Bamboo fiber composite material and preparation method thereof

Abstract

The application provides a bamboo fiber composite material and a preparation method thereof. The method comprises the following steps: S1, material preparation and drying: drying bamboo fibers, an epoxy adhesive and glass beads; the epoxy adhesive comprises E51 epoxy resin, glycidyl ether 501, CMP-410, methyl hexahydrophthalic anhydride, tung oil anhydride and DMP-30 toughening agent; S2, glue preparation: brushing a release agent on a mold; preparing glue and stirring uniformly; pre-curing at 60 DEG C for 30 minutes; uniformly mixing the glass beads and the epoxy; paving; laminating; curing; and demolding. The bamboo fiber composite material prepared by the method has low density and high mechanical properties; a hydrophobic layer structure is formed on the surface of the bamboo fiber composite material, and the long-term stability of the composite material is not affected.

Description

Technical Field

[0001] This invention relates to the field of bamboo fiber technology, specifically to a bamboo fiber composite material and a method for preparing the bamboo fiber composite material. Background Technology

[0002] Bamboo fiber composites have become a research hotspot in the field of lightweight materials due to their excellent mechanical properties, environmental friendliness, and renewability. Especially in industries such as automotive, aerospace, and construction, the lightweight characteristics of bamboo fiber composites are of great significance for improving energy efficiency and reducing carbon emissions.

[0003] However, several technical challenges and problems remain when applying bamboo fiber composites to lightweight applications. The following are the main issues related to the lightweighting of bamboo fiber composites:

[0004] The balance between density and mechanical properties of bamboo fiber composites; the lightweighting of bamboo fiber composites mainly relies on reducing the material's density. However, bamboo fiber itself has a relatively high density, approximately 1.4 g / cm³. 3 This means that if left unchecked, the overall density of the composite material may be too high. To achieve lightweighting, it is usually necessary to reduce the bamboo fiber content or introduce other low-density fillers, but this process leads to a decrease in mechanical properties, especially compressive strength, tensile strength, and impact toughness.

[0005] The problem of hygroscopicity of bamboo fiber: Bamboo fiber has strong hygroscopicity. When the humidity is high, the mechanical properties of bamboo fiber composites will decrease significantly. Hygroscopicity not only affects the long-term stability of the material, but may also lead to performance fluctuations of composites in practical applications. Especially in humid and hot environments, problems such as expansion, deformation and corrosion of bamboo fiber composites are more significant.

[0006] Processing issues of bamboo fiber composites: The natural nature of bamboo fiber determines the heterogeneity of its fiber structure, which may lead to problems such as poor fiber dispersion and poor resin permeability during processing, thus affecting the uniformity and mechanical properties of the composite material; In addition, the interfacial bonding force between bamboo fiber and conventional resin is weak, which can easily cause interlayer delamination, increased brittleness and other phenomena. Summary of the Invention

[0007] Therefore, the purpose of this invention is to provide a bamboo fiber composite material, a method for preparing the bamboo fiber composite material, and applications of the bamboo fiber composite material.

[0008] A first aspect of the present invention relates to an epoxy adhesive comprising E51 epoxy resin, glycidyl ether 501, CMP-410, methylhexahydrophthalic anhydride, tung oil anhydride, and a toughening agent.

[0009] The epoxy adhesive, preferably, comprises 70-85 parts of E51 epoxy resin, 5-15 parts of glycidyl ether 501, 3-7 parts of CMP-410, 40-50 parts of methylhexahydrophthalic anhydride, 5-12 parts of tung oil anhydride, and 0.5-2 parts of DMP-30 toughening agent.

[0010] A second aspect of this invention relates to a method for manufacturing bamboo fiber sheets, comprising the following steps:

[0011] S1 Raw Material Preparation: Ensure that the bamboo fiber is free of impurities and contaminants and is suitable for further processing;

[0012] S2 pretreatment: Removes excess moisture, increases fiber plasticity, makes bamboo fiber softer and easier for subsequent molding;

[0013] S3 Ingredient Preparation and Laying: Ensure that the bamboo fiber is laid evenly, resulting in uniform molding without defects such as filament separation or delamination;

[0014] S4 Hot Press Molding: Bamboo fiber sheets with a thickness of less than 10mm are produced by high temperature and high pressure, preferably bamboo fiber sheets with a thickness of about 1mm.

[0015] S5 Cooling: Gradually cools down the formed bamboo fiber sheets;

[0016] S6 Cutting: Cut bamboo fiber sheets to meet specifications according to the size of the forming mold.

[0017] A third aspect of the present invention relates to a bamboo fiber composite material comprising bamboo fiber sheets, an epoxy adhesive of the first aspect of the present invention, and glass microspheres.

[0018] Preferably, the bamboo fiber sheet is prepared using the bamboo fiber sheet manufacturing method described in the second aspect of this application;

[0019] As a preferred bamboo fiber composite material, the bamboo fiber sheet accounts for 10-40% by mass, the epoxy system accounts for 40%-70% by mass, and the glass microspheres account for 10%-40% by mass.

[0020] A fourth aspect of this invention relates to a method for preparing bamboo fiber composite materials, the method comprising the following steps:

[0021] S1 Material preparation and drying: Drying bamboo fiber, epoxy adhesive of the first aspect of the present invention, and glass microspheres;

[0022] S2 adhesive preparation: Apply release agent to the mold; prepare the adhesive and stir evenly; pre-cure at 60℃ for 30 minutes;

[0023] Mix glass microspheres and epoxy evenly; lay them up; laminate; cure; demold.

[0024] The method for preparing bamboo fiber composite materials provided by this invention produces bamboo fiber composite materials with low density and high mechanical properties; a hydrophobic layer structure is formed on the surface of the bamboo fiber composite material, which does not affect the long-term stability of the composite material; this invention uses high temperature and high pressure lamination of thin bamboo fiber sheets, which solves the problems of poor bamboo fiber dispersion and poor resin permeability. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 Figure 1 shows the bamboo fiber composite material prepared using the formulation of this application.

[0027] Figure 2 Image of the shaped bamboo fiber sheet obtained by the bamboo fiber sheet preparation method of this application;

[0028] Figure 3 Water contact angle diagram of bamboo fiber composite material; Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0030] An epoxy adhesive comprising 70-85 parts of E51 epoxy resin, 5-15 parts of glycidyl ether 501, 3-7 parts of CMP-410, 40-50 parts of methylhexahydrophthalic anhydride, 5-12 parts of tung oil anhydride, and 0.5-2 parts of DMP-30 toughening agent.

[0031] A bamboo fiber composite material comprising bamboo fiber, epoxy adhesive, and glass microspheres; the epoxy adhesive comprising 70-85 parts of E51 epoxy resin, 5-15 parts of glycidyl ether 501, 3-7 parts of CMP-410, 40-50 parts of methylhexahydrophthalic anhydride, 5-12 parts of tung oil anhydride, and 0.5-2 parts of DMP-30 toughening agent.

[0032] As one preferred embodiment, the bamboo fiber comprises 10-40% by weight, the epoxy adhesive comprises 40%-70% by weight, and the glass microspheres comprise 10%-40% by weight. (See attached drawings of this application.) Figure 1 The paper demonstrates a bamboo fiber composite material prepared using the formulation of this application.

[0033] As one preferred method, add 0.2-0.4 g / cm³. 3 Glass microspheres, with a controlled mass ratio of 10-30%, and a composite material density of 0.4-0.8 g / cm³. 3 .

[0034] A method for producing bamboo fiber sheets includes the following steps:

[0035] S1 Raw Material Preparation: Ensure that the bamboo fiber is free of impurities and contaminants and is suitable for further processing;

[0036] The bamboo fiber is selected with a fiber length of 8cm or more;

[0037] The initial moisture content of the preferred bamboo fiber should be controlled between 10-15%, and the bamboo fiber should be free of impurities and contaminants to ensure that it is suitable for further processing.

[0038] S2 pretreatment: Removes excess moisture, increases fiber plasticity, makes bamboo fiber softer and easier for subsequent molding;

[0039] The preferred preheating temperature is 70℃.

[0040] The preferred preheating time is 30 minutes.

[0041] Pressure conditions: No external pressure needs to be applied at this stage. The bamboo fiber only needs to be heated in a temperature-controlled environment. After the moisture evaporates, the bamboo fiber will become softer, making it easier to lay and shape later.

[0042] S3 Ingredient Preparation and Laying: Ensure that the bamboo fiber is laid evenly, resulting in uniform molding without defects such as bubbles or delamination.

[0043] The pre-treated bamboo fibers are evenly laid in the molding mold to ensure uniform fiber distribution and avoid uneven thickness or improper fiber interweaving.

[0044] According to design requirements, ensure the bamboo fiber cloth has a uniform thickness. During the laying process, ensure the density of each layer of bamboo fiber is reasonable, avoiding gaps and accumulation; in a loose state, the thickness should be controlled within 1 cm. S4 Hot pressing: Through high temperature and high pressure, the bamboo fiber is fully bonded to the epoxy adhesive or other matrix material of the first aspect of this invention.

[0045] The preferred hot-pressing temperature is 160-175℃;

[0046] The preferred hot-pressing pressure is 10-20 MPa;

[0047] The optimal hot-pressing time is 10-20 minutes;

[0048] Extend the heat preservation time to 25-30 minutes;

[0049] S5 Cooling: Gradually cools down the formed bamboo fiber cloth.

[0050] Natural cooling is employed, allowing the bamboo fiber cloth to gradually cool to room temperature in the air. Natural cooling effectively avoids stress concentration and material deformation caused by rapid cooling, ensuring the stability of the finished product.

[0051] S6 Cutting: Cut bamboo fiber cloth to meet specifications according to the size of the forming mold.

[0052] Cutting method: Use a special cutting tool to cut the required amount of bamboo fiber fabric according to the size of the molding die. Ensure neat edges and remove excess material during cutting to avoid waste.

[0053] The bamboo fiber sheets prepared using the above method are shown in the attached diagram of the instruction manual. Figure 2 .

[0054] A method for preparing bamboo fiber composite material, the method comprising the following steps:

[0055] S1 Material preparation and drying: Drying bamboo fiber, epoxy adhesive of the first aspect of the present invention, and glass microspheres;

[0056] S2 Glue Preparation: The glue preparation process includes S21 brushing release agent onto the mold; S22 preparing the glue and stirring it evenly; S23 pre-curing at 60℃ for 30 minutes; S24 mixing glass microspheres and epoxy evenly; S25 laying; S26 laminating; S27 curing; S28 demolding.

[0057] In step S1, the glass microspheres and bamboo fibers are preferably dried at 80°C for 24 hours.

[0058] The chemical substances such as epoxy E51, tung oil anhydride and hexamethyl anhydride are preferably placed at 60°C for 2 hours.

[0059] In step S21, the mold release agent is applied to the mold by brushing, ensuring that it is evenly covered on the mold surface.

[0060] In step S22, epoxy resin E51 is mixed with curing agents tung oil anhydride and hexamethyl anhydride in a certain proportion.

[0061] In step S23, the adhesive is pre-cured at 60°C for 30 minutes. This pre-curing step allows the adhesive to partially cure ahead of time, ensuring thorough curing of the epoxy system later. Curing at 60°C for 30 minutes creates the necessary conditions for subsequent material application and lamination of the composite material system.

[0062] In step S24, glass microspheres are mixed uniformly with epoxy resin E51. The glass microspheres and resin are fully bonded, thereby enhancing the composite material's wear resistance, sound insulation, and flame retardancy. As a filler, the glass microspheres effectively improve the material's mechanical properties and surface finish.

[0063] In step S25, the laying process involves layering glass microspheres and bamboo fibers in a mold to form different layers of the composite material. Each layer is bonded to epoxy resin, which improves the overall mechanical properties of the composite material and ensures uniform strength distribution. The thickness and laying method of each layer affect the final mechanical properties of the material.

[0064] In step S26, the lamination process involves pressing the composite material under a specified pressure to ensure a tight bond between different layers.

[0065] First, apply pressure of 2-4 MPa for 3-5 minutes to ensure initial bonding.

[0066] Then increase the pressure to 8-10 MPa and continue pressing for 3-5 minutes. This helps to further remove air bubbles from the material and ensure good interfacial bonding.

[0067] In step S27, the curing process is crucial for the molding of the composite material. Temperature-controlled curing ensures that the crosslinking reaction between the epoxy resin and the curing agent occurs completely. Curing at 60-80℃ for 4-24 hours initially completes the crosslinking of the resin.

[0068] The material is then cured at 120-160℃ for 2-6 hours to further enhance its strength and stability.

[0069] In step S28, after curing, the material can be removed from the mold through the pre-drilled release port. Special care must be taken in this step to ensure the finished product is undamaged.

[0070] The composite material prepared using the method described in this application has a density of 0.4-0.8 g / cm³. 3 Compared to pure epoxy resin (density approximately 1.2 g / cm³), 3 Compared to the previous decrease, it decreased by 200%;

[0071] The composite material prepared in this application has a static bending strength of 40-60 MPa, which is 50% higher than that of pure epoxy resin (tested static bending strength of 40 MPa).

[0072] The composite material prepared in this application has an elastic modulus of 5000-6000MPa; the material surface is a hydrophobic layer with a water contact angle greater than 90°, while the water contact angle of bamboo fiber is between 30° and 60°, thus solving the water absorption problem of bamboo fiber composite materials.

[0073] When using the following epoxy system: E51 epoxy resin: 85; glycidyl ether: 10; CMP-410: 5; hexacarboxylic anhydride: 50; tung oil anhydride: 10; DMP toughening agent: 1;

[0074] When the mass proportions of the components of the composite material are as follows: bamboo fiber 25%, glass microspheres 15%, and epoxy resin system (E51 epoxy resin: 85; glycidyl ether: 10; CMP-410: 5; hexaformic anhydride: 50; tung oil anhydride: 10; DMP-toughening agent: 1) 60%, the relevant properties of the composite material are measured as follows:

[0075] The composite material has a static bending strength of 52.440 MPa and an elastic modulus of 5479 MPa; under pure rubber performance testing, i.e. only epoxy resin, the static bending strength is 39.51 MPa.

[0076] The density of the composite material was tested as follows:

[0077]

[0078] The bamboo fiber composite material prepared in this application has a hydrophobic surface with a water contact angle greater than 90°. See details... Figure 3 .

[0079] It should be noted that although the technical solutions of the present invention have been described with reference to specific embodiments, those skilled in the art will understand that the present invention should not be limited thereto. The above descriptions of various embodiments of the present invention are exemplary and not exhaustive.

Claims

1. A method for producing bamboo fiber sheets, comprising the following steps: S1 Raw material preparation: ensuring that the bamboo fiber is free of impurities and contaminants; the initial moisture content of the bamboo fiber should be controlled between 10-15% and ensuring that the bamboo fiber is free of impurities and contaminants, suitable for further processing; S2 Pretreatment: removing excess moisture and increasing the plasticity of the fiber; S3 Laying: laying the bamboo fiber evenly, forming a uniform shape without bubbles or delamination; S4 Hot pressing: producing bamboo fiber sheets with a thickness of less than 10mm through high temperature and high pressure; the hot pressing temperature is 160-175°C; S5 Cooling and cooling; S6 Cutting the sheets.

2. A bamboo fiber composite material, comprising bamboo fiber sheets, epoxy adhesive, and glass microspheres; wherein, The bamboo fiber sheet comprises 10-40% by weight, the epoxy adhesive comprises 40%-70% by weight, and the glass microspheres comprise 10%-40% by weight. The epoxy adhesive includes 70-85 parts E51 epoxy resin, 5-15 parts glycidyl ether 501, 3-7 parts CMP-410, 40-50 parts methylhexahydrophthalic anhydride, 5-12 parts tung oil anhydride, and 0.5-2 parts DMP-30 toughening agent. The bamboo fiber sheet is prepared by the following methods: Raw material preparation: Ensure the bamboo fiber is free of impurities and contaminants; the initial moisture content of the bamboo fiber should be controlled between 10-15%, ensuring it is free of impurities and contaminants and suitable for further processing; Pretreatment: Remove excess moisture to increase fiber plasticity; Laying: Evenly lay the bamboo fiber, ensuring uniform molding without bubbles or delamination; Hot pressing: Produce bamboo fiber sheets less than 10mm thick using high temperature and high pressure; the hot pressing temperature is 160-175℃; Cooling; Cutting the sheet.

3. A method for preparing a bamboo fiber composite material, comprising the following steps: S1 Preparing an epoxy adhesive system; the epoxy adhesive system comprising 70-85 parts E51 epoxy resin, 5-15 parts glycidyl ether 501, 3-7 parts CMP-410, 40-50 parts methylhexahydrophthalic anhydride, 5-12 parts tung oil anhydride, and 0.5-2 parts DMP-30 toughening agent; S2 Mixing the prepared epoxy adhesive system with glass microspheres; S3 Laminating and bonding the glass microspheres mixed with the epoxy system with bamboo fiber sheets; S4 Curing and demolding; wherein, The bamboo fiber sheet in S3 is prepared by the following steps: S31 Raw material preparation: Ensure that the bamboo fiber is free of impurities and contaminants; the initial moisture content of the bamboo fiber should be controlled between 10-15% and ensure that the bamboo fiber is free of impurities and contaminants, suitable for further processing; S32 Pretreatment: Remove excess moisture and increase the plasticity of the fiber; S33 Laying: Lay the bamboo fiber evenly, forming a uniform shape without bubbles or delamination; S34 Hot pressing: Produce bamboo fiber sheets with a thickness of less than 10mm through high temperature and high pressure; the hot pressing temperature is 160-175°C; S35 Cooling; S36 Cutting the sheet.

4. In the method for preparing bamboo fiber composite material according to claim 3, when preparing the epoxy bonding system, epoxy resin E51, tung oil anhydride, and methyl hexacyanate anhydride need to be dried at 60°C for 2 hours.

5. In the method for preparing bamboo fiber composite material according to claim 3, the glass microspheres or bamboo fibers are dried at 60°C for 24 hours.

6. The method for preparing bamboo fiber composite material according to claim 3, first pressing with a pressure of 2-4 MPa, then increasing the pressure to 8-10 MPa, and continuing pressing.

7. The application of the bamboo fiber composite material according to claim 2 in the preparation of automotive interior parts.

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