PBT-based composite material and preparation method thereof

Abstract

The invention relates to a PBT-based composite material and a preparation method thereof. The PBT-based composite material is prepared from the following components in parts by mass: 40 to 55 parts of PBT resin; 5 to 10 parts of PET resin; 28 to 32 parts of alkali-free glass fiber; 8 to 15 parts of brominated flame retardant; 2 to 5 parts of a solid flame retardant synergist; 0.2 to 1 part of a liquid flame retardant synergist; 0.1 to 1 part of a lubricant; 0-5 parts of a toughening agent; the PBT-based composite material has the advantages of low floating fiber, low precipitation, enhanced flame retardance and excellent mechanical properties.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, in particular to a PBT-based composite material and a preparation method thereof. Background Art

[0002] Polybutylene terephthalate (PBT) has excellent toughness and fatigue resistance. It can be used to prepare various parts used in aerospace, automobile, electrical and electronic fields, realizing "plastic replacing steel". With the upgrading and transformation of industrial technology, the use of engineering plastics and modified plastics will further increase.

[0003] In traditional technology, in order to achieve the goal of "replacing steel with plastic", PBT products need to be modified. In the process of modifying PBT, glass fiber, flame retardant and some additives are usually added to improve the properties of PBT materials to achieve reinforcement, flame retardancy, toughening and other properties. However, in the injection molding process of the product, there are often problems such as serious floating fibers on the product surface, a lot of mold deposits during the injection molding process, and unidentified substances precipitating on the surface of the product after the injection molded product is placed for a period of time. As a result, the performance of the modified material is limited. At the same time, the surface of the injection molded sample will be rough and the fibers will float, affecting its use. In addition, during the continuous processing process, the mold needs to be cleaned regularly, which increases the production cost.

[0004] Therefore, it is necessary to optimize the traditional production technology and develop a PBT-based composite material with low floating fiber, low precipitation, low mold deposit, enhanced flame retardancy and excellent mechanical properties. Summary of the invention

[0005] Based on this, the present invention provides a PBT-based composite material with low floating fiber, low precipitation, low mold deposit, enhanced flame retardancy and excellent mechanical properties and a preparation method thereof.

[0006] In one aspect of the present invention, a PBT-based composite material is provided, wherein the PBT-based composite material comprises the following components in parts by mass:

[0007]

[0008]

[0009] The above-mentioned PBT-based composite material includes specific components and proportions, wherein the viscosity difference between the components and the alkali-free glass fiber can be reduced by coordinating the PET resin with the PBT resin, and flame retardants, lubricants and other additives are added to achieve enhanced flame retardant effects, and liquid flame retardant synergists are added to enable the raw materials to be more stably combined together and to wrap the small molecules in the raw materials. The specific components work synergistically through a specific proportion relationship, so that the PBT-based composite material can improve the tensile, impact resistance and other mechanical properties, achieve excellent flame retardancy and good fluidity, while reducing the precipitation of floating fibers and small molecules, thereby reducing the probability of surface precipitation problems.

[0010] The flame retardant performance of the above PBT-based composite material reaches the UL-94 standard 0.8mmV0 level, the tensile strength can reach more than 140MPa, and the notched impact strength reaches 7KJ / m 2 Above performance.

[0011] In some embodiments, the intrinsic viscosity of the PBT resin is 0.75 dL / g to 1.00 dL / g; and / or

[0012] The intrinsic viscosity of the PET resin is 0.60 dL / g to 0.75 dL / g.

[0013] It should be noted that the above-mentioned “intrinsic viscosity” is obtained by testing with reference to the GB / T 14190-2017 method.

[0014] In some embodiments, the diameter of the alkali-free glass fiber is 10 μm to 14 μm.

[0015] In some embodiments, the brominated flame retardant includes at least one of brominated epoxy resin, decabromodiphenylethane, and brominated polycarbonate; and / or

[0016] The solid flame retardant synergist comprises an antimony-containing flame retardant; and / or

[0017] The liquid flame retardant synergist comprises a liquid epoxy resin, and the epoxy equivalent of the liquid epoxy resin is 160 g / eq to 180 g / eq.

[0018] Liquid epoxy resin can make PBT resin and alkali-free glass fiber more compatible.

[0019] In some embodiments, the lubricant includes at least one of aliphatic carboxylic acid ester, erucic acid amide, polyethylene wax, and oxidized polyethylene wax; and / or

[0020] The toughening agent includes at least one of ethylene-acrylate binary copolymer, ethylene-vinyl acetate copolymer, and methyl methacrylate-butadiene-styrene copolymer.

[0021] In some of the embodiments, the other processing aids include at least one of an antioxidant, an anti-dropping agent and a black masterbatch, the antioxidant includes at least one of a phosphite antioxidant and a hindered phenol antioxidant; the anti-dropping agent includes at least one of polytetrafluoroethylene and its derivatives, and the black masterbatch is a PET carrier black masterbatch.

[0022] One aspect of the present invention provides a method for preparing the PBT-based composite material of the first aspect, comprising the following steps:

[0023] The components of the PBT-based composite material are mixed and extruded to prepare the PBT-based composite material.

[0024] In some embodiments, the step of mixing and extruding comprises the following steps:

[0025] Mixing the components of the raw materials of the PBT-based composite material except the alkali-free glass fiber to obtain a first mixture;

[0026] The first mixture is fed into a main feed scale of a twin-screw extruder for feeding, and the alkali-free glass fiber is fed into another separate feed scale for feeding, and then extrusion treatment is performed.

[0027] Feeding the alkali-free glass fiber into other separate feeding scales for separate feeding can reduce the probability of the twin screw extruder damaging the alkali-free glass fiber.

[0028] In some of the embodiments, in the direction from the feeding port of the twin-screw extruder to the head, the temperatures in each section are 90±10℃, 230±10℃, 230±10℃, 225±10℃, 220±10℃, 220±10℃, 220±10℃, 225±10℃, 230±10℃ and 240±10℃ respectively.

[0029] Further controlling the extrusion temperature can reduce the probability of excessive decomposition of small molecules due to heat, resulting in surface precipitation.

[0030] The third aspect of the present invention provides a PBT-based composite material, wherein the PBT-based composite material is prepared by the preparation method of the PBT-based composite material according to the second aspect. DETAILED DESCRIPTION

[0031] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively below. Preferred embodiments of the present invention are provided in the specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0033] Unless otherwise specified or incompatible herewith, the terms and phrases used herein shall have the following meanings:

[0034] The terms "and / or", "or / and", and "and / or" used herein include any one of two or more related listed items, and also include any and all combinations of the related listed items, wherein the any and all combinations include any combination of two related listed items, any more related listed items, or all related listed items. It should be noted that when at least three items are connected by at least two conjunctions selected from "and / or", "or / and", and "and / or", it should be understood that in the present application, the technical solution undoubtedly includes technical solutions connected by "logical and", and also undoubtedly includes technical solutions connected by "logical or".

[0035] In the present invention, when it comes to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values ​​in the numerical interval is considered to be continuous, and includes the two numerical endpoints (i.e., the minimum value and the maximum value) of the numerical interval, and each numerical value between the two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to the integers in the numerical interval, including the two endpoint integers of the numerical range, and each integer between the two endpoints, is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical range disclosed herein should be understood to include any and all sub-ranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. "Numerical interval" allows broadly including numerical interval types such as percentage intervals, ratio intervals, and ratio intervals.

[0036] The temperature parameters in the present invention, if not specifically limited, are allowed to be either constant temperature treatment or to vary within a certain temperature range. It should be understood that the constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. Fluctuations within the range of ±5°C, ±4°C, ±3°C, ±2°C, ±1°C are allowed. In the present invention, the term "room temperature" or "normal temperature" generally refers to 4°C to 35°C, for example, 20°C ±5°C.

[0037] The mass or weight of the relevant components mentioned in the description of the embodiments of the present invention may not only refer to the specific content of each component, but also indicate the proportional relationship of the mass or weight between the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the description of the embodiments of the present invention, it is within the scope disclosed in the description of the embodiments of the present invention. Specifically, the mass or weight described in the description of the embodiments of the present invention may be units known in the chemical industry such as μg, mg, g, and kg.

[0038] As described in the background technology, in the process of modifying PBT with traditional technology, glass fiber, flame retardant and some additives are usually added to improve the properties of PBT materials. However, in the injection molding process of traditional technology, problems such as floating fibers on the product surface often occur.

[0039] Research has found that the above problems are mainly caused by the following aspects: (1) PBT and glass fiber have poor compatibility, which makes it impossible for the two to be effectively bonded together; (2) The viscosity of PBT and glass fiber is very different, which leads to a tendency for the two to separate during the flow process. When the separation force is greater than the bonding force, detachment will occur, and the glass fiber will float to the outer layer and leak out; (3) The existence of shear force will not only lead to differences in local viscosity, but also damage the interface layer on the surface of the glass fiber. The smaller the melt viscosity, the more damaged the interface layer, and the smaller the bonding force on the glass fiber. When the viscosity is reduced to a certain extent, the glass fiber will break free from the constraints of the PBT resin matrix and gradually accumulate on the surface and expose; (4) Influence of mold temperature. Due to the low temperature of the mold surface, the light and fast-condensing glass fiber is instantly frozen. If it cannot be fully surrounded by the melt in time, it will be exposed to form "floating fibers"; (5) There are substances precipitated on the surface of the product and mold scale. The precipitation is caused by the excessive small molecule content of the material itself or the poor thermal stability of the material. The excessive content of small molecules decomposed during the extrusion or injection molding process of the product causes challenges.

[0040] Based on this, the technicians of the present invention obtained the technical solution of the present application after a large number of creative experiments, providing a composite material with low floating fibers, low precipitation, excellent mechanical properties and enhanced flame retardancy.

[0041] An embodiment of the present invention provides a PBT-based composite material, which includes the following components in terms of mass fraction:

[0042]

[0043]

[0044] It can be understood that PBT resin is polybutylene terephthalate; PET resin is polyethylene terephthalate.

[0045] The above-mentioned PBT-based composite material includes specific components and proportions, wherein PBT resin coordinates PET resin to reduce the viscosity difference between the components and alkali-free glass fiber, and flame retardants, lubricants and other additives are added to achieve enhanced flame retardant effects, and liquid flame retardant synergists are added to enable the raw materials to be more stably combined together and to wrap the small molecules in the raw materials. The specific components work synergistically through a specific proportion relationship, so that the PBT-based composite material can reduce the precipitation of floating fibers and small molecules while achieving high mechanical properties, excellent flame retardancy and good fluidity, thereby reducing the probability of surface precipitation problems.

[0046] In some embodiments, the mass fractions of the PBT resin include: 40 parts, 41 parts, 42 parts, 43 parts, 44 parts, 45 parts, 46 parts, 47 parts, 48 ​​parts, 49 parts, 50 parts, 51 parts, 52 parts, 53 parts, 54 parts, 55 parts, and every value between the minimum and maximum values, or a range consisting of any two values.

[0047] In some embodiments, the intrinsic viscosity of the PBT resin is 0.75 dL / g to 1.00 dL / g.

[0048] In some embodiments, the mass fraction of the PET resin includes 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, and every value between the minimum and maximum values, or a range consisting of any two values.

[0049] In some embodiments, the intrinsic viscosity of the PET resin is 0.60 dL / g to 0.75 dL / g.

[0050] Adjusting the intrinsic viscosity of the PBT resin and / or PET resin can further reduce the viscosity difference between the components and the alkali-free glass fiber, thereby reducing the probability of surface precipitation problems.

[0051] It should be noted that the above-mentioned “intrinsic viscosity” is obtained by testing with reference to the GB / T 14190-2017 method.

[0052] In some embodiments, the mass fraction of the alkali-free glass fiber includes: 28 parts, 29 parts, 30 parts, 31 parts, 32 parts, and each value between the minimum and maximum values, or a range consisting of any two values.

[0053] In some embodiments, the diameter of the alkali-free glass fiber is 10 μm to 14 μm.

[0054] Alkali-free glass fiber is glass fiber treated with coupling agent. It has high tensile strength and good electrical insulation. By adjusting the diameter and length of alkali-free glass fiber, while maintaining excellent reinforcement effect, it improves dispersion, further improves the reinforcement effect and reduces the probability of floating fibers.

[0055] In some of the embodiments, the mass fractions of the brominated flame retardant include: 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, and every value between the minimum and maximum values, or a range consisting of any two values.

[0056] In some embodiments, the mass fraction of the solid flame retardant synergist includes: 2 parts, 3 parts, 4 parts, 5 parts, and any value between the minimum and maximum values, or a range consisting of any two values.

[0057] In some embodiments, the mass fraction of the liquid flame retardant synergist includes: 0.2 part, 0.3 part, 0.4 part, 0.5 part, 0.6 part, 0.7 part, 0.8 part, 0.9 part, 1 part, and every value between the minimum and maximum values, or a range consisting of any two values.

[0058] In some embodiments, the brominated flame retardant includes at least one of brominated epoxy resin, decabromodiphenylethane, and brominated polycarbonate.

[0059] In some embodiments, the solid flame retardant synergist comprises an antimony-containing flame retardant; optionally, the solid flame retardant synergist comprises antimony powder.

[0060] In some embodiments, the liquid flame retardant synergist includes a liquid epoxy resin, and the epoxy equivalent of the liquid epoxy resin is 160 g / eq to 180 g / eq.

[0061] Brominated flame retardants have the characteristics of good thermal stability, high bromine content, and are not easy to precipitate. Brominated flame retardants and antimony-containing flame retardants have very good synergistic flame retardant effects, which can further reduce the probability of decomposition due to heat during the addition process.

[0062] In some embodiments, the mass fraction of the lubricant includes: 0.1 part, 0.2 part, 0.3 part, 0.4 part, 0.5 part, 0.6 part, 0.7 part, 0.8 part, 0.9 part, 1 part, and every value between the minimum and maximum values, or a range consisting of any two values.

[0063] In some embodiments, the lubricant includes at least one of aliphatic carboxylic acid ester, erucamide, polyethylene wax, and oxidized polyethylene wax.

[0064] In some embodiments, the mass fraction of the toughening agent includes: 0, 1, 2, 3, 4, 5, and any value between the minimum and maximum values, or a range consisting of any two values.

[0065] In some embodiments, the toughening agent includes at least one of ethylene-acrylate copolymer, ethylene-vinyl acetate copolymer, and methyl methacrylate-butadiene-styrene copolymer.

[0066] In some embodiments, the mass fractions of the other processing aids include: 1 part, 2 parts, 3 parts, and any value between the minimum and maximum values, or a range consisting of any two values.

[0067] In some of the embodiments, other processing aids include at least one of an antioxidant, an anti-dropping agent and a black masterbatch; optionally, the antioxidant includes at least one of a phosphite antioxidant and a hindered phenol antioxidant; the anti-dropping agent includes at least one of polytetrafluoroethylene and its derivatives, and the black masterbatch is a PET carrier black masterbatch.

[0068] Another embodiment of the present invention provides a method for preparing the above-mentioned PBT-based composite material, comprising the following step S10.

[0069] Step S10: mixing and extruding raw materials of the PBT-based composite material to prepare the PBT-based composite material.

[0070] In some embodiments, the mixed extrusion step includes the following steps S11 to S12.

[0071] Step S11: Mix components of the PBT-based composite material except the alkali-free glass fiber to obtain a first mixture.

[0072] The specific steps include: drying the PBT resin and the PET resin at 120° C. to 140° C. for 2 h to 4 h, then mixing them together with the toughening agent through a high-speed mixer, adding a liquid flame retardant synergist and mixing them again through a high-speed mixer, and then adding a brominated flame retardant, a solid flame retardant synergist, a lubricant and other processing aids into the high-speed mixer again for mixing to obtain a first mixture.

[0073] It should be noted that the above-mentioned “components of the PBT-based composite material” can be understood as raw materials corresponding to the components of the PBT-based composite material.

[0074] Step S12: feeding the first mixture into a main feed scale of a twin-screw extruder for feeding, feeding the alkali-free glass fiber into another separate feed scale for feeding, and then performing extrusion processing.

[0075] Feeding the alkali-free glass fiber into other separate feeding scales for separate feeding can reduce the probability of the twin screw extruder damaging the alkali-free glass fiber.

[0076] It can be understood that during the extrusion process, the raw materials will undergo melting and plasticization, kneading and mixing, and then be extruded from the extrusion port.

[0077] In some embodiments, after the mixing and extruding step, the extruded product is further subjected to the steps of cooling, air-drying, pelletizing, collecting, etc.

[0078] In some of the embodiments, in the direction from the feeding port to the head of the twin-screw extruder, the temperatures in each section are 90±10℃, 230±10℃, 230±10℃, 225±10℃, 220±10℃, 220±10℃, 220±10℃, 225±10℃, 230±10℃ and 240±10℃, respectively.

[0079] Further controlling the extrusion temperature can reduce the probability of excessive decomposition of small molecules due to heat, resulting in surface precipitation.

[0080] In some of the embodiments, the extruder screw speed of the twin-screw extruder is 300 rpm to 400 rpm, and the feeding rate is 500 kg / hour to 800 kg / hour.

[0081] In some of the embodiments, the twin-screw extruder is a KraussMaffei Φ50 twin-screw extruder.

[0082] Another aspect of the present invention provides a PBT-based composite material, which is prepared by the above-mentioned preparation method of the PBT-based composite material.

[0083] The above-mentioned PBT-based composite material has the characteristics of low floating fiber, low precipitation, enhanced flame retardancy and excellent mechanical properties, and can reduce production costs, which is conducive to large-scale industrial applications.

[0084] Some embodiments of the present invention further provide an electronic and electrical component material, which includes the PBT-based composite material of the first aspect or the PBT-based composite material prepared by the preparation method of the PBT-based composite material of the second aspect.

[0085] The present invention will be described below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments. It should be understood that the attached claims summarize the scope of the present invention. Under the guidance of the concept of the present invention, those skilled in the art should realize that certain changes made to the various embodiments of the present invention will be covered by the spirit and scope of the claims of the present invention.

[0086] The following are specific embodiments.

[0087] The sources of the main raw materials used in each embodiment and comparative example are described as follows:

[0088] PBT resin: PBT KH2083, China Kanghui New Materials, the intrinsic viscosity of the resin is 0.83dL / g.

[0089] PET resin: PET FG-604, Yizheng Chemical, China, the intrinsic viscosity of the resin is 0.67 dL / g.

[0090] Brominated flame retardants: Brominated epoxy resin CR-225K, Borida; Decabromodiphenylethane SAYTEX 8010, Albemarle, USA.

[0091] Solid synergistic flame retardant: antimony powder, specification 99.8%, flash star.

[0092] Toughening agent: ethylene-butyl acrylate copolymer, brand W5A, Coase Chemical Co., Ltd.

[0093] Liquid flame retardant synergist: liquid epoxy resin, NPEF170, Nanya Electronic Technology Co., Ltd.

[0094] Lubricant: Ester lubricant LOXIOL P 861 / 3.5, Corning.

[0095] Alkali-free glass fiber: ECS13-4.5-534A (glass fiber diameter: 13μm, Jushi Group); ECS10-3.0-534A (glass fiber diameter: 10μm, Jushi Group).

[0096] Other processing aids: Antioxidant: Irganox1010, Irgafos168, BASF; Anti-drop agent: FS-257, Hannano; Black masterbatch: MBB1411, Cabot.

[0097] Example 1

[0098] (1) PBT resin and PET resin are dried at 120° C. for 4 hours, and then mixed with a toughening agent through a high-speed mixer, and then a liquid flame retardant synergist is added and mixed again through a high-speed mixer, and then a brominated flame retardant, a solid flame retardant synergist, a lubricant and other processing aids are added to the high-speed mixer again and mixed to obtain a first mixture.

[0099] (2) The first mixture is fed into the main feed scale of the twin-screw extruder for feeding, and the alkali-free glass fiber is fed into another separate feed scale for feeding, and then extrusion treatment is performed: melt plasticization, kneading and mixing, extrusion, cooling, air drying, pelletizing, and collection are performed in sequence to obtain a PBT-based composite material. The twin-screw extruder adopts a KraussMaffei Φ50 twin-screw extruder, the extruder screw speed is 400rpm, the feeding rate is 500kg / hour, and the temperatures of each section from the feeding port of the twin-screw extruder to the die are 90°C, 230°C, 230°C, 225°C, 220°C, 220°C, 220°C, 225°C, 230°C and 240°C, respectively.

[0100] The types and weight fractions of raw materials are specifically shown in Table 1.

[0101] Embodiments 2 to 6

[0102] Examples 2 to 6 are basically the same as Example 1, except that the raw material ratio is different from that of Example 1, as shown in Table 1 for details.

[0103] The other steps and conditions are the same as those in Example 1.

[0104] Table 1

[0105]

[0106] Note: “ / ” means the raw material does not exist.

[0107] Comparative Examples 1 to 4

[0108] Comparative Examples 1 to 4 are substantially the same as Example 1, except that the raw material ratios are different from those in Example 1. For details, see Table 2.

[0109] The other steps and conditions are the same as those in Example 1.

[0110] Table 2

[0111]

[0112]

[0113] Performance test: The following performance tests were performed on the PBT-based composite materials obtained in the above embodiments and comparative examples:

[0114] (1) Floating fiber verification and rating: The prepared PBT-based composite material was subjected to injection molding process using a Dongguan Fuqiangxin machine (model HN-125): material temperature 260-280°C, medium-high speed injection speed, mold temperature 100°C, injection molding into a 60×60×1.5mm sample, and the floating fiber on the sample was observed and visually graded:

[0115] Level 1: No floating fibers, the surface of the sample is smooth, and it feels smooth when touched lightly with your fingers;

[0116] Level 2: There are few floating fibers, the surface of the sample is smooth, and there is a slight sense of resistance when gently touched with a finger;

[0117] Level 3: The floating fiber is average, silver streaks appear on the surface of the sample, and a slight prickling feeling will appear when you touch it with your fingers;

[0118] Level 4: There is a lot of precipitation, there are obviously more floating fibers on the surface of the sample, and silver streaks are serious.

[0119] (2) Precipitation Verification Rating - Referring to the above injection molding process, the prepared PBT-based composite material was injection molded into a 60×60×1.5 mm sample. The sample was placed in an oven at 120°C for 48 hours, taken out, cooled to room temperature, and the precipitation on the surface of the material was observed. The precipitation was visually graded:

[0120] Level 1: No precipitation, no precipitation can be seen on the surface of the sample, and no change can be seen on the black paper after wiping it with black paper;

[0121] Level 2: Less precipitation, no precipitation can be seen on the surface of the sample, and a little precipitation can be seen on the black paper when wiped;

[0122] Level 3: The precipitation is general, a small amount of precipitation can be seen on the surface of the sample, and more precipitation can be seen on the black paper after wiping it with black paper;

[0123] Level 4: There is a lot of precipitation, and many precipitates are clearly seen on the surface of the sample.

[0124] (3) Mold Deposits Verification and Rating - The prepared PBT-based composite materials were subjected to injection molding process using a Dongguan Fuqiangxin machine (model HN-125): material temperature 260°C to 280°C, injection speed medium to high, mold temperature 100°C, continuous injection for 2 hours, visual observation of mold deposits, and visual mold deposit classification:

[0125] Level 1: There is very little mold scale, and no mold scale precipitation can be seen at the mold scale collection point. When wiped with black paper, there is no change on the black paper, and there is no mold scale in other places of the mold;

[0126] Level 2: There is less mold scale, and no mold scale precipitation can be seen at the mold scale collection area. When wiped with black paper, there is a little mold scale precipitation on the black paper, and there is no mold scale in other places of the mold;

[0127] Level 3: The mold scale is general. Slight mold scale precipitation can be seen at the mold scale collection area. Wipe it with black paper. There are more precipitations on the black paper. There is no mold scale in other places of the mold.

[0128] Level 4: There is a lot of mold scale. There are a lot of mold scale precipitates in the mold scale collection area, and there is obvious mold scale in other places of the mold.

[0129] (4) Other performance tests: The PBT-based composite material was dried at 140°C for 4 hours; the test specimens were prepared by injection molding according to the corresponding standards, the tensile strength was tested according to ISO 527-2012 standard, the impact strength was tested according to ISO 180A notch standard, and the flame retardant grade was tested as follows, using the UL94-2016 combustion standard, the standard strip specimen size was 125±5mm long, 13.0±0.5mm wide and 0.8±0.15mm thick. Each group of 10 test specimens were treated at 23±2°C, 50±5% for 48 hours.

[0130] Please see Table 3 for specific test results.

[0131] Table 3

[0132]

[0133] Comparative analysis of the performance test results of each embodiment and comparative example in Table 3 shows that: in comparative example 1, no flame retardant or synergistic flame retardant is added. Although the precipitation and mold deposit precipitation of the composite material obtained are very low and the rating can reach level 1, the flame retardant grade does not meet the relevant requirements and the mechanical properties are also low; in comparative example 2, although brominated flame retardants and synergistic flame retardants are added, the flame retardant performance can reach level V, but the precipitation rating and mold deposit precipitation level are significantly reduced, the precipitate is more, reaching level 3, and the floating fiber level also reaches level 3; in comparative example 3, a small amount of bromine flame retardant and synergistic flame retardant are added, and the flame retardant performance can reach level V, but the precipitation rating and mold deposit precipitation level are significantly reduced, the precipitate is more, reaching level 3, and the floating fiber level also reaches level 3. The amount of PET resin can improve the tensile and notched impact properties, but the relief of the floating fiber problem is limited; the floating fiber, precipitation, mold scale precipitation and other problems in Example 4 have not been effectively improved; while the PBT-based composite materials prepared by Examples 1 to 6 of the technical method of the present application have high mechanical properties and excellent flame retardancy, and can reduce floating fibers and surface precipitation, precipitation and mold scale precipitation grades reach Grade 1, flame retardancy reaches UL-94 standard V0 grade, tensile strength can reach more than 140MPa, and notched impact strength reaches 7KJ / m 2 above.

[0134] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0135] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A PBT-based composite material, characterized in that: The PBT-based composite material comprises the following components in parts by mass:

2. The PBT-based composite material according to claim 1, characterized in that: The intrinsic viscosity of the PBT resin is 0.75 dL / g to 1.00 dL / g; and / or The intrinsic viscosity of the PET resin is 0.60 dL / g to 0.75 dL / g.

3. The PBT-based composite material according to any one of claims 1 to 2, characterized in that: The diameter of the alkali-free glass fiber is 10 μm to 14 μm.

4. The PBT-based composite material according to any one of claims 1 to 2, characterized in that: The brominated flame retardant comprises at least one of brominated epoxy resin, decabromodiphenylethane, and brominated polycarbonate; and / or The solid flame retardant synergist comprises an antimony-containing flame retardant; and / or The liquid flame retardant synergist comprises a liquid epoxy resin, and the epoxy equivalent of the liquid epoxy resin is 160 g / eq to 180 g / eq.

5. The PBT-based composite material according to any one of claims 1 to 2, characterized in that: The lubricant comprises at least one of aliphatic carboxylic acid ester, erucamide, polyethylene wax, and oxidized polyethylene wax; and / or The toughening agent includes at least one of ethylene-acrylate binary copolymer, ethylene-vinyl acetate copolymer, and methyl methacrylate-butadiene-styrene copolymer.

6. The PBT-based composite material according to any one of claims 1 to 2, characterized in that: The other processing aids include at least one of an antioxidant, an anti-dropping agent and a black masterbatch, the antioxidant includes at least one of a phosphite antioxidant and a hindered phenol antioxidant; the anti-dropping agent includes at least one of polytetrafluoroethylene and its derivatives, and the black masterbatch is a PET carrier black masterbatch.

7. The method for preparing a PBT-based composite material according to any one of claims 1 to 6, characterized in that: The steps include: The components of the PBT-based composite material are mixed and extruded to prepare the PBT-based composite material.

8. The method for preparing the PBT-based composite material according to claim 7, characterized in that: The step of mixing and extruding comprises the following steps: Mixing the components of the raw materials of the PBT-based composite material except the alkali-free glass fiber to obtain a first mixture; The first mixture is fed into a main feed scale of a twin-screw extruder for feeding, and the alkali-free glass fiber is fed into another separate feed scale for feeding, and then extrusion treatment is performed.

9. The method for preparing the PBT-based composite material according to claim 8, characterized in that: In the direction from the feeding port of the twin-screw extruder to the head, the temperatures in each section are 90±10℃, 230±10℃, 230±10℃, 225±10℃, 220±10℃, 220±10℃, 220±10℃, 225±10℃, 230±10℃ and 240±10℃ respectively.

10. A PBT-based composite material, characterized in that: The PBT-based composite material is prepared by the preparation method of the PBT-based composite material according to any one of claims 7 to 9.

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