​​forming a range.

[0050] Without compromising the technical effect of this application, other fillers and additives, such as coupling agents to activate calcium carbonate, may be added to the thermoplastic elastomer.

[0051] Secondly, this application also provides a method for preparing the thermoplastic elastomer, which includes the following steps: mixing raw materials other than low-density filler, adding them to a twin-screw extruder by main feeding, adding low-density filler by side feeding, melt extrusion, granulation, drying, and obtaining thermoplastic elastomer.

[0052] Preferably, the temperature of the melt extrusion is 160–230°C.

[0053] Preferably, the length-to-diameter ratio of the twin-screw extruder is 36 to 60 / 1.

[0054] Preferably, the side feed port of the twin-screw extruder is located one section before the die head.

[0055] Thirdly, this application provides the application of the thermoplastic elastomer in plastic parts of daily necessities. For example, the thermoplastic elastomer can be used for overmolding PP parts in daily necessities, such as toothbrushes.

[0056] Compared with the prior art, the beneficial effects of this application are as follows:

[0057] (1) The thermoplastic elastomer of this application simultaneously adds a first styrene elastomer of a specific molecular weight and a second styrene elastomer of a specific molecular weight. The first styrene elastomer can improve the mechanical properties of the material. The second styrene elastomer can not only reduce the melt viscosity during the preparation of the thermoplastic elastomer and reduce the degree of breakage of low-density fillers, ensuring that the material has a lower density and better processing performance, but also help reduce the amount of low-density fillers suspended at the overmolding interface, improve the overmolding performance, and at the same time maintain the material with good mechanical properties. In addition, a specific reinforcing agent is added to make the mechanical properties of the material, such as elongation at break, even better.

[0058] (2) The thermoplastic elastomer of this application has low density, good mechanical properties, and good overmolding performance, and is suitable for manufacturing plastic parts for daily necessities, etc. Detailed Implementation

[0059] To better illustrate the purpose, technical solutions, and advantages of this application, the following description, in conjunction with specific embodiments and comparative examples, aims to provide a detailed understanding of the content of this application, rather than limiting it. All other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of this application. Unless otherwise specified, the experimental reagents and instruments involved in the implementation of this application are commonly used reagents and instruments. In this application, the technical features described in an open-ended manner include both closed-ended technical solutions composed of the listed features and open-ended technical solutions that include the listed features.

[0060] The raw materials used in the following embodiments and comparative examples are shown in Table 1, and unless otherwise specified, all raw materials are commercially available. Furthermore, the same raw materials were used in each parallel experiment.

[0061] Table 1

[0062]

[0063]

[0064] The following examples and comparative examples all provide a thermoplastic elastomer, comprising the following steps: mixing raw materials other than low-density filler, adding them to a twin-screw extruder via main feeding, adding the low-density filler via side feeding, melting and extruding at 230°C, granulating, and drying to obtain the thermoplastic elastomer. The twin-screw extruder has a length-to-diameter ratio of 56 / 1, and the side feed port is located one section before the die head. The formulations of the thermoplastic elastomers in these examples and comparative examples are shown in Tables 2 and 3.

[0065] Table 2

[0066]

[0067] Table 3

[0068]

[0069]

[0070] The thermoplastic elastomers of the above embodiments and comparative examples were subjected to the following performance tests, and the test results are shown in Table 4.

[0071] Density: Tested according to GB / T 533-2008 test standard, method B, temperature 23℃;

[0072] Melt flow rate: Tested according to GB / T 3682.1-2018 test standard, temperature 190℃, load 2.16kg;

[0073] Tensile strength and elongation at break: Tested according to GB / T 528-2009 test standard, temperature 23℃, dumbbell shape type 1;

[0074] Overmolding performance: Injected onto the surface of PP (grade HP500N, Sinopec) at 200℃, and after being placed at 23℃ for 48 hours, a 90° peel test was conducted at 23℃ according to GB / T 7760-2003.

[0075] Table 4

[0076]

[0077]

[0078] The data above shows that the thermoplastic elastomers in each embodiment are lightweight, have good processability, high tensile strength and elongation at break, and good overmolding properties, such as a density of 0.785 g / cm³. 3 The following properties are required: melt index above 26.5 g / 10 min, tensile strength above 1.8 MPa, elongation at break above 600%, and peel bond strength to PP above 2.8 kN / m.

[0079] Comparative Examples 1 and 2 only added high molecular weight styrene-based elastomers and did not add low molecular weight styrene-based elastomers. The materials had higher density and lower melt index, which is not conducive to achieving lightweighting and processing.

[0080] Comparative Example 3 only added low molecular weight styrene-based elastomers and did not add high molecular weight styrene-based elastomers, resulting in deviations in the mechanical properties of the material, with lower tensile strength and elongation at break.

[0081] Comparative Example 4, which did not contain any reinforcing agent, exhibited poor mechanical properties, with low tensile strength and elongation at break. Comparative Examples 6 and 7, which used other types of reinforcing agents, resulted in low elongation at break.

[0082] Comparative Example 5 uses a high oil-filling ratio to reduce the melt viscosity of the material, but the mechanical properties are deviated, such as low tensile strength and elongation at break, and the overmolding performance is also deviated.

[0083] As can be seen from the comparison of Examples 1, 5 to 8, when the weight ratio of the first styrene elastomer to the second styrene elastomer is in the range of (0.7 to 1.5):1, the melt viscosity and elongation at break are better balanced.

[0084] As can be seen from the comparison of Examples 1, 9-12, when the crystallinity of the reinforcing agent is in the range of 9% to 19%, the mechanical properties are better, and the tensile strength and elongation at break are higher.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit the scope of protection of this application. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the substance and scope of the technical solutions of this application.

Claims

1. A thermoplastic elastomer, characterized by, Components comprising the following parts by weight: First styrene-based elastomer 7~20 parts, Second styrene-based elastomer 7~20 parts, Plastic 0~20 parts, Low-density filler 5~15 parts, Plasticizer 40~60 parts, Reinforcing agent 1~10 parts, Auxiliary agent 0~1 part; Wherein, the weight average molecular weight of the first styrene-based elastomer is 150~250 thousand; The weight average molecular weight of the second styrene-based elastomer is 40~100 thousand; The low density filler has a density of 0.25-0.35 g / cm 3 ; The reinforcing agent is at least one of ethylene octene copolymer, ethylene butene copolymer, and propylene octene copolymer; The crystallinity of the reinforcing agent is 9%~26%; The plastic is at least one of polypropylene and polyethylene.

2. The thermoplastic elastomer of claim 1, wherein The weight ratio of the first styrene-based elastomer to the second styrene-based elastomer is (0.7~1.5):

1.

3. The thermoplastic elastomer of claim 1, wherein, The crystallinity of the reinforcing agent is 9%~19%.

4. The thermoplastic elastomer of claim 1, wherein, At least one of conditions (1)~(4) is also met: (1) The first styrene-based elastomer and the second styrene-based elastomer each independently include at least one of styrene-butadiene copolymer, hydrogenated copolymer of styrene-butadiene, styrene-isoprene copolymer, hydrogenated copolymer of styrene-isoprene, and polystyrene-poly(ethylene / ethylene / propylene)-polystyrene copolymer; (2) The low-density filler includes hollow glass microbeads; (3) The plasticizer includes white oil; (4) The auxiliary agent includes at least one of antioxidants, light stabilizers, and lubricants.

5. A process for the preparation of a thermoplastic elastomer as claimed in any one of claims 1 to 4, characterized in that The method comprises the following steps: mixing raw materials of components except for low-density filler, adding into a twin-screw extruder through a main feeding mode, and adding low-density filler through a side feeding mode, melt extruding, granulating, drying, and obtaining a thermoplastic elastomer.

6. The method of preparing a thermoplastic elastomer according to claim 5, wherein At least one of conditions (5)~(7) is also met: (5) The temperature of the melt extrusion is 160~230℃; (6) The length-diameter ratio of the twin-screw extruder is 36~60 / 1; (7) The side feeding port of the twin-screw extruder is located one section before the head.

7. Use of the thermoplastic elastomer according to any one of claims 1~4 in plastic parts of daily necessities, automobiles, or personal protective equipment.

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