WO2025108000A1 - Pcr-pet composition, and preparation method therefor and use thereof - Google Patents

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: 78-88 parts of a PCR-PET resin; 12-20 parts of a toughening agent; 0.2-0.8 parts of a nucleating agent; and 0-0.5 parts of an antioxidant. According to the present invention, a PCR-PET resin having a specific yellow flake content is selected, a certain amount of a toughening agent (E-MA-GMA or E-BA-GMA) is added, and the GMA content of the toughening agent is optimized, such that a high-toughness PCR-PET composition having an impact strength greater than 19 kJ/m² and allowing for production of injection molded parts having good appearance is prepared, thereby satisfying the use requirements of products having high toughness and realizing recycling of PCR-PET.

Description

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

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

Background Art

Polyethylene terephthalate (PET) is a semi-crystalline thermoplastic polyester. In addition to being used for synthetic fibers, PET has been applied 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, such as mineral water bottles, beverage bottles, oil bottles, cosmetic bottles, and medicine bottles. Due to the recycling process, the mechanical properties of PCR-PET are greatly reduced, especially the poor toughness (the notched impact strength is generally only 2-4kJ/ ^m2 ), which greatly limits the practical application of PCR-PET.

Chinese patent application CN115895208A discloses a PET composite material containing a PCR-PET film material, which uses a PCR-PET film material and a nucleating agent to improve the crystallization properties of PET, thereby improving the mechanical properties and heat resistance, but the toughness of the material is not well improved.

Summary of the invention

In order to overcome the deficiencies of the prior art, the present invention aims to provide a high-toughness PCR-PET composition having high impact strength and good appearance of injection molded parts.

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

The present invention is achieved through the following technical solutions:

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

PCR-PET resin 78-88 copies;

Toughening agent 12-20 parts;

Nucleating agent 0.2-0.8 parts;

Antioxidant                0-0.5 parts.

The weight proportions of the PCR-PET resin may be 78 parts, 80 parts, 82 parts, 84 parts, 86 parts or 88 parts, as well as specific proportions between the above proportions.

The weight percentage of the toughening agent can be 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts or 18 parts, as well as specific values between the above points.

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, and specific values between the above points.

The present invention uses "yellow flake content" to characterize the aging crosslinking degree of PCR-PET resin. The yellow flakes in the present invention refer to PCR-PET fragments that turn yellow/darken/carbonize and become sticky/exude grease on the surface after being baked at 220°C for 50 minutes.

The specific test method for the yellow flake content of the PCR-PET resin of the present invention is as follows: take 1 kg of PCR-PET fragment samples (sample specifications: irregularly shaped fragments, thickness 0.2-0.8 mm, average diameter 10-14 mm, the diameter is the maximum diameter of the irregularly shaped fragment samples), put them into a 220°C oven, bake for 50 minutes, and immediately select the residual fragments in the PCR-PET after taking them out, and take out the yellowed flakes, aged flakes, sticky flakes and oily flakes (the yellowed flakes are specifically fragments that turn yellow after baking and have no grease on the surface; the aged flakes are specifically fragments with a darker color after baking; the sticky flakes refer to fragments that are carbonized and sticky on the surface after baking; the oily flakes refer to fragments that turn yellow after baking and have grease precipitated on the surface; refer to the schematic diagram of yellowed flakes/aged flakes/sticky flakes/oil flakes corresponding to Figure 1), weigh them, and calculate the proportion of yellowed flakes/aged flakes/sticky flakes/oil flakes in the total PCR-PET fragment samples, which is the yellow flake content of the PCR-PET resin.

Preferably, the present invention is selected from PCR-PET resins with a yellow flake content of ≤2000ppm, and more preferably PCR-PET resins with a yellow flake content of 100-1200ppm. In the material system of the present invention, if a PCR-PET resin with too high a yellow flake content is used, the resin system will be too highly cross-linked after aging, and a high-toughness PCR-PET composition cannot be obtained, and the appearance of the injection molded parts will be affected, resulting in wrinkles/shiny/yellowing and other problems.

The present invention further prefers a PCR-PET resin having an intrinsic viscosity of 0.73 to 0.90 dL/g. The test standard for the intrinsic viscosity is GB/T 14190-2017.

Preferably, the PCR-PET of the present invention is derived from post-consumer recycled PET bottles, including mineral water bottles, beverage bottles, oil bottles, cosmetic bottles or pharmaceutical bottles.

The toughening agent of the present 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%.

More preferably, the melt index of the toughening agent at 190°C and 2.16 kg is 3-15 g/10 min, more preferably 6-12 g/10 min. The melt index test standard is ISO 1133-2011.

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

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

The present invention also provides a method for preparing the above-mentioned PCR-PET composition, comprising the following steps: adding each component into a mixer according to a ratio and mixing them evenly to obtain a premix; the premix is melt-extruded at 190-270° C. through a twin-screw extruder, cooled, and granulated to prepare the PCR-PET composition.

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

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, 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.

The present invention also provides the application of the above-mentioned PCR-PET composition in the field of household appliances, which is specifically suitable for products with high requirements on product toughness and excellent appearance, such as electrical appliance housings.

The present invention has the following beneficial effects:

The present 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 optimizes the GMA content of the toughening agent to prepare a high-toughness PCR-PET composition with an impact strength of more than 19 kJ/m ² and good appearance of injection molded parts, which can meet the use requirements of products with high toughness and good appearance, and realizes the recycling of PCR-PET.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of yellowing flakes/aging flakes/sticky flakes/oily flakes when testing the yellow flake content of PCR-PET resin.

DETAILED DESCRIPTION

The present invention is described in detail below in conjunction with 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 of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

The raw materials used in the embodiments and comparative examples of the present invention are described as follows, but are not limited to these materials:

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

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

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

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

Toughener 1: E-MA-GMA, GMA content 8%, melt index at 190℃/2.16kg is 6g/10min, Arkema, LOTADER AX8900;

Toughener 2: E-BA-GMA, GMA content 8%, melt index at 190℃/2.16kg is 9g/10min, Arkema, LOTADER AX8700;

Toughener 3: E-BA-GMA, GMA content 5%, melt index at 190℃/2.16kg is 12g/10min, DuPont, ELVALOY RESINS PTW;

Toughener 4: E-MA-GMA, GMA content 3%, melt index at 190℃/2.16kg is 7g/10min, Arkema, LOTADER AX8930;

Toughener 5: EMA, GMA content is 0%, melt index at 190℃/2.16kg is 0.5g/10min, DuPont, ELVALOY AC RESIN 1125;

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

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

Preparation method of PCR-PET composition of embodiment and comparative example:

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 by 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 200-400kg/h, and the vacuum degree is (-0.1)-0Mpa.

Related performance test methods:

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

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

Level 1: Excellent appearance: The surface of the spline is flat and smooth, without yellowing or wrinkles;

Level 2: Good appearance: The surface of the spline is flat and slightly rough;

Level 3: Poor appearance: The surface of the specimen is wrinkled or shiny or yellow.

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

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 PCR-PET resin 1 84.5 84.5 84.5 78 84.5 PCR-PET resin 2 84.5 PCR-PET resin 3 88 Toughener 1 15 15 12 20 15 Toughener 2 15 Toughener 3 15 Nucleating Agent 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Antioxidants 0.2 0.2 0.2 0.2 0.2 0.2 / Notched impact strength kJ/m ² 36.2 22.4 36.5 20.3 19.8 48.2 35.8 Appearance Level 1 Level 2 Level 1 Level 1 Level 1 Level 1 Level 1

Table 2: Distribution ratio of each group in comparative examples 1-5 (by weight) and related performance test results

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 PCR-PET resin 1 84.5 84.5 84.5 84.5 PCR-PET resin 4 84.5 Toughener 1 15 5 30 Toughener 4 15 Toughener 5 15 Nucleating Agent 0.3 0.3 0.3 0.3 0.3 Antioxidants 0.2 0.2 0.2 0.2 0.2 Notched impact strength kJ/m ² 8.9 11.8 4.2 56.8 7.8 Appearance Level 3 Level 1 Level 1 Level 3 Level 2

From the above results, it can be seen that the present 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 optimizes the GMA content of the toughening agent to prepare a high-toughness PCR-PET composition with an impact strength of >19kJ/ ^m2 and good appearance of injection molded parts.

Comparative Example 1 uses PCR-PET resin with too high a yellow flake content, resulting in poor material toughness and poor appearance of the injection molded product.

In Comparative Example 2, a toughening agent with too low a GMA content was used, and the required toughness could not be achieved.

In comparative example 3, the amount of toughening agent added is too small, and the toughness of the material is poor.

In Comparative Example 4, too much toughening agent was added. Although the toughness was high, the excessive toughening agent significantly reduced the melt index of the system, and the toughening agent aggregated itself and was not well dispersed, which resulted in poor appearance of the injection molded part.

Comparative Example 5, using EMA toughening agent, cannot achieve the required toughness.

Claims (10)

A PCR-PET composition, characterized in that it comprises the following components in parts by weight: PCR-PET resin 78-88 copies; Toughening agent 12-20 parts; Nucleating agent 0.2-0.8 parts; Antioxidant                0-0.5 parts. The PCR-PET composition according to claim 1 is characterized in that the yellow flake content of the PCR-PET resin is ≤2000ppm, preferably, the yellow flake content of the PCR-PET resin is 100-1200ppm. The PCR-PET composition according to claim 2 is characterized in that the yellow flakes are PCR-PET fragments that turn yellow, darken in color, become carbonized and sticky, and/or have grease precipitated on the surface after being baked at 220° C. for 50 minutes. The PCR-PET composition according to claim 1 is characterized in that the PCR-PET resin is derived from post-consumer recycled PET bottles, including mineral water bottles, beverage bottles, oil bottles, cosmetic bottles or pharmaceutical bottles. The PCR-PET composition according to claim 1, characterized in that the toughening agent is selected from any one or more of E-MA-GMA or E-BA-GMA. The PCR-PET composition according to claim 3, characterized in that the GMA grafting content in the toughening agent is 5-10%, preferably 7-9%. 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. The PCR-PET composition according to claim 1, characterized in that the antioxidant is selected from at least one of a hindered phenol antioxidant, a phosphite antioxidant or a thioether antioxidant. The method for preparing the PCR-PET composition according to any one of claims 1 to 8 is characterized in that it comprises the following steps: adding each component into a mixer according to a ratio and mixing them evenly to obtain a premix, and melt-extruding the premix at 190-270° C. through a twin-screw extruder, cooling, and granulating to prepare the PCR-PET composition. Use of the PCR-PET composition according to any one of claims 1 to 8 in the field of household appliances.