Cutting PETG composite foaming material and preparation method thereof

Abstract

The invention discloses a machinable PETG composite foam material and a preparation method thereof. The preparation method of the PETG composite foam material mainly comprises the following steps: drying 100 parts by weight of PETG resin, 5-20 parts by weight of calcium carbonate, 5-20 parts by weight of a flexibilizer and 0.5-3 parts by weight of a chain extender, and then carrying out melt blending to obtain modified PETG particles; the dried modified PETG particles are added into an injection molding machine, supercritical nitrogen is introduced, and the PETG composite foaming material is obtained through a melt blending and under-injection molding method. According to the method, calcium carbonate, a flexibilizer and a chain extender are used for synergistically modifying PETG, and a supercritical nitrogen injection molding foaming process is combined, so that the technical problems that the PETG melt is low in strength, easy to break and collapse in foaming, poor in toughness and the like are effectively solved, and the PETG composite foaming material prepared by the method has good expandability and machinability, and is suitable for industrial production. The material can be applied to eyebrow pencil shell packaging materials.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials technology, and in particular to a machinable PETG composite foam material and its preparation method. Background Technology

[0002] With the rapid development of the cosmetics industry, packaging materials that come into direct contact with active ingredients are subject to strict regulation, and the market has reached billions of dollars in recent years. For consumer safety, the government and relevant departments have standardized the safety of packaging materials. Regulations such as the "Cosmetics Supervision and Management Regulations" and the "Cosmetics Safety Technical Specifications (2015 Edition)" stipulate that packaging materials must not chemically react with cosmetics or release substances harmful to the human body, ensuring compatibility between packaging materials and cosmetics. Packaging materials must not only protect the product and attract consumers, but also avoid introducing hazardous substances, such as leachates, and must not absorb the active ingredients in cosmetics to guarantee product quality and efficacy.

[0003] Currently, the industry primarily uses styrene-based polymers, polypropylene, and polyethylene as direct-contact packaging materials. With the implementation of dual-carbon policies, there is a need to further reduce the use of packaging materials. European regulations are gradually restricting and prohibiting the use of silicone solvents and styrene-based polymers in cosmetics, necessitating the adoption of new materials as alternatives across the industry. While domestic research on lightweight packaging materials includes extrusion, injection molding, and foaming, there is a lack of targeted research on resistance to solvents such as isoparaffins and machinability.

[0004] Polyethylene terephthalate-1,4-cyclohexanediethanol (PETG) is a fully recyclable polymer that is resistant to most oils and alcohols, meets FDA food exposure standards, and can be used in direct contact packaging for cosmetics.

[0005] However, PETG resin has a high elastic modulus and, as an intangible polymer, has poor expandability, which cannot meet the requirement of being cuttable for eyebrow pencil packaging. Summary of the Invention

[0006] The purpose of this patent application is to provide a machinable PETG composite foam material and its preparation method, so as to improve the expandability and machinability of PETG material and obtain a foam material suitable for eyebrow pencil packaging.

[0007] The purpose of this patent application is achieved as follows: A cuttable PETG composite foam material, characterized in that it comprises: 100 parts of PETG resin, 5-20 parts of calcium carbonate, 5-20 parts of toughening agent, and 0.5-3 parts of chain extender.

[0008] Preferably, the calcium carbonate in step S1 is heavy calcium carbonate with a particle size of 0.1~1μm. The calcium carbonate selected in this invention can not only promote the dimensional stability of foamed products, but also improve the hardness and rigidity of the material, making the foamed material easier to plan and cut.

[0009] Preferably, the toughening agent is one or more of thermoplastic polyurethane elastomer (TPU), thermoplastic polyester elastomer (TPEE), acrylate copolymer (ACR), and nylon elastomer (PEBAX).

[0010] Preferably, the chain extender is an epoxy-based chain extender.

[0011] Preferably, the chain extender is one of ADR4468, ADR4368, and ADR4400. The chain extender selected in this invention restores molecular weight and strength through chain extension, and further improves the impact resistance of PETG through synergy with toughening agents.

[0012] Machinable PETG composite foam material can be used in eyebrow pencil shell materials.

[0013] A method for preparing a machinable PETG composite foam material, comprising the aforementioned machinable PETG composite foam material, and the steps thereof are as follows: S1. The dried raw materials: PETG resin, calcium carbonate, toughening agent and chain extender are mixed and then melt-blended and extruded to obtain modified PETG granules; S2. The dried modified PETG granules are added to the injection molding machine, and supercritical nitrogen gas is introduced into the injection molding machine. After melt blending, the PETG composite foam material is obtained by injection molding foaming.

[0014] Preferably, the raw materials and modified PETG particles mentioned in steps S1 and S2 need to be dried before use, with a drying time of 6 to 12 hours and a drying temperature of 75 to 80°C.

[0015] Preferably, the amount of supercritical nitrogen added in step S2 is 0.5-1% of the amount of modified PETG particles added, and the supercritical nitrogen is high-purity nitrogen. The supercritical nitrogen forms a homogeneous single-phase solution in the melt, and after injection molding and pressure relief, it undergoes in-situ micro-foaming, forming a highly closed-cell microporous structure, which improves chemical resistance, lightweighting, and cutting feel.

[0016] Preferably, the melt temperature of the injection molding machine in step S2 is 210~230℃; Preferably, the injection pressure of the injection molding machine in step S2 is 100~180MPa and the injection speed is 120~180mm / s.

[0017] Preferably, the foamed material is prepared by under-injection molding with an under-injection rate of 70% to 80%. The under-injection rate is the percentage of the volume of the injected melt to the volume of the mold cavity. The remaining volume is filled into the cavity by supercritical foaming to obtain the foamed material.

[0018] The outstanding and beneficial technical effects of this patent application compared to the prior art are: This invention effectively improves the melt strength and expandability of PETG by adding chain extenders and toughening agents, and significantly improves the uniformity of cell morphology and size through their synergistic effect. The microporous foam prepared by supercritical nitrogen injection molding has a high closed-cell ratio, which improves the chemical resistance of the foamed material. The addition of calcium carbonate can promote the dimensional stability of the foamed product and the hardness and rigidity of the material, making the foamed material easier to plan and cut. The modified PETG foamed by supercritical fluid foaming produces a PETG composite foam material with excellent properties such as high closed-cell ratio, good planability and chemical resistance, which can be used in eyebrow pencil shell products.

[0019] This invention synergistically modifies PETG using calcium carbonate, toughening agents, and epoxy chain extenders: the chain extender improves melt strength and stabilizes foaming; the toughening agent improves toughness and prevents chipping during cutting; calcium carbonate acts as a nucleating agent to refine the pores and simultaneously increase rigidity, achieving easy machining; ultimately, a PETG foam material with high closed-cell ratio, lightweight, chemical resistance, and machinability is obtained. The weight reduction percentage of the PETG composite foam material is 20-30%, and the cutting torque is 10-15 N·cm; the PETG composite foam material has a closed-cell structure with a closed-cell ratio of 95-99%. Attached Figure Description

[0020] Figure 1 Electron micrograph of the PETG foam sample provided in Example 1.

[0021] Figure 2 Electron micrograph of the PETG foam sample provided for Comparative Example 1. Detailed Implementation

[0022] This patent application will now be further described with reference to the accompanying drawings and specific embodiments. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0023] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0024] The weight reduction percentage of the foamed material in this invention is calculated in the following way: Weigh the unfoamed sample using an analytical balance. Weigh the foamed sample. The ratio of the difference between the two to that of the micro-foamed sample is the weight loss percentage of the foamed sample. Δm=

[0025] The method for testing the bubble size in this invention is as follows: The fracture surface of the PETG foam sample after quenching was sputtered with gold, and the internal cell structure of the foam material was observed using a scanning electron microscope.

[0026] The method for testing cutting force in this invention is as follows: One end of the PETG foam sample was tightened with a torque meter, and the other end was placed in a pencil sharpener. The torque meter was then rotated to measure the cutting force of the PETG.

[0027] The method for testing the open area ratio in this invention is as follows: The porosity of the PETG composite foam samples was analyzed using a densitometer with a fully automated gas displacement method. The porosity of the samples was measured by gas displacement and pressure difference change.

[0028] The chemical resistance test method for samples in this invention is as follows: According to the standard "Determination of resistance of plastics to liquid chemical reagents (GB / T 11547-2008)," the sample was immersed in isododecane, and the mass of the sample before and after immersion was weighed.

[0029] Example 1 (1) Preparation of modified PETG particles PETG resin, toughening agent, calcium carbonate, and chain extender were dried in an 80℃ oven for 8 hours. The mixture consisted of 100 parts PETG resin, 20 parts TPEE toughening agent, 15 parts calcium carbonate, and 2 parts chain extender 4468 (Joncryl® ADR-4468, an epoxy reactive chain extender). After thorough mixing, the mixture was added to a twin-screw extruder. The temperatures of each section of the twin screw were 100-180-220-220-220-220-200℃. The shear force of the twin screw ensured thorough mixing of the components and simultaneous chain extension reaction. After cooling, the mixture was pelletized to obtain modified PETG granules.

[0030] (2) Preparation of modified PETG composite foam material The modified PETG granules obtained in the above steps were dried in an 80℃ oven for 8 hours and then added to an injection molding machine. The length of the injection molding machine was divided into 6 sections, and the temperature of each section was set separately. The temperatures of the 6 sections along the extrusion direction were 200℃, 230℃, 230℃, 230℃, 220℃, and 210℃, respectively. The undershoot of the equipment was set to 75%, that is, the volume of the melt was 75% of the volume of the mold cavity, the injection pressure was 150MPa, the injection speed was 160mm / s, and the mold temperature was 100℃.

[0031] After the sample cooled for 180 seconds, the mold was opened to obtain the PETG composite foam material. Its properties are as follows: weight reduction of 25%, average cell size of 20μm, closed cell rate of 97%, chemical resistance / weight gain percentage of 0.13%, and cutting force of 12 N·cm.

[0032] Example 2 This embodiment is the same as Example 1, except that the amount of calcium carbonate added is different. By weight, the amounts are: 100 parts PETG resin, 20 parts toughening agent TPEE, 5 parts calcium carbonate, and 2 parts chain extender 4468. The properties of the resulting PETG composite foam material are as follows: weight reduction of 25%, average cell size of 25 μm, closed cell rate of 98%, chemical resistance / weight gain percentage of 0.12%, and cutting force of 15 N·cm.

[0033] Example 3 This embodiment is the same as Example 1, except that the amount of calcium carbonate added is different. By weight, the amounts are: 100 parts PETG resin, 20 parts toughening agent TPEE, 20 parts calcium carbonate, and 2 parts chain extender 4468. The properties of the resulting PETG composite foam material are as follows: weight reduction of 25%, average cell size of 18 μm, closed cell rate of 96%, chemical resistance / weight gain percentage of 0.15%, and cutting force of 10 N·cm.

[0034] Example 4 This embodiment is the same as Example 1, except that the amount of chain extender added is different. By weight: 100 parts PETG resin, 20 parts toughening agent TPEE, 15 parts calcium carbonate, and 0.3 parts chain extender 4468. The properties of the obtained PETG composite foam material are as follows: weight reduction of 25%, average cell size of 22 μm, closed cell rate of 95%, chemical resistance / weight gain percentage of 0.16%, and cutting force of 11 N·cm.

[0035] Example 5 This embodiment is the same as Example 1, except that the amount of chain extender added is different. By weight, the amounts are: 100 parts PETG resin, 20 parts toughening agent TPEE, 15 parts calcium carbonate, and 3 parts chain extender 4468. The properties of the obtained PETG composite foam material are as follows: weight reduction of 25%, average cell size of 23 μm, closed cell rate of 98%, chemical resistance / weight gain percentage of 0.12%, and cutting force of 15 N·cm.

[0036] Example 6 This embodiment is the same as Example 1, except that the toughening agent added is different. By weight, the components are: 100 parts PETG resin, 5 parts TPEE toughening agent, 15 parts calcium carbonate, and 2 parts chain extender 4468. The properties of the obtained PETG composite foam material are as follows: weight reduction of 25%, average cell size of 28 μm, closed cell rate of 96%, chemical resistance / weight gain percentage of 0.10%, and cutting force of 15 N·cm.

[0037] Example 7 This embodiment is the same as Example 1, except that the amount of calcium carbonate added is different. By weight, the amounts are: 100 parts PETG resin, 20 parts toughening agent TPEE, 12 parts calcium carbonate, and 2 parts chain extender 4468. The properties of the resulting PETG composite foam material are as follows: weight reduction of 25%, average cell size of 20 μm, closed cell rate of 96%, chemical resistance / weight gain percentage of 0.16%, and cutting force of 11 N·cm.

[0038] Comparative Example 1 This comparative example is the same as Example 1, except that no calcium carbonate is added. By weight, the amounts are: 100 parts PETG resin, 20 parts toughening agent TPEE, 0 parts calcium carbonate, and 2 parts chain extender 4468. The properties of the obtained PETG composite foam material are as follows: weight reduction of 25%, average cell size of 130 μm, closed cell rate of 80%, chemical resistance / weight gain percentage of 1.24%, and cutting force of 25 N·cm.

[0039] Comparative Example 2 This comparative example is the same as Example 1, except that no chain extender is added. By weight, the following components are used: 100 parts PETG resin, 20 parts toughening agent TPEE, 15 parts calcium carbonate, and 0 parts chain extender 4468. The properties of the obtained PETG composite foam material are as follows: weight reduction of 25%, average cell size of 85 μm, closed cell rate of 90%, chemical resistance / weight gain percentage of 0.2%, and cutting force of 22 N·cm.

[0040] Comparative Example 3 This comparative example is the same as Example 1, except that no toughening agent is added. By weight, the composition is: 100 parts PETG resin, 0 parts toughening agent, 15 parts calcium carbonate, and 2 parts chain extender 4468. The properties of the obtained PETG composite foam material are as follows: weight reduction of 25%, average cell size of 68 μm, closed cell rate of 96%, chemical resistance / weight gain percentage of 0.12%, and cutting force of 30 N·cm.

[0041] Compared with the control group without calcium carbonate, chain extender, and toughening agent, the scheme in Example 1 is as follows: The pore size decreased from 68-130μm to 18-28μm; the cutting force decreased from 22-30N. cm decreased to 10-15N cm; the closed-cell rate increased from 80-96% to 95-99%; the resistance to isoparaffins was significantly improved, and the weight gain decreased from 1.24% to about 0.1%; this invention modifies PETG through the synergistic action of calcium carbonate, toughening agent, and epoxy chain extender, combined with supercritical nitrogen micro-injection molding foaming, successfully solving the technical problems of low melt strength, difficult foaming, large pores, and difficult cutting of PETG, and preparing a machinable, highly closed-cell, lightweight, and isoparaffin-resistant PETG composite foam material, which is particularly suitable for eyebrow pencil packaging materials, and has outstanding substantive characteristics and significant progress.

[0042] The foregoing has shown and described the basic principles, main features, and advantages of this technical solution. Those skilled in the art should understand that this technical solution is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this technical solution. Various changes and modifications can be made to this technical solution without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed technical solution. The scope of protection of this technical solution is defined by the appended claims and their equivalents.

Claims

1. A machinable PETG composite foam material, characterized in that, include: 100 parts PETG resin, 5-20 parts calcium carbonate, 5-20 parts toughening agent, and 0.5-3 parts chain extender.

2. The machinable PETG composite foam material according to claim 1, characterized in that, The calcium carbonate mentioned in step S1 is heavy calcium carbonate with a particle size of 0.1~1μm.

3. The machinable PETG composite foam material according to claim 1, characterized in that, The toughening agent is one or more of thermoplastic polyurethane elastomer (TPU), thermoplastic polyester elastomer (TPEE), acrylate copolymer (ACR), and nylon elastomer (PEBAX).

4. The machinable PETG composite foam material according to claim 1, characterized in that, The chain extender mentioned is an epoxy-based chain extender.

5. The machinable PETG composite foam material according to claim 4, characterized in that, The chain extender is one of ADR4468, ADR4368, and ADR4400.

6. The machinable PETG composite foam material according to claim 1, characterized in that, Used in eyebrow pencil casing materials.

7. A method for preparing a machinable PETG composite foam material, characterized in that, The steps for including the machinable PETG composite foam material according to any one of claims 1-5 are as follows: S1. The dried raw materials: PETG resin, calcium carbonate, toughening agent and chain extender are mixed and then melt-blended and extruded to obtain modified PETG granules; S2. The dried modified PETG granules are added to the injection molding machine, and supercritical nitrogen gas is introduced into the injection molding machine. After melt blending, the PETG composite foam material is obtained by injection molding foaming.

8. The method for preparing a machinable PETG composite foam material according to claim 7, characterized in that, The raw materials and modified PETG particles mentioned in steps S1 and S2 need to be dried before use. The drying time is 6 to 12 hours and the drying temperature is 75 to 80°C.

9. The method for preparing a machinable PETG composite foam material according to claim 7, characterized in that, The amount of supercritical nitrogen added in step S2 is 0.5-1% of the amount of modified PETG particles added, and the supercritical nitrogen is high-purity nitrogen.

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