High IPT halogen-free flame-retardant reinforced PBT composite material and preparation method and application thereof

Abstract

The present invention discloses a high IPT halogen-free flame retardant reinforced PBT composite material and its preparation method and application. The composite material comprises the following components by mass percentage: 46.2-66.3% PBT resin, 5-8% halogen-free flame retardant, 5-8% silicon-based flame retardant toughening agent, 20-40% glass fiber, 0.3-0.5% antioxidant, and 0.3-0.5% lubricant. The composite material provided by the present invention has excellent resistance to inclined surface leakage tracking, can pass the IPT test up to 2KV, and has good impact performance (the simply supported beam unnotched impact can reach 55KJ / m 2 ) and flame retardant properties (flame retardant grade reaches 0.8mm V‑0 level), and can be used to prepare high-voltage energy storage connectors and / or photovoltaic connectors in new energy materials.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer material modification, and specifically relates to a high IPT halogen-free flame-retardant reinforced PBT composite material and a preparation method and application thereof. Background Art

[0002] Polybutylene terephthalate (PBT) resin has excellent performance, electrical properties, chemical resistance and excellent UV resistance. After modification, polybutylene terephthalate (PBT) composite materials have excellent flame retardant properties and excellent electrical properties. They are often used as insulating structural parts in the electronic and electrical fields, and are also widely used in automobile manufacturing, new energy materials and other fields. Inclined plate tracking (IPT) simulates the corrosion resistance and insulation performance of materials under high-voltage energy storage effect (>1.5KV) when they are exposed to pollutants and hot and humid environments under harsh outdoor conditions. The test method is to tilt the sample 45°, install electrodes at the top and bottom of the sample along the downward inclined surface, and the test voltage is 1KV~35KV. The failure standard of ASTM D2303-2013 is that the sample forms a hole and burns, the tracking length reaches 25mm or the tracking time is less than 60min; IPT test is mainly used in outdoor high-voltage environment. With the development of new energy materials, high-voltage energy storage connectors and photovoltaic connectors are increasingly used. High-voltage energy storage connectors and photovoltaic connectors need to withstand the test of hot and humid environments, and have high requirements for flame retardancy and IPT: For example, the UL4128 standard for photovoltaic connectors stipulates that for polymers that are in direct or close contact (less than 0.8mm) with live parts, when the voltage is greater than 600V and the creepage distance is less than 16mm, the IPT of the material needs to reach more than 1.5KV.

[0003] Halogen-free flame retardant reinforced PBT has excellent electrical properties and excellent weather resistance. Commonly used halogen-free flame retardants include: melamine polyphosphate, phosphinate, phenoxyphosphazene, phosphorus nitrogen composite flame retardant, etc. Halogen-free flame retardant reinforced PBT has the disadvantages of low impact performance, easy precipitation, metal corrosion, etc. when ensuring the flame retardant grade reaches UL94 V-0 grade, and the IPT is low (generally lower than 1.5KV). Due to these shortcomings, halogen-free flame retardant reinforced PBT composite materials are rarely used in the field of high-voltage energy storage connectors and photovoltaic connectors.

[0004] Chinese patent application number 200910057461.1 discloses a halogen-free flame-retardant reinforced polybutylene terephthalate composition and a preparation method thereof, wherein a phosphorus-nitrogen flame retardant and a synergistic flame retardant are compounded, and phenoxyphosphazene is used as a synergistic flame retardant, which can give the material good flame retardancy and mechanical properties. Since the phosphorus-nitrogen flame retardant is easily precipitated and degraded during the heating process, it is easy to form hole combustion under the high voltage of the IPT test. After testing, this system cannot reach the UL4128 standard requirement of more than 1.5KV.

[0005] Chinese patent application number 202011573229.6 discloses an antimony-free bromine-based flame-retardant PBT composition, a preparation method and application thereof, and introduces a preparation method and application of flame-retardant reinforced PBT using a compound of bromine, nitrogen and organosiloxane flame retardants. The method used is to use nitrogen and organosiloxane to replace antimony in the bromine-based flame retardant system to improve the flame retardancy. Since this system contains bromine, it cannot meet the halogen-free requirements. Secondly, bromine-based flame retardants easily promote carbonization in IPV tests. After testing, this system cannot meet the requirement of more than 1.5KV in the UL4128 standard.

[0006] Chinese patent application with application number 202010465508.4 discloses a halogen-free flame retardant reinforced PBT modified material and its preparation method, and introduces a preparation method of silicone-coated aluminum hypophosphite and MCA compound flame retardant reinforced PBT. The method adopted is to use silicone-coated aluminum hypophosphite and MCA compound, but it still cannot solve the problem that phosphorus-nitrogen flame retardants and MCA are easily precipitated during the heating process. After testing, this system cannot reach the requirement of UL4128 standard of more than 1.5KV.

[0007] The Chinese patent application with application number 202210596232.2 discloses short glass fiber reinforced flame retardant high CTI high glow wire environmentally friendly PBT, and introduces a preparation method of short glass fiber reinforced flame retardant high CTI high glow wire environmentally friendly PBT. It adopts a compound of phosphorus nitrogen flame retardant and a small amount of silicon flame retardant, but it still cannot solve the defect that phosphorus nitrogen flame retardant is easy to precipitate during the heating process. Although a protective layer is formed by silicon, it still cannot reach the requirement of UL4128 standard of more than 1.5KV after testing.

[0008] At present, there is almost no halogen-free flame retardant reinforced PBT with high IPT, and related research is still in its infancy; therefore, the development of halogen-free flame retardant reinforced PBT composite materials with high IPT values ​​(≥1.5KV) has great market significance and economic value, and the preparation of halogen-free flame retardant reinforced composite materials with high IPT is of great significance in the application and development of new energy materials. Summary of the invention

[0009] The primary purpose of the present invention is to overcome the shortcomings and deficiencies of the existing halogen-free flame-retardant reinforced PBT composite material technology and provide a high IPT halogen-free flame-retardant reinforced PBT composite material. The composite material has both high impact resistance and good flame retardant properties.

[0010] Another object of the present invention is to provide a method for preparing the above-mentioned high IPT halogen-free flame retardant reinforced PBT composite material.

[0011] Another object of the present invention is to provide an application of the high IPT halogen-free flame retardant reinforced PBT composite material.

[0012] To achieve the above object, the present invention adopts the following technical solution:

[0013] A high IPT halogen-free flame-retardant reinforced PBT composite material comprises the following components by mass percentage: 46.2-66.3% of PBT resin, 5-8% of halogen-free flame retardant, 5-8% of silicon-based flame retardant toughening agent, 20-40% of glass fiber, 0.3-0.5% of antioxidant, and 0.3-0.5% of lubricant; preferably comprises the following components by mass percentage: 46.2-66.3% of PBT resin, 5-8% of halogen-free flame retardant, 5-8% of silicon-based flame retardant toughening agent, 20-40% of glass fiber, 0.3-0.4% of antioxidant, and 0.3-0.5% of lubricant; more preferably comprises the following components by mass percentage: 55.2-57.2% of PBT resin, 6-7% of halogen-free flame retardant, 5-8% of silicon-based flame retardant toughening agent, 30% of glass fiber, 0.4% of antioxidant, and 0.4% of lubricant.

[0014] The PBT resin is a polybutylene terephthalate resin with a viscosity of 0.83-1.05 dl / g, preferably XW321 produced by Sinopec Yizheng.

[0015] The halogen-free flame retardant is a phenyl structure organic silicon solid resin with a softening point of 90°C to 120°C, preferably KR-480 produced by Shin-Etsu Chemical.

[0016] The silicon-based flame retardant toughening agent is a flame retardant toughening agent for silicone rubber with a core-shell structure and a core Tg of -100°C to -120°C, preferably MR-01 produced by Kaneka Chemical.

[0017] The glass fiber is E glass fiber; preferably E glass fiber with a short cut length of 3 to 5 cm and a single fiber thickness of 8 to 10 μm, and more preferably ECS303-3-H from Chongqing International Composite Materials.

[0018] The antioxidant is at least one of a hindered phenol antioxidant and a phosphite antioxidant, preferably a mixture of the two, and more preferably BASF's B225.

[0019] The lubricant is polyester grafted modified polydimethylsiloxane, preferably Tegomer H-Si6441P of Evonik Specialty Chemicals.

[0020] The high IPT is capable of passing a 2000V voltage test.

[0021] The above-mentioned high IPT halogen-free flame retardant reinforced PBT composite material is prepared by melt blending in a commonly used twin-screw extruder; the specific preparation method preferably includes the following steps: adding ingredients other than halogen-free flame retardant and glass fiber (such as PBT resin, silicon-based flame retardant toughening agent, antioxidant, lubricant and other components) from the main feeding port of the twin-screw extruder, adding halogen-free flame retardant and glass fiber from two side feeding ports respectively, and after melt blending and extrusion through the twin-screw extruder, cooling, air drying, and pelletizing, a high IPT halogen-free flame retardant reinforced PBT composite material is obtained.

[0022] The twin-screw extruder is a twin-screw extruder with a length-to-diameter ratio of 40.

[0023] The extrusion conditions are preferably as follows: the extrusion temperature is 230-250° C., and the screw speed is 250-400 rpm.

[0024] The above-mentioned high IPT halogen-free flame retardant reinforced PBT composite material has high IPT, good impact resistance and flame retardant properties, and is suitable for preparing high-voltage energy storage connectors and / or photovoltaic connectors in new energy materials.

[0025] Compared with the prior art, this application has the following beneficial effects:

[0026] (1) The IPT (inclined surface tracking resistance) test of the halogen-free flame retardant reinforced PBT composite material provided by the present invention reaches 2KV.

[0027] (2) The present invention uses a compound of an organic silicon flame retardant and a core-shell structured silicone rubber flame retardant toughening agent to obtain a halogen-free flame retardant reinforced PBT composite material having good impact properties (the simply supported beam unnotched impact can reach 55KJ / m 2 ) and flame retardant properties (flame retardant grade reaches 0.8mm V-0 level).

[0028] (3) The specific polyester grafted modified polydimethylsiloxane used in the present invention helps to improve the compatibility of glass fiber and the hydrophobicity of the material surface. The combination of the two can effectively improve the electrical tracking length performance of the material of the present invention in the IPT test. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

[0030] Preparation of high IPT halogen-free flame retardant reinforced PBT composite material: weigh the raw materials of S1 to C10 according to the material ratios in Tables 1 and 2 below, add the ingredients other than halogen-free flame retardant and glass fiber (such as PBT resin, silicon-based flame retardant toughening agent, antioxidant, lubricant and other components) from the main feeding port of the twin-screw extruder, add halogen-free flame retardant and glass fiber from two side feeding ports, melt blend and extrude through the twin-screw extruder, cool, air-dry and pelletize to obtain a high IPT halogen-free flame retardant reinforced PBT composite material. Twin-screw extruder extrusion temperature: 230-250°C (before the glass fiber addition port), 210-220°C (between the glass fiber addition port and the vacuum port), 240-250°C (after the vacuum port).

[0031] Table 1: Technical solutions and performance results of the embodiments

[0032]

[0033] Note: Pass means pass.

[0034] Table 2: Comparative technical solutions and performance results

[0035]

[0036]

[0037] Note: Pass means pass; NG means fail.

[0038] In the above examples, the following properties of the prepared samples were tested according to the following methods, and the results and comparisons are shown in Tables 1 and 2:

[0039] The composite materials prepared in Examples S1 to S6 and Comparative Examples C1 to C10 were tested. First, test specimens were prepared under the same injection molding conditions (baking temperature 120°C, baking time 4 hours; injection molding machine nozzle, front section, middle section and rear section temperatures of 260°C, 250°C, 250°C, 240°C, injection molding machine screw speed 60rpm, mold temperature 90°C, injection pressure 75Mpa, injection time 3 seconds, holding pressure 50Mpa, holding time 8 seconds, cooling time 10 seconds, back pressure 10Mpa), and the specific physical property test items are as follows:

[0040] IPT (Inclined Plane Tracking) Test: The inclined plane tracking test was performed according to ASTM D2303-2013, using a constant voltage method, with a test voltage of 2 KV for the embodiment and 1.5 KV for the comparative example.

[0041] Tensile strength: tested according to ISO 527 standard, with a tensile speed of 10mm / min.

[0042] Simple supported beam unnotched impact strength: tested in accordance with ISO 179 standard, notch type is A.

[0043] Flame retardant test conditions: Tested in accordance with UL94 standard, thickness 0.8±0.15mm.

[0044] It can be seen from Examples S1 to S6 that the high IPT halogen-free flame retardant reinforced composite material has excellent anti-slope tracking performance, flame retardant performance and impact performance through the method of the present invention. The IPT test can pass 2KV, the flame retardant grade can reach 0.8mmV-0, and the simply supported beam unnotched impact strength is greater than 55KJ / m 2 .

[0045] It can be seen from comparative examples C1-C2 that KR-480 and MR-01 are added separately, and the flame retardant is unqualified and the IPT test fails, which fully demonstrates that the two have a good synergistic effect and can simultaneously improve the flame retardant and IPT performance of the system. The inventor speculates that this may be because a large amount of heat will be released during the arc discharge process of the IPT test to act on the surface of the material, and during the heating process of the phenyl silicone resin, the phenyl siloxane will quickly migrate and interact with the core-shell silicone rubber to form a silicon-based heat-insulating and oxygen-insulating protective layer on the surface of the polymer, which not only inhibits the thermal decomposition of the composite material but also prevents rapid carbonization, thereby achieving the purpose of simultaneously improving the IPT and flame retardant properties.

[0046] It can be seen from comparative examples C3-C5 that KR-480 and MR-01 are not within the addition range of the present invention, and still have good IPT performance, but if it is below the range, the flame retardancy is unqualified, and if it is above this range, the impact strength is low: the inventor speculates that the reason for the low performance is that the silicone rubber content is too high and it is difficult to disperse in the twin-screw, resulting in low mechanical properties of the system; flame retardancy and impact performance are of great significance to the safety of new energy connector products and must meet relevant application requirements.

[0047] Compared with Example S5, although the system IPT of Comparative Example C6 without adding Tegomer H-Si 6441P can pass, the tracking length is close to the critical value. The IPT tracking length of the system with adding Tegomer H-Si 6441P is greatly shortened, indicating that Tegomer H-Si 6441P can effectively improve the tracking length performance of the material of the present invention in the IPT test.

[0048] It can be seen from comparative examples C7-C10 that the flame retardant systems used in other inventions contain either halogen / phosphorus or nitrogen / phosphorus, which are prone to rapid precipitation and degradation or rapid carbonization during high heat, thereby reducing the electrical insulation performance of the system, especially in the IPT test, and none of them can pass the 1.5KV test; in addition, the impact performance of these systems also does not meet the requirements, and only C7 can achieve the flame retardant performance, which proves that this type of system is not suitable for use as high-voltage energy storage connectors and photovoltaic connector materials.

[0049] In summary, the high IPT halogen-free flame retardant reinforced PBT composite material provided by the present invention can pass the IPT test up to 2KV and has excellent flame retardant and impact properties, and can be used to prepare high-voltage energy storage connectors and photovoltaic connectors in new energy materials.

[0050] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A high IPT halogen-free flame retardant reinforced PBT composite material, characterized in that The invention comprises the following components in percentage by mass: 46.2-66.3% of PBT resin, 5-8% of halogen-free flame retardant, 5-8% of silicon-based flame retardant toughening agent, 20-40% of glass fiber, 0.3-0.5% of antioxidant, and 0.3-0.5% of lubricant; The halogen-free flame retardant is a phenyl structure organic silicon solid resin with a softening point of 90°C to 120°C; The silicone-based flame retardant toughening agent is a flame retardant toughening agent for silicone rubber with a core-shell structure and a core Tg of -100°C to -120°C; The lubricant is polyester grafted modified polydimethylsiloxane.

2. The high IPT halogen-free flame retardant reinforced PBT composite material according to claim 1, characterized in that The invention comprises the following components in percentage by mass: 55.2-57.2% of PBT resin, 6-7% of halogen-free flame retardant, 5-8% of silicon-based flame retardant toughening agent, 30% of glass fiber, 0.4% of antioxidant and 0.4% of lubricant.

3. The high IPT halogen-free flame retardant reinforced PBT composite material according to claim 1 or 2, characterized in that: The PBT resin is a polybutylene terephthalate resin with a viscosity of 0.83 to 1.05 dl / g; The glass fiber is E glass fiber.

4. The high IPT halogen-free flame retardant reinforced PBT composite material according to claim 3, characterized in that: The glass fiber is an E glass fiber with a short cut length of 3 to 5 cm and a single fiber thickness of 8 to 10 μm.

5. The high IPT halogen-free flame retardant reinforced PBT composite material according to claim 1 or 2, characterized in that: The antioxidant is at least one of a hindered phenol antioxidant and a phosphite antioxidant.

6. The method for preparing the high IPT halogen-free flame retardant reinforced PBT composite material according to any one of claims 1 to 5, characterized in that The method comprises the following steps: adding components except halogen-free flame retardant and glass fiber from the main feeding port of a twin-screw extruder, respectively adding halogen-free flame retardant and glass fiber from two side feeding ports, and after melt blending and extrusion through the twin-screw extruder, cooling, air drying and pelletizing are performed to obtain a high IPT halogen-free flame retardant reinforced PBT composite material.

7. The method for preparing the high IPT halogen-free flame retardant reinforced PBT composite material according to claim 6, characterized in that: The twin-screw extruder is a twin-screw extruder with a length-to-diameter ratio of 40.

8. The method for preparing the high IPT halogen-free flame retardant reinforced PBT composite material according to claim 6, characterized in that: The extrusion conditions are as follows: the extrusion temperature is 230-250° C., and the screw speed is 250-400 rpm.

9. Use of the high IPT halogen-free flame retardant reinforced PBT composite material according to any one of claims 1 to 5 in the preparation of high-voltage energy storage connectors and / or photovoltaic connectors in new energy materials.

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