High-light-transmittance hydrolysis-resistant glass fiber and PBT composite material and preparation method and application thereof

Abstract

The invention provides a high-light-transmittance hydrolysis-resistant glass fiber and PBT composite material as well as a preparation method and application thereof. The high-light-transmittance hydrolysis-resistant glass fiber and PBT composite material sequentially comprises a fluoride-free boron-free ECT glass core layer, a silane coupling agent middle layer and a copolymerization outer coating from inside to outside, the fluorine-free boron-free ECT glass core layer is prepared from the following raw materials in percentage by mass: 58 to 62 percent of silicon dioxide, 12 to 15 percent of aluminum oxide and 18 to 22 percent of calcium oxide; the raw materials of the silane coupling agent middle layer comprise at least one or more of gamma-methacryloxy propyl trimethoxy silane, gamma-aminopropyl triethoxy silane and gamma-glycidyl ether oxypropyl trimethoxy silane, and the silane coupling agent middle layer comprises at least one or more of gamma-methacryloxy propyl trimethoxy silane, gamma-aminopropyl triethoxy silane, gamma-aminopropyl triethoxy silane and gamma-glycidyl ether oxypropyl trimethoxy silane; the raw material of the copolymerization outer coating is a copolymer formed by polyurethane, acrylic acid and polyurethane-acrylic acid; compared with the prior art, the ECT core layer, the interface enhancement layer and the light regulation and control coating synergistically improve the light transmittance and interface combination, the welding efficiency and quality are improved, and the problems of scattering and hydrolysis of traditional glass fibers are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, and in particular to a high-transmittance, hydrolysis-resistant glass fiber, PBT composite material, and a preparation method and application thereof. Background Art

[0002] Polybutylene terephthalate (PBT) has excellent heat resistance, electrical insulation, weather resistance and chemical stability, and is widely used in electronic components, lighting industry and household appliances. Among them, some plastic parts with complex structures and shapes cannot be processed and formed in one go, and adhesives, screw fixation, snap fit, hot plate welding, ultrasonic welding and other methods are needed to connect multiple formed parts.

[0003] Compared with the traditional plastic connection method, laser welding technology is a technology that uses laser (light source with a wavelength of 800-1200nm) to locally heat the plastic in a small welding area, and the plastic melts quickly for welding. It has the characteristics of being able to achieve precise welding of tiny parts, low thermal damage to surrounding materials, beautiful and high-strength welds, easy automation, improved efficiency, and reduced costs. The principle of laser transmission welding technology is that the light-transmitting layer and the light-absorbing layer are arranged in an overlapping manner. Most of the laser penetrates the light-transmitting layer and is absorbed by the light-absorbing layer and converted into heat. The interface area between the light-absorbing layer and the light-transmitting layer is melted and combined together through heat transfer. Therefore, the optical properties of the material are crucial. The light-transmitting layer needs to have a high transmittance in a specific laser band range, and the light-absorbing layer needs to be able to absorb enough laser energy to convert it into heat for interface fusion.

[0004] PBT is a semi-crystalline material that can crystallize quickly at a relatively low temperature. The crystallization property of PBT forms a tiny crystal structure inside it, which makes PBT material have relatively low laser transmittance, especially in glass fiber reinforced PBT composite materials. Due to the addition of glass fiber, its tensile strength, bending strength and thermal deformation temperature are greatly improved. Although it greatly expands the scope of use of PBT materials, it also significantly reduces the transparency of the material, making the processing condition window narrower. When welding, it is necessary to increase the laser power or irradiation speed, or reduce the thickness of the molded part in the irradiation area to achieve a good bonding effect. Increasing the laser power or irradiation rate may cause the surface of the material to burn and whiten, and the welding strength will decrease.

[0005] A PBT composite material and its preparation method disclosed in CN109306157A use flat glass fibers to improve the light transmittance of the glass fiber reinforced PBT composite material to a certain extent, but it does not solve the problems of hydrolysis and interface bonding, and the preparation process of flat glass fibers is complicated, resulting in its high price. Summary of the invention

[0006] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a high-transmittance hydrolysis-resistant glass fiber, a PBT composite material and a preparation method and application thereof, so as to solve the problem in the prior art that, although the existing glass fiber is added to the PBT composite material, the transmittance can be improved, but the hydrolysis and interface bonding problems are not solved, and the price is still relatively expensive.

[0007] To achieve the above-mentioned object, the first aspect of the present invention adopts the following technical scheme: a highly transparent hydrolysis-resistant glass fiber, which comprises, from the inside to the outside, a fluorine-free and boron-free ECT glass core layer, a silane coupling agent intermediate layer, and a copolymer outer coating layer;

[0008] Calculated by mass percentage, the raw materials of the fluorine-free and boron-free ECT glass core layer include silicon dioxide, aluminum oxide and calcium oxide, and the mass ratio thereof is 58-62:12-15:18-22;

[0009] The raw materials of the silane coupling agent intermediate layer include at least one or more of γ-methacryloxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane and γ-glycidyloxypropyltrimethoxysilane;

[0010] The raw materials of the copolymer outer coating are polyurethane, acrylic acid and a copolymer formed by polyurethane-acrylic acid.

[0011] Technical principle:

[0012] The fluorine-free and boron-free ECT glass core layer provides strength, and the silane coupling agent intermediate layer acts as a bridge between the fluorine-free and boron-free ECT glass core layer and the copolymer outer coating layer, connecting with the glass fiber surface through chemical bonds, and forming physical or chemical interactions with the copolymer coating layer; at the same time, the copolymer outer coating layer also provides mechanical protection, and after being applied to the PBT composite material, it gives the PBT composite material specific properties, such as high transparency and hydrolysis resistance. The three work together to improve the interface compatibility and stress transfer efficiency between the high-transmittance and hydrolysis-resistant glass fiber and the polybutylene terephthalate resin in the PBT composite material.

[0013] The second aspect of the present invention adopts the following technical scheme: a PBT composite material, calculated by weight, includes 30-70 parts of polybutylene terephthalate resin, 0.1-0.5 parts of composite black masterbatch, 1-3 parts of core-shell toughening agent, 0.2-0.6 parts of antioxidant, 0.2-0.6 parts of lubricant, 0.05-0.2 parts of ester exchange inhibitor and 30-55 parts of high-transmittance hydrolysis-resistant glass fiber as described in the first aspect of the present invention.

[0014] Optimized, the raw materials of the composite black masterbatch include:

[0015] PBT carrier matrix;

[0016] Nano carbon black, wherein the nano carbon black accounts for 0.1%-0.3% of the PBT carrier matrix according to mass percentage;

[0017] Titanium dioxide, which accounts for 0.05% to 0.1% of the PBT carrier matrix by mass percentage;

[0018] The hyperbranched polyester dispersant accounts for 0.5%-1% of the PBT carrier matrix according to mass percentage.

[0019] The composite black masterbatch is prepared by chemically modifying the traditional black masterbatch by adding titanium dioxide and a hyperbranched polyester dispersant. The titanium dioxide can maintain good chemical stability in a hot and humid environment, and the hyperbranched polyester dispersant makes the glass fiber more evenly dispersed in the PBT composite material.

[0020] Optimally, the core-shell toughening agent is a core-shell structure particle, the core layer is ethylene-octene copolymer, the shell layer is polymethyl methacrylate, and the mass ratio of the core layer to the shell layer is 7:3.

[0021] The core-shell toughening agent has higher strength and better processing performance. The core layer of the core-shell toughening agent of the present invention is a soft elastomer, which can form a good interface with the high-transmittance hydrolysis-resistant glass fiber, absorb energy when the material is impacted, and play a buffering role; the shell layer is a hard polymer that can form a good compatibility with the polybutylene terephthalate resin, improve the mechanical properties of the material, and the material has good melt fluidity and a stable processing process.

[0022] Optimally, the lubricant is pentaerythritol stearate or polyethylene wax;

[0023] And / or the antioxidant is a mixture of phosphite and n-octadecylβ-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate in a mass ratio of 1:1.

[0024] Optimally, the transesterification inhibitor is at least one of sodium dihydrogen phosphate, sodium pyrophosphate, and phosphorous acid.

[0025] The third aspect of the present invention adopts the following technical solution: a method for preparing the PBT composite material as described in the second aspect of the present invention, comprising the following steps:

[0026] Adding polybutylene terephthalate resin, composite black masterbatch, core-shell toughening agent, antioxidant, lubricant and transesterification inhibitor into a high-speed mixer and mixing them evenly to obtain a premix;

[0027] The premix is ​​added to the main feed port of the twin-screw extruder, and the high-transmittance hydrolysis-resistant glass fiber is added to the side feed port. After shearing in the twin-screw extruder, it is fully mixed, and then extruded, cooled and pelletized in sequence to obtain the product; wherein the temperature of each section in the extrusion process adopts a dynamic gradient temperature.

[0028] Optimally, the dynamic gradient temperature is: the first stage temperature is 240°C ± 2°C, the second stage temperature is 250°C ± 2°C, and the third stage temperature is 245°C ± 2°C.

[0029] Optimally, the aspect ratio of the twin-screw extruder is 40-60:1, the screw speed of the twin-screw extruder is 300-400r / min, and the vacuum degree in the twin-screw extruder is -0.05MPa to -0.1MPa.

[0030] The fourth aspect of the present invention adopts the following technical solution: an application of the PBT composite material as described in the second aspect of the present invention, wherein the PBT composite material is applied to automotive electronic laser welding components.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The refractive index of the high-transmittance hydrolysis-resistant glass fiber used in the present invention is highly matched with the refractive index of the polybutylene terephthalate resin, which reduces the scattering at the interface, thereby improving the transmittance; at the same time, the high-transmittance hydrolysis-resistant glass fiber has hydrolysis resistance, which can increase the service life of the material; the nano-scale silane coupling agent intermediate layer improves the interface bonding force with the polybutylene terephthalate resin, and the copolymer outer coating inhibits light scattering, and the transmittance is increased by more than 20%;

[0033] 2. Through the "ECT core layer + interface enhancement layer + light regulation coating", the transmittance and interface bonding are synergistically improved, the welding efficiency and quality are improved, and the scattering and hydrolysis problems of traditional glass fibers are solved;

[0034] 3. Excellent mechanical properties: PBT composite materials have high tensile strength and flexural modulus, can still maintain high strength after wet heat aging, and show good durability, which is significantly better than ordinary materials;

[0035] 4. High laser transmittance: The laser transmittance of PBT composite materials (1.5mm, 980nm laser) is ≥55%, ensuring the efficiency and quality of laser welding; by optimizing the optical properties of the material, reducing the laser power and time required for welding, reducing welding costs, and improving the strength and aesthetics of the welded parts;

[0036] 5. Environmental protection and economy: The use of high-transmittance and hydrolysis-resistant glass fiber meets environmental protection requirements and reduces the impact on the environment. Compared with flat glass fibers, the high-transmittance and hydrolysis-resistant glass fiber used in the present invention is in a common cylindrical shape, which has lower cost, simple process, and is easy for large-scale production. DETAILED DESCRIPTION

[0037] The present invention is further described in detail below through specific embodiments:

[0038] Example 1

[0039] 1. Preparation of high light transmittance and hydrolysis resistant glass fiber

[0040] 58 parts of silicon dioxide, 12 parts of aluminum oxide and 18 parts of calcium oxide are mixed and sent into a melting furnace, and then the temperature in the melting furnace is adjusted to 1400°C-1720°C to melt the components to form molten glass liquid;

[0041] The glass liquid flows out through a platinum-rhodium alloy leak plate and is stretched at high speed to form thin and long glass filaments;

[0042] A nano-scale silane coupling agent composed of γ-methacryloxypropyltrimethoxysilane is coated on the surface of the glass filament to form a silane coupling agent intermediate layer;

[0043] Then, a copolymer formed by polyurethane, acrylic acid and polyurethane-acrylic acid is coated on the surface of the silane coupling agent intermediate layer to form a copolymer outer coating;

[0044] After drying and winding, it forms high light transmittance and hydrolysis resistant glass fiber.

[0045] 2. Preparation of composite black masterbatch

[0046] 100 parts of PBT carrier matrix, 0.1 parts of nano carbon black with a particle size of 20-30 nm, 0.05 parts of titanium dioxide and 0.5 parts of Hybrane PS2550, a hyperbranched polyester dispersant, are processed and formed through existing processes, such as pre-mixing, melt extrusion, granulation, drying, screening and packaging steps.

[0047] 3. Preparation of PBT composite materials

[0048] Weigh 67 parts of polybutylene terephthalate resin, 30 parts of prepared high-transmittance hydrolysis-resistant glass fiber, 0.3 parts of prepared composite black masterbatch, 2 parts of core-shell toughening agent, 0.3 parts of antioxidant, 0.2 parts of lubricant and 0.2 parts of ester exchange inhibitor; wherein the core-shell toughening agent is a core-shell structure particle formed by emulsion polymerization, the core layer is ethylene-octene copolymer, the shell layer is polymethyl methacrylate, and the mass ratio of the core layer to the shell layer is 7:3; the antioxidant is a mixture of phosphite and β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, and the mass ratio is 1:1; the lubricant is pentaerythritol stearate; the ester exchange inhibitor is sodium dihydrogen phosphate; the single filament diameter of the high-transmittance hydrolysis-resistant glass fiber is 10um, and the short cut length is 3mm.

[0049] Add polybutylene terephthalate resin, composite black masterbatch, core-shell toughening agent, antioxidant, lubricant and transesterification inhibitor into a high-speed mixer and mix at 800-1200 r / min for 2-4 minutes to obtain a premix;

[0050] The premix is ​​added to the main feed port of a twin-screw extruder with a length-to-diameter ratio of 48:1 for melt dispersion, and the high-transmittance and hydrolysis-resistant glass fiber is added to the side feed port at a rate of 60 kg / hour. After screw shearing, the premix is ​​fully mixed with the sheared high-transmittance and hydrolysis-resistant glass fiber, extruded through a twin-screw, and then cooled and formed in a cooling water tank, and pelletized to obtain a PBT composite material.

[0051] During the extrusion process of the twin-screw extruder, dynamic gradient temperature control is adopted, specifically, the temperature of the first stage is 240℃±2℃, the temperature of the second stage is 250℃±2℃, and the temperature of the third stage is 245℃±2℃; and the screw speed of the twin-screw extruder is 300-400r / min, and the vacuum degree is -0.05MPa to -0.1MPa.

[0052] Example 2

[0053] 1. Preparation of high light transmittance and hydrolysis resistant glass fiber

[0054] 60 parts of silicon dioxide, 13 parts of aluminum oxide and 20 parts of calcium oxide are mixed and sent into a melting furnace, and then the temperature in the melting furnace is adjusted to 1400°C-1720°C to melt the components to form molten glass liquid;

[0055] The glass liquid flows out through a platinum-rhodium alloy plate and is stretched at high speed to form long and thin glass filaments;

[0056] A nano-scale silane coupling agent composed of γ-methacryloxypropyltrimethoxysilane and γ-aminopropyltriethoxysilane in a mass ratio of 1:1 is coated on the surface of the glass filament to form a silane coupling agent intermediate layer;

[0057] Then, a copolymer formed by polyurethane, acrylic acid and polyurethane-acrylic acid is coated on the surface of the silane coupling agent intermediate layer to form a copolymer outer coating;

[0058] After drying and winding, it forms high light transmittance and hydrolysis resistant glass fiber.

[0059] 4. Preparation of composite black masterbatch

[0060] 100 parts of PBT carrier matrix, 0.2 parts of nano carbon black with a particle size of 20-30 nm, 0.08 parts of titanium dioxide and 0.7 parts of Hybrane PS2550, a hyperbranched polyester dispersant, are processed and formed through existing processes, such as pre-mixing, melt extrusion, granulation, drying, screening and packaging steps.

[0061] 5. Preparation of PBT composite materials

[0062] Weigh 68 parts of polybutylene terephthalate resin, 30 parts of prepared high-transmittance hydrolysis-resistant glass fiber, 0.5 parts of prepared composite black masterbatch, 1 part of core-shell toughening agent, 0.2 parts of antioxidant, 0.2 parts of lubricant and 0.1 parts of ester exchange inhibitor; wherein the core-shell toughening agent is a core-shell structure particle formed by emulsion polymerization, the core layer is ethylene-octene copolymer, the shell layer is polymethyl methacrylate, and the mass ratio of the core layer to the shell layer is 7:3; the antioxidant is a mixture of phosphite and β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, and the mass ratio is 1:1; the lubricant is pentaerythritol stearate; the ester exchange inhibitor is sodium dihydrogen phosphate; the single filament diameter of the high-transmittance hydrolysis-resistant glass fiber is 10um, and the short cut length is 3mm.

[0063] Add polybutylene terephthalate resin, composite black masterbatch, core-shell toughening agent, antioxidant, lubricant and transesterification inhibitor into a high-speed mixer and mix at 800-1200 r / min for 2-4 minutes to obtain a premix;

[0064] The premix is ​​added to the main feed port of a twin-screw extruder with a length-to-diameter ratio of 48:1 for melt dispersion, and the high-transmittance and hydrolysis-resistant glass fiber is added to the side feed port at a rate of 60 kg / hour. After screw shearing, the premix is ​​fully mixed with the sheared high-transmittance and hydrolysis-resistant glass fiber, extruded through a twin-screw, and then cooled and formed in a cooling water tank, and pelletized to obtain a PBT composite material.

[0065] During the extrusion process of the twin-screw extruder, dynamic gradient temperature control is adopted, specifically, the temperature of the first stage is 240℃±2℃, the temperature of the second stage is 250℃±2℃, and the temperature of the third stage is 245℃±2℃; and the screw speed of the twin-screw extruder is 300-400r / min, and the vacuum degree is -0.05MPa to -0.1MPa.

[0066] Example 3

[0067] 1. Preparation of high light transmittance and hydrolysis resistant glass fiber

[0068] 62 parts of silicon dioxide, 15 parts of aluminum oxide and 22 parts of calcium oxide are mixed and sent into a melting furnace, and then the temperature in the melting furnace is adjusted to 1400°C-1720°C to melt the components to form molten glass liquid;

[0069] The glass liquid flows out through a platinum-rhodium alloy leak plate and is stretched at high speed to form thin and long glass filaments;

[0070] A nano-scale silane coupling agent composed of γ-methacryloxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane and γ-glycidyloxypropyltrimethoxysilane in a mass ratio of 1:1:1 is coated on the surface of the glass filament to form a silane coupling agent intermediate layer;

[0071] Then, a copolymer formed by polyurethane, acrylic acid and polyurethane-acrylic acid is coated on the surface of the silane coupling agent intermediate layer to form a copolymer outer coating;

[0072] After drying and winding, it forms high light transmittance and hydrolysis resistant glass fiber.

[0073] 6. Preparation of composite black masterbatch

[0074] 100 parts of PBT carrier matrix, 0.3 parts of nano carbon black with a particle size of 20-30 nm, 0.1 parts of titanium dioxide and 1 part of Hybrane PS2550, a hyperbranched polyester dispersant, are processed and formed through existing processes, such as pre-mixing, melt extrusion, granulation, drying, screening and packaging steps.

[0075] 7. Preparation of PBT composite materials

[0076] Weigh 70 parts of polybutylene terephthalate resin, 55 parts of prepared high-transmittance hydrolysis-resistant glass fiber, 0.4 parts of prepared composite black masterbatch, 3 parts of core-shell toughening agent, 0.6 parts of antioxidant, 0.6 parts of lubricant and 0.2 parts of ester exchange inhibitor; wherein the core-shell toughening agent is a core-shell structure particle formed by emulsion polymerization, the core layer is ethylene-octene copolymer, the shell layer is polymethyl methacrylate, and the mass ratio of the core layer to the shell layer is 7:3; the antioxidant is a mixture of phosphite and β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate octadecyl ester and the mass ratio is 1:1; the lubricant is polyethylene wax; the ester exchange inhibitor is sodium pyrophosphate and phosphorous acid in a mass ratio of 1:1; the single filament diameter of the high-transmittance hydrolysis-resistant glass fiber is 10um, and the short cut length is 3mm.

[0077] Add polybutylene terephthalate resin, composite black masterbatch, core-shell toughening agent, antioxidant, lubricant and transesterification inhibitor into a high-speed mixer and mix at 800-1200 r / min for 2-4 minutes to obtain a premix;

[0078] The premix is ​​added to the main feed port of a twin-screw extruder with a length-to-diameter ratio of 60:1 for melt dispersion, and the high-transmittance and hydrolysis-resistant glass fiber is added to the side feed port at a rate of 60 kg / hour. After screw shearing, the premix is ​​fully mixed with the sheared high-transmittance and hydrolysis-resistant glass fiber, extruded through a twin-screw, and then cooled and formed in a cooling water tank, and pelletized to obtain a PBT composite material.

[0079] During the extrusion process of the twin-screw extruder, dynamic gradient temperature control is adopted, specifically, the temperature of the first stage is 240℃±2℃, the temperature of the second stage is 250℃±2℃, and the temperature of the third stage is 245℃±2℃; and the screw speed of the twin-screw extruder is 300-400r / min, and the vacuum degree is -0.05MPa to -0.1MPa.

[0080] Example 4

[0081] 1. Preparation of high light transmittance and hydrolysis resistant glass fiber

[0082] 62 parts of silicon dioxide, 12 parts of aluminum oxide and 28 parts of calcium oxide are mixed and sent into a melting furnace, and then the temperature in the melting furnace is adjusted to 1400°C-1720°C to melt the components to form molten glass liquid;

[0083] The glass liquid flows out through a platinum-rhodium alloy plate and is stretched at high speed to form long and thin glass filaments;

[0084] A nano-scale silane coupling agent composed of γ-aminopropyltriethoxysilane and γ-glycidyloxypropyltrimethoxysilane in a mass ratio of 1:1 is coated on the surface of the glass filament to form a silane coupling agent intermediate layer;

[0085] Then, a copolymer formed by polyurethane, acrylic acid and polyurethane-acrylic acid is coated on the surface of the silane coupling agent intermediate layer to form a copolymer outer coating;

[0086] After drying and winding, it forms high light transmittance and hydrolysis resistant glass fiber.

[0087] 8. Preparation of composite black masterbatch

[0088] 100 parts of PBT carrier matrix, 0.2 parts of nano carbon black with a particle size of 20-30 nm, 0.08 parts of titanium dioxide and 0.9 parts of Hybrane PS2550, a hyperbranched polyester dispersant, are processed and formed through existing processes, such as pre-mixing, melt extrusion, granulation, drying, screening and packaging steps.

[0089] 9. Preparation of PBT composite materials

[0090] Weigh 30 parts of polybutylene terephthalate resin, 45 parts of prepared high-transmittance hydrolysis-resistant glass fiber, 0.1 parts of prepared composite black masterbatch, 1 part of core-shell toughening agent, 0.4 parts of antioxidant, 0.4 parts of lubricant and 0.05 parts of ester exchange inhibitor; wherein the core-shell toughening agent is a core-shell structure particle formed by emulsion polymerization, the core layer is ethylene-octene copolymer, the shell layer is polymethyl methacrylate, and the mass ratio of the core layer to the shell layer is 7:3; the antioxidant is a mixture of phosphite and β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate and the mass ratio is 1:1; the lubricant is polyethylene wax; the ester exchange inhibitor is sodium pyrophosphate and phosphorous acid in a mass ratio of 1:1; the single filament diameter of the high-transmittance hydrolysis-resistant glass fiber is 10um, and the short cut length is 3mm.

[0091] Add polybutylene terephthalate resin, composite black masterbatch, core-shell toughening agent, antioxidant, lubricant and transesterification inhibitor into a high-speed mixer and mix at 800-1200 r / min for 2-4 minutes to obtain a premix;

[0092] The premix is ​​added to the main feed port of a twin-screw extruder with a length-to-diameter ratio of 40:1 for melt dispersion, and the high-transmittance and hydrolysis-resistant glass fiber is added to the side feed port at a rate of 60 kg / hour. After screw shearing, the premix is ​​fully mixed with the sheared high-transmittance and hydrolysis-resistant glass fiber, extruded through a twin-screw, and then cooled and formed in a cooling water tank, and pelletized to obtain a PBT composite material.

[0093] During the extrusion process of the twin-screw extruder, dynamic gradient temperature control is adopted, specifically, the temperature of the first stage is 240℃±2℃, the temperature of the second stage is 250℃±2℃, and the temperature of the third stage is 245℃±2℃; and the screw speed of the twin-screw extruder is 300-400r / min, and the vacuum degree is -0.05MPa to -0.1MPa.

[0094] Comparative Example 1

[0095] The only difference from Example 1 is that the high-transmittance hydrolysis-resistant glass fiber is replaced by the flat glass fiber in the background art.

[0096] Comparative Example 2

[0097] The only difference from Example 2 is that the high-transmittance and hydrolysis-resistant glass fiber is replaced by the flat glass fiber in the background technology, and during the extrusion process of the twin-screw extruder, constant temperature control is adopted, specifically, the temperature of each section is the same, which can be 230°C, 240°C or 250°C. In this comparative example, the temperature of each section is 240°C.

[0098] The test standards and methods of the present invention are specifically:

[0099] Tensile properties: According to GB / T1040-2006 national standard for the determination of tensile properties of plastics ISO 527-1 / -2, the speed is 20mm / min;

[0100] Bending performance: According to GB / T9341-2008 national standard for the determination of plastic bending performance ISO 178:2010, the speed is 20mm / min;

[0101] Notched impact test: According to GB / T1843-2008 national standard for the determination of plastic cantilever beam impact strength ISO179:2010 / 1Ea, the speed is 3.5m / s;

[0102] Unnotched impact test: According to GB / T1843-2008 national standard for the determination of plastic cantilever beam impact strength ISO179:2010 / 1Eu, the speed is 3.5m / s;

[0103] Transmittance test: Use a transmittance tester to test the transmittance of the injection molded sample, and the laser wavelength is 980nm. The greater the transmittance, the better the light transmission performance, and the more conducive to laser welding.

[0104] The data in Table 1 and Table 2 were obtained through testing.

[0105]

[0106] Table 1

[0107]

[0108] Table 2

[0109] It can be seen from Table 1 and Table 2 that the PBT composite materials prepared by Examples 1-4 of the present invention have high fluidity, mechanical properties and light transmittance. Example 1 and Example 2 use high-transparency, hydrolysis-resistant glass fibers. Compared with Comparative Examples 1 and 2, their hydrolysis resistance is improved by nearly 10%, and the transmittance is nearly doubled, indicating that the use of high-transmittance hydrolysis-resistant glass fibers significantly improves water resistance and transmittance. The mechanism is: "ECT core layer + interface enhancement layer + light regulation coating" synergistically improves transmittance and interface bonding, improves welding efficiency and quality, and solves the problems of traditional glass fiber scattering and hydrolysis. The twin-screw extruder is divided into three sections using a gradient temperature control to avoid excessive degradation of PBT and maintain the mechanical properties and hydrolysis resistance of the composite material.

[0110] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A high light transmittance and hydrolysis resistant glass fiber, characterized in that: From the inside to the outside, it includes a fluorine-free and boron-free ECT glass core layer, a silane coupling agent intermediate layer, and a copolymer outer coating layer; Calculated by mass percentage, the raw materials of the fluorine-free and boron-free ECT glass core layer include silicon dioxide, aluminum oxide and calcium oxide, and the mass ratio thereof is 58-62:12-15:18-22; The raw materials of the silane coupling agent intermediate layer include at least one or more of γ-methacryloxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane and γ-glycidyloxypropyltrimethoxysilane; The raw materials of the copolymer outer coating are polyurethane, acrylic acid and a copolymer formed by polyurethane-acrylic acid.

2. A PBT composite material, characterized in that: Calculated by weight, it includes 30-70 parts of polybutylene terephthalate resin, 0.1-0.5 parts of composite black masterbatch, 1-3 parts of core-shell toughening agent, 0.2-0.6 parts of antioxidant, 0.2-0.6 parts of lubricant, 0.05-0.2 parts of ester exchange inhibitor and 30-55 parts of the high-transmittance hydrolysis-resistant glass fiber as claimed in claim 1.

3. The PBT composite material according to claim 2, characterized in that: The raw materials of the composite black masterbatch include: PBT carrier matrix; Nano carbon black, wherein the nano carbon black accounts for 0.1%-0.3% of the PBT carrier matrix according to mass percentage; Titanium dioxide, which accounts for 0.05% to 0.1% of the PBT carrier matrix by mass percentage; The hyperbranched polyester dispersant accounts for 0.5%-1% of the PBT carrier matrix according to mass percentage.

4. The PBT composite material according to claim 2, characterized in that: The core-shell toughening agent is a core-shell structure particle, the core layer is ethylene-octene copolymer, the shell layer is polymethyl methacrylate, and the mass ratio of the core layer to the shell layer is 7:

3.

5. The PBT composite material according to claim 2, characterized in that: The lubricant is pentaerythritol stearate or polyethylene wax; And / or the antioxidant is a mixture of phosphite and n-octadecylβ-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate in a mass ratio of 1:

1.

6. The PBT composite material according to claim 2, characterized in that: The transesterification inhibitor is at least one of sodium dihydrogen phosphate, sodium pyrophosphate and phosphorous acid.

7. A method for preparing a PBT composite material as claimed in any one of claims 2 to 6, characterized in that: The following steps are involved: Adding polybutylene terephthalate resin, composite black masterbatch, core-shell toughening agent, antioxidant, lubricant and transesterification inhibitor into a high-speed mixer and mixing them evenly to obtain a premix; The premix is ​​added to the main feed port of the twin-screw extruder, and the high-transmittance hydrolysis-resistant glass fiber is added to the side feed port. After shearing in the twin-screw extruder, it is fully mixed, and then extruded, cooled and pelletized in sequence to obtain the product; wherein the temperature of each section in the extrusion process adopts a dynamic gradient temperature.

8. The method for preparing the PBT composite material according to claim 7, characterized in that: The dynamic gradient temperature is: the first stage temperature is 240°C±2°C, the second stage temperature is 250°C±2°C, and the third stage temperature is 245°C±2°C.

9. The method for preparing the PBT composite material according to claim 7, characterized in that: The aspect ratio of the twin-screw extruder is 40-60:1, the screw speed of the twin-screw extruder is 300-400r / min, and the vacuum degree in the twin-screw extruder is -0.05MPa to -0.1MPa.

10. An application of the PBT composite material according to any one of claims 2 to 6, characterized in that: Apply PBT composite materials to automotive electronic laser welding parts.

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