Thermoplastic elastomer as well as preparation method and application thereof

Abstract

The invention discloses a thermoplastic elastomer as well as a preparation method and application thereof, and belongs to the technical field of high polymer materials. The thermoplastic elastomer added with the low-density filler simultaneously adopts the first styrene elastomer with the specific molecular weight and the second styrene elastomer with the specific molecular weight, so that the first styrene elastomer is utilized to provide good mechanical properties; the melt viscosity of the second styrene elastomer in the material preparation process is utilized to reduce the crushing degree of the low-density filler, so that the material has relatively low density and processability, and meanwhile, the material keeps relatively good mechanical properties; in addition, the specific reinforcing agent is added, so that the mechanical properties, such as elongation at break, of the material are better.

Description

Technical Field

[0001] The present application relates to the technical field of polymer materials, and in particular to a thermoplastic elastomer and a preparation method and application thereof. Background Art

[0002] In the field of contemporary materials science and industrial design, thermoplastic elastomer (TPE) has attracted wide attention due to its excellent performance. TPE combines the high elasticity of rubber with the thermoplastic processing characteristics of plastic, showing significant adaptability in the production and processing process, and providing excellent touch and durability in the final product. However, with the continuous upgrading of the market's requirements for lightweight materials, reducing the density of TPE has become a new direction for the development of the industry. The density of TPE can be reduced by adding low-density fillers, such as hollow glass microspheres. However, in order to obtain better mechanical properties, high molecular weight styrene elastomers are usually required, which makes the melt viscosity higher during the preparation of TPE, and the low-density filler is easy to break, which leads to poor lightweight effect. In addition, when the obtained material is used for encapsulation, the low-density filler is easy to suspend at the encapsulation interface, resulting in poor bonding performance. Generally, the melt viscosity in the preparation process of TPE is reduced by increasing the oil filling ratio, but this will lead to a significant reduction in mechanical properties. Therefore, it is urgent to develop a technology that enables TPE to have both low density and good mechanical properties, encapsulation properties and processing properties. Summary of the invention

[0003] Based on the defects of the prior art, the purpose of this application is to provide a thermoplastic elastomer and its preparation method and application, aiming to make the thermoplastic elastomer have lower density and better mechanical properties, encapsulation properties and processing properties.

[0004] In order to achieve the above object, in a first aspect, the present application provides a thermoplastic elastomer comprising the following components in parts by weight:

[0005] 7 to 20 parts of the first styrene elastomer,

[0006] 7 to 20 parts of the second styrene elastomer,

[0007] Plastic 0-20 parts,

[0008]

[0009] Wherein, 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 ;

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

[0013] A first styrene elastomer with a specific molecular weight and a second styrene elastomer with a specific molecular weight are added to the thermoplastic elastomer at the same time, wherein the first styrene elastomer can improve the mechanical properties of the material, such as hardness, tensile strength, elongation at break, etc.; the second styrene elastomer can not only reduce the melt viscosity in the preparation process of the thermoplastic elastomer, reduce the degree of crushing of low-density fillers, and ensure that the material has a lower density and better processing performance, but also help to reduce the amount of low-density fillers suspended at the encapsulation interface, improve the encapsulation performance, and at the same time enable the material to maintain good mechanical properties, such as tensile strength, elongation at break, etc.; a specific reinforcing agent is added, the specific reinforcing agent itself has a lower hardness, and its introduction will not increase the hardness of the material, and it itself has a higher strength, and at the same time has good compatibility with the styrene elastomer, so it can significantly improve the strength of the thermoplastic elastomer in the present invention without increasing the hardness.

[0014] The thermoplastic elastomer has low density, good mechanical properties (such as tensile strength, elongation at break, etc.) and processing properties, and is suitable for use in lightweight application scenarios, such as daily necessities, automobiles or personal protective equipment plastic parts.

[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 a range formed by 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 a range formed by any two of the above values.

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

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

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

[0020] The molecular weight distribution of the first styrene-based elastomer and the molecular weight distribution of the second styrene-based elastomer are measured by GPC.

[0021] Preferably, the weight percentage of styrene in the first styrene elastomer is 28% to 32%.

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

[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 measured using hydrogen nuclear magnetic resonance spectroscopy.

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

[0025] The density of the low-density filler is tested according to method B in the GB / T 533-2008 test standard at a test temperature of 23°C.

[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 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm or a range formed by any two of the above values.

[0027] The average particle size of the low-density filler is obtained 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 a range formed by 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 a range formed by 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 a range formed by 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 a range formed by 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 a range formed by 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 a range formed by 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 a range formed by any two of the above values.

[0035] In the thermoplastic elastomer, the weight ratio of the first styrene elastomer to the second styrene 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 a range formed by any two of the above values. Preferably, the weight ratio of the first styrene elastomer to the second styrene 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 a range formed by 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 as 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26% or a range formed by any two of the above values.

[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%, the reinforcing agent itself has higher crystallinity and molecular chain flexibility, higher tensile strength and elongation at break, and better compatibility with styrene elastomers.

[0039] The crystallinity of the reinforcing agent can be measured by the following method: firstly, the melting enthalpy of the sample is tested by a differential scanning calorimeter (for example, DSC204F1, NETZSCH, heating from 30°C to 230°C at a rate of 10°C / min, and then cooling from 230°C to 30°C at a rate of 10°C / min), and then the crystallinity is calculated according to the following formula:

[0040] Xc=ΔH / Hm

[0041] Where Xc is the crystallinity, %;

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

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

[0044] Preferably, the first styrene elastomer and the second styrene 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 / 2.16kg can be selected to be 10-100g / 10min, such as 10g / 10min, 15g / 10min, 20g / 10min, 25g / 10min, 30g / 10min, 35g / 10min, 40g / 10min, 45g / 10min, 50g / 10min, 55g / 10min, 60g / 10min, 65g / 10min, 70g / 10min, 75g / 10min, 80g / 10min, 85g / 10min, 90g / 10min, 95g / 10min, 100g / 10min, or a range formed by any two of the above values.

[0047] Preferably, the plasticizer comprises white oil.

[0048] Preferably, the auxiliary agent includes at least one of an antioxidant, a light stabilizer and a lubricant.

[0049] Preferably, the mass fraction of the first styrene elastomer in the thermoplastic elastomer is above 6%, such as 6%, 8%, 10%, 12%, 15%, 18%, 20% or a range formed by any two of the above values.

[0050] Without impairing the technical effect of the present application, other fillers and other additives, such as coupling agent activated calcium carbonate, can be added to the thermoplastic elastomer.

[0051] In a second aspect, the present application also provides a method for preparing the thermoplastic elastomer, which comprises the following steps: mixing the component raw materials except the low-density filler, adding them into a twin-screw extruder by main feeding, adding the low-density filler by side feeding, melt-extruding, granulating, and drying to obtain a thermoplastic elastomer.

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

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

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

[0055] In a third aspect, the present application provides the application of the thermoplastic elastomer in plastic parts of daily necessities. For example, the thermoplastic elastomer can be used as the coating of PP parts in daily necessities, such as the coating of toothbrushes.

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

[0057] (1) The thermoplastic elastomer of the present application simultaneously adds a first styrene elastomer with a specific molecular weight and a second styrene elastomer with a specific molecular weight, wherein 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, reduce the degree of crushing of the low-density filler, and ensure that the material has a lower density and better processing performance, but also help to reduce the amount of low-density filler suspended at the encapsulation interface, improve the encapsulation performance, and at the same time enable the material to maintain good mechanical properties; in addition, a specific reinforcing agent is added to make the mechanical properties of the material, such as elongation at break, better.

[0058] (2) The thermoplastic elastomer of the present application has low density, good mechanical properties, and good encapsulation properties, and is suitable for preparing plastic parts for daily necessities, etc. DETAILED DESCRIPTION

[0059] In order to better illustrate the purpose, technical scheme and advantages of the present application, the present application will be further described below in conjunction with specific embodiments and comparative examples, the purpose of which is to understand the content of the present application in detail, rather than to limit the present application. All other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application. The experimental reagents and instruments involved in the implementation of this application are all commonly used ordinary reagents and instruments unless otherwise specified. In the present application, the technical features described in an open manner include closed technical schemes composed of the listed features, and also include open technical schemes containing the listed features.

[0060] The raw materials used in the following examples and comparative examples are shown in Table 1, and unless otherwise specified, they are all commercially available raw materials. In addition, the component raw materials used in each parallel experiment are all of the same kind.

[0061] Table 1

[0062]

[0063]

[0064] Each of the following examples and comparative examples provides a thermoplastic elastomer, comprising the following steps: mixing the component raw materials except the low-density filler, adding them to a twin-screw extruder by main feeding, adding the low-density filler by side feeding, and after melt extrusion at 230° C., granulating, and drying to obtain the thermoplastic elastomer, wherein the twin-screw extruder has an aspect ratio of 56 / 1, and the side feeding port is located in the front section of the die head. The formulas of the thermoplastic elastomers of these examples and comparative examples are shown in Tables 2 and 3.

[0065] Table 2

[0066]

[0067] Table 3

[0068]

[0069]

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

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

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

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

[0074] Encapsulation performance: Injection molded on the surface of PP (grade HP500N, Sinopec) at 200°C, placed at 23°C for 48 hours, and then subjected to a 90° peel test at 23°C according to GB / T 7760-2003.

[0075] Table 4

[0076]

[0077]

[0078] It can be seen from the above data that the thermoplastic elastomers in each embodiment are lightweight, have good processing performance, high tensile strength and elongation at break, and good encapsulation performance. For example, the density is 0.785 g / cm 3 The melt index is above 26.5 g / 10 min, the tensile strength is above 1.8 MPa, the elongation at break is above 600%, and the peel adhesion strength to PP is above 2.8 kN / m.

[0079] In Comparative Examples 1 and 2, only high molecular weight styrene elastomer is added, and low molecular weight styrene elastomer is not added. The material density is high and the melt index is low, which is not conducive to achieving lightweight and processing.

[0080] In Comparative Example 3, only low molecular weight styrene elastomer is added without high molecular weight styrene elastomer. The mechanical properties of the material are biased, and the tensile strength and elongation at break are low.

[0081] In comparative example 4, no reinforcing agent was added, the mechanical properties of the material were biased, and the tensile strength and elongation at break were low; in comparative examples 6 and 7, other types of reinforcing agents were used, resulting in a low elongation at break of the material.

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

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

[0084] From the comparison between Examples 1 and 9 to 12, it can be seen that 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 solution of the present application rather than to limit the scope of protection of the present application. Although the present application has been described in detail with reference to the preferred embodiments, ordinary technicians in this field should understand that the technical solution of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present application.

Claims

1. A thermoplastic elastomer, characterized in that: Contains the following components in parts by weight: Wherein, the weight average molecular weight of the first styrene elastomer is 150,000 to 250,000; The weight average molecular weight of the second styrene elastomer is 40,000 to 100,000; The density of the low-density filler is 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.

2. The thermoplastic elastomer according to claim 1, characterized in that 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 according to claim 1, characterized in that The reinforcing agent is a crystalline thermoplastic elastomer with a crystallinity of 4% to 26%.

4. The thermoplastic elastomer according to claim 3, characterized in that The crystallinity of the reinforcing agent is 9% to 19%.

5. The thermoplastic elastomer according to claim 1, characterized in that At least one of the following conditions (1) to (5) is also met: (1) the first styrene-based elastomer and the second styrene-based elastomer each independently include at least one of a styrene-butadiene copolymer, a hydrogenated styrene-butadiene copolymer, a styrene-isoprene copolymer, a hydrogenated styrene-isoprene copolymer, and a polystyrene-poly(ethylene / ethylene / propylene)-polystyrene copolymer; (2) The low-density filler includes hollow glass microspheres; (3) The plastic includes at least one of polypropylene and polyethylene; (4) The plasticizer includes white oil; (5) The auxiliary agent includes at least one of an antioxidant, a light stabilizer and a lubricant.

6. A method for preparing a thermoplastic elastomer according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: mixing component raw materials except low-density filler, adding them into a twin-screw extruder through main feeding, adding low-density filler through side feeding, melt extruding, granulating, and drying to obtain a thermoplastic elastomer.

7. The method for preparing a thermoplastic elastomer according to claim 6, characterized in that: At least one of the conditions (6) to (8) is also satisfied: (6) The temperature of the melt extrusion is 160 to 230° C.; (7) The aspect ratio of the twin-screw extruder is 36 to 60 / 1; (8) The side feed port of the twin-screw extruder is located in the section before the die head.

8. Use of the thermoplastic elastomer according to any one of claims 1 to 5 in plastic parts for daily necessities, automobiles or personal protective equipment.

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