A high impact-resistant, lightweight and high-strength composite board and its preparation method

Abstract

The present invention relates to a kind of high-impact lightweight high-strength composite board and preparation method thereof, comprise the following steps:S1, the first glass fiber is arranged between two thermoplastic polyurethane films, hot pressing, obtains glass fiber cloth reinforced polyurethane film;Polyamide-polyether block copolymer film is placed between adjacent two layers of glass fiber cloth reinforced polyurethane film, hot pressing, obtains high toughness surface layer;S2, modified hollow glass microsphere, bisphenol A epoxy resin, polyurethane modified epoxy resin, dicyandiamide, accelerator are added in solvent, obtain resin glue;The second glass fiber cloth is immersed in resin glue, taken out after being completely soaked and baked, obtain epoxy glass fiber prepreg;S3, multiple epoxy glass fiber prepregs are stacked, obtain low-density core layer;S4, low-density core layer is stacked between adjacent two layers of high toughness surface layer, hot pressing, obtains target product.The present invention has the advantages of light weight, high strength and high impact resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, and more particularly to a high-impact, lightweight, high-strength composite board and a preparation method thereof. Background Art

[0002] As a synthetic foam reinforced with glass fiber cloth, the epoxy glass fiber composite material filled with hollow glass microspheres has a lower density and better static mechanical strength. For example, the ultra-low density epoxy glass fiber composite material prepared in patent CN201410127336 has a density as low as 0.7g / cm 3 , with a bending strength of about 254MPa. Therefore, as a lightweight and high-strength composite material, it is widely used in fields that require both weight reduction and structural strength.

[0003] However, since thermosetting epoxy resins and hollow glass microspheres are both relatively brittle, the toughness and impact resistance of epoxy-glass fiber composites filled with a large number of hollow glass microspheres are poor, which limits their application in fields with high requirements for impact resistance, such as automobiles, home appliances, and 3C electronic products. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the object of the present invention is to provide a high-impact lightweight high-strength composite board and a preparation method thereof, which has the advantages of light weight, high strength and high impact resistance.

[0005] The above technical objectives of the present invention are achieved through the following technical solutions: A method for preparing a high-impact, lightweight, high-strength composite board comprises the following steps:

[0006] S1. Arranging a first glass fiber between two thermoplastic polyurethane films and hot pressing to obtain a glass fiber cloth reinforced polyurethane film;

[0007] Placing a polyamide-polyether block copolymer film between two adjacent layers of the glass fiber cloth reinforced polyurethane film, and hot pressing to obtain a high-toughness surface layer;

[0008] S2, adding modified hollow glass microspheres, bisphenol A epoxy resin, polyurethane modified epoxy resin, dicyandiamide, and accelerator to the solvent, mixing well, and obtaining a resin glue;

[0009] Dipping the second glass fiber cloth into the resin glue solution, taking it out after it is completely soaked, and baking it to obtain an epoxy glass fiber prepreg;

[0010] S3, stacking a plurality of the epoxy glass fiber prepregs to obtain a low-density core layer;

[0011] S4. Stacking the low-density core layer between two adjacent high-toughness surface layers, hot pressing, and obtaining the target product.

[0012] In one embodiment, the step S2 specifically includes the following steps:

[0013] S21, dissolving the modified nitrile rubber using butanone to obtain a modified nitrile rubber solution;

[0014] S22, adding hollow glass microspheres to the modified nitrile rubber solution, soaking, mixing, and filtering out the modified nitrile rubber solution to obtain the modified hollow glass microspheres;

[0015] S23, adding the bisphenol A epoxy resin, the polyurethane-modified epoxy resin, the dicyandiamide, and the accelerator to the solvent, mixing them uniformly, to obtain a mixture solution;

[0016] S24, adding the modified hollow glass microspheres to the mixture solution, mixing evenly, to obtain the resin glue solution.

[0017] In one embodiment, in S22, the specific steps of soaking are: first stirring at a medium speed to evenly disperse the hollow glass microspheres, and then continuing stirring at a low speed for 6-24 hours.

[0018] In one embodiment, the step S23 further includes: using the solvent to pre-dissolve a portion of the bisphenol A epoxy resin, and using ethylene glycol monomethyl ether to pre-dissolve the dicyandiamide and the accelerator.

[0019] In one embodiment, the step S3 further includes: performing hot pressing treatment on the low-density core layer.

[0020] In one embodiment, in S4, at least two low-density core layers are provided.

[0021] In one embodiment, the mass fractions of each component in the resin glue are:

[0022] 50-100 parts of bisphenol A epoxy resin;

[0023] 50-100 parts of polyurethane modified epoxy resin;

[0024] Accelerator 0.02-0.5 parts;

[0025] 5-50 parts of modified nitrile rubber;

[0026] 170-270 parts of hollow glass microspheres;

[0027] 2-15 parts of dicyandiamide.

[0028] In one embodiment, the solvent is at least one of butanone and acetone, and the accelerator is dimethylimidazole or 2-ethyl-4-methylimidazole.

[0029] A high-impact, lightweight, and high-strength composite board is prepared by the above-mentioned preparation method.

[0030] In one embodiment, the thickness of the high-toughness surface layer is 10%-50% of the thickness of the low-density core layer.

[0031] The above-mentioned high-impact, lightweight, high-strength composite board and its preparation method have the following beneficial effects:

[0032] First, a high-impact, lightweight, and high-strength composite panel is produced by combining a glass fiber cloth-reinforced polyurethane film with a polyamide-polyether block copolymer film to form a high-toughness surface layer. This layer is then combined with epoxy resin and modified hollow glass microspheres to create a low-density core layer. Finally, the high-toughness surface layer and the low-density core layer are combined through a hot-pressing process. This composite panel not only maintains its lightweight and high-strength properties, but also exhibits excellent impact resistance, capable of withstanding significant impact forces without breaking. It is ideal for applications requiring high impact resistance, such as automotive, home appliances, and consumer electronics.

[0033] Secondly, the design is highly flexible. By flexibly adjusting the number of high-toughness surface layers and low-density core layers, as well as the number of epoxy resin glass fiber semi-cured sheets in the low-density core layer, the specific requirements of material thickness and impact resistance in different application scenarios can be met, thereby optimizing the use efficiency and cost-effectiveness of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a flow chart of the steps of the present invention. DETAILED DESCRIPTION

[0035] The present invention is described in further detail below in conjunction with the embodiments. It should be noted that the embodiments described below are intended to facilitate understanding of the present invention and are not intended to limit the present invention in any way. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as those of ordinary skill in the art to which the present invention belongs. In the event of a conflict, the definitions in this specification shall prevail.

[0036] As used herein, the term "prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variations thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0037] The conjunction "consisting of" excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed, excluding materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim, rather than immediately following the subject matter, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0038] When amount, concentration or other value or parameter is represented with range, preferred range or the range that a series of upper preferred value and lower preferred value limit are expressed, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value and any range lower limit or preferred value, no matter whether this range is disclosed separately.For example, when disclosing scope "1 to 5", described scope should be interpreted as including scope "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5" etc.When numerical range is described in this article, unless otherwise stated, otherwise this scope is intended to include its end value and all integers and fractions within this range.

[0039] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0040] A method for preparing a high-impact, lightweight, high-strength composite board, such as Figure 1 As shown, the following steps are included:

[0041] S1. Arranging a first glass fiber between two thermoplastic polyurethane films and hot pressing to obtain a glass fiber cloth reinforced polyurethane film;

[0042] The polyamide-polyether block copolymer film is placed between two adjacent layers of glass fiber cloth reinforced polyurethane film, and hot pressed to obtain a high-toughness surface layer;

[0043] In this step, the first glass fiber cloth is a plain glass fiber cloth, and the weight of the plain glass fiber cloth is 48-165g / m 2, preferably a glass fiber cloth with a lower gram weight, so that the thermoplastic polyurethane can completely penetrate the glass fiber cloth under the action of high temperature and high pressure; the thermoplastic polyurethane film is preferably a polyether thermoplastic polyurethane film, which has a more similar chemical composition to the polyamide-polyether block copolymer film and contains a large number of reactive chemical groups, so that the high-toughness surface layer can be better combined together; polyamide-polyether block copolymer is a block copolymer composed of hard segments and soft segments, the hard segments of which are mainly composed of polyamide (PA) segments. These segments contain repeated amide groups (-CONH-), which can provide mechanical strength and heat resistance to the material, while the soft segments are composed of polyether segments. These segments contain repeated ether bonds (-O-), which give the material flexibility and elasticity. It is this unique molecular structure combination of hard and soft segments that makes amide-polyether block copolymers have high strength, heat resistance, excellent flexibility and elasticity.

[0044] In actual production, the plain glass fiber cloth and two thermoplastic polyurethane films are placed between them and hot pressed at a temperature of 170-210°C, preferably 180-200°C, and a pressure of 25-35kg / cm 2 The hot pressing time is 20-60 minutes, so that the thermoplastic polyurethane film melts and completely impregnates the plain glass fiber cloth, obtaining a glass fiber cloth reinforced polyurethane film with a thickness of 0.05-0.25mm. The layers are then stacked in a structure where the polyamide-polyether block copolymer film is placed between two adjacent layers of glass fiber cloth reinforced polyurethane film to obtain a high-toughness surface layer. Alternatively, the layers can be stacked in the same structure and then hot-pressed again at a temperature of 170-210°C, preferably 180-200°C, and a pressure of 5-10kg / cm 2 The hot pressing time is 60-600s, preferably 150-300s, to obtain a high-toughness surface layer.

[0045] S2, adding modified hollow glass microspheres, bisphenol A epoxy resin, polyurethane modified epoxy resin, dicyandiamide, and accelerator to the solvent, mixing well, and obtaining a resin glue;

[0046] Dipping the second glass fiber cloth into the resin glue, taking it out after it is completely soaked and baking it to obtain the epoxy glass fiber prepreg;

[0047] In this step, a mixture of bisphenol A epoxy resin and polyurethane-modified epoxy resin is used to improve the resin's adhesive strength and heat resistance while maintaining a certain degree of flexibility. A second glass fiber cloth is immersed in the resin and baked, evenly distributing the resin throughout the cloth and initially curing it, forming an epoxy glass fiber prepreg. This intermediate product provides the necessary structural strength and bonding properties for subsequent lamination.

[0048] Specifically, the second glass fiber cloth is an electronic grade alkali-free glass fiber cloth, and the gram weight of the electronic grade alkali-free glass fiber cloth is 16-105g / m 2 , preferably 48g / m 2 1080 glass fiber cloth. The lower weight of glass fiber cloth can increase the resin content in the prepreg, which helps to reduce the overall density. The hollow glass microspheres are borosilicate hollow glass microspheres with a density of 0.3-0.6g / cm 3 , particle size D50 is 30-75 μm, particle size D90 is 60-120 μm, and the preferred density is 0.38 g / cm 3 The hollow glass microspheres can effectively reduce the overall density of the material while ensuring sufficient compressive strength.

[0049] S3, stacking multiple epoxy glass fiber prepregs to obtain a low-density core layer;

[0050] In actual production, the stacking quantity and stacking specifications of the prepregs can be flexibly designed according to actual needs.

[0051] S4. Stack the low-density core layer between two adjacent high-toughness surface layers, and hot-press to obtain the target product.

[0052] Specifically, a low-density core layer is stacked between two adjacent high-toughness surface layers, which are then placed in a mold lined with a release film or coated with a release agent. Molding is performed according to set temperature and pressure parameters to ensure a tight bond between the materials. After molding, the fully cured composite panel is removed from the mold and placed in a shaping jig to cool to room temperature, resulting in a highly impact-resistant, lightweight, and high-strength composite panel. Both the top and bottom layers of the resulting composite panel are high-toughness surface layers, enhancing the panel's impact resistance.

[0053] In actual production, the hot pressing temperature of S4 is 70-170℃ and the maximum pressure does not exceed 15kg / m 2 , preferably 10kg / m 2 The hot pressing time is 0.5-3h, preferably 1.5-2.5h. By setting the range value in the vacuum press, the hot pressing temperature and hot pressing pressure are gradually increased to ensure that the epoxy glass fiber semi-cured sheet of the low-density core layer is completely cured.

[0054] The present invention combines a glass fiber reinforced polyurethane film with a polyamide-polyether block copolymer film to form a high-toughness surface layer, then combines epoxy resin with modified hollow glass microspheres to form a low-density core layer. Finally, the high-toughness surface layer and the low-density core layer are combined through a hot-pressing lamination process to produce a high-impact, lightweight, and high-strength composite panel. This composite panel not only maintains its lightweight and high-strength properties but also exhibits excellent impact resistance, capable of withstanding significant impact forces without cracking. It is well-suited for applications requiring high impact resistance, such as automotive, home appliances, and consumer electronics.

[0055] Furthermore, S2 specifically includes the following steps:

[0056] S21, dissolving the modified nitrile rubber using butanone to obtain a modified nitrile rubber solution;

[0057] S22, adding hollow glass microspheres to the modified nitrile rubber solution, soaking, mixing, and then filtering out the modified nitrile rubber solution to obtain modified hollow glass microspheres;

[0058] S23, adding bisphenol A epoxy resin, polyurethane modified epoxy resin, dicyandiamide, and accelerator to the solvent, mixing well, and obtaining a mixture solution;

[0059] S24. Add the modified hollow glass microspheres to the mixture solution, mix well, and obtain a resin glue solution.

[0060] Specifically, the modified nitrile rubber is preferably a carboxyl-terminated modified nitrile rubber. In actual production, the concentration of rubber in the modified nitrile rubber solution is between 5% and 20%, preferably 6% and 12%. If the concentration is too high, the viscosity is too high and it is not suitable for effectively dispersing the hollow glass microspheres. If the concentration is too low, the amount of modified nitrile rubber adsorbed and deposited on the surface of the hollow glass microspheres during the immersion treatment is too small.

[0061] Because the terminal carboxyl group of acrylonitrile-butadiene rubber can interact with the surface hydroxyl group of hollow glass microspheres by hydrogen bond, so the modified hollow glass microsphere surface obtained after the immersion treatment can adsorb a deck acrylonitrile-butadiene rubber, avoid collision between the rigid hollow glass microspheres and with the rigid thermosetting epoxy resin, thereby improve toughness and the impact resistance of composite material. Preferably, also can use acid or alkali to first activate the hollow glass microsphere surface to produce more surface silanols, wherein preferred acid, acid can also catalyze the reaction between the terminal carboxyl group of silanols and modified acrylonitrile-butadiene rubber except activating microsphere surface silanols, further increases the modified acrylonitrile-butadiene rubber quantity of hollow glass microsphere surface adsorption deposition. In order to realize the high concentration of hollow glass microspheres, add and ensure its good dispersibility simultaneously, the quality of modified acrylonitrile-butadiene rubber solution is 1-3.5 times of hollow glass microsphere quality, is preferably 1.5-2.5 times.

[0062] Furthermore, in S22, the specific steps of soaking are: first stirring at a medium speed to evenly disperse the hollow glass microspheres, and then continuing stirring at a low speed for 6-24 hours. In actual production, the speed of medium stirring is 200-800 rpm, and the speed of low stirring is 60-100 rpm.

[0063] Furthermore, S23 also includes: using a solvent to pre-dissolve a portion of the bisphenol A epoxy resin, and using ethylene glycol monomethyl ether to pre-dissolve dicyandiamide and an accelerator.

[0064] Specifically, pre-dissolving bisphenol A epoxy resin can improve its dissolution efficiency and the efficiency of subsequent reactions. Dicyandiamide is a commonly used latent curing agent, but due to its high polarity, its dispersibility and solubility in epoxy resin are poor. Therefore, ethylene glycol monomethyl ether is used to pre-dissolve dicyandiamide, ensuring a more uniform dispersion of the dicyandiamide in the resin glue. Ethylene glycol monomethyl ether also improves the solubility and dispersibility of the accelerator, thereby increasing the efficiency of the curing reaction.

[0065] Furthermore, S3 also includes: hot pressing the low-density core layer, that is, hot pressing the epoxy glass fiber semi-cured sheet constituting the low-density core layer, and then hot pressing and compounding it with the high-toughness surface layer obtained in S1.

[0066] Furthermore, in S4, at least two low-density core layers are provided to improve the overall impact resistance of the composite panel.

[0067] Specifically, since polyurethane-modified epoxy resin is used in the preparation of the low-density core layer, and thermoplastic polyurethane film is used in the preparation of the high-toughness surface layer, the chemical composition of these two materials is similar and there are a large number of reactive chemical groups, which makes the low-density core layer and the high-toughness surface layer have good bonding strength. Therefore, the number of high-toughness surface layers and low-density core layers can be set as needed, and stratification is not easy to occur.

[0068] The present invention has great design flexibility and can meet the specific requirements of material thickness and impact resistance in different application scenarios by flexibly adjusting the number of high-toughness surface layers and low-density core layers, as well as the number of epoxy resin glass fiber semi-cured sheets in the low-density core layer, thereby optimizing the use efficiency and cost-effectiveness of the material.

[0069] Furthermore, the mass fractions of the components in the resin glue are: 50-100 parts of bisphenol A epoxy resin; 50-100 parts of polyurethane modified epoxy resin; 0.02-0.5 parts of accelerator; 5-50 parts of modified nitrile rubber; 170-270 parts of hollow glass microspheres; and 2-15 parts of dicyandiamide.

[0070] In actual production, to improve the dissolution efficiency of the bisphenol A epoxy resin, a portion of the bisphenol A epoxy resin can be pre-dissolved in a solvent. All components of the resin adhesive (excluding the solvent) are calculated by weight based on the non-volatile content. By using the solvent, the solids content of the resin adhesive is controlled to 50-75%, preferably 65%. By precisely controlling the solids content of the resin adhesive, the viscosity and fluidity of the resin adhesive are balanced, ensuring that it can fully impregnate the glass fiber cloth without being too viscous to cause processing difficulties.

[0071] Furthermore, the solvent is at least one of butanone and acetone. In actual production, the viscosity and fluidity of the resin glue are increased by adding a solvent to facilitate the impregnation and curing process.

[0072] Furthermore, the accelerator is dimethylimidazole or 2-ethyl-4-methylimidazole. In actual production, they have high catalytic activity for the curing of epoxy resins and can significantly increase the curing speed and the performance of the cured resin.

[0073] A high-impact, lightweight, and high-strength composite board is prepared by the above-mentioned preparation method.

[0074] Furthermore, the thickness of the high-toughness surface layer is 10%-50% of the low-density core layer, which can significantly improve the impact resistance of the composite board while maintaining its overall lightweight. If the high-toughness surface layer is too thin, the impact resistance of the composite board will be poor; if the high-toughness surface layer is too thick, the overall density of the composite board will be too high. Example 1

[0075] This embodiment provides a high-impact, lightweight, and high-strength composite board, the specific preparation steps of which are as follows:

[0076] S1, the basis weight is 105g / m 2 The 2116 glass fiber is placed between two polyether thermoplastic polyurethane films and hot pressed at a temperature of 180°C and a pressure of 30 kg / cm 2 , hot pressing for 40 minutes and then taking it out to obtain a glass fiber cloth reinforced polyurethane film;

[0077] A 0.1 mm thick polyamide-polyether block copolymer film was placed between two adjacent layers of glass fiber cloth reinforced polyurethane film, and then hot pressed at a temperature of 180°C and a pressure of 8 kg / cm 2 , after hot pressing for 250s, take it out and cool it to 25℃ to obtain a high-toughness surface layer with a thickness of about 1.20mm;

[0078] S2, using 320 parts of butanone solution to dissolve 40 parts of modified nitrile rubber to obtain a modified nitrile rubber solution;

[0079] 225 parts of hollow glass microspheres were added to the modified nitrile rubber solution, and the hollow glass microspheres were evenly dispersed by stirring at a speed of 600 rpm. Then, stirring was continued at a speed of 80 rpm for 24 hours to complete the soaking process. After mixing evenly, the modified nitrile rubber solution was filtered out to obtain modified hollow glass microspheres;

[0080] Dissolve 6.4 parts of dicyandiamide and 0.09 parts of dimethylimidazole in 150 parts of ethylene glycol monomethyl ether to obtain a premixed solution;

[0081] Dissolve 70 parts of a solid bisphenol A epoxy resin having an epoxy equivalent weight of about 475 g / eq in 115 parts of acetone, then add the premixed solution, 30 parts of a liquid bisphenol A epoxy resin having an epoxy equivalent weight of about 185 g / eq, and 70 parts of a polyurethane-modified epoxy resin, and mix well to obtain a mixture solution;

[0082] Adding modified hollow glass microspheres to the mixture solution and mixing evenly to obtain a resin glue solution;

[0083] The basis weight is 48g / m 2 The 1080 glass fiber cloth was immersed in the resin glue, taken out after being completely soaked, and baked at 160℃ for 4.5min to obtain the epoxy glass fiber prepreg.

[0084] S3, stacking 25 zero-degree cut epoxy glass fiber prepregs of the same specifications to obtain a low-density core layer with a thickness of approximately 5.10 mm;

[0085] S4, the low-density core layer obtained in S3 is stacked between two high-toughness surface layers and hot pressed at a temperature of 160°C and a pressure of 5 kg / cm 2 Stepwise pressurization up to 10kg / cm 2 After hot pressing for 150 minutes, the product was taken out and transferred to a cold press to be cooled to 25°C to obtain a target product with a thickness of about 7.50 mm.

[0086] The composite structure of this embodiment is: "high-toughness surface layer-low-density core layer-high-toughness surface layer" arranged from bottom to top, wherein the high-toughness surface layer is composed of 4 glass fiber cloth reinforced polyurethane films and 3 polyamide-polyether block copolymer films stacked alternately, and the upper and lower surfaces of the high-toughness surface layer are both glass fiber cloth reinforced polyurethane films, and the low-density core layer is 25 semi-cured sheets that have not been hot-pressed. Example 2

[0087] This embodiment provides a high-impact, lightweight, and high-strength composite board, the specific preparation steps of which are as follows:

[0088] S1, the basis weight is 78g / m 2The 2113 glass fiber is arranged between two polyether thermoplastic polyurethane films and hot pressed at a temperature of 180°C and a pressure of 30kg / cm 2 , hot pressing for 40 minutes and then taking it out to obtain a glass fiber cloth reinforced polyurethane film;

[0089] A 0.125 mm thick polyamide-polyether block copolymer film was placed between two adjacent layers of glass fiber cloth reinforced polyurethane film, and then hot pressed at a temperature of 180°C and a pressure of 8 kg / cm 2 , after hot pressing for 250s, take it out and cool it to 25℃ to obtain a high-toughness surface layer with a thickness of about 1.20mm;

[0090] S2, using 300 parts of butanone solution to dissolve 30 parts of modified nitrile rubber to obtain a modified nitrile rubber solution;

[0091] 235 parts of hollow glass microspheres were added to the modified nitrile rubber solution, and the hollow glass microspheres were evenly dispersed by stirring at a speed of 600 rpm. Then, stirring was continued at a speed of 80 rpm for 24 hours to complete the soaking process. After mixing evenly, the modified nitrile rubber solution was filtered out to obtain modified hollow glass microspheres;

[0092] Dissolve 7.2 parts of dicyandiamide and 0.12 parts of dimethylimidazole in 150 parts of ethylene glycol monomethyl ether to obtain a premixed solution;

[0093] Dissolve 60 parts of a solid bisphenol A epoxy resin having an epoxy equivalent weight of about 475 g / eq in 130 parts of acetone, then add the premixed solution, 40 parts of a liquid bisphenol A epoxy resin having an epoxy equivalent weight of about 185 g / eq, and 80 parts of a polyurethane-modified epoxy resin, and mix well to obtain a mixture solution;

[0094] Adding modified hollow glass microspheres to the mixture solution and mixing evenly to obtain a resin glue solution;

[0095] The basis weight is 48g / m 2 The 1080 glass fiber cloth was immersed in the resin glue, taken out after being completely soaked, and baked at 160℃ for 4.5min to obtain the epoxy glass fiber prepreg.

[0096] S3, stack 25 zero-degree cut epoxy glass fiber prepregs of the same specifications to obtain a low-density core layer with a thickness of about 5.10 mm, and perform hot pressing on the low-density core layer at a temperature of 160°C and a pressure of 5 kg / cm 2 Stepwise pressurization up to 10kg / cm 2 , hot pressing for 60min;

[0097] S4: stack the low-density core layer after the pressure treatment in S3 between two high-toughness surface layers, and hot press at a temperature of 160°C and a pressure of 5kg / cm 2 Stepwise pressurization up to 10kg / cm 2 After hot pressing for 150 minutes, the product was taken out and transferred to a cold press to be cooled to 25°C to obtain a target product with a thickness of about 7.50 mm.

[0098] The composite structure of this embodiment is: "high-toughness surface layer-low-density core layer-high-toughness surface layer" arranged from bottom to top, wherein the high-toughness surface layer is composed of 4 glass fiber cloth reinforced polyurethane films and 3 polyamide-polyether block copolymer films stacked alternately, and the upper and lower surfaces of the high-toughness surface layer are both glass fiber cloth reinforced polyurethane films, and the low-density core layer is 25 semi-cured sheets that have been heat-pressed. Example 3

[0099] This embodiment provides a high-impact, lightweight, and high-strength composite board, the specific preparation steps of which are as follows:

[0100] S1, the basis weight is 105g / m 2 The 2116 glass fiber is placed between two polyether thermoplastic polyurethane films and hot pressed at a temperature of 180°C and a pressure of 30 kg / cm 2 , hot pressing for 40 minutes and then taking it out to obtain a glass fiber cloth reinforced polyurethane film;

[0101] A 0.30 mm thick polyamide-polyether block copolymer film was placed between two adjacent layers of glass fiber cloth reinforced polyurethane film, and then hot pressed at a temperature of 180°C and a pressure of 8 kg / cm 2 , after hot pressing for 250s, take it out and cool it to 25℃ to obtain a high-toughness surface layer with a thickness of about 1.20mm;

[0102] S2, using 300 parts of butanone solution to dissolve 20 parts of modified nitrile rubber to obtain a modified nitrile rubber solution;

[0103] 245 parts of hollow glass microspheres were added to the modified nitrile rubber solution, and the hollow glass microspheres were evenly dispersed by stirring at a speed of 600 rpm. Then, stirring was continued at a speed of 80 rpm for 24 hours to complete the soaking process. After mixing evenly, the modified nitrile rubber solution was filtered out to obtain modified hollow glass microspheres;

[0104] Dissolve 8.1 parts of dicyandiamide and 0.15 parts of dimethylimidazole in 150 parts of ethylene glycol monomethyl ether to obtain a premixed solution;

[0105] Dissolve 50 parts of a solid bisphenol A epoxy resin having an epoxy equivalent weight of about 475 g / eq in 145 parts of acetone, then add the premixed solution, 50 parts of a liquid bisphenol A epoxy resin having an epoxy equivalent weight of about 185 g / eq, and 90 parts of a polyurethane-modified epoxy resin, and mix well to obtain a mixture solution;

[0106] Adding modified hollow glass microspheres to the mixture solution and mixing evenly to obtain a resin glue solution;

[0107] The basis weight is 48g / m 2 The 1080 glass fiber cloth was immersed in the resin glue, taken out after being completely soaked, and baked at 160℃ for 4.5min to obtain the epoxy glass fiber prepreg.

[0108] S3, stacking 25 zero-degree cut epoxy glass fiber prepregs of the same specifications to obtain a low-density core layer with a thickness of approximately 5.10 mm;

[0109] S4, stack the low-density core layer obtained in S3 between two high-toughness surface layers, and hot press them at a temperature of 160°C and a pressure of 5 kg / cm 2 Stepwise pressurization up to 10kg / cm 2 After hot pressing for 150 minutes, the product was taken out and transferred to a cold press to be cooled to 25°C to obtain a target product with a thickness of about 7.50 mm.

[0110] The composite structure of this embodiment is: "high-toughness surface layer-low-density core layer-high-toughness surface layer" arranged from bottom to top, wherein the high-toughness surface layer is composed of 3 glass fiber cloth reinforced polyurethane films and 2 polyamide-polyether block copolymer films stacked alternately, and the upper and lower surfaces of the high-toughness surface layer are both glass fiber cloth reinforced polyurethane films, and the low-density core layer is 25 semi-cured sheets that have not been hot-pressed. Example 4

[0111] This embodiment provides a high-impact, lightweight, and high-strength composite board, the specific preparation steps of which are as follows:

[0112] S1, the basis weight is 105g / m 2 The 2116 glass fiber is placed between two polyether thermoplastic polyurethane films and hot pressed at a temperature of 180°C and a pressure of 30 kg / cm 2 , hot pressing for 40 minutes and then taking it out to obtain a glass fiber cloth reinforced polyurethane film;

[0113] A 0.1 mm thick polyamide-polyether block copolymer film was placed between two adjacent layers of glass fiber cloth reinforced polyurethane film, and then hot pressed at a temperature of 180°C and a pressure of 8 kg / cm 2, after hot pressing for 250s, it was taken out and cooled to 25°C to obtain a high-toughness surface layer with a thickness of about 0.84mm;

[0114] S2, taking the epoxy glass fiber prepreg obtained in S2 of Example 1;

[0115] S3, stacking 12 zero-degree cut epoxy glass fiber prepregs of the same specifications to obtain a low-density core layer with a thickness of approximately 2.50 mm;

[0116] S4, the low-density core layer and the low-density secondary core layer obtained in S3 are alternately stacked, and then hot pressed at a temperature of 160°C and a pressure of 5 kg / cm 2 Stepwise pressurization up to 10kg / cm 2 After hot pressing for 150 minutes, the product was taken out and transferred to a cold press to be cooled to 25°C to obtain a target product with a thickness of about 7.50 mm.

[0117] The composite structure of this embodiment is: "high-toughness surface layer-low-density core layer-high-toughness surface layer-low-density core layer-high-toughness surface layer" arranged from bottom to top, wherein the high-toughness surface layer is composed of 3 glass fiber cloth reinforced polyurethane films and 2 polyamide-polyether block copolymer films stacked alternately, and the upper and lower surfaces of the high-toughness surface layer are both glass fiber cloth reinforced polyurethane films, and the low-density core layer is 12 semi-cured sheets that have not been hot-pressed.

[0118] Comparative Example 1

[0119] This comparative example provides a high-impact, lightweight, and high-strength composite board, the specific preparation steps of which are as follows:

[0120] S1, the basis weight is 105g / m 2 The 2116 glass fiber is placed between two thermoplastic polyurethane films with a thickness of 0.1 mm and hot pressed at a temperature of 180°C and a pressure of 30 kg / cm 2 , hot pressing for 40 minutes and then taking it out to obtain a glass fiber cloth reinforced polyurethane film;

[0121] Five glass fiber cloth reinforced polyurethane films were stacked and hot pressed at a temperature of 180°C and a pressure of 8 kg / cm 2 , after hot pressing for 250s, take it out and cool it to 25℃ to obtain a high-toughness surface layer with a thickness of about 1.14-1.26mm;

[0122] S2, take the low-density core layer obtained in S3 of Example 1, and stack it between two layers of high-toughness surface layers, hot press, hot pressing temperature is 160 ° C, hot pressing pressure is 5kg / cm 2 Stepwise pressurization up to 10kg / cm 2After hot pressing for 150 minutes, the product was taken out and transferred to a cold press to be cooled to 25°C to obtain a target product with a thickness of about 7.50 mm.

[0123] Comparative Example 2

[0124] This comparative example provides a high-impact, lightweight, and high-strength composite board, the specific preparation steps of which are as follows:

[0125] S1, using 66 parts of ethylene glycol monomethyl ether to dissolve 3.4 parts of dicyandiamide and 0.06 parts of 2-methylimidazole to obtain a premixed solution;

[0126] 65 parts of bisphenol A epoxy resin with an epoxy equivalent weight of 475 g / eq and 35 parts of bisphenol A epoxy resin with an epoxy equivalent weight of 185 g / eq were added to 37 parts of acetone, and stirred and dispersed uniformly to obtain a mixture solution;

[0127] The premixed solution was added to the mixture solution and stirred evenly, and then 78.5 parts of hollow glass microspheres were added to the mixture and stirred evenly to obtain a resin glue solution;

[0128] The basis weight is 48g / m 2 The 1080 glass fiber cloth was immersed in the resin glue solution, taken out after being completely soaked, and then placed in a 150°C oven and baked for 3.5 minutes to obtain the epoxy glass fiber prepreg.

[0129] S2. Stack 25 epoxy glass fiber prepregs, place a release film on each of the top and bottom, and then overlap the mirror template on both sides to obtain a low-density core layer with a thickness of about 5.10 mm.

[0130] S3, take the high-toughness surface layer obtained in S1 of Example 1, stack the low-density core layer obtained in S2 between the two high-toughness surface layers, send them into a vacuum hot press, and press them at a pressure of 25Kg / cm 2 , temperature 180℃, hot press for 60 minutes, take out, transfer to a cold press and cool to 25℃ to obtain the target product with a thickness of about 7.50mm.

[0131] Relevant performance tests were performed on each embodiment and comparative example, and the results are as follows:

[0132] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Impact resistance (drop hammer impact test) OK OK OK OK NG NG <![CDATA[Average density (g / cm 3 )]]> 0.94 0.92 0.90 0.94 0.95 0.95

[0133] Table 1

[0134] Table 1 records the impact resistance and average density of each example and comparative example.

[0135] Examples 1, 2, 3, and 4 all employed polyether-based thermoplastic polyurethane, polyamide-polyether block copolymer, bisphenol A epoxy resin, polyurethane-modified epoxy resin, and hollow glass microspheres. The results showed that the resulting composite panels exhibited excellent impact resistance, capable of withstanding impact forces exceeding 400J, making them ideal for applications requiring high impact resistance, such as automotive, home appliances, and consumer electronics.

[0136] Among them, Comparative Example 1 did not use polyamide-polyether block copolymer in the high-toughness surface layer, so the impact resistance was worse than that of Example 1, specifically, the impact dent depth exceeded 3 mm, but there was no interlayer delamination phenomenon; Comparative Example 2 replaced the high-toughness low-density core layer with an ordinary ultra-low density epoxy glass fiber board filled with hollow glass microspheres on the basis of Example 1. Its impact resistance was worse than that of Comparative Example 1. After the drop hammer impact test, the low-density core layer was penetrated and interlayer delamination problems occurred.

[0137] If the materials mentioned in the above embodiments and comparative examples are in liquid form, they need to be stirred and dispersed evenly; if they are solid, they need to be stirred until they are completely dissolved to avoid affecting the preparation of the target product due to insufficient dissolution.

[0138] The materials used in the above embodiments are as follows:

[0139] Polyether thermoplastic polyurethane film: Model XG2285 produced by Shanghai Xingeng Environmental Protection Technology Co., Ltd.

[0140] Polyamide-polyether block copolymer film: Pebax 2533 produced by Arkema;

[0141] Modified nitrile rubber: NANCAR 1072CGL produced by Zhenjiang Nandi Chemical Co., Ltd.

[0142] Hollow glass microspheres: H38 model produced by Zhongke Yali Technology Co., Ltd.

[0143] Bisphenol A epoxy resin: Use NPES-901 or NPEL-128 produced by Nan Ya Plastics Corporation;

[0144] Polyurethane modified epoxy resin: EPU-133 model produced by Luohe High-tech Materials (Shanghai) Co., Ltd.

[0145] Relevant performance tests were conducted on the above-mentioned embodiments and comparative examples. Among them, the impact resistance test method of the composite plate is as follows: the sample is fixed on a rigid support, and a drop hammer impact test is performed using a spherical punch with a diameter of 25 mm. The drop weight is 26.5 kg, the drop height is 1558 mm, and the impact potential energy is 400 J. During the test, the sample must withstand the impact load of a circular convex hemispherical punch. The damage resistance of the sample is determined by the size and form of the impact scar left on the sample. After the drop hammer impact test, the sample is not penetrated and the impact dent depth is ≤3 mm, which is considered to have passed.

[0146] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for preparing a high-impact, lightweight, high-strength composite board, characterized in that: The following steps are involved: S1. Arranging a first glass fiber between two thermoplastic polyurethane films and hot pressing to obtain a glass fiber cloth reinforced polyurethane film; Placing a polyamide-polyether block copolymer film between two adjacent layers of the glass fiber cloth reinforced polyurethane film, and hot pressing to obtain a high-toughness surface layer; S2, adding modified hollow glass microspheres, bisphenol A epoxy resin, polyurethane modified epoxy resin, dicyandiamide, and accelerator to the solvent, mixing well, and obtaining a resin glue; Dipping the second glass fiber cloth into the resin glue solution, taking it out after it is completely soaked, and baking it to obtain an epoxy glass fiber prepreg; S3, stacking a plurality of the epoxy glass fiber prepregs to obtain a low-density core layer; S4. Stacking the low-density core layer between two adjacent high-toughness surface layers, hot pressing, and obtaining the target product.

2. The method for preparing a high-impact, lightweight, high-strength composite board according to claim 1, characterized in that: The S2 specifically includes the following steps: S21, dissolving the modified nitrile rubber using butanone to obtain a modified nitrile rubber solution; S22, adding hollow glass microspheres to the modified nitrile rubber solution, soaking, mixing, and filtering out the modified nitrile rubber solution to obtain the modified hollow glass microspheres; S23, adding the bisphenol A epoxy resin, the polyurethane-modified epoxy resin, the dicyandiamide, and the accelerator to the solvent, mixing them uniformly, to obtain a mixture solution; S24, adding the modified hollow glass microspheres to the mixture solution, mixing evenly, to obtain the resin glue solution.

3. The method for preparing a high-impact, lightweight, high-strength composite board according to claim 2, characterized in that: In S22, the specific steps of soaking are: firstly stirring at a medium speed to evenly disperse the hollow glass microspheres, and then continuing stirring at a low speed for 6-24 hours.

4. The method for preparing a high-impact, lightweight, high-strength composite board according to claim 2, wherein: The S23 further includes: using the solvent to pre-dissolve a portion of the bisphenol A epoxy resin, and using ethylene glycol monomethyl ether to pre-dissolve the dicyandiamide and the accelerator.

5. The method for preparing a high-impact, lightweight, high-strength composite board according to claim 1, characterized in that: The S3 further includes: performing a hot pressing process on the low-density core layer.

6. The method for preparing a high-impact, lightweight, high-strength composite board according to claim 1, characterized in that: In the step S4, at least two low-density core layers are provided.

7. The method for preparing a high-impact, lightweight, high-strength composite board according to claim 1, characterized in that: The mass fractions of each component in the resin glue are: 50-100 parts of bisphenol A epoxy resin; 50-100 parts of polyurethane modified epoxy resin; Accelerator 0.02-0.5 parts; 5-50 parts of modified nitrile rubber; 170-270 parts of hollow glass microspheres; 2-15 parts of dicyandiamide.

8. The method for preparing a high-impact, lightweight, high-strength composite board according to claim 1, characterized in that: The solvent is at least one of butanone and acetone, and the accelerator is dimethylimidazole or 2-ethyl-4-methylimidazole.

9. A high-impact, lightweight, high-strength composite panel, characterized by: The high-impact, lightweight, and high-strength composite board is prepared according to the method for preparing the high-impact, lightweight, and high-strength composite board according to any one of claims 1 to 8.

10. The high-impact, lightweight, high-strength composite panel according to claim 9, characterized in that: The thickness of the high-toughness surface layer is 10%-50% of the thickness of the low-density core layer.

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