Flexible interlayer foaming heat insulation composite material and preparation method thereof

Abstract

The invention relates to the technical field of composite materials, in particular to a flexible interlayer foaming heat insulation composite material and a preparation method thereof. A flexible interlayer foaming heat insulation composite material comprises a composite bottom blank layer and common PVC layers located on the two sides of the composite bottom blank layer, and the composite bottom blank layer sequentially comprises polyester fiber mesh cloth, the common PVC layers and a foaming PVC layer according to the coating sequence; the foamable PVC paste is prepared from the following components in parts by weight: 100 to 120 parts of PVC paste resin; 10 to 20 parts of a micron-sized nucleating agent; 70-90 parts of a plasticizer; 5-7 parts of a foaming agent; 3-4 parts of a stabilizer; and 5-10 parts of bonding resin. The sandwich structure design of the common PVC layers on the two sides and the composite bottom blank layer in the middle is adopted, the optimized foamable PVC paste formula is combined, the preparation technology of two-step heating, plasticizing and foaming is adopted, the cell structure is precisely regulated and controlled, the uniform and compact closed-cell foaming layer is formed, and the heat insulation performance is improved.

Description

Technical Field

[0001] This application relates to the field of composite materials technology, and in particular to a flexible sandwich foamed thermal insulation composite material and its preparation method. Background Technology

[0002] Outdoor semi-permanent structures, such as tents, awnings, and membrane structures, widely use polyester fiber mesh as the reinforcing base material, coated with polyvinyl chloride. Such materials need to have excellent flexibility, water resistance, weather resistance, and processability to meet the requirements of rapid assembly, disassembly, and long-term outdoor use.

[0003] With global warming and increased awareness of energy conservation, the market has put forward clear requirements for the thermal insulation performance of such materials. At present, the conventional approach to improve the thermal insulation performance of materials is to use integral foamed materials. Foamed plastics contain a large amount of air inside and have good thermal insulation performance. However, pure foamed materials are loose and have a rough surface, which makes them impossible to reliably weld and process, and cannot meet the basic construction requirements of outdoor building fabrics.

[0004] Therefore, how to develop a new type of composite material that can maintain the excellent processing performance of PVC polyester fiber coating materials and significantly improve their thermal insulation efficiency to obtain a thin-layer high thermal insulation has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] In order to improve thermal insulation performance without affecting the material's processing performance, this application provides a flexible sandwich foamed thermal insulation composite material and its preparation method.

[0006] In a first aspect, this application provides a flexible sandwich foamed thermal insulation composite material, which adopts the following technical solution: A flexible sandwich foamed thermal insulation composite material includes a composite substrate and ordinary PVC layers located on both sides of the composite substrate, wherein the ordinary PVC layers are formed by heating and plasticizing ordinary PVC paste; The composite substrate layer is coated in the following order: polyester fiber mesh, ordinary PVC layer and foamed PVC layer. The foamed PVC layer is made by heating and plasticizing a foamable PVC paste and then foaming it. The foamable PVC paste comprises, by weight: 100-120 parts of PVC paste resin; 10-20 parts of micron-sized nucleating agent; Plasticizer 70-90 parts; 5-7 parts foaming agent; Stabilizer 3-4 parts; 5-10 parts of adhesive resin.

[0007] By adopting the above technical solution, the polyester fiber mesh in the composite substrate layer serves as a structural reinforcement skeleton, playing a role in constraint and shaping during the foaming process, guiding the foamed layer to form a uniform and dense cell structure in the vertical direction, thereby ensuring the overall flexibility of the material; the ordinary PVC layer is made of ordinary PVC paste through heating and plasticization, playing a role in connecting the polyester fiber mesh and the foamed PVC layer as well as protecting the internal structure.

[0008] The foamed PVC layer is made by heating and plasticizing a foamable PVC paste with a specific formulation. The PVC paste resin is the matrix material, providing basic physical properties. Micron-level nucleating agents help control the foaming process, making the foaming more uniform and improving the thermal insulation performance.

[0009] Plasticizers increase the flexibility and processability of materials; foaming agents generate bubbles to form an insulating structure; stabilizers ensure the stability of materials during processing and use; and bonding resins enhance the adhesion between components, ensuring the structural stability of composite materials.

[0010] The ordinary PVC layers located on both sides of the composite substrate further protect the internal structure and also make the material surface smoother, which is convenient for subsequent processing and use. This structure can maintain the original excellent processing performance and mechanical strength, and significantly improve the thermal insulation efficiency.

[0011] Preferably, the micron-sized nucleating agent is an inorganic microparticle with an average particle size D50 ≤ 1 μm.

[0012] By adopting the above technical solution, inorganic microparticles with an average particle size of ≤1μm are used as micron-sized nucleating agents and uniformly dispersed in the paste, providing extremely rich heterogeneous nucleation sites. This guides the directional and uniform growth of the gas generated by the decomposition of the foaming agent, ultimately forming a closed-cell foam structure with small pore size and dense distribution, ensuring that the thermal insulation performance meets the standards.

[0013] Preferably, the inorganic particles are at least one of calcium carbonate, silicon dioxide, talc, or kaolin.

[0014] By adopting the above technical solution, using any one of the inorganic microparticles from calcium carbonate, silica, talc, or kaolin as a micron-level nucleating agent, it can better play a nucleating role in the foaming process, which helps the foamable PVC paste to form a uniform and dense cell structure, thereby improving the thermal insulation performance of the flexible sandwich foamed thermal insulation composite material.

[0015] Preferably, it also includes 1-2.5 parts of a composite activator, wherein the composite activator is composed of zinc oxide and aluminum stearate in a weight ratio of 1:(0.8-1.2).

[0016] By adopting the above technical solution, the composite activator formed by the combination of zinc oxide and aluminum stearate plays an activating role in the foaming process of foamable PVC paste, which helps to better form a foamed structure, thereby further improving the thermal insulation effect of the material.

[0017] Preferably, the plasticizer is selected from any one of tri(2-ethylhexyl) trimellitate, triisononyl trimellitate, and triisodecyl trimellitate.

[0018] By adopting the above technical solution and selecting high-temperature plasticizers of trimellitate, which have low volatility, migration resistance and heat resistance far superior to ordinary phthalate plasticizers, it is ensured that the foam layer structure will not harden, shrink or collapse due to plasticizer loss during long-term use, thereby maintaining the long-term stability of thermal insulation performance and material flexibility.

[0019] Preferably, the foaming agent is selected from any one of azodicarbonamide, sodium bicarbonate, and azobisisobutyronitrile.

[0020] By adopting the above technical solution, the specific types of foaming agents are identified, and the heating and plasticizing process of PVC paste is adapted to ensure the decomposition efficiency of the foaming agent and the stability of the gas source, forming a uniform foam cell structure, while taking into account the safety and cost controllability of the foaming agent.

[0021] Secondly, this application provides a method for preparing a flexible sandwich foamed thermal insulation composite material, which adopts the following technical solution: A method for preparing a flexible sandwich foamed thermal insulation composite material includes the following steps: S1. A layer of ordinary PVC paste and a layer of foamable PVC paste are sequentially coated on a polyester fiber mesh, and a first heat treatment is performed to plasticize the ordinary PVC paste and to plasticize and foam the foamable PVC paste to form a composite substrate layer. S2. Coat at least one layer of ordinary PVC paste on at least one side of the composite substrate and perform a second heating and plasticizing molding.

[0022] By adopting the above technical solution and using step-by-step coating and heating processes, the plasticizing and foaming processes of each layer are precisely controlled, ensuring the interfacial bonding force and structural integrity of the sandwich structure. This results in the composite material having good thermal insulation performance and a smooth surface, similar to ordinary PVC coating material, which facilitates processing and assembly. This achieves synergistic optimization of the composite material's thermal insulation and processing performance.

[0023] Preferably, in steps S1 and S2, the plasticizing and molding treatment temperature is 200-210℃, and the processing speed is 5-9 meters / minute.

[0024] By adopting the above technical solution, controlling the processing temperature and speed during the preparation of flexible sandwich foamed thermal insulation composite materials can fully plasticize ordinary PVC paste and fully plasticize and foam foamable PVC paste. This is beneficial for preparing flexible sandwich foamed thermal insulation composite materials with good foaming effect, stable quality and smooth surface, thus enabling them to have thermal insulation effect.

[0025] Thirdly, this application provides a foamable PVC paste.

[0026] A foamable PVC paste, comprising, by weight: 100-120 parts PVC paste resin; 10-20 parts micron-sized nucleating agent; 70-90 parts plasticizer; 5-7 parts foaming agent; 3-4 parts stabilizer; and 5-10 parts adhesive resin.

[0027] By adopting the above technical solution, the foamable PVC paste can form a foam pore structure with small pore size and uniform distribution after heating, plasticizing and foaming, so that the flexible sandwich foamed thermal insulation composite material has a good thermal insulation effect.

[0028] In summary, this application has the following beneficial effects: 1. Because this application rationally combines polyester fiber mesh, ordinary PVC layer and foamed PVC layer, the outer ordinary PVC layer ensures the flatness of the material surface, which is convenient for processing and construction, and also protects the internal structure. The middle foamed PVC layer utilizes the synergistic effect of the components in the foamable PVC paste to form a porous heat insulation structure, which effectively reduces the thermal conductivity of the material and achieves a good heat insulation effect. 2. This application adopts a step-by-step coating and step-by-step heating process to precisely control the plasticizing and foaming process of each layer, ensuring the interfacial bonding force and structural integrity of the sandwich structure, so that the composite material has good thermal insulation effect and achieves synergistic optimization of the thermal insulation and processing performance of the composite material. 3. This application involves heating and plasticizing a foamable PVC paste to form a uniform and dense closed-cell structure, which is suitable for preparing the core insulation layer of flexible thermal insulation composite materials. Detailed Implementation

[0029] The present application will be further described in detail below with reference to the embodiments.

[0030] Performance testing 1. Thermal insulation performance According to the standard EN 12664:2001, the thermal conductivity of the composite material prepared by this invention is tested and the target thermal conductivity value is less than or equal to 0.04 W / (mk).

[0031] 2. Machinability (1) According to EN ISO 2411, the peel strength between the ordinary PVC layer and the foamed PVC layer is tested. The present invention requires an interlayer peel strength ≥80 N / 5cm; (2) The cross-section of the sample was prepared by liquid nitrogen brittle fracture method, observed under 100x magnification using a digital video microscope, and the thickness of the foam layer was directly measured using image analysis software. The result was the average of three measurements.

[0032] Examples 1-3 A flexible sandwich foamed thermal insulation composite material, the components and amounts of its raw materials are shown in Table 1 (kg) below, and it is prepared using the following steps: S1. A layer of ordinary PVC paste and a layer of foamable PVC paste are sequentially coated on a polyester fiber mesh. The first heat treatment is carried out at 205°C and 7 m / min to plasticize the ordinary PVC paste and to plasticize and foam the foamable PVC paste to form a composite substrate. S2. Two layers of ordinary PVC paste are coated on both sides of the composite substrate, and a second heating and plasticizing molding is carried out at 205°C and 7 m / min.

[0033] The polyester fiber mesh is 0.15 mm thick, and the ordinary PVC layer is 0.1 mm thick.

[0034]

[0035] In the table above, the PVC paste resin grade is P-450, which was purchased from Wuhan Jiyesheng Chemical Co., Ltd. The micron-sized nucleating agent is an inorganic microparticle, which is calcium carbonate, with an average particle size of 1 μm. The plasticizer is tri(2-ethylhexyl) trimellitate; The foaming agent is azodicarbonamide; The bonding resin is epoxy resin, brand name E51, purchased from Jinan Chuangshi Chemical Co., Ltd.

[0036] Comparative Example 1 A flexible sandwich foamed thermal insulation composite material differs from Example 1 in that it does not contain micron-level nucleating agents, and its proportion is supplemented by PVC paste resin.

[0037] Test samples corresponding to Examples 1-3 and Comparative Example 1 were extracted and tested according to the aforementioned performance testing method. The thermal conductivity and peel strength of ordinary PVC layer and foamed PVC layer were measured respectively, and the average value of the test results was recorded in Table 2 below.

[0038]

[0039] As can be seen from Table 2, the flexible sandwich foamed thermal insulation composite material in Examples 1-3 has a thermal conductivity of 0.037-0.040 W / (mk), a peel strength of 82-88 N / 5cm, and a foaming thickness of 0.65-0.72 mm. The resulting composite material is relatively thin, has strong interfacial bonding force, and exhibits excellent thin-layer high thermal insulation performance and processability.

[0040] However, Comparative Example 1, which did not add micron-level nucleating agent, had a foam layer thickness of 0.35 mm, which was significantly lower than that of Examples 1-3. Its thermal conductivity was as high as 0.095 W / (m・k), and its peel strength was only 48 N / 5cm. Its thermal insulation effect and processability were significantly inferior to those of Examples 1-3.

[0041] The possible reasons are as follows: Micron-sized nucleating agents disperse in PVC paste to form a large number of uniform nucleation sites. On the one hand, this guides the gas from the decomposition of the foaming agent to aggregate and grow in a directional manner, forming a closed-cell foam structure with small pore size, dense distribution, and complete structure. This seals in still air and blocks heat conduction, thereby significantly reducing the thermal conductivity of the composite material and improving its thermal insulation performance. On the other hand, as inorganic rigid microparticles, this optimizes the coating leveling properties of the PVC paste, thereby enhancing the interfacial bonding force of the layer structure, increasing the peel strength, and ensuring the structural stability and processability of the composite material.

[0042] In Comparative Example 1, due to the lack of micron-sized nucleating agents, the decomposition gas of the foaming agent could not effectively nucleate and grow stably. After the gas polymerized, it formed a coarse open-pore structure, which caused a large amount of gas to escape from the paste and fail to effectively participate in the construction of the foam. Its physical thickness was also significantly reduced due to the gas escape, resulting in a decrease in thermal insulation performance and processability.

[0043] Examples 4-5 A flexible sandwich foamed thermal insulation composite material differs from Example 1 in that the average particle size of calcium carbonate is different. Test samples corresponding to Examples 4-5 were extracted and tested according to the aforementioned performance testing methods. The thermal conductivity and peel strength of the ordinary PVC layer and the foamed PVC layer were measured respectively, and the average test results were recorded in Table 3 below.

[0044]

[0045] Combining Examples 4-5 and Example 1 with Table 3, it can be seen that the thermal conductivity ranges from 0.038 to 0.040 W / (mk), the peel strength ranges from 80 to 84 N / 5cm, and the foam layer thickness is 0.64 to 0.66 mm. All indicators show excellent performance, demonstrating high thermal insulation performance in a thin layer. At the same time, the reliable interlayer bonding performance provides a strong guarantee for processability.

[0046] In Example 4, the best performance was achieved when the calcium carbonate particle size was 0.5 μm. The thermal conductivity was reduced by 0.002 W / (mk) compared to Example 1, the peel strength was increased by 2 N / 5 cm, and the foam layer thickness was 0.66 mm. In Example 5, when the calcium carbonate particle size was 2 μm, the peel strength was reduced by 2 N / 5 cm compared to Example 1 and by 4 N / 5 cm compared to Example 4. The foam layer thickness was 0.64 mm, but it still met the requirements stably.

[0047] Examples 6-8 A flexible sandwich foamed thermal insulation composite material differs from Example 1 in that the selection of inorganic microparticles is different. Test samples corresponding to Examples 6-8 were extracted and tested according to the aforementioned performance testing methods. The thermal conductivity and peel strength of the ordinary PVC layer and the foamed PVC layer were measured respectively, and the average value of the test results was recorded in Table 4 below.

[0048]

[0049] As can be seen from Table 4, the thermal conductivity of Examples 6-8 is 0.038-0.039 W / (mk), the peel strength is 82-83 N / 5cm, and the foam layer thickness is 0.65-0.67 mm. The performance difference from Example 1 is small, and all indicators are excellent, showing excellent thin-layer high thermal insulation performance. At the same time, the reliable interlayer bonding performance and the thin foam layer thickness provide a strong guarantee for processability.

[0050] Examples 9-11 A flexible sandwich foamed thermal insulation composite material differs from Example 1 in that it also includes 1-2.5 parts of a composite activator, the amount of which (kg) is shown in Table 5 below.

[0051]

[0052] The composite activator is composed of zinc oxide and aluminum stearate in a weight ratio of 1:1.

[0053] Test samples corresponding to Examples 9-11 above were extracted and tested according to the aforementioned performance testing methods. The thermal conductivity and peel strength of ordinary PVC layer and foamed PVC layer were measured respectively, and the average value of the test results was recorded in Table 6 below.

[0054]

[0055] As can be seen from Table 6, the flexible sandwich foamed thermal insulation composite materials prepared in Examples 9-11 have a thermal conductivity of 0.036-0.038 W / (mk), a peel strength of 85-87 N / 5cm, and a foaming thickness of 0.67-0.70 mm. Examples 9-11 are all superior to Example 1 without the addition of the composite activator. This proves that the composite activator can effectively activate the foaming process and optimize the interfacial bonding, and the proportion range specified in this application has good performance compatibility.

[0056] Examples 12-13 A flexible sandwich foamed thermal insulation composite material differs from Example 10 in that the weight ratio of zinc oxide to aluminum stearate is different. Test samples corresponding to Examples 12-13 were extracted and tested according to the aforementioned performance testing methods. The thermal conductivity and peel strength of the ordinary PVC layer and the foamed PVC layer were measured, and the average test results were recorded in Table 7 below.

[0057]

[0058] Combining Examples 12-13 and Example 10 with Table 7, it can be seen that the thermal conductivity ranges from 0.036 to 0.037 W / (mk), the peel strength ranges from 87 to 89 N / 5cm, and the foam thickness is 0.68 to 0.70 mm. All indicators show excellent performance, demonstrating superior thin-layer high thermal insulation performance. At the same time, the reliable interlayer bonding performance and the thin foam layer thickness provide a strong guarantee for processability. Among them, Example 10 has the best performance in terms of thermal conductivity (0.036 W / (mk), peel strength (89 N / 5cm), and foam thickness (0.70 mm), indicating that the optimal weight ratio of zinc oxide to aluminum stearate is 1:1.

[0059] Examples 14-15 A flexible sandwich foamed thermal insulation composite material differs from Example 1 in that it uses a different type of plasticizer. Test samples corresponding to Examples 14-15 were extracted and tested according to the aforementioned performance testing methods. The thermal conductivity and peel strength of the ordinary PVC layer and the foamed PVC layer were measured, and the average test results were recorded in Table 8 below.

[0060]

[0061] Combining Examples 14-15 and Example 1 with Table 8, it can be seen that the thermal conductivity ranges from 0.038 to 0.040 W / (mk), the peel strength ranges from 82 to 84 N / 5cm, and the foam layer thickness is 0.65 to 0.67 mm. All indicators show excellent performance, fully demonstrating the material's outstanding thermal insulation performance and exhibiting excellent thin-layer high thermal insulation performance. At the same time, the reliable interlayer bonding performance and the relatively thin foam layer thickness provide a strong guarantee for processability, indicating that the material performance differences corresponding to different types of trimellitate plasticizers are small.

[0062] Examples 16-17 A flexible sandwich foamed thermal insulation composite material differs from Example 1 in that it uses a different type of foaming agent. Test samples corresponding to Examples 16-17 were extracted and tested according to the aforementioned performance testing methods. The thermal conductivity and peel strength of the ordinary PVC layer and the foamed PVC layer were measured, and the average test results were recorded in Table 9 below.

[0063]

[0064] Combining Examples 16-17 and Example 1 with Table 9, it can be seen that the thermal conductivity ranges from 0.037 to 0.040 W / (mk), the peel strength ranges from 82 to 84 N / 5cm, and the foam layer thickness is 0.65 to 0.71 mm. All indicators show excellent performance, demonstrating excellent thin-layer high thermal insulation performance. At the same time, the reliable interlayer bonding performance and the thin foam layer thickness provide a strong guarantee for processability. Among them, Example 17 has the best performance in all aspects, with a thermal conductivity of 0.037 W / (mk), a peel strength of 84 N / 5cm, and a foam layer thickness of 0.71 mm. Therefore, azobisisobutyronitrile (AIBN) is the optimal foaming agent in this experiment.

[0065] Example 18

[0066] A flexible sandwich foamed thermal insulation composite material differs from Example 1 in that the processing temperature in S1 and S2 is 200°C and the processing speed is 5 meters / minute.

[0067] Example 19

[0068] A flexible sandwich foamed thermal insulation composite material differs from Example 1 in that the processing temperature in S1 and S2 is 210°C and the processing speed is 9 meters / minute.

[0069] Test samples corresponding to Examples 18-19 above were extracted and tested according to the aforementioned performance testing methods. The thermal conductivity and peel strength of ordinary PVC layer and foamed PVC layer were measured respectively, and the average value of the test results was recorded in Table 10 below.

[0070]

[0071] As shown in Table 10, the composite materials prepared in Examples 18-19 have a thermal conductivity of 0.039-0.040 W / (m·k), a peel strength of 81-83 N / 5cm, and a foam layer thickness of 0.66-0.70 mm. All indicators are excellent. The test results show that the material has a low thermal conductivity, high interlayer peel strength, and maintains a relatively thin overall thickness, successfully achieving a balance between thin-layer high thermal insulation and good processability.

[0072] The above data shows that 200-210℃ is the suitable temperature range for plasticizing PVC paste and decomposing foaming agent, while the processing speed of 5-9m / min can ensure that the material has sufficient heating and reaction time during continuous production, avoiding performance defects caused by excessively fast processing. This proves that the process parameter range of this technology has good compatibility and can be flexibly adjusted according to the needs of industrial production.

[0073] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A flexible sandwich foamed thermal insulation composite material, characterized in that, It includes a composite substrate layer and ordinary PVC layers located on both sides of the composite substrate layer, wherein the ordinary PVC layers are formed by heating and plasticizing ordinary PVC paste; The composite substrate layer is coated in the following order: polyester fiber mesh, ordinary PVC layer and foamed PVC layer. The foamed PVC layer is made by heating and plasticizing a foamable PVC paste and then foaming it. The foamable PVC paste comprises, by weight: 100-120 parts of PVC paste resin; 10-20 parts of micron-sized nucleating agent; Plasticizer 70-90 parts; 5-7 parts foaming agent; Stabilizer 3-4 parts; 5-10 parts of adhesive resin.

2. The flexible sandwich foamed thermal insulation composite material according to claim 1, characterized in that, The micron-sized nucleating agent is an inorganic microparticle with an average particle size ≤1μm.

3. The flexible sandwich foamed thermal insulation composite material according to claim 2, characterized in that, The inorganic particles are at least one of calcium carbonate, silicon dioxide, talc, or kaolin.

4. The flexible sandwich foamed thermal insulation composite material according to claim 1, characterized in that, It also includes 1-2.5 parts of a composite activator, which is composed of zinc oxide and aluminum stearate in a weight ratio of 1:(0.8-1.2).

5. The flexible sandwich foamed thermal insulation composite material according to claim 1, characterized in that, The plasticizer is selected from any one of tri(2-ethylhexyl) trimellitate, triisononyl trimellitate, and triisodecyl trimellitate.

6. The flexible sandwich foamed thermal insulation composite material according to claim 1, characterized in that, The foaming agent is selected from any one of azodicarbonamide, sodium bicarbonate, and azobisisobutyronitrile.

7. The method for preparing the flexible sandwich foamed thermal insulation composite material according to any one of claims 1-6, characterized in that, Includes the following steps: S1. A layer of ordinary PVC paste and a layer of foamable PVC paste are sequentially coated on a polyester fiber mesh, and a first heat treatment is performed to plasticize the ordinary PVC paste and to plasticize and foam the foamable PVC paste to form a composite substrate layer. S2. Coat at least one layer of ordinary PVC paste on at least one side of the composite substrate and perform a second heat-plasticizing molding.

8. The method for preparing the flexible sandwich foamed thermal insulation composite material according to claim 7, characterized in that, In steps S1 and S2, the plasticizing and molding process temperature is 200-210℃, and the processing speed is 5-9 meters / minute.

9. A foamable PVC paste, characterized in that, By weight, it includes: 100-120 parts PVC paste resin; 10-20 parts micron-sized nucleating agent; 70-90 parts plasticizer; 5-7 parts foaming agent; 3-4 parts stabilizer; and 5-10 parts adhesive resin.

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