A vacuum packaging structure and method for high-temperature and high-pressure autoclave molding

Abstract

The present invention discloses a vacuum packaging structure and method for high-temperature and high-pressure autoclave molding, and belongs to the technical field of autoclave molding composite materials. The present invention places a composite material preform in a mold, and the mold has a vacuuming channel; places a layer of high-temperature demoulding material on the upper and lower surfaces of the preform, and then places a layer of high-temperature breathable material on the upper high-temperature demoulding material; adheres three layers of sealing tape to the outer edge of the mold, namely high-temperature sealing tape, low-temperature sealing tape and high-temperature sealing tape, to present a sandwich structure, and the sealing tapes are all located outside the vacuuming channel; covers the outermost layer with a vacuum bag, and forms a packaging system by bonding it to the outer layer of high-temperature sealing tape, and forms a vacuum packaging system by vacuuming. The present invention combines the temperature resistance of the high-temperature sealing tape and the excellent bonding performance of the low-temperature sealing tape, which can significantly improve the airtightness and packaging efficiency of the packaging system, and improve the molding quality and qualified rate of the product.

Description

Technical Field

[0001] The invention relates to a vacuum bag packaging structure and method for high-temperature and high-pressure autoclave molding, belonging to the technical field of autoclave molding composite materials. Background Art

[0002] With the improvement of the performance of aerospace equipment, the technical indicators of composite materials such as lightweight and high temperature resistance are becoming increasingly stringent. High-temperature resistant resin-based composite materials have become the main material solution for load-bearing structures due to their excellent thermal and mechanical properties. High-temperature resistant resin-based composite materials (such as high-temperature bismaleimide, polyimide, etc.) can be prepared through a variety of molding methods, such as autoclave molding process, compression molding process, etc. Compared with other molding processes, the autoclave molding process has the characteristics of uniform distribution of temperature and pressure fields, and no restrictions on the size and shape of components. It has become one of the most important methods for molding high-temperature resistant resin-based composite materials.

[0003] Autoclave molding involves placing composite materials in a molding tool, forming a vacuum packaging state through vacuum bags, sealing tape, and related auxiliary materials, and setting a corresponding temperature and pressure curing program based on the characteristics of the composite materials. The molding temperature and molding pressure act indirectly on the composite materials through the packaging system to complete the curing and molding of the product. Existing autoclave molding packaging systems usually use vacuum bags and sealing tape for packaging. However, due to the high molding temperature, high molding pressure, and long curing time of composite materials such as high-temperature bismaleimide and polyimide, the long-term high temperature and high pressure environment can easily cause the packaging system to break or become debonded, resulting in a decrease in the vacuum degree of the packaging system. In severe cases, the bag may burst, causing the packaging system to completely fail, directly affecting the molding quality of the composite materials. In addition, due to different material properties, compared with low-temperature sealing tape, high-temperature sealing tape has insufficient adhesion, making it difficult to encapsulate and prone to debonding and cracking if not properly encapsulated, which increases the difficulty of encapsulation and reduces the efficiency of encapsulation. Currently, there is a patent that combines low-temperature sealing tape and high-temperature sealing tape to improve the vacuum degree of the packaging system. For example, the CN115195155A patent uses a double-layer high-temperature sealing tape and a single-layer low-temperature sealing tape, which can solve the problem of high vacuum leakage under high temperature and high pressure conditions during autoclave molding of composite materials. However, since the single-layer low-temperature sealing tape is on the outside of the double-layer sealing tape, the low-temperature sealing tape will decompose when the autoclave temperature exceeds 200°C, and the thermal decomposition products will contaminate the autoclave body, thereby reducing the service life of the autoclave and affecting subsequent autoclave molded products. Summary of the Invention

[0004] The purpose of the present invention is to propose a new type of "high temperature-low temperature-high temperature" sandwich structure and its packaging method, which is suitable for high temperature and high pressure autoclave molding, and can be used for high temperature bismuth, low temperature polyimide, high temperature polyimide and other resin system autoclave molding. The maximum molding temperature covers 220~400℃, which can effectively avoid the packaging system from debonding, breakage, etc. during the autoclave curing molding process, significantly improve the airtightness and packaging efficiency of the packaging system, and improve the product molding quality and pass rate.

[0005] The present invention provides the following technical solutions to achieve the above-mentioned objectives:

[0006] A vacuum bag packaging structure for high-temperature and high-pressure autoclave molding, comprising:

[0007] A layer of high-temperature demoulding material is placed on the upper and lower surfaces of the composite material preform, and the preform is placed in a mold having a vacuum channel;

[0008] A layer of high-temperature breathable material is placed on the upper high-temperature release material;

[0009] The sandwich structure composed of high-temperature sealing tape, low-temperature sealing tape and high-temperature sealing tape is bonded to the outer edge of the mold and located outside the vacuum channel of the mold;

[0010] A vacuum bag is located on the outermost layer and is bonded to the outer layer of high-temperature sealing tape.

[0011] Furthermore, the composite material is selected from high-temperature bismaleimide resin, low-temperature polyimide resin or high-temperature polyimide resin.

[0012] Furthermore, the high-temperature sealing tape is a modified polysiloxane rubber tape, and the low-temperature sealing tape is a butyl rubber tape.

[0013] A vacuum bag packaging method for high-temperature and high-pressure autoclave molding comprises the following steps:

[0014] (1) placing a composite material preform in a mold having a vacuum channel;

[0015] (2) placing a layer of high-temperature demoulding material on the upper and lower surfaces of the preform, and then placing a layer of high-temperature breathable material on the upper high-temperature demoulding material;

[0016] (3) Three layers of sealing tape are bonded to the outer edge of the mold, namely, high-temperature sealing tape, low-temperature sealing tape, and high-temperature sealing tape, forming a sandwich structure, and the sealing tapes are all located outside the vacuum channel;

[0017] (4) Covering the outermost layer with a vacuum bag, bonding it to the outer layer with a high-temperature sealing tape to form a packaging system, and then forming a vacuum packaging system by vacuuming.

[0018] Furthermore, the composite material is selected from high-temperature bismaleimide resin, low-temperature polyimide resin or high-temperature polyimide resin.

[0019] Furthermore, the high-temperature sealing tape is a modified polysiloxane rubber tape, and the low-temperature sealing tape is a butyl rubber tape.

[0020] The beneficial effects achieved by the present invention are as follows:

[0021] The quality of high-temperature-resistant resin-based composite molding is closely related to the state of the autoclave molding packaging system. The novel double-layer "high-temperature-low-temperature" sandwich packaging method proposed in this invention incorporates two layers of high-temperature sealing tape, acting as two lines of defense. The outer high-temperature sealing tape acts as a protective layer, reducing the risk of debonding and damage to the packaging system caused by high temperature and high pressure. The inner high-temperature sealing tape acts as a sealing layer, ensuring effective transmission of molding pressure. Furthermore, a low-temperature sealing tape is introduced between the two layers of high-temperature sealing tape. Due to its inherent material properties, the low-temperature sealing tape exhibits superior adhesion compared to high-temperature sealing tape, improving packaging efficiency and further enhancing the airtightness of the packaging system. Furthermore, the low-temperature sealing tape is positioned between the two layers of high-temperature sealing tape. Even if the temperature during autoclave curing exceeds its decomposition temperature (above 200°C), its decomposition products are confined between the two layers of high-temperature sealing tape, preventing contamination within the autoclave and contamination of the composite material preparation. Therefore, the "high-temperature-low-temperature-high-temperature" sandwich packaging method proposed in this invention is practical and has significant economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of vacuum bag packaging for high-temperature and high-pressure autoclave molding in Example 1 of the present invention. DETAILED DESCRIPTION

[0023] In order to make the various technical features and advantages or technical effects of 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.

[0024] Example 1:

[0025] This example uses high-temperature bismuth composite materials as the verification object, and uses the vacuum bag packaging method for high-temperature and high-pressure autoclave molding proposed in the present invention to perform "high-temperature-low-temperature-high-temperature" sandwich structure packaging to achieve the sealing of the autoclave vacuum system. Figure 1 As shown, the encapsulation steps are as follows:

[0026] (1) placing a high-temperature BMI composite material preform in a mold having a vacuum channel;

[0027] (2) Place a layer of high-temperature demoulding material on the upper and lower surfaces of the preform, and then place a layer of high-temperature breathable material on the upper high-temperature demoulding material to better vent the packaging system;

[0028] (3) Three layers of sealing tape are bonded to the outer edge of the mold, namely, high-temperature sealing tape, low-temperature sealing tape, and high-temperature sealing tape, forming a sandwich structure, and the sealing tapes are all located outside the vacuum channel;

[0029] (4) A high-temperature vacuum bag is laid on the outermost layer, and a packaging system is formed by bonding it with a sealing tape, and a vacuum packaging system is formed by vacuuming.

[0030] The vacuum packaging system was subjected to an autoclave curing operation. Under the conditions of 250° C., 5 h, and 0.8 MPa pressure, the vacuum packaging system had excellent airtightness and a vacuum degree of -99 KPa.

[0031] Example 2:

[0032] Low-temperature polyimide composite materials were selected as the verification object, and the autoclave vacuum system was sealed according to the new "high-temperature-low-temperature-high-temperature" sandwich structure packaging method. The packaging process is as follows:

[0033] (1) placing a low-temperature polyimide composite material preform in a mold, wherein the mold has a vacuum channel;

[0034] (2) Place a layer of high-temperature demoulding material on the upper and lower surfaces of the preform, and then place a layer of high-temperature breathable material on the upper high-temperature demoulding material to better vent the packaging system;

[0035] (3) Three layers of sealing tape are bonded to the outer edge of the mold, namely, high-temperature sealing tape, low-temperature sealing tape, and high-temperature sealing tape, forming a sandwich structure, and the sealing tapes are all located outside the vacuum channel;

[0036] (4) A high-temperature vacuum bag is laid on the outermost layer, and a packaging system is formed by bonding it with a sealing tape, and a vacuum packaging system is formed by vacuuming.

[0037] The vacuum packaging system was subjected to an autoclave curing operation. Under the conditions of 300°C, 3h and 1.0MPa pressure, the vacuum packaging system had excellent airtightness and a vacuum degree of -98KPa.

[0038] Example 3:

[0039] High-temperature polyimide composite materials were selected as the verification object, and the autoclave vacuum system was sealed according to the new "high-temperature-low-temperature-high-temperature" sandwich structure packaging method. The packaging process is as follows:

[0040] (1) placing a high-temperature polyimide composite material preform in a mold, wherein the mold has a vacuum channel;

[0041] (2) Place a layer of high-temperature demoulding material on the upper and lower surfaces of the preform, and then place a layer of high-temperature breathable material on the upper high-temperature demoulding material to better vent the packaging system;

[0042] (3) Three layers of sealing tape are bonded to the outer edge of the mold, namely, high-temperature sealing tape, low-temperature sealing tape, and high-temperature sealing tape, forming a sandwich structure, and the sealing tapes are all located outside the vacuum channel;

[0043] (4) A high-temperature vacuum bag is laid on the outermost layer, and a packaging system is formed by bonding it with a sealing tape, and a vacuum packaging system is formed by vacuuming.

[0044] The vacuum packaging system was subjected to an autoclave curing operation. Under the conditions of 380°C, 3h and 1.5MPa pressure, the vacuum packaging system had excellent airtightness and a vacuum degree of -97KPa.

[0045] Comparative Example 1:

[0046] High-temperature polyimide composite materials were selected as the verification object, and the autoclave vacuum system was sealed using a double-layer high-temperature sealing tape. The packaging process is as follows:

[0047] (1) placing a high-temperature polyimide composite material preform in a mold, wherein the mold has a vacuum channel;

[0048] (2) Place high-temperature demoulding materials on the upper and lower surfaces of the preform, and then place a layer of high-temperature breathable material on the upper high-temperature demoulding material to better vent the packaging system;

[0049] (3) Bonding two layers of high-temperature sealing tape to the outer edge of the mold, with both layers of sealing tape located outside the vacuum channel;

[0050] (4) A high-temperature vacuum bag is laid on the outermost layer, and a packaging system is formed by bonding it with a sealing tape. A vacuum packaging system is then formed by vacuuming. Without the assistance of a low-temperature sealing tape, the packaging efficiency of the vacuum packaging system is low. This is because the low-temperature sealing tape has much better viscosity than the high-temperature sealing tape, so it is easy to bond quickly during packaging, thereby improving packaging efficiency. Based on packaging work experience, the packaging operation of the vacuum system with the assistance of low-temperature sealing tape is expected to be completed within 1 hour, while without the assistance of low-temperature sealing tape, the packaging operation is basically expected to be completed within 2 hours.

[0051] The vacuum packaging system was subjected to an autoclave curing operation. Under the conditions of 380° C., 3 h, and 1.5 MPa pressure, the vacuum packaging system had excellent airtightness and a vacuum degree of -90 KPa.

[0052] Comparative Example 2:

[0053] High-temperature polyimide composite materials were selected as the verification object, and the autoclave vacuum system was sealed using a single layer of high-temperature sealing tape. The packaging process is as follows:

[0054] (1) placing a high-temperature polyimide composite material preform in a mold, wherein the mold has a vacuum channel;

[0055] (2) Place a layer of high-temperature demoulding material on the upper and lower surfaces of the preform, and then place a layer of high-temperature breathable material on the upper high-temperature demoulding material to better vent the packaging system;

[0056] (3) Bonding a single layer of high-temperature sealing tape to the outer edge of the mold, with the sealing tape located outside the vacuum channel;

[0057] (4) A high-temperature vacuum bag is laid on the outermost layer, and a packaging system is formed by bonding it with a sealing tape, and a vacuum packaging system is formed by vacuuming. Due to the lack of the assistance of a low-temperature sealing tape, the packaging efficiency of the vacuum packaging system is low.

[0058] The vacuum packaging system was subjected to an autoclave curing operation. Under the conditions of 380° C., 3 h, and 1.5 MPa pressure, the airtightness of the vacuum packaging system was poor, with a vacuum degree of -73 KPa.

[0059] Although the present invention has been disclosed as above by way of embodiments, they are not intended to limit the present invention. Any appropriate modification or equivalent substitution of the technical solution of the present invention by a person skilled in the art should be included in the protection scope of the present invention. The protection scope of the present invention shall be based on that defined in the claims.

Claims

1. A vacuum bag packaging structure for high temperature and high pressure autoclave molding, characterized in that: include: A layer of high-temperature demoulding material is placed on the upper and lower surfaces of the composite material preform, and the preform is placed in a mold having a vacuum channel; A layer of high-temperature breathable material is placed on the upper high-temperature release material; The sandwich structure composed of high-temperature sealing tape, low-temperature sealing tape and high-temperature sealing tape is bonded to the outer edge of the mold and located outside the vacuum channel of the mold; A vacuum bag is located on the outermost layer and is bonded to the outer layer of high-temperature sealing tape.

2. The vacuum bag packaging structure according to claim 1, wherein: The composite material is selected from high-temperature bismaleimide resin, low-temperature polyimide resin or high-temperature polyimide resin.

3. The vacuum bag packaging structure according to claim 1, wherein: The high-temperature sealing tape is a modified polysiloxane rubber tape, and the low-temperature sealing tape is a butyl rubber tape.

4. A vacuum bag packaging method for high temperature and high pressure autoclave molding, characterized in that: The following steps are involved: (1) placing a composite material preform in a mold having a vacuum channel; (2) placing a layer of high-temperature demoulding material on the upper and lower surfaces of the preform, and then placing a layer of high-temperature breathable material on the upper high-temperature demoulding material; (3) Three layers of sealing tape are bonded to the outer edge of the mold, namely, high-temperature sealing tape, low-temperature sealing tape, and high-temperature sealing tape, forming a sandwich structure, and the sealing tapes are all located outside the vacuum channel; (4) Covering the outermost layer with a vacuum bag, bonding it to the outer layer with a high-temperature sealing tape to form a packaging system, and then forming a vacuum packaging system by vacuuming.

5. The vacuum bag packaging method according to claim 4, wherein: The composite material is selected from high-temperature bismaleimide resin, low-temperature polyimide resin or high-temperature polyimide resin.

6. The vacuum bag packaging method according to claim 4, wherein: The high-temperature sealing tape is a modified polysiloxane rubber tape, and the low-temperature sealing tape is a butyl rubber tape.

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