Straw powder-based hot-press molded heat-conducting plate and preparation method thereof

Abstract

The invention discloses a straw powder-based hot-press molded heat-conducting plate and a preparation method thereof.The heat-conducting plate comprises modified straw powder, an acrylate oligomer, an acrylate monomer, an initiator and other raw materials, and the preparation process comprises the steps that firstly, the straw powder is modified through a coupling agent and a modifying agent, then modified straw slurry is prepared, and the modified straw slurry is subjected to hot-press molding to obtain the straw powder-based hot-press molded heat-conducting plate. The prepared board is high in heat conductivity coefficient, large in hardness, good in hydrophobic effect and capable of retarding flame, can replace wood to be applied to the fields of stairs, floors, beam columns, doors and windows, roofs, tables and chairs, beds, cabinets, sofas and the like, and has wide market application prospects.

Description

Technical Field

[0001] The invention relates to a heat-conducting plate, in particular to a straw powder-based hot-pressed heat-conducting plate and a preparation method thereof; and belongs to the technical field of new materials and preparation thereof. Background Art

[0002] Thermally conductive sheet is a new type of sheet that combines efficient heat conduction with comfortable touch. In recent years, it has been widely used in home decoration and commercial space design. However, in the face of the increasing depletion of natural forest resources and the tight supply of logs, finding sustainable and high-performance alternative materials has become an urgent problem to be solved in the industry. In this context, straw has become an ideal choice to replace traditional wood due to its renewable and environmental advantages. Crop straw resources are abundant and can replace wood to make artificial boards, which can not only reduce the number of deforestation and alleviate the growing contradiction between supply and demand, but also provide a new channel for the comprehensive utilization of straw and reduce environmental pollution caused by straw burning in the field. Straw artificial board not only does not release formaldehyde, but also has excellent physical and chemical properties, high strength, bending resistance, moisture resistance, flame retardancy and aging resistance are better than general artificial boards. It can replace traditional artificial boards and can be used in furniture manufacturing, decoration and other fields.

[0003] Straw, as the raw material of heat-conducting board, can reduce the dependence on natural wood and promote the recycling of resources on the basis of meeting the heat-conducting performance. The application of straw in the research of building materials can not only effectively reduce the discharge of agricultural waste, but also provide a green and environmentally friendly alternative for the production of wood flooring materials. The invention patent with application number 200910182040.1 discloses a straw-based board, which contains a waterproof adhesive and a flame retardant, and is obtained by curing and molding after the plant straw is evenly mixed at room temperature. The straw-based board is made of plant straw cut into a certain size and shape and a resin adhesive. The surface of the straw-based board is bonded with a decorative layer, and a transparent waterproof, fireproof and wear-resistant layer is bonded outside the surface decorative layer. It is a solid straight board or a solid special-shaped board. The invention patent with application number CN201510997094.9 discloses a composite wood flooring material. The straw-based board material comprises, from top to bottom, an impregnated paper, a herbaceous plant fiber layer and a composite wood layer. The surface of the impregnated paper is processed to have imitation wood grain. The composite wood layer consists of two layers, the upper layer is a board made of horizontally placed coniferous wood, and the lower layer is a board made of vertically arranged broad-leaved wood. The plant fiber layer is pressed from straw fiber or reed stem fiber. However, the manufacturing method of the straw-based board material is relatively complicated and has a single function.

[0004] With the development of society and the advancement of science and technology, straw-based boards need to have not only good strength but also simple preparation methods to achieve industrial application. In addition, straw-based boards mainly replace wood and are widely used in floors, stairs, beams, doors and windows, roofs, tables and chairs, beds, cabinets, sofas and other fields. When used as floors, the widespread use of floor heating needs to be considered, requiring the boards to have good thermal conductivity to meet energy-saving needs.

[0005] In view of the above reasons, the development of thermally conductive panels with high strength and simple preparation methods, as well as excellent properties such as thermal conductivity, scratch resistance, and weather resistance, has become a development trend for straw-based panels. Summary of the invention

[0006] In order to overcome the deficiencies in the prior art, the purpose of the present invention is to provide a straw powder-based hot-pressed thermally conductive plate and a preparation method thereof, so as to improve the thermal conductivity of the thermally conductive plate, thereby achieving the purpose of shortening the heat transfer time and reducing energy consumption. The preparation method is simple and easy to implement, and is convenient for industrial promotion and application.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] The present invention first discloses a straw powder-based hot-pressed thermally conductive plate, which is prepared by hot-pressing the following raw materials in parts by weight: 100 to 150 parts of modified straw powder, 5 to 20 parts of acrylate oligomers, 10 to 50 parts of acrylate monomers and 0.2 to 1 part of initiator; the straw powder is selected from one or more of corn straw powder, wheat straw powder, pine straw powder, soybean straw powder and peanut straw powder.

[0009] Preferably, the modified straw powder is prepared by stirring and mixing 100 parts by mass of straw powder, 0.1-0.5 parts by mass of silane coupling agent, and 10-40 parts by mass of modifier, and reacting at elevated temperature.

[0010] More preferably, the aforementioned acrylate monomer is one or more of methyl methacrylate, methacrylate, hydroxyethyl methacrylate, lauryl methacrylate, hexanediol acrylate and polyethylene glycol acrylate.

[0011] More preferably, the acrylate oligomer is selected from the group consisting of polyurethane acrylate oligomer, polyester acrylate oligomer, epoxy acrylate oligomer and silicone acrylate oligomer.

[0012] More preferably, the aforementioned modifier is selected from one or more of carbon nanotubes, boron nitride, aluminum oxide, silicon carbide, and graphene, which can improve the thermal conductivity, flame retardancy and other properties of the material.

[0013] Preferably, the average particle size of the aforementioned modifier is 0.05 to 1 μm. Nano-scale modifiers have a reinforcing function, but are expensive, so in practical applications, considering the actual conditions such as cost, micro-scale modifiers are preferred, such as boron nitride with an average particle size of 1 μm.

[0014] More preferably, the silane coupling agent is one of vinyltriethoxysilane, vinyltrimethoxysilane, methacryloxypropyltrimethoxysilane and acryloxytriisopropylsilane.

[0015] More preferably, the initiator is a peroxide initiator or an azo initiator.

[0016] The present invention also discloses a method for preparing a straw powder-based hot-pressed heat-conducting plate as described above, the method comprising the following steps:

[0017] S1. Preparation of modified straw powder

[0018] Add 100 parts by mass of straw powder, 0.1-0.5 parts by mass of silane coupling agent, and 10-40 parts by mass of modifier into a reaction kettle, heat to 100-110° C., stir and react for 1-3 hours, cool to room temperature, discharge, and obtain modified straw powder;

[0019] S2. Preparation of Acrylate Reaction Solution

[0020] Add 5-20 parts by weight of acrylate oligomer, 10-50 parts by weight of acrylate monomer, and 0.2-1 parts by weight of initiator into a reaction kettle, and stir at room temperature for 0.5-1 hour to obtain an acrylate reaction solution;

[0021] S3. Preparation of modified straw slurry

[0022] First, add the modified straw powder prepared in step S1 into the stirring kettle, start stirring, slowly add the acrylate reaction solution prepared in step S2 within 10-30 minutes, continue stirring for 30-60 minutes, and obtain modified straw slurry;

[0023] S4. Preparation of straw powder-based hot-pressed thermal conductive sheet

[0024] The modified straw slurry prepared in the above step S3 is poured into a mold, and then the mold is placed in a flat plate vulcanizer at 80-120°C, hot-pressed for 10-40 minutes at a pressure of 5-15 MPa in the flat plate vulcanizer, and then the mold is transferred to another flat plate vulcanizer at room temperature for cold pressing for 5-20 minutes to obtain a straw powder-based hot-pressed thermal conductive plate.

[0025] More preferably, the modifier is boron nitride with an average particle size of 1 μm, which can achieve more excellent thermal conductivity.

[0026] The present invention is beneficial in that:

[0027] (1) The raw materials used in the heat-conducting plate of the present invention are all environmentally friendly, so the heat-conducting plate finally produced does not release formaldehyde and can be used in the fields of floors, stairs, beams, doors and windows, roofs, tables and chairs, beds, cabinets, sofas, etc.;

[0028] (2) In the preparation method of the present invention, the siloxane group of the coupling agent reacts with the hydroxyl groups on the surface of the straw powder and the modifier to modify the straw powder, thereby optimizing the dispersibility and stability of the straw powder in the acrylate reaction solution, thereby improving the thermal conductivity and flame retardancy;

[0029] (3) In the straw powder-based hot pressing process, the acrylate oligomer will react chemically with the acrylate monomer during curing to form a stable chemical bond, and will form a tight bond with the modifier, thereby giving the board excellent properties such as high thermal conductivity, thermal stability, waterproofness and high hardness;

[0030] (4) The hot pressing process of the present invention can not only improve the curing efficiency of the thermal conductive sheet, but also further improve the qualified rate and strength of the thermal conductive sheet. The physical and chemical properties of the obtained sheet are very excellent. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is an infrared thermal imaging photo of the plate of Example 1;

[0032] Figure 2 is an infrared thermal imaging photograph of the plate of Example 1;

[0033] Figure 3 This is a flame retardant test diagram of the board of comparative example 1;

[0034] Figure 4 This is a flame retardant test diagram of the board in Example 1;

[0035] Figure 5 is a hardness test diagram of the plate material of Example 1;

[0036] Figure 6 This is a contact angle test diagram of the plate of Example 3. DETAILED DESCRIPTION

[0037] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] Example 1

[0039] S1. Preparation of modified straw powder

[0040] 100 parts by mass of soybean straw powder, 0.1 parts by mass of vinyltriethoxysilane, and 10 parts by mass of silicon carbide with a size of 50 nm were added to a reactor, the temperature was raised to 100° C., the reaction was carried out for 3 hours, the reaction was cooled to room temperature, and the modified straw powder was obtained.

[0041] S2. Preparation of Acrylate Reaction Solution

[0042] 5 parts by mass of epoxy acrylate oligomer, 10 parts by mass of hydroxyethyl methacrylate, and 0.2 parts by mass of azobisisobutyronitrile were added to a reaction vessel, and the mixture was stirred at room temperature for 0.5 hours to obtain an acrylate reaction solution.

[0043] S3. Preparation of modified straw slurry

[0044] First, the modified straw powder prepared above was added into a stirring kettle, stirring was started, and the acrylate reaction solution prepared above was slowly added within 10 minutes, and stirring was continued for 30 minutes to obtain a modified straw slurry.

[0045] S4. Preparation of straw powder-based hot-pressed thermal conductive sheet

[0046] The modified straw slurry prepared above was placed in a mold, and then the mold was placed in a flat-plate vulcanizer at 80°C, hot-pressed for 40 minutes at a pressure of 5 MPa in the flat-plate vulcanizer, and then the mold was transferred to another flat-plate vulcanizer at room temperature and cold-pressed for 5 minutes to obtain a straw powder-based hot-pressed thermal conductive plate.

[0047] Example 2

[0048] S1. Preparation of modified straw powder

[0049] 100 parts by mass of wheat straw powder, 0.5 parts by mass of methacryloyloxypropyltrimethoxysilane, and 20 parts by mass of 500 nm aluminum oxide were added to a reactor, the temperature was raised to 105° C., the reaction was performed for 2 hours, the reactor was cooled to room temperature, and the modified straw powder was obtained.

[0050] S2. Preparation of Acrylate Reaction Solution

[0051] 10 parts by mass of polyester acrylate oligomer, 15 parts by mass of hexanediol acrylate, and 0.5 parts by mass of dibenzoyl peroxide were added to a reaction vessel, and the mixture was stirred at room temperature for 0.7 hours to obtain an acrylate reaction solution.

[0052] S3. Preparation of modified straw slurry

[0053] First, the modified straw powder prepared above was added to a stirring kettle, stirring was started, and the acrylate reaction solution prepared above was slowly added within 20 minutes, and stirring was continued for 45 minutes to obtain a modified straw slurry.

[0054] S4. Preparation of straw powder-based hot-pressed thermal conductive sheet

[0055] The modified straw slurry prepared above was placed in a mold, and then the mold was placed in a flat-plate vulcanizer at 100°C, hot-pressed for 20 minutes at a pressure of 10 MPa in the flat-plate vulcanizer, and then the mold was transferred to another flat-plate vulcanizer at room temperature and cold-pressed for 10 minutes to obtain a straw powder-based hot-pressed thermal conductive plate.

[0056] Example 3

[0057] S1. Preparation of modified straw powder

[0058] 100 parts by mass of corn straw powder, 0.5 parts by mass of acryloxytriisopropylsilane, and 40 parts by mass of 1 μm boron nitride were added to a reactor, the temperature was raised to 110° C., the reaction was performed for 1 hour, the reaction was cooled to room temperature, and the material was discharged to obtain modified straw powder.

[0059] S2. Preparation of Acrylate Reaction Solution

[0060] 20 parts by mass of epoxy acrylate oligomer, 25 parts by mass of lauryl methacrylate, 25 parts by mass of hexanediol acrylate, and 1 part by mass of azobisisobutyronitrile were added to a reaction vessel, and the mixture was stirred at room temperature for 1 hour to obtain an acrylate reaction solution.

[0061] S3. Preparation of modified straw slurry

[0062] First, the modified straw powder prepared above was added to a stirring kettle, stirring was started, and the acrylate reaction solution prepared above was slowly added within 30 minutes, and stirring was continued for 60 minutes to obtain a modified straw slurry.

[0063] S4. Preparation of straw powder-based hot-pressed thermal conductive sheet

[0064] The modified straw slurry prepared above was placed in a mold, and then the mold was placed in a flat-plate vulcanizer at 120°C, hot-pressed for 10 minutes at a pressure of 15 MPa in the flat-plate vulcanizer, and then the mold was transferred to another flat-plate vulcanizer at room temperature and cold-pressed for 20 minutes to obtain a straw powder-based hot-pressed thermal conductive plate.

[0065] Comparative Example 1

[0066] S1. Preparation of modified straw powder

[0067] 100 parts by mass of soybean straw powder and 0.1 parts by mass of vinyltriethoxysilane were added to a reaction kettle, the temperature was raised to 100° C., the reaction was carried out for 3 hours, the reaction was cooled to room temperature, and the material was discharged to obtain modified straw powder.

[0068] S2. Preparation of Acrylate Reaction Solution

[0069] 5 parts by mass of epoxy acrylate oligomer, 10 parts by mass of hydroxyethyl methacrylate, and 0.2 parts by mass of azobisisobutyronitrile were added to a reaction vessel, and the mixture was stirred at room temperature for 0.5 hours to obtain an acrylate reaction solution.

[0070] S3. Preparation of modified straw slurry

[0071] First, the modified straw powder prepared above was added into a stirring kettle, stirring was started, and the acrylate reaction solution prepared above was slowly added within 10 minutes, and stirring was continued for 30 minutes to obtain a modified straw slurry.

[0072] S4. Preparation of straw powder-based hot-pressed boards

[0073] The modified straw slurry prepared above was placed in a mold, and then the mold was placed in a flat-plate vulcanizer at 80°C, hot-pressed for 40 minutes at a pressure of 5 MPa in the flat-plate vulcanizer, and then the mold was transferred to another flat-plate vulcanizer at room temperature and cold-pressed for 5 minutes to obtain a straw powder-based hot-pressed molded board.

[0074] Performance Testing

[0075] The following performance tests were performed on the straw composite boards of Examples 1-3 and Comparative Example 1:

[0076] (1) Thermal conductivity test: The thermal conductivity of the board is tested using a thermal conductivity tester according to the American standard "ASTM-D5470".

[0077] (2) Hardness test: Use a Shore hardness tester to test the hardness of the plate according to the national standard "GB / T 3398.2-2008".

[0078] (3) Contact angle test: The static contact angle method is used, that is, a certain amount of deionized water is dropped on the surface of the plate, and the angle between the edge of the droplet and the solid surface is measured by a contact angle tester.

[0079] The test results are shown in Table 1 below:

[0080] Serial number <![CDATA[Thermal conductivity (W·m -1 ·K -1 )]]> Hardness (HD) Contact angle (°) Example 1 1.50 74 135 Example 2 1.98 78 140 Example 3 2.79 80 156 Comparative Example 1 0.19 54 100

[0081] Table 1 Performance test results of Examples 1-3 and Comparative Example 1

[0082] As can be seen from Table 1, the thermal conductivity, hardness and contact angle of the straw composite board of Examples 1-3 are significantly improved compared with that of Comparative Example 1, which shows that the addition of the modifier has a crucial effect on the thermal conductivity and hardness of the material.

[0083] also, Figure 1 and Figure 2The infrared thermal imaging photos show that under the same temperature conditions and the same time, the heat transfer of the plate in Example 1 is faster than that of Comparative Example 1. Figure 3 and 4 The burning conditions of Comparative Example 1 and Example 1 were recorded in the time period of 10s-60s. It can be seen from the photos that the plate of Comparative Example 1 has been burned and deformed, and will reignite at any time, but the plate of Example 1 is only carbonized on the surface without any deformation and has not reached the ignition point. This is consistent with the thermal conductivity test data in Table 1 above.

[0084] After analysis, the applicant believes that the significant effect of the modifier on the performance may be due to the following factors:

[0085] (1) During the production process of straw composite boards, the modifier is mixed evenly with straw powder and other necessary adhesives as an additive, which forms additional heat conduction paths in the straw composite boards. These paths enable heat to be transferred through the board more quickly and efficiently, thereby improving the overall thermal conductivity.

[0086] (2) The added modifier plays a role of filling and supporting between the straw powders, making the microstructure of the board more compact and strong. In particular, when micron boron nitride particles are used as modifiers, due to their high hardness, the straw composite board can better resist deformation and breakage when subjected to external forces.

[0087] (3) The addition of modifiers may also increase the friction and cohesion between straw fibers, thereby further increasing the hardness of the board. Figure 5 The test results show that the hardness of the plates of Examples 1-3 can reach 70-80HD.

[0088] (4) The addition of modifiers may also change the surface chemical properties of the straw composite board, reducing its surface energy. The reduction in surface energy usually leads to an increase in the contact angle, that is, the board surface becomes less wettable by water, enhancing the overall hydrophobic effect of the straw composite board, thereby increasing the contact angle, such as Figure 6 As shown, the contact angle of the plate of Example 3 is as high as 156°.

[0089] In summary, the straw powder-based hot-pressed molded board prepared by the present invention has excellent performance, good system compatibility, fast curing speed, high production efficiency, easy industrialization, and wide application. No toxic solvent is released during the entire process, and it has good commercial application prospects.

[0090] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the present invention in any form, and any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present invention.

Claims

1. A straw powder-based hot-pressed thermally conductive sheet material, characterized in that: The invention is prepared by hot pressing the following raw materials in parts by weight: 100-150 parts of modified straw powder, 5-20 parts of acrylate oligomer, 10-50 parts of acrylate monomer and 0.2-1 part of initiator; the straw powder is selected from one or more of corn straw powder, wheat straw powder, pine straw powder, soybean straw powder and peanut straw powder.

2. The straw powder-based hot-pressed thermally conductive sheet material according to claim 1, characterized in that: The modified straw powder is prepared by stirring and mixing 100 parts by mass of straw powder, 0.1-0.5 parts by mass of silane coupling agent and 10-40 parts by mass of modifier and reacting at elevated temperature.

3. The straw powder-based hot-pressed thermally conductive plate material according to claim 1, characterized in that: The acrylate monomer is one or more of methyl methacrylate, methacrylate, hydroxyethyl methacrylate, lauryl methacrylate, hexanediol acrylate and polyethylene glycol acrylate.

4. The straw powder-based hot-pressed thermally conductive sheet material according to claim 1, characterized in that: The acrylate oligomer is selected from one of polyurethane acrylate oligomer, polyester acrylate oligomer, epoxy acrylate oligomer and silicone acrylate oligomer.

5. The straw powder-based hot-pressed thermally conductive plate material according to claim 1, characterized in that: The modifier is selected from one or more of carbon nanotubes, boron nitride, aluminum oxide, silicon carbide, and graphene.

6. The straw powder-based hot-pressed thermally conductive sheet material according to claim 6, characterized in that: The average particle size of the modifier is 0.05 to 1 μm, 50 nm, 100 nm, 500 nm or 1 μm.

7. The straw powder-based hot-pressed thermally conductive plate material according to claim 1, characterized in that: The silane coupling agent is one of vinyl triethoxysilane, vinyl trimethoxysilane, methacryloxypropyl trimethoxysilane and acryloxy triisopropyl silane.

8. The straw powder-based hot-pressed thermally conductive plate material according to claim 1, characterized in that: The initiator is a peroxide initiator or an azo initiator.

9. The method for preparing a straw powder-based hot-pressed thermally conductive plate material according to any one of claims 1 to 9, characterized in that: The steps include: S1. Preparation of modified straw powder Add 100 parts by mass of straw powder, 0.1-0.5 parts by mass of silane coupling agent, and 10-40 parts by mass of modifier into a reaction kettle, heat to 100-110° C., stir and react for 1-3 hours, cool to room temperature, discharge, and obtain modified straw powder; S2. Preparation of Acrylate Reaction Solution Add 5-20 parts by weight of acrylate oligomer, 10-50 parts by weight of acrylate monomer, and 0.2-1 parts by weight of initiator into a reaction kettle, and stir at room temperature for 0.5-1 hour to obtain an acrylate reaction solution; S3. Preparation of modified straw slurry First, add the modified straw powder prepared in step S1 into the stirring kettle, start stirring, slowly add the acrylate reaction solution prepared in step S2 within 10-30 minutes, continue stirring for 30-60 minutes, and obtain modified straw slurry; S4. Preparation of straw powder-based hot-pressed thermal conductive sheet The modified straw slurry prepared in the above step S3 is poured into a mold, and then the mold is placed in a flat plate vulcanizer at 80-120°C, hot-pressed for 10-40 minutes at a pressure of 5-15 MPa in the flat plate vulcanizer, and then the mold is transferred to another flat plate vulcanizer at room temperature for cold pressing for 5-20 minutes to obtain a straw powder-based hot-pressed thermal conductive plate.

10. The method for preparing a straw powder-based hot-pressed thermally conductive plate material according to claim 9, characterized in that: The modifier is boron nitride with an average particle size of 1 μm.

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