CN116496610A - PET modified material and its preparation method and application - Google Patents

Abstract

The application provides a PET modified material, and a preparation method and application thereof. The PET modified material comprises the following components in percentage by mass: 45-90 wt% of polyethylene terephthalate, 0-20 wt% of heat conducting filler, 1.3-6.4 wt% of auxiliary agent and 7-50 wt% of glass fiber; wherein the melt index of the PET modified material is 10g/10 min-20 g/10min. The PET modified material has higher molecular weight, and is beneficial to improving the mechanical property of the PET modified material.

Description

PET modified material and its preparation method and application

technical field

The application relates to the technical field of automobiles, in particular to a PET modified material and its preparation method and application.

Background technique

At present, with the continuous development of science and technology, heat dissipation materials are required in many fields. Due to the limitations of weight and processing performance, materials such as metals and ceramics with excellent thermal conductivity are difficult to meet the needs of modern industries, and relatively light and easy-to-process plastic products have become ideal heat dissipation materials.

Polyethylene glycol terephthalate (PET) can be used as a heat dissipation material due to its excellent mechanical properties, heat resistance, electrical properties and chemical stability, and is widely used in the automotive field, such as new energy vehicles. Box housings, fuse (FUSE) bases, automotive modular light modules or thermally conductive light brackets. However, with the rapid development of technology, higher requirements have been put forward for the heat dissipation performance and mechanical properties of heat dissipation materials. At present, due to the limitation of production process, many properties of PET materials cannot meet the high demands of modern emerging industries.

Contents of the invention

This application is made in view of the above problems, and its purpose is to provide a PET modified material, which has a lower melt index, and its mechanical properties are obviously enhanced, which can meet the needs of modern emerging industries.

The first aspect of the present application provides a PET modified material, and the preparation of the PET modified material includes the following components in mass percentage:

Polyethylene terephthalate 45wt%~90wt%,

Thermally conductive filler 0wt%~20wt%,

Additive 1.3wt%~6.4wt%,

Glass fiber 7wt%~50wt%;

Wherein, the melt index of the PET modified material is 10g/10min~20g/10min.

Using polyethylene terephthalate (PET) as the base material, thermally conductive fillers, additives, glass fibers react with PET to prepare PET modified materials, and control its melt index to 10g/10min~20g/10min, so that PET The modified material has a larger molecular weight, which is conducive to improving the mechanical properties of its PET modified material.

In any embodiment, the PET modified material has a viscosity greater than 0.65 dl/g. In any embodiment, the PET modified material has a viscosity greater than 0.85 dl/g.

Control the viscosity of the PET modified material to be greater than 0.65dl/g, so that the PET modified material has a larger molecular weight, which is beneficial to the improvement of its mechanical properties.

In any embodiment, the polyethylene terephthalate comprises homopolyethylene terephthalate.

Homopolyethylene terephthalate has a regular molecular structure, which is conducive to the improvement of the crystallinity of PET modified materials, and then improves the mechanical properties of PET modified materials.

In any embodiment, the thermally conductive filler includes one of flake graphene, natural graphite, carbon nanotube, carbon fiber, thermally conductive carbon material, boron nitride, aluminum nitride, silicon carbide, aluminum oxide, magnesium oxide, or Various, optionally including graphene flakes.

The addition of thermally conductive fillers is conducive to improving the thermal conductivity of the PET modified material, that is, the heat dissipation of the PET modified material is significantly improved.

In any embodiment, the preparation of the PET modified material includes the following components in mass percentage:

Polyethylene terephthalate 45wt%~90wt%,

Flake graphene 1wt%~20wt%,

Additive 1.3wt%~6.4wt%,

Glass fiber 7wt%~50wt%.

Since flake graphene has a planar carbon six-membered ring conjugated crystal structure, and has a large radial width/thickness ratio and a large contact area, flake graphene can significantly improve the thermal conductivity of PET modified materials , greatly improving the heat dissipation performance of PET modified materials.

In any embodiment, the auxiliary agent includes a toughening agent, a nucleating agent, a lubricant and an antioxidant, and optionally, the auxiliary agent further includes an antimony-containing compound.

The above additives can comprehensively improve the toughness, crystallinity, processability and oxidation resistance of PET modified materials.

In any embodiment, based on the total mass of the PET modified material, the mass fraction of the toughening agent is 1 wt % to 5 wt %.

In any embodiment, the toughening agent includes ethylene-methyl acrylate-glycidyl methacrylate copolymer, polymethyl acrylate, polyethyl acrylate, copolymerized polyethylene terephthalate, olefin copolymer One or more of elastomers and polyether esters.

The above toughening agents can effectively improve the toughness of the PET modified material, and reduce the risk of cracks in the PET modified material under external impact, resulting in a decrease in impact resistance. Controlling the mass fraction of the toughening agent within an appropriate range can not only effectively improve the toughness of the PET modified material, but also avoid the adverse effects of excessive toughening agent degradation on the PET modified material at high temperature.

In any embodiment, based on the total mass of the PET modified material, the mass fraction of the nucleating agent is 0.1 wt% to 0.35 wt%.

In any embodiment, the nucleating agent includes one or more of an organic nucleating agent and an inorganic nucleating agent, and the organic nucleating agent includes sodium montanate, sorbitol salt, benzoate, P250 , Surlyn8920, RS-735, the inorganic nucleating agent includes one or more of talcum powder and barium sulfate.

The above-mentioned nucleating agents can be used as the crystallization site of the PET modified material, so that the PET modified material has a suitable crystallinity, which is beneficial to the improvement of the mechanical properties of the PET modified material. Controlling the mass fraction of the nucleating agent within an appropriate range is conducive to providing enough nucleating sites to make the PET modified material a crystalline substance, improving its mechanical properties, and reducing the introduction of too much nucleating agent The effect on the properties of PET modified materials.

In any embodiment, based on the total mass of the PET modified material, the mass fraction of the lubricant is 0.1wt%-0.5wt%.

In any embodiment, the lubricant includes one or more of silicone powder, silicone masterbatch, polyethylene wax, stearate, and montanate.

All of the above lubricants can improve the processing performance of PET modified materials. Controlling the mass fraction of the lubricant in an appropriate range can not only effectively improve the processing performance of the PET modified material, but also reduce the influence of the introduction of too much lubricant on the performance of the PET modified material.

In any embodiment, based on the total mass of the PET modified material, the mass fraction of the antioxidant is 0.1wt%~0.5wt%.

In any embodiment, the antioxidant includes one or more of hindered phenolic antioxidants and phosphite antioxidants, and the hindered phenolic antioxidants include antioxidant 1010, antioxidant One or more of antioxidant 2246, antioxidant 1076, antioxidant 330, the phosphite antioxidant includes antioxidant 168, antioxidant 626, antioxidant 619, antioxidant 3010, One or more of the antioxidant PEP36.

The above antioxidants can improve the oxidation resistance of PET modified materials. Controlling the mass fraction of antioxidants in an appropriate range can not only effectively improve the oxidation resistance of PET modified materials, but also reduce the impact of the introduction of too much antioxidant on the properties of PET modified materials.

In any embodiment, the glass fibers include one or more of E-long glass fibers and E-short glass fibers, optionally including E-short glass fibers.

Alkali-free long glass fiber or alkali-free short glass fiber can effectively improve the mechanical properties of PET modified materials.

In any embodiment, the diameter of the alkali-free short glass fiber is 7um-13um, optionally 7um-10um, and the fiber length of the alkali-free short glass fiber is 3mm-6mm, optionally 3mm-4.5mm.

Controlling the diameter and fiber length of alkali-free short glass fibers within an appropriate range can not only effectively improve the mechanical properties of PET modified materials, but also reduce the load on production equipment caused by the introduction of glass fibers.

The second aspect of the present application provides a method for preparing a PET modified material. The raw materials for preparing the PET modified material include:

Polyethylene terephthalate 45wt%~90wt%,

Thermally conductive filler 0wt%~20wt%,

Additive 1.3wt%~6.4wt%,

Glass fiber 7wt%~50wt%;

Wherein, the melt index of the PET modified material is 10g/10min-20g/10min.

Prepare PET modified materials by reacting thermally conductive fillers, additives, glass fibers and PET, and control its melt index to 10g/10min~20g/10min, so that the PET modified materials have a larger molecular weight, which is conducive to improving its PET modification The mechanical properties of the material.

In any embodiment, the auxiliary agent includes a toughening agent, a nucleating agent, a lubricant and an antioxidant, and optionally, the auxiliary agent further includes an antimony-containing compound.

Tougheners are beneficial to improve the toughness of PET modified materials, thereby improving the impact resistance of PET materials. The nucleating agent, as the nucleation site of the PET modified material, is conducive to the formation of crystalline substances and improves the mechanical properties of the PET modified material. The addition of the lubricant is beneficial to improve the fluidity during the preparation of the PET modified material, which can quickly release the mold and shorten the preparation cycle. Antioxidants are beneficial to improve the oxidation resistance of PET modified materials. Antimony-containing compounds can further accelerate the reaction rate of PET modified materials and shorten the production time.

In any embodiment, the preparation method comprises:

Mixing and processing the raw materials to prepare PET modified material pellet semi-finished products;

The PET modified material pellet semi-finished product is subjected to solid phase polycondensation reaction to obtain the PET modified material.

The molecular weight of the PET modified material can be increased by solid-state polycondensation reaction of the semi-finished PET modified material pellets, that is, the melt index of the PET modified material is further reduced, the viscosity is further increased, and the mechanical properties of the PET modified material are improved.

In any embodiment, the gas atmosphere of the solid-phase polycondensation reaction is a nitrogen atmosphere, and the vacuum degree of the solid-phase polycondensation reaction is lower than 50 Pa.

In any embodiment, the reaction temperature of the solid-state polycondensation reaction is 165°C-245°C, optionally 225°C-235°C, and the reaction time is 8h-15h, optionally 8h-12h.

Control the solid-state polycondensation reaction to react under appropriate conditions to increase the molecular weight of the PET modified material, that is, the melt index of the PET modified material is further reduced, the viscosity is further increased, and the mechanical properties of the PET modified material are improved.

In any embodiment, the preparation method specifically includes:

Putting polyethylene terephthalate and the auxiliary agent into a mixer and mixing to obtain a premix; optionally, the premix also includes the thermally conductive filler;

Adding the premix and the glass fiber into an extruder to process, extrude and pelletize to obtain the PET modified material pellet semi-finished product;

Under a nitrogen atmosphere and a vacuum degree lower than 50 Pa, the PET modified material pellet semi-finished product is subjected to solid-state polycondensation reaction, the reaction temperature is 165°C~245°C, and the reaction time is 8h~15h, to obtain the PET modified Material.

By further performing solid-state polycondensation reaction on the semi-finished PET modified material pellets, the molecular weight of the PET modified material is further increased, that is, the melt index of the PET modified material is further reduced, the viscosity is further increased, and the mechanical properties of the PET modified material are improved.

In any embodiment, the extrusion temperature of the extruder is 260° C. to 290° C., and the rotation speed of the extruder is 300 rpm to 450 rpm.

Controlling the extrusion temperature and rotational speed of the extruder within an appropriate range can not only make the raw materials fully mix and react, but also reduce the adverse effects of excessive temperature or excessive rotational speed on the semi-finished PET modified material pellets.

In any embodiment, the step of adding the premix and the glass fiber into an extruder to process, extrude and pelletize to obtain the semi-finished product of PET modified material pellets includes:

Add the premix through the main feed port of the extruder;

adding the glass fibers through the side feed port of the extruder;

The extrusion temperature of the extruder is controlled to be 260° C. to 290° C., and the rotation speed of the extruder is controlled to be 300 rpm to 450 rpm to obtain the semi-finished PET modified material pellets.

The premix and glass fiber are fed into the extruder through different feeding ports to make the premix and glass fiber mix evenly and fully react.

In any embodiment, the viscosity of the semi-finished PET modified material pellets is greater than 0.5dl/g, optionally greater than 0.65dl/g.

In any embodiment, the PET modified material has a viscosity greater than 0.65 dl/g, optionally greater than 0.85 dl/g.

The viscosity of the PET modified material is significantly greater than that of the semi-finished PET modified material pellets, that is, the molecular weight of the PET modified material is significantly greater than the molecular weight of the PET modified material pellet semi-finished product, and the mechanical properties of the PET modified material have been improved.

The third aspect of the present application provides the application of the modified PET material of the first aspect or the modified PET material prepared by the preparation method of the second aspect in automobiles.

Description of drawings

Fig. 1 is a scanning electron microscope image of a PET modified material according to an embodiment of the present application.

FIG. 2 is a partially enlarged view of FIG. 1 .

Detailed ways

Hereinafter, the embodiment of the modified PET material of the present application and its preparation method and application will be described in detail with appropriate reference to the accompanying drawings. However, unnecessary detailed description may be omitted. For example, detailed descriptions of well-known items and repeated descriptions of substantially the same configurations may be omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following descriptions are provided for those skilled in the art to fully understand the present application, and are not intended to limit the subject matter described in the claims.

A "range" disclosed herein is defined in terms of lower and upper limits, and a given range is defined by selecting a lower limit and an upper limit that define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive and may be combined arbitrarily, ie any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are contemplated. Additionally, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, the following ranges are all expected: 1-3, 1-4, 1-5, 2- 3, 2-4 and 2-5. In this application, unless otherwise stated, the numerical range "a-b" represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article, and "0-5" is only an abbreviated representation of the combination of these values. In addition, when expressing that a certain parameter is an integer ≥ 2, it is equivalent to disclosing that the parameter is an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

If there is no special description, all the implementation modes and optional implementation modes of the present application can be combined with each other to form new technical solutions.

If there is no special description, all the technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

Unless otherwise specified, all steps in the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed in sequence, and may also include steps (b) and (a) performed in sequence. For example, mentioning that the method may also include step (c) means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c) , may also include steps (a), (c) and (b), may also include steps (c), (a) and (b) and so on.

If there is no special description, the "comprising" and "comprising" mentioned in this application mean open or closed. For example, the "comprising" and "comprising" may mean that other components not listed may be included or included, or only listed components may be included or included.

In this application, the term "or" is inclusive unless otherwise stated. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied by either: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists) ; or both A and B are true (or exist).

Usually, PET materials are prepared by melt blending additives and PET matrix, but PET materials generally have too large melt index, low melt strength, and its mechanical properties do not meet the needs of products on the market. Therefore, it is necessary to provide a PET modified Advanced materials to meet the needs of modern emerging industries.

[PET modified material]

Based on this, the application proposes a PET modified material, and the preparation of the PET modified material includes the following components in mass percentage:

Polyethylene terephthalate 45wt%~90wt%,

Thermally conductive filler 0wt%~20wt%,

Additive 1.3wt%~6.4wt%,

Glass fiber 7wt%~50wt%;

Among them, the melt index of the PET modified material is 10g/10min~20g/10min.

In this paper, based on the total mass of PET modified materials, the total mass fraction of polyethylene terephthalate, thermal conductive filler, additives and glass fiber is 100%.

Herein, the term "auxiliary" refers to substances that can improve the properties of PET modified materials, including but not limited to toughening agents, nucleating agents, lubricants or antioxidants.

In some embodiments, based on the total mass of the PET modified material, the mass fraction of polyethylene terephthalate can be selected as 45wt%, 50wt%, 55wt%, 60wt%, 65wt%, 70wt%, 75wt% %, 80wt%, 85wt%, 90wt%, or a value in the range consisting of any two of the above points, the mass fraction of the thermally conductive filler can be 0wt%, 1wt%, 2wt%, 4wt%, 5wt%, 6wt%, 8wt%, 10wt%, 12wt%, 14wt%, 15wt%, 16wt%, 18wt%, 20wt%, or a value in the range consisting of any two points above, the mass fraction of additives can be 1.3wt%, 1.5 wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%, 6.4wt%, or a value in the range consisting of any two of the above , the mass fraction of glass fiber can be selected as 7wt%, 8wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt%, 50wt%, or any two points formed by the above Numeric values in the range.

In some embodiments, the melt index of the PET modified material is 10g/10min, 11g/10min, 12g/10min, 13g/10min, 14g/10min, 15g/10min, 16g/10min, 17g/10min, 18g/10min, 19g/10min, 20g/10min, or a value within the range formed by any two of the above.

In this paper, there is a negative correlation between the melt index and molecular weight of PET modified materials. The smaller the melt index of the PET modified material, the larger its molecular weight. The increase in the molecular weight of PET modified materials is conducive to the improvement of its mechanical properties.

Herein, the melt index of the PET modified material can be tested by any known method. As an example, the test of the melt index of the PET modified material is carried out with reference to the test standard ISO 1133. Take about 20g of the PET modified material and bake it in an oven at 150°C for 1 hour, put it into the melt index tester while it is still hot, and test it at a test temperature of 300°C and a mass of 2.16kg to obtain the melt index in g/10min.

Using polyethylene terephthalate (PET) as the base material, thermally conductive fillers, additives, glass fibers react with PET to prepare PET modified materials, and control its melt index to 10g/10min~20g/10min, so that PET The modified material has a larger molecular weight, which is conducive to improving the mechanical properties of its PET modified material.

In some embodiments, the viscosity of the PET modified material is greater than 0.65 dl/g, optionally greater than 0.85 dl/g.

In some embodiments, the viscosity of the PET modified material can be selected as 0.655dl/g, 0.66dl/g, 0.686dl/g, 0.70dl/g, 0.72dl/g, 0.74dl/g, 0.75dl/g, 0.76dl/g, 0.78dl/g, 0.8dl/g, 0.85dl/g, 0.9dl/g, 0.95dl/g, 1.0dl/g, 1.05dl/g, or within the range consisting of any two of the above value.

In this paper, the viscosity and molecular weight of PET modified materials are positively correlated. The greater the viscosity of the PET modified material, the greater its molecular weight. The increase in the molecular weight of PET modified materials is conducive to the improvement of its mechanical properties.

Herein, the viscosity of the PET modified material can be tested by any known method. As an example, refer to the test standard GB/T14190-2008 for the viscosity test of the PET modified material. Ubbelohde viscometer method, 0.84mm viscosity tube. The solvent is mixed with phenol and tetrachloroethane in a volume ratio of 1:1, and 500ml is prepared for use. Take 200mg of PET modified material into a 25ml volumetric flask, add 2/3 volume of mixed solvent, then put the volumetric flask into a constant temperature oil bath at 130°C for about 2~3 hours until the PET modified material is completely dissolved in In the solvent, observe the complete dissolution with the naked eye, take it out and cool it to room temperature 25°C, and then use the prepared solvent to dilute to 25ml. Next, the glass fibers in the dissolved PET modified material were filtered out using a Buchner funnel. The filtered PET modified material solution was used for viscosity test, and the viscosity was measured in dl/mg.

Control the viscosity of the PET modified material to be greater than 0.65dl/g, so that the PET modified material has a larger molecular weight, which is beneficial to the improvement of its mechanical properties.

In some embodiments, polyethylene terephthalate includes homopolyethylene terephthalate.

Homopolyethylene terephthalate has a regular molecular structure, which is conducive to the improvement of the crystallinity of PET modified materials, and then improves the mechanical properties of PET modified materials.

In some embodiments, the thermally conductive filler includes one or more of flake graphene, natural graphite, carbon nanotubes, carbon fibers, thermally conductive carbon materials, boron nitride, aluminum nitride, silicon carbide, aluminum oxide, and magnesium oxide , optionally comprising graphene flakes.

In this paper, the term "flaky graphene" refers to a single-layer graphene layer stack with more than 10 carbon layers and a thickness in the range of 5-100 nm. Sheet-like graphene has an ultrathin structure. Flake graphene maintains the original planar carbon six-membered ring conjugated crystal structure of single-layer graphene, and still has excellent mechanical strength, thermal conductivity, and good lubrication, high temperature resistance and corrosion resistance.

The addition of thermally conductive fillers is conducive to improving the thermal conductivity of the PET modified material, that is, the heat dissipation of the PET modified material is significantly improved.

In some embodiments, the preparation of PET modified materials includes the following components in mass percent:

Polyethylene terephthalate 45wt%~90wt%,

Flake graphene 1wt%~20wt%,

Additive 1.3wt%~6.4wt%,

Glass fiber 7wt%~50wt%.

In some embodiments, based on the total mass of the PET modified material, the mass fraction of graphene flakes can be selected as 0wt%, 1wt%, 2wt%, 4wt%, 5wt%, 6wt%, 8wt%, 10wt%, 12wt%, 14wt%, 15wt%, 16wt%, 18wt%, 20wt%, or a value in the range formed by any two of the above.

Since flake graphene has a planar carbon six-membered ring conjugated crystal structure, and the thickness of flake graphene is in the range of nanometer size, its radial width can reach micron level, the radial width and thickness of flake graphene A large ratio can increase the contact area. Therefore, the flake graphene can significantly improve the thermal conductivity of the PET modified material, and greatly improve the heat dissipation performance of the PET modified material.

In some embodiments, the auxiliary agent includes a toughening agent, a nucleating agent, a lubricant and an antioxidant, and optionally, the auxiliary agent further includes an antimony-containing compound.

The above additives can comprehensively improve the toughness, crystallinity, processability and oxidation resistance of PET modified materials.

In some embodiments, based on the total mass of the PET modified material, the mass fraction of the toughening agent is 1 wt % to 5 wt %. In some embodiments, based on the total mass of the PET modified material, the mass fraction of the toughening agent can be selected as 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5 wt%, 5wt%, or a value in the range consisting of any two of the above points.

In some embodiments, the toughening agent includes ethylene-methyl acrylate-glycidyl methacrylate copolymer, polymethyl acrylate, polyethyl acrylate, copolyethylene terephthalate, olefin copolymer elastic Body, one or more of polyether ester.

In this paper, the mass content of glycidyl methacrylate (GMA) in ethylene-methyl acrylate-glycidyl methacrylate copolymer is 6%~10%, ethylene-methyl acrylate-glycidyl methacrylate The mass content of ethylene or methyl acrylate in the ester copolymer is not limited.

The above toughening agents can effectively improve the toughness of the PET modified material, and reduce the risk of cracks in the PET modified material under external impact, resulting in a decrease in impact resistance. Controlling the mass fraction of the toughening agent within an appropriate range can not only effectively improve the toughness of the PET modified material, but also avoid the adverse effects of excessive toughening agent degradation on the PET modified material at high temperature.

In some embodiments, based on the total mass of the PET modified material, the mass fraction of the nucleating agent is 0.1 wt% to 0.35 wt%. In some embodiments, based on the total mass of the PET modified material, the mass fraction of the nucleating agent can be selected as 0.1wt%, 0.15wt%, 0.2wt%, 0.25wt%, 0.3wt%, 0.35wt%, or A value in the range formed by any two of the above points.

In some embodiments, the nucleating agent includes one or more of an organic nucleating agent and an inorganic nucleating agent, and the organic nucleating agent includes sodium montanate, sorbitol salt, benzoate, P250, Surlyn8920, RS One or more of -735, the inorganic nucleating agent includes one or more of talcum powder and barium sulfate.

The above-mentioned nucleating agents can be used as the crystallization site of the PET modified material, so that the PET modified material has a suitable crystallinity, which is beneficial to the improvement of the mechanical properties of the PET modified material. Controlling the mass fraction of the nucleating agent within an appropriate range is conducive to providing enough nucleating sites to make the PET modified material a crystalline substance, improving its mechanical properties, and reducing the introduction of too much nucleating agent The effect on the properties of PET modified materials.

In some embodiments, based on the total mass of the PET modified material, the mass fraction of the lubricant is 0.1 wt% to 0.5 wt%. In some embodiments, based on the total mass of the PET modified material, the mass fraction of the lubricant can be selected as 0.1wt%, 0.15wt%, 0.2wt%, 0.25wt%, 0.3wt%, 0.35wt%, 0.4wt% %, 0.45wt%, 0.5wt%, or a value in the range consisting of any two of the above points.

In some embodiments, the lubricant includes one or more of silicone powder, silicone masterbatch, polyethylene wax, stearate, and montanate.

All of the above lubricants can improve the processing performance of PET modified materials. Controlling the mass fraction of the lubricant in an appropriate range can not only effectively improve the processing performance of the PET modified material, but also reduce the influence of the introduction of too much lubricant on the performance of the PET modified material.

In some embodiments, based on the total mass of the PET modified material, the mass fraction of the antioxidant is 0.1 wt% to 0.5 wt%. In some embodiments, based on the total mass of the PET modified material, the mass fraction of the antioxidant can be selected as 0.1wt%, 0.15wt%, 0.2wt%, 0.25wt%, 0.3wt%, 0.35wt%, 0.4 wt%, 0.45wt%, 0.5wt%, or a value in the range consisting of any two of the above.

In some embodiments, the antioxidant includes one or more of hindered phenolic antioxidants and phosphite antioxidants, and hindered phenolic antioxidants include antioxidant 1010, antioxidant 2246, antioxidant One or more of Oxygen 1076, Antioxidant 330, phosphite antioxidants include Antioxidant 168, Antioxidant 626, Antioxidant 619, Antioxidant 3010, Antioxidant PEP36 one or more species.

The above antioxidants can improve the oxidation resistance of PET modified materials. Controlling the mass fraction of antioxidants in an appropriate range can not only effectively improve the oxidation resistance of PET modified materials, but also reduce the impact of the introduction of too much antioxidant on the properties of PET modified materials.

In some embodiments, the antimony-containing compound includes one or more of sodium antimonate, antimony trioxide, antimony glycolate, antimony acetate, and antimony trichloride.

In some embodiments, the glass fibers include one or more of E-long glass fibers, E-short glass fibers, optionally including E-short glass fibers.

E-long glass fibers or E-short glass fibers can effectively enhance the mechanical properties of PET modified materials.

In some embodiments, the diameter of the short alkali-free glass fiber is 7um~13um, optionally 7um~10um, and the fiber length of the short alkali-free glass fiber is 3mm~6mm, optionally 3mm~4.5mm. In some embodiments, the diameter of the alkali-free short glass fiber can be 7um, 8um, 9um, 10um, 11um, 12um, 13um, or a value in the range formed by any two of the above-mentioned points, and the fiber of the alkali-free short glass fiber The length may be 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, or a numerical value in the range formed by any two points above.

Controlling the diameter and fiber length of alkali-free short glass fibers within an appropriate range can not only effectively improve the mechanical properties of PET modified materials, but also reduce the load on production equipment caused by the introduction of glass fibers.

The application also provides a method for preparing PET modified materials, the raw materials for preparing PET modified materials include:

Polyethylene terephthalate 45wt%~90wt%,

Thermally conductive filler 0wt%~20wt%,

Additive 1.3wt%~6.4wt%,

Glass fiber 7wt%~50wt%;

Among them, the melt index of the PET modified material is 10g/10min~20g/10min.

Prepare PET modified materials by reacting thermally conductive fillers, additives, glass fibers and PET, and control its melt index to 10g/10min~20g/10min, so that the PET modified materials have a larger molecular weight, which is conducive to improving its PET modification The mechanical properties of the material. Among them, the addition of thermally conductive fillers can not only improve the heat dissipation performance of PET modified materials, but also increase the crystallization temperature of PET modified materials, shorten the production cycle of PET modified materials, and improve production efficiency.

In some embodiments, the auxiliary agent includes a toughening agent, a nucleating agent, a lubricant and an antioxidant, and optionally, the auxiliary agent further includes an antimony-containing compound.

Tougheners are beneficial to improve the toughness of PET modified materials, thereby improving the impact resistance of PET materials. The nucleating agent, as the nucleation site of the PET modified material, is conducive to the formation of crystalline substances and improves the mechanical properties of the PET modified material. The addition of the lubricant is beneficial to improve the fluidity during the preparation of the PET modified material, which can quickly release the mold and shorten the preparation cycle. Antioxidants are beneficial to improve the oxidation resistance of PET modified materials. Antimony-containing compounds can further accelerate the reaction rate of PET modified materials and shorten the production time.

In some embodiments, the preparation method includes:

Mix raw materials and prepare semi-finished products of PET modified material pellets;

The PET modified material pellet semi-finished product is subjected to solid phase polycondensation reaction to obtain the PET modified material.

In this article, the term "solid-state polycondensation reaction" refers to the polycondensation reaction of molten polyethylene terephthalate with a lower molecular weight in the semi-finished product of PET modified material pellets under the action of a catalyst under vacuum and high temperature conditions. , so that the molecular weight of the PET modified material increases, that is, the melt index decreases. The polycondensation reaction can be a polycondensation reaction between low molecular weight polyethylene terephthalate with carboxyl groups and diethylene glycol, or a low molecular weight polyethylene terephthalate with carboxyl or terminal hydroxyl groups. The solid-state polycondensation reaction has the advantages of low reaction temperature, less side reactions, low acetaldehyde content, and excellent product performance.

It can be understood that the preparation method of conventional PET materials is only to mix PET modified materials with thermally conductive fillers and additives for high-temperature reaction and then extrude. The melt index is generally high, the molecular weight is low, and the mechanical properties are low. In the embodiment of the present application, the semi-finished product of PET modified material pellets is subjected to solid-state polycondensation reaction, which can increase the molecular weight of the PET modified material, that is, the melt index of the PET modified material is further reduced, and the viscosity is further increased, which improves the PET modified material. The mechanical properties of the material.

In addition, the addition of thermally conductive fillers can significantly improve the thermal conductivity of PET modified materials, that is, the addition of thermally conductive fillers can make PET modified materials have excellent heat dissipation performance, but the addition of thermally conductive fillers usually affects the mechanical properties of PET modified materials. The reduction is not conducive to the mechanical properties of PET modified materials. In the embodiment of the present application, the mixed processed PET modified material pellet semi-finished product is further subjected to solid-state polycondensation reaction to increase the molecular weight of the PET modified material, that is, the melt index of the PET modified material is further reduced, and the viscosity is further increased. Modified mechanical properties of materials.

In some embodiments, the gas atmosphere of the solid-phase polycondensation reaction is a nitrogen atmosphere, and the vacuum degree of the solid-phase polycondensation reaction is lower than 50 Pa.

In some embodiments, the reaction temperature of the solid-state polycondensation reaction is 165°C-245°C, optionally 225°C-235°C, and the reaction time is 8h-15h, optionally 8h-12h. In some embodiments, the reaction temperature of the solid phase polycondensation reaction can be selected as 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C, 205°C, 210°C, 215°C, 220°C °C, 225 °C, 230 °C, 235 °C, 240 °C, 245 °C, or a value in the range formed by any two of the above points, the reaction time can be 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h , or a value within the range consisting of any two of the above points.

It can be understood that the solid-phase polycondensation reaction is a reversible reaction, and controlling the vacuum degree, reaction time and reaction temperature of the solid-phase polycondensation reaction in an appropriate range is conducive to the forward progress of the polycondensation reaction, so that the molecular weight of the PET modified material It is improved, that is, the melt index of the PET modified material is further reduced, the viscosity is further increased, and the mechanical properties of the PET modified material are improved. At the same time, the solid-state polycondensation reaction is also conducive to reducing the content of terminal carboxyl groups in PET modified materials, which can effectively improve the hydrolysis resistance of PET modified materials, and comprehensively improve the performance of PET modified materials.

In addition, controlling the vacuum degree of the solid-state polycondensation reaction to be lower than 50Pa is also conducive to the large amount of low molecular weight substances (such as small molecular substances, diethylene glycol and water molecules produced by the decomposition of toughening agents and nucleating agents at high temperatures) in vacuum. Downgassing is pumped away so that the PET compounds have low volatile content.

In some embodiments, the preparation method specifically includes:

Putting polyethylene terephthalate and additives into a mixer and mixing to obtain a premix; optionally, the premix also includes thermally conductive fillers;

Add the premix and glass fiber to the extruder for processing, extruding and pelletizing to obtain semi-finished PET modified material pellets;

Under a nitrogen atmosphere and a vacuum lower than 50Pa, the semi-finished PET modified material pellets are subjected to solid-state polycondensation reaction at a reaction temperature of 165°C~245°C and a reaction time of 8h~15h to obtain a PET modified material.

By further performing solid-state polycondensation reaction on the semi-finished PET modified material pellets, the molecular weight of the PET modified material is further increased, that is, the melt index of the PET modified material is further reduced, the viscosity is further increased, and the mechanical properties of the PET modified material are improved.

In some embodiments, the extrusion temperature of the extruder is 260° C. to 290° C., and the rotation speed of the extruder is 300 rpm to 450 rpm. In some embodiments, the extrusion temperature of the extruder is 260°C, 265°C, 270°C, 275°C, 280°C, 285°C, 290°C, or a value in the range formed by any two of the above points. The rotational speed of the machine is 300rmp, 320rmp, 340rmp, 350rmp, 360rmp, 380rmp, 400rmp, 420rmp, 440rmp, 450rmp, or a value in the range formed by any two of the above points.

Herein, the head vacuum of the extruder is controlled below 0.08MPa, and the low molecular weight substances that do not participate in the reaction in the premix (such as low molecular weight substances including ethanol, oxalic acid, diethylene glycol, carboxyl-terminated, Terephthalic acid or water molecules) are gasified and taken away under vacuum to reduce the impact of the accumulation of low molecular weight substances on the performance of PET modified materials.

Controlling the extrusion temperature and rotational speed of the extruder within an appropriate range can not only make the raw materials fully mix and react, but also reduce the adverse effects of excessive temperature or excessive rotational speed on the semi-finished PET modified material pellets.

In some embodiments, the premix and glass fiber are added to the extruder for processing and extruded pelletizing, and the step of obtaining the semi-finished product of PET modified material pellets includes:

Add the premix through the main feed port of the extruder;

Add glass fiber through the side feed port of the extruder;

The extrusion temperature of the extruder is controlled to be 260° C. to 290° C., and the rotational speed of the extruder is 300 rpm to 450 rpm to obtain a semi-finished product of PET modified material pellets.

The premix and glass fiber are fed into the extruder through different feeding ports to make the premix and glass fiber mix evenly and fully react.

Controlling the extrusion temperature of the extruder within an appropriate range can not only make the reaction between the premix and glass fiber occur, but also avoid the decomposition of the premix caused by excessive temperature, which will have adverse effects. Control the extrusion speed of the extruder within an appropriate range, which can not only meet the demand for uniform mixing, but also avoid damage to the semi-finished PET modified material pellets caused by excessive extrusion speed, for example, excessive extrusion speed Excessive shear force will be generated to act on the premix and glass fiber, causing the premix to be easily decomposed into small molecules, which is not conducive to the performance of the semi-finished PET modified material pellets.

In some embodiments, the viscosity of the PET modified material pellet blank is greater than 0.5 dl/g, optionally greater than 0.65 dl/g.

In some embodiments, the viscosity of the PET modified material is greater than 0.65 dl/g, optionally greater than 0.85 dl/g.

The viscosity of the PET modified material is significantly greater than that of the semi-finished PET modified material pellets, that is, the molecular weight of the PET modified material is significantly greater than the molecular weight of the PET modified material pellet semi-finished product, and the mechanical properties of the PET modified material have been improved.

The present application also provides the application of the modified PET material in some embodiments or the modified PET material prepared by the preparation method in some embodiments in automobiles.

PET modified materials with excellent heat dissipation and mechanical properties can be widely used in the automotive field, especially in the field of new energy vehicles. Lamp module or heat conduction car lamp bracket, due to its excellent heat dissipation performance and mechanical properties, can not only meet the heat dissipation requirements of new energy vehicles, reduce the risk of thermal runaway caused by the inability to spread heat in time, but also meet the needs of new energy vehicles for mechanical Strength needs to make it have a certain impact resistance. In addition, the PET modified material has low volatile matter content and hydrolysis resistance, which can effectively improve its service life, and the PET modified material is used in the field of new energy vehicles, such as in modular car light modules and heat conduction vehicles For lamp brackets, because the PET modified material has low volatile matter content and hydrolysis resistance, its haze is low, which effectively improves the use feeling and safety of new energy vehicles.

Example

Hereinafter, examples of the present application will be described. The embodiments described below are exemplary and are only used for explaining the present application, and should not be construed as limiting the present application. If no specific technique or condition is indicated in the examples, it shall be carried out according to the technique or condition described in the literature in this field or according to the product specification. The reagents or instruments used were not indicated by the manufacturer, and they were all commercially available conventional products.

1. Preparation method

Example 1

Preparation of PET modified materials

Polyethylene terephthalate, toughening agent ethylene/methyl acrylate/glycidyl methacrylate, nucleating agent sodium montanate, lubricant silicone powder, sodium antimonate, antioxidant 168 and anti Oxygen 1010 (mass ratio of antioxidant 168 to antioxidant 1010 is 1:1) is put into a high mixer according to 64:1:0.15:0.2:0.05:0.2 and mixed evenly to obtain a premix.

The premix is added through the main feed of the twin-screw extruder, and the short glass fiber is added through the side feed of the twin-screw extruder (the mass ratio of glass fiber to premix is 65.6:34.4), and the twin-screw extruder The vacuum degree of the head of the extruder is controlled below 0.08MPa, the extrusion temperature of the twin-screw extruder is controlled at 280°C, and the screw speed of the twin-screw extruder is controlled at 390RPM to prepare semi-finished PET modified material pellets.

Subsequently, the semi-finished PET modified material pellets are transferred to a viscosification-transfer machine for solid-state polycondensation. Control the temperature in the viscosification-transsolidation machine to rise to 120°C, and pass inert gas to discharge the water vapor and oxygen inside the viscosification-consolidation machine; continue to control the temperature in the viscosification-consolidation machine to rise to 150°C, stop The introduction of inert gas; continue to control the temperature in the viscosification-transfer machine to rise to 230°C, control the pressure of the viscosification-transfer machine at 20Pa, and perform solid-phase polycondensation. When the product in the viscosification-transfer machine melts When the index is less than 20g/10min, the reaction is stopped to obtain a PET modified material.

Example 2

The preparation method of PET modified material in embodiment 2 is basically similar to embodiment 1, but in the premix, added thermally conductive filler flake graphene and adjusted the quality of polyethylene terephthalate in PET modified material content, the mass content of other additives remains unchanged, and the specific parameters are shown in Table 1.

Example 3

The PET modified material preparation method in embodiment 3 is basically similar to embodiment 2, but adjusted the mass content of polyethylene terephthalate in thermally conductive filler flake graphene and PET modified material in the premix, The mass content of other additives remains unchanged, and the specific parameters are shown in Table 1.

Example 4

The preparation method of the PET modified material in Example 4 is basically similar to that of Example 2, but the thermally conductive filler flake graphene in the premix is adjusted to the thermally conductive filler magnesium oxide, and the specific parameters are shown in Table 1.

Example 5

The preparation method of the PET modified material in Example 5 is basically similar to that of Example 3, but the thermally conductive filler flake graphene in the premix is adjusted to the thermally conductive filler magnesium oxide, and the specific parameters are shown in Table 1.

Embodiment 6~10

The preparation method of the PET modified material in Examples 6-10 is basically similar to that of Example 2, but the pressure, reaction temperature and reaction time of the solid phase polycondensation in the preparation method of the PET modified material were adjusted, and the specific parameters are shown in Table 1.

Comparative example 1

The PET modified material preparation method in comparative example 1 is basically similar to embodiment 1, but does not comprise solid phase polycondensation reaction in the PET modified material preparation method, specifically:

Polyethylene terephthalate, toughening agent ethylene/methyl acrylate/glycidyl methacrylate, nucleating agent sodium montanate, lubricant silicone powder, sodium antimonate, antioxidant 168 and anti Oxygen 1010 (mass ratio of antioxidant 168 to antioxidant 1010 is 1:1) is put into a high mixer according to 64:1:0.15:0.2:0.05:0.2 and mixed evenly to obtain a premix.

The premix is added through the main feed of the twin-screw extruder, and the short glass fiber is added through the side feed of the twin-screw extruder (the mass ratio of glass fiber to premix is 65.6:34.4), and the twin-screw extrusion The head vacuum of the extruder is controlled below 0.08 MPa, the extrusion temperature of the twin-screw extruder is controlled at 280° C., and the screw speed of the twin-screw extruder is controlled at 350 RPM to obtain PET modified materials.

Comparative example 2

The preparation method of the PET modified material in Comparative Example 2 is basically similar to that of Comparative Example 1, but the thermally conductive filler flake graphene is added to the premix and the content of other components in the PET modified material is adjusted. The specific parameters are shown in the table 1.

Comparative example 3

The preparation method of the PET modified material in Comparative Example 3 is basically similar to that of Comparative Example 2, but the content of the thermally conductive filler flake graphene in the premix and the content of other components in the PET modified material were adjusted. The specific parameters are shown in the table 1.

Comparative example 4

The preparation method of the PET modified material in Comparative Example 4 is basically similar to that of Comparative Example 2, but the thermally conductive filler flake graphene in the premix is adjusted to the thermally conductive filler magnesium oxide, and the specific parameters are shown in Table 1.

Comparative example 5

The preparation method of the PET modified material in Comparative Example 5 is basically similar to that of Comparative Example 3, but the thermally conductive filler flake graphene in the premix is adjusted to the thermally conductive filler magnesium oxide, and the specific parameters are shown in Table 1.

2. Performance test

1. Performance test of PET modified materials

1) Melt Flow Rate (MFR) test

Reference test standard ISO 1133. Take about 20g of the PET modified material and bake it in an oven at 150°C for 1 hour, put it into the melt index tester while it is still hot, and perform the test according to the test temperature of 300°C and the mass of 2.16kg, and measure the melt index in g/10min.

2) Viscosity test

Refer to the test standard GB/T14190-2008. Ubbelohde viscometer method, 0.84mm viscosity tube. The solvent is mixed with phenol and tetrachloroethane in a volume ratio of 1:1, and 500ml is prepared for use. Take 200mg of PET modified material into a 25ml volumetric flask, add 2/3 volume of mixed solvent, then put the volumetric flask into a constant temperature oil bath at 130°C for about 2~3 hours until the PET modified material is completely dissolved in In the solvent, observe the complete dissolution with the naked eye, take it out and cool it to room temperature 25°C, and then use the prepared solvent to dilute to 25ml. Next, the glass fibers in the dissolved PET modified material were filtered out using a Buchner funnel. The filtered PET modified material solution is used for viscosity test, and the viscosity is measured, and the unit is dl/mg.

3) Thermal conductivity test

Refer to Transient Plane Method Test - Refer to test standard ASTM D5470. The diameter and thickness of injection molding samples made of PET modified materials for injection molding machines are 30 mm × 2 mm, and the thermal conductivity meter of TH-91-13-00654 from Canada C-Therm Company is used for testing. The unit of thermal conductivity is W/(m K)

4) Tensile strength test

Reference test standard ISO 527. Utilize an injection molding machine to inject type 1a standard splines with PET modified materials (type 1a spline gauge length is 50±0.5mm, distance between fixtures is 115±5mm), and use a universal testing machine to test the tensile strength at a tensile rate of 10mm/min , stretched to the maximum tensile strength of the material to break, then it is the tensile strength of the PET modified material, and the unit is Mpa.

5) Elongation at break test

Reference test standard ISO 527. Utilize an injection molding machine to inject type 1a standard splines with PET modified materials (the gauge length of type 1a splines is 50±0.5mm, and the distance between fixtures is 115±5mm), and use a universal testing machine to test the tensile strength, and the tensile rate is 10mm/min , install the test elongation clamping device so that the sample is located on the vertical plane of the upper and lower clamps, and fine-tune the position of the upper clamp so that the sample is completely straightened without force; use a vernier caliper to measure the distance between the upper and lower clamps at this time - Record L ₀ , the elongation within the gauge length when the sample breaks, that is, the stroke read when it breaks - record ΔL _b , the elongation at break Σ=ΔL _b /L ₀ ×100, the unit is %.

6) Bending strength test

Reference test standard ISO 178. Utilize the injection molding machine to inject standard splines (spline length 80mm±2mm, width 10.0mm±0.2mm, thickness 4.0mm±0.2mm), use a universal testing machine for bending strength test, bending rate 2mm/min, three-point load, will test Place the sample on two fulcrums, apply a load to the center of the fulcrum, measure the pressure applied to the sample during the process, and the bending stress when the load reaches the maximum value is the bending strength, and the unit is Mpa.

7) Flexural modulus test

Reference test standard ISO 178. Utilize the injection molding machine to inject standard splines (spline length 80mm±2mm, width 10.0mm±0.2mm, thickness 4.0mm±0.2mm), use a universal testing machine for bending strength test, bending rate 2mm/min, three-point load, will test Place the sample on two fulcrums, apply a load to the center of the fulcrum, measure the pressure applied to the sample during the process, the bending stress when the load reaches the maximum value, and the ratio of the bending stress to the strain generated by the upper bending to obtain the bending modulus, the unit is Mpa.

8) Unnotched impact (charpy beam) test

Reference test standard ISO 179. Charpy unnotched impact strength test, use injection molding machine to inject standard spline (spline length 80mm±2mm, width 10.0mm±0.2mm, thickness 4.0mm±0.2mm), use impact tester to test, place the sample on simply supported The beam impact machine is placed at the specified position, and then the pendulum is used to fall freely, and the impact bending load is applied to the sample to break the sample. The impact toughness of the material is obtained by using the ratio of the impact energy consumed by the unit cross-sectional area of the sample to the area, and the unit is KJ/m ² .

9) Crystallization temperature test

Reference test standard ISO 11357-3. Using a differential scanning calorimeter, the test conditions are in a nitrogen environment, the temperature is raised from 30°C to 300°C at a rate of 20°C/min, and the temperature is kept constant for 5 minutes; then the temperature is lowered from 300°C to 50°C at a rate of 20°C/min, and the temperature is kept constant for 5 minutes ; Then the temperature was raised from 50°C to 300°C at a rate of 20°C/min. The crystallization temperature is obtained by standardizing the peak tip temperature of the exothermic peak in the cooling section, and the unit is °C.

10) Haze test

Refer to the standard VW 50181 test. The test adopts the gravimetric method. The sample requires a diameter and thickness of 80mm×2mm. The atomizer is used for analysis and testing. The unit of haze is ug/g.

11) Scanning electron micrograph of PET modified material

Use tetrachloroethane solvent to dissolve the PET modified material at a temperature of 130 °C, and wash off the tetrachloroethane with ethanol after filtration. Use a scanning electron microscope to observe the morphology of the insoluble matter after filtration and washing, mainly glass fibers and Morphology of resin on glass fiber surface.

Three, each embodiment, comparative example test result analysis

The batteries of each example and comparative example were respectively prepared according to the above method, and various performance parameters were measured. The results are shown in Table 1 and Table 2 below.

Table 1

Table 2

According to the above results, it can be seen that the melt index of the PET modified materials in Examples 1-10 is 10g/10min-20g/10min, all of which have excellent heat dissipation and mechanical properties.

As can be seen from Fig. 1 and Fig. 2, in the embodiment of the present application, the component polyethylene terephthalate and the component heat-conducting fillers of the PET modified material are in contact with the component glass fibers in large quantities, and they form a Chemical bonds, the mechanical properties of PET modified materials can be significantly improved.

Embodiment 1 and comparative example 1, embodiment 2,7～10, embodiment 3 and comparative example 3, embodiment 4 and comparative example 4, the contrast of embodiment 5 and comparative example 5 can be seen, and the melting of controlled PET modified material The index is 10g/10min~20g/10min, which is beneficial to improve the tensile strength, flexural strength, flexural modulus, and unnotched impact force (simply supported beam) of PET modification.

Embodiment 1 and comparative example 1, embodiment 2,7～10, embodiment 3 and comparative example 3, embodiment 4 and comparative example 4, the contrast of embodiment 5 and comparative example 5 can be seen, and the preparation method of PET modified material comprises Solid-state polycondensation reaction, so that the melt index of PET modified materials is 10g/10min~20g/10min, and its viscosity is greater than 0.65dl/mg, thereby improving tensile strength, elongation at break, flexural strength, flexural modulus, no Notch impact force (charpy) and thermal conductivity, reduce haze, comprehensively improve the mechanical properties and heat dissipation properties of PET modified materials, and broaden the application fields of PET modified materials.

From the comparison between Examples 2~5 and Example 1, it can be seen that the addition of thermally conductive filler flake graphene or magnesium oxide can significantly improve the thermal conductivity of PET modified materials, improve the heat dissipation performance of PET modified materials, and also improve the thermal conductivity of PET modified materials. Crystallization temperature of PET modified materials. From the comparison between Example 2 and Example 4, Example 3 and Example 5, it can be seen that compared with magnesium oxide as a thermally conductive filler, flake graphene as a thermally conductive filler can further improve the thermal conductivity of PET modified materials, and maximize the thermal conductivity of PET modified materials. To improve the heat dissipation performance of PET modified materials.

It can be seen from Examples 2 and 6 that the vacuum degree of controlling the solid-state polycondensation reaction is lower than 50 Pa, which can make the PET modified material have excellent mechanical properties and heat dissipation properties.

It can be seen from Examples 2, 7-10 that controlling the reaction temperature of the solid-state polycondensation reaction to be 165°C-245°C can make the PET modified material have excellent mechanical properties and heat dissipation properties.

It can be seen from Examples 2, 7-10 that controlling the reaction time of the solid-state polycondensation reaction to be 8h-15h can make the PET modified material have excellent mechanical properties and heat dissipation properties.

It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and within the scope of the technical solutions of the present application, embodiments that have substantially the same configuration as the technical idea and exert the same effects are included in the technical scope of the present application. In addition, without departing from the scope of the present application, various modifications conceivable by those skilled in the art are added to the embodiments, and other forms constructed by combining some components in the embodiments are also included in the scope of the present application. .

Claims (31)

1. The PET modified material is characterized by comprising the following components in percentage by mass:

45-90 wt% of polyethylene terephthalate,

0-20 wt% of heat conducting filler,

1.3-6.4 wt% of auxiliary agent,

7-50 wt% of glass fiber;

the melt index of the PET modified material is 10g/10 min-20 g/10min.

2. The PET-modified material of claim 1, wherein the viscosity of the PET-modified material is greater than 0.65dl/g.

3. The PET-modified material of claim 2, wherein the viscosity of the PET-modified material is greater than 0.85dl/g.

4. The PET-modified material of claim 1, wherein the polyethylene terephthalate comprises a homo-polyethylene terephthalate.

5. The PET-modified material of claim 1, wherein the thermally conductive filler comprises one or more of graphene flakes, natural graphite, carbon nanotubes, carbon fibers, thermally conductive carbon materials, boron nitride, aluminum nitride, silicon carbide, aluminum oxide, magnesium oxide.

6. The PET-modified material of claim 5, wherein the PET-modified material is prepared from the following components in percentage by mass:

45-90 wt% of polyethylene terephthalate,

1-20wt% of flaky graphene,

1.3-6.4 wt% of auxiliary agent,

7-50 wt% of glass fiber.

7. The PET-modified material of claim 1, wherein the auxiliary agents comprise a toughening agent, a nucleating agent, a lubricant, and an antioxidant.

8. The PET-modified material of claim 7, wherein the auxiliary agent further comprises an antimony-containing compound.

9. The PET-modified material of claim 7, wherein the mass fraction of the toughening agent is 1wt% to 5wt% based on the total mass of the PET-modified material;

the toughening agent comprises one or more of ethylene-methyl acrylate-glycidyl methacrylate copolymer, polymethyl acrylate, polyethyl acrylate, copolymerized polyethylene terephthalate, olefin copolymer elastomer and polyether ester.

10. The PET-modified material of claim 7, wherein the mass fraction of the nucleating agent is 0.1wt% to 0.35wt% based on the total mass of the PET-modified material;

the nucleating agent comprises one or more of an organic nucleating agent and an inorganic nucleating agent, wherein the organic nucleating agent comprises one or more of sodium montanate, sorbitol salt and benzoate, and the inorganic nucleating agent comprises one or more of talcum powder and barium sulfate.

11. The PET-modified material of claim 7, wherein the mass fraction of the lubricant is 0.1wt% to 0.5wt% based on the total mass of the PET-modified material;

the lubricant comprises one or more of silicone powder, silicone master batch, polyethylene wax, stearate and montanate.

12. The PET-modified material according to claim 7, wherein the antioxidant is 0.1wt% to 0.5wt% based on the total mass of the PET-modified material;

the antioxidant comprises one or more of hindered phenol antioxidants and phosphite antioxidants, wherein the hindered phenol antioxidants comprise one or more of antioxidants 1010, 2246, 1076 and 330, and the phosphite antioxidants comprise one or more of antioxidants 168, 626, 619, 3010 and PEP 36.

13. The PET-modified material of any one of claims 1 to 12, wherein the glass fibers comprise one or more of alkali-free long glass fibers, alkali-free short glass fibers.

14. The PET-modified material of any one of claims 1 to 12, wherein the glass fibers comprise alkali-free short glass fibers.

15. The PET-modified material of claim 14, wherein the alkali-free short glass fibers have a diameter of 7um to 13um and a fiber length of 3mm to 6mm.

16. The PET-modified material of claim 15, wherein the alkali-free short glass fibers have a diameter of 7um to 10um and a fiber length of 3mm to 4.5mm.

17. The preparation method of the PET modified material is characterized by comprising the following raw materials:

45-90 wt% of polyethylene terephthalate,

0-20 wt% of heat conducting filler,

1.3-6.4 wt% of auxiliary agent,

7-50 wt% of glass fiber;

the melt index of the PET modified material is 10g/10 min-20 g/10min.

18. The method of claim 17, wherein the auxiliary agents include toughening agents, nucleating agents, lubricants, and antioxidants.

19. The method of claim 18, wherein the auxiliary agent further comprises an antimony-containing compound.

20. The method of manufacturing according to claim 17, characterized in that the method of manufacturing comprises:

Mixing and processing the raw materials to prepare a PET modified material pellet semi-finished product;

and carrying out solid-phase polycondensation reaction on the PET modified material pellet semi-finished product to obtain the PET modified material.

21. The method according to claim 20, wherein the gas atmosphere of the solid phase polycondensation reaction is a nitrogen atmosphere, and the vacuum degree of the solid phase polycondensation reaction is lower than 50Pa;

the reaction temperature of the solid phase polycondensation reaction is 165-245 ℃ and the reaction time is 8-15 h.

22. The method according to claim 21, wherein the gas atmosphere of the solid phase polycondensation reaction is a nitrogen atmosphere, and the vacuum degree of the solid phase polycondensation reaction is lower than 50Pa;

the reaction temperature of the solid phase polycondensation reaction is 225-235 ℃, and the reaction time is 8-12 h.

23. The preparation method according to claim 20, characterized in that it comprises in particular:

putting polyethylene glycol terephthalate and the auxiliary agent into a mixer to be mixed to obtain a premix;

adding the premix and the glass fiber into an extruder, processing, extruding and granulating to obtain a PET modified material pellet semi-finished product;

and (3) carrying out solid-phase polycondensation reaction on the PET modified material pellet semi-finished product in a nitrogen atmosphere under the vacuum degree lower than 50Pa, wherein the reaction temperature is 165-245 ℃ and the reaction time is 8-15 h, and thus the PET modified material is obtained.

24. The method of making according to claim 23, wherein the premix further comprises the thermally conductive filler.

25. The method according to claim 23, wherein the extrusion temperature of the extruder is 260 ℃ to 290 ℃ and the rotation speed of the extruder is 300rmp to 450rmp.

26. The method of claim 23, wherein the step of adding the premix and the glass fibers to an extruder to process and extrude pellets to produce the semi-finished PET-modified material pellets comprises:

adding the premix through a main feeding port of an extruder;

adding the glass fiber through a side feeding port of an extruder;

the extrusion temperature of the extruder is controlled to be 260-290 ℃, and the rotating speed of the extruder is 300-450 rmp, so that the PET modified material pellet semi-finished product is prepared.

27. The process according to any one of claims 20 to 26, wherein the pellet semi-finished PET-modified material has a viscosity of greater than 0.5dl/g.

28. The process according to claim 27, wherein the pellet semi-finished PET-modified material has a viscosity greater than 0.65dl/g.

29. The method of any one of claims 20 to 26, wherein the PET-modified material has a viscosity of greater than 0.65dl/g.

30. The method of claim 29, wherein the PET-modified material has a viscosity greater than 0.85dl/g.

31. Use of the PET-modified material according to any one of claims 1 to 16 or the PET-modified material prepared by the preparation method according to any one of claims 17 to 30, for automobiles.