Flame retardant glass fibers and methods of making and using the same

Abstract

This invention discloses a flame-retardant glass fiber, its preparation method, and its application. The flame-retardant glass fiber comprises glass fiber and piperazine diphosphate, with the piperazine diphosphate coating the surface of the glass fiber. The mass ratio of piperazine diphosphate to glass fiber is (0.2~0.7):100. The flame-retardant glass fiber provided by this invention, with its adjusted mass ratio of piperazine diphosphate to glass fiber, is applied to flame-retardant polypropylene composites. During combustion, a carbon layer easily forms on the surface of the glass fiber, thereby hindering the transport of polypropylene resin to the combustion front, effectively mitigating the afterglow effect and improving flame-retardant performance.

Description

Technical Field

[0001] This invention belongs to the field of thermoplastic modification technology, and more specifically, relates to a flame-retardant glass fiber, its preparation method and application. Background Technology

[0002] Polypropylene, as a general-purpose plastic with excellent comprehensive performance, possesses good processing fluidity, mechanical strength, and chemical stability, and is widely used in core fields such as the automotive industry (interior and exterior trim parts, engine peripheral components), home appliances (casings, structural components), and electronics and electrical systems (connectors, insulating components). In recent years, with the increasing demand for lightweight, high-strength, and flame-retardant safety materials in high-end fields such as new energy vehicles, smart home appliances, and rail transportation, glass fiber reinforced polypropylene, due to its high strength and good impact resistance, has become a key choice to replace metal materials, and is particularly suitable for use in safety-sensitive components such as power battery pack casings and vehicle electronic control system components.

[0003] However, glass fiber reinforced polypropylene faces several technical bottlenecks in practical applications: First, the "wick effect" is difficult to eliminate, as the fiber skeleton guides the flow of molten polymer and accelerates oxygen supply during combustion, leading to a sharp drop in flame retardant performance; second, it is difficult to balance flame retardancy and mechanical properties. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing glass fiber reinforced polypropylene composite materials, which cannot simultaneously possess good flame retardant properties and impact strength, and to provide a flame retardant glass fiber.

[0005] Another object of the present invention is to provide a method for preparing the flame-retardant glass fiber.

[0006] Another object of the present invention is to provide the application of the flame-retardant glass fiber.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A flame-retardant glass fiber, comprising glass fiber and piperazine diphosphate, wherein the piperazine diphosphate is coated on the surface of the glass fiber, and the mass ratio of piperazine diphosphate to glass fiber is (0.2~0.7):100.

[0008] This invention provides a flame-retardant glass fiber. The applicant has discovered that flame-retardant glass fiber comprising glass fiber and piperazine diphosphate is applied to polypropylene materials, and the resulting polypropylene materials have good flame-retardant properties. During combustion, a carbon layer is easily formed on the surface of the glass fiber, thereby hindering the transport of polypropylene resin to the combustion front, thus effectively mitigating the afterglow effect and improving the flame-retardant performance.

[0009] It should be noted that the mass ratio of piperazine diphosphate to glass fiber in this invention is (0.2~0.7):100, for example, but not limited to, 0.2:100, 0.22:100, 0.25:100, 0.28:100, 0.3:100, 0.32:100, 0.35:100, 0.38:100, 0.4:100, 0.42:100, 0.45: 100, 0.48:100, 0.5:100, 0.52:100, 0.55:100, 0.58:100, 0.6:100, 0.62:100, 0.65:100, 0.68:100, or 0.7:100, etc., and the specific point values ​​between the above point values, are not exhaustively listed in this invention due to space limitations and for the sake of brevity.

[0010] Furthermore, the mass ratio of piperazine diphosphate to glass fiber is (0.2~0.65):100.

[0011] Furthermore, the mass ratio of piperazine diphosphate to glass fiber is (0.3~0.5):100.

[0012] Furthermore, the chopped length of the flame-retardant glass fiber is 3-5 mm; the average diameter is 10-13 μm.

[0013] Specifically, the chopped length of the flame-retardant glass fiber is determined by the method specified in GB / T 38978-2020 "Determination of the Length of Chopped Glass Fiber".

[0014] Specifically, the average diameter of the flame-retardant glass fiber is determined by the method in GB / T 7690.1 "Test methods for glass fiber yarns - Part 1: Determination of linear density".

[0015] Furthermore, the content of piperazine diphosphate in the flame-retardant glass fiber can be characterized by energy dispersive spectroscopy (EDS) to characterize phosphorus content.

[0016] Furthermore, the flame-retardant glass fiber is prepared by the following method: It is obtained by impregnating glass fibers in a treatment solution containing silane coupling agent and piperazine diphosphate, followed by drying.

[0017] Specifically, the content of piperazine diphosphate in the treatment solution is 0.3~0.75wt%.

[0018] Specifically, the content of silane coupling agent in the treatment solution is 0.5~2wt%.

[0019] Specifically, the solvent of the treatment solution is water and / or alcohol.

[0020] Specifically, the mass ratio of piperazine diphosphate to glass fiber is adjusted by adjusting the content of piperazine diphosphate in the treatment solution.

[0021] Specifically, the silane coupling agent includes one or more of aminosilane coupling agents, epoxysilane coupling agents, or vinylsilane coupling agents.

[0022] Furthermore, the silane coupling agent is an epoxy silane coupling agent.

[0023] Furthermore, the solvent in the treatment solution includes water and / or alcohol.

[0024] Furthermore, the drying temperature is 110~120℃.

[0025] The present invention also provides a polypropylene composite material comprising the following components in parts by weight: 25-55 parts of polypropylene resin; 20-30 parts of brominated flame retardant; 3-10 parts of antimony trioxide; 2-4 parts compatibilizer; 12-35 parts of the above flame-retardant glass fiber.

[0026] It should be noted that, in the polypropylene composite material of the present invention, the content of polypropylene resin is preferably not less than 30 wt%.

[0027] It should be noted that the flame-retardant glass fiber mentioned in this invention is 12 to 35 parts, for example, but not limited to 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, 30 parts, 31 parts, 32 parts, 33 parts, 34 parts, or 35 parts, etc., and the specific point values ​​between the above point values ​​are not exhaustively listed in this invention due to space limitations and for the sake of brevity.

[0028] Furthermore, the brominated flame retardant includes one or more of the following: decabromodiphenyl ethane, decabromodiphenyl ether, brominated styrene, tris(tribromoneopentyl) phosphate, tetrabromobisphenol A-bis(2,3-dibromopropyl) ether, tris(2,3-dibromopropyl)isocyanate, bromobisphenol S-bis(2,3-dibromopropyl) ether, 1,2-bis(tetrabromophthalimide) ethane or melamine hydrobromide and 1,2-bis(pentabromophenyl) ethane.

[0029] Furthermore, the brominated flame retardant includes 1,2-bis(tetrabromophthalimide) ethane and / or decabromodiphenyl ethane.

[0030] Furthermore, the compatibilizer comprises maleic anhydride-grafted polyolefin and / or glycidyl acrylate-grafted polyolefin.

[0031] Furthermore, the maleic anhydride-grafted polyolefin includes maleic anhydride-grafted polypropylene and / or maleic anhydride-grafted ethylene-octene copolymer; the glycidyl acrylate-grafted polyolefin is glycidyl acrylate-grafted polypropylene.

[0032] Furthermore, the grafting rate of maleic anhydride in the compatibilizer is 0.3~1wt%.

[0033] Furthermore, the polypropylene resin includes one or more of homopolymer polypropylene, propylene-ethylene block copolymer, propylene-ethylene random copolymer, and propylene-1-butene random block copolymer.

[0034] Furthermore, the melt flow rate of the polypropylene resin at 230°C and a load of 2.16 kg is 8~30 g / 10 min.

[0035] Specifically, the melt flow rate of the polypropylene resin was determined with reference to ISO 1133-2011.

[0036] Furthermore, the polypropylene resin includes one or more of homopolymer polypropylene, propylene-ethylene block copolymer, propylene-ethylene random copolymer, and propylene / 1-butene random block copolymer.

[0037] Furthermore, the polypropylene composite material also includes 1 to 4 parts of flame retardant synergist.

[0038] Specifically, the particle size D of the flame retardant synergist 50 It is 5~8μm.

[0039] Specifically, the flame retardant synergist includes one or more of ammonium borate, zinc borate, low-melting-point glass powder, or zinc oxide. By adding the flame retardant synergist in conjunction with flame-retardant glass fibers, the afterglow time and maximum smoke density of the composite material can be further reduced.

[0040] Furthermore, the polypropylene composite material also includes 2-4 parts of a phosphorus-based flame retardant; the phosphorus-based flame retardant includes one or more of inorganic aluminum hypophosphite, inorganic calcium hypophosphite, inorganic sodium hypophosphite, aluminum diethylphosphite, or aluminum diisobutylphosphite. By compounding the phosphorus-based flame retardant and flame retardant synergist with the brominated flame retardant, the flame retardant properties of the resulting polypropylene composite material can be made more stable, and the afterglow time and maximum smoke density can be further reduced.

[0041] It should be noted that, without affecting the flame retardancy and impact strength of the polypropylene composite material described in this invention, it also includes 0.1 to 2 parts of processing aids.

[0042] Specifically, the processing aids include, but are not limited to, antioxidants.

[0043] In this invention, the antioxidant can be a commonly used antioxidant, such as, but not limited to, one or more of hindered phenolic antioxidants, phosphite antioxidants, or thioester antioxidants.

[0044] The hindered phenolic antioxidants include pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (Irganox 1010), tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate (antioxidant 3114), vinylbis(oxyvinyl)bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate] (Irganox 245), 3,9-bis{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)acrylic acid]-1,1-dimethyl}-2,4,8,10-tetraoxaspirocycloundecane (ADK AO-80), and N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyphenylpropionamide) (Irganox). One or more of the following: 1098), 1,6-hexanediol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (Irganox 259), or β-(4-hydroxy-3,5-di-tert-butylphenyl)propionate n-octadecyl ester (Irganox 1076).

[0045] The phosphite antioxidant is one or more of tris(2,4-di-tert-butylphenyl) phosphite (Irganox 168), bis(2,6-di-tert-butyl-4-tolyl) pentaerythritol phosphite (PEP-36), or 627A.

[0046] The thioester antioxidant is one or more of distearate thiodipropionate, dilaurate thiodipropionate, or pentaerythritol-based dodecathiopropyl ester.

[0047] The present invention also provides a method for preparing the above-mentioned polypropylene composite material, comprising the following steps: S1. Mix all components except flame-retardant glass fiber evenly to obtain a premix; S2. The premixed material described in step S1 is fed into the extruder through the main feed port, and the flame-retardant glass fiber is fed into the extruder through the side feed port. The mixture is then melt-blended, extruded, and granulated to obtain the final product.

[0048] Furthermore, the extruder described in step S2 is a twin-screw extruder.

[0049] Furthermore, in step S2, the temperature of the twin-screw extruder in zones one to five is 150~160℃, the temperature of zones six to ten is 180~190℃, the temperature of zones eleven to twelve is 210~230℃, and the die temperature is 210~230℃.

[0050] Furthermore, the rotational speed of the twin-screw extruder in step S2 is 350~600 rpm.

[0051] This invention also protects the application of the above-mentioned polypropylene composite material in the preparation of materials for the electronics, electrical appliances, and automotive industries, and is particularly suitable for materials requiring high flame retardancy and mechanical properties.

[0052] A controller housing is made of the aforementioned polypropylene composite material, such as a battery module housing, upper and lower covers, module brackets, high-voltage connector housing, etc.

[0053] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a flame-retardant glass fiber comprising a specific mass ratio of piperazine diphosphate and glass fiber. When applied to polypropylene materials, it can produce polypropylene composite materials that possess good flame-retardant properties, low smoke density, and good impact strength. Detailed Implementation

[0054] The present invention will be further described in detail below with reference to specific embodiments. These embodiments are only used to explain the present invention and are not intended to limit the scope of the present invention. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods; the materials and reagents used are commercially available unless otherwise specified.

[0055] 1. Raw materials used in each embodiment and comparative example: Polypropylene resin: Polypropylene resin 1: Copolymer polypropylene, PP EP300M, with a melt flow rate of 8 g / 10 min at 230℃ and 2.16 kg load, purchased from CNOOC Shell Petrochemicals Co., Ltd. Polypropylene resin 2: Copolymer polypropylene, PP EP548R, with a melt flow rate of 28 g / 10 min at 230℃ and 2.16 kg load, purchased from CNOOC Shell Petrochemicals Co., Ltd. Brominated flame retardants: Brominated flame retardant 1:1,2-bis(tetrabromophthalimide) ethane, BT-93W, purchased from Albemarle, USA; Brominated flame retardant 2: Decabromodiphenyl ethane, Saytex® 8010, purchased from Albemarle, USA; Antimony trioxide: KS-08, purchased from Chenzhou Antimony Industry; Compatibilizer: Maleic anhydride-grafted polypropylene, 1001CN, maleic anhydride grafting rate of 0.6wt%, purchased from Guangzhou Lushan Chemical Co., Ltd. Flame retardant synergist: Flame retardant synergist 1: Zinc borate, HT-207, purchased from Jinan Hongtu New Materials Co., Ltd.; Flame retardant synergist 2: Low melting point glass powder (melting point 450℃), CA450, purchased from Guangzhou Geliner New Materials Co., Ltd.; Phosphorus-based flame retardants: Phosphorus-based flame retardant 1: Diethylaluminum hypophosphite, OP1230, purchased from Clariant Chemicals (China) Co., Ltd.; Phosphorus-based flame retardant 2: Ammonium polyphosphate, SA-APP, Shandong Shian Chemical Co., Ltd.; Fiberglass: Fiberglass 1: ECS13-4.5-508A, purchased from Jushi Group Co., Ltd.; Fiberglass 2: ECS10-03-508C, purchased from Jushi Group Co., Ltd.; Piperazine diphosphate: Hangzhou Jiersi Flame Retardant Chemical Co., Ltd. Piperazine pyrophosphate: CAS NO: 66034-17-1, Sichuan Jingshida Technology Co., Ltd.; Processing aids: Antioxidants: A compound of hindered phenolic antioxidants and thioester antioxidants in a mass ratio of 1:2, all of which are commercially available; It should be noted that the same raw materials used in the parallel experiments of the embodiments and comparative examples in this invention all come from the same source.

[0056] 2. The flame-retardant glass fibers described in the various embodiments and comparative examples were prepared according to the formulations in Table 1 by the following method: An epoxy silane coupling agent (KH560, chemical name: γ-glycidyl etheroxypropyltrimethoxysilane, Zhejiang Boiling Point Chemical Co., Ltd.) was dissolved at 0.5~2 wt% in a water / ethanol mixed solvent (volume ratio 1:1), and then 0.3~0.75 wt% of piperazine diphosphate was dissolved in it, and the pH was adjusted to 4~5 to obtain a treatment solution. Glass fibers were passed through the treatment solution and dried at 110~120℃ for 0.5~1 hours. The mass ratio of piperazine diphosphate to glass fibers was adjusted by adjusting the content of piperazine diphosphate in the treatment solution.

[0057] 3. The polypropylene composite materials described in the various embodiments and comparative examples were prepared according to the formulations in Tables 2-3 by the following methods: S1. Mix all components except flame-retardant glass fiber / glass fiber in a high-speed mixer for 1-3 minutes until homogeneous to obtain a premix; S2. The premixed material described in step S1 is fed into a twin-screw extruder through the main feed port, and flame-retardant glass fiber / glass fiber is fed into the side feed port. The mixture is melt-blended, extruded, and granulated to obtain a polypropylene composite material. The temperature of the twin-screw extruder in zones one to five is 150~160℃, the temperature in zones six to ten is 180~190℃, the temperature in zones eleven to twelve is 210~230℃, and the die temperature is 210~230℃. The rotational speed of the twin-screw extruder is 350~600 rpm.

[0058] 4. Performance Testing: (1) Flame retardant performance test: The polypropylene composite materials prepared in each example and comparative example were injection molded into 125mm×12.5mm×0.80mm strips, and the flame retardant performance was tested according to UL94-2023.

[0059] (2) Maximum smoke density level: The polypropylene composite materials prepared in each example and comparative example were injection molded into square plates of (25.4±0.3) mm × (25.4±0.3) mm × (6.2±0.3) mm, and the smoke density of combustion or decomposition was tested according to standard GB / T 8627-2007.

[0060] (3) Impact strength test: The polypropylene composite materials prepared in each example and comparative example were prepared according to the standard ISO180-2019. They were placed in an environment of 23±2℃ and 50±5% humidity for 48 hours, and the impact strength of the samples was tested using a 2.75J pendulum.

[0061] Examples 1-15 and Comparative Examples 1-7 Table 1. Amounts of each component in flame-retardant glass fiber in Examples 1-4 and Comparative Examples 1-3 (unit: parts by weight)

[0062] The flame-retardant glass fibers obtained in Examples 1-4 correspond to flame-retardant glass fibers 1-4, and the flame-retardant glass fibers obtained in Comparative Examples 1-3 correspond to flame-retardant glass fibers 5-7.

[0063] Table 2. Amounts (parts by weight) and properties of each component in the polypropylene composites of Examples 5-13

[0064] Table 3. Amounts (parts by weight) and properties of each component in the polypropylene composites of Examples 14-15 and Comparative Examples 4-7

[0065] The polypropylene composite materials prepared in the various embodiments of the present invention have good flame retardant properties and impact strength. Specifically, they all achieve V-0 flame retardancy and have an impact strength of not less than 13 kJ / m. 2 The maximum smoke density is no higher than 120 MSD.

[0066] As can be seen from Comparative Example 4, if piperazine diphosphate in flame-retardant glass fiber is replaced by other substances, the resulting flame-retardant glass fiber, when applied to polypropylene composite materials, cannot form a char layer or suppress the wick effect during combustion, resulting in low flame-retardant efficiency, no improvement in afterflame and afterglow time, and deterioration of maximum smoke density.

[0067] As can be seen from Comparative Examples 5 and 6, if the mass ratio of glass fiber to piperazine diphosphate in flame-retardant glass fiber is too low or too high, when the mass of piperazine diphosphate is too low, the char layer is difficult to effectively block combustion, weakening the flame-retardant and smoke-suppressing effect; when it is too high, it will weaken the interfacial bonding force between glass fiber and polypropylene resin, which will have an adverse effect on mechanical properties. The piperazine diphosphate surface treatment on glass fiber is easy to fall off, which is actually detrimental to suppressing the wick effect.

[0068] As can be seen from Comparative Example 7, the blend obtained by directly adding piperazine diphosphate and ordinary glass fiber to the polypropylene resin system and extruding it cannot effectively form a char layer on the fiber surface. Therefore, it cannot hinder the transport of molten polypropylene fuel during combustion to suppress the wick effect, which is not conducive to improving flame retardant performance, reducing afterflame and afterglow time and maximum smoke density.

[0069] 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 flame-retardant glass fiber, characterized in that, The flame-retardant glass fiber comprises glass fiber and piperazine diphosphate, wherein the piperazine diphosphate is coated on the surface of the glass fiber, and the mass ratio of piperazine diphosphate to glass fiber is (0.2~0.7):100; preferably (0.3~0.5):

1.

2. The flame-retardant glass fiber according to claim 1, characterized in that, The flame-retardant glass fiber has a chopped length of 3-5 mm and an average diameter of 10-13 μm.

3. The flame-retardant glass fiber according to claim 1, characterized in that, It was prepared by the following method: It is obtained by impregnating glass fibers in a treatment solution containing silane coupling agent and piperazine diphosphate, followed by drying.

4. A polypropylene composite material, characterized in that, Includes the following components, calculated in parts by weight: 25-55 parts of polypropylene resin; 20-30 parts of brominated flame retardant; 3-10 parts of antimony trioxide; 2-4 parts compatibilizer; 12 to 35 parts of the flame-retardant glass fiber as described in any one of claims 1 to 3.

5. The polypropylene composite material according to claim 4, characterized in that, The brominated flame retardant includes one or more of the following: decabromodiphenyl ethane, decabromodiphenyl ether, styrene bromide, tris(tribromoneopentyl) phosphate, tetrabromobisphenol A-bis(2,3-dibromopropyl ether), tris(2,3-dibromopropyl)isocyanate, bromobisphenol S-bis(2,3-dibromopropyl) ether, 1,2-bis(tetrabromophthalimide) ethane or melamine hydrobromide and 1,2-bis(pentabromophenyl) ethane.

6. The polypropylene composite material according to claim 4, characterized in that, The compatibilizer includes maleic anhydride-grafted polyolefin and / or glycidyl acrylate-grafted polyolefin; preferably, the maleic anhydride-grafted polyolefin includes maleic anhydride-grafted polypropylene and / or maleic anhydride-grafted ethylene-octene copolymer; the glycidyl acrylate-grafted polyolefin is glycidyl acrylate-grafted polypropylene.

7. The polypropylene composite material according to claim 4, characterized in that, Meet at least one of the following four conditions: (a) The melt flow rate of the polypropylene resin at 230°C and 2.16 kg load is 8~30 g / 10 min; (b) It also includes 1 to 4 parts of a flame retardant synergist; said flame retardant synergist includes one or more of ammonium borate, zinc borate, low melting point glass powder or zinc oxide; (c) It also includes 2 to 4 parts of phosphorus-based flame retardant; the phosphorus-based flame retardant includes one or more of inorganic aluminum hypophosphite, inorganic calcium hypophosphite, inorganic sodium hypophosphite, aluminum diethylphosphite, or aluminum diisobutylphosphite; (d) also includes 0.1 to 2 parts of processing aids; said processing aids include antioxidants.

8. A method for preparing the polypropylene composite material according to any one of claims 4 to 7, characterized in that, Includes the following steps: S1. Mix all components except flame-retardant glass fiber evenly to obtain a premix; S2. The premixed material described in step S1 is fed into the extruder through the main feed port, and the flame-retardant glass fiber is fed into the extruder through the side feed port. The mixture is then melt-blended, extruded, and granulated to obtain the final product.

9. The application of the polypropylene composite material according to any one of claims 4 to 7 in the preparation of materials for the electronics, electrical appliances, and automotive industries.

10. A controller housing, characterized in that, It is prepared using the polypropylene composite material described in any one of claims 4 to 7.

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