阅读说明：本技术 免喷涂聚酰胺66材料及其制备方法 (Spraying-free polyamide 66 material and preparation method thereof ) 是由 王忠强 蓝承东 冯刚 于 2019-10-18 设计创作，主要内容包括：本发明涉及一种免喷涂聚酰胺66材料及其制备方法,所述免喷涂聚酰胺66材料由以下原料原位聚合制备而成：己二胺,己二酸,改性蒙脱土,改性珠光颜料,改性金属粉,苯甲酸,甲苯二异氰酸酯,抗氧剂。该免喷涂聚酰胺66材料具有优异的力学性能、加工性能和免喷涂效果,可应用于家用电器部件和汽车内外饰件等。(The invention relates to a spraying-free polyamide 66 material and a preparation method thereof, wherein the spraying-free polyamide 66 material is prepared by in-situ polymerization of the following raw materials: hexamethylene diamine, adipic acid, modified montmorillonite, modified pearlescent pigment, modified metal powder, benzoic acid, toluene diisocyanate and an antioxidant. The spraying-free polyamide 66 material has excellent mechanical property, processability and spraying-free effect, and can be applied to household appliance parts, automobile interior and exterior trimming parts and the like.)

1. The spraying-free polyamide 66 material is characterized by being prepared from the following raw materials in parts by weight:

the modified montmorillonite is obtained by reacting sodium-based montmorillonite with caprolactam;

the modified pearlescent pigment is obtained by reacting pearlescent pigment, succinic anhydride and gamma-aminopropyltriethoxysilane; the pearlescent pigment is one or a mixture of more than two of natural fish scale pearlescent pigment, bismuth oxychloride crystalline pearlescent pigment, mica coated pearlescent pigment, silicon dioxide coated pearlescent pigment, aluminum silicate coated pearlescent pigment, aluminum borate coated pearlescent pigment, artificial mica coated pearlescent pigment and bismuth oxide coated pearlescent pigment;

the modified metal powder is obtained by reacting metal powder, succinic anhydride and gamma-aminopropyltriethoxysilane; the metal powder is one or a mixture of more than two of aluminum powder, copper powder, silver powder, zinc powder and gold powder.

2. The spray-free polyamide 66 material as claimed in claim 1, which is prepared from the following raw materials in parts by weight:

3. the spraying-free polyamide 66 material of claim 1 or 2, wherein the modified montmorillonite is obtained by reacting sodium montmorillonite and caprolactam in a mass ratio of 1: 0.03-0.05; and/or the presence of a catalyst in the reaction mixture,

the modified pearlescent pigment is obtained by reacting pearlescent pigment, succinic anhydride and gamma-aminopropyltriethoxysilane in a mass ratio of 1: 0.15-0.25: 0.4-0.5, and the molar numbers of the succinic anhydride and the gamma-aminopropyltriethoxysilane are equal; and/or the presence of a catalyst in the reaction mixture,

the modified metal powder is obtained by reacting metal powder, succinic anhydride and gamma-aminopropyltriethoxysilane according to the mass ratio of 1: 0.15-0.25: 0.4-0.5, and the molar numbers of the succinic anhydride and the gamma-aminopropyltriethoxysilane are equal.

4. The spray-free polyamide 66 material as claimed in claim 1 or 2, wherein the antioxidant consists of a primary antioxidant and a secondary antioxidant; the main antioxidant is one or a mixture of more than two of tetra (beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid) pentaerythritol ester, N '-1, 6-hexamethylene-bis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionamide ], N' -bis (2,2,6, 6-tetramethyl-4-piperidyl) -1, 3-benzenedicarboxamide; the auxiliary antioxidant is one or a mixture of more than two of tris (2, 4-di-tert-butylphenyl) phosphite, bis (2, 4-di-tert-butylphenol) pentaerythritol diphosphite, bis (2, 4-di-tert-butyl) pentaerythritol diphosphite and bis (2, 6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite.

5. The spray-free polyamide 66 material of claim 1 or 2, wherein the pearlescent pigment is a silica-coated pearlescent pigment; and/or the presence of a catalyst in the reaction mixture,

the metal powder is aluminum powder; and/or the presence of a catalyst in the reaction mixture,

the antioxidant comprises a main antioxidant and an auxiliary antioxidant, wherein the main antioxidant is N, N' -bis (2,2,6, 6-tetramethyl-4-piperidyl) -1, 3-benzenedicarboxamide, and the auxiliary antioxidant is bis (2, 6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphate.

6. The spray-free polyamide 66 material of claim 1 or 2, wherein the pearlescent pigment has a particle size of 5 to 300 μ ι η; and/or the presence of a catalyst in the reaction mixture,

the particle size of the metal powder is 5-300 mu m; and/or the presence of a catalyst in the reaction mixture,

the intrinsic viscosity of the spraying-free polyamide 66 material is 1.2-1.8 dL/g, and the melting temperature is 260-266 ℃.

7. The spray-free polyamide 66 material of claim 1 or 2, wherein the preparation method of the modified montmorillonite comprises the following steps: dispersing the sodium montmorillonite in distilled water at the temperature of 75-85 ℃ to obtain montmorillonite water suspension, dissolving caprolactam and concentrated hydrochloric acid in distilled water at the temperature of 55-65 ℃ to obtain caprolactam solution, pouring the caprolactam solution into the montmorillonite water suspension, stirring at the temperature of 85-95 ℃ for 3-5 hours, and performing suction filtration to obtain the modified montmorillonite; and/or the presence of a catalyst in the reaction mixture,

the preparation method of the modified pearlescent pigment comprises the following steps: dispersing the succinic anhydride and the gamma-aminopropyltriethoxysilane in N, N-dimethylformamide, stirring for 2-4 hours at 55-65 ℃, adding N, N-dimethylformamide suspension of pearlescent pigment subjected to ultrasonic dispersion into the system, simultaneously adding distilled water, stirring for 2-4 hours at 55-65 ℃, washing with ethanol, and performing centrifugal separation to obtain the modified pearlescent pigment; and/or the presence of a catalyst in the reaction mixture,

the preparation method of the modified metal powder comprises the following steps: dispersing the succinic anhydride and the gamma-aminopropyltriethoxysilane in N, N-dimethylformamide, stirring for 2-4 hours at 55-65 ℃, adding N, N-dimethylformamide suspension of ultrasonically dispersed metal powder into the system, simultaneously adding distilled water, stirring for 2-4 hours at 55-65 ℃, washing with ethanol, and performing centrifugal separation to obtain the modified metal powder.

8. The spray-free polyamide 66 material of claim 7, wherein in the preparation of the modified montmorillonite, the mass ratio of sodium-based montmorillonite to caprolactam is 1: 0.03-0.05; and/or the presence of a catalyst in the reaction mixture,

in the preparation of the modified pearlescent pigment, the mass ratio of the pearlescent pigment to succinic anhydride to gamma-aminopropyltriethoxysilane is 1: 0.15-0.25: 0.4-0.5, and the mole numbers of the succinic anhydride and the gamma-aminopropyltriethoxysilane are equal; and/or the presence of a catalyst in the reaction mixture,

in the preparation of the modified metal powder, the mass ratio of the metal powder to the succinic anhydride to the gamma-aminopropyltriethoxysilane is 1: 0.15-0.25: 0.4-0.5, and the mole numbers of the succinic anhydride and the gamma-aminopropyltriethoxysilane are equal.

9. The preparation method of the spraying-free polyamide 66 material as claimed in any one of claims 1 to 8, characterized by comprising the following steps:

(1) adding the hexamethylene diamine and the adipic acid which are dried in vacuum into a stirring type polymerization reactor, and simultaneously adding the modified montmorillonite, the modified pearlescent pigment, the modified metal powder, the benzoic acid, the toluene diisocyanate, the antioxidant and a proper amount of water; vacuumizing for 3-7 min, introducing nitrogen for 3-7 min, and circulating for 4-8 times in such a way, so that reactants exist in an environment under the protection of nitrogen, and controlling the system pressure in the stirring type polymerization reactor to be 0.1-0.4 MPa;

(2) heating the stirring type polymerization reactor to 265-275 ℃ within 2-4 hours in a sealed manner at a constant speed, adjusting the stirring speed of the stirring type polymerization reactor to 30-50 r/min, wherein when the temperature of the stirring type polymerization reactor reaches 220 ℃, gas is discharged to 1.4MPa, the pressure is maintained at 1.4MPa, after 0.5-3 hours of reaction, the gas is discharged to normal pressure, meanwhile, the temperature is increased to 276-286 ℃, after 0.5-3 hours of continuous reaction at 276-286 ℃, constant temperature continuous vacuum pumping is carried out for 0.1-2 hours, the reaction is finished, and nitrogen is supplemented during discharging, so that the spraying-free polyamide 66 material is obtained.

10. The method of claim 9, comprising the steps of:

(1) adding the hexamethylene diamine and the adipic acid which are dried in vacuum into a stirring type polymerization reactor, and simultaneously adding the modified montmorillonite, the modified pearlescent pigment, the modified metal powder, the benzoic acid, the toluene diisocyanate, the antioxidant and a proper amount of water; vacuumizing for 4-6 min, introducing nitrogen for 4-6 min, and circulating for 5-7 times in such a way, so that reactants exist in an environment under the protection of nitrogen, and controlling the system pressure in the stirring type polymerization reactor to be 0.2-0.3 MPa;

(2) and heating the stirring type polymerization reactor to 267-273 ℃ within 2-4 hours in a sealed manner at a constant speed, adjusting the stirring speed of the stirring type polymerization reactor to 30-50 r/min, wherein when the temperature of the stirring type polymerization reactor reaches 220 ℃, the gas is discharged to 1.4MPa, the pressure is maintained at 1.4MPa, after the reaction is carried out for 1-2 hours, the gas is discharged to normal pressure, the temperature is increased to 278-284 ℃, after the reaction is carried out for 1-2 hours at 278-284 ℃, the constant temperature is continuously vacuumized for 0.3-1 hour, the reaction is finished, and nitrogen is supplemented during discharging, so that the spraying-free polyamide 66 material is obtained.

Technical Field

The invention relates to the field of materials, in particular to a spraying-free polyamide 66 material and a preparation method thereof.

Background

The traditional plastic part can obtain rich appearance effects including pearl effect, metal texture and flickering effect after being sprayed, and is favored by consumers, the appearance effects are applied to industries such as electronics, electric tools, household appliances, buildings, automobiles and the like, the unprecedented market competitiveness is displayed, but the spraying process is complicated and pollutes the environment, toxic and harmful gas and dust are generated, and the human health is harmed. In order to solve the problems of environmental pollution and energy waste generated in the spraying process, people continuously improve the spraying process flow, so that the spraying process flow gradually develops towards the direction of low organic solvent rate, aqueous solvent and powder pigment. In the field of resin application, the concept of a spraying-free product is developed, namely, metallic pigment, pearlescent pigment and other pigments with special color effects are directly added into a resin substrate, so that a series of products similar to the appearance effect of the spraying process treatment are obtained.

Polyamide, also known as nylon, is a polymer resin with a plurality of repeated polyamide groups on a molecular main chain, has good mechanical properties, heat resistance, wear resistance and chemical resistance, is easy to process, and is an ideal material for preparing household appliance parts and automobile interior and exterior trim parts.

Currently, some studies have been made in the prior art on spray-free polyamide materials, such as: chinese patent CN107674413A discloses a spraying-free polyamide resin compound and a preparation method thereof, wherein the polyamide resin compound comprises the following components in parts by weight: 30-70 parts of polyamide, 5-60 parts of AS-based polymer, 0.1-6 parts of effect pigment, 2-10 parts of compatilizer and 0-60 parts of filler; chinese patent CN107793754A discloses an environment-friendly low-odor spray-free polyamide composition, which comprises the following components in parts by weight: 95-100 parts of polyamide, 0.01-5 parts of metal compound and 0.1-6 parts of effect pigment; chinese patent CN107722620A discloses a low-odor high-gloss spray-free polyamide composition, which comprises the following components in parts by weight: 30-100 parts of polyamide, 0.1-6 parts of effect pigment, 0-50 parts of mineral filler, 0-20 parts of toughening agent, 0-5 parts of auxiliary agent, 0-1 part of heat stabilizer and 0-1 part of antioxidant; chinese patent CN108559258A discloses a high-flow spraying-free metallic silver polyamide composition and a preparation method thereof, wherein the raw materials comprise PA6 resin, metallic silver powder, a coupling agent, an internal lubricant, an external lubricant, an antioxidant, an ultraviolet absorbent, amino silicone oil, a flame retardant, calcium stearate, MBS, SMA, silicon dioxide, magnesium salt whisker, hollow glass bead, EBS, glass fiber, a compatilizer and ABS; chinese patent CN108976783A discloses a polyamide aesthetic resin composition with high metal texture, which is composed of the following components: 70-95 parts of Polyamide (PA), 0-5 parts of an auxiliary agent and 5.6-50 parts of special effect master batch; the special effect master batch consists of the following components: 5-30 parts of polymethyl methacrylate grafted maleic anhydride/styrene (PMMA-g-MAH/St), 0.5-18 parts of special effect toner and 0.1-2 parts of additive; chinese patent CN109897368A discloses a spraying-free heat-conducting nylon material for LED lighting products and a preparation method thereof, relating to the field of high polymer materials, wherein the spraying-free heat-conducting nylon material for LED lighting products comprises the following raw materials in parts by weight: 40-60 parts of polyamide, 5-10 parts of toughening agent, 30-50 parts of heat-conducting powder, 1-8 parts of metal pigment, 0.5-1.0 part of coupling agent, 0.2-0.6 part of antistatic agent and 0.2-0.6 part of antioxidant; chinese patent CN107216649A discloses a spraying-free polyamide composition with metallic luster, which comprises the following raw material components in parts by weight: 100 parts of polyamide resin, 4-20 parts of acrylonitrile-styrene copolymer, 0.2-2 parts of metal pigment, 2-10 parts of compatilizer, 0-25 parts of filler, 0.2-6 parts of toughening agent, 0.2-2 parts of dispersing aid and 0.2-2 parts of processing aid; chinese patent CN108299820A discloses a spraying-free nano nylon 6 composite material, which comprises the following raw materials in parts by weight: 70-94 parts of nano nylon 6 material, 4-10 parts of metal color master batch, 1-10 parts of antistatic agent and 1-10 parts of antibacterial agent; the nano nylon 6 material comprises the following raw materials in parts by mass: 81-87 parts of caprolactam and 3-6 parts of montmorillonite; chinese patent CN107805385A discloses a spraying-free nylon material and a preparation method thereof, wherein the spraying-free nylon material comprises the following raw materials by weight: 40-50 parts of nylon, 20-30 parts of reinforcement, 4-8 parts of foaming agent master batch, 2-4 parts of metal pigment master batch, 0.3-2.4 parts of lubricant and 1-4 parts of antioxidant; chinese patent CN109825077A discloses a heat-resistant spray-free high-gloss nylon material, which is composed of the following raw materials in parts by weight: 55.9-82.8 parts of semi-aromatic nylon resin, 5-20 parts of polycaprolactam and/or poly hexamethylene diamine, 10-20 parts of solid glass beads, 1-3 parts of brightening agent, 0.4-0.8 part of antioxidant, 0.5-1.5 parts of colorant and 0.3-0.8 part of lubricant; chinese patent CN108117745A discloses a spray-free toughened nylon 6 material and a preparation method thereof, belonging to the technical field of modification of high polymer materials, the material is composed of 59.4-76.9% of nylon 6 resin, 10-15% of toughening agent, 7-12% of plasticizer, 3-6% of maleic anhydride grafted polypropylene, 0.2-0.6% of oxidized polyethylene wax, 0.2-0.5% of flow modifier, 0.2-0.5% of antioxidant, 0.5-1.0% of lubricant and 2-5% of metal master batch.

It can be seen that the spraying-free polyamide materials disclosed in the prior art are a series of products similar to the appearance effect of the spraying process treatment by directly adding effect pigments with special colors, such as metal pigments, pearlescent pigments and the like, into a resin substrate, and the effect pigments directly added in the methods belong to inorganic components, and have poor compatibility with polyamide, so that the spraying-free polyamide materials are easy to have the problems of flow marks, welding marks and the like in the processing process, and the mechanical properties, such as tensile strength and the like, of the polyamide materials are influenced.

Disclosure of Invention

Based on the above, the invention aims to provide a polyamide 66 material which has excellent mechanical properties, processability and a spraying-free effect, has low probability of occurrence of problems such as flow marks, welding marks and the like in a processing process, and can be applied to household appliance parts, automobile interior and exterior parts and the like.

In order to achieve the purpose, the invention adopts the following scheme:

the spraying-free polyamide 66 material is prepared from the following raw materials in parts by weight:

the modified montmorillonite is obtained by reacting sodium-based montmorillonite with caprolactam;

the modified pearlescent pigment is obtained by reacting pearlescent pigment, succinic anhydride and gamma-aminopropyltriethoxysilane; the pearlescent pigment is one or a mixture of more than two of natural fish scale pearlescent pigment, bismuth oxychloride crystalline pearlescent pigment, mica coated pearlescent pigment, silicon dioxide coated pearlescent pigment, aluminum silicate coated pearlescent pigment, aluminum borate coated pearlescent pigment, artificial mica coated pearlescent pigment and bismuth oxide coated pearlescent pigment;

the modified metal powder is obtained by reacting metal powder, succinic anhydride and gamma-aminopropyltriethoxysilane; the metal powder is one or a mixture of more than two of aluminum powder, copper powder, silver powder, zinc powder and gold powder.

In some embodiments, the spraying-free polyamide 66 material is prepared from the following raw materials in parts by weight:

in some embodiments, the spraying-free polyamide 66 material is further preferably prepared from the following raw materials in parts by weight:

in some embodiments, the modified montmorillonite is obtained by reacting sodium montmorillonite and caprolactam in a mass ratio of 1: 0.03-0.05.

In some embodiments, the modified pearlescent pigment is obtained by reacting pearlescent pigment, succinic anhydride and gamma-aminopropyltriethoxysilane at a mass ratio of 1: 0.15-0.25: 0.4-0.5, and the molar numbers of the succinic anhydride and the gamma-aminopropyltriethoxysilane are equal.

In some embodiments, the modified metal powder is obtained by reacting metal powder, succinic anhydride and gamma-aminopropyltriethoxysilane at a mass ratio of 1: 0.15-0.25: 0.4-0.5, and the molar numbers of the succinic anhydride and the gamma-aminopropyltriethoxysilane are equal.

In some of these embodiments, the antioxidant consists of a primary antioxidant and a secondary antioxidant; the main antioxidant is one or a mixture of more than two of tetra (beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid) pentaerythritol ester, N '-1, 6-hexamethylene-bis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionamide ], N' -bis (2,2,6, 6-tetramethyl-4-piperidyl) -1, 3-benzenedicarboxamide; the auxiliary antioxidant is one or a mixture of more than two of tris (2, 4-di-tert-butylphenyl) phosphite, bis (2, 4-di-tert-butylphenol) pentaerythritol diphosphite, bis (2, 4-di-tert-butyl) pentaerythritol diphosphite and bis (2, 6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite.

In some of these embodiments, the primary antioxidant is N, N' -bis (2,2,6, 6-tetramethyl-4-piperidinyl) -1, 3-benzenedicarboxamide and the secondary antioxidant is bis (2, 6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphate.

In some of these embodiments, the pearlescent pigment is a silica-coated pearlescent pigment.

In some of these embodiments, the metal powder is aluminum powder.

In some of these embodiments, the pearlescent pigment has a particle size of 5 μm to 300 μm.

In some of these embodiments, the pearlescent pigment has a particle size of 10 to 30 μm.

In some of these embodiments, the metal powder has a particle size of 5 μm to 300 μm.

In some of these embodiments, the metal powder has a particle size of 10 μm to 30 μm.

In some embodiments, the spray-free polyamide 66 material has an intrinsic viscosity of 1.2-1.8 dL/g and a melting temperature of 260-266 ℃.

In some embodiments, the preparation method of the modified montmorillonite comprises the following steps: dispersing the sodium montmorillonite in distilled water at 75-85 ℃ to obtain montmorillonite water suspension, dissolving caprolactam and concentrated hydrochloric acid in distilled water at 55-65 ℃ to obtain caprolactam solution, pouring the caprolactam solution into the montmorillonite water suspension, stirring at 85-95 ℃ for 3-5 hours, and performing suction filtration to obtain the modified montmorillonite.

In some of these embodiments, the method of preparing the modified pearlescent pigment comprises the steps of: dispersing the succinic anhydride and the gamma-aminopropyltriethoxysilane in N, N-dimethylformamide, stirring for 2-4 hours at 55-65 ℃, adding N, N-dimethylformamide suspension of the pearlescent pigment subjected to ultrasonic dispersion into the system, simultaneously adding distilled water, stirring for 2-4 hours at 55-65 ℃, washing with ethanol, and performing centrifugal separation to obtain the modified pearlescent pigment.

In some embodiments, the method for preparing the modified metal powder comprises the following steps: dispersing the succinic anhydride and the gamma-aminopropyltriethoxysilane in N, N-dimethylformamide, stirring for 2-4 hours at 55-65 ℃, adding N, N-dimethylformamide suspension of ultrasonically dispersed metal powder into the system, simultaneously adding distilled water, stirring for 2-4 hours at 55-65 ℃, washing with ethanol, and performing centrifugal separation to obtain the modified metal powder.

In some embodiments, in the preparation of the modified montmorillonite, the mass ratio of the sodium montmorillonite to the caprolactam is 1: 0.03-0.05.

In some embodiments, the modified pearlescent pigment is prepared by mixing the pearlescent pigment, succinic anhydride and gamma-aminopropyltriethoxysilane in a mass ratio of 1: 0.15-0.25: 0.4-0.5, and the molar numbers of succinic anhydride and gamma-aminopropyltriethoxysilane are equal.

In some embodiments, in the preparation of the modified metal powder, the mass ratio of the metal powder to the succinic anhydride to the gamma-aminopropyltriethoxysilane is 1: 0.15-0.25: 0.4-0.5, and the molar numbers of the succinic anhydride and the gamma-aminopropyltriethoxysilane are equal.

The invention also aims to provide a preparation method of the spray-free polyamide 66 material.

The preparation method of the spraying-free polyamide 66 material comprises the following steps:

(1) adding the hexamethylene diamine and the adipic acid which are dried in vacuum into a stirring type polymerization reactor, and simultaneously adding the modified montmorillonite, the modified pearlescent pigment, the modified metal powder, the benzoic acid, the toluene diisocyanate, the antioxidant and a proper amount of water; vacuumizing for 3-7 min, introducing nitrogen for 3-7 min, and circulating for 4-8 times in such a way, so that reactants exist in an environment under the protection of nitrogen, and controlling the system pressure in the stirring type polymerization reactor to be 0.1-0.4 MPa;

(2) heating the stirring type polymerization reactor to 265-275 ℃ within 2-4 hours in a sealed manner at a constant speed, adjusting the stirring speed of the stirring type polymerization reactor to 30-50 r/min, wherein when the temperature of the stirring type polymerization reactor reaches 220 ℃, gas is discharged to 1.4MPa, the pressure is maintained at 1.4MPa, after 0.5-3 hours of reaction, the gas is discharged to normal pressure, meanwhile, the temperature is increased to 276-286 ℃, after 0.5-3 hours of continuous reaction at 276-286 ℃, constant temperature continuous vacuum pumping is carried out for 0.1-2 hours, the reaction is finished, and nitrogen is supplemented during discharging, so that the spraying-free polyamide 66 material is obtained.

Introducing nitrogen before the reaction aims to reduce the probability of side reaction; adding a proper amount of water before the reaction has the functions of increasing the pressure in the kettle and transferring heat and mass in the heating process; the purpose of vacuumizing in the reaction process is to remove water generated in the polymerization reaction, so that the forward progress of the polymerization reaction is facilitated.

In some embodiments, the preparation method of the spray-free polyamide 66 material comprises the following steps:

(1) adding the hexamethylene diamine and the adipic acid which are dried in vacuum into a stirring type polymerization reactor, and simultaneously adding the modified montmorillonite, the modified pearlescent pigment, the modified metal powder, the benzoic acid, the toluene diisocyanate, the antioxidant and a proper amount of water; vacuumizing for 4-6 min, introducing nitrogen for 4-6 min, and circulating for 5-7 times in such a way, so that reactants exist in an environment under the protection of nitrogen, and controlling the system pressure in the stirring type polymerization reactor to be 0.2-0.3 MPa;

(2) and heating the stirring type polymerization reactor to 267-273 ℃ within 2-4 hours in a sealed manner at a constant speed, adjusting the stirring speed of the stirring type polymerization reactor to 30-50 r/min, wherein when the temperature of the stirring type polymerization reactor reaches 220 ℃, the gas is discharged to 1.4MPa, the pressure is maintained at 1.4MPa, after the reaction is carried out for 1-2 hours, the gas is discharged to normal pressure, the temperature is increased to 278-284 ℃, after the reaction is carried out for 1-2 hours at 278-284 ℃, the constant temperature is continuously vacuumized for 0.3-1 hour, the reaction is finished, and nitrogen is supplemented during discharging, so that the spraying-free polyamide 66 material is obtained.

The principle of the spraying-free polyamide 66 material is as follows:

because the traditional spraying-free polyamide material uses inorganic components, the compatibility of the inorganic components and polyamide is poor, the problems of flow marks, welding marks and the like easily occur in the processing process of the spraying-free polyamide material, and the mechanical properties such as tensile strength and the like of the polyamide material can be influenced. In order to solve the problems, the invention takes hexamethylenediamine, adipic acid, modified montmorillonite, modified pearlescent pigment and modified metal powder as raw materials, prepares the spraying-free polyamide material by in-situ polymerization, can improve the compatibility between the obtained polyamide material and the modified montmorillonite, the modified pearlescent pigment and the modified metal powder, and simultaneously adds the compatilizer toluene diisocyanate to improve the compatibility between the polyamide material and the modified montmorillonite, the modified pearlescent pigment and the modified metal powder. After the sodium-based montmorillonite is organically modified by caprolactam, the interlayer spacing between montmorillonite layers can be effectively increased, the dispersion of montmorillonite in polyamide resin is facilitated, the crystallization rate of the polyamide resin is improved, the processing time is shortened, and the mechanical property and the flame retardant property of a polyamide material can be improved; after the pearlescent pigment and the metal powder are organically modified by succinic anhydride and gamma-aminopropyltriethoxysilane, carboxyl is carried on the particle surface of the pearlescent pigment and the metal powder, and the carboxyl can react with terminal amino of polyamide and isocyanate group of toluene diisocyanate, so that the compatibility between the pearlescent pigment and the metal powder and the polyamide is improved, and the probability of occurrence of problems such as flow marks, weld marks and the like in the processing process is reduced; the isocyanate group of the toluene diisocyanate can react with the terminal group of the polyamide, the terminal group of the modified montmorillonite, the terminal carboxyl group of the modified pearlescent pigment and the modified metal powder, so that the compatibility between the modified pearlescent pigment and the modified metal powder is improved. In addition, benzoic acid is added into the preparation raw materials of the spraying-free polyamide material, and the intrinsic viscosity of the polyamide material is adjusted by adopting the benzoic acid, so that the processing performance of the spraying-free polyamide material is improved.

The spraying-free polyamide 66 material and the preparation method thereof provided by the invention have the following advantages:

(1) the spraying-free polyamide 66 material disclosed by the invention has excellent mechanical properties, processability and spraying-free effect, has low probability of occurrence of problems such as flow marks, welding marks and the like in the processing process, and can be applied to household appliance parts, automobile interior and exterior trim parts and the like.

(2) The preparation method of the spraying-free polyamide 66 material is simple, can be obtained through in-situ polymerization, and has no need of carrying out all reactions in a solvent, thereby omitting the subsequent complex process of removing the solvent.

(3) In the preparation method of the spray-free polyamide 66 material, low-molecular extractables generated in the polymerization process can be pumped away by high vacuum in the second preparation step, and the residual low-molecular extractables do not influence the performance of the spray-free polyamide 66 material, so that additional extraction equipment is not needed for separating the low-molecular extractables, and time and energy can be saved.

Drawings

FIG. 1 is a flow chart of a preparation process of a spraying-free polyamide 66 material.

Detailed Description

In order to further understand the features and technical means of the present invention and achieve the specific objects and functions, the advantages and spirit of the present invention are further illustrated by the following embodiments.

The reaction mechanism of the spraying-free polyamide 66 material of the invention is as follows (see the preparation process flow chart in figure 1):

wherein R is one of modified montmorillonite, modified pearlescent pigment and modified metal powder.

Mechanism of reaction

From the above reaction formula, the terminal groups of the polyamide and the modified montmorillonite, the terminal carboxyl groups of the modified pearlescent pigment and the modified metal powder can respectively react with the isocyanate group of the toluene diisocyanate, so as to improve the compatibility between the two.

The raw materials used in the embodiment of the invention are as follows:

hexamethylenediamine, available from Henan Shenma Nylon chemical, Inc.

Adipic acid, available from south Henan Shenma Nylon chemical Limited liability company.

Caprolactam available from Hubei Sanning chemical industries, Inc.

Sodium-based montmorillonite, available from Zhejiang Fenghong New materials, Inc.

Silica coated pearlescent pigments, particle size 20 μm, available from merck chemical technology (shanghai) ltd.

Aluminum powder, 20 μm in particle size, was purchased from merck chemical technology (shanghai) ltd.

Succinic anhydride, available from Puyang Puhui electronic materials, Inc.

Gamma-aminopropyltriethoxysilane, available from Shanghai Pont chemical Co., Ltd.

Benzoic acid, available from national pharmaceutical group chemical reagents, ltd.

Toluene diisocyanate, available from national pharmaceutical group chemical agents, ltd.

N, N' -bis (2,2,6, 6-tetramethyl-4-piperidinyl) -1, 3-benzenedicarboxamide, available from Toxongitai chemical Co., Ltd.

Bis (2, 6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphate, available from Shanghai Yaozao Fine chemical Co., Ltd.

Polyamide 66, available from Henan Shenma Nylon chemical Limited liability company.

The preparation of the modified montmorillonite is as follows: dispersing 200g of sodium montmorillonite in 1000mL of distilled water at 80 ℃ to obtain montmorillonite aqueous suspension, dissolving 8g of caprolactam and 15mL of concentrated hydrochloric acid in 200mL of distilled water at 60 ℃ to obtain caprolactam solution, pouring the caprolactam solution into the montmorillonite aqueous suspension, stirring for 4 hours at 90 ℃, performing suction filtration to obtain modified montmorillonite, washing with distilled water, performing vacuum drying, crushing, and sieving with a 200-mesh sieve for later use.

The modified silica-coated pearlescent pigment was prepared as follows: 1mol of succinic anhydride (100g) and 1mol of gamma-aminopropyltriethoxysilane (221g) were dispersed in 1000mL of N, N-dimethylformamide, and after stirring at 60 ℃ for 3 hours, a suspension (3000mL) of ultrasonically dispersed silica-coated pearlescent pigment (500g) of N, N-dimethylformamide was added to the system, and simultaneously distilled water (500mL) was added thereto, and after stirring at 60 ℃ for 3 hours, the suspension was washed with ethanol several times and centrifuged to obtain a modified silica-coated pearlescent pigment.

The modified aluminum powder is prepared as follows: 1mol of succinic anhydride (100g) and 1mol of gamma-aminopropyltriethoxysilane (221g) were dispersed in 1000mL of N, N-dimethylformamide, and after stirring at 60 ℃ for 3 hours, a suspension (3000mL) of ultrasonically dispersed aluminum powder (500g) in N, N-dimethylformamide was added to the system, and simultaneously distilled water (500mL) was added thereto, and after stirring at 60 ℃ for 3 hours, the mixture was washed with ethanol several times and centrifuged to obtain a modified aluminum powder.