PCR-pet composition, and preparation method therefor and use thereof

Abstract

Disclosed in the present invention are a PCR-PET composition, and a preparation method therefor and a use thereof. The PCR-PET composition comprises the following components in parts by weight: 65-85 parts of a PCR-PET resin; 15-30 parts of POE-g-MAH; and 0.5-2 parts of an epoxy resin. According to the present invention, by selecting a PCR-PET resin having a specific PVC content, and adding certain amounts of POE-g-MAH and an epoxy resin, a high-toughness PCR-PET composition having the impact strength greater than 20 kJ / m2, the elongation at break greater than 22%, and good processing stability is prepared; the present invention can meet use requirements of products having high toughness requirements, and implements recycling of PCR-PET.

Description

A PCR-PET composition and its preparation method and application Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to a PCR-PET composition, a preparation method and an application thereof. Background Art

[0002] Polyethylene terephthalate (PET) is a semi-crystalline thermoplastic polyester. In addition to being used for synthetic fibers, PET has been expanded to various types of containers, packaging materials, films, films, engineering plastics and many other fields. With the substantial increase in the use of plastics, recycling and reusing waste plastics as resources has become a top priority for environmental protection in countries around the world. PCR-PET is post-consumer recycled PET, and its main source is post-consumer recycled PET bottles. Due to the recycling process, the mechanical properties of PCR-PET are greatly reduced, especially the toughness is poor (the notched impact strength is generally only 2-4kJ / m 2 ), and has poor thermal stability. Carbonization problems are prone to occur during the recycling process, and strict control of process conditions is required. This greatly limits the practical application of PCR-PET, especially in the field of toys with high toughness requirements and products that need to pass throwing tests / drop tests. PCR-PET is difficult to meet its usage requirements.

[0003] Chinese patent application CN115895208A discloses a PET composite material containing a PCR-PET film material. The PCR-PET film material and a nucleating agent are used to improve the crystallization properties of PET, thereby enhancing the mechanical properties and heat resistance. However, the toughness of the material is not significantly improved. Summary of the Invention

[0004] In order to overcome the deficiencies of the prior art, the present invention aims to provide a PCR-PET composition having high toughness, good elongation at break and good processing stability.

[0005] Another object of the present invention is to provide a method for preparing the above-mentioned PCR-PET composition.

[0006] The present invention is achieved through the following technical solutions:

[0007] A PCR-PET composition, comprising the following components in parts by weight:

[0008] 65-85 parts of PCR-PET resin;

[0009] POE-g-MAH 15-30 parts;

[0010] 0.5-2 parts of epoxy resin.

[0011] The weight parts of the PCR-PET resin can be 65 parts, 70 parts, 75 parts, 80 parts or 85 parts, as well as specific values ​​between the above points.

[0012] The weight proportions of the POE-g-MAH may be 15 parts, 18 parts, 20 parts, 22 parts, 24 parts, 26 parts, 28 parts or 30 parts, as well as specific values ​​between the above values.

[0013] The weight percentage of the epoxy resin can be 0.5 parts, 0.8 parts, 1 parts, 1.2 parts, 1.5 parts, 1.8 parts or 2 parts, as well as specific values ​​between the above points.

[0014] Preferably, the present invention selects a PCR-PET resin with a PVC content of less than 60 ppm, more preferably a PCR-PET resin with a PVC content of 10-55 ppm, and even more preferably a PCR-PET resin with a PVC content of 20-40 ppm. In the material system of the present invention, if a PCR-PET resin with too high a PVC content is used, the material toughness may not meet the required performance. Experimental analysis suggests that this may be because the PCR-PET resin with too high a PVC content generates acidity during extrusion, causing chain scission and degradation of the PCR-PET molecular chain, reducing the viscosity of the system and severely degrading the material toughness.

[0015] The present invention provides a method for testing PVC content, which comprises taking 1 kg of a PCR-PET fragment sample (sample specifications: irregularly shaped fragments, thickness 0.2-0.8 mm, average diameter 12-14 mm, where the diameter is the maximum diameter of the irregularly shaped fragment sample), placing the sample in a 220° C. oven, and baking the sample for 50 minutes. After removal, the PCR-PET sample is selected, and the blackened sample is removed with tweezers and weighed using an electronic balance (Mettler Toledo, model: MS204TS / 02). The weight ratio of the blackened sample to the total PCR-PET sample is calculated, which is the PVC content of the PCR-PET resin.

[0016] The present invention further prefers PCR-PET resins having an intrinsic viscosity of 0.73 to 0.90 dL / g. The intrinsic viscosity is tested in accordance with GB / T 14190-2017.

[0017] Preferably, the PCR-PET of the present invention is sourced from recycled mineral water bottles after consumption, with a melting point range of 245-265°C.

[0018] Preferably, in the PCR-PET composition of the present invention, the mass percentage of the PCR-PET resin is not less than 68%.

[0019] The POE-g-MAH described in the present invention is maleic anhydride-grafted POE. When POE-g-MAH is used alone, a highly tough PCR-PET composition cannot be obtained, possibly due to limited compatibility between POE-g-MAH and PCR-PET or weak end-group reactivity between POE-g-MAH and PCR-PET. However, the present invention significantly improves the toughness, thermal stability, and processing stability of the material by adding an epoxy resin to the POE-g-MAH. This is presumably because the epoxy groups in the epoxy resin open during the extrusion process and react with the MAH in the POE-g-MAH and the end groups of the PCR-PET to form a bridging effect, thereby significantly improving the toughness of the system, while also effectively enhancing the thermal stability of the material and improving the processing stability during extrusion.

[0020] Preferably, the MAH graft content in the POE-g-MAH is 0.45-1.5%, more preferably 0.8-1.2%. The MAH graft content is tested as follows:

[0021] Accurately weigh 1g of POE-g-MAH sample and heat under reflux in a xylene solution to dissolve the grafted material. While hot, titrate with a 0.1mol / L KOH-ethanol standard solution using colorless phenolphthalein test solution as an indicator. Stir while titrating to allow the anhydride and base to fully react. When the solution turns red, record the volume of KOH-ethanol standard solution used (V1). Back-titrate the excess KOH-ethanol standard solution with an HCl-isopropanol standard solution of the same concentration. Stop the titration when the solution turns from red to colorless and record the volume of HCl-isopropanol standard solution used (V2). The grafting rate is calculated as follows:

[0022]

[0023] Where: G: grafting rate

[0024] C: concentration of KOH-ethanol and HCl-isopropanol standard solutions (mol / L);

[0025] M: molecular weight of MAH 98.06 (g / mol);

[0026] m: mass of the grafted material (g).

[0027] Preferably, the epoxy equivalent weight of the epoxy resin is 170-4200 g / mol, more preferably 2200-4000 g / mol.

[0028] More preferably, the weight percentage of the epoxy resin is 2.5%-10%, more preferably 6%-8.5%, of the weight percentage of the POE-g-MAH. Excessive use of epoxy resin may leave some epoxy groups unreacted, which can easily cause the screw to stick during extrusion, leading to extrusion stagnation and carbonization.

[0029] Preferably, the PCR-PET composition of the present invention further comprises 0.2-0.8 parts by weight of a nucleating agent; the nucleating agent is selected from at least one of sodium montmorillonite soap, calcium montmorillonite soap, or amino acid calcium soap. The nucleating agent is preferably selected from at least one of sodium montmorillonite soap, calcium montmorillonite soap, or amino acid calcium soap.

[0030] Preferably, the PCR-PET composition of the present invention further comprises 0.1-0.5 parts by weight of an antioxidant; the antioxidant is preferably selected from at least one of a hindered phenol antioxidant, a phosphite antioxidant, or a thioether antioxidant. Furthermore, the hindered phenol antioxidant can be selected from pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0031] The present invention also provides a method for preparing the above-mentioned PCR-PET composition, comprising the following steps: mixing the components uniformly according to the proportion, and then melt-extruding and granulating them through a twin-screw extruder to prepare the PCR-PET composition.

[0032] Preferably, the PCR-PET resin is dried in advance to a moisture content of less than 0.1% and then blended with other components.

[0033] Preferably, the temperatures of the barrels of the twin-screw extruder from the feeding port to the die are: 250-270°C, 240-260°C, 230-250°C, 190-210°C, 190-210°C, 190-210°C, 190-210°C, 200-220°C, 220-240°C, the screw speed is 300-500 rpm, the feed rate is 200-400kg / h, and the vacuum degree is (-0.1)-0Mpa.

[0034] The present invention also provides an application of the above-mentioned PCR-PET composition in the field of toys, which is specifically suitable for products with high toughness requirements and need to pass throwing tests or drop tests, such as building blocks.

[0035] The present invention has the following beneficial effects:

[0036] The present invention selects PCR-PET resin with a specific PVC content, adds a certain amount of POE-g-MAH and epoxy resin, and prepares a resin with an impact strength of >20 kJ / m 2The high-toughness PCR-PET composition with a breaking elongation of >22% and good processing stability can meet the use requirements of products with high toughness requirements and realize the recycling of PCR-PET. DETAILED DESCRIPTION

[0037] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several variations and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0038] The raw materials used in the examples and comparative examples of the present invention are described below, but are not limited to these materials:

[0039] PCR-PET resin 1: intrinsic viscosity 0.73-0.8 dL / g, PVC content 20 ppm, Suzhou Jiulong, SRPET-PGNC0123(LSK) 3A;

[0040] PCR-PET resin 2: intrinsic viscosity 0.73-0.8 dL / g, PVC content 50 ppm, Suzhou Jiulong, SRPET-PGNC0123(LSK) 2A;

[0041] PCR-PET resin 3: intrinsic viscosity 0.73-0.8 dL / g, PVC content 100 ppm, Suzhou Jiulong, SRPET-PGNC0123(LSK) A;

[0042] PCR-PET resin 4: intrinsic viscosity 0.73-0.8 dL / g, PVC content 200 ppm, Suzhou Jiulong, SRPET-PGNC0123(LSK) B;

[0043] POE-g-MAH 1: MAH grafting rate 0.9%, Foshan Nanhai Bochen Polymer New Materials Co., Ltd., PC-28;

[0044] POE-g-MAH 2: MAH grafting rate 0.5%, Ningbo Nengzhiguang New Material Technology Co., Ltd., N406;

[0045] Epoxy resin 1: epoxy equivalent weight 2200-4000 g / mol, Nantong Xingchen Synthetic Materials Co., Ltd., 0199;

[0046] Epoxy resin 2: epoxy equivalent weight 170-190 g / mol, Shandong Aimonte New Materials Co., Ltd., EMTE-502;

[0047] Nucleating agent: sodium montmorillonite soap, Guangzhou Fengtian Chemical Co., Ltd., LICOMONT NAV101 PWD;

[0048] Antioxidant: Pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, SONOX 1010, Linyi Sanfeng Chemical Co., Ltd., Shandong Province.

[0049] Preparation methods of the PCR-PET compositions of the Examples and Comparative Examples:

[0050] First, the PCR-PET resin is dried in advance to a moisture content of less than 0.1%; according to the ratio, the PCR-PET resin is added to a high-speed mixer together with other components and mixed for 2-5 minutes to obtain a premix, and the premix is ​​melt-extruded, cooled, and granulated through a twin-screw extruder to prepare a PCR-PET composition; wherein, the temperatures of the barrels of the twin-screw extruder from the feed port to the die are: 250-270°C, 240-260°C, 230-250°C, 190-210°C, 190-210°C, 190-210°C, 190-210°C, 190-210°C, 200-220°C, 220-240°C, the screw speed is 300-500 rpm, the feed rate is 200-400 kg / h, and the vacuum degree is (-0.1)-0 MPa.

[0051] Related performance test methods:

[0052] (1) Impact strength: Tested according to ISO 180-2019, pendulum energy 5.5 J;

[0053] (2) Elongation at break: Tested according to ISO 527-2-2012, with a test speed of 50 mm / min;

[0054] (3) Throwing test: The product size is 5cm*3cm*7cm (length, width and height) (toy sample), the height is 1m, the fixed thrust is 10N, and a single product is thrown repeatedly 20 times to see if the product breaks and judge whether it is OK or NG;

[0055] (4) Thermal stability test (mass change under constant temperature TG): 5-10 mg of particles were tested under constant temperature TG in N2 atmosphere at 250°C for 30 min. The thermal stability of the material was determined by the amount of mass loss.

[0056] (5) Processing conditions: Observe whether the particles turn yellow or black during the extrusion process. If so, it indicates carbonization problems.

[0057] Table 1: Distribution ratios of each group in Examples 1-9 (by weight) and related performance test results

[0058] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 PCR-PET resin 17878787878836878 PCR-PET resin 278 PCR-PET resin 3 PCR-PET resin 4 POE-g-MAH 12020202020153020 POE-g-MAH 220 Epoxy resin 11.51.51.50.521.51.51.5 Epoxy resin 21.5 Nucleating agent 0.30.30.30.30.30.30.30.30.3 Antioxidant 0.20.20.20.20.20.20.20.2 / Notched impact strength kJ / m 2 30.824.224.429.621.650.220.455.130.2Elongation at break%28.523.427.426.224.634.322.840.227.8Throwing testOKOKOKOKOKOKOKOKOKOKConstant temperature TGMass change%2.53.12.92.63.72.32.73.32.8ProductionCarbonization or notNo carbonizationNo carbonizationNo carbonizationNo carbonizationNo carbonizationNo carbonizationNo carbonizationNo carbonizationNo carbonizationNo carbonizationNo carbonizationNo carbonization

[0059] Table 2: Distribution ratio of each group of comparative examples 1-6 (by weight) and related performance test results

[0060] Comparative Example 1Comparative Example 2Comparative Example 3Comparative Example 4Comparative Example 5Comparative Example 6PCR-PET resin 178787878PCR-PET resin 2PCR-PET resin 378PCR-PET resin 478POE-g-MAH 1202020201040POE-g-MAH 2Epoxy resin 11.51.5 / 41.51.5Epoxy resin 2Nucleating agent 0.30.30.30.30.30.3Antioxidant 0.20.20.20.20.20.2Notched impact strength kJ / m 2 8.45.68.750.88.263.4Elongation at break%13.112.210.235.412.355.1Throwing testNGNGNGOKNGNGDeformationConstant temperatureTGMass change%7.210.86.28.43.58.8ProductionCarbonization or notNo carbonizationNo carbonizationNo carbonizationCarbonizationNo carbonizationCarbonization

[0061] From the above results, it can be seen that the present invention selects PCR-PET resin with a specific PVC content, adds a certain amount of POE-g-MAH and epoxy resin, and prepares a high-toughness PCR-PET composite with an impact strength of >20 kJ / m 2 , elongation at break>22%, able to pass the throwing test; and effectively improves the thermal stability of the material, has good processing stability, and there is no carbonization problem during the extrusion process.

[0062] Comparative Example 1 / 2 uses PCR-PET resin with too high PVC content, the material has poor toughness and cannot pass the throwing test, and the material has poor thermal stability.

[0063] In Comparative Example 3, no epoxy resin was added, and good toughness could not be obtained, and the throwing test failed.

[0064] In Comparative Example 4, the amount of epoxy resin used was too much. Although the toughness was high, some epoxy groups were unreacted, which made it easy to stick to the screw during the extrusion process, causing extrusion retention and leading to carbonization problems.

[0065] In comparative example 5, the amount of POE-g-MAH added was too little, the material toughness was poor, and it could not pass the throwing test.

[0066] In Comparative Example 6, too much POE-g-MAH was added. Since POE-g-MAH itself has low heat resistance and a high POE-g-MAH content reduces the fluidity of the system, the viscosity of the extruded melt increases, thereby causing carbonization problems.

Claims

1. A PCR-PET composition, characterized in that: By weight, it includes the following components: PCR-PET resin 65-85 parts; POE-g-MAH 15-30 parts; Epoxy resin 0.5-2 parts.

2. The PCR-PET composition according to claim 1, characterized in that The PVC content of the PCR-PET resin is <60ppm; preferably, the PVC content of the PCR-PET resin is 10-55ppm; more preferably, the PVC content of the PCR-PET resin is 20-40ppm.

3. The PCR-PET composition according to claim 1, characterized in that The MAH grafting rate in the POE-g-MAH is 0.45-1.5%, preferably 0.8-1.2%.

4. The PCR-PET composition according to claim 1, characterized in that The epoxy equivalent of the epoxy resin is 170-4200 g / mol, preferably 2200-4000 g / mol.

5. The PCR-PET composition according to claim 1, characterized in that The weight proportion of the epoxy resin is 2.5%-10% of POE-g-MAH, preferably 6%-8.5%.

6. The PCR-PET composition according to claim 1, characterized in that By weight, it also includes 0.2-0.8 parts of a nucleating agent; the nucleating agent is selected from at least one of sodium montmorillonite soap, calcium montmorillonite soap or amino acid calcium soap.

7. The PCR-PET composition according to claim 1, characterized in that The invention also includes 0.1-0.5 parts of antioxidant by weight; the antioxidant is selected from at least one of hindered phenol antioxidants, phosphite antioxidants or thioether antioxidants.

8. The method for preparing the PCR-PET composition according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: according to the proportion, each component is uniformly mixed, and then melt-extruded and granulated by a twin-screw extruder to prepare a PCR-PET composite.

9. Use of the PCR-PET composition according to any one of claims 1 to 7 in the field of toys.

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