A high-strength recycled PET composite material and its preparation method

Abstract

The present invention relates to a high-strength recycled PET composite material and a preparation method thereof, belonging to the technical field of polymer composite materials. The components of the recycled PET composite material are as follows: 4.2-5.5 wt% of a strengthening regenerant, 0.06-0.08 wt% of a promoter, 10-15 wt% of a calcium-based filler, 1.4-1.8 wt% of a lubricant, and 0.1-0.12 wt% of an antioxidant, with the balance being PET recycled material; the main chain of the strengthening regenerant is a polyester chain, which improves the dispersibility through compatibilization. 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 for strengthening at the polymer repair nodes, thereby realizing the high-strength regeneration of PET.

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 fields such as 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. 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:

[0004] Physical blending reinforcement: The mechanical properties are improved by adding fillers (such as glass fibers, calcium carbonate, etc.) or toughening agents (elastomers). However, the interfacial bonding between the filler and the PET matrix is weak, which is prone to cause stress concentration and cannot repair the damage of molecular chains.

[0005] Chemical chain extension repair: Epoxy-based and oxazoline-based chain extenders are used to repair broken chains. However, traditional chain extension-type regenerants have insufficient compatibility with PET, low repair efficiency for short chains, and excessive regenerants will cause deterioration of mechanical properties. Summary of the Invention

[0006] 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.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] 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, with the balance being PET recycled material.

[0009] The preparation method of the strengthening regenerant is as follows:

[0010] 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 ends, rotary evaporate to remove tetrahydrofuran, wash the substrate with water and mix, separate the liquid and dry it under vacuum to obtain a modified monomer.

[0011] Further, the feeding ratio of diethyl iminodiacetate, allyl bromide, triethylamine, and anhydrous tetrahydrofuran is 10 mmol: 12 - 15 mmol: 2 - 3 mL: 25 - 40 mL. Under an anhydrous environment, triethylamine promotes the substitution reaction of allyl bromide and diethyl iminodiacetate to introduce allyl structure modification.

[0012] Step A2: Premix the modified monomer, tetrabutyl titanate, sodium nitrite, and dimethyl sulfoxide, then add polyester diol and mix. Introduce dry nitrogen for protection, heat up to 160 - 200 °C, and react for 2.5 - 3.5 h. After the reaction, rotate and evaporate under reduced pressure to remove dimethyl sulfoxide to obtain the modified matrix.

[0013] Further, the feeding ratio of the modified monomer, the hydroxyl content of polyester diol, tetrabutyl titanate, sodium nitrite, and dimethyl sulfoxide is 10 mmol: 20 mmol: 0.2 - 0.3 g: 15 - 30 mg: 20 - 30 mL. At high temperature, tetrabutyl titanate promotes the alcoholysis reaction between the modified monomer and polyester diol to form a low - molecular - weight polyester compound with modified monomer segments.

[0014] Preferably, the weight - average molecular weight of the polyester diol is not higher than 2000.

[0015] Step A3: Mix the modified matrix, 2 - mercapto - 5 - methylbenzoxazole, tert - butyl peroxyacetate, photoinitiator 1173, and dimethylformamide, heat up to 80 - 100 °C, and perform UV irradiation and stirring reaction for 6 - 8 h. After the reaction, rotate and evaporate under reduced pressure to remove dimethylformamide to obtain the strengthening regenerant. 2

[0016] Further, the feeding ratio of the modified matrix, 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. Under the action of photoinitiation, 2 - mercapto - 5 - methylbenzoxazole adds to the branched allyl structure introduced by block in the modified matrix molecules.

[0017] Preferably, the accelerator is selected from dibutyltin monobutyl maleate, which has good compatibility with the PET composite system and plays an efficient promoting role in the strengthening regeneration of recycled PET.

[0018] Preferably, the calcium - based filler is selected from light calcium carbonate with a fineness of 150 - 300 mesh.

[0019] A preparation method of a high - strength recycled PET composite material is as follows: Premix the PET recycled material, strengthening regenerant, accelerator, lubricant, and antioxidant, plasticize and knead at 260 - 280 °C, and then add the calcium - based filler and extrude and pelletize. ​

[0020] Advantages of the present invention:

[0021] The present invention discloses a strengthening regenerant applicable to the PET system. It is prepared by substituting allyl bromide with diethyl iminodiacetate through a substitution reaction to introduce an allyl structure for modification to form a modified monomer. Then, the modified monomer undergoes alcohol-ester exchange with polyester diol to form a low-molecular-weight polyester compound with modified monomer segments, which is the modified matrix. Finally, 2-mercapto-5-methylbenzoxazole is added to the branched allyl structure introduced in the segments of the modified matrix molecules. 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 the side-chain addition forms a stable chelating 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

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0023] Example 1, preparing a recycled PET composite material, specifically as follows:

[0024] (1) Preparing the strengthening regenerant

[0025] Step A1: Premix allyl bromide, triethylamine, and anhydrous tetrahydrofuran, protect it by introducing a dry gas, add diethyl iminodiacetate and mix, heat up 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 ends, evaporate off the tetrahydrofuran by rotary evaporation, wash the substrate with water, separate the liquid, and dry it under vacuum to obtain the modified monomer.

[0026] 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 160°C and react for 3.5 hours, wherein the polyester diol is selected from ODX-1118 type raw material with a weight average molecular weight of 1000, 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:0.2g:15mg:20mL. After the reaction is completed, dimethyl sulfoxide is removed by reduced pressure rotary evaporation to obtain a modified matrix.

[0027] Step A3: Take the modified substrate, 2-mercapto-5-methylbenzoxazole, tert-butyl peroxyacetate, photoinitiator 1173 and dimethylformamide and mix them, raise the temperature to 80°C, and 2 The reaction was stirred under UV irradiation for 8 hours, wherein the feed ratio of the modified substrate, 2-mercapto-5-methylbenzoxazole, tert-butyl peroxyacetate, photoinitiator 1173 and dimethylformamide was 10 g: 8 mmol: 20 mg: 50 mg: 30 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

[0029] Ingredients: raw materials are taken according to weight percentage, 4.2wt% of the strengthening regeneration agent is self-made in this embodiment; 0.06wt% of the accelerator is selected from dibutyltin monobutyl maleate; 10wt% of the calcium-based filler is selected from 300 mesh light calcium carbonate; 1.4wt% of the lubricant is selected from industrial grade calcium stearate; 0.1wt% 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.

[0030] 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 260°C, add calcium-based filler from the side feeding port, extrude and pelletize to obtain recycled PET composite material.

[0031] Example 2, preparing a recycled PET composite material, as follows:

[0032] (1) Preparation of enhanced regeneration agent

[0033] 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 3h, wherein the feed ratio of diethyl iminodiacetate, allyl bromide, triethylamine and anhydrous tetrahydrofuran is 10mmol:15mmol:3mL:40mL. 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.

[0034] 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 200°C and react for 2.5 hours, wherein the polyester diol is selected from ODX-218 raw material with a weight-average molecular weight of 2000, 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:0.3g:30mg:30mL. After the reaction is completed, dimethyl sulfoxide is removed by reduced pressure rotary evaporation to obtain a modified matrix.

[0035] Step A3: Mix the modified substrate, 2-mercapto-5-methylbenzoxazole, tert-butyl peroxyacetate, photoinitiator 1173 and dimethylformamide, heat to 100°C, and heat at 800 mW / cm 2 The reaction was stirred under UV irradiation for 6 hours, wherein the feed ratio of the modified substrate, 2-mercapto-5-methylbenzoxazole, tert-butyl peroxyacetate, photoinitiator 1173 and dimethylformamide was 10 g: 14 mmol: 30 mg: 70 mg: 40 mL. After the reaction was completed, the dimethylformamide was removed by vacuum rotary evaporation to obtain an enhanced regeneration agent.

[0036] (2) Preparation of recycled PET composite materials

[0037] Ingredients: raw materials are taken according to weight percentage, 5.5wt% of the strengthening regeneration agent is self-made in this embodiment; 0.08wt% of the accelerator is selected from dibutyltin monobutyl maleate; 15wt% of the calcium-based filler is selected from 150 mesh light calcium carbonate; 1.8wt% of the lubricant is selected from industrial grade calcium stearate; 0.12wt% of the antioxidant is selected from antioxidant 1010 and antioxidant 168 in an equal weight ratio; the remainder is PET recycled material, selected from PET recycled chips of Veolia Huafei Group.

[0038] 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 280°C, add calcium-based filler from the side feeding port, extrude and pelletize to obtain recycled PET composite material.

[0039] Example 3, preparing a recycled PET composite material, as follows:

[0040] (1) Preparation of enhanced regeneration agent

[0041] Step A1: premix allyl bromide, triethylamine and anhydrous tetrahydrofuran, pass dry gas protection, add diethyl iminodiacetate and mix, heat to 65°C, stir and reflux for reaction for 3.5h, wherein the feed ratio of diethyl iminodiacetate, allyl bromide, triethylamine and anhydrous tetrahydrofuran is 10mmol:13mmol:3mL:35mL. 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.

[0042] 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 180°C and react for 3 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:0.2g:25mg:30mL. After the reaction is completed, dimethyl sulfoxide is removed by reduced pressure rotary evaporation to obtain a modified matrix.

[0043] 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.

[0044] (2) Preparation of recycled PET composite materials

[0045] 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.

[0046] 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.

[0047] Example 4, preparing a recycled PET composite material, as follows:

[0048] (1) Preparation of enhanced regeneration agent

[0049] 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.

[0050] 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.

[0051] Step A3: Mix the modified substrate, 2-mercapto-5-methylbenzoxazole, tert-butyl peroxyacetate, photoinitiator 1173 and dimethylformamide, heat to 85°C, and heat at 600 mW / cm 2 The reaction was stirred under UV irradiation for 7.5 h, wherein the feed ratio of the modified substrate, 2-mercapto-5-methylbenzoxazole, tert-butyl peroxyacetate, photoinitiator 1173 and dimethylformamide was 10 g:12 mmol:30 mg:60 mg:35 mL. After the reaction, the dimethylformamide was removed by vacuum rotary evaporation to obtain an enhanced regeneration agent.

[0052] (2) Preparation of recycled PET composite materials

[0053] Ingredients: raw materials are taken according to weight percentage, 5wt% of the strengthening regeneration agent is self-made in this embodiment; 0.07wt% of the accelerator is selected from dibutyltin monobutyl maleate; 13wt% of the calcium-based filler is selected from 300 mesh light calcium carbonate; 1.6wt% of the lubricant is selected from industrial grade calcium stearate; 0.12wt% 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.

[0054] Mixing: Premix PET recycled material, strengthening regenerant, accelerator, lubricant and antioxidant using 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 and extrude and pelletize to obtain recycled PET composite material.

[0055] Comparative Example 1: Refer to Example 4, without adding the strengthening regenerant, and use PET recycled material to supplement to 100 wt%.

[0056] Comparative Example 2: Refer to Example 4, without adding the strengthening regenerant, add 3 wt% of bisoxazoline benzene and 2 wt% of silane coupling agent KH560, and the rest of the implementation process is exactly the same.

[0057] Take samples from the recycled PET composite material prepared as above, hot press into specimens at 230 °C and 10 MPa, and conduct relevant performance tests on the specimens. See Tables 1 - 2 for details;

[0058] Table 1

[0059]

[0060] Table 2

[0061]

[0062] Combined with the test results in Tables 1 - 2, it can be seen that the recycled PET composite material prepared in the examples has excellent strength and toughness, and still maintains high mechanical properties under ultraviolet aging and hydrothermal aging, realizing high-strength and efficient recycling of PET.

[0063] 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 representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0064] The above content is only an example and explanation of the present invention. Those skilled in the art of this technology can make various modifications or supplements to the described specific embodiments or use similar methods 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 fall within the protection scope of the present invention.

Claims

1. A high-strength recycled PET composite material, characterized in that, Its components are: 4.2-5.5 wt% of enhanced regenerant, 0.06-0.08 wt% of accelerator, 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; The preparation method of the enhanced regenerant is as follows: Step A1: Premix allyl bromide, triethylamine and anhydrous tetrahydrofuran, protect with dry gas, add diethyl iminodiacetate and mix, heat up to 60-70 °C and stir and reflux for 3-4 h to obtain a modified monomer; 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 160-200 °C and react for 2.5-3.5 h 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 matrix, 2-mercapto-5-methylbenzoxazole, tert-butyl peroxyacetate, photoinitiator 1173 and dimethylformamide, heat up to 80-100 °C, and carry out UV irradiation stirring reaction at 500-800 mW / cm 2 for 6-8 h to obtain the enhanced regenerant.

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

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

4. The high-strength recycled PET composite material according to claim 3, characterized in that, The feeding ratio of the modified matrix, 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. A 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, wherein The calcium-based filler is light calcium carbonate with a fineness of 150-300 mesh.

7. A method for preparing a high-strength recycled PET composite material according to any one of claims 1-6, characterized in that, Specifically: Premix the PET recycled material, enhanced regenerant, accelerator, lubricant and antioxidant, plasticize and mix at 260-280 °C, and then add the calcium-based filler and extrude and pelletize.

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