Thermal insulation material and method for producing the same, cold plate

Abstract

The application belongs to the technical field of thermal insulation materials, and particularly relates to a novel thermal insulation material, a preparation method thereof and a cold plate. The novel thermal insulation material comprises the following raw material components: polystyrene particles 70-80 parts; methyl octabromo ether 5-7 parts; ethanol 0.5-1 part; freon 2-5 parts; and modified graphite powder 14-16 parts. The novel thermal insulation material has simple components, and after being prepared through compounding, the thermal conductivity coefficient is significantly reduced, and the novel thermal insulation material also has high strength and pressure resistance, fire resistance and water resistance. When the novel thermal insulation material is used for manufacturing a cold plate, the thickness can be greatly reduced under the same thermal insulation requirement, the space for use is saved, the self-weight is also reduced, and the novel thermal insulation material has a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of thermal insulation materials technology, specifically relating to a thermal insulation material and its preparation method, and a cold storage plate. Background Technology

[0002] In the cold chain logistics sector, the insulation performance of refrigerated compartments is crucial, directly impacting the quality and spoilage of goods. Traditional refrigerated compartment insulation panels primarily use materials such as polyurethane foam and XPS extruded polystyrene boards. While polyurethane foam has a thermal conductivity of approximately 0.023 W / (m·K), it performs poorly in limiting heat transfer and is not heat-resistant, thus limiting the lifespan of the refrigerated compartment. Furthermore, the associated spraying process cannot exceed 100℃ for baking. Although ordinary XPS extruded polystyrene boards offer good insulation and compressive strength, as industry demands for insulation material performance continue to rise, they are increasingly failing to meet requirements in areas such as further improvement in thermal insulation performance, enhanced fire resistance, usability, and energy efficiency. Therefore, developing a high-performance insulation material is essential. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a thermal insulation material, its preparation method, and a refrigerated board. This thermal insulation material has a simple composition, and after composite preparation, its thermal conductivity is significantly reduced. It also possesses high strength and compressive strength, fire resistance, and durability. When used to manufacture refrigerated boards, the thickness can be greatly reduced under the same insulation requirements, saving space and reducing weight. Applying this refrigerated board to cold chain logistics is beneficial for improving transportation efficiency and reducing energy consumption, and has broad application prospects.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] The first objective of this invention is to provide a thermal insulation material, which, by weight, comprises the following raw material components:

[0006] 70-80 parts of polystyrene granules;

[0007] 5-7 parts of methyl octabromoether;

[0008] 0.5-1 part ethanol;

[0009] Freon 2-5 parts;

[0010] 14-16 parts of modified graphite powder.

[0011] Furthermore, in the above technical solution, the preparation steps of the modified graphite powder are as follows:

[0012] (1) Mix graphite powder with mixed acid and sonicate for 2-3 hours, wash with water until neutral, and then dry.

[0013] (2) The pretreated graphite was mixed with heptadecafluorodecyltrimethoxysilane and loaded into a ball mill jar. Nitrogen was introduced to replace the air. After grinding at 400-500 rpm for 2-3 hours, the mixture was washed with ethanol 2-3 times.

[0014] (3) The graphite obtained in step (2) is mixed with nano boron carbide, modified silicon dioxide and nanofiber in a high-speed mixer for 10-20 min to obtain modified graphite powder.

[0015] In this technical solution, graphite powder is first pretreated with acid to improve its surface activity. Then, it is mixed with heptadecafluorodecyltrimethoxysilane and ball-milled to form a low surface energy layer of perfluoroalkyl groups on the graphite surface. Finally, it is mixed at high speed with nano-boron carbide, modified silica, and nanofibers to form a surface activity that matches that of the subsequent Freon foaming agent. Nano-boron carbide provides directional adsorption capacity, and modified silica provides nucleation sites. The synergistic effect of the two can improve the uniformity of the foam pores. The nanofibers can penetrate the two to form a three-dimensional network, which can prevent pore migration and agglomeration during foaming, limit the growth space of the pores, and improve the interfacial stability. The modified graphite not only retains its own layered structure, high thermal conductivity, and flame retardancy, but also exhibits good dispersibility when mixed with PS and foaming agents. Utilizing its closed-cell honeycomb structure and modified active sites, the closed-cell structure becomes denser, more uniform, and more stable, greatly improving the overall thermal insulation performance of the board.

[0016] Furthermore, in step (1) of the above technical solution, the mixed acid is a mixed acid in which the volume ratio of concentrated sulfuric acid to nitric acid is 3:1, and the solid-liquid ratio of the graphite powder to the mixed acid is 1:1-3.

[0017] Furthermore, in step (2) of the above technical solution, the amount of heptadecafluorodecyltrimethoxysilane used is 4-6% of the mass of the graphite powder.

[0018] Furthermore, in step (3) of the above technical solution, the mass ratio of graphite to nano boron carbide, modified silicon dioxide, and nanofiber is 1:(0.05-0.1):(0.3-0.6):(0.2-0.4).

[0019] Furthermore, in the above technical solution, the modification method of the modified silica is as follows: silica powder is placed in a fluidized bed reactor, the air is purged with nitrogen, and heptadecafluorodecyltrimethoxysilane vapor is introduced at 110-125℃ for 15-25 minutes. After purging, the mixture is cooled to obtain the desired product. In this technical solution, silica is pretreated and modified with heptadecafluorodecyltrimethoxysilane. The resulting fluorinated silica not only improves the dispersion performance of graphite in the mixture but also provides high-density nucleation sites during foaming and induces uniform bubbles by generating repulsive forces with Freon.

[0020] A second objective of this invention is to provide a method for preparing a thermal insulation material, the method comprising the following steps:

[0021] S1. Add polystyrene particles, modified graphite powder, methyl octabromoether and ethanol into a high-speed mixer in proportion, and stir thoroughly to obtain a mixture;

[0022] S2. The mixture is heated to 180-220℃ through a twin-screw extruder to melt and plasticize the polystyrene particles, and Freon is injected into the extruder to form a uniform melt;

[0023] S3. The melt is extruded through the extruder head and rapidly cooled;

[0024] S4. Cut the shaped boards into finished boards of specified sizes according to requirements;

[0025] S5. After the finished boards have been placed for 24-48 hours, they are inspected, packaged, and put into storage.

[0026] Furthermore, in the above technical solution, in S1, the stirring speed is 1000-1500 rpm; in S2, the pressure of the Freon injection is 10-12 MPa, and the temperature is 60-80℃. In this technical solution, the foaming agent is injected into the extruder under high pressure, and the foaming agent dissolves in the melt under high temperature and high pressure, resulting in good uniformity.

[0027] The present invention also provides a refrigerated plate, which is made of fiberglass reinforced plastic and the above-mentioned insulation material.

[0028] Furthermore, the specific manufacturing method of the above technical solution is as follows: First, fiberglass reinforced plastic (FRP) is laid flat on the platform of the board-making equipment. Then, a pre-prepared two-component polyurethane composite adhesive is evenly applied to the FRP surface using a glue-applying machine. Next, the prepared insulation material is laid flat on the glue-applyed FRP. The two-component polyurethane composite adhesive is then evenly applied to the insulation material using the glue-applying machine. Finally, the FRP is covered on top of the glue-applyed insulation material. Finally, the material is fed into the pressing equipment via a mechanical transmission chain for positive pressure bonding to obtain the refrigerated board. The two-component polyurethane composite adhesive is a commercially available AB two-component polyurethane composite adhesive, which is mixed evenly with components A and B in a 1:5 ratio during use.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] The thermal insulation material of this invention uses polystyrene particles as the main raw material. By adding modified graphite, it is uniformly distributed inside the polystyrene. While bringing in the inherent properties of graphite, it can improve its melt flowability, temperature uniformity, and interfacial stability. At the same time, it acts as a nucleation site, generating more uniform microbubbles during the foaming process and increasing the closed-cell bubble rate. The addition of methyl octabromoether further enhances the flame retardant properties of the material. The addition of Freon as a foaming agent fully utilizes its low thermal conductivity and swelling rate in polystyrene, which can effectively inhibit cell coalescence and improve the closed-cell rate.

[0031] The thermal insulation material prepared by this invention has a high closed-cell rate and low thermal conductivity. It also has high strength and compressive strength, excellent fire resistance, and good waterproof, moisture-proof and durability properties. When used to make refrigerated panels for refrigerated compartments, it has good thermal insulation effect and long service life. Under the same insulation requirements, the thickness can be reduced, the self-weight of the compartment can be reduced, which is conducive to improving transportation efficiency and reducing energy consumption. It has broad application prospects. Detailed Implementation

[0032] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the raw materials used in the following examples are all commercially available products and can be purchased from the market.

[0033] The above-described technical features of the present invention and the technical features specifically described below (such as in the embodiments) can be combined with each other to form new or preferred technical solutions.

[0034] The raw materials involved in the various embodiments of the present invention are either existing commercially available products or can be prepared according to existing methods, and the testing methods are industry-standard methods.

[0035] Example 1

[0036] A thermal insulation material, by weight, comprises the following raw material components:

[0037] 70 parts of polystyrene granules;

[0038] 5 parts of methyl octabromoether;

[0039] 0.5 parts ethanol;

[0040] 2 parts Freon;

[0041] 14 parts of modified graphite powder;

[0042] The preparation steps of the modified graphite powder are as follows:

[0043] (1) Mix graphite powder with mixed acid (concentrated sulfuric acid to nitric acid in a volume ratio of 3:1) at a solid-liquid ratio of 1:1, sonicate for 3 hours, wash with water until neutral, and then dry.

[0044] (2) The pretreated graphite was mixed with 4% heptadecafluorodecyltrimethoxysilane and loaded into a ball mill jar. Nitrogen was introduced to replace the air. After grinding at 400 rpm for 3 hours, the mixture was washed twice with ethanol.

[0045] (3) The graphite obtained in step (2) is mixed with nano boron carbide, modified silica and nanofiber in a mass ratio of 1:0.05:0.3:0.2 in a high-speed mixer for 10 min to obtain modified graphite powder;

[0046] The modification method for modified silica is as follows: silica powder is placed in a fluidized bed reactor, the air is purged with nitrogen, and heptadecafluorodecyltrimethoxysilane vapor is introduced at 110°C for 25 minutes. After the gas introduction is stopped, the mixture is cooled to obtain the modified silica.

[0047] The preparation method of this thermal insulation material includes the following steps:

[0048] S1. Add polystyrene particles, modified graphite powder, methyl octabromoether and ethanol into a high-speed mixer in proportion, and stir thoroughly at 1000 pm to obtain a mixture;

[0049] S2. The mixture is heated to 180-220℃ through a twin-screw extruder to melt and plasticize the polystyrene particles, and Freon is injected into the extruder through a high-pressure injection device (pressure 10MPa, temperature 60℃) to form a uniform melt;

[0050] S3. The melt is extruded through the extruder head. At this time, the pressure drops sharply, the foaming agent rapidly vaporizes and expands, forming a large number of uniform and dense bubble structures, and is rapidly cooled in a water bath.

[0051] S4. Cut the shaped boards into finished boards of specified sizes according to requirements;

[0052] S5. After the finished boards have been placed for 48 hours, they are inspected, packaged, and put into storage.

[0053] Example 2

[0054] A thermal insulation material, by weight, comprises the following raw material components:

[0055] 74 parts of polystyrene granules;

[0056] 6 parts of methyl octabromoether;

[0057] 0.8 parts ethanol;

[0058] 3.5 parts Freon;

[0059] 15 parts of modified graphite powder;

[0060] The preparation steps of the modified graphite powder are as follows:

[0061] (1) Mix graphite powder with mixed acid (concentrated sulfuric acid to nitric acid in a volume ratio of 3:1) at a solid-liquid ratio of 1:2, sonicate for 3 hours, wash with water until neutral, and then dry.

[0062] (2) The pretreated graphite was mixed with 5% heptadecafluorodecyltrimethoxysilane and loaded into a ball mill jar. Nitrogen was introduced to replace the air. After grinding at 450 rpm for 3 hours, the mixture was washed with ethanol 3 times.

[0063] (3) The graphite obtained in step (2) is mixed with nano boron carbide, modified silica and nanofiber in a mass ratio of 1:0.07:0.5:0.3 in a high-speed mixer for 15 min to obtain modified graphite powder;

[0064] The modification method of modified silica is as follows: put silica powder into a fluidized bed reactor, purge the air with nitrogen, and then introduce heptadecafluorodecyltrimethoxysilane vapor at 120°C for 20 minutes. After purging, cool the mixture to obtain the modified silica.

[0065] The preparation method of this thermal insulation material includes the following steps:

[0066] S1. Add polystyrene particles, modified graphite powder, methyl octabromoether and ethanol into a high-speed mixer in proportion, and stir thoroughly at 1200 rpm to obtain a mixture;

[0067] S2. The mixture is heated to 180-220℃ through a twin-screw extruder to melt and plasticize the polystyrene particles, and Freon is injected into the extruder through a high-pressure injection device (pressure 12MPa, temperature 60℃) to form a uniform melt;

[0068] S3. The melt is extruded through the extruder head. At this time, the pressure drops sharply, the foaming agent rapidly vaporizes and expands, forming a large number of uniform and dense bubble structures, and is rapidly cooled in a water bath.

[0069] S4. Cut the shaped boards into finished boards of specified sizes according to requirements;

[0070] S5. After the finished boards have been placed for 48 hours, they are inspected, packaged, and put into storage.

[0071] Example 3

[0072] A thermal insulation material, by weight, comprises the following raw material components:

[0073] 80 parts of polystyrene granules;

[0074] 7 parts of methyl octabromoether;

[0075] 1 part ethanol;

[0076] 5 parts Freon;

[0077] 16 parts of modified graphite powder;

[0078] The preparation steps of the modified graphite powder are as follows:

[0079] (1) Mix graphite powder with mixed acid (concentrated sulfuric acid to nitric acid in a volume ratio of 3:1) at a solid-liquid ratio of 1:3, sonicate for 2 hours, wash with water until neutral, and then dry.

[0080] (2) The pretreated graphite was mixed with 6% heptadecafluorodecyltrimethoxysilane and loaded into a ball mill jar. Nitrogen was introduced to replace the air. After grinding at 500 rpm for 2 hours, the mixture was washed with ethanol 3 times.

[0081] (3) The graphite obtained in step (2) is mixed with nano boron carbide, modified silica and nanofiber in a mass ratio of 1:0.1:0.6:0.4 in a high-speed mixer for 10 min to obtain modified graphite powder;

[0082] The modification method for modified silica is as follows: silica powder is placed in a fluidized bed reactor, the air is purged with nitrogen, and heptadecafluorodecyltrimethoxysilane vapor is introduced at 125°C for 15 minutes. After the aeration is stopped, the mixture is cooled to obtain the desired product.

[0083] The preparation method of this thermal insulation material includes the following steps:

[0084] S1. Add polystyrene particles, modified graphite powder, methyl octabromoether and ethanol into a high-speed mixer in proportion, and stir thoroughly at 1500 rpm to obtain a mixture;

[0085] S2. The mixture is heated to 180-220℃ through a twin-screw extruder to melt and plasticize the polystyrene particles, and Freon is injected into the extruder through a high-pressure injection device (pressure 12MPa, temperature 60℃) to form a uniform melt;

[0086] S3. The melt is extruded through the extruder head. At this time, the pressure drops sharply, the foaming agent rapidly vaporizes and expands, forming a large number of uniform and dense bubble structures, and is rapidly cooled in a water bath.

[0087] S4. Cut the shaped boards into finished boards of specified sizes according to requirements;

[0088] S5. After the finished boards have been placed for 48 hours, they are inspected, packaged, and put into storage.

[0089] Comparative Example 1

[0090] An insulation material, which differs from Example 1 in that the graphite powder used is not modified, but the other preparation methods are the same.

[0091] Comparative Example 2

[0092] A thermal insulation material, which differs from Example 1 in that the modified graphite powder used is not modified in step (2), but the other preparation methods are the same.

[0093] Comparative Example 3

[0094] A thermal insulation material, which differs from Example 1 in that the modified graphite powder used is not modified in step (3), but the other preparation methods are the same.

[0095] Comparative Example 4

[0096] A thermal insulation material, which differs from Example 1 in that the modified graphite powder used has unmodified silicon dioxide in step (3) of the modification process, while the other preparation methods are the same.

[0097] Comparative Example 5

[0098] A thermal insulation material, commercially available ordinary XPS extruded polystyrene board.

[0099] Test case

[0100] 1. The properties of the thermal insulation materials prepared in Examples 1-3 and Comparative Examples 1-5 were tested, and the results are shown in Table 1. The thermal conductivity was determined according to the relevant methods in GB / T 10294-2008, and the compressive strength, flammability rating, and volumetric water absorption rate were determined according to the relevant methods in JG / T536-2017.

[0101] Table 1 Performance Tests

[0102]

[0103] As can be seen from the results in Table 1, the thermal insulation material prepared by the method of the present invention has a higher closed-cell rate, lower thermal conductivity, better compressive strength, higher flame retardant rating, and better waterproof performance compared with comparative examples 1-5, making it an excellent thermal insulation material.

[0104] In Comparative Examples 1-4, the performance of the silica was affected by the lack of modification or the different modification methods. It is likely that the silica that was not modified according to the present invention had poor dispersibility when mixed with PS and foaming agent, and affected the formation of closed-cell structure in the subsequent foaming process, thus affecting the overall performance of the material.

[0105] 2. The insulation material obtained in Example 1 and the commercially available XPS extruded board from Comparative Example 5 were used to make refrigerated boards with the same insulation requirements (±30℃). The thickness of the two types of refrigerated boards was then measured, and the results are shown in Table 2. The preparation method of the refrigerated board is as follows: First, fiberglass reinforced plastic is laid flat on the platform of the board making equipment. Then, the pre-prepared two-component polyurethane composite adhesive is evenly applied to the fiberglass surface using a glue-applying machine. Next, the prepared insulation material (Example 1 and Comparative Example 5) is laid flat on the glue-applying fiberglass reinforced plastic. The two-component polyurethane composite adhesive is then evenly applied to the insulation material using a glue-applying machine. Finally, the fiberglass reinforced plastic is placed on top of the glue-applying insulation material. Finally, the refrigerated board is fed into the pressing equipment by a mechanical transmission chain for positive pressure bonding to obtain the refrigerated board.

[0106] Table 2 Thickness Comparison

[0107]

[0108] As can be seen from the results in Table 2, the thermal insulation material prepared by this invention has an extremely low thermal conductivity. Under the same thermal insulation requirements, the thickness of the refrigerated board made from it can be greatly reduced compared to commercially available ordinary XPS extruded board. This not only saves space but also reduces weight, which can improve transportation efficiency when applied to refrigerated compartments.

[0109] Finally, it should be emphasized that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A thermal insulation material, characterized in that, By weight, the thermal insulation material comprises the following raw material components: 70-80 parts of polystyrene granules; 5-7 parts of methyl octabromoether; 0.5-1 part ethanol; Freon 2-5 parts; 14-16 parts of modified graphite powder; The preparation steps of the modified graphite powder are as follows: (1) Mix graphite powder with mixed acid and sonicate for 2-3 hours, wash with water until neutral, and then dry. (2) The pretreated graphite was mixed with heptadecafluorodecyltrimethoxysilane and loaded into a ball mill jar. Nitrogen was introduced to replace the air. After grinding at 400-500 rpm for 2-3 hours, the mixture was washed with ethanol 2-3 times. (3) The graphite obtained in step (2) is mixed with nano-boron carbide, modified silica, and nanofibers in a high-speed mixer for 10-20 minutes to obtain modified graphite powder; wherein, The modification method of the modified silica is as follows: silica powder is placed in a fluidized bed reactor, the air is purged with nitrogen, and heptadecafluorodecyltrimethoxysilane vapor is introduced at 110-125℃ for 15-25 minutes. After the gas introduction is stopped, the mixture is cooled to obtain the modified silica.

2. The thermal insulation material according to claim 1, characterized in that, In step (1), the mixed acid is a mixture of concentrated sulfuric acid and nitric acid in a volume ratio of 3:1, and the solid-liquid ratio of the graphite powder to the mixed acid is 1:1-3.

3. The thermal insulation material according to claim 1, characterized in that, In step (2), the amount of heptadecafluorodecyltrimethoxysilane used is 4-6% of the mass of the graphite powder.

4. The thermal insulation material according to claim 1, characterized in that, In step (3), the mass ratio of graphite to nano boron carbide, modified silica, and nanofiber is 1:(0.05-0.1):(0.3-0.6):(0.2-0.4).

5. A method for preparing a thermal insulation material according to any one of claims 1-4, characterized in that, The preparation method includes the following steps: S1. Add polystyrene particles, modified graphite powder, methyl octabromoether and ethanol into a high-speed mixer in proportion, and stir thoroughly to obtain a mixture; S2. The mixture is heated to 180-220℃ through a twin-screw extruder to melt and plasticize the polystyrene particles, and Freon is injected into the extruder to form a uniform melt; S3. The melt is extruded through the extruder head and rapidly cooled; S4. Cut the shaped boards into finished boards of specified sizes according to requirements; S5. After the finished boards have been placed for 24-48 hours, they are inspected, packaged, and put into storage.

6. The method for preparing a thermal insulation material according to claim 5, characterized in that, In S1, the stirring speed is 1000-1500 rpm; in S2, the pressure of the Freon injection is 10-12 MPa and the temperature is 60-80℃.

7. A refrigerated plate, characterized in that, It is made of fiberglass reinforced plastic and the thermal insulation material described in any one of claims 1-4.

8. A refrigerated plate according to claim 7, characterized in that, The specific manufacturing method is as follows: First, fiberglass reinforced plastic is laid flat on the platform of the board making equipment. Then, the pre-made two-component polyurethane composite adhesive is evenly applied to the fiberglass surface through a glue-applying machine. Next, the prepared insulation material is laid flat on the fiberglass reinforced plastic after applying the adhesive. Then, the two-component polyurethane composite adhesive is evenly applied to the insulation material through the glue-applying machine. Finally, the fiberglass reinforced plastic is placed on top of the insulation material after applying the adhesive. Finally, the material is fed into the pressing equipment through a mechanical transmission chain for positive pressure bonding to obtain the refrigerated board.

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