Novel thermal insulation material, preparation method thereof and refrigeration plate

Abstract

The invention belongs to the technical field of thermal insulation materials, and particularly relates to a novel thermal insulation material, a preparation method thereof and a refrigeration plate. The novel thermal insulation material comprises the following raw material components: 70-80 parts of polystyrene particles; 5-7 parts of methyl octabromoether; 0.5 to 1 part of ethanol; 2 to 5 parts of Freon; and 14-16 parts of modified graphite powder. The novel thermal insulation material is simple in component, the heat conductivity coefficient is remarkably reduced after the novel thermal insulation material is compounded and prepared, meanwhile, the novel thermal insulation material has high strength, pressure resistance, fire resistance and water resistance, when the novel thermal insulation material is used for manufacturing a refrigeration plate, the thickness can be greatly reduced under the same thermal insulation requirement, the used space is saved, meanwhile, the self weight can be reduced, and the novel thermal insulation material has wide application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal insulation materials, and in particular relates to a novel thermal insulation material and a preparation method thereof, and a refrigeration plate. Background Art

[0002] In the field of cold chain logistics, the thermal insulation performance of refrigerated compartments is of vital importance and is directly related to the quality and loss of goods. Traditional refrigerated compartment insulation boards are mostly made of materials such as polyurethane foam and XPS extruded boards. Among them, although the thermal conductivity of polyurethane foam is about 0.023W / (m·K), it performs poorly in terms of heat conduction restrictions and is not resistant to high temperatures, which limits the service life of the refrigerated compartments. The temperature of the supporting spraying process cannot exceed 100°C for baking. Although ordinary XPS extruded boards have good thermal insulation and pressure resistance, as the industry's requirements for the performance of insulation materials continue to rise, it is gradually difficult to meet the needs in terms of further improvement of thermal insulation performance, strengthening of fire resistance, usage performance, and energy-saving performance. Therefore, it is necessary to develop a new type of high-performance insulation material. Summary of the Invention

[0003] In response to the deficiencies in the prior art, the present invention provides a new thermal insulation material, a preparation method thereof, and a refrigeration board. The new thermal insulation material has a simple composition, and after composite preparation, the thermal conductivity coefficient is significantly reduced. At the same time, it also has high strength and compression resistance, fire resistance and durability. When used to make refrigeration boards, the thickness can be greatly reduced under the same insulation requirements, saving space and reducing the weight. The refrigeration board is applied to cold chain logistics, which is beneficial to improving transportation efficiency and reducing energy consumption, and has broad application prospects.

[0004] In order to achieve the above object, the present invention provides the following technical solutions: The first object of the present invention is to provide a new thermal insulation material, which comprises the following raw material components in parts by weight: 70-80 parts of polystyrene particles; 5-7 parts of methyl octabromoether; 0.5-1 part of ethanol; 2-5 parts of Freon; 14-16 parts of modified graphite powder.

[0005] Furthermore, in the above technical solution, the preparation steps of the modified graphite powder are: (1) Mix graphite powder and mixed acid and ultrasonically treat for 2-3 hours, wash with water until neutral and then dry; (2) The pretreated graphite and heptafluorodecyltrimethoxysilane were mixed and placed in a ball mill, nitrogen was introduced to replace the air, and the mixture was ground at 400-500 rpm for 2-3 hours, and then washed with ethanol 2-3 times; (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 minutes to obtain modified graphite powder.

[0006] In this technical solution, graphite powder is first pretreated with acid to increase its surface activity. It is then mixed and ball-milled with heptadecafluorodecyltrimethoxysilane 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. The nano-boron carbide provides directional adsorption capacity, and the modified silica provides nucleation sites. The synergistic effect of the two improves the uniformity of the foaming cells. The nanofibers penetrate the two to form a three-dimensional network, which prevents pore migration and agglomeration during the foaming process, limits the space for pore growth, and improves interfacial stability. The modified graphite not only retains its inherent layered structure, high thermal conductivity, and flame retardancy, but also exhibits good dispersibility when mixed with PS and the foaming agent. Its closed-cell honeycomb structure and modified active sites make the closed-cell structure more dense, uniform, and stable, greatly improving the overall thermal insulation performance of the board.

[0007] Furthermore, in step (1) of the above technical solution, the mixed acid is a mixed acid with a volume ratio of concentrated sulfuric acid to nitric acid of 3:1, and the solid-liquid ratio of the graphite powder to the mixed acid is 1:1-3.

[0008] Furthermore, in step (2) of the above technical solution, the amount of heptadecafluorodecyltrimethoxysilane used is 4-6% of the mass of the graphite powder.

[0009] Furthermore, in step (3) of the above technical solution, the mass ratio of the graphite to nano-boron carbide, modified silicon dioxide, and nanofiber is 1:(0.05-0.1):(0.3-0.6):(0.2-0.4).

[0010] Furthermore, in the above technical solution, the modified silica is modified by placing silica powder into a fluidized bed reactor, evacuating the air with nitrogen, and then introducing heptadecafluorodecyltrimethoxysilane vapor at 110-125°C for 15-25 minutes. The evacuation is terminated, and the silica is cooled to obtain the modified silica. In this technical solution, the silica is pretreated and modified with heptadecafluorodecyltrimethoxysilane. The resulting fluorinated silica not only improves the dispersion of graphite in the mixture but also provides a high density of nucleation sites during foaming, generating a repulsive force with the freon, thereby inducing uniform bubbles.

[0011] A second object of the present invention is to provide a method for preparing a novel thermal insulation material, the method comprising the following steps: S1. The polystyrene particles, modified graphite powder, methyl octabromoether and ethanol were added to a high-speed mixer in proportion and stirred thoroughly to obtain a mixture; S2. The mixture is heated to 180-220°C through a twin-screw extruder to melt and plasticize the polystyrene particles, and the 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 sheet into finished sheets of specified size according to the requirements; S5. After the finished boards are placed for 24-48 hours, they are inspected, packaged and put into storage.

[0012] Furthermore, in the above technical solution, in S1, the stirring speed is 1000-1500 rpm; and in S2, the freon injection pressure is 10-12 MPa and the temperature is 60-80°C. 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 pressure, resulting in good uniformity.

[0013] The present invention also provides a refrigeration plate, which is made by compounding glass fiber reinforced plastic and the above-mentioned novel heat-insulating material.

[0014] Furthermore, in the above technical solution, the specific production method is as follows: first, fiberglass reinforced plastic (FRP) is laid flat on the plate-making equipment platform, then a pre-prepared two-component polyurethane composite glue is evenly applied to the FRP surface via a glue spraying machine, then the prepared new thermal insulation material is laid flat on the FRP coated with glue, then the two-component polyurethane composite glue is evenly applied to the new thermal insulation material via a glue spraying machine, then the FRP is covered with glue on the new thermal insulation material, and finally, the cold storage panel is fed into a press equipment via a mechanical transmission chain for positive pressure lamination. The two-component polyurethane composite glue is a commercially available AB two-component polyurethane composite glue, and when used, components A and B are evenly mixed in a ratio of 1:5.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The novel thermal insulation material of the present invention uses polystyrene particles as the main raw material. By adding modified graphite, the modified graphite is evenly distributed inside the polystyrene. While introducing the characteristics of the graphite itself, the melt fluidity, temperature uniformity and interface stability of the graphite can be improved. At the same time, as a nucleation site, more uniform tiny bubbles are generated during the foaming process, thereby increasing the closed-cell bubble rate. Methyl octabromoether is added to further enhance the flame retardant properties of the material. Freon is added as a foaming agent to fully utilize its low thermal conductivity and swelling rate in polystyrene, thereby effectively inhibiting the merging of bubbles and increasing the closed-cell rate.

[0016] The new thermal insulation material prepared by the present invention has a high closed-pore rate and low thermal conductivity. It also has high strength and compression resistance, excellent fire resistance, waterproofness, moisture resistance and good durability. It is used to make refrigerated panels for refrigerated compartments, has good thermal insulation effect and long service life. Under the same thermal insulation requirements, the thickness can be reduced and the dead weight of the compartment can be reduced, which is beneficial to improving transportation efficiency and reducing energy consumption, and has broad application prospects. DETAILED DESCRIPTION

[0017] The experimental methods in the following examples are conventional methods unless otherwise specified. The raw materials involved in the following examples are common commercial products and can be purchased from the market unless otherwise specified.

[0018] The above-mentioned technical features of the present invention and the technical features specifically described below (such as embodiments) can be combined with each other to form new or preferred technical solutions.

[0019] The raw materials involved in the 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 methods.

[0020] Example 1 A novel thermal insulation material, comprising the following raw material components in parts by weight: 70 parts of polystyrene particles; 5 parts of methyl octabromoether; 0.5 parts of ethanol; 2 parts of Freon; 14 parts of modified graphite powder; Wherein, the preparation steps of modified graphite powder are: (1) Graphite powder and mixed acid (concentrated sulfuric acid and nitric acid volume ratio of 3:1) were mixed at a solid-liquid ratio of 1:1, ultrasonically treated for 3 hours, washed with water until neutral, and then dried; (2) The pretreated graphite was mixed with 4% heptadecafluorodecyltrimethoxysilane and placed in a ball mill, nitrogen was introduced to replace the air, and the mixture was ground at 400 rpm for 3 h, followed by washing with ethanol twice; (3) The graphite obtained in step (2) was mixed with nano-boron carbide, modified silicon dioxide, and nanofiber in a mass ratio of 1:0.05:0.3:0.2 in a high-speed mixer for 10 minutes to obtain modified graphite powder; The modified silica is modified by placing silica powder in a fluidized bed reactor, evacuating the air with nitrogen, introducing heptadecafluorodecyltrimethoxysilane vapor at 110° C. for 25 minutes, stopping the ventilation, and cooling to obtain the modified silica.

[0021] The preparation method of the novel thermal insulation material comprises the following steps: S1. The polystyrene particles, modified graphite powder, methyl octabromoether and ethanol were added to a high-speed mixer in proportion and stirred thoroughly at 1000pm to obtain a mixture; S2. The mixture is heated to 180-220°C through a twin-screw extruder to melt and plasticize the polystyrene particles. Freon is then injected into the extruder through a high-pressure injection device (pressure 10 MPa, temperature 60°C) to form a uniform melt. S3. The melt is extruded through the extruder head, at which point the pressure drops sharply, the foaming agent rapidly vaporizes and expands, forming a large number of uniform and dense bubble structures, and rapidly cooled in a water bath; S4. Cut the shaped sheet into finished sheets of specified size according to the requirements; S5. After the finished boards are placed for 48 hours, they are inspected, packaged and put into storage.

[0022] Example 2 A novel thermal insulation material, comprising the following raw material components in parts by weight: 74 parts of polystyrene particles; 6 parts of methyl octabromoether; 0.8 parts of ethanol; 3.5 parts of Freon; 15 parts of modified graphite powder; Wherein, the preparation steps of modified graphite powder are: (1) Graphite powder was mixed with mixed acid (concentrated sulfuric acid and nitric acid volume ratio 3:1) at a solid-liquid ratio of 1:2, and ultrasonically treated for 3 hours, then washed with water until neutral and dried; (2) The pretreated graphite was mixed with 5% heptafluorodecyltrimethoxysilane and placed in a ball mill, nitrogen was introduced to replace the air, and the mixture was ground at 450 rpm for 3 h, followed by washing with ethanol three times; (3) The graphite obtained in step (2) was mixed with nano boron carbide, modified silicon dioxide, and nanofiber in a mass ratio of 1:0.07:0.5:0.3 in a high-speed mixer for 15 minutes to obtain modified graphite powder; The modified silica is modified by placing silica powder in a fluidized bed reactor, evacuating the air with nitrogen, introducing heptadecafluorodecyltrimethoxysilane vapor at 120° C. for 20 minutes, stopping the ventilation, and cooling to obtain the modified silica.

[0023] The preparation method of the novel thermal insulation material comprises the following steps: S1. The polystyrene particles, modified graphite powder, methyl octabromoether and ethanol were added to a high-speed mixer in proportion and stirred thoroughly at 1200 rpm to obtain a mixture; S2. The mixture is heated to 180-220°C through a twin-screw extruder to melt and plasticize the polystyrene particles. Freon is then injected into the extruder through a high-pressure injection device (pressure 12 MPa, temperature 60°C) to form a uniform melt. S3. The melt is extruded through the extruder head, at which point the pressure drops sharply, the foaming agent rapidly vaporizes and expands, forming a large number of uniform and dense bubble structures, and rapidly cooled in a water bath; S4. Cut the shaped sheet into finished sheets of specified size according to the requirements; S5. After the finished boards are placed for 48 hours, they are inspected, packaged and put into storage.

[0024] Example 3 A novel thermal insulation material, comprising the following raw material components in parts by weight: 80 parts of polystyrene particles; 7 parts of methyl octabromoether; 1 part ethanol; 5 parts of Freon; 16 parts of modified graphite powder; Wherein, the preparation steps of modified graphite powder are: (1) Graphite powder was mixed with mixed acid (concentrated sulfuric acid and nitric acid volume ratio 3:1) at a solid-liquid ratio of 1:3, ultrasonically treated for 2 h, washed with water until neutral, and then dried; (2) The pretreated graphite was mixed with 6% heptafluorodecyltrimethoxysilane and placed in a ball mill, nitrogen was introduced to replace the air, and the mixture was ground at 500 rpm for 2 h, followed by washing with ethanol three times; (3) The graphite obtained in step (2) was mixed with nano-boron carbide, modified silicon dioxide, and nanofiber in a mass ratio of 1:0.1:0.6:0.4 in a high-speed mixer for 10 minutes to obtain modified graphite powder; The modified silica is modified by placing silica powder in a fluidized bed reactor, evacuating the air with nitrogen, introducing heptadecafluorodecyltrimethoxysilane vapor at 125° C. for 15 minutes, stopping the ventilation, and cooling to obtain the modified silica.

[0025] The preparation method of the novel thermal insulation material comprises the following steps: S1. The polystyrene particles, modified graphite powder, methyl octabromoether and ethanol were added to a high-speed mixer in proportion and stirred thoroughly at 1500 rpm to obtain a mixture; S2. The mixture is heated to 180-220°C through a twin-screw extruder to melt and plasticize the polystyrene particles. Freon is then injected into the extruder through a high-pressure injection device (pressure 12 MPa, temperature 60°C) to form a uniform melt. S3. The melt is extruded through the extruder head, at which point the pressure drops sharply, the foaming agent rapidly vaporizes and expands, forming a large number of uniform and dense bubble structures, and rapidly cooled in a water bath; S4. Cut the shaped sheet into finished sheets of specified size according to the requirements; S5. After the finished boards are placed for 48 hours, they are inspected, packaged and put into storage.

[0026] Comparative Example 1 A new type of thermal insulation material is different from Example 1 in that the graphite powder used is not modified, and other preparation methods are the same.

[0027] Comparative Example 2 A novel thermal insulation material is different from Example 1 in that the modified graphite powder used is not subjected to step (2) during modification, and the other preparation methods are the same.

[0028] Comparative Example 3 A novel thermal insulation material is different from Example 1 in that the modified graphite powder used is not subjected to step (3) during modification, and the other preparation methods are the same.

[0029] Comparative Example 4 A novel thermal insulation material is different from Example 1 in that the silicon dioxide in step (3) of the modified graphite powder used in the modification is unmodified silicon dioxide, and the other preparation methods are the same.

[0030] Comparative Example 5 A thermal insulation material, commercially available ordinary XPS extruded board.

[0031] Test example 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 method of GB / T 10294-2008, and the compressive strength, combustion performance grade, and volume water absorption were determined according to the relevant method of JG / T536-2017. Table 1 Performance test

[0032] It can be seen from the results in Table 1 that the new thermal insulation material prepared by the method of the present invention has a higher closed porosity, lower thermal conductivity, better compressive strength, higher flame retardant grade, and better waterproof performance than comparative examples 1-5, and is an excellent thermal insulation material.

[0033] In Comparative Examples 1-4, since the silica was not modified or the modification methods were different, their performance was affected to a certain extent. It is very likely that the silica that was not modified according to the present invention had poor dispersibility after being mixed with PS and foaming agent, and affected the formation of closed-cell structure in the subsequent foaming process, thereby affecting the overall performance of the material.

[0034] 2. The new insulation material obtained in Example 1 and the commercially available XPS extruded board in Comparative Example 5 were used to make cold storage panels with the same insulation requirements (±30°C). The thickness of the two cold storage panels was then measured, and the results are shown in Table 2. The cold storage panels were prepared as follows: first, fiberglass reinforced plastic was laid flat on the panel-making platform; then, a pre-prepared two-component polyurethane composite adhesive was evenly applied to the fiberglass surface using a glue dispenser; then, the prepared insulation materials (Example 1 and Comparative Example 5) were laid flat on the glued fiberglass reinforced plastic; then, the two-component polyurethane composite adhesive was evenly applied to the new insulation material using a glue dispenser; then, the fiberglass reinforced plastic was placed over the glued new insulation material; and finally, the cold storage panels were fed into a press via a mechanical transmission chain for positive pressure lamination to obtain the cold storage panels.

[0035] Table 2 Thickness comparison

[0036] From the results in Table 2, it can be seen that the new thermal insulation material prepared by the present invention has an extremely low thermal conductivity. Under the same thermal insulation requirements, the thickness of the refrigeration board made can be greatly reduced compared with the ordinary XPS extruded board purchased on the market. This not only saves the use space, but also reduces the dead weight. When used in refrigerated compartments, it can improve transportation efficiency.

[0037] Finally, it should be emphasized that the above 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 may have various changes and modifications. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A new type of thermal insulation material, characterized in that: The novel thermal insulation material comprises the following raw material components in parts by weight: 70-80 parts of polystyrene particles; 5-7 parts of methyl octabromoether; 0.5-1 part of ethanol; 2-5 parts of Freon; 14-16 parts of modified graphite powder.

2. A new thermal insulation material according to claim 1, characterized in that: The preparation steps of the modified graphite powder are: (1) Mix graphite powder and mixed acid and ultrasonically treat for 2-3 hours, wash with water until neutral and then dry; (2) The pretreated graphite and heptafluorodecyltrimethoxysilane were mixed and placed in a ball mill, nitrogen was introduced to replace the air, and the mixture was ground at 400-500 rpm for 2-3 hours, and then washed with ethanol 2-3 times; (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 minutes to obtain modified graphite powder.

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

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

5. A new type of thermal insulation material according to claim 2, characterized in that: In step (3), the mass ratio of the graphite to nano-boron carbide, modified silicon dioxide, and nanofiber is 1:(0.05-0.1):(0.3-0.6):(0.2-0.4).

6. A new type of thermal insulation material according to claim 2 or 5, characterized in that: The modified silica is modified by placing silica powder in a fluidized bed reactor, evacuating the air with nitrogen, introducing heptadecafluorodecyltrimethoxysilane vapor at 110-125° C. for 15-25 minutes, stopping the ventilation, and cooling to obtain the modified silica.

7. A method for preparing a novel thermal insulation material according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: S1. The polystyrene particles, modified graphite powder, methyl octabromoether and ethanol were added to a high-speed mixer in proportion and stirred thoroughly to obtain a mixture; S2. The mixture is heated to 180-220°C through a twin-screw extruder to melt and plasticize the polystyrene particles, and the 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 sheet into finished sheets of specified size according to the requirements; S5. After the finished boards are placed for 24-48 hours, they are inspected, packaged and put into storage.

8. The method for preparing a novel thermal insulation material according to claim 7, 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°C.

9. A refrigeration plate, characterized in that: The thermal insulation material is made of glass fiber reinforced plastic and the novel thermal insulation material according to any one of claims 1 to 6.

10. A refrigeration plate according to claim 9, characterized in that: The specific production method is: first spread the fiberglass reinforced plastic flat on the plate making equipment platform, then use the glue spraying machine to evenly spread the prepared two-component polyurethane composite glue on the fiberglass surface, and then spread the prepared new thermal insulation material flat on the fiberglass reinforced plastic sprayed with glue, and then use the glue spraying machine to evenly spread the two-component polyurethane composite glue on the new thermal insulation material, and then cover the fiberglass reinforced plastic on the new thermal insulation material sprayed with glue, and finally send it into the pressing plate equipment through a mechanical transmission chain for positive pressure compounding to obtain a refrigerated plate.

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