Polyamide resin composition and preparation method thereof

Abstract

The invention belongs to the technical field of high polymer materials, and particularly relates to a polyamide resin composition and a preparation method thereof. The polyamide resin composition is prepared from the following raw materials in parts by weight: 100 parts of polyamide resin, 5 to 10 parts of inorganic filler, 1 to 5 parts of antioxidant, 1 to 3 parts of coupling agent, 1 to 5 parts of flame retardant A, 1 to 3 parts of accelerant and 10 to 15 parts of diluent. The polyamide resin composition prepared by the invention has excellent mechanical property and flame retardant property, the addition amount of the flame retardant A is relatively low, and under the condition that the addition amount of the flame retardant A is 2-4wt%, the flame retardant grade of UL-94 V-0 is realized, the LOI value is as high as 38%, and the flame retardant A and the flame retardant B have excellent molten drop resistance and do not cause a dripping ignition phenomenon.

Description

Technical Field

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

[0002] Polyamide (PA), commonly known as nylon, has excellent electrical and mechanical properties, and is wear-resistant, oil-resistant, solvent-resistant, and corrosion-resistant. Because the ends of the main chain of polyamide contain amino and carboxyl groups, they have certain reactivity. Their own shortcomings, such as high water absorption and flammability, can be physically and chemically modified by methods such as blocking, grafting, blending, reinforcement, and filling. Since the industrialization of polyamide, it has been widely used in the automotive, electronic, mechanical, and aviation industries, with a large demand, and is an indispensable structural material in the industrial field.

[0003] As a polymer material, polyamide has an obvious disadvantage of being flammable. In addition, polyamide has a fast combustion speed and high heat release. A large number of flaming droplets are produced during combustion, which increases the risk of fire spread. At present, the flame retardant properties of polyamide are mainly modified by adding flame retardants. Flame retardants can be divided into three categories according to the different component categories: inorganic flame retardants, organic flame retardants, and inorganic-organic mixed flame retardants. Inorganic flame retardants mainly include aluminum hydroxide, magnesium hydroxide, antimony oxide, silicon series, etc.; organic flame retardants are mainly organic compounds containing halogens, phosphorus, nitrogen, silicon and other elements. Flame retardants can also be divided into two categories according to their relationship with the flame-retardant material: additive flame retardants and reactive flame retardants. Additive flame retardants exist in the polymer matrix material in a physically dispersed manner. They need a higher addition amount to exert their flame retardant effect, and they have poor compatibility with the polymer matrix, resulting in poor physical properties. Reactive flame retardants participate in the polymerization reaction of polymers as reactive monomers or auxiliary reagents, embedding effective flame retardant components into macromolecular chains. The characteristics are that there is no volatilization, dissolution and migration of flame retardants in the polymer matrix, and polymer materials do not need additional flame retardant treatment to have inherent flame retardancy. Flame retardants are usually divided into halogen-based, halogen-phosphorus-based, organic phosphorus-based, inorganic phosphorus-based, nitrogen-based, silicon-based, boron-based flame retardants, etc. according to the types of elements contained.

[0004] Polyamide resin has excellent comprehensive properties and is one of the most widely used engineering plastics. However, the flammability of polyamide resin also brings potential fire hazards. Moreover, the use environment of polyamide resin is harsh, such as high temperature, high humidity, high voltage, etc., so it is very important to have flame retardancy. At present, the halogen-containing flame retardant with the largest usage and the best flame retardant effect in polyamide resin is gradually being eliminated because it will cause a surge in the release of toxic smoke. Therefore, it is urgent to develop a polyamide resin composition with high-efficiency flame retardant properties 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 of toxic flame retardants and poor flame retardant properties.

[0006] A polyamide resin composition, comprising the following raw materials by weight: Polyamide resin 100 parts Inorganic filler 5~10 parts 1~5 parts of antioxidant Coupling agent 1~3 parts Flame retardant A1~5 parts 1~3 parts of accelerator 10~15 parts of diluent Among them, the structural formula of flame retardant A is as follows: .

[0007] In some embodiments, the polyamide resin is selected from one or more of polycaprolactam PA6, polyhexamethylene adipamide PA66, polydecanediamide PA1010, polyhexamethylene dodecanediamide PA612, and polyhexamethylene dodecanediamide PA610.

[0008] In some embodiments, the antioxidant may be selected from one or more of hindered phenol antioxidants, hindered amine antioxidants, and phosphite antioxidants.

[0009] In some embodiments, the antioxidant is selected from one or more of Antioxidant 168, Antioxidant 1098, Antioxidant 1010, and Antioxidant S9228.

[0010] In some embodiments, 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.

[0011] 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.

[0012] In some embodiments, the accelerator is selected from one or more of ethanolamine, diethanolamine, triethanolamine, dimethylethanolamine, bis(dimethylaminoethyl)ether, pentamethyldialkylenetriamine, and tetramethylalkylenediamine.

[0013] 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.

[0014] On the other hand, the present invention also provides a method for preparing a polyamide resin composition, comprising the following steps: 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 traction, 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.

[0015] The present invention has the following beneficial effects: 1) The polyamide resin composition prepared by the present invention has excellent mechanical properties and flame retardant properties. The tensile strength can reach more than 90Mpa, while the polyamide resin obtained by using ordinary flame retardants is only 50-65Mpa; in addition, the addition amount of flame retardant A is low. When the addition amount is 2-4wt%, the flame retardant grade of UL-94 V-0 is achieved, and the LOI value is as high as 38%. They also have excellent anti-melting droplet performance and will not cause dripping ignition.

[0016] 2) The flame retardant A prepared by the present invention is a reactive flame retardant, which contains -COOH at both ends and can undergo polymerization reaction with -NH2 on the polyamide resin to form a triazine ring chemical cross-linking network structure, thereby improving mechanical properties such as tensile strength; 3) The structure of flame retardant A is embedded in the polyamide resin prepared by the present invention. When it burns and melts, P=O and POC bonds decompose to produce phosphoric acid, metaphosphoric acid and polymetaphosphoric acid and their derivatives, which are liquid viscous glassy substances that cover and wrap the surface of the burning polymer, so that the combustibles below the surface cannot contact the oxygen and flame in the air, thereby achieving flame retardant effects of oxygen isolation and heat insulation. 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 matrix. With the improvement of carbonization performance, 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, which has a better flame retardant effect. DETAILED DESCRIPTION

[0017] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] The endpoints and any values ​​of the scope described in the present invention are not limited to the precise scope or value, and these scopes or values ​​should be understood to include values ​​close to these scopes or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the 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 as specifically disclosed in this article.

[0019] Preparation Example 1: Synthesis of Flame Retardant A Step 1: Synthesis of intermediate compound 3

[0020] 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 nitrogen protection, and stirred for 1 h in an ice bath to mix evenly, which was recorded as solution A. Compound 2 (0.15 mol) and triethylamine (0.15 mol) were dissolved in acetonitrile (100 mL), and ultrasonically dispersed for 1 h, which was recorded as solution B. Solution B was slowly added dropwise to solution A, and the pH of the mixed solution was maintained at 7-9, and then the mixed solution was stirred at 5 ° C for 3 h to generate a large amount of white precipitate. After the reaction, deionized water (100 mL) was added, filtered, and the filter residue was washed with ice water 3 times (100 mL x 3), and vacuum dried at 100 ° C to obtain a white solid with a yield of 92.8% and an HPLC purity of 99.3%.

[0021] 1 H-NMR (400 MHz, DMSO- d 6): δ(ppm): 4.65 (d,6H), 3.72 (dq,2H).

[0022] Step 2: Synthesis of flame retardant A

[0023] The 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 nitrogen protection, and the temperature was raised to 90°C and stirred for 8 hours. After the reaction, the mixture was filtered, and the filtrate was washed with water 3 times (200 mL x 3). The organic layer was dried over anhydrous sodium sulfate and concentrated under reduced pressure to obtain a crude product. The crude product was separated and purified by column chromatography to obtain a white solid, namely flame retardant A, with a yield of 81.5% and an HPLC purity of 99.2%.

[0024] LC-MS (ESI): [M+H] + =644.1.

[0025] 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).

[0026] Example 1 A polyamide resin composition is prepared from the following raw materials: Polycaprolactam PA6 100 parts 10 parts of silicon dioxide Antioxidant 10102 parts KH-5701 copy Flame retardant A3 parts 2 parts of ethanolamine 10 parts of dodecyl glycidyl ether The preparation method of the polyamide resin composition comprises the following steps: The polyamide resin, inorganic filler, antioxidant, coupling agent, flame retardant A, accelerator and diluent are stirred and mixed uniformly at a speed of 500 rpm 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. The twin-screw extruder is set at a temperature of 200-250° C. and a screw speed of 300-500 rpm.

[0027] Example 2 A polyamide resin composition is prepared from the following raw materials: Polyhexamethylene adipamide PA66 100 parts 6 parts of silicon dioxide Antioxidant 1098 2 parts KH-550 2 pcs Flame retardant A5 parts 3 parts of ethanolamine 10 parts of ethylene glycol diglycidyl ether The preparation method of the polyamide resin composition comprises the following steps: The polyamide resin, inorganic filler, antioxidant, coupling agent, flame retardant A, accelerator and diluent are stirred and mixed uniformly at a speed of 500 rpm 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. The twin-screw extruder is set at a temperature of 200-250° C. and a screw speed of 300-500 rpm.

[0028] Example 3 A polyamide resin composition is prepared from the following raw materials: Polycaprolactam PA6 100 parts Mica 10 parts Antioxidant S92285 parts DL-1711 copies Flame retardant A3 parts 3 parts of ethanolamine 15 parts of Octyl Glycidyl Ether The preparation method of the polyamide resin composition comprises the following steps: The polyamide resin, inorganic filler, antioxidant, coupling agent, flame retardant A, accelerator and diluent are stirred and mixed uniformly at a speed of 500 rpm 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. The twin-screw extruder is set at a temperature of 200-250° C. and a screw speed of 300-500 rpm.

[0029] Comparative Example 1 Based on Example 1, flame retardant A was replaced with flame retardant SR-245 A polyamide resin composition is prepared from the following raw materials: Polycaprolactam PA6 100 parts 10 parts of silicon dioxide Antioxidant 10102 parts KH-5701 copy Flame retardant SR-245 3 parts 2 parts of ethanolamine 10 parts of dodecyl glycidyl ether The preparation method of the polyamide resin composition comprises the following steps: The polyamide resin, inorganic filler, antioxidant, coupling agent, flame retardant SR-245, accelerator and diluent are stirred and mixed uniformly at a speed of 500 rpm 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. The twin-screw extruder is set at a temperature of 200-250° C. and a screw speed of 300-500 rpm.

[0030] Comparative Example 2 On the basis of Example 1, flame retardant A was replaced by triphenyl phosphate (TPP) A polyamide resin composition is prepared from the following raw materials: Polycaprolactam PA6 100 parts 10 parts of silicon dioxide Antioxidant 10102 parts KH-5701 copy 3 parts of triphenyl phosphate (TPP) 2 parts of ethanolamine 10 parts of dodecyl glycidyl ether The preparation method of the polyamide resin composition comprises the following steps: The polyamide resin, inorganic filler, antioxidant, coupling agent, triphenyl phosphate (TPP), accelerator and diluent are stirred and mixed uniformly at a speed of 500 rpm 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. The twin-screw extruder is set at a temperature of 200-250° C. and a screw speed of 300-500 rpm.

[0031] Performance Testing 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.

[0032] 1) Tensile strength: The spline is injection molded and tested according to the national standard GB / T1040.1-2006. The test spline size is a dumbbell-shaped spline of 75 mm × 5 mm × 2 mm. Before the measurement, the actual length, width and thickness of the spline are accurately measured. The tensile rate is 5 mm / min, and the tensile strength is the average of 5 valid data; 2) Limiting Oxygen Index (LOI) Test: 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 mixed gas. For flame retardancy requirements, if the sample is to be self-extinguishing, the limiting oxygen index must be above 26. For the same type of polymer, under the same conditions, the larger the oxygen index, the greater the percentage of O2 volume required for the substance to burn in a nitrogen and oxygen atmosphere; and under the same O2 concentration, the less likely it is to burn or the less fully it burns, the better the flame retardant performance of the material.

[0033] 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.

[0034] 3) Vertical burning test The UL-94 test method is to evaluate the burning behavior of the sample by measuring the linear burning rate of the sample. The direct burning test is carried out according to the standard ASTM D3801.

[0035] Table 1 Polyamide composition performance test results 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 Drip Ignition Comparative Example 2 53.8 27.1 V-2 Drip Ignition It can be seen from Examples 1-3 and Comparative Examples 1-2 that the polyamide resin composition prepared using flame retardant A has excellent mechanical properties and flame retardant properties. Among them, the tensile strength can reach more than 90Mpa, while the polyamide resin obtained using ordinary flame retardants is only 50-65Mpa; in addition, the addition amount of flame retardant A is relatively low. When its addition amount is 2-4wt%, the flame retardant grade of UL-94 V-0 is achieved, and the LOI value is as high as 39%. They also have excellent anti-drip performance and will not cause dripping and ignition, which is significantly better than the prior art.

[0036] The main reasons why the amide resin composition of the present invention achieves the above-mentioned excellent performance are: 1) The flame retardant A prepared by the present invention is a reactive flame retardant, and its two ends contain -COOH, which can undergo polymerization reaction with -NH2 on the polyamide resin to form a triazine ring chemical cross-linking network structure, thereby improving mechanical properties such as tensile strength; 2) Flame retardant A contains N and P flame retardant elements, which can achieve synergistic and efficient flame retardancy. The flame retardant A structure is embedded in the polyamide resin. When it burns and melts, the P=O and POC bonds decompose to produce phosphoric acid, metaphosphoric acid and polymetaphosphoric acid and their derivatives, which are liquid viscous glassy substances that cover and wrap the surface of the burning polymer, so that the combustibles below the surface cannot contact the oxygen and flame in the air, thereby achieving an oxygen-insulating and heat-insulating flame retardant effect. In addition, the molecular chain contains triazine rings, which enhance the charring properties 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 charring 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, which has a better flame retardant effect.

[0037] 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 equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A polyamide resin composition comprising the following raw materials by weight: Polyamide resin 100 parts Inorganic filler 5~10 parts 1~5 parts of antioxidant Coupling agent 1~3 parts 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, characterized in that The polyamide resin is selected from one or more of polycaprolactam PA6, polyhexamethylene adipamide PA66, polydecanediamide PA1010, polyhexamethylene dodecanoamide PA612 and polyhexamethylene dodecanoamide PA610.

3. The polyamide resin composition according to claim 1, characterized in that 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 4, characterized in that 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, characterized in that 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, characterized in that 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, 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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