A heat-insulating microporous foam composite structure film and its preparation method

Abstract

The present invention discloses a heat-insulating microporous foam composite structure membrane. The upper surface of the substrate layer is made of corrosion-resistant PVC / PVDF membrane by using double-sided hetero-coating technology, and the lower surface is coated with composite foaming resin. The heat-insulating microporous foam composite structure membrane is obtained by integrated molding technology. The substrate layer is a fiber-reinforced resin-based composite sheet; the corrosion-resistant PVC / PVDF membrane is composed of PVC membrane, polymer adhesive and PVDF membrane; the composite foaming resin is composed of aerogel particles, PVC resin, plasticizer, stabilizer and foaming agent. Chemical bonding and physical adsorption are used to realize the foaming agent on the surface and pores of inorganic particles, especially porous particles. This structure realizes the in-situ generation of gas on the interface layer with the lowest nucleation energy barrier, maximizes the heterogeneous nucleation efficiency, improves the pore structure, retains the aerogel pore structure, and comprehensively improves the thermal insulation performance of the foam material.

Description

Technical Field

[0001] The present invention relates to the technical field of foaming materials, and in particular to a heat-insulating microporous foaming composite structure film and a preparation method thereof. Background Art

[0002] High-strength composite membranes are multilayer composite membrane materials made from a base fiber, resin coating, and other functional layers through a special composite process. They possess durability, waterproofing, corrosion resistance, UV protection, and thermal insulation properties, and are widely used in aerospace, marine engineering, military and defense, construction, and other fields. Among these numerous functions, thermal insulation is a crucial one for composite membrane materials. Currently, there are many methods for imparting thermal insulation properties to composite membranes. Among these, microporous foam materials, due to their porous internal structure, result in extremely low gas-phase and solid-phase heat conduction, making them the preferred material for thermal insulation. Leveraging the excellent thermal insulation properties of foam materials and combining them with composite membranes to enhance the thermal insulation and noise reduction capabilities of the composite membranes has become an important development direction for the functionalization of composite membrane materials.

[0003] Although the organic combination of foam material and composite film can give the composite film functions such as heat insulation and noise absorption, there are still many problems in material preparation and composite structure, mainly including: 1) low bonding strength. Composite films are mostly made of high-strength polyester fiber as the base material and PVC resin as the coating. When polymer foam sheet is used to composite it, adhesive bonding or thermal bonding is usually adopted. The incompatibility between the fiber base material and the polymer foam material causes the composite strength of the two to be low, especially after alternating hot and cold use, separation is easy to occur, resulting in a decrease in thermal insulation performance; 2) complex production and processing process. The existing process technology adopts multi-step composite, involving the screening, slicing, gluing, composite, curing and other processes of foam material, with a long production cycle and a complicated process; 3) poor construction performance. Composite films often need to be pulled, twisted, bent and other processes during construction. Many thermal insulation foam materials are brittle, and bonding with composite film will seriously affect the flexibility and foldability of the material. In particular, when silica aerogel is used, its brittle texture seriously affects the use of composite film. Therefore, it is urgent to develop a low-cost, effective and easy-to-implement technical route for industrial production. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a heat-insulating microporous foamed composite structure membrane and a preparation method thereof. The present invention proposes to prepare a microporous foamed composite structure membrane material by adopting a double-sided coating process on a base cloth (one side is foamed and the other side is not foamed) and an integrated continuous production technology. The high strength and high corrosion resistance of the composite membrane are achieved by adopting high-strength fiber base cloth pretreatment technology, optimizing the pre-coating and PVC coating formula, and high-bonding PVDF coating. By adding nano-aerogel particles loaded with a foaming agent to the foaming resin, the bubble size is reduced and the bubble density is increased. At the same time, high-insulation aerogel materials are introduced to achieve excellent thermal insulation performance, thereby realizing the efficient preparation of high-performance heat-insulating microporous foamed composite structure membranes.

[0005] The specific technical solutions of the present invention are:

[0006] A heat-insulating microporous foam composite structure membrane utilizes a double-sided different coating process technology to achieve a corrosion-resistant PVC / PVDF membrane on the upper surface of the substrate layer, and a composite foaming resin is coated on the lower surface. The heat-insulating microporous foam composite structure membrane is obtained through an integrated molding technology. The characteristics are: the substrate layer is a fiber-reinforced resin-based composite sheet; the corrosion-resistant PVC / PVDF membrane is composed of a PVC film, a polymer adhesive and a PVDF membrane; the composite foaming resin is composed of aerogel particles, PVC resin, a plasticizer, a stabilizer and a foaming agent.

[0007] Preferably, the fibers of the fiber-reinforced resin-based composite sheet are one or more of glass fibers, carbon fibers, boron fibers or aramid fibers, and the resin is one or more of unsaturated polyester, vinyl resin, polyurethane resin, epoxy resin or phenolic resin.

[0008] Preferably, the polymer adhesive is an acrylic adhesive.

[0009] Preferably, the aerogel powder is silica aerogel powder.

[0010] Preferably, the plasticizer is one or more of dioctyl phthalate, dioctyl terephthalate, octyl stearate, or dioctyl adipate.

[0011] Preferably, the stabilizer is one or more of zinc stearate, calcium stearate, barium stearate, dibutyltin dilaurate or dibutyltin maleate.

[0012] Preferably, the foaming agent is an azo foaming agent or a sulfonylhydrazine foaming agent, or a mixture of the two.

[0013] The present invention also discloses a method for preparing a heat-insulating microporous foamed composite structure film, comprising the following steps:

[0014] S1. Preparation of PVC / aerogel particle composite foaming material

[0015] S11, preparing SiO2 aerogel particles;

[0016] S12, modifying SiO2 aerogel particles by using a silane coupling agent;

[0017] S13, loading the modified SiO2 aerogel with a foaming agent by chemical grafting and impregnation;

[0018] Azo compounds are grafted onto the aerogel surface by reacting the carboxyl groups of azobis(cyanovaleric acid) in azo foaming agents with the epoxy groups in silane coupling agents. Alternatively, azo foaming agents or sulfonylhydrazide foaming agents are loaded into the aerogel pores via an impregnation method. The former method controls the grafting rate by adjusting the reaction temperature and time, while the latter method controls the loading amount by adjusting the type of silane coupling agent and the solution concentration.

[0019] S14, mixing the modified aerogel particles with PVC resin, plasticizer, and stabilizer to form a foaming slurry and coating the foaming slurry on the fiber-reinforced resin-based composite sheet;

[0020] SiO2 aerogel loaded with a foaming agent allows the foaming agent to generate gas in situ at the interface layer where the nucleation energy barrier is the lowest, thereby maximizing the heterogeneous nucleation efficiency and improving the pore structure while retaining the aerogel pore structure, thereby comprehensively improving the thermal insulation performance of the foaming material.

[0021] S2, preparation of PVC / PVDF composite coating;

[0022] S21, performing surface treatment on the base fabric using a surface modifier;

[0023] S22, applying a high-bonding PVC pre-coating layer on one side of the base fabric;

[0024] In order to solve the problems of poor permeability between PVC film and polyester industrial yarn substrate and low bonding strength between PVC film and fiber, a low-viscosity and high-permeability PVC pre-coating slurry formula is adopted, the cross-linking agent ratio is appropriately increased, and the pressure of the pressing roller after dipping is increased to improve its high permeability, thereby improving the bonding strength between PVC film and fiber and the overall tear resistance of the membrane material.

[0025] S23, coating a PVC layer on the PVC pre-coating layer;

[0026] S24. First apply a layer of acrylic adhesive layer having high bonding performance with both PVDF and PVC film on the surface of the PVC coating, and then apply the PVDF coating.

[0027] By first applying a modified polymer cross-linking layer with high adhesion to both PVDF and PVC film on the surface of the PVC coating, and then coating PVDF, the technical problems of large hardness difference, low bonding strength and easy peeling between PVDF coating and PVC coating are solved, while the corrosion resistance of the composite film is improved.

[0028] Preferably, in S11, ethyl orthosilicate, water, ethanol and drying chemical control agent DCCA are placed in a reactor in a certain molar ratio, stirred evenly and then a certain mass of fluorine-containing solution is added. After stirring for several minutes, a gel is formed and aged at room temperature for 12-24 hours. After the aging is completed, solvent replacement is performed, and the mixture is dried at a certain ambient temperature and finally crushed to obtain silica aerogel particles.

[0029] Preferably, in S12, the silane coupling agent is one or more of KH550, KH570 or KH560.

[0030] Preferably, the coating process in S14 and S24 is blade coating.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) This project uses a method of combining aerogel particles with polymer foaming materials to prepare composite foaming materials. Chemical bonding and physical adsorption are used to achieve the foaming agent on the surface and pores of inorganic particles, especially porous particles. This structure achieves the in-situ generation of gas at the interface layer with the lowest nucleation energy barrier, maximizes the heterogeneous nucleation efficiency, improves the pore structure, retains the aerogel pore structure, and comprehensively improves the thermal insulation performance of the foaming material.

[0033] (2) This project adopts a double-sided coating process and an integrated molding process to realize the production of thermal insulation structural composite membrane. Compared with the traditional process, the process is simple and the bonding strength of each layer is high, which provides new ideas and methods for the design and preparation of functional structural composite membrane materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a cross-sectional SEM image of the high-performance heat-insulating microporous foamed composite structure membrane prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0035] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0036] Example 1

[0037] A heat-insulating microporous foam composite structural membrane utilizes a double-sided different coating process to achieve a corrosion-resistant PVC / PVDF membrane on the upper surface of the substrate layer, and a composite foaming resin is coated on the lower surface. The heat-insulating foam membrane material is obtained through integrated molding technology. The substrate layer is a fiber-reinforced resin-based composite sheet; the upper surface is composed of a PVC film, a polymer adhesive, and a PVDF film; the lower surface is composed of aerogel particles, PVC resin, a plasticizer, and a foaming agent.

[0038] The preparation method of the high-performance heat-insulating microporous foam composite structure film comprises the following steps:

[0039] (1) Surface modification of glass fiber reinforced epoxy resin based composite sheets;

[0040] (2) applying a high-bonding PVC pre-coating layer on one side of the base fabric by a doctor blade coating process, and then applying a PVC layer on the PVC pre-coating layer;

[0041] (3) First apply a layer of acrylic adhesive with high bonding performance on the surface of the PVC coating, and then apply the PVDF coating;

[0042] (4) SiO2 aerogel particles were prepared by the sol-gel method and then surface modified with KH560. The mass ratio of SiO2 aerogel particles to KH560 was 1:2.

[0043] (5) The azo foaming agent and the modified SiO2 aerogel particles are uniformly dispersed in DMF at a mass ratio of 1:1, and then reacted at 80°C for 10 hours. After the reaction, the product is centrifuged and washed with ethanol to obtain SiO2 aerogel particles grafted with an azo foaming agent.

[0044] (6) PVC resin is mixed with the aerogel particles obtained in step (5), dioctyl phthalate, and zinc stearate in a mass ratio of 90:6:3:1 to form a foaming slurry, which is then applied on a fiber-reinforced resin-based composite sheet.

[0045] (7) The film is foamed in a high-temperature foaming furnace at 135°C and finally rolled up to obtain a thermal insulation structure composite film material.

[0046] Example 2

[0047] A heat-insulating microporous foam composite structural membrane utilizes a double-sided different coating process to achieve a corrosion-resistant PVC / PVDF membrane on the upper surface of the substrate layer, and a composite foaming resin is coated on the lower surface. The heat-insulating foam membrane material is obtained through integrated molding technology. The substrate layer is a fiber-reinforced resin-based composite sheet; the upper surface is composed of a PVC film, a polymer adhesive, and a PVDF film; the lower surface is composed of aerogel particles, PVC resin, a plasticizer, and a foaming agent.

[0048] The preparation method of the high-performance heat-insulating microporous foam composite structure film comprises the following steps:

[0049] (1) Surface modification of glass fiber reinforced vinyl resin based composite sheets;

[0050] (2) applying a high-bonding PVC pre-coating layer on one side of the base fabric by a doctor blade coating process, and then applying a PVC layer on the PVC pre-coating layer;

[0051] (3) First apply a layer of acrylic adhesive with high bonding performance on the surface of the PVC coating, and then apply the PVDF coating;

[0052] (4) SiO2 aerogel particles were prepared by the sol-gel method and then surface modified with KH570. The mass ratio of SiO2 aerogel particles to KH560 was 1:3.

[0053] (5) The azo foaming agent and the modified SiO2 aerogel particles are uniformly dispersed in DMF at a mass ratio of 1:1, immersed at room temperature for 24 hours, and the supernatant is removed and filtered and dried to obtain SiO2 aerogel particles grafted with the azo foaming agent.

[0054] (6) PVC resin is mixed with the aerogel particles obtained in step (5), dioctyl terephthalate, and calcium stearate in a mass ratio of 90:7:2:1 to form a foaming slurry, which is then applied on a fiber-reinforced resin-based composite sheet.

[0055] (7) The film is foamed in a high-temperature foaming furnace at 145°C and finally rolled up to obtain a thermal insulation structure composite film material.

[0056] Example 3

[0057] A heat-insulating microporous foam composite structural membrane utilizes a double-sided different coating process to achieve a corrosion-resistant PVC / PVDF membrane on the upper surface of the substrate layer, and a composite foaming resin is coated on the lower surface. The heat-insulating foam membrane material is obtained through integrated molding technology. The substrate layer is a fiber-reinforced resin-based composite sheet; the upper surface is composed of a PVC film, a polymer adhesive, and a PVDF film; the lower surface is composed of aerogel particles, PVC resin, a plasticizer, and a foaming agent.

[0058] The preparation method of the high-performance heat-insulating microporous foam composite structure film comprises the following steps:

[0059] (1) Surface modification of aramid fiber reinforced epoxy resin based composite sheets;

[0060] (2) applying a high-bonding PVC pre-coating layer on one side of the base fabric by a doctor blade coating process, and then applying a PVC layer on the PVC pre-coating layer;

[0061] (3) First apply a layer of acrylic adhesive with high bonding performance on the surface of the PVC coating, and then apply the PVDF coating;

[0062] (4) SiO2 aerogel particles were prepared by the sol-gel method and then surface modified with KH570. The mass ratio of SiO2 aerogel particles to KH570 was 1:2.5.

[0063] (5) The sulfonylhydrazide foaming agent and the modified SiO2 aerogel particles are uniformly dispersed in acetone at a mass ratio of 2:1, immersed at room temperature for 24 hours, and the supernatant is removed and filtered and dried to obtain SiO2 aerogel particles grafted with an azo foaming agent.

[0064] (6) PVC resin is mixed with the aerogel particles obtained in step (5), octyl stearate, and barium stearate in a mass ratio of 90:7:1.5:1.5 to form a foaming slurry, which is then applied to the fiber-reinforced resin-based composite sheet.

[0065] (7) The film is foamed in a high-temperature foaming furnace at 160°C and finally rolled up to obtain a thermal insulation structure composite film material.

[0066] Example 4

[0067] (1) Surface modification of glass fiber reinforced epoxy resin based composite sheets;

[0068] (2) applying a high-bonding PVC pre-coating layer on one side of the base fabric by a doctor blade coating process, and then applying a PVC layer on the PVC pre-coating layer;

[0069] (3) First apply a layer of acrylic adhesive with high bonding performance on the surface of the PVC coating, and then apply the PVDF coating;

[0070] (4) SiO2 aerogel particles were prepared by the sol-gel method and then surface modified with KH550. The mass ratio of SiO2 aerogel particles to KH550 was 1:1.5.

[0071] (5) The sulfonylhydrazide foaming agent and the modified SiO2 aerogel particles are uniformly dispersed in acetone at a mass ratio of 1:1, immersed at room temperature for 36 hours, and the supernatant is removed and filtered and dried to obtain SiO2 aerogel particles grafted with an azo foaming agent.

[0072] (6) PVC resin is mixed with the aerogel particles obtained in step (5), dioctyl adipate, and zinc stearate in a mass ratio of 94:3:2:1 to form a foaming slurry, which is then applied on a fiber-reinforced resin-based composite sheet.

[0073] (7) The film is foamed in a high-temperature foaming furnace at 165°C and finally rolled up to obtain a thermal insulation structure composite film material.

[0074] Example 5

[0075] (1) Surface modification of glass fiber reinforced epoxy resin based composite sheets;

[0076] (2) applying a high-bonding PVC pre-coating layer on one side of the base fabric by a doctor blade coating process, and then applying a PVC layer on the PVC pre-coating layer;

[0077] (3) First apply a layer of acrylic adhesive with high bonding performance on the surface of the PVC coating, and then apply the PVDF coating;

[0078] (4) SiO2 aerogel particles were prepared by the sol-gel method and then surface modified with KH570. The mass ratio of SiO2 aerogel particles to KH570 was 1:3.

[0079] (5) The azo foaming agent and the modified SiO2 aerogel particles are uniformly dispersed in DMF at a mass ratio of 1:1, immersed at room temperature for 24 hours, and the supernatant is removed and filtered and dried to obtain SiO2 aerogel particles grafted with the azo foaming agent.

[0080] (6) PVC resin is mixed with the aerogel particles obtained in step (5), dioctyl phthalate, and calcium stearate in a mass ratio of 87:10:2:1 to form a foaming slurry, which is then applied on a fiber-reinforced resin-based composite sheet.

[0081] (7) The film is foamed in a high-temperature foaming furnace at 150°C and finally rolled up to obtain a thermal insulation structure composite film material.

[0082] Comparative Example 1

[0083] (1) Surface modification of glass fiber reinforced vinyl resin based composite sheets;

[0084] (2) applying a high-bonding PVC pre-coating layer on one side of the base fabric by a doctor blade coating process, and then applying a PVC layer on the PVC pre-coating layer;

[0085] (3) First apply a layer of acrylic adhesive with high bonding performance on the surface of the PVC coating, and then apply the PVDF coating;

[0086] (4) PVC resin, azo foaming agent, dioctyl phthalate, and zinc stearate are mixed in a mass ratio of 90:6:2:2 to form a foaming slurry, which is then scraped onto a fiber-reinforced resin-based composite sheet.

[0087] (5) The film is foamed in a high-temperature foaming furnace at 135°C and finally rolled up to obtain a thermal insulation structure composite film material.

[0088] Comparative Example 2

[0089] A heat-insulating microporous foam composite structural membrane utilizes a double-sided coating process to achieve a corrosion-resistant PVC / PVDF membrane on the upper surface of the substrate layer, and a composite foaming resin coating on the lower surface. The heat-insulating foam membrane material is obtained through integrated molding technology. The invention is characterized in that: the substrate layer is a fiber-reinforced resin-based composite sheet; the upper surface is composed of a PVC film, a polymer adhesive and a PVDF film; and the lower surface is composed of aerogel particles, a PVC resin, a plasticizer and a foaming agent.

[0090] The preparation method of the high-performance heat-insulating microporous foam composite structure film comprises the following steps:

[0091] (1) Surface modification of glass fiber reinforced epoxy resin based composite sheets;

[0092] (2) coating a PVC layer on one side of the base fabric using a doctor blade coating process, and then coating the PVDF coating on the PVC coating;

[0093] (3) SiO2 aerogel particles were prepared by the sol-gel method and then surface modified with KH560. The mass ratio of SiO2 aerogel particles to KH560 was 1:2.

[0094] (4) The azo foaming agent and the modified SiO2 aerogel particles are uniformly dispersed in DMF at a mass ratio of 1:1, and then reacted at 80°C for 10 hours. After the reaction, the product is centrifuged and washed with ethanol to obtain SiO2 aerogel particles grafted with an azo foaming agent.

[0095] (5) PVC resin is mixed with the aerogel particles obtained in step (5), dioctyl terephthalate, and dibutyl tin maleate in a mass ratio of 90:6:2:2 to form a foaming slurry, which is then applied on a fiber-reinforced resin-based composite sheet.

[0096] (6) The film is foamed in a high-temperature foaming furnace at 135°C and finally rolled up to obtain a thermal insulation structure composite film material.

[0097] The cell data of the materials prepared in the examples and comparative examples were calculated, and the tear strength and tensile strength were tested according to national standards. The results are shown in the following table.

[0098]

[0099]

[0100] The difference between Examples 1 and 2 lies in the method of loading the aerogel particles with the foaming agent: the former uses a chemical method, while the latter uses a physical method. This shows that both loading methods can produce products with similar cell size and cell density and excellent performance.

[0101] The difference between Example 2 and Example 3 is that the proportion of the foaming agent in the aerogel impregnation is increased. The increase in the proportion does not significantly change the cell density, indicating that the loading amount of the foaming agent in Example 2 has reached the maximum value.

[0102] The difference between Example 1 and Examples 4 and 5 lies in the content of aerogel particles loaded with a foaming agent. As the content increases, the heterogeneous nucleation of the aerogel particles plays a leading role, the cell density increases, and the mechanical properties are improved.

[0103] The difference between Comparative Example 1 and Example 1 is that no aerogel particles are added, the cell density is reduced, and the mechanical properties are deteriorated.

[0104] The difference between Comparative Example 2 and Example 1 is that it is coated with a high-bonding PVC pre-coating and a high-bonding acrylic adhesive layer, which results in poor adhesion between the PVC coating and the base fabric, low firmness of the PVC coating and the PVDF coating, and significantly poorer tear strength of the material.

[0105] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A heat-insulating microporous foam composite structure membrane, which is obtained by using a double-sided coating process to achieve a corrosion-resistant PVC / PVDF membrane on the upper surface of the substrate layer and a composite foaming resin coating on the lower surface. The heat-insulating microporous foam composite structure membrane is obtained by an integrated molding process, characterized by: The substrate layer is a glass fiber or aramid fiber reinforced epoxy resin-based composite sheet; the corrosion-resistant PVC / PVDF membrane is composed of a PVC membrane, a polymer adhesive, and a PVDF membrane; the composite foaming resin is composed of aerogel particles, PVC resin, a plasticizer, a stabilizer, and a foaming agent; the aerogel particles are silica aerogel particles modified with a silane coupling agent; The plasticizer is one or more of dioctyl phthalate, dioctyl terephthalate, octyl stearate, or dioctyl adipate; The stabilizer is one or more of zinc stearate, calcium stearate, barium stearate, dibutyltin dilaurate or dibutyltin maleate; The foaming agent is an azo foaming agent or a sulfonylhydrazine foaming agent, or a mixture of the two.

2. The heat-insulating microporous foamed composite structure membrane according to claim 1, characterized in that: The polymer adhesive is an acrylic adhesive.

3. A method for preparing a heat-insulating microporous foamed composite structure film according to claim 1, characterized in that: The following steps are involved: S1. Preparation of PVC / aerogel particle composite foam material: S11, preparing SiO2 aerogel particles; S12, modifying SiO2 aerogel particles by using a silane coupling agent; S13, loading the modified SiO2 aerogel particles with a foaming agent by chemical grafting or impregnation; S14, mixing the loaded aerogel particles with PVC resin, plasticizer, and stabilizer to form a foaming slurry and coating the foaming slurry on the fiber-reinforced resin-based composite sheet; S2. Preparation of PVC / PVDF composite coating: S21, performing surface treatment on the base fabric using a surface modifier; S22, applying a high-bonding PVC pre-coating layer on one side of the base fabric; S23, coating a PVC layer on the PVC pre-coating layer; S24. First apply a layer of acrylic adhesive layer having high bonding performance with both PVDF and PVC film on the surface of the PVC coating, and then apply the PVDF coating.

4. The method for preparing a heat-insulating microporous foamed composite structure membrane according to claim 3, characterized in that: In the S11, ethyl orthosilicate, water, ethanol and a drying chemical control agent are placed in a reactor in a certain molar ratio, stirred evenly, and then a certain mass of fluorine-containing solution is added. After stirring for several minutes, a gel is formed and aged at room temperature for 12-24 hours. After the aging is completed, solvent replacement is performed, and the mixture is dried at a certain ambient temperature and finally crushed to obtain silica aerogel particles.

5. The method for preparing a heat-insulating microporous foamed composite structure membrane according to claim 4, characterized in that: In the S12, the silane coupling agent is one or more of KH550, KH570 or KH560.

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