A kind of aging-resistant polypropylene recycled material and preparation method thereof

Abstract

The invention discloses an anti-aging polypropylene recycled material and a preparation method thereof, and belongs to the technical field of polymer materials. The raw materials of the polypropylene recycled material include: 70 parts of recycled polypropylene resin, 20-30 parts of ethylene propylene diene monomer rubber, 15-25 parts of fillers, 1-3 parts of coupling agents, 0.5-1.2 parts of anti-aging agents, 0.5-1 parts of lubricants, and 0.05-0.1 parts of initiators. The filler of the invention can produce chemical reactions with the anti-aging agent, the matrix resin and the rubber under the action of the coupling agent and the initiator, and the anti-aging agent containing aromatic amine structure, hindered phenol structure and hindered amine structure also has chemical reactions with the filler, the matrix resin and the rubber. Therefore, the filler and the anti-aging agent can be highly dispersed and stably present in the polypropylene recycled material, and play a synergistic role to give the polypropylene recycled material excellent and stable anti-ultraviolet aging performance, anti-thermal oxygen aging performance and wear resistance and other properties.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to an aging-resistant polypropylene recycled material and a preparation method thereof. Background Art

[0002] Polypropylene (PP) is one of the five general-purpose resins. It has excellent properties such as light weight, easy processing, and resistance to chemical corrosion. It is widely used in the fields of chemical industry, electrical appliances, packaging, and automobiles. However, with the increase in the use of plastics, discarded PP plastics have caused serious pollution to the environment and economic waste. Therefore, the rational use of PP recycled materials can effectively reduce the harm of plastic waste to the environment and protect the ecological environment. At the same time, the use of recycled PP crushed materials can also save resources, reduce the demand for new raw materials, and promote the reuse of resources, thereby achieving effective resource management and environmental protection.

[0003] However, the tertiary carbon atoms in the polypropylene molecular chain are susceptible to oxygen attack and oxidation reaction, which leads to polypropylene aging. In addition, ultraviolet rays in sunlight will also catalyze this oxidation reaction, accelerating the aging process of polypropylene. Oxidation causes the polymer chain to break, which in turn affects the physical and mechanical properties of polypropylene, manifested as the material becoming brittle and the strength decreasing, which directly affects the service life and performance of polypropylene materials. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide an aging-resistant polypropylene recycled material and a preparation method thereof.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] The invention discloses an aging-resistant polypropylene recycled material, which comprises the following raw materials in parts by weight: 70 parts of recycled polypropylene resin, 20-30 parts of ethylene propylene diene monomer rubber, 15-25 parts of fillers, 1-3 parts of coupling agents, 0.5-1.2 parts of anti-aging agents, 0.5-1 parts of lubricants, and 0.05-0.1 parts of initiators.

[0007] Furthermore, the filler is one or more of nano titanium dioxide, calcium carbonate, aluminum hydroxide, magnesium hydroxide, and silicon powder.

[0008] Furthermore, the coupling agent is one or more of vinyl trimethoxy silane, vinyl triethoxy silane, 3-(methacryloyloxy)propyl trimethoxy silane, and vinyl tri(2-methoxyethoxy) silane.

[0009] The surface of the filler of the present invention contains abundant hydroxyl groups, and the coupling agent will form silanol (Si-OH) and siloxysilane (Si-O-Si) after hydrolysis and cross-linking. The silanol in the coupling agent and the hydroxyl on the surface of the filler will produce a chemical reaction to form a covalent bond, which will effectively improve the interface compatibility between the filler and other organic raw materials, so that the filler is evenly dispersed in the polypropylene recycled material, giving full play to its own role, and giving the polypropylene recycled material anti-ultraviolet aging performance, flame retardant performance and wear resistance.

[0010] In addition, the coupling agents used in the present invention all contain carbon-carbon double bonds, so the filler surface also contains abundant double bonds under the action of the coupling agent, and can produce chemical reaction with the carbon-carbon double bonds in the matrix resin or rubber under the action of the initiator, which further makes the filler highly dispersed in the polypropylene recycled material, thereby giving the polypropylene recycled material excellent and stable mechanical and physical properties, anti-aging and flame retardancy and other properties.

[0011] Furthermore, the anti-aging agent is prepared by the following steps:

[0012] S1. Add 2,6-di-tert-butyl-4-bromomethylphenol, N-isopropyl-N-phenyl-p-phenylenediamine and toluene to a dry three-necked flask under nitrogen protection, stir to dissolve, then slowly add triethylamine, heat to 60°C and stir to react for 3 hours after the addition is complete, cool to room temperature after the reaction is complete, distill under reduced pressure, purify by column chromatography (a mixed solvent of benzene and acetone is selected as the eluent, and the volume ratio of benzene to acetone is 9:1), and distill under reduced pressure to obtain intermediate 1; the amount ratio of 2,6-di-tert-butyl-4-bromomethylphenol, N-isopropyl-N-phenyl-p-phenylenediamine, triethylamine and toluene is 23.9 g:19.6 g:14.5 mL:200 mL;

[0013] The molar ratio of 2,6-di-tert-butyl-4-bromomethylphenol and N-isopropyl-N-phenyl-p-phenylenediamine is controlled to be 1:1.05-1.1. Under heating, -NH2 of N-isopropyl-N-phenyl-p-phenylenediamine and -Br of 2,6-di-tert-butyl-4-bromomethylphenol undergo nucleophilic substitution reaction, and triethylamine is used as an acid binding agent. The reaction process is as follows:

[0014] ;

[0015] S2. Add intermediate 1, hydroxyethyl methacrylate and DMSO (dimethyl sulfoxide) into a dry three-necked flask under nitrogen protection, stir evenly, then slowly add DBU (1,8-diazabicyclo (5,4,0)-7-undecene), heat to 60°C and react for 24 hours after the addition is complete, and after the reaction is completed, distill under reduced pressure, purify by column chromatography (select a mixed solvent of benzene and ethyl acetate as the eluent, the volume ratio of benzene and ethyl acetate is 8:2), and distill under reduced pressure to obtain intermediate 2; the usage ratio of intermediate 1, hydroxyethyl methacrylate, DBU and DMSO is 33.3 g:9.8 mL:2.2 mL:200 mL;

[0016] The molar ratio of intermediate 1 to hydroxyethyl methacrylate is controlled to be 1:1.05-1.1. Under the catalytic action of DBU, intermediate 1 and hydroxyethyl methacrylate undergo Michael addition reaction. The reaction process is as follows:

[0017] ;

[0018] S3. Add intermediate 2, maleic anhydride, DMAP (4-dimethylaminopyridine) and DMF (N,N-dimethylformamide) to a dry three-necked flask under nitrogen protection, stir evenly, heat to 50°C for 12 hours, cool to room temperature after the reaction, centrifuge, take the supernatant, add saturated brine, shake and separate, take the organic phase and quickly dry it with anhydrous magnesium sulfate, filter and distill the filtrate under reduced pressure, purify by column chromatography (the eluent is a mixed solution of chloroform and ether, the volume ratio of chloroform and ether is 9:1), and distill under reduced pressure to obtain intermediate 3; the amount ratio of intermediate 2, maleic anhydride, DMAP and DMF is 37.4g:7.2g:0.24g:200mL;

[0019] The molar ratio of intermediate 2 to maleic anhydride is controlled to be 1:1.1-1.15. Under the catalytic action of DMAP, intermediate 2 and maleic anhydride undergo esterification reaction. The reaction process is as follows:

[0020] ;

[0021] S4. Under nitrogen protection, add intermediate 3, 2,2,6,6-tetramethylpiperidinamine and DMF into a dry three-necked flask, stir and dissolve, then add EDC (1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride) and NHS (N-hydroxysuccinimide), stir evenly again, heat to 50°C for 6h, cool to room temperature after the reaction, and then distill under reduced pressure to obtain an antioxidant; the dosage ratio of intermediate 3, 2,2,6,6-tetramethylpiperidinamine, EDC, NHS and DMSO is 36.9g:10.8mL:0.31g:0.19g:200mL;

[0022] The molar ratio of intermediate 3 to 2,2,6,6-tetramethylpiperidinamine is controlled to be 1:1.1-1.2. Under the action of EDC and NHS, -COOH of intermediate 3 and -NH2 of 2,2,6,6-tetramethylpiperidinamine undergo amidation reaction. The reaction equation is as follows:

[0023] ;

[0024] The anti-aging agent of the present invention contains an aromatic amine structure, a hindered phenol structure and a hindered amine structure. The aromatic amine structure is a universal antioxidant for synthetic rubber, natural rubber, etc. It has excellent protective performance against ozone cracking and flex cracking, and is also an excellent protective agent against heat, oxygen, light and general aging. At the same time, it can also inhibit the aging effect of variable-valence metal ions, and has relatively comprehensive protective performance; the hindered phenol structure mainly delays the aging process of polypropylene recycled materials by capturing free radicals; the hindered amine structure has high light stability efficiency, and it achieves light protection effects by capturing free radicals, decomposing hydrogen peroxides, quenching singlet oxygen and capturing heavy metal ions; the three anti-aging structures work synergistically to effectively prevent the aging of polypropylene recycled materials. At the same time, the nano-titanium dioxide in the filler has a small particle size and can absorb, reflect and scatter ultraviolet rays very well, and the nano-titanium dioxide has a wide range of anti-ultraviolet wavelengths, including medium-wave and long-wave ranges; therefore, the anti-aging agent and filler of the present invention work synergistically to give the polypropylene recycled materials excellent anti-ultraviolet aging performance and anti-thermal oxygen aging performance.‌

[0025] In addition, the anti-aging agent contains carbon-carbon double bonds, which can produce chemical reactions with the carbon-carbon double bonds in the matrix resin or rubber under the action of the initiator, and can also produce chemical reactions with the double bonds on the surface of the filler. On the one hand, this allows the anti-aging agent to exist stably and be evenly dispersed in the polypropylene recycled material, giving full play to its anti-ultraviolet aging and anti-thermal oxygen aging properties. On the other hand, it further improves the interfacial compatibility of the filler and allows the filler to be further dispersed in the polypropylene recycled material, giving the polypropylene recycled material excellent and stable mechanical and physical properties, anti-aging and flame retardancy and other properties.

[0026] Furthermore, the lubricant is one or more of polyethylene wax, stearic acid, zinc stearate, and butyl stearate.

[0027] Furthermore, the initiator is one or more of dibenzoyl peroxide, diisopropylbenzene peroxide, and azobisisobutyronitrile.

[0028] A method for preparing aging-resistant polypropylene recycled material, comprising the following steps:

[0029] The raw materials are weighed by weight and added into a mixer for mixing, and then put into a twin-screw extruder for melt blending, extrusion and drying to obtain aging-resistant polypropylene recycled material.

[0030] The beneficial effects of the present invention are as follows: the filler of the present invention can produce chemical reactions with the anti-aging agent, the base resin and the rubber under the action of the coupling agent and the initiator, and the anti-aging agent containing the aromatic amine structure, the hindered phenol structure and the hindered amine structure also has chemical reactions with the filler, the base resin and the rubber. Therefore, a hybrid cross-linked network structure is formed between the filler, the anti-aging agent, the recycled polypropylene resin and the EPDM rubber. Furthermore, the filler and the anti-aging agent can be highly dispersed and stably present in the recycled polypropylene material, and play a synergistic role to give the recycled polypropylene material excellent and stable anti-ultraviolet aging performance, anti-thermal oxygen aging performance and wear resistance, etc. Under the action of the two, the recycled polypropylene material can be protected for a long time. 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] Example 1

[0033] The preparation of the anti-aging agent comprises the following specific steps:

[0034] S1. Under nitrogen protection, add 23.9 g of 2,6-di-tert-butyl-4-bromomethylphenol, 19.6 g of N-isopropyl-N-phenyl-p-phenylenediamine and 200 mL of toluene to a 500 mL dry three-necked flask, stir to dissolve, slowly add 14.5 mL of triethylamine, raise the temperature to 60°C and stir to react for 3 h after the addition is complete, cool to room temperature after the reaction is completed, distill under reduced pressure, purify by column chromatography (a mixed solvent of benzene and acetone is selected as the eluent, and the volume ratio of benzene to acetone is 9:1), and distill under reduced pressure to obtain intermediate 1;

[0035] S2, under nitrogen protection, add 33.3g of intermediate 1, 9.8mL of hydroxyethyl methacrylate and 200mL of DMSO into a 500mL dry three-necked flask, stir evenly, then slowly add 2.2mL of DBU, heat to 60°C and react for 24h after the addition is complete, after the reaction is completed, distill under reduced pressure, purify by column chromatography (a mixed solvent of benzene and ethyl acetate is selected as the eluent, and the volume ratio of benzene and ethyl acetate is 8:2), and distill under reduced pressure to obtain intermediate 2;

[0036] S3, under nitrogen protection, add 37.4g of intermediate 2, 7.2g of maleic anhydride, 0.24g of DMAP and 200mL of DMF into a 500mL dry three-necked flask, stir evenly, heat to 50°C and react for 12h, cool to room temperature after the reaction, centrifuge and take the supernatant, add saturated brine, shake and layer, take the organic phase and quickly dry it with anhydrous magnesium sulfate, filter and distill the filtrate under reduced pressure, purify by column chromatography (the eluent is a mixed solution of chloroform and ether, the volume ratio of chloroform and ether is 9:1), and distill under reduced pressure to obtain intermediate 3;

[0037] S4. Under nitrogen protection, add 36.9 g of intermediate 3, 10.8 mL of 2,2,6,6-tetramethylpiperidinamine and 200 mL of DMF into a 500 mL dry three-necked flask, stir to dissolve, then add 0.31 g of EDC and 0.19 g of NHS, stir evenly again, heat to 50 °C and react for 6 h. After the reaction is completed, cool to room temperature, and then distill under reduced pressure to obtain an anti-aging agent.

[0038] Example 2

[0039] Preparation of polypropylene recycled material, the specific steps are as follows:

[0040] 70 parts of recycled polypropylene resin, 20 parts of EPDM rubber, 15 parts of nano titanium dioxide, 1 part of vinyl tri(2-methoxyethoxy)silane, 0.5 parts of the anti-aging agent prepared in Example 1, 0.5 parts of polyethylene wax, and 0.05 parts of dibenzoyl peroxide were weighed by weight and added to a mixer for mixing, and then put into a twin-screw extruder for melt blending, extrusion, and drying to obtain recycled polypropylene material.

[0041] Example 3

[0042] Preparation of polypropylene recycled material, the specific steps are as follows:

[0043] 70 parts of recycled polypropylene resin, 25 parts of ethylene propylene diene monomer rubber, 7 parts of nano titanium dioxide, 5 parts of calcium carbonate, 8 parts of magnesium hydroxide, 2 parts of vinyl trimethoxy silane, 1 part of the anti-aging agent prepared in Example 1, 0.8 parts of stearic acid, and 0.08 parts of azobisisobutyronitrile were weighed by weight and added to a mixer for mixing, and then put into a twin-screw extruder for melt blending, extrusion, and drying to obtain recycled polypropylene material.

[0044] Example 4

[0045] Preparation of polypropylene recycled material, the specific steps are as follows:

[0046] 70 parts of recycled polypropylene resin, 30 parts of EPDM rubber, 10 parts of nano titanium dioxide, 10 parts of magnesium hydroxide, 5 parts of silicon powder, 3 parts of vinyl triethoxysilane, 1.2 parts of the antioxidant prepared in Example 1, 0.5 parts of zinc stearate, 0.5 parts of butyl stearate, and 0.1 parts of dicumyl peroxide were weighed by weight and added to a mixer for mixing, and then put into a twin-screw extruder for melt blending, extrusion, and drying to obtain recycled polypropylene material.

[0047] Comparative Example 1

[0048] Preparation of polypropylene recycled material, the specific steps are as follows:

[0049] The remaining steps remain unchanged, only the antioxidant in Example 2 is replaced by 0.4 parts of antioxidant 1010, 0.4 parts of light stabilizer GW-540 and 0.4 parts of antioxidant 4010 to prepare polypropylene recycled material.

[0050] Comparative Example 2

[0051] Preparation of polypropylene recycled material, the specific steps are as follows:

[0052] The remaining steps remained unchanged, except that the vinyltriethoxysilane in Example 2 was replaced by 3-aminopropyltrimethoxysilane to prepare polypropylene recycled material.

[0053] Comparative Example 3

[0054] Preparation of polypropylene recycled material, the specific steps are as follows:

[0055] The remaining steps remain unchanged, except that the vinyl triethoxysilane in Example 2 is replaced by 3-aminopropyl trimethoxysilane, and the anti-aging agent is replaced by 0.4 parts of antioxidant 1010, 0.4 parts of light stabilizer GW-540 and 0.4 parts of antioxidant 4010 to prepare polypropylene recycled material.

[0056] Comparative Example 4

[0057] Preparation of polypropylene recycled material, the specific steps are as follows:

[0058] The remaining steps remain unchanged, only the anti-aging agent in Example 2 is removed to prepare the polypropylene recycled material.

[0059] Performance Testing

[0060] The polypropylene recycled materials obtained in Examples 2-4 and Comparative Examples 1-4 were made into corresponding samples according to the test standards and the following performance tests were performed:

[0061] The tensile strength test was carried out according to the ASTM D638-2010 standard, with a thickness of 3.0 mm. The wear resistance test was carried out according to the GB / T 9867-2008 standard. The tensile specimens were placed in a 150°C oven for aging for 200 hours, and the tensile strength after heat aging was tested. The tensile specimens were placed in a UV box for irradiation for 200 hours, with a light source of UVA-340, a light intensity of 0.76 W, and a cycle condition of 8 hours of illumination (BPT: 60°C), 4 hours of condensation (BPT: 50°C) (GB / T16422.3), and the tensile strength after UV aging was tested. The test results of all items are shown in Table 1 below:

[0062] Table 1

[0063] ;

[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. An aging-resistant polypropylene recycled material, characterized in that: The raw materials include the following parts by weight: 70 parts of recycled polypropylene resin, 20-30 parts of EPDM rubber, 15-25 parts of filler, 1-3 parts of coupling agent, 0.5-1.2 parts of anti-aging agent, 0.5-1 parts of lubricant, and 0.05-0.1 parts of initiator; The coupling agent is one or more of vinyl trimethoxy silane, vinyl triethoxy silane, 3-(methacryloyloxy)propyl trimethoxy silane, and vinyl tri(2-methoxyethoxy) silane; Wherein, the anti-aging agent is prepared by the following steps: S1. Add 2,6-di-tert-butyl-4-bromomethylphenol, N-isopropyl-N-phenyl-p-phenylenediamine and toluene into a flask under nitrogen protection, add triethylamine after stirring, react at 60° C. for 3 h, cool, distill under reduced pressure, purify by column chromatography, and distill under reduced pressure to obtain intermediate 1; S2, under nitrogen protection, add intermediate 1, hydroxyethyl methacrylate and DMSO into a flask, stir, add DBU, react at 60°C for 24h, distill under reduced pressure, purify by column chromatography, and distill under reduced pressure to obtain intermediate 2; S3, under nitrogen protection, add intermediate 2, maleic anhydride, DMAP and DMF to a flask, stir and react at 50°C for 12 hours, cool, centrifuge, take the supernatant and add saturated brine, dry the organic phase after separation, filter, distill the filtrate under reduced pressure, purify by column chromatography, and distill under reduced pressure to obtain intermediate 3; S4. Under nitrogen protection, add intermediate 3, 2,2,6,6-tetramethylpiperidinamine and DMF into a flask, add EDC and NHS, stir and react at 50°C for 6h, cool, and distill under reduced pressure to obtain an antioxidant.

2. The aging-resistant polypropylene recycled material according to claim 1, characterized in that: The usage ratio of 2,6-di-tert-butyl-4-bromomethylphenol, N-isopropyl-N-phenyl-p-phenylenediamine, triethylamine and toluene in step S1 is 23.9 g:19.6 g:14.5 mL:200 mL.

3. The aging-resistant polypropylene recycled material according to claim 1, characterized in that: The usage ratio of intermediate 1, hydroxyethyl methacrylate, DBU and DMSO in step S2 is 33.3 g:9.8 mL:2.2 mL:200 mL.

4. The aging-resistant polypropylene recycled material according to claim 1, characterized in that: The usage ratio of intermediate 2, maleic anhydride, DMAP and DMF in step S3 is 37.4 g:7.2 g:0.24 g:200 mL.

5. The aging-resistant polypropylene recycled material according to claim 1, characterized in that: The usage ratio of intermediate 3, 2,2,6,6-tetramethylpiperidinamine, EDC, NHS and DMSO in step S4 is 36.9 g:10.8 mL:0.31 g:0.19 g:200 mL.

6. The aging-resistant polypropylene recycled material according to claim 1, characterized in that: The filler is one or more of nano titanium dioxide, calcium carbonate, aluminum hydroxide, magnesium hydroxide, and silicon micropowder.

7. The aging-resistant polypropylene recycled material according to claim 1, characterized in that: The lubricant is one or more of polyethylene wax, stearic acid, zinc stearate, and butyl stearate.

8. The aging-resistant polypropylene recycled material according to claim 1, characterized in that: The initiator is one or more of dibenzoyl peroxide, diisopropylbenzene peroxide and azobisisobutyronitrile.

9. The method for preparing an aging-resistant polypropylene recycled material according to claim 1, characterized in that: The following steps are involved: The raw materials are weighed by weight and added into a mixer for mixing, and then put into a twin-screw extruder for melt blending, extrusion and drying to obtain aging-resistant polypropylene recycled material.