Surface-coated prepreg and application thereof in preparation of composite cellular board

Abstract

The invention provides a prepreg coated with a film on the surface and application of the prepreg in preparation of a composite cellular board, and relates to the technical field of composite material preparation processes. The preparation method of the prepreg with the surface coated with the film comprises the steps that a fabric is soaked in a resin dispersion liquid for soaking, then the fabric is pressed, dried and cooled in sequence, a biaxially oriented polypropylene film is arranged on one face of the fabric, a polyethylene film is arranged on the other face of the fabric, rolling is conducted, and the prepreg with the surface coated with the film is obtained. When the prepreg and a honeycomb core are compounded to prepare the honeycomb plate, the OPP films on the upper surface and the lower surface are reserved, hot pressing combination can be directly carried out under the condition that a release agent is not used, the problem that pollution is easily caused by the release agent is solved, and after the OPP films on the surface of the composite honeycomb plate are torn off after hot pressing, the surface of a product is smooth and does not need to be further polished.

Description

Technical Field

[0001] The present invention relates to the technical field of composite material preparation technology, in particular to a surface-coated prepreg and application thereof in preparing composite honeycomb panels. Background Art

[0002] Currently, the steps used to form and cure composite honeycomb panels are as follows: 1) Prepreg cutting: Cut the prepreg into different sizes according to product requirements; 2) Film peeling and laying: Remove the film from the side of the cut prepreg that will be attached to the honeycomb core and apply it to the honeycomb core; 3) Spraying a release agent: Clean the upper and lower surfaces of the press and spray the release agent. The release agent is generally a silicone-based material; 4) Film peeling and curing: Remove the film from the upper and lower prepreg surfaces of the honeycomb panel and place it on the hot plate inside the press for curing; 5) Surface polishing: Because the release agent was sprayed before curing, some of the release agent will remain on the surface of the honeycomb panel after curing, so it needs to be polished. This production process is not only inefficient but also harmful to the environment and the health of production workers. This is because before the honeycomb panels are cured, a certain amount of release agent needs to be sprayed on the upper and lower hot plates of the press. During the spraying process, the release agent inevitably spills onto the press, the floor, and the operating table, resulting in a dirty and messy production environment. The release agent is also harmful to the workers' skin. The subsequent surface polishing process also prolongs the processing time and reduces production efficiency. Therefore, how to disclose a method for producing composite honeycomb panels with high production efficiency and without the use of release agents is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0003] The purpose of the present invention is to provide a surface-coated prepreg and its application in the preparation of composite honeycomb panels, so as to solve the problem that a release agent needs to be sprayed on the press surface during the preparation of existing composite honeycomb panels, which easily causes environmental pollution.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions: The present invention provides a surface-coated prepreg, and the preparation method of the surface-coated prepreg is as follows: The fabric is immersed in a resin dispersion for impregnation, and then the fabric is pressed, dried, and cooled in sequence. A biaxially oriented polypropylene film is placed on one side of the fabric, and a polyethylene film is placed on the other side for winding to obtain a surface-coated prepreg.

[0005] Preferably, the fabric is glass fiber fabric or carbon fiber fabric; The resin dispersion is an acetone dispersion of epoxy resin with a solid content of 76% to 80%; The pressing interval is 0.45~0.55mm; The drying temperature is 90-125°C; the cooling temperature is 5-10°C.

[0006] The present invention also provides an application of the surface-coated prepreg in preparing a composite honeycomb panel, wherein the application method comprises the following steps: The polyethylene film of the prepreg with the surface coating is removed, and the exposed side of the obtained prepreg is attached to the surface of the honeycomb core and hot-pressed and cured. After the hot-pressing and curing is completed, the biaxially oriented polypropylene film is removed to obtain a composite honeycomb panel product.

[0007] Preferably, the temperature of the hot pressing curing is 130-150° C., the pressure is 0.3 MPa, and the time is 15-35 min.

[0008] Preferably, when preparing a composite honeycomb panel, if multiple layers of prepreg need to be attached to the upper and lower surfaces of the honeycomb core, the biaxially oriented polypropylene film and polyethylene film on the surface of each inner prepreg layer need to be removed.

[0009] The present invention has at least the following beneficial effects: When using the surface-coated prepreg described in this application to prepare a composite honeycomb panel, since the upper and lower surfaces in contact with the hot press are attached with OPP film (biaxially oriented polypropylene film), there is no need to spray a release agent during the hot pressing curing process, and there is no need to polish the product surface after curing. This improves the working environment of the hot pressing curing step, reduces the harm of chemicals to the human body, and improves production efficiency and product quality.

[0010] OPP film has high-temperature adhesion, maintaining its bonding strength during hot pressing (e.g., high-temperature, high-pressure environments) and leaving no residue when peeled off after cooling. However, other films (such as PE and PET) cannot maintain bonding strength when heated, have poor form-fitting properties, and tend to cling to the surface of the part after cooling. In existing mass production, due to the relatively large size of the parts, films generally shrink easily when heated. If the OPP film is applied directly to the press surface, it will deform and the part will not be cured by hot pressing. In this invention, the OPP film is directly applied to the prepreg surface. When the part enters the press along with the part, the film adhered to the prepreg surface is less likely to deform, allowing for direct hot pressing. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Schematic diagram of the prepreg production process; Figure 2 Schematic diagram of prepreg with surface coating; Figure 3 Schematic diagram of the structure of the composite honeycomb panel prepared in Example 1 before hot pressing; Figure 4 Schematic diagram of the structure of the composite honeycomb panels prepared in Example 2, Example 3 and Example 4 before hot pressing; Figure 5 This is an optical photograph of the composite honeycomb panel prepared in Example 1; Figure 6 This is an optical photograph of the composite honeycomb panel prepared in Example 2; Figure 7 This is an optical photograph of the composite honeycomb panel prepared in Example 3; Figure 8 This is an optical photograph of the composite honeycomb panel prepared in Example 4. DETAILED DESCRIPTION

[0012] The present invention provides a surface-coated prepreg, and the preparation method of the surface-coated prepreg is as follows: The fabric is immersed in a resin dispersion for impregnation, and then the fabric is pressed, dried, and cooled in sequence. A biaxially oriented polypropylene film is placed on one side of the fabric, and a polyethylene film is placed on the other side for winding to obtain a surface-coated prepreg.

[0013] In the present invention, the fabric is glass fiber fabric or carbon fiber fabric; In the present invention, the resin dispersion is an acetone dispersion of epoxy resin, and the solid content is 76% to 80%, preferably 77% to 79%, and more preferably 78%.

[0014] In the present invention, the pressing interval is 0.45-0.55 mm, preferably 0.47-0.53 mm, and more preferably 0.5 mm, and the pressing method is to press the fabric through a roller.

[0015] In the present invention, the drying temperature is 90~125℃, and the drying is carried out in an oven. Four zones are preferably set in the oven, and the temperature of each zone is preferably set as follows: the temperature of oven zone 1 is 100~110℃, the temperature of oven zone 2 is 115~125℃, the temperature of oven zone 3 is 95~105℃, and the temperature of oven zone 4 is 90~100℃; more preferably, the temperature of zone 1 is 102~108℃, the temperature of zone 2 is 117~122℃, the temperature of zone 3 is 97~102℃, and the temperature of zone 4 is 92~97℃; more preferably, the temperature of zone 1 is 105℃, the temperature of zone 2 is 120℃, the temperature of zone 3 is 100℃, and the temperature of zone 4 is 95℃.

[0016] In the present invention, the speed at which the fabric passes through the oven is 3 to 5 m / min, preferably 3.5 to 4.5 m / min, more preferably 3.8 to 4.2 m / min, and even more preferably 4 m / min.

[0017] In the present invention, the cooling temperature is 5-10° C., preferably 6-8° C., and more preferably 7° C., and the cooling method is to cool the fabric preferably by passing it through a cooling roller.

[0018] The present invention also provides an application of the surface-coated prepreg in preparing a composite honeycomb panel, wherein the application method comprises the following steps: The polyethylene film of the prepreg with the surface coating is removed, and the exposed side of the obtained prepreg is attached to the surface of the honeycomb core and hot-pressed and cured. After the hot-pressing and curing is completed, the biaxially oriented polypropylene film is removed to obtain a composite honeycomb panel product.

[0019] In the present invention, the temperature of the hot pressing curing is 130~150℃, preferably 140℃, and more preferably 150℃; the pressure is 0.3Mpa; the time is 15~35min, which can be 15min, 20min, 25min, 30min or 35min, among which the best effect is achieved when the hot pressing curing time is 15min.

[0020] In the present invention, when preparing the composite honeycomb panel, if multiple layers of prepreg need to be attached to the upper or lower surface of the honeycomb core, the biaxially oriented polypropylene film and polyethylene film on the surface of each inner prepreg layer need to be removed.

[0021] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0022] Example 1 (1) Use Figure 1 The production process shown in the figure is to prepare the surface coated prepreg, and eight three-fly satin fiberglass fabrics (weight 300g / m 2 The fabric is drawn from the unwinding roller and passed through a guide roller into a resin tank filled with a 78% solid content epoxy resin acetone dispersion (BAC 811 epoxy resin produced by Lily Aerospace Composite Materials Co., Ltd.). A circulating pump is used to control the liquid level in the resin tank to maintain a depth of 23 cm. The impregnated fabric enters the nip roller to remove excess epoxy resin acetone dispersion from the surface, maintaining a liquid volume of 315 g / m 2 The fabric then enters the oven at a speed of 4 m / min with a temperature of 105°C in zone 1, 120°C in zone 2, 100°C in zone 3, and 95°C in zone 4. It leaves the oven after 3 minutes. The prepreg after leaving the oven passes through a cooling roller (7°C) and is then rolled using OPP film (biaxially oriented polypropylene film, model WL-50, thickness 50 μm, width 1300 mm) and PE film (polyethylene film, weight 25 g / m 2, width 1310mm) are attached to both sides of the prepreg, and then rolled up after passing through the laminating roller to obtain a prepreg with two sides coated. The structure is as follows Figure 2 As shown, the structure is OPP film-prepreg-PE film.

[0023] (2) Take two pieces of cut prepreg, tear off the PE film on the surface, and stick them on the honeycomb core (purchased from Jiaxing Yagang Composite Materials Co., Ltd., the honeycomb core has a side length of 1.83mm and a density of 56kg / m 3 ) The upper and lower surfaces have a structure of OPP film-prepreg-honeycomb core-prepreg-OPP film, as shown in the following example: Figure 3 As shown, the composite honeycomb panel is then heat-cured using a hot press at 0.3 MPa and 150° C., and the hot pressing is stopped after 15 minutes. The OPP films on the upper and lower surfaces of the composite honeycomb panel are torn off to obtain a composite honeycomb panel.

[0024] Example 2 (1) Use Figure 1 The production process shown in the figure is to prepare the surface coated prepreg, and eight three-fly satin fiberglass fabrics (weight 300g / m 2 , width 1270mm), is drawn from the fabric unwinding roller, passes through the guide roller and enters the resin tank, which is filled with epoxy resin acetone dispersion with a solid content of 78% (using epoxy resin model BAC 811 produced by Lily Aerospace Composite Materials Co., Ltd. as the raw material). A circulating pump is used to control the liquid level of the resin tank to maintain a depth of 23cm. The impregnated fabric enters the roller to remove excess epoxy resin acetone dispersion on the surface, maintaining the liquid volume at 315g / m 2 The fabric then enters the oven at a rate of 4 m / min, with a temperature of 105°C in zone 1, 120°C in zone 2, 100°C in zone 3, and 95°C in zone 4. It leaves the oven after 3 minutes. The prepreg after leaving the oven passes through a cooling roller, and then OPP film (biaxially oriented polypropylene film) and PE film (polyethylene film) are attached to both sides of the prepreg respectively. After passing through a laminating roller, it is rolled up to obtain a prepreg with two-sided film coating. The structure is as follows: Figure 2 As shown, the structure is OPP film-prepreg-PE film.

[0025] (2) Take two pieces of sheared prepreg, tear off the PE film and OPP film on the surface, and stick them on the upper and lower surfaces of the honeycomb core (purchased from Jiaxing Yagang Composite Materials Co., Ltd., CMAG-CNC1-1.83-56). Then take two more pieces of sheared prepreg, tear off the PE film on the surface, and continue to stick them on the upper and lower surfaces of the honeycomb core. The structure is OPP film-prepreg-prepreg-honeycomb core-prepreg-prepreg-OPP film. Figure 4As shown, the composite honeycomb panel is then heat-cured using a hot press at 0.3 MPa and 150° C., and the hot pressing is stopped after 15 minutes. The OPP films on the upper and lower surfaces of the composite honeycomb panel are torn off to obtain a composite honeycomb panel.

[0026] Example 3 (1) Use Figure 1 The production process shown in the figure is to prepare the surface coated prepreg, and eight three-fly satin fiberglass fabrics (weight 300g / m 2 The fabric is drawn from the unwinding roller and passed through a guide roller into a resin tank filled with a 78% solid content epoxy resin acetone dispersion (BAC 811 epoxy resin produced by Lily Aerospace Composite Materials Co., Ltd.). A circulating pump is used to control the liquid level in the resin tank to maintain a depth of 23 cm. The impregnated fabric enters the nip roller to remove excess epoxy resin acetone dispersion from the surface, maintaining a liquid volume of 315 g / m 2 The fabric then enters the oven at a rate of 4 m / min, with a temperature of 105°C in zone 1, 120°C in zone 2, 100°C in zone 3, and 95°C in zone 4. It leaves the oven after 3 minutes. The prepreg after leaving the oven passes through a cooling roller, and then OPP film (biaxially oriented polypropylene film) and PE film (polyethylene film) are attached to both sides of the prepreg respectively. After passing through a laminating roller, it is rolled up to obtain a prepreg with two-sided film coating. The structure is as follows: Figure 2 As shown, the structure is OPP film-prepreg-PE film.

[0027] (2) Take two pieces of sheared prepreg, tear off the PE film and OPP film on the surface, and stick them on the upper and lower surfaces of the honeycomb core (purchased from Jiaxing Yagang Composite Materials Co., Ltd., CMAG-CNC1-1.83-56). Then take two more pieces of sheared prepreg, tear off the PE film on the surface, and continue to stick them on the upper and lower surfaces of the honeycomb core. The structure is OPP film-prepreg-prepreg-honeycomb core-prepreg-prepreg-OPP film. Figure 4 As shown, it is then hot-pressed and cured using a hot press at 0.3 MPa and 140° C., the hot pressing is stopped after 25 minutes, and the OPP films on the upper and lower surfaces of the composite honeycomb panel are torn off to obtain a composite honeycomb panel.

[0028] Example 4 (1) Use Figure 1 The production process shown in the figure is to prepare the surface coated prepreg, and eight three-fly satin fiberglass fabrics (weight 300g / m 2The fabric is drawn from the unwinding roller and passed through a guide roller into a resin tank filled with a 78% solid content epoxy resin acetone dispersion (BAC 811 epoxy resin produced by Lily Aerospace Composite Materials Co., Ltd.). A circulating pump is used to control the liquid level in the resin tank to maintain a depth of 23 cm. The impregnated fabric enters the nip roller to remove excess epoxy resin acetone dispersion from the surface, maintaining a liquid volume of 315 g / m 2 The fabric then enters the oven at a rate of 4 m / min, with a temperature of 105°C in zone 1, 120°C in zone 2, 100°C in zone 3, and 95°C in zone 4. It leaves the oven after 3 minutes. The prepreg after leaving the oven passes through a cooling roller, and then OPP film (biaxially oriented polypropylene film) and PE film (polyethylene film) are attached to both sides of the prepreg respectively. After passing through a laminating roller, it is rolled up to obtain a prepreg with two-sided film coating. The structure is as follows: Figure 2 As shown, the structure is OPP film-prepreg-PE film.

[0029] (2) Take two pieces of sheared prepreg, tear off the PE film and OPP film on the surface, and stick them on the upper and lower surfaces of the honeycomb core (purchased from Jiaxing Yagang Composite Materials Co., Ltd., CMAG-CNC1-1.83-56). Then take two more pieces of sheared prepreg, tear off the PE film on the surface, and continue to stick them on the upper and lower surfaces of the honeycomb core. The structure is OPP film-prepreg-prepreg-honeycomb core-prepreg-prepreg-OPP film. Figure 4 As shown, it is then hot-pressed and cured at 0.3 MPa and 130° C. using a hot press. The hot pressing is stopped after 35 minutes, and the OPP films on the upper and lower surfaces of the composite honeycomb panel are torn off to obtain a composite honeycomb panel.

[0030] Figures 5-8 These are optical photographs of the composite honeycomb panels prepared in Examples 1 to 4. It can be seen from the figures that the surfaces of the composite honeycomb panels are flat and smooth without bubbles.

[0031] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A surface-coated prepreg, characterized in that: The preparation method of the surface-coated prepreg is as follows: The fabric is immersed in a resin dispersion for impregnation, and then the fabric is pressed, dried, and cooled in sequence. A biaxially oriented polypropylene film is placed on one side of the fabric, and a polyethylene film is placed on the other side for winding to obtain a surface-coated prepreg.

2. The surface-coated prepreg according to claim 1, characterized in that The fabric is glass fiber fabric or carbon fiber fabric; The resin dispersion is an acetone dispersion of epoxy resin with a solid content of 76% to 80%; The pressing interval is 0.45~0.55mm; The drying temperature is 90-125°C; The cooling temperature is 5-10°C.

3. Use of a surface-coated prepreg according to any one of claims 1 to 2 in the preparation of a composite honeycomb panel, characterized in that: The method of application comprises the following steps: The polyethylene film of the prepreg with the surface coating is removed, and the exposed side of the obtained prepreg is attached to the surface of the honeycomb core and hot-pressed and cured. After the hot-pressing and curing is completed, the biaxially oriented polypropylene film is removed to obtain a composite honeycomb panel product.

4. Use of a surface-coated prepreg according to claim 3 in preparing a composite honeycomb panel, characterized in that: The temperature of the hot pressing curing is 130-150° C., the pressure is 0.3 MPa, and the time is 15-35 minutes.

5. Use of a surface-coated prepreg according to claim 4 in preparing a composite honeycomb panel, characterized in that: When preparing a composite honeycomb panel, if multiple layers of prepreg need to be attached, the biaxially oriented polypropylene film and polyethylene film on the surface of each inner prepreg layer need to be removed.

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