Bamboo fiber composite material and preparation method thereof

Abstract

The invention provides a bamboo fiber composite material and a preparation method thereof. The method comprises the following steps: S1, preparing and drying materials: drying bamboo fibers, an epoxy adhesive and glass beads; the epoxy adhesive is prepared from E51 epoxy resin, glycidyl ether 501, CMP-410, methylhexahydrophthalic anhydride, tung oil anhydride and a DMP-30 toughening agent; s2, glue preparation, wherein a mold is brushed with a release agent; preparing glue, and uniformly stirring; pre-curing for 30 minutes under the condition of 60 DEG C; uniformly mixing the glass beads with epoxy; paving is conducted; performing lamination; performing curing; and demolding. The bamboo fiber composite material prepared by the method is low in density and high in mechanical property; a hydrophobic layer structure is formed on the surface of the bamboo fiber composite material, and long-term stability of the composite material is not affected.

Description

Technical Field

[0001] The invention relates to the technical field of bamboo fibers, in particular to a bamboo fiber composite material and a preparation method of the bamboo fiber composite material. Background Art

[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 the automotive, aerospace, construction and other industries, the lightweight characteristics of bamboo fiber composites are of great significance for improving energy efficiency and reducing carbon emissions.

[0003] However, there are still many technical challenges and problems in applying bamboo fiber composites to lightweighting. The following are the main problems in lightweighting bamboo fiber composites:

[0004] The balance between density and mechanical properties of bamboo fiber composites; the lightweight of bamboo fiber composites mainly depends on reducing the density of the material. However, the density of bamboo fiber itself is relatively high, about 1.4g / cm 3 , which means that if not controlled, the overall density of the composite material may be too high. In order to achieve lightweighting, it is usually necessary to reduce the content of bamboo fiber or introduce other low-density fillers, but this process will lead to a decrease in mechanical properties, especially compressive strength, tensile strength and impact toughness.

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

[0006] Processing technology issues of bamboo fiber composites; The natural nature of bamboo fiber determines the heterogeneity of its fiber structure, which may cause problems such as poor fiber dispersion and poor resin permeability during processing, thereby 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] In view of this, the purpose of the present invention is to provide a bamboo fiber composite material, a preparation method of the bamboo fiber composite material, and an application of the bamboo fiber composite material.

[0008] The first aspect of the present invention relates to an epoxy adhesive, which includes E51 epoxy resin, glycidyl ether 501, CMP-410, methyl hexahydrophthalic 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 methyl hexahydrophthalic anhydride, 5-12 parts of tung oil anhydride, and 0.5-2 parts of DMP-30 toughening agent.

[0010] The second aspect of the present invention relates to a method for making a bamboo fiber sheet, 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: remove excess water, increase the plasticity of the fiber, make the bamboo fiber softer and facilitate subsequent molding;

[0013] S3 Batching and laying: Ensure that the bamboo fiber is laid evenly and formed evenly without defects such as splitting and delamination;

[0014] S4 hot pressing molding: through high temperature and high pressure, a bamboo fiber sheet with a thickness of less than 10 mm is produced, preferably a bamboo fiber sheet of about 1 mm.

[0015] S5 cooling: gradually cooling the formed bamboo fiber sheet;

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

[0017] The third aspect of the present invention relates to a bamboo fiber composite material, which includes a bamboo fiber sheet, the epoxy adhesive of the first aspect of the present invention, and glass microspheres.

[0018] Preferably, the bamboo fiber sheet is prepared by the bamboo fiber sheet manufacturing method involved in the second aspect of the present application;

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

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

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

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

[0023] Mix glass beads and epoxy evenly; lay; laminate; cure; demould.

[0024] The invention provides a method for preparing a bamboo fiber composite material. 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, which will not affect the long-term stability of the composite material. The invention adopts high temperature and high pressure to laminate thin bamboo fiber sheets, which solves the problems of poor dispersibility of bamboo fibers and poor resin permeability. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 Figure 1 shows the bamboo fiber composite material prepared by using the formula of the present application;

[0027] Figure 2 Figure 1 shows a shaped bamboo fiber sheet obtained by the bamboo fiber sheet preparation method of the present application;

[0028] Figure 3 Water contact angle diagram of bamboo fiber composites; DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0030] An epoxy adhesive 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 methyl hexahydrophthalic anhydride, 5-12 parts of tung oil anhydride and 0.5-2 parts of DMP-30 toughening agent.

[0031] A bamboo fiber composite material comprises bamboo fiber, epoxy adhesive and glass microbeads; the epoxy adhesive 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 methyl hexahydrophthalic anhydride, 5-12 parts of tung oil anhydride and 0.5-2 parts of DMP-30 toughening agent.

[0032] As one preferred method, the bamboo fiber accounts for 10-40% by weight, the epoxy adhesive accounts for 40%-70% by weight, and the glass beads account for 10%-40% by weight. Figure 1 , showing the bamboo fiber composite material prepared using the formula of the present application.

[0033] As one of the preferred methods, add 0.2-0.4g / cm 3 The glass microspheres have a controlled mass ratio of 10-30% and a composite material density of 0.4-0.8 g / cm 3 .

[0034] A method for making a bamboo fiber sheet comprises 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] Bamboo fiber is preferred and the fiber length is controlled to be above 8cm;

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

[0038] S2 pretreatment: remove excess water, increase the plasticity of the fiber, make the bamboo fiber softer and facilitate subsequent molding;

[0039] The preheating temperature is preferably 70°C.

[0040] The preheating time is preferably 30 minutes.

[0041] Pressure conditions: No external pressure is required at this stage. The bamboo fiber only needs to be heated in a temperature-controlled environment. After the water evaporates, the bamboo fiber will become softer, which is convenient for subsequent laying and shaping.

[0042] S3 Batching and laying: Ensure that the bamboo fiber is laid evenly, formed evenly and without defects such as bubbles and delamination.

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

[0044] According to the design requirements, ensure that the thickness of the bamboo fiber cloth is uniform. During the laying process, ensure that the laying density of each layer of bamboo fiber is reasonable, avoid gaps and accumulation, and control the thickness within 1 cm in a loose state. S4 Hot pressing molding: through high temperature and high pressure, the bamboo fiber is fully combined with the epoxy adhesive or other matrix material of the first aspect of the present invention.

[0045] The hot pressing temperature is preferably 160-175°C;

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

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

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

[0049] S5 cooling: gradually cool down the formed bamboo fiber cloth.

[0050] The bamboo fiber cloth is cooled to room temperature in the air by natural cooling. Natural cooling can effectively avoid internal stress concentration and material deformation caused by rapid cooling, and ensure the stability of the finished product.

[0051] S6 Cutting: Cut the bamboo fiber cloth that meets the specifications according to the size of the molding mold.

[0052] Cutting method: Use special cutting tools to cut the required bamboo fiber cloth according to the size of the molding mold. When cutting, make sure the edges are neat and remove the excess parts to avoid waste.

[0053] The bamboo fiber sheet obtained by the above-mentioned bamboo fiber sheet preparation method is shown in the attached figure of the specification. Figure 2 .

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

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

[0056] S2 glue preparation: The glue preparation process includes S21 brushing a mold release agent on the mold; S22 preparing the glue and stirring it evenly; S23 pre-curing at 60°C for 30 minutes; S24 mixing the glass beads and the epoxy evenly; S25 laying; 26 laminating; S27 curing; S28 demoulding.

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

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

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

[0060] In step S22, epoxy resin epoxy E51 and curing agent tung oil anhydride and methyl hexachloride are mixed in proportion.

[0061] In step S23, pre-curing is performed at 60°C for 30 minutes. The pre-curing step is to allow the glue to partially cure in advance so that the epoxy system can be cured thoroughly afterwards. Curing at 60°C for 30 minutes can create conditions for subsequent material laying and laminating of the composite material system.

[0062] In step S24, glass beads are mixed evenly with epoxy resin E51. The glass beads are fully combined with the resin, thereby enhancing the wear resistance, sound insulation and flame retardancy of the composite material. As fillers, glass beads can effectively improve the mechanical properties and surface finish of the material.

[0063] In step S25, the paving process involves stacking glass beads and bamboo fibers in layers in a mold to form different layers of the composite material. There is a combination of glass beads and epoxy resin between each layer, which can improve the overall mechanical properties of the composite material and ensure uniform strength distribution. The thickness and laying method of each layer will affect the mechanical properties of the final material.

[0064] In step S26, the lamination process is to press the composite material under a specified pressure to ensure that the different layers are tightly bonded.

[0065] First press with 2-4MPa pressure for 3-5 minutes to ensure initial bonding.

[0066] The pressure is then increased to 8-10 MPa and the pressing is continued for 3-5 minutes, which helps to further remove bubbles in the material and ensure good interface bonding.

[0067] In step S27, the curing process is the key to composite material molding. Temperature-controlled curing can ensure that the cross-linking reaction between the epoxy resin and the curing agent occurs completely. Curing at 60-80°C for 4-24 hours preliminarily completes the cross-linking of the resin.

[0068] This is followed by curing at 120-160°C for 2-6 hours to further enhance the strength and stability of the material.

[0069] In step S28, after curing is completed, the material can be taken out of the mold through the reserved demoulding port. This step requires special attention to ensure that the finished product has no damage.

[0070] The composite material obtained by the preparation method of the bamboo fiber composite material of the present application has a density of 0.4-0.8 g / cm 3 , compared with pure epoxy resin (density about 1.2g / cm 3 ) compared to 200%;

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

[0072] The elastic modulus of the composite material prepared in the present application is 5000-6000 MPa; the surface of the material is a hydrophobic layer, the water contact angle is greater than 90°, and the water contact angle of the bamboo fiber is between 30°-60°, which solves the water absorption problem of the bamboo fiber composite material.

[0073] When the following epoxy system is used: E51 epoxy resin: 85; glycidyl ether: 10; CMP-410, 5; hexacarboxylic anhydride: 50; tung oil anhydride: 10; DMP-toughener: 1;

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

[0075] The static bending strength of the composite material is 52.440MPa and the elastic modulus is 5479MPa; under the pure glue performance test, that is, when there is only epoxy resin, the static bending strength is 39.51MPa.

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

[0077]

[0078] The surface of the bamboo fiber composite material prepared in this application is a hydrophobic layer, and the water contact angle is greater than 90. Figure 3 .

[0079] It should be noted that, although the technical solution of the present invention is described with specific embodiments, those skilled in the art will appreciate that the present invention should not be limited thereto. The above describes various embodiments of the present invention, and the above description is exemplary and not exhaustive.

Claims

1. An epoxy adhesive, comprising E51 epoxy resin, glycidyl ether 501, CMP-410, methyl hexahydrophthalic anhydride, tung oil anhydride, and DMP-30 toughening agent.

2. The epoxy adhesive as claimed in claim 1, 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 methyl hexahydrophthalic anhydride, 5-12 parts of tung oil anhydride, and 0.5-2 parts of DMP-30 toughening agent.

3. A method for producing a bamboo fiber sheet, comprising the following steps: S1 Raw material preparation: Ensure that bamboo fiber is free of impurities and pollutants; S2 pretreatment: remove excess water and increase fiber plasticity; S3 Laying: Evenly lay bamboo fiber, forming it evenly without bubbles or delamination; S4 hot pressing: through high temperature and high pressure, bamboo fiber sheets with a thickness of less than 10mm are produced; S5 cooling down. S6 cropped film.

4. A bamboo fiber composite material, comprising a bamboo fiber sheet, the epoxy adhesive according to claim 1, and glass microspheres.

5. The bamboo fiber composite material as claimed in claim 4, wherein the weight of the bamboo fiber sheet accounts for 10-40%, the weight of the epoxy adhesive accounts for 40%-70%, and the weight of the glass microspheres accounts for 10%-40%.

6. A method for preparing a bamboo fiber composite material, comprising the following steps: S1 prepares the epoxy bonding system; The epoxy adhesive system prepared in S2 is mixed with glass microspheres; The glass microbeads mixed with S3 and epoxy system are laid and laminated with the prepared bamboo fiber sheets; S4 is used for curing and demoulding.

7. The method for preparing a bamboo fiber composite material according to claim 6, when preparing the epoxy adhesive system, the epoxy resin E51, tung oil anhydride and methyl hexacarboxylic anhydride need to be dried at 60°C for 2 hours.

8. The method for preparing a bamboo fiber composite material according to claim 6, wherein the glass beads or bamboo fibers are dried at 60°C for 24 hours.

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

10. Use of the bamboo fiber composite material according to claim 4 or 5 in preparing automobile interior decoration parts.

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