High-temperature-yellowing-resistant brominated flame-retardant polyamide composite material and preparation method thereof

Abstract

The invention discloses a high-temperature-yellowing-resistant brominated flame-retardant polyamide composite material which comprises the following raw material components in parts by mass: 45-52 parts of nylon resin, 28-32 parts of glass fibers, 13-16 parts of a brominated flame retardant, 3-5 parts of a synergistic flame retardant, 0.5-3.0 parts of a high-temperature-aging-resistant additive, 0.4-1.0 part of an antioxidant and 0.2-0.9 part of a lubricant. On the basis of a brominated flame-retardant polyamide material, the variety of antioxidants is optimized, the reaction with common components (antimony compounds) in brominated products is reduced, meanwhile, a small amount of laponite and kieselguhr auxiliaries are added, the yellowing phenomenon of the brominated flame-retardant polyamide material in a high-temperature environment is further reduced, and in the modification process, the anti-yellowing performance of the brominated flame-retardant polyamide material is improved. The overall mechanical property of the material is not reduced, so that the high-temperature-yellowing-resistant brominated flame-retardant polyamide material is obtained.

Description

Technical Field

[0001] The invention relates to the field of polyamide materials, and in particular to a bromine-based flame-retardant polyamide composite material that is resistant to high-temperature yellowing. Background Art

[0002] Polyamide materials are widely used in the automotive, electrical, and power tool industries due to their excellent mechanical and electrical properties. Among them, the working environment of electrical equipment is often accompanied by high temperature and high current, so the material needs to have certain flame retardant properties to meet the use requirements of these parts. Flame-retardant polyamide materials can be divided into nitrogen flame retardant, red phosphorus flame retardant, bromine flame retardant, phosphorus nitrogen flame retardant, etc. according to the type of flame retardant. Compared with other flame retardant materials, bromine flame retardant materials have better mechanical properties and high flame retardant efficiency, but they have shortcomings such as low CTI value and easy decomposition and yellowing of flame retardants at high temperatures.

[0003] Polyamide materials will break their molecular chains under high temperature and hot oxygen conditions, especially the breakage of amide bonds will easily generate chromophores, which will cause the material to change color significantly. In addition, due to the introduction of brominated flame retardants, such as decabromodiphenylethane, brominated flame retardant polyamide materials will partially decompose at high temperatures to produce bromine free radicals, which will further yellow the surface of the material. Generally speaking, brominated flame retardant polyamide materials have weaker high temperature resistance than nitrogen and phosphorus nitrogen flame retardant polyamide materials, and are more likely to turn yellow in a short period of time at high temperatures, resulting in a larger color difference. However, most electrical products of brominated flame retardant nylon are mainly light colors such as white or gray, and the light background color will make the yellowing color difference of brominated flame retardant polyamide materials before and after high temperature more obvious. Therefore, solving the problem of high temperature yellowing resistance of such materials is an industry pain point. At present, most patents to solve such problems are mainly focused on the selection of antioxidant types.

[0004] In order to improve the high temperature yellowing resistance of nylon materials, the application publication number CN 108285640A discloses a high temperature yellowing resistant nylon material and its preparation method. It uses nylon as the base material and improves the high temperature resistance of nylon from two aspects: antioxidants and color powders. On the one hand, organic copper salt H3386 and inorganic phosphate H10 are compounded to inhibit the thermal oxidation aging and yellowing of nylon materials. On the other hand, the yellow light is eliminated and covered by the preferred color powder (such as titanium dioxide and ultramarine), so that the material maintains a high whiteness. At present, there are few studies on the improvement of the high temperature aging resistance of brominated flame retardant polyamide materials using additives other than antioxidants. Summary of the invention

[0005] In view of the shortcomings of the existing technology, the present invention hopes that the polyamide composite material has better high temperature baking resistance while having the original flame retardant performance and high mechanical properties. The present invention adopts polyamide as the base material, glass fiber as the reinforcing component, and adds brominated flame retardants, synergistic flame retardants, antioxidants, lubricants and high temperature aging resistant additives, etc., and prepares a high temperature yellowing resistant brominated flame retardant polyamide material through an extruder To achieve the purpose of the present invention, the technical solution adopted is: A high temperature yellowing resistant brominated flame retardant polyamide material, comprising the following raw material components by weight: Nylon resin 45-52 Glass fiber 28-32 Brominated flame retardant 13-16 Synergistic flame retardant 3-5 High temperature aging resistant additive 0.5-3.0 Antioxidant 0.4-1.0 Lubricant 0.2-0.9.

[0006] The nylon resin includes PA6, PA66 and a blend of PA6 and PA66. Preferably, the PA6 relative viscosity of the nylon resin is 2.4-2.7.

[0007] The glass fiber includes glass fiber with a diameter of 10 μm, preferably Jushi glass fiber 560A.

[0008] The brominated flame retardant is one or more of decabromodiphenylethane, polybrominated styrene, and brominated polystyrene, preferably decabromodiphenylethane.

[0009] The synergistic flame retardant is antimony trioxide, zinc stannate, etc., preferably antimony trioxide.

[0010] The high temperature aging resistant additive is diatomaceous earth and / or lithium diatomaceous earth, preferably lithium diatomaceous earth.

[0011] The antioxidant comprises a mixture of a primary antioxidant and an auxiliary antioxidant, and the types thereof include one or a mixture of phosphites, hindered phenols and thioesters. Preferably, the antioxidant is a mixture of 1098, 168 and 3301.

[0012] The lubricant includes silicone powder, silicone masterbatch, polyethylene wax, ethylene bis stearamide, etc. Polyethylene wax is preferred, specifically Honeywell AC-540.

[0013] The present invention provides a brominated flame-retardant polyamide composite material resistant to high temperature yellowing and a preparation method thereof, and the preparation steps are as follows: After nylon resin, antioxidant, lubricant, synergistic flame retardant and high temperature aging resistant additive are mixed and added into the twin screw extruder from the main feeding hopper, and short glass fiber and brominated flame retardant are respectively fed into the extruder from the second and third side feeding ports, plasticized and sheared by the screw, and the uniform material strips are water-cooled and pelletized to obtain high temperature yellowing resistant brominated flame retardant polyamide composite materials. The specific process parameters are as follows: the extrusion speed is 350 rpm, the barrel temperature from the first zone to the tenth zone is 250℃, 260℃, 250℃, 240℃, 230℃, 210℃, 200℃, 190℃, 180℃, 170℃, and the die head temperature is 220℃.

[0014] A more preferred preparation method is to first dissolve the antioxidant in an organic solvent, add a high temperature aging resistant additive, and stir at high speed for 3 to 5 minutes at a stirring speed of 500 to 1000 r / min. Then premix with other raw materials and additives, add glass fiber and brominated flame retardant from the side feed port, and extrude and granulate. The specific process parameters are as follows: the extrusion speed is 350 rpm, the barrel temperature from the first zone to the tenth zone is 250°C, 260°C, 250°C, 240°C, 230°C, 210°C, 200°C, 190°C, 180°C, 170°C, and the die head temperature is 220°C.

[0015] The innovation of the present invention is as follows: on the basis of the brominated flame-retardant polyamide material, the type of antioxidant is optimized to reduce the reaction with the common components (antimony compounds) in the brominated products, and at the same time, a small amount of additives such as lithium talcum powder, diatomaceous earth, talcum powder, etc. are added to further reduce the yellowing phenomenon of the brominated flame-retardant polyamide material in a high temperature environment, and in this modification process, the overall mechanical properties of the material are not reduced, thereby obtaining a brominated flame-retardant polyamide material resistant to high temperature yellowing. The present invention provides a more preferred preparation method, which can obtain better high temperature yellowing resistance. DETAILED DESCRIPTION

[0016] The technical solution of the present invention will be further described below in conjunction with specific comparative examples 1-2 and embodiments 1-7.

[0017] The raw materials and proportions used in the present invention are shown in Table 1, but are not limited to the raw materials and proportions used in the comparative examples and embodiments. All raw materials used are commercially available industrial products.

[0018] The raw materials in the proportions of Table 1 were premixed and granulated through a twin-screw extruder to obtain a brominated flame-retardant polyamide composite material resistant to high temperature yellowing. The specific process parameters are as follows: the extrusion speed is 350 rpm, the barrel temperatures from the first zone to the tenth zone are 250°C, 260°C, 250°C, 240°C, 230°C, 210°C, 200°C, 190°C, 180°C, 170°C, and the die head temperature is 220°C.

[0019] Performance characterization and test methods: The tensile strength of the composite materials prepared in the above-mentioned comparative examples and embodiments is measured with a universal mechanical testing machine with reference to GB / T 1040.2-2022 standard; the flexural strength is measured with reference to GB / T 9341-2008 standard and a universal mechanical testing machine; the notched impact strength is measured with reference to GB / T 1043.1-2008 standard and a simply supported beam impact testing machine; the vertical burning flame retardancy is measured with reference to GB / T 2408-2021 standard and a vertical-horizontal burning measuring instrument; the high temperature aging condition selects a temperature of 150°C, and the specific color difference value is measured with a colorimeter.

[0020] Comparative Example 1 is a common glass fiber reinforced bromine flame retardant polyamide material on the market, and Comparative Example 2 is a common glass fiber reinforced bromine flame retardant polyamide material added with a common antioxidant on the market. Adding a small amount of antioxidant does not affect the overall mechanical properties of the material, and can reduce the high temperature yellowing phenomenon of the material to a certain extent.

[0021] Example 1 and Example 2 are based on Comparative Example 1, with the introduction of lithium algae mineral. The addition of lithium algae can effectively reduce the yellowing phenomenon of the material at a high temperature of 150°C. The increase in the content of lithium algae can further alleviate the high-temperature yellowing, and the lithium algae at this ratio has little effect on the overall mechanical properties of the material. The main component of lithium algae is lithium magnesium silicate, which can neutralize the acidic substances produced by the decomposition of brominated flame retardants in a hot oxygen environment and reduce the overall yellowing of the material.

[0022] Examples 3 and 4 compare diatomite and lithium terephthalate. Example 4 is based on Example 2, with the addition of a phosphorous acid antioxidant 3301. Antioxidant 3301 is a phosphite auxiliary antioxidant, which can synergize with the main antioxidant 1098 to improve the thermal oxidation aging resistance of the material. Examples 5-6 increase the content of phosphites on the basis of Example 4 to further improve the thermal oxidation aging resistance of the brominated flame retardant polyamide material.

[0023] The preparation method of Example 7 is different from that of other examples. The antioxidant is first dissolved in an organic solvent, and then stirred with lithium algae for 5 minutes at a stirring speed of 1000 r / min. Then it is premixed with other raw materials, and glass fiber and brominated flame retardant are added from the second and third side feed ports respectively, and extruded into granules. The specific process parameters are as follows: the extrusion speed is 350 rpm, the barrel temperatures from the first zone to the tenth zone are 250°C, 260°C, 250°C, 240°C, 230°C, 210°C, 200°C, 190°C, 180°C, 170°C, and the die head temperature is 220°C.

[0024] formula Comparative Example 1 Comparative Example 2 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Meida M12400 51.2 51.0 50.7 50.2 50.0 50.0 49.8 49.6 50.0 Taishan short fiber T435N 30 30 30 30 30 30 30 30 30 Decabromodiphenylethane 14 14 14 14 14 14 14 14 14 Antimony trioxide 4 4 4 4 4 4 4 4 4 Lithium Earth / / 0.5 1 / 1 1 1 1 diatomite / / / / 1 / / / / 3301 / 0.2 / / 0.2 0.2 0.4 0.6 0.2 AC540 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 168 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 1098 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2

[0025] Test items Comparative Example 1 Comparative Example 2 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Tensile strength (MPa) 142 144 143 138 137 137 136 132 138 Bending strength (MPa) 222 225 226 219 217 218 219 220 219 <![CDATA[Notched impact of simply supported beam (KJ / m 2 )]]> 13 13 13 12 12 12 12 12 12 <![CDATA[Izod impact strength of simply supported beam (KJ / m 2 )]]> 62 59 58 59 56 58 57 58 58 Vertical burning (1.6mm) V0 V0 V0 V0 V0 V0 V0 V0 V0 ΔE (150℃ 4h) 6.29 4.32 4.98 4.35 3.23 2.80 2.21 1.84 2.40

[0026] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, it can be improved or changed according to the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A high temperature yellowing resistant brominated flame retardant polyamide composite material, comprising the following raw material components by weight: Nylon resin 45-52 Glass fiber 28-32 Brominated flame retardant 13-16 Synergistic flame retardant 3-5 High temperature aging resistant additive 0.5-3.0 Antioxidant 0.4-1.0 Lubricant 0.2-0.

9.

2. The high temperature yellowing resistant brominated flame retardant polyamide composite material according to claim 1, characterized in that: The nylon resin includes PA6, PA66 and a blend of PA6 and PA66.

3. The high temperature yellowing resistant brominated flame retardant polyamide composite material according to claim 1, characterized in that: The glass fiber includes a glass fiber having a diameter of 10 μm.

4. The high temperature yellowing resistant brominated flame retardant polyamide composite material according to claim 1, characterized in that: The brominated flame retardant is one or more of decabromodiphenylethane, polybrominated styrene and brominated polystyrene.

5. The high temperature yellowing resistant brominated flame retardant polyamide composite material according to claim 1, characterized in that: The synergistic flame retardant is antimony trioxide and zinc stannate.

6. The high temperature yellowing resistant brominated flame retardant polyamide composite material according to claim 1, characterized in that: The high temperature aging resistant additive is diatomaceous earth and / or lithium diatomaceous earth.

7. The high temperature yellowing resistant brominated flame retardant polyamide composite material according to claim 1, characterized in that: The antioxidant comprises a mixture of a primary antioxidant and an auxiliary antioxidant, and the types thereof include one or a mixture of phosphites, hindered phenols and thioesters.

8. The high temperature yellowing resistant brominated flame retardant polyamide composite material according to claim 1, characterized in that: The lubricant includes silicone powder, silicone masterbatch, polyethylene wax, ethylene bis stearamide and the like.

9. The high temperature yellowing resistant brominated flame retardant polyamide composite material and preparation method thereof according to claim 1, the preparation steps are as follows: After nylon resin, antioxidant, lubricant, synergistic flame retardant and high temperature aging resistant additive are mixed and added into the twin screw extruder from the main feeding hopper, and short glass fiber and brominated flame retardant are respectively fed into the extruder from the second and third side feeding ports, plasticized and sheared by the screw, and the uniform material strips are water-cooled and pelletized to obtain high temperature yellowing resistant brominated flame retardant polyamide composite materials. The specific process parameters are as follows: the extrusion speed is 350 rpm, the barrel temperature from the first zone to the tenth zone is 250℃, 260℃, 250℃, 240℃, 230℃, 210℃, 200℃, 190℃, 180℃, 170℃, and the die head temperature is 220℃.