A polyamide resin composition and preparation method thereof

Abstract

The present invention belongs to the technical field of polymer materials, and in particular to a polyamide resin composition and a preparation method thereof. The polyamide resin composition of the present invention, by weight, its raw materials include: 100 parts of polyamide resins, 5 to 10 parts of inorganic fillers, 1 to 5 parts of antioxidants, 1 to 3 parts of coupling agents, 1 to 5 parts of flame retardants A, 1 to 3 parts of promoters, and 10 to 15 parts of diluents. The polyamide resin composition prepared by the present invention has excellent mechanical properties and flame retardant properties, and the addition amount of flame retardant A is relatively low. When its addition amount is 2 4wt%, a flame retardant grade of UL 94 V 0 is achieved, and LOI values ​​are as high as 38%, and their anti-dripping performance is excellent, and dripping ignition phenomenon will not be caused.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and in particular relates to a polyamide resin composition and a preparation method thereof. Background Art

[0002] Polyamide (PA), commonly known as nylon, possesses excellent electrical and mechanical properties, as well as resistance to wear, oil, solvents, and corrosion. Because the amino and carboxyl groups at the ends of the polyamide backbone provide a certain degree of reactivity, its inherent drawbacks, such as high water absorption and flammability, can be physically and chemically modified through methods such as segmentation, grafting, blending, reinforcement, and filling. Since its industrialization, polyamide has been widely used in the automotive, electronics, machinery, and aviation industries, generating significant demand and becoming an indispensable structural material in the industrial sector.

[0003] As a polymer material, polyamide's flammability is a significant drawback. Furthermore, polyamide burns quickly and releases a high amount of heat. This produces large amounts of flaming droplets during combustion, increasing the risk of fire spread. Currently, the flame retardancy of polyamide is primarily modified by adding flame retardants. These flame retardants can be categorized into three main groups based on their composition: inorganic, organic, and inorganic-organic hybrids. Inorganic flame retardants primarily include aluminum hydroxide, magnesium hydroxide, antimony oxide, and silicon-based compounds; organic flame retardants primarily consist of organic compounds containing halogens, phosphorus, nitrogen, and silicon. Flame retardants can also be divided into two main groups based on their relationship with the target material: additive and reactive. Additive flame retardants are physically dispersed within the polymer matrix, requiring high addition levels to achieve their flame retardant effect. Furthermore, their poor compatibility with the polymer matrix can lead to reduced physical properties. Reactive flame retardants participate in polymer polymerization reactions as reactive monomers or auxiliary reagents, embedding effective flame retardant components into the macromolecular chain. Their unique characteristics prevent volatilization, dissolution, and migration of the flame retardant within the polymer matrix, rendering the polymer inherently flame retardant without the need for additional flame retardant treatment. Flame retardants are generally classified into halogen-based, halogen-phosphorus-based, organophosphorus-based, inorganic phosphorus-based, nitrogen-based, silicon-based, and boron-based flame retardants, depending on the elements they contain.

[0004] Polyamide resin, due to its excellent overall performance, is one of the most widely used engineering plastics. However, its flammability also poses a potential fire hazard. Furthermore, polyamide resins are used in demanding environments, such as high temperature, high humidity, and high voltage, making flame retardancy crucial. Currently, halogenated flame retardants, the most widely used and most effective in polyamide resins, are being phased out due to the increased release of toxic fumes. Therefore, there is an urgent need to develop polyamide resin compositions that exhibit both effective flame retardancy and mechanical properties. Summary of the Invention

[0005] The main purpose of the present invention is to provide a polyamide resin composition and a preparation method thereof, so as to solve the existing problems such as toxic flame retardants and poor flame retardant properties.

[0006] A polyamide resin composition comprising the following raw materials by weight:

[0007] 100 parts of polyamide resin

[0008] 5~10 parts of inorganic filler

[0009] 1-5 parts antioxidant

[0010] 1~3 parts coupling agent

[0011] Flame retardant A1~5 parts

[0012] 1~3 parts of accelerator

[0013] 10~15 parts of diluent

[0014] Among them, the structural formula of flame retardant A is as follows:

[0015] .

[0016] In some embodiments, the polyamide resin is selected from one or more of polycaprolactam PA6, polyhexamethylene adipamide PA66, polydecamethylenediamine PA1010, polyhexamethylenedodecanoamide PA612, and polyhexamethylenediamine PA610.

[0017] In some embodiments, the antioxidant may be selected from one or more of hindered phenol antioxidants, hindered amine antioxidants, and phosphite antioxidants.

[0018] In some embodiments, the antioxidant is selected from one or more of antioxidant 168, antioxidant 1098, antioxidant 1010, and antioxidant S9228.

[0019] In some embodiments, the inorganic filler is selected from one or more of silica, aluminum hydroxide, aluminum oxide, talc, aluminum nitride, boron nitride, silicon carbide, barium sulfate, barium titanate, strontium titanate, calcium carbonate, calcium silicate, mica, and glass fiber powder.

[0020] In some embodiments, the diluent is selected from one or more of dodecyl glycidyl ether, p-tert-butylphenol glycidyl ether, cresol glycidyl ether, ethylene glycol diglycidyl ether, octyl glycidyl ether, butanediol diglycidyl ether, phenyl glycidyl ether, and butyl glycidyl ether.

[0021] In some embodiments, the accelerator is selected from one or more of ethanolamine, diethanolamine, triethanolamine, dimethylethanolamine, bis(dimethylaminoethyl)ether, pentamethyldialkylenetriamine, and tetramethylalkylenediamine.

[0022] In some embodiments, the coupling agent is selected from one or more of KH-550, KH-560, KH-570, KH-792, KH-791, DL-602, and DL-171.

[0023] On the other hand, the present invention also provides a method for preparing a polyamide resin composition, comprising the following steps:

[0024] The polyamide resin, inorganic filler, antioxidant, coupling agent, flame retardant A, accelerator and diluent are stirred and mixed uniformly according to the proportion, and then plasticized by a twin-screw extruder. After pulling, cooling, pelletizing and drying, a polyamide resin composition is obtained, wherein the twin-screw extruder is set at a temperature of 200-250° C. and a screw speed of 300-500 rpm.

[0025] The present invention has the following beneficial effects:

[0026] 1) The polyamide resin composition prepared by the present invention exhibits excellent mechanical and flame retardant properties. Its tensile strength can reach over 90 MPa, while polyamide resins prepared using conventional flame retardants only have a strength of 50-65 MPa. Furthermore, the addition level of flame retardant A is relatively low; at a 2-4 wt% addition, it achieves a UL-94 V-0 flame retardancy rating and a LOI value as high as 38%. Furthermore, the composition exhibits excellent anti-drip properties, preventing dripping and ignition.

[0027] 2) The flame retardant A prepared by the present invention is a reactive flame retardant. It contains -COOH at both ends, which can undergo polymerization reaction with -NH2 on the polyamide resin to form a triazine ring chemical cross-linked network structure, thereby improving mechanical properties such as tensile strength;

[0028] 3) The polyamide resin prepared by the present invention is embedded with the structure of flame retardant A. When it burns and melts, the P=O and POC bonds decompose to produce phosphoric acid, metaphosphoric acid, and polymetaphosphoric acid, and their derivatives. These are liquid, viscous, glassy substances that cover and envelop the surface of the burning polymer, preventing the combustible material beneath the surface from coming into contact with oxygen in the air and flames, thereby achieving a flame retardant effect that isolates oxygen and heat. In addition, the presence of triazine rings in the molecular chain enhances the polymer's charring properties. The carbonized layer formed during combustion can prevent or delay the diffusion of oxygen into the matrix. As the charring properties improve, a dense, oxygen- and heat-isolating carbonized layer forms on the polymer surface, resulting in insufficient heat and oxygen to support the polymer's combustion, thus achieving a better flame retardant effect. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0030] The endpoints and any values ​​of the ranges described herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed herein.

[0031] Preparation Example 1: Synthesis of Flame Retardant A

[0032] Step 1: Synthesis of intermediate compound 3

[0033]

[0034] Cyanuric chloride (compound 1) (0.1 mol) and acetonitrile (200 mL) were added to a three-necked flask equipped with a constant-temperature stirrer, a reflux condenser, and a nitrogen atmosphere. Stirring was performed under ice bath for 1 hour until uniformly mixed, designated as Solution A. Compound 2 (0.15 mol) and triethylamine (0.15 mol) were dissolved in acetonitrile (100 mL) and ultrasonically dispersed for 1 hour, designated as Solution B. Solution B was slowly added dropwise to Solution A, maintaining the pH of the mixed solution between 7 and 9. The mixture was then stirred at 5°C for 3 hours, resulting in the formation of a large amount of white precipitate. After completion of the reaction, deionized water (100 mL) was added, the mixture was filtered, and the residue was washed with ice water three times (100 mL x 3). The residue was then dried under vacuum at 100°C to obtain a white solid with a yield of 92.8% and a purity of 99.3% by HPLC.

[0035] 1 H-NMR (400 MHz, DMSO- d 6): δ(ppm): 4.65 (d,6H), 3.72 (dq,2H).

[0036] Step 2: Synthesis of flame retardant A

[0037]

[0038] Intermediate compound 3 (0.1 mol), compound 4 (0.22 mol), tetrakistriphenylphosphine palladium (0.01 mol), and THF (200 mL) were added to a three-necked flask equipped with a constant temperature stirrer, a reflux condenser, and a nitrogen atmosphere. The temperature was raised to 90°C and stirred for 8 hours. After completion of the reaction, the mixture was filtered, and the filtrate was washed three times with water (200 mL x 3). The organic layer was dried over anhydrous sodium sulfate and concentrated under reduced pressure to obtain the crude product. The crude product was separated and purified by column chromatography to obtain a white solid, flame retardant A, with a yield of 81.5% and an HPLC purity of 99.2%.

[0039] LC-MS (ESI): [M+H] + =644.1.

[0040] 1 H-NMR (400 MHz, DMSO- d 6): δ(ppm): 12.60 (s,2H), 11.95 (s,2H), 8.51-8.44(m,2H), 8.17-8.10 (m,2H), 7.63-7.55 (m,2H), 4.32 (d,6H), 3.50-3.44 (m,2H).

[0041] Example 1

[0042] A polyamide resin composition is prepared from the following raw materials:

[0043] Polycaprolactam PA6 100 parts

[0044] 10 parts of silicon dioxide

[0045] 10102 parts of antioxidant

[0046] KH-5701 copies

[0047] 3 parts of flame retardant A

[0048] 2 parts of ethanolamine

[0049] 10 parts of lauryl glycidyl ether

[0050] The preparation method of the polyamide resin composition comprises the following steps:

[0051] The polyamide resin, inorganic filler, antioxidant, coupling agent, flame retardant A, accelerator, and diluent are stirred and mixed at a speed of 500 rpm until uniformly mixed, and then plasticized by a twin-screw extruder. After pulling, cooling, pelletizing, and drying, a polyamide resin composition is obtained. The twin-screw extruder is set at a temperature of 200-250°C and a screw speed of 300-500 rpm.

[0052] Example 2

[0053] A polyamide resin composition is prepared from the following raw materials:

[0054] 100 parts of polyhexamethylene adipamide PA66

[0055] 6 parts of silicon dioxide

[0056] 2 parts of Antioxidant 1098

[0057] KH-550 2 servings

[0058] 5 parts of flame retardant A

[0059] 3 parts of ethanolamine

[0060] 10 parts of ethylene glycol diglycidyl ether

[0061] The preparation method of the polyamide resin composition comprises the following steps:

[0062] The polyamide resin, inorganic filler, antioxidant, coupling agent, flame retardant A, accelerator, and diluent are stirred and mixed at a speed of 500 rpm until uniformly mixed, and then plasticized by a twin-screw extruder. After pulling, cooling, pelletizing, and drying, a polyamide resin composition is obtained. The twin-screw extruder is set at a temperature of 200-250°C and a screw speed of 300-500 rpm.

[0063] Example 3

[0064] A polyamide resin composition is prepared from the following raw materials:

[0065] Polycaprolactam PA6 100 parts

[0066] 10 parts mica

[0067] 2285 parts of antioxidant S9

[0068] DL-1711 copies

[0069] 3 parts of flame retardant A

[0070] 3 parts of ethanolamine

[0071] 15 parts of octyl glycidyl ether

[0072] The preparation method of the polyamide resin composition comprises the following steps:

[0073] The polyamide resin, inorganic filler, antioxidant, coupling agent, flame retardant A, accelerator, and diluent are stirred and mixed at a speed of 500 rpm until uniformly mixed, and then plasticized by a twin-screw extruder. After pulling, cooling, pelletizing, and drying, a polyamide resin composition is obtained. The twin-screw extruder is set at a temperature of 200-250°C and a screw speed of 300-500 rpm.

[0074] Comparative Example 1

[0075] Based on Example 1, flame retardant A was replaced with flame retardant SR-245

[0076] A polyamide resin composition is prepared from the following raw materials:

[0077] Polycaprolactam PA6 100 parts

[0078] 10 parts of silicon dioxide

[0079] 10102 parts of antioxidant

[0080] KH-5701 copies

[0081] 3 parts of flame retardant SR-245

[0082] 2 parts of ethanolamine

[0083] 10 parts of lauryl glycidyl ether

[0084] The preparation method of the polyamide resin composition comprises the following steps:

[0085] A polyamide resin, an inorganic filler, an antioxidant, a coupling agent, a flame retardant SR-245, an accelerator, and a diluent are uniformly mixed at a speed of 500 rpm, plasticized by a twin-screw extruder, and subjected to pulling, cooling, pelletizing, and drying to obtain a polyamide resin composition. The twin-screw extruder is set at a temperature of 200-250°C and a screw speed of 300-500 rpm.

[0086] Comparative Example 2

[0087] On the basis of Example 1, flame retardant A was replaced by triphenyl phosphate (TPP)

[0088] A polyamide resin composition is prepared from the following raw materials:

[0089] Polycaprolactam PA6 100 parts

[0090] 10 parts of silicon dioxide

[0091] 10102 parts of antioxidant

[0092] KH-5701 copies

[0093] 3 parts of triphenyl phosphate (TPP)

[0094] 2 parts of ethanolamine

[0095] 10 parts of lauryl glycidyl ether

[0096] The preparation method of the polyamide resin composition comprises the following steps:

[0097] A polyamide resin, an inorganic filler, an antioxidant, a coupling agent, triphenyl phosphate (TPP), an accelerator, and a diluent are uniformly mixed at a speed of 500 rpm, plasticized by a twin-screw extruder, and subjected to pulling, cooling, pelletizing, and drying to obtain a polyamide resin composition. The twin-screw extruder is set at a temperature of 200-250°C and a screw speed of 300-500 rpm.

[0098] Performance Testing

[0099] The polyamide resin compositions of Examples 1-3 and Comparative Examples 1-2 were sampled according to the methods specified in the performance test standards, and their mechanical properties and flame retardant properties were tested. The results are shown in Table 1.

[0100] 1) Tensile Strength: Splines were injection molded and tested according to the national standard GB / T1040.1-2006. The test spline dimensions were 75 mm × 5 mm × 2 mm dumbbell-shaped. The actual length, width, and thickness of the spline were accurately measured before measurement. The tensile strength was calculated as the average of five valid data points at a tensile rate of 5 mm / min.

[0101] 2) Limiting Oxygen Index (LOI) test:

[0102] The LOI refers to the minimum oxygen concentration required for a polymer to maintain stable combustion in a mixture of O2 and N2 under standard test conditions, expressed as the volume percentage of O2 in the mixture. For flame retardancy, for a sample to be self-extinguishing, the LOI must be above 26. For the same polymer, under the same conditions, a higher LOI indicates a greater percentage of O2 by volume required for combustion in a nitrogen-oxygen atmosphere. Furthermore, at the same O2 concentration, the less likely a polymer is to burn or the less complete the combustion, the better the flame retardancy.

[0103] The limiting oxygen index was determined according to ASTM D2863, and the sample size was 100 × 6.5 × 3 mm. 3 , each spline was repeated 5 times and the average value was taken.

[0104] 3) Vertical combustion test

[0105] The UL-94 test method evaluates the burning behavior of a specimen by measuring its linear burning rate. This is done in accordance with ASTM D3801, a standard for direct burning tests.

[0106] Table 1 Polyamide composition performance test results

[0107] Serial number Tensile strength (Mpa) Limiting oxygen index (%) Flame retardant grade Anti-drip performance Example 1 80.5 36.4 V-0 No dripping Example 2 90.8 38.2 V-0 No dripping Example 3 83.4 35.7 V-0 No dripping Comparative Example 1 61.2 26.5 V-2 dripping ignition Comparative Example 2 53.8 27.1 V-2 dripping ignition

[0108] As shown in Examples 1-3 and Comparative Examples 1-2, the polyamide resin compositions prepared using Flame Retardant A exhibit excellent mechanical and flame retardant properties. Specifically, the tensile strength reaches over 90 MPa, while polyamide resins prepared using conventional flame retardants only have a strength of 50-65 MPa. Furthermore, the addition of Flame Retardant A is relatively low, achieving a UL-94 V-0 flame retardancy rating and a high LOI value of 39% at a low addition level of 2-4 wt%. Furthermore, these compositions exhibit excellent anti-drip properties, preventing dripping and ignition, significantly outperforming existing technologies.

[0109] The amide resin composition of the present invention achieves these excellent properties primarily due to the following: 1) Flame Retardant A, prepared in the present invention, is a reactive flame retardant containing -COOH groups at both ends, which can polymerize with the -NH2 groups on the polyamide resin to form a chemically cross-linked triazine ring network, thereby enhancing mechanical properties such as tensile strength; 2) Flame Retardant A contains N and P flame retardant elements, resulting in synergistic and highly effective flame retardancy. Furthermore, the structure of Flame Retardant A is embedded in the polyamide resin. When the polyamide resin burns and melts, the P=O and POC bonds decompose to produce phosphoric acid, metaphosphoric acid, and polymetaphosphoric acid, and their derivatives. These liquid, viscous, glassy substances coat and envelop the surface of the burning polymer, shielding the underlying combustible material from oxygen and flame, thereby providing a flame retardant effect that isolates the flame from oxygen and heat. In addition, the molecular chain contains triazine rings, which enhance the carbonization performance of the polymer. The carbonized layer formed during the combustion process can prevent or delay the diffusion of oxygen into the interior of the matrix. As the carbonization performance improves, a dense carbonized layer that isolates oxygen and heat is formed on the surface of the polymer, resulting in insufficient heat and oxygen to support the combustion of the polymer, thereby achieving a better flame retardant effect.

[0110] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A polyamide resin composition comprising the following raw materials by weight: 100 parts of polyamide resin 5~10 parts of inorganic filler 1-5 parts antioxidant 1~3 parts coupling agent Flame retardant A1~5 parts 1~3 parts of accelerator 10~15 parts of diluent in, The structural formula of flame retardant A is as follows: 。 2. The polyamide resin composition according to claim 1, wherein The polyamide resin is selected from one or more of polycaprolactam PA6, polyhexamethylene adipamide PA66, polydecamethylenediamine PA1010, polydodecanediamide PA612 and polyhexamethylenediamine PA610.

3. The polyamide resin composition according to claim 1, wherein The antioxidant may be selected from one or more of hindered phenol antioxidants, hindered amine antioxidants and phosphite antioxidants.

4. The polyamide resin composition according to claim 3, wherein The antioxidant is selected from one or more of antioxidant 168, antioxidant 1098, antioxidant 1010 and antioxidant S9228.

5. The polyamide resin composition according to claim 4, characterized in that The inorganic filler is selected from one or more of silicon dioxide, aluminum hydroxide, aluminum oxide, talc, aluminum nitride, boron nitride, silicon carbide, barium sulfate, barium titanate, strontium titanate, calcium carbonate, calcium silicate, mica and glass fiber powder.

6. The polyamide resin composition according to claim 1, characterized in that The diluent is selected from one or more of dodecyl glycidyl ether, p-tert-butylphenol glycidyl ether, cresol glycidyl ether, ethylene glycol diglycidyl ether, octyl glycidyl ether, butanediol diglycidyl ether, phenyl glycidyl ether, and butyl glycidyl ether.

7. The polyamide resin composition according to claim 1, wherein The accelerator is selected from one or more of ethanolamine, diethanolamine, triethanolamine, dimethylethanolamine, bis(dimethylaminoethyl)ether, pentamethyldialkylenetriamine and tetramethylalkylenediamine.

8. The polyamide resin composition according to claim 1, wherein The coupling agent is selected from one or more of KH-550, KH-560, KH-570, KH-792, KH-791, DL-602 and DL-171.

9. A method for preparing the polyamide resin composition according to any one of claims 1 to 8, comprising the steps of: The polyamide resin, inorganic filler, antioxidant, coupling agent, flame retardant A, accelerator and diluent are stirred and mixed uniformly according to the proportion, and then plasticized by a twin-screw extruder, and then pulled, cooled, pelletized and dried to obtain a polyamide resin composition, wherein: The twin-screw extruder is set at a temperature of 200-250°C and a screw speed of 300-500 rpm.

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