Composite breathable felt for autoclave molding process and preparation method of composite breathable felt

Abstract

The invention provides a composite breathable felt for an autoclave forming process and a preparation method of the composite breathable felt. The composite breathable felt comprises a non-woven fabric and an ePTFE film arranged on the surface of one side of the non-woven fabric. The non-woven fabric is adopted as the base fabric, and the ePTFE film is arranged on the surface of one side of the non-woven fabric, so that the obtained composite breathable felt has the characteristics of breathability and glue resistance, also has efficient release property and good mechanical strength, is used in an autoclave forming process of a composite material, has better breathability and isolation effect compared with a conventional isolation film, and is suitable for being used in the autoclave forming process of the composite material. And in the vacuum curing stage of the composite material, residual air in a prepreg laying layer and volatile gas generated under the high-temperature condition can be effectively exhausted, and then the forming effect of the composite material can be effectively improved.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer molding technology, and particularly relates to a composite breathable felt in an autoclave molding process and a preparation method thereof. Background Art

[0002] Composite materials have the advantages of high quality and strength compared with metal materials, and have been widely used in various fields. At present, the most widely used composite material molding includes metal molding and autoclave molding technology.

[0003] Among them, the advantage of the metal molding process is that the surface contour of the product after molding is good, but the molds required for both the inner and outer surfaces are relatively complex. It is difficult to pressurize the molds on both sides during the production process, which makes the process complicated and the production cycle long. In addition, the products after molding are prone to defects such as stratification and looseness. The autoclave molding process has simple process parts, simple molds, short production cycles, high yields, and is more suitable for medium and small components. This is because the composite parts are not directly in contact with the fluid medium in the autoclave during the molding process, and the effect of the external temperature field on the parts is mainly transmitted through the mold.

[0004] In the autoclave molding process, the method to ensure the molding quality of the non-mold-attached surface is mainly solved by uniform packaging, supplementary machining, traditional soft molds, etc.; among them, uniform packaging is to directly carry out the packaging of isolation film, breathable felt, and vacuum bag after the prepreg layer is completed in the mold; however, the conventional isolation film used has certain disadvantages. The porous isolation film has good air permeability, but it cannot block the resin and will cause resin overflow. The non-porous isolation film has a good isolation effect, but it does not have a breathable function. During the vacuum curing stage of the composite material, it is difficult to effectively discharge the air remaining in the prepreg layer and the volatile gas generated under high temperature conditions, which affects the molding effect of the composite material.

[0005] Therefore, in view of the above problems, it is of great significance to develop a composite breathable felt which has air permeability and glue-blocking effects, and also has certain mechanical strength and high-efficiency release properties. Summary of the invention

[0006] In view of the deficiencies in the prior art, the object of the present invention is to provide a composite breathable felt for use in an autoclave molding process and a preparation method thereof. The breathable composite felt has the characteristics of air permeability and adhesive resistance, and has efficient release properties and good mechanical strength. It is used in the autoclave molding process of composite materials. During the vacuum curing stage of the composite materials, it can effectively discharge the air remaining in the prepreg ply and the volatile gases generated under high temperature conditions, thereby improving the molding effect of the composite materials.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a composite breathable felt for use in an autoclave molding process, wherein the composite breathable felt comprises a non-woven fabric and an ePTFE film disposed on one surface of the non-woven fabric.

[0009] The composite breathable felt for autoclave molding process provided by the present invention comprises a non-woven fabric and an ePTFE film arranged on one side surface of the non-woven fabric. By adopting the non-woven fabric as the base fabric and arranging the ePTFE film on one side surface thereof, the obtained composite breathable felt has the characteristics of air permeability and adhesive resistance, and also has efficient release property and high mechanical strength. When used in the autoclave molding process of composite materials, it has better mechanical strength, air permeability and isolation effect than conventional isolation films. During the vacuum curing stage of the composite materials, it can effectively discharge the air remaining in the prepreg ply and the volatile gas generated under high temperature conditions, thereby improving the molding effect of the composite materials.

[0010] Preferably, the nonwoven fabric includes any one of needle-punched nonwoven fabric, spunlace nonwoven fabric or melt-blown nonwoven fabric, and is more preferably spunlace nonwoven fabric.

[0011] Preferably, the material of the non-woven fabric includes polyamide or polyester, and more preferably polyester.

[0012] Preferably, the nonwoven fabric has a gram weight of 80 to 150 g / m 2 , for example 80g / m 2 , 90g / m 2 , 100g / m 2 , 110g / m 2 , 120g / m 2 , 130g / m 2 , 140g / m 2 or 150g / m 2 , and specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range, and further preferably 100 to 130 g / m 2 .

[0013] Preferably, the thickness of the nonwoven fabric is 0.3-0.6 mm, for example, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm or 0.6 mm, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0014] Preferably, the linear density of the fibers in the nonwoven fabric is 3 to 8D, for example, 3D, 4D, 5D, 6D, 7D or 8D, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range, and 3 to 6D is further preferred.

[0015] Preferably, the thickness of the ePTFE film is 0.05-0.1 mm, for example, 0.05 mm, 0.055 mm, 0.06 mm, 0.065 mm, 0.07 mm, 0.075 mm, 0.08 mm, 0.085 mm, 0.09 mm, 0.095 mm or 0.1 mm, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0016] Preferably, the average pore size of the ePTFE film is 0.1 to 10 μm, for example, 0.1 μm, 0.2 μm, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range, and 1 to 5 μm is further preferred.

[0017] Preferably, the porosity of the ePTFE film is 40-80%, for example 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75% or 80%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the said range, and it is further preferably 50-70%.

[0018] Preferably, the ePTFE film is obtained by sequentially subjecting the ePTFE resin to extrusion molding, calendaring, biaxial stretching, heat setting and cooling.

[0019] Preferably, the number of calendering passes is 3 to 5, for example, 3, 4 or 5 passes, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0020] Preferably, the biaxial stretching rate is 100 to 1200% / s, for example, 100% / s, 200% / s, 400% / s, 600% / s, 800% / s, 1000% / s or 1200% / s, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range, and it is further preferably 600 to 800% / s.

[0021] Preferably, the temperature of the biaxial stretching is 200-280°C, for example, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C or 280°C, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range, and it is further preferably 240-260°C.

[0022] Preferably, the thickness of the composite breathable felt is 0.4-0.7 mm, for example, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm or 0.7 mm, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0023] In a second aspect, the present invention provides a method for preparing the composite breathable felt as described in the first aspect, the preparation method comprising: compounding a non-woven fabric and an ePTFE film to obtain the composite breathable felt.

[0024] Preferably, the compounding method includes hot rolling compounding or glue coating compounding.

[0025] In a third aspect, the present invention provides an autoclave molding process for a composite material, the autoclave molding process comprising: laminating a release cloth, a prepreg, the composite breathable felt as described in the first aspect, and a vacuum bag in that order, sealing them with a sealing tape, and curing and molding them in an autoclave to obtain the composite material.

[0026] Wherein, the non-woven fabric in the composite breathable felt is close to one side of the vacuum bag.

[0027] Preferably, the prepreg comprises carbon fiber reinforced prepreg and / or glass fiber reinforced prepreg.

[0028] Preferably, the curing temperature is 180-230°C, for example, 180°C, 185°C, 190°C, 195°C, 200°C, 205°C, 210°C, 215°C, 220°C, 225°C or 230°C, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0029] Preferably, the curing molding pressure is 0.9-1 MPa, for example, 0.9 MPa, 0.92 MPa, 0.94 MPa, 0.96 MPa, 0.98 MPa or 1 MPa, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The composite breathable felt for autoclave molding process provided by the present invention comprises a non-woven fabric and an ePTFE film arranged on one side surface of the non-woven fabric; by adopting the non-woven fabric as the base fabric and arranging the ePTFE film on one side surface thereof, the obtained composite breathable felt has the characteristics of air permeability and adhesive resistance, and also has efficient release property and high mechanical strength. When used in the autoclave molding process of composite materials, it has better mechanical strength, air permeability and isolation effect than conventional isolation films. During the vacuum curing stage of the composite materials, it can effectively discharge the air remaining in the prepreg ply and the volatile gas generated under high temperature conditions, thereby improving the molding effect of the composite materials. DETAILED DESCRIPTION

[0032] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating directions or positional relationships, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention; the terms "first", "second", and "third" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance, unless otherwise clearly specified and limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] The technical solution provided by the present invention will be clearly and completely described below in conjunction with embodiments. Obviously, the specific implementation methods described are only part of the implementation methods of the present invention, rather than all the implementation methods.

[0034] Unless otherwise specified, the raw materials involved in the following specific embodiments are all conventional materials in the art and can be purchased commercially;

[0035] In particular, some of the raw material information involved is as follows:

[0036] (1) ePTFE resin: purchased from DAIKIN, brand F-106.

[0037] Preparation Example 1

[0038] An ePTFE film with a thickness of 0.1 mm, an average pore size of 4.5 μm, and a porosity of 60%;

[0039] The preparation method of the ePTFE film includes: extruding the ePTFE resin, performing four calendering steps, biaxially stretching at a stretching rate of 800% / s and a temperature of 250°C, and finally heat setting at 180°C and cooling to room temperature to obtain the ePTFE film.

[0040] Preparation Example 2

[0041] An ePTFE film with a thickness of 0.09 mm, an average pore size of 1 μm, and a porosity of 50%;

[0042] The preparation method of the ePTFE film includes: extruding the ePTFE resin, calendering it in four steps, biaxially stretching it at a stretching rate of 600% / s and a temperature of 240°C, and finally heat-setting it at 200°C and cooling it to room temperature to obtain the ePTFE film.

[0043] Preparation Example 3

[0044] An ePTFE film with a thickness of 0.08 mm, an average pore size of 2.5 μm, and a porosity of 70%;

[0045] The preparation method of the ePTFE film includes: extruding the ePTFE resin, calendering it in four steps, biaxially stretching it at a stretching rate of 800% / s and a temperature of 260°C, and finally heat-setting it at 210°C and cooling it to room temperature to obtain the ePTFE film.

[0046] Preparation Example 4

[0047] An ePTFE film, which differs from Preparation Example 1 in that the porosity is 40%, and other parameters and preparation methods are the same as those of Preparation Example 1.

[0048] Preparation Example 5

[0049] An ePTFE film, which differs from Preparation Example 1 in that the porosity is 80%, and other parameters and preparation methods are the same as those of Preparation Example 1.

[0050] Example 1

[0051] A composite breathable felt for an autoclave molding process, having an overall thickness of 0.5 mm, specifically comprising a polyester spunlace nonwoven fabric and an ePTFE film disposed on one side of the polyester spunlace nonwoven fabric;

[0052] Among them, the weight of polyester spunlace nonwoven fabric is 120g / m 2 , thickness is 0.4mm, and the linear density of the polyester fiber contained is 5D;

[0053] The ePTFE film is from Preparation Example 1;

[0054] The method for preparing the composite breathable felt used in the autoclave molding process comprises: hot-rolling and compounding the polyester spunlace nonwoven fabric and the ePTFE film to obtain the composite breathable felt.

[0055] Example 2

[0056] A composite breathable felt for an autoclave molding process, having an overall thickness of 0.52 mm, specifically comprising a polyester spunlace nonwoven fabric and an ePTFE film disposed on one side of the polyester spunlace nonwoven fabric;

[0057] Among them, the weight of polyester spunlace nonwoven fabric is 130g / m 2 , thickness is 0.43mm, and the linear density of the polyester fiber contained is 5D;

[0058] The ePTFE film is from Preparation Example 2;

[0059] The method for preparing the composite breathable felt used in the autoclave molding process comprises: compounding a polyester spunlace nonwoven fabric and an ePTFE film to obtain the composite breathable felt.

[0060] Example 3

[0061] A composite breathable felt for an autoclave molding process, having an overall thickness of 0.46 mm, specifically comprising a polyester spunlace nonwoven fabric and an ePTFE film disposed on one side of the polyester spunlace nonwoven fabric;

[0062] Among them, the weight of polyester spunlace nonwoven fabric is 110g / m 2 , thickness is 0.38mm, and the linear density of the polyester fiber contained is 5D;

[0063] The ePTFE film is from Preparation Example 3;

[0064] The method for preparing the composite breathable felt used in the autoclave molding process comprises: compounding a polyester spunlace nonwoven fabric and an ePTFE film to obtain the composite breathable felt.

[0065] Example 4

[0066] A composite breathable felt for use in an autoclave molding process, which differs from Example 1 in that the ePTFE film provided in Preparation Example 4 is used to replace the ePTFE film provided in Preparation Example 1, and other structures, parameters and preparation methods are the same as those in Example 1.

[0067] Example 5

[0068] A composite breathable felt for use in an autoclave molding process, which differs from Example 1 in that the ePTFE film provided in Preparation Example 5 is used to replace the ePTFE film provided in Preparation Example 1, and other structures, parameters and preparation methods are the same as those in Example 1.

[0069] Example 6

[0070] A composite breathable felt for autoclave molding process, which is different from Example 1 in that a composite breathable felt with a gram weight of 120 g / m 2 The polyester spunlace nonwoven fabric is replaced by a polyamide spunlace nonwoven fabric having a thickness of 0.35 mm and a fiber linear density of 5D. The other structures, parameters and preparation methods are the same as those in Example 1.

[0071] Example 7

[0072] A composite breathable felt for autoclave molding process, which is different from Example 1 in that a composite breathable felt with a gram weight of 120 g / m 2 The polyester needle-punched nonwoven fabric with a thickness of 0.5 mm and a fiber linear density of 5D replaces the polyester spunlace nonwoven fabric. Other structures, parameters and preparation methods are the same as those in Example 1.

[0073] Performance Test:

[0074] (1) Air permeability: Tested according to the test method provided in GB / T 5453@127pa.

[0075] (2) Mechanical strength: Tested in accordance with the test method provided in GB / T 24218.3.

[0076] (3) Adhesive resistance and release properties: Lay the layers in the order of release cloth, carbon fiber reinforced epoxy resin prepreg, composite breathable felt and vacuum bag, seal them with sealing tape, and place them in an autoclave for curing at 200°C and 1MPa. Observe whether the composite breathable felt is infiltrated with resin, whether there is co-curing, and whether it can be easily peeled off.

[0077] The composite air-permeable felts provided in Examples 1 to 7 were tested according to the above test method. The test results are shown in Table 1:

[0078] Table 1

[0079]

[0080] From the data in Table 1, we can see that:

[0081] The composite breathable felts provided in Examples 1 to 3 have both excellent air permeability and high mechanical strength, and will not experience glue seepage when used in the autoclave molding process. They can also be easily peeled off, indicating that they also have excellent glue resistance and release properties.

[0082] Compared with Example 1, the composite breathable felt provided in Example 4 has a lower porosity of the ePTFE film contained therein, thereby slightly reducing its air permeability; the composite breathable felt provided in Example 5 has a higher porosity of the ePTFE film contained therein, resulting in less point-like glue infiltration during the autoclave molding process, and its strippability and glue resistance are slightly reduced.

[0083] Compared with Example 1, the composite breathable felt provided in Example 6 uses polyamide spunlace non-woven fabric, and the overall mechanical strength is reduced.

[0084] Compared with Example 1, the composite breathable felt provided in Example 7 uses needle-punched non-woven fabric instead of spunlace non-woven fabric, which leads to a decrease in mechanical strength. At the same time, it causes more point-like glue infiltration during the autoclave molding process, and the strippability and glue resistance become worse.

[0085] The applicant declares that the present invention illustrates a composite breathable felt for autoclave molding process and its preparation method through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A composite breathable felt for autoclave molding process, characterized in that: The composite breathable felt comprises a non-woven fabric and an ePTFE film arranged on one surface of the non-woven fabric.

2. The composite breathable felt for autoclave molding process according to claim 1, characterized in that: The nonwoven fabric includes any one of a needle-punched nonwoven fabric, a spunlace nonwoven fabric or a melt-blown nonwoven fabric, preferably a spunlace nonwoven fabric; Preferably, the material of the non-woven fabric includes polyamide or polyester, and more preferably polyester.

3. The composite air-permeable felt for autoclave molding process according to claim 1 or 2, characterized in that: The nonwoven fabric has a gram weight of 80 to 150 g / m 2 , preferably 100 to 130 g / m 2 ; Preferably, the nonwoven fabric has a thickness of 0.3-0.6 mm.

4. The composite breathable felt for autoclave molding process according to any one of claims 1 to 3, characterized in that: The linear density of the fibers in the nonwoven fabric is 3-8D, more preferably 3-6D.

5. The composite air-permeable felt for autoclave molding process according to any one of claims 1 to 4, characterized in that: The thickness of the ePTFE film is 0.05 to 0.15 mm; Preferably, the average pore size of the ePTFE film is 0.1 to 10 μm, more preferably 1 to 5 μm, and even more preferably 2 to 5 μm; Preferably, the porosity of the ePTFE film is 40 to 80%, more preferably 50 to 70%.

6. The composite air-permeable felt for autoclave molding process according to any one of claims 1 to 5, characterized in that: The ePTFE film is obtained by sequentially subjecting the ePTFE resin to extrusion molding, calendaring, biaxial stretching, heat setting and cooling; Preferably, the number of calendering passes is 3 to 5; Preferably, the biaxial stretching rate is 100 to 1200% / s, more preferably 600 to 800% / s; Preferably, the temperature of the biaxial stretching is 200 to 280°C, more preferably 240 to 260°C.

7. The composite air-permeable felt for autoclave molding process according to any one of claims 1 to 6, characterized in that: The thickness of the composite air-permeable felt is 0.4-0.7 mm.

8. A method for preparing a composite breathable felt for autoclave molding process as claimed in any one of claims 1 to 7, characterized in that: The preparation method comprises: compounding a non-woven fabric and an ePTFE film to obtain the composite breathable felt used in the autoclave molding process; Preferably, the compounding method includes hot rolling compounding or glue coating compounding.

9. A composite material autoclave forming process, characterized in that: The autoclave molding process comprises: laminating the release cloth, the prepreg, the composite breathable felt according to any one of claims 1 to 7 and the vacuum bag in this order, sealing them with a sealing tape, and curing and molding them in an autoclave to obtain the composite material.

10. The autoclave forming process according to claim 9, characterized in that: The prepreg comprises carbon fiber reinforced prepreg and / or glass fiber reinforced prepreg; Preferably, the curing temperature is 180-230°C; Preferably, the curing molding pressure is 0.9-1 MPa.

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