A prepreg vacuum plate and its manufacturing method

Abstract

The present invention relates to a prepreg vacuum panel and a manufacturing method thereof, and pertains to the field of vacuum panel manufacturing. The prepreg vacuum panel structurally includes upper and lower panels, middle support columns, circumferential sealing foam, and circumferential sealing resin. The upper and lower panels and the support columns are fiber-reinforced composite materials, and the space enclosed by the upper and lower panels, the support columns, and the circumferential sealing foam is a vacuum. The vacuum panel of the present invention has the advantages of heat insulation, high strength, and light weight compared with traditional plates. It can not only improve the performance such as heat preservation of products, but also reduce energy consumption and be more energy-efficient when applied to transportation equipment.

Description

Technical Field

[0001] The present invention relates to the field of vacuum plate manufacturing, and particularly to a structure of a fiber-reinforced composite vacuum plate and a manufacturing method thereof. Background Art

[0002] At present, the performance requirements for insulating boards in cutting-edge special fields such as new energy, national defense, chemical industry, aerospace, and transportation are becoming increasingly stringent. Traditional insulating boards are mainly organic and inorganic materials, each having its own advantages and disadvantages in terms of thermal conductivity and combustion performance, and it is difficult for them to complement each other, thus unable to meet the diversified requirements for insulating materials today. As a new generation of insulating material structure, the vacuum plate not only has a lower thermal conductivity than traditional organic insulating materials, but also can reach the combustion performance level of traditional inorganic insulating materials, making it the most promising insulating material structure for research at present.

[0003] Traditional insulating materials have poor corrosion resistance and low strength, and need to be subjected to anti-corrosion treatment and regular maintenance, which seriously affects their service life. Compared with traditional insulating materials, fiber-reinforced composites have the advantages of light weight, high modulus, high specific strength, and corrosion resistance. However, most of the existing insulating materials on the market are solid-structured composites, and these types of insulating boards fail to fully utilize the excellent performance brought by the vacuum structure of the composite material, resulting in a relatively heavy self-weight and being unable to meet the growing demand for ultra-light components in high-precision and cutting-edge fields. Summary of the Invention

[0004] Aiming at the above problems, the purpose of the present invention is to provide a vacuum plate with lighter weight, higher strength, and better heat insulation effect and a manufacturing method thereof.

[0005] To achieve the above object, the present invention discloses a prepreg vacuum plate and a manufacturing method thereof: the prepreg vacuum plate structurally includes upper and lower panels, middle support columns, circumferential sealing foam, and circumferential sealing resin. The upper and lower panels and the support columns are fiber-reinforced composites, and the space enclosed by the upper and lower panels, the support columns, and the circumferential sealing foam is a vacuum. The upper and lower panels and the support columns can be carbon fiber, glass fiber, or aramid fiber prepregs. The manufacturing method of this vacuum plate includes the following steps:

[0006] First, according to the thickness of the upper and lower panels, prepregs are laid on the upper and lower surfaces of a soluble or low-temperature fusible material plate;

[0007] Second, the support columns are inserted into the thickness direction of the laminated plate after laying, so that they penetrate through the laminated plate;

[0008] Third, the pierced plate material is cured by methods such as compression molding, autoclave molding, or vacuum bag pressing, and the heating temperature is lower than the melting point of the middle filling material, so that it remains stiff during the molding process to ensure the molding pressure of the prepreg;

[0009] Fourth, after the sheet material is cured, remove it according to the physical properties of the filling material. If the material soluble in water, acid or alkali is used, the filling material can be removed by dissolving it in a solvent through the dissolution method. If a low-temperature molten material is used, the filling material can be removed by heating to make it flow;

[0010] Fifth, stick the unfoamed closed-cell foam sheet on the adhesive film. The size of the adhesive film is in accordance with the size of the periphery of the sheet material to be stuck, and the length and width of the foam sheet are each 0.5 to 16 mm smaller than the length and width of the adhesive film. Among them, the curing temperature of the adhesive film is not lower than the foaming temperature of the foam sheet, and the foaming ratio of the foam sheet is less than 20;

[0011] Sixth, stick the foam adhesive film sheet stuck together in the previous step on the periphery of the sheet material, with the foam sheet as the inner side and the adhesive film as the outer side, and leave pores or holes when sticking, so that the inner cavity of the sheet material is not completely sealed, which is convenient for later vacuum evacuation;

[0012] Seventh, place the sheet material with the periphery well-stuck in the mold cavity, evacuate the mold cavity, and heat. First, control the heating temperature at the foaming temperature of the foam to make the foam foam. The heating time is the time for the foam to be fully foamed, and then raise it to the curing temperature of the adhesive film sheet. The heating time is for the resin to cure. During this process, the foam will expand and foam in the mold, fill the pores or holes to seal the sheet material. At the same time, the adhesive film will have fluidity after heating and fill the pores not filled by the foam to further seal the outer layer of the foam;

[0013] Eighth, open the mold and trim the edges to obtain the prepreg vacuum board.

[0014] Compared with the existing thermal insulation materials, the prepreg composite vacuum board manufactured by the present invention uses its hollow structure as the vacuum thermal insulation layer, which can greatly reduce its thermal conductivity and improve the thermal insulation effect. The material of the vacuum board of the present invention is mainly fiber-reinforced composite material, and its remarkable feature is that it has higher strength under a lighter mass, and can greatly reduce energy consumption when applied in the fields of transportation, aerospace and construction.

[0015] The foam material adopted by the present invention can be materials that can be foamed under a certain vacuum degree, such as epoxy resin, polyurethane, polyethylene, etc. The foam holes are closed cells. When it is not foamed in the mold, since it does not seal the inner cavity of the sheet material, the gas in the board can be removed by evacuating the mold, so that the sheet material obtains a vacuum environment. And by using the characteristics that the foaming material can expand and has closed cells, it can stick and seal the periphery of the sheet material to prevent air from entering the board.

[0016] In the manufacturing process of the prepreg vacuum panel of the present invention, a soluble or low-temperature molten material is used as the sandwich material to separate the upper and lower panels by a certain distance, which bears a large pressure during the pressurized curing of the composite material panel and provides a supporting role. After the material is cured, it is removed by dissolution or melting methods, thereby generating a hollow structure. During the use of the vacuum panel, the support columns will provide a pressure-bearing role.

[0017] The support column material can be a thin metal rod, or a thin rod of a high-performance fiber-reinforced resin matrix composite material such as carbon fiber, glass fiber, basalt fiber, or hemp.

[0018] On the one hand, the role of the adhesive film is to seal the periphery of the vacuum board material. During the use of the vacuum panel, it can protect the foam material and improve the mechanical properties of the periphery of the board. On the other hand, during the forming process of the vacuum panel, the adhesive film will have fluidity after heating. Under the action of the foam expansion force, it can fill the reserved pores or holes, and also plays a sealing role. As the second sealing layer except for the foam layer, it fully ensures the sealing effect of the board.

[0019] The reason why the length and width of the foam sheet are each 0.5 to 16 mm smaller than the length and width of the adhesive film is to enable the adhesive film to be in full contact with the upper and lower panels of the vacuum board material during the pasting of the board material and the curing of the board. After curing, it can form the outermost sealing layer, so that the foam material will not be exposed outside the board. On the one hand, it can ensure the mechanical properties, and on the other hand, it can give full play to the role of the second sealing layer.

[0020] To facilitate the evacuation of the interior of the vacuum board material before forming, when the foam adhesive film is pasted around the board, it should not be completely sealed, and pores or holes need to be left, but the pores or holes should not be too large to prevent the board from being difficult to seal during later foaming. The area of the pores or holes should be less than 1 cm 2 .

[0021] The adhesive film material is an uncured thermosetting hot melt adhesive film material. On the one hand, the thermosetting adhesive film has a low curing temperature and can be cured at the foaming temperature of the foam layer. On the other hand, the thermosetting hot melt adhesive film has good fluidity after heating and can fill the holes to ensure the sealing effect.

[0022] The curing temperature of the adhesive film should not be lower than the foaming temperature of the foam sheet, ensuring that the foaming material first foams and expands, enabling the adhesive film to closely adhere to the mold, and then curing after ensuring the shape of the product. At the same time, to prevent the excessive foaming pressure from causing the adhesive film to shift and ensure that the vacuum cavity space is not overly reduced, the foaming ratio should be controlled within 20. Description of the Drawings

[0023] Figure 1 It is a schematic diagram of the paving operation of the upper and lower panels and the low-temperature molten material plate of a prepreg vacuum panel of the present invention.

[0024] Figure 2 Schematic diagram of the support column of a prepreg vacuum plate of the present invention piercing the laid sandwich panel structure.

[0025] Figure 3 Schematic diagram of the structure of removing the middle low-temperature fusible material after the prepreg vacuum plate of the present invention is cured and formed.

[0026] Figure 4 Schematic diagram of the operation of placing closed-cell foaming material with adhesive film attached around the prepreg vacuum plate of the present invention.

[0027] Figure 5 Schematic diagram of the prepreg vacuum plate structure of the present invention. Specific embodiments

[0028] The following will describe the embodiments of the present invention in detail with reference to the accompanying drawings.

[0029] Taking the manufacture of a carbon fiber prepreg vacuum plate as an example, the manufactured carbon fiber prepreg vacuum plate is 300 mm long, 300 mm wide and 30 mm thick. The specific implementation steps are as follows:

[0030] First, prepare a water-soluble material, a polyvinyl alcohol plate 101, which is 300 mm long, 300 mm wide and 28 mm thick, and lay low-temperature curing carbon fiber prepreg 102 on its upper and lower surfaces respectively, with a thickness of 1 mm, as Figure 1 shown.

[0031] Second, take a support column 201 with a length of 30 mm and a diameter of 2 mm, and penetrate it through the thickness direction of the laid sandwich panel, as Figure 2 shown.

[0032] Third, place the pierced sandwich panel in a heating device at the melting point temperature (70 °C) of the polyvinyl alcohol plate 101 and cure it by using a molding method.

[0033] Fourth, put the cured sandwich panel into water at 60 °C to completely dissolve the middle material, the polyvinyl alcohol plate 101, in warm water and then dry it. After drying, it is as Figure 3 shown.

[0034] Fifth, take four closed-cell epoxy foamable sheets 401 (foaming ratio is 3, foaming temperature is 130 °C, time is 2 hours), which are 296 mm long, 296 mm wide and 2 mm thick, and stick them on an epoxy resin adhesive film 402 with a thickness of 0.5 mm (curing temperature is 130 °C, time is 2.5 hours), and align the centers. The length and width of the adhesive film 402 are both 4 mm longer than those of the closed-cell foaming material 401.

[0035] Sixth, place the closed-cell foaming material 401 with a film on its four sides around the board. The side with the film 402 is on the outside, and ensure that there are holes 403 with a size of 1mm * 1mm left during pasting, as Figure 4 shown.

[0036] Seventh, place the whole board 100 in the mold cavity, evacuate the mold cavity to make the inside of the board in a vacuum state of -35KPa.

[0037] Eighth, heat the mold cavity, control the heating temperature at 130°C, and heat for 2.5 hours. This temperature can not only make the foam expand but also cure the film, so that the closed-cell foaming material 401 expands and foams, and at the same time the film 402 flows by heat and fills the pores to achieve double-layer sealing of the board.

[0038] Ninth, open the mold and trim the product to obtain the prepreg vacuum board, as Figure 5 shown.

[0039] It should be noted here that the above embodiments are only used to illustrate the technical solutions of the present invention and do not limit the protection scope of the claims. Although the present invention has been described in detail with reference to the embodiments, those of ordinary skill in the art should understand that non-essential modifications or equivalent replacements made to the technical solutions of the present invention cannot depart from the essence of the technical solutions of the present invention, and should all be within the protection scope of the claims of the present invention.

Claims

1. A prepreg vacuum plate, which structurally includes upper and lower panels, middle support columns, circumferential sealing foam and circumferential sealing resin. The upper and lower panels and the support columns are fiber-reinforced composite materials, and the space enclosed by the upper and lower panels, the support columns and the circumferential sealing foam is a vacuum. The manufacturing method of this prepreg vacuum plate, characterized in that it includes the following steps: First, according to the thickness of the upper and lower panels, prepregs are laid on the upper and lower surfaces of a soluble or low-temperature fusible material plate; Second, the support columns are stabbed into the thickness direction of the laminated plate after laying, so that they penetrate through the laminated plate; Third, the stabbed plate material is cured by methods such as compression molding, autoclave molding or vacuum bag pressing. The heating temperature is lower than the melting point of the middle filling material, so that it remains stiff during the molding process to ensure the molding pressure of the prepreg; Fourth, after the plate is cured, according to the physical properties of the filling material, it is removed. If a material soluble in water, acid or alkali is used, the filling material is dissolved in a solvent by a dissolution method and removed. If a low-temperature fusible material is used, the filling material is removed by heating to make it flow; Fifth, the unfoamed closed-cell foam sheet is adhered to the adhesive film. The size of the adhesive film is in accordance with the size of the periphery of the adhered plate, and the length and width of the foam sheet are 0.5 to 16 mm smaller than the length and width of the adhesive film, so that the adhesive film is directly adhered to the upper and lower panels; Sixth, the foam sheet with the adhesive film adhered in the previous step is adhered to the periphery of the plate. The foam sheet is used as the inner side and the adhesive film is used as the outer side and adhered around the plate. When adhering, pores or holes are left, so that the inner cavity of the plate is not completely sealed, which is convenient for later vacuum pumping and exhaust; Seventh, the plate adhered around is placed in the mold cavity, the mold cavity is evacuated, and heated. The heating temperature is first controlled at the foam foaming temperature to make the foam foam. The heating time is the time for the foam to foam well, and then it is raised to the curing temperature of the adhesive film sheet. The heating time cures the resin. During this process, the foam will expand and foam in the mold, fill the pores or holes to seal the plate. At the same time, the adhesive film will be fluid after heating and fill the pores not filled by the foam, and further seal on the outer layer of the foam; Eighth, open the mold and trim to obtain the prepreg vacuum plate.

2. A prepreg vacuum plate according to claim 1, characterized in that the foaming ratio of the foam sheet is less than 20.

3. A prepreg vacuum plate according to claim 1, characterized in that the curing temperature of the adhesive film is not lower than the foaming temperature of the foam sheet.

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