Sandwich structure composite material capable of enhancing cementing performance and preparation method of sandwich structure composite material

Abstract

The invention discloses a sandwich structure composite material for enhancing cementing performance and a preparation method thereof, and relates to the technical field of composite materials. The sandwich structure composite material provided by the invention is structurally characterized in that an upper skin and a lower skin are bonded with a sandwich material between the upper skin and the lower skin through a reinforced adhesive film respectively, wherein the reinforced adhesive film is structurally one of a conventional adhesive film / fiber mat / conventional adhesive film, a fiber mat / conventional adhesive film / fiber mat and a fiber mat / conventional adhesive film. The fiber mat and the conventional adhesive film are combined to form the required reinforced adhesive film, so that the mechanical property of the sandwich structure composite material can be improved, and the adhesive layer of the adhesive joint surface is prevented from being damaged.

Description

Technical Field

[0001] The invention relates to the technical field of composite materials, and in particular to a sandwich structure composite material with enhanced bonding performance and a preparation method thereof. Background Art

[0002] Various sandwich structures, including honeycomb sandwich structures and foam sandwich structures, usually use adhesive films to bond the core layer and the skin layer during the preparation process. Conventional adhesive films are thin layers of resin films with conventional thicknesses ranging from 0.1mm to 0.5mm. Since the sandwich structure completely relies on the adhesive layer to achieve load transfer between the skin and the core material when it is loaded, the bonding performance of the adhesive layer directly determines the performance of the sandwich structure. The adhesive film material used in traditional sandwich structures is often a resin matrix that has been toughened to a certain extent, and has strong shear strength and high toughness as a whole. However, in sandwich structures, especially foam sandwich structures, a thick adhesive layer is often formed at the interface between the core and the skin. When the sandwich structure is loaded, especially when it is subjected to shear loads, the body strength of the adhesive film resin matrix becomes a short board factor that limits the structural strength, and the adhesive layer is often damaged, causing the sandwich structure to be destroyed. Therefore, it is necessary to design a sandwich structure composite material with enhanced bonding performance for such application requirements, to improve the performance of the adhesive layer in a targeted manner, and to ensure that the structural performance of the honeycomb sandwich structure meets the design requirements.

[0003] Without significantly increasing the weight of the resin, the commonly used resin reinforcement method is to use chopped fibers to improve the performance of the resin matrix, which can significantly improve the structural strength of the matrix with a relatively small weight gain (generally less than 10%). For adhesive films that need to be applied to sandwich structures, hot coating methods are usually used to prepare adhesive films of resin adhesive liquid, but the addition of chopped fibers will significantly increase the viscosity of the resin system, making it difficult to prepare chopped fiber reinforced adhesive films using conventional hot coating methods. Therefore, it is possible to consider using certain process implementation methods to process traditional conventional adhesive films to obtain reinforced adhesive films. Summary of the invention

[0004] The purpose of the present invention is mainly to solve the problem that the adhesive layer of the current sandwich structure is prone to damage when bearing, and proposes a sandwich structure composite material technical solution that can enhance the bonding performance without changing the existing raw material process preparation process and production conditions; and for shelf-type adhesive film products and shelf-type fiber felts, without changing the original conventional adhesive film production conditions, by adding a fiber felt pre-impregnation composite operation after the conventional adhesive film is prepared, the fiber felt and the conventional adhesive film are combined to form the required enhanced adhesive film. According to the process design of pre-impregnation composite, the structural composition of the enhanced adhesive film, the proportion of the enhanced components, etc. can be regulated.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A sandwich structure composite material with enhanced bonding performance, wherein the upper and lower skins are respectively bonded to the middle sandwich material by reinforcing adhesive films, wherein the structure of the reinforcing adhesive film is one of conventional adhesive film / fiber felt / conventional adhesive film, fiber felt / conventional adhesive film / fiber felt, and fiber felt / conventional adhesive film.

[0007] Preferably, the conventional adhesive film is one of an epoxy resin system, a bismaleimide resin system, and a cyanate ester resin system.

[0008] Preferably, the surface density of the conventional film is 100-500 g / m 2 .

[0009] Preferably, the fiber felt is one of carbon fiber felt and aramid fiber felt, and the surface density of the fiber felt is 5-50g / m 2 , corresponding to 1%-10% of the mass of conventional films.

[0010] A method for preparing a sandwich structure composite material with enhanced bonding performance comprises the following steps:

[0011] 1) According to the design structure of the reinforced film, i.e., one of conventional film / fiber felt / conventional film, fiber felt / conventional film / fiber felt, and fiber felt / conventional film, the fiber felt and the conventional film are placed in the corresponding positions of the structural components of the prepreg composite equipment in order;

[0012] 2) According to the types and specifications of conventional adhesive film and fiber mat, set the prepreg composite process parameters, set the gap between the pressure roller and the hot pressing roller according to the designed thickness of the enhanced adhesive film, the thickness of the enhanced adhesive film is determined by the surface density of the conventional adhesive film and the fiber mat, set the temperature of the hot pressing roller, select the cooling platform, protect the release paper according to the normal film winding, and set the winding rate;

[0013] 3) The production line continuously produces the reinforced film, and the release paper is removed during subsequent use;

[0014] 4) The reinforcing film is used as a connecting layer between the sandwich material and the skin, and the upper and lower skins are bonded to the sandwich material in the middle through the reinforcing film to form a sandwich structure composite material.

[0015] Preferably, the temperature of the hot pressing roller in step 2) is set to 80-120°C.

[0016] Preferably, the cooling platform in step 2) is an air cooling or water cooling platform.

[0017] Preferably, in step 2), the winding rate is set to 2-10 cm / s.

[0018] The present invention has the following advantages:

[0019] 1. Without changing the existing sandwich structure composite material preparation technology, the bonding performance of the sandwich structure can be significantly improved.

[0020] 2. Strong applicability. Since the addition of chopped fibers as reinforcing components and the step-by-step implementation of the resin coating process do not affect the resin viscosity flow characteristics of the resin coating process, and thus do not have any impact on the production process of the original film, it can be applied to shelf-type film products and shelf-type fiber felt products that have been prepared.

[0021] 3. By controlling the types and specifications of the prepreg composite film and the types and specifications of the fiber mat, the performance control level of the reinforced film prepreg with different combinations of fiber mats and films and reinforcing component contents can be achieved (the fiber and resin are evenly distributed in steps and the content deviation is controlled within 5%), and the process adjustability and controllability are strong.

[0022] 4. Conventional prepreg equipment can be used to realize the assembly line production of reinforced film, which can meet the application requirements of industrial mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the structure of a sandwich composite material with enhanced bonding performance in an embodiment.

[0024] Figure 2 Schematic diagram of three structural designs of reinforced films.

[0025] Figure 3 It is a schematic diagram of the preparation of the reinforced adhesive film of the present invention. DETAILED DESCRIPTION

[0026] In order to make the various technical features and advantages or technical effects in the above technical solutions of the present invention more obvious and easy to understand, they are described in detail below with reference to the accompanying drawings.

[0027] The embodiment of the present invention provides a sandwich structure composite material with enhanced bonding performance, the structure of which is as follows Figure 1 As shown, the upper and lower skins are bonded to the core material in the middle by reinforcing adhesive films. The structure of the reinforcing adhesive film is one of conventional adhesive film / fiber felt / conventional adhesive film, fiber felt / conventional adhesive film / fiber felt, and fiber felt / conventional adhesive film, such as Figure 2 shown.

[0028] As a preferred embodiment, the conventional adhesive film is one of an epoxy resin system, a bismaleimide resin system, and a cyanate resin system.

[0029] As a preferred embodiment, the surface density of the conventional adhesive film is 100-500 g / m 2, corresponding to a thickness of 0.1-0.5mm.

[0030] As a preferred embodiment, the fiber felt is one of carbon fiber felt and aramid fiber felt, and the surface density of the fiber felt is 5-50g / m 2 , corresponding to 1%-10% of the mass of conventional film, the surface density of the fiber felt can be adjusted according to the surface density of conventional film.

[0031] The present invention also provides a method for preparing a sandwich structure composite material with enhanced bonding performance, such as Figure 3 As shown, structural components 1, 2, and 3 refer to fiber felt and conventional adhesive film, and specifically include the following steps:

[0032] 1) According to the design structure of the reinforced film, the fiber felt and the conventional film are placed in the corresponding positions of the structural components of the prepreg composite equipment in order, and after being pulled into place, a production line similar to the preparation of prepreg is formed;

[0033] 2) According to the types and specifications of conventional adhesive film and fiber mat, set the prepreg composite process parameters, set the gap between the pressure roller and the hot pressing roller according to the designed thickness of the reinforced adhesive film, the thickness of the reinforced adhesive film is determined by the surface density of the conventional adhesive film and the fiber mat, set the temperature of the hot pressing roller to 80-120°C, the cooling platform adopts air cooling or water cooling platform, and the release paper is protected according to the normal film winding, and the winding rate is set to 2-10cm / s;

[0034] 3) After continuous production on the assembly line, a reinforced film with a designed structure is obtained, and the release paper can be removed for subsequent use;

[0035] 4) In keeping with the use of ordinary adhesive films for sandwich structure bonding and forming, the reinforced adhesive film is used as a connecting layer between the core material and the skin, and the upper and lower skins are respectively bonded to the core material in the middle through the reinforced adhesive film to form a sandwich structure composite material.

[0036] The performance test of the sandwich structure composite material with enhanced bonding performance of the present invention is as follows:

[0037] The surface density of the present invention is 200g / m 2 Conventional film and 10g / m 2The fiber felt is compounded according to the structure of "conventional film / fiber felt / conventional film" to obtain a reinforced film, and the reinforced film is used to prepare a sandwich structure composite material according to the structure of "upper skin / reinforced film / sandwich material / reinforced film / lower skin". Compared with the sandwich structure composite material prepared by using conventional films with the same structure (i.e., "upper skin / conventional film / sandwich material / conventional film / lower skin"), the bending strength of the sandwich structure composite material prepared by the present invention is increased by 15%, and the lateral pressure strength is increased by 40%, which shows that the mechanical function of the composite material is significantly improved.

[0038] Although the present invention has been disclosed as above by way of embodiments, it is not intended to limit the present invention. Appropriate modifications or equivalent substitutions of the technical solutions of the present invention made by ordinary technicians in the field should all be included in the protection scope of the present invention. The protection scope of the present invention shall be based on what is defined in the claims.

Claims

1. A sandwich structure composite material with enhanced bonding performance, characterized in that: Its structure is that the upper and lower skins are bonded to the sandwich material in the middle by reinforcing films, wherein the structure of the reinforcing film is one of conventional film / fiber felt / conventional film, fiber felt / conventional film / fiber felt, and fiber felt / conventional film.

2. The sandwich structure composite material according to claim 1, characterized in that: Conventional adhesive films are one of epoxy resin systems, bismaleimide resin systems, and cyanate resin systems.

3. The sandwich structure composite material according to claim 2, characterized in that: The surface density of conventional film is 100-500g / m 2 .

4. The sandwich structure composite material according to claim 1, characterized in that: The fiber felt is one of carbon fiber felt and aramid fiber felt.

5. The sandwich structure composite material according to claim 4, characterized in that: The surface density of the fiber mat is 5-50g / m 2 .

6. A method for preparing a sandwich structure composite material with enhanced bonding performance, characterized in that: The following steps are involved: 1) According to the design structure of the reinforced film, i.e., one of conventional film / fiber felt / conventional film, fiber felt / conventional film / fiber felt, and fiber felt / conventional film, the fiber felt and the conventional film are placed in the corresponding positions of the structural components of the prepreg composite equipment in order; 2) According to the types and specifications of conventional adhesive film and fiber mat, set the prepreg composite process parameters, set the gap between the pressure roller and the hot pressing roller according to the designed thickness of the enhanced adhesive film, the thickness of the enhanced adhesive film is determined by the surface density of the conventional adhesive film and the fiber mat, set the temperature of the hot pressing roller, select the cooling platform, protect the release paper according to the normal film winding, and set the winding rate; 3) The production line continuously produces the reinforced film, and the release paper is removed during subsequent use; 4) The reinforcing film is used as a connecting layer between the sandwich material and the skin, and the upper and lower skins are bonded to the sandwich material in the middle through the reinforcing film to form a sandwich structure composite material.

7. The preparation method according to claim 6, characterized in that: The conventional adhesive film is one of epoxy resin system, bismaleimide resin system and cyanate resin system; the fiber felt is one of carbon fiber felt and aramid fiber felt.

8. The preparation method according to claim 7, characterized in that: The surface density of conventional film is 100-500g / m 2 .

9. The preparation method according to claim 7, characterized in that: The surface density of the fiber mat is 5-50g / m 2 .

10. The preparation method according to claim 6, characterized in that: In step 2), the temperature of the hot pressing roller is set to 80-120° C.; the cooling platform adopts air cooling or water cooling platform; and the winding speed is set to 2-10 cm / s.

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