Glass fiber reinforced polypropylene diaphragm and preparation method thereof

Abstract

The invention relates to the technical field of high polymer materials, and particularly discloses a glass fiber reinforced polypropylene diaphragm and a preparation method thereof. The glass fiber reinforced polypropylene diaphragm provided by the invention is prepared from the following raw materials in parts by weight: 95-98 parts of polypropylene, 1-3 parts of glass fiber powder and 1-3 parts of a silane coupling agent. The glass fiber powder with specific particle size is uniformly dispersed in the polypropylene matrix, and the particle size and proportion of the glass fiber powder are optimally selected, so that the puncture strength performance of the traditional polypropylene diaphragm is greatly improved, the puncture strength of the polypropylene diaphragm is remarkably improved, and meanwhile, good electrical insulation performance is maintained; and the application range of the polypropylene diaphragm is expanded, so that the polypropylene diaphragm can adapt to a harsh use environment.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a glass fiber reinforced polypropylene membrane and its preparation method. Background Technology

[0002] The separator is a crucial component of batteries such as lithium-ion batteries. Located between the positive and negative electrodes, it isolates them and prevents short circuits and other accidents. Currently, the most commonly used mainstream lithium-ion battery separators are polyolefin separators, including two main categories: polyethylene (PE) and polypropylene (PP) separators. Compared to PP separators, PE separators have relatively poor heat resistance. Polypropylene separators are currently the most widely used lithium-ion battery separator material. They possess good mechanical strength, thermal stability, and corrosion resistance, while also exhibiting high electrochemical stability and isolation performance, effectively preventing internal short circuits.

[0003] However, current polypropylene separators still have some disadvantages, such as insufficient puncture resistance. During battery charge and discharge cycles, especially under fast charging or deep discharge conditions, lithium dendrites formed may puncture the separator. When the separator is punctured by lithium dendrites, the safety and reliability of the battery will be greatly reduced, as this may lead to internal short circuits and thermal runaway. Therefore, the puncture resistance of polypropylene separators is an important performance indicator for evaluating separator performance. Summary of the Invention

[0004] (a) Technical problems to be solved The technical problem to be solved by this invention is to improve the puncture strength of traditional polypropylene separators and enhance the safety and reliability of batteries.

[0005] (II) Technical Solution To address the aforementioned technical problems, in a first aspect, the present invention provides a glass fiber reinforced polypropylene separator, comprising the following raw materials in parts by weight: 95-98 parts polypropylene, 1-3 parts glass fiber powder, 1-3 parts silane coupling agent; The glass fiber has a particle size of 9~23μm.

[0006] As one embodiment of the present invention, the polypropylene includes polypropylene material with a melt index of 2.0 and / or polypropylene material with a melt index of 0.9.

[0007] As one embodiment of the present invention, the silane coupling agent is selected from any one or two of 3-aminopropyltriethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, and vinyltrimethoxysilane.

[0008] As one embodiment of the present invention, the silane coupling agent is selected from a mixture of 3-aminopropyltriethoxysilane and vinyltrimethoxysilane, or a mixture of 3-methacryloyloxypropyltrimethoxysilane and vinyltrimethoxysilane.

[0009] In one embodiment of the present invention, the silane coupling agent is a mixture of 3-aminopropyltriethoxysilane and vinyltrimethoxysilane.

[0010] Preferably, the mass ratio of 3-aminopropyltriethoxysilane to vinyltrimethoxysilane is (0.5~1.5):1. More preferably, the mass ratio of 3-aminopropyltriethoxysilane to vinyltrimethoxysilane is 1:1.

[0011] In one embodiment of the present invention, the silane coupling agent is a mixture of 3-methacryloxypropyltrimethoxysilane and vinyltrimethoxysilane. Preferably, the mass ratio of 3-methacryloxypropyltrimethoxysilane to vinyltrimethoxysilane is (0.5~1.5):1. More preferably, the mass ratio of 3-methacryloxypropyltrimethoxysilane to vinyltrimethoxysilane is 1:1.

[0012] In one embodiment of the present invention, the glass fiber reinforced polypropylene diaphragm has a thickness of 12~25μm.

[0013] Secondly, the present invention provides a method for preparing a glass fiber reinforced polypropylene separator, comprising the following steps: S1. Pretreatment of glass fiber powder; S2. The glass fiber powder obtained in S1 is mixed with a silane coupling agent for modification treatment to obtain modified glass fiber powder. S3. The modified glass fiber powder is premixed with polypropylene to obtain a premix; S4. The premixed material is heated and stirred to form a homogeneous blend, which is then extruded to obtain a cast film. The cast film is then subjected to composite stretching to obtain a glass fiber reinforced polypropylene diaphragm.

[0014] In one embodiment of the preparation method of the present invention, in step S4, the temperature of heating and blending is 180~200℃, and the temperature of extrusion processing is 220℃~230℃.

[0015] The present invention also provides an application of a glass fiber reinforced polypropylene separator in batteries.

[0016] The present invention further provides an application of a glass fiber reinforced polypropylene separator as a separator for lithium-ion batteries.

[0017] (III) Beneficial Effects The above-described technical solution of the present invention has the following advantages: This invention utilizes glass fiber powder of a specific particle size uniformly dispersed in a polypropylene matrix. By optimizing the particle size and ratio of the glass fiber powder, the puncture strength performance of traditional polypropylene diaphragms is greatly improved, significantly increasing the puncture strength of polypropylene diaphragms while maintaining good electrical insulation properties. This expands the application range of polypropylene diaphragms, enabling them to adapt to more demanding operating environments, especially in high-pressure environments. Attached Figure Description

[0018] Figure 1 The preparation process of the glass fiber polypropylene composite separator of the present invention is as follows. Detailed Implementation

[0019] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0020] Figure 1 This invention relates to a manufacturing process for a glass fiber reinforced polypropylene composite separator. The glass fiber reinforced polypropylene separator comprises the following raw materials in parts by weight: 95-98 parts polypropylene, 1-3 parts glass fiber powder, 1-3 parts silane coupling agent; The glass fiber powder has a particle size of 9~23μm.

[0021] As one embodiment of the present invention, the polypropylene includes polypropylene material with a melt index of 2.0 and / or polypropylene material with a melt index of 0.9.

[0022] As one embodiment of the present invention, the silane coupling agent is selected from any one or two of 3-aminopropyltriethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, and vinyltrimethoxysilane.

[0023] As one embodiment of the present invention, the silane coupling agent is selected from a mixture of 3-aminopropyltriethoxysilane and vinyltrimethoxysilane, or a mixture of 3-methacryloyloxypropyltrimethoxysilane and vinyltrimethoxysilane.

[0024] In one embodiment of the present invention, the silane coupling agent is a mixture of 3-aminopropyltriethoxysilane and vinyltrimethoxysilane. Preferably, the mass ratio of 3-aminopropyltriethoxysilane to vinyltrimethoxysilane is (0.5~1.5):1. More preferably, the mass ratio of 3-aminopropyltriethoxysilane to vinyltrimethoxysilane is 1:1.

[0025] In one embodiment of the present invention, the silane coupling agent is a mixture of 3-methacryloxypropyltrimethoxysilane and vinyltrimethoxysilane. Preferably, the mass ratio of 3-methacryloxypropyltrimethoxysilane to vinyltrimethoxysilane is (0.5~1.5):1. More preferably, the mass ratio of 3-methacryloxypropyltrimethoxysilane to vinyltrimethoxysilane is 1:1.

[0026] In one embodiment of the present invention, the glass fiber reinforced polypropylene diaphragm has a thickness of 12~25μm.

[0027] A method for preparing a glass fiber reinforced polypropylene separator, such as... Figure 1 As shown, it includes the following steps: S1. Pretreatment of glass fiber powder; S2. The glass fiber powder obtained in S1 is mixed with a silane coupling agent for modification treatment to obtain modified glass fiber powder. S3. The modified glass fiber powder is premixed with polypropylene to obtain a premix; S4. The premixed material is heated and stirred to form a homogeneous blend, which is then extruded to obtain a cast film. The cast film is then subjected to composite stretching to obtain a glass fiber reinforced polypropylene diaphragm.

[0028] In one embodiment of the preparation method of the present invention, in step S4, the temperature of heating and blending is 180~200℃, and the temperature of extrusion processing is 220℃~230℃.

[0029] All raw materials used in the following examples were commercially available and obtained through conventional purchase.

[0030] Example 1 This embodiment provides a glass fiber reinforced polypropylene separator, and the raw materials used in its preparation are as follows (in parts by weight): 97 parts of polypropylene with a melt flow index of 2.0; Two parts of glass fiber powder with a particle size of 9μm; 0.5 parts of 3-aminopropyltriethoxysilane; Vinyltrimethoxysilane 0.5 parts.

[0031] The method for preparing a glass fiber reinforced polypropylene separator provided by the present invention includes the following steps: S1. Pre-treat the glass fiber powder by washing and soaking it in water to remove dust and other impurities from the surface of the glass fiber powder. After treatment, use a hot air circulating drying oven to dry it thoroughly at a drying temperature of 125±5℃ for 2 hours to ensure that the glass fiber powder is dry and removes oil, moisture and other impurities. S2. The glass fiber powder obtained in S1 is modified by blending with 0.5 parts of 3-aminopropyltriethoxysilane and 0.5 parts of vinyltrimethoxysilane. Specifically, the mixture is impregnated and blended at room temperature (about 25°C) to obtain modified glass fiber powder. S3. Modified glass fiber powder is premixed with polypropylene to obtain a premix; S4. The premixed material is heated and mixed to form a homogeneous blend at a temperature of 185°C. The mixture is then extruded through a twin-screw extruder at a temperature of 228°C to produce a cast film with a thickness of approximately 14.7 μm. The resulting cast film is then subjected to composite stretching to obtain a stretched film with a thickness of 25 μm, which is the glass fiber reinforced polypropylene diaphragm of Example 1.

[0032] Example 2 This embodiment provides a glass fiber reinforced polypropylene membrane, and the raw materials used in its preparation are as follows (in parts by weight): 48 parts of polypropylene with a melt flow index of 2.0; 48 parts of polypropylene with a melt flow index of 0.8; Three parts of glass fiber powder with a particle size of 9μm; 0.5 parts of 3-methacryloyloxypropyltrimethoxysilane; Vinyltrimethoxysilane 0.5 parts.

[0033] The method for preparing a glass fiber reinforced polypropylene separator provided by the present invention includes the following steps: S1. Pre-treat the glass fiber powder by washing and soaking it in water to remove dust and other impurities from the surface of the glass fiber powder. After treatment, use a hot air circulating drying oven to dry it thoroughly at a drying temperature of 130±5℃ for 2 hours to ensure that the glass fiber powder is dry and removes oil, moisture and other impurities. S2. The glass fiber powder obtained in S1 is modified by blending with 0.5 parts of 3-methacryloyloxypropyltrimethoxysilane and 0.5 parts of vinyltrimethoxysilane. Specifically, the mixture is impregnated and blended at room temperature (about 25°C) to obtain modified glass fiber powder. S3. Modified glass fiber powder is premixed with polypropylene to obtain a premix; S4. The premixed material is heated and mixed to form a homogeneous blend at a temperature of 190°C. The mixture is then extruded through a twin-screw extruder at a temperature of 226°C to produce a cast film with a thickness of approximately 14.7 μm. The resulting cast film is then subjected to composite stretching to obtain a stretched film with a thickness of 25 μm, which is the glass fiber reinforced polypropylene diaphragm of Example 2.

[0034] Example 3 This embodiment provides a glass fiber reinforced polypropylene membrane, and the raw materials used in its preparation are as follows (in parts by weight): 49 parts of polypropylene with a melt flow index of 2.0; 49 parts of polypropylene with a melt flow index of 0.8; One part of glass fiber powder with a particle size of 9μm; 0.5 parts of 3-methacryloyloxypropyltrimethoxysilane; Vinyltrimethoxysilane 0.5 parts.

[0035] The method for preparing a glass fiber reinforced polypropylene separator provided by the present invention includes the following steps: S1. Pre-treat the glass fiber powder by washing and soaking it in water to remove dust and other impurities from the surface of the glass fiber powder. After treatment, use a hot air circulating drying oven to dry it thoroughly at a drying temperature of 135±5℃ for 2 hours to ensure that the glass fiber powder is dry and removes oil, moisture and other impurities. S2. The glass fiber powder obtained in S1 is modified by blending with 0.5 parts of 3-methacryloyloxypropyltrimethoxysilane and 0.5 parts of vinyltrimethoxysilane. Specifically, the mixture is impregnated and blended at room temperature (about 25°C) to obtain modified glass fiber powder. S3. Modified glass fiber powder is premixed with polypropylene to obtain a premix; S4. The premixed material is heated and mixed to form a homogeneous blend at a temperature of 195°C. The mixture is then extruded through a twin-screw extruder at a temperature of 227°C to produce a cast film with a thickness of approximately 14.7 μm. The resulting cast film is then subjected to composite stretching to obtain a stretched film with a thickness of 25 μm, which is the glass fiber reinforced polypropylene diaphragm of Example 3.

[0036] Example 4 This embodiment provides a glass fiber reinforced polypropylene membrane, and the raw materials used in its preparation are as follows (in parts by weight): 4.8 parts of polypropylene with a melt flow index of 2.0; 48 parts of polypropylene with a melt flow index of 0.8; Three parts of glass fiber powder with a particle size of 9μm; 1 part of vinyltrimethoxysilane.

[0037] The method for preparing a glass fiber reinforced polypropylene separator provided by the present invention includes the following steps: S1. Pre-treat the glass fiber powder by washing and soaking it in water to remove dust and other impurities from the surface of the glass fiber powder. After treatment, use a hot air circulating drying oven to dry it thoroughly at a drying temperature of 135±5℃ for 2 hours to ensure that the glass fiber powder is dry and removes oil, moisture and other impurities. S2. The glass fiber powder obtained in S1 is modified by blending with 1 part by mass of vinyltrimethoxysilane. Specifically, the glass fiber powder is obtained by impregnation and blending at room temperature (about 25°C). S3. Modified glass fiber powder is premixed with polypropylene to obtain a premix; S4. The premixed material is heated and mixed to form a homogeneous blend at a temperature of 200°C. The mixture is then extruded through a twin-screw extruder at a temperature of 230°C to produce a cast film with a thickness of approximately 14.7 μm. The resulting cast film is then subjected to composite stretching to obtain a stretched film with a thickness of 25 μm, which is the glass fiber reinforced polypropylene diaphragm of Example 4.

[0038] Comparative Example 1 This comparative example provides a conventional polypropylene separator, prepared from the following raw materials in parts by weight: 50 parts of polypropylene with a melt flow index of 2.0; 50 parts of polypropylene with a melt flow index of 0.8.

[0039] The conventional method for preparing a polypropylene membrane includes the following steps: The raw materials are heated and blended to form a homogeneous blend, which is then extruded through a twin-screw extruder at a temperature of 228°C to produce a cast film with a thickness of approximately 14.7 μm. After composite stretching, a stretched film with a thickness of 25 μm is finally obtained, which is the conventional polypropylene separator of this comparative example.

[0040] The high-performance diaphragms prepared in Examples 1-4 and Comparative Example 1 were subjected to key physicochemical properties tests according to the national standard method GB / T36363-2018, specifically testing the diaphragm thickness, tensile strength, and puncture strength. In addition, the membrane rupture temperature of the prepared diaphragms was tested using a thermomechanical analyzer under a test tensile force of 0.02N. The test diaphragm samples were 1cm in length and 0.5cm in width. The test results are shown in the table below.

[0041] As shown in the table above, a comparison of Examples 1, 2, 3, and 4 with Comparative Example 1 reveals that blending polypropylene raw material with glass fiber powder modified by silane coupling agent can enhance the puncture resistance of the composite diaphragm to a certain extent, while also improving the tensile strength of the glass fiber polypropylene composite diaphragm to a certain degree.

[0042] A comparison of Examples 1, 2, 3 and Example 4 shows that the polypropylene reinforced with glass fiber powder modified by mixing two silane coupling agents exhibits better puncture resistance and tensile strength as well as a higher film breaking temperature. This indicates that the effect of reinforcing polypropylene with glass fiber powder modified by mixing two silane coupling agents is better.

[0043] It should be noted that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. For the embodiments of the method, relevant parts can be referred to the description of the device embodiments (as appropriate). The present invention is not limited to the specific steps and structures described above and shown in the figures. Furthermore, for the sake of brevity, detailed descriptions of known methods and techniques are omitted here.

[0044] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A glass fiber reinforced polypropylene separator, characterized in that, The ingredients include the following parts by weight: 95-98 parts polypropylene, 1-3 parts glass fiber powder, 1-3 parts silane coupling agent; The glass fiber powder has a particle size of 9~23μm.

2. The polypropylene separator as described in claim 1, characterized in that, The polypropylene includes polypropylene material with a melt index of 2.0 and / or polypropylene material with a melt index of 0.

9.

3. The polypropylene separator as described in claim 1, characterized in that, The silane coupling agent is selected from any one or two of 3-aminopropyltriethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, and vinyltrimethoxysilane.

4. The polypropylene separator as described in claim 1, characterized in that, The silane coupling agent is selected from a mixture of 3-aminopropyltriethoxysilane and vinyltrimethoxysilane, or a mixture of 3-methacryloyloxypropyltrimethoxysilane and vinyltrimethoxysilane.

5. The polypropylene separator as described in claim 4, characterized in that, The silane coupling agent is a mixture of 3-aminopropyltriethoxysilane and vinyltrimethoxysilane, wherein the mass ratio of 3-aminopropyltriethoxysilane to vinyltrimethoxysilane is (0.5~1.5):1; or, the silane coupling agent is a mixture of 3-methacryloyloxypropyltrimethoxysilane and vinyltrimethoxysilane, wherein the mass ratio of 3-methacryloyloxypropyltrimethoxysilane to vinyltrimethoxysilane is (0.5~1.5):

1.

6. The polypropylene separator as described in claim 1, characterized in that, The thickness of the glass fiber reinforced polypropylene diaphragm is 12~25μm.

7. A method for preparing a glass fiber reinforced polypropylene separator as described in any one of claims 1 to 6, characterized in that, Includes the following steps: S1. Pretreatment of glass fiber powder; S2. The glass fiber powder obtained in S1 is mixed with a silane coupling agent for modification treatment to obtain modified glass fiber powder. S3. The modified glass fiber powder is premixed with polypropylene to obtain a premix; S4. The premixed material is heated and stirred to form a homogeneous blend, which is then extruded to obtain a cast film. The cast film is then subjected to composite stretching to obtain a glass fiber reinforced polypropylene diaphragm.

8. The preparation method according to claim 7, characterized in that, In step S4, the extrusion temperature is 220°C to 230°C.

9. The application of the glass fiber reinforced polypropylene separator according to any one of claims 1-6 in batteries.

10. The application of a glass fiber reinforced polypropylene separator according to any one of claims 1-6 as a separator for lithium-ion batteries.

Images