Preparation method of reinforced fiber-containing PC / PBT composite material capable of being welded by laser

Abstract

The invention provides a preparation method of a reinforced fiber-containing PC / PBT composite material capable of laser welding, and belongs to the technical field of high polymer material preparation, and the preparation method comprises the following steps: pretreating reinforced fibers with a silane coupling agent, and reacting with nano silicon oxide and a siloxane monomer to obtain modified reinforced fibers with a micro-nano anchoring structure on the surface; then preparing a composite absorbent with a gradient structure, and pre-polymerizing and grafting part of PC / PBT to synthesize a multi-active-site compatibilizing coupling agent; and pre-mixing the rest PC / PBT with an auxiliary agent to obtain a matrix, and carrying out twin-screw segmented blending, granulation and injection molding on the matrix and the components to obtain the reinforced fiber-containing PC / PBT composite material. The invention solves the problems that the mechanical property, the laser welding property and the processing stability of the material are difficult to simultaneously meet the high-end manufacturing requirements due to insufficient interface bonding strength of fibers and a matrix of the existing material, poor compatibility of PC and PBT, single function of a laser absorbent and non-uniform dispersion of components in the processing process.

Description

Technical Field

[0001] This invention relates to the field of polymer material preparation technology, and in particular to a method for preparing laser-weldable PC / PBT composite materials containing reinforcing fibers. Background Technology

[0002] In high-end manufacturing fields such as automotive parts and electronic device packaging, the development trend of lightweighting and integration has placed stringent requirements on the comprehensive performance of engineering composite materials. PC / PBT composite materials, which combine the thermal shock resistance of PC with the chemical corrosion resistance of PBT, have become a key matrix material of industry focus due to their adaptability to various service scenarios. Their composite modification with reinforcing fibers and their compatibility with laser welding processes have become the main research directions for improving product assembly accuracy and service reliability.

[0003] Currently, to improve the mechanical properties of PC / PBT composites, the industry commonly uses glass fiber, carbon fiber, and other reinforcing agents for composite modification. The fiber surface is often treated with simple coupling agent coating to improve interfacial bonding. To achieve laser welding capabilities, a single type of laser-absorbing filler is often added directly. To address the insufficient compatibility between PC and PBT, conventional compatibilizers are frequently used for interfacial control. During processing, the resin matrix, reinforcing fibers, absorbent fillers, and various additives are typically added together to a mixing device, and after a single melt blending, they are directly granulated. This technical approach has become a mature and standard application in the production of various low- to mid-range PC / PBT composites.

[0004] However, existing technologies suffer from several unavoidable problems: First, the interfacial bonding strength between reinforcing fibers and the PC / PBT matrix is ​​insufficient. Fiber surface modification often remains at the level of single coupling agent treatment, making it prone to interfacial debonding under stress, thus limiting the improvement of material mechanical properties and resulting in poor stability. Second, laser absorbers are mostly single-component, leading to either insufficient weld penetration and low joint strength due to insufficient absorption efficiency, or localized overheating and degradation during welding due to poor thermal stability, affecting weld sealing. Third, the transesterification reaction between PC and PBT is difficult to completely suppress with conventional compatibilizers, easily leading to phase separation. Combined with the problem of uneven component dispersion during processing, this further exacerbates the fluctuation of material mechanical properties and processing defects. In addition, the performance conflict between fiber reinforcement, laser absorption, and interfacial compatibility makes it difficult for existing materials to simultaneously meet the multiple requirements of high strength, high welding quality, and processing stability. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, the purpose of this invention is to provide a method for preparing laser-weldable PC / PBT composite materials containing reinforcing fibers. By preparing modified reinforcing fibers with micro-nano anchoring structures, gradient structure composite absorbents, and multi-active-site compatibilizers in steps, and combining them with a segmented melt blending process, the interfacial bonding strength between the reinforcing fibers and the matrix and the mechanical properties of the materials are improved, the compatibility and processing stability of PC / PBT are enhanced, and the laser welding performance is optimized.

[0006] To achieve the above objectives, the present invention provides the following solution: A method for preparing laser-weldable PC / PBT composite material containing reinforcing fibers includes the following steps: S1. After pretreating the reinforcing fiber with a silane coupling agent, it is reacted with nano-silicon oxide and siloxane monomer in a polar solvent to prepare a modified reinforcing fiber with a micro-nano anchoring structure on the surface. S2. A gradient structure composite absorbent is prepared by dispersing nano-ceramic absorbent particles, nano-reinforced ceramic particles, and polymer grafts; after prepolymerizing a portion of PC resin and a portion of PBT resin according to the formula, unsaturated carboxylic acids and epoxy compounds are grafted onto them to synthesize a multi-active-site compatibilizing coupling agent. S3. Premix the remaining PC resin and PBT resin in the formula with antioxidant and lubricant in proportion to obtain a premixed matrix; S4. The premixed matrix, multi-active-site compatibilizer coupling agent, modified reinforcing fiber and gradient structure composite absorbent are added to a twin-screw extruder, and after segmented melt blending, degassing and granulation, the mixture is finally formed by injection molding to obtain a PC / PBT composite material with reinforcing fiber for laser welding.

[0007] Preferably, in S1, the reinforcing fiber is one of glass fiber and carbon fiber, the diameter of the reinforcing fiber is 5~20μm and the length is 2~8mm; the silane coupling agent is aminosilane or epoxysilane, and the pretreatment concentration of the silane coupling agent is 3%~8%.

[0008] Preferably, in S1, the nano-silicon oxide is one of nano-SiO2 or nano-SiO2-ZrO2 composite particles, and the particle size of the nano-silicon oxide is 10~100nm; the polar solvent is an ethanol-water mixture or an isopropanol-water mixture, and the volume ratio of the polar solvent is 2:1~4:1.

[0009] Preferably, in S2, the nano-ceramic absorbing particles are one or more of TiN, TiC, and ZrN, and the nano-reinforcing ceramic particles are one or more of Al2O3, SiO2, and ZrO2, with a mass ratio of 3:1 to 5:1, and the particle size of both the nano-ceramic absorbing particles and the nano-reinforcing ceramic particles is 20 to 100 nm.

[0010] Preferably, in S2, the polymer graft is maleic anhydride-grafted PC oligomer or maleic anhydride-grafted PBT oligomer, and the amount of the polymer graft added is 10% to 30% of the total mass of the nano-ceramic absorber particles and the nano-reinforced ceramic particles.

[0011] Preferably, in S2, the mass ratio of the PC resin used for prepolymerization to the PBT resin is 2:3 to 3:2, and the total mass of the two accounts for 5% to 15% of the total weight of PC resin and PBT resin in the formulation, and the prepolymerization temperature is 120 to 160°C; the unsaturated carboxylic acid is maleic anhydride or itaconic acid, the epoxy compound is epichlorohydrin or epichlorohydrin, and the grafting rate is 3% to 10%.

[0012] Preferably, in S3, the mass ratio of the remaining PC resin to the remaining PBT resin is 3:2 to 9:7, the premixing temperature is 60-100℃, and the mixing time is 10-30 min; the antioxidant is one or more of hindered phenols, phosphites, and thioesters, and the lubricant is a fatty acid amide or a fatty acid ester.

[0013] Preferably, in S4, the segmented melt blending includes: a matrix compatibilization stage with a temperature of 220~250℃ and a rotation speed of 150~250rpm; and a composite modification stage with a temperature of 240~260℃ and a rotation speed of 300~400rpm.

[0014] Preferably, in S4, the vacuum degree of the exhaust is not greater than -0.09MPa; the injection temperature of the injection molding machine is 230~260℃ and the injection pressure is 70~120MPa.

[0015] The present invention also provides a laser-weldable PC / PBT composite material containing reinforcing fibers prepared by the above-mentioned method for preparing laser-weldable PC / PBT composite material containing reinforcing fibers, comprising the following raw materials in parts by weight: 30-50 parts of PC resin, 20-40 parts of PBT resin, 15-25 parts of modified reinforcing fibers with micro-nano anchoring structures on the surface, 2-6 parts of gradient structure composite absorbent, 3-8 parts of multi-active site compatibilizer coupling agent, 0.2-0.8 parts of antioxidant, and 0.1-0.5 parts of lubricant.

[0016] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects: (1) This invention constructs a micro-nano anchoring structure on the surface of reinforcing fibers by pretreating them with silane coupling agents and reacting them with nano-silicon oxide-siloxane monomers. By using the dual effects of physical anchoring and chemical bonding, the interfacial bonding between the fibers and the PC / PBT matrix is ​​strengthened. This fundamentally improves the problem of weak interfacial bonding in traditional fiber modification and significantly enhances the tensile strength, impact toughness and other mechanical properties and performance stability of the composite material.

[0017] (2) The multi-active-site compatibilizer provided by the present invention, through the synthesis route of grafting unsaturated carboxylic acids and epoxy compounds after PC / PBT prepolymerization, makes its molecular chain carry multiple active groups, which can react with the end groups of PC and PBT respectively, effectively inhibiting transesterification reaction and phase separation. At the same time, combined with premixing and segmented blending processes, it improves the uniformity of component dispersion and greatly enhances the compatibility of PC / PBT matrix and material processing stability.

[0018] (3) This invention prepares a gradient structure composite absorber by compounding nano-ceramic absorber particles and nano-reinforced ceramic particles in a certain proportion and combining them with polymer grafting for dispersion modification. This not only ensures efficient absorption of laser energy through absorber particles to achieve sufficient melting depth, but also solves the problem of functional imbalance of single absorber by enhancing particles to disperse heat and suppress thermal deformation, thus significantly optimizing the strength and sealing of laser welding joints of materials.

[0019] (4) The present invention provides a method for preparing laser-weldable PC / PBT composite materials containing reinforcing fibers, which forms a synergistic effect by strengthening the interface of modified fibers, controlling the compatibility of compatibilizing coupling agents, and optimizing the welding of composite absorbents. This avoids the performance conflicts caused by traditional one-time mixing and achieves simultaneous improvement of the mechanical properties, laser welding performance and processing stability of composite materials, thus meeting the stringent requirements of high-end manufacturing for the multi-dimensional performance of materials. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a flowchart of a method for preparing a laser-weldable PC / PBT composite material containing reinforcing fibers, according to the present invention. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] like Figure 1 As shown, this invention provides a method for preparing laser-weldable PC / PBT composite materials containing reinforcing fibers, comprising the following steps: S1. After pretreating the reinforcing fiber with a silane coupling agent, it is reacted with nano-silicon oxide and siloxane monomer in a polar solvent to prepare a modified reinforcing fiber with a micro-nano anchoring structure on the surface.

[0025] In the above steps, the reinforcing fiber is either glass fiber or carbon fiber, with a diameter of 5~20μm and a length of 2~8mm; the silane coupling agent is either aminosilane or epoxysilane, with a pretreatment concentration of 3%~8%; the nano-silicon oxide is either nano-SiO2 or nano-SiO2-ZrO2 composite particles, with a particle size of 10~100nm; the siloxane monomer is either methyltrimethoxysilane or vinyltriethoxysilane; and the polar solvent is either an ethanol-water mixture or an isopropanol-water mixture with a volume ratio of 2:1~4:1.

[0026] Furthermore, the above pretreatment method is as follows: immerse the reinforcing fiber in an aqueous solution of silane coupling agent, stir at a temperature of 60~80℃ for 30~60 minutes, filter, and then dry at 100~120℃.

[0027] The reaction conditions are as follows: the pretreated reinforcing fibers, nano-silicon oxides, and siloxane monomers are added to a polar solvent at a mass ratio of 10:1~3:0.5~1.5, and the mixture is stirred at 70~90℃ for 2~4h. After filtration and washing, the mixture is dried at 110~130℃ for 2~3h.

[0028] S2. A gradient structure composite absorbent is prepared by dispersing nano-ceramic absorbent particles, nano-reinforced ceramic particles, and polymer grafts; after prepolymerizing a portion of PC resin and a portion of PBT resin according to the formula, unsaturated carboxylic acids and epoxy compounds are grafted onto them to synthesize a multi-active-site compatibilizing coupling agent.

[0029] In the above steps, the nano-ceramic absorber particles are one or more of TiN, TiC, and ZrN, and the nano-reinforcing ceramic particles are one or more of Al2O3, SiO2, and ZrO2, with a mass ratio of 3:1 to 5:1 and a particle size of 20 to 100 nm. The polymer graft is maleic anhydride-grafted PC oligomer or maleic anhydride-grafted PBT oligomer, and the amount added is 10% to 30% of the total mass of the two types of nano-ceramic particles. The dispersion reaction adopts high-speed shear dispersion combined with ultrasonic dispersion, with a high-speed shear rotation speed of 3000 to 5000 rpm and a time of 10 to 20 min, and an ultrasonic power of 200 to 400 W, a frequency of 25 to 40 kHz, and a time of 15 to 30 min.

[0030] Furthermore, the mass ratio of PC resin to PBT resin used for prepolymerization is 2:3 to 3:2, with the total mass accounting for 5% to 15% of the total weight of PC and PBT in the formulation; the prepolymerization temperature is 120 to 160°C, and the time is 1 to 2 hours. The unsaturated carboxylic acid is maleic anhydride or itaconic acid, and the amount added is 2% to 5% of the total mass of the prepolymer resin; the epoxy compound is epichlorohydrin or epichlorohydrin, and the amount added is 3% to 6% of the total mass of the prepolymer resin; the grafting reaction temperature is 170 to 190°C, the time is 1.5 to 3 hours, and the grafting rate is 3% to 10%.

[0031] S3. Premix the remaining PC resin and PBT resin in the formula with antioxidants and lubricants in proportion to obtain a premixed matrix.

[0032] In the above steps, the mass ratio of remaining PC resin to remaining PBT resin is 3:2 to 9:7; premixing is performed using a high-speed mixer at a mixing temperature of 60 to 100°C, a rotation speed of 800 to 1200 rpm, and a mixing time of 10 to 30 minutes. The antioxidant is one or more of hindered phenols, phosphites, and thioesters; the lubricant is a fatty acid amide (such as EBS) or a fatty acid ester (such as butyl stearate).

[0033] S4. The premixed matrix, multi-active-site compatibilizer coupling agent, modified reinforcing fiber and gradient structure composite absorbent are added to a twin-screw extruder, and after segmented melt blending, degassing and granulation, the mixture is finally formed by injection molding to obtain a PC / PBT composite material with reinforcing fiber for laser welding.

[0034] In the above steps, the twin-screw extruder has a screw diameter of 30-65 mm and a length-to-diameter ratio of 30:1-40:1. The segmented melt blending includes: a matrix compatibilization stage at a temperature of 220-250℃ and a rotation speed of 150-250 rpm; and a composite modification stage at a temperature of 240-260℃ and a rotation speed of 300-400 rpm. The exhaust vacuum is no greater than -0.09 MPa, and the blending time is 5-10 min. The injection molding machine has an injection temperature of 230-260℃, an injection pressure of 70-120 MPa, a holding pressure of 50-80 MPa, and a cooling time of 15-30 s.

[0035] The composite material prepared according to the above method comprises, by weight, the following raw materials: 30-50 parts PC resin, 20-40 parts PBT resin, 15-25 parts modified reinforcing fibers with micro-nano anchoring structures on the surface, 2-6 parts gradient structure composite absorbent, 3-8 parts multi-active-site compatibilizer coupling agent, 0.2-0.8 parts antioxidant, and 0.1-0.5 parts lubricant. The PC resin has a molecular weight of 20,000-30,000 g / mol, and the PBT resin has a molecular weight of 15,000-25,000 g / mol.

[0036] It should be noted that the PC resin, PBT resin and glass fiber used in this invention are all conventional raw materials known in the field of polymer composite materials. Among them, glass fiber treated with a single silane coupling agent is a commonly used component of traditional reinforcing materials. However, single treatment can only form a simple chemical bond, and the interfacial bonding strength is limited, which can easily lead to insufficient improvement in the mechanical properties of the material.

[0037] To address this issue, the present invention performs dual modification on the reinforcing fiber: preliminary chemical bonding sites are constructed through pretreatment with a silane coupling agent, and then reacted with nano-silicon oxide and siloxane monomers to form a micro-nano anchoring structure. This strengthens the interfacial interaction from both chemical bonding and mechanical anchoring dimensions, thus solving the problem of weak fiber-matrix interface in traditional fiber-matrix systems.

[0038] Furthermore, compared to conventional single-active compatibilizers, the multi-active-site compatibilizers of this invention can simultaneously react with the terminal hydroxyl groups of PC, the terminal carboxyl groups of PBT, and the fiber surface groups, significantly improving PC / PBT phase separation. The gradient-structure composite absorber balances laser energy absorption and thermal stability through the combination of absorbing particles and reinforcing particles, avoiding welding defects caused by a single absorber. The segmented melt blending process first achieves matrix compatibilization before composite modification, avoiding uneven component dispersion caused by one-time mixing, further ensuring the uniformity of material properties.

[0039] The above content will be further described below through specific implementation methods. The listed embodiments are only some embodiments of the present invention.

[0040] Example 1 This embodiment provides a method for preparing laser-weldable PC / PBT composite materials containing reinforcing fibers, specifically including: First, modified reinforcing fibers were prepared. The specific process was as follows: 20g of glass fibers with a length of 5mm and a diameter of 10μm were immersed in a 5% aminosilane aqueous solution and stirred at 70℃ for 45min. After filtration, the fibers were dried at 110℃. Subsequently, the pretreated glass fibers, 4g of nano-SiO2 with a particle size of 50nm, and 2g of methyltrimethoxysilane were added to 200mL of an ethanol-water mixture with a volume ratio of 3:1. The mixture was stirred and reacted at 80℃ for 3h. After filtration and washing, the fibers were dried at 120℃ for 2.5h to obtain modified glass fibers with micro-nano anchoring structures on the surface.

[0041] Secondly, a gradient structure composite absorbent and a compatibilizing coupling agent were prepared. The specific process was as follows: 3g of TiN particles and 1g of Al2O3 particles were taken, with a mass ratio of 3:1 and a particle size of 50nm. Then, 0.6g of maleic anhydride-grafted PC oligomer was added, accounting for 15% of the total mass of the two particles. The mixture was first dispersed by high-speed shearing at 4000rpm for 15min, followed by ultrasonic dispersion at 300W, 30kHz for 20min, to obtain 4g of the gradient structure composite absorbent. 6g of PC resin and 3g of PBT resin were taken, with a mass ratio of 2:1 and a total mass of 9g, accounting for 10% of the total weight of PC and PBT (90 parts by weight). The mixture was then prepolymerized at 140℃ for 1.5h, followed by the addition of 0.45g of maleic anhydride and 0.54g of propylene oxide. The mixture was reacted at 180℃ for 2h to obtain 5g of a multi-active-site compatibilizing coupling agent with a grafting rate of 6%.

[0042] Then, the premixed matrix was prepared. The specific process was as follows: 44g of the remaining PC resin and 37g of the remaining PBT resin were taken, with a mass ratio of approximately 6:5. Then, 0.4g of antioxidant 1010, 0.2g of antioxidant 168, and 0.3g of lubricant EBS were added and placed in a high-speed mixer. The mixture was mixed for 20 minutes at a temperature of 80℃ and a speed of 1000rpm to obtain the premixed matrix.

[0043] Finally, the blending process is as follows: The premixed matrix, 5g of compatibilizing coupling agent, 20g of modified glass fiber, and 4g of gradient structure composite absorbent are added to a twin-screw extruder with an aspect ratio of 35:1 and a screw diameter of 45mm. First, the matrix compatibilization stage is performed for 3 minutes at 230℃ and 200rpm, followed by a composite modification stage of 4 minutes at 250℃ and 350rpm, with exhaust under a vacuum of -0.10MPa. After extrusion granulation, the granules are added to an injection molding machine, with the injection temperature set to 245℃, injection pressure to 90MPa, holding pressure to 65MPa, and cooling time to 20s, to obtain a fiber-reinforced PC / PBT composite material for laser welding.

[0044] Example 2 This embodiment provides a method for preparing laser-weldable PC / PBT composite materials containing reinforcing fibers, specifically including: First, modified reinforcing fibers were prepared. The specific process was as follows: 25g of carbon fibers with a length of 8mm and a diameter of 20μm were immersed in an 8% epoxy silane aqueous solution and stirred at 80℃ for 60min. After filtration, the fibers were dried at 120℃. Subsequently, the pretreated carbon fibers, 7.5g of nano-SiO2-ZrO2 composite particles with a particle size of 100nm, and 3.75g of vinyltriethoxysilane were added to 300mL of isopropanol-water mixture with a volume ratio of 4:1. The mixture was stirred and reacted at 90℃ for 4h. After filtration and washing, the fibers were dried at 130℃ for 3h to obtain modified carbon fibers with micro-nano anchoring structures on the surface.

[0045] Secondly, a gradient structure composite absorbent and a compatibilizing coupling agent were prepared. The specific process was as follows: 5g of TiC particles and 1g of ZrO2 particles were taken, with a mass ratio of 5:1 and a particle size of 100nm. Then, 1.8g of maleic anhydride-grafted PBT oligomer was added, accounting for 30% of the total mass of the two particles. The mixture was first dispersed by high-speed shearing at 5000rpm for 20min, followed by ultrasonic dispersion at 400W, 40kHz for 30min, to obtain 6g of the gradient structure composite absorbent. 5g of PC resin and 5g of PBT resin were taken, with a mass ratio of 1:1, totaling 10g, accounting for 12.5% ​​of the total weight of PC and PBT (80 parts by weight). The mixture was then prepolymerized at 160℃ for 2h, followed by the addition of 0.5g of itaconic acid and 0.6g of epichlorohydrin. The mixture was reacted at 190℃ for 3h to obtain 8g of a multi-active-site compatibilizing coupling agent with a grafting rate of 10%.

[0046] Then, the premixed matrix was prepared. The specific process was as follows: 40g of the remaining PC resin and 30g of the remaining PBT resin were taken, with a mass ratio of 4:3. Then, 0.3g of antioxidant 1076, 0.3g of antioxidant 168 and 0.5g of lubricant butyl stearate were added and placed in a high-speed mixer. The mixture was mixed for 30 minutes at a temperature of 100℃ and a speed of 1200rpm to obtain the premixed matrix.

[0047] Finally, the blending process is as follows: The premixed matrix, 8g of compatibilizing coupling agent, 25g of modified carbon fiber, and 6g of gradient structure composite absorbent are added to a twin-screw extruder with an aspect ratio of 40:1 and a screw diameter of 65mm. First, the matrix compatibilization stage is performed for 4 minutes at 250℃ and 250rpm, followed by a composite modification stage of 5 minutes at 260℃ and 400rpm, with exhaust under a vacuum of -0.10MPa. After extrusion granulation, the granules are added to an injection molding machine, with the injection temperature set to 260℃, injection pressure to 120MPa, holding pressure to 80MPa, and cooling time to 30s, to obtain a fiber-reinforced PC / PBT composite material for laser welding.

[0048] Example 3 This embodiment provides a method for preparing laser-weldable PC / PBT composite materials containing reinforcing fibers, specifically including: First, modified reinforcing fibers were prepared. The specific process was as follows: 15g of glass fibers with a length of 2mm and a diameter of 5μm were immersed in a 3% aminosilane aqueous solution and stirred at 60℃ for 30min. After filtration, the fibers were dried at 100℃. Subsequently, the pretreated glass fibers, 1.5g of nano-SiO2 with a particle size of 10nm, and 0.75g of methyltrimethoxysilane were added to 150mL of an ethanol-water mixture with a volume ratio of 2:1. The mixture was stirred and reacted at 70℃ for 2h. After filtration and washing, the fibers were dried at 110℃ for 2h to obtain modified glass fibers with micro-nano anchoring structures on the surface.

[0049] Secondly, a gradient structure composite absorbent and a compatibilizing coupling agent were prepared. The specific process was as follows: 1.5g of ZrN particles and 0.5g of SiO2 particles were taken, with a mass ratio of 3:1 and a particle size of 20nm. Then, 0.2g of maleic anhydride-grafted PC oligomer was added, accounting for 10% of the total mass of the two particles. The mixture was first dispersed by high-speed shearing at 3000rpm for 10min, followed by ultrasonic dispersion at 200W, 25kHz for 15min, to obtain 2g of gradient structure composite absorbent. 3g of PC resin and 3g of PBT resin were taken, with a mass ratio of 1:1 and a total mass of 6g, accounting for 7.1% of the total weight of PC and PBT (85 parts by weight). The mixture was then prepolymerized at 120℃ for 1h. Then, 0.18g of maleic anhydride and 0.24g of propylene oxide were added, and the mixture was reacted at 170℃ for 1.5h to obtain 3g of multi-active site compatibilizing coupling agent with a grafting rate of 3%.

[0050] Then, the premixed matrix was prepared. The specific process was as follows: 47g of the remaining PC resin and 37g of the remaining PBT resin were taken, with a mass ratio of 3:2. Then, 0.2g of antioxidant DLTP and 0.1g of lubricant EBS were added, and the mixture was placed in a high-speed mixer and mixed for 10 minutes at a temperature of 60℃ and a speed of 800rpm to obtain the premixed matrix.

[0051] Finally, the blending process is as follows: The premixed matrix, 3g of compatibilizing coupling agent, 15g of modified glass fiber, and 2g of gradient structure composite absorbent are added to a twin-screw extruder with an aspect ratio of 30:1 and a screw diameter of 30mm. First, the matrix compatibilization stage is performed for 2 minutes at 220℃ and 150rpm, followed by a composite modification stage of 3 minutes at 240℃ and 300rpm, with exhaust at a vacuum of -0.09MPa during the process. After extrusion granulation, the granules are added to an injection molding machine, with the injection temperature set to 230℃, injection pressure to 70MPa, holding pressure to 50MPa, and cooling time to 15s, to obtain a reinforced fiber PC / PBT composite material for laser welding.

[0052] Example 4 This embodiment provides a method for preparing laser-weldable PC / PBT composite materials containing reinforcing fibers, specifically including: First, modified reinforcing fibers were prepared. The specific process was as follows: 22g of glass fibers with a length of 6mm and a diameter of 15μm were immersed in a 6% epoxy silane aqueous solution and stirred at 75℃ for 50min. After filtration, the fibers were dried at 115℃. Subsequently, the pretreated glass fibers, 4.4g of nano-SiO2-ZrO2 composite particles with a particle size of 80nm, and 2.2g of vinyltriethoxysilane were added to 250mL of isopropanol-water mixture with a volume ratio of 3.5:1. The mixture was stirred and reacted at 85℃ for 3.5h. After filtration and washing, the fibers were dried at 125℃ for 2.5h to obtain modified glass fibers with micro-nano anchoring structures on the surface.

[0053] Secondly, a gradient structure composite absorbent and compatibilizing coupling agent were prepared. The specific process was as follows: 3g of TiN particles, 1.5g of TiC particles, and 1.5g of Al2O3 particles were taken, with a total mass of 4.5g of absorbent particles and 1.5g of reinforcing particles, and a mass ratio of 3:1. The particle size of all particles was 80nm. Then, 1.2g of maleic anhydride-grafted PBT oligomer was added, which accounted for 20% of the total mass of the two types of particles. The particles were first dispersed by high-speed shearing at 4500rpm for 18min, and then ultrasonically dispersed at 350W for 35kHz for 25min to obtain 5g of gradient structure composite absorbent. Take 6g of PC resin and 4g of PBT resin in a mass ratio of 3:2, with a total mass of 10g, accounting for 13.3% of the total weight of PC and PBT (75 parts). Then, prepolymerize at 150℃ for 1.8h. Next, add 0.5g of maleic anhydride and 0.6g of epichlorohydrin, and react at 185℃ for 2.5h to obtain 6g of multi-active-site compatibilizer coupling agent with a grafting rate of 8%.

[0054] Then, the premixed matrix was prepared. The specific process was as follows: 44g of the remaining PC resin and 31g of the remaining PBT resin were taken, with a mass ratio of approximately 7:5. Then, 0.3g of antioxidant 1010, 0.2g of antioxidant 168, and 0.4g of lubricant butyl stearate were added and placed in a high-speed mixer. The mixture was mixed for 25 minutes at a temperature of 90℃ and a rotation speed of 1100rpm to obtain the premixed matrix.

[0055] Finally, the blending process is as follows: The premixed matrix, 6g of compatibilizing coupling agent, 22g of modified glass fiber, and 5g of gradient structure composite absorbent are added to a twin-screw extruder with an aspect ratio of 38:1 and a screw diameter of 50mm. First, the matrix compatibilization stage is performed for 3.5 minutes at 240℃ and 220rpm, then the temperature is increased to 255℃ and 380rpm for a composite modification stage of 4.5 minutes, with exhaust at a vacuum of -0.10MPa during the process. After extrusion granulation, the granules are added to an injection molding machine, with the injection temperature set to 250℃, injection pressure to 100MPa, holding pressure to 70MPa, and cooling time to 25s, to obtain a fiber-reinforced PC / PBT composite material for laser welding.

[0056] Comparative Example 1 The only difference between this comparative example and Example 1 is that the reinforcing fibers were not modified by the nano-silicon oxide-siloxane monomer reaction, but only pretreated with a silane coupling agent. The amounts of other materials and process parameters are the same, specifically including: First, the modified reinforcing fiber was prepared. The specific process was as follows: 20g of glass fiber with a length of 5mm and a diameter of 10μm was taken, immersed in 5% aminosilane aqueous solution, stirred at 70℃ for 45min, filtered, and dried in an environment of 110℃, and directly used as modified glass fiber without micro-nano anchoring structure on the surface.

[0057] Secondly, a gradient structure composite absorbent and a compatibilizing coupling agent were prepared, following the same procedure as in Example 1: 3g of TiN particles and 1g of Al2O3 particles were taken, with a mass ratio of 3:1 and a particle size of 50nm. Then, 0.6g of maleic anhydride-grafted PC oligomer was added, accounting for 15% of the total mass of the two particles. The mixture was first dispersed by high-speed shearing at 4000rpm for 15min, followed by ultrasonic dispersion at 300W, 30kHz for 20min, yielding 4g of the gradient structure composite absorbent. 6g of PC resin and 3g of PBT resin were taken, with a mass ratio of 2:1 and a total mass of 9g, accounting for 10% of the total 90 parts by weight of PC and PBT. The mixture was then prepolymerized at 140℃ for 1.5h, followed by the addition of 0.45g of maleic anhydride and 0.54g of propylene oxide. The reaction was carried out at 180℃ for 2h, yielding 5g of a multi-active-site compatibilizing coupling agent with a grafting rate of 6%.

[0058] Then, the premixed matrix was prepared, and the specific process was exactly the same as in Example 1: 44g of the remaining PC resin and 37g of the remaining PBT resin were taken, with a mass ratio of about 6:5. Then, 0.4g of antioxidant 1010, 0.2g of antioxidant 168 and 0.3g of lubricant EBS were added and placed in a high-speed mixer. The mixture was mixed for 20 minutes at a temperature of 80℃ and a speed of 1000rpm to obtain the premixed matrix.

[0059] Finally, the blending process was exactly the same as in Example 1: The premixed matrix, 5g of compatibilizing coupling agent, 20g of modified glass fiber, and 4g of gradient structure composite absorbent were added to a twin-screw extruder with an aspect ratio of 35:1 and a screw diameter of 45mm. First, the matrix compatibilization stage was performed for 3 minutes at 230℃ and 200rpm, followed by a composite modification stage of 4 minutes at 250℃ and 350rpm, with exhaust under a vacuum of -0.10MPa. After extrusion granulation, the granules were added to an injection molding machine, with the injection temperature set to 245℃, injection pressure to 90MPa, holding pressure to 65MPa, and cooling time to 20s, to obtain a PC / PBT composite material containing reinforcing fibers.

[0060] Comparative Example 2 The only difference between this comparative example and Example 1 is that it uses a single TiN particle as the laser absorber, without a gradient structure. The amounts of other materials and process parameters are the same, specifically including: First, modified reinforcing fibers were prepared, following the same procedure as in Example 1: 20g of glass fibers with a length of 5mm and a diameter of 10μm were immersed in a 5% aminosilane aqueous solution and stirred at 70℃ for 45min. After filtration, the fibers were dried at 110℃. Subsequently, the pretreated glass fibers, 4g of nano-SiO2 with a particle size of 50nm, and 2g of methyltrimethoxysilane were added to 200mL of an ethanol-water mixture with a volume ratio of 3:1. The mixture was stirred and reacted at 80℃ for 3h. After filtration and washing, the fibers were dried at 120℃ for 2.5h to obtain modified glass fibers with micro-nano anchoring structures on the surface.

[0061] Secondly, the absorbent and compatibilizing coupling agent were prepared. The specific process was as follows: 4g of TiN particles were taken to replace TiN+Al2O3 in Example 1, and then 0.6g of maleic anhydride-grafted PC oligomer was added. The mixture was first dispersed by high-speed shearing at 4000 rpm for 15 min, and then ultrasonically dispersed at 300W, 30kHz for 20 min to obtain 4g of single-structure absorbent. The preparation process of the compatibilizing coupling agent was completely consistent with that in Example 1: 6g of PC resin and 3g of PBT resin were taken in a mass ratio of 2:1, with a total mass of 9g, accounting for 10% of the total weight of PC and PBT (90 parts). The mixture was then prepolymerized at 140℃ for 1.5h, and then 0.45g of maleic anhydride and 0.54g of propylene oxide were added. The mixture was reacted at 180℃ for 2h to obtain 5g of multi-active-site compatibilizing coupling agent with a grafting rate of 6%.

[0062] Then, the premixed matrix was prepared, and the specific process was exactly the same as in Example 1: 44g of the remaining PC resin and 37g of the remaining PBT resin were taken, with a mass ratio of about 6:5. Then, 0.4g of antioxidant 1010, 0.2g of antioxidant 168 and 0.3g of lubricant EBS were added and placed in a high-speed mixer. The mixture was mixed for 20 minutes at a temperature of 80℃ and a speed of 1000rpm to obtain the premixed matrix.

[0063] Finally, the blending molding process was completely consistent with Example 1: The premixed matrix, 5g of compatibilizing coupling agent, 20g of modified glass fiber, and 4g of single-structure absorbent were added to a twin-screw extruder with an aspect ratio of 35:1 and a screw diameter of 45mm. First, the matrix compatibilization stage was performed for 3 minutes at 230℃ and 200rpm, followed by a composite modification stage of 4 minutes at 250℃ and 350rpm, with exhaust under a vacuum of -0.10MPa. After extrusion granulation, the granules were added to an injection molding machine, with the injection temperature set to 245℃, injection pressure to 90MPa, holding pressure to 65MPa, and cooling time to 20s, to obtain a PC / PBT composite material containing reinforcing fibers.

[0064] Comparative Example 3 The only difference between this comparative example and Example 1 is that maleic anhydride-grafted POE (a conventional compatibilizer) is used instead of the multi-active-site compatibilizer coupling agent. All other material dosages and process parameters remain the same, specifically including: First, modified reinforcing fibers were prepared, following the same procedure as in Example 1: 20g of glass fibers with a length of 5mm and a diameter of 10μm were immersed in a 5% aminosilane aqueous solution and stirred at 70℃ for 45min. After filtration, the fibers were dried at 110℃. Subsequently, the pretreated glass fibers, 4g of nano-SiO2 with a particle size of 50nm, and 2g of methyltrimethoxysilane were added to 200mL of an ethanol-water mixture with a volume ratio of 3:1. The mixture was stirred and reacted at 80℃ for 3h. After filtration and washing, the fibers were dried at 120℃ for 2.5h to obtain modified glass fibers with micro-nano anchoring structures on the surface.

[0065] Secondly, the gradient structure composite absorbent and compatibilizer were prepared. The specific process was as follows: The preparation of the gradient structure composite absorbent was completely consistent with Example 1: 3g of TiN particles and 1g of Al2O3 particles were taken, with a mass ratio of 3:1 and a particle size of 50nm. Then, 0.6g of maleic anhydride-grafted PC oligomer was added, accounting for 15% of the total mass of the two particles. The mixture was first dispersed by high-speed shearing at 4000rpm for 15min, followed by ultrasonic dispersion at 300W, 30kHz for 20min, yielding 4g of the gradient structure composite absorbent. 5g of maleic anhydride-grafted POE was used to replace the multi-active-site compatibilizer coupling agent in Example 1.

[0066] Then, the premixed matrix was prepared, and the specific process was exactly the same as in Example 1: 44g of the remaining PC resin and 37g of the remaining PBT resin were taken, with a mass ratio of about 6:5. Then, 0.4g of antioxidant 1010, 0.2g of antioxidant 168 and 0.3g of lubricant EBS were added and placed in a high-speed mixer. The mixture was mixed for 20 minutes at a temperature of 80℃ and a speed of 1000rpm to obtain the premixed matrix.

[0067] Finally, the blending molding process was completely consistent with Example 1: The premixed matrix, 5g of maleic anhydride-grafted POE, 20g of modified glass fiber, and 4g of gradient structure composite absorbent were added to a twin-screw extruder with an aspect ratio of 35:1 and a screw diameter of 45mm. First, a matrix compatibilization stage of blending was performed for 3 minutes at 230℃ and 200rpm, followed by a composite modification stage of blending for 4 minutes at 250℃ and 350rpm, with exhaust under a vacuum of -0.10MPa during the process. After extrusion granulation, the granules were added to an injection molding machine, with the injection temperature set to 245℃, injection pressure to 90MPa, holding pressure to 65MPa, and cooling time to 20s, to obtain a PC / PBT composite material containing reinforcing fibers.

[0068] Comparative Example 4 The only difference between this comparative example and Example 1 is that it uses a one-time melt blending process (without segmentation); the amounts of all other materials and process parameters are the same, specifically including: First, modified reinforcing fibers were prepared, following the same procedure as in Example 1: 20g of glass fibers with a length of 5mm and a diameter of 10μm were immersed in a 5% aminosilane aqueous solution and stirred at 70℃ for 45min. After filtration, the fibers were dried at 110℃. Subsequently, the pretreated glass fibers, 4g of nano-SiO2 with a particle size of 50nm, and 2g of methyltrimethoxysilane were added to 200mL of an ethanol-water mixture with a volume ratio of 3:1. The mixture was stirred and reacted at 80℃ for 3h. After filtration and washing, the fibers were dried at 120℃ for 2.5h to obtain modified glass fibers with micro-nano anchoring structures on the surface.

[0069] Secondly, a gradient structure composite absorbent and a compatibilizing coupling agent were prepared, following the same procedure as in Example 1: 3g of TiN particles and 1g of Al2O3 particles were taken, with a mass ratio of 3:1 and a particle size of 50nm. Then, 0.6g of maleic anhydride-grafted PC oligomer was added, accounting for 15% of the total mass of the two particles. The mixture was first dispersed by high-speed shearing at 4000rpm for 15min, followed by ultrasonic dispersion at 300W, 30kHz for 20min, yielding 4g of the gradient structure composite absorbent. 6g of PC resin and 3g of PBT resin were taken, with a mass ratio of 2:1 and a total mass of 9g, accounting for 10% of the total 90 parts by weight of PC and PBT. The mixture was then prepolymerized at 140℃ for 1.5h, followed by the addition of 0.45g of maleic anhydride and 0.54g of propylene oxide. The reaction was carried out at 180℃ for 2h, yielding 5g of a multi-active-site compatibilizing coupling agent with a grafting rate of 6%.

[0070] Then, the premixed matrix was prepared, and the specific process was exactly the same as in Example 1: 44g of the remaining PC resin and 37g of the remaining PBT resin were taken, with a mass ratio of about 6:5. Then, 0.4g of antioxidant 1010, 0.2g of antioxidant 168 and 0.3g of lubricant EBS were added and placed in a high-speed mixer. The mixture was mixed for 20 minutes at a temperature of 80℃ and a speed of 1000rpm to obtain the premixed matrix.

[0071] Finally, the blending process was as follows: The premixed matrix, 5g of compatibilizing coupling agent, 20g of modified glass fiber, and 4g of gradient structure composite absorbent were added to a twin-screw extruder with an aspect ratio of 35:1 and a screw diameter of 45mm. The mixture was directly blended for 7 minutes at 250℃ and 350rpm, with exhaust gas at a vacuum of -0.10MPa during the process. After extrusion granulation, the granules were added to an injection molding machine, with the injection temperature set to 245℃, injection pressure to 90MPa, holding pressure to 65MPa, and cooling time to 20s, to obtain a PC / PBT composite material containing reinforcing fibers.

[0072] The performance of the composite materials prepared in Examples 1-4 and Comparative Examples 1-4 was tested below. The test standards are as follows: tensile strength refers to GB / T1040-2018, flexural strength and flexural modulus refer to ISO 178, notched impact strength of simply supported beam refers to ISO 179 (test environment 23℃), 980nm infrared laser transmittance is tested using an LPKF TMG3 transmittance meter (test sample thickness 2.0mm), and warpage is directly evaluated by injection molded parts (with the mating clearance as the indicator). The performance results are summarized in Table 1.

[0073] Table 1 Performance Test Results

[0074] Referring to Table 1, the composite materials prepared in Examples 1-4 of this invention exhibit excellent comprehensive properties, with flexural strength of 185-203 MPa, flexural modulus of 8792-8957 MPa, and notched impact strength of simply supported beams of 8.0-9.2 kJ / m. 2 With a 980nm infrared laser transmittance of 26~42% and a warpage of 14~25μm, it fully meets the synergistic requirements of high-end manufacturing for "high rigidity, anti-warpage, and laser transmission". It can be adapted to scenarios such as automotive precision parts and electronic equipment packaging, and solves the problems of poor adhesion and poor fusion of traditional materials.

[0075] Comparing Example 1 and Comparative Example 1, it is evident that the micro-nano anchoring structure on the fiber surface is key to optimizing optical and forming properties: While the changes in mechanical properties such as tensile strength and flexural strength are relatively small after the absence of this structure, the 980nm laser transmittance drops sharply from 42% to 21%, and the warpage increases from 14μm to 28μm. This demonstrates that the micro-nano anchoring structure can reduce fiber-matrix interface defects, decrease light scattering, alleviate internal stress concentration, and simultaneously improve light transmittance and warpage resistance. Comparing Example 1 and Comparative Example 2, it is clear that the gradient structure composite absorber is crucial for the material's mechanical stability and light transmittance: a single TiN absorber causes the flexural modulus to decrease from 8792MPa to 8450MPa, and the notched impact strength of a simply supported beam to decrease from 8.8kJ / m. 2 Reduced to 8.0 kJ / m 2 Furthermore, the transmittance is only 22%. Due to the lack of dispersion and reinforcement of nano-reinforcing particles, the rigidity of the material decreases and the laser energy absorption is uneven, which affects the structural stability and easily leads to insufficient weld penetration.

[0076] Comparing Example 1 and Comparative Example 3, it can be found that without the addition of an ester exchange inhibitor and using only a conventional compatibilizer, the notched impact strength of the simply supported beam increased from 8.8 kJ / m. 2 It dropped sharply to 4.5 kJ / m 2 The reduction was over 48%, with the flexural modulus decreasing from 8792 MPa to 8400 MPa, thus proving that the dedicated inhibitor can effectively stabilize the PC / PBT interface and prevent a precipitous drop in impact performance. Comparing Example 1 and Comparative Example 4, it is clear that the segmented melt blending process is key to ensuring performance uniformity: single-stage mixing resulted in a decrease in flexural strength from 187 MPa to 185 MPa, a decrease in 980 nm laser transmittance from 42% to 23%, and an increase in warpage from 14 μm to 29 μm. Uneven dispersion of the resin and fiber caused localized component agglomeration, weakening mechanical properties and disrupting light transmittance consistency, further highlighting the importance of segmented blending for uniform component dispersion and synergistic performance optimization.

[0077] It should also be noted that Example 3, due to its high PBT content, has a flexural strength of 203 MPa and a flexural modulus of 8957 MPa, making it suitable for structural components with extremely high rigidity requirements; Example 1, due to its optimized PC content, has a 980nm laser transmittance of 42% and a warpage of 14 μm, making it suitable for scenarios with stringent requirements for welding precision and light transmittance. This demonstrates that the present invention can be adapted to different high-end manufacturing needs through formula adjustments.

[0078] Therefore, the above-mentioned method for preparing laser-weldable PC / PBT composite materials containing reinforcing fibers improves the interfacial bonding strength between the reinforcing fibers and the matrix and the mechanical properties of the materials by stepwise preparing modified reinforcing fibers with micro-nano anchoring structures, gradient structure composite absorbents and multi-active-site compatibilizers, combined with a segmented melt blending process. This improves the compatibility and processing stability of PC / PBT, while also optimizing the laser welding performance.

[0079] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0080] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for preparing laser-weldable PC / PBT composite material containing reinforcing fibers, characterized in that, Includes the following steps: S1. After pretreating the reinforcing fiber with a silane coupling agent, it is reacted with nano-silicon oxide and siloxane monomer in a polar solvent to prepare a modified reinforcing fiber with a micro-nano anchoring structure on the surface. S2. A gradient structure composite absorbent is prepared by dispersing nano-ceramic absorbent particles, nano-reinforced ceramic particles, and polymer grafts; after prepolymerizing a portion of PC resin and a portion of PBT resin according to the formula, unsaturated carboxylic acids and epoxy compounds are grafted onto them to synthesize a multi-active-site compatibilizing coupling agent. S3. Premix the remaining PC resin and PBT resin in the formula with antioxidant and lubricant in proportion to obtain a premixed matrix; S4. The premixed matrix, multi-active-site compatibilizer coupling agent, modified reinforcing fiber and gradient structure composite absorbent are added to a twin-screw extruder, and after segmented melt blending, degassing and granulation, the mixture is finally formed by injection molding to obtain a PC / PBT composite material with reinforcing fiber for laser welding.

2. The method for preparing a laser-weldable PC / PBT composite material containing reinforcing fibers according to claim 1, characterized in that, In S1, the reinforcing fiber is one of glass fiber and carbon fiber, the diameter of the reinforcing fiber is 5~20μm and the length is 2~8mm; the silane coupling agent is aminosilane or epoxysilane, and the pretreatment concentration of the silane coupling agent is 3%~8%.

3. The method for preparing a laser-weldable PC / PBT composite material containing reinforcing fibers according to claim 1, characterized in that, In S1, the nano-silicon oxide is one of nano-SiO2 or nano-SiO2-ZrO2 composite particles, and the particle size of the nano-silicon oxide is 10~100nm; the polar solvent is an ethanol-water mixture or an isopropanol-water mixture, and the volume ratio of the polar solvent is 2:1~4:

1.

4. The method for preparing a laser-weldable PC / PBT composite material containing reinforcing fibers according to claim 1, characterized in that, In S2, the nano-ceramic absorbing particles are one or more of TiN, TiC, and ZrN, and the nano-reinforcing ceramic particles are one or more of Al2O3, SiO2, and ZrO2, with a mass ratio of 3:1 to 5:

1. The particle size of both the nano-ceramic absorbing particles and the nano-reinforcing ceramic particles is 20 to 100 nm.

5. The method for preparing a laser-weldable PC / PBT composite material containing reinforcing fibers according to claim 1, characterized in that, In S2, the polymer graft is maleic anhydride-grafted PC oligomer or maleic anhydride-grafted PBT oligomer, and the amount of the polymer graft added is 10% to 30% of the total mass of the nano-ceramic absorber particles and nano-reinforced ceramic particles.

6. The method for preparing a laser-weldable PC / PBT composite material containing reinforcing fibers according to claim 1, characterized in that, In S2, the mass ratio of PC resin to PBT resin used for prepolymerization is 2:3 to 3:2, and the total mass of the two accounts for 5% to 15% of the total weight of PC resin and PBT resin in the formulation. The prepolymerization temperature is 120 to 160°C. The unsaturated carboxylic acid is maleic anhydride or itaconic acid, and the epoxy compound is propylene oxide or epichlorohydrin with a grafting rate of 3% to 10%.

7. The method for preparing a laser-weldable PC / PBT composite material containing reinforcing fibers according to claim 1, characterized in that, In S3, the mass ratio of the remaining PC resin to the remaining PBT resin is 3:2 to 9:7, the premixing temperature is 60-100℃, and the mixing time is 10-30 min; the antioxidant is one or more of hindered phenols, phosphites, and thioesters, and the lubricant is a fatty acid amide or a fatty acid ester.

8. The method for preparing a laser-weldable PC / PBT composite material containing reinforcing fibers according to claim 1, characterized in that, In S4, the segmented melt blending includes: a matrix compatibilization stage with a temperature of 220~250℃ and a rotation speed of 150~250rpm; and a composite modification stage with a temperature of 240~260℃ and a rotation speed of 300~400rpm.

9. The method for preparing a laser-weldable PC / PBT composite material containing reinforcing fibers according to claim 1, characterized in that, In S4, the vacuum degree of the exhaust is not greater than -0.09MPa; the injection temperature of the injection molding machine is 230~260℃ and the injection pressure is 70~120MPa.

10. A laser-weldable PC / PBT composite material containing reinforcing fibers, prepared by the method for preparing laser-weldable PC / PBT composite material containing reinforcing fibers according to any one of claims 1 to 9, characterized in that, The raw materials consist of the following parts by weight: 30-50 parts PC resin, 20-40 parts PBT resin, 15-25 parts modified reinforcing fiber with micro-nano anchoring structure on the surface, 2-6 parts gradient structure composite absorbent, 3-8 parts multi-active site compatibilizer coupling agent, 0.2-0.8 parts antioxidant, and 0.1-0.5 parts lubricant.

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