Preparation method of modified PVC recycled material
By blending the pretreated PVC recycling material with lignin and modifier, the modified PVC recycling material was prepared, which solved the problem of the performance of PVC recycling material degradation after secondary heating, significantly improved the mechanical, heat resistance, antibacterial and flame retardant properties of the material, and achieved efficient reuse and environmental protection effects.
Patent Information
- Application Number
- CN202411857133.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-17
- Publication Date
- 2025-03-25
AI Technical Summary
During the secondary heating process, existing PVC plastic recycling materials have reduced mechanical properties, unstable processing, weakened heat resistance and flame retardant properties, and do not have antibacterial properties, which can easily lead to the reproduction of bacteria and viruses.
Modified PVC recovery material is prepared by stirring and mixing the pretreated PVC recovery material with lignin, modifier, antioxidant and processing aid, and melt blending in a twin screw extruder. Lignin enhances mechanical properties, and modifiers improve heat resistance, antibacterial properties and flame retardant properties.
The mechanical properties, heat resistance, antibacterial properties and flame retardant properties of modified PVC recycling materials are significantly improved, ensuring the stability and long-term performance of the materials, and meeting the needs of environmental protection and reuse.
Smart Images
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Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of plastic recycling, and in particular relates to a method for preparing modified PVC recycled material. Background Art
[0002] Polyvinyl chloride (PVC) is formed by free radical polymerization of vinyl chloride monomers. It is the third largest synthetic polymer plastic in the world. PVC has good electrical properties, mechanical properties, chemical stability and wear resistance, so it is widely used in various industries such as water supply and drainage pipes, home decoration materials, door and window profiles, film materials, wire and cable materials, etc.
[0003] With the increasing application of PVC plastic products, a large amount of waste PVC materials are also generated every year. PVC plastic profiles are thermoplastic plastics. They can be repeatedly heated and softened and then reprocessed. Therefore, furniture board profiles made of PVC as raw material can be fully reused, which is of environmental significance. However, since PVC plastic products have undergone a complete production and processing process, the secondary heating during the recycling process will cause the mechanical properties of PVC plastic products to further decline, which will not only lead to unstable processing of PVC plastics during the production process, reduced heat resistance and mechanical properties of recycled products, but also seriously affect the flame retardant properties of PVC plastics. In addition, PVC does not have antibacterial properties. In the rainy season, furniture board profiles made of PVC as raw material provide a breeding ground for bacteria and viruses after being damp, resulting in a large number of bacteria and viruses. Some of these bacteria and viruses are pathogenic, posing a threat and harm to people's lives and health. Therefore, it is urgent to solve the above problems to meet the higher demands in the field of plastic recycling technology. Summary of the invention
[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a method for preparing modified PVC recycled material.
[0005] The purpose of the present invention can be achieved through the following technical solutions:
[0006] A method for preparing modified PVC recycled material comprises the following steps:
[0007] The pretreated PVC recycled material, lignin, a modifier, an antioxidant and a processing aid are stirred and mixed evenly in a mixer, and then put into a twin-screw extruder for melt blending and extrusion to obtain a modified PVC recycled material.
[0008] Furthermore, the raw materials are calculated in parts by weight as follows: 80-90 parts of pre-treated PET recycled material, 12-18 parts of lignin, 5-15 parts of modifier, 6-8 parts of antioxidant, and 2-4 parts of processing aid.
[0009] Furthermore, the antioxidant is a hindered phenol antioxidant.
[0010] Furthermore, the processing aid is one of olive oil, beeswax and zinc stearate.
[0011] Adding lignin as a reinforcing material can enhance the mechanical properties of PVC recycled materials. Moreover, lignin is abundant in sources, contains a large number of benzene rings and methyl groups in its structure, has a certain hydrophobicity, and has good compatibility with the PVC matrix. It can enhance the antibacterial and flame retardant properties of recycled materials, and is environmentally friendly and renewable.
[0012] Furthermore, the pretreated PVC recycled material is prepared by the following steps:
[0013] The discarded PVC board is recycled, rinsed back and forth with clean water to rinse off the dirt and debris on the surface of the PVC board, and then the PVC board is cut into several small pieces with a cutting machine, placed in an oven for drying, and then crushed with a pulverizer to obtain small particles. The small particles are placed in water, left to stand for 1-2 hours, and then centrifuged with a centrifuge to separate PVC from other impurities to obtain pre-treated PVC recycled materials.
[0014] Furthermore, the modifier is prepared by the following steps:
[0015] S1. Mix 4-hydroxystyrene and toluene, add them to a three-necked round-bottom flask equipped with a thermometer, a magnetic stirring system and a spherical condenser, add formaldehyde solution dropwise under an ice bath condition of 5°C, and continue stirring until the dropwise addition is completed, then add 4,4'-diaminodiphenyl sulfone to the device, control the reaction temperature to 55°C, reflux for 6 hours, and after the reaction is completed, cool to room temperature, remove the solvent by rotary evaporation, and then purify by column chromatography (the eluent is a mixed solvent of benzene / ethyl acetate, and the volume ratio of the two is 3:1), remove the eluent by rotary evaporation to obtain intermediate 1; the ratio of the amount of 4-hydroxystyrene, toluene, formaldehyde solution, and 4,4'-diaminodiphenyl sulfone is 11.8g:100mL:25mL:25.7g;
[0016] 4-Hydroxystyrene, 4,4'-diaminodiphenyl sulfone and formaldehyde undergo a Mannich condensation reaction. By controlling the molar ratio of the two to be close to 1:1 and a slight excess of 4,4'-diaminodiphenyl sulfone, intermediate 1 is obtained. The specific reaction process is as follows:
[0017]
[0018] S2, in a three-necked flask equipped with a stirring device, glutaraldehyde, 4-aminoazobenzene, piperidine (condensing agent) and toluene were mixed and stirred uniformly, the device temperature was controlled at 60 ° C, and the reaction was kept warm for 6 hours. After the reaction was completed, it was naturally cooled, and the solvent was distilled off under reduced pressure, and then purified by column chromatography (eluent was a mixed solvent of benzene / ethyl acetate, and the volume ratio of the two was 2:1), and the eluent was removed by rotary evaporation to obtain intermediate 2; the ratio of glutaraldehyde, 4-aminoazobenzene, piperidine and toluene was 9.9g:19.7g:15mL:100mL;
[0019] Under the action of the condensing agent, the amino group on 4-aminoazobenzene condenses with the aldehyde group on glutaraldehyde to form an imine group (C=N Schiff base structure), and by controlling the molar ratio of the two to be close to 1:1 and a slight excess of glutaraldehyde, only one aldehyde group on glutaraldehyde participates in the reaction to obtain intermediate 2; the specific reaction process is as follows:
[0020]
[0021] S3, in a three-necked flask equipped with a stirring device, intermediate 1, intermediate 2 and N, N-dimethylformamide (DMF) were mixed, and piperidine was added to stir and mix evenly, and the reaction temperature was controlled to 70 ° C. The reaction was kept warm for 8 hours. After the reaction was completed, part of the solvent was removed by reduced pressure distillation, and then purified by column chromatography (the eluent was a mixed solvent of ethyl acetate / benzene, and the volume ratio of the two was 5:3), the eluent was removed by rotary evaporation, and vacuum drying was performed to obtain a modifier; the ratio of the amount of intermediate 1, intermediate 2, N, N-dimethylformamide, and piperidine was 39.2g:27.9g:150mL:15mL;
[0022] Under the action of the condensing agent, the amino group on the intermediate 1 and the aldehyde group on the intermediate 2 are condensed to form an imine group (C=N Schiff base structure) to obtain a modifier; the structure of the modifier is shown below:
[0023]
[0024] The prepared modifier molecule contains diphenyl sulfone, benzoxazine, azobenzene, Schiff base and carbon-carbon double bond structure, wherein the diphenyl sulfone structure contains two benzene rings, which can enhance the heat resistance of the PVC matrix, and the S element in the diphenyl sulfone structure generates SO2, sulfurous acid and water during thermal desulfurization, which can promote the Fries rearrangement reaction of the matrix, accelerate the carbonization of the matrix, and effectively enhance the flame retardant property of the matrix; not only that, the introduced benzoxazine can further enhance the heat resistance of the matrix; in addition, the introduced azobenzene, as an excellent antibacterial structure, can combine with the chitin of bacteria, destroy the bacterial structure, play a bactericidal effect, and improve the antibacterial property of the matrix; the introduced Schiff base structure has both antibacterial and flame retardant properties, can synergize with diphenyl sulfone and azobenzene, greatly enhance the flame retardancy and antibacterial property of the matrix, and finally the introduced carbon-carbon double bond can be cross-linked with the PVC matrix, which can improve the migration resistance and exudation resistance of the modifier, so that the modifier can perform its performance stably for a long time.
[0025] It should be added that the modifier molecule contains multiple benzene rings, which can enhance the mechanical properties of the matrix.
[0026] Beneficial effects of the present invention:
[0027] 1. The modified PVC recycled material prepared by the present invention uses waste PVC sheets as raw materials, and by pre-treating the waste PVC sheets, not only impurities are removed, but also waste resources are reused;
[0028] 2. Adding lignin as raw material not only has good compatibility with the PVC matrix, but also enhances the mechanical properties, antibacterial and flame retardant properties of the recycled material, and is environmentally friendly and renewable;
[0029] 3. The prepared modifier molecules contain various functional groups, which can play a synergistic role with each other, and can significantly improve the heat resistance, antibacterial, flame retardancy and mechanical properties of the recycled materials. The performance is stable and not easy to fall off.
[0030] Therefore, the modified PVC recycled material prepared by the present invention has excellent mechanical properties, stable and efficient heat resistance, antibacterial and flame retardancy, and can recycle waste materials, which is green and environmentally friendly and has important application value in the field of plastic recycling technology. DETAILED DESCRIPTION
[0031] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0032] Embodiment 1
[0033] Preparation of modifier:
[0034] S1. Mix 11.8 g of 4-hydroxystyrene with 100 mL of toluene, add the mixture to a three-necked round-bottom flask equipped with a thermometer, a magnetic stirring system and a spherical condenser, add 25 mL of formaldehyde solution (mass fraction 16%) dropwise under an ice bath at 5°C, and continue stirring until the addition is complete, then add 25.7 g of 4,4'-diaminodiphenyl sulfone to the device, control the reaction temperature to 55°C, reflux for 6 hours, complete the reaction, cool to room temperature, remove the solvent by rotary evaporation, and purify by column chromatography (the eluent is a mixed solvent of benzene / ethyl acetate, the volume ratio of the two is 3:1), remove the eluent by rotary evaporation to obtain intermediate 1;
[0035] S2, in a three-necked flask equipped with a stirring device, 9.9g of glutaraldehyde, 19.7g of 4-aminoazobenzene, 15mL of piperidine and 100mL of toluene were mixed and stirred uniformly, the device temperature was controlled at 60°C, and the reaction was kept warm for 6h. After the reaction was completed, it was naturally cooled, and the solvent was distilled off under reduced pressure, and then purified by column chromatography (the eluent was a mixed solvent of benzene / ethyl acetate, and the volume ratio of the two was 2:1), and the eluent was removed by rotary evaporation to obtain intermediate 2;
[0036] S3. In a three-necked flask equipped with a stirring device, 39.2 g of intermediate 1, 27.9 g of intermediate 2 and 150 mL of N,N-dimethylformamide were mixed, and 15 mL of piperidine was added and stirred to mix evenly. The reaction temperature was controlled to 70°C, and the reaction was kept warm for 8 hours. After the reaction was completed, part of the solvent was distilled off under reduced pressure, and then purified by column chromatography (the eluent was a mixed solvent of ethyl acetate / benzene in a volume ratio of 5:3), the eluent was removed by rotary evaporation, and vacuum drying was performed to obtain a modifier.
[0037] Embodiment 2
[0038] Preparation of modifier:
[0039] S1. Mix 23.6 g of 4-hydroxystyrene with 200 mL of toluene, add the mixture to a three-necked round-bottom flask equipped with a thermometer, a magnetic stirring system and a spherical condenser, add 50 mL of formaldehyde solution (mass fraction 16%) dropwise under an ice bath at 5°C, and continue stirring until the addition is complete, then add 51.4 g of 4,4'-diaminodiphenyl sulfone to the device, control the reaction temperature to 55°C, reflux for 6 hours, complete the reaction, cool to room temperature, remove the solvent by rotary evaporation, and purify by column chromatography (the eluent is a mixed solvent of benzene / ethyl acetate, the volume ratio of the two is 3:1), remove the eluent by rotary evaporation, and obtain intermediate 1;
[0040] S2, in a three-necked flask equipped with a stirring device, 19.8g of glutaraldehyde, 39.4g of 4-aminoazobenzene, 30mL of piperidine and 200mL of toluene were mixed and stirred uniformly, the device temperature was controlled at 60°C, and the reaction was kept warm for 6h. After the reaction was completed, it was naturally cooled, and the solvent was distilled off under reduced pressure, and then purified by column chromatography (the eluent was a mixed solvent of benzene / ethyl acetate, and the volume ratio of the two was 2:1), and the eluent was removed by rotary evaporation to obtain intermediate 2;
[0041] S3. In a three-necked flask equipped with a stirring device, 78.4 g of intermediate 1, 55.8 g of intermediate 2 and 300 mL of N,N-dimethylformamide were mixed, and 30 mL of piperidine was added and stirred to mix evenly. The reaction temperature was controlled to 70°C, and the reaction was kept warm for 8 hours. After the reaction was completed, part of the solvent was distilled off under reduced pressure, and then purified by column chromatography (the eluent was a mixed solvent of ethyl acetate / benzene in a volume ratio of 5:3), the eluent was removed by rotary evaporation, and vacuum drying was performed to obtain a modifier.
[0042] Embodiment 3
[0043] Preparation of pre-treated PVC recycled materials:
[0044] The discarded PVC board is recycled, rinsed back and forth with clean water to rinse off the dirt and debris on the surface of the PVC board, and then the PVC board is cut into several small pieces with a cutting machine, placed in an oven for drying, and then crushed with a pulverizer to obtain small particles. The small particles are placed in water, left to stand for 1 hour, and then centrifuged with a centrifuge to separate PVC from other impurities to obtain pre-treated PVC recycled materials.
[0045] Embodiment 4
[0046] 80 g of the pretreated PVC recycled material prepared in Example 3, 12 g of lignin, 5 g of the modifier prepared in Example 1, 6 g of antioxidant 1010 and 2 g of olive oil were stirred and mixed uniformly in a mixer, and then put into a twin-screw extruder, melt-blended and extruded to obtain modified PVC recycled material.
[0047] Embodiment 5
[0048] 85 g of the pretreated PVC recycled material prepared in Example 3, 15 g of lignin, 10 g of the modifier prepared in Example 2, 7 g of antioxidant 1010 and 3 g of beeswax were stirred and mixed uniformly in a mixer, and then put into a twin-screw extruder, melt-blended and extruded to obtain modified PVC recycled material.
[0049] Embodiment 6
[0050] 90 g of the pretreated PVC recycled material prepared in Example 3, 18 g of lignin, 15 g of the modifier prepared in Example 2, 8 g of antioxidant 1010 and 4 g of zinc stearate were stirred and mixed uniformly in a mixer, and then put into a twin-screw extruder, melt-blended and extruded to obtain modified PVC recycled material.
[0051] Comparative Example 1
[0052] The modifier in Example 6 was replaced by a commercially available antibacterial agent of equal quality, and the remaining steps were the same as those in Example 6 to obtain a recycled material.
[0053] Comparative Example 2
[0054] The modifier in Example 6 was replaced by a commercially available flame retardant of equal quality, and the remaining steps were the same as those in Example 6 to obtain a recycled material.
[0055] Comparative Example 2
[0056] Use commercially available recycled PVC materials.
[0057] Embodiments 4, 5, 6 and comparative examples 1, 2, 3 were made into corresponding shapes according to different test standards and the following performance tests were performed:
[0058] The tensile strength is measured according to the national standard GB / T1040-2006 "Determination of tensile properties of plastics"; the sample is placed in an environment of 120°C and hot air oxidized for 72 hours, and then the tensile strength is measured (test standard GB / T1040.2-2006), and the retention rate of tensile strength is calculated; the retention rate of tensile strength = tensile strength after test / tensile strength before test × 100%;
[0059] The antibacterial rates of Staphylococcus aureus and Escherichia coli of the samples were determined using QB / T 2591-2003A "Test Methods and Antibacterial Effects of Antibacterial Plastics", and the antibacterial rates of Examples 4, 5, 6 and Comparative Example 1 after standing at room temperature for 200 days were determined;
[0060] The oxygen index of the sample was determined by adopting the national standard GB / T2406-2008 "Test Method for Combustion Performance of Plastics", and then the limiting oxygen index of Examples 4, 5, 6 and Comparative Example 2 after standing at room temperature for 200 days was determined;
[0061] The measured results are shown in the following table:
[0062]
[0063] It can be seen from the above table that the modified PVC recycled material prepared in the embodiment of the present invention has higher tensile strength, heat resistance, oxygen index and antibacterial performance than the comparative example, and the performance is long-lasting and stable, which has important application value in the field of plastic recycling technology.
[0064] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.
[0065] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.
Claims
1. A method for preparing modified PVC recycled material, characterized in that: The following steps are involved: The pretreated PVC recycled material, lignin, a modifier, an antioxidant and a processing aid are stirred and mixed evenly in a mixer, and then put into a twin-screw extruder for melt blending and extrusion to obtain a modified PVC recycled material.
2. The method for preparing a modified PVC recycled material according to claim 1, characterized in that: The modifying agent is prepared by the following steps: S1. Mix 4-hydroxystyrene and toluene, add to a three-necked round-bottom flask, add formaldehyde solution dropwise under an ice bath at 5°C, and continue stirring until the addition is complete, then add 4,4'-diaminodiphenyl sulfone to the device, reflux at 55°C for 6h, and after the reaction is complete, cool to room temperature, perform rotary evaporation, purify by column chromatography, and perform rotary evaporation to obtain intermediate 1; S2, glutaraldehyde, 4-aminoazobenzene, piperidine and toluene were mixed and stirred evenly, and then kept at 60° C. for reaction for 6 hours. After the reaction was completed, the mixture was naturally cooled, distilled under reduced pressure, purified by column chromatography, and rotary evaporated to obtain intermediate 2; S3. Mix intermediate 1, intermediate 2 and N,N-dimethylformamide, add piperidine and stir to mix evenly, and then keep warm at 70°C for 8 hours. After the reaction is completed, perform vacuum distillation, purify by column chromatography, rotary evaporate, and vacuum dry to obtain a modifier.
3. The method for preparing a modified PVC recycled material according to claim 2, characterized in that: In step S1, the ratio of the amount of 4-hydroxystyrene, toluene, formaldehyde solution, and 4,4'-diaminodiphenyl sulfone is 11.8 g: 100 mL: 25 mL: 25.7 g.
4. The method for preparing a modified PVC recycled material according to claim 2, characterized in that: In step S2, the ratio of glutaraldehyde, 4-aminoazobenzene, piperidine and toluene is 9.9 g:19.7 g:15 mL:100 mL.
5. The method for preparing a modified PVC recycled material according to claim 2, characterized in that: In step S3, the ratio of the amount of intermediate 1, intermediate 2, N,N-dimethylformamide and piperidine is 39.2 g:27.9 g:150 mL:15 mL.
6. The method for preparing a modified PVC recycled material according to claim 1, characterized in that: The raw materials are calculated in parts by weight as follows: 80-90 parts of pre-treated PET recycled material, 12-18 parts of lignin, 5-15 parts of modifier, 6-8 parts of antioxidant, and 2-4 parts of processing aid.
7. The method for preparing a modified PVC recycled material according to claim 1, characterized in that: The antioxidant is a hindered phenol antioxidant.
8. The method for preparing a modified PVC recycled material according to claim 1, characterized in that: The processing aid is one of olive oil, beeswax and zinc stearate.
9. The method for preparing a modified PVC recycled material according to claim 1, characterized in that: The pre-treated PVC recycled material is prepared by the following steps: The discarded PVC board is recycled, rinsed back and forth with clean water to rinse off the dirt and debris on the surface of the PVC board, and then the PVC board is cut into several small pieces with a cutting machine, placed in an oven for drying, and then crushed with a pulverizer to obtain small particles. The small particles are placed in water, allowed to stand, and centrifuged with a centrifuge to separate PVC from other impurities to obtain pre-treated PVC recycled materials.