A low-acidity halogen-free flame retardant, a preparation method thereof, and a flame-retardant polyamide composite and application

Abstract

The application discloses a low-acidity halogen-free flame retardant, which comprises the following components in parts by weight: 89-96 parts of aluminum dialkyl hypophosphite, and 5-10 parts of hindered amine light stabilizer, wherein the low-acidity halogen-free flame retardant has a pH value of 6.5-7. The low-acidity halogen-free flame retardant can improve the corrosion of the flame retardant to a resin matrix, improve the flame retardant performance and oxygen insulation, and reduce the corrosion to rubber when the low-acidity halogen-free flame retardant is applied to a polyamide composition by reducing the acidity of the halogen-free flame retardant and containing the specific content of the hindered amine light stabilizer.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a low-acid, halogen-free flame retardant and its preparation method, a flame-retardant polyamide composite material and its application. Background Technology

[0002] Hypophosphite flame retardants have a high phosphorus content and can be used as flame retardants or flame retardant synergists. However, they also have drawbacks, namely strong acidity, which can cause degradation of polymer materials, corrosion of equipment, and migration and precipitation. These problems limit their use as flame retardants. In particular, polyamide resins are significantly affected by acidic components. Therefore, how to reduce the acidity of materials without affecting their flame retardant properties, thereby effectively reducing material corrosion, has significant economic value.

[0003] Meanwhile, the applicant's experiments revealed that the addition of commercially available aluminum dialkylphosphite flame retardants significantly reduces the oxygen barrier properties of polyamide composites, accelerates the internal oxidation process of the material, and shortens its service life, thus reducing the application of polyamide composites in the electronics, power tools, and automotive fields. Furthermore, commercially available aluminum dialkylphosphite flame retardants also make polyamide composites corrosive to the rubber materials they come into contact with, affecting their application in new energy vehicle components (such as connectors and plugs).

[0004] However, there are no reports on methods to improve the aforementioned defects in existing technologies. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned 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 its preparation method and application.

[0006] This invention is achieved through the following technical solution:

[0007] A low-acid, halogen-free flame retardant, comprising the following components by weight:

[0008] 89-96 parts of dialkyl aluminum hypophosphite,

[0009] 5-10 parts of hindered amine light stabilizer

[0010] The pH value of the low-acid halogen-free flame retardant is 6.5-7.

[0011] The pH test method for 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 thoroughly for 15 min. Take the mixed solution and add it to a centrifuge tube for high-speed centrifugation, and then test the pH value of the supernatant.

[0012] The dialkyl aluminum hypophosphite is selected from diethyl aluminum hypophosphite.

[0013] The hindered amine light stabilizer is selected from at least one of high molecular weight hindered amine light stabilizers and low molecular weight hindered amine light stabilizers; the high molecular weight hindered amine light stabilizer is selected from at least one of the following substances:

[0014] 1,5,8,12-Tetra[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),

[0015] Poly-{[6-[(1,1,3,3-tetramethylbutyl)-imino]-1,3,5-triazine-2,4-diyl][2-(2,2,6,6-tetramethylpiperidinyl)-amino]-hexene-[4-(2,2,6,6-tetramethylpiperidinyl)-imino](CAS: 70624-18-9),

[0016] Poly[1-(2'-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidine succinate] (CAS: 65447-77-0),

[0017] 1,2,3,4-Butanetetracarboxylic acid tetra(1,2,2,6,6-pentamethyl-4-piperidinyl) ester (CAS: 91788-83-9)(LA-52),

[0018] Polymers of 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 (CAS: 192268-64-7)

[0019] Poly{(6-morpholino-5-triazine-2,4-diyl)(2,2,6,6-tetramethylpiperidinyl)iminohexamethylene[(2,2,6,6-tetramethylpiperidinyl)-imino]} (CAS: 82451-48-7).

[0020] The low-molecular-weight hindered amine light stabilizer is selected from at least one of the following substances:

[0021] Bis-2,2,6,6-Tetramethylpiperidinol sebacic acid (CAS: 52829-07-9)

[0022] N,N'-Dicarboxylo-N,N'-Di(2,2,6,6-tetramethyl-4-piperidine)-hexamethylenediamine (CAS: 124172-53-8)

[0023] 1,2,3,4-Butanetetracarboxylic acid tetra(1,2,2,6,6-pentamethyl-4-piperidinyl) ester (CAS: 91788-83-9),

[0024] 2,2,6,6-Tetramethyl-4-piperidinyl stearate (CAS: 167078-06-0).

[0025] Preferably, the hindered amine light stabilizer is selected from polymeric hindered amine light stabilizers; more preferably, the polymeric 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]-hexylene-[4-(2,2,6,6-tetramethylpiperidin)-imino] and poly[1-(2'-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidin succinate].

[0026] The preparation method of the low-acid halogen-free flame retardant of the present invention includes the following steps: Weigh 1-5 parts by weight of calcium oxide, 40-98 parts by weight of water, 1-5 parts by weight of ammonium aluminum sulfate, 90-95 parts by weight of aluminum dialkylphosphite, and 5-10 parts by weight of hindered amine light stabilizer. Dissolve the calcium oxide and ammonium aluminum sulfate in water, adjust the pH value to 6.5-7 with 5-15 wt% dilute hydrochloric acid, then add the aluminum dialkylphosphite and hindered amine light stabilizer, stir for 0.5-3 hours while controlling the temperature at 60-90℃, then let stand for 5-15 hours, filter, and dry to obtain the low-acid halogen-free flame retardant. The pH value of the tested product is 6.5-7. This application can adjust the pH value to 6.5-7 using 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 feed. 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, and then the ratio of dialkyl aluminum hypophosphite and hindered amine light stabilizer is obtained.

[0027] The present invention also discloses a flame-retardant polyamide composite material, which, by weight, comprises the following components: 30-80 parts of polyamide resin and 20-40 parts of the low-acid halogen-free flame retardant of the present invention.

[0028] The polyamide resin is selected from at least one of aliphatic polyamide resin, semi-aromatic polyamide resin, and polylactam resin.

[0029] 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, etc.

[0030] The semi-aromatic polyamide is selected from PA MXD6, PA10T, PA10T1010, PA10T66, PA6T, PA6T66, PA9T, etc.

[0031] The polylactam is selected from PA5, PA6, PA11, PA12, etc.

[0032] The relative viscosity range of the polyamide resin suitable for this invention is 1.8-3.8. The test method for polyamide viscosity refers to GB12006.1-89. Specifically, the test method is to measure the relative viscosity of polyamide with a concentration of 0.25 g / dl in 98% concentrated sulfuric acid at 25±0.01℃.

[0033] The product also includes 0-1 parts by weight of heat stabilizer, wherein the heat stabilizer is selected from phenolic heat stabilizers and thiosulfate antioxidants.

[0034] The flame-retardant polyamide composite material may also contain 0-30 parts of filler, such as talc, glass fiber, etc.

[0035] The flame-retardant polyamide composite material is used to manufacture electronic and electrical components that come into contact with rubber, as well as automotive accessories that come into contact with rubber, such as connectors and plugs.

[0036] 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, and carbon fiber.

[0037] The preparation method of flame-retardant polyamide composite material is as follows: the components are mixed evenly and then extruded and granulated by a twin-screw extruder. The screw temperature range is 170-300℃ and the rotation speed is 400-600r / min.

[0038] The present invention has the following beneficial effects:

[0039] This invention utilizes 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 weakly acidic state. Furthermore, the buffer system of this invention provides a longer-lasting pH adjustment, addressing pH fluctuations over extended periods. Additionally, the addition of a specific amount of hindered amine light stabilizer during the preparation process significantly enhances flame retardancy, oxygen barrier properties of the polyamide composite material, and reduces the corrosiveness of the polyamide composite material to rubber. Detailed Implementation

[0040] 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. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0041] The raw materials used in this invention are sourced from the following sources:

[0042] PA56: ECOPENT1273, relative viscosity 2.3, Shandong Kaisai;

[0043] PA6: HY-2500A, relative viscosity 2.4, Jiangsu Haiyang Chemical Fiber;

[0044] PA66 / 6T: C1504T, relative viscosity 2.6, purchased from Shandong Guangyin;

[0045] 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]-hexylene-[4-(2,2,6,6-tetramethylpiperidinyl)-imino], high molecular weight hindered amine light stabilizer, BASF, Chimassorb 944.

[0046] Hindered amine light stabilizer B: Poly[1-(2'-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidine succinate] (CAS: 65447-77-0), high molecular weight hindered amine light stabilizer, light stabilizer 622, Wuhan Xinxin Jiali Biotechnology Co., Ltd.;

[0047] Hindered amine light stabilizer C: a 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, a high molecular weight hindered amine light stabilizer, light stabilizer UV2020, Nanjing Milan Chemical.

[0048] Hindered amine light stabilizer D: tetra(1,2,2,6,6-pentamethyl-4-piperidinyl) ester of 1,2,3,4-butanediol (CAS: 91788-83-9), a low molecular weight hindered amine light stabilizer, manufactured by Wuhan Xinxin Jiali Biotechnology Co., Ltd.

[0049] Hindered amine light stabilizer E: bis-2,2,6,6-tetramethylpiperidinol sebacate, low molecular weight hindered amine light stabilizer, BASF, Tinuvin 770.

[0050] Hindered amine light stabilizer F: 2,2,6,6-tetramethyl-4-piperidine stearate, low molecular weight hindered amine light stabilizer, UV3853, Nanjing Milan Chemical.

[0051] Diethylaluminum hypophosphite: OP1230, Clariant;

[0052] Calcium oxide: Calcium oxide powder, Guangxi Baojia Environmental Building Materials;

[0053] Ammonium aluminum sulfate: Ammonium alum, Zibo Guangzheng Aluminum Salt Chemical Co., Ltd.

[0054] Phenolic heat stabilizers: N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine, Irganox 1098, BASF;

[0055] Thiosulfate antioxidants: dioctadecyl thiodipropionate, antioxidant DSTP, and Rianon;

[0056] Other light stabilizers: [2-hydroxy-4-(octoxy)phenyl]phenyl ketone, Guangzhou Kafen Biotechnology Co., Ltd., UV-531.

[0057] Preparation method of low acid halogen-free flame retardant: Weigh calcium oxide, water, aluminum ammonium sulfate, dialkyl aluminum hypophosphite, and hindered amine light stabilizer (or other light stabilizer) by weight. Dissolve calcium oxide and aluminum ammonium sulfate in water, adjust the pH value to 6.5-7 (or other pH value) with 8wt% dilute hydrochloric acid, then add dialkyl aluminum hypophosphite and hindered amine light stabilizer, stir for 1.5-2 hours, control the temperature at 60-90℃ during the process, then let stand for 10 hours, filter, and dry to obtain low acid halogen-free flame retardant.

[0058] 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 and stir in 60 parts of water. Add 5% sodium hydroxide aqueous solution dropwise until the pH value is 6.7. Then let stand for 10 hours, filter, and dry to obtain other low-acid halogen-free flame retardants.

[0059] Various test methods

[0060] (1) Flame retardancy: The UL94 test method is used to evaluate the flame retardancy of plastic materials. A 1.6 mm thick sample is injection molded, fixed on a vertical test frame, and irradiated with a flame for a certain period of time. The situation after spontaneous combustion is then observed, including the burning time, flame spread, and extinguishing of the sample. Based on the observation results, the sample will be classified into different grades, such as V0, V1, and V2, to describe different levels of its flame retardancy performance.

[0061] (2) Oxygen Transmission Rate: The oxygen transmission rate of the vacuum-dried co-extruded film samples was measured at room temperature using an Oxtran 2 / 21 (Modern Control Inc., USA) instrument under 50% relative humidity. Nitrogen was used as the carrier gas, and 99.9% pure oxygen was used as the ambient gas. The surface area analyzed was 50 square centimeters, and the oxygen transmission rate was recorded in cm². 3 / (mil·day·100in 2 • atm). Generally, the industry considers an oxygen permeability of less than 10 cm³ to be acceptable. 3 / (mil·day·100in 2 The optimal time is 8-20 cm (atm). 3 / (mil·day·100in 2 It has good oxygen barrier properties at · atm, greater than 20cm 3 / (mil·day·100in 2 A reading of ·atm indicates poor oxygen barrier properties.

[0062] (3) Content of dialkyl aluminum hypophosphite / hindered amine light stabilizer in low acid halogen-free flame retardant: The contents of phosphorus and nitrogen were determined by X-ray fluorescence spectrometer and elemental analyzer, and converted into the contents of dialkyl aluminum hypophosphite / hindered amine light stabilizer.

[0063] (4) Rubber contact corrosion: The sample is injection molded into a template, and then silicone rubber is sandwiched between two templates and compressed and fixed with a rubber compression setter. Referring to the test standard GB / T7759.1, the initial rubber deformation is fixed, the initial thickness is 5.7 mm, and the thickness after compression is 2.5 mm. Then it is stored in an oven at 120℃ for 1000 hours. After releasing the compressor, the thickness h of the rubber gasket is tested, and the rebound ratio λ = (h-2.5) / (5.7-2.5)×100% is calculated. 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.

[0064] (5) The pH test method for 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 thoroughly for 15 min, take the mixed solution and add it to a centrifuge tube for high-speed centrifugation, and then test the pH value of the supernatant.

[0065] Table 1: Feeding amount (parts by weight), product ratio and pH of low-acid halogen-free flame retardant preparation process

[0066] A1 A2 A3 A4 A5 A6 A7 Diethylaluminum hypophosphite feed amount 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 amount 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 Aluminum ammonium sulfate addition amount 2.0 2.0 2.0 2.0 2.0 2.0 1.0 The product contains % diethylaluminum hypophosphite. 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

[0067] Continued from Table 1:

[0068] A8 A9 A10 A11 A12 A13 Diethylaluminum hypophosphite feed amount 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 amount 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 Aluminum ammonium sulfate addition amount 5.0 5.0 5.0 5.0 5.0 5.0 The product contains % diethylaluminum hypophosphite. 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

[0069] Table 2: Feeding amounts (parts by weight), product ratios, and pH values ​​for other low-acid halogen-free flame retardant preparation processes

[0070] B1 B2 B3 B4 B5 Diethylaluminum hypophosphite feed amount 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 amount 3.0 3.0 3.0 3.0 3.0 Water addition amount 60.0 60.0 60.0 60.0 60.0 Aluminum ammonium sulfate addition amount 2.0 2.0 2.0 2.0 The product contains % diethylaluminum hypophosphite. 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

[0071] The preparation method of flame-retardant polyamide composite material is as follows: the components are mixed evenly and extruded and granulated by a twin-screw extruder. The screw temperature is set to 170℃ in zone 1, 190℃ in zone 2, 230℃ in zone 3, 260℃ in zone 4, 280℃ in zone 5, 280℃ in zone 6, 280℃ in zone 7, 260℃ in zone 8, and 260℃ in zone 9, and the rotation speed is 500r / min.

[0072] Table 3: Content (parts by weight) and test results of each component in the flame-retardant polyamide composites of Examples 1-6

[0073] 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 acid 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 <![CDATA[Oxygen transmission rate, cm 3 / (mil·day·100 in 2 ·atm)]]> 7 6 8 7 8 9 Rubber resilience, % 68 72 69 65 68 73

[0074] As can be seen from Examples 1-15, the flame-retardant polyamide composite material modified with low-acid halogen-free flame retardant of this application has low oxygen permeability and low rubber contact corrosion.

[0075] Table 4: Content (parts by weight) of each component and test results of flame-retardant polyamide composites in Examples 7-12

[0076] 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 acid 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 <![CDATA[Oxygen Transmission Rate, cm 3 / (mil·day·100in 2 ·atm)]]> 8 9 7 9 8 11 Rubber resilience, % 66 70 65 69 71 66

[0077] Table 5: Component content (parts by weight) and test results of flame-retardant polyamide composites in Examples 13 / 14 and Comparative Examples 1-5

[0078] 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 acid 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 <![CDATA[Oxygen transmission rate, cm 3 / (mil·day·100in 2 ·atm)]]> 12 14 17 29 32 25 27 20 Rubber resilience, % 63 51 57 42 34 46 38 43

[0079] As can be seen from Examples 10-15, the preferred hindered amine light stabilizer in the low-acid halogen-free flame retardant is preferably a polymeric type, and the polymeric hindered amine light stabilizer is further selected from 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-tetramethylpiperidin)-imino], poly[1-(2'-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidin succinate].

[0080] The oxygen permeability of the flame-retardant polyamide composite material of the present invention is less than 20 cm. 3 / (mil·day·100in 2 (atm), and the rubber resilience is >50%.

[0081] As shown in Comparative Example 1, if the buffer system composed of ammonium aluminum sulfate is not included in the modification process of low-acid halogen-free flame retardants, the oxygen barrier properties and the corrosiveness to rubber of flame-retardant polyamide composites cannot be effectively improved.

[0082] As can be seen from Comparative Example 2 / 3, if the pH of the low-acid halogen-free flame retardant is not within the range of the present invention, it cannot effectively improve the oxygen barrier properties and the corrosiveness to rubber of the flame-retardant polyamide composite material.

[0083] As can be seen from Comparative Example 4, if the low-acid halogen-free flame retardant does not contain the light stabilizer specified in this invention, it cannot improve oxygen permeability and corrosivity to rubber.

[0084] As shown in Comparative Example 5, if other types of light stabilizers are added to the low-acid halogen-free flame retardant, it will not be able to effectively improve oxygen permeability and the corrosiveness to rubber.

[0085] Table 6: Content (parts by weight) of each component and test results of flame-retardant polyamide composites of Comparative Examples 6-8

[0086] Comparative Example 6 Comparative Example 7 Comparative Example 8 PA56 60 60 60 Other low-acid halogen-free flame retardants 25 Aluminum diethylphosphite 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 <![CDATA[Oxygen transmission rate, cm 3 / (mil·day·100in 2 ·atm)]]> 26 35 19 Rubber resilience, % 41 33 65

[0087] As can be seen from Comparative Example 6, if there is no buffer system in the process of adjusting the pH of diethylaluminum hypophosphite, even if the pH is adjusted to the range of the present invention, good technical results cannot be obtained.

[0088] As can be seen from Comparative Example 7, when 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 severely corrode the resin matrix, resulting in high oxygen permeability and strong corrosiveness to rubber.

[0089] As can be seen from Comparative Example 8 and all embodiments, the flame-retardant polyamide composite material with added low-acid halogen-free flame retardant of this application not only reduces oxygen permeability, but also improves the corrosion of rubber by traditional diethyl aluminum hypophosphite.

Claims

1. A low-acid, halogen-free flame retardant, characterized in that, By weight, it includes the following components: 89-96 parts of dialkyl aluminum hypophosphite, 5-10 parts of hindered amine light stabilizer The pH value of the low-acid halogen-free flame retardant is 6.5-7; The preparation method of the low-acid halogen-free flame retardant includes the following steps: Weigh 1-5 parts of calcium oxide, 40-98 parts of water, 1-5 parts of ammonium aluminum sulfate, 90-95 parts of aluminum dialkylphosphite, and 5-10 parts of hindered amine light stabilizer by weight. Dissolve the calcium oxide and ammonium aluminum sulfate in water, adjust the pH value to 6.5-7 with 5-15 wt% dilute hydrochloric acid, add aluminum dialkylphosphite and hindered amine light stabilizer, stir for 0.5-3 hours, control the temperature at 60-90℃ during the process, let stand for 5-15 hours, filter, and dry to obtain the low-acid halogen-free flame retardant.

2. The low-acidity halogen-free flame retardant according to claim 1, characterized in that, The pH test method for 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 thoroughly for 15 min. Add the mixed solution to a centrifuge tube and centrifuge at high speed. Then test the pH value of the supernatant.

3. The low-acid, halogen-free flame retardant according to claim 1, characterized in that, The dialkyl aluminum hypophosphite is selected from diethyl aluminum hypophosphite.

4. The low-acid, halogen-free flame retardant according to claim 1, characterized in that, The hindered amine light stabilizer is selected from at least one of high molecular weight hindered amine light stabilizers and low molecular weight hindered amine light stabilizers; the high molecular weight hindered amine light stabilizer is selected from 1,5,8,12-tetra[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, poly-{[6-[(1,1,3,3-tetramethyl [Butyl)-imino]-1,3,5-triazine-2,4-diyl][2-(2,2,6,6-tetramethylpiperidinyl)-amino]-hexene-[4-(2,2,6,6-tetramethylpiperidinyl)-imino], poly[1-(2'-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidinyl succinate], 1,2,3,4-butanetracarboxylic acid tetra(1,2,2,6,6-pentamethyl-4-piperidinyl) ester, N Polymers of 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-piperidinylamine, poly{(6-morpholino-5-triazine-2,4-diyl)(2,2,6,6-tetramethylpiperidinyl)imino-hexamethylene[(2,2,6,6-tetramethylpiperidinyl)-imino-hexamethylene[(2,2,6,6-tetramethylpiperidinyl)-imino-hexamethylene] At least one of the following groups: [amine group]; the low molecular weight hindered amine light stabilizer is selected from at least one of the following groups: bis-2,2,6,6-tetramethylpiperidinol sebacate, N,N'-dicarboxylo-N,N'-bis(2,2,6,6-tetramethyl-4-piperidin)-hexamethylenediamine, tetra(1,2,2,6,6-pentamethyl-4-piperidinyl) ester of 1,2,3,4-butanediol tetracarboxylate, and 2,2,6,6-tetramethyl-4-piperidinyl stearate.

5. The low-acid, halogen-free flame retardant according to claim 4, characterized in that, The hindered amine light stabilizer is selected from high molecular weight hindered amine light stabilizers.

6. The low-acidity halogen-free flame retardant according to claim 5, characterized in that... The 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]-hexylene-[4-(2,2,6,6-tetramethylpiperidin)-imino] and poly[1-(2'-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidin succinate].

7. A flame-retardant polyamide composite material, characterized in that, The product comprises, by weight, the following components: 30-80 parts of polyamide resin and 20-40 parts of the low-acid, halogen-free flame retardant as described in any one of claims 1-6.

8. The flame-retardant polyamide composite material according to claim 7, characterized in that, The polyamide resin is selected from at least one of aliphatic polyamide resin, semi-aromatic polyamide resin, and polylactam resin.

9. The flame-retardant polyamide composite material according to claim 7, characterized in that, The product also includes 0-1 parts by weight of heat stabilizer, wherein the heat stabilizer is selected from phenolic heat stabilizers and thiosulfate antioxidants.

10. The application of the flame-retardant polyamide composite material according to any one of claims 7-9, characterized in that, Used for manufacturing electronic and electrical components that come into contact with rubber, and automotive accessories that come into contact with rubber.