PBT composite material, preparation method and application thereof

Abstract

The application discloses a PBT composite material and a preparation method and application thereof, and belongs to the technical field of polymer engineering plastics; the PBT composite material provided by the application comprises the following components in parts by mass: PBT resin 30-60 parts, flame retardant 10-30 parts, and plasticizer 0.2-1.2 parts. The PBT composite material provided by the application can significantly reduce the adhesion of material on a screw during the preparation process of a thin-wall product, thereby reducing the appearance frequency of black spots on the surface of the product, and obtaining a thin-wall product with low injection molding black spots; meanwhile, the obtained composite material still has excellent flame retardant performance when being prepared into a thin-wall product, and has good tensile strength and impact strength; and the preparation method provided by the application is simple and is beneficial to actual production.

Description

Technical Field

[0001] This invention belongs to the field of polymer engineering plastics technology, and particularly relates to a PBT composite material, its preparation method and application. Background Technology

[0002] Flame-retardant PBT composite materials are widely used in the electronics and electrical industry due to their excellent mechanical, electrical, and heat resistance properties, as well as relatively low cost. They are particularly prevalent in relay and film capacitor housings, where flame-retardant reinforced PBT composite materials are the most common. With the continuous development of materials technology, the market trend is towards miniaturization and thinner walls. However, numerous molding challenges limit this development. In recent years, the maturity of various new molding processes and mold flow analysis techniques has greatly promoted the application of thin-walled 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 extrusion; these black spots only appear during injection molding. Furthermore, injection molding with PBT composites without added flame retardants also does not produce black spots. Black spots only appear in PBT composites with added flame retardants during injection molding, especially under extreme conditions (such as when thin-walled molding is required). This is because thin-walling significantly increases the injection temperature and pressure, posing a greater challenge to the heat resistance of flame-retardant PBT composites. Therefore, after prolonged injection molding under these conditions, flame-retardant PBT composites will develop noticeable carbonized black spots on the surface of light-colored parts. These black spots are irregularly distributed, significantly impacting the product's appearance quality. This causes time and effort for customers during selection and easily leads to quality complaints from downstream customers. Therefore, urgent research and improvement are needed. Currently, the injection molding black spot problem is a pain point in the industry, with few domestic and international publications exploring it, and its specific formation mechanism remains unclear. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a PBT composite material with fewer injection molding black spots when used in the preparation of thin-walled products (≤0.4mm), while also having excellent flame retardant properties, tensile strength and impact strength, as well as its preparation method and application.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a PBT composite material comprising the following components in parts by weight: 30-60 parts of PBT resin, 10-30 parts of flame retardant, and 0.2-1.2 parts of plasticizer;

[0006] The plasticizer is at least one of phosphate ester plasticizers, polyether plasticizers, or polyether ester plasticizers;

[0007] The PBT resin has a terminal carboxyl group content of ≤22mol / t.

[0008] This invention provides a PBT composite material by selecting a specific type of plasticizer and compounding an appropriate mass of the plasticizer with PBT resin and other components within a specific range of terminal carboxyl group content. This significantly reduces the adhesion of the material to the screw during the preparation of thin-walled products, thereby reducing the frequency of black spots on the product surface and obtaining thin-walled products 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 also has good tensile strength and impact strength.

[0009] Specifically, to address the issue of black spots occurring during the injection molding of flame-retardant PBT composite materials, the inventors, based on their research experience and data analysis, deduced that the black spots might be due to insufficient heat resistance of the material itself. They reasoned that the thin-walled molding process requires high shear and high-temperature injection molding conditions, under which carbonization occurs. Building upon this deduction, the inventors further verified the issue using various characterization methods (TG, isothermal TG, melt indexer thermal retention, injection molding machine thermal retention, high-temperature baking, etc.). They discovered that the problem was not actually related to the material's heat resistance, but rather that the flame-retardant PBT material easily adhered to the inner wall of the screw / barrel, making it difficult to remove. After prolonged contact, carbonization occurred, resulting in black spots. Therefore, based on these observations and characterizations, the inventors creatively proposed the technical solution of this invention. Under this solution, by selecting appropriate mass fractions of plasticizer and compounding it with PBT resin within a specific end-carboxyl group content, the adhesion of the material to the inner wall of the screw / barrel can be effectively reduced, thereby decreasing the frequency of black spot occurrence.

[0010] In a preferred embodiment of the PBT composite material of the present invention, the mass ratio of PBT resin to plasticizer is PBT resin:plasticizer = (19-28):0.3.

[0011] The inventors discovered that when the mass ratio of PBT resin to plasticizer is further selected within the above range, the adhesion of material to the inner wall of the screw / barrel can be better reduced, thereby reducing the frequency of black spots appearing on the product.

[0012] For example, the mass ratio of PBT resin to plasticizer can be any point value or any range formed by any two points between (19-28):0.3, 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, etc.; when the mass ratio of PBT resin to plasticizer is within the range of (19-28):0.3, excellent comprehensive effects can be achieved.

[0013] The minimum mass percentage of PBT resin in the PBT composite material is 28%.

[0014] In a preferred embodiment of the PBT composite material of the present invention, the end carboxyl group content of the PBT resin is 7-19 mol / t.

[0015] The end carboxyl group content of PBT resin was tested in accordance with GB / T 14190-2017.

[0016] The inventors discovered that when the end carboxyl group content of the PBT resin is further selected to be 7-19 mol / t, the overall performance is even better.

[0017] For example, the terminal carboxyl group content of PBT resin can be any point value or any range between two points between 7 and 19 mol / t, 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, etc., or any range between two points. Due to space limitations, they will not be listed here. When the terminal carboxyl group content is in the range of 7-19 mol / t as further preferred by the present invention, a more excellent overall effect can be achieved.

[0018] In a preferred embodiment of the PBT composite material of the present invention, the phosphate ester plasticizer is selected from at least one of resorcinol bis(diphenyl phosphate) (SOL-DP), resorcinol bis[bis(2,6-dimethylphenyl) phosphate (RDX), bisphenol A bis(diphenyl phosphate) (BDP), resorcinol-bis(diphenyl phosphate) (RDP), and polyaryl phosphate (PX-220);

[0019] 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.

[0020] The number-average molecular weight of the polyether ester plasticizer is tested using high-temperature gel permeation chromatography, in accordance with SN / T 3002-2011; the average molecular weight of the polyether plasticizer is tested using gel permeation chromatography (GPC).

[0021] Preferably, the phosphate ester plasticizer is at least one of bisphenol A bis(diphenyl phosphate) (BDP) and resorcinol-bis(diphenyl phosphate) (RDP).

[0022] Preferably, the polyether ester plasticizer is at least one of polyaromatic ether ester or polyaliphatic ether ester.

[0023] Preferably, the polyether plasticizer includes polyethylene glycol.

[0024] For example, the average molecular weight of the polyether plasticizer can be any value between 300 and 4200, or a range of any two values, such as 1400-2000, or values ​​of 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, or 2000. The following are examples of molecular weights: 2100, 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. Within the average molecular weight range given in this invention, the effects of this invention can be achieved.

[0025] The number average molecular weight of the polyether ester plasticizer can be any value between 300 and 4200, or a range of any two values, such as 1400-2000, or values ​​of 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2... 100, 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 due to space limitations; within the number-average molecular weight range given in this invention, the effects of this invention can be achieved.

[0026] Preferably, 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 product is even better.

[0027] In a preferred embodiment of the PBT composite material of the present invention, the flame retardant is a halogenated flame retardant or a halogen-free flame retardant.

[0028] The halogenated and halogen-free flame retardants in this invention are conventionally used flame retardant types. For example, the halogen-free flame retardant may be diethyl aluminum hypophosphite, inorganic aluminum hypophosphite, melamine polyphosphate, melamine cyanurate, etc., and the halogenated flame retardant may be brominated epoxy, brominated polystyrene, brominated polycarbonate, decabromodiphenyl ethane, pentabromobenzyl polyacrylate, ethylene bis(tetrabromophthalimide), bromotriazine, antimony white, etc.

[0029] As a preferred embodiment of the PBT composite material of the present invention, the PBT composite material further includes 25-40 parts of glass fiber, 0-4 parts of toughening agent, and 0-1 parts of processing aid.

[0030] In a preferred embodiment of the PBT composite material of the present invention, the average diameter of the glass fiber is 6-13 μm.

[0031] For example, the average diameter of the glass fiber can be any point value or a range of any two points between 6 and 13 μm, 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, etc. 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 due to space limitations; the effects of this invention can be achieved within the average diameter range of glass fibers given in this invention.

[0032] Preferably, 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 even better.

[0033] In 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 ethylene-octene copolymer grafted with glycidyl methacrylate.

[0034] In a preferred embodiment of the PBT composite material of the present invention, the processing aid includes at least one of antioxidants and lubricants.

[0035] Preferably, the lubricant is at least one of aliphatic carboxylic acid esters and polyolefin waxes; the antioxidant is a hindered phenolic antioxidant.

[0036] In a second aspect, the present invention also provides a method for preparing the PBT composite material, the method comprising the following steps: weighing and mixing the dried raw materials and feeding them into a twin-screw extruder, followed by extrusion, stranding, cooling, pelletizing and drying to obtain the PBT composite material.

[0037] As a preferred embodiment of the preparation method of the present invention, the drying process of the PBT resin is as follows: the PBT resin is dried at 120-140°C for 4-6 hours until the moisture content is <0.03%.

[0038] As a preferred embodiment of the preparation method described in this invention, the parameters of the twin-screw extruder are as follows: feeding speed is 450-800 kg / hour; the screw temperatures from the feed port to the die head are 220-230℃, 230-240℃, 230-240℃, 240-250℃, 250-260℃, 240-250℃, 240-250℃, 230-240℃, and 220-230℃, respectively; and the screw speed is 250-400 rpm.

[0039] In a third aspect, the present invention also provides the application of the PBT composite material in ultra-thin (≤0.4 mm) electronic components.

[0040] Examples of applications of PBT composite materials include cooling fans, relays, and capacitors.

[0041] In a fourth aspect, the present invention also provides the application of a plasticizer in reducing black spots in injection molding of flame-retardant PBT composite materials, wherein the plasticizer is at least one of phosphate ester plasticizers, polyether plasticizers, or polyether ester plasticizers.

[0042] The PBT resin has a terminal carboxyl group content of ≤22mol / t.

[0043] This invention has found that when at least one of phosphate ester plasticizers, polyether plasticizers, or polyether ester plasticizers is used in flame-retardant PBT composites, the occurrence of injection molding black spots caused by the introduction of flame retardants into PBT composites can be reduced.

[0044] As a preferred embodiment of the application described in this invention, the flame-retardant PBT composite material comprises the following components in parts by weight: 30-60 parts of PBT resin, 10-30 parts of flame retardant, and 0.2-1.2 parts of plasticizer.

[0045] As a preferred embodiment of the application described in this invention, the phosphate ester plasticizer is selected from at least one of resorcinol bis(diphenyl phosphate), resorcinol bis[bis(2,6-dimethylphenyl) phosphate, bisphenol-A bis(diphenyl phosphate), resorcinol-bis(diphenyl phosphate), and polyaryl phosphate.

[0046] 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.

[0047] In a preferred embodiment of the application described in this invention, the polyether ester plasticizer is at least one of polyaromatic ether ester or polyaliphatic ether ester.

[0048] And / or, the polyether plasticizer includes polyethylene glycol.

[0049] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0050] This invention provides a PBT composite material that uses a specific type of plasticizer and blends an appropriate amount of plasticizer with PBT resin and other components. This significantly reduces material adhesion to the screw during the preparation of thin-walled products, thereby reducing the frequency of black spots on the product surface and resulting in thin-walled products with low injection molding black spots. Simultaneously, the resulting composite material maintains excellent flame retardant properties, as well as good tensile strength and impact strength, even when prepared as thin-walled (≤0.4mm) products. Specifically, regardless of whether the flame retardant system is halogenated or halogen-free, when the product is prepared as a 0.4mm test sample, the flame retardant rating is V-0, the wall-mounted material weight is less than 0.226g, the black spot frequency is less than 36ppm, the tensile strength is above 123MPa, and the impact strength is 10.4kJ / m². 2 The above points are also relevant; furthermore, the method for preparing the composite material provided by this invention is simple and beneficial for actual production. Detailed Implementation

[0051] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0052] Unless otherwise specified, the reagents, methods and equipment used in this invention are all conventional reagents, methods and equipment in the field.

[0053] PBT-1: PBT GX121J, with a terminal carboxyl group content of 9.0 mol / t, produced by Sinopec Yizheng Chemical Fiber.

[0054] PBT-2: PBT-GX112, with a terminal carboxyl group content of 19.0 mol / t, produced by Sinopec Yizheng Chemical Fiber.

[0055] PBT-3: PBT GX122J, with a terminal carboxyl group content of 7.0 mol / t, produced by Sinopec Yizheng Chemical Fiber.

[0056] PBT-4: PBT GX110, with a terminal carboxyl group content of 28.0 mol / t, produced by Sinopec Yizheng Chemical Fiber.

[0057] Flame retardant 1: Halogenated flame retardant, brominated epoxy resin, commercially available;

[0058] Flame retardant 2: Halogenated flame retardant, antimony white, commercially available;

[0059] Flame retardant 3: Halogen-free flame retardant, aluminum diethylphosphite, commercially available;

[0060] Flame retardant 4: Halogen-free flame retardant, melamine polyphosphate, commercially available;

[0061] Plasticizer 1: Phosphate ester plasticizer, resorcinol bis(diphenyl phosphate), WSFR-RDP, Zhejiang Wansheng Chemical;

[0062] Plasticizer 2: Phosphate ester plasticizer, bisphenol A bis(diphenyl phosphate), WSFR-BDP, Zhejiang Wansheng Chemical;

[0063] Plasticizer 3: Phosphate ester plasticizers, resorcinol-bis(diphenyl phosphate), SOL-DP, Israel ICL;

[0064] Plasticizer 4: Polyether ester plasticizer, oligomeric aromatic ether ester, A-55, number average molecular weight of 1500, Japanese DIC;

[0065] Plasticizer 5: Polyether ester plasticizer, oligomeric aliphatic ether ester, RS-735, number average molecular weight 850, ADEKA (Shanghai);

[0066] Plasticizer 6: Polyether plasticizer, PEG-2000, average molecular weight 2000, Aoki (Japan);

[0067] Plasticizer 7: Polyether plasticizer, PEG-400, average molecular weight 400, BASF (Germany);

[0068] Plasticizer 8: Polyether plasticizer, PEG-4000, average molecular weight 4000, Lotte (South Korea);

[0069] Plasticizer 9: Diisobutyl phthalate, commercially available;

[0070] Plasticizer 10: Cellulose acetate (butyl acetate), commercially available;

[0071] Glass fiber 1: average diameter 7μm, ECS7-4.5-T436S, Taishan Glass Fiber Co., Ltd.;

[0072] Glass fiber 2: average diameter 10μm, ECS10-4.5-T436H, Taishan Glass Fiber Co., Ltd.;

[0073] Glass fiber 3: average diameter 13μm, ECS13-4.5-534A, Jushi Group Co., Ltd.;

[0074] Toughening agent: Ethylene-acrylate-glycidyl methacrylate terpolymer, commercially available;

[0075] Antioxidant: Antioxidant 1010, commercially available.

[0076] Lubricant: Polyethylene wax, commercially available;

[0077] The toughening agents, antioxidants, and lubricants used in the parallel experiments of the examples and comparative examples were consistent.

[0078] Examples 1-20 and Comparative Examples 1-5

[0079] The component contents (parts by weight) of Examples 1-20 and Comparative Examples 1-5 of the present invention are shown in Tables 1-2;

[0080] Table 1

[0081]

[0082]

[0083] Table 2

[0084]

[0085]

[0086] The preparation methods of Examples 1-20 and Comparative Examples 1-5 are as follows:

[0087] After drying, the raw materials are weighed and added to a mixer for uniform mixing. The mixture is then fed into a twin-screw extruder, with the feed rate adjusted to 600 kg / hour. The material is extruded, stretched, cooled, pelletized, and dried to obtain the PBT composite material. The drying process for the PBT resin involves drying it at 130°C for 5 hours until the moisture content is below 0.03%. The parameters of the twin-screw extruder are as follows: the screw temperatures from the feed port to the die head are 230°C, 240°C, 240°C, 250°C, 260°C, 250°C, 240°C, 230°C, and 220°C, respectively; the screw speed is 400 rpm.

[0088] Example of effect

[0089] The effectiveness examples of this invention verify the performance of the products prepared in Examples 1-20 and Comparative Examples 1-5; test samples (0.4 mm thick) were prepared by injection molding according to the corresponding standards; the test items included the following aspects:

[0090] 1. Tensile strength was tested according to ISO 527-1-2012 standard;

[0091] 2. The notched impact strength of the cantilever beam was tested according to ISO 180-2007 standard;

[0092] 3. Flame retardant performance is tested according to UL 94-1985 standard;

[0093] 4. Mass of Material Adhering to the Melt Analyzer Wall: An evaluation method for the material adhering to the melt analyzer wall is designed. The mass of the material adhering to the wall refers to the mass of material remaining on the inner wall of the melt after it has flowed through the melt analyzer. It can reflect the material's ability 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 analyzer and the die. Weigh a fixed mass of granules m1 and place it in the melt analyzer. After 4 minutes, extrude the sample and weigh it, recording the weight as m2. Then, the mass of the material remaining in the melt analyzer m3 = m1 - m2, and the mass of the material adhering to the wall of the melt analyzer m5 = m3 - the material in the die m4. Considering that the mass of the material in the die m4 is inconvenient... Weighing was performed, 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 that it is caused by the mass difference of the wall-mounting material. Based on this, we can compare and evaluate the existing formula. According to the above method, we take 3 measurements each time and take the average value.

[0094] 5. Actual injection molding black spots: The frequency of actual injection molding black spots in the material is verified during actual injection molding. That is, after injection molding, parts with black spots are manually selected. The frequency calculation result = number of parts with black spots / total number of parts, and the result is in ppm.

[0095] The test results are shown in Table 3.

[0096] Table 3

[0097]

[0098]

[0099] As can be seen from Table 3, when the technical solution of this invention is adopted, the resulting product has excellent comprehensive effects. It not only meets the flame retardant requirements of thin-walled products, but also has excellent mechanical properties. Furthermore, the resulting product has less material residue on the melt indexer and fewer black spots in actual injection molding. Specifically, the resulting product has a flame retardant rating of V-0, a tensile strength of over 123 MPa, and an impact strength of 10.4 kJ / m. 2 The above results indicate that the mass of material adhering to the melt indexer is below 0.226g, and the actual injection molding black spot content is below 36ppm.

[0100] As can be seen from Examples 1-8, the mass fraction of the components added to the PBT composite material affects the product's performance, and the mass ratio of PBT resin to plasticizer also affects the product's performance. When the mass ratio of PBT resin to plasticizer is further optimized to (19-28):0.3, the resulting product has better overall performance, a flame retardant rating of V-0, a tensile strength of over 130 MPa, and an impact strength of 11.2 kJ / m. 2 The above indicates that the mass of material adhering to the melt indexer is below 0.215g, and the actual injection molding black spots are below 20ppm.

[0101] As can be seen from Example 1 and Comparative Example 1, when the plasticizer of the present invention is not added, the mass of the melt flow indexer wall-mounted material of the obtained product reaches 0.236g, and the actual injection molding black spot rate reaches 92ppm. Compared with Example 1, the melt flow indexer wall-mounted material mass increases by 12.92%, and the actual injection molding black spot frequency increases by 4.1%. As can be seen from Example 1 and Comparative Example 2, when the mass fraction of the plasticizer is not within the range given by the present invention, the overall performance of the obtained product decreases significantly. Compared with Example 1, the melt flow indexer wall-mounted material mass of the product in Comparative Example 2 increases by 13.88%, and the actual injection molding black spot frequency increases by 3.9 times.

[0102] As can be seen from Examples 1, 9-10, and Comparative Example 3, the end carboxyl group content of PBT resin significantly affects the overall performance of the product. When the end carboxyl group content of PBT resin is further selected to be 7-19 mol / t, the resulting product exhibits superior overall performance, achieving a flame retardancy rating of V-0, a tensile strength exceeding 132 MPa, and an impact strength of 10.8 kJ / m. 2 The above results show that the mass of the melt flow indexer wall-mounted material is below 0.215g, and the actual injection molding black spots are below 21ppm. When the PBT resin end carboxyl group content selected in Comparative Example 3 is not within the range given in this invention, compared with Example 1, the mass of the melt flow indexer wall-mounted material of the product increases by 13.88%, and the frequency of actual injection molding black spots increases by 4.4 times.

[0103] As can be seen from Examples 1 and 11, the system provided by the present invention achieves excellent results for both halogenated and halogen-free flame retardants.

[0104] As can be seen from Examples 1, 12-18 and Comparative Examples 4-5, the type of plasticizer significantly affects the overall performance of the product of the present invention. When the selected plasticizer is not the phosphate ester plasticizer, polyether plasticizer or polyether ester plasticizer described in the present invention, the overall performance of the obtained product decreases significantly. Compared with Example 1, the melt indexer wall material mass of the product 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.

[0105] As can be seen from Examples 1 and 19-20, the diameter of the alkali-free glass fiber also has a significant impact on the performance of the product. When the diameter of the alkali-free glass fiber is further selected to be 7-10μm, the actual injection molding black spot frequency of the product is lower, below 20ppm.

[0106] Finally, it should be noted that the above embodiments are used to illustrate the technical solutions of the present invention and not 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 modifications or equivalent substitutions can be made to the technical solutions of the present invention 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 weight: 30-60 parts PBT resin, 10-30 parts flame retardant, 0.2-1.2 parts plasticizer, and 25-40 parts glass fiber; The plasticizer is at least one of phosphate ester plasticizers, polyether plasticizers, or polyether ester plasticizers; The PBT resin has a terminal carboxyl group content of 7-19 mol / t; The mass ratio of PBT resin to plasticizer is PBT resin:plasticizer = (19-28):0.3; The average diameter of the glass fiber is 6-13 μm.

2. The PBT composite material according to claim 1, characterized in that, The phosphate ester plasticizer is selected from at least one of resorcinol-bis(diphenyl phosphate), resorcinol bis[bis(2,6-dimethylphenyl) phosphate, bisphenol-A 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.

3. 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.

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

5. The PBT composite material according to claim 1, characterized in that, The PBT composite material also includes 0-4 parts toughening agent and 0-1 part processing aid; The toughening agent is at least one of the following: ethylene-acrylate-glycidyl methacrylate terpolymer, ethylene-acrylate binary copolymer, ethylene-vinyl acetate, and ethylene-octene copolymer grafted with glycidyl methacrylate. And / or, the processing aid is at least one of a lubricant and an antioxidant.

6. The method for preparing the PBT composite material according to any one of claims 1-5, characterized in that, The preparation method includes the following steps: weighing the dried raw materials and mixing them, feeding them into a twin-screw extruder, and extruding, stretching, cooling, pelletizing and drying to obtain PBT composite material.

7. The application of the PBT composite material as described in any one of claims 1-5 in ultra-thin electronic components.

8. The application of plasticizers in reducing black spots in injection molding of flame-retardant PBT composite materials, characterized in that, The plasticizer is at least one of phosphate ester plasticizers, polyether plasticizers, or polyether ester plasticizers; The PBT resin has a terminal carboxyl group content of 7-19 mol / t; The flame-retardant PBT composite material comprises the following components in parts by weight: 30-60 parts PBT resin, 10-30 parts flame retardant, 0.2-1.2 parts plasticizer, and 25-40 parts glass fiber; The mass ratio of PBT resin to plasticizer is PBT resin:plasticizer = (19-28):0.3; The average diameter of the glass fiber is 6-13 μm.

Images