Mould pressing method for reducing glass fabric lines

Abstract

The invention discloses a mould pressing method for reducing glass fiber cloth veins, which comprises the steps of laminated structure preparation, mould pressing curing, release film covering, texture inhibition, transfer printing and the like, and reconstructs a glass fiber texture transfer path through the collaborative design of gradient lamination, heightening and covering layer filling. Although a rigid structure of a prepreg in a traditional process provides high bending strength, a regular weaving interface of the prepreg causes anisotropic shrinkage of resin during mold pressing, a transition layer and a covering layer are introduced innovatively in the scheme, stress waves are dispersed through fine weaving, a high filling system inhibits flowing of the resin, and the peak intensity difference value of surface textures is reduced; through the synergistic effect of the rough surface of the release film and the filler resin, double barriers are formed to inhibit generation of glass fiber grains and inhibit resin migration. By means of the collaborative design, the overall process efficiency is improved, and forced cooling depending on the cold-in and cold-out process is not needed.

Description

Technical Field

[0001] This invention relates to the field of composite material technology, specifically a molding method for reducing fiberglass fabric texture. Background Technology

[0002] Fiberglass texture refers to a specific texture pattern formed on the surface of a product during the molding process of prepreg or unidirectional prepreg. Due to the regular woven structure of the material, the resin undergoes directional shrinkage along the fiber direction during curing and shrinkage, resulting in this texture. This texture not only interferes with the uniformity of the coating, making it difficult to perfectly achieve the designed texture effect, but also significantly impacts production efficiency. The industry commonly uses a cold-in, cold-out method, where the mold is heated to a certain temperature before the product is placed in and heated further, and then the mold is opened after cooling to room temperature. While this method effectively reduces fiberglass texture, it severely affects production efficiency.

[0003] Chinese patent literature discloses a high-strength, high-modulus glass fiber with high compressive strength, production method and system [Application No.: 202410972638.5, Publication No.: CN118495821B]. This invention adds 0.4-1.4 wt% TiO2 and 0-1.0 wt% BaO to the glass fiber composition. While ensuring the high strength and high modulus of the glass fiber, it can improve the hardness, heat resistance and compressive strength of the glass fiber. Although the material performance is improved by optimizing the fiber composition, it does not combine the synergistic effect of the low fiber density transition layer and the filler-containing covering layer, resulting in the difficulty in eliminating surface texture defects. Summary of the Invention

[0004] A molding method for reducing fiberglass fabric texture, characterized by comprising the following steps: (a) Fabrication of the layered structure: sequentially stacking a conventional structural layer, a texture transition layer, and a masking layer; (b) Molding and curing: Molding is carried out at a molding temperature of 140°C and a molding time of 60 minutes; (c) Covering with release film: The rough surface of polyester film is selected as the release film; (d) Texture suppression and transfer: The rough surface of the release film suppresses resin collapse and buildup, and the release film texture is transferred to the surface of the product after curing to weaken the glass fiber texture.

[0005] Preferably, the conventional structural layer consists of at least one layer of 2116 prepreg.

[0006] Through the above technical solution, the conventional structural layer plays a crucial role in the molding process, providing the necessary mechanical strength and thermal stability for the final product. The 2116 prepreg has high tensile strength, effectively supporting the structure and preventing structural instability caused by the glass fiber texture during molding. Simultaneously, the 2116 prepreg maintains its strength under high-temperature conditions, ensuring that the product does not experience performance degradation when used in high-temperature environments. The material selection and stacking method of this layer have a significant impact on the overall quality of the product.

[0007] Furthermore, the conventional structural layer design can also solve the fiberglass texture problem caused by uneven resin flow in traditional molding methods. The use of 2116 prepreg reduces excessive resin flow and shrinkage, allowing the resin to cure evenly, thus significantly reducing the appearance of fiberglass texture. This design, combined with subsequent texture transition layers and masking layers, improves the appearance quality of the product, making the surface smoother and meeting high appearance standards, ultimately enhancing the product's market competitiveness and performance.

[0008] Preferably, the texture transition layer is a three-layer structure consisting of a 1080 prepreg, a 1067 prepreg, and a 1067 prepreg.

[0009] Through the above technical solution, the three-layer structure of the texture transition layer effectively controls the resin flow during molding, reduces the fiber density of the fiberglass fabric, and thus significantly reduces resin buildup. This structural design, by optimizing the stacking sequence, reduces the formation of fiberglass textures while maintaining a certain strength, and improves the surface quality of the product. The combination of 1080 prepreg, 1067 prepreg, and 1067 prepreg utilizes their complementary different physical properties to ensure uniform resin distribution, reduce stress concentration during curing, and avoid surface defects caused by excessive resin flow.

[0010] Furthermore, the three-layer structure of the texture transition layer effectively bonds the resin to the fiberglass fabric, reducing the appearance of textures caused by resin shrinkage during molding. This not only improves the smoothness of the molded product's appearance but also ensures its surface smoothness and aesthetics, meeting high-quality appearance requirements. On this basis, the texture transition layer reduces the impact of fiberglass grain on the product, enhancing its market competitiveness and application performance.

[0011] Preferably, the covering layer is an epoxy resin film containing filler, wherein the filler is selected from one or more combinations of alumina, calcium carbonate, wood flour, talc, glass microspheres or fumed silica, and the number of layers is at least one.

[0012] Through the above technical solutions, the design of the masking layer not only effectively reduces the visibility of fiberglass texture but also significantly improves the surface quality of the product. The addition of the selected fillers to the epoxy resin film enhances its mechanical strength, improves its thermal stability, and enhances its resistance to chemical corrosion. Different combinations of fillers such as alumina, calcium carbonate, wood flour, talc, glass microspheres, or fumed silica, utilizing their different properties, work synergistically to make the film surface smoother, further reducing the transmission of fiberglass texture during molding.

[0013] Furthermore, the at least one layer design of the masking layer, through precise control of the type and quantity of fillers, ensures that the adhesive film can effectively mask the fiberglass texture on the substrate surface during molding, without affecting the mechanical properties of the product. This technical solution not only improves the appearance quality of the product, making its surface smoother and more uniform, but also enhances its durability and reliability in practical applications, thereby strengthening the product's market competitiveness.

[0014] Preferably, the epoxy resin film also contains a silane coupling agent and a dispersant.

[0015] Through the above technical solutions, the addition of silane coupling agents and dispersants significantly improves the interfacial bonding between the epoxy resin film and the inorganic fillers. Silane coupling agents can form chemical bonds between the resin and glass fiber, thereby improving the resin's adhesion and stability, and enhancing the overall structural strength of the product. The addition of dispersants effectively prevents filler agglomeration, ensuring uniform distribution of fillers in the resin film, further optimizing resin flowability during molding, and reducing defects caused by resin shrinkage.

[0016] Furthermore, the synergistic effect of the silane coupling agent and dispersant helps improve the flowability and permeability of the film, ensuring that the resin can better penetrate into the fiberglass fabric during molding, thereby reducing the formation of fiberglass texture. This improvement not only enhances the mechanical properties of the product but also optimizes its appearance quality, making its surface smoother and further strengthening the product's market competitiveness.

[0017] Preferably, the release film is a high-temperature resistant film with a release effect, including but not limited to polyethylene, polytetrafluoroethylene, silicone coated paper, plastic film, etc.

[0018] Through the above technical solutions, the selected release film possesses excellent high-temperature resistance and release effect, effectively preventing resin from adhering to the mold surface during molding. Materials such as polyethylene, polytetrafluoroethylene, silicone-coated paper, and plastic film, due to their superior temperature resistance and non-adhesive properties, can withstand the high temperatures and pressures required during molding, while ensuring that the resin can cure smoothly without causing damage to the material or contamination of the mold.

[0019] Furthermore, the special surface treatment of the release film, such as the low coefficient of friction of polytetrafluoroethylene, can effectively reduce resin flow during molding, preventing excessive resin flow or accumulation, thereby reducing the appearance of fiberglass texture. This technical solution, through the rational selection of the release film, not only improves the appearance quality of molded products but also increases production efficiency, reduces mold maintenance costs, and enhances the overall performance and market competitiveness of the products.

[0020] Preferably, the molding conditions are a temperature of 140°C and a molding time of 60 minutes.

[0021] The above technical solution ensures that the selected molding conditions guarantee full curing of the epoxy resin film during molding, while effectively reducing the appearance of fiberglass texture. The combination of a temperature of 140℃ and a molding time of 60 minutes allows the resin to reach the ideal curing state in a short time, without excessive resin flow or insufficient curing. These molding conditions not only guarantee uniform resin distribution and complete curing but also avoid fiberglass texture and surface defects caused by uneven temperature or excessively long molding times.

[0022] Furthermore, the application of these molding conditions helps improve production efficiency, shorten production cycles, and ensure the quality stability of molded products. During this process, the control of molding time and temperature effectively reduces defects caused by resin shrinkage, ensuring that the final product has a smooth, even surface and meets high standards of appearance quality, thus guaranteeing the product's market competitiveness.

[0023] Preferably, the method for measuring fiberglass texture includes the following steps: (a) Place the molded sample under a confocal microscope; (b) Select the Precision Surface Settings to optimize the sample surface; (c) Select a tangent spline of the sample surface texture and perform linear measurements along the diagonal of the rectangular texture; (d) Adjust the measurement range and calculate the peak distribution by taking the measurement values ​​of the same line segment; (e) Determine the suppression effect of glass fiber texture based on the difference between the maximum and minimum peak intensity of the peak position distribution.

[0024] Through the above technical solution, this glass fiber texture measurement method can accurately evaluate the glass fiber texture on the surface of molded products, ensuring that the quality of the product is controllable and consistent after molding. Optimizing the sample surface using a confocal microscope maximizes measurement accuracy and avoids measurement errors caused by surface unevenness or uneven lighting. Selecting tangent strips and performing linear measurements along the diagonal of the rectangular texture ensures a comprehensive evaluation of the entire surface texture, thereby obtaining an accurate peak distribution.

[0025] Furthermore, by adjusting the measurement range and calculating the maximum and minimum peak intensity differences in the peak position distribution, the suppression effect of glass fiber texture can be effectively evaluated, providing a quantitative basis for optimizing the molding process. This method not only improves the quality control level of molded products but also provides reliable data support for further suppression and optimization of glass fiber texture.

[0026] Compared with the prior art, the present invention has the following advantages: 1. This invention reconstructs the transmission path of glass fiber texture through a synergistic design of gradient layering and a high-filling masking layer. While the rigid structure of prepreg in traditional processes provides high flexural strength, its regular woven interface induces anisotropic resin shrinkage during molding, forming a grid pattern. This innovative solution introduces a transition layer and a masking layer, utilizing fine weaving to disperse stress waves and a high-filling system to suppress resin flow, thereby reducing the peak intensity difference of the surface texture.

[0027] 2. This invention utilizes the synergistic effect of the rough surface of the release film and the filler resin to form a double barrier that inhibits the formation of glass fiber texture. During molding, the rough surface of the PET release film mechanically restricts the flow direction of the molten resin, preventing it from collapsing directionally along the glass fiber weave path. The alumina filler in the cover layer significantly increases the viscosity of the epoxy resin film, further inhibiting resin migration. This synergistic design improves overall process efficiency and eliminates the need for forced cooling in a cold-in, cold-out process.

[0028] 3. The detection method of this invention uses a confocal microscope to select five regions along the diagonal of the product surface. A precise surface optimization algorithm is used to eliminate equipment errors. Linear measurements are performed along the diagonal of the rectangular texture, and the peak position distribution differences are calculated. The maximum and minimum peak intensity differences are used as the core quantitative indicators. This method upgrades traditional subjective visual inspection to objective data judgment, offering high measurement accuracy and enabling rapid and accurate results. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the process of this invention; Figure 2 This is a schematic diagram illustrating the stacking effect of the present invention; Figure 3 This is a schematic diagram of the glass fiber texture effect detection of the present invention; Figure 4 This is a schematic diagram of the comparative detection of glass fiber texture of different types of glass fibers according to the present invention; Figure 5 This is a schematic diagram illustrating the fiberglass texture effect of the present invention; Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] refer to Figures 1 to 5 .

[0032] A method for improving the texture of epoxy fiberglass composites after hot pressing, characterized by comprising the following steps: A molding method for reducing fiberglass fabric texture, characterized by comprising the following steps: (a) Fabrication of the layered structure: sequentially stacking a conventional structural layer, a texture transition layer, and a masking layer; (b) Molding and curing: Molding is carried out at a molding temperature of 140°C and a molding time of 60 minutes; (c) Covering with release film: The rough surface of polyester film is selected as the release film; (d) Texture suppression and transfer: The rough surface of the release film suppresses resin collapse and buildup, and the release film texture is transferred to the surface of the product after curing to weaken the glass fiber texture.

[0033] Stacking effect illustration reference Figure 2 .

[0034] Example 1 (Solution of the present invention): Gradient layered structure + alumina filler film Layer composition: includes a regular structure layer, a texture transition layer, and a masking layer. Standard structural layers: 2 layers of 2116 prepreg.

[0035] Texture transition layer: adopts a gradient layer design, layer 1: 1080 prepreg; layer 2: 1067 prepreg; layer 3: 1067 prepreg; Covering layer: 2 layers of epoxy resin film; formulation: epoxy resin (bisphenol A type, Tg=150℃); filler: alumina (30wt%, particle size 5μm); additives: silane coupling agent KH-550 (1wt%); dispersant BYK-111 (0.5wt%). Compression molding process: Compression molding parameters: 140℃ constant temperature, 60 minutes curing, 10MPa pressure Experimental variables Selection of release film Group 1: PET matte mask; Group 2: OPP glossy mask Effect verification refer to Figure 3 , Figure 3The images show glass fiber textures measured by confocal microscopy after molding with different release films. The left image shows the glass fiber texture measured by conventional 2116 on a matte PET film, while the right image shows the glass fiber texture measured by conventional 2116 on a glossy OPP film.

[0036] Comparative studies revealed significant differences in the fiberglass texture produced during the composite molding process between matte and glossy masks. The matte mask exhibited a unique microscopic rough structure, with irregular surface protrusions providing abundant sites for resin impregnation and adhesion during the molding process. Compared to glossy masks, this microscopic interfacial characteristic allows the resin to penetrate more fully into the fiberglass fabric, effectively suppressing the appearance of fiberglass texture and ultimately resulting in a smoother surface finish.

[0037] Example 2 (Comparative Scheme): Comparison of the Invention Scheme with the Traditional Process Scheme Group 1: Invention Scheme Layer composition: includes a regular structure layer, a texture transition layer, and a masking layer. Standard structural layers: 2 layers of 2116 prepreg.

[0038] Texture transition layer: adopts a gradient layer design, layer 1: 1080 prepreg; layer 2: 1067 prepreg; layer 3: 1067 prepreg; Covering layer: 2 layers of epoxy resin film; formulation: epoxy resin (bisphenol A type, Tg=150℃); filler: alumina (30wt%, particle size 5μm); additives: silane coupling agent KH-550 (1wt%); dispersant BYK-111 (0.5wt%). Release film: PET polyester film (rough surface Ra=1.2μm) Molding process: Molding parameters: 140℃ constant temperature, 60 minutes curing, 10Mpa pressure.

[0039] Group 2: Traditional solution of single 2116 prepreg stack Layer composition: 6 layers of 2116 prepreg, with no transition layer or masking layer.

[0040] Release film: PET polyester film (rough surface Ra=1.2μm).

[0041] Molding conditions: 140℃ / 60 minutes, pressure 10MPa.

[0042] The products manufactured using the above scheme were observed. Observation group 1: The effect diagram of the scheme of the present invention, as shown. Figure 4 As shown in the figure, the glass fiber textures of different types of glass fibers are compared. From left to right, the diagram shows the structural strength layered glass fiber texture, the texture transition layer glass fiber texture, and the cover layer glass fiber texture.

[0043] In the three-layer structure of this material system, the visibility of fiberglass grain exhibits a gradient distribution from strong to weak. As the core area bearing mechanical properties, the structural strength layer inevitably has significant fiberglass grain defects due to the need to meet stringent mechanical performance requirements. The weakening layer serves as a transitional layer between mechanical properties and appearance quality, effectively reducing the visual impact of fiberglass grain while maintaining a certain structural strength. The covering layer, as the surface, does not participate in bearing structural stress, but through its unique design, it conceals the residual fine fiberglass grain in the underlying layer, thereby ensuring that the product surface presents an ideal appearance.

[0044] Observe the products made using the above methods, and observe the fiberglass texture presentation effect of Group 1 and Group 2, such as... Figure 5 As shown in the figure, the image illustrates the effect of the fiberglass texture. From left to right, the image shows a schematic diagram of the matte fiberglass texture of a regular product and a schematic diagram of the matte fiberglass texture of a designed layered structure.

[0045] In traditional lamination processes, the surface of molded products exhibits obvious and dense fiberglass texture defects, severely affecting their appearance quality. However, by innovatively introducing a composite structure design of a weakening layer and a masking layer, microscopic observation using a confocal microscope shows that the fiberglass texture on the optimized product surface is significantly suppressed, with the texture becoming almost invisible to the naked eye, resulting in a substantial improvement in appearance quality.

[0046] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A molding method for reducing fiberglass cloth texture, characterized in that, Includes the following steps: (a) Fabrication of the layered structure: sequentially stacking a conventional structural layer, a texture transition layer, and a masking layer; (b) Molding and curing: Molding is carried out at a molding temperature of 140°C and a molding time of 60 minutes; (c) Covering with release film: The rough surface of polyester film is selected as the release film; (d) Texture suppression and transfer: The rough surface of the release film suppresses resin collapse and buildup, and the release film texture is transferred to the surface of the product after curing to weaken the glass fiber texture.

2. The molding method according to claim 1, characterized in that, The conventional structural layer consists of at least one layer of 2116 prepreg.

3. The molding method according to claim 1, characterized in that, The texture transition layer is a three-layer structure consisting of a 1080 prepreg, a 1067 prepreg, and a 1067 prepreg.

4. The molding method according to claim 1, characterized in that, The covering layer is an epoxy resin film containing filler. The filler is selected from one or more combinations of alumina, calcium carbonate, wood flour, talc, glass microspheres or fumed silica, and the number of layers is at least one.

5. The molding method according to claim 1, characterized in that, The epoxy resin film also contains a silane coupling agent and a dispersant.

6. The molding method according to claim 1, characterized in that, The release film is a high-temperature resistant film with a release effect, including but not limited to polyethylene, polytetrafluoroethylene, silicone coated paper, plastic film, etc.

7. The molding method according to claim 1, characterized in that, The molding conditions are a temperature of 140°C and a molding time of 60 minutes.

8. The molding method according to claim 1, characterized in that, The fiberglass texture measurement method includes the following steps: (a) Place the molded sample under a confocal microscope; (b) Select the Precision Surface Settings to optimize the sample surface; (c) Select a tangent spline of the sample surface texture and perform linear measurements along the diagonal of the rectangular texture; (d) Adjust the measurement range and calculate the peak distribution by taking the measurement values ​​of the same line segment; (e) Determine the suppression effect of glass fiber texture based on the difference between the maximum and minimum peak intensity of the peak position distribution.

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