A composite film for vacuum bag press molding

Abstract

The utility model relates to a kind of composite membranes for vacuum bag compression molding, the composite membranes for vacuum bag compression molding include demoulding layer, first glue point adhesive layer, isolation layer, second glue point adhesive layer and air-permeable felt layer which are sequentially laminated;The grammage of the first glue point adhesive layer and the second glue point adhesive layer is independently 4~7g / m 2 ;In vacuum bag compression molding, the composite membranes for vacuum bag compression molding of the utility model can be laid once, save time, help to vacuum, improve the surface quality of product, have good flatness, easy demoulding.

Description

Technical Field

[0001] This utility model relates to the field of vacuum bag compression molding technology, and in particular to a composite film for vacuum bag compression molding. Background Technology

[0002] In the vacuum bag molding process, after the product is layered (hand lay-up, spraying, or prepreg), release media such as release cloth and release film, as well as air-guiding media such as breathable felt, are laid layer by layer to facilitate demolding and air guidance. Finally, sealing strips are applied, vacuum bag film is laid, and auxiliary vacuuming parts (vacuum valve, quick connector, and vacuum tube) are installed. Then, an air source is connected, the vacuum degree is checked, vacuuming is performed, the product is cured, and demolding is carried out. The resulting product has advantages such as high density and low porosity, and is widely used in the manufacture of aerospace, automotive, and sporting goods, as well as other fields that require high-strength, lightweight composite materials.

[0003] Vacuum bag molding uses a vacuum pump to extract air from the mold, creating a pressure difference between atmospheric pressure and the area beneath the bag. Atmospheric pressure ensures the composite material is continuously and uniformly pressurized during curing. The demolding and air-guiding effects in vacuum bag molding significantly impact the surface finish of the product. Currently, demolding and air-guiding are achieved by layering release cloths and breathable felts. However, this layer-by-layer process is time-consuming, and the resin's workable time is limited, potentially affecting product quality. Improper mold closing or deformation of the release cloth and other materials due to resin flow and pressure within the mold during vacuum bag molding can lead to wrinkles, resulting in poor surface smoothness and requiring extensive subsequent sanding and repair. Furthermore, the release cloth and breathable felt are prone to damage during demolding, making demolding difficult.

[0004] Therefore, there is a need to develop a composite film for vacuum bag compression molding that is easy to lay, easy to demold, and produces products with good surface quality. Utility Model Content

[0005] To solve the above-mentioned technical problems, this utility model provides a composite film for vacuum bag molding. The composite film for vacuum bag molding can be laid in one go during vacuum bag molding, saving time, improving the surface quality of the product, ensuring good flatness, and facilitating demolding.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] This invention provides a composite film for vacuum bag compression molding, comprising a release layer, a first adhesive layer, a release layer, a second adhesive layer, and a breathable felt layer stacked sequentially; the basis weight of the first adhesive layer and the second adhesive layer is independently 4-7 g / m³. 2 (e.g., 4.5g / m) 25g / m 2 5.5g / m 2 6g / m 2 Or 6.5g / m 2 wait).

[0008] In this invention, the first adhesive layer and the second adhesive layer are composed of adhesive dots, which have little impact on air permeability; the composite film for vacuum bag molding has the functions of assisting demolding, absorbing excess resin, helping to expel air and maintaining a vacuum environment when used in vacuum bag molding.

[0009] In the vacuum bag molding process, the resin has a certain working time, so it is necessary to lay the release medium and air-conducting medium as much as possible. The composite film for vacuum bag molding described in this utility model can achieve one-time laying of the release medium and air-conducting medium, which shortens the laying time and greatly reduces the laying time, leaving more time for resin processing. The composite film for vacuum bag molding can achieve one-time laying of the release medium and air-conducting medium, which can reduce environmental impact, reduce the contamination of the product by dust and impurities, and improve the surface quality of the product. Using the composite film for vacuum bag molding can avoid the problems of wrinkles caused by tension when laying multiple layers sequentially, and wrinkles caused by slight displacement of the release cloth and breathable felt during vacuum bag molding due to pressure. This reduces wrinkles on the surface of the product, increases the flatness of the product, and reduces the amount of work for further grinding and repair. The composite film for vacuum bag molding can also avoid the problems of large gaps between layers when the release medium and breathable felt are laid sequentially, which causes long vacuuming time and resin accumulation between layers, resulting in waste.

[0010] In this invention, the composite film for vacuum bag molding can be laid in one go, saving time, facilitating vacuuming, increasing flow rate, improving the surface quality of the product, ensuring good flatness, facilitating demolding, and having little impact on air permeability. It can be used to replace the demolding medium and air-conducting medium such as breathable felt in the traditional vacuum bag molding process.

[0011] In this invention, the weight of the first adhesive dot bonding layer and the second adhesive dot bonding layer refers to the weight of adhesive dots formed per square meter after the adhesive is dried and the solvent is removed.

[0012] In this invention, the basis weight of the first adhesive dot bonding layer and the second adhesive dot bonding layer are each independently 4-7 g / m³. 2It can achieve good interlayer adhesion, giving the composite film for vacuum bag compression molding good release properties during vacuum bag compression molding. If the basis weight is too high, the adhesive dots will be too dense, which will reduce the porosity of the composite film for vacuum bag compression molding and decrease air permeability. When using it for vacuum bag compression molding, the contact between the resin-permeable isolation layer and the adhesive dots will increase, making release difficult. If the basis weight is too low, the density of adhesive dot distribution will be low, the unbonded area will be large, the bonding and bonding effect will be poor, and the layers will be more susceptible to tension and wrinkles will occur. When using it for vacuum bag compression molding, the surface defects of the product will be serious, uneven, and require more grinding.

[0013] Preferably, the release layer comprises a release fabric.

[0014] Preferably, the release fabric is any one or a combination of at least two of polyester release fabric, nylon 6 release fabric, or nylon 66 release fabric.

[0015] Preferably, the thickness of the release layer is 130–160 μm, such as 133 μm, 136 μm, 139 μm, 142 μm, 145 μm, 148 μm, 151 μm, 154 μm, or 157 μm.

[0016] Preferably, the first adhesive dot bonding layer and the second adhesive dot bonding layer are prepared using an adhesive.

[0017] Preferably, the adhesive is any one or a combination of at least two of solvent-based adhesives, water-based adhesives, or hot-melt adhesives.

[0018] For example, the solvent-based adhesive includes polyurethane adhesives and / or polyvinyl acetate adhesives; the water-soluble adhesive includes ethylene-vinyl acetate copolymer adhesives and / or ethylene-acrylic acid copolymer adhesives; and the hot-melt adhesive includes polystyrene adhesives and / or polyacrylate adhesives.

[0019] Preferably, the thickness of the isolation layer is 25–75 μm, such as 30 μm, 40 μm, 50 μm, 60 μm or 70 μm.

[0020] In this invention, the thickness of the isolation layer is preferably 25-75 μm. If the thickness of the isolation layer is too thin, it is easy to break under tension, causing some resin to overflow through the isolation layer during vacuum bag molding, making it difficult to release the mold and resulting in defects and unevenness on the surface of the part.

[0021] Preferably, the isolation layer is an isolation membrane.

[0022] Preferably, the separator is any one or a combination of at least two of polyethylene film, polypropylene film, ethylene-tetrafluoroethylene copolymer film, or perfluoroethylene-propylene copolymer film.

[0023] Preferably, the separator membrane comprises a porous separator membrane or a non-porous separator membrane.

[0024] Preferably, the porosity of the porous separator is 45% to 60%, such as 47%, 49%, 51%, 53%, 55%, 57%, or 59%.

[0025] Preferably, the pore size of the perforated separator is 0.25 to 0.5 mm, such as 0.28 mm, 0.31 mm, 0.34 mm, 0.37 mm, 0.40 mm, 0.43 mm, 0.46 mm or 0.49 mm.

[0026] Preferably, the basis weight of the breathable felt layer is 135-150 g / m². 2 For example, 137g / m 2 139g / m 2 141g / m 2 143g / m 2 145g / m 2 147g / m 2 Or 149g / m 2 wait.

[0027] In this invention, the basis weight of the breathable felt layer refers to the basis weight of the breathable felt layer, and the basis weight of the breathable felt layer is preferably 135-150 g / m³. 2 If the basis weight of the breathable felt layer is too high, the bonding effect of the breathable felt layer will be poor, and wrinkles will easily appear in the release layer and the isolation layer. During vacuum bag molding, the surface defects of the product will be serious and uneven. If the basis weight of the breathable felt layer is too low, it will be difficult to extract air during vacuum bag molding. The gas generated in the prepreg layer will be difficult to extract, which will also lead to serious surface defects of the product.

[0028] Preferably, the breathable felt layer comprises a breathable felt.

[0029] Preferably, the breathable felt is a polyester breathable felt and / or a polyester plus nylon breathable felt.

[0030] For example, the grade of the polyester-nylon breathable felt is WF300N, and the manufacturer is Ningbo Ligo Composite Materials Co., Ltd.

[0031] Preferably, the thickness of the breathable felt layer is 0.65 to 0.9 mm, such as 0.68 mm, 0.71 mm, 0.74 mm, 0.77 mm, 0.80 mm, 0.83 mm, 0.86 mm or 0.89 mm.

[0032] Preferably, the thickness of the composite film used for vacuum bag compression molding is 0.8 to 1.2 mm, such as 0.85 mm, 0.90 mm, 0.95 mm, 1.00 mm, 1.05 mm, 1.10 mm or 1.15 mm.

[0033] This invention does not impose any special restrictions on the preparation method of the composite film for vacuum bag compression molding. For example, the following method can be used: a breathable felt and a perforated or non-perforated isolation film are composited with an adhesive, and then the perforated or non-perforated isolation film is coated with an adhesive on the side away from the breathable felt and then composited with a release cloth to obtain the composite film for vacuum bag compression molding.

[0034] Compared with the prior art, the present invention has at least the following beneficial effects:

[0035] The composite film for vacuum bag compression molding of this utility model comprises a release layer, a first adhesive layer, a release layer, a second adhesive layer, and a breathable felt layer stacked sequentially; the adhesive weight of the first adhesive layer and the second adhesive layer is independently 4-7 g / m³. 2 Using the aforementioned composite film for vacuum bag molding can reduce laying time, improve the surface quality of the product, enhance flatness, and facilitate demolding. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the structure of the composite film for vacuum bag compression molding provided in Example 1;

[0037] Wherein, 1-release layer; 2-first adhesive layer; 3-isolation layer; 4-second adhesive layer; 5-breathable felt layer; 6-adhesive dots. Detailed Implementation

[0038] The technical solution of this utility model will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are merely simplified examples of this utility model and do not represent or limit the scope of protection of this utility model. The scope of protection of this utility model is determined by the claims.

[0039] Example 1

[0040] This embodiment provides a composite film for vacuum bag compression molding, such as Figure 1 As shown, the composite film for vacuum bag compression molding includes a release layer 1, a first adhesive dot bonding layer 2, an isolation layer 3, a second adhesive dot bonding layer 4, and a breathable felt layer 5 stacked in sequence. The first adhesive dot bonding layer 2 and the second adhesive dot bonding layer 4 are composed of adhesive dots 6.

[0041] The release layer 1 is a polyester release fabric with a basis weight of 85 g / m². 2 The thickness is 135μm;

[0042] The basis weight of the first adhesive dot bonding layer 2 is 4 g / m². 2 The first adhesive layer is made of polyurethane adhesive (manufacturer: Guangzhou Ruilin New Materials Co., Ltd., brand name: R5090);

[0043] The isolation layer 3 is a porous polyethylene film with a thickness of 50 μm, a porosity of 45%, and a pore size of 0.3 mm.

[0044] The basis weight of the second adhesive layer 2 is 4 g / m². 2 The first adhesive layer is made of polyurethane adhesive (manufacturer: Guangzhou Ruilin New Materials Co., Ltd., brand name: R5090);

[0045] The breathable felt layer 5 is a polyester breathable felt (manufactured by Ningbo Ligo Composite Materials Co., Ltd., brand name WF135), with a thickness of 0.65mm and a basis weight of 135g / m³. 2 .

[0046] Example 2

[0047] This embodiment provides a composite film for vacuum bag compression molding. The composite film for vacuum bag compression molding includes a release layer, a first adhesive dot layer, an isolation layer, a second adhesive dot layer, and a breathable felt layer stacked in sequence. The first adhesive dot layer and the second adhesive dot layer are composed of adhesive dots.

[0048] The release layer is made of nylon 6 release fabric with a basis weight of 85 g / m². 2 The thickness is 140μm;

[0049] The basis weight of the first adhesive dot bonding layer is 5 g / m². 2 The first adhesive layer is made of ethylene-vinyl acetate copolymer adhesive (manufacturer: Nanjing Xinyi Synthetic Technology Co., Ltd., brand name: Xinyi Synthetic L7);

[0050] The isolation layer is a porous polypropylene film with a thickness of 75 μm, a porosity of 60%, and a pore size of 0.5 mm.

[0051] The basis weight of the second adhesive dot bonding layer is 5 g / m². 2 The first adhesive layer is made of ethylene-vinyl acetate copolymer adhesive (manufacturer: Nanjing Xinyi Synthetic Technology Co., Ltd., brand name: Xinyi Synthetic L7);

[0052] The breathable felt layer is made of polyester breathable felt (manufactured by Ningbo Ligo Composite Materials Co., Ltd., brand name WF150), with a thickness of 0.9 mm and a basis weight of 150 g / m². 2 .

[0053] Example 3

[0054] This embodiment provides a composite film for vacuum bag compression molding, the composite film for vacuum bag compression molding includes a release layer, a first adhesive layer, an isolation layer, a second adhesive layer, and a breathable felt layer stacked in sequence;

[0055] The release layer is nylon 66 release fabric with a basis weight of 92 g / m². 2 The thickness is 155μm;

[0056] The basis weight of the first adhesive dot bonding layer is 7 g / m². 2 The first adhesive layer is made of polyacrylate adhesive (manufacturer: Nanjing Tiehebao New Material Co., Ltd., brand name: THB600);

[0057] The isolation layer is a porous ethylene-tetrafluoroethylene copolymer film with a thickness of 25 μm, a porosity of 50%, and a pore size of 0.45 mm.

[0058] The basis weight of the first adhesive dot bonding layer is 5 g / m². 2 The first adhesive layer is made of polyacrylate adhesive (manufacturer: Nanjing Tiehebao New Material Co., Ltd., brand name: THB600);

[0059] The breathable felt layer is made of polyester breathable felt (manufactured by Ningbo Ligo Composite Materials Co., Ltd., brand name WF135), with a thickness of 0.65 mm and a basis weight of 135 g / m². 2 .

[0060] Example 4

[0061] This embodiment provides a composite film for vacuum bag compression molding, which differs from Embodiment 1 in that the isolation layer is a non-porous polyethylene film with a thickness of 50 μm, while other conditions are the same as in Embodiment 1.

[0062] Example 5

[0063] This embodiment provides a composite film for vacuum bag compression molding, which differs from Embodiment 1 in that the basis weight of the polyester breathable felt is 300 g / m³. 2 (Manufacturer: Ningbo Ligo Composite Materials Co., Ltd., Grade: WF300), other conditions are the same as in Example 1.

[0064] Comparative Example 1

[0065] This comparative example provides a composite film for vacuum bag compression molding, which differs from Example 1 in that the basis weight of the first adhesive layer is adjusted to 3 g / m³. 2 The weight of the second adhesive layer was adjusted to 3 g / m². 2 Other conditions are the same as in Example 1.

[0066] Comparative Example 2

[0067] This comparative example provides a composite film for vacuum bag compression molding, which differs from Example 1 in that the basis weight of the first adhesive layer is adjusted to 8 g / m³. 2 The weight of the second adhesive layer was adjusted to 8 g / m². 2 Other conditions are the same as in Example 1.

[0068] Comparative Example 3

[0069] This comparative example provides a three-layer film for vacuum bag compression molding, which is composed of polyester release fabric, perforated polyethylene film and polyester breathable felt, and does not include the first adhesive dot layer and the second adhesive dot layer.

[0070] The polyester release fabric has a basis weight of 85 g / m². 2 The thickness is 135μm;

[0071] The porous polyethylene film has a thickness of 50 μm, a porosity of 45%, and a pore size of 0.3 mm.

[0072] The polyester breathable felt (manufactured by Ningbo Ligo Composite Materials Co., Ltd., grade WF135) has a thickness of 0.65 mm and a basis weight of 135 g / m². 2 .

[0073] Application Example 1

[0074] This application example provides a vacuum bag compression molding process, which includes the following steps: applying a release agent to the mold, laying 6 layers of 0.5m × 0.5m prepreg, laying a 0.6m × 0.6m composite film for vacuum bag compression molding provided in Example 1 on top of the prepreg, wherein the release layer side of the composite film for vacuum bag compression molding is in contact with the prepreg, applying a sealing strip, then laying the vacuum bag film and auxiliary vacuuming parts, drawing a vacuum, heating at 120°C for 2 hours for curing, demolding, and completing the vacuum bag compression molding process.

[0075] The manufacturer of the aforementioned prepreg is Solvay, and the grade is MTM28-1-33%-12KT700SC-125-600.

[0076] Application Examples 2-5

[0077] Application Examples 2-5 provide a vacuum bag compression molding process, which differs from Application Example 1 in that the composite film for vacuum bag compression molding provided in Example 1 is replaced with the composite film for vacuum bag compression molding provided in Examples 2-5, while other conditions are the same as in Application Example 1.

[0078] Comparative application examples 1-2

[0079] Comparative Application Examples 1 and 2 provide a vacuum bag compression molding process, which differs from Application Example 1 in that the composite film for vacuum bag compression molding provided in Example 1 is replaced with the composite film for vacuum bag compression molding provided in Comparative Examples 1 and 2, while other conditions are the same as in Application Example 1.

[0080] Comparative Application Example 3

[0081] Comparative Application Example 3 provides a vacuum bag compression molding process, which differs from Application Example 1 in that the 0.6m × 0.6m composite film for vacuum bag compression molding provided in Example 1, which is laid on top of the prepreg, is replaced with a three-layer film for vacuum bag compression molding provided in Comparative Example 3, which is laid on top of the prepreg. Specifically, a 0.6m × 0.6m polyester release cloth, a 0.6m × 0.6m perforated polyethylene film, and a 0.6m × 0.6m polyester breathable felt are laid on top of the prepreg in sequence, and other conditions are the same as in Application Example 1.

[0082] Performance testing

[0083] (1) Air permeability: The air permeability of the vacuum bag compression molding composite films provided in Examples 1-3, 5 and Comparative Examples 1-2 was tested using an air permeability tester (manufacturer: Zhejiang Sangong Instrument Co., Ltd., model: YG461E); the test pressure was 100 Pa and the sample area was 20 cm². 2 ;

[0084] (2) Release properties and product surface defects: Observe whether the vacuum bag compression molding process provided in Application Examples 1 to 5 and Comparative Application Examples 1 to 3 is easy to demold, and observe the surface condition of the product to see if it is flat and whether there are serious defects.

[0085] The test results are shown in Tables 1 and 2.

[0086] Table 1

[0087] Air permeability (mm / s) Example 1 16.48 Example 2 22.23 Example 3 18.52 Example 5 17.07 Comparative Example 1 17.13 Comparative Example 2 13.61

[0088] Table 2

[0089] Release Surface defects of products Application Example 1 Easy to demold The surface is in good condition and relatively flat. Application Example 2 Easy to demold The surface is in good condition and relatively flat. Application Example 3 Easy to demold The surface is in good condition and relatively flat. Application Example 4 Easy to demold The surface is in good condition and relatively flat. Application Example 5 Easy to demold Uneven surface, severe defects Comparative Application Example 1 Difficult to demold Uneven surface, severe defects Comparative Application Example 2 Difficult to demold The surface is in good condition and relatively flat. Comparative Application Example 3 Difficult to demold Uneven surface, severe defects

[0090] The test results in Tables 1 and 2 show that the air permeability of the composite films for vacuum bag molding provided in Examples 1 to 3 is 16.48 mm / s to 22.23 mm / s, with good release properties, good surface condition of the products, relatively smooth surface, and few areas requiring grinding and repair.

[0091] Compared with Example 1, if the release layer is a non-porous release film (Example 4), the release properties are good, the surface condition of the product is good, and the excess adhesive at the edge of the product is slightly more than in Example 1, but it does not affect the product.

[0092] Compared with Example 1, if the weight of the breathable felt layer is too large (Example 5), although the release property is good, the bonding effect of the breathable felt after gluing is poor, the release cloth and the release film are prone to wrinkling, and the surface defects of the product prepared by vacuum bag molding are serious and uneven.

[0093] Compared with Example 1, if the basis weight of the first adhesive layer and the second adhesive layer is too low (Comparative Example 1), the adhesive dot distribution density on the composite film for vacuum bag molding is low, some areas are not well bonded, and the release cloth and release film are more susceptible to wrinkles due to tension. When vacuum bag molding is performed using it (Comparative Application Example 1), the surface defects of the product are serious, uneven, and more areas need to be polished.

[0094] Compared with Example 1, if the weight of the first adhesive layer and the second adhesive layer is too high (Comparative Example 2), the air permeability of the composite film for vacuum bag molding will be affected. When vacuum bag molding is performed using it (Comparative Application Example 2), the surface condition of the product is still acceptable, but the resin-permeable isolation layer has more contact with the adhesive dots, making release more difficult.

[0095] Compared to Application Example 1, if the composite film for vacuum bag molding is not used, and instead polyester release fabric, perforated polyethylene film, and polyester breathable felt are laid out sequentially (compared to Application Example 3), demolding is difficult and the surface defects of the product are severe. The sequential laying of polyester release fabric, perforated polyethylene film, and polyester breathable felt results in more wrinkles in the release fabric due to tension during laying and pressure during vacuum bag molding. Resin tends to accumulate at these wrinkles, forming wrinkle marks.

[0096] The applicant declares that the above description is only a specific embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present utility model fall within the protection and disclosure scope of the present utility model.

Claims

1. A composite film for vacuum bag compression molding, characterized in that, The composite film for vacuum bag compression molding includes a release layer, a first adhesive layer, an isolation layer, a second adhesive layer, and a breathable felt layer stacked in sequence. The first and second glue spot bonding layers each independently have a grammage of 4 to 7 g / m 2 .

2. The composite film for vacuum bag compression molding according to claim 1, characterized in that, The release layer includes a release fabric; The release fabric is any one or a combination of at least two of polyester release fabric, nylon 6 release fabric, or nylon 66 release fabric.

3. The composite film for vacuum bag compression molding according to claim 1, characterized in that, The thickness of the release layer is 130–160 μm.

4. The composite film for vacuum bag compression molding according to claim 1, characterized in that, The thickness of the isolation layer is 25–75 μm.

5. The composite film for vacuum bag compression molding according to claim 1, characterized in that, The isolation layer is an isolation membrane; The separator is any one or a combination of at least two of the following: polyethylene film, polypropylene film, ethylene-tetrafluoroethylene copolymer film, or perfluoroethylene-propylene copolymer film.

6. The composite film for vacuum bag compression molding according to claim 5, characterized in that, The isolation membrane may be a porous isolation membrane or a non-porous isolation membrane.

7. The composite film for vacuum bag compression molding according to claim 6, characterized in that, The porosity of the porous isolation membrane is 45% to 60%; The pore size of the perforated separator is 0.25–0.5 mm.

8. The composite film for vacuum bag compression molding according to claim 1, characterized in that, The air-permeable felt layer has a grammage of 135 to 150 g / m 2 ; The breathable felt layer includes a breathable felt.

9. The composite film for vacuum bag compression molding according to claim 1, characterized in that, The thickness of the breathable felt layer is 0.65–0.9 mm.

10. The composite film for vacuum bag compression molding according to claim 1, characterized in that, The thickness of the composite film used for vacuum bag compression molding is 0.8–1.2 mm.

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