PBT composite material, preparation method and application thereof

Abstract

The present application relates to a kind of PBT composite material and its preparation method and application.The PBT composite material includes the following weight parts of component: PBT resin 40~55 parts, sheet filler 1.9~5.1 parts, flat glass fiber 25~35 parts, epoxy resin 1.9~5.1 parts.The present application is obtained by the cooperation of the flat glass fiber of specific flat ratio, the epoxy resin of specific epoxy equivalent and sheet filler, and the poisson ratio of the PBT composite material is small, the poisson ratio change at high and low temperature is small, and the electric leakage resistance is good.

Description

Technical Field

[0001] This invention relates to the field of polymer material processing technology, and more specifically, to a PBT composite material, its preparation method, and its application. Background Technology

[0002] In the field of engineering plastics, especially crystalline polyester materials such as polybutylene terephthalate (PBT), due to their excellent electrical properties, mechanical strength, processability, and electrical insulation properties, they are widely used as functional components in electrical systems, such as motor housings, relays, connectors, plugs and sockets, and cooling fans. Because these functional components need to provide high load-bearing capacity and vibration characteristics, they require a low Poisson's ratio. On the other hand, when these functional components are being functionally adjusted, the ambient temperature may exceed 100°C. Under high temperatures, the Poisson's ratio of the material will change. If the difference between the Poisson's ratio at room temperature and at high temperature is large, it will affect the accuracy of functional adjustment, potentially impacting the subsequent operation of the functional component. Therefore, it is necessary to ensure that the difference in the Poisson's ratio of the material is small across different temperatures.

[0003] In addition, considering factors such as short circuits and fires, the leakage current resistance of functional components of electrical devices also needs to be evaluated, and the leakage current resistance of current polybutylene terephthalate materials needs to be further improved. Summary of the Invention

[0004] The primary objective of this invention is to overcome the problems of high Poisson's ratio, large differences in Poisson's ratio at different temperatures, and the need for further improvement in leakage resistance of existing materials, and to provide a PBT composite material.

[0005] A further objective of this invention is to provide a method for preparing the above-mentioned PBT composite material.

[0006] A further object of the present invention is to provide the application of the above-mentioned PBT composite material in the preparation of functional components of electrical components.

[0007] The above-mentioned objective of the present invention is achieved through the following technical solution:

[0008] A PBT composite material comprises the following components in parts by weight:

[0009]

[0010] The flat glass fiber has a flatness ratio ≥ 3.5:1; the epoxy resin has an epoxy equivalent of 2500~3500g / eq.

[0011] The inventors of this invention discovered through research that a PBT composite material obtained by combining flat glass fibers with a specific aspect ratio, epoxy resin with a specific epoxy equivalent, and sheet fillers exhibits a low Poisson's ratio, minimal variation in Poisson's ratio at high and low temperatures, and excellent resistance to leakage current. This is because: glass fibers themselves provide reinforcement, and a certain flatness allows the reinforcement effect of the glass fibers to be amplified in different directions, reducing longitudinal and transverse strain during material stretching; the epoxy resin, through its epoxy functional groups, binds the PBT resin and flat glass fibers more tightly, further contributing to the reduction of strain variation; the addition of sheet fillers disrupts the arrangement of the flat glass fibers, also positively impacting the reduction of Poisson's ratio; simultaneously, reducing Poisson's ratio by decreasing longitudinal and transverse strain also narrows the difference in Poisson's ratio between high and low temperatures. Furthermore, epoxy resin with an appropriate epoxy equivalent allows the flat glass fibers to flow better with the PBT resin during processing, while the sheet fillers reduce the exposure of the flat glass fibers on the surface of the PBT composite material. These two effects result in a smoother surface and an improved CTI value for the PBT composite material.

[0012] If conventional glass fibers (circular cross-section) are used, their reinforcement in different directions varies under stress, resulting in a high Poisson's ratio and a large difference in Poisson's ratio at high and low temperatures. Furthermore, they are more easily exposed on the material surface, leading to poor leakage current resistance. If the epoxy equivalent of the epoxy resin is too high and the epoxy content is too low, the PBT resin and flat glass fibers cannot bond well. If the epoxy equivalent of the epoxy resin is too low, it will cause excessive cross-linking of the PBT resin, reducing its fluidity and resulting in poor bonding between the glass fibers and the PBT resin. Both of these factors lead to poor performance of the PBT composite material. While other shapes of fillers can reduce the exposure of flat glass fibers in the material and help improve the CTI value, they are significantly less effective than sheet fillers in reducing the Poisson's ratio and the difference in Poisson's ratio at high and low temperatures.

[0013] In this invention, PBT resin is used as the main resin, and its content is preferably more than 40 wt% of the PBT composite material.

[0014] In this invention, flat glass fiber refers to glass fiber with an elliptical cross-section, and the aspect ratio refers to the ratio of the longest diameter to the shortest diameter of the ellipse. The aspect ratio of flat glass fiber can be measured by optical microscopy, specifically by using an optical microscope with 1000x magnification and a graduated scale to read the longest and shortest diameters of the cross-sections of 50 flat glass fibers, and then calculating and averaging the results.

[0015] In this invention, the flatness ratio of the flat glass fiber can be specifically 3.5:1, 3.6:1, 3.7:1, 3.8:1, 3.9:1, 4.0:1, 4.1:1 or 4.2:1.

[0016] Preferably, the flat glass fiber is alkali-free glass fiber.

[0017] Preferably, the flat glass fiber has a flatness ratio of 3.5 to 4.2:1.

[0018] Increasing the aspect ratio further affects the Poisson's ratio, the variation of Poisson's ratio at high and low temperatures, and the current leakage current (CTI) of the PBT composite material. Controlling the aspect ratio within the range of 3.5–4.2:1 results in a PBT composite material with a smaller Poisson's ratio, less variation in Poisson's ratio at high and low temperatures, and better leakage current resistance.

[0019] Preferably, the average minimum diameter of the cross-section of the flat glass fiber is 6 to 10 μm, and more preferably 7 to 9 μm.

[0020] In this invention, the epoxy equivalent of the epoxy resin can specifically be 2500, 2700, 2800, 2900, 3000, 3100, 3200, 3300, or 3500 g / eq. The epoxy equivalent of the epoxy resin of this invention can be measured according to the method of GB / T4612-2008.

[0021] Preferably, the intrinsic viscosity of the PBT resin is 0.8 to 1.5 dl / g (specifically, it can be 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4 or 1.5 dl / g).

[0022] More preferably, the intrinsic viscosity of the PBT resin is 0.82 to 1.25 dl / g.

[0023] More preferably, the intrinsic viscosity of the PBT resin is 0.82 to 1.10 dl / g.

[0024] When the intrinsic viscosity of PBT resin is controlled within this range, the PBT composite material has a lower Poisson's ratio and a higher CTI value.

[0025] In this invention, the intrinsic viscosity of PBT resin is tested according to Method A (capillary viscometer method) in GB / T14190-2017.

[0026] Preferably, the sheet-like filler is at least one of mica powder, talc powder, or wollastonite.

[0027] Preferably, the sheet-like filler has an average particle size of 2μm to 20μm.

[0028] More preferably, the sheet-like filler has an average particle size of 10 μm to 18 μm.

[0029] With the average particle size of the sheet filler controlled within this range, the properties of the PBT composite material are better.

[0030] In this invention, the average particle size of the sheet-like filler can be measured by a particle size analyzer.

[0031] Preferably, the mass ratio of the flat glass fiber to the sheet filler is 5 to 18:1.

[0032] More preferably, the mass ratio of the flat glass fiber to the sheet filler is 10 to 15:1.

[0033] By adjusting the mass ratio of flat glass fibers to sheet fillers within this range, the PBT composite material exhibits better properties.

[0034] Preferably, the epoxy resin is at least one of bisphenol A type epoxy resin or bisphenol F type epoxy resin.

[0035] Preferably, the PBT composite material further includes 8-15 parts of flame retardant and 2-4 parts of flame retardant synergist.

[0036] More preferably, the flame retardant is a brominated flame retardant, which includes, but is not limited to, at least one of brominated epoxy, brominated polystyrene, brominated polycarbonate, decabromodiphenyl ethane, or pentabromobenzyl polyacrylate.

[0037] More preferably, the flame retardant synergist is an antimony-containing compound; the antimony-containing compound includes, but is not limited to, antimony white.

[0038] Preferably, the PBT composite material further includes 0.3 to 2 parts of other additives.

[0039] Preferably, the other additives are at least one of lubricants or antioxidants.

[0040] Optionally, the lubricant is at least one of aliphatic carboxylic acid esters, erucamide, ethylene bis-stearamide, montan esters, polyethylene wax, or oxidized polyethylene wax.

[0041] Optionally, the antioxidant is at least one of hindered phenolic antioxidants, phosphite antioxidants, or organosulfur antioxidants.

[0042] The preparation method of the above-mentioned PBT composite material includes the following steps: mixing the components, melt extruding, and granulating to obtain the PBT composite material.

[0043] Preferably, the temperature of the melt extrusion is 200-250°C; the screw speed of the extruder for the melt extrusion is 300-550 rpm, and the length-to-diameter ratio of the screw is 30-50:1.

[0044] The application of the above-mentioned PBT composite material in the preparation of functional components of electrical components is also within the scope of protection of this invention.

[0045] Preferably, the functional components of the electrical element are relay housings, cooling fan frames and blades, or connector housings.

[0046] Compared with the prior art, the beneficial effects of the present invention are:

[0047] The present invention obtains a PBT composite material with a small Poisson's ratio, small variation in Poisson's ratio at high and low temperatures, and good resistance to leakage current by combining flat glass fibers with a specific aspect ratio, epoxy resin with a specific epoxy equivalent, and sheet filler. Detailed Implementation

[0048] To more clearly and completely describe the technical solution of the present invention, the present invention will be further described in detail below through specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention. Various changes can be made within the scope of the claims of the present invention.

[0049] The reagents used in the various embodiments and comparative examples of this invention are described below:

[0050] PBT resin #1: Lanshan Tunhe, TH6100, intrinsic viscosity is 1.0 dl / g;

[0051] PBT resin #2: Lanshan Tunhe, TH6082, intrinsic viscosity is 0.82 dl / g;

[0052] PBT resin #3: Yizheng Chemical Fiber, GL236, intrinsic viscosity is 1.25 dl / g;

[0053] Flame retardant: Brominated polystyrene, SR-3010, Shandong Xurui;

[0054] Flame retardant synergist: Antimony white, S-05N, Chenzhou Antimony Industry;

[0055] Flat fiberglass 1#: TFG-3.0-T436, flatness ratio 3.5:1, Taishan Fiberglass;

[0056] Flat fiberglass 2#: ECS4F-03-534A, flatness ratio 4.0:1, Jushi Group;

[0057] Flat fiberglass 3#: ECS3F-03-534A, flatness ratio 3.0:1, Jushi Group;

[0058] Ordinary glass fiber 1#: ECS13-4.5-534A, with a circular cross-section and an average diameter of 13μm, manufactured by Jushi Group;

[0059] Epoxy resin #1: YD-019, Guodu Chemical, epoxy equivalent is 2800g / eq;

[0060] Epoxy resin #2: YD-019K, Guodu Chemical, epoxy equivalent is 3100g / eq;

[0061] Epoxy resin #3: YD-017H, epoxy equivalent is 2200g / eq;

[0062] Epoxy resin #4: YD-020, Guodu Chemical, epoxy equivalent is 4000g / eq;

[0063] Flaky filler #1: Talc, HY-TA05, Shenzhen Haiyang Powder, particle size D50 is 4.0μm;

[0064] Flaky filler #2: Talc, HY-TA10, Shenzhen Haiyang Powder, particle size D50 is 11.2μm;

[0065] Flaky filler #3: Mica, GM-6, Anhui Gree New Material Technology Co., Ltd., particle size D50 is 17.0μm;

[0066] Other filler #1: Granular, calcium carbonate, Omyacarb 5T-JI, particle size D50 is 4.9μm.

[0067] Other additives #1: This is obtained by mixing antioxidant 1010, antioxidant 168, and pentaerythritol stearate (lubricant) in a mass ratio of 1:1:1. Antioxidant 1010, antioxidant 168, and pentaerythritol stearate are all commercially available products.

[0068] Unless otherwise specified, all components (e.g., flame retardants, other additives 1#, etc.) used in each parallel embodiment and comparative example are the same commercially available products.

[0069] The performance of the PBT composite materials provided in the embodiments and comparative examples of this invention was determined according to the following test methods:

[0070] (1) Poisson's ratio: Using a sample prepared according to ISO 527-2019 standard, the longitudinal and transverse strain data of the width plane of the sample were collected by a high-speed vision DIC system. The test temperatures were 23℃ and 150℃, respectively. The test sample was conditioned for at least 4 hours at the corresponding test temperature. The clamp spacing was 115mm, the extensometer gauge length was 50mm, and the test speed was 1mm / min.

[0071] (2) Tracking Index (CTI) is tested according to IEC 60112-2020 standard. A solution with a conductivity of 395±5Ω·cm is prepared using ammonium chloride and distilled or deionized water. The maximum voltage value that does not ignite or the current does not exceed 0.5A after 50 drops of liquid are tested using a CTI tester. A 100×100×3.0mm square plate is used for the test.

[0072] The preparation process of the PBT composite materials in the embodiments and comparative examples of the present invention is as follows: First, the PBT resin is dried at 130°C for 3 hours; then, each component is weighed according to the formula, mixed, and then melt-extruded in a twin-screw extruder and granulated to obtain the PBT composite material. The temperatures of the twin-screw extruder are as follows: Zone 1: 210°C; Zone 2: 210°C; Zone 3: 220°C; Zone 4: 220°C; Zone 5: 230°C; Zone 6: 230°C; Zone 7: 240°C; Zone 8: 250°C; Zone 9: 240°C; Die head temperature: 240°C; Main extruder speed: 500 rpm; Screw length-to-diameter ratio: 40:1.

[0073] Examples 1-11

[0074] Examples 1-11 provide a series of PBT composite materials, the formulations of which are shown in Table 1.

[0075] Table 1. Formulations (parts by weight) for Examples 1-11

[0076]

[0077] Comparative Examples 1-7

[0078] Comparative Examples 1–7 provide a series of PBT composite materials, the formulations of which are shown in Table 2.

[0079] Table 2 shows the formulations (parts by weight) for Comparative Examples 1–7.

[0080]

[0081]

[0082] The properties of the PBT composite materials in each embodiment and comparative example were determined according to the test methods mentioned above, and the test results are shown in Table 3.

[0083] Table 3. Performance test results of PBT composite materials in each embodiment and comparative example.

[0084]

[0085]

[0086] As can be seen from Table 3:

[0087] The Poisson's ratios of the PBT composite materials in Examples 1-11 are all less than or equal to 0.298 at 23°C, the difference between the Poisson's ratios at 23°C and 150°C is less than or equal to 0.018, and the CTI values ​​are all greater than or equal to 250. This indicates that the PBT composite materials of the present invention have small Poisson's ratios, small changes in Poisson's ratios at high and low temperatures, and good leakage resistance, making them very suitable for manufacturing functional components of electrical components that require load-bearing capacity and vibration characteristics.

[0088] Comparative Example 1 used flat glass fibers with a low aspect ratio. Comparative Example 2 used conventional glass fibers, resulting in a PBT composite material with a high Poisson's ratio and large variations in Poisson's ratio at high and low temperatures. Furthermore, Comparative Example 2 exhibited poor leakage current resistance. Comparative Example 3 did not add flat glass fibers but instead used an equal amount of sheet filler, resulting in a PBT composite material with a high Poisson's ratio and large variations in Poisson's ratio at high and low temperatures. In Comparative Examples 4 and 5, the epoxy equivalent of the epoxy resin was unsuitable, leading to poor performance of the PBT composite materials. Comparative Example 6 did not add sheet filler but instead used an equal amount of flat glass fibers, resulting in poor performance of the PBT composite material. Comparative Example 7 used non-sheet fillers instead of sheet fillers, resulting in a PBT composite material with a high Poisson's ratio and large variations in Poisson's ratio at high and low temperatures.

[0089] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A PBT composite material, characterized by, Comprise the following components by weight: PBT resin 40~55 parts, Flaky filler 1.9~5.1 parts, Flat glass fiber 25~35 parts, Epoxy resin 1.9~5.1 parts; The flat ratio of the flat glass fiber is ≥3.5:1; the epoxy equivalent weight of the epoxy resin is 2500~3500g / eq.

2. The PBT composite material according to claim 1, characterized in that, The flat ratio of the flat glass fiber is 3.5~4.2:

1.

3. The PBT composite of claim 1, wherein, The intrinsic viscosity of the PBT resin is 0.8~1.5dl / g.

4. The PBT composite of claim 1, wherein, The flaky filler is at least one of mica powder, talc powder or wollastonite.

5. The PBT composite of claim 1, wherein, The average particle size of the flaky filler is 2μm~20μm.

6. The PBT composite of claim 1, wherein, The mass ratio of the flat glass fiber and the flaky filler is 5~18:

1.

7. The PBT composite of claim 1, wherein, The PBT composite material further comprises flame retardant 8~15 parts, flame retardant synergist 2~4 parts.

8. The PBT composite of claim 1, wherein, The PBT composite material further comprises other auxiliary agent 0.3~2 parts.

9. The method for preparing the PBT composite material according to any one of claims 1-8, characterized in that, Comprise the following steps: mixing, melt extruding, granulating the components, and the PBT composite material is obtained.

10. Use of the PBT composite according to any one of claims 1 to 8 for the production of functional parts of electrical components, characterized in that The electrical component functional part is a relay shell, a heat dissipation fan frame and fan blade or a connector shell.

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