A PCR-PET composition, a preparation method therefor, and use thereof

Abstract

This invention discloses a PCR-PET composition, its preparation method, and its application. The PCR-PET composition comprises, by weight, the following components: 78-88 parts PCR-PET resin; 12-20 parts toughening agent; 0.2-0.8 parts nucleating agent; and 0-0.5 parts antioxidant. This invention selects PCR-PET resin with a specific yellow flake content, adds a certain amount of toughening agent (E-MA-GMA or E-BA-GMA), and preferably has a high GMA content in the toughening agent, to prepare an impact strength >19 kJ / m. 2 The high-toughness PCR-PET composition, which produces injection-molded parts with good appearance, can meet the usage requirements of products with high toughness requirements and realize the recycling of PCR-PET.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a PCR-PET composition, its preparation method, and its application. Background Technology

[0002] Polyethylene terephthalate (PET) is a semi-crystalline thermoplastic polyester. Currently, besides its use in synthetic fibers, PET's applications have expanded to various types of containers, packaging materials, films, sheets, engineering plastics, and many other fields. With the significant increase in plastic consumption, recycling and reusing waste plastics has become a top priority for environmental protection efforts worldwide. PCR-PET, or post-consumer recycled PET, primarily originates from recycled PET bottles, such as mineral water bottles, beverage bottles, oil bottles, cosmetic bottles, and medicine bottles. Due to the recycling process, PCR-PET suffers a significant reduction in mechanical properties, particularly in toughness (its notched impact strength is typically only 2-4 kJ / m²). 2 This greatly limits the practical application of PCR-PET.

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

[0004] In order to overcome the shortcomings of the prior art, the present invention aims to provide a high-toughness PCR-PET composition with high impact strength and good appearance of its injection molded parts.

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

[0006] This invention is achieved through the following technical solution:

[0007] A PCR-PET composition, by weight, comprises the following components:

[0008] 78-88 parts of PCR-PET resin;

[0009] 12-20 parts toughening agent;

[0010] Nucleating agent 0.2-0.8 parts;

[0011] Antioxidant 0-0.5 parts.

[0012] The weight fractions of the PCR-PET resin can be 78, 80, 82, 84, 86, or 88 parts, or specific values ​​between the above-mentioned values.

[0013] The toughening agent can be present in weight parts of 12, 13, 14, 15, 16, 17, or 18 parts, or specific values ​​between the aforementioned values.

[0014] The weight percentage of the nucleating agent can be 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, or 0.8 parts, as well as specific values ​​between the above-mentioned values.

[0015] This invention uses "yellow flake content" to characterize the degree of aging and cross-linking of PCR-PET resin. The yellow flakes mentioned in this invention refer to PCR-PET fragments that, after being baked at 220℃ for 50 minutes, exhibit yellowing / darkening / carbonization and stickiness / oil precipitation on the surface.

[0016] The specific test method for the content of yellow flakes in PCR-PET resin according to the present invention is as follows: Take 1 kg of PCR-PET fragment sample (sample specifications: irregularly shaped fragments, thickness 0.2-0.8 mm, average diameter 10-14 mm, where the diameter is the maximum diameter of the irregularly shaped fragment sample), place it in a 220℃ oven, bake for 50 minutes, and immediately after removal, select the residual fragments in the PCR-PET, and remove the yellowed flakes, aged flakes, adhesive flakes, and oil flakes (the yellowed flakes are specifically fragments that turn yellow after baking and have no oil on the surface; the aged flakes are specifically fragments that are darker in color after baking; the adhesive flakes are fragments that carbonize and become sticky after baking; the oil flakes are fragments that turn yellow after baking and have oil precipitated on the surface; refer to...). Figure 1 (See the corresponding diagrams for yellowed / aged / adhesive / oiled flakes). Weigh the flakes and calculate the proportion of yellowed / aged / adhesive / oiled flakes in the total PCR-PET fragment sample. This proportion represents the yellow flake content of the PCR-PET resin.

[0017] Preferably, the PCR-PET resin selected in this invention has a yellow flake content of ≤2000ppm, and more preferably, it has a yellow flake content of 100-1200ppm. In the material system of this invention, if a PCR-PET resin with an excessively high yellow flake content is used, the resin system will undergo excessive aging and cross-linking, failing to obtain a high-toughness PCR-PET composition, and affecting the appearance of the injection-molded parts, resulting in problems such as wrinkles, shine, and yellowing.

[0018] The present invention further preferably uses PCR-PET resin with an intrinsic viscosity of 0.73~0.90 dL / g. The test standard for the intrinsic viscosity is GB / T 14190-2017.

[0019] Preferably, the PCR-PET of the present invention originates from post-consumer recycled PET bottles, including mineral water bottles, beverage bottles, oil bottles, cosmetic bottles, or medicine bottles.

[0020] The toughening agent of this invention is selected from any one or more of ethylene-methyl acrylate-glycidyl methacrylate block copolymer (E-MA-GMA) or ethylene-butyl acrylate-glycidyl methacrylate block copolymer (E-BA-GMA). Preferably, the GMA content in the toughening agent is 5-10%, more preferably 7-9%.

[0021] More preferably, the toughening agent has a melt index of 3-15 g / 10min at 190°C and 2.16 kg, more preferably 6-12 g / 10min. The melt index is tested according to ISO 1133-2011.

[0022] Preferably, the nucleating agent is selected from one of sodium montmorillonite soap, calcium montmorillonite soap, or amino acid calcium soap.

[0023] Preferably, the antioxidant is selected from at least one of hindered phenolic antioxidants, phosphite antioxidants, or thioether antioxidants. Further, the hindered phenolic antioxidant may be selected from pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0024] The present invention also provides a method for preparing the above-mentioned PCR-PET composition, comprising the following steps: according to the ratio, each component is added to a mixer and mixed evenly to obtain a premix; the premix is ​​melt-extruded by a twin-screw extruder at 190-270°C, cooled, and granulated to prepare the PCR-PET composition.

[0025] Preferably, the PCR-PET resin is first dried to a moisture content of less than 0.1% before being blended with other components.

[0026] Preferably, the temperatures of each screw barrel from the feed port to the die head in the twin-screw extruder are: 250-270℃, 240-260℃, 230-250℃, 190-210℃, 190-210℃, 190-210℃, 190-210℃, 200-220℃, and 220-240℃, respectively; the screw speed is 300-500 rpm; the feed rate is 200-400 kg / h; and the vacuum degree is (-0.1)-0 MPa.

[0027] The present invention also provides the application of the above-mentioned PCR-PET composition in the field of household appliances, specifically applicable to products with high requirements for toughness and excellent appearance, such as appliance housings.

[0028] The present invention has the following beneficial effects:

[0029] This invention selects PCR-PET resin with a specific content of yellow flakes, adds a certain amount of toughening agent (E-MA-GMA or E-BA-GMA), and preferably optimizes the GMA content of the toughening agent to prepare an impact strength >19kJ / m. 2 The high-toughness PCR-PET composition, which produces injection-molded parts with good appearance, can meet the usage requirements of products with high toughness and good appearance, and realizes the recycling of PCR-PET. Attached Figure Description

[0030] Figure 1 A schematic diagram of yellowed / aged / adhesive / oiled flakes used in the PCR-PET resin yellow flake content test. Implementation

[0031] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0032] The raw materials used in the embodiments and comparative examples of the present invention are described below, but are not limited to these materials:

[0033] PCR-PET resin 1: intrinsic viscosity is 0.73-0.8 dL / g, yellow flake content is 400 ppm, Suzhou Jiulong, SRPET-PGNC0123(LSK) 3A;

[0034] PCR-PET resin 2: intrinsic viscosity is 0.73 dL / g, yellow flake content is 2000 ppm, Jiulongtai Co., Ltd. & Xinhuatai Co., Ltd., JLT ZWT B2B white;

[0035] PCR-PET resin 3: intrinsic viscosity is 0.73-0.8 dL / g, yellow flake content is 1200 ppm, Suzhou Jiulong, SRPET-PGNC0123(LSK) A;

[0036] PCR-PET resin 4: intrinsic viscosity is 0.73 dL / g, yellow flake content is 4500 ppm, Jiulongtai Co., Ltd. & Xinhuatai Co., Ltd., JLT ZWT SHEET white;

[0037] Toughening agent 1: E-MA-GMA, GMA content 8%, melt index of 6 g / 10 min at 190℃ / 2.16 kg, Arkema, LOTADER AX8900;

[0038] Toughening agent 2: E-BA-GMA, GMA content 8%, melt index of 9 g / 10 min at 190℃ / 2.16 kg, Arkema, LOTADER AX8700;

[0039] Toughening agent 3: E-BA-GMA, GMA content 5%, melt index of 12g / 10min at 190℃ / 2.16kg, DuPont, ELVALOY RESINS PTW;

[0040] Toughening agent 4: E-MA-GMA, GMA content 3%, melt index of 7 g / 10 min at 190℃ / 2.16 kg, Arkema, LOTADER AX8930;

[0041] Toughening agent 5: EMA, GMA content 0%, melt index of 0.5 g / 10 min at 190℃ / 2.16 kg, DuPont, ELVALOY AC RESIN 1125;

[0042] Nucleating agent: Sodium montmorillonite soap, Guangzhou Fengtian Chemical Co., Ltd., LICOMONT NAV101 PWD;

[0043] Antioxidant: Pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], Sanfeng Chemical Co., Ltd., Linyi City, Shandong Province, SONOX 1010.

[0044] Preparation methods of PCR-PET compositions in the examples and comparative examples:

[0045] First, the PCR-PET resin is dried to a moisture content of less than 0.1%. Then, according to the formula, the PCR-PET resin and other components are added to a high-speed mixer and mixed for 2-5 minutes to obtain a premix. The premix is ​​then melt-extruded, cooled, and granulated using a twin-screw extruder to prepare the PCR-PET composition. The temperatures of the screw barrels from the feed port to the die head in the twin-screw extruder are: 250-270℃, 240-260℃, 230-250℃, 190-210℃, 190-210℃, 190-210℃, 190-210℃, 200-220℃, and 220-240℃, respectively. The screw speed is 300-500 rpm, the feed rate is 200-400 kg / h, and the vacuum degree is (-0.1)-0 MPa.

[0046] Relevant performance testing methods:

[0047] (1) Impact strength: Tested according to standard ISO 180-2019, the pendulum energy is 5.5J;

[0048] (2) Appearance evaluation: The appearance of the stretched spline is judged as follows:

[0049] Grade 1: Excellent appearance: The surface of the sample is flat and smooth, without yellowing or wrinkles;

[0050] Grade 2: Good appearance: The surface of the sample is flat, but slightly rough;

[0051] Grade 3: Poor appearance: The surface of the sample has wrinkles or is shiny and yellow, etc.

[0052] Table 1: Distribution ratios (by weight) and related performance test results for each group in Examples 1-7

[0053]

[0054] Table 2: Distribution ratios (by weight) and related performance test results for each group in Comparative Examples 1-5

[0055]

[0056] The results above show that by selecting PCR-PET resin with a specific content of yellow flakes, adding a certain amount of toughening agent (E-MA-GMA or E-BA-GMA), and preferably optimizing the GMA content of the toughening agent, an impact strength >19kJ / m is obtained. 2 A high-toughness PCR-PET composition that produces injection-molded parts with good appearance.

[0057] Comparative Example 1 uses PCR-PET resin with excessive yellow flake content, resulting in poor material toughness and poor appearance of injection molded parts.

[0058] Comparative Example 2 shows that a toughening agent with too low a GMA content cannot achieve the required toughness.

[0059] Comparative Example 3: Insufficient toughening agent resulted in poor material toughness.

[0060] Comparative Example 4: Excessive toughening agent addition, although resulting in high toughness, significantly reduces the melt index of the system due to the excessive toughening agent. Furthermore, the toughening agent tends to aggregate and disperse poorly, leading to poor appearance of the injection molded parts.

[0061] Comparative Example 5, using EMA toughening agent, failed to achieve the required toughness.

Claims

1. A PCR-PET composition, characterized in that, By weight, it includes the following components: 78-88 parts of PCR-PET resin; 12-20 parts toughening agent; Nucleating agent 0.2-0.8 parts; Antioxidant 0-0.5 parts; The yellow flakes content of the PCR-PET resin is ≤2000ppm. The yellow flakes are PCR-PET fragments that turn yellow, darken in color, carbonize and become sticky, and / or have oil precipitated on the surface after being baked at 220℃ for 50 minutes. The toughening agent is selected from any one or more of E-MA-GMA or E-BA-GMA, and the GMA grafting content in the toughening agent is 5-9%.

2. The PCR-PET composition according to claim 1, characterized in that, The yellow flake content of the PCR-PET resin is 100-1200 ppm.

3. The PCR-PET composition according to claim 1, characterized in that, The PCR-PET resin is derived from recycled PET bottles after consumption, including mineral water bottles, beverage bottles, oil bottles, cosmetic bottles, or medicine bottles.

4. The PCR-PET composition according to claim 1, characterized in that, The toughening agent contains 7-9% GMA grafting.

5. The PCR-PET composition according to claim 1, characterized in that, The nucleating agent is selected from one of sodium montmorillonite soap, calcium montmorillonite soap, or amino acid calcium soap.

6. The PCR-PET composition according to claim 1, characterized in that, The antioxidant is selected from at least one of hindered phenolic antioxidants, phosphite antioxidants, or thioether antioxidants.

7. The method for preparing the PCR-PET composition according to any one of claims 1-6, characterized in that, The process includes the following steps: according to the formula, each component is added to a mixer and mixed evenly to obtain a premix. The premix is ​​then melt-extruded, cooled, and granulated by a twin-screw extruder at 190-270°C to prepare a PCR-PET composition.

8. The application of the PCR-PET composition according to any one of claims 1-6 in the field of household appliances.

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