WO2025190075A1 - Low-acidity halogen-free flame retardant and preparation method therefor, and flame-retardant polyamide composite material and application thereof - Google Patents

Abstract

Disclosed in the present invention is a low-acidity halogen-free flame retardant, comprising the following components in parts by weight: 89-96 parts of dialkyl aluminum hypophosphite and 5-10 parts of a hindered amine light stabilizer. The pH value of the low-acidity halogen-free flame retardant is 6.5-7. In the present invention, the acidity of the halogen-free flame retardant is reduced and a specific content of hindered amine light stabilizer is contained, so that when the halogen-free flame retardant is applied to a polyamide composition, the corrosion of the flame retardant to a resin matrix can be ameliorated, and additionally, the flame retardancy and the oxygen isolation are improved, and the corrosion to rubber is reduced.

Description

A low-acid halogen-free flame retardant and its preparation method, and a flame-retardant polyamide composite material and its application Technical Field

The present invention relates to the technical field of polymer materials, in particular to a low-acid halogen-free flame retardant and a preparation method thereof, and a flame-retardant polyamide composite material and application thereof.

Background Art

Hypophosphite flame retardants have a high phosphorus content and can be used as flame retardants or flame retardant synergists. However, they have drawbacks: their strong acidity can cause degradation of polymer materials, corrosion of equipment, and migration and precipitation. These issues limit their use as flame retardants. Polyamide resins are particularly susceptible to acidic components. Therefore, reducing the acidity of materials without compromising their flame retardancy, thereby effectively reducing their corrosiveness, is of great economic value.

At the same time, the applicant discovered through experiments that the addition of commercially available dialkyl aluminum hypophosphite flame retardants significantly reduces the oxygen barrier properties of polyamide composites, accelerates the internal oxidation process of the material, shortens its service life, and reduces its application in electronic appliances, power tools, and automobiles. Furthermore, commercially available dialkyl aluminum hypophosphite flame retardants can make polyamide composites corrosive to contacting rubber materials, affecting their application in new energy vehicle parts (such as connectors and connectors).

However, there is no report on the above-mentioned method for improving the related defects in the prior art.

Summary of the Invention

The purpose of the present invention is to overcome the above technical defects and provide a low-acidity, halogen-free flame retardant with good flame retardancy and improved oxygen barrier properties of polyamide compositions, as well as a preparation method and application thereof.

The present invention is achieved through the following technical solutions:

A low-acid halogen-free flame retardant, comprising the following components in parts by weight:

Dialkyl aluminum hypophosphite 89-96 parts,

Hindered amine light stabilizer 5-10 parts,

The pH value of the low-acid halogen-free flame retardant is 6.5-7.

The test method for the pH value of low-acid halogen-free flame retardant is as follows: take 500 mg of low-acid halogen-free flame retardant, add 50 ml of deionized water, place it in an 80℃ ultrasonic water bath and stir it thoroughly for 15 minutes, take the mixed solution into a centrifuge tube for high-speed centrifugation, and then test the pH value of the supernatant.

The dialkyl aluminum hypophosphite is selected from diethyl aluminum hypophosphite.

The hindered amine light stabilizer is selected from at least one of a polymer hindered amine light stabilizer and a low molecular weight hindered amine light stabilizer; the polymer hindered amine light stabilizer is selected from at least one of the following substances:

1,5,8,12-Tetrakis[4,6-bis(N-butyl-N-1,2,2,6,6-pentamethyl-4-piperidinylamino)-1,3,5-triazin-2-yl]-1,5,8,12-tetraazadodecane (CAS: 106990-43-6),

Poly-{[6-[(1,1,3,3-tetramethylbutyl)-imino]-1,3,5-triazine-2,4-diyl][2-(2,2,6,6-tetramethylpiperidinyl)-amino]-hexylene-[4-(2,2,6,6-tetramethylpiperidinyl)-imino] (CAS: 70624-18-9),

Poly[1-(2'-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidinylsuccinate](CAS:65447-77-0),

1,2,3,4-Butanetetracarboxylic acid tetrakis (1,2,2,6,6-pentamethyl-4-piperidinyl) ester (CAS: 91788-83-9) (LA-52),

N,N'-Bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,6-hexanediamine, polymer with 2,4,6-trichloro-1,3,5-triazine, N-butyl-1-butylamine and N-butyl-2,2,6,6-tetramethyl-4-piperidinamine (CAS: 192268-64-7),

Poly{(6-morpholinyl-5-triazine-2,4-diyl)(2,2,6,6-tetramethylpiperidinyl)iminohexamethylene[(2,2,6,6-tetramethylpiperidinyl)imino]} (CAS: 82451-48-7).

The low molecular weight hindered amine light stabilizer is selected from at least one of the following substances:

Bis-2,2,6,6-tetramethylpiperidinol sebacate (CAS: 52829-07-9),

N,N’-diformyl-N,N’-bis(2,2,6,6-tetramethyl-4-piperidinyl)-hexamethylenediamine (CAS: 124172-53-8),

1,2,3,4-Butanetetracarboxylic acid tetrakis (1,2,2,6,6-pentamethyl-4-piperidinyl) ester (CAS: 91788-83-9),

2,2,6,6-Tetramethyl-4-piperidinyl stearate (CAS: 167078-06-0).

Preferably, the hindered amine light stabilizer is selected from a polymer hindered amine light stabilizer; further preferably, the polymer hindered amine light stabilizer is selected from at least one of poly-{[6-[(1,1,3,3-tetramethylbutyl)-imino]-1,3,5-triazine-2,4-diyl][2-(2,2,6,6-tetramethylpiperidinyl)-amino]-hexamethylene-[4-(2,2,6,6-tetramethylpiperidine)-imino], poly[1-(2'-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidine succinate].

The preparation method of the low-acid halogen-free flame retardant of the present invention comprises the following steps: weighing 1-5 parts of calcium oxide, 40-98 parts of water, 1-5 parts of ammonium aluminum sulfate, 90-95 parts of dialkyl aluminum hypophosphite, and 5-10 parts of hindered amine light stabilizer by weight, dissolving the calcium oxide and ammonium aluminum sulfate in water, adjusting the pH value to 6.5-7 with 5-15wt% dilute hydrochloric acid, then adding dialkyl aluminum hypophosphite and hindered amine light stabilizer, stirring for 0.5-3 hours, controlling the temperature at 60-90°C during the stirring, then standing for 5-15 hours, filtering, and drying to obtain a low-acid halogen-free flame retardant. The pH value of the tested product is in the range of 6.5-7. The present application can adjust the pH value to 6.5-7 by the above method. In the above process, dialkyl aluminum hypophosphite and hindered amine light stabilizer are insoluble in water. Therefore, the ratio of dialkyl aluminum hypophosphite and hindered amine light stabilizer in the product is close to that of the raw material. The ratio of the two is tested by X-ray fluorescence spectrometer and elemental analyzer. The content of phosphorus and nitrogen elements is determined by combining the test results of the two, and then the ratio of dialkyl aluminum hypophosphite and hindered amine light stabilizer is obtained.

The invention also discloses a flame-retardant polyamide composite material, which comprises the following components in parts by weight: 30-80 parts of polyamide resin and 20-40 parts of the low-acid halogen-free flame retardant of the invention.

The polyamide resin is selected from at least one of aliphatic polyamide resin, semi-aromatic polyamide resin and polylactam resin.

The aliphatic polyamide resin is selected from PA66, PA46, PA610, PA612, PA56, PA510, PA512, PA910, PA912, PA913, PA914, PA915, PA616, PA936, PA1010, PA1012, PA1013, PA1014, PA1210, PA1212, PA1213, PA1214, PA614, PA613, PA615, PA616 and the like.

The semi-aromatic polyamide is selected from PA MXD6, PA10T, PA10T1010, PA10T66, PA6T, PA6T66, PA9T and the like.

The polylactam is selected from PA5, PA6, PA11, PA12 and the like.

The relative viscosity range of the polyamide resin suitable for the present invention is 1.8-3.8. The test method for polyamide viscosity refers to GB12006.1-89. The specific test method is to measure the relative viscosity of polyamide with a concentration of 0.25g/dl in 98% concentrated sulfuric acid at 25±0.01℃.

By weight, the invention further comprises 0-1 part of a heat stabilizer, wherein the heat stabilizer is selected from phenolic heat stabilizers and thiosulfate antioxidants.

The flame retardant polyamide composite material may also contain 0-30 parts of fillers, such as talc powder, glass fiber, etc.

The flame-retardant polyamide composite material is used to prepare electronic and electrical parts in contact with rubber, and vehicle accessories in contact with rubber, such as connectors and connectors.

Those skilled in the art can choose whether to add a certain amount of filler according to actual needs. The filler can be conventional fillers such as talc, glass fiber, carbon fiber, etc.

The preparation method of the flame retardant polyamide composite material is as follows: uniformly mixing the components, extruding and granulating the components through a twin-screw extruder, wherein the screw temperature range is 170-300°C and the rotation speed is 400-600r/min.

The present invention has the following beneficial effects:

The present invention uses a weakly alkaline buffer pH adjustment system formed by calcium oxide and ammonium aluminum sulfate to effectively adjust the pH value of dialkyl aluminum hypophosphite to a weak acidic state. At the same time, the pH adjusted by the buffer system of the present invention has a longer timeliness, which solves the pH fluctuation over a longer time dimension. In addition, a specific amount of hindered amine light stabilizer is added during the preparation process, which can significantly improve the flame retardancy and oxygen barrier properties of the polyamide composite material, and improve the corrosiveness of the polyamide composite material to rubber.

DETAILED DESCRIPTION

The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several variations and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

The raw materials used in the present invention come from the following sources:

PA56: ECOPENT1273, relative viscosity 2.3, Shandong Kaisai;

PA6: HY-2500A, relative viscosity 2.4, Jiangsu Haiyang Chemical Fiber;

PA66/6T: C1504T, relative viscosity 2.6, purchased from Shandong Guangyin;

Hindered amine light stabilizer A: Poly-{[6-[(1,1,3,3-tetramethylbutyl)-imino]-1,3,5-triazine-2,4-diyl][2-(2,2,6,6-tetramethylpiperidinyl)-amino]-hexamethylene-[4-(2,2,6,6-tetramethylpiperidinyl)-imino], polymer hindered amine light stabilizer, BASF, Chimassorb 944.

Hindered amine light stabilizer B: poly[1-(2’-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidinylsuccinate] (CAS: 65447-77-0), polymer hindered amine light stabilizer, light stabilizer 622, Wuhan Xinxin Jiali Biotechnology Co., Ltd.

Hindered amine light stabilizer C: polymer of N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,6-hexanediamine, 2,4,6-trichloro-1,3,5-triazine, N-butyl-1-butylamine and N-butyl-2,2,6,6-tetramethyl-4-piperidinamine, polymer hindered amine light stabilizer, light stabilizer UV2020, Nanjing Milan Chemical.

Hindered amine light stabilizer D: 1,2,3,4-butanetetracarboxylic acid tetrakis (1,2,2,6,6-pentamethyl-4-piperidinyl) ester (CAS: 91788-83-9), a low molecular weight hindered amine light stabilizer, Wuhan Xinxin Jiali Biotechnology Co., Ltd.

Hindered amine light stabilizer E: bis-2,2,6,6-tetramethylpiperidinol sebacate, low molecular weight hindered amine light stabilizer, BASF, Tinuvin770.

Hindered amine light stabilizer F: 2, 2, 6, 6-tetramethyl-4-piperidinyl stearate, low molecular weight hindered amine light stabilizer, UV3853, Nanjing Milan Chemical.

Diethylaluminum hypophosphite: OP1230, Clariant;

Calcium oxide: calcium oxide powder, Guangxi Baojia environmentally friendly building materials;

Ammonium aluminum sulfate: ammonium alum, Zibo Guangzheng Aluminum Salt Chemical;

Phenolic heat stabilizer: N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine, Irganox1098, BASF;

Thiosulfate antioxidants: distearyl thiodipropionate, antioxidant DSTP, Lianlong;

Other light stabilizers: [2-hydroxy-4-(octyloxy)phenyl]phenyl ketone, Guangzhou Kafen Biotechnology Co., Ltd., UV-531.

The preparation method of the low-acid halogen-free flame retardant is as follows: calcium oxide, water, ammonium aluminum sulfate, dialkyl aluminum hypophosphite, and hindered amine light stabilizer (or other light stabilizer) are weighed in parts by weight, the calcium oxide and ammonium aluminum sulfate are dissolved in water, the pH value is adjusted to 6.5-7 (or other pH value) with 8wt% dilute hydrochloric acid, the dialkyl aluminum hypophosphite and hindered amine light stabilizer are added, and the mixture is stirred for 1.5-2 hours while controlling the temperature at 60-90°C, and then allowed to stand for 10 hours, filtered, and dried to obtain the low-acid halogen-free flame retardant.

Preparation method of other low-acid halogen-free flame retardants (Comparative Example 6): Weigh 95 parts of dialkyl aluminum hypophosphite and 5 parts of hindered amine light stabilizer A in 60 parts of water, stir, add 5% sodium hydroxide aqueous solution dropwise to the pH value of 6.7, then let it stand for 10 hours, filter, and dry to obtain other low-acid halogen-free flame retardants.

Various test methods

(1) Flame retardancy: The UL94 test method is used to evaluate the flame retardancy of plastic materials. 1.6mm thick specimens are injection molded, fixed on a vertical test stand, and irradiated with flame for a certain period of time. The flame is then observed after spontaneous combustion, including the burning time, flame spread, and extinguishing of the sample. Based on the observation results, the sample will be divided into different grades, such as V0, V1, and V2, to describe the different levels of its flame retardancy.

(2) Oxygen transmission rate: The oxygen transmission rate of the coextruded film samples dried in vacuum was measured at room temperature under 50% relative humidity using an Oxtran 2/21 (Modern Control Inc., USA) instrument. The carrier gas was nitrogen and the ambient gas was 99.9% pure oxygen. The surface area analyzed was 50 square centimeters, and the oxygen transmission rate was recorded in cm ³ /(mil·day·100in ² ·atm). Generally, the industry believes that an oxygen transmission rate below 10 cm ³ /(mil·day·100in ² ·atm) is optimal, 8-20 cm ³ /(mil·day·100in ² ·atm) indicates good oxygen barrier properties, and a value greater than 20 cm ³ /(mil·day·100in ² ·atm indicates poor oxygen barrier properties.

(3) Content of dialkyl aluminum hypophosphite/hindered amine light stabilizer in low-acid halogen-free flame retardant: Use X-ray fluorescence spectrometer and elemental analyzer to determine the content of phosphorus and nitrogen respectively, and convert them into the content of dialkyl aluminum hypophosphite/hindered amine light stabilizer.

(4) Rubber contact corrosion: The sample is injection molded into a sample plate, and then two samples are sandwiched with silicone rubber and compressed with a rubber compression permanent deformation device. Refer to the test standard GB/T7759.1, fix the initial rubber deformation, the initial thickness is 5.7mm, and the thickness after compression is 2.5mm. Then, store it in a 120℃ oven for 1000 hours. Release the compressor to test the rubber gasket thickness h, and calculate the rebound ratio λ = (h-2.5)/(5.7-2.5)×100%. When the rebound rate is ≥65%, it means that the sample will not corrode the rubber. When the rebound rate is ≥45%, it means that the sample will corrode the rubber slightly. When the rebound rate is less than 45%, the sample is severely corrosive to the rubber.

(5) The test method for the pH value of low-acid halogen-free flame retardant is as follows: take 500 mg of low-acid halogen-free flame retardant, add 50 ml of deionized water, place it in an 80℃ ultrasonic water bath and stir it thoroughly for 15 minutes, take the mixed solution and add it to a centrifuge tube for high-speed centrifugation, and then test the pH value of the supernatant.

Table 1: Feeding amount (parts by weight), product ratio and pH of the preparation process of low-acid halogen-free flame retardant

A1 A2 A3 A4 A5 A6 A7 Amount of diethylaluminum hypophosphite 95.0 95.0 95.0 91.5 93.5 90.0 95.0 Types of Hindered Amine Light Stabilizers A A A A A A A Hindered amine light stabilizer addition amount 5.0 5.0 5.0 8.5 7.5 10.0 5.0 Calcium oxide addition 3.0 3.0 3.0 3.0 3.0 3.0 1.0 Water addition amount 60.0 60.0 60.0 60.0 60.0 60.0 40.0 Amount of ammonium aluminum sulfate added 2.0 2.0 2.0 2.0 2.0 2.0 1.0 Content of diethylaluminum hypophosphite in the product, % 94.9 95.0 95.0 91.5 93.5 90.0 95.0 Hindered amine light stabilizer content, % 5.1 5.0 5.0 8.5 7.5 10.0 5.0 PH 6.5 6.8 7.0 6.8 6.8 6.8 6.8

Continued Table 1:

A8 A9 A10 A11 A12 A13 Amount of diethylaluminum hypophosphite 95.0 95.0 95.0 95.0 95.0 95.0 Types of Hindered Amine Light Stabilizers A B C D E F Hindered amine light stabilizer addition amount 5.0 5.0 5.0 5.0 5.0 5.0 Calcium oxide addition 5.0 5.0 5.0 5.0 5.0 5.0 Water addition amount 98.0 98.0 98.0 98.0 98.0 98.0 Amount of ammonium aluminum sulfate added 5.0 5.0 5.0 5.0 5.0 5.0 Content of diethylaluminum hypophosphite in the product, % 94.9 95.0 95.0 94.9 95.0 95.0 Hindered amine light stabilizer content, % 5.1 5.0 5.0 5.1 5.0 5.0 PH 6.8 6.8 6.8 6.8 6.8 6.8

Table 2: Feeding amount (parts by weight), product ratio and pH of other low-acid halogen-free flame retardant preparation processes

B1 B2 B3 B4 B5 Amount of diethylaluminum hypophosphite 95.0 95.0 95.0 100 95.0 Types of Hindered Amine Light Stabilizers A A A Other light stabilizers 5.0 Hindered amine light stabilizer addition amount 5.0 5.0 5.0 Calcium oxide addition 3.0 3.0 3.0 3.0 3.0 Water addition amount 60.0 60.0 60.0 60.0 60.0 Amount of ammonium aluminum sulfate added 2.0 2.0 2.0 2.0 Content of diethylaluminum hypophosphite in the product, % 95.0 95.0 94.9 100 95.0 Light stabilizer content, % 5.0 5.0 5.1 5.0 PH 6.8 6.2 7.2 6.8 6.8

The preparation method of the flame retardant polyamide composite material is: the components are mixed evenly, and granulated by extrusion through a twin-screw extruder, the screw temperatures are set to 170°C in zone one, 190°C in zone two, 230°C in zone three, 260°C in zone four, 280°C in zone five, 280°C in zone six, 280°C in zone seven, 260°C in zone eight, and 260°C in zone nine, and the rotation speed is 500 r/min.

Table 3: Content (parts by weight) of each component of flame-retardant polyamide composite materials of Examples 1-6 and test results

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 PA56 60 60 60 60 PA6 60 PA66/6T 60 Types of low acid halogen-free flame retardants A1 A1 A1 A2 A3 A4 Low acidity halogen-free flame retardant content 25 25 25 25 25 25 Phenolic heat stabilizers 0.5 0.5 0.5 0.5 0.5 0.5 Thiosulfate antioxidants 0.3 0.3 0.3 0.3 0.3 0.3 flame retardancy V0 V0 V0 V0 V0 V0 Oxygen transmission rate, cm ³ /(mil·day·100in ² ·atm) 7 6 8 7 8 9 Rubber rebound, % 68 72 69 65 68 73

It can be seen from Examples 1-15 that the flame-retardant polyamide composite material modified with the low-acidity halogen-free flame retardant of the present application has low oxygen permeability and low rubber contact corrosion.

Table 4: Content (parts by weight) of each component in flame-retardant polyamide composite materials of Examples 7-12 and test results

Example 7 Example 8 Example 9 Example 10 Example 11 Example 12 PA56 60 60 60 60 60 60 Types of low acid halogen-free flame retardants A5 A6 A7 A8 A9 A10 Low acidity halogen-free flame retardant content 25 25 25 25 25 25 Phenolic heat stabilizers 0.5 0.5 0.5 0.5 0.5 0.5 Thiosulfate antioxidants 0.3 0.3 0.3 0.3 0.3 0.3 flame retardancy V0 V0 V0 V0 V0 V0 Oxygen transmission rate, cm ³ /(mil·day·100in ² ·atm) 8 9 7 9 8 11 Rubber rebound, % 66 70 65 69 71 66

Table 5: Content (parts by weight) of each component in the flame-retardant polyamide composite materials of Examples 13/14 and Comparative Examples 1-5 and their test results

Example 13 Example 14 Example 15 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 PA56 60 60 60 60 60 60 60 60 Types of low acid halogen-free flame retardants A11 A12 A13 B1 B2 B3 B4 B5 Low acidity halogen-free flame retardant content 25 25 25 25 25 25 25 25 Phenolic heat stabilizers 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Thiosulfate antioxidants 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 flame retardancy V0 V0 V0 V1 V1 V1 V1 V0 Oxygen transmission rate, cm ³ /(mil·day·100in ² ·atm) 12 14 17 29 32 25 27 20 Rubber rebound, % 63 51 57 42 34 46 38 43

It can be seen from Examples 10-15 that the preferred hindered amine light stabilizer in the low-acid halogen-free flame retardant is preferably a polymer type, and further the polymer hindered amine light stabilizer is selected from poly-{[6-[(1,1,3,3-tetramethylbutyl)-imino]-1,3,5-triazine-2,4-diyl][2-(2,2,6,6-tetramethylpiperidinyl)-amino]-hexamethylene-[4-(2,2,6,6-tetramethylpiperidinyl)-imino], poly[1-(2'-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidinyl succinate].

The flame-retardant polyamide composite material has an oxygen permeability lower than 20 cm ³ /(mil·day·100in ² ·atm), and rubber rebound resilience greater than 50%.

It can be seen from Comparative Example 1 that if the buffer system composed of ammonium aluminum sulfate is not included in the modification process of the low-acidity halogen-free flame retardant, the oxygen barrier property and the corrosion resistance to rubber of the flame-retardant polyamide composite material cannot be effectively improved.

It can be seen from Comparative Examples 2/3 that if the pH of the low-acid halogen-free flame retardant is not within the range of the present invention, the oxygen barrier property and the corrosion resistance to rubber of the flame-retardant polyamide composite material cannot be effectively improved.

It can be seen from Comparative Example 4 that if the low-acid halogen-free flame retardant does not contain the light stabilizer defined in the present invention, the oxygen permeability and the corrosion resistance to rubber cannot be improved.

It can be seen from Comparative Example 5 that if other types of light stabilizers are added to the low-acid halogen-free flame retardant, the oxygen permeability and the corrosiveness to rubber cannot be effectively improved.

Table 6: Content of each component (parts by weight) and test results of flame retardant polyamide composite materials of Comparative Examples 6-8

Comparative Example 6 Comparative Example 7 Comparative Example 8 PA56 60 60 60 Other low-acid halogen-free flame retardants 25 Diethylaluminum hypophosphite 23.7 Hindered Amine Light Stabilizer A 1.3 Phenolic heat stabilizers 0.5 0.5 0.5 Thiosulfate antioxidants 0.3 0.3 0.3 flame retardancy V2 V0 HB Oxygen transmission rate, cm ³ /(mil·day·100in ² ·atm) 26 35 19 Rubber rebound, % 41 33 65

It can be seen from Comparative Example 6 that if there is no buffer system in the process of adjusting the pH of diethylaluminum hypophosphite, even if the pH is adjusted to within the range of the present invention, good technical effects cannot be obtained.

Comparative Example 7 shows that when only diethyl aluminum hypophosphite and hindered amine light stabilizer A are added to the flame-retardant polyamide composite material, the strong acidity of diethyl aluminum hypophosphite will seriously corrode the resin matrix, resulting in a high oxygen permeability and strong corrosion to rubber.

It can be seen from Comparative Example 8 and all the examples that the flame-retardant polyamide composite material to which the low-acid halogen-free flame retardant of the present application is added not only reduces the oxygen permeability, but also improves the corrosion of traditional diethyl aluminum hypophosphite to rubber.

Claims (10)

A low-acid halogen-free flame retardant, characterized in that it comprises the following components in parts by weight: Dialkyl aluminum hypophosphite 89-96 parts, Hindered amine light stabilizer 5-10 parts, The pH value of the low-acid halogen-free flame retardant is 6.5-7. The low-acid halogen-free flame retardant according to claim 1 is characterized in that the testing method for the pH value of the low-acid halogen-free flame retardant is: take 500 mg of low-acid halogen-free flame retardant, add 50 ml of deionized water, place it in an 80°C ultrasonic water bath and stir it thoroughly for 15 minutes, take the mixed solution and add it to a centrifuge tube for high-speed centrifugation, and then test the pH value of the supernatant. The low-acid halogen-free flame retardant according to claim 1 is characterized in that the dialkyl aluminum hypophosphite is selected from diethyl aluminum hypophosphite. The low-acid halogen-free flame retardant according to claim 1 is characterized in that the hindered amine light stabilizer is selected from at least one of a polymer hindered amine light stabilizer and a low molecular weight hindered amine light stabilizer; the polymer hindered amine light stabilizer is selected from 1,5,8,12-tetrakis[4,6-bis(N-butyl-N-1,2,2,6,6-pentamethyl-4-piperidinylamino)-1,3,5-triazine-2-yl]-1,5,8,12-tetraazadodecane , poly-{[6-[(1,1,3,3-tetramethylbutyl)-imino]-1,3,5-triazine-2,4-diyl][2-(2,2,6,6-tetramethylpiperidinyl)-amino]-hexylene-[4-(2,2,6,6-tetramethylpiperidinyl)-imino], poly[1-(2'-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidinyl succinate], 1,2,3,4-butanetetracarboxylic acid tetra(1,2,2,6,6- ester, N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,6-hexanediamine and 2,4,6-trichloro-1,3,5-triazine and N-butyl-1-butylamine and N-butyl-2,2,6,6-tetramethyl-4-piperidinamine polymer, poly{(6-morpholinyl-5-triazine-2,4-diyl)(2,2,6,6-tetramethylpiperidinyl)iminohexamethylene[(2,2,6,6-tetramethyl The low molecular hindered amine light stabilizer is selected from at least one of bis-2,2,6,6-tetramethylpiperidinol sebacate, N,N'-diformyl-N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-hexamethylenediamine, 1,2,3,4-butanetetracarboxylic acid tetra(1,2,2,6,6-pentamethyl-4-piperidinyl) ester, and 2,2,6,6-tetramethyl-4-piperidinyl stearate. The low-acid halogen-free flame retardant according to claim 4 is characterized in that the hindered amine light stabilizer is selected from a polymer hindered amine light stabilizer; preferably, the polymer hindered amine light stabilizer is selected from at least one of poly-{[6-[(1,1,3,3-tetramethylbutyl)-imino]-1,3,5-triazine-2,4-diyl][2-(2,2,6,6-tetramethylpiperidinyl)-amino]-hexamethylene-[4-(2,2,6,6-tetramethylpiperidine)-imino], poly[1-(2’-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidinyl succinate]. The preparation method of the low-acid halogen-free flame retardant according to any one of claims 1-5 is characterized in that it includes the following steps: weighing 1-5 parts of calcium oxide, 40-98 parts of water, 1-5 parts of ammonium aluminum sulfate, 90-95 parts of dialkyl aluminum hypophosphite, and 5-10 parts of hindered amine light stabilizer in parts by weight, dissolving the calcium oxide and ammonium aluminum sulfate in water, adjusting the pH value to 6.5-7 with 5-15wt% dilute hydrochloric acid, then adding dialkyl aluminum hypophosphite and hindered amine light stabilizer, stirring for 0.5-3 hours, controlling the temperature at 60~90°C, then standing for 5-15 hours, filtering, and drying to obtain the low-acid halogen-free flame retardant. A flame-retardant polyamide composite material, characterized in that it comprises the following components, measured in parts by weight: 30-80 parts of a polyamide resin and 20-40 parts of the low-acid halogen-free flame retardant according to any one of claims 1 to 5. The flame-retardant polyamide composite material according to claim 7 is characterized in that the polyamide resin is selected from at least one of aliphatic polyamide resin, semi-aromatic polyamide resin, and polylactamide resin. The flame-retardant polyamide composite material according to claim 7 is characterized in that it further comprises 0-1 parts of heat stabilizer by weight, and the heat stabilizer is selected from phenolic heat stabilizers and thiosulfate antioxidants. The application of the flame-retardant polyamide composite material according to any one of claims 7 to 9 is characterized in that it is used to prepare electronic and electrical components that come into contact with rubber and automotive accessories that come into contact with rubber.