Preparation process of high-rigidity low-warp polypropylene modified plastic

Abstract

The application discloses a preparation process of high-rigidity and low-warp polypropylene modified plastic and relates to the technical field of modified plastic.The natural fiber structure in rice husk powder and glass fiber jointly act on the polypropylene modified plastic, so that the rigidity of the polypropylene modified plastic is effectively enhanced.The rice husk powder contains not only natural fibers such as cellulose but also mineral components.These components can interact with polypropylene molecules after being filled into the polypropylene, increase the friction between molecules, and improve the rigidity of the material.Copper phthalocyanine is added as a functional additive, so that the crystalline grains of the polypropylene are refined, the difference in crystallinity is reduced, and the warping deformation of the product is further reduced.The metal phthalocyanine has good thermal stability, can help improve the performance of the polypropylene in a high-temperature environment, and can be used to improve the ultraviolet protection capability of the polypropylene and prolong the service life of the material due to the significant light absorption capability of the metal phthalocyanine in the visible light and ultraviolet light regions.

Description

Technical Field

[0001] This invention relates to the field of modified plastics technology, and in particular to a preparation process for a high-rigidity, low-warpage modified polypropylene plastic. Background Technology

[0002] As the application fields of plastic products continue to expand, the performance requirements for them are also increasing. Among many plastic products, polypropylene (PP) is widely used due to its advantages such as low cost and good overall performance. However, pure PP has problems such as insufficient rigidity and easy warping and deformation, which limits its application in some fields with high requirements for rigidity and dimensional stability.

[0003] Currently, to improve the rigidity of PP, reinforcing materials such as glass fiber are often added, but this often exacerbates warping problems in the finished products. Traditional methods for addressing warping, such as adding talc, are not ideal and cannot simultaneously meet the requirements of high rigidity and low warping. Furthermore, high temperatures during PP processing can cause material degradation, affecting product performance; therefore, effective antioxidant and stabilization measures are necessary. Finding a manufacturing process that can simultaneously solve the problems of PP rigidity, warping, and processing stability is of significant practical importance. Summary of the Invention

[0004] The main objective of this invention is to provide a preparation process for high-rigidity, low-warpage modified polypropylene plastics. By optimizing the raw material formulation and processing technology, the prepared modified polypropylene plastics possess both high rigidity and low warpage properties, while simultaneously improving the stability of the material during processing.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A preparation process for a high-rigidity, low-warpage modified polypropylene plastic, the specific preparation steps of which are as follows: Step 1: Prepare the raw materials according to the following mass percentages: polypropylene 70-82.5%, copper phthalocyanine 1-3%, rice husk powder 10-14%, glass fiber 5-10%, antioxidant 0.5-1%, stabilizer 0.5-1%, lubricant 0.5-1%; Step 2: Add copper phthalocyanine, rice husk powder, antioxidant, stabilizer and lubricant to a high-speed mixer according to the formula ratio, and stir at 300-500 r / min for 10-15 minutes to make the raw materials initially mixed evenly to obtain a premix. Step 3: Feed the premixed material into the main feed port of the extruder, and feed the glass fiber into the side feed port. Set the extruder temperature to 170-190℃, 180-200℃, and 190-210℃ from the hopper end to the die head, and control the screw speed at 250-350 r / min. Step 4: After the extruded material is extruded through the die, it is cooled by air cooling or water cooling, and then pelletized. The pellet size is controlled at 2-4mm to obtain high-rigidity, low-warpage modified polypropylene plastic particles.

[0006] Preferably, in step 1, the antioxidant is specifically a benzotriazole or Brazilian palm oil, the stabilizer is specifically a calcium-zinc stabilizer, and the lubricant is stearic acid.

[0007] Preferably, the specific preparation method of copper phthalocyanine in step 1 is as follows: a1. Dissolve copper chloride and o-phenylenediamine in N-methylpyrrolidone until completely dissolved; a2. Transfer the dissolved reactant solution to a high-pressure reactor, set the reaction temperature to 180°C to 220°C, and the reaction time to 6-12 hours; a3. After the reaction is complete, the reaction vessel is allowed to cool naturally to room temperature. The precipitate is separated by filtration or centrifugation, and unreacted metal salts and organic impurities in the precipitate are removed by washing with ethanol multiple times to obtain crude copper phthalocyanine. a4. Dissolve the separated crude copper phthalocyanine in N-dimethylformamide, and then recrystallize it by lowering the temperature of the solvent or evaporating the solvent to obtain copper phthalocyanine.

[0008] Preferably, in step a1 of preparing copper phthalocyanine, the molar ratio of copper chloride and o-phenylenediamine is 1:2.

[0009] Preferably, in step a1, the ratio of N-methylpyrrolidone as a solvent to the mass of the reactants is 10-20 mL / g.

[0010] Preferably, the preparation steps of the rice husk powder are as follows: b1. Select fresh, dry rice husks with a moisture content of less than 5%; b2. The prepared rice husks are crushed using a vertical ball mill to achieve a target particle size of 60-100 mesh. b3. Use a 100-mesh vibrating screen to crush the pulverized rice husks at a vibration frequency of 60-80 times / minute, and then use an air classifier to remove impurities from the rice husks. b4. After processing, cool down to room temperature and conduct quality testing to ensure that the dryness and particle size meet the requirements, thus obtaining the rice husk powder.

[0011] Compared with the prior art, the present invention has the following beneficial effects: This invention incorporates rice husk powder, a widely available and inexpensive natural renewable resource. The natural fiber structure of rice husk powder, combined with glass fibers, effectively enhances the rigidity of modified polypropylene. Glass fibers, as a reinforcing material, act as a skeletal support within the plastic matrix, significantly improving the material's tensile and flexural strength. Rice husk powder not only contains natural fibers such as cellulose but also mineral components. These components, when incorporated into polypropylene, interact with the polypropylene molecules, increasing intermolecular friction and further enhancing the material's rigidity.

[0012] In this invention, the natural fibrous structure of rice husk powder helps improve the crystallization behavior of polypropylene, resulting in more uniform shrinkage and reduced warpage during molding. Copper phthalocyanine, as a functional additive, refines the crystalline grains of polypropylene, reducing differences in crystallinity and further minimizing warpage deformation of the finished product. Simultaneously, glass fibers, to some extent, restrict the orientation of polypropylene molecules, also contributing to reduced warpage. Metal phthalocyanine exhibits good thermal stability, helping to improve the performance of polypropylene at high temperatures. Furthermore, due to its significant light absorption capacity in the visible and ultraviolet light regions, metal phthalocyanine can be used to improve the ultraviolet protection capability of polypropylene, extending the material's service life.

[0013] In this invention, Brazilian palm oil can capture free radicals during high-temperature processing, inhibiting the oxidative degradation of polypropylene and maintaining the material's performance stability. Calcium-zinc stabilizers can absorb acidic substances such as hydrogen chloride generated during processing, preventing their degradation effects on the material, improving its thermal stability, and extending its service life. Stearic acid can reduce friction between the material and processing equipment, improve material flowability, make the processing smoother, and reduce equipment wear. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0015] This invention discloses a preparation process for high-rigidity, low-warpage modified polypropylene plastics. Compared with traditional modified polypropylene plastics, this invention innovatively incorporates rice husk powder. The natural fiber structure and glass fiber in rice husk powder work together to effectively enhance the rigidity of the modified polypropylene plastics. Rice husk powder not only contains natural fibers such as cellulose, but also mineral components. After being filled into polypropylene, these components can interact with polypropylene molecules, increasing the intermolecular friction and thus further improving the rigidity of the material.

[0016] The preparation process of rice husk powder in this invention is further disclosed below: b1. Select fresh, dry rice husks with a moisture content of less than 5%; b2. The prepared rice husks are crushed using a vertical ball mill to achieve a target particle size of 60-100 mesh. b3. Use a 100-mesh vibrating screen to crush the pulverized rice husks at a vibration frequency of 60-80 times / minute, and then use an air classifier to remove impurities from the rice husks. b4. After processing, cool down to room temperature and conduct quality testing to ensure that the dryness and particle size meet the requirements, thus obtaining rice husk powder.

[0017] It should be noted that the copper phthalocyanine in this invention, as a functional additive, can refine the crystalline grains of polypropylene, reduce the difference in crystallinity, and further reduce the warping deformation of the product. The metal phthalocyanine has good thermal stability, which can help improve the performance of polypropylene in high-temperature environments. In addition, since the metal phthalocyanine has significant light absorption capacity in the visible and ultraviolet light regions, it can be used to improve the ultraviolet protection capability of polypropylene and extend the service life of the material.

[0018] The preparation process of copper phthalocyanine in this invention is further disclosed below: a1. Dissolve copper chloride and o-phenylenediamine in N-methylpyrrolidone until completely dissolved; a2. Transfer the dissolved reactant solution to a high-pressure reactor, set the reaction temperature to 180°C to 220°C, and the reaction time to 6-12 hours; a3. After the reaction is complete, the reaction vessel is allowed to cool naturally to room temperature. The precipitate is separated by filtration or centrifugation, and unreacted metal salts and organic impurities in the precipitate are removed by washing with ethanol multiple times to obtain crude copper phthalocyanine. a4. Dissolve the separated crude copper phthalocyanine in N-dimethylformamide, and then recrystallize it by lowering the temperature of the solvent or evaporating the solvent to obtain copper phthalocyanine.

[0019] It should be further noted that in step a1 of the preparation of copper phthalocyanine, the molar ratio of copper chloride and o-phenylenediamine is 1:2, and the ratio of N-methylpyrrolidone as solvent to the mass of reactants in step a1 is 10-20 mL / g.

[0020] The following specific embodiments further disclose the preparation process of a high-rigidity, low-warpage modified polypropylene plastic according to the present invention. Example 1

[0021] Prepare modified polypropylene plastics according to the following steps: Step 1: Prepare the raw materials according to the following mass percentages: polypropylene 82.5%, copper phthalocyanine 1%, rice husk powder 10%, glass fiber 5%, antioxidant 0.5%, stabilizer 0.5%, lubricant 0.5%; Step 2: Add copper phthalocyanine, rice husk powder, antioxidant, stabilizer and lubricant to a high-speed mixer according to the formula ratio, and stir at 300-500 r / min for 10-15 minutes to make the raw materials initially mixed evenly to obtain a premix. Step 3: Feed the premixed material into the main feed port of the extruder, and feed the glass fiber into the side feed port. Set the extruder temperature to 170-190℃, 180-200℃, and 190-210℃ from the hopper end to the die head, and control the screw speed at 250-350 r / min. Step 4: After the extruded material is extruded through the die, it is cooled by air cooling or water cooling, and then pelletized. The pellet size is controlled at 2-4mm to obtain high-rigidity, low-warpage modified polypropylene plastic particles. Example 2

[0022] Step 1: Prepare the raw materials according to the following mass percentages: polypropylene 77.9%, copper phthalocyanine 2%, rice husk powder 12%, glass fiber 6%, antioxidant 0.7%, stabilizer 0.7%, lubricant 0.7%; Step 2: Add copper phthalocyanine, rice husk powder, antioxidant, stabilizer and lubricant to a high-speed mixer according to the formula ratio, and stir at 300-500 r / min for 10-15 minutes to make the raw materials initially mixed evenly to obtain a premix. Step 3: Feed the premixed material into the main feed port of the extruder, and feed the glass fiber into the side feed port. Set the extruder temperature to 170-190℃, 180-200℃, and 190-210℃ from the hopper end to the die head, and control the screw speed at 250-350 r / min. Step 4: After the extruded material is extruded through the die, it is cooled by air cooling or water cooling, and then pelletized. The pellet size is controlled at 2-4mm to obtain high-rigidity, low-warpage modified polypropylene plastic particles. Example 3

[0023] Step 1: Prepare the raw materials according to the following mass percentages: polypropylene 76.6%, copper phthalocyanine 2%, rice husk powder 12%, glass fiber 7%, antioxidant 0.8%, stabilizer 0.8%, lubricant 0.8%; Step 2: Add copper phthalocyanine, rice husk powder, antioxidant, stabilizer and lubricant to a high-speed mixer according to the formula ratio, and stir at 300-500 r / min for 10-15 minutes to make the raw materials initially mixed evenly to obtain a premix. Step 3: Feed the premixed material into the main feed port of the extruder, and feed the glass fiber into the side feed port. Set the extruder temperature to 170-190℃, 180-200℃, and 190-210℃ from the hopper end to the die head, and control the screw speed at 250-350 r / min. Step 4: After the extruded material is extruded through the die, it is cooled by air cooling or water cooling, and then pelletized. The pellet size is controlled at 2-4mm to obtain high-rigidity, low-warpage modified polypropylene plastic particles. Example 4

[0024] Step 1: Prepare the raw materials according to the following mass percentages: polypropylene 72.5%, copper phthalocyanine 3%, rice husk powder 13%, glass fiber 9%, antioxidant 0.7%, stabilizer 0.8%, lubricant 1%; Step 2: Add copper phthalocyanine, rice husk powder, antioxidant, stabilizer and lubricant to a high-speed mixer according to the formula ratio, and stir at 300-500 r / min for 10-15 minutes to make the raw materials initially mixed evenly to obtain a premix. Step 3: Feed the premixed material into the main feed port of the extruder, and feed the glass fiber into the side feed port. Set the extruder temperature to 170-190℃, 180-200℃, and 190-210℃ from the hopper end to the die head, and control the screw speed at 250-350 r / min. Step 4: After the extruded material is extruded through the die, it is cooled by air cooling or water cooling, and then pelletized. The pellet size is controlled at 2-4mm to obtain high-rigidity, low-warpage modified polypropylene plastic particles. Example 5

[0025] Step 1: Prepare the raw materials according to the following mass percentages: polypropylene 70%, copper phthalocyanine 3%, rice husk powder 14%, glass fiber 10%, antioxidant 1%, stabilizer 1%, lubricant 1%; Step 2: Add copper phthalocyanine, rice husk powder, antioxidant, stabilizer and lubricant to a high-speed mixer according to the formula ratio, and stir at 300-500 r / min for 10-15 minutes to make the raw materials initially mixed evenly to obtain a premix. Step 3: Feed the premixed material into the main feed port of the extruder, and feed the glass fiber into the side feed port. Set the extruder temperature to 170-190℃, 180-200℃, and 190-210℃ from the hopper end to the die head, and control the screw speed at 250-350 r / min. Step 4: After the extruded material is extruded through the die, it is cooled by air cooling or water cooling, and then pelletized. The pellet size is controlled at 2-4mm to obtain high-rigidity, low-warpage modified polypropylene plastic particles.

[0026] Comparative Example 1 The only difference between this comparative example and Example 3 is that the proportions of each component in step 1 are changed to: 88.6% polypropylene, 2% copper phthalocyanine, 7% glass fiber, 0.8% antioxidant, 0.8% stabilizer, and 0.8% lubricant. The preparation steps are the same as in Example 3.

[0027] Comparative Example 2 The only difference between this comparative example and Example 3 is that the proportions of each component in step 1 are changed to: 78.6% polypropylene, 12% rice husk powder, 7% glass fiber, 0.8% antioxidant, 0.8% stabilizer, and 0.8% lubricant. The preparation steps are the same as in Example 3.

[0028] The polypropylene modified plastic particles prepared in Examples 1-5 and Comparative Examples 1-2 were taken out and their performance was tested according to the following test methods: 1. Tensile strength Test method: According to GB / T1040.2-2006 "Determination of tensile properties of plastics - Part 2: Test conditions for molded and extruded plastics", the prepared polypropylene modified plastic was injection molded into standard specimens. Tensile tests were conducted on a universal testing machine at a tensile speed of 50 mm / min. The maximum tensile force at which the specimen broke was recorded, and the tensile strength was calculated.

[0029] 2. Bending strength Test method: According to GB / T9341-2008 "Determination of bending properties of plastics". The sample is made into a strip of 80mm×10mm×4mm. A three-point bending test is adopted, and the test speed is set to 2mm / min. The bending strength is calculated from the data recorded by the equipment.

[0030] 3. Heat distortion temperature Test method: Polypropylene modified plastic particles were prepared into samples according to GB / T1634.2-2004 "Determination of load deformation temperature of plastics - Part 2: Plastics, hard rubber and long fiber reinforced composites". The samples were subjected to a temperature rise test under a load of 1.82 MPa, and the temperature at which the sample reached the specified deformation amount was recorded, which is the heat distortion temperature.

[0031] 4. Warpage Test method: Polypropylene modified plastic particles are injection molded into square flat plates of 100mm×100mm×3mm and placed at room temperature for 24 hours. The warpage height on the diagonal of the sample is measured with a dial indicator, and the warpage is calculated by formula.

[0032] The above test results The test results show that the polypropylene modified plastic prepared by the high rigidity and low warpage method disclosed in this invention has greatly improved tensile strength, bending resistance, heat deformation resistance, and warpage prevention.

[0033] Regarding overall rigidity, the tensile strength of Examples 1-5 all reached above 46 MPa, with Example 3 showing a particularly significant effect, achieving a tensile strength as high as 50 MPa. Regarding flexural strength, the tensile strength of Examples 1-5 all reached above 61 MPa, with Example 3 showing a particularly significant effect, achieving a tensile strength as high as 64 MPa. Regarding high-temperature resistance, the heat distortion temperature of Examples 1-5 all reached above 127°C, with Example 3 showing a particularly significant effect, achieving a heat distortion temperature of 13-0°C. Regarding warpage, the warpage rate of Examples 1-5 was all below 0.47%, with Example 3 showing a particularly significant effect, achieving a warpage rate as low as 0.47%.

[0034] Furthermore, performance tests on the samples prepared in Comparative Example 1 and Comparative Example 2 showed that, without the addition of rice husk powder and copper phthalocyanine, the rigidity, deformation resistance, high-temperature resistance, and warpage of the modified polypropylene plastic were inferior to those in Examples 1-5. This demonstrates that the modified polypropylene plastic prepared in this invention exhibits high rigidity and low warpage. The synergistic effect of rice husk powder, glass fiber, and copper phthalocyanine effectively improves the material's rigidity while reducing warpage.

[0035] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A preparation process for a high-rigidity, low-warpage modified polypropylene plastic, characterized in that, The specific preparation steps are as follows: Step 1: Prepare the raw materials according to the following mass percentages: polypropylene 70-82.5%, copper phthalocyanine 1-3%, rice husk powder 10-14%, glass fiber 5-10%, antioxidant 0.5-1%, stabilizer 0.5-1%, lubricant 0.5-1%; Step 2: Add copper phthalocyanine, rice husk powder, antioxidant, stabilizer and lubricant to a high-speed mixer according to the formula ratio, and stir at 300-500 r / min for 10-15 minutes to make the raw materials initially mixed evenly to obtain a premix. Step 3: Feed the premixed material into the main feed port of the extruder, and feed the glass fiber into the side feed port. Set the extruder temperature to 170-190℃, 180-200℃, and 190-210℃ from the hopper end to the die head, and control the screw speed at 250-350 r / min. Step 4: After the extruded material is extruded through the die, it is cooled by air cooling or water cooling, and then pelletized. The pellet size is controlled at 2-4mm to obtain high-rigidity, low-warpage modified polypropylene plastic particles.

2. The preparation process of a high-rigidity, low-warpage modified polypropylene plastic according to claim 1, characterized in that, In step 1, the antioxidant is specifically benzotriazole or Brazilian palm oil, the stabilizer is specifically calcium-zinc stabilizer, and the lubricant is stearic acid.

3. The preparation process of a high-rigidity, low-warpage modified polypropylene plastic according to claim 1, characterized in that, The specific preparation method of copper phthalocyanine in step 1 is as follows: a1. Dissolve copper chloride and o-phenylenediamine in N-methylpyrrolidone until completely dissolved; a2. Transfer the dissolved reactant solution to a high-pressure reactor, set the reaction temperature to 180°C to 220°C, and the reaction time to 6-12 hours; a3. After the reaction is complete, the reaction vessel is allowed to cool naturally to room temperature. The precipitate is separated by filtration or centrifugation, and unreacted metal salts and organic impurities in the precipitate are removed by washing with ethanol multiple times to obtain crude copper phthalocyanine. a4. Dissolve the separated crude copper phthalocyanine in N-dimethylformamide, and then recrystallize it by lowering the temperature of the solvent or evaporating the solvent to obtain copper phthalocyanine.

4. The preparation process of a high-rigidity, low-warpage modified polypropylene plastic according to claim 3, characterized in that, In step a1 of the preparation of copper phthalocyanine, the molar ratio of copper chloride and o-phenylenediamine is 1:

2.

5. The preparation process of a high-rigidity, low-warpage modified polypropylene plastic according to claim 3, characterized in that, In step a1, the ratio of N-methylpyrrolidone as a solvent to the mass of the reactants is 10-20 mL / g.

6. The preparation process of a high-rigidity, low-warpage modified polypropylene plastic according to claim 1, characterized in that, The specific steps for preparing the rice husk powder are as follows: b1. Select fresh, dry rice husks with a moisture content of less than 5%; b2. The prepared rice husks are crushed using a vertical ball mill to achieve a target particle size of 60-100 mesh. b3. Use a 100-mesh vibrating screen to crush the pulverized rice husks at a vibration frequency of 60-80 times / minute, and then use an air classifier to remove impurities from the rice husks. b4. After processing, cool down to room temperature and conduct quality testing to ensure that the dryness and particle size meet the requirements, thus obtaining the rice husk powder.