A light-transmitting laser-welded PC / PBT composite material and its preparation method

Abstract

This invention relates to the field of resin technology, specifically to a light-transmitting enhanced laser-welded PC / PBT composite material and its preparation method. The composite material comprises, by weight, the following components: 27.6–44 parts PC, 27.6–43 parts PBT, 20–30 parts modified glass fiber, 0.5–1.0 parts transesterification inhibitor, 0.1–0.2 parts antioxidant, and 0.1–0.2 parts non-silicone defoamer. This invention utilizes modified glass fiber with a refractive index close to that of the PC / PBT resin matrix, improving the infrared transmittance of the composite material. Furthermore, by constructing a porous nano-coating on the surface of the ECR glass fiber, a refractive index gradient transition layer is formed by melt co-extrusion of the porous nano-coating with PC / PBT, significantly improving the light transmittance of the composite material. This achieves a good balance between light transmittance and mechanical properties, and can be widely applied to laser-welded components for new energy vehicles, infrared optical housings, etc.

Description

Technical Field

[0001] This invention relates to the field of resin technology, specifically to a light-transmitting enhanced laser-welded PC / PBT composite material and its preparation method. Background Technology

[0002] PC / PBT composites combine the excellent electrical properties, solvent resistance, and good injection molding performance of PBT with the high notched impact strength and high heat resistance of PC. They also have relatively low crystallinity, effectively reducing warpage and providing excellent dimensional stability. Using glass fiber (GF) to reinforce PC / PBT composites further enhances the material's mechanical properties, heat resistance, and dimensional stability, while also reducing production costs. This has led to their widespread application in the automotive, electronics, home appliance, and laser welding industries.

[0003] Glass fiber reinforced PC / PBT can significantly improve the mechanical strength of the material, but the difference in refractive index between the glass fiber and the resin matrix can easily lead to interfacial light scattering and reduce infrared transmittance. Summary of the Invention

[0004] The purpose of this invention is to provide a light-transmitting enhanced laser-welded PC / PBT composite material and its preparation method, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a light-transmitting enhanced laser-welded PC / PBT composite material, wherein the composite material comprises the following components by weight: 27.6–44 parts PC, 27.6–43 parts PBT, 20–30 parts modified glass fiber, 0.5–1.0 parts transesterification inhibitor, 0.1–0.2 parts antioxidant, and 0.1–0.2 parts non-silicone defoamer;

[0006] The mass ratio of PC to PBT is (2:3) to (3:2), the PC is optical grade polycarbonate resin with a molecular weight of 20,000 to 30,000 g / mol and a refractive index of 1.591, the PBT is injection molding grade polybutylene terephthalate with a molecular weight of 40,000 to 45,000 g / mol and a refractive index of 1.580, and the refractive index of the modified glass fiber is 1.582 to 1.585.

[0007] The preparation method of the modified glass fiber includes the following steps: Tetraethoxysilane, phenyltriethoxysilane, methyltriethoxysilane, tetrabutyl titanate, water, and ethanol are mixed in a molar ratio of 1:(0.9–1.1):(0.25–0.35):(0.20–0.30):(3.5–4.5):(7.5–8.5) to obtain a sol; 0.05 mol / L dilute hydrochloric acid is added dropwise to the sol to adjust the pH to 2–3, followed by the addition of 4–6 wt% PEO-b-PPO, and stirring at 120 rpm for 1–2 h at room temperature to obtain a clear sol; the clear sol and ECR glass fiber are placed in an impregnation tank, and then... A nitrogen flow of 0.1–0.2 m / s is introduced into the impregnation tank to keep the ECR glass fibers in a turbulent suspension state for 20–30 min to obtain impregnated glass fibers. The impregnated glass fibers are then transferred to a horizontal centrifugal dryer and centrifuged at 800 rpm for 30–40 s to make the wet film thickness on the surface of the impregnated glass fibers 8–10 µm. Subsequently, they are placed in a constant temperature water bath at 72–75 °C for 30 min to obtain wet gel glass fibers. The wet gel glass fibers are dried in supercritical CO2 at 60–70 °C / 12–16 MPa for 30–50 min, and then cured in nitrogen at 260–280 °C for 30–35 min to obtain the modified glass fibers.

[0008] Optionally, the melt flow rate of the PC is 12.5±2.0 g / 10 min, and the intrinsic viscosity of the PBT is 0.83±0.02 dL.

[0009] Optionally, the modified glass fiber has a length of 3.0 to 4.0 mm and a diameter of 12 to 14 μm.

[0010] Optionally, the transesterification inhibitor is sodium dihydrogen phosphate or transesterification inhibitor SA-PGP-B.

[0011] Optionally, the antioxidant is a hindered phenolic antioxidant or a phosphite antioxidant.

[0012] Optionally, the non-silicone defoamer is BYK-3155 or AFCONA-2720.

[0013] On the other hand, the present invention also provides the following technical solution: a method for preparing a light-transmitting enhanced laser-welded PC / PBT composite material, comprising the following steps:

[0014] S1: Add PC, PBT, transesterification inhibitor, antioxidant, and non-silicone defoamer to a high-speed mixer and mix thoroughly to obtain a premix.

[0015] S2: The premixed material is added to the main feed port of the twin-screw extruder, and the modified glass fiber is added to the side feed port of the twin-screw extruder. After melting, extrusion, granulation, and air drying, the composite material is obtained.

[0016] Optionally, the twin-screw extruder has a screw length-to-diameter ratio of (42-46):1 and a rotational speed of 300-400 rpm / min.

[0017] Optionally, the temperatures of each zone of the twin-screw extruder include: zone 1 temperature 220-230℃, zone 2 temperature 235-245℃, zone 3 temperature 235-245℃, zone 4 temperature 245-250℃, zone 5 temperature 250-255℃, zone 6 temperature 240-245℃, and die head temperature 235-240℃.

[0018] Compared with the prior art, the present invention has the following beneficial effects: The present invention uses modified glass fiber with a refractive index close to that of PC / PBT resin matrix, which improves the infrared transmittance of composite material. By constructing a porous nano-coating on the surface of ECR ​​glass fiber, the porous nano-coating and PC / PBT are melt-co-extruded to form a refractive index gradient transition layer, which significantly improves the light transmittance of composite material and achieves a good balance between light transmittance and mechanical properties. It can be widely used in laser welding parts of new energy vehicles, infrared optical housings, etc. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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.

[0020] Example 1

[0021] This invention provides a light-transmitting enhanced laser-welded PC / PBT composite material. The composite material comprises the following components by weight: 34.6 parts PC, 34.6 parts PBT, 30 parts modified glass fiber, 0.5 parts transesterification inhibitor, 0.2 parts antioxidant, and 0.1 parts non-silicone defoamer. The modified glass fiber has a length of 3.0 mm and a diameter of 12 μm. The transesterification inhibitor is sodium dihydrogen phosphate. The antioxidant is a hindered phenolic antioxidant. The non-silicone defoamer is BYK-3155.

[0022] The preparation method of modified glass fiber includes the following steps: Tetraethoxysilane, phenyltriethoxysilane, methyltriethoxysilane, tetrabutyl titanate, water, and ethanol are mixed in a molar ratio of 1:1:0.3:0.25:4.0:8.0 to obtain a sol; 0.05 mol / L dilute hydrochloric acid is added dropwise to the sol to adjust the pH to 2, followed by the addition of 4 wt% PEO-b-PPO, and stirring at 120 rpm for 1 h at room temperature to obtain a clear sol; the clear sol and ECR glass fiber are placed in an impregnation tank, and the mixture is then added to the impregnation tank... A nitrogen flow of 0.1 m / s was introduced to keep the ECR glass fiber in a turbulent suspension state for 20 min to obtain impregnated glass fiber. The impregnated glass fiber was then transferred to a horizontal centrifuge and centrifuged at 800 rpm for 30 s to make the wet film thickness on the surface of the impregnated glass fiber 8 µm. Subsequently, it was placed in a constant temperature water bath at 72℃ for 30 min to obtain wet gel glass fiber. The wet gel glass fiber was dried in supercritical CO2 at 60℃ / 12 MPa for 30 min, and then cured in nitrogen at 260℃ for 30 min to obtain modified glass fiber.

[0023] The above-mentioned method for preparing the light-transmitting enhanced laser-welded PC / PBT composite material includes the following steps:

[0024] S1: Add PC, PBT, transesterification inhibitor, antioxidant, and non-silicone defoamer to a high-speed mixer and mix thoroughly to obtain a premix.

[0025] S2: The premixed material is added to the main feed port of the twin-screw extruder, and the modified glass fiber is added to the side feed port of the twin-screw extruder. After melting, extrusion, granulation and air drying, the composite material is obtained.

[0026] The twin-screw extruder has a screw length-to-diameter ratio of 42:1 and a rotational speed of 300 rpm / min.

[0027] Example 2

[0028] This invention provides a light-transmitting enhanced laser-welded PC / PBT composite material. The composite material comprises the following components by weight: 41.4 parts PC, 27.6 parts PBT, 30 parts modified glass fiber, 0.7 parts transesterification inhibitor, 0.2 parts antioxidant, and 0.1 parts non-silicone defoamer. The modified glass fiber has a length of 3.2 mm and a diameter of 13 μm. The transesterification inhibitor is sodium dihydrogen phosphate. The antioxidant is a hindered phenolic antioxidant. The non-silicone defoamer is BYK-3155.

[0029] The preparation method of modified glass fiber includes the following steps: Tetraethoxysilane, phenyltriethoxysilane, methyltriethoxysilane, tetrabutyl titanate, water, and ethanol are mixed in a molar ratio of 1:0.9:0.25:0.20:3.5:7.5 to obtain a sol; 0.05 mol / L dilute hydrochloric acid is added dropwise to the sol to adjust the pH to 2.5, followed by the addition of 5 wt% PEO-b-PPO, and stirring at 120 rpm for 1.5 h at room temperature to obtain a clear sol; the clear sol and ECR glass fiber are placed in an impregnation tank, and the impregnation process is carried out... A nitrogen flow of 0.15 m / s was introduced into the glue bath to keep the ECR glass fiber in a turbulent suspension state for 24 min to obtain impregnated glass fiber. The impregnated glass fiber was then transferred to a horizontal centrifuge and centrifuged at 800 rpm for 34 s to make the wet film thickness on the surface of the impregnated glass fiber 9 µm. It was then placed in a constant temperature water bath at 73℃ for 30 min to obtain wet gel glass fiber. The wet gel glass fiber was dried in supercritical CO2 at 64℃ / 13 MPa for 40 min, and then cured in nitrogen at 270℃ for 33 min to obtain modified glass fiber.

[0030] The above-mentioned method for preparing the light-transmitting enhanced laser-welded PC / PBT composite material includes the following steps:

[0031] S1: Add PC, PBT, transesterification inhibitor, antioxidant, and non-silicone defoamer to a high-speed mixer and mix thoroughly to obtain a premix.

[0032] S2: The premixed material is added to the main feed port of the twin-screw extruder, and the modified glass fiber is added to the side feed port of the twin-screw extruder. After melting, extrusion, granulation and air drying, the composite material is obtained.

[0033] The twin-screw extruder has a screw length-to-diameter ratio of 43:1 and a rotational speed of 360 rpm / min.

[0034] Example 3

[0035] This invention provides a light-transmitting enhanced laser-welded PC / PBT composite material. The composite material comprises, by weight, 27.6 parts PC, 41.4 parts PBT, 30 parts modified glass fiber, 0.8 parts transesterification inhibitor, 0.1 parts antioxidant, and 0.1 parts non-silicone defoamer. The modified glass fiber has a length of 3.6 mm and a diameter of 13 μm. The transesterification inhibitor is SA-PGP-B. The antioxidant is a hindered phenolic antioxidant. The non-silicone defoamer is AFCONA-2720.

[0036] The preparation method of modified glass fiber includes the following steps: Tetraethoxysilane, phenyltriethoxysilane, methyltriethoxysilane, tetrabutyl titanate, water, and ethanol are mixed in a molar ratio of 1:0.9:0.3:0.25:4.0:8.0 to obtain a sol; 0.05 mol / L dilute hydrochloric acid is added dropwise to the sol to adjust the pH to 2.5, followed by the addition of 5 wt% PEO-b-PPO, and stirring at 120 rpm for 1.5 h at room temperature to obtain a clear sol; the clear sol and ECR glass fiber are placed in an impregnation tank, and impregnation is performed... A nitrogen flow of 0.15 m / s was introduced into the tank to keep the ECR glass fiber in a turbulent suspension state for 28 min to obtain impregnated glass fiber. The impregnated glass fiber was then transferred to a horizontal centrifuge and centrifuged at 800 rpm for 36 s to make the wet film thickness on the surface of the impregnated glass fiber 9 µm. It was then placed in a constant temperature water bath at 74 ℃ for 30 min to obtain wet gel glass fiber. The wet gel glass fiber was dried in supercritical CO2 at 68 ℃ / 15 MPa for 45 min, and then cured in nitrogen at 275 ℃ for 32 min to obtain modified glass fiber.

[0037] The above-mentioned method for preparing the light-transmitting enhanced laser-welded PC / PBT composite material includes the following steps:

[0038] S1: Add PC, PBT, transesterification inhibitor, antioxidant, and non-silicone defoamer to a high-speed mixer and mix thoroughly to obtain a premix.

[0039] S2: The premixed material is added to the main feed port of the twin-screw extruder, and the modified glass fiber is added to the side feed port of the twin-screw extruder. After melting, extrusion, granulation and air drying, the composite material is obtained.

[0040] The twin-screw extruder has a screw length-to-diameter ratio of 45:1 and a rotational speed of 350 rpm / min.

[0041] Example 4

[0042] This invention provides a light-transmitting enhanced laser-welded PC / PBT composite material. The composite material comprises the following components by weight: 29.4 parts PC, 39.2 parts PBT, 30 parts modified glass fiber, 0.6 parts transesterification inhibitor, 0.2 parts antioxidant, and 0.2 parts non-silicone defoamer. The modified glass fiber has a length of 4.0 mm and a diameter of 14 μm. The transesterification inhibitor is SA-PGP-B. The antioxidant is a phosphite antioxidant. The non-silicone defoamer is AFCONA-2720.

[0043] The preparation method of modified glass fiber includes the following steps: mixing tetraethoxysilane, phenyltriethoxysilane, methyltriethoxysilane, tetrabutyl titanate, water, and ethanol in a molar ratio of 1:1.1:0.35:0.30:4.5: 8.5 Mix to obtain a sol; add 0.05 mol / L dilute hydrochloric acid dropwise to the sol to adjust the pH to 3, then add 6 wt% PEO-b-PPO of the total sol mass, and stir at 120 rpm for 2 h at room temperature to obtain a clear sol; place the clear sol and ECR glass fiber in an impregnation tank, and introduce a 0.2 m / s nitrogen flow into the impregnation tank to keep the ECR glass fiber in a turbulent suspension state for 30 min to obtain impregnated glass fiber; transfer the impregnated glass fiber to a horizontal centrifuge and centrifuge at 800 rpm for 40 s to make the wet film thickness on the surface of the impregnated glass fiber 10 µm, then place it in a constant temperature water bath at 75℃ for 30 min to obtain wet gel glass fiber; dry the wet gel glass fiber in supercritical CO2 at 70℃ / 16 MPa for 50 min, and then cure it in nitrogen at 280℃ for 35 min to obtain modified glass fiber.

[0044] The above-mentioned method for preparing the light-transmitting enhanced laser-welded PC / PBT composite material includes the following steps:

[0045] S1: Add PC, PBT, transesterification inhibitor, antioxidant, and non-silicone defoamer to a high-speed mixer and mix thoroughly to obtain a premix.

[0046] S2: The premixed material is added to the main feed port of the twin-screw extruder, and the modified glass fiber is added to the side feed port of the twin-screw extruder. After melting, extrusion, granulation and air drying, the composite material is obtained.

[0047] The twin-screw extruder has a screw length-to-diameter ratio of 46:1 and a rotational speed of 400 rpm / min.

[0048] Example 5

[0049] This invention provides a light-transmitting enhanced laser-welded PC / PBT composite material. The composite material comprises the following components by weight: 44 parts PC, 35.2 parts PBT, 20 parts modified glass fiber, 0.6 parts transesterification inhibitor, 0.2 parts antioxidant, and 0.2 parts non-silicone defoamer. The modified glass fiber has a length of 3.2 mm and a diameter of 12 μm. The transesterification inhibitor is sodium dihydrogen phosphate. The antioxidant is a hindered phenolic antioxidant. The non-silicone defoamer is BYK-3155.

[0050] The preparation method of modified glass fiber includes the following steps: Tetraethoxysilane, phenyltriethoxysilane, methyltriethoxysilane, tetrabutyl titanate, water, and ethanol are mixed in a molar ratio of 1:0.9:0.25:0.20:3.5:7.5 to obtain a sol; 0.05 mol / L dilute hydrochloric acid is added dropwise to the sol to adjust the pH to 2.5, followed by the addition of 5 wt% PEO-b-PPO, and stirring at 120 rpm for 1.5 h at room temperature to obtain a clear sol; the clear sol and ECR glass fiber are placed in an impregnation tank, and the impregnation process is carried out... A nitrogen flow of 0.15 m / s was introduced into the glue bath to keep the ECR glass fiber in a turbulent suspension state for 24 min to obtain impregnated glass fiber. The impregnated glass fiber was then transferred to a horizontal centrifuge and centrifuged at 800 rpm for 34 s to make the wet film thickness on the surface of the impregnated glass fiber 9 µm. It was then placed in a constant temperature water bath at 73℃ for 30 min to obtain wet gel glass fiber. The wet gel glass fiber was dried in supercritical CO2 at 64℃ / 13 MPa for 40 min, and then cured in nitrogen at 270℃ for 33 min to obtain modified glass fiber.

[0051] The above-mentioned method for preparing the light-transmitting enhanced laser-welded PC / PBT composite material includes the following steps:

[0052] S1: Add PC, PBT, transesterification inhibitor, antioxidant, and non-silicone defoamer to a high-speed mixer and mix thoroughly to obtain a premix.

[0053] S2: The premixed material is added to the main feed port of the twin-screw extruder, and the modified glass fiber is added to the side feed port of the twin-screw extruder. After melting, extrusion, granulation and air drying, the composite material is obtained.

[0054] The twin-screw extruder has a screw length-to-diameter ratio of 45:1 and a rotational speed of 360 rpm / min.

[0055] Example 6

[0056] This invention provides a light-transmitting enhanced laser-welded PC / PBT composite material. The composite material comprises the following components by weight: 30.8 parts PC, 43 parts PBT, 25 parts modified glass fiber, 0.9 parts transesterification inhibitor, 0.1 parts antioxidant, and 0.2 parts non-silicone defoamer. The modified glass fiber has a length of 3.6 mm and a diameter of 13 μm. The transesterification inhibitor is SA-PGP-B. The antioxidant is a hindered phenolic antioxidant. The non-silicone defoamer is AFCONA-2720.

[0057] The preparation method of modified glass fiber includes the following steps: Tetraethoxysilane, phenyltriethoxysilane, methyltriethoxysilane, tetrabutyl titanate, water, and ethanol are mixed in a molar ratio of 1:0.9:0.3:0.25:4.0:8.0 to obtain a sol; 0.05 mol / L dilute hydrochloric acid is added dropwise to the sol to adjust the pH to 2.5, followed by the addition of 5 wt% PEO-b-PPO, and stirring at 120 rpm for 1.5 h at room temperature to obtain a clear sol; the clear sol and ECR glass fiber are placed in an impregnation tank, and impregnation is performed... A nitrogen flow of 0.15 m / s was introduced into the tank to keep the ECR glass fiber in a turbulent suspension state for 28 min to obtain impregnated glass fiber. The impregnated glass fiber was then transferred to a horizontal centrifuge and centrifuged at 800 rpm for 36 s to make the wet film thickness on the surface of the impregnated glass fiber 9 µm. It was then placed in a constant temperature water bath at 74 ℃ for 30 min to obtain wet gel glass fiber. The wet gel glass fiber was dried in supercritical CO2 at 68 ℃ / 15 MPa for 45 min, and then cured in nitrogen at 275 ℃ for 32 min to obtain modified glass fiber.

[0058] The above-mentioned method for preparing the light-transmitting enhanced laser-welded PC / PBT composite material includes the following steps:

[0059] S1: Add PC, PBT, transesterification inhibitor, antioxidant, and non-silicone defoamer to a high-speed mixer and mix thoroughly to obtain a premix.

[0060] S2: The premixed material is added to the main feed port of the twin-screw extruder, and the modified glass fiber is added to the side feed port of the twin-screw extruder. After melting, extrusion, granulation and air drying, the composite material is obtained.

[0061] The twin-screw extruder has a screw length-to-diameter ratio of 44:1 and a rotational speed of 350 rpm / min.

[0062] In Examples 1-6, PC was an optical-grade polycarbonate resin with a molecular weight of 20,000-30,000 g / mol and a refractive index of 1.591, PBT was an injection-grade polybutylene terephthalate with a molecular weight of 40,000-45,000 g / mol and a refractive index of 1.580, and the modified glass fiber had a refractive index of 1.582-1.585. The melt flow rate of PC was 12.5 ± 2.0 g / 10 min, and the intrinsic viscosity of PBT was 0.83 ± 0.02 dL. The temperatures of each zone of the twin-screw extruder were as follows: Zone 1: 220-230°C; Zone 2: 235-245°C; Zone 3: 235-245°C; Zone 4: 245-250°C; Zone 5: 250-255°C; Zone 6: 240-245°C; and the die head temperature was 235-240°C.

[0063] In the preparation of modified glass fibers, tetraethoxysilane and tetrabutyl titanate undergo co-condensation under acidic conditions to form a transparent sol containing Si-O-Ti bonds. ECR glass fibers are suspended in a turbulent state within the impregnation tank, which promotes the dispersion of ECR ​​glass fiber monofilaments and prevents clumping. In a horizontal centrifugal dryer, excess sol is removed by centrifugal force, controlling the wet film thickness. A constant temperature water bath at 72–75℃, higher than room temperature but lower than the boiling point of ethanol, allows for slow ethanol evaporation, clarifying the sol concentration and accelerating the tetraethoxysilane condensation, promoting the formation of a three-dimensional Si-O-Ti network. PEO-b-PPO undergoes thermal decomposition and volatilization at 260–280℃, leaving mesopores, thus constructing a porous nano-coating on the surface of the ECR glass fibers. Through melt extrusion of the modified glass fibers with PC and PBT, PC / PBT occupies the mesopores, forming a refractive index gradient transition layer with the porous nano-coating. This invention introduces a benzene ring through phenyltriethoxysilane to improve local polarizability and the refractive index of the refractive index gradient transition layer. Furthermore, it introduces methyl steric hindrance through methyltriethoxysilane to suppress excessive crosslinking of the three-dimensional Si-O-Ti network and reduce the brittleness of the refractive index gradient transition layer.

[0064] Examples 1-6 of this invention provide a light-transmitting enhanced laser-welded PC / PBT composite material. The dosage ratios of each component in Examples 1-6 are shown in Table 1.

[0065] Table 1 Dosage and Proportioning

[0066] PC 34.6 41.4 27.6 29.4 44 30.8 PBT 34.6 27.6 41.4 39.2 35.2 43 Modified glass fiber 30 30 30 30 20 25 Ester exchange inhibitor 0.5 0.7 0.8 1.0 0.6 0.9 antioxidants 0.2 0.2 0.1 0.2 0.1 0.1 Non-silicone defoamer 0.1 0.1 0.1 0.2 0.1 0.2 Total number of copies 100 100 100 100 100 100 PC / PBT 1 1.5 0.67 0.75 1.25 0.72

[0067] Comparative Example 1

[0068] It is basically the same as Example 1, except that the composite material does not use modified glass fiber.

[0069] Comparative Example 2

[0070] It is basically the same as Example 1, except that ECR glass fiber is used instead of modified glass fiber.

[0071] Performance testing

[0072] Composite materials were prepared according to the preparation methods of Examples 1-6 and Comparative Examples 1-2, and the refractive index, flexural strength, flexural modulus, and transmittance of the composite materials were tested respectively. The results are shown in Table 2.

[0073] The methods for obtaining product performance parameters in Examples 1-6 and Comparative Examples 1-2 are as follows:

[0074] Refractive index was measured according to ASTM D542-18 method;

[0075] Tensile strength was tested according to GB / T 1040.2-2006.

[0076] The flexural modulus was tested according to the method of GB / T 9341-2008;

[0077] Transmittance was measured using an LPKF TMG3 transmittance meter to test the transmittance of infrared light at 980 nm, with the composite material thickness being 2 mm.

[0078] Table 2 Performance Test Results

[0079]

[0080] As shown in Table 2, regarding refractive index, the refractive indices of Examples 1-6 range from 1.573 to 1.578, which matches well with the refractive index of the PC / PBT matrix. In terms of mechanical properties, Examples 1-6, containing 30% modified glass fiber, exhibit higher flexural strength and flexural modulus; while Examples 5 and 6, with 20% and 25% modified glass fiber respectively, show slightly lower mechanical properties. Comparative Example 1, without added glass fiber, has the worst mechanical properties; Comparative Example 2, although containing ECR glass fiber, did not undergo surface modification, resulting in weaker interfacial bonding, and therefore its mechanical properties are still lower than those of the other examples.

[0081] It is worth noting that the composite material with added modified glass fiber showed a smaller change in refractive index compared to Comparative Example 1 without added glass fiber. This indicates that the porous nanocoating constructed on the surface of ECR ​​glass fiber through the sol-gel process promotes the matrix resin to penetrate into the pores during melt blending, forming a transition layer with a continuously changing refractive index. This smoothly connects the refractive index between the glass fiber and the matrix resin, effectively eliminating optical abrupt changes at the interface.

[0082] Regarding light transmittance, Comparative Example 1, lacking fiber scattering, exhibited the highest transmittance but suffered from severely insufficient mechanical properties. Comparative Example 2, due to the significant difference in refractive index between the unmodified glass fiber and the matrix, experienced severe interfacial scattering, resulting in a sharp decrease in transmittance. In contrast, Examples 1-6 maintained excellent mechanical properties while keeping transmittance between 42% and 52%, approaching the level of Comparative Example 1. Among these, Example 5, with its lower modified glass fiber content and higher PC proportion, achieved the best transmittance, reaching 52%. This demonstrates that the present invention successfully achieved a good balance between light transmittance and mechanical properties through interfacial optical design.

[0083] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A light-transmitting enhanced laser-welded PC / PBT composite material, characterized in that, The composite material comprises the following components by weight: 27.6–44 parts PC, 27.6–43 parts PBT, 20–30 parts modified glass fiber, 0.5–1.0 parts transesterification inhibitor, 0.1–0.2 parts antioxidant, and 0.1–0.2 parts non-silicone defoamer. The mass ratio of PC to PBT is (2:3) to (3:2), the PC is optical grade polycarbonate resin with a molecular weight of 20,000 to 30,000 g / mol and a refractive index of 1.591, the melt flow rate of the PC is 12.5 ± 2.0 g / 10 min, the PBT is injection molding grade polybutylene terephthalate with a molecular weight of 40,000 to 45,000 g / mol and a refractive index of 1.580, the intrinsic viscosity of the PBT is 0.83 ± 0.02 dL, and the refractive index of the modified glass fiber is 1.582 to 1.

585. The preparation method of the modified glass fiber includes the following steps: Tetraethoxysilane, phenyltriethoxysilane, methyltriethoxysilane, tetrabutyl titanate, water, and ethanol are mixed in a molar ratio of 1:(0.9–1.1):(0.25–0.35):(0.20–0.30):(3.5–4.5):(7.5–8.5) to obtain a sol; 0.05 mol / L dilute hydrochloric acid is added dropwise to the sol to adjust the pH to 2–3, followed by the addition of 4–6 wt% PEO-b-PPO, and stirring at 120 rpm for 1–2 h at room temperature to obtain a clear sol; the clear sol and ECR glass fiber are placed in an impregnation tank, and then... A nitrogen flow of 0.1–0.2 m / s is introduced into the impregnation tank to keep the ECR glass fibers in a turbulent suspension state for 20–30 min to obtain impregnated glass fibers. The impregnated glass fibers are then transferred to a horizontal centrifugal dryer and centrifuged at 800 rpm for 30–40 s to make the wet film thickness on the surface of the impregnated glass fibers 8–10 µm. Subsequently, they are placed in a constant temperature water bath at 72–75 °C for 30 min to obtain wet gel glass fibers. The wet gel glass fibers are dried in supercritical CO2 at 60–70 °C / 12–16 MPa for 30–50 min, and then cured in nitrogen at 260–280 °C for 30–35 min to obtain the modified glass fibers.

2. The light-transmitting enhanced laser-welded PC / PBT composite material according to claim 1, characterized in that, The modified glass fiber has a length of 3.0–4.0 mm and a diameter of 12–14 μm.

3. The light-transmitting enhanced laser-welded PC / PBT composite material according to claim 1, characterized in that, The transesterification inhibitor is sodium dihydrogen phosphate or transesterification inhibitor SA-PGP-B.

4. The light-transmitting enhanced laser-welded PC / PBT composite material according to claim 1, characterized in that, The antioxidant is a hindered phenolic antioxidant or a phosphite antioxidant.

5. The light-transmitting enhanced laser-welded PC / PBT composite material according to claim 1, characterized in that, The non-silicone defoamer is BYK-3155 or AFCONA-2720.

6. The method for preparing the light-transmitting enhanced laser-welded PC / PBT composite material according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1: Add PC, PBT, transesterification inhibitor, antioxidant, and non-silicone defoamer to a high-speed mixer and mix thoroughly to obtain a premix. S2: The premixed material is added to the main feed port of the twin-screw extruder, and the modified glass fiber is added to the side feed port of the twin-screw extruder. After melting, extrusion, granulation, and air drying, the composite material is obtained.

7. The method for preparing a light-transmitting enhanced laser-welded PC / PBT composite material according to claim 6, characterized in that, The twin-screw extruder has a screw length-to-diameter ratio of (42-46):1 and a rotational speed of 300-400 rpm.

8. The method for preparing a light-transmitting enhanced laser-welded PC / PBT composite material according to claim 6, characterized in that, The temperatures of each zone of the twin-screw extruder include: Zone 1 temperature 220-230℃, Zone 2 temperature 235-245℃, Zone 3 temperature 235-245℃, Zone 4 temperature 245-250℃, Zone 5 temperature 250-255℃, Zone 6 temperature 240-245℃, and die head temperature 235-240℃.

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