A diatomite / polyethylene composite board and a preparation method thereof

Abstract

This invention relates to the field of polyethylene composite sheet technology, and discloses a diatomaceous earth / polyethylene composite sheet and its preparation method. The composite sheet is composed of 65-80 parts by weight of polyethylene resin, 3-6 parts by weight of maleic anhydride-grafted polyethylene, 2-4 parts by weight of hyperbranched polymer, 4-6 parts by weight of modified diatomaceous earth, 0.1-0.4 parts by weight of calcium stearate, and 0.2-0.3 parts by weight of antioxidant 1010. The diatomaceous earth is surface-modified using KH-550 to improve its compatibility with polyethylene resin; the hyperbranched polymer is synthesized through a multi-step reaction, possessing both cross-linking reinforcement and flame-retardant functions; the components are mixed at high speed, melt-extruded using a twin-screw extruder, calendered and cooled, and then cut to form the final product. This invention solves the problems of poor compatibility and difficulty in simultaneously achieving mechanical and antibacterial properties in traditional diatomaceous earth / polyethylene composite materials, while also exhibiting high tensile strength and good impact toughness.

Description

Technical Field

[0001] This invention relates to the field of polyethylene composite board technology, specifically to a diatomaceous earth / polyethylene composite board and its preparation method. Background Technology

[0002] Polyethylene sheets are widely used in various fields due to their advantages such as light weight, corrosion resistance, and ease of processing and molding. However, the poor rigidity and flame retardancy of pure polyethylene sheets limit their application in scenarios requiring high mechanical properties. Diatomaceous earth, a natural siliceous mineral, is characterized by its porous structure, large specific surface area, high hardness, wide availability, and low price. It is often used as a filler added to polymer matrices to improve material rigidity and control costs. However, diatomaceous earth has a large number of hydroxyl groups on its surface, making it highly polar, while polyethylene resin is a non-polar material. The two have poor compatibility, and direct blending can lead to uneven internal structure of the composite sheet, limited improvement in mechanical properties, and even a decrease in toughness.

[0003] In the prior art, for example, Chinese patent application CN102911421A discloses a method for preparing modified diatomaceous earth / polyethylene composite plastics. Through ultrafine refining and surface modification techniques, a novel "low-carbon and environmentally friendly" polyethylene plastic is developed, which is environmentally friendly, low-carbon emission, and can replace calcium carbonate filler in plastics. However, the modification effect is limited, and there is still room for improvement in the impact strength and tensile strength of the composite material. Therefore, developing a diatomaceous earth / polyethylene composite board with good compatibility, excellent mechanical properties, and simple preparation is of great significance. Summary of the Invention

[0004] Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a diatomaceous earth / polyethylene composite board and its preparation method, which exhibits good antibacterial effects and mechanical properties.

[0005] Technical solution To achieve the above objectives, the present invention provides the following technical solution: a diatomaceous earth / polyethylene composite board, comprising the following weight components: 65-80 parts by weight of polyethylene resin, 3-6 parts by weight of maleic anhydride-grafted polyethylene, 2-4 parts by weight of hyperbranched polymer, 4-6 parts by weight of modified diatomaceous earth, 0.1-0.4 parts by weight of calcium stearate, and 0.2-0.3 parts by weight of antioxidant 1010.

[0006] Furthermore, the preparation method of the hyperbranched polymer is as follows: S1. Add diethylenetriamine to a reaction flask, then slowly add itaconic anhydride, react at 50-55℃ for 2-3 hours, then raise the temperature to 140-145℃ and react for 3-5 hours. After the reaction is completed, cool to room temperature to obtain alkenyl hyperbranched polyamide. S2. Add 8-10 mmol of benzisothiazolinone and 14-16 mmol of anhydrous potassium carbonate to 20-30 mL of N,N-dimethylformamide solvent. Purge with nitrogen for protection and stir magnetically at room temperature for 20-30 min to ensure thorough mixing. Then slowly add 14-16 mmol of 3-bromo-1-propene. After the addition is complete, slowly raise the temperature to 70-75 °C and react. After the reaction is complete, cool to room temperature, quench the reaction with deionized water, extract with ethyl acetate, combine the organic phases, dry with anhydrous magnesium sulfate, filter and rotary evaporate. Purify the crude product by chromatographic column to obtain the alkenyl intermediate. S3. Add 0.2-0.3 g of N-isopropylacrylamide, 0.6-0.8 g of alkenyl hyperbranched polyamide, 6-8 mmol of alkenyl intermediate, and 0.01-0.02 g of azobisisobutyronitrile initiator to a reaction flask containing 40-45 mL of 1,4-dioxane solvent. Then, stir magnetically, evacuate, purge with nitrogen to remove oxygen, and heat to react for 22-24 h. After the reaction is completed, evaporate by rotary evaporation, concentrate, precipitate with anhydrous diethyl ether, filter, and vacuum dry the precipitate to constant weight to obtain the hyperbranched polymer.

[0007] Furthermore, in S1, the ratio of diethylenetriamine to itaconic anhydride is 3.6-4.2g:4.3-5g.

[0008] Furthermore, in S2, the reaction time is 2-3 hours.

[0009] Furthermore, in S3, the heating temperature is 70-75℃.

[0010] Further, the modified diatomaceous earth is prepared as follows: Diatomaceous earth is added to a reaction flask containing 10-12 mL of anhydrous ethanol and 10-12 mL of deionized water, and ultrasonically dispersed for 30-35 min. Then, KH-550 is added, and the reaction is carried out at 65-70℃ for 1-2 h. After the reaction is completed, the precipitate is collected, filtered, washed 2-3 times with deionized water, and dried to obtain modified diatomaceous earth.

[0011] Furthermore, the ratio of diatomaceous earth to KH-550 is 1.5-2g:0.01-0.02g.

[0012] Further, the preparation method of the diatomaceous earth / polyethylene composite board is as follows: polyethylene resin, maleic anhydride grafted polyethylene, hyperbranched polymer, modified diatomaceous earth, calcium stearate, and antioxidant are added to a high-speed mixer and stirred. The mixture is then added to a twin-screw extruder, and the temperatures of each section of the extruder are set as follows: feeding section 140-160℃, compression section 160-180℃, homogenization section 180-190℃, and die head 170-180℃. The screw speed is 30-60 rpm, and the board blank is obtained by melt extrusion. After the board blank is calendered by a three-roll calender, it is cooled to room temperature in a cooling water tank at a water temperature of 20-30℃ to obtain a shaped board. Then, according to the required size, the cooled and shaped board is cut by a cutting machine to obtain the diatomaceous earth / polyethylene composite board.

[0013] Beneficial technical effects This invention modifies the surface of diatomaceous earth using KH-550. The silane coupling agent is hydrolyzed to generate silanol, which condenses with the silanol on the surface of diatomaceous earth to form a covalent bond. Organic functional groups (amino groups) are grafted onto the surface of diatomaceous earth, thereby regulating its surface polarity and introducing organic compatible groups, while reducing its aggregation effect.

[0014] Maleic anhydride-grafted polyethylene in the composite board acts as a compatibilizer. Its anhydride groups can chemically react with the amino groups on the surface of modified diatomaceous earth and the hydroxyl groups of hyperbranched polymers, preventing diatomaceous earth from agglomerating in the polyethylene matrix. This allows the components to be evenly dispersed and form a dense three-dimensional cross-linked network in the polyethylene matrix, firmly binding the components to form a dense composite system. This not only solves the problem of uneven internal structure caused by traditional diatomaceous earth filling, but also improves its tensile properties.

[0015] The branched structure of the hyperbranched polymer in the composite board can absorb impact energy, forming "elastic buffer points" within the material. This absorbs external impact energy, alleviates stress concentration, and improves the impact strength of the composite board, avoiding the problem of "increased rigidity but decreased toughness" common with traditional filler materials. The porous rigid structure of modified diatomaceous earth is uniformly dispersed in the matrix, forming "rigid support points." Combined with the cross-linking network effect of the hyperbranched polymer, this improves the tensile strength of the composite board, meeting the requirements of high mechanical performance applications. The benzisothiazolinone structure of the hyperbranched polymer has good antibacterial effects; adding it to the board enhances its antibacterial properties. Attached Figure Description

[0016] Figure 1 It is the reaction route for alkenyl intermediates. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific embodiments.

[0019] The polyethylene resin is high-density polyethylene resin. The grafting rate of maleic anhydride-grafted polyethylene is 1%.

[0020] Diatomaceous earth: 800℃ calcined diatomaceous earth, from a company in Linjiang City, Jilin Province.

[0021] KH-550: γ-aminopropyltriethoxysilane.

[0022] Example 1 A method for preparing a diatomaceous earth / polyethylene composite board is as follows: S1. Add 3.6g of diethylenetriamine to a reaction flask, then slowly add 4.3g of itaconic anhydride, react at 50℃ for 2h, then raise the temperature to 140℃ for 3h, and cool to room temperature after the reaction to obtain alkenyl hyperbranched polyamide; S2. Add 8 mmol of benzisothiazolinone and 14 mmol of anhydrous potassium carbonate to 20 mL of N,N-dimethylformamide solvent, purge with nitrogen for protection, stir magnetically at room temperature for 20 min to ensure thorough mixing, then slowly add 14 mmol of 3-bromo-1-propene. After the addition is complete, slowly raise the temperature to 70 °C and react for 2 h. After the reaction is complete, cool to room temperature, add deionized water to quench the reaction, extract with ethyl acetate, combine the organic phases, dry with anhydrous magnesium sulfate, filter and rotary evaporate, and purify the crude product by chromatographic column to obtain the alkenyl intermediate. S3. Add 0.2 g of N-isopropylacrylamide, 0.6 g of alkenyl hyperbranched polyamide, 6 mmol of alkenyl intermediate, and 0.01 g of azobisisobutyronitrile initiator to a reaction flask containing 40 mL of 1,4-dioxane solvent. Then, stir magnetically, evacuate, purge with nitrogen to remove oxygen, heat to 70 °C and react for 22 h. After the reaction is completed, evaporate by rotary evaporation, concentrate, precipitate with anhydrous diethyl ether, filter, and vacuum dry the precipitate to constant weight to obtain the hyperbranched polymer. S4. Add 1.5g of diatomaceous earth to a reaction flask containing 10mL of anhydrous ethanol and 10mL of deionized water, sonicate for 30min, then add 0.01g of KH-550, react at 65℃ for 1h, after which the precipitate is formed, filtered, washed twice with deionized water, dried, and modified diatomaceous earth is obtained. S5. Add 65 parts by weight of polyethylene resin, 3 parts by weight of maleic anhydride-grafted polyethylene, 2 parts by weight of hyperbranched polymer, 4 parts by weight of modified diatomaceous earth, 0.1 parts by weight of calcium stearate, and 0.2 parts by weight of antioxidant to a high-speed mixer and stir to mix. Add the mixture to a twin-screw extruder and set the temperatures of each section of the extruder as follows: feed section 140℃, compression section 160℃, homogenization section 180℃, and die head 170℃. Set the screw speed to 30 rpm and melt extrude to obtain a sheet blank. After calendering the sheet blank through a three-roll calender, cool it to room temperature in a cooling water tank at a water temperature of 20℃ to obtain a shaped sheet. Then, according to the required size, cut the cooled and shaped sheet using a cutting machine to obtain a diatomaceous earth / polyethylene composite sheet.

[0023] Example 2 A method for preparing a diatomaceous earth / polyethylene composite board is as follows: S1. Add 4.2g of diethylenetriamine to a reaction flask, then slowly add 5g of itaconic anhydride, react at 55℃ for 3h, then raise the temperature to 145℃ and react for 5h, then cool to room temperature after the reaction to obtain alkenyl hyperbranched polyamide; S2. Add 10 mmol of benzisothiazolinone and 16 mmol of anhydrous potassium carbonate to 30 mL of N,N-dimethylformamide solvent, purge with nitrogen for protection, stir magnetically at room temperature for 30 min to ensure thorough mixing, then slowly add 16 mmol of 3-bromo-1-propene. After the addition is complete, slowly raise the temperature to 75 °C and react for 3 h. After the reaction is complete, cool to room temperature, add deionized water to quench the reaction, extract with ethyl acetate, combine the organic phases, dry with anhydrous magnesium sulfate, filter and rotary evaporate, and purify the crude product by chromatographic column to obtain the alkenyl intermediate. S3. Add 0.3 g of N-isopropylacrylamide, 0.8 g of alkenyl hyperbranched polyamide, 8 mmol of alkenyl intermediate, and 0.02 g of azobisisobutyronitrile initiator to a reaction flask containing 45 mL of 1,4-dioxane solvent. Then, stir magnetically, evacuate, purge with nitrogen to remove oxygen, heat to 75 °C and react for 24 h. After the reaction is completed, evaporate by rotary evaporation, concentrate, precipitate with anhydrous diethyl ether, filter, and vacuum dry the precipitate to constant weight to obtain the hyperbranched polymer. S4. Add 2g of diatomaceous earth to a reaction flask containing 12mL of anhydrous ethanol and 12mL of deionized water, sonicate for 35min, then add 0.02g of KH-550, react at 70℃ for 2h, after which the precipitate is formed, filtered, washed 3 times with deionized water, dried, and modified diatomaceous earth is obtained. S5. Add 80 parts by weight of polyethylene resin, 6 parts by weight of maleic anhydride-grafted polyethylene, 4 parts by weight of hyperbranched polymer, 6 parts by weight of modified diatomaceous earth, 0.4 parts by weight of calcium stearate, and 0.3 parts by weight of antioxidant to a high-speed mixer and stir to mix. Add the mixture to a twin-screw extruder and set the temperatures of each section of the extruder as follows: feed section 160℃, compression section 180℃, homogenization section 190℃, and die head 180℃. Set the screw speed to 60 rpm and melt extrude to obtain a sheet blank. After calendering the sheet blank through a three-roll calender, cool it to room temperature in a cooling water tank at a water temperature of 30℃ to obtain a shaped sheet. Then, according to the required size, cut the cooled and shaped sheet using a cutting machine to obtain a diatomaceous earth / polyethylene composite sheet.

[0024] Example 3 A method for preparing a diatomaceous earth / polyethylene composite board is as follows: S1. Add 3.9g of diethylenetriamine to a reaction flask, then slowly add 4.6g of itaconic anhydride, react at 53℃ for 2h, then raise the temperature to 142℃ for 4h, and cool to room temperature after the reaction to obtain alkenyl hyperbranched polyamide; S2. Add 9 mmol of benzisothiazolinone and 14-16 mmol of anhydrous potassium carbonate to 25 mL of N,N-dimethylformamide solvent, purge with nitrogen for protection, stir magnetically at room temperature for 25 min to ensure thorough mixing, then slowly add 15 mmol of 3-bromo-1-propene. After the addition is complete, slowly raise the temperature to 73 °C and react for 2.5 h. After the reaction is complete, cool to room temperature, add deionized water to quench the reaction, extract with ethyl acetate, combine the organic phases, dry with anhydrous magnesium sulfate, filter and rotary evaporate, and purify the crude product by chromatographic column to obtain the alkenyl intermediate. S3. Add 0.25 g of N-isopropylacrylamide, 0.7 g of alkenyl hyperbranched polyamide, 7 mmol of alkenyl intermediate, and 0.015 g of azobisisobutyronitrile initiator to a reaction flask containing 42 mL of 1,4-dioxane solvent. Then, stir magnetically, evacuate, purge with nitrogen to remove oxygen, heat to 72 °C and react for 23 h. After the reaction is completed, evaporate by rotary evaporation, concentrate, precipitate with anhydrous diethyl ether, filter, and vacuum dry the precipitate to constant weight to obtain the hyperbranched polymer. S4. Add 1.8g of diatomaceous earth to a reaction flask containing 11mL of anhydrous ethanol and 11mL of deionized water, sonicate for 32min, then add 0.01g of KH-550, react at 68℃ for 2h, after which the precipitate is formed, filtered, washed 3 times with deionized water, dried, and modified diatomaceous earth is obtained. S5. Add 70 parts by weight of polyethylene resin, 5 parts by weight of maleic anhydride-grafted polyethylene, 3 parts by weight of hyperbranched polymer, 5 parts by weight of modified diatomaceous earth, 0.2 parts by weight of calcium stearate, and 0.25 parts by weight of antioxidant to a high-speed mixer and stir to mix. Add the mixture to a twin-screw extruder and set the temperatures of each section of the extruder as follows: feed section 150℃, compression section 170℃, homogenization section 185℃, and die head 175℃. Set the screw speed to 40 rpm and melt extrude to obtain a sheet blank. After calendering the sheet blank through a three-roll calender, cool it to room temperature in a cooling water tank at a water temperature of 25℃ to obtain a shaped sheet. Then, according to the required size, cut the cooled and shaped sheet using a cutting machine to obtain a diatomaceous earth / polyethylene composite sheet.

[0025] Comparative Example 1 The difference between this comparative example and Example 3 is that diethylenetriamine was used instead of the hyperbranched polymer.

[0026] Comparative Example 2 The difference between this comparative example and Example 3 is that diatomaceous earth was used instead of modified diatomaceous earth.

[0027] Performance testing Table 1: Mechanical and Antibacterial Properties Tests

[0028] As shown in Table 1, the diatomaceous earth / polyethylene composite board prepared by this invention has good mechanical and antibacterial properties. Comparative Example 1 uses diethylenetriamine to replace the hyperbranched polymer, which does not contain the benzisothiazolinone structure and has no antibacterial properties; Comparative Example 2 contains a hyperbranched polymer, but its antibacterial properties are reduced. It is speculated that the unmodified diatomaceous earth agglomeration affects the dispersion of the hyperbranched polymer, resulting in the antibacterial active sites being unable to contact microorganisms.

[0029] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0030] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0031] Those skilled in the art should understand that the above descriptions are merely several specific embodiments of the present invention, and not all embodiments.

Claims

1. A diatomaceous earth / polyethylene composite board, characterized in that, It includes the following components by weight: 65-80 parts by weight of polyethylene resin, 3-6 parts by weight of maleic anhydride grafted polyethylene, 2-4 parts by weight of hyperbranched polymer, 4-6 parts by weight of modified diatomaceous earth, 0.1-0.4 parts by weight of calcium stearate, and 0.2-0.3 parts by weight of antioxidant 1010. The preparation method of the hyperbranched polymer is as follows: S1. Add diethylenetriamine to a reaction flask, then slowly add itaconic anhydride, react at 50-55℃ for 2-3 hours, then raise the temperature to 140-145℃ and react for 3-5 hours. After the reaction is completed, cool to room temperature to obtain alkenyl hyperbranched polyamide. S2. Add 8-10 mmol of benzisothiazolinone and 14-16 mmol of anhydrous potassium carbonate to 20-30 mL of N,N-dimethylformamide solvent. Purge with nitrogen for protection and stir magnetically at room temperature for 20-30 min to ensure thorough mixing. Then slowly add 14-16 mmol of 3-bromo-1-propene. After the addition is complete, slowly raise the temperature to 70-75 °C and react. After the reaction is complete, cool to room temperature, quench the reaction with deionized water, extract with ethyl acetate, combine the organic phases, dry with anhydrous magnesium sulfate, filter and rotary evaporate. Purify the crude product by chromatographic column to obtain the alkenyl intermediate. S3. Add 0.2-0.3 g of N-isopropylacrylamide, 0.6-0.8 g of alkenyl hyperbranched polyamide, 6-8 mmol of alkenyl intermediate, and 0.01-0.02 g of azobisisobutyronitrile initiator to a reaction flask containing 40-45 mL of 1,4-dioxane solvent. Then, stir magnetically, evaporate under vacuum, purge with nitrogen to remove oxygen, and heat to react for 22-24 h. After the reaction is completed, evaporate by rotary evaporation, concentrate, precipitate with anhydrous diethyl ether, filter, and vacuum dry the precipitate to constant weight to obtain the hyperbranched polymer. The modified diatomaceous earth is prepared as follows: Diatomaceous earth is added to a reaction flask containing 10-12 mL of anhydrous ethanol and 10-12 mL of deionized water, and ultrasonically dispersed for 30-35 min. Then, KH-550 is added, and the reaction is carried out at 65-70℃ for 1-2 h. After the reaction is completed, the precipitate is collected, filtered, washed 2-3 times with deionized water, and dried to obtain the modified diatomaceous earth.

2. The diatomaceous earth / polyethylene composite board according to claim 1, characterized in that, In S1, the ratio of diethylenetriamine to itaconic anhydride is 3.6-4.2g:4.3-5g.

3. The diatomaceous earth / polyethylene composite board according to claim 1, characterized in that, In S2, the reaction time is 2-3 hours.

4. The diatomaceous earth / polyethylene composite board according to claim 1, characterized in that, In S3, the heating temperature is 70-75℃.

5. The diatomaceous earth / polyethylene composite board according to claim 1, characterized in that, The ratio of diatomaceous earth to KH-550 is 1.5-2g:0.01-0.02g.

6. A method for preparing a diatomaceous earth / polyethylene composite board as described in any one of claims 1-5, characterized in that, Polyethylene resin, maleic anhydride-grafted polyethylene, hyperbranched polymer, modified diatomaceous earth, calcium stearate, and antioxidant are added to a high-speed mixer and stirred. The mixture is then added to a twin-screw extruder, and the temperatures of each section of the extruder are set as follows: feed section 140-160℃, compression section 160-180℃, homogenization section 180-190℃, and die head 170-180℃. The screw speed is 30-60 rpm. The sheet blank is melt-extruded to obtain a sheet blank. After the sheet blank is calendered by a three-roll calender, it is cooled to room temperature in a cooling water tank at a water temperature of 20-30℃ to obtain a shaped sheet. Then, according to the required size, the cooled and shaped sheet is cut by a cutting machine to obtain a diatomaceous earth / polyethylene composite sheet.

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