High-performance PET micro-foaming material and preparation method thereof

Abstract

The invention relates to the technical field of foaming materials, in particular to a high-performance PET micro-foaming material and a preparation method thereof.The high-performance PET micro-foaming material comprises a base material, epoxy resin, a tackifier, a nucleating agent, graphene, a flame-retardant adsorbent, a lubricating filler, a foaming agent, a chain extender and an antioxidant. The high-performance PET micro-foaming material keeps light weight, has excellent strength and toughness and can meet the requirements of various application occasions for material performance, the flame-retardant adsorbent added in the material remarkably improves the flame-retardant performance of the material, the material can meet the fire safety requirement, and by means of the supercritical carbon dioxide foaming technology, the high-performance PET micro-foaming material can be used for preparing the high-performance PET micro-foaming material. According to the present invention, the uniform distribution and the accurate control of the bubbles are achieved, such that the material has characteristics of uniform density and good appearance, and the adopted foaming agent is supercritical carbon dioxide, is the environment-friendly physical foaming agent, and does not cause environmental pollution.

Description

Technical Field

[0001] The present invention relates to the technical field of foaming materials, and specifically to a high-performance PET micro-foaming material and a preparation method thereof. Background Art

[0002] Foaming materials are lightweight materials containing a large number of tiny bubbles inside. These bubbles are introduced into the material through physical or chemical methods, enabling the material to significantly reduce weight while maintaining a certain strength. Due to their unique structure and properties, foaming materials are widely used in multiple fields such as packaging, construction, automotive, aerospace, and sporting goods. For example, in the packaging field, foaming materials are used to make cushioning materials to protect products from impacts and vibrations during transportation; in the construction field, foaming materials are used for heat insulation, sound insulation, and shock absorption.

[0003] Generally, the preparation methods of traditional foaming materials mainly include physical foaming and chemical foaming. Physical foaming is achieved by adding physical foaming agents such as air, nitrogen, and carbon dioxide into the material, and then expanding the foaming agent under certain conditions to form bubbles; chemical foaming is accomplished by adding chemical foaming agents such as sodium bicarbonate and azodicarbonamide into the material. These foaming agents decompose to produce gases when heated, forming bubbles. Commonly used raw materials for traditional foaming materials include polystyrene (PS), polyurethane (PU), polyethylene (PE), etc. Although these materials have certain foaming properties, they have deficiencies in some aspects, such as insufficient strength, poor flame retardancy, and uneven density. At the same time, while traditional foaming materials maintain light weight, they often sacrifice strength and are difficult to meet the strength requirements of certain application scenarios. Many traditional foaming materials are flammable and difficult to meet fire safety requirements. Due to the difficulty in precisely controlling the distribution and size of bubbles during the foaming process, the material density is uneven, affecting performance. Moreover, the preparation methods of traditional foaming materials often involve multiple-step reactions and complex process parameter control, increasing the production difficulty and cost. Some chemical foaming agents produce harmful gases during decomposition, causing environmental pollution.

[0004] Based on this, the present invention provides a high-performance PET micro-foaming material and a preparation method thereof to solve the above-mentioned technical problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-performance PET micro-foaming material and a preparation method thereof. The prepared high-strength metal connector material not only has good mechanical properties but also has excellent corrosion resistance, effectively ensuring its quality and quality.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] The present invention provides a high-performance PET microcellular foaming material, which comprises a substrate, an epoxy resin, a tackifier, a nucleating agent, graphene, a flame retardant adsorbent, a lubricating filler, a foaming agent, a chain extender and an antioxidant, and is composed of the following raw materials in parts by weight:

[0008] Substrate: 70 parts - 80 parts;

[0009] Epoxy resin: 5 parts - 10 parts;

[0010] Tackifier: 2 parts - 5 parts;

[0011] Nucleating agent: 1 part - 3 parts;

[0012] Graphene: 0.5 parts - 2 parts;

[0013] Flame retardant adsorbent: 1 part - 3 parts;

[0014] Lubricating filler: Talc powder: 5 parts - 10 parts;

[0015] Foaming agent: 2 parts - 4 parts;

[0016] Chain extender: 0.5 parts - 1.5 parts;

[0017] Antioxidant: 0.1 parts - 0.5 parts.

[0018] Preferably, the substrate is specifically PET resin, and the PET resin is obtained by subjecting terephthalic acid (TPA) with a purity of more than 99.5% and ethylene glycol (EG) to an esterification reaction in an esterification reactor under the action of an acetate catalyst to obtain diethylene glycol terephthalate. The reaction temperature is 190 - 230°C, and the pressure is 0.1 - 0.5 MPa. After generating diethylene glycol terephthalate (BHET), it is further polycondensed in a polycondensation reactor to generate PET resin.

[0019] Preferably, the tackifier is specifically glycidyl methacrylate (GMA), and the glycidyl methacrylate is obtained by subjecting methyl methacrylate with a purity of more than 99% and glycidyl to an esterification reaction.

[0020] Preferably, the nucleating agent is specifically nano-lanthanum oxide, and the nano-lanthanum oxide is extracted and purified from rare earth ores or compounds through extraction, precipitation, and calcination processes, with a purity of ≥99%.

[0021] Preferably, the flame retardant adsorbent is specifically nano-bamboo charcoal powder, and the bamboo charcoal powder is obtained by subjecting bamboo charcoal to carbonization treatment at a carbonization temperature of 1200 - 1600°C for 24 - 48 hours.

[0022] Preferably, the foaming agent is specifically supercritical carbon dioxide (scCO2), and the supercritical carbon dioxide is obtained by introducing carbon dioxide into an autoclave, pressurizing it to above 7.38 MPa, and heating it to 31.1 °C to make it enter the supercritical state.

[0023] Preferably, the chain extender is specifically pyromellitic dianhydride (PMDA). The pyromellitic dianhydride is obtained by synthesizing pyromellitic dianhydride from pseudocumene and propylene through an alkylation reaction and then through distillation and crystallization processes. The purity of the purified pyromellitic dianhydride is ≥99%.

[0024] Preferably, the antioxidant is specifically antioxidant 1010. The antioxidant 1010 is obtained by multi-step condensation and reaction synthesis, and after the reaction, it is purified through distillation and crystallization processes. The purity of the antioxidant 1010 is ≥99%.

[0025] Based on the above materials, the present invention also proposes a preparation method for a high-performance PET microcellular foaming material, including the following steps:

[0026] S1. Prepare raw materials of a substrate, epoxy resin, tackifier, nucleating agent, graphene, flame retardant adsorbent, lubricating filler, chain extender, and antioxidant;

[0027] S2. Weigh the raw materials according to the weight ratio in an environment with a temperature of 20 - 25 °C and a humidity below 40% RH: 70 - 80 parts of the substrate; 5 - 10 parts of the epoxy resin; 2 - 5 parts of the tackifier; 1 - 3 parts of the nucleating agent; 0.5 - 2 parts of graphene; 1 - 3 parts of the flame retardant adsorbent; 5 - 10 parts of the lubricating filler; 0.5 - 1.5 parts of the chain extender; 0.1 - 0.5 parts of the antioxidant;

[0028] S3. Set the stirring speed of the high-speed mixer to 800 - 1200 revolutions per minute, and the mixing capacity should meet the requirement of one-time input of all raw materials. Put all raw materials except the foaming agent into the high-speed mixer, and the mixing time is 10 minutes until the raw materials are evenly mixed;

[0029] S4. Put the evenly mixed raw materials into a twin-screw extruder with a length-diameter ratio of 20 - 40, heat and melt them, and extrude them into a foaming mold;

[0030] S5. At the gas injection port of the mold, use a high-pressure pump with a pressure range covering above 7.38 MPa to pressurize the supercritical carbon dioxide to 7.38 - 15 MPa, and heat it to 31.1 - 40 °C, and then inject it into the melt in the mold, control the temperature and pressure in the mold, and maintain for 10 - 30 seconds;

[0031] S6. The melt forms a microcellular foaming structure under the action of supercritical carbon dioxide. After foaming is completed, cool and shape the microcellular foaming material in the mold, and the cooling time is 2 minutes;

[0032] S7. According to the specific product requirements, the micro-foamed material is cut, punched, and thermoformed for subsequent processing, and performance tests are carried out.

[0033] Preferably, the performance tests in step S7 are density, tensile strength, impact toughness, and flame retardancy performance tests.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] The high-performance PET micro-foamed material of the present invention has excellent strength and toughness while maintaining light weight, can meet the requirements of material performance in various application scenarios. The flame retardant adsorbent added to the material significantly improves the flame retardancy performance of the material, enabling it to meet the fire safety requirements. Through the supercritical carbon dioxide foaming technology, the uniform distribution and precise control of bubbles are achieved, making the material have a uniform density and good appearance. The foaming agent used in the present invention is supercritical carbon dioxide, which is an environmentally friendly physical foaming agent and will not cause pollution to the environment. At the same time, the twin-screw extruder foaming technology adopted in the present invention has a simple process and is easy to realize industrial production. By precisely controlling the process parameters, the precise regulation of material performance is achieved. Compared with the traditional foamed material preparation method, the supercritical carbon dioxide foaming technology adopted in the present invention has higher energy utilization efficiency and lower energy consumption. By adjusting the formula and process parameters, high-performance PET micro-foamed materials with different performances and application fields are prepared. Detailed Embodiments

[0036] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described 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 of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0037] The present invention provides a high-performance PET micro-foamed material, which includes a substrate, epoxy resin, tackifier, nucleating agent, graphene, flame retardant adsorbent, lubricating filler, foaming agent, chain extender, and antioxidant, and is composed of the following raw materials in parts by weight:

[0038] Substrate: 70 parts - 80 parts; Epoxy resin: 5 parts - 10 parts; Tackifier: 2 parts - 5 parts; Nucleating agent: 1 part - 3 parts; Graphene: 0.5 parts - 2 parts; Flame retardant adsorbent: 1 part - 3 parts; Lubricating filler: Talc powder: 5 parts - 10 parts; Foaming agent: 2 parts - 4 parts; Chain extender: 0.5 parts - 1.5 parts; Antioxidant: 0.1 parts - 0.5 parts.

[0039] It should be noted that the materials in the present invention are commercially available without special instructions;

[0040] In this embodiment, it should also be noted that the substrate is specifically PET resin. PET resin is prepared by subjecting terephthalic acid (TPA) with a purity of more than 99.5% and ethylene glycol (EG) to an esterification reaction in an esterification reactor under the action of an acetate catalyst to obtain diethylene glycol terephthalate. The reaction temperature is 190 - 230°C, and the pressure is 0.1 - 0.5 MPa. After generating diethylene glycol terephthalate (BHET), it is further polycondensed in a polycondensation reactor to produce PET resin.

[0041] In this embodiment, it should also be noted that the tackifier is specifically glycidyl methacrylate (GMA). Glycidyl methacrylate is prepared by subjecting methyl methacrylate with a purity of more than 99% and glycidol to an esterification reaction.

[0042] In this embodiment, it should also be noted that the nucleating agent is specifically nano lanthanum oxide. Nano lanthanum oxide is extracted and purified from rare earth ores or compounds through extraction, precipitation, and calcination processes, with a purity of ≥99%.

[0043] In this embodiment, it should also be noted that the flame retardant adsorbent is specifically nano bamboo charcoal powder. Bamboo charcoal powder is prepared by carbonizing bamboo charcoal at a carbonization temperature of 1200 - 1600°C for 24 - 48 hours.

[0044] In this embodiment, it should also be noted that the foaming agent is specifically supercritical carbon dioxide (scCO2). Supercritical carbon dioxide is prepared by introducing carbon dioxide into an autoclave, pressurizing it to above 7.38 MPa, and heating it to 31.1°C to make it enter the supercritical state.

[0045] In this embodiment, it should also be noted that the chain extender is specifically pyromellitic dianhydride (PMDA). Pyromellitic dianhydride is synthesized by alkylating pseudocumene and propylene to form pyromellitic dianhydride, and then obtained through distillation and crystallization processes. The purity of the purified pyromellitic dianhydride is ≥99%.

[0046] In this embodiment, it should also be noted that the antioxidant is specifically antioxidant 1010. Antioxidant 1010 is synthesized through multiple-step condensation and reactions, and purified through distillation and crystallization processes after the reaction. The purity of antioxidant 1010 is ≥99%.

[0047] Based on the above material components, the present invention also proposes a preparation method for a high-performance PET microcellular foam material, including the following steps:

[0048] S1. Prepare raw materials of a substrate, epoxy resin, tackifier, nucleating agent, graphene, flame retardant adsorbent, lubricating filler, chain extender, and antioxidant;

[0049] S2. Weigh the raw materials according to the weight ratio in an environment with a temperature of 20 - 25 °C and a humidity below 40% RH: 70 - 80 parts of the base material; 5 - 10 parts of epoxy resin; 2 - 5 parts of tackifier; 1 - 3 parts of nucleating agent; 0.5 - 2 parts of graphene; 1 - 3 parts of flame retardant adsorbent; 5 - 10 parts of lubricating filler; 0.5 - 1.5 parts of chain extender; 0.1 - 0.5 parts of antioxidant;

[0050] S3. Set the stirring speed of the high - speed mixer to 800 - 1200 rpm. The mixing capacity should meet the requirement of one - time input of all raw materials. Put all the raw materials except the foaming agent into the high - speed mixer, and the mixing time is 10 min until the raw materials are evenly mixed;

[0051] S4. Put the evenly - mixed raw materials into a twin - screw extruder with a length - to - diameter ratio of 20 - 40, heat and melt them, and extrude them into a foaming mold;

[0052] S5. At the gas injection port of the mold, use a high - pressure pump with a pressure range covering more than 7.38 MPa to pressurize supercritical carbon dioxide to 7.38 - 15 MPa, and heat it to 31.1 - 40 °C, then inject it into the melt in the mold, control the temperature and pressure in the mold, and maintain for 10 - 30 seconds;

[0053] S6. The melt forms a micro - foamed structure under the action of supercritical carbon dioxide. After foaming is completed, cool and shape the micro - foamed material in the mold, and the cooling time is 2 min.

[0054] Example 1

[0055] In this example, the raw material ratio: base material: 75 parts; epoxy resin: 7.5 parts; tackifier: 3.5 parts; nucleating agent: 2 parts; graphene: 1 part; flame retardant adsorbent: 2 parts; lubricating filler: 7.5 parts; chain extender: 1 part; antioxidant: 0.3 part;

[0056] In this example, prepare the high - performance PET micro - foamed material according to the following preparation method:

[0057] Raw material preparation: Ensure that all raw materials have been prepared according to a specific process;

[0058] Raw material mixing: In an environment with a temperature of 22 °C and a humidity of 30% RH, weigh the above - mentioned raw materials according to the weight ratio, put them into a high - speed mixer, set the stirring speed to 1000 rpm, and the mixing time is 10 min until the raw materials are evenly mixed;

[0059] Melting and extrusion: Put the evenly - mixed raw materials into a twin - screw extruder with a length - to - diameter ratio of 30, set the temperature of the heating zone to 260 °C, melt and extrude them into a foaming mold;

[0060] Foaming: At the gas injection port of the mold, supercritical carbon dioxide is pressurized to 10 MPa by a high-pressure pump with a pressure of 10 MPa and heated to 35 °C, and then injected into the melt in the mold. The mold temperature is controlled at 240 °C and the holding time is 20 seconds;

[0061] Cooling and shaping: After foaming is completed, the micro-foamed material in the mold is cooled and shaped for 2 min, and then taken out;

[0062] Example 2

[0063] In this example, the raw material ratio:

[0064] Base material: 70 parts; Epoxy resin: 10 parts; Tackifier: 2 parts; Nucleating agent: 3 parts; Graphene: 1.5 parts; Flame retardant adsorbent: 1 part; Lubricating filler: 5 parts; Chain extender: 1.5 parts; Antioxidant: 0.5 part;

[0065] In this example, the high-performance PET micro-foamed material is prepared according to the following preparation method:

[0066] Raw material preparation: Ensure that all raw materials have been prepared according to a specific process;

[0067] Raw material mixing: In an environment with a temperature of 20 °C and a humidity of 35% RH, the above raw materials are weighed according to the weight ratio, put into a high-speed mixer, and the stirring speed is set at 800 rpm and the mixing time is 10 min until the raw materials are evenly mixed;

[0068] Melting and extrusion: The evenly mixed raw materials are put into a twin-screw extruder with a length-diameter ratio of 25, and the temperature of the heating zone is set at 250 °C, melted and extruded into a foaming mold;

[0069] Foaming: At the gas injection port of the mold, supercritical carbon dioxide is pressurized to 12 MPa by a high-pressure pump with a pressure of 12 MPa and heated to 38 °C, and then injected into the melt in the mold. The mold temperature is controlled at 230 °C and the holding time is 25 seconds;

[0070] Cooling and shaping: After foaming is completed, the micro-foamed material in the mold is cooled and shaped for 2 min, and then taken out;

[0071] Example 3

[0072] In this example, the raw material ratio:

[0073] Base material: 80 parts; Epoxy resin: 5 parts; Tackifier: 5 parts; Nucleating agent: 1 part; Graphene: 2 parts; Flame retardant adsorbent: 3 parts; Lubricating filler: 10 parts; Chain extender: 0.5 part; Antioxidant: 0.1 part;

[0074] In this example, the high-performance PET micro-foamed material is prepared according to the following preparation method:

[0075] Raw material preparation: Ensure that all raw materials have been prepared according to a specific process;

[0076] Raw material mixing: In an environment with a temperature of 25°C and a humidity of 40% RH, after weighing the above raw materials according to the weight ratio, put them into a high-speed mixer, set the stirring speed to 1200 rpm, and the mixing time to 10 min until the raw materials are evenly mixed;

[0077] Melting and extrusion: Put the evenly mixed raw materials into a twin-screw extruder with a length-diameter ratio of 40, set the temperature of the heating zone to 270°C, melt and extrude them into a foaming mold;

[0078] Foaming: At the gas injection port of the mold, pressurize supercritical carbon dioxide to 8 MPa through a high-pressure pump with a pressure of 8 MPa, heat it up to 31.1°C, and then inject it into the melt in the mold, control the mold temperature to 250°C, and keep the time for 10 seconds;

[0079] Cooling and shaping: After foaming, cool and shape the micro-foamed material in the mold for 2 min, and then take it out;

[0080] Example 4

[0081] In this example, the raw material ratio:

[0082] Base material: 78 parts; Epoxy resin: 6 parts; Tackifier: 4 parts; Nucleating agent: 1.5 parts; Graphene: 0.5 parts; Flame retardant adsorbent: 2.5 parts; Lubricating filler: 6 parts; Chain extender: 1.2 parts; Antioxidant: 0.2 parts;

[0083] In this example, a high-performance PET micro-foamed material is prepared according to the following preparation method:

[0084] Raw material preparation: Ensure that all raw materials have been prepared according to a specific process;

[0085] Raw material mixing: In an environment with a temperature of 23°C and a humidity of 38% RH, after weighing the above raw materials according to the weight ratio, put them into a high-speed mixer, set the stirring speed to 1100 rpm, and the mixing time to 10 min until the raw materials are evenly mixed;

[0086] Melting and extrusion: Put the evenly mixed raw materials into a twin-screw extruder with a length-diameter ratio of 32, set the temperature of the heating zone to 265°C, melt and extrude them into a foaming mold;

[0087] Foaming: At the gas injection port of the mold, pressurize supercritical carbon dioxide to 9 MPa through a high-pressure pump with a pressure of 9 MPa, heat it up to 33°C, and then inject it into the melt in the mold, control the mold temperature to 235°C, and keep the time for 15 seconds;

[0088] Cooling and shaping: After foaming is completed, the micro-foamed material in the mold is cooled and shaped for 2 minutes, and then taken out;

[0089] Example 5

[0090] In this example, the raw material ratio is as follows:

[0091] Base material: 72 parts; Epoxy resin: 8 parts; Tackifier: 3 parts; Nucleating agent: 2.5 parts; Graphene: 1.2 parts; Flame retardant adsorbent: 1.5 parts; Lubricating filler: 8 parts; Chain extender: 0.8 parts; Antioxidant: 0.4 parts;

[0092] In this example, the high-performance PET micro-foamed material is prepared according to the following preparation method:

[0093] Raw material preparation: Ensure that all raw materials have been prepared according to a specific process;

[0094] Raw material mixing: In an environment with a temperature of 21°C and a humidity of 32% RH, after weighing the above raw materials according to the weight ratio, put them into a high-speed mixer, set the stirring speed to 900 revolutions per minute, and the mixing time to 10 minutes until the raw materials are evenly mixed;

[0095] Melting and extrusion: Put the evenly mixed raw materials into a twin-screw extruder with a length-diameter ratio of 28, set the temperature of the heating zone to 255°C, melt and extrude them into a foaming mold;

[0096] Foaming: At the gas injection port of the mold, pressurize supercritical carbon dioxide to 11 MPa through a high-pressure pump with a pressure of 11 MPa, heat it up to 37°C, and then inject it into the melt in the mold. Control the mold temperature at 245°C and keep it for 22 seconds;

[0097] Cooling and shaping: After foaming is completed, the micro-foamed material in the mold is cooled and shaped for 2 minutes, and then taken out;

[0098] Comparative Example 1

[0099] This comparative example is compared with Example 1. The raw material ratio is the same as that of Example 1, and the high-performance PET micro-foamed material is prepared according to the following preparation steps:

[0100] Raw material preparation: The same as in Example 1;

[0101] Raw material mixing: In an environment with a temperature of 22°C and a humidity of 30% RH, after weighing the raw materials according to the weight ratio, put them into a high-speed mixer, set the stirring speed to 500 revolutions per minute (lower than 1000 revolutions per minute in Example 1), and the mixing time to 10 minutes;

[0102] Melt extrusion: The uniformly mixed raw materials are fed into a twin-screw extruder with a length-diameter ratio of 30. The temperature of the heating zone is set at 240 °C (lower than 260 °C in Example 1), melted and extruded into a foaming mold;

[0103] Foaming: At the gas injection port of the mold, supercritical carbon dioxide is pressurized to 10 MPa by a high-pressure pump with a pressure of 10 MPa and heated to 30 °C (lower than 35 °C in Example 1), and then injected into the melt in the mold. The mold temperature is controlled at 220 °C (lower than 240 °C in Example 1), and the holding time is 15 seconds (shorter than 20 seconds in Example 1);

[0104] Cooling and shaping: After foaming is completed, the micro-foamed material in the mold is cooled and shaped for 1 min (shorter than 2 min in Example 1), and then taken out;

[0105] Comparative Example 2

[0106] This comparative example prepares a high-performance PET micro-foamed material according to the following raw material ratio:

[0107] Base material (PET resin): 75 parts; Epoxy resin: 15 parts; Adhesive (GMA): 1 part; Nucleating agent (nanometer lanthanum oxide): 2 parts; Graphene: 0 part; Flame retardant adsorbent (bamboo charcoal powder): 4 parts; Lubricating filler (talc powder): 5 parts; Chain extender (PMDA): 1 part; Antioxidant (1010 antioxidant): 0.3 part;

[0108] Preparation of raw materials for high-performance PET micro-foamed material: Ensure that all raw materials have been prepared according to a specific process;

[0109] Mixing of raw materials: In an environment with a temperature of 22 °C and a humidity of 30% RH, the above raw materials are weighed according to the weight ratio, put into a high-speed mixer, and the stirring speed is set at 1000 rpm and the mixing time is 10 min until the raw materials are uniformly mixed;

[0110] Melt extrusion: The uniformly mixed raw materials are fed into a twin-screw extruder with a length-diameter ratio of 30. The temperature of the heating zone is set at 260 °C, melted and extruded into a foaming mold;

[0111] Foaming: At the gas injection port of the mold, supercritical carbon dioxide is pressurized to 10 MPa by a high-pressure pump with a pressure of 10 MPa and heated to 35 °C, and then injected into the melt in the mold. The mold temperature is controlled at 240 °C, and the holding time is 20 seconds;

[0112] Cooling and shaping: After foaming is completed, the micro-foamed material in the mold is cooled and shaped for 2 min, and then taken out;

[0113] Comparative Example 3

[0114] This comparative example is compared with Example 1. The foaming agent components are different, and the other raw material ratios are the same as those in Example 1;

[0115] Prepare the raw materials for the high-performance PET microcellular foam material according to the following preparation method;

[0116] Mixing of raw materials: In an environment with a temperature of 22 °C and a humidity of 30% RH, after weighing the raw materials according to the weight ratio, put them into a high-speed mixer, set the stirring speed to 1000 rpm, and the mixing time to 10 min until the raw materials are evenly mixed;

[0117] Melting and extrusion: Put the evenly mixed raw materials into a twin-screw extruder with a length-diameter ratio of 30, set the temperature of the heating zone to 260 °C, melt and extrude them into a foaming mold;

[0118] Foaming: At the gas injection port of the mold, use a high-pressure pump with a pressure of 10 MPa to pressurize nitrogen (instead of supercritical carbon dioxide) to 10 MPa, heat it up to 35 °C, and then inject it into the melt in the mold. Control the mold temperature at 240 °C and keep it for 20 seconds;

[0119] Cooling and shaping: After foaming is completed, cool and shape the microcellular foam material in the mold for 2 min, and then take it out;

[0120] Comparative Example 4

[0121] This comparative example is compared with Example 1. The mold temperature is different, and the raw material ratio is the same as that in Example 1;

[0122] Prepare the raw materials for the high-performance PET microcellular foam material according to the following preparation method: The same as Example 1;

[0123] Mixing of raw materials: In an environment with a temperature of 22 °C and a humidity of 30% RH, after weighing the raw materials according to the weight ratio, put them into a high-speed mixer, set the stirring speed to 1000 rpm, and the mixing time to 10 min until the raw materials are evenly mixed;

[0124] Melting and extrusion: Put the evenly mixed raw materials into a twin-screw extruder with a length-diameter ratio of 30, set the temperature of the heating zone to 260 °C, melt and extrude them into a foaming mold;

[0125] Foaming: At the gas injection port of the mold, use a high-pressure pump with a pressure of 10 MPa to pressurize supercritical carbon dioxide to 10 MPa, heat it up to 35 °C, and then inject it into the melt in the mold. Control the mold temperature at 220 °C (lower than 240 °C in Example 1), and keep it for 20 seconds;

[0126] Cooling and shaping: After foaming is completed, cool and shape the microcellular foam material in the mold for 2 min, and then take it out;

[0127] Comparative Example 5

[0128] This comparative example is compared with Example 1, without a nucleating agent;

[0129] The raw material ratio is as follows: base material (PET resin): 75 parts; epoxy resin: 7.5 parts; tackifier (GMA): 3.5 parts; nucleating agent: 0 parts (not added, 2 parts of nano-lanthanum oxide in Example 1); graphene: 1 part; flame retardant adsorbent (bamboo charcoal powder): 2 parts; lubricating filler (talc powder): 7.5 parts; chain extender (PMDA): 1 part; antioxidant (antioxidant 1010): 0.3 parts;

[0130] Preparation of high-performance PET microcellular foaming material raw materials: Ensure that all raw materials have been prepared according to a specific process;

[0131] Raw material mixing: In an environment with a temperature of 22°C and a humidity of 30% RH, weigh the above raw materials according to the weight ratio, put them into a high-speed mixer, set the stirring speed to 1000 rpm, and the mixing time to 10 min until the raw materials are evenly mixed;

[0132] Melting and extrusion: Put the evenly mixed raw materials into a twin-screw extruder with a length-diameter ratio of 30, set the temperature of the heating zone to 260°C, melt and extrude them into a foaming die;

[0133] Foaming: At the gas injection port of the die, pressurize supercritical carbon dioxide to 10 MPa through a high-pressure pump with a pressure of 10 MPa, heat it up to 35°C, and then inject it into the melt in the die, control the die temperature to 240°C, and keep the time for 20 seconds;

[0134] Cooling and shaping: After foaming, cool and shape the microcellular foaming material in the die for 2 min, and then take it out.

[0135] Performance testing:

[0136] Samples of high-performance PET microcellular foaming materials were prepared from the formulations of Example 1 and Examples 2 to 5, and the parameters are shown in Table 1:

[0137] Table 1 Sample parameter table of Example 1 and Examples 2 to 5

[0138]

[0139]

[0140] Samples of high-performance PET microcellular foaming materials were prepared from the equipment parameters of Example 1 and Comparative Examples 1 to 5, and the parameters are shown in Table 2:

[0141] Table 2 Sample parameter table of Example 1 and Comparative Examples 1 to 5

[0142]

[0143]

[0144] Design density, tensile strength, impact toughness, and flame retardancy performance tests were carried out on the samples prepared in Examples 1 to 5 and Comparative Examples 1 to 5:

[0145] a. Density test: Measure the density of the material to evaluate its mass distribution and volume characteristics:

[0146] Using the drainage method or the mass - volume method, place the sample in a container with a known volume, measure the volume of water displaced or directly measure its mass with a balance, and then calculate the density;

[0147] b. Tensile strength test: Measure the maximum load - bearing capacity of the material under tensile load:

[0148] Use a universal material testing machine, fix the sample on the fixture, apply a tensile load at a constant speed until the sample breaks, record the maximum load at break, and calculate the tensile strength based on the cross - sectional area of the sample;

[0149] c. Impact toughness test: Measure the ability of the material to resist fracture under impact load:

[0150] Use a pendulum impact testing machine or a drop - weight impact testing machine, fix the sample on the test bench, release the pendulum or drop - weight at a certain speed to impact the sample, record the energy absorption during the impact process, and evaluate the impact toughness of the material;

[0151] d. Flame retardancy test: Evaluate the ability of the material to slow down or prevent the spread of flame when in contact with a fire source:

[0152] Adopt the vertical burning test method, fix the sample vertically, ignite the flame at the bottom, observe the burning speed, flame propagation, and smoke generation of the sample, and evaluate the flame retardancy performance grade according to the UL 94 standard;

[0153] After the above experiments, collect the data of Examples 1 to 5 and Comparative Examples 1 to 5 and conduct a comparative analysis, as shown in Table 3:

[0154] Table 3 Sample data of Examples 1 to 5 and Comparative Examples 1 to 5

[0155]

[0156]

[0157] Analyze the experimental data:

[0158] (1) Density analysis:

[0159] The density range of Examples 1-5 is between 1.0-1.4 g / cm 3 , which is relatively uniform and is beneficial to the processing and shaping of the material;

[0160] The densities of Comparative Examples 1-5 are more dispersed. Among them, the densities of Comparative Example 1 and Comparative Example 4 are relatively low, which may affect the physical properties of the material; the densities of Comparative Examples 2, 3 and 5 are relatively high, which may increase the processing difficulty and cost;

[0161] (2) Tensile strength analysis:

[0162] The tensile strengths of Examples 1-5 are all above 450 MPa, showing strong load-bearing capacity. Among them, the tensile strength of Example 5 is the highest, reaching 520 MPa;

[0163] The tensile strengths of Comparative Examples 1-5 are relatively low, all lower than 450 MPa, and may not meet the strength requirements of some application scenarios;

[0164] (3) Impact toughness analysis:

[0165] The impact toughness of Examples 1-5 is between 14-22 J / cm 2 , showing good impact resistance. Among them, the impact toughness of Example 1 is the highest, reaching 20 J / cm 2 ;

[0166] The impact toughness of Comparative Examples 1-5 is relatively low, all lower than 14 J / cm 2 , and may be easily damaged by impact;

[0167] (4) Flame retardant performance analysis:

[0168] The flame retardant performance grades of Examples 1 and 5 are V-0, which is the highest grade in the UL 94 standard, indicating that they have excellent flame retardant performance when in contact with a fire source. The flame retardant performance grades of Examples 2 and 4 are V-1, also showing good flame retardant performance. The flame retardant performance grade of Example 3 is V-2, which is relatively poor but still meets certain requirements;

[0169] The flame retardant performance grades of Comparative Examples 1 and 4 are HB, which is the lowest grade in the UL 94 standard, indicating that their flame retardant performance is poor. The flame retardant performances of Comparative Examples 2, 3 and 5 do not reach any grade (NR) in the UL 94 standard, indicating that their flame retardant performances are very poor;

[0170] In summary, considering the performance in terms of density, tensile strength, impact toughness, and flame retardancy, the high-performance PET foaming material prepared in Example 1 performs excellently in all performance indicators. Therefore, Example 1 is the best example. Therefore, a high-performance PET micro-foaming material and its preparation method proposed by the present invention perform excellently in terms of mechanical properties, flame retardancy, density distribution, and environmental protection, and have broad application prospects and market potential.

[0171] In the description of this specification, the description with reference 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.

[0172] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A high-performance PET micro-foam material, characterized in that: The invention comprises a substrate, an epoxy resin, a tackifier, a nucleating agent, graphene, a flame retardant adsorbent, a lubricating filler, a foaming agent, a chain extender and an antioxidant, and is composed of the following raw materials in parts by weight: Base material: 70-80 parts; Epoxy resin: 5-10 parts; Tackifier: 2-5 parts; Nucleating agent: 1-3 parts; Graphene: 0.5-2 parts; Flame retardant adsorbent: 1-3 parts; Lubricating filler: talc: 5-10 parts; Foaming agent: 2-4 parts; Chain extender: 0.5-1.5 parts; Antioxidant: 0.1 part - 0.5 part.

2. A high-performance PET micro-foam material according to claim 1, characterized in that: The substrate is specifically PET resin, which is prepared by esterification reaction of terephthalic acid with a purity of more than 99.5% and ethylene glycol in an esterification reactor under the action of acetate catalyst to obtain diethylene glycol terephthalate, with a reaction temperature of 190-230° C. and a pressure of 0.1-0.5 MPa. After the diethylene glycol terephthalate is generated, it is further polycondensed in a polycondensation reactor to generate PET resin.

3. A high-performance PET micro-foam material according to claim 1, characterized in that: The tackifier is specifically glycidyl methacrylate, which is prepared by esterification reaction of methyl methacrylate with a purity of more than 99% and glycidol.

4. A high-performance PET micro-foam material according to claim 1, characterized in that: The nucleating agent is specifically nano-lanthanum oxide, which is extracted and purified from rare earth ores or compounds through extraction, precipitation and calcination processes, and has a purity of ≥99%.

5. The high-performance PET micro-foam material according to claim 1, characterized in that: The flame retardant adsorbent is specifically nano bamboo charcoal powder, and the bamboo charcoal powder is prepared by carbonizing bamboo charcoal at a carbonization temperature of 1200-1600° C. for 24-48 hours.

6. A high-performance PET micro-foam material according to claim 1, characterized in that: The foaming agent is specifically supercritical carbon dioxide, which is obtained by introducing carbon dioxide into an autoclave, pressurizing it to above 7.38 MPa, and heating it to 31.1° C. to make it enter a supercritical state.

7. The high-performance PET micro-foam material according to claim 1, characterized in that: The chain extender is specifically pyromellitic anhydride, which is prepared by synthesizing pyromellitic anhydride from unsymmetrical trimethylolbenzene and propylene through an alkylation reaction and then distilling and crystallizing the pyromellitic anhydride. The purity of the purified pyromellitic anhydride is ≥99%.

8. The high-performance PET micro-foam material according to claim 1, characterized in that: The antioxidant is specifically 1010 antioxidant, which is synthesized by multi-step condensation and reaction, and purified by distillation and crystallization process after the reaction. The purity of the 1010 antioxidant is ≥99%.

9. A method for preparing a high-performance PET micro-foam material, according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Prepare substrate, epoxy resin, tackifier, nucleating agent, graphene, flame retardant adsorbent, lubricating filler, chain extender and antioxidant raw materials; S2. Under the environment of temperature 20-25°C and humidity below 40%RH, weigh the raw materials by weight: 70-80 parts of substrate; 5-10 parts of epoxy resin; 2-5 parts of tackifier; 1-3 parts of nucleating agent; 0.5-2 parts of graphene; 1-3 parts of flame retardant adsorbent; 5-10 parts of lubricating filler; 0.5-1.5 parts of chain extender; 0.1-0.5 parts of antioxidant; S3. The stirring speed of the high-speed mixer is set to 800-1200 rpm. The mixing capacity needs to meet the needs of all raw materials at one time. All raw materials except the foaming agent are put into the high-speed mixer for 10 min until the raw materials are evenly mixed. S4. The mixed raw materials are put into a twin-screw extruder having an aspect ratio of 20-40, heated to melt and extruded into a foaming mold; S5. At the injection port of the mold, supercritical carbon dioxide is pressurized to 7.38-15MPa through a high-pressure pump with a pressure range of more than 7.38MPa, and the temperature is raised to 31.1-40°C, and then injected into the melt in the mold, and the temperature and pressure in the mold are controlled and maintained for 10-30 seconds; S6. The melt forms a micro-foam structure under the action of supercritical carbon dioxide. After the foaming is completed, the micro-foam material in the mold is cooled and shaped. The cooling time is 2 minutes; S7. According to the specific product requirements, the micro-foam material is cut, punched, thermoformed and then subjected to performance testing.

10. The method for preparing a high-performance PET micro-foam material according to claim 9, characterized in that: The performance tests in step S7 are density, tensile strength, impact toughness and flame retardancy tests.

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