Low-thermal-conductivity high-density polystyrene board and production process thereof

Abstract

The invention relates to the field of foam materials, and particularly discloses a low-thermal-conductivity high-density polystyrene board and a production process thereof. The polystyrene board comprises the following raw materials in parts by weight: 85-90 parts of polystyrene; 2-10 parts of graphite powder; 0.04 to 0.06 part of glycerin monostearate; and 2-5 parts of functional filler. The production process comprises the following steps: uniformly mixing the raw materials to obtain a mixed material, and pre-foaming, curing and forming the mixed material to obtain the polystyrene board. The low-heat-conductivity and high-density polystyrene board has the performance advantages of low heat conductivity, high density and high strength.

Description

Technical Field

[0001] The present application relates to the field of foam materials, and more specifically, to a low thermal conductivity and high density polystyrene board and its production process. Background Art

[0002] Thermal insulation materials are widely used in all walks of life. In particular, the rapid development of polymer thermal insulation materials has promoted the development of the thermal insulation material industry and related industries.

[0003] The polystyrene foam board has a honeycomb structure with a high closed cell rate, making it have a lower water absorption rate, higher compressive strength and lower thermal conductivity than similar materials. However, its dimensional stability is poor and it is easy to crack. In related technologies, a thermal insulation material is prepared from polystyrene and graphite, which improves these disadvantages. However, with the continuous improvement of people's requirements for environmental protection and energy conservation, the density and thermal conductivity performance of this thermal insulation material are still not good enough. The market needs thermal insulation materials with better performance to meet the requirements of building energy conservation and insulation. Summary of the Invention

[0004] In order to increase the density of the thermal insulation material and reduce its thermal conductivity, the present application provides a low thermal conductivity and high density polystyrene board and its production process.

[0005] In a first aspect, the present application provides a low thermal conductivity and high density polystyrene board, adopting the following technical solution: A low thermal conductivity and high density polystyrene board, comprising the following raw materials in parts by weight: Polystyrene 85 - 90 parts; Graphite powder 2 - 10 parts; Glycerol monostearate 0.04 - 0.06 parts; Functional filler 2 - 5 parts.

[0006] By adopting the above technical solution, due to the use of the functional filler and compounding with graphite powder, not only the agglomeration problem of graphite powder is improved, the stress concentration situation is reduced, but also the density of the polystyrene board is effectively increased, the thermal conductivity of the polystyrene board is reduced, and the compressive strength of the polystyrene board is improved.

[0007] Optionally, each part of the functional filler comprises de-alkalized lignin and diatomite with a weight ratio of 1:1.5.

[0008] By adopting the above technical solutions, dealkalized lignin (DAL) as a bio-based reinforcing filler can form an interpenetrating network structure in combination with the polystyrene matrix, enhancing the interfacial bonding force. Its rigid benzene ring structure improves the compressive strength and heat resistance of the polystyrene board. The porous structure of diatomite (DE) can provide additional support and stress dispersion, reducing internal defects of the material and enhancing the impact resistance of the polystyrene board. As a high-density inorganic material (with a density of about 2.3 g / cm³), the addition of DE directly increases the mass fraction of the composite material, while the bio-based characteristics of DAL can also contribute to part of the density increase while maintaining environmental friendliness. The rigid benzene ring structure of DAL and the porous framework of DE can enhance the mechanical support of the polystyrene matrix, reducing the excessive expansion of bubbles during the foaming process, thereby increasing the density of the board. Both DAL and DE are renewable resources, and replacing traditional petrochemical fillers (such as talcum powder) can reduce carbon emissions, meeting the trend of green manufacturing. The porosity of DE and the reinforcing effect of DAL can refine the cell structure, forming a more uniform closed-cell honeycomb, reducing heat convection and radiative heat transfer. The composite interface of DAL and DE will introduce additional phonon scattering, hindering the heat conduction path. The nano-scale pores of DE can further reduce the heat conduction efficiency through the "nano-trap" effect. Therefore, the DAL / DE powder filler can reduce the thermal conductivity while increasing the density of the polystyrene board by enhancing the closed-cell structure and optimizing the heat conduction path, and can also improve the compressive strength of the polystyrene board.

[0009] Optionally, the preparation method of the functional filler is: preparing dealkalized lignin / diatomite hydrogel by free radical polymerization; spray-drying the hydrogel and collecting the powder; hydrophobically modifying the surface of the powder.

[0010] By adopting the above technical solutions, first preparing the DAL / DE hydrogel by free radical polymerization can enable the two to bind more closely and play a synergistic role. By spray-drying and adding it to the production process of the polystyrene board in the form of powder, it can effectively reduce the influence of moisture on the foaming process of polystyrene. After the powder is hydrophobically modified, it can further prevent the increase in thermal conductivity caused by moisture intrusion and maintain the long-term thermal insulation stability of the polystyrene board.

[0011] Optionally, the functional filler further includes hydrophobically modified nano-silica, and the weight of the hydrophobically modified nano-silica is 3% of the weight of the dealkalized lignin.

[0012] By adopting the above technical solutions, hydrophobically modifying the nano-silica is beneficial to improving the dispersion of the nano-silica in the hydrogel. By adding hydrophobically modified nano-silica, it is wrapped in the DAL / DE cross-linked network to form a physical barrier layer, which can delay the thermal decomposition of the functional filler through the physical barrier effect, making the functional filler more suitable for the production process of the polystyrene board and reducing losses.

[0013] Optionally, the preparation method of the functional filler is as follows: surface modification of nano-silica, addition of hydrophobically modified nano-silica, and free radical polymerization to prepare a de-alkalized lignin / diatomite hydrogel; spray drying the hydrogel and collecting the powder; surface hydrophobic modification of the powder.

[0014] Optionally, the polystyrene board further comprises the following raw materials in parts by weight: Seaweed fiber 2 - 4 parts; Polyvinyl alcohol 1 - 3 parts.

[0015] By adopting the above technical solution, the seaweed fiber is made from marine organisms such as kelp, the production process is pollution-free and can be naturally degraded, which conforms to the trend of green manufacturing. When compounded with polyvinyl alcohol, it can form an interpenetrating network structure, reduce some stress concentration problems brought by the functional filler and graphite powder in the polystyrene board, disperse stress and absorb impact, and improve the compressive strength of the polystyrene board. At the same time, the functional filler can in turn fill the pores of the polymer matrix, reduce the moisture penetration path, and thus reduce the impact of the high hygroscopicity of the seaweed fiber on the closed-cell structure in the polystyrene board.

[0016] Optionally, the polystyrene board further comprises maleic anhydride grafted polystyrene.

[0017] By adopting the above technical solution, by adding maleic anhydride grafted polystyrene, the compatibility between the interfaces of the seaweed fiber and polyvinyl alcohol and the polymer matrix can be effectively improved, and the occurrence of interfacial stress concentration can be reduced.

[0018] In the second aspect, the present application provides a production process for a low thermal conductivity and high density polystyrene board, adopting the following technical solution: A production process for a low thermal conductivity and high density polystyrene board, comprising the following steps: Mix all the raw materials evenly to obtain a mixed material, and the mixed material is pre-expanded, cured and molded to obtain a polystyrene board.

[0019] By adopting the above technical solution, the obtained polystyrene board has the performance advantages of low thermal conductivity, high density and high strength.

[0020] In summary, the present application has the following beneficial effects: 1. Since the present application uses a functional filler and is compounded with graphite powder, it not only improves the agglomeration problem of graphite powder, reduces the stress concentration situation, but also effectively increases the density of the polystyrene board, reduces the thermal conductivity coefficient of the polystyrene board, and improves the compressive strength of the polystyrene board.

[0021] 2. In this application, it is preferably to use seaweed fiber and polyvinyl alcohol to form an interpenetrating network structure, reduce some stress concentration problems brought by functional fillers and graphite powder in the polystyrene board, disperse stress and absorb impact, and improve the compressive strength of the polystyrene board. At the same time, the functional fillers can in turn fill the pores of the polymer matrix, reduce the moisture penetration path, and thus reduce the impact of the high hygroscopicity of seaweed fiber on the closed-cell structure in the polystyrene board.

[0022] 3. The polystyrene board prepared by the method of this application has the performance advantages of low thermal conductivity, high density, and high strength. Detailed implementation mode

[0023] The following further elaborates on this application in combination with examples. It should be specifically noted that: those without specific conditions in the following examples are carried out according to conventional conditions or the conditions recommended by the manufacturer, and the raw materials used in the following examples can be obtained from ordinary commercial sources except as otherwise specified.

[0024] Polystyrene, Yanshan Petrochemical 666D.

[0025] Graphite powder, 400 mesh.

[0026] Glycerol monostearate, industrial grade, purity ≥ 99.5%.

[0027] Delignified lignin, CAS No.: 9005-53-2, superior grade, brand Langbowan.

[0028] Diatomite, 325 mesh.

[0029] Nano-silica, 12 mesh.

[0030] Seaweed fiber, purchased from Qingdao Hailan Bioproducts Co., Ltd., with a length of 1 mm after crushing.

[0031] Polyvinyl alcohol, CAS No. 9002-89-5.

[0032] Preparation example of functional filler Preparation example 1 The functional filler includes delignified lignin and diatomite.

[0033] The preparation method of the functional filler is: (1)Prepare the following raw materials: 4 g of delignified alkali lignin (DAL), 6 g of diatomaceous earth (DE), 90 ml of deionized water, 2.5 g of acrylic acid (AA), 0.75 g of initiator ammonium persulfate (APS), and 0.25 g of crosslinking agent N,N'-methylenebisacrylamide (MBA). Add DAL and DE to deionized water and ultrasonically disperse for 30 minutes (power 300 W) to form a uniform suspension. Cool down to 5 °C (ice-water bath) to inhibit premature polymerization. Add AA and stir magnetically for 30 minutes. Add APS and MBA, stir evenly and then pour into a mold, and carry out free radical polymerization at 50 °C in a water bath to obtain delignified alkali lignin / diatomaceous earth hydrogel.

[0034] (2)Soak the hydrogel in additional deionized water for 24 h to remove excess reagents, and then store it at room temperature. Dilute the hydrogel with deionized water to a solid content of 5%, carry out high-pressure homogenization (50 MPa) 3 times, and perform spray drying with an inlet temperature of 180 °C, an outlet temperature of 80 °C, and a feeding rate of 10 mL / min. Collect the powder with a cyclone separator and screen it to 20 - 100 μm.

[0035] (3)Immerse all the powder in a 1% stearic acid ethanol solution, stir at 60 °C for 2 hours, filter and dry at 60 °C to reduce water absorption, and then screen to obtain powders of 80 mesh, 100 mesh, 150 mesh and 200 mesh, with a weight ratio of 1:1:1:1.

[0036] Preparation Example 2 The functional filler includes delignified alkali lignin, diatomaceous earth and hydrophobically modified nano-silica.

[0037] The preparation method of the functional filler is as follows: (1)Take 1 g of nano-silica and disperse it in absolute ethanol (solid-liquid ratio 1:50), and ultrasonically treat for 30 minutes (power 300 W). Add silane coupling agent KH570 (3% of the weight of nano-silica), add acetic acid to adjust the pH to 5, and stir at 60 °C for 4 hours. Centrifuge and wash 3 times with absolute ethanol, and dry at 80 °C to obtain hydrophobically modified nano-silica.

[0038] Prepare the following raw materials: 4 g of delignified alkali lignin (DAL), 6 g of diatomaceous earth (DE), 0.12 g of hydrophobically modified nano-silica, 90 ml of deionized water, 2.5 g of acrylic acid (AA), 0.75 g of initiator ammonium persulfate (APS), and 0.25 g of crosslinking agent N,N'-methylenebisacrylamide (MBA).

[0039] Add DAL and DE to deionized water, and ultrasonically disperse for 30 minutes (power 300 W) to form a uniform suspension. Add hydrophobically modified nano-silica to the suspension and ultrasonically treat (40 kHz, 30 minutes) to ensure uniform dispersion of the hydrophobically modified nano-silica. Cool down to 5 °C (ice-water bath) to inhibit premature polymerization. Add AA and stir magnetically for 30 minutes. Add APS and MBA, stir evenly and then pour into a mold, and carry out free radical polymerization in a water bath at 50 °C to obtain a de-alkali lignin / diatomite hydrogel.

[0040] (2) Immerse the hydrogel in another portion of deionized water for 24 h to remove excess reagents, and then store it at room temperature. Dilute the hydrogel with deionized water to a solid content of 5%, and carry out high-pressure homogenization (50 MPa) 3 times, followed by spray drying at an inlet temperature of 180 °C, an outlet temperature of 80 °C, and a feeding rate of 10 mL / min. Collect the powder with a cyclone separator and screen it to 20 - 100 μm.

[0041] (3) Immerse all the powder in a 1% stearic acid ethanol solution, stir at 60 °C for 2 hours, filter and then dry at 60 °C to reduce water absorption, and then screen again to obtain powders of 80 mesh, 100 mesh, 150 mesh and 200 mesh, with a weight ratio of 1:1:1:1.

[0042] Example

[0043] Example 1 A low thermal conductivity and high density polystyrene board, comprising the following raw materials: Polystyrene; graphite powder; glycerol monostearate; the functional filler prepared in Preparation Example 1. The dosage of each raw material is shown in Table 1 in detail.

[0044] A production process of a low thermal conductivity and high density polystyrene board, comprising the following steps: Mix all the raw materials evenly to obtain a mixed material for standby.

[0045] Pre-expansion: Add the mixed material to a pre-expander, input the corresponding material according to the set target weight, keep the steam pressure in the range of 0.5 bar, the inlet air temperature at 95 ± 5 °C, and the pre-expansion time of 300 s. Wait for the pre-expansion to be completed and enter the fluidized bed for surface drying and weight detection. The drying temperature is 45 ± 5 °C and the time is 60 s. Then send the material to a ripening bin for ripening and stabilization. Control the ambient temperature at 40 °C to meet the requirements of the material, at normal pressure, and the time is set to 7 days to obtain pre-expanded beads.

[0046] Molding: First, preheat the mold. The intake air temperature should not be lower than 90 °C, and the preheating time should not be less than 120 s. Secondly, send the pre-expanded beads to the molding mold through a pipeline. Further expand them through steam heating and closely fit the mold to form the required shape. The steam heating uses unsaturated steam, with a temperature of 100 °C, a pressure of 0.5 bar, and a time of 150 s. After molding is completed, let it cool naturally for 10 min, cool the mold to fix the product shape, and then demold to take out the finished product.

[0047] Example 2 The difference between this example and Example 1 lies in the different dosages of each raw material. See Table 1 for details.

[0048] Example 3 The difference between this example and Example 1 lies in the different dosages of each raw material. See Table 1 for details.

[0049] Example 4 The difference between this example and Example 2 is that the functional filler in this example is prepared from Preparation Example 2.

[0050] Example 5 The difference between this example and Example 2 is that the functional filler in this example is de-alkali lignin.

[0051] Example 6 The difference between this example and Example 2 is that the functional filler in this example is diatomite.

[0052] Example 7 The difference between this example and Example 2 is that the functional filler in this example is hydrophobically modified nano-silica.

[0053] Example 8 The difference between this example and Example 4 is that the nano-silica in this example is not surface-modified.

[0054] Example 9 The difference between this example and Example 2 is that the functional filler powder is not surface-hydrophobically modified.

[0055] Example 10 The difference between this example and Example 4 is that the polystyrene board also includes seaweed fiber and polyvinyl alcohol. See Table 1 for the dosages.

[0056] Example 11 The difference between this example and Example 4 is that the dosages of seaweed fiber and polyvinyl alcohol are different. See Table 1 for the dosages.

[0057] Example 12 The difference between this example and Example 4 is that the dosages of seaweed fiber and polyvinyl alcohol are different. See Table 1 for the dosages.

[0058] Example 13 The difference between this example and Example 11 is that there is no seaweed fiber in this example.

[0059] Example 14 The difference between this example and Example 11 is that there is no polyvinyl alcohol in this example.

[0060] Example 15 The difference between this example and Example 11 is that this example also includes maleic anhydride grafted polystyrene, and the dosage is 5% of the weight of the seaweed fiber.

[0061] Comparative Example Comparative Example 1 The difference between this comparative example and Example 2 is that there is no functional filler in this comparative example.

[0062] Table 1 Dosages of each raw material in each example and comparative example

[0063] Performance Detection Test Detection Method 1. Refer to "GB / T 10801.1-2021 Expanded polystyrene boards for thermal insulation", sample preparation and performance detection are carried out on the polystyrene boards prepared in each example and comparative example. 5 specimens are tested for each performance of each material, and the results are averaged. See Table 2 for details. Among them, the apparent density is carried out according to "6.10" (specifically in accordance with GB / T 6343-2009); the compressive deformation strength is carried out according to "6.5", and the compression ratio is 10% (specifically in accordance with GB / T 8813-2020); the thermal conductivity is carried out according to 6.11, and the average temperature is 25 °C (specifically in accordance with GB / T 10294-2008).

[0064] 2. Refer to "Determination of the screw-holding force of profiles" in "GB / T 17657-2022 Test methods for physical and chemical properties of wood-based panels and wood-based panels with surface decoration", sample preparation and performance detection are carried out on the polystyrene boards prepared in each example and comparative example. 5 specimens are tested for each performance of each material, and the results are averaged. See Table 2 for details.

[0065] Table 2 Performance Detection Results

[0066] Combined with Example 2 and Comparative Example 1 and Table 2, it can be seen that by adding functional fillers, the functional fillers contain delignified lignin and diatomaceous earth. The rigid benzene ring structure of DAL and the porous skeleton of DE can enhance the mechanical support of the polystyrene matrix, reduce the excessive expansion of bubbles during the foaming process, thereby increasing the density of the board. Both DAL and DE are renewable resources, and replacing traditional petrochemical fillers (such as talc powder) can reduce carbon emissions, which is in line with the trend of green manufacturing. The porosity of DE and the strengthening effect of DAL can refine the cell structure, form a more uniform closed-cell honeycomb, and reduce heat convection and radiative heat transfer. The composite interface of DAL and DE will introduce additional phonon scattering and hinder the heat conduction path. The nanoscale pores of DE can further reduce the heat conduction efficiency through the "nano trap" effect. The functional fillers effectively increase the density of the polystyrene board, reduce the thermal conductivity of the polystyrene board, and improve the compressive strength of the polystyrene board by enhancing the closed-cell structure and optimizing the heat conduction path.

[0067] Combined with Example 2 and Example 4 and Table 2, it can be seen that hydrophobic modification of nano-silica is beneficial to improving the dispersion of nano-silica in the hydrogel. By adding hydrophobically modified nano-silica, it is wrapped in the DAL / DE cross-linked network to form a physical barrier layer, which can delay the thermal decomposition of the functional filler through the physical barrier effect, making the functional filler more suitable for the production process of polystyrene boards, reducing losses, and having a better effect on improving the performance of polystyrene boards.

[0068] Combined with Example 2, Example 4 - 8 and Table 2, it can be seen that only when delignified lignin, diatomaceous earth and hydrophobically modified nano-silica are used synergistically, can the optimal performance improvement effect be achieved.

[0069] Combined with Example 2 and Example 9 and Table 2, it can be seen that after the functional filler powder is hydrophobically modified, it can further prevent the increase in thermal conductivity caused by water intrusion and maintain the long-term thermal insulation stability of the polystyrene board.

[0070] Combined with Example 4 and Example 11 and Table 2, it can be seen that after adding seaweed fiber and polyvinyl alcohol, an interpenetrating network structure can be formed, reducing some stress concentration problems brought by the functional filler and graphite powder in the polystyrene board, dispersing stress and absorbing impact, and improving the compressive strength of the polystyrene board. At the same time, the functional filler can in turn fill the pores of the polymer matrix, reducing the moisture penetration path, thereby reducing the impact of the high hygroscopicity of seaweed fiber on the closed-cell structure in the polystyrene board.

[0071] Combined with Example 11, Example 13, Example 14 and Table 2, it can be seen that only when seaweed fiber and polyvinyl alcohol are compounded and added can the optimal performance improvement effect be achieved.

[0072] Combined with Example 11, Example 15 and Table 2, it can be seen that by adding maleic anhydride grafted polystyrene, the compatibility between the interfaces of seaweed fiber and polyvinyl alcohol and the polymer matrix can be effectively improved, and the occurrence of interfacial stress concentration can be reduced, thereby further improving various properties of the polystyrene board.

[0073] This specific embodiment is only an explanation of the present application, and it is not a limitation of the present application. Those skilled in the art can make modifications without creative contributions to this embodiment according to needs after reading this specification, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A low thermal conductivity and high density polystyrene board, characterized in that, It comprises raw materials in the following parts by weight: 85 - 90 parts of polystyrene; 2 - 10 parts of graphite powder; 0.04 - 0.06 part of glycerol monostearate; 2 - 5 parts of functional filler.

2. A low thermal conductivity and high density polystyrene board according to claim 1, characterized in that Each part of the functional filler comprises delignified lignin and diatomite with a weight ratio of 1:1.

5.

3. A low thermal conductivity and high density polystyrene board according to claim 2, characterized in that, The preparation method of the functional filler is as follows: preparing a delignified lignin / diatomite hydrogel by free radical polymerization; spray-drying the hydrogel and collecting the powder; hydrophobically modifying the surface of the powder.

4. A low thermal conductivity high density polystyrene board according to claim 2, characterized in that: The functional filler further comprises hydrophobically modified nano-silica, and the weight of the hydrophobically modified nano-silica is 3% of the weight of the delignified lignin.

5. The low thermal conductivity and high density polystyrene board according to claim 4, wherein: The preparation method of the functional filler is as follows: performing surface modification treatment on nano-silica, adding hydrophobically modified nano-silica, and preparing a delignified lignin / diatomite hydrogel by free radical polymerization; spray-drying the hydrogel and collecting the powder; hydrophobically modifying the surface of the powder.

6. A low thermal conductivity high density polystyrene board according to claim 1, characterized in that: The polystyrene board further comprises raw materials in the following parts by weight: 2 - 4 parts of seaweed fiber; 1 - 3 parts of polyvinyl alcohol.

7. The low thermal conductivity and high density polystyrene board according to claim 6, characterized in that: The polystyrene board further comprises maleic anhydride grafted polystyrene, and the dosage is 5% of the weight of the seaweed fiber.

8. The production process of a low thermal conductivity and high density polystyrene board according to any one of claims 1 to 7, characterized in that, It comprises the following steps: Mixing the raw materials evenly to obtain a mixed material, and subjecting the mixed material to pre-expansion, ripening and molding to obtain the polystyrene board.

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