Halogen-free flame-retardant reinforced polyester composite material with high hydrolysis resistance

Abstract

The present application relates to a kind of halogen-free flame-retardant reinforced polyester composite with high hydrolysis resistance.The hydrolysis-resistant halogen-free flame-retardant reinforced polyester composite of the present application includes polyester resin, alkali-free glass fiber, halogen-free flame retardant, hydrolysis-resistant agent, buffer, antioxidant and lubricant, wherein the alkali-free glass fiber can improve the mechanical strength and impact resistance of the material, the synergistic effect between the hydrolysis-resistant halogen-free flame retardant, hydrolysis-resistant agent and buffer is used to obtain a polyester composition composite with high hydrolysis resistance, the flame retardancy has UL-94 standard 0.4mm V-0 level, and the tensile strength has a retention rate of 70% after storage in 85℃ / 85%RH environment for 2000h.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials, specifically relating to a halogen-free flame-retardant reinforced polyester composite material with high hydrolysis resistance. Background Technology

[0002] Polyester resin is a general term for high molecular weight compounds formed by the condensation polymerization of diols, diacids, or polyols and polyacids. Polyesters represented by polyethylene terephthalate (PET), polypropylene terephthalate (PTT), and polybutylene terephthalate (PBT) have excellent properties and are widely used in packaging, electronics, medical and health, construction, automobile and other fields.

[0003] However, polyester materials generally have a drawback: they are prone to hydrolysis. This leads to a significant reduction in the service life and overall performance of polyester products. Polyester molecules contain numerous ester bonds and terminal carboxyl groups. Under the influence of these terminal carboxyl groups, ester bonds are easily eroded by water or moisture, especially in high-temperature and high-humidity environments. Ester bonds readily react with water, causing molecular chain breakage and a decrease in molecular weight. Therefore, there are two main factors leading to polyester hydrolysis: water molecules and terminal carboxyl groups. Thus, reducing the water absorption rate (moisture content) and terminal carboxyl group content of polyester can effectively enhance its hydrolysis resistance. Currently, the commonly used method is to add carbodiimide-based anti-hydrolysis agents or resins containing epoxy groups to consume the terminal carboxyl groups in the polyester, inhibiting the hydrolysis reaction and thereby improving the overall performance and service life of the polyester.

[0004] For example, Chinese invention patent application number 102838850B discloses a method for preparing hydrolysis-resistant PBT resin, whose composition is: PBT 96%, polycarbodiimide 3%, and antioxidant 1%. The -NCO groups in polycarbodiimide can react with the terminal carboxyl groups in PBT resin, thereby improving hydrolysis resistance. Chinese invention patent application number 104583290A discloses a method for preparing a melt-stable and hydrolysis-resistant polyester composition, whose composition is: polyester resin 40-89%, glass fiber 10-50%, hydroxyapatite 0.5-5%, epoxy resin 0.5-4%, and toughening agent 0.5-15%. The compositions obtained in these patents exhibit excellent hydrolysis resistance and maintain stable melt viscosity. Chinese invention patent application number 106832810A discloses a hydrolysis-resistant polyester and its preparation method, the composition of which is: 30-99% polyester resin and 1-70% boehmite (γ-AlOOH). This invention does not use carbodiimide additives, is safe and environmentally friendly, exhibits excellent hydrolysis resistance, and can still maintain good mechanical properties after aging.

[0005] However, research on the hydrolysis resistance of flame-retardant reinforced polyester resins is currently limited. Typically, the introduction of flame retardants degrades the hydrolysis resistance of polyester resins, and traditional methods of improving hydrolysis resistance by adding carbodiimide and epoxy materials have little effect on flame-retardant systems. Therefore, the method of this invention for improving the hydrolysis resistance of flame-retardant reinforced polyester systems has high application value. Summary of the Invention

[0006] The purpose of this invention is to address the problems existing in the prior art by providing a halogen-free flame-retardant reinforced polyester composite material with high hydrolysis resistance.

[0007] The hydrolysis-resistant, halogen-free, flame-retardant, reinforced polyester composite material of the present invention comprises polyester resin, alkali-free glass fiber, halogen-free flame retardant, anti-hydrolysis agent, buffer, antioxidant, and lubricant. The alkali-free glass fiber improves the mechanical strength and impact resistance of the material, achieving a tensile strength of ≥105 MPa and a notched impact strength ≥7 kJ / m. 2 In flame-retardant systems, a single anti-hydrolysis agent offers limited improvement in hydrolysis resistance. While this invention utilizes epoxy resin or carbodiimide-type anti-hydrolysis agents to enhance hydrolysis resistance, the addition of reactive anti-hydrolysis agents increases melt viscosity, severely impacting flowability and hindering subsequent processing. In contrast, the addition of a buffer can adsorb acidic substances, maintaining the material's pH near neutral and reducing the rate of acidic hydrolysis. Furthermore, it addresses the increased melt viscosity caused by the addition of anti-hydrolysis agents, while simultaneously stabilizing melt viscosity and imparting stable processing properties to the material.

[0008] By combining the effects of hydrolysis-resistant halogen-free flame retardants, anti-hydrolysis agents, and buffers, a polyester composite material with high hydrolysis resistance is obtained. The flame retardancy meets the UL-94 standard 0.4mm V-0 rating, and the tensile strength retains 70% after being stored in an environment of 85°C / 85%RH for 2000 hours.

[0009] The objective of this invention can be achieved through the following methods:

[0010] This invention provides a halogen-free flame-retardant reinforced polyester composite material with high hydrolysis resistance, wherein the halogen-free flame-retardant reinforced polyester composite material comprises the following components in parts by weight:

[0011]

[0012] The polyester resin includes one of polyethylene terephthalate (PET), polypropylene terephthalate (PTT), and polybutylene terephthalate (PBT), with PBT being preferred. The terminal carboxyl group content of the polyester resin is less than 30 mol / t, preferably less than 20 mol / t, and more preferably less than 15 mol / t. The polyester resin is prepared by direct esterification.

[0013] The halogen-free flame retardant is a phosphorus-nitrogen-based flame retardant, prepared by compounding melamine polyphosphate and alkyl phosphinate, with a mass ratio of melamine polyphosphate to alkyl phosphinate of 2-2.5:1. The alkyl phosphinate includes one or more of methyl ethyl aluminum hypophosphite, diethyl aluminum hypophosphite, dipropyl aluminum hypophosphite, and isobutyl aluminum hypophosphite; preferably dipropyl aluminum hypophosphite, more preferably diethyl aluminum hypophosphite. The flame retardant used in this invention is a high-purity, low-ion-release phosphorus-nitrogen-based halogen-free flame retardant, which can reduce the decomposition and precipitation of acidic substances during the damp-heat aging process.

[0014] The glass fiber is an alkali-free, hydrolysis-resistant glass fiber that has been surface-treated with a coupling agent, with a preferred diameter of 11-15 μm and a preferred quantity of 15-30 parts; the coupling agent includes one or more of aminosilane, epoxysilane, methacryloxysilane, and monoalkoxytitanate coupling agents.

[0015] The anti-hydrolysis agent comprises one or more of epoxy resins containing epoxy groups and carbodiimides, preferably 0.4 to 1 part. The epoxy component of the epoxy resin containing epoxy groups is preferably a bisphenol epoxy condensate, more preferably a glycidyl ether, and even more preferably a glycidyl ether of a phenolic compound; the carbodiimide comprises one or more of dicyclohexylcarbodiimide, N,N'-diisopropylcarbodiimide, and (1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, preferably dicyclohexylcarbodiimide, more preferably N,N'-diisopropylcarbodiimide, and even more preferably (1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride), and polymeric carbodiimides are preferred over monomeric carbodiimides. The anti-hydrolysis auxiliaries used in this invention are a class of organic compounds that can react with the terminal carboxyl groups of polyester resins.

[0016] The buffer comprises an amphoteric compound and a melt stabilizer (acid absorber) in a mass ratio of 1-2:1. The amphoteric compound comprises one or more of hydroxides and stearates; the stabilizer (acid absorber) is hydrotalcite.

[0017] Hydroxides include one or more of aluminum hydroxide and magnesium hydroxide; stearates include one or more of zinc stearate, magnesium stearate, and calcium stearate; hydrotalcites include one or more of magnesium aluminum hydrotalcite and calcium aluminum hydrotalcite.

[0018] The buffers used in this invention are a class of amphoteric compounds and acid adsorbents capable of adsorbing small acidic molecules. These buffers also stabilize the melt viscosity and adjust the processability of the material. The ability of the buffer to adjust acidity and alkalinity significantly affects the hydrolysis resistance of the material. Among the selected buffers, hydrotalcite primarily provides melt viscosity stability and can also adsorb acidic substances, preventing them from participating in the hydrolysis process. Amphoteric hydroxides can react with acidic and alkaline substances, mainly providing stability in the acidity and alkalinity of the material. Adding only a single component cannot simultaneously achieve melt stability and acid-base stability. The hydrolysis resistance and the effect of the buffer on improving the hydrolysis resistance of the material are relatively small when added in small amounts; significant improvements in hydrolysis resistance only occur at certain concentrations. Especially with epoxy-based hydrolysis stabilizers, the reaction of polyepoxy functional groups with terminal carboxyl groups leads to chain extension and cross-linking, resulting in poor flowability. The melt stabilizer then plays a role in preventing further reduction in flowability.

[0019] The buffer has a preferred particle size of 5-10 μm, more preferably 3-5 μm, and most preferably 2-3 μm. Particle size affects its dispersion in the matrix, and the presence of some metal ions can degrade the acid-base balance (metal ions, such as sodium ions, are present in aluminum hydroxide and magnesium hydroxide). Therefore, in the buffer, the preferred sodium ion content (purity) is <50 ppm, more preferably <20 ppm, and most preferably <10 ppm.

[0020] The surface of the buffer is treated with a coupling agent, which includes one or more of aminosilanes, epoxysilanes, methacryloxysilanes, and monoalkoxytitanate coupling agents. For this buffer, it is necessary to consider the comprehensive performance requirements of various indicators and achieve optimal effect under a certain ratio.

[0021] The antioxidant is preferably a mixture of hindered phenolic antioxidants and phosphite antioxidants in a mass ratio of 1-1.5:1. The preferred phosphite antioxidant is pentaerythritol di(2,4-di-tert-butylphenyl) bisphosphite; the preferred hindered phenolic antioxidant is pentaerythritol ester.

[0022] The lubricant is preferably one or more of silicone powder, N,N'-ethylene bis-stearamide, and pentaerythritol stearate.

[0023] This invention also provides a method for preparing a halogen-free flame-retardant reinforced polyester composite material with high hydrolysis resistance, comprising the following steps:

[0024] (1) Prepare the components according to the following weight proportions:

[0025]

[0026] (2) Mix the components in step (1) thoroughly and extrude them into granules to obtain the halogen-free flame-retardant reinforced polyester composite material.

[0027] In step (2), the screw extruder for granulation rotates at 300–500 rpm and the temperature is 270–290°C. Each component is added to a high-speed mixer according to the above weight percentages, and then placed in the screw extruder to obtain a highly hydrolysis-resistant, halogen-free, flame-retardant reinforced polyester composite material.

[0028] The high hydrolysis resistance of the halogen-free flame-retardant reinforced polyester composite material of this invention is mainly achieved through the combined action of the halogen-free flame retardant, the anti-hydrolysis agent, and the buffer. Traditional halogen-free flame retardants contain a large number of metallic impurities and components that are acidic themselves or after decomposition, which greatly reduces the hydrolysis resistance of the material. In this invention, a high-purity, low-ion-emission phosphorus-nitrogen-based halogen-free flame retardant is used, which can reduce the decomposition and precipitation of acidic substances during the damp heat aging process. The anti-hydrolysis agent uses a traditional carbodiimide-type anti-hydrolysis agent to end-carboxyl groups of the polyester resin. However, carbodiimide end-capping to improve hydrolysis resistance has a drawback: end-capping can only end-carboxyl groups of the polyester resin and cannot end-cap small molecules that exhibit acidity produced by the decomposition of other components in the material. As a result, the acidity of the material itself cannot be controlled, thus deteriorating the hydrolysis resistance. Therefore, a third component, a buffer, needs to be added. Polyester resin has better hydrolytic stability under weakly alkaline conditions than under acidic conditions. Therefore, the role of the buffer is to adjust the environmental acidity and alkalinity of the matrix polyester resin, making it tend to be between neutral and weakly alkaline, and to adsorb the acidic small molecules produced by decomposition, thereby reducing the hydrolysis rate of the polyester resin and improving the hydrolysis resistance of the material.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1) Compared to existing hydrolysis-resistant polyester resin materials, which commonly use single carbodiimide or epoxy resins to improve the hydrolysis resistance of polyester resins, in flame-retardant reinforced polyester resin systems, the method of using a single water-resistant agent cannot effectively improve the hydrolysis resistance of polyester resins. Furthermore, adding too much water-resistant agent has a deteriorating effect on the physical properties of the composite material and will seriously affect the processing performance of the material. This invention addresses the hydrolysis resistance problem of polyester resins by synergistically considering both the terminal carboxyl groups of the polyester resin and the melt pH value.

[0031] 2) Because a certain amount of inorganic materials with acid-base adjustment properties are added to the system, the hydrolysis resistance of the material is improved without reducing the various properties of the material. Moreover, thanks to the acid-base adjustment effect, the amount of anti-hydrolysis agent added to the system can be reduced, thereby reducing costs and improving the processability of the material to a certain extent.

[0032] 3) Furthermore, the addition of anti-hydrolysis agents will cause a sharp increase in the melt viscosity of the matrix material and a decrease in fluidity, thereby affecting the subsequent processability of the material. The addition of buffers not only adjusts the acidity and alkalinity of the matrix material, but also has a beneficial effect on the stability of melt viscosity, giving the material better processing performance.

[0033] 4) The preparation process of this invention is simple and does not require precise control of temperature, rotation speed and other parameters during the production process to obtain polyester resin materials with stable performance. During the production process, no toxic or harmful gases are generated, which does not pollute the environment and has a wide range of applications. The buffer and anti-hydrolysis agent can stably improve the hydrolysis resistance of the material and have a high tolerance for other components and contents in the formula without strict limitations. Detailed Implementation

[0034] The present invention will now be described in detail with reference to specific embodiments. The following examples are implemented under the premise of the technical solution of the present invention, providing detailed implementation methods and specific operating procedures, which will help those skilled in the art to further understand the present invention. It should be noted that the scope of protection of the present invention is not limited to the following embodiments; any adjustments and improvements made under the concept of the present invention are all within the scope of protection of the present invention.

[0035] In the embodiments and comparative examples of this invention, the material compositions in Tables 1 and 2 are as follows:

[0036] PBT: Purchased from Yizheng Chemical Fiber Company, grade GL236, intrinsic viscosity 1.280±0.030 dl / g; terminal carboxyl group content less than 27 mol / t;

[0037] Flame retardant: Purchased from Zhejiang Xusen, a halogen-free flame retardant with phosphorus and nitrogen as flame retardant elements, with a mass ratio of melamine polyphosphate and aluminum diethylphosphinate of 2:1;

[0038] Fiberglass: Purchased from Jushi Co., Ltd., grade ECS13-03-534A, diameter 13μm;

[0039] Anti-hydrolysis agents: carbodiimide was purchased from LANXESS, brand name P400; epoxy resin was purchased from Nan Ya, brand name NPES-907.

[0040] Buffers: hydrotalcite (<200nm), purchased from Chenghe Technology, brand name AC-320; zinc stearate (1-2μm), purchased from FACI, brand name ZS-TM;

[0041] Antioxidant: It is a mixture of hindered phenolic and phosphite antioxidants IRGANOX 1010 and IRGAFOS168 in a weight ratio of 1:1;

[0042] Lubricant: Pentaerythritol stearate, German Corning PETS LOXIOL P 861 / 3.5.

[0043] Examples 1-7

[0044] A halogen-free flame-retardant reinforced polyester composite material with high hydrolysis resistance and its preparation method, the method comprising the following steps:

[0045] According to the weight percentage of the ingredients in Table 1, add the raw materials to a high-speed mixer and mix thoroughly. Then place the mixture in a screw extruder, control the screw speed at 400 rpm and the temperature at 280℃, and extrude and granulate to obtain the product.

[0046] Examples 1-7 are products of compound CTI synergist and polyolefin, Examples 1-3 are used to determine the optimal ratio of CTI synergist and polyolefin, and Examples 4-7 are material formulations with different glass fiber contents.

[0047] Explanation of the compilation of Table 1:

[0048] Examples 1-3 are used to demonstrate that carbodiimide and buffering agents work together to improve the hydrolysis resistance of materials. However, the amount added needs to reach a certain threshold, and the overall effect is optimal when 0.5 parts and 5 parts are added respectively.

[0049] Examples 6 and 7 demonstrate that epoxy resin combined with a buffer can also achieve high hydrolysis resistance, with 1 part and 5 parts being optimal.

[0050] Examples 6 and 7 demonstrate that the compound system of anti-hydrolysis agent and buffer can be used in 15-40 parts of glass fiber reinforced PBT composite material system and can stably obtain high hydrolysis resistance.

[0051] Table 1 - Formula

[0052]

[0053]

[0054] Comparative Examples 1-9

[0055] A halogen-free flame-retardant reinforced polyester composite material with high hydrolysis resistance has the composition shown in Table 2, and its preparation method is the same as that in the examples.

[0056] Comparative Examples 1-9 are used to demonstrate that for flame-retardant reinforced PBT materials, neither a single anti-hydrolysis agent nor a buffer can effectively improve the hydrolysis resistance of the material, even if the anti-hydrolysis content is increased to 1%.

[0057] Table 2 - Formula

[0058]

[0059]

[0060] Performance testing:

[0061] Tables 3 and 4 show the performance test results, with specific items as follows:

[0062] Table 3. Test results of Comparative Examples 1-9

[0063]

[0064] Table 4 Test Results of Examples 1-7

[0065]

[0066]

[0067] The performance testing standards are as follows:

[0068] Charpy notched impact strength: tested according to ISO 179-1:2010 standard;

[0069] Tensile strength: Tested according to ISO 527-1:2019 standard;

[0070] MI: Tested according to ISO 1133-1:2011 standard;

[0071] Flame retardancy test: Tested according to UL-94 standard;

[0072] Tensile strength and retention rate under damp heat aging: Tested according to GB / T 2573-2008 standard. After the test, the test specimens were stored at room temperature for 24 hours and then tested according to the tensile test standard. Damp heat aging conditions: temperature 85℃, humidity 85%RH, time 2000 hours;

[0073] Tensile strength and retention rate under high-pressure steam test: Tested according to JEDEC JESD22-A102 standard. After the test, the test specimens were stored at room temperature for 24 hours and then tested according to the tensile test standard. High-pressure steam test conditions: temperature 121℃, humidity 100%RH, pressure 2atm, time 96 hours;

[0074] Analysis of the test results shows that, in Comparative Example 1, without any added anti-hydrolysis agent, the extremely poor hydrolysis resistance of PBT resulted in a tensile strength retention rate of only 32% after 2000 hours of damp heat aging. This severe performance degradation makes it unsuitable for applications in harsh damp heat environments. Comparative Examples 2 and 3, with the addition of 0.1%-0.5% carbodiimide-based anti-hydrolysis agents, showed no significant improvement in tensile strength retention after damp heat aging. Similarly, Comparative Examples 4 and 5, with the addition of 0.5%-1% epoxy resin, also showed no significant improvement in hydrolysis resistance. This indicates that for halogen-free flame-retardant PBT systems, simply adding a single anti-hydrolysis component is insufficient to effectively improve the material's hydrolysis resistance. Comparative Examples 6 and 7, with the addition of 1%-5% buffers, also exhibited low tensile strength retention rates, demonstrating that buffers do not effectively reduce the acidic hydrolysis process of PBT; they only serve to adjust the pH. To achieve hydrolysis resistance, it is necessary to use them in combination with other types of anti-hydrolysis agents.

[0075] Examples 1 and 2 verified that even though the combined action of anti-hydrolysis agent and buffer can produce a higher improvement in hydrolysis resistance, low amounts of anti-hydrolysis agent still cannot significantly improve hydrolysis resistance. The hydrolysis resistance is significantly improved only when the content of carbodiimide anti-hydrolysis agent reaches 0.5%. Examples 2 and 3 verified that when the buffer content is 5% and the carbodiimide anti-hydrolysis agent content is 0.5%, the hydrolysis resistance of the material is optimal, and the tensile strength retention rate reaches 59%. This shows that the buffer needs to be at a certain content to more effectively maintain the acid-base balance of the matrix material, thereby improving the hydrolytic stability of the material.

[0076] Examples 4 and 5 verified that epoxy resins and buffers can both stably improve the hydrolysis resistance of materials. When 1% epoxy resin and 5% buffer were added, the tensile strength retention rate of the composition reached 53%; compared with comparative examples 4 and 5, this was an increase of 8% and 7%, respectively, indicating that the addition of the buffer, in synergy with the anti-hydrolysis agent, improved the hydrolysis resistance of the composition.

[0077] Examples 6 and 7 verified that, with a glass fiber content between 15% and 40%, the addition of epoxy resin-based anti-hydrolysis agents and buffers can still yield PBT halogen-free flame-retardant reinforced materials with consistently improved hydrolysis resistance. This demonstrates the stable synergistic effect between the anti-hydrolysis agent and the buffer, which can be applied to a wider range of systems.

[0078] By comparing Comparative Examples 3 and 5, and Examples 3 and 5, it can be determined that the anti-hydrolysis agent and buffer can effectively improve the hydrolysis resistance of PBT halogen-free flame-retardant reinforced materials. When 0.5% carbodiimide and 5% buffer, 1% epoxy resin and 5% buffer are added, tensile strength retention rates of 59% and 53% can be obtained, as well as other excellent comprehensive properties. This demonstrates a simple and effective method for preparing halogen-free flame-retardant reinforced PBT composite materials with high hydrolysis resistance.

[0079] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A halogen-free flame-retardant reinforced polyester composite material with high hydrolysis resistance, characterized in that, The halogen-free flame-retardant reinforced polyester composite material comprises the following components in parts by weight: 48.5~58.5 parts of polyester resin, 15-20 parts of halogen-free flame retardant 15-25 parts fiberglass Anti-hydrolysis agent 0.5~1 part, 5 parts buffer Antioxidant 0.1~0.5 parts, Lubricant 0.1~0.5 parts; The polyester resin includes one of polyethylene terephthalate, polypropylene terephthalate, and polybutylene terephthalate. When the anti-hydrolysis agent is epoxy resin, the amount of anti-hydrolysis agent is 1 part; when the anti-hydrolysis agent is carbodiimide, the amount of anti-hydrolysis agent is 0.5 parts. The buffer comprises an amphoteric compound and a melt stabilizer in a mass ratio of 1-2:1; The amphoteric compound includes one or more of hydroxides and stearates; the hydroxide includes one or more of aluminum hydroxide and magnesium hydroxide; the stearate includes one or more of zinc stearate, magnesium stearate, and calcium stearate. The melt stabilizer is hydrotalcite; hydrotalcite includes one or more of magnesium aluminum hydrotalcite and calcium aluminum hydrotalcite.

2. The halogen-free flame-retardant reinforced polyester composite material according to claim 1, characterized in that, The halogen-free flame retardant is a combination of phosphorus and nitrogen-based flame retardants, including melamine polyphosphate and alkyl phosphonates.

3. The halogen-free flame-retardant reinforced polyester composite material according to claim 1, characterized in that, The glass fiber is alkali-free and hydrolysis-resistant, with a diameter of 11-15 μm.

4. The halogen-free flame-retardant reinforced polyester composite material according to claim 1, characterized in that, The antioxidants include hindered phenolic antioxidants and phosphite antioxidants; the lubricants include one or more of silicone powder, methyl bis-stearamide, and N,N'-ethylene bis-stearamide.

5. A method for preparing the halogen-free flame-retardant reinforced polyester composite material as described in claim 1, characterized in that, Includes the following steps: (1) Prepare the components according to the following weight proportions: 48.5~58.5 parts of polyester resin, 15-20 parts flame retardant 15-25 parts fiberglass Anti-hydrolysis agent 0.5~1 part, 5 parts buffer Antioxidant 0.1~0.5 parts, Lubricant 0.1~0.5 parts; (2) Mix all the components in step (1) thoroughly, and then extrude and granulate to obtain the halogen-free flame-retardant reinforced polyester composite material.

6. The preparation method according to claim 5, characterized in that, In step (2), the screw speed of the extrusion granulation is 300~500 rpm and the temperature is 270~290℃.

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