PBT (Polybutylene Terephthalate) composite material with low abrasion and low free glass fibers and preparation method of PBT composite material

Abstract

The invention relates to a low-abrasion low-free-glass-fiber PBT composite material and a preparation method thereof, and relates to the technical field of polymer composites.The low-abrasion low-free-glass-fiber PBT composite material is prepared from 50-80 parts of PBT resin, 10-40 parts of glass fibers, 0.1-0.5 part of peroxide initiator, 0.1-0.8 part of accelerant containing carbon-carbon double bonds, 1-5 parts of low-abrasion agent and 0.2-2 parts of silane coupling agent containing carbon-carbon double bonds; the mass ratio of the polytetrafluoroethylene to the molybdenum disulfide is (1-3): 1, the average particle size of the polytetrafluoroethylene is 0.1-5 microns, and the size of the molybdenum disulfide is 0.1-5 microns. The reinforced PBT composite material with high glass fiber content prepared by the invention shows excellent wear resistance and low free glass fiber content, and is suitable for producing low-voltage electric appliance products with contacts.

Description

Technical Field

[0001] This application relates to the field of polymer composite materials technology, and in particular to a low-wear, low-free-glass fiber PBT composite material and its preparation method. Background Technology

[0002] Polybutylene terephthalate (PBT) is widely used in automobiles, electronics, and precision instruments due to its excellent mechanical properties, electrical insulation, and processing performance. To further improve its strength and rigidity, it is often modified with reinforcing materials such as glass fiber. However, glass fiber reinforced PBT is prone to generating debris during friction and has poor wear resistance. In particular, during injection molding, abrupt shear changes and gate geometry changes cause localized disorientation of the glass fibers, resulting in free fiber microfilaments. This manifests as "glass fiber fuzz" or "burrs" at the injection gate, which easily fall off after impact or friction. These gate debris not only affect the appearance of the product but also severely limit its use in the production of low-voltage electrical products with contacts, such as electronic switches. Furthermore, the free glass fibers in PBT can also cause surface roughness, affecting secondary processing such as coating and electroplating. In existing technologies, the above problems are often alleviated by adding lubricants and improving the dispersion of glass fibers, but the effect is limited, especially in systems with high glass fiber content, it is still difficult to achieve both low wear and good appearance performance. Summary of the Invention

[0003] The purpose of this application is to address the shortcomings of existing technologies in preparing high-glass fiber reinforced PBT composites, which struggle to balance low wear and good appearance performance. Therefore, this application proposes a low-wear, low-free-glass-fiber PBT composite material and its preparation method. This application combines polytetrafluoroethylene (PTFE) and molybdenum disulfide (MoD) of specific particle sizes in a certain proportion. Through their synergistic effect, the surface friction coefficient of the high-glass fiber reinforced PBT composite material can be significantly reduced. Simultaneously, free radicals in the composite material form C-C bonds with a promoter containing carbon-carbon double bonds. These C-C bonds form a micro-crosslinked structure that improves the wear resistance of the material matrix, thus reducing wear. Furthermore, a silane coupling agent containing carbon-carbon double bonds bonds with the glass fibers, reducing the content of unbonded free glass fibers in the high-glass fiber reinforced PBT composite material. Consequently, during the injection molding process, the burrs at the injection gate of the prepared high-glass fiber reinforced PBT composite material are significantly reduced.

[0004] In a first aspect, the PBT composite material with low abrasion and low free glass fiber provided in this application adopts the following technical solution: the raw materials of the PBT composite material include the following components in parts by weight: 50-80 parts of PBT resin, 10-40 parts of glass fiber, 0.1-0.5 parts of peroxide initiator, 0.1-0.8 parts of accelerator containing carbon-carbon double bonds, 1-5 parts of low abrasion agent and 0.2-2 parts of silane coupling agent containing carbon-carbon double bonds; the low abrasion agent contains polytetrafluoroethylene and molybdenum disulfide in a mass ratio of 1-3:1, wherein the average particle size of the polytetrafluoroethylene is 0.1-5 μm and the size of the molybdenum disulfide is 0.1-5 μm.

[0005] For example, in the raw materials of the PBT composite material, the PBT resin can be 50 parts, 55 parts, 60 parts, 63.1 parts, 64.4 parts, 64.5 parts, 64.6 parts, 65.3 parts, 68.9 parts, 75 parts, or 80 parts; the glass fiber can be 10 parts, 20 parts, 30 parts, or 40 parts; the peroxide initiator can be 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, or 0.5 parts; the accelerator containing carbon-carbon double bonds can be 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, or 0.8 parts; the low-wear agent can be 1 part, 2 parts, 3 parts, 3.6 parts, 4 parts, or 5 parts; and the silane coupling agent containing carbon-carbon double bonds can be 0.2 parts, 0.5 parts, 0.6 parts, 0.7 parts, 1 part, 1.5 parts, or 2 parts.

[0006] For example, in the low-wearing agent, the mass ratio of polytetrafluoroethylene to molybdenum disulfide can be 1:1, 1.5:1, 2:1, 2.5:1 or 3:1.

[0007] Optionally, the accelerator may also contain a triazine ring.

[0008] Through the above technical solution, the triazine ring has a symmetrical aromatic heterocyclic structure with high rigidity and stability, which can resist deformation and wear caused by external forces and improve the wear resistance of composite materials.

[0009] Specifically, the accelerator is selected from one or more of triallyl isocyanurate (TAIC), trimethylallyl isocyanurate (TMAIC), and triallyl cyanurate (TAC).

[0010] Further optionally, the promoter is triallyl isocyanurate and / or triallyl cyanurate.

[0011] By using the above technical solution, triallyl isocyanurate and / or triallyl cyanurate are selected as accelerators, which can react with the free radicals generated by PBT segments to form CC bonds, and further form a structurally stable micro-crosslinked structure inside the glass fiber reinforced PBT composite material. This stable micro-crosslinked structure improves the wear resistance of the material matrix, so that the wear amount of the prepared high glass fiber reinforced PBT composite material is less than 7.6 mg.

[0012] Specifically, the accelerator may be a composition of triallyl isocyanurate and triallyl cyanurate, wherein the mass ratio of triallyl isocyanurate to triallyl cyanurate is 2:1, or it may be triallyl isocyanurate or triallyl cyanurate; in a preferred embodiment, the accelerator is triallyl isocyanurate or triallyl cyanurate.

[0013] Optionally, the low-wear agent contains polytetrafluoroethylene and molybdenum disulfide in a mass ratio of 2:1, wherein the average particle size of the polytetrafluoroethylene is 1~2.9 μm and the size of the molybdenum disulfide is 0.2~5 μm.

[0014] Through the above technical solution, the mass ratio of polytetrafluoroethylene (PTFE) and molybdenum disulfide (MoD) in the low-wear agent was continuously optimized and finally determined to be 2:1. When the mass ratio of PTFE to MoD is 2:1, it has the following synergistic effects: 1) PTFE has extremely low surface energy, so it first spreads rapidly on the material surface to form a film, reducing the coefficient of friction. At the same time, MoD embeds itself in the defects of the PTFE film in the system, forming a second enrichment layer. The two films complement each other in space and have a synergistic effect due to their superimposed functions; 2) During the friction process, MoD is continuously transported to the surface of the material to replenish the worn PTFE film in situ. Conversely, the PTFE wear debris can cover the oxidation active sites of MoD, preventing MoD from transforming into MoD with poor wear resistance. At the same time, the average particle size or size of the two is synergistically controlled within a certain range. Therefore, the surface friction coefficient of the high glass fiber content reinforced PBT composite material can be significantly reduced, so that the friction coefficient of the final high glass fiber content reinforced PBT composite material is less than 0.157.

[0015] In a specific embodiment, the peroxide initiator is selected from one or more of dicumyl peroxide (DCP), di-tert-butyl peroxide (DTBP), and bis(2,5-dimethyl)sulfide (DBPH).

[0016] Optionally, the peroxide initiator is dicumyl peroxide (DCP) and / or bis(2,5-diphenyl) sulfide (DBPH).

[0017] By using the above technical solution, dicumyl peroxide and / or bis(2,5-dimethyl)sulfide as peroxide initiators, a large number of free radicals can be generated in the PBT segments of the high glass fiber content reinforced PBT composite material. The large number of free radicals react with the promoter containing carbon-carbon double bonds to form a certain amount of C-C bonds, thereby forming a structurally stable micro-crosslinked structure inside the high glass fiber content reinforced PBT composite material. Under the combined effect of this stable micro-crosslinked structure and the low surface energy film formed on the material surface by the low wear agent, the wear resistance of the material matrix can be significantly improved.

[0018] Specifically, the peroxide initiator can be a combination of dicumyl peroxide and bis(2,5-diphenyl)sulfide, wherein the mass ratio of dicumyl peroxide to bis(2,5-diphenyl)sulfide is 1:1, or it can be either dicumyl peroxide or bis(2,5-diphenyl)sulfide; in a preferred embodiment, the peroxide initiator is either dicumyl peroxide or bis(2,5-diphenyl)sulfide.

[0019] Optionally, the silane coupling agent containing carbon-carbon double bonds is γ-methacryloxypropyltrimethoxysilane (KH570).

[0020] Through the above technical solution, the siloxy groups and alkenyl and acyl groups at specific positions in KH570 react with the free radicals generated by the PBT segments in the high glass fiber content reinforced PBT composite material, effectively improving the bonding force between the materials. This allows the high glass fiber content reinforced PBT composite material to maintain good mechanical properties. In addition, the bonding between KH570 and the siloxy groups in the glass fiber significantly reduces the free glass fiber content in the high glass fiber content reinforced PBT composite material. As a result, during the injection molding process, the burrs at the injection gate of the prepared high glass fiber content reinforced PBT composite material are greatly reduced, with very few or no burrs. The prepared high glass fiber content reinforced PBT composite material is very suitable for subsequent spraying, electroplating and other treatments, and is especially suitable for the production of low-voltage electrical products with contacts.

[0021] Optionally, at least one of the following (a)-(b): (a) The intrinsic viscosity of the PBT resin is 0.9~1.0 dL / g. In this document, the intrinsic viscosity of the PBT resin is determined with reference to GB / T14190-2017, and the test temperature is 25℃. (b) The glass fiber is alkali-free chopped glass fiber with a length of 2-5 mm and a diameter of 9-15 μm.

[0022] By using the above technical solution, PBT resin with a specific viscosity and alkali-free short-cut glass fibers of a specific length and diameter are selected, so that the high glass fiber content reinforced PBT composite material prepared in this application can maintain good mechanical properties (tensile strength and impact strength) while exhibiting excellent wear resistance. The material has a low coefficient of friction, corresponding to extremely low wear. Furthermore, when the PBT composite material is observed at the gate after injection molding, its surface has no or very few glass fiber burrs.

[0023] Optionally, the raw materials of the PBT composite material include the following components in parts by weight: 60-70 parts of PBT resin, 30 parts of glass fiber, 0.2 parts of peroxide initiator, 0.6 parts of accelerator containing carbon-carbon double bonds, 3.6 parts of low-wear agent, and 0.5-0.7 parts of silane coupling agent containing carbon-carbon double bonds.

[0024] Through the above technical solution, the components in the raw materials of the PBT composite material are controlled at a certain content, and the synergistic effect between the components reaches the optimal level. This allows the high glass fiber content reinforced PBT composite material to maintain good mechanical properties while significantly reducing the coefficient of friction and wear. The coefficient of friction can reach below 0.157, and the wear can reach below 7.6 mg. At the same time, after injection molding, the PBT composite material shows no or very few glass fiber burrs on the surface of the gate.

[0025] Optionally, the raw materials of the PBT composite material further include: 0.1-2 parts of lubricant and 0.1-1 parts of antioxidant; wherein the lubricant is pentaerythritol stearate and the antioxidant is 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanuric acid. In a preferred embodiment, the lubricant comprises 0.1-0.3 parts and the antioxidant 0.1-0.2 parts.

[0026] Secondly, this application provides a method for preparing the aforementioned low-wear, low-free-glass-fiber PBT composite material, the method comprising the following steps: S1. The PBT resin, peroxide initiator, low abrasion agent and silane coupling agent containing carbon-carbon double bonds, which are mixed evenly, are added to the main feed port of the twin-screw extruder. The accelerator containing carbon-carbon double bonds is added to the first side feed port of the twin-screw extruder. The glass fiber is added to the second side feed port of the twin-screw extruder. S2. The material added to the twin-screw extruder in step S1 is melted and extruded to obtain a PBT composite material with low abrasion and low free glass fiber.

[0027] The above technical solution involves adding the accelerator separately to prevent it from reacting with the initiator and thus affecting the performance of the high glass fiber content reinforced PBT composite material.

[0028] In a specific embodiment of the preparation method described in this application, the melt extrusion conditions are: temperature of 220~250 ℃ and screw speed of 350~450 rpm.

[0029] In summary, this application includes at least one of the following beneficial technical effects: 1. This application combines polytetrafluoroethylene with a specific particle size and molybdenum disulfide with a specific particle size in a certain proportion. Through the synergistic effect of the two, a low surface energy double lubricating film layer is spread on the material surface, which can significantly reduce the surface friction coefficient of the high glass fiber content reinforced PBT composite material. At the same time, the peroxide initiator induces the PBT chain segments to generate free radicals. The free radicals react with the promoter containing carbon-carbon double bonds to form CC bonds. The CC bonds form a micro-crosslinked structure inside the PBT composite material. This micro-crosslinked structure can improve the wear resistance of the material matrix and inhibit surface melting and film peeling. Under the combined action of the micro-crosslinked structure and the low surface energy film, the prepared high glass fiber content reinforced PBT composite material has outstanding low wear characteristics. 2. The free radicals generated by PBT segments also react with silane coupling agents containing carbon-carbon double bonds, improving the bonding force between materials. This allows PBT composites to maintain good mechanical properties. In addition, the bonding between silane coupling agents containing carbon-carbon double bonds and glass fibers further improves the dispersion and interfacial bonding of glass fibers in the resin matrix. Ultimately, this significantly improves the bonding between the PBT matrix and glass fibers, reducing the content of unbonded free glass fibers in high-glass-fiber reinforced PBT composites. As a result, the burrs at the injection gate of the prepared high-glass-fiber reinforced PBT composites are greatly reduced during the injection molding process. 3. In a preferred embodiment, triallyl isocyanurate and / or triallyl cyanurate with a specific structure containing carbon-carbon double bonds and triazine rings are selected as accelerators. These accelerators can form a structurally stable micro-crosslinked structure inside the high glass fiber content reinforced PBT composite material. This structure can improve the wear resistance of the material matrix. Furthermore, the synergistic use of polytetrafluoroethylene and molybdenum disulfide with specific particle sizes and proportions as low-wear agents results in a wear amount of less than 7.6 mg and a friction coefficient of less than 0.157 for the prepared high glass fiber content reinforced PBT composite material. 4. In a preferred embodiment, KH570 with alkenyl and acyloxy groups at specific positions is selected as an interface modifier, which can significantly reduce the free glass fiber content in the high glass fiber content reinforced PBT composite material. As a result, the burrs at the injection gate of the prepared high glass fiber content reinforced PBT composite material are greatly reduced during the injection molding process, with very few or no burrs. 5. The high glass fiber content reinforced PBT composite material prepared using the present invention has a smooth surface, no exposed glass fiber, and less chipping when injection molded, making it suitable for subsequent spraying, electroplating and other treatments, and is especially suitable for the production of low-voltage electrical products with contacts. Detailed Implementation

[0030] The present application will be further described in detail below with reference to specific embodiments.

[0031] The following examples further illustrate the low-wear, low-free-glass-fiber PBT composite material and its preparation method described in this application. The examples are implemented based on the technical solution of this application, providing detailed implementation methods and specific operating procedures; however, the scope of protection of this application is not limited to the following examples.

[0032] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following embodiments are commercially available.

[0033] Polytetrafluoroethylene-1: Purchased from Fuzhou Taipuda New Material Co., Ltd., product number TPD-503SA, average particle size 1.0~2.9 μm; Polytetrafluoroethylene-2: Purchased from Fuzhou Taipuda New Material Co., Ltd., product number TPD-505SA, average particle size 3.0~5.0 μm; Polytetrafluoroethylene-3: Purchased from Fuzhou Taipuda New Material Co., Ltd., product number TPD-508SA, average particle size 5.1~8.0 μm; Polytetrafluoroethylene-4: Purchased from Fuzhou Taipuda New Material Co., Ltd., product number TPD-512SA, average particle size 8.0~12.0 μm; Molybdenum disulfide-1: Purchased from Shanghai Angwei Technology Co., Ltd., molybdenum disulfide powder, size 0.2~5 μm; Molybdenum disulfide-2: Purchased from Shanghai Angwei Technology Co., Ltd., molybdenum disulfide powder, size 15 μm; Molybdenum disulfide-3: Purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd., molybdenum disulfide powder, size less than 10 nm; PBT: Purchased from Sinopec Yizheng Branch, product number PBT GX121, intrinsic viscosity is 1.0 dL / g; Glass fiber: Purchased from China Jushi Co., Ltd., product number ECS10-03-534A, alkali-free chopped glass fiber, length 3 mm, diameter 10 μm; γ-Methacryloxypropyltrimethoxysilane: KH570, purchased from Jiangsu Langsheng New Material Technology Co., Ltd.

[0034] Examples 1-10 and Comparative Examples 1-17 Examples 1-6 and Comparative Examples 1-10 of this application provide a PBT composite material with low abrasion and low free glass fiber. The raw materials (parts by mass) of the PBT composite material are shown in Table 1. The low abrasion agent is composed of polytetrafluoroethylene-1 and molybdenum disulfide-1 in a mass ratio of 2:1. The preparation process of PBT composite materials in Examples 1-6 and Comparative Examples 1-10 is as follows: PBT resin, peroxide initiator, low abrasion agent, silane coupling agent, lubricant and antioxidant are added to a high-speed mixer according to the formula and mixed. The mixed material is added to the main feed port of a twin-screw extruder. The accelerator containing carbon-carbon double bonds is added to the fifth side feed port (first side feed port) of the extruder. Glass fiber is added to the eighth side feed port (second side feed port) of the extruder. The temperature of each zone of the extruder is set to 230 ℃ and the screw speed is 400 rpm. After melt extrusion, cooling, drying and pelletizing, a PBT composite material with low abrasion and low free glass fiber is obtained. Table 1 Example 7

[0035] The method described in Example 6 is adopted, except that all polytetrafluoroethylene-1 is replaced with polytetrafluoroethylene-2. Example 8

[0036] The procedure was carried out as described in Example 6, except that all triallyl isocyanurate (accelerator) was replaced with isopropyl acrylate. Example 9

[0037] The method described in Example 6 is adopted, except that the low-wearing agent is composed of polytetrafluoroethylene-1 and molybdenum disulfide-1 in a mass ratio of 1:1. Example 10

[0038] The method described in Example 6 is adopted, except that the low-wearing agent is composed of polytetrafluoroethylene-1 and molybdenum disulfide-1 in a mass ratio of 3:1.

[0039] Comparative Example 11 The method described in Example 6 is adopted, except that all polytetrafluoroethylene-1 is replaced with polytetrafluoroethylene-3.

[0040] Comparative Example 12 The method described in Example 6 is adopted, except that all polytetrafluoroethylene-1 is replaced with polytetrafluoroethylene-4.

[0041] Comparative Example 13 The method described in Example 6 is adopted, except that all of the molybdenum disulfide-1 is replaced with molybdenum disulfide-2.

[0042] Comparative Example 14 The method described in Example 6 is adopted, except that all of the molybdenum disulfide-1 is replaced with molybdenum disulfide-3.

[0043] Comparative Example 15 The method described in Example 6 is adopted, except that the low-wearing agent is composed of polytetrafluoroethylene-1 and molybdenum disulfide-1 in a mass ratio of 0.5:1.

[0044] Comparative Example 16 The method described in Example 6 is adopted, except that the low-wearing agent is composed of polytetrafluoroethylene-1 and molybdenum disulfide-1 in a mass ratio of 5:1.

[0045] Comparative Example 17 The process was carried out in accordance with Example 6, except that in the preparation of the PBT composite material, PBT resin, peroxide initiator, accelerator containing carbon-carbon double bonds, low abrasion agent, silane coupling agent, lubricant and antioxidant were added to a high-speed mixer according to the formula and mixed. The mixed material was added to the main feed port of a twin-screw extruder, and glass fiber was added to the side feed port of the extruder. The temperature of each zone of the extruder was set to 230 ℃ and the screw speed was set to 400 rpm. After melt extrusion, cooling, drying and pelletizing, a PBT composite material with low abrasion and low free glass fiber was obtained.

[0046] Test case Tensile strength was tested according to GB / T 1040.2 standard at a speed of 10 mm / min; The impact strength was tested according to GB / T 1843 standard, and the pendulum energy was 2.75 J; The coefficient of friction was tested according to the GB / T10006 standard for the dynamic coefficient of friction of the material surface at a speed of 100 mm / min. The wear amount was tested according to GB / T 30314 standard, after 1000 rotations at a speed of 72 rpm. The free glass fiber content can be indirectly characterized by observing the burr state of the gate after injection molding of PBT composite materials.

[0047] The PBT composite materials prepared in Examples 1-10 and Comparative Examples 1-17 were subjected to tensile strength, impact strength, coefficient of friction, and wear loss tests, respectively. The burr state of the PBT composite materials at the gate after injection molding was also observed. The test results are shown in Table 2. Table 2

[0048] As can be seen from the test results of Examples 1-6 in Table 2, the low-wear, low-free-glass-fiber PBT composite material prepared by this invention exhibits excellent wear resistance while maintaining good mechanical properties (tensile strength and impact strength). The material has a low coefficient of friction, corresponding to extremely low wear. After injection molding, the gate surface was observed to have little or no glass fiber burrs, indicating good interfacial bonding between the glass fiber and resin, and a low content of free glass fiber.

[0049] Compared with Example 6, in Example 7, polytetrafluoroethylene-1 with an average particle size of 1.0~2.9 μm was replaced with polytetrafluoroethylene-2 ​​with an average particle size of 3.0~5.0 μm, resulting in a slight enhancement of mechanical properties and a slight decrease in wear resistance. Compared with Example 6, Example 8 replaced triallyl isocyanurate (accelerator) containing carbon-carbon double bonds and triazine rings with isopropyl acrylate (accelerator) containing carbon-carbon double bonds, resulting in a decrease in both mechanical properties and wear resistance. Compared with Example 6, in Example 9, the mass ratio of polytetrafluoroethylene-1 and molybdenum disulfide-1 was adjusted to 1:1, the mechanical properties remained basically unchanged, but the wear resistance was reduced; Compared with Example 6, in Example 10, the mass ratio of polytetrafluoroethylene-1 and molybdenum disulfide-1 was adjusted to 3:1, resulting in decreased mechanical properties but enhanced wear resistance. In Comparative Example 1, no initiator, accelerator, or low-wear agent was added to the formulation. It was also processed at a high speed of 800 rpm. Compared with Example 6, the coefficient of friction and wear amount were significantly increased, and there were obvious glass fiber burrs at the gate after injection molding. In Comparative Example 2, no initiator or accelerator was added to the formulation. Under the action of low abrasion agent, the coefficient of friction of the material was significantly reduced, and the amount of abrasion was also reduced to a certain extent, but it was still significantly higher than that of Example 6. The glass fiber burrs at the gate after injection molding were more obvious. The formulation of Comparative Example 3 did not contain a low-abrasion agent, resulting in a significant reduction in wear resistance. The formulation of Comparative Example 4 did not contain any accelerators, resulting in a significant decrease in wear resistance. The formulation of Comparative Example 5 did not contain an initiator, and its wear resistance was significantly reduced. In Comparative Example 6, no silane coupling agent was added to the formulation, resulting in reduced mechanical properties and significantly reduced wear resistance. Comparative Example 7 contained an accelerator exceeding the limits specified in this application. The PBT crosslinking degree after melt extrusion was too high, which affected the subsequent injection molding of the PBT composition and made it impossible to process. Therefore, no corresponding tests were conducted. Comparative Example 8, which contained an initiator exceeding the scope specified in this application, showed a significant decrease in both mechanical properties and wear resistance. In Comparative Example 9, the addition of a small amount of low-wearing agent showed a slight tendency to enhance mechanical properties, but a significant decrease in wear resistance. In Comparative Example 10, the addition of excessive low-abrasion agent resulted in a slight decrease in mechanical properties and a significant reduction in wear resistance. Compared with Example 6, in Comparative Example 11, polytetrafluoroethylene-1 with an average particle size of 1.0~2.9 μm was replaced with polytetrafluoroethylene-3 with an average particle size of 5.1~8.0 μm. The mechanical properties remained basically unchanged, but the wear resistance was significantly reduced. Compared with Example 6, in Comparative Example 12, polytetrafluoroethylene-1 with an average particle size of 1.0~2.9 μm was replaced with polytetrafluoroethylene-4 with an average particle size of 8.0~12.0 μm. The mechanical properties remained basically unchanged, but the wear resistance was significantly reduced. Compared with Example 6, in Comparative Example 13, molybdenum disulfide-1 with a size of 0.2~5 μm was replaced with molybdenum disulfide-2 with a size of 15 μm. The mechanical properties remained basically unchanged, but the wear resistance was significantly reduced. Compared with Example 6, in Comparative Example 14, molybdenum disulfide-1 with a size of 0.2~5 μm was replaced with molybdenum disulfide-3 with a size of less than 10 nm. The mechanical properties remained basically unchanged, but the wear resistance was significantly reduced. Compared with Example 6, the mass ratio of polytetrafluoroethylene-1 and molybdenum disulfide-1 in Comparative Example 15 was adjusted to 0.5:1. The mechanical properties remained basically unchanged, but the wear resistance was significantly reduced. Compared with Example 6, the mass ratio of polytetrafluoroethylene-1 and molybdenum disulfide-1 in Comparative Example 16 was adjusted to 5:1. The mechanical properties remained basically unchanged, but the wear resistance was significantly reduced. Compared with Example 6, Comparative Example 17 added the accelerator and initiator to the main feed port of the extruder at the same time during preparation. Because the initiator can react quickly with the accelerator, the probability of the accelerator reacting with PBT resin is reduced, resulting in a significantly higher wear rate than in Example 6. Glass fiber burrs were also observed at the gate.

[0050] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made to the structure, shape, and principle of this application should be covered within the scope of protection of this application.

Claims

1. A PBT composite material with low wear and low free glass fiber, characterized in that, The raw materials of the PBT composite material include the following components in parts by weight: 50-80 parts of PBT resin, 10-40 parts of glass fiber, 0.1-0.5 parts of peroxide initiator, 0.1-0.8 parts of accelerator containing carbon-carbon double bonds, 1-5 parts of low-wear agent, and 0.2-2 parts of silane coupling agent containing carbon-carbon double bonds; the low-wear agent contains polytetrafluoroethylene and molybdenum disulfide in a mass ratio of 1-3:1, wherein the average particle size of the polytetrafluoroethylene is 0.1-5 μm, and the size of the molybdenum disulfide is 0.1-5 μm.

2. The low-wear, low-free-glass-fiber PBT composite material according to claim 1, characterized in that, The accelerator also contains a triazine ring.

3. The low-wear, low-free-glass-fiber PBT composite material according to claim 2, characterized in that, The accelerator is triallyl isocyanurate and / or triallyl cyanurate.

4. The low-wear, low-free-glass-fiber PBT composite material according to claim 1, characterized in that, The low-wear agent contains polytetrafluoroethylene and molybdenum disulfide in a mass ratio of 2:1, wherein the average particle size of the polytetrafluoroethylene is 1~2.9 μm and the size of the molybdenum disulfide is 0.2~5 μm.

5. The low-wear, low-free-glass-fiber PBT composite material according to claim 1, characterized in that, The peroxide initiator is dicumyl peroxide and / or bis(2,5-dimethyl)sulfide.

6. The low-wear, low-free-glass-fiber PBT composite material according to claim 1, characterized in that, The silane coupling agent containing carbon-carbon double bonds is γ-methacryloxypropyltrimethoxysilane.

7. The low-wear, low-free-glass-fiber PBT composite material according to claim 1, characterized in that, At least one of the following (a)-(b): (a) The intrinsic viscosity of the PBT resin is 0.9~1.0 dL / g; (b) The glass fiber is alkali-free chopped glass fiber with a length of 2-5 mm and a diameter of 9-13 μm.

8. The low-wear, low-free-glass-fiber PBT composite material according to claim 1, characterized in that, The raw materials of the PBT composite material include the following components in parts by weight: 60-70 parts of PBT resin, 30 parts of glass fiber, 0.2 parts of peroxide initiator, 0.6 parts of accelerator containing carbon-carbon double bonds, 3.6 parts of low-wear agent, and 0.5-0.7 parts of silane coupling agent containing carbon-carbon double bonds.

9. The low-wear, low-free-glass-fiber PBT composite material according to claim 1, characterized in that, The raw materials of the PBT composite material also include: 0.1 to 2 parts of lubricant and 0.1 to 1 part of antioxidant; wherein the lubricant is pentaerythritol stearate and the antioxidant is 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanuric acid.

10. A method for preparing a low-wear, low-free-glass-fiber PBT composite material according to any one of claims 1 to 9, characterized in that, The preparation method includes the following steps: S1. The PBT resin, peroxide initiator, low abrasion agent and silane coupling agent containing carbon-carbon double bonds, which are mixed evenly, are added to the main feed port of the twin-screw extruder. The accelerator containing carbon-carbon double bonds is added to the first side feed port of the twin-screw extruder. The glass fiber is added to the second side feed port of the twin-screw extruder. S2. The material added to the twin-screw extruder in step S1 is melted and extruded to obtain a PBT composite material with low abrasion and low free glass fiber.

Images