Light-transmitting laser-weldable glass fiber reinforced PBT (Polybutylene Terephthalate) material and preparation method thereof

Abstract

The invention relates to the technical field of engineering plastics, in particular to a light-transmitting laser-weldable glass fiber reinforced PBT (Polybutylene Terephthalate) material and a preparation method thereof. The glass fiber reinforced PBT material is prepared from the following raw materials in parts by weight: 120 to 140 parts of PBT resin, 20 to 40 parts of PC resin, 30 to 50 parts of glass fiber, 0.01 to 0.02 part of graphene oxide grafted hyperbranched polyamide, 0.2 to 2 parts of silane coupling agent, 0.2 to 2 parts of flowable agent, 0.2 to 2 parts of lubricant, 0.2 to 1 part of antioxidant, 0.5 to 1.5 parts of ester exchange inhibitor and 0.4 to 2 parts of dispersant. The method has the advantage of improving the strength of the laser-weldable PBT material.

Description

Technical Field

[0001] The present application relates to the technical field of engineering plastics, and particularly to a glass fiber reinforced PBT material that is light-transmitting and laser-weldable and a preparation method thereof. Background Art

[0002] Plastic laser welding technology is a new type of plastic connection technology. By means of a laser beam penetrating through one layer of plastic and being absorbed by the dual-layer plastic, the heat generated by the laser melts the plastic contact surface, and then thermoplastic sheets, films or molded parts are bonded together, and after further cooling and shaping, a connection is formed. Therefore, for plastic laser welding, the upper layer material of the parts to be welded needs to have a certain transmittance to the laser to ensure sufficient laser energy at the interface of the upper and lower layer materials.

[0003] PBT (polybutylene terephthalate) is a polyester formed by the polycondensation of terephthalic acid and 1,4-butanediol. There is no side chain in the molecule and the structure is symmetrical, making it a highly crystalline material. Moreover, PBT has homogeneous nucleation, a fast nucleation rate and a high crystallinity, that is, there are a large number of crystals in PBT, which causes serious refraction and scattering when a laser irradiates an unmodified PBT sample or template, resulting in a low energy transmitted by the laser and not meeting the requirements of laser welding.

[0004] Currently, the laser transmission performance of PBT materials is mainly improved by regulating the crystallization performance of PBT. On the one hand, by adding a nucleating agent, the spherulite particles of PBT are reduced, so as to achieve a high transmittance of the material to a specific wavelength laser; on the other hand, by introducing a transparent resin to form an alloy, such as polycarbonate (PC), polyethylene terephthalate (PET), etc., the PBT is alloyed and blended and modified, and the proportion of non-transparent phase PBT in the blend is reduced to improve the transmittance. However, it is found in the actual application process that common nucleating agents often produce free alkali metal ions, triggering the decomposition reaction of PBT; while introducing a transparent resin will cause an ester exchange reaction between PBT and the alloy components, both of which will deteriorate the mechanical properties of PBT materials. That is, when the existing PBT materials improve the laser transmission performance, their mechanical properties often decline. Summary of the Invention

[0005] In order to improve the strength of the laser-weldable PBT material, the present application provides a glass fiber reinforced PBT material that is light-transmitting and laser-weldable and a preparation method thereof.

[0006] In the first aspect, the present application provides a glass fiber reinforced PBT material that is light-transmitting and laser-weldable, and adopts the following technical solution: A light-transmitting and laser-weldable glass fiber-reinforced PBT material, which comprises the following raw materials in parts by weight: 120-140 parts of PBT resin, 20-40 parts of PC resin, 30-50 parts of glass fiber, 0.01-0.02 part of graphene oxide grafted hyperbranched polyamide, 0.2-2 parts of silane coupling agent, 0.2-2 parts of flow agent, 0.2-2 parts of lubricant, 0.2-1 part of antioxidant, 0.5-1.5 part of transesterification inhibitor and 0.4-2 parts of dispersant.

[0007] By adopting the above technical solution, in this application, graphene oxide grafted hyperbranched polyamide is added to the glass fiber-reinforced PBT material. By utilizing the excellent mechanical properties of graphene oxide, the strength of the glass fiber-reinforced PBT material is improved; the graphene oxide is modified by hyperbranched polyamide to conduct organic modification, so that its compatibility with the system is improved, and the interfacial tension between it and the system is greatly reduced; on this basis, it is found that graphene oxide grafted hyperbranched polyamide can act as a nucleating agent, which can greatly reduce the spherulite particles of PBT and reduce its crystallinity, thereby improving its laser transmittance.

[0008] Preferably: The graphene oxide grafted hyperbranched polyamide is prepared by an amide reaction of graphene oxide and terminal amino hyperbranched polyamide.

[0009] By adopting the above technical solution, most of the carboxyl groups in the molecular structure of graphene oxide are at the edges. Using its carboxyl groups for amide reaction can reduce the reaction steric hindrance and make the reaction proceed better. The molecular branches of terminal amino hyperbranched polyamide are more and it contains more amino groups, which can improve the grafting rate, so as to prepare a target product with a higher grafting rate.

[0010] Preferably: The molecular weight of the terminal amino hyperbranched polyamide is 800-1000.

[0011] By adopting the above technical solution, the compatibility between graphene oxide grafted hyperbranched polyamide and the system is related to the molecular weight of the terminal amino hyperbranched polyamide. When its molecular weight is small, its compatibility is reduced, resulting in poor overall performance of the material; when its molecular weight is large, the steric hindrance during the reaction with graphene oxide is large, reducing its grafting amount, thus affecting the compatibility with the system; when its molecular weight is 800-1000, it is a better choice.

[0012] Preferably: The addition amount of the graphene oxide grafted hyperbranched polyamide is 0.015 part by weight.

[0013] By adopting the above technical solution, graphene oxide itself has an absorption effect on laser. Therefore, it is necessary to control and adjust its addition amount to make the comprehensive performance of the mechanical properties and laser transmittance of the glass fiber-reinforced PBT material reach the optimum.

[0014] Preferably, the addition amount of the PC resin is 30 parts by weight.

[0015] By adopting the above technical solution, when the addition amount of PC is low, the crystallization inhibition of the PBT resin is low; but when its addition amount is high, the overall strength of the material will be reduced; in this system, its preferred addition amount is 30 parts by weight.

[0016] Preferably, the PBT resin is a mixture of PBT resin-1 and PBT resin-2 with a mass ratio of 4:9, the viscosity of the PBT resin-1 is 0.8 dL / g, and the viscosity of the PBT resin-2 is 1.0 dL / g.

[0017] By adopting the above technical solution, when two PBT resins with different viscosities are added together, their laser transmittance is better.

[0018] Preferably, the glass fiber reinforced PBT material further comprises 0.4-2 parts by weight of welding powder.

[0019] By adopting the above technical solution, the welding powder can improve the welding performance of the glass fiber reinforced PBT material. The focus of this application is to discuss the effect of graphene oxide grafted hyperbranched polyamide on this system, and the effect of the welding powder is common knowledge, so it will not be discussed in the embodiments of this application, but this is also within the protection scope of this application.

[0020] Secondly, this application provides a preparation method of a light-transmitting and laser-weldable glass fiber reinforced PBT material, adopting the following technical solution: A preparation method of a light-transmitting and laser-weldable glass fiber reinforced PBT material, which comprises the following steps: Stir and mix each raw material, then transfer it to an extruder for melt blending, and extrude and pelletize to obtain a glass fiber reinforced PBT material; wherein, the temperature of melt extrusion is 240-260 °C.

[0021] By adopting the above technical solution, this application modifies graphene oxide to improve the dispersibility of graphene oxide. Without additional special processes, it can also be evenly dispersed in the system; the qualified rate of the products prepared by the preparation method of this application can reach 98% or more, and the uniformity of the products is good.

[0022] In summary, this application includes at least one of the following beneficial technical effects: 1. The present application improves the strength of glass fiber reinforced PBT material by adding graphene oxide grafted hyperbranched polyamide to the glass fiber reinforced PBT material and utilizing the excellent mechanical properties of graphene oxide; the graphene oxide is modified by hyperbranched polyamide to be organically modified, thereby improving the compatibility with the system and greatly reducing the interfacial tension between the graphene oxide and the system; on this basis, it is found that the graphene oxide grafted hyperbranched polyamide can act as a nucleating agent, which can greatly reduce the spherulite particles of PBT and reduce its crystallinity, thereby improving its laser transmittance.

[0023] 2. The notched impact strength of the glass fiber reinforced PBT material prepared in this application is 23.8-32.1 kJ / M 2 The flexural strength is between 270-298MPa, the flexural modulus is between 10686-11203MPa, the tensile strength is between 227-259MPa, and the laser transmittance is 52.2% and above, and the highest can reach 63.2%. This shows that the glass fiber reinforced PBT material prepared in this application has excellent laser transmittance, as well as excellent strength and toughness. DETAILED DESCRIPTION

[0024] The present application is further described in detail below in conjunction with the specific contents.

[0025] raw material The raw materials used in the examples of the present application are all commercially available, wherein the graphene oxide has a thickness of about 1 nm, a number of layers of 1-2, an average flake diameter of 30 μm, a specific surface area of ​​200 m2 / g, and a purity>95wt%; the glass fiber is chopped glass fiber with a diameter of 10 μm and a length of 4.5 mm; the PC resin is extrusion grade, purchased from Suzhou Yican Plastics Co., Ltd.; the silane coupling agent is KH550; the antioxidant is antioxidant 168; the model of the flow agent is MP-20; the dispersant is polyethylene wax, and the grade is industrial grade; the lubricant is PETS, produced by Guangzhou Shanshan New Material Technology Co., Ltd.; and the ester exchange inhibitor is triphenyl phosphate. Example

[0026] Example 1 A light-transmitting laser-weldable glass fiber reinforced PBT material, the preparation method of which is as follows: S1. Preparation of graphene oxide grafted hyperbranched polyamide 0.2 g of graphene oxide was added to 100 mL of DMF. After ultrasonic dispersion, 0.045 g of EDC, 0.033 g of HOBt, and 0.035 g of triethylamine were added. After stirring and reacting for 30 min, 0.08 g of amino-terminated hyperbranched polyamide was added, and then the mixture was stirred and reacted for 2 h. After centrifugation, the precipitate was filtered, washed with DMF and ethanol respectively, and dried to obtain graphene oxide grafted hyperbranched polyamide; the model of the amino-terminated hyperbranched polyamide was HyPer N101, and the molecular weight was 350 - 370; S2. 130 kg of PBT resin, 30 kg of PC resin, 40 kg of glass fiber, 0.01 kg of graphene oxide grafted hyperbranched polyamide, 1 kg of silane coupling agent, 1 kg of flow agent, 1 kg of lubricant, 0.8 kg of antioxidant, 1 kg of transesterification inhibitor, and 1 kg of dispersant were added to a high-speed stirring pot for mixing. The stirring speed was 600 r / min, and then it was transferred to a twin-screw extruder for melt blending and pelletizing to obtain a glass fiber reinforced PBT material; among them, the temperature of melt extrusion was 250 °C, and the screw speed was 700 r / min; the PBT resin was a mixture of PBT resin-1 and PBT resin-2 with a mass ratio of 4:9. The viscosity of PBT resin-1 was 0.8 dL / g, and the viscosity of PBT resin-2 was 1.0 dL / g.

[0027] Example 2 A light-transmitting and laser-weldable glass fiber reinforced PBT material, which is different from Example 1 in that the model of the amino-terminated hyperbranched polyamide in S1 is HyPer N102, the molecular weight is 800 - 1000, and the addition amount is 0.2 g. The remaining steps are the same as those in Example 1.

[0028] Example 3 A light-transmitting and laser-weldable glass fiber reinforced PBT material, which is different from Example 1 in that the model of the amino-terminated hyperbranched polyamide in S1 is HyPer N103, the molecular weight is 1900 - 2200, and the addition amount is 0.46 g. The remaining steps are the same as those in Example 1.

[0029] Example 4 A light-transmitting and laser-weldable glass fiber reinforced PBT material, which is different from Example 2 in that the addition amount of graphene oxide grafted hyperbranched polyamide in S2 is 0.015 kg. The remaining steps are the same as those in Example 2.

[0030] Example 5 A light-transmitting and laser-weldable glass fiber reinforced PBT material, which is different from Example 2 in that the addition amount of graphene oxide grafted hyperbranched polyamide in S2 is 0.02 kg. The remaining steps are the same as those in Example 2.

[0031] Example 6 A light-transmitting and laser-weldable glass fiber-reinforced PBT material, which is different from Example 4 in that the addition amount of PC resin in S2 is 20 kg, the addition amount of PBT resin is 140 kg, and the remaining steps are the same as those in Example 4.

[0032] Example 7 A light-transmitting and laser-weldable glass fiber-reinforced PBT material, which is different from Example 4 in that the addition amount of PC resin in S2 is 40 kg, the addition amount of PBT resin is 120 kg, and the remaining steps are the same as those in Example 4.

[0033] Example 8 A light-transmitting and laser-weldable glass fiber-reinforced PBT material, which is different from Example 4 in that the PBT resin in S2 is PBT resin-1, and the remaining steps are the same as those in Example 4.

[0034] Example 9 A light-transmitting and laser-weldable glass fiber-reinforced PBT material, which is different from Example 4 in that the PBT resin in S2 is PBT resin-2, and the remaining steps are the same as those in Example 4.

[0035] Comparative Example Comparative Example 1 A light-transmitting and laser-weldable glass fiber-reinforced PBT material, which is different from Example 4 in that graphene oxide grafted hyperbranched polyamide is not added in S2, and the remaining steps are the same as those in Example 4.

[0036] Comparative Example 2 A light-transmitting and laser-weldable glass fiber-reinforced PBT material, which is different from Example 4 in that the graphene oxide grafted hyperbranched polyamide added in S2 is replaced with graphene oxide of equal mass, and the remaining steps are the same as those in Example 4.

[0037] Comparative Example 3 A light-transmitting and laser-weldable glass fiber-reinforced PBT material, which is different from Example 4 in that the terminal carboxyl hyperbranched polyamide added in S1 is replaced with terminal carboxyl poly(lactic-co-glycolic acid) of equal mass. The average molecular weight of terminal carboxyl poly(lactic-co-glycolic acid) is 1000, which is customized by Jinan Daigang Biotechnology Co., Ltd., and the remaining steps are the same as those in Example 4.

[0038] Performance Detection Test Detection Method / Test Method Prepare glass fiber-reinforced PBT materials according to the preparation methods of Examples 1-9 and Comparative Examples 1-3 respectively, and then conduct detections according to the following detection methods. The detection results are shown in Table 1.

[0039] Notched impact strength: Tested according to the test method in GB / T 1843-2008; Flexural strength: Tested according to the test method in GB / T 9341-2008; Flexural modulus: Tested according to the test method in GB / T 9341-2008; Tensile strength: Tested according to the test method in GB / T 1040.1-2006; Laser transmittance: The infrared transmittance at 980 nm was tested using a Guangzhou Yuke T-1000 transmittance tester. The color plate made of glass fiber reinforced PBT material had a thickness of 2 mm; Time resistance to ethylene glycol: By immersing the glass fiber reinforced PBT materials of Examples 1-9 in an ethylene glycol solution, there were no cracks after 72 h and 240 h; Density: Tested according to the test method in GB / T 1033.1-2008. The densities of the glass fiber reinforced PBT materials of Examples 1-9 were all between 1.43 - 1.49 g / cm 3 between.

[0040] Table 1 Test results of Examples 1-9 and Comparative Examples 1-3 It can be seen from Examples 1-9, Comparative Examples 1-3, and the test data in Table 1 that the notched impact strengths of the glass fiber reinforced PBT materials prepared in this application are all between 23.8 - 32.1 kJ / M 2 between, the flexural strengths are all between 270 - 298 MPa, the flexural moduli can all reach between 10686 - 11203 MPa, the tensile strengths can all reach between 227 - 259 MPa, and at the same time their laser transmittances are all 52.2% and above, with the highest reaching 63.2%; indicating that the glass fiber reinforced PBT materials prepared in this application have excellent laser transmittance, and their strength and toughness are both excellent.

[0041] In this application, graphene oxide grafted hyperbranched polyamide is added to the glass fiber reinforced PBT material. By utilizing the excellent mechanical properties of graphene oxide, the strength of the glass fiber reinforced PBT material is improved; graphene oxide is modified through hyperbranched polyamide to conduct organic modification, thereby improving its compatibility with the system and greatly reducing the interfacial tension between it and the system; on this basis, it is found that graphene oxide grafted hyperbranched polyamide can act as a nucleating agent, which can greatly reduce the spherulite particles of PBT and reduce its crystallinity, thereby improving its laser transmittance. This can be verified by the detection data of Example 1 and Comparative Examples 1-2. The compatibility between graphene oxide grafted hyperbranched polyamide and the system is related to the molecular weight of the terminal amino hyperbranched polyamide. When its molecular weight is small, its compatibility decreases, resulting in poor overall performance of the material; when its molecular weight is large, there is a large steric hindrance during its reaction with graphene oxide, reducing its grafting amount, thereby affecting its compatibility with the system; through Examples 1-3, when its molecular weight is 800-1000, it is a better choice.

[0042] However, graphene oxide itself has an absorption effect on laser. Therefore, it is necessary to control and adjust its addition amount to optimize the comprehensive performance of the mechanical properties and laser transmittance of the glass fiber reinforced PBT material. This can be verified by combining the detection data of Example 2 and Examples 4-5.

[0043] From the detection data of Example 4 and Examples 6-7, it can be seen that when the addition amount of PC is low, the crystallization inhibition of the PBT resin is low; when its addition amount is high, it will reduce the overall strength of the material; in this system, its better addition amount is 30 kg.

[0044] From the detection data of Example 4 and Examples 8-9, it can be seen that when two PBT resins with different viscosities are added together in this application, the laser transmittance is better.

[0045] From the detection data of Example 4 and Comparative Example 3, it can be seen that ignoring the differences in the polymer reaction monomers, when the linear polymer modifies graphene oxide, the modified graphene oxide has worse compatibility with the system than that modified by the hyperbranched polymer; it is speculated that because the viscosity of the hyperbranched polymer itself is small, its terminal amino groups can form hydrogen bonds with the oxygen atoms and hydrogen atoms in the system, enabling the polymer chains in the system to cover more graphene oxide, thereby reducing the surface tension with the system and being able to play its role as a nucleating agent; while the modification by the linear polymer molecules cannot achieve this effect.

[0046] This specific embodiment is only an interpretation of the present invention and does not limit the present invention. After reading this specification, those skilled in the art can make modifications to this embodiment that do not contribute creatively as needed, but as long as it is within the scope of the claims of the present invention, it is protected by the patent law.

Claims

1. A light-transmitting and laser-weldable glass fiber-reinforced PBT material, characterized in that: It comprises the following raw materials in parts by weight: 120-140 parts of PBT resin, 20-40 parts of PC resin, 30-50 parts of glass fiber, 0.01-0.02 parts of graphene oxide grafted hyperbranched polyamide, 0.2-2 parts of silane coupling agent, 0.2-2 parts of flow agent, 0.2-2 parts of lubricant, 0.2-1 part of antioxidant, 0.5-1.5 parts of transesterification inhibitor and 0.4-2 parts of dispersant.

2. The glass fiber reinforced PBT material which is light-transmissive and laser-weldable according to claim 1, wherein: The graphene oxide grafted hyperbranched polyamide is prepared by an amide reaction of graphene oxide and amino-terminated hyperbranched polyamide.

3. The glass fiber reinforced PBT material which is light-transmissive and laser-weldable according to claim 2, characterized in that: The molecular weight of the amino-terminated hyperbranched polyamide is 800-1000.

4. The glass fiber reinforced PBT material capable of being laser welded and having light transmittance according to claim 1, wherein: The addition amount of the graphene oxide grafted hyperbranched polyamide is 0.015 parts by weight.

5. A light-transmitting and laser-weldable glass fiber-reinforced PBT material according to claim 1, characterized in that: The addition amount of the PC resin is 30 parts by weight.

6. The glass fiber reinforced PBT material that is light-transmissive and laser-weldable according to claim 1, wherein: The PBT resin is a mixture of PBT resin-1 and PBT resin-2 with a mass ratio of 4:

9. The viscosity of the PBT resin-1 is 0.8 dL / g, and the viscosity of the PBT resin-2 is 1.0 dL / g.

7. A light-transmitting and laser-weldable glass fiber-reinforced PBT material according to claim 1, characterized in that: The glass fiber reinforced PBT material further comprises 0.4-2 parts by weight of welding powder.

8. A method for preparing the light-transmitting and laser-weldable glass fiber-reinforced PBT material according to any one of claims 1-7, characterized in that: It comprises the following steps: Stir and mix the raw materials, then transfer them to an extruder for melt blending and extrusion granulation to obtain the glass fiber reinforced PBT material; wherein, the temperature of melt extrusion is 240-260 °C.

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