Method for preparing composite board by using recycled one-way belt, composite board and application of composite board

Abstract

The invention relates to the technical field of composite board processing, in particular to a method for preparing a composite board through a recycled one-way belt, the composite board and application of the composite board. The one-way belt is irregularly and evenly laid and then subjected to composite treatment, and a composite board is obtained; the thickness of the one-way belt is 0.2 mm, and the specification of the one-way belt is 10 mm * 15 mm, 30 mm * 30 mm or 50 mm * 50 mm; or the one-way belt is made of 3 mm irregular chippings. The material processability of the one-way belt is effectively improved, the fracture resistance of the one-way belt is improved when the one-way belt is formed and processed into a three-dimensional part, and therefore the problem that a traditional one-way belt is prone to fracture in the forming and processing process is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of composite sheet processing, and particularly to a method for preparing composite sheets using recycled unidirectional tapes, composite sheets and their applications. Background Art

[0002] In the technical fields of composite material processing, molding process technology and material surface treatment technology, unidirectional tapes are a commonly used material. A unidirectional tape is a narrow tape composed of one or more materials, with a length much greater than its width and the fiber arrangement direction being consistent, so it has high strength and stiffness. Unidirectional tapes are usually used to manufacture high-performance composite materials, such as structural components in the aerospace, automotive and electronics industries.

[0003] In the existing technology, the processing of unidirectional tapes is mainly completed through a molding process. Specifically, the unidirectional tape is placed in a mold, and then it is pressed into the required shape through processes such as pressurization and heating. This process can produce high-strength three-dimensional components, but there are also some problems.

[0004] However, when the existing unidirectional tapes are processed into three-dimensional components with large stretching, there is a problem that the positions with large stretching are prone to breakage. This is because the fiber arrangement direction of the unidirectional tape is consistent, so when it is subjected to external forces, it is easy to break along the fiber direction. This problem greatly limits the application of unidirectional tapes in manufacturing components with complex shapes, and also increases the production cost and production cycle.

[0005] Therefore, how to improve the material processability of unidirectional tapes while ensuring their high mechanical properties, especially how to improve their anti-fracture ability when formed into three-dimensional components, is an urgent problem to be solved in this field currently. Summary of the Invention

[0006] To solve the above problems, the present invention provides a method for preparing composite sheets using recycled unidirectional tapes, composite sheets and their applications. The present invention effectively improves the material processability of unidirectional tapes and enhances their anti-fracture ability when formed into three-dimensional components, thus solving the problem that traditional unidirectional tapes are prone to breakage during the forming process.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] The present invention provides a method for preparing composite sheets using recycled unidirectional tapes, comprising the following steps:

[0009] Randomly and evenly spread the unidirectional tape and then perform a composite treatment to obtain a composite sheet;

[0010] Spread 315 g of unidirectional tape per area of 30 cm × 40 cm;

[0011] The thickness of the unidirectional tape is 0.2 mm, and the specifications are 10 mm×15 mm, 30 mm×30 mm, or 50 mm×50 mm;

[0012] Or the unidirectional tape is 3 mm irregular debris.

[0013] Preferably, the unidirectional tape in step 1) is a unidirectional tape of glass fiber infiltrated with PP resin, and the mass percentage content of glass fiber is 30-60%.

[0014] Preferably, the unidirectional tape is randomly and evenly laid on the PP film to obtain a material to be compounded, and the material to be compounded is subjected to compounding treatment to obtain a composite board.

[0015] Preferably, the melting point of the PP film in step 1) is 167.3 °C, and the melt index is 107.55 g / 10 min.

[0016] Preferably, it is laid in the structure of PP film-unidirectional tape-PP film or PP film-unidirectional tape-PP film-unidirectional tape-PP film. The area of the PP film is 30-40 cm×30-40 cm, and the ratio of the total mass of the PP film to the total mass of the unidirectional tape is 1:1.

[0017] Preferably, the conditions for the compounding treatment in step 2) include: holding pressure for 2 min at a temperature of 190 °C and a pressure of 1 MPa, then holding pressure for 6 min at a temperature of 190 °C and a pressure of 4 MPa, and finally holding pressure for 4 min at a temperature of 20-30 °C and a pressure of 4 MPa.

[0018] The present invention also provides a composite board prepared by the method according to the above technical solution. The thickness of the composite board is 3.5 mm, and the grammage is 3500 g / m 2 , and the bulk density is 1.2 g / m 3 .

[0019] The present invention also provides the application of the composite board according to the above technical solution in improving the anti-fracture ability of the board.

[0020] The present invention also provides the application of the composite board according to the above technical solution in improving the tensile strength of the board.

[0021] The present invention also provides the application of the composite board according to the above technical solution in improving the tensile modulus of the board.

[0022] The present invention also provides the application of the composite board according to the above technical solution in improving the melting performance of the board.

[0023] The beneficial effects of the present invention:

[0024] 1. Improve the processability of materials: In the present invention, the corner waste of the unidirectional tape is cut into short pieces, the short-cut unidirectional tape is evenly dispersed, and then heated and compression-molded with a whole high-melt-index thermoplastic resin film, effectively improving the processability of the unidirectional tape material. This process makes the fiber arrangement of the unidirectional tape more diverse, thereby enhancing its ability to resist fracture when subjected to external forces. At the same time, the addition of the high-melt-index thermoplastic resin film increases the melt index of the material, making it easier to perform molding processing in the subsequent mold.

[0025] 2. Enhance the anti-fracture ability: In the present invention, the short-cut unidirectional tape is dispersed and compression-molded into a plate, making the fiber arrangement direction more randomized and uniform, thus enhancing the anti-fracture ability of the unidirectional tape. This advantage enables the unidirectional tape to better resist external forces when formed into three-dimensional components, reducing the possibility of fracture, and thereby improving the quality and reliability of the product.

[0026] 3. Reduce production costs and cycle: Since the present invention can enhance the anti-fracture ability of the unidirectional tape, it is possible to manufacture components with more complex shapes without incurring additional costs. This not only reduces production costs but also shortens the production cycle and improves production efficiency.

[0027] 4. Expand the application scope: Due to the improvement of the processability of the unidirectional tape and the enhancement of its anti-fracture ability in the present invention, the application scope of the unidirectional tape in high-performance fields such as aerospace, automotive industry, and electronics industry will be further expanded. This will provide new material options and design ideas for the development of these industries.

[0028] 5. Environmental protection and sustainability: The short-cut and compression-molding process adopted in the present invention can effectively utilize the waste resources of the cut edges during the production of the unidirectional tape, reducing waste. Recycling the waste resources and producing products with practical and economic value thus has better environmental protection and sustainability. This is of great significance for the current global advocacy of green manufacturing and sustainable development. Specific implementation method

[0029] The present invention provides a method for preparing a composite plate using recycled unidirectional tape, comprising the following steps:

[0030] The unidirectional tape is randomly and evenly laid flat and then subjected to composite treatment to obtain a composite plate; 315 g of unidirectional tape is laid flat per 30 cm × 40 cm area; the thickness of the unidirectional tape is 0.2 mm, and the specifications are 10 mm × 15 mm, 30 mm × 30 mm, or 50 mm × 50 mm; or the unidirectional tape is 3 mm irregular debris.

[0031] The present invention uniformly spreads unidirectional tapes irregularly and then performs a composite treatment to obtain a composite board; 315 g of unidirectional tapes are spread per area of 30 cm × 40 cm; the thickness of the unidirectional tape is 0.2 mm, and the specifications are 10 mm × 15 mm, 30 mm × 30 mm or 50 mm × 50 mm; or the unidirectional tape is 3 mm irregular debris. In the present invention, the unidirectional tape is preferably a unidirectional tape of glass fiber infiltrated with PP resin, and the mass percentage content of glass fiber is 30-60%. The present invention preferably uses a shearing machine to cut the unidirectional tape of glass fiber infiltrated with PP resin along the fiber direction and perpendicular to the fiber direction into small pieces of 10 mm × 15 mm, 30 mm × 30 mm or 50 mm × 50 mm, and keep the blades of the shearing machine sharp during the cutting process to ensure the cutting accuracy and quality. The present invention has no special limitation on the source of the unidirectional tape of glass fiber infiltrated with PP resin, and it can be purchased commercially, such as purchased from Jiangsu Yisu Composite New Materials 375 g / m 2 PP unidirectional tape.

[0032] The present invention preferably spreads the unidirectional tape irregularly and uniformly on the PP film to obtain a material to be composite, and performs a composite treatment on the material to be composite to obtain a composite board. In the present invention, the melting point of the PP film is 167.3 °C, and the melt index is 107.55 g / 10 min. The present invention preferably lays according to the structure of PP film - unidirectional tape - PP film or PP film - unidirectional tape - PP film - unidirectional tape - PP film. The area of the PP film is 30-40 cm × 30-40 cm, and the ratio of the total mass of the PP film to the total mass of the unidirectional tape is 1:1. The present invention has no special limitation on the source of the PP film, and it can be purchased commercially, such as purchased from Zhejiang Gaoyuan New Materials 70 g / m 2 PP adhesive film.

[0033] In the present invention, the conditions of the composite treatment preferably include: holding pressure for 2 min at a temperature of 190 °C and a pressure of 1 MPa, then holding pressure for 6 min at a temperature of 190 °C and a pressure of 4 MPa, and finally holding pressure for 4 min at a temperature of 20-30 °C and a pressure of 4 MPa.

[0034] The present invention also provides a composite board prepared by the method according to the above technical solution. The thickness of the composite board is 3.5 mm, and the gram weight is 3500 g / m 2 , and the bulk density is 1.2 g / m 3 .

[0035] The present invention also provides the application of the composite board according to the above technical solution in improving the anti-fracture ability of the board.

[0036] The present invention also provides the application of the composite board according to the above technical solution in improving the tensile strength of the board.

[0037] The present invention also provides an application of the composite board described in the above technical solution in improving the tensile modulus of the board.

[0038] The present invention also provides an application of the composite board described in the above technical solution in improving the melting performance of the board.

[0039] In order to further illustrate the present invention, the present invention will be described in detail below with reference to embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0040] Example 1

[0041] A method for preparing a composite board using recycled unidirectional tapes, the steps are as follows:

[0042] Step 1: Cut the unidirectional tape into short pieces. First, select a unidirectional tape with glass fibers infiltrated with PP resin, with a width of 1 m, a thickness of 0.2 mm, and a glass fiber content of 30% at. Using a shear machine, cut the unidirectional tape along the fiber direction and perpendicular to the fiber direction into small pieces with sizes of 10×15 mm, 30×30 mm, 50×50 mm, and a thickness still of 0.2 mm. During the cutting process, keep the blades of the shear machine sharp to ensure the cutting accuracy and quality.

[0043] Step 2: Disperse the short-cut unidirectional tapes. Pour the cut short-cut unidirectional tapes into a stainless steel tray with an area of 50 cm×50 cm, and use a stirrer to stir at a speed of 200 revolutions per minute for 5 minutes to make the short-cut unidirectional tapes evenly distributed in the tray. During the stirring process, pay attention to observing the distribution of the short-cut unidirectional tapes to avoid the phenomenon of local excessive accumulation.

[0044] Step 3: Uniformly disperse and lay the short-cut unidirectional tapes. According to actual needs and design requirements, take 315 g of the short-cut unidirectional tapes dispersed in Step 2 and evenly place them on a Teflon tape. The laying area of the short-cut unidirectional tapes is 30 cm×30 cm. Prepare four samples with sizes of 10×15 mm, 30×30 mm, 50×50 mm, and a mass ratio of 10×15 mm:30×30 mm of 1:1 respectively. In this example, the short-cut unidirectional tapes are laid in a uniform and random manner to ensure that the short-cut unidirectional tapes can be closely combined during the subsequent molding and compounding process.

[0045] Step 4: Compression molding and compounding. Place the Teflon tape with chopped unidirectional tapes laid on it between copper plates and transfer it to a flat vulcanizer. Keep the temperature at 190 °C all the time. Hold the pressure at 1 MPa for 2 minutes, then quickly raise the pressure to 14 MPa and keep the constant pressure for 6 minutes. Cold press at room temperature under a pressure of 14 MPa in the cold press plate for 4 minutes. The chopped unidirectional tapes are tightly bonded together during the hot pressing in the vulcanizer, forming a composite board with good mechanical properties and structural stability, with a thickness of 2.8 mm and a gram weight of 3300 g / m 2 , and the bulk density is 1.2 g / m 3 .

[0046] During the compression molding and compounding process, pay attention to controlling the uniformity of pressure and temperature to avoid local overheating or overcooling of the composite material.

[0047] Through the above steps, the unidirectional tapes were successfully chopped and dispersed, and were laid on the long unidirectional tapes evenly and randomly for compression molding and compounding, thus improving the processability of the unidirectional tape materials and enhancing their anti-fracture ability when formed into three-dimensional components.

[0048] Test method for tensile modulus: ASTM D790-03 Standard Test Method for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials.

[0049] Test method for tensile strength:

[0050] 1. Specimen preparation: Prepare specimens with dimensions meeting the requirements according to ASTM D638 standard. The thickness is strictly controlled within the range of 3 to 4 mm, and at least 5 samples are taken in both transverse and longitudinal directions to ensure the accuracy and repeatability of the test.

[0051] Conditioning: The specimens need to be conditioned in an environment of 23 ± 2 °C and 50 ± 5% relative humidity for at least 40 hours to eliminate the influence of environmental differences on the materials.

[0052] 2. Test speed setting: Select a test speed of 5 mm / min. This speed is suitable for hard and semi-hard materials and can ensure the consistency of the strain rate of the specimens during the tensile process.

[0053] 3. Tensile test: Install the conditioned specimens on a tensile testing machine and perform tensile testing at a speed of 5 mm / min until the specimens break, and record the data of load and elongation throughout the process.

[0054] 4. Data recording: Accurately record the load-elongation curve of the specimens during the tensile process, especially the yield point (if any) and the load and elongation at break. These data are crucial for subsequent calculations.

[0055] 5. Calculate the tensile strength: Using the average original cross-sectional area within the standard length portion of the specimen, calculate the tensile strength corresponding to the maximum load according to the formula:

[0056]

[0057] 6. Calculate the elastic modulus: Calculate the elastic modulus, which is the ratio of stress to strain, from the initial linear portion of the load-elongation curve. The formula is:

[0058]

[0059] 7. Result analysis: Conduct a statistical analysis of the test results, calculate the average value and standard deviation to evaluate the consistency and reliability of the material.

[0060] Table 1 Performance of the composite board prepared in Example 1

[0061]

[0062] Example 2

[0063] A method for preparing a composite board using recycled unidirectional tapes, the steps are as follows:

[0064] Step 1: Cut the unidirectional tape into short pieces. First, select a unidirectional tape with glass fibers infiltrated with PP resin, its width is 1 m, thickness is 0.2 mm, and the glass fiber content is 60% at. Cut it through a cutting device into small pieces with a size of 30 mm × 30 mm, and cut the PP film with a high melt index into blocks with a size of 30 cm × 30 cm. The melting point of the PP film is 167.3 °C, and the melt index is 107.55 g / 10 min.

[0065] Step 2: Disperse the short-cut unidirectional tapes. Pour the cut short-cut unidirectional tapes into a 50 cm x 50 cm stainless steel tray, and use a stirrer to stir at a speed of 200 revolutions per minute for 5 minutes to make the short-cut unidirectional tapes evenly and randomly distributed in the tray. During the stirring process, pay attention to observing the distribution of the short-cut unidirectional tapes to avoid the phenomenon of local excessive accumulation.

[0066] Step 3: Lay the PP film flat, and evenly and randomly lay an equal mass of short-cut unidirectional tapes (the mass of the short-cut unidirectional tapes is 189 g) on the PP film. Lay them according to the structure of PP film - unidirectional tape - PP film. The area of the PP film is 30 cm × 300 cm, and the mass ratio of the total mass of the PP film to the mass of the unidirectional tape is 1:1. After laying, lay a PP film of the same size and weight on the unidirectional tape.

[0067] Step 4: Compression molding and compounding. Place the PP film and randomly and uniformly laid chopped unidirectional tapes into a Teflon tape, and then perform compounding treatment through a compression molding device. The compression molding temperature is 190 °C, hold the pressure at 1 MPa for 2 minutes, and then hold the pressure at 4 MPa for 6 minutes. Then perform cold pressing at 4 MPa at room temperature for 4 minutes. The compression molding device used is a flat vulcanizing machine. Through the above steps, a compression molded composite board that improves the processability of unidirectional tape materials can be obtained, with a thickness of 3.2 mm and a grammage of 3300 g / m 2 , and the bulk density is 1.2 g / m 3 .

[0068] The addition of the PP adhesive film can conveniently and effectively control the PP content of the chopped unidirectional tape board. The increase in high melt index PP and PP content can enhance the meltability of the final board and improve the forming processability of the material.

[0069] Example 3

[0070] A method for preparing a composite board using recycled unidirectional tape, the steps are as follows:

[0071] Step 1: Chop the unidirectional tape. First, select a unidirectional tape with glass fibers infiltrated with PP resin, with a width of 1 m, a thickness of 0.2 mm, and a glass fiber content of 60% at. Cut it through a chopping device into irregular debris with a size of 3 mm, and cut the high melt index PP film into blocks of 40 cm × 40 cm. The melting point of the PP film is 167.3 °C, and the melt index is 107.55 g / 10 min.

[0072] Step 2: Disperse the chopped unidirectional tape. Pour the chopped unidirectional tape after cutting into a stainless steel tray with an area of 50 cm x 50 cm, and use a stirrer to stir at a speed of 200 revolutions per minute for 5 minutes to make the chopped unidirectional tape evenly and randomly distributed in the tray. During the stirring process, pay attention to observing the distribution of the chopped unidirectional tape to avoid the phenomenon of local excessive accumulation.

[0073] Step 3: Lay the PP film flat, and lay the chopped unidirectional tape evenly and randomly on the PP film. Lay it in 5 layers according to PP film - chopped unidirectional tape - PP film - chopped unidirectional tape - PP film. The outermost layer is a single layer of PP film. The laying quality of the two layers of chopped unidirectional tapes is the same. The total mass ratio of the PP film to the total mass of the chopped unidirectional tape is 1:1. Most of the PP film is sandwiched between the unidirectional tapes, which is beneficial for the PP film to infiltrate the unidirectional tape during hot pressing. The chopped unidirectional tape hinders the flow of the PP film due to pressure during heating, reduces the internal stress generated by hot pressing, and reduces the warping of the final board.

[0074] Step 4: Compression molding. Place the PP film and randomly and evenly laid short-cut unidirectional tapes into the Teflon tape, and then perform composite treatment through a compression molding device. The compression molding temperature is 190°C, hold the pressure at 1 MPa for 2 minutes, and then hold the pressure at 4 MPa for 6 minutes. Then perform cold pressing at room temperature under 4 MPa for 4 minutes to obtain a composite board with a thickness of 3.5 mm and a grammage of 3900 g / m 2 , and the bulk density is 1.04 g / m 3 . The compression molding device used is a flat vulcanizer. The unidirectional tape debris is easier to spread, can be laid more evenly, and can reduce the warping problem caused by uneven laying of the unidirectional tape.

[0075] Test method for tensile modulus: ASTM D790-03 Standard Test Method for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials.

[0076] Test method for tensile strength:

[0077] 1. Specimen preparation: According to ASTM D638 standard, prepare specimens with dimensions meeting the requirements, where the thickness is strictly controlled within the range of 3 to 4 mm, and at least 5 samples are taken in both the transverse and longitudinal directions to ensure the accuracy and repeatability of the test.

[0078] Conditioning: The specimens need to be conditioned in an environment of 23±2°C and 50±5% relative humidity for at least 40 hours to eliminate the influence of environmental differences on the material.

[0079] 2. Test speed setting: Select a test speed of 5 mm / min. This speed is suitable for rigid and semi-rigid materials and can ensure the consistency of the strain rate of the specimens during the tensile process.

[0080] 3. Tensile test: Install the conditioned specimens on a tensile testing machine and perform tensile testing at a speed of 5 mm / min until the specimens break, and record the data of load and elongation throughout the process.

[0081] 4. Data recording: Accurately record the load-elongation curve of the specimens during the tensile process, especially the yield point (if any) and the load and elongation at break. These data are crucial for subsequent calculations.

[0082] 5. Calculate the tensile strength: Use the average original cross-sectional area within the standard length part of the specimens and calculate the tensile strength corresponding to the maximum load according to the formula:

[0083]

[0084] 6. Calculate the elastic modulus: Calculate the elastic modulus from the initial linear part of the load-elongation curve, that is, the ratio of stress to strain. The formula is:

[0085]

[0086] 7. Result Analysis: Statistically analyze the test results, calculate the average value and standard deviation to evaluate the consistency and reliability of the material.

[0087] 1. Sample Preparation: Prepare specimens of the desired size according to ASTM D790 standard, ensure that the specimens are cut or molded from sheets, plates or molded profiles, and perform polishing treatment.

[0088] 2. Conditioning: Store the specimens for at least 40 hours under the conditions of 23 ± 2 °C and 50 ± 5% relative humidity according to Method A of D618.

[0089] 3. Test Speed Setting: Set an appropriate test speed according to the specimen type.

[0090] 4. Bending Test: Mount the conditioned specimens on a bending testing machine, support the specimens through two supports, and apply pressure through a indenter in the middle of the two supports. Conduct the test using the three-point load simply supported beam method. The span is 16 times the average thickness of the sample.

[0091] 5. Data Recording: During the test, record the load-bending curve of the specimen, including the yield point (if any) and the load at fracture.

[0092] 6. Calculate Bending Stress: Use the formula

[0093]

[0094] Calculate the stress of the specimen during bending, where P is the pressure at a specified point, L is the span between the supports, b is the width of the specimen, and d is the height of the specimen.

[0095] Calculate Bending Modulus: Calculate the elastic modulus E from the initial linear part of the load-bending curve using the formula

[0096]

[0097] where m is the slope of the initial straight part of the curve.

[0098] 7. Result Analysis: Statistically analyze the test results, calculate the average value and standard deviation of the bending strength and modulus.

[0099] Table 2 Properties of the Composite Board Prepared in Example 3

[0100]

[0101] Example 4

[0102] A method for preparing a composite board using recycled unidirectional tapes, the steps are as follows:

[0103] Step 1: Chopping the unidirectional tape. First, select a unidirectional tape with glass fibers infiltrated by PP resin, which has a width of 1 m, a thickness of 0.2 mm, and a glass fiber content of 60% at. Cut it through a chopping device into irregular debris with a width of 3 mm and a length of 20 mm.

[0104] Step 2: Dispersing the chopped unidirectional tape and mixing with flame-retardant PP particles. Pour the chopped unidirectional tape after cutting into a stainless-steel tray with an area of 50 cm x 50 cm, and add flame-retardant PP particles and the debris of the unidirectional tape according to a mass ratio of 1:1. Use a blender to stir at a speed of 200 revolutions per minute for 5 minutes, so that the chopped unidirectional tape is evenly and randomly distributed in the tray. During the stirring process, pay attention to observing the distribution of the chopped unidirectional tape to avoid the phenomenon of local excessive accumulation. There is no special limitation on the source of the flame-retardant PP particles in the present invention, and conventional commercially available products can be used, such as TS950F2A(7468) purchased from Zhejiang Xinli New Materials.

[0105] Step 3: Compression molding and compounding. Uniformly and randomly spread a total of 360 g of PP film and flame-retardant PP particles on an area of 30 cm × 30 cm on a Teflon belt, and then perform compounding treatment through a compression molding device. The compression molding temperature is 190 °C, and it is kept under pressure at 4 MPa for 10 minutes. Then, cold press at room temperature under 4 MPa for 10 minutes to obtain a composite board with a thickness of 3.5 - 4.0 mm and a grammage of about 4000 g / m 2 , and the bulk density is 1.04 g / m 3 . The compression molding device used is a flat vulcanizing machine. The debris of the unidirectional tape is easier to spread, can be laid more evenly, and can reduce the warping problem caused by uneven laying of the unidirectional tape.

[0106] Test method for HB flame retardant rating:

[0107] 1. Sample preparation: Prepare sheet samples according to GB 2408-2008, with dimensions of about 125 mm × 13 mm, providing samples with a minimum thickness and a thickness of 3 mm ± 0.2 mm, a maximum thickness not exceeding 13 mm, a corner radius not greater than 1.3 mm, at least 2 sets, and 3 pieces in each set.

[0108] 2. Test process: Clamp the sample at an angle of 45°, with a methane flame height of 20 mm, burn for 30 seconds or move the flame away when it reaches 25 mm, and record the burning length and time.

[0109] 3. Data recording and calculation: Calculate the burning rate V = 60L / t (L is the burning length, t is the burning time).

[0110] 4. Result determination: For samples with a thickness of 3.0 - 13 mm, the burning rate ≤ 40 mm / min; for samples with a thickness < 3.0 mm, the burning rate ≤ 75 mm / min, and stopping burning before 100 mm is considered HB grade.

[0111] Test method for Class V fire resistance test:

[0112] 1. Sample preparation: Prepare sheet samples with dimensions of approximately 125 mm × 13 mm, provide samples with the minimum and maximum thicknesses, the maximum thickness not exceeding 13 mm, the corner radius not greater than 1.3 mm, at least 2 sets, and 5 pieces in each set.

[0113] 2. Conditioning: Condition in an environment of 23 ± 2°C and 50 ± 5% RH for more than 48 hours, and then cool after 168 hours in an air exchange furnace at 70 ± 1°C.

[0114] 3. Test procedure: Vertically clamp the sample, with the lower end 80 mm away from the camphor layer, the height of the methane flame being 20 mm, burn for 10 seconds, record the afterflame and afterglow times, and observe whether the sample burns out and whether the dripping ignites the cotton.

[0115] 4. Result determination: V - 0: t1 + t2 ≤ 10 s, t' + t2 ≤ 30 s, does not burn out, and the dripping does not ignite the cotton. V - 1: t1 + t2 ≤ 30 s, t' + t2 ≤ 60 s, does not burn out, and the dripping does not ignite the cotton. V - 2: t1 + t2 ≤ 30 s, t' + t2 ≤ 60 s, does not burn out, and the dripping can ignite the cotton.

[0116] Table 3 Performance comparison of the composite board prepared in Example 4 with that in Example 3

[0117]

[0118] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, not all of them. People can also obtain other embodiments based on these embodiments without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing a composite sheet using recycled unidirectional tape, characterized in that: The following steps are involved: The unidirectional tape is evenly laid irregularly and then composited to obtain a composite board; Lay 315g unidirectional tape on every 30cm×40cm area; The thickness of the unidirectional tape is 0.2 mm, and the specifications are 10 mm×15 mm, 30 mm×30 mm or 50 mm×50 mm; Or the unidirectional tape is 3 mm irregular chips.

2. The method according to claim 1, characterized in that The unidirectional tape in step 1) is a unidirectional tape of glass fiber impregnated with PP resin, and the mass percentage of glass fiber is 30-60%.

3. The method according to claim 1, characterized in that The unidirectional tape is evenly and irregularly laid on the PP film to obtain the material to be composited, and the material to be composited is composited to obtain a composite board.

4. The method according to claim 3, characterized in that In the step 1), the melting point of the PP film is 167.3° C., and the melt index is 107.55 g / 10 min; According to the structure of PP film-unidirectional tape-PP film or PP film-unidirectional tape-PP film-unidirectional tape-PP film, the area of ​​PP film is 30-40 cm×30-40 cm, and the total mass ratio of the PP film to the total mass of the unidirectional tape is 1:

1.

5. The method according to claim 1 or 3, characterized in that: The conditions of the composite treatment include: maintaining pressure at a temperature of 190° C. and a pressure of 1 MPa for 2 minutes, maintaining pressure at a temperature of 190° C. and a pressure of 4 MPa for 6 minutes, and finally maintaining pressure at a temperature of 20-30° C. and a pressure of 4 MPa for 4 minutes.

6. A composite board prepared by the method according to any one of claims 1 to 5, wherein the composite board has a thickness of 3 to 4 mm and a gram weight of 3500 to 4000 g / m 2 , the bulk density is 1.0~1.4g / m 3 .

7. Use of the composite board material according to claim 6 in improving the fracture resistance of the board material.

8. Use of the composite sheet material according to claim 6 in improving the tensile strength of the sheet material.

9. Use of the composite sheet material according to claim 6 in improving the tensile modulus of the sheet material.

10. Use of the composite sheet material according to claim 6 in improving the melting performance of the sheet material.

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