PBT composite material, and preparation method therefor and use thereof

Abstract

The present invention belongs to the technical field of polymer engineering plastics. Disclosed are a PBT composite material, and a preparation method therefor and the use thereof. The PBT composite material provided by the present invention comprises the following components in parts by mass: 30-60 parts of a PBT resin, 25-40 parts of alkali-free glass fibers, 12-20 parts of aluminum diethyl hypophosphite, 2-8 parts of melamine polyphosphate, and 1-4 parts of a phosphate. When the PBT composite material provided by the present invention is prepared into a thin-wall (≤0.4 mm) product, the PBT composite material still has a good flame retardant property, and the obtained product has good fluidity, and also has good tensile strength and impact strength; and the preparation method provided by the present invention is simple, and is beneficial to actual production.

Description

A PBT composite material and its preparation method and application Technical Field

[0001] The present invention belongs to the technical field of polymer engineering plastics, and in particular relates to a PBT (Polybutylene terephthalate) composite material and a preparation method and application thereof. Background Art

[0002] Brominated flame retardants have the advantages of high flame retardant efficiency, good flame retardant stability, good compatibility, and excellent mechanical properties. However, halogen flame retardants pose a great threat to the environment and humans. Compared with the current halogen flame retardant system, the halogen-free flame retardant system has obvious advantages in density, smoke density, toxicity, CTI (Comparative Tracking Index), etc. Therefore, halogen-free flame retardants will be the major trend of future development. In addition, with the continuous development of material technology, market products have shown another development trend, namely miniaturization and thin-walling. The advantages of thin-walling are obvious, but at the same time, there are also many molding problems that restrict its development. In recent years, various new molding processes and the maturity of mold flow analysis technology have greatly promoted the application of thin-wall products. More and more customers have put forward the requirements of miniaturization and thin-walling (≤0.4mm), and the market capacity is very huge.

[0003] Numerous research results have been published on halogen-free flame-retardant reinforced PBT. Generally speaking, halogen-free flame retardants are less effective than their halogenated counterparts, requiring a higher dosage to achieve the same flame retardancy. Halogen-free flame retardants also have poor compatibility with resins and larger particle sizes, significantly reducing mechanical properties and fluidity. These two key technical indicators are crucial for thin-wall technology. Excellent performance ensures sufficient strength for thin-wall products, while high fluidity ensures smooth molding. The thinnest flame retardant rating reported for halogen-free systems is 0.8mm V-0. Chinese patent CN108676330A uses a compound of melamine cyanurate (MCA) and aluminum hypophosphite to achieve a 0.8mm V-0 flame-retardant PBT product. However, aluminum hypophosphite itself has poor thermal stability and easily releases phosphine during processing. Phosphine is highly harmful to the human body and poses a risk of ignition, making it unsuitable for flame retardancy in ultra-thin halogen-free systems. Mainstream halogen-free flame retardants on the market, such as Clariant's Exolit OP1230, have aluminum diethylphosphinate as their core ingredient. Diethylphosphinate protection offers excellent thermal stability and synergistic flame retardancy with melamine polyphosphate (MPP). Compounding can achieve a higher flame retardant rating (0.8mm). However, increasing the flame retardant dosage significantly impairs flowability, resulting in uneven dispersion, unstable flame retardancy, and poor performance. Current halogen-free flame retardant technologies cannot achieve both ultra-thin flame retardancy (≤0.4mm) and high flowability and performance.

[0004] Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a PBT composite material that still has good flame retardant properties in an ultra-thin state (≤0.4mm) and has good fluidity and mechanical properties, as well as a preparation method and application thereof.

[0006] To achieve the above objectives, in a first aspect of the present invention, the present invention provides a PBT composite material, comprising the following components in parts by mass: 30-60 parts of PBT resin, 25-40 parts of alkali-free glass fiber, 12-20 parts of diethyl aluminum hypophosphite, 2-8 parts of melamine polyphosphate, and 1-4 parts of phosphate ester.

[0007] The present invention provides a PBT composite material in which diethylaluminum hypophosphite, melamine polyphosphate (MPP) and phosphate ester are simultaneously added to a PBT resin matrix in a specific mass range and can be compounded with each other, and a certain amount of alkali-free glass fiber is added as an auxiliary. The obtained composite material still has excellent flame retardant properties when prepared into a thin-walled (≤0.4mm) product, and the product obtained in the thin-walled state has excellent fluidity, good tensile strength and impact strength.

[0008] Preferably, in the PBT composite material, the mass percentage of PBT resin is between 38-45%, the mass percentage of diethylaluminum hypophosphite is between 10-20%, the mass percentage of melamine polyphosphate is between 1.5-8%, and the mass percentage of phosphate ester is between 0.5-5%.

[0009] As a preferred embodiment of the PBT composite material of the present invention, in the PBT composite material, the mass ratio of diethyl aluminum hypophosphite, melamine polyphosphate and phosphate is diethyl aluminum hypophosphite: melamine polyphosphate: phosphate = (14-16): (4-6): (2-3).

[0010] The inventors have found that when diethyl aluminum hypophosphite, melamine polyphosphate and phosphate are further selected within the above-mentioned mass ratio range, the compounding effect between the three is better and the overall performance of the obtained product is better.

[0011] As a preferred embodiment of the PBT composite material of the present invention, at least one of the following (a) to (d) is satisfied:

[0012] (a) The glass fiber is an alkali-free glass fiber treated with a coupling agent and has a diameter of 5-20 μm;

[0013] (b) the average particle size of the diethyl aluminum hypophosphite is 8-42 μm;

[0014] (c) the average particle size of the melamine polyphosphate is 7-10 μm;

[0015] (d) The intrinsic viscosity of the PBT resin is 0.6-1.15 dL / g.

[0016] Illustratively, the diameter of the glass fiber may be 5.0 μm, 5.5 μm, 6.0 μm, 6.5 μm, 7.0 μm, 7.5 μm, 8.0 μm, 8.5 μm, 9.0 μm, 9.5 μm, 10.0 μm, 10.5 μm, 11 μm, 11.5 μm, 12 μm, 12.5 μm, 13 μm, 13.5 μm, 14 μm, 14.5 μm, 15 μm, 15.5 μm, 16 μm, 16.5 μm, 17 μm, 17.5 μm, 18 μm, 18.5 μm, 19 μm, 19.5 μm, 20 μm, etc., as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0017] For example, the average particle size of the diethyl aluminum hypophosphite may be 8 μm, 8.5 μm, 9 μm, 9.5 μm, 10 μm, 10.5 μm, 11 μm, 11.5 μm, 12 μm, 12.5 μm, 13 μm, 13.5 μm, 14 μm, 14.5 μm, 15 μm, 15.5 μm, 16 μm, 16.5 μm, 17 μm, 17.5 μm, 18 μm, 18.5 μm, 19 μm, 19.5 μm, 20 μm, 20.5 μm, 21 μm, 21.5 μm, 22 μm, 22.5 μm, 23 μm, 23.5 μm, 24 μm, 24.5 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 30 μm, 31 μm, 32 μm, 33 μm, 34 μm, 35 μm, 36 μm, 37 μm, 38 μm, 39 μm, 40 μm, 41 μm, 42 μm, 43 μm, 44 μm, 45 μm, 46 μm, 47 μm, 48 μm, 49 μm, 50 μm, 51 μm, 52 μm, 53 μm, 54 μm, 55 μm, 56 μm, 57 μm, 58 μm, 59 μm, 60 μm, 61 μm, 62 μm, 63 μm, 64 μm, 65 μm, 66 μm, 67 μm, 5μm, 26μm, 26.5μm, 27μm, 27.5μm, 28μm, 28.5μm, 29μm, 29.5μm, 30μm, 30.5μm, 31μm, 31.5μm, 32μm, 32.5μm, 33μm, 33.5μm, 34μm, 34.5μm, 35μm, 35.5μm, 36μm, 36.5μm, 37μm, 37.5μm, 38μm, 38.5μm, 39μm, 39.5μm, 40μm, etc., as well as specific point values ​​between the above point values, due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the said range.

[0018] Illustratively, the average particle size of the melamine polyphosphate may be 7.0 μm, 7.2 μm, 7.4 μm, 7.6 μm, 7.8 μm, 8.0 μm, 8.2 μm, 8.4 μm, 8.6 μm, 8.8 μm, 9.0 μm, 9.2 μm, 9.4 μm, 9.6 μm, 9.8 μm, 10.0 μm, etc., as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0019] For example, the intrinsic viscosity of the PBT resin may be 0.6 dL / g, 0.62 dL / g, 0.65 dL / g, 0.67 dL / g, 0.7 dL / g, 0.72 dL / g, 0.75 dL / g, 0.77 dL / g, 0.8 dL / g, 0.82 dL / g, 0.85 dL / g, 0.87 dL / g, 0.9 dL / g, 0.92 dL / g, g, 0.95 dL / g, 0.97 dL / g, 1.0 dL / g, 1.02 dL / g, 1.04 dL / g, 1.06 dL / g, 1.08 dL / g, 1.10 dL / g, 1.12 dL / g, 1.15 dL / g, etc., as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively enumerates the specific point values ​​included in the said range.

[0020] Preferably, the diameter of the glass fiber is 7-17 μm, and more preferably, the diameter of the glass fiber is 10-13 μm.

[0021] Preferably, the average particle size of the diethyl aluminum hypophosphite is 10-40 μm, and more preferably, the average particle size of the diethyl aluminum hypophosphite is 20-30 μm.

[0022] Preferably, the average particle size of the melamine polyphosphate is 8-10 μm.

[0023] The inventors have found that when the average particle sizes of diethyl aluminum hypophosphite and melamine polyphosphate are further selected to be 20-30 μm and 8-10 μm, respectively, and the diameter of the alkali-free glass fiber is selected to be 10-13 μm, the flame retardant properties of the obtained product are better, and the fluidity and mechanical properties of the obtained product are also better.

[0024] Preferably, the intrinsic viscosity of the PBT resin is 0.67-1.05 dL / g, and more preferably, the intrinsic viscosity of the PBT resin is 0.7-1.00 dL / g.

[0025] The intrinsic viscosity of PBT resin is determined with reference to GB / T 14190-2017.

[0026] The inventors have found that when the intrinsic viscosity of the PBT resin is further selected to be 0.7-1.0 dL / g, the added diethyl aluminum hypophosphite, melamine polyphosphate and phosphate ester can be better dispersed in the resin matrix, thereby achieving a better overall effect.

[0027] Preferably, the coupling agent is at least one of an epoxy-terminated silane coupling agent and an amino-terminated silane coupling agent.

[0028] As a preferred embodiment of the PBT composite material of the present invention, the phosphate ester is at least one of triphenyl phosphate (TPP), polyaryl phosphate (PX-220), resorcinol-bis(diphenyl phosphate) condensation product (SOL-DP), bisphenol A-bisdiphenyl phosphate (BDP), resorcinol-bis[di(2,6-dimethylphenyl) phosphate] (RDX), resorcinol-bisdiphenyl phosphate (RDP), and phenoxy cyclophosphazene.

[0029] Preferably, the phosphate ester is resorcinol-bisdiphenyl phosphate (RDP).

[0030] As a preferred embodiment of the PBT composite material of the present invention, the PBT composite material further comprises 0.001-4 parts of a toughening agent and 0.001-1 part of a processing aid.

[0031] As a preferred embodiment of the PBT composite material of the present invention, the toughening agent is at least one of ethylene-acrylate-glycidyl methacrylate terpolymer, ethylene-acrylate binary copolymer, ethylene-vinyl acetate, and glycidyl methacrylate grafted ethylene-octene copolymer.

[0032] As a preferred embodiment of the PBT composite material of the present invention, the processing aid includes at least one of an antioxidant and a lubricant.

[0033] Preferably, the lubricant is at least one of aliphatic carboxylic acid ester and polyolefin wax; and the antioxidant is a hindered phenol antioxidant.

[0034] In the second aspect of the present invention, the present invention also provides a method for preparing the PBT composite material, which comprises the following steps: weighing the dried raw materials, mixing them, and feeding them into a twin-screw extruder, extruding, drawing, cooling, pelletizing, and drying to obtain the PBT composite material.

[0035] As a preferred embodiment of the preparation method of the present invention, the drying process of the PBT resin is: drying the PBT resin at 125-135° C. for 4-6 hours until the moisture content is less than 0.03%.

[0036] As a preferred embodiment of the preparation method of the present invention, the parameters of the twin-screw extruder are: a feeding rate of 450-800 kg / hour; the temperatures of each section of the screw from the feeding port to the die are 220-230°C, 230-240°C, 230-240°C, 240-250°C, 250-260°C, 240-250°C, 240-250°C, 230-240°C, and 220-230°C; and the screw speed is 250-400 rpm.

[0037] In the third aspect of the present invention, the present invention further provides application of the PBT composite material in ultra-thin (≤0.4 mm) electronic components.

[0038] For example, PBT composite materials are used in cooling fans, relays, and capacitors.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The present invention provides a PBT composite material which uses PBT resin as a matrix, is compounded with diethyl aluminum hypophosphite, melamine polyphosphate and phosphate in a specific mass range, and a certain amount of alkali-free glass fiber. The obtained composite material still has excellent flame retardant properties when prepared into a thin-walled (≤0.4 mm) product, that is, the composite material provided by the present invention can achieve an ultra-high-level flame retardant effect when a small amount of flame retardant is added; and the obtained product has excellent fluidity and good tensile strength and impact strength; specifically, when the obtained product is prepared into a test sample at 0.4 mm, the flame retardant grade of the sample is V-0 or V-1, the average burning time is within 7.5 s, the maximum burning time is within 15.6 s, the tensile strength is above 105 MPa, and the impact strength is above 7.2 kJ / m 2 The melt index is above 8.9; and the preparation method of the composite material provided by the present invention is simple, which is conducive to actual production. DETAILED DESCRIPTION

[0041] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0042] Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0043] PBT-1: GX111, intrinsic viscosity 0.73 dL / g, Yizheng, Jiangsu;

[0044] PBT-2: GX121, intrinsic viscosity 0.98 dL / g, Yizheng, Jiangsu;

[0045] PBT-3: GX110, intrinsic viscosity 0.67 dL / g, Yizheng, Jiangsu;

[0046] PBT-4: GX122J, intrinsic viscosity 1.05 dL / g, Yizheng, Jiangsu;

[0047] Diethylaluminum hypophosphite 1: average particle size 20 μm, Clariant, Switzerland;

[0048] Diethylaluminum hypophosphite 2: average particle size 30 μm, Clariant, Switzerland;

[0049] Diethylaluminum hypophosphite 3: average particle size 10 μm, Clariant, Switzerland;

[0050] Diethylaluminum hypophosphite 4: average particle size 40 μm, Clariant, Switzerland;

[0051] Inorganic aluminum hypophosphite: M-116, average particle size 5 μm, Shanghai Meilaipo Chemical Material Technology Co., Ltd.

[0052] MPP-1: BUDIT 3141, average particle size 8 μm, Budenheim, Germany;

[0053] MPP-2: FR-NP, average particle size ≤ 6 μm, Weidong, Shouguang, Shandong;

[0054] MPP-3: average particle size 20 μm, Sichuan Fine Chemical Research Institute;

[0055] Melamine cyanurate (MCA): MCA-01, average particle size 0.05-0.6 mm, Sichuan Fine Chemical Research Institute;

[0056] Phosphate 1: RDP, Zhejiang Wansheng Chemical;

[0057] Phosphate 2: BDP, Zhejiang Wansheng Chemical;

[0058] Phosphate 3: PX-200, Japan Daihachi Chemical;

[0059] Glass fiber 1: diameter 10 μm, ECS10-4.5-T436H, Taishan Glass Fiber Co., Ltd.

[0060] Glass fiber 2: diameter 13 μm, ECS13-4.5-534A, Jushi Group Co., Ltd.

[0061] Glass fiber 3: diameter 7 μm, ECS7-4.5-T436S, Taishan Glass Fiber Co., Ltd.

[0062] Glass fiber 4: diameter 17 μm, EDR17-2000-988A, Jushi Group Co., Ltd.

[0063] Toughening agent: ethylene-acrylate-glycidyl methacrylate terpolymer, commercially available;

[0064] Antioxidant: Antioxidant 1010, commercially available,

[0065] Lubricant: polyethylene wax, commercially available;

[0066] The toughening agent, antioxidant and lubricant used in the parallel experiments of the examples and comparative examples were consistent;

[0067] The products of different average particle sizes of diethyl aluminum hypophosphite are obtained by purchasing OP1230 product from Clariant of Switzerland, and then obtaining products of different average particle sizes by grinding and / or screening, wherein the screening is performed using sieves of corresponding different mesh sizes to obtain samples of the required average particle size; the average particle size of the product is tested by using a laser particle size analyzer to test the particle size of the sample, and the particle size analyzer model is MS2000E from MALVERN Company of the United Kingdom (UK).

[0068] Examples 1-19 and Comparative Examples 1-7

[0069] The component contents (parts by weight) of Examples 1-19 and Comparative Examples 1-7 of the present invention are shown in Table 1-3;

[0070] Table 1

[0071] Table 2

[0072] Table 3

[0073] The preparation methods of Examples 1-19 and Comparative Examples 1-7 are:

[0074] The dried raw materials were weighed and added to a mixer for uniform mixing, and then fed into a twin-screw extruder. The feed rate of the twin-screw extruder was adjusted to 600 kg / hour. The raw materials were extruded, stretched, cooled, pelletized, and dried to obtain a PBT composite material. The drying process of the PBT resin was as follows: the PBT resin was dried at 130° C. for 5 hours. The parameters of the twin-screw extruder were as follows: the temperatures of each section of the screw from the feed port to the die were 230° C., 240° C., 240° C., 250° C., 260° C., 250° C., 240° C., 230° C., and 220° C., respectively; and the screw speed was 400 rpm.

[0075] Effect Examples

[0076] The performance of the products prepared in Examples 1-19 and Comparative Examples 1-7 was verified by injection molding according to the corresponding standards to prepare test specimens (the thickness of the specimens was 0.4 mm); the test items included the following aspects:

[0077] 1. Tensile strength is tested according to ISO 527-1-2012 standard;

[0078] 2. Izod notched impact strength is tested in accordance with ISO 180-2007;

[0079] 3. Melt index test is carried out in accordance with ASTM D 1238 standard, and the test conditions are 250℃ / 2.16Kg;

[0080] 4. Flame retardancy is tested according to UL 94-1985 standard, with the thickness of the sample being 0.4 mm, and the flame retardancy grade is recorded. At the same time, the burning time of 5 standard specimens is tested, and the maximum and average time of T1+T2 are recorded, which are recorded as Tmax and Tavg, respectively. Tavg indicates the average flame retardancy of the material, and Tmax indicates the flame retardancy stability of the material. In addition, the flame retardancy grade of the sample with a thickness of 0.4 mm is tested.

[0081] The test results are shown in Table 4;

[0082] Table 4

[0083] As can be seen from Table 4, when the technical solution of the present invention is adopted, the obtained product has an excellent comprehensive effect, which not only meets the flame retardant requirements of thin-walled products, but also has excellent mechanical properties and fluidity. Specifically, the flame retardant grade of the obtained product is V-1 or V-0, wherein the average T is less than 7.5s, the longest T is less than 15.6s, the tensile strength is above 105MPa, and the impact strength is 7.2kJ / m 2 When the selected parameters are within the preferred range of the present invention, the flame retardant grade of the obtained product is V-0, wherein the average T is between 3.5-5.7s, the longest T is between 5.4-7.8s, the tensile strength is between 115-118MPa, and the impact strength is between 7.5-9.5kJ / m 2 The melt index is between 8.9-13.8g / 10min;

[0084] It can be seen from Examples 1 and 3 that the mass ratios of diethylaluminum hypophosphite, melamine polyphosphate and phosphate ester will affect the performance of the product. When the mass ratio of diethylaluminum hypophosphite, melamine polyphosphate and phosphate ester is further selected as diethylaluminum hypophosphite: melamine polyphosphate: phosphate ester = (14-16): (4-6): (2-3), the comprehensive performance of the obtained product is better; the flame retardant grade of the obtained products is V-0, wherein the average T is less than 4.2s, the longest T is less than 6.5s, the tensile strength is above 114MPa, and the impact strength is above 8.2kJ / m 2 Above, the melt index is above 10.1g / 10min;

[0085] It can be seen from Example 1 and Comparative Examples 1-3 that when any one of diethyl aluminum hypophosphite and melamine polyphosphate is missing, although the melt index of the obtained product increases, the flame retardancy of the product decreases significantly, the flame retardancy grade of V-2 cannot be achieved, and the average flame retardancy and flame retardancy stability also decrease significantly, T average>30s, T longest>30s, and when melamine polyphosphate is not added, the tensile strength and impact strength of the obtained product also decrease significantly; when phosphate is not added, although the flame retardancy grade of the obtained product does not change much, the average flame retardancy and flame retardancy stability also decrease significantly, and the fluidity of the obtained product deteriorates significantly, and the melt index decreases by 72.13% compared with Example 1; It can be seen from Example 1 and Comparative Examples 4-5 that when the total mass parts of diethyl aluminum hypophosphite, melamine polyphosphate and phosphate remain unchanged, However, when the relative weight parts of the three are changed, if they are not within the range of the addition parts specified in the present invention, the average flame retardant ability and flame retardant stability of the obtained product are significantly reduced. Compared with Example 1, the average increase in T is more than 351.43%, and the longest increase in T is more than 335.19%; It can be seen from Example 1 and Comparative Examples 6-7 that when an analogue is used to replace diethyl aluminum hypophosphite, the average flame retardant ability and flame retardant stability of the obtained product are significantly reduced. Compared with Example 1, the average increase in T is more than 371.43%, and the longest increase in T is 377.78% or more, and the tensile strength and impact strength also show a certain downward trend. When a similar product is used to replace melamine polyphosphate, although the fluidity of the obtained product is significantly increased, the flame retardancy is significantly reduced, and the flame retardancy grade is not achieved to be V-2. The average flame retardancy and flame retardancy stability are also significantly reduced, with T average > 30s and T maximum also > 30s. At the same time, the tensile strength and impact strength of the obtained product are also significantly reduced. Compared with Example 1, the tensile strength decreased by 17.24% and the impact strength decreased by 17.65%.

[0086] It can be seen from Example 1 and Examples 7-9 that the intrinsic viscosity of the PBT resin has a significant impact on the performance of the product. When the intrinsic viscosity of the PBT resin is not within the further preferred range, the comprehensive performance of the obtained product shows a certain downward trend. Specifically, when the intrinsic viscosity of the PBT resin is further preferably 0.7-1.0 dL / g, the comprehensive effect of the obtained product is more excellent. Specifically, the flame retardant grade of the obtained products is V-0, wherein the average T is less than 5.7s, the longest T is less than 7.8s, the tensile strength is greater than 116 MPa, and the impact strength is greater than 8.5 kJ / m 2 Above, the melt index is above 8.9g / 10min;

[0087] It can be seen from Example 1 and Examples 10-12, Example 1 and Examples 13-15, Example 1 and Examples 16-17, and Example 1 and Examples 18-19 that the selection of glass fiber diameter, average particle size of diethyl aluminum hypophosphite, melamine polyphosphate, and phosphate type will also affect the comprehensive performance of the product.

[0088] Finally, it should be noted that the above embodiments are intended to illustrate the technical solutions of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A PBT composite material, characterized in that: The PBT composite material comprises the following components in parts by mass: 30-60 parts of PBT resin, 25-40 parts of alkali-free glass fiber, 12-20 parts of diethyl aluminum hypophosphite, 2-8 parts of melamine polyphosphate, and 1-4 parts of phosphate ester.

2. The PBT composite material according to claim 1, characterized in that: In the PBT composite material, the mass ratio of diethyl aluminum hypophosphite, melamine polyphosphate and phosphate is diethyl aluminum hypophosphite: melamine polyphosphate: phosphate = (14-16): (4-6): (2-3).

3. The PBT composite material according to claim 1, characterized in that: At least one of the following (a)-(d): (a) The glass fiber is an alkali-free glass fiber treated with a coupling agent and has a diameter of 5-20 μm; (b) the average particle size of the diethyl aluminum hypophosphite is 8-42 μm; (c) the average particle size of the melamine polyphosphate is 7-10 μm; (d) The intrinsic viscosity of the PBT resin is 0.6-1.15 dL / g.

4. The PBT composite material according to claim 1, characterized in that: The phosphate ester is at least one of triphenyl phosphate, aryl phosphate, resorcinol-bis-diphenyl phosphate, bisphenol A-bis-diphenyl phosphate, resorcinol-bis[di(2,6-dimethylphenyl)phosphate], resorcinol-bis-diphenyl phosphate, and phenoxy cyclophosphazene.

5. The PBT composite material according to claim 1, characterized in that: The PBT composite material also includes 0.001-4 parts of a toughening agent and 0.001-1 parts of a processing aid.

6. The PBT composite material according to claim 5, characterized in that: The toughening agent is at least one of ethylene-acrylate-glycidyl methacrylate terpolymer, ethylene-acrylate binary copolymer, ethylene-vinyl acetate, and glycidyl methacrylate grafted ethylene-octene copolymer.

7. The PBT composite material according to claim 5, characterized in that: The processing aid is at least one of a lubricant and an antioxidant.

8. The method for preparing the PBT composite material according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: weighing the dried raw materials, mixing them and sending them into a twin-screw extruder, and performing extrusion, strip drawing, cooling, pelletizing and drying to obtain a PBT composite material.

9. The preparation method according to claim 8, characterized in that: The parameters of the twin-screw extruder are: feeding speed is 450-800kg / hour; the temperature of each section of the screw from the feeding port to the head is 220-230℃, 230-240℃, 230-240℃, 240-250℃, 250-260℃, 240-250℃, 240-250℃, 230-240℃, 220-230℃ respectively; the screw speed is 250-400rpm.

10. Use of the PBT composite material according to any one of claims 1 to 7 in ultra-thin electronic components.

11. A PBT composite material, characterized in that: The PBT composite material comprises the following components in parts by mass: 30-60 parts of PBT resin, 25-40 parts of glass fiber, 12-20 parts of diethyl aluminum hypophosphite, 2-8 parts of melamine polyphosphate, and 1-4 parts of phosphate ester.

12. The PBT composite material according to claim 11, characterized in that: In the PBT composite material, the mass ratio of diethyl aluminum hypophosphite, melamine polyphosphate and phosphate is diethyl aluminum hypophosphite: melamine polyphosphate: phosphate = (14-16): (4-6): (2-3).

13. The PBT composite material according to claim 11, characterized in that: At least one of the following (a)-(d): (a) The glass fiber is an alkali-free glass fiber treated with a coupling agent and has a diameter of 5-20 μm; (b) the average particle size of the diethyl aluminum hypophosphite is 8-42 μm; (c) the average particle size of the melamine polyphosphate is 7-10 μm; (d) The intrinsic viscosity of the PBT resin is 0.6-1.15 dL / g.

14. The PBT composite material according to claim 11, characterized in that: The phosphate ester is at least one of triphenyl phosphate, aryl phosphate, resorcinol-bis-diphenyl phosphate, bisphenol A-bis-diphenyl phosphate, resorcinol-bis[di(2,6-dimethylphenyl)phosphate], resorcinol-bis-diphenyl phosphate, and phenoxy cyclophosphazene.

15. The PBT composite material according to claim 11, characterized in that: The PBT composite material also includes 0.001-4 parts of a toughening agent and 0.001-1 parts of a processing aid.

16. The PBT composite material according to claim 15, characterized in that: The toughening agent is at least one of ethylene-acrylate-glycidyl methacrylate terpolymer, ethylene-acrylate binary copolymer, ethylene-vinyl acetate, and glycidyl methacrylate grafted ethylene-octene copolymer.

17. The PBT composite material according to claim 15, characterized in that: The processing aid is at least one of a lubricant and an antioxidant.

18. The method for preparing the PBT composite material according to any one of claims 11 to 17, characterized in that: The preparation method comprises the following steps: weighing the dried raw materials, mixing them and sending them into a twin-screw extruder, and performing extrusion, strip drawing, cooling, pelletizing and drying to obtain a PBT composite material.

19. The preparation method according to claim 18, characterized in that: The parameters of the twin-screw extruder are: feeding speed is 450-800kg / hour; the temperature of each section of the screw from the feeding port to the head is 220-230℃, 230-240℃, 230-240℃, 240-250℃, 250-260℃, 240-250℃, 240-250℃, 230-240℃, 220-230℃ respectively; the screw speed is 250-400rpm.

20. Use of the PBT composite material according to any one of claims 11 to 17 in ultra-thin electronic components.

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