High-strength regenerated PET composite material and preparation method thereof

Abstract

The invention relates to a high-strength regenerated PET composite material and a preparation method thereof, and belongs to the technical field of polymer composite materials. The regenerated PET composite material is prepared from the following components in percentage by weight: 4.2 to 5.5 percent of reinforced regeneration agent, 0.06 to 0.08 percent of accelerant, 10 to 15 percent of calcium-based filler, 1.4 to 1.8 percent of lubricant, 0.1 to 0.12 percent of antioxidant and the balance of PET regenerated material, a main chain of the reinforced regeneration agent is a polyester chain, dispersity is improved through compatibilization, an oxazole ring on a side chain of the reinforced regeneration agent reacts with an aging fracture end group of a PET polymer, a sulfur-nitrogen structure formed by PET polymer chain repair and side chain addition forms a stable chelate ring with a calcium-based filler, and the calcium-based filler is introduced to a polymer repair node for reinforcement. The high-strength regeneration of the PET is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer composite materials, and specifically relates to a high-strength recycled PET composite material and a preparation method thereof. Background Art

[0002] Polyethylene terephthalate (PET) is widely used in the fields of packaging, fibers, electronic devices, and automotive parts due to its light weight, transparency, chemical resistance, and easy processability. However, the large-scale use of PET products has led to a sharp increase in waste volume. More than 30 million tons of PET waste are generated globally every year, and only about 30% of it is effectively recycled. Due to the influence of multiple processing and service environments, the molecular chains of recycled PET are prone to breakage (such as ester bond hydrolysis and thermal oxidative degradation), resulting in a significant decline in mechanical properties, which limits its application in high-end fields.

[0003] Currently, the modification technologies of recycled PET mainly focus on the following two categories: Physical blending enhancement: The mechanical properties are improved by adding fillers (such as glass fiber, calcium carbonate, etc.) or toughening agents (such as elastomers). However, the interfacial bonding between the filler and the PET matrix is weak, which is prone to cause stress concentration and cannot repair molecular chain damage. Chemical chain extension repair: Epoxy-based and oxazoline-based chain extenders are used to repair broken chains. However, traditional chain extension regenerants have insufficient compatibility with PET and low repair efficiency for short chains. Excessive regenerants will cause deterioration of mechanical properties. Summary of the Invention

[0004] In order to solve the technical problems mentioned in the background art, the purpose of the present invention is to provide a high-strength recycled PET composite material and a preparation method thereof.

[0005] The purpose of the present invention can be achieved by the following technical solutions: A high-strength recycled PET composite material, whose components are: 4.2 - 5.5 wt% of strengthening regenerant, 0.06 - 0.08 wt% of promoter, 10 - 15 wt% of calcium-based filler, 1.4 - 1.8 wt% of lubricant, and 0.1 - 0.12 wt% of antioxidant, and the balance is PET recycled material.

[0006] The preparation method of the strengthening regenerant is as follows: Step A1: Premix allyl bromide, triethylamine, and anhydrous tetrahydrofuran, protect with dry gas, add diethyl iminodiacetate and mix, heat to 60 - 70 °C and stir for reflux reaction for 3 - 4 h. After the reaction, rotary evaporate to remove tetrahydrofuran, wash the substrate with water, separate the liquid and dry it under vacuum to obtain a modified monomer. Furthermore, the feed ratio of diethyl iminodiacetate, allyl bromide, triethylamine and anhydrous tetrahydrofuran is 10mmol:12-15mmol:2-3mL:25-40mL. In an anhydrous environment, triethylamine promotes the substitution reaction of allyl bromide and diethyl iminodiacetate to introduce allyl structure modification.

[0007] Step A2: premixing the modified monomer, tetrabutyl titanate, sodium nitrite and dimethyl sulfoxide, adding polyester diol and mixing, introducing dry nitrogen for protection, heating to 160-200° C. and reacting for 2.5-3.5 hours. After the reaction is completed, dimethyl sulfoxide is removed by vacuum rotary evaporation to obtain a modified matrix; Furthermore, the feed ratio of the modified monomer, the hydroxyl content of the polyester diol, tetrabutyl titanate, sodium nitrite and dimethyl sulfoxide is 10mmol:20mmol:0.2-0.3g:15-30mg:20-30mL. At high temperature, tetrabutyl titanate promotes the alcohol ester exchange between the modified monomer and the polyester diol to form a low molecular weight polyester compound of the modified monomer block.

[0008] Preferably, the weight average molecular weight of the polyester diol is not higher than 2,000.

[0009] Step A3: Mix the modified substrate, 2-mercapto-5-methylbenzoxazole, tert-butyl peroxyacetate, photoinitiator 1173 and dimethylformamide, heat to 80-100°C, and heat at 500-800 mW / cm 2 The reaction was stirred and UV irradiated for 6-8 hours, and dimethylformamide was removed by vacuum rotary evaporation after the reaction to obtain a reinforced regeneration agent; Furthermore, the feed ratio of the modified matrix, 2-mercapto-5-methylbenzoxazole, tert-butyl peroxyacetate, photoinitiator 1173 and dimethylformamide is 10g:8-14mmol:20-30mg:50-70mg:30-40mL. Under the action of photoinitiation, 2-mercapto-5-methylbenzoxazole adds to the branched allyl structure introduced into the block of the modified matrix molecule.

[0010] Preferably, the promoter is selected from dibutyltin monobutyl maleate, which has good compatibility with the PET composite system and plays an efficient role in promoting the enhanced regeneration of recycled PET.

[0011] Preferably, the calcium-based filler is selected from light calcium carbonate with a fineness of 150-300 mesh.

[0012] A preparation method of a high-strength recycled PET composite material comprises the following steps: premixing PET recycled material, a strengthening regeneration agent, a accelerator, a lubricant and an antioxidant, plasticizing and mixing at 260-280° C., and then adding a calcium-based filler for extrusion and pelletizing.

[0013] Beneficial effects of the present invention: The present invention discloses a strengthening regenerant applicable to the PET system. It is prepared by subjecting allyl bromide and diethyl iminodiacetate to a substitution reaction to introduce an allyl structure for modification to form a modified monomer. Then, the modified monomer and polyester diol are subjected to alcohol-ester exchange to form a low-molecular-weight polyester compound with modified monomer blocks, which is the modified matrix. Finally, 2-mercapto-5-methylbenzoxazole is added to the branched allyl structure introduced in the block in the modified matrix molecule; the main chain of the strengthening regenerant is a polyester chain, which has good compatibility with the PET matrix and can be evenly dispersed during the blending and regeneration process. The oxazole ring on its side chain reacts with the aged and broken end groups of the PET polymer to repair the PET polymer chain. The sulfur-nitrogen structure formed by side chain addition forms a stable chelate ring with the calcium-based filler, and the calcium-based filler is introduced at the polymer repair nodes for strengthening. On the one hand, the mechanical properties of the recycled composite material are enhanced to achieve high-strength regeneration. On the other hand, the chelating force is less affected by external aging, realizing the long-term regeneration of the composite material and delaying the service life of the composite material. Specific Embodiments

[0014] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0015] Example 1. Preparation of recycled PET composite material is as follows: (1) Preparation of strengthening regenerant Step A1: Premix allyl bromide, triethylamine and anhydrous tetrahydrofuran, protect by introducing dry gas, add diethyl iminodiacetate and mix, heat to 60 °C and stir for reflux reaction for 4 h. Among them, the feeding ratio of diethyl iminodiacetate, allyl bromide, triethylamine and anhydrous tetrahydrofuran is 10 mmol: 12 mmol: 2 mL: 25 mL. After the reaction, rotary evaporation is used to remove tetrahydrofuran, the substrate is washed with water, separated by liquid and dried in vacuum to obtain the modified monomer.

[0016] Step A2: Premix the modified monomer, tetrabutyl titanate, sodium nitrite and dimethyl sulfoxide, then add polyester diol and mix, protect by introducing dry nitrogen, heat to 160 °C and react for 3.5 h. Among them, the polyester diol is selected from ODX-1118 type raw material with a weight average molecular weight of 1000. The feeding ratio of the modified monomer, the hydroxyl content of the polyester diol, tetrabutyl titanate, sodium nitrite and dimethyl sulfoxide is 10 mmol: 20 mmol: 0.2 g: 15 mg: 20 mL. After the reaction, rotary evaporation under reduced pressure is used to remove dimethyl sulfoxide to obtain the modified matrix.

[0017] Step A3: Mix the modified matrix, 2-mercapto-5-methylbenzoxazole, tert-butyl peroxyacetate, photoinitiator 1173, and dimethylformamide, heat up to 80 °C, and irradiate with UV and stir for reaction for 8 h at 500 mW / cm 2 The feeding ratio of the modified matrix, 2-mercapto-5-methylbenzoxazole, tert-butyl peroxyacetate, photoinitiator 1173, and dimethylformamide is 10 g: 8 mmol: 20 mg: 50 mg: 30 mL. After the reaction, dimethylformamide is removed by rotary evaporation under reduced pressure to obtain the enhanced regenerant.

[0018] (2) Preparation of recycled PET composite material Batching: Take raw materials according to weight percentage, 4.2 wt% of enhanced regenerant, self-made in this example; 0.06 wt% of accelerator, selected from dibutyltin monobutyl maleate; 10 wt% of calcium-based filler, selected from 300-mesh light calcium carbonate; 1.4 wt% of lubricant, selected from industrial-grade calcium stearate; 0.1 wt% of antioxidant, selected from antioxidant 1010 and antioxidant 168 compounded in equal weight ratio; the balance is recycled PET material, selected from recycled PET chips of Veolia Huafei Group.

[0019] Mixing and kneading: Premix the recycled PET material, enhanced regenerant, accelerator, lubricant, and antioxidant with a high-speed mixer, feed from the main feeding port of the twin-screw extruder, plasticize and knead at 260 °C, and add the calcium-based filler from the side feeding port and extrude and pelletize to obtain the recycled PET composite material.

[0020] Example 2, preparation of recycled PET composite material, is as follows: (1) Preparation of enhanced regenerant Step A1: Premix allyl bromide, triethylamine, and anhydrous tetrahydrofuran, protect with dry gas, add diethyl iminodiacetate and mix, heat up to 70 °C and stir and reflux for reaction for 3 h. The feeding ratio of diethyl iminodiacetate, allyl bromide, triethylamine, and anhydrous tetrahydrofuran is 10 mmol: 15 mmol: 3 mL: 40 mL. After the reaction, tetrahydrofuran is removed by rotary evaporation, the substrate is washed with water, separated by liquid separation and dried in vacuum to obtain the modified monomer.

[0021] Step A2: Premix the modified monomer, tetrabutyl titanate, sodium nitrite, and dimethyl sulfoxide, then add polyester diol and mix, protect with dry nitrogen, heat up to 200 °C and react for 2.5 h. The polyester diol is selected from ODX-218 type raw material with a weight average molecular weight of 2000. The feeding ratio of the modified monomer, hydroxyl content of polyester diol, tetrabutyl titanate, sodium nitrite, and dimethyl sulfoxide is 10 mmol: 20 mmol: 0.3 g: 30 mg: 30 mL. After the reaction, dimethyl sulfoxide is removed by rotary evaporation under reduced pressure to obtain the modified matrix.

[0022] Step A3: Mix the modified matrix, 2-mercapto-5-methylbenzoxazole, tert-butyl peroxyacetate, photoinitiator 1173, and dimethylformamide, heat up to 100 °C, and irradiate with UV and stir for reaction for 6 h at 800 mW / cm 2 wherein the feeding ratio of the modified matrix, 2-mercapto-5-methylbenzoxazole, tert-butyl peroxyacetate, photoinitiator 1173, and dimethylformamide is 10 g: 14 mmol: 30 mg: 70 mg: 40 mL. After the reaction, remove dimethylformamide by rotary evaporation under reduced pressure to obtain the enhanced regenerant.

[0023] (2) Preparation of regenerated PET composite Ingredient preparation: Take raw materials by weight percentage, 5.5 wt% of the enhanced regenerant, self-made in this example; 0.08 wt% of the promoter, selected from dibutyltin maleate monobutyl ester; 15 wt% of the calcium-based filler, selected from 150-mesh light calcium carbonate; 1.8 wt% of the lubricant, selected from industrial-grade calcium stearate; 0.12 wt% of the antioxidant, selected from antioxidant 1010 and antioxidant 168 compounded in an equal weight ratio; the balance is PET recycled material, selected from PET recycled chips of Veolia Huafei Group.

[0024] Mixing and kneading: Premix the PET recycled material, enhanced regenerant, promoter, lubricant, and antioxidant using a high-speed mixer, feed from the main feeding port of the twin-screw extruder, plasticize and mix at 280 °C, and add the calcium-based filler from the side feeding port and extrude and pelletize to obtain the regenerated PET composite.

[0025] Example 3: Preparation of the regenerated PET composite is as follows: (1) Preparation of the enhanced regenerant Step A1: Premix allyl bromide, triethylamine, and anhydrous tetrahydrofuran, protect with dry gas, add diethyl iminodiacetate and mix, heat up to 65 °C and stir and reflux for reaction for 3.5 h. Among them, the feeding ratio of diethyl iminodiacetate, allyl bromide, triethylamine, and anhydrous tetrahydrofuran is 10 mmol: 13 mmol: 3 mL: 35 mL. After the reaction, remove tetrahydrofuran by rotary evaporation, wash the substrate with water, separate the liquid, and dry in vacuum to obtain the modified monomer.

[0026] Step A2: Premix the modified monomer, tetrabutyl titanate, sodium nitrite, and dimethyl sulfoxide, then add polyester diol and mix, protect with dry nitrogen, heat up to 180 °C and react for 3 h. Among them, the polyester diol is selected from ODX-150 type raw material with a weight average molecular weight of 1500. The feeding ratio of the modified monomer, hydroxyl content of the polyester diol, tetrabutyl titanate, sodium nitrite, and dimethyl sulfoxide is 10 mmol: 20 mmol: 0.2 g: 25 mg: 30 mL. After the reaction, remove dimethyl sulfoxide by rotary evaporation under reduced pressure to obtain the modified matrix.

[0027] Step A3: Mix the modified substrate, 2-mercapto-5-methylbenzoxazole, tert-butyl peroxyacetate, photoinitiator 1173 and dimethylformamide, heat to 90°C, and heat at 700 mW / cm 2 The reaction was stirred under UV irradiation for 7 hours, wherein the feed ratio of the modified substrate, 2-mercapto-5-methylbenzoxazole, tert-butyl peroxyacetate, photoinitiator 1173 and dimethylformamide was 10 g: 10 mmol: 25 mg: 60 mg: 40 mL. After the reaction, the dimethylformamide was removed by vacuum rotary evaporation to obtain an enhanced regeneration agent.

[0028] (2) Preparation of recycled PET composite materials Ingredients: raw materials are taken according to weight percentage, 5.5wt% of the strengthening regeneration agent is self-made in this embodiment; 0.07wt% of the accelerator is selected from dibutyltin monobutyl maleate; 12wt% of the calcium-based filler is selected from 300 mesh light calcium carbonate; 1.5wt% of the lubricant is selected from industrial grade calcium stearate; 0.11wt% of the antioxidant is selected from antioxidant 1010 and antioxidant 168 compounded in an equal weight ratio; the remainder is PET recycled material, selected from PET recycled chips of Veolia Huafei Group.

[0029] Mixing: Premix PET recycled material, reinforcing regeneration agent, accelerator, lubricant and antioxidant in a high-speed mixer, feed from the main feeding port of a twin-screw extruder, plasticize and mix at 270°C, add calcium-based filler from the side feeding port, extrude and pelletize to obtain recycled PET composite material.

[0030] Example 4, preparing a recycled PET composite material, as follows: (1) Preparation of enhanced regeneration agent Step A1: premix allyl bromide, triethylamine and anhydrous tetrahydrofuran, pass dry gas protection, add diethyl iminodiacetate and mix, heat to 70°C, stir and reflux for reaction for 3.5h, wherein the feed ratio of diethyl iminodiacetate, allyl bromide, triethylamine and anhydrous tetrahydrofuran is 10mmol:12mmol:2mL:30mL. After the reaction, remove tetrahydrofuran by rotary evaporation, wash the substrate with water, separate the liquids and dry in vacuo to obtain a modified monomer.

[0031] Step A2: pre-mix the modified monomer, tetrabutyl titanate, sodium nitrite and dimethyl sulfoxide, add the polyester diol and mix, introduce dry nitrogen protection, heat to 190°C and react for 3.2 hours, wherein the polyester diol is selected from ODX-150 type raw material with a weight average molecular weight of 1500, and the feed ratio of the modified monomer, the hydroxyl content of the polyester diol, tetrabutyl titanate, sodium nitrite and dimethyl sulfoxide is 10mmol:20mmol:0.25g:20mg:30mL. After the reaction is completed, dimethyl sulfoxide is removed by reduced pressure rotary evaporation to obtain a modified matrix.

[0032] Step A3: Mix the modified matrix, 2-mercapto-5-methylbenzoxazole, tert-butyl peroxyacetate, photoinitiator 1173 and dimethylformamide, heat up to 85 °C, and irradiate with UV and stir for reaction for 7.5 h at 600 mW / cm 2 wherein the feeding ratio of the modified matrix, 2-mercapto-5-methylbenzoxazole, tert-butyl peroxyacetate, photoinitiator 1173 and dimethylformamide is 10 g: 12 mmol: 30 mg: 60 mg: 35 mL. After the reaction, remove dimethylformamide by rotary evaporation under reduced pressure to obtain the strengthened regenerant.

[0033] (2) Preparation of regenerated PET composite material Ingredient preparation: Take raw materials according to weight percentage, 5 wt% of strengthened regenerant, self-made in this example; 0.07 wt% of accelerator, selected from dibutyltin maleate monobutyl ester; 13 wt% of calcium-based filler, selected from 300-mesh light calcium carbonate; 1.6 wt% of lubricant, selected from industrial-grade calcium stearate; 0.12 wt% of antioxidant, selected from antioxidant 1010 and antioxidant 168 compounded in equal weight ratio; the balance is PET recycled material, selected from PET recycled chips of Veolia Huafei Group.

[0034] Mixing: Premix PET recycled material, strengthened regenerant, accelerator, lubricant and antioxidant with a high-speed mixer, feed from the main feeding port of the twin-screw extruder, plasticize and mix at 270 °C, add calcium-based filler from the side feeding port and extrude and pelletize to obtain the regenerated PET composite material.

[0035] Comparative example 1: Refer to Example 4, without adding the strengthened regenerant, and supplement with PET recycled material to 100 wt%.

[0036] Comparative example 2: Refer to Example 4, without adding the strengthened regenerant, add 3 wt% of bisoxazolinyl benzene and 2 wt% of silane coupling agent KH560, and the rest of the implementation process is exactly the same.

[0037] Take samples from the regenerated PET composite material prepared as above, hot press into specimens at 230 °C and 10 MPa, and conduct relevant performance tests on the specimens, as shown in Table 1 - Table 2 specifically; Table 1

[0038] Table 2

[0039] Combined with the test results in Table 1 - Table 2, it can be seen that the regenerated PET composite material prepared in the example has excellent strength and toughness, and still maintains high mechanical properties under ultraviolet aging and hydrothermal aging, realizing the high-strength and high-efficiency regeneration of PET.

[0040] In the description of the specification, the description referring to terms such as "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0041] The above content is only an example and explanation of the present invention. Those skilled in the art of the present technology can make various modifications or supplements to the described specific embodiments or use similar ways to replace them. As long as they do not deviate from the invention or exceed the scope defined by the claims of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A high-strength recycled PET composite material, characterized in that: Its components are: 4.2-5.5wt% of reinforcing regeneration agent, 0.06-0.08wt% of accelerator, 10-15wt% of calcium-based filler, 1.4-1.8wt% of lubricant and 0.1-0.12wt% of antioxidant, and the balance is PET recycled material; The preparation method of the enhanced regeneration agent is as follows: Step A1: premix allyl bromide, triethylamine and anhydrous tetrahydrofuran, pass dry gas protection, add diethyl iminodiacetate and mix, heat to 60-70° C., stir and reflux for reaction for 3-4 hours to obtain a modified monomer; Step A2: premixing the modified monomer, tetrabutyl titanate, sodium nitrite and dimethyl sulfoxide, adding polyester diol and mixing, introducing dry nitrogen for protection, heating to 160-200° C. and reacting for 2.5-3.5 hours to obtain a modified matrix, wherein the weight average molecular weight of the polyester diol is not higher than 2000; Step A3: Mix the modified substrate, 2-mercapto-5-methylbenzoxazole, tert-butyl peroxyacetate, photoinitiator 1173 and dimethylformamide, heat to 80-100°C, and heat at 500-800 mW / cm 2 The reaction was stirred and irradiated with UV for 6-8 hours to obtain a reinforced regeneration agent.

2. A high-strength recycled PET composite material according to claim 1, characterized in that: The feed ratio of diethyl iminodiacetate, allyl bromide, triethylamine and anhydrous tetrahydrofuran is 10 mmol: 12-15 mmol: 2-3 mL: 25-40 mL.

3. A high-strength recycled PET composite material according to claim 2, characterized in that: The feed ratio of the modified monomer, the hydroxyl content of the polyester diol, tetrabutyl titanate, sodium nitrite and dimethyl sulfoxide is 10mmol: 20mmol: 0.2-0.3g: 15-30mg: 20-30mL.

4. A high-strength recycled PET composite material according to claim 3, characterized in that: The feed ratio of the modified substrate, 2-mercapto-5-methylbenzoxazole, tert-butyl peroxyacetate, photoinitiator 1173 and dimethylformamide is 10 g: 8-14 mmol: 20-30 mg: 50-70 mg: 30-40 mL.

5. The high-strength recycled PET composite material according to claim 1, characterized in that: The accelerator is dibutyltin monobutyl maleate.

6. The high-strength recycled PET composite material according to claim 1, characterized in that: The calcium-based filler is light calcium carbonate with a fineness of 150-300 mesh.

7. A method for preparing the high-strength recycled PET composite material according to any one of claims 1 to 6, characterized in that: Specifically, PET recycled material, reinforcing regeneration agent, accelerator, lubricant and antioxidant are premixed, plasticized and mixed at 260-280℃, and then calcium-based filler is added for extrusion and pelletization.

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