Basalt fiber composite material for mobile phone shell and preparation method thereof

Abstract

The application provides a basalt fiber composite material for a mobile phone shell and a preparation method thereof. The composite material is prepared by hot-pressing molding of multilayer basalt fiber fabric prepreg. The basalt fiber fabric prepreg is prepared by coating epoxy resin glue solution on both sides of basalt fiber fabric and then baking to form a film. The epoxy resin glue solution comprises 100 parts of epoxy resin, 20-40 parts of imidazole-based polyamide acid and 10-25 parts of a curing agent by weight. The basalt fiber composite material for a mobile phone shell and the preparation method thereof have excellent high mechanical strength and toughness, and the overall wear resistance is also excellent, and the basalt fiber composite material can be applied to a mobile phone shell.

Description

Technical Field

[0001] This invention relates to the field of mobile phone casing technology, and in particular to a basalt fiber composite material for mobile phone casings and its preparation method. Background Technology

[0002] Since the birth of the mobile phone, its appearance has undergone tremendous changes, and the mainstream materials used for its casing have also changed several times. Currently, the main materials for mobile phone casings are metal, plastic, and glass. Among them, while metal casings have advantages such as drop resistance, high plasticity, and good heat dissipation, their significant signal shielding effect has become a key factor restricting their development. For the sake of lightweighting and ease of manufacturing, mobile phone casings can also be made of plastic. However, plastic casings are manufactured through integrated injection molding and compression molding processes, and the main problem is that their visual appearance and texture are poor. Glass casings mainly employ processes such as opening, fine carving, polishing, tempering, printing, and film application. 3D glass requires a graphite furnace hot bending process before tempering, which is a key factor affecting product yield.

[0003] Currently, when selecting materials for mobile phone casings, continuous fiber cloth is used as a reinforcing layer, with resin adhesive coated on both sides. After curing, multiple layers are hot-pressed to obtain a composite material for mobile phone casings. However, in practical applications, the wear resistance and toughness of existing composite materials cannot meet the required standards, and the strength of the casing cannot be guaranteed. Summary of the Invention

[0004] Based on the technical problems existing in the background technology, the present invention proposes a basalt fiber composite material for mobile phone casing and its preparation method. The composite material has excellent high mechanical strength and toughness, and its overall wear resistance is also relatively good, so it can be used as a mobile phone casing.

[0005] The present invention proposes a basalt fiber composite material for mobile phone casings, which is obtained by hot pressing of multi-layer basalt fiber fabric prepreg.

[0006] The basalt fiber fabric prepreg is prepared by coating both sides of the basalt fiber fabric with epoxy resin and then baking it into a film.

[0007] The epoxy resin adhesive comprises, by weight, 100 parts epoxy resin, 20-40 parts imidazole polyamic acid, and 10-25 parts curing agent.

[0008] In this invention, basalt fiber fabric is used as a reinforcing layer, and epoxy resin is coated on both sides. After curing, a prepreg is prepared. The prepreg is then hot-pressed and laminated with multiple layers to obtain the basalt fiber composite material for mobile phone casings. This invention utilizes the strength of basalt fiber and the cured resin to meet the requirements of dimensional stability, high strength and high toughness of mobile phone casing products, while maintaining wear resistance under the condition of meeting strength and toughness requirements.

[0009] Preferably, the epoxy resin content in the basalt fiber fabric prepreg is 30-50 wt%.

[0010] Preferably, the epoxy resin is at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, or bisphenol S type epoxy resin;

[0011] Preferably, the epoxy value of the epoxy resin is 0.3-0.7.

[0012] Preferably, the imidazole-containing polyamic acid is obtained by polycondensation of an imidazole diamine monomer and a dianhydride monomer;

[0013] Preferably, the molar ratio of the imidazole diamine monomer to the dianhydride monomer is 1:0.9-1.1.

[0014] Preferably, the imidazole diamine monomer is at least one of 2-(3-aminophenyl)-5-aminobenzimidazole or 2-(4-aminophenyl)-5-aminobenzimidazole; the dianhydride monomer is at least one of 4,4′-(hexafluoroisopropene)phthalic anhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, dicyclohexyl-3,4,3',4'-tetracarboxylic dianhydride or pyromellitic anhydride.

[0015] In this invention, imidazole-containing polyamic acid is used as a curing agent, which not only enables effective curing of epoxy resin, but also allows the imidazole groups to form additional curing, which helps to obtain a cross-linked network structure resin curing layer and further improves the mechanical properties of the cured epoxy resin.

[0016] Preferably, the curing agent is at least one selected from 4,4'-diaminodiphenylmethane, 4,4'-diaminophenyl sulfone, dicyandiamide, phthalic anhydride, ethylenediamine, or dimethylaminophenol.

[0017] Preferably, the basalt fiber fabric is a surface-modified basalt fiber fabric;

[0018] Preferably, the surface-modified basalt fiber fabric is obtained by impregnating basalt fabric with an epoxy coupling agent solution.

[0019] Preferably, the epoxy coupling agent solution is obtained by adding an epoxy coupling agent to an aqueous acetic acid solution, and the content of the epoxy coupling agent is 0.1-1 wt%.

[0020] Preferably, the basalt fiber fabric is at least one of basalt fiber cloth, basalt fiber woven fabric, basalt fiber composite cloth, or basalt fiber felt.

[0021] In this invention, to improve the adhesion between basalt fiber fabric and epoxy resin adhesive, the basalt fiber fabric is first impregnated with an epoxy coupling agent solution before being coated with epoxy resin adhesive. This grafts epoxy groups onto the surface of the basalt fiber fabric. Subsequently, a resin adhesive containing epoxy resin, imidazole-containing polyamic acid, and a curing agent is applied. Because the imidazole groups and epoxy groups in the imidazole-containing polyamic acid can undergo ring-opening bonding, the imidazole-containing polyamic acid can adhere to the basalt fiber fabric. Therefore, during the subsequent curing of the epoxy resin, the resulting cured resin adhesive layer firmly adheres to the surface of the basalt fiber fabric, enhancing the mechanical interlocking between the basalt fiber fabric and the epoxy resin. Without affecting the strength performance, this further enhances the toughness and wear resistance of the basalt fiber fabric, contributing to the obtaining of a high-performance mobile phone casing.

[0022] This invention also proposes a method for preparing the above-mentioned basalt fiber composite material for mobile phone casings, comprising the following steps:

[0023] S1. Mix 100 parts of epoxy resin, 20-40 parts of imidazole polyamic acid and 10-25 parts of curing agent by weight to obtain epoxy resin solution.

[0024] S2. The epoxy resin solution is coated on both sides of the basalt fiber fabric, and after baking, a basalt fiber fabric prepreg is obtained.

[0025] S3. After stacking multiple layers of the basalt fiber fabric prepreg and hot-pressing them, the basalt fiber composite material for the mobile phone casing is obtained.

[0026] Preferably, in step S1, the mixing temperature is 40-60℃; in step S2, the baking temperature is 90-130℃ and the time is 1-10 min; in step S3, the hot pressing temperature is 150-200℃ and the pressure is 5-15 MPa.

[0027] This invention discloses a basalt fiber composite material for mobile phone casings and its preparation method. The composite material not only has high wear resistance, but also excellent mechanical strength and toughness. Detailed Implementation

[0028] The technical solution of the present invention will be described in detail below through specific embodiments. However, it should be clearly stated that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0029] Example 1

[0030] A basalt fiber composite material for mobile phone casings, the preparation method of which includes the following steps:

[0031] (1) γ-glycidoxypropyltrimethoxysilane was added to an acetic acid solution (concentration 1 wt%) and stirred to dissolve, yielding an epoxy coupling agent solution, wherein the content of γ-glycidoxypropyltrimethoxysilane was 0.5 wt%; basalt fiber cloth (plain weave, diameter 13 μm, areal density 300 g / m²) was used. 2 The basalt fiber cloth (0.15 mm thick) was impregnated in the epoxy coupling agent solution. The mass ratio of the basalt fiber cloth to the epoxy coupling agent solution was 1:20. After ultrasonic treatment at 50°C (300 W power) for 2 hours, the basalt fiber cloth was taken out and vacuum dried to obtain the surface modified basalt fiber cloth.

[0032] (2) 2-(3-aminophenyl)-5-aminobenzimidazole was dissolved completely in N-methylpyrrolidone. Under nitrogen protection, an equimolar amount of 4,4′-(hexafluoroisopropene)phthalic anhydride was added. After stirring at room temperature for 3 hours, a large amount of methanol was added to precipitate the mixture, resulting in imidazole-containing polyamic acid. Bisphenol A type epoxy resin (E-51), imidazole-containing polyamic acid, and 4,4′-diaminodiphenylmethane were stirred and mixed at 50°C. The mass ratio of bisphenol A type epoxy resin (E-51), imidazole-containing polyamic acid, and 4,4′-diaminodiphenylmethane was 100:30:15 to obtain an epoxy resin solution. The epoxy resin solution was coated on both sides of the surface-modified basalt fiber cloth and cured at a heating rate of 5°C / min to 110°C to obtain a basalt fiber cloth prepreg. The content of the resin solution was 40 wt%.

[0033] (3) The three layers of basalt fiber cloth prepreg are stacked and hot-pressed. The hot-pressing temperature is 170°C and the pressure is 10MPa. After cutting and shaping, the basalt fiber composite material for mobile phone casing is obtained.

[0034] Example 2

[0035] A basalt fiber composite material for mobile phone casings, the preparation method of which includes the following steps:

[0036] (1) Add γ-glycidoxypropyltrimethoxysilane to an acetic acid solution (concentration 1wt%) and stir to dissolve to obtain an epoxy coupling agent solution, wherein the content of γ-glycidoxypropyltrimethoxysilane is 0.1wt%; basalt fiber cloth (plain weave, diameter 13μm, areal density 300g / m²) 2 The basalt fiber cloth (0.15 mm thick) was impregnated in the epoxy coupling agent solution. The mass ratio of the basalt fiber cloth to the epoxy coupling agent solution was 1:30. After ultrasonic treatment at 50°C (300 W power) for 2 hours, the basalt fiber cloth was taken out and vacuum dried to obtain the surface modified basalt fiber cloth.

[0037] (2) 2-(4-aminophenyl)-5-aminobenzimidazole was dissolved completely in N-methylpyrrolidone. Under nitrogen protection, an equimolar amount of 1,2,4,5-cyclohexanetetracarboxylic dianhydride was added. After stirring at room temperature for 3 hours, a large amount of methanol was added to precipitate the mixture, resulting in imidazole-containing polyamic acid. Bisphenol A type epoxy resin (E-51), imidazole-containing polyamic acid, and 4,4'-diaminophenyl sulfone were stirred and mixed at 40°C. The mass ratio of bisphenol A type epoxy resin (E-51), imidazole-containing polyamic acid, and 4,4'-diaminodiphenylmethane was 100:20:25 to obtain an epoxy resin solution. The epoxy resin solution was coated on both sides of the surface-modified basalt fiber cloth and cured at a heating rate of 10°C / min to 130°C to obtain a basalt fiber cloth prepreg. The content of the resin solution was 30 wt%.

[0038] (3) The three layers of basalt fiber cloth prepreg are stacked and hot-pressed. The hot-pressing temperature is 150℃ and the pressure is 15MPa. After cutting and shaping, the basalt fiber composite material for mobile phone casing is obtained.

[0039] Example 3

[0040] A basalt fiber composite material for mobile phone casings, the preparation method of which includes the following steps:

[0041] (1) Add γ-glycidoxypropyltrimethoxysilane to an acetic acid solution (concentration 1wt%) and stir to dissolve to obtain an epoxy coupling agent solution, wherein the content of γ-glycidoxypropyltrimethoxysilane is 1wt%; basalt fiber cloth (plain weave, diameter 13μm, areal density 300g / m²) 2 The basalt fiber cloth (0.15 mm thick) was impregnated in the epoxy coupling agent solution. The mass ratio of the basalt fiber cloth to the epoxy coupling agent solution was 1:15. After ultrasonic treatment (300 W power) at 50°C for 2 hours, the basalt fiber cloth was taken out and vacuum dried to obtain the surface modified basalt fiber cloth.

[0042] (2) 2-(3-aminophenyl)-5-aminobenzimidazole was dissolved completely in N-methylpyrrolidone. Under nitrogen protection, an equimolar amount of pyromellitic anhydride was added. After stirring at room temperature for 3 hours, a large amount of methanol was added to precipitate the mixture, resulting in imidazole-containing polyamic acid. Bisphenol A type epoxy resin (E-51), imidazole-containing polyamic acid, and 4,4'-diaminodiphenylmethane were stirred and mixed at 60°C. The mass ratio of bisphenol A type epoxy resin (E-51), imidazole-containing polyamic acid, and 4,4'-diaminodiphenylmethane was 100:40:10 to obtain an epoxy resin solution. The epoxy resin solution was coated on both sides of the surface-modified basalt fiber cloth and cured at a heating rate of 5°C / min to 90°C to obtain a basalt fiber cloth prepreg. The content of the resin solution was 50 wt%.

[0043] (3) The three layers of basalt fiber cloth prepreg are stacked and hot-pressed. The hot-pressing temperature is 200℃ and the pressure is 5MPa. After cutting and shaping, the basalt fiber composite material for mobile phone casing is obtained.

[0044] Comparative Example 1

[0045] A basalt fiber composite material for mobile phone casings, the preparation method of which includes the following steps:

[0046] (1) γ-glycidoxypropyltrimethoxysilane was added to an acetic acid solution (concentration 1 wt%) and stirred to dissolve, yielding an epoxy coupling agent solution, wherein the content of γ-glycidoxypropyltrimethoxysilane was 0.5 wt%; basalt fiber cloth (plain weave, diameter 13 μm, areal density 300 g / m²) was used. 2 The basalt fiber cloth (0.15 mm thick) was impregnated in the epoxy coupling agent solution. The mass ratio of the basalt fiber cloth to the epoxy coupling agent solution was 1:20. After ultrasonic treatment at 50°C (300 W power) for 2 hours, the basalt fiber cloth was taken out and vacuum dried to obtain the surface modified basalt fiber cloth.

[0047] (2) 4,4'-diaminobiphenyl was dissolved completely in N-methylpyrrolidone. Under nitrogen protection, an equimolar amount of 4,4'-(hexafluoroisopropene)phthalic anhydride was added. After stirring at room temperature for 3 hours, a large amount of methanol was added to precipitate polyamic acid. Bisphenol A type epoxy resin (E-51), polyamic acid and 4,4'-diaminodiphenylmethane were stirred and mixed at 50°C. The mass ratio of bisphenol A type epoxy resin (E-51), polyamic acid and 4,4'-diaminodiphenylmethane was 100:30:15 to obtain epoxy resin solution. The epoxy resin solution was coated on both sides of the surface-modified basalt fiber cloth and cured at a heating rate of 5°C / min to 110°C to obtain basalt fiber cloth prepreg. The content of the resin solution was 40wt%.

[0048] (3) The three layers of basalt fiber cloth prepreg are stacked and hot-pressed. The hot-pressing temperature is 170°C and the pressure is 10MPa. After cutting and shaping, the basalt fiber composite material for mobile phone casing is obtained.

[0049] Comparative Example 2

[0050] A basalt fiber composite material for mobile phone casings, the preparation method of which includes the following steps:

[0051] (1) 2-(3-aminophenyl)-5-aminobenzimidazole was completely dissolved in N-methylpyrrolidone. Under nitrogen protection, an equimolar amount of 4,4′-(hexafluoroisopropene)phthalic anhydride was added. After stirring at room temperature for 3 hours, a large amount of methanol was added to precipitate the mixture, yielding imidazole-containing polyamic acid. Bisphenol A type epoxy resin (E-51), imidazole-containing polyamic acid, and 4,4′-diaminodiphenylmethane were stirred and mixed at 50°C. The mass ratio of bisphenol A type epoxy resin (E-51), imidazole-containing polyamic acid, and 4,4′-diaminodiphenylmethane was 100:30:15 to obtain an epoxy resin solution. The epoxy resin solution was coated onto basalt fiber cloth (plain weave, diameter 13 μm, surface density 300 g / m³). 2 The basalt fiber cloth prepreg (with a thickness of 0.15 mm) was heated to 110 °C at a heating rate of 5 °C / min and then cured to obtain the resin liquid content of 40 wt%.

[0052] (2) The three layers of basalt fiber cloth prepreg are stacked and hot-pressed. The hot-pressing temperature is 170°C and the pressure is 10MPa. After cutting and shaping, the basalt fiber composite material for mobile phone casing is obtained.

[0053] According to the GB / T1447-2005 standard and the three-point bending method, the mechanical properties of the composite materials prepared in the examples and comparative examples were tested, and the results are shown in Table 1 below.

[0054] Table 1. Performance test results of the composite materials described in the examples and comparative examples.

[0055] Tensile strength / MPa Bending strength / MPa <![CDATA[Notched impact strength / kJ / m 2 > Example 1 596 545 421 Example 2 565 519 379 Example 3 584 551 417 Comparative Example 1 457 413 234 Comparative Example 2 403 377 183

[0056] As can be seen from the table above, the composite material described in this invention has excellent strength and toughness, making it particularly suitable for use in mobile phone casings.

[0057] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A basalt fiber composite material for mobile phone casings, characterized in that, It is made by hot pressing of multi-layer basalt fiber fabric prepreg; The basalt fiber fabric prepreg is prepared by coating both sides of the basalt fiber fabric with epoxy resin and then baking it into a film. The epoxy resin adhesive comprises, by weight, 100 parts epoxy resin, 20-40 parts imidazole polyamic acid, and 10-25 parts curing agent.

2. The basalt fiber composite material for mobile phone casing according to claim 1, characterized in that, The epoxy resin content in the basalt fiber fabric prepreg is 30-50 wt%.

3. The basalt fiber composite material for mobile phone casings according to claim 1 or 2, characterized in that, The epoxy resin is at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, or bisphenol S type epoxy resin.

4. The basalt fiber composite material for mobile phone casing according to claim 3, characterized in that, The epoxy value of the epoxy resin is 0.3-0.

7.

5. The basalt fiber composite material for mobile phone casings according to claim 1 or 2, characterized in that, The imidazole-containing polyamic acid is prepared by polycondensation of imidazole diamine monomer and dianhydride monomer.

6. The basalt fiber composite material for mobile phone casing according to claim 5, characterized in that, The molar ratio of the imidazole diamine monomer to the dianhydride monomer is 1:0.9-1.

1.

7. The basalt fiber composite material for mobile phone casing according to claim 5, characterized in that, The imidazole diamine monomer is at least one of 2-(3-aminophenyl)-5-aminobenzimidazole or 2-(4-aminophenyl)-5-aminobenzimidazole; the dianhydride monomer is at least one of 4,4′-(hexafluoroisopropene) phthalic anhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, dicyclohexyl-3,4,3',4'-tetracarboxylic dianhydride or pyromellitic dianhydride.

8. The basalt fiber composite material for mobile phone casings according to claim 1 or 2, characterized in that, The curing agent is at least one of 4,4'-diaminodiphenylmethane, 4,4'-diaminophenyl sulfone, dicyandiamide, phthalic anhydride, ethylenediamine, or dimethylaminophenol.

9. The basalt fiber composite material for mobile phone casings according to claim 1 or 2, characterized in that, The basalt fiber fabric is a surface-modified basalt fiber fabric.

10. The basalt fiber composite material for mobile phone casing according to claim 9, characterized in that, The surface-modified basalt fiber fabric is obtained by impregnating basalt fiber fabric with an epoxy coupling agent solution.

11. The basalt fiber composite material for mobile phone casing according to claim 10, characterized in that, The epoxy coupling agent solution is obtained by adding an epoxy coupling agent to an aqueous acetic acid solution, and the content of the epoxy coupling agent is 0.1-1 wt%.

12. The basalt fiber composite material for mobile phone casing according to claim 11, characterized in that, The basalt fiber fabric is at least one of basalt fiber cloth or basalt fiber felt.

13. A method for preparing a basalt fiber composite material for a mobile phone casing according to any one of claims 1-12, characterized in that, Includes the following steps: S1. Mix 100 parts of epoxy resin, 20-40 parts of imidazole polyamic acid and 10-25 parts of curing agent by weight to obtain epoxy resin solution. S2. The epoxy resin solution is coated on both sides of the basalt fiber fabric, and after baking, a basalt fiber fabric prepreg is obtained. S3. After stacking multiple layers of the basalt fiber fabric prepreg and hot-pressing them, the basalt fiber composite material for the mobile phone casing is obtained.

14. The method for preparing basalt fiber composite material for mobile phone casings according to claim 13, characterized in that, In step S1, the mixing temperature is 40-60℃; in step S2, the baking temperature is 90-130℃ and the time is 1-10min; in step S3, the hot pressing temperature is 150-200℃ and the pressure is 5-15MPa.