Preparation method of bio-based high-performance honeycomb core material

Abstract

The invention discloses a preparation method of a bio-based high-performance honeycomb core material, and relates to the field of composite material preparation. The invention aims to solve the technical problem that a high-performance straw-plastic honeycomb plate cannot be efficiently prepared in a long fiber form in the prior art. The method comprises the steps of straw-plastic composite board preparation, softening, mold pressing, corrugated board softening, assembling and cooling. Biomass does not need to be smashed, and energy consumption of processing and generated dust pollution are reduced; the composite board with high mechanical strength in a specific direction is prepared by utilizing anisotropy of long fibers; the processing technology is simplified, the honeycomb core material is prepared by directly using mature molding technologies such as mold pressing and the like by utilizing the reprocessability of the thermoplastic plastic matrix, and the method has industrialization potential. The method is used for preparing the bio-based high-performance honeycomb core material.

Description

Technical Field

[0001] The present invention relates to the field of composite material preparation. Background Art

[0002] With the rapid development of new materials, extensive research has focused on the topological optimization of material structures. Honeycomb materials, due to their unique hexagonal structure, offer high strength, lightweight construction, and excellent mechanical properties, making them widely used in aerospace, automotive, construction, electronic equipment, and other fields. Currently, honeycomb materials often use non-renewable aluminum, epoxy resin, and other thermosetting polymers as raw materials, seriously violating the trend of energy conservation, emission reduction, and biodegradable materials. Furthermore, due to the complex structure of honeycomb materials, research in this field often uses 3D printing, which is inefficient, energy-intensive, and requires demanding materials.

[0003] Rice is widely cultivated as the world's third-largest cereal crop. According to the Food and Agriculture Organization of the United Nations (FAO), 513.7 million tons of rice straw are produced globally. However, much of this straw is not properly disposed of. Incineration is often the simplest disposal method. Chemically, rice straw is primarily composed of cellulose, hemicellulose, and lignin, with proportions similar to those of wood. Morphologically, rice straw consists of three components: epidermal tissue, vascular tissue, and parenchyma tissue. The epidermal and vascular tissues have small cell lumens and thick cell walls, resulting in excellent mechanical properties. Therefore, research on using rice straw as a raw material to replace wood in the preparation of composite materials has a solid theoretical basis. In most current studies, rice straw is used as a reinforcement material in powder form. This results in significant damage to the straw fibers. Furthermore, large areas of rice straw powder consume more matrix or adhesive. Therefore, the long length of the rice straw must be retained to achieve a fully secure reinforcement effect. Summary of the Invention

[0004] The present invention aims to solve the technical problem that the prior art cannot efficiently prepare high-performance straw-plastic honeycomb panels in the form of long fibers, and provides a method for preparing a bio-based high-performance honeycomb core material.

[0005] The high-performance straw plastic honeycomb panel of the present invention is formed respectively by three methods: film rolling, layered paving and rice straw powder granulation.

[0006] A method for preparing a bio-based high-performance honeycomb core material is specifically carried out in the following steps:

[0007] Step 1: Preparation of straw-plastic composite board:

[0008] The straw-plastic composite board is prepared by using straw, plastic matrix and coupling agent;

[0009] Step 2: Softening:

[0010] The straw-plastic composite board is placed in an infrared heating box at a heating temperature of 100°C to 200°C and softened for 10 seconds to 1 minute to obtain a prepreg sheet;

[0011] Step 3: Molding:

[0012] The prepreg sheet is placed on the corrugated board female mold, and then covered with the male mold. Under the conditions of temperature of 100-200°C and pressing speed of 5-15mm / min, the mold is closed and pressure is maintained for 15s-60s, and the pressure is maintained at 1-5MPa. Then, the mold is cooled to 40-60°C to obtain a high-performance straw plastic corrugated board.

[0013] Step 4: Softening of corrugated board:

[0014] Place the high-performance straw plastic corrugated sheet prepared in step 3 flat on a hot plate at a hot pressing temperature of 100°C to 200°C, and soften the wave crests by contact with the hot plate;

[0015] Step 5: Assembly:

[0016] The softened high-performance straw plastic corrugated sheets are stacked and assembled, and the crests of adjacent high-performance straw plastic corrugated sheets are controlled to face each other and fully contact during assembly, and the sheets are bonded using the softened thermoplastic matrix on the surface;

[0017] Step 6: Cooling:

[0018] The matrix is fully cooled until it is completely solidified to obtain the bio-based high-performance honeycomb core material.

[0019] Furthermore, the method for preparing the straw-plastic composite board in step 1 is:

[0020] Step A, drying:

[0021] The dust and fragile leaves in the straw are blown away by a fan, and the straw is dried to a mass moisture content of less than 3% at a temperature of 60℃ to 105℃;

[0022] Step B, film rolling:

[0023] The dried straw is evenly arranged on a plastic film, and coupling agent powder is evenly sprayed on the film. Then, the plastic film and the straw on the film are rolled up unilaterally perpendicular to the direction of the straw arrangement to obtain a straw / plastic straw roll;

[0024] The mass fraction of the plastic film is 10% to 50%, and the mass fraction of the coupling agent is 1% to 10%;

[0025] Step C: Paving:

[0026] Arrange straw / plastic straw rolls in parallel in a mold to obtain a paved straw roll slab;

[0027] Step D, hot pressing:

[0028] The straw roll blank laid in step C is covered with release paper and a metal pad, and then placed in a hot press. Under the condition of a temperature of 100-180°C, it is pre-pressed for 1-60s with a pre-pressing pressure of 0.1-1MPa, and then hot-pressed. The hot-pressing time is controlled to be 30-60s / mm according to the thickness, and the hot-pressing pressure is 1-5MPa. After trimming, the straw-plastic composite board is obtained.

[0029] Furthermore, the method for preparing the straw-plastic composite board in step 1 is:

[0030] Step A, drying:

[0031] The dust and fragile leaves in the straw are blown away by a fan, and then dried at a temperature of 60℃ to 100℃ to a mass moisture content of less than 3%;

[0032] Step B: Cutting:

[0033] Cut the dried straw into 150-200 mm lengths, and cut the plastic film into (150-200) mm × (150-200) mm squares;

[0034] Step C: Layered Paving:

[0035] Arrange the straw evenly and orientably on the plastic film, spray the coupling agent evenly, repeat the operation, and stack 10 to 30 layers of plastic film and straw in an alternating order to form a slab, and then place it in a mold;

[0036] The mass fraction of the plastic film is 10% to 50%, and the mass fraction of the coupling agent is 1% to 10%;

[0037] Step D, hot pressing:

[0038] The slab laid in step C is covered with release paper and a metal pad, and then placed in a hot press. Under the condition of a temperature of 100-180°C, pre-pressing is performed for 1-60 seconds with a pre-pressing pressure of 0.1-1 MPa, and then hot pressing is performed. The hot pressing time is controlled to be 30-60 seconds / mm according to the thickness, and the hot pressing pressure is controlled to be 1-5 MPa. After trimming, the straw-plastic composite board is obtained.

[0039] Furthermore, the method for preparing the straw-plastic composite board in step 1 is:

[0040] Step A, drying:

[0041] The dust and fragile leaves in the straw are blown away by a fan, and then dried at a temperature of 60℃ to 100℃ to a mass moisture content of less than 3%;

[0042] Step B, crushing:

[0043] The straw is processed into powder using a crusher, and the size of the crushed straw powder is 30 to 100 meshes;

[0044] Step C, mixing and granulation:

[0045] The straw powder, plastic particles and coupling agent particles are mixed evenly in a high-speed mixer, and then fed into an extruder for blending and granulation to obtain straw-plastic composite particles;

[0046] The mass fraction of the plastic particles is 10% to 50%, and the mass fraction of the coupling agent particles is 1% to 10%;

[0047] Step D, hot pressing:

[0048] The straw-plastic composite particles prepared in step C are placed in a mold, covered with release paper and a metal pad, and then placed in a hot press. Under the condition of a temperature of 100-180° C., they are pre-pressed for 1-60 seconds with a pre-pressing pressure of 0.1-1 MPa, and then hot-pressed. The hot-pressing time is controlled to be 30-60 seconds / mm according to the thickness, and the hot-pressing pressure is 1-5 MPa. After trimming, a straw-plastic composite board is obtained.

[0049] Furthermore, the straw in step 1 is rice straw, wheat straw, bamboo fiber, hemp fiber or reed straw.

[0050] Furthermore, in step 1, the plastic matrix is high-density polyethylene, linear low-density polyethylene, polypropylene, polyvinyl chloride or polylactic acid.

[0051] Furthermore, the coupling agent in step 1 is maleic anhydride grafted polyethylene or maleic anhydride grafted polypropylene.

[0052] Beneficial effects of the present invention:

[0053] The present invention uses various uncrushed crop processing residues (rice straw, wheat straw, bamboo fiber, hemp fiber, etc.) as reinforcements and thermoplastic plastics (polyethylene, polypropylene, polylactic acid, etc.) as a matrix. The biomass fibers are wrapped with the above-mentioned plastic film into rolls and assembled, or plastic film and biomass fibers are laid layer by layer to assemble, and long fiber reinforced bio-based composite materials are prepared by hot pressing and other molding methods. The prepared board is used as a prepreg, and a honeycomb core material can be obtained after molding. The present invention does not require the crushing of biomass, reducing processing energy consumption and dust pollution; utilizing the anisotropy of long fibers to prepare composite boards with high mechanical strength in a specific direction; simplifying the processing technology, utilizing the reproducibility of the thermoplastic plastic matrix, and directly using mature molding processes such as molding to prepare honeycomb core materials, which has the potential for industrialization.

[0054] The method of the present invention is used for preparing bio-based high-performance honeycomb core material. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 Multi-angle photos of the bio-based high-performance honeycomb core material prepared for the example;

[0056] Figure 2 A photo of a bio-based high-performance honeycomb core material made with different types of natural biomass fibers as reinforcement;

[0057] Figure 3 Compression curve diagram of bio-based high-performance honeycomb core material prepared in Example;

[0058] Figure 4 This is a graph showing the compressive strength of a bio-based high-performance honeycomb core material prepared in this example. DETAILED DESCRIPTION

[0059] Specific embodiment 1: This embodiment provides a method for preparing a bio-based high-performance honeycomb core material, which is specifically carried out in the following steps:

[0060] Step 1: Preparation of straw-plastic composite board:

[0061] The straw-plastic composite board is prepared by using straw, plastic matrix and coupling agent;

[0062] Step 2: Softening:

[0063] The straw-plastic composite board is placed in an infrared heating box at a heating temperature of 100°C to 200°C and softened for 10 seconds to 1 minute to obtain a prepreg sheet;

[0064] Step 3: Molding:

[0065] The prepreg sheet is placed on the corrugated board female mold, and then covered with the male mold. Under the conditions of temperature of 100-200°C and pressing speed of 5-15mm / min, the mold is closed and pressure is maintained for 15s-60s, and the pressure is maintained at 1-5MPa. Then, the mold is cooled to 40-60°C to obtain a high-performance straw plastic corrugated board.

[0066] Step 4: Softening of corrugated board:

[0067] Place the high-performance straw plastic corrugated sheet prepared in step 3 flat on a hot plate at a hot pressing temperature of 100°C to 200°C, and soften the wave crests by contact with the hot plate;

[0068] Step 5: Assembly:

[0069] The softened high-performance straw plastic corrugated sheets are stacked and assembled, and the crests of adjacent high-performance straw plastic corrugated sheets are controlled to face each other and fully contact during assembly, and the sheets are bonded using the softened thermoplastic matrix on the surface;

[0070] Step 6: Cooling:

[0071] The matrix is fully cooled until it is completely solidified to obtain the bio-based high-performance honeycomb core material.

[0072] Specific embodiment 2: This embodiment differs from the specific embodiment 1 in that the method for preparing the straw-plastic composite board in step 1 is:

[0073] Step A, drying:

[0074] The dust and fragile leaves in the straw are blown away by a fan, and the straw is dried to a mass moisture content of less than 3% at a temperature of 60℃ to 105℃;

[0075] Step B, film rolling:

[0076] The dried straw is evenly arranged on a plastic film, and coupling agent powder is evenly sprayed on the film. Then, the plastic film and the straw on the film are rolled up unilaterally perpendicular to the direction of the straw arrangement to obtain a straw / plastic straw roll;

[0077] The mass fraction of the plastic film is 10% to 50%, and the mass fraction of the coupling agent is 1% to 10%;

[0078] Step C: Paving:

[0079] Arrange straw / plastic straw rolls in parallel in a mold to obtain a paved straw roll slab;

[0080] Step D, hot pressing:

[0081] The straw roll slab prepared in step C is covered with release paper and a metal backing plate, then placed in a hot press. Pre-pressing is performed at a temperature of 100-180°C for 1-60 seconds at a pre-pressing pressure of 0.1-1 MPa. Hot pressing is then performed, with the hot pressing time controlled to 30-60 seconds / mm and the hot pressing pressure being 1-5 MPa depending on the thickness. After trimming, the straw-plastic composite board is obtained. Other aspects are the same as those in the first embodiment.

[0082] Specific embodiment three: This embodiment differs from specific embodiment one or two in that: the method for preparing the straw-plastic composite board in step one is:

[0083] Step A, drying:

[0084] The dust and fragile leaves in the straw are blown away by a fan, and then dried at a temperature of 60℃ to 100℃ to a mass moisture content of less than 3%;

[0085] Step B: Cutting:

[0086] Cut the dried straw into 150-200 mm lengths, and cut the plastic film into (150-200) mm × (150-200) mm squares;

[0087] Step C: Layered Paving:

[0088] Arrange the straw evenly and orientably on the plastic film, spray the coupling agent evenly, repeat the operation, and stack 10 to 30 layers of plastic film and straw in an alternating order to form a slab, and then place it in a mold;

[0089] The mass fraction of the plastic film is 10% to 50%, and the mass fraction of the coupling agent is 1% to 10%;

[0090] Step D, hot pressing:

[0091] The slab prepared in step C is covered with release paper and a metal backing plate, then placed in a hot press. Pre-pressing is performed at a temperature of 100-180°C for 1-60 seconds at a pre-pressing pressure of 0.1-1 MPa. Hot pressing is then performed, with the hot pressing time controlled to 30-60 seconds / mm and the hot pressing pressure being 1-5 MPa depending on the thickness. After trimming, the straw-plastic composite board is obtained. Other aspects are the same as in the first or second embodiment.

[0092] Specific embodiment 4: This embodiment differs from any one of specific embodiments 1 to 3 in that: the method for preparing the straw-plastic composite board in step 1 is:

[0093] Step A, drying:

[0094] The dust and fragile leaves in the straw are blown away by a fan, and then dried at a temperature of 60℃ to 100℃ to a mass moisture content of less than 3%;

[0095] Step B, crushing:

[0096] The straw is processed into powder using a crusher, and the size of the crushed straw powder is 30 to 100 meshes;

[0097] Step C, mixing and granulation:

[0098] The straw powder, plastic particles and coupling agent particles are mixed evenly in a high-speed mixer, and then fed into an extruder for blending and granulation to obtain straw-plastic composite particles;

[0099] The mass fraction of the plastic particles is 10% to 50%, and the mass fraction of the coupling agent particles is 1% to 10%;

[0100] Step D, hot pressing:

[0101] The straw-plastic composite particles prepared in step C are placed in a mold, covered with release paper and a metal backing plate, and then placed in a hot press. Under conditions of a temperature of 100-180°C, they are pre-pressed for 1-60 seconds at a pre-pressing pressure of 0.1-1 MPa, and then hot-pressed. The hot-pressing time is controlled to 30-60 seconds / mm according to the thickness, and the hot-pressing pressure is controlled to 1-5 MPa. After trimming, the straw-plastic composite board is obtained. Other steps are the same as those of the first to third embodiments.

[0102] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that the straw in step 1 is rice straw, wheat straw, bamboo fiber, hemp fiber or reed straw. Other aspects are the same as specific embodiments 1 to 4.

[0103] Specific embodiment 6: This embodiment differs from specific embodiments 1 to 5 in that: in step 1, the plastic matrix is high-density polyethylene, linear low-density polyethylene, polypropylene, polyvinyl chloride or polylactic acid. Other aspects are the same as specific embodiments 1 to 5.

[0104] Specific embodiment 7: This embodiment differs from any one of specific embodiments 1 to 6 in that the coupling agent in step 1 is maleic anhydride grafted polyethylene or maleic anhydride grafted polypropylene. Other aspects are the same as any one of specific embodiments 1 to 6.

[0105] The content of the present invention is not limited to the content of the above-mentioned embodiments. The combination of one or more specific embodiments can also achieve the purpose of the invention.

[0106] Example 1:

[0107] This embodiment provides a method for preparing a bio-based high-performance honeycomb core material, which is specifically carried out in the following steps:

[0108] Step 1: Drying:

[0109] After removing dust and fragile leaves from the straw by shaking and colliding, the straw is cut into sections about 200 mm long. The sections are then dried in a forced air drying oven at 80°C to a moisture content of less than 3%.

[0110] Step 2: Roll film:

[0111] According to the ratio of straw mass to LLDPE film ...

[0112] Step 3: Paving:

[0113] Arrange 16 straws / plastic straw rolls in parallel in a mold in two layers to obtain a paved straw roll slab;

[0114] Step 4: Hot pressing:

[0115] The straw roll slab prepared in step 3 is covered with release paper and a metal backing plate, and then placed in a hot press. Under the condition of a temperature of 160°C, pre-pressing is performed for 30 seconds with a pre-pressing pressure of 0.5 MPa, and then hot pressing is performed for 2 minutes with a hot pressing pressure of 1.5 MPa. After cooling to 40°C, the slab is taken out and trimmed to obtain a straw-plastic composite board.

[0116] The mold is a square iron frame with a side length of 165 mm and a thickness of 2 mm;

[0117] Step 5: Softening:

[0118] The straw-plastic composite board was placed in an infrared heating box at a heating temperature of 140°C and softened for 30 seconds to obtain a prepreg sheet;

[0119] Step 6: Molding:

[0120] The prepreg sheet is placed on the female mold of the corrugated board (profile), and then covered with the male mold. Under the conditions of temperature of 160°C and pressing speed of 10mm / min, the mold is closed and pressure is maintained for 30s, the pressure is maintained at 1.5MPa, and then cooled to 40°C to obtain a high-performance straw plastic corrugated board;

[0121] Step 7: Softening of corrugated board:

[0122] Place the high-performance straw plastic corrugated sheet prepared in step 6 flat on a hot plate, heat press at 160°C, soften the corrugated sheet by contact with the hot plate, and place a 200mm×200mm×2mm metal iron plate on the corrugated sheet to ensure full contact between the corrugated sheet and the hot plate;

[0123] Step 8: Assembly:

[0124] The softened high-performance straw plastic corrugated sheets are stacked and assembled, and the crests of adjacent high-performance straw plastic corrugated sheets are controlled to face each other and fully contact during assembly, and the sheets are bonded using the softened thermoplastic matrix on the surface;

[0125] Step 9: Cooling:

[0126] The matrix is fully cooled until it is completely solidified to obtain the bio-based high-performance honeycomb core material.

[0127] In this embodiment, a bio-based high-performance honeycomb core material is prepared by a roll-to-roll process.

[0128] Example 2:

[0129] This embodiment provides a method for preparing a bio-based high-performance honeycomb core material, which is specifically carried out in the following steps:

[0130] Step 1: Drying:

[0131] After removing dust and fragile leaves from the straw by shaking and colliding, the straw is cut into sections about 200 mm long. The sections are then dried in a forced air drying oven at 80°C to a moisture content of less than 3%.

[0132] Step 2: Cutting:

[0133] Cut the dried straw into 165 mm lengths and the plastic film into 165 mm × 165 mm squares;

[0134] Step 3: Layered paving:

[0135] The straw is evenly arranged on the plastic film, and the coupling agent is evenly sprayed. The operation is repeated, and 15 layers are stacked in an alternating order of plastic film and straw to form a slab, which is then placed in a mold.

[0136] The mass fraction of the plastic film is 27%, and the mass fraction of the coupling agent is 3%;

[0137] Step 4: Hot pressing:

[0138] The slab prepared in step 3 is covered with release paper and a metal backing plate, and then placed in a hot press. Under the condition of a temperature of 160°C, pre-pressing is performed for 30 seconds with a pre-pressing pressure of 0.5 MPa, and then hot pressing is performed. The hot pressing time is controlled to 60 seconds / mm according to the thickness, and the hot pressing pressure is 1.5 MPa. After cooling to 40°C, the slab is taken out and trimmed to obtain a straw-plastic composite board.

[0139] The mold is a square iron frame with a side length of 165 mm and a thickness of 2 mm;

[0140] Step 5: Softening:

[0141] The straw-plastic composite board was placed in an infrared heating box at a heating temperature of 140°C and softened for 30 seconds to obtain a prepreg sheet;

[0142] Step 6: Molding:

[0143] The prepreg sheet is placed on the female mold of the corrugated board (profile), and then covered with the male mold. Under the conditions of temperature of 160°C and pressing speed of 10mm / min, the mold is closed and pressure is maintained for 30s, the pressure is maintained at 1.5MPa, and then cooled to 40°C to obtain a high-performance straw plastic corrugated board;

[0144] Step 7: Softening of corrugated board:

[0145] Place the high-performance straw plastic corrugated sheet prepared in step 6 flat on a hot plate, heat press at 160°C, soften the corrugated sheet by contact with the hot plate, and place a 200mm×200mm×2mm metal iron plate on the corrugated sheet to ensure full contact between the corrugated sheet and the hot plate;

[0146] Step 8: Assembly:

[0147] The softened high-performance straw plastic corrugated sheets are stacked and assembled, and the crests of adjacent high-performance straw plastic corrugated sheets are controlled to face each other and fully contact during assembly, and the sheets are bonded using the softened thermoplastic matrix on the surface;

[0148] Step 9: Cooling:

[0149] The matrix is fully cooled until it is completely solidified to obtain the bio-based high-performance honeycomb core material.

[0150] In this embodiment, a bio-based high-performance honeycomb core material is prepared through a layered paving process.

[0151] Example 3:

[0152] This embodiment provides a method for preparing a bio-based high-performance honeycomb core material, which is specifically carried out in the following steps:

[0153] Step 1: Drying:

[0154] After removing dust and fragile leaves from the straw by shaking and colliding, the straw is cut into sections about 200 mm long. The sections are then dried in a forced air drying oven at 80°C to a moisture content of less than 3%.

[0155] Step 2: Crushing:

[0156] The straw is processed into powder using a crusher, and the crushed straw powder has a size of 50 mesh;

[0157] Step 3: Mixing and granulation:

[0158] The straw powder, plastic particles and coupling agent particles are mixed evenly in a high-speed mixer, and then fed into an extruder for blending and granulation to obtain straw-plastic composite particles; wherein the mass fraction of the plastic particles is 27% and the mass fraction of the coupling agent particles is 3%;

[0159] Step 4: Hot pressing:

[0160] The straw-plastic composite particles prepared in step 3 are placed in a mold, covered with release paper and a metal backing plate, and then placed in a hot press. Under the condition of a temperature of 160°C, pre-pressing for 30 seconds with a pre-pressing pressure of 0.5 MPa, and then hot pressing. The hot pressing time is controlled to 60 seconds / mm according to the thickness, and the hot pressing pressure is 1.5 MPa. After cooling to 40°C, the particles are taken out and trimmed to obtain a straw-plastic composite board;

[0161] The mold is a square iron frame with a side length of 165 mm and a thickness of 2 mm;

[0162] Step 5: Softening:

[0163] The straw-plastic composite board was placed in an infrared heating box at a heating temperature of 140°C and softened for 30 seconds to obtain a prepreg sheet;

[0164] Step 6: Molding:

[0165] The prepreg sheet is placed on the female mold of the corrugated board (profile), and then covered with the male mold. Under the conditions of temperature of 160°C and pressing speed of 10mm / min, the mold is closed and pressure is maintained for 30s, the pressure is maintained at 1.5MPa, and then cooled to 40°C to obtain a high-performance straw plastic corrugated board;

[0166] Step 7: Softening of corrugated board:

[0167] Place the high-performance straw plastic corrugated sheet prepared in step 6 flat on a hot plate, heat press at 160°C, soften the corrugated sheet by contact with the hot plate, and place a 200mm×200mm×2mm metal iron plate on the corrugated sheet to ensure full contact between the corrugated sheet and the hot plate;

[0168] Step 8: Assembly:

[0169] The softened high-performance straw plastic corrugated sheets are stacked and assembled, and the crests of adjacent high-performance straw plastic corrugated sheets are controlled to face each other and fully contact during assembly, and the sheets are bonded using the softened thermoplastic matrix on the surface;

[0170] Step 9: Cooling:

[0171] The matrix is fully cooled until it is completely solidified to obtain the bio-based high-performance honeycomb core material.

[0172] In this embodiment, a bio-based high-performance honeycomb core material is prepared by a rice straw powder granulation process.

[0173] Performance test 1. Apparent performance: Figure 1 The following are multi-angle photos of the bio-based high-performance honeycomb core materials prepared in the examples; it can be seen from the figures that Example 1 (rolling film process), Example 2 (layered paving process) and Example 3 (rice straw powder granulation process) can all prepare bio-based high-performance honeycomb core materials.

[0174] Figure 2 This is a physical picture of bio-based high-performance honeycomb core materials prepared using different types of natural biomass fibers as reinforcement.

[0175] Performance test 2. Mechanical properties test:

[0176] The bio-based high-performance honeycomb core material prepared in this example was cut into samples measuring 70 mm in length, 60 mm in width, and 30 mm in thickness, ensuring that each honeycomb specimen contained five complete hexagonal cells. The samples were tested on an electromechanical universal testing machine (CMT5504, MTS Systems, Inc., USA) equipped with a 1000N load cell at a loading rate of 2 mm / min. All tests were conducted at 20 ± 2°C and a humidity of 65% ± 2%. Five samples were selected for each compression test.

[0177] Figure 3 Compression curve diagram of bio-based high-performance honeycomb core material prepared in Example;

[0178] Figure 4 This is a graph showing the compressive strength of a bio-based high-performance honeycomb core material prepared in this example.

[0179] like Figure 4 As shown, the honeycomb prepared in Example 3 has the lowest compressive strength (4.5 MPa), while the compressive strength of the honeycomb core material prepared in Example 2 is 6.1 MPa, and the honeycomb core material prepared in Example 1 has the highest compressive strength, reaching 7.8 MPa. Figure 3 It shows that the honeycomb core material prepared in Example 3 has the weakest ability to resist continuous compressive loads. When the compressive strain is 15%, the material is damaged. The honeycomb core material prepared in Example 1 has the best ability to resist continuous loads. Before the densification stage, it can continuously provide a stress of about 4.3 MPa.

Claims

1. A method for preparing a bio-based high-performance honeycomb core material, characterized in that The method is specifically carried out in the following steps: Step 1: Preparation of straw-plastic composite board: The straw-plastic composite board is prepared by using straw, plastic matrix and coupling agent; Step 2: Softening: The straw-plastic composite board is placed in an infrared heating box at a heating temperature of 100°C to 200°C and softened for 10 seconds to 1 minute to obtain a prepreg sheet; Step 3: Molding: The prepreg sheet is placed on the corrugated board female mold, and then covered with the male mold. Under the conditions of temperature of 100-200°C and pressing speed of 5-15mm / min, the mold is closed and pressure is maintained for 15s-60s, and the pressure is maintained at 1-5MPa. Then, the mold is cooled to 40-60°C to obtain a high-performance straw plastic corrugated board. Step 4: Softening of corrugated board: Place the high-performance straw plastic corrugated sheet prepared in step 3 flat on a hot plate at a hot pressing temperature of 100°C to 200°C, and soften the wave crests by contact with the hot plate; Step 5: Assembly: The softened high-performance straw plastic corrugated sheets are stacked and assembled, and the crests of adjacent high-performance straw plastic corrugated sheets are controlled to face each other and fully contact during assembly, and the sheets are bonded using the softened thermoplastic matrix on the surface; Step 6: Cooling: The matrix is fully cooled until it is completely solidified to obtain the bio-based high-performance honeycomb core material.

2. The method for preparing a bio-based high-performance honeycomb core material according to claim 1, characterized in that The method for preparing the straw-plastic composite board in step 1 is: Step A, drying: The dust and fragile leaves in the straw are blown away by a fan, and the straw is dried to a mass moisture content of less than 3% at a temperature of 60℃ to 105℃; Step B, film rolling: The dried straw is evenly arranged on a plastic film, and coupling agent powder is evenly sprayed on the film. Then, the plastic film and the straw on the film are rolled up unilaterally perpendicular to the direction of the straw arrangement to obtain a straw / plastic straw roll; The mass fraction of the plastic film is 10% to 50%, and the mass fraction of the coupling agent is 1% to 10%; Step C: Paving: Arrange straw / plastic straw rolls in parallel in a mold to obtain a paved straw roll slab; Step D, hot pressing: The straw roll blank laid in step C is covered with release paper and a metal pad, and then placed in a hot press. Under the condition of a temperature of 100-180°C, it is pre-pressed for 1-60s with a pre-pressing pressure of 0.1-1MPa, and then hot-pressed. The hot-pressing time is controlled to be 30-60s / mm according to the thickness, and the hot-pressing pressure is 1-5MPa. After trimming, the straw-plastic composite board is obtained.

3. The method for preparing a bio-based high-performance honeycomb core material according to claim 1, characterized in that The method for preparing the straw-plastic composite board in step 1 is: Step A, drying: The dust and fragile leaves in the straw are blown away by a fan, and then dried at a temperature of 60℃ to 100℃ to a mass moisture content of less than 3%; Step B: Cutting: Cut the dried straw into 150-200 mm lengths, and cut the plastic film into (150-200) mm × (150-200) mm squares; Step C: Layered Paving: Arrange the straw evenly and orientably on the plastic film, spray the coupling agent evenly, repeat the operation, and stack 10 to 30 layers of plastic film and straw in an alternating order to form a slab, and then place it in a mold; The mass fraction of the plastic film is 10% to 50%, and the mass fraction of the coupling agent is 1% to 10%; Step D, hot pressing: The slab laid in step C is covered with release paper and a metal pad, and then placed in a hot press. Under the condition of a temperature of 100-180°C, pre-pressing is performed for 1-60 seconds with a pre-pressing pressure of 0.1-1 MPa, and then hot pressing is performed. The hot pressing time is controlled to be 30-60 seconds / mm according to the thickness, and the hot pressing pressure is controlled to be 1-5 MPa. After trimming, the straw-plastic composite board is obtained.

4. The method for preparing a bio-based high-performance honeycomb core material according to claim 1, characterized in that The method for preparing the straw-plastic composite board in step 1 is: Step A, drying: The dust and fragile leaves in the straw are blown away by a fan, and then dried at a temperature of 60℃ to 100℃ to a mass moisture content of less than 3%; Step B, crushing: The straw is processed into powder using a crusher, and the size of the crushed straw powder is 30 to 100 meshes; Step C, mixing and granulation: The straw powder, plastic particles and coupling agent particles are mixed evenly in a high-speed mixer, and then fed into an extruder for blending and granulation to obtain straw-plastic composite particles; The mass fraction of the plastic particles is 10% to 50%, and the mass fraction of the coupling agent particles is 1% to 10%; Step D, hot pressing: The straw-plastic composite particles prepared in step C are placed in a mold, covered with release paper and a metal pad, and then placed in a hot press. Under the condition of a temperature of 100-180° C., they are pre-pressed for 1-60 seconds with a pre-pressing pressure of 0.1-1 MPa, and then hot-pressed. The hot-pressing time is controlled to be 30-60 seconds / mm according to the thickness, and the hot-pressing pressure is 1-5 MPa. After trimming, a straw-plastic composite board is obtained.

5. The method for preparing a bio-based high-performance honeycomb core material according to claim 1, characterized in that The straw in step 1 is rice straw, wheat straw, bamboo fiber, hemp fiber or reed straw.

6. The method for preparing a bio-based high-performance honeycomb core material according to claim 1, characterized in that Step 1: The plastic matrix is high-density polyethylene, linear low-density polyethylene, polypropylene, polyvinyl chloride or polylactic acid.

7. The method for preparing a bio-based high-performance honeycomb core material according to claim 1, characterized in that The coupling agent in step 1 is maleic anhydride grafted polyethylene or maleic anhydride grafted polypropylene.

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