Fiber / powder composite VIP core material based on DLP technology and preparation method and application thereof

Abstract

The invention discloses a fiber / powder composite VIP core material based on a DLP technology and a preparation method and application thereof, and belongs to the technical field of vacuum insulation panel manufacturing. The preparation method of the core material comprises the following steps: (1) uniformly stirring and mixing glass fibers, gas-phase SiO2 powder, light-cured resin, a dispersing agent and a photoinitiator to obtain a printing material; (2) printing a fiber / powder composite VIP core material by adopting the printing material in the step (1) according to a three-dimensional model of a preset structure, drying and cooling; and (3) putting the core material in the step (2) into a barrier film, adding a getter, and packaging to obtain the product. The method has the beneficial effects that solid-phase heat conduction can be effectively reduced through elaborately optimized material composition and structural design, particularly fiber directional layered arrangement which is beneficial to realization based on a DLP printer, and fiber pores can be further filled after gas-phase SiO2 is compounded. The heat conductivity of the VIP can be reduced to 0.0025-0.0035 W / (m.K) by combining the synergistic effect of all the components, and is remarkably improved compared with that of traditional VIP.

Description

Technical Field

[0001] The present invention relates to the technical field of vacuum insulation panel manufacturing, and in particular to a fiber / powder composite VIP core material based on DLP technology, and a preparation method and application thereof. Background Art

[0002] As a highly efficient thermal insulation material, vacuum insulation panels (VIP) have broad application prospects in many fields with strict requirements on thermal insulation performance, such as cold chain logistics, building energy conservation, aerospace, etc. Its basic principle is to achieve excellent thermal insulation effect by vacuum sealing thermal insulation core materials such as fibers, powders, and foams in a barrier film, based on macro-control of three heat transfer modes: heat conduction, heat convection, and heat radiation. However, the traditional VIP core material preparation method has obvious limitations in practical applications.

[0003] In terms of structural design and preparation, it is difficult for traditional processes to achieve precise control of the microstructure of the core material, and it is impossible to design and prepare core materials with specific pore structures, fiber distributions, and external dimensions according to different usage scenarios and thermal requirements, resulting in poor adaptability and versatility of the product. For example, in some occasions with special requirements for thermal insulation and mechanical properties, such as the thermal insulation layer of high-temperature and high-pressure equipment or the thermal insulation sleeve of a cryogenic container with a complex shape, the traditional VIP structure cannot meet its requirements for structural refinement. In addition, the traditional process is not precise enough in controlling the thickness of the VIP core material, which will directly affect the thermal insulation performance and overall dimensional accuracy of the VIP. In some application scenarios with strict space requirements, such as the thermal insulation packaging of precision instruments or thermal insulation facilities in a small space, thickness deviations may lead to failure to install or use normally, which seriously limits the scope of application of VIP.

[0004] In terms of core material molding and VIP preparation, traditional processes cannot guarantee high-quality core material molding and long-lasting VIP preparation. It is known that ultra-fine glass fiber core material VIP is the application-oriented product with the lowest thermal conductivity and the most mature preparation process among the existing VIPs, but it is highly dependent on the vacuum environment. With the influence of external conditions and the aging of the barrier film itself, it is easy to cause leakage in the vacuum environment, resulting in the loss of its thermal insulation performance. Some scholars have proposed fiber / powder composite core materials, which further regulate the fiber pore size by introducing powder particles, thereby reducing its air pressure sensitivity to achieve the purpose of extending its service life. However, in the process of mixing fibers and powders, due to the lack of effective mixing means and process control conditions, the fibers and powders are often not fully and evenly mixed together. This will not only affect the overall thermal insulation performance of the core material, but also lead to the unevenness of the internal structure of the material, making the core material prone to local thermal bridges during use, reducing the reliability of the product. In addition, uneven mixing may also cause powder loss, and the powder that falls out may affect the packaging quality of the VIP and further weaken its service life.

[0005] Digital Light Processing (DLP) additive manufacturing technology, as an advanced 3D printing technology, uses digital micromirror devices to project light onto the surface of liquid photocurable resin, so that the resin is cured layer by layer. This technology has the characteristics of high precision, high resolution and the ability to achieve rapid prototyping of complex structures. It has been widely used in many industrial manufacturing and scientific research fields and has achieved remarkable results. In view of its unique advantages in material molding, combined with diversified structural design and digital projection printing technology, it provides a new technical idea for the preparation of VIP core materials.

[0006] The Chinese patent application document with publication number CN102942305A discloses a method for preparing a new type of mineral wool VIP core material, comprising the following steps: 1) adding rock wool fibers to a deflaking machine, then adding sulfuric acid and clean water to disperse the rock wool fibers to a diameter of less than 1.5 μm; then sending the dispersed rock wool fibers to a storage stirring tank, and then adding sulfuric acid and clean water to adjust the pH value to 3.5-4.5 and the mass concentration to 3%-4% slurry; 2) diluting the slurry obtained in step 1) to a mass concentration of 0.2%-0.4%, and then performing a slag removal treatment; then conveying the slurry to an inclined mesh former for wet forming to obtain wet paper; then suction dehydrating the wet paper under a vacuum degree of 0.01-0.05 MPa; 3) drying the wet paper obtained in step 2) at 200-300°C. However, the thermal conductivity of the VIP core material prepared by this patent is poor, so it needs to be further improved. Summary of the invention

[0007] The technical problem to be solved by the present invention is how to solve the problem of poor performance of existing vacuum insulation panel (VIP) core materials.

[0008] The present invention solves the above technical problems through the following technical means:

[0009] The first aspect of the present invention provides a method for preparing a fiber / powder composite VIP core material based on DLP technology, comprising the following steps:

[0010] (1) Glass fiber, gas phase SiO 2 The powder, the photocurable resin, the dispersant and the photoinitiator are stirred and mixed to obtain a printing material;

[0011] (2) According to the three-dimensional model of the preset structure, the fiber / powder composite VIP core material is printed using the printing material in (1), and then dried and cooled;

[0012] (3) The core material in (2) is placed in a barrier film, and a getter is added, and then encapsulated to obtain the product.

[0013] Preferably, in step (1), the glass fiber, gas-phase SiO 2 The volume ratio of powder, photocurable resin, dispersant and photoinitiator is: (28-32): (53-55): (13-17): (1-1.5): (2.5-3.5).

[0014] Preferably, the glass fiber has a length of 4 to 10 mm and a diameter of 4 to 12 μm.

[0015] Preferably, the gas phase SiO 2 The particle size of the powder is 8 to 25 nm.

[0016] Preferably, the photocurable resin is an acrylic photocurable resin, specifically selected from any one of HEA, HDDA, and TMPTA.

[0017] Preferably, the dispersant is selected from any one of CPD01, CPD02, and CPD03.

[0018] Preferably, the photoinitiator is selected from any one of CPI01, CPI06 and TPO.

[0019] Preferably, in step (1), the stirring speed is 50 to 200 r / min, and the stirring time is 4 to 10 h.

[0020] Preferably, in step (2), when printing, the wavelength of the light source is 385nm and the light intensity is 12-16mW / cm 2 , the exposure time is 1.8~2.5s, and the printing layer thickness is 40μm~50μm.

[0021] Preferably, the drying temperature is 90-110° C., and the drying time is 5-12 hours.

[0022] Preferably, a gap of 2 to 3 mm is reserved between the barrier film and the core material, and the gap is filled with polyurethane foam particle cushioning material.

[0023] Preferably, the barrier film is a composite aluminum-plastic film or a polyimide film.

[0024] The second aspect of the present invention provides a fiber / powder composite VIP core material obtained by the above preparation method.

[0025] The third aspect of the present invention proposes the use of the above-mentioned fiber / powder composite VIP core material as a thermal insulation material in the field of thermal insulation.

[0026] The beneficial effects of the present invention are:

[0027] 1. The present invention proposes a fiber / powder composite VIP core material based on DLP technology, including glass fiber, gas phase SiO 2 Powder, light-curing resin, dispersant, photoinitiator components, glass fiber with small diameter and short length, helps to extend the solid phase heat transfer path, thereby reducing the thermal conductivity; gas phase SiO 2 The characteristics of high porosity and low thermal conductivity help to improve the thermal insulation performance of the core material. Through carefully optimized material composition and structural design, the directional layered arrangement of fibers achieved by DLP printer can effectively reduce solid-phase heat conduction. The synergistic effect among the various components improves the performance of the VIP core material, making the thermal conductivity of VIP as low as 0.0025~0.0035W / (m·K), which is significantly improved compared with traditional VIP.

[0028] 2. The core material of the present invention has good compressive strength and thickness controllability. The structural design of the composite core material and the synergistic effect of the fiber and the resin give the composite core material good compressive strength and can withstand external pressures of 2 to 4 MPa. (Compared with traditional materials, fiber core materials: 0.1 to 0.5 MPa, powder core materials: 0.2 to 0.8 MPa, foam core materials: 0.3 to 1.2 MPa) At the same time, the thickness of the core material can be accurately controlled by DLP printing technology, which can be adjusted within the range of 8 to 20 mm according to actual needs, and no significant volume shrinkage occurs during the vacuum process.

[0029] 3. The core material of the present invention has a long service life. Based on the DLP technology, it can realize the preparation of fiber / powder composite core materials with controllable density. The pore size printing accuracy can reach 5μm. At the same time, it has good compressive strength, so it shows extremely low air pressure sensitivity. The thermal conductivity coefficient does not change much after vacuum leakage, which effectively improves the service life of VIP and can achieve long-term service of more than 80 years.

[0030] 4. Customized core material structure design. Based on DLP technology, fiber / powder composite core material VIP with different pore structures, fiber distribution and external dimensions can be designed and prepared according to different application scenarios and thermal requirements to meet diverse market needs and improve product adaptability and competitiveness. DLP layered printing technology is conducive to the layered and directional distribution of fibers inside the core material, especially the horizontal arrangement, which significantly reduces solid-phase heat conduction and greatly improves the thermal insulation performance of VIP.

[0031] 5. The fiber / powder composite core material VIP based on DLP technology provided by the present invention effectively overcomes the problems of uncontrollable process, uncontrollable thickness, uncontrollable structure, etc. in traditional VIP preparation technology, and provides a new solution for long-lasting and diversified VIP manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of the structure of the fiber / powder composite VIP core material in Example 1 of the present invention; wherein 1 is a barrier film, 2 is a fiber / powder composite core material, and 3 is a getter;

[0033] Figure 2 The three-dimensional model diagram of the core material preset in Example 1 of the present invention;

[0034] Figure 3 The three-dimensional model diagram of the core material preset in Example 2 of the present invention;

[0035] Figure 4 The three-dimensional model diagram of the core material preset in Example 3 of the present invention;

[0036] Figure 5 This is a three-dimensional model diagram of the core material preset in Example 4 of the present invention. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] Unless otherwise specified, the test materials and reagents used in the following examples can be obtained from commercial sources.

[0039] If no specific techniques or conditions are specified in the examples, they can be carried out according to the techniques or conditions described in the literature in the art or according to the product instructions.

[0040] Experimental Example 1:

[0041] A method for preparing a fiber / powder composite VIP core material based on DLP technology comprises the following steps:

[0042] (1) Using an anchor-type stirring paddle, glass fiber (length 6 mm, diameter 6 μm), gas-phase SiO 2 The powder (particle size 12 nm), photocurable resin (HEA), dispersant (CPD01), and photoinitiator (CPI01) were mixed in a volume ratio of 30:55:14:1.2:3.5, and the mixing was thorough and uniform to obtain the printing material; the speed of the stirring paddle was controlled at 100 r / min for 8 hours;

[0043] (2) According to the preset core material three-dimensional model ( Figure 2 The wavelength of the light source is 385nm and the light intensity is 13mW / cm 2 , exposure time is 2s, printing layer thickness is 40μm; the printed fiber / powder composite core material is placed in an oven, heated to 100℃, kept warm for 8h; then cooled naturally to room temperature;

[0044] (3) Place the core material in (2) into a composite aluminum-plastic barrier film and add a getter; leave a gap of 3 mm between the barrier film and the core material, and fill the gap with polyurethane foam particle cushioning material, use vacuum packaging equipment to package, deeply evacuate the air to reduce the internal pressure to 0.001 Pa, the evacuation rate is 5 L / s, and the pressure is maintained for 2 h to obtain a composite aluminum-plastic film fiber / powder composite VIP core material.

[0045] Experimental Example 2:

[0046] A method for preparing a fiber / powder composite VIP core material based on DLP technology comprises the following steps:

[0047] (1) Using an anchor-type stirring paddle, glass fiber (length 7 mm, diameter 6 μm), gas-phase SiO 2 Powder (particle size 10 nm), photocurable resin (HEA), dispersant (CPD02), and photoinitiator (CPI06) were mixed in a volume ratio of 32:50:14:1.2:2.8, and stirred thoroughly to obtain printing materials; the speed of the stirring paddle was controlled at 150 r / min for 6 hours;

[0048] (2) According to the preset core material three-dimensional model ( Figure 3 The wavelength of the light source is 385nm and the light intensity is 15mW / cm 2 , the exposure time is 2.5s, and the printing layer thickness is 50μm; the printed fiber / powder composite core material is placed in an oven, heated to 110℃, and kept warm for 5h; then naturally cooled to room temperature;

[0049] (3) Place the core material in (2) into a polyimide barrier film and add a getter; leave a 2 mm gap between the barrier film and the core material and fill the gap with a polyurethane foam particle cushioning material; use a vacuum packaging device to package, deeply evacuate the air to reduce the internal pressure to 0.001 Pa, at a evacuation rate of 5 L / s, and maintain the pressure for 3 h to obtain a polyimide film fiber / powder composite VIP core material.

[0050] Comparative Example 1:

[0051] Commercially available ultra-fine glass fiber VIP core material.

[0052] Comparative Example 2:

[0053] Commercially available fumed silica VIP core material.

[0054] Comparative Example 3:

[0055] Commercially available polyurethane foam VIP core material.

[0056] The material properties of Example 1 and Example 2 were tested, and the specific testing method was as follows:

[0057] (1) Thermal conductivity

[0058] Use NETZSCH HFM446 thermal conductivity tester as the test equipment, prepare VIP samples with the size of 300*300*10mm, place the preheated VIP samples in the test area of ​​the instrument, make them fit tightly on the heat flow sensor and temperature sensor, and pay attention to avoid air gaps between the sample and the sensor to avoid affecting the measurement results. Set relevant test parameters through the instrument's operation interface. For VIP, the hot plate temperature can usually be set between 20℃ and 50℃, and the cold plate temperature can be set between 0℃ and 20℃ to form a suitable temperature difference. After confirming that the parameter settings are correct, start the measurement. When the measurement system reaches a stable state, the thermal conductivity of VIP is obtained.

[0059] (2) Compressive strength

[0060] Use a universal mechanical testing machine as the testing equipment, prepare a VIP sample with a size of 10*10*5mm, place it between the upper and lower pressure plates of the universal mechanical testing machine, adjust the position of the pressure plate so that it contacts the sample evenly, set the loading rate, generally 0.5-1mm / min, start the equipment, and observe the real-time changes in the pressure value during the loading process. When the sample ruptures or the pressure value changes drastically, record the pressure value at this time, and calculate the compressive strength by dividing the pressure value by the force-bearing area of ​​the sample. The test process needs to be carried out under standard ambient temperature and humidity conditions to ensure the accuracy and reliability of the test results.

[0061] (3) Service life

[0062] Refer to GB / T 37608-2019 Vacuum Insulation Panel Appendix E Vacuum Insulation Panel Service Life Assessment Method A.

[0063] The test results are shown in Table 1 below:

[0064] Table 1

[0065] Thermal conductivity / W / (m·K) Compressive strength / MPa Service life / year Example 1 0.0035 2.7 80 Example 2 0.0025 3.2 82 Comparative Example 1 0.002 0.2 30 Comparative Example 2 0.006 0.7 50 Comparative Example 3 0.008 0.2 30

[0066] Embodiment 3:

[0067] A method for preparing a fiber / powder composite VIP core material based on DLP technology comprises the following steps:

[0068] (1) Using an anchor-type stirring paddle, glass fiber (length 4 mm, diameter 12 μm), gas-phase SiO 2 The powder (particle size 8 nm), photocurable resin (HDDA), dispersant (CPD03), and photoinitiator (TPO) were mixed in a volume ratio of 28:53:17:1.5:2.5, and the printing material was obtained. The speed of the stirring paddle was controlled at 50 r / min for 10 h.

[0069] (2) According to the preset core material three-dimensional model ( Figure 4 The wavelength of the light source is 385nm and the light intensity is 12mW / cm 2 , the exposure time is 1.8s, and the printing layer thickness is 45μm; the printed fiber / powder composite core material is placed in an oven, heated to 90℃, and kept warm for 12h; then naturally cooled to room temperature;

[0070] (3) Place the core material in (2) into a composite aluminum-plastic barrier film and add a getter; leave a gap of 2.5 mm between the barrier film and the core material, and fill the gap with polyurethane foam particle cushioning material, use vacuum packaging equipment to package, deeply evacuate the air to reduce the internal pressure to 0.001 Pa, the evacuation rate is 5 L / s, and the pressure is maintained for 2 h to obtain a composite aluminum-plastic film fiber / powder composite VIP core material.

[0071] Embodiment 4:

[0072] A method for preparing a fiber / powder composite VIP core material based on DLP technology comprises the following steps:

[0073] (1) Using an anchor-type stirring paddle, glass fiber (length 10 mm, diameter 4 μm), gas-phase SiO 2 The powder (particle size 25 nm), photocurable resin (TMPTA), dispersant (CPD03), and photoinitiator (TPO) were mixed in a volume ratio of 30.5:54.2:15.5:1.4:2.6, and the printing material was obtained. The speed of the stirring paddle was controlled at 200 r / min for 4 hours.

[0074] (2) According to the preset core material three-dimensional model ( Figure 5 The wavelength of the light source is 385nm and the light intensity is 16mW / cm 2 , the exposure time is 1.8s, and the printing layer thickness is 48μm; the printed fiber / powder composite core material is placed in an oven, heated to 90℃, and kept warm for 12h; then naturally cooled to room temperature;

[0075] (3) Place the core material in (2) into a composite aluminum-plastic barrier film and add a getter; leave a gap of 2.6 mm between the barrier film and the core material, and fill the gap with polyurethane foam particle cushioning material, use vacuum packaging equipment to package, deeply evacuate the air to reduce the internal pressure to 0.001 Pa, the evacuation rate is 5 L / s, and the pressure is maintained for 2 h to obtain a composite aluminum-plastic film fiber / powder composite VIP core material.

[0076] The performance of the core materials prepared in Examples 3 and 4 is similar to that in Example 1.

[0077] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a fiber / powder composite VIP core material based on DLP technology, characterized in that: The following steps are involved: (1) mixing glass fiber, gas-phase SiO2 powder, photocurable resin, dispersant, and photoinitiator to obtain a printing material; (2) According to the three-dimensional model of the preset structure, the fiber / powder composite VIP core material is printed using the printing material in (1), and then dried and cooled; (3) The core material in (2) is placed in a barrier film, and a getter is added, and then encapsulated to obtain the product.

2. The preparation method according to claim 1, characterized in that: In step (1), the volume ratio of the glass fiber, gas-phase SiO2 powder, photocurable resin, dispersant and photoinitiator is: (28-32): (53-55): (13-17): (1-1.5): (2.5-3.5).

3. The preparation method according to claim 1, characterized in that: The glass fiber has a length of 4 to 10 mm and a diameter of 4 to 12 μm.

4. The preparation method according to claim 1, characterized in that: The particle size of the gas phase SiO2 powder is 8 to 25 nm.

5. The preparation method according to claim 1, characterized in that: The photocurable resin is an acrylic photocurable resin, specifically selected from any one of HEA, HDDA, and TMPTA; the dispersant is selected from any one of CPD01, CPD02, and CPD03; the photoinitiator is selected from any one of CPI01, CPI06, and TPO.

6. The preparation method according to claim 1, characterized in that: In step (1), the stirring speed is 50 to 200 r / min, and the stirring time is 4 to 10 hours.

7. The preparation method according to claim 1, characterized in that: In step (2), when printing, the wavelength of the light source is 385nm and the light intensity is 12-16mW / cm 2 , the exposure time is 1.8~2.5s, and the printing layer thickness is 40μm~50μm.

8. The preparation method according to claim 1, characterized in that: The drying temperature is 90-110° C., and the drying time is 5-12 hours.

9. The fiber / powder composite VIP core material obtained by the preparation method according to any one of claims 1 to 8.

10. Use of the fiber / powder composite VIP core material according to claim 9 as a thermal insulation material in the field of thermal insulation.

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