PBT composite material, and preparation method therefor and use thereof

Abstract

Disclosed in the present application are a PBT composite material, and a preparation method therefor and the use thereof. The PBT composite material comprises the following components in parts by mass: 30-60 parts of a PBT resin, 10-30 parts of a flame retardant and 0.2-1.2 parts of a plasticizer. The PBT composite material can significantly reduce the adhesion of the material to a screw rod during the preparation process of a thin-wall product, thereby reducing the occurrence frequency of black spots on the surface of the product, so as to obtain a thin-wall product having low levels of injection molding black spots; in addition, the obtained composite material still has excellent flame retardant property in the preparation of a thin-wall product, and has a good tensile strength and a good impact strength. Moreover, the preparation method provided in the present application is simple and is beneficial to actual production.

Description

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

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

[0002] Flame-retardant PBT (polybutylene terephthalate) composites are widely used in the electronics and electrical industry due to their excellent mechanical, electrical, and heat resistance properties, as well as their relatively low cost. Relay and film capacitor casings, in particular, are mostly constructed from flame-retardant reinforced PBT composites. With the continuous advancement of materials technology, market products are trending towards miniaturization and thinner walls. However, this development is also hindered by numerous molding challenges. In recent years, the maturation of various new molding processes and mold flow analysis techniques has significantly promoted the application of thin-wall products, leading to an increasing number of customers demanding miniaturization and thinner walls (≤0.4mm).

[0003] In actual production, it was found that flame-retardant PBT composites do not produce black spots during the extrusion process, but rather during the injection molding process. Furthermore, when PBT composites without flame retardants are injection molded, no black spots are produced. Only PBT composites with flame retardants will develop black spots during the injection molding process. These spots are particularly prone to occur under extreme conditions (such as when thin-walled composites are required). Thinning the walls significantly increases the injection temperature and pressure of the material, posing a greater challenge to the heat resistance of flame-retardant PBT composites. Consequently, after prolonged injection molding of flame-retardant PBT composites under these conditions, noticeable carbonized black spots will form on the surface of light-colored parts. These spots are irregularly distributed, significantly impacting the product's appearance and quality. This makes selection time-consuming and labor-intensive for customers, and can easily lead to quality complaints from downstream customers. Therefore, research and improvement are urgently needed. Currently, the injection molding black spot problem is a pain point within the industry, with little research available domestically or internationally, and its specific mechanism of production remains unclear. Summary of the Invention

[0004] The present application provides a PBT composite material having fewer injection molding black spots when used in the preparation of thin-walled products (≤0.4 mm) and having excellent flame retardant properties, tensile strength and impact strength, as well as a preparation method and application thereof.

[0005] The present application provides a PBT composite material, comprising the following components in parts by weight:

[0006] 30-60 parts of PBT (polybutylene terephthalate) resin, 10-30 parts of flame retardant, and 0.2-1.2 parts of plasticizer;

[0007] The plasticizer is at least one of a phosphate plasticizer, a polyether plasticizer, or a polyether ester plasticizer;

[0008] The terminal carboxyl content of the PBT resin is ≤22 mol / t.

[0009] In some embodiments, the mass ratio of the PBT resin to the plasticizer is PBT resin:plasticizer=(19-28):0.3.

[0010] In some embodiments, the PBT resin has a terminal carboxyl content of 7-19 mol / t.

[0011] In some embodiments, the phosphate plasticizer is selected from at least one of resorcinol bis(diphenyl phosphate), resorcinol bis[di(2,6-dimethylphenyl) phosphate, bisphenol-A bis(diphenyl phosphate), resorcinol-bis(diphenyl phosphate), and polyaryl phosphate;

[0012] And / or, the average molecular weight of the polyether plasticizer is 300-4200, and the number average molecular weight of the polyether ester plasticizer is 300-4200.

[0013] In some embodiments, the polyetherester plasticizer is at least one of polyaromatic etherester or polyaliphatic etherester;

[0014] And / or, the polyether plasticizer includes polyethylene glycol.

[0015] In some embodiments, the flame retardant is a halogen flame retardant or a halogen-free flame retardant.

[0016] In some embodiments, the PBT composite material further comprises 25-40 parts by mass of glass fiber, 0-4 parts by mass of a toughening agent, and 0-1 part by mass of a processing aid;

[0017] 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;

[0018] And / or, the processing aid is at least one of a lubricant and an antioxidant.

[0019] The present application also provides a method for preparing the PBT composite material, comprising 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.

[0020] The present application also provides an application of the PBT composite material in ultra-thin electronic components.

[0021] The present application also provides the use of a plasticizer in reducing black spots in injection molding of a PBT composite material, wherein the plasticizer is at least one of a phosphate plasticizer, a polyether plasticizer, or a polyether ester plasticizer;

[0022] The PBT composite material comprises a PBT resin, and the terminal carboxyl group content of the PBT resin is less than or equal to 22 mol / t.

[0023] The beneficial effects of the present invention are:

[0024] The present invention provides a PBT composite material by selecting a specific type of plasticizer, and compounding the plasticizer in appropriate parts by mass with PBT resin and other components, thereby significantly reducing the adhesion of the material on the screw during the preparation of thin-walled products, thereby reducing the frequency of black spots on the product surface, and obtaining a thin-walled product with low injection molding black spots; at the same time, the obtained composite material still has excellent flame retardant properties when prepared into thin-walled (≤0.4mm) products, and has good tensile strength and impact strength; specifically, whether it is a halogen flame retardant system or a halogen-free flame retardant system, when the obtained product is prepared into a test sample at 0.4mm, the flame retardant grade of the sample is V-0, the mass of the wall material is less than 0.226g, the frequency of black spots is less than 36ppm, the tensile strength is greater than 123MPa, and the impact strength is greater than 10.4kJ / m 2 The above; and the preparation method of the composite material provided by the present invention is simple, which is conducive to actual production. DETAILED DESCRIPTION

[0025] A first aspect of the present application provides a PBT composite material, comprising the following components in parts by mass: 30-60 parts of PBT resin, 10-30 parts of flame retardant, and 0.2-1.2 parts of plasticizer;

[0026] The plasticizer is at least one of a phosphate plasticizer, a polyether plasticizer, or a polyether ester plasticizer;

[0027] The terminal carboxyl content of the PBT resin is ≤22 mol / t.

[0028] The present application provides a PBT composite material that selects a specific type of plasticizer and compounding an appropriate amount of the plasticizer by weight with a PBT resin within a specific end carboxyl content range and other components, thereby significantly reducing the adhesion of the material on the screw during the preparation of thin-walled products, thereby reducing the frequency of black spots on the product surface and obtaining a thin-walled product with low injection molding black spots; at the same time, the obtained composite material still has excellent flame retardant properties when prepared into thin-walled products (for example, thickness ≤0.4 mm), and has good tensile strength and impact strength.

[0029] Specifically, in order to solve the problem of black spots during the injection molding process of flame-retardant PBT composite materials, the inventors combined their R&D experience and data in the actual R&D process to infer that the generation of black spots may be due to the insufficient heat resistance of the material itself. When preparing thin walls, strong shear and high-temperature injection molding conditions are required, under which carbonization will occur. Based on the above inference, the inventors further used a variety of characterization methods (TG, constant temperature TG, melt index instrument heat retention, injection molding machine heat retention, high-temperature baking, etc.) to verify and found that it was not actually a problem of the heat resistance of the material, but most likely because the flame-retardant PBT material easily adheres to the inner wall of the screw / barrel and is not easily brought out by the material. After a long period of residence, carbonization occurs, and then black spots are generated. Therefore, based on the above observations and characterizations, the inventors creatively proposed the technical solution of the present application. Under the technical solution provided in this application, selecting a plasticizer in appropriate parts by mass and compounding it with a PBT resin within a specific end carboxyl content can effectively reduce the adhesion of the material to the inner wall of the screw / barrel, thereby reducing the frequency of black spots.

[0030] In some embodiments, the mass ratio of the PBT resin to the plasticizer is PBT resin:plasticizer=(19-28):0.3.

[0031] The inventors have found that when the mass ratio of PBT resin and plasticizer is further selected within the above range, the adhesion of the material to the inner wall of the screw / barrel can be better reduced, thereby reducing the frequency of black spots in the product.

[0032] Exemplarily, the mass ratio of the PBT resin and the plasticizer can be any point value between (19-28):0.3 or a range value formed by any two points, such as 19:0.3, 20:0.3, 21:0.3, 22:0.3, 23:0.3, 24:0.3, 25:0.3, 26:0.3, 27:0.3, 28:0.3 or the like, or a range value between the point values; when the mass ratio of the PBT resin and the plasticizer is within the range of (19-28):0.3, excellent comprehensive effects can be achieved.

[0033] In some embodiments, the minimum mass percentage of PBT resin in the PBT composite is 28%.

[0034] In some embodiments, the PBT resin has a terminal carboxyl content of 7-19 mol / t.

[0035] The terminal carboxyl content of PBT resin can be tested with reference to GB / T 14190-2017.

[0036] The inventors have found that when the terminal carboxyl content of the PBT resin is further selected to be 7-19 mol / t, the overall performance is better.

[0037] Exemplarily, the terminal carboxyl content of the PBT resin can be any point value between 7 and 19 mol / t or a range value between any two points, such as 7 mol / t, 8 mol / t, 9 mol / t, 10 mol / t, 11 mol / t, 12 mol / t, 13 mol / t, 14 mol / t, 15 mol / t, 16 mol / t, 17 mol / t, 18 mol / t, 19 mol / t or the like, or a range value between any two points. Due to space limitations, they are not listed here one by one. When the terminal carboxyl content is within the range of 7 to 19 mol / t, a better overall effect can be achieved.

[0038] In some embodiments, the phosphate plasticizer is selected from at least one of resorcinol bis(diphenyl phosphate) (SOL-DP), resorcinol bis[di(2,6-dimethylphenyl) phosphate (RDX), bisphenol-A bis(diphenyl phosphate) (BDP), resorcinol-bis(diphenyl phosphate) (RDP), and polyaryl phosphate (PX-220);

[0039] In some embodiments, the average molecular weight of the polyether plasticizer is 300-4200, and the number average molecular weight of the polyetherester plasticizer is 300-4200. In some embodiments, the average molecular weight of the polyether plasticizer refers to the number average molecular weight.

[0040] The testing method for the number average molecular weight of the polyether ester plasticizer can refer to SN / T 3002-2011, and can be tested by high-temperature gel permeation chromatography; the testing method for the average molecular weight of the polyether plasticizer can refer to gel permeation chromatography (GPC).

[0041] In some embodiments, the phosphate plasticizer is at least one of bisphenol-A bis(diphenyl phosphate) (BDP) and resorcinol-bis(diphenyl phosphate) (RDP).

[0042] In some embodiments, the polyetherester plasticizer is at least one of polyaromatic etherester or polyaliphatic etherester.

[0043] In some embodiments, the polyether plasticizer includes polyethylene glycol.

[0044] For example, the average molecular weight of the polyether plasticizer can be any point value between 300-4200 or a range value consisting of any two points, such as a range value of 1400-2000, or 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000. , 2100, 2200, 2300, 2400, 2500, 2600, 2700, 2800, 2900, 3000, 3100, 3200, 3300, 3400, 3500, 3600, 3700, 3800, 3900, 4000, 4100, 4200, etc., are not listed here one by one due to space limitations; within the average molecular weight range given in this application, the effects of the present application can be achieved.

[0045] The number average molecular weight of the polyether ester plasticizer can be any point value between 300-4200 or a range of any two points, such as 1400-2000, or 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2100, 2200, 2300, 2400, 2500, 2600, 2700, 2800, 2900, 3000, 3100, 3200, 3300, 3400, 3500, 3600, 3700, 3800, 3900, 4000, 4100, 4200, 4300, 4400 100, 2200, 2300, 2400, 2500, 2600, 2700, 2800, 2900, 3000, 3100, 3200, 3300, 3400, 3500, 3600, 3700, 3800, 3900, 4000, 4100, 4200, etc. Due to space limitations, they are not listed here one by one; within the number average molecular weight range given in this application, the effects of the present application can be achieved.

[0046] In some embodiments, the average molecular weight of the polyether plasticizer is 800-2200, and the number average molecular weight of the polyether ester plasticizer is 800-2200. The inventors have found that when the average molecular weight of the polyether plasticizer and the number average molecular weight of the polyether ester plasticizer are further selected to be 800-2200, the overall effect of the obtained product is even better.

[0047] In some embodiments, the flame retardant is a halogen flame retardant or a halogen-free flame retardant.

[0048] The halogenated and halogen-free flame retardants in this application are commonly used flame retardants. For example, the halogen-free flame retardant may be diethyl aluminum hypophosphite, inorganic aluminum hypophosphite, melamine polyphosphate, melamine cyanurate, etc. For example, the halogenated flame retardant may be brominated epoxy, brominated polystyrene, brominated polycarbonate, decabromodiphenylethane, polypentabromobenzyl acrylate, ethylenebistetrabromophthalimide, bromotriazine, antimony white, etc.

[0049] In some embodiments, the PBT composite material further comprises 25-40 parts by mass of glass fiber, 0-4 parts by mass of a toughening agent, and 0-1 part by mass of a processing aid.

[0050] In some embodiments, the glass fibers have an average diameter of 6-13 μm.

[0051] For example, the average diameter of the glass fiber can be any point value between 6-13 μm or a range value consisting of any two points, such as 6 μm, 6.2 μm, 6.4 μm, 6.6 μm, 6.8 μm, 7 μm, 7.2 μm, 7.4 μm, 7.6 μm, 7.8 μm, 8 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, 9.8μm, 10μm, 10.2μm, 10.4μm, 10.6μm, 10.8μm, 11μm, 11.2μm, 11.4μm, 11.6μm, 11.8μm, 12μm, 12.2μm, 12.4μm, 12.6μm, 12.8μm, 13μm, etc., are not listed here one by one due to space limitations; within the average diameter range of the glass fiber given in this application, the effects of this application can be achieved.

[0052] In some embodiments, the average diameter of the glass fiber is 7-10 μm. The inventors have found that when the average diameter of the glass fiber is further selected to be 7-10 μm, the overall effect is better.

[0053] In some embodiments, 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.

[0054] In some embodiments, the processing aid includes at least one of an antioxidant and a lubricant.

[0055] In some embodiments, the lubricant is at least one of aliphatic carboxylic acid ester and polyolefin wax; and the antioxidant is a hindered phenol antioxidant.

[0056] The second aspect of the present application 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.

[0057] In some embodiments, the drying process of the PBT resin is: drying the PBT resin at 120-140° C. for 4-6 hours until the moisture content is less than 0.03%.

[0058] In some embodiments, the parameters of the twin-screw extruder are: feeding rate of 450-800 kg / hour; the temperature of each section of the screw from the feeding port to the head is 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 respectively; the screw speed is 250-400 rpm.

[0059] The third aspect of the present application further provides application of the PBT composite material in ultra-thin (eg, thickness ≤ 0.4 mm) electronic components.

[0060] In some embodiments, the application is application of the PBT composite material in cooling fans, relays, and capacitors.

[0061] The fourth aspect of the present application further provides the use of a plasticizer in reducing black spots in injection molding of PBT composite materials, wherein the plasticizer is at least one of a phosphate plasticizer, a polyether plasticizer, or a polyether ester plasticizer;

[0062] The PBT composite material comprises a PBT resin, and the terminal carboxyl group content of the PBT resin is less than or equal to 22 mol / t.

[0063] The present application study found that selecting at least one of phosphate plasticizers, polyether plasticizers or polyether ester plasticizers for use in flame-retardant PBT composite materials can reduce the occurrence of injection molding black spots caused by the introduction of flame retardants into PBT composite materials.

[0064] In some embodiments, the flame retardant PBT composite material includes the following components in parts by mass: 30-60 parts of PBT resin, 10-30 parts of flame retardant, and 0.2-1.2 parts of plasticizer.

[0065] In some embodiments, the phosphate plasticizer is selected from at least one of resorcinol bis(diphenyl phosphate), resorcinol bis[di(2,6-dimethylphenyl) phosphate, bisphenol-A bis(diphenyl phosphate), resorcinol-bis(diphenyl phosphate), and polyaryl phosphate;

[0066] And / or, the average molecular weight of the polyether plasticizer is 300-4200, and the number average molecular weight of the polyether ester plasticizer is 300-4200.

[0067] In some embodiments, the polyetherester plasticizer is at least one of polyaromatic etherester or polyaliphatic etherester;

[0068] And / or, the polyether plasticizer includes polyethylene glycol.

[0069] In some embodiments, the PBT composite material described in the fourth aspect of the present application is the PBT composite material described in any one of the embodiments described in the first aspect of the present application.

[0070] In order to better illustrate the purpose, technical solutions and advantages of this application, this application will be further described below in conjunction with specific embodiments.

[0071] Unless otherwise specified, the reagents, methods and equipment used in this application are conventional reagents, methods and equipment in the art.

[0072] PBT-1: PBT GX121J, terminal carboxyl content 9.0 mol / t, Sinopec Yizheng Chemical Fiber;

[0073] PBT-2: PBT-GX112, terminal carboxyl content 19.0 mol / t, Sinopec Yizheng Chemical Fiber;

[0074] PBT-3: PBT GX122J, terminal carboxyl content 7.0 mol / t, Sinopec Yizheng Chemical Fiber;

[0075] PBT-4: PBT GX110, terminal carboxyl content 28.0 mol / t, Sinopec Yizheng Chemical Fiber;

[0076] Flame retardant 1: halogenated flame retardant, brominated epoxy resin, commercially available;

[0077] Flame retardant 2: halogenated flame retardant, antimony white, commercially available;

[0078] Flame retardant 3: halogen-free flame retardant, diethyl aluminum hypophosphite, commercially available;

[0079] Flame retardant 4: halogen-free flame retardant, melamine polyphosphate, commercially available;

[0080] Plasticizer 1: Phosphate plasticizer, resorcinol bis(diphenyl phosphate), WSFR-RDP, Zhejiang Wansheng Chemical;

[0081] Plasticizer 2: Phosphate plasticizer, bisphenol A bis(diphenyl phosphate), WSFR-BDP, Zhejiang Wansheng Chemical;

[0082] Plasticizer 3: Phosphate plasticizer, resorcinol-bis(diphenyl phosphate), SOL-DP, ICL, Israel;

[0083] Plasticizer 4: Polyether ester plasticizer, oligomeric aromatic ether ester, A-55, number average molecular weight 1500, Japan DIC;

[0084] Plasticizer 5: polyether ester plasticizer, oligomeric aliphatic ether ester, RS-735, number average molecular weight 850, ADEKA (Shanghai);

[0085] Plasticizer 6: polyether plasticizer, PEG-2000, average molecular weight 2000, Aoki (Japan);

[0086] Plasticizer 7: polyether plasticizer, PEG-400, average molecular weight 400, BASF (Germany);

[0087] Plasticizer 8: polyether plasticizer, PEG-4000, average molecular weight 4000, Lotte (South Korea);

[0088] Plasticizer 9: diisobutyl phthalate, commercially available;

[0089] Plasticizer 10: cellulose butyl acetate, commercially available;

[0090] Glass fiber 1: average diameter 7 μm, ECS7-4.5-T436S, Taishan Glass Fiber Co., Ltd.

[0091] Glass fiber 2: average diameter 10 μm, ECS10-4.5-T436H, Taishan Glass Fiber Co., Ltd.

[0092] Glass fiber 3: average diameter 13 μm, ECS13-4.5-534A, Jushi Group Co., Ltd.

[0093] Toughening agent: ethylene-acrylate-glycidyl methacrylate terpolymer, commercially available;

[0094] Antioxidant: Antioxidant 1010, commercially available,

[0095] Lubricant: polyethylene wax, commercially available;

[0096] The toughening agent, antioxidant and lubricant used in the parallel experiments of the examples and comparative examples were consistent.

[0097] Examples 1-20 and Comparative Examples 1-5

[0098] The component contents (parts by weight) of Examples 1-20 and Comparative Examples 1-5 of the present application are shown in Table 1-2;

[0099] Table 1

[0100] Table 2

[0101] The preparation methods of Examples 1-20 and Comparative Examples 1-5 are:

[0102] 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 until the moisture content was below 0.03%. The parameters of the twin-screw extruder were as follows: the temperatures of each screw section 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.

[0103] Effect Examples

[0104] The present application effect example verifies the performance of the products prepared in Examples 1-20 and Comparative Examples 1-5; test samples (the thickness of the sample is 0.4 mm) are prepared by injection molding according to the corresponding standards; the test items include the following aspects:

[0105] 1. Tensile strength is tested according to ISO 527-1-2012 standard;

[0106] 2. Izod notched impact strength is tested in accordance with ISO 180-2007;

[0107] 3. Flame retardant performance is tested according to UL 94-1985 standard;

[0108] 4. Quality of the material hanging on the wall of the melt indexer: Design an evaluation method for the material hanging on the wall of the melt indexer. The quality of the material hanging on the wall is the quality of the material remaining on the inner wall after the melt flows through the melt indexer. It can reflect the ability of the material to adhere to the inner wall of the metal to a certain extent. The specific method is as follows: Before each experiment, clean the accumulated material in the melt indexer and the die, weigh a fixed mass of pellets m1 and place it in the melt indexer. After 4 minutes, squeeze out the sample and weigh it as m2. The mass of the residual material in the melt indexer is m3 = m1-m2, and the mass of the material hanging on the wall of the melt indexer is m5 = m3-the material in the die m4. Considering that the mass of the material in the die m4 is inconvenient Weighing, but after calculation, we believe that the maximum difference caused by the mass of the material in the die is about 0.0025g (die diameter 0.2cm, die height 0.8cm, melt density calculated as 1.3-1.4, the maximum difference caused by different material densities is: 0.1×0.1×3.14×0.8×(1-1.3 / 1.4)×=0.0025g). If the difference in m3 exceeds 0.0025g, it can basically be considered to be caused by the quality difference of the wall hanging material. Based on this, we can compare and evaluate the existing formula. According to the above method, measure 3 times each time and take the average value;

[0109] 5. Actual injection molding black spots: The actual injection molding black spot frequency of the material is verified during the actual injection molding process. That is, the parts with black spots are manually selected after the injection molding. The frequency calculation result = the number of black spot parts / the total number of parts. The result is in ppm.

[0110] The test results are shown in Table 3;

[0111] Table 3

[0112] As can be seen from Table 3, when the technical solution of the present application 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 the obtained product has less wall hanging material on the melt index instrument and less actual injection molding black spots; specifically, the obtained product has a flame retardant grade of V-0, a tensile strength of more than 123 MPa, and an impact strength of 10.4 kJ / m 2 Above, the mass of the wall material on the melt index instrument is less than 0.226g, and the actual injection molding black spot is less than 36ppm;

[0113] It can be seen from Examples 1-8 that the mass fraction of the components added to the PBT composite material will affect the performance of the product, and the mass fraction ratio of the PBT resin to the plasticizer will also affect the performance of the product. When the mass fraction ratio of the PBT resin to the plasticizer is further preferably (19-28):0.3, the comprehensive performance of the obtained product is better, and the flame retardant grade of the obtained product is V-0, the tensile strength is above 130 MPa, and the impact strength is above 11.2 kJ / m2 Above, the mass of the wall material on the melt index instrument is less than 0.215g, and the actual injection molding black spot is less than 20ppm;

[0114] It can be seen from Example 1 and Comparative Example 1 that when the plasticizer of the present application is not added, the mass of the melt indexer wall material of the obtained product reaches 0.236 g, and the actual injection molding black spot reaches 92 ppm. Compared with Example 1, the mass of the melt indexer wall material increased by 12.92%, and the actual injection molding black spot frequency increased by 4.1%; It can be seen from Example 1 and Comparative Example 2 that when the mass fraction of the plasticizer is not within the range given in this application, the comprehensive performance of the obtained product is significantly reduced. Compared with Example 1, the mass of the melt indexer wall material of the product in Comparative Example 2 increased by 13.88%, and the actual injection molding black spot frequency increased by 3.9 times;

[0115] It can be seen from Example 1, Examples 9-10 and Comparative Example 3 that the terminal carboxyl content of the PBT resin will also significantly affect the comprehensive performance of the product. When the terminal carboxyl content of the PBT resin is further selected to be 7-19 mol / t, the comprehensive performance of the obtained product is better, and the flame retardant grade of the obtained product is V-0, the tensile strength is above 132 MPa, and the impact strength is above 10.8 kJ / m 2 As shown above, the mass of the melt indexer wall material is less than 0.215g, and the actual injection molding black spot is less than 21ppm; when the terminal carboxyl group content of the PBT resin selected in Comparative Example 3 is not within the range given in this application, compared with Example 1, the mass of the melt indexer wall material of the product increases by 13.88%, and the actual injection molding black spot frequency increases by 4.4 times;

[0116] It can be seen from Examples 1 and 11 that the system provided by this application has excellent effects on both halogenated flame retardants and halogen-free flame retardants;

[0117] It can be seen from Example 1, Examples 12-18 and Comparative Examples 4-5 that the type of plasticizer significantly affects the overall effect of the product of the present application. When the type of plasticizer selected is not the phosphate plasticizer, polyether plasticizer or polyether ester plasticizer described in the present application, the overall performance of the obtained product is significantly reduced. Compared with Example 1, the melt index instrument wall hanging material quality of the products obtained in Comparative Examples 4-5 increased by 12.44-14.83%, and the actual injection molding black spot frequency increased by 3.8-4.8 times;

[0118] It can be seen from Example 1 and Examples 19-20 that the diameter of the alkali-free glass fiber will also have a more obvious impact on the performance of the product. When the diameter of the alkali-free glass fiber is further selected to be 7-10 μm, the actual injection molding black spot frequency of the obtained product is lower, below 20 ppm.

[0119] Finally, it should be noted that the above embodiments are intended to illustrate the technical solutions of the present application rather than to limit the scope of protection of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A PBT composite material, characterized in that: The PBT composite material comprises the following components in parts by mass: PBT (polybutylene terephthalate) resin 30-60 parts, flame retardant 10-30 parts, plasticizer 0.2-1.2 parts; The plasticizer is at least one of a phosphate plasticizer, a polyether plasticizer or a polyether ester plasticizer; The terminal carboxyl content of the PBT resin is ≤22 mol / t.

2. The PBT composite material according to claim 1, characterized in that: The mass ratio of the PBT resin to the plasticizer is PBT resin:plasticizer=(19-28):0.

3.

3. The PBT composite material according to claim 1, characterized in that: The terminal carboxyl content of the PBT resin is 7-19 mol / t.

4. The PBT composite material according to claim 1, characterized in that: The phosphate plasticizer is selected from at least one of resorcinol bis(diphenyl phosphate), resorcinol bis[di(2,6-dimethylphenyl) phosphate, bisphenol-A bis(diphenyl phosphate), resorcinol-bis(diphenyl phosphate), and polyaryl phosphate; And / or, the average molecular weight of the polyether plasticizer is 300-4200, and the number average molecular weight of the polyether ester plasticizer is 300-4200.

5. The PBT composite material according to claim 1, characterized in that: The polyether ester plasticizer is at least one of polyaromatic ether ester or polyaliphatic ether ester; And / or, the polyether plasticizer includes polyethylene glycol.

6. The PBT composite material according to claim 1, characterized in that: The flame retardant is a halogen flame retardant or a halogen-free flame retardant.

7. The PBT composite material according to claim 1, characterized in that: The PBT composite material further comprises 25-40 parts by mass of glass fiber, 0-4 parts by mass of toughening agent, and 0-1 parts by mass of processing aid; 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; And / or, 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. Application of the PBT composite material according to any one of claims 1 to 7 in ultra-thin electronic components.

10. Application of plasticizer in reducing black spots in injection molding of PBT composite materials, characterized in that: The plasticizer is at least one of a phosphate plasticizer, a polyether plasticizer or a polyether ester plasticizer; The PBT composite material comprises a PBT resin, and the terminal carboxyl content of the PBT resin is ≤22 mol / t.

Images