A phosphorus-nitrogen flame retardant, an ABS composite containing the phosphorus-nitrogen flame retardant and a preparation method thereof

Abstract

This invention discloses a phosphorus-nitrogen flame retardant, an ABS composite material containing the phosphorus-nitrogen flame retardant, and a method for preparing the same. It belongs to the technical field of functional additives for polymer materials. The phosphorus-nitrogen flame retardant is a hybrid flame retardant additive system with defined structural characteristics, comprising at least: (a) an organophosphorus flame retardant unit containing an aluminum-oxygen-phosphorus structure; (b) an organosilicon bridging structure connected to the organophosphorus flame retardant unit via a silicon-oxygen bond; and (c) a hindered amine group connected to the organosilicon bridging structure via a covalent bond. The ABS composite material contains the phosphorus-nitrogen flame retardant. The hindered amine group is introduced into the flame retardant system chemically, reducing the migration of the additive in the ABS resin. The organophosphorus, organosilicon, and hindered amine form a synergistic effect in the ABS resin, improving the material's aging resistance while ensuring flame retardant performance.

Description

Technical Field

[0001] This invention belongs to the technical field of functional additives for polymer materials, specifically relating to a phosphorus-nitrogen flame retardant, an ABS composite material containing the phosphorus-nitrogen flame retardant, and a method for preparing the same. Background Technology

[0002] Acrylonitrile-butadiene-styrene copolymer (ABS) resin has been widely used in electronics, home appliances, and automotive parts due to its excellent mechanical and processing properties. However, ABS resin itself is flammable, and its butadiene phase is highly susceptible to aging under the influence of heat, oxygen, and light, leading to discoloration and performance degradation. This, to some extent, limits its application under long-term service conditions.

[0003] Currently, flame retardants for ABS resin typically employ brominated triazine flame retardants, combined with inorganic or organophosphorus flame retardants to enhance flame retardancy efficiency. On the other hand, hindered amine light stabilizers are often added to ABS resin through physical blending, which presents problems such as easy migration and poor compatibility with the flame retardant system, making it difficult to simultaneously achieve both flame retardant and aging resistance properties.

[0004] Therefore, it is necessary to construct a flame retardant system that combines flame-retardant functional units with aging-resistant functional units at the chemical structure level in order to improve the overall performance of ABS materials. Summary of the Invention

[0005] The purpose of this invention is to provide a phosphorus-nitrogen flame retardant that, by chemically combining organophosphorus flame retardant units, organosilicon bridging structures and hindered amine groups, produces a flame retardant with good dispersibility and low migration in ABS resin, while also possessing flame retardant and aging resistance effects.

[0006] The technical solution of the present invention is as follows:

[0007] A phosphorus-nitrogen flame retardant, wherein the phosphorus-nitrogen flame retardant is a hybrid flame retardant additive system with defined structural characteristics, comprising at least:

[0008] (a) An organophosphorus flame retardant unit containing an aluminum-oxygen-phosphorus structure;

[0009] (b) An organosilicon bridging structure that is connected to the organophosphorus flame retardant unit via silicon-oxygen bonds;

[0010] (c) A hindered amine group connected to the organosilicon bridging structure via a covalent bond.

[0011] The phosphorus-nitrogen flame retardant is not a small molecule compound with a single, defined molecular formula, but rather a flame retardant additive system with a defined functional group composition and linkage mode.

[0012] Preferably, the organophosphorus flame retardant unit is aluminum organophosphate.

[0013] Preferably, the organophosphorus flame retardant unit is aluminum diethylphosphite.

[0014] Preferably, the organosilicon bridging structure is derived from an organosilicon compound containing a hydrolyzable alkoxy group or its hydrolysis condensation product; the organosilicon compound is selected from any one or more of epoxysilanes and hydroxyorganosilicones; wherein the organosilicon compound contains a reactive functional group capable of reacting with hindered amine derivatives to construct or retain a carbamate bond structure.

[0015] Preferably, the organosilicon compound is selected from any one or more of γ-glycidoxypropyltrimethoxysilane and 3-hydroxypropyltrimethoxysilane.

[0016] Preferably, the hindered amine derivative is selected from any one or more of 2,2,6,6-tetramethylpiperidine carbamate derivatives.

[0017] The phosphorus-nitrogen flame retardant described in this invention is essentially a bridging network structure with polysiloxane as the core and organophosphorus and hindered amine functional groups attached to the surface. Its formation mechanism mainly involves the following two chemical processes:

[0018] (1) During the reaction, the alkoxy group in the silane coupling agent undergoes hydrolysis in the aqueous alcohol system to generate silanol groups (Si–OH). The generated silanol groups further undergo the following two types of reactions: condensation with other silanol groups to form a Si–O–Si network; or forming Si–O–Al bonds or stable coordination bonds with oxygen coordination sites or aluminum centers on the surface of the organophosphorus flame retardant unit. The connection methods include: covalent Si–O–Al bonds; or stable coordination structures achieved through oxygen bridges. This technology does not limit the connection to a single chemical bond, but refers to the structural integration of organosilicon units and organophosphorus flame retardant units through silicon-oxygen bridging structures.

[0019] (2) During the reaction, when the hindered amine derivative contains an amino (–NH2 or –NH–) structure, the epoxy group in the organosilicon compound can undergo a nucleophilic ring-opening reaction under heating conditions to generate a β-hydroxyamine structure, thereby achieving a covalent connection between the hindered amine group and the silicon bridging structure; under heating conditions or a catalytic environment, if the system contains hydroxyl groups and active carbonate or carbamate structures, transesterification can also occur to form an –O–C(=O)–NH– bond connection structure. This reaction pathway belongs to the known hydroxyl-involved carbonate transesterification reaction in the art.

[0020] Therefore, the final product contains urethane bonds or equivalent stable bond types, achieving the chemical fixation of hindered amine groups and silicon-oxygen networks.

[0021] This technique does not limit the specific reaction path, but rather limits the presence of the aforementioned connection structure in the resulting product.

[0022] A method for preparing a phosphorus-nitrogen flame retardant includes the following steps:

[0023] S1. Under nitrogen protection, the organophosphorus flame retardant unit is added to a high-boiling-point organic solvent and stirred to form a uniformly dispersed system.

[0024] S2. Subsequently, an organosilicon compound containing hydrolyzable alkoxy groups or its hydrolysis condensation product is added to the uniformly dispersed system, and the reaction is carried out under heating conditions to allow the organosilicon compound to be adsorbed or grafted onto the surface of the organophosphorus flame retardant.

[0025] After the S3 and S2 reactions are completed, the system is cooled to a medium-low temperature range, and an aqueous alcohol solvent is slowly added to cause the organosilicon compound to undergo partial hydrolysis, condensation or complexation reaction.

[0026] S4. Next, the hindered amine derivative and catalyst are added to the reaction system of step S3, and the reaction continues under mild conditions. After the nucleophilic ring-opening reaction or transesterification reaction is completed, the solvent is removed under reduced pressure, washed and dried to obtain the phosphorus-nitrogen flame retardant.

[0027] An ABS composite material comprising a phosphorus-nitrogen flame retardant.

[0028] Preferably, by weight, the composition comprises 73–79 parts of ABS resin, 12–14 parts of brominated triazine flame retardant, and 7–15 parts of phosphorus-nitrogen flame retardant, with the ratio of brominated triazine to phosphorus-nitrogen flame retardant being 4:5 to 2:1.

[0029] A method for preparing ABS composite material includes the following steps:

[0030] The raw materials were placed in a drying oven and dried at 80 ℃ for 4 h. Then, the raw materials of each component were placed in a mixer according to the ratio and mixed thoroughly. The mixed raw materials were then fed into a twin-screw extruder with a temperature range of 190-230 ℃ and a speed of 300-400 rpm and extruded into a granulator for granulation to obtain ABS composite material with phosphorus and nitrogen flame retardant.

[0031] The beneficial effects of this invention are as follows:

[0032] (1) By introducing hindered amine groups into the flame retardant system through chemical means, the migration of additives in ABS resin is reduced;

[0033] (2) Organophosphorus, organosilicon and hindered amine form a synergistic effect in ABS resin, which improves the aging resistance of the material while ensuring flame retardant performance;

[0034] (3) The phosphorus-nitrogen flame retardant has good dispersibility in ABS resin and has little adverse effect on the mechanical properties of the material;

[0035] (4) The preparation method has mild process conditions and is suitable for industrial production. Detailed Implementation

[0036] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way.

[0037] The raw materials used in this invention are sourced from the following sources:

[0038] ABS resin: HI-121H / LG-Yognxing, Wuxi Weixinlong Plastics Import & Export Co., Ltd.;

[0039] Bromotriazine: FR-245, Guangzhou Yinuo Chemical Technology Co., Ltd.;

[0040] Diethylaluminum hypophosphite: CQ-X1-80, Jiaxing Jingzuan New Material Technology Co., Ltd.;

[0041] Silane coupling agent KH 560: γ-glycidyl etheroxypropyltrimethoxysilane, Guangzhou Yihuisheng Chemical Co., Ltd.;

[0042] Methyl (2,2,6,6-tetramethylpiperidin-4-yl)carbamate: Suqian Liansheng Technology Co., Ltd.;

[0043] N,N-Dimethylformamide (DMF): Aladdin;

[0044] Xylene: Shandong Xuchen Chemical Technology Co., Ltd.;

[0045] 3-Hydroxypropyltrimethoxysilane: Jiangxi Chenguang New Materials Co., Ltd.;

[0046] Tetrabutyl titanate: Aladdin.

[0047] The equipment models used in this invention are as follows:

[0048] Drying oven: DHG-9624A, Changzhou Jintan Liangyou Instrument Co., Ltd.;

[0049] Mixer: SHR-10A, Zhangjiagang Hongji Machinery Co., Ltd.;

[0050] Twin-screw extruder: HK-36, Nanjing Keya Chemical Complete Equipment Co., Ltd.;

[0051] Granulator: ZM130 Aomai granulator, Jiangsu Zhimao Machinery Co., Ltd.;

[0052] Injection molding machine: MA900III / 280SE, Haitian Plastics Machinery Group Co., Ltd., used for making standard specimens for flame retardancy and mechanical testing.

[0053] Example 1

[0054] The preparation method of phosphorus-nitrogen flame retardants includes the following steps:

[0055] Under nitrogen protection, 30 g of aluminum diethylphosphite (organophosphorus flame retardant unit) was added to the high-boiling-point organic solvent N,N-dimethylformamide (DMF) and stirred to form a homogeneous dispersion. Subsequently, 0.5 g of silane coupling agent KH 560 (γ-glycidoxypropyltrimethoxysilane) was added to the homogeneous dispersion, and the temperature was raised to 150°C. o The reaction was carried out under constant temperature reflux for 6 h, allowing KH 560 to be adsorbed and initially grafted onto the surface of diethyl hypophosphoric acid particles.

[0056] After the above reaction is complete, cool the system to 60°C. o At temperature C (low to medium temperature range), 20 mL of an ethanol / water mixture (9:1 volume ratio) was slowly added, and the mixture was kept at this temperature for 1 h to induce hydrolysis and condensation, causing partial hydrolysis and condensation of the organosilicon compound to generate silanol groups (Si–OH). The generated silanol groups further undergo two types of reactions: condensation with other silanol groups to form a Si–O–Si network; and formation of Si–O–Al bonds or stable coordination bonds with oxygen coordination sites or aluminum centers on the surface of organophosphorus flame retardant units. Subsequently, 4.5 g of methyl (2,2,6,6-tetramethylpiperidin-4-yl)carbamate and 0.1 g of tetrabutyl titanate were added to the system, and the temperature was raised to 75°C. o The reaction continued at C (under mild conditions) for 4 h. Under the catalysis of titanate ester, the side chain carbon hydroxyl groups generated from the ring-opening reaction underwent transesterification or alcoholysis with the methyl ester group in the HALS molecule (methyl (2,2,6,6-tetramethylpiperidin-4-yl)carbamate), removing small molecule methanol and forming a stable organic carbamate bond (-CO-CO-NH-HALS), thereby fixing the hindered amine group onto the organosilicon hybrid framework. After the reaction was completed, the solvent was removed under reduced pressure, washed, and dried to obtain the phosphorus-nitrogen flame retardant. The obtained phosphorus-nitrogen flame retardant was a pale yellow solid, 33.1 g, and exhibited good thermal stability within the conventional processing temperature range.

[0057] A method for preparing a flame-retardant ABS composite material containing phosphorus and nitrogen flame retardants includes the following steps:

[0058] The raw materials in the formulation shown in Table 1 were placed in a drying oven and dried at 80 ℃ for 4 h. Then, the raw materials of each component were placed in a mixer according to the ratio and mixed thoroughly. The mixed raw materials were then fed into a twin-screw extruder with a temperature range of 190-230 ℃ and a speed of 350 rpm and extruded into a granulator for granulation to obtain ABS composite material with phosphorus and nitrogen flame retardant.

[0059] Examples 2-6

[0060] Repeat the steps of Example 1, except that the raw material formulations are different from those in Example 1, as shown in Table 1.

[0061] Example 7

[0062] The preparation method of phosphorus-nitrogen flame retardants includes the following steps:

[0063] Under nitrogen protection, 30 g of aluminum diethylphosphite (organophosphorus flame retardant unit) was added to xylene, a high-boiling-point organic solvent, and stirred to form a uniform dispersion system. Then, 0.5 g of 3-hydroxypropyltrimethoxysilane was added to the uniform dispersion system, and the mixture was refluxed at 130 °C for 6 h to allow KH 560 to be adsorbed and initially grafted onto the surface of the diethylphosphite particles.

[0064] After the above reaction is completed, the system is cooled to 60 °C (low to medium temperature range), and 20 mL of an ethanol / water mixture (9:1 volume ratio) is slowly added. The mixture is kept at this temperature for 1 h to carry out hydrolysis and condensation, generating silanol groups (Si–OH). The generated silanol groups further undergo the following two types of reactions: condensation with other silanol groups to form a Si–O–Si network; and formation of Si–O–Al bonds or stable coordination bonds with oxygen coordination sites or aluminum centers on the surface of organophosphorus flame retardant units. Subsequently, 4.5 g of methyl (2,2,6,6-tetramethylpiperidin-4-yl)carbamate and 0.1 g of tetrabutyl titanate (catalyst) were added to the system. The reaction was continued for 4 h at 110-120 °C (under mild conditions). Under the catalysis of tetrabutyl titanate, the hydroxyl groups on 3-hydroxypropyltrimethoxysilane underwent transesterification or alcoholysis with methyl (2,2,6,6-tetramethylpiperidin-4-yl)carbamate, thereby grafting hindered amine groups. After the reaction was completed, the solvent and byproducts (methanol) were removed under reduced pressure, followed by washing and drying to obtain the phosphorus-nitrogen flame retardant. The obtained phosphorus-nitrogen flame retardant was a pale yellow solid, weighing 34.3 g, and exhibited good thermal stability within the conventional processing temperature range.

[0065] A method for preparing a flame-retardant ABS composite material containing phosphorus and nitrogen flame retardants includes the following steps:

[0066] The raw materials (79 parts ABS resin, 14 parts bromotriazine, and 7 parts phosphorus-nitrogen flame retardant prepared in this example) were placed in a drying oven and dried at 80 °C for 4 h. Then, the raw materials were placed in a mixer according to the proportion and mixed thoroughly. The mixed raw materials were then fed into a twin-screw extruder with a temperature range of 190-230 °C and a speed of 350 rpm and extruded into a granulator for granulation to obtain the ABS composite material with phosphorus-nitrogen flame retardant.

[0067] Comparative Examples 1-6

[0068] Repeat the steps of Example 1, except that the raw material formulas are different from those in Example 1, as shown in Table 2.

[0069] The relevant testing methods are as follows:

[0070] (1) Melt flow rate: in accordance with GB / T 3682.1-2018 standard, load 10.0 Kg, temperature 220 ℃;

[0071] (2) Flame retardant: Complies with UL-94 testing standards, thickness 1.6 mm;

[0072] (3) Impact strength: in accordance with ISO 180-2023 standard, 23 °C;

[0073] (4) Elongation at break: GB / T 1040.2-2022 standard, test speed 50 mm / min;

[0074] (5) Color difference: Comply with GB / T 16422.2-2022 standard, aging test for 168 h.

[0075] Table 1: Weight parts of each component and test results in the examples

[0076]

[0077] As can be seen from Examples 1-7, ABS resin exhibits excellent flame retardant properties, mechanical properties and anti-aging properties under the synergistic effect of the phosphorus-nitrogen flame retardant and brominated triazine prepared in this invention. The UL-94 test reaches V-0, and V-0 can be achieved when the ratio of brominated triazine to phosphorus-nitrogen flame retardant is 4:5 to 2:1.

[0078] Table 2: Weight parts of each component and test results in the comparative example

[0079]

[0080] As can be seen from Comparative Example 1 and Examples 5 and 6, in the presence of bromotriazine, the UL-94 test of the ABS composite material cannot reach V-0 without the addition of phosphorus and nitrogen flame retardants.

[0081] As can be seen from Comparative Examples 2 and 3, if the ratio of brominated triazine to phosphorus nitrogen flame retardant is not within the scope of this invention, the UL-94 test of the ABS composite material will not reach V-0.

[0082] In Comparative Example 4, diethylaluminum hypophosphite, ABS resin, and bromotriazine were directly mixed evenly in a mixer. In Comparative Example 5, diethylaluminum hypophosphite, silane coupling agent KH 560, and methyl (2,2,6,6-tetramethylpiperidin-4-yl)carbamate were mixed evenly in a mixer.

[0083] As shown in Comparative Examples 4, 5, and Example 6, the addition of silane coupling agent KH 560 optimizes the impact strength and elongation at break of the ABS composite material. Furthermore, the organosilicon bridging achieves molecular-level interfacial coupling, transforming the flame-retardant unit from a "filler phase" to a "structural phase." This structural change allows the material to more effectively transfer and dissipate energy under external forces, resulting in superior impact strength and elongation at break compared to simple physical mixing. In Example 6, because methyl (2,2,6,6-tetramethylpiperidin-4-yl)carbamate does not readily migrate after reacting with silane coupling agent KH 560, the color difference of the ABS composite material after aging is significantly reduced. In Comparative Example 5, however, methyl (2,2,6,6-tetramethylpiperidin-4-yl)carbamate and silane coupling agent KH 560 exist independently, only through simple blending, resulting in poor flame retardant and anti-aging properties of the ABS composite material.

[0084] It should be noted that the above content merely illustrates the technical concept of the present invention and cannot be used to limit the scope of protection of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A phosphorus-nitrogen flame retardant, characterized in that, This phosphorus-nitrogen flame retardant is a hybrid flame retardant additive system with defined structural characteristics, comprising at least: (a) An organophosphorus flame retardant unit containing an aluminum-oxygen-phosphorus structure; (b) An organosilicon bridging structure that is connected to the organophosphorus flame retardant unit via silicon-oxygen bonds; (c) A hindered amine group connected to the organosilicon bridging structure via a covalent bond.

2. The phosphorus-nitrogen flame retardant according to claim 1, characterized in that, The organophosphorus flame retardant unit is aluminum organophosphate.

3. The phosphorus-nitrogen flame retardant according to claim 2, characterized in that, The organophosphorus flame retardant unit is diethylaluminum hypophosphite.

4. The phosphorus-nitrogen flame retardant according to claim 1, characterized in that, The organosilicon bridging structure is derived from an organosilicon compound containing a hydrolyzable alkoxy group or its hydrolysis condensation product; the organosilicon compound is selected from any one or more of epoxy silanes and hydroxy organosilicones; wherein the organosilicon compound contains a reactive functional group capable of reacting with hindered amine derivatives to construct or retain a urethane bond structure.

5. The phosphorus-nitrogen flame retardant according to claim 4, characterized in that, The organosilicon compound is selected from any one or more of γ-glycidoxypropyltrimethoxysilane and 3-hydroxypropyltrimethoxysilane.

6. The phosphorus-nitrogen flame retardant according to claim 1, characterized in that, The hindered amine group is derived from a hindered amine derivative, which is selected from any one or more of 2,2,6,6-tetramethylpiperidine carbamate derivatives.

7. A method for preparing the phosphorus-nitrogen flame retardant as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Under nitrogen protection, the organophosphorus flame retardant unit is added to a high-boiling-point organic solvent and stirred to form a uniformly dispersed system. S2. Subsequently, an organosilicon compound containing hydrolyzable alkoxy groups or its hydrolysis condensation product is added to the uniformly dispersed system, and the reaction is carried out under heating conditions to allow the organosilicon compound to be adsorbed or grafted onto the surface of the organophosphorus flame retardant. After the S3 and S2 reactions are completed, the system is cooled to a medium-low temperature range, and an aqueous alcohol solvent is slowly added to cause the organosilicon compound to undergo partial hydrolysis, condensation or complexation reaction. S4. Next, the hindered amine derivative and catalyst are added to the reaction system of step S3, and the reaction continues under mild conditions. After the nucleophilic ring-opening reaction or transesterification reaction is completed, the solvent is removed under reduced pressure, washed and dried to obtain the phosphorus-nitrogen flame retardant.

8. An ABS composite material, characterized in that, The ABS composite material contains the phosphorus-nitrogen flame retardant as described in any one of claims 1–6.

9. The ABS composite material according to claim 8, characterized in that, By weight, the ABS resin comprises 73–79 parts, the brominated triazine flame retardant comprises 12–14 parts, and the phosphorus-nitrogen flame retardant comprises 7–15 parts, with the ratio of brominated triazine to phosphorus-nitrogen flame retardant being 4:5 to 2:

1.

10. A method for preparing an ABS composite material as described in any one of claims 8 or 9, characterized in that, Includes the following steps: The raw materials were placed in a drying oven and dried at 80 ℃ for 4 h. Then, the raw materials of each component were placed in a mixer according to the ratio and mixed thoroughly. The mixed raw materials were then fed into a twin-screw extruder with a temperature range of 190-230 ℃ and a speed of 300-400 rpm and extruded into a granulator for granulation to obtain ABS composite material with phosphorus and nitrogen flame retardant.

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