A method for off-site gas flow guiding for composite vacuum bag molding

Abstract

The present application relates to the technical field of composite material forming, in particular to a kind of off-site gas flow guide method of composite material vacuum bag forming.It includes the following steps: after impregnating off-site flow guide agent using non-woven grid cloth, drying, preparing off-site gas flow guide net;Off-site gas flow guide net is laid in the interlayer interval of prepreg, and is cured with prepreg in the curing process.The purpose of the off-site gas flow guide method of composite material vacuum bag forming is to solve the problem of internal quality defects such as porosity that easily occurs in the vacuum forming and curing process when forming large thickness composite material using large tow high weight prepreg, reduce material process cost by reducing the number of laid layers, effectively improve the production efficiency of existing large thickness composite material products.

Description

Technical Field

[0001] This invention relates to the field of composite material forming technology, and specifically to a method for off-site gas diversion in composite material vacuum bag forming. Background Technology

[0002] Prepreg vacuum bag molding technology is a low-cost molding technology for composite materials. Compared with traditional autoclave molding technology, it has the cost advantages of low equipment investment and economical maintenance costs.

[0003] When using vacuum bag forming technology to produce thicker parts, vacuum pressure alone is insufficient to fully remove air from the prepreg. After curing, the internal porosity of the part increases with its thickness. This high porosity from vacuum bag forming reduces the mechanical and fatigue properties of the composite material. Existing technologies generally address the process characteristics of vacuum bag forming by modifying the material in situ, such as reducing the prepreg basis weight and increasing the prepreg impregnation degree, to improve the yield of vacuum bag forming. However, this in situ modification method reduces the material's areal density, increasing material production and processing costs.

[0004] Therefore, the inventors provide a method for displaced gas diversion in composite material vacuum bag forming. Summary of the Invention

[0005] (1) Technical problems to be solved

[0006] This invention provides a method for displaced gas diversion in vacuum bag forming of composite materials, which solves the technical problem that internal quality defects such as pores are prone to occur during the vacuum forming and curing process when using large-bundle, high-grammage prepreg to form thick composite materials.

[0007] (2) Technical solution

[0008] This invention provides a method for guiding out-of-place gas in composite material vacuum bag forming, comprising the following steps:

[0009] An off-site gas guiding net was prepared by impregnating a non-woven mesh with an off-site guiding agent and then drying it.

[0010] The off-site gas guide net is laid at intervals between the layers of the prepreg and cured together with the prepreg during the curing process.

[0011] Furthermore, the preparation of the gas diversion mesh by impregnating a nonwoven mesh with a diversion agent and then drying it is specifically as follows:

[0012] The nonwoven mesh fabric, which is made of continuous polyester fiber, glass fiber or carbon fiber bonded with thermoplastic adhesive, is fully impregnated with the displacement agent and then dried to prepare the displacement gas guiding net.

[0013] Furthermore, the structure of the off-site gas guiding net includes flat laying, diagonal laying, and diamond pattern.

[0014] Furthermore, the areal density of the off-site gas guiding mesh is 5–25 g / m². 2 .

[0015] Further, the explanted flow agent comprises epoxy resin, curing agent, accelerator, and toughening agent, and the explanted flow agent forms a flow agent solution with acetone solvent; the epoxy resin accounts for 40% to 50% of the total weight of the flow agent solution, the curing agent accounts for 25% to 28% of the total weight of the flow agent solution, the accelerator accounts for 1% to 5% of the total weight of the flow agent solution, the toughening agent accounts for 1% to 3% of the total weight of the flow agent solution, and the acetone solvent accounts for 20% to 25% of the total weight of the flow agent solution.

[0016] Furthermore, the epoxy resin is one or a mixture of several of bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin and phenolic epoxy resin.

[0017] Furthermore, the epoxy value of the epoxy resin is 0.4 to 0.6 mol / 100g.

[0018] Furthermore, the curing agent is an acid anhydride-based curing agent.

[0019] Furthermore, the accelerator is a mixture of 9920 resin and dimethylaminomethyl, and the mixing ratio of 9920 resin and dimethylaminomethyl is 1:1 to 1:1.3.

[0020] Furthermore, the toughening agent is one or a mixture of several resins such as polyaryletherketone, polyethersulfone, and polysulfone.

[0021] (3) Beneficial effects

[0022] In summary, this invention utilizes an off-site gas guiding mesh for vacuum bag molding of thermosetting prepregs. During the curing process, the off-site gas guiding mesh forms an effective guiding channel between the prepreg layers. The off-site guiding agent impregnated on the surface of the guiding mesh can improve the interlayer flow effect during the resin curing process, thereby improving the internal quality of thick composite materials formed in vacuum bags. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1This is a schematic flowchart of an off-site gas diversion method for composite material vacuum bag forming according to an embodiment of the present invention;

[0025] Figure 2(a) is a schematic diagram of an off-site gas guiding net provided in an embodiment of the present invention;

[0026] Figure 2(b) is a schematic diagram of another off-site gas guiding net provided in an embodiment of the present invention;

[0027] Figure 2(c) is a schematic diagram of another off-site gas guiding net provided in an embodiment of the present invention;

[0028] Figure 3 This is a schematic diagram of a nonwoven mesh fabric impregnation process with a gas-conducting solution provided in an embodiment of the present invention;

[0029] Figure 4 This is a schematic diagram of the structure of a composite material vacuum bag forming off-site gas guiding layup provided in an embodiment of the present invention.

[0030] In the picture:

[0031] 1-Unwinding device; 2-Solution tank; 3-Drying oven; 4-Rewinding device; 5-Nonwoven mesh fabric. Detailed Implementation

[0032] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present invention by way of example, but should not be used to limit the scope of the present invention, that is, the present invention is not limited to the described embodiments.

[0033] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0034] Figure 1 This is a schematic flowchart of a method for displaced gas diversion in composite material vacuum bag forming according to an embodiment of the present invention, as shown below. Figure 1 As shown, the method may include the following steps:

[0035] S100. A gas flow guide net is prepared by impregnating a non-woven mesh with a gas flow guide agent and then drying it.

[0036] S200. A gas-guiding mesh is laid at intervals between layers of the prepreg and cured together with the prepreg during the curing process.

[0037] In the above embodiments, unlike the traditional in-situ modification method that optimizes the resin matrix or resin fiber interface of composite materials, the concept of an off-site gas guiding network is introduced outside the composite material body. A non-woven network with special additives is added between the composite material layers. During the curing process, the prepreg interlayer guiding channels are artificially established to accelerate the resin flow and gas discharge in the composite material blank, realize efficient vacuum forming of thermosetting prepreg, and improve the internal quality of thick composite materials formed by vacuum bag forming.

[0038] As an optional implementation, in step S100, a nonwoven mesh fabric is impregnated with a displacement agent and then dried to prepare a displacement gas guiding net. Specifically, a nonwoven mesh fabric made of continuous polyester fiber, glass fiber or carbon fiber bonded with a thermoplastic adhesive is fully impregnated with a displacement agent and then dried to prepare a displacement gas guiding net.

[0039] As an optional implementation method, such as Figures 2(a) to 2(c) As shown, the structural forms of the free-floating gas guiding net include flat, diagonal, and diamond patterns. The specific structural form of the free-floating gas guiding net is not limited and can be selected according to actual needs.

[0040] As an optional implementation, the areal density of the off-site gas guiding mesh is 5–25 g / m². 2 Specifically, such as Figure 3 As shown, the nonwoven mesh fabric 5 is transported by the cooperation of the unwinding device 1 and the winding device 4, and enters the solution pool 2 for impregnation with the displacement guiding agent. After impregnation, the nonwoven mesh fabric 5 enters the drying box 3 for drying. The drying temperature is selected in the range of 30 to 80°C according to the equipment settings, and the drying time is no more than 30 minutes.

[0041] As an optional embodiment, the explanted flow agent includes epoxy resin, curing agent, accelerator, and toughening agent, and the explanted flow agent forms a flow agent solution with acetone solvent; the epoxy resin accounts for 40% to 50% of the total weight of the flow agent solution, the curing agent accounts for 25% to 28% of the total weight of the flow agent solution, the accelerator accounts for 1% to 5% of the total weight of the flow agent solution, the toughening agent accounts for 1% to 3% of the total weight of the flow agent solution, and the acetone solvent accounts for 20% to 25% of the total weight of the flow agent solution.

[0042] Specifically, the mass percentages of epoxy resin, curing agent, accelerator, toughening agent, and acetone solvent are formulated based on the relevant chemical properties of the out-of-place flow guiding agent. The out-of-place flow guiding agent uses epoxy resin as the matrix to eliminate the interfacial effect of the out-of-place flow guiding mesh in the resin matrix. An appropriate amount of curing agent can improve the chemical properties of the flow guiding agent, adapting it to different composite resin matrices and achieving co-curing during the process. Simultaneously, the addition of accelerators and toughening agents optimizes the flow channel effect of the out-of-place flow guiding mesh between layers, achieving efficient flow guiding and venting. Finally, adding a certain proportion of acetone solution improves the rheological properties of the out-of-place flow guiding agent at room temperature, achieving efficient preparation of the out-of-place gas flow guiding mesh.

[0043] As an optional implementation, the epoxy resin is one or a mixture of several types of bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, and phenolic epoxy resin.

[0044] The specific components of the epoxy resin are not limited and can be selected according to actual needs. The epoxy value of the epoxy resin is 0.4 to 0.6 mol / 100g.

[0045] As an optional implementation method, the curing agent is an acid anhydride-based curing agent. Specifically, it can be one or a mixture of several of phthalic anhydride, tetrahydrophthalic anhydride, and methyltetrahydrophthalic anhydride. The specific components of the curing agent are not limited and can be selected according to actual needs.

[0046] As an optional implementation, the accelerator is a mixture of 9920 resin and dimethylaminomethyl, and the mixing ratio of 9920 resin to dimethylaminomethyl is 1:1 to 1:1.3. The specific components of the accelerator are not limited and can be selected according to actual needs. This ratio was determined through influencing factor level experiments. This ratio is beneficial for maximizing the flow-guiding effect of the off-site flow-guiding agent. An inappropriate ratio will result in unsatisfactory flow-guiding effect or internal defects caused by excessive resin flow.

[0047] As an optional implementation, the toughening agent is one or a mixture of several resins such as polyaryletherketone, polyethersulfone, and polysulfone. The specific components of the toughening agent are not limited and can be selected according to actual needs.

[0048] like Figure 4 As shown, the gas-displacement guiding mesh is flexible and foldable, making it easy to cut into various sizes. During the prepreg laying process, the gas-displacement guiding mesh can be laid layer by layer or in layers between the prepreg layers. The edge contour of the guiding mesh should be larger than the size of the prepreg blank to facilitate gas escape during the vacuum bag forming process, without requiring changes to the composite material forming process. The 50mm thick composite material sheet formed by the vacuum bag forming gas-displacement guiding method can reduce the porosity to within 1%.

[0049] It should be noted that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. The present invention is not limited to the specific steps and structures described above and shown in the figures. Furthermore, for the sake of brevity, detailed descriptions of known methods and techniques are omitted here.

[0050] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art without departing from the scope of the invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this application should be included within the scope of the claims of this application.

Claims

1. A method for guiding out-of-place gas in a composite material vacuum bag forming process, characterized in that, The method includes the following steps: An off-site gas guiding net was prepared by impregnating a non-woven mesh with an off-site guiding agent and then drying it. The off-site gas guiding mesh is laid at intervals between the layers of the prepreg and cured together with the prepreg during the curing process; The free-floating agent comprises epoxy resin, curing agent, accelerator, and toughening agent. The free-floating agent forms a flow-conducting agent solution with acetone solvent. The epoxy resin accounts for 40% to 50% of the total weight of the flow-conducting agent solution, the curing agent accounts for 25% to 28% of the total weight of the flow-conducting agent solution, the accelerator accounts for 1% to 5% of the total weight of the flow-conducting agent solution, the toughening agent accounts for 1% to 3% of the total weight of the flow-conducting agent solution, and the acetone solvent accounts for 20% to 25% of the total weight of the flow-conducting agent solution.

2. The method for guiding off-site gas flow in composite material vacuum bag forming according to claim 1, characterized in that, The process of preparing a gas-displacement guiding net by impregnating a non-woven mesh fabric with a displacement guiding agent and then drying it is specifically as follows: The nonwoven mesh fabric, which is made of continuous polyester fiber, glass fiber or carbon fiber bonded with thermoplastic adhesive, is fully impregnated with the displacement agent and then dried to prepare the displacement gas guiding net.

3. The method for guiding out-of-place gas in composite material vacuum bag forming according to claim 1 or 2, characterized in that, The structure of the off-site gas guiding net includes flat laying, diagonal laying, and diamond pattern.

4. The method for guiding out-of-place gas in composite material vacuum bag forming according to claim 1, characterized in that, The surface density of the off-site gas guiding mesh is 5–25 g / m³. 2 .

5. The method for guiding off-site gas in composite material vacuum bag forming according to claim 1, characterized in that, The epoxy resin is one or a mixture of several of the following: bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, and phenolic epoxy resin.

6. The method for guiding out-of-place gas in composite material vacuum bag forming according to claim 5, characterized in that, The epoxy value of the epoxy resin is 0.4 to 0.6 mol / 100g.

7. The method for guiding off-site gas in composite material vacuum bag forming according to claim 1, characterized in that, The curing agent is an acid anhydride-based curing agent.

8. The method for guiding out-of-place gas in composite material vacuum bag forming according to claim 1, characterized in that, The accelerator is a mixture of 9920 resin and dimethylaminomethyl, and the mixing ratio of 9920 resin and dimethylaminomethyl is 1:1 to 1:1.

3.

9. The method for guiding off-site gas in composite material vacuum bag forming according to claim 1, characterized in that, The toughening agent is one or a mixture of several resins such as polyaryletherketone, polyethersulfone, and polysulfone.

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