A high-tack nylon 12 powder coating and method of making and use thereof

Abstract

The application provides a high-adhesion nylon 12 powder coating, a preparation method and use thereof. The method comprises the following steps: mixing nylon 12 particles and a solvent, dissolving at a high temperature, reducing to a crystallization temperature, and precipitating the nylon 12 powder; adding dodecanolactam, a comonomer, an end-capping agent, a catalyst and water into a polymerization reactor to polymerize and obtain copolymerized nylon 12 particles; dissolving the copolymerized nylon 12 particles in a solvent to form a solution, the solution adheres to the surface of the nylon 12 powder, and after separation, drying and screening, the high-adhesion nylon 12 powder coating is obtained. The powder coating prepared by the method has higher adhesion than common nylon 12 powder coatings, and the addition of the copolymerized nylon 12 can make the surface of the product coating more smooth.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of nylon materials, and particularly relates to a high-adhesion nylon 12 powder coating, a preparation method thereof and application thereof. BACKGROUND

[0002] The powder coating is a new type of coating, which is directly coated in the form of fine powder. The solid system of the powder coating can realize high utilization and maximize the use of resources, and the powder coating belongs to an environmentally-friendly coating. At present, the powder coating can be divided into thermosetting and thermoplastic according to processing and film-forming characteristics.

[0003] The thermosetting powder coating is composed of thermosetting resin, curing agent, pigment, additive and the like, and is crosslinked to form a body structure after reacting with the curing agent under heating. The thermosetting coating does not have recyclability.

[0004] The thermoplastic powder coating takes thermoplastic resin as the main raw material, and can be obtained by sedimentation or cryogenic crushing. The thermoplastic powder coating does not need a complex curing process, and can form a film by heating, leveling, and cooling and solidifying, and has recyclability. The nylon powder coating is a kind of thermoplastic powder coating.

[0005] The nylon 12 has good mechanical properties and wear resistance, and has good weather resistance and other advantages. Therefore, the nylon 12 powder coating is widely used in metal coating. The coating prepared from the nylon 12 powder coating has excellent properties such as resistance to detergents, resistance to cold and hot water alternation, smooth surface, excellent wear resistance and stain resistance.

[0006] The nylon 12 powder coating is mainly used in household appliances and automobiles. The use environment of household appliances and automobiles is relatively complex and changeable, and may be in contact with high humidity, high temperature, acid and alkali, oil and salt for a long time. Insufficient adhesion may cause peeling, delamination, corrosion and other problems of the product. Improving the adhesion of the product can improve the quality and service life of the product.

[0007] In summary, the current nylon 12 powder coating field needs to solve the product defects caused by insufficient adhesion. SUMMARY

[0008] One of the purposes of the application is to provide a preparation method of a high-adhesion nylon 12 powder coating. The powder coating prepared by the method has higher adhesion than ordinary nylon 12 powder coatings. The addition of the copolymerized nylon 12 can make the surface of the product coating more smooth.

[0009] To achieve the above-mentioned purposes, the application adopts the following technical scheme:

[0010] A preparation method of a high-adhesion nylon 12 powder coating, the method comprising the following steps:

[0011] Optionally, S1: mixing nylon 12 particles and solvent, warming to dissolve, lowering to crystallization temperature, and precipitating nylon 12 powder;

[0012] S2: adding lauryl lactam, comonomer, end-capping agent, catalyst, and water into a polymerization reactor to polymerize and obtain copolymerized nylon 12 particles;

[0013] S3: dissolving the copolymerized nylon 12 particles in a solvent to form a solution, and adhering the solution to the surface of the nylon 12 powder, and then separating, drying, and sieving to obtain high-adhesion nylon 12 powder coating.

[0014] The copolymerized nylon 12 has a slow crystallization speed, and thus has more time to fuse with the contact surface during the melting and cooling process, and the mechanism is similar to that of the nylon hot melt adhesive. The inventors have found in research that the addition of the copolymerized nylon 12 can reduce the crystallization speed during the nylon 12 powder coating process, and thus improve the adhesion. The addition of the copolymerized nylon 12 can reduce the crystallization size and speed of the nylon 12 matrix powder, and is conducive to improving the smoothness of the coated surface of the product.

[0015] In an embodiment of the present application, the relative viscosity of the nylon 12 in S1 is in the range of 1.4-2.5, preferably 1.6-2.1.

[0016] In an embodiment of the present application, the solvent in S1 is a polar alcohol solvent, preferably one or more of ethanol, benzyl alcohol, and hexafluoroisopropyl alcohol.

[0017] In an embodiment of the present application, the temperature for warming in S1 is in the range of 140-200℃.

[0018] In an embodiment of the present application, the concentration of the solution obtained by dissolving in S1 is in the range of 1-60wt%, preferably 10-40wt%.

[0019] In an embodiment of the present application, the crystallization temperature in S1 is in the range of 25-139℃.

[0020] In an embodiment of the present application, the comonomer in S2 is a combination of lactam monomers, organic diacid monomers, and organic diamine monomers; preferably a combination of C6-C12 lactam monomers, C2-C30 organic diacid monomers, and C2-C30 organic diamine monomers; more preferably a combination of caprolactam, one or more of hexamethylenediamine, pentanediamine, decanediamine, and dodecanediamine, and one or more of adipic acid, sebacic acid, dodecanedioic acid, tridecanedioic acid, and tetradecanedioic acid; preferably, the molar ratio of carboxyl groups to amino groups in the combination is 1:1. It is well known in the art that the molar ratio of carboxyl groups to amino groups in the combination is most suitable for the reaction ratio, but small adjustments in the range do not significantly affect the actual effect.

[0021] In one embodiment of the present application, the mass proportion of laurolactam in all comonomers in S2 is 1%-99%.

[0022] In one embodiment of the present application, the end-capping agent in S2 is an organic carboxylic acid, preferably an organic mono-acid and / or an organic di-acid; preferably, the amount of end-capping agent added is 0.1-3wt% based on the total mass of laurolactam monomer and comonomer.

[0023] In one embodiment of the present application, the catalyst in S2 is an oxygen-containing phosphorus-based catalyst, preferably containing one or more of phosphate, phosphite, and hypophosphite; preferably, the amount of catalyst added is 0.1-3wt% based on the total mass of laurolactam monomer, comonomer, and end-capping agent.

[0024] In one embodiment of the present application, the amount of water added in S2 is 1-30wt% based on the total mass of laurolactam monomer.

[0025] In one embodiment of the present application, the melting point of the copolymerized nylon 12 particles in S2 is in the range of 80-180℃. The degree of breaking the regularity of the molecular chain through copolymerization, and the melting point of the copolymerized product are controlled by adjusting the type and proportion of laurolactam and comonomer.

[0026] In one embodiment of the present application, the solvent in S3 is a polar polyol, preferably one or more of benzyl alcohol, hexafluoroisopropyl alcohol, and ethanol; preferably, the concentration of the copolymerized nylon 12 solution is 1-40wt%.

[0027] In one embodiment of the present application, the amount of the adhered copolymerized nylon 12 in S3 is 0.1-99.9wt%, preferably 1-10wt%, based on the total mass of nylon 12 powder.

[0028] In one embodiment of the present application, the copolymerized nylon 12 solution in S3 is adhered to the nylon 12 powder by one or more of dropwise addition stirring, atomized spraying, and powder soaking, preferably atomized spraying.

[0029] Another object of the present application is to provide a high-adhesion nylon 12 powder coating.

[0030] A high-adhesion nylon 12 powder coating is obtained by the above-mentioned preparation method, and the powder coating is nylon 12 powder to which copolymerized nylon 12 is adhered.

[0031] In one embodiment of the present application, the D50 particle size of the powder coating is 100-200 microns.

[0032] Still another object of the present application is to provide a use of a high-adhesion nylon 12 powder coating.

[0033] Use of a high-adhesion nylon 12 powder coating obtained by the above method or the powder coating described above, the nylon 12 powder coating being used for powder coating of conveying pipes, containers, kitchen and bathroom, industrial mechanical parts.

[0034] Compared with the prior art, the present application has the following positive effects:

[0035] (1) Better adhesion in use, which can increase product quality and service life, and the addition of copolymerized nylon 12 can make the surface of the product coating more smooth.

[0036] (2) The method can be applied to different scenarios by adjusting the performance of the copolymerized nylon 12 in combination with the nylon 12 powder coating. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 The powder particle size of the base nylon 12 powder in Example 1 is 150 microns;

[0038] Figure 2 The nylon 12 powder coating obtained in Example 1. DETAILED DESCRIPTION

[0039] The following examples are further illustrations of the technical solutions provided by the present application, but the present application is not limited to the listed examples, and also includes any other known changes within the scope of the present application.

[0040] Main raw material information:

[0041]

[0042] The relative viscosity data in the table are obtained by ASTM D789-2006 test.

[0043] The adhesion test method refers to the patent GB / T 9286-1998 Crosshatch Test for Paint and Varnish Films, the crosshatch interval is 2mm; the adhesive tape with adhesion greater than 10N / 25mm is covered on the crosshatched coating, and is pressed to remove the air under the adhesive tape, then the adhesive tape is quickly pulled up at an angle perpendicular to the surface of the coating, and the rating is according to GB / T9286.

[0044] The testing equipment is a crosshatch knife, which is used to evenly draw a certain size of square, and the adhesion of the coating to the substrate is evaluated by evaluating the completeness of the square, which is expressed by 'grade'. It is mainly used for the determination of the adhesion of organic coatings by crosshatch method, and is not only suitable for laboratory, but also for construction site under various conditions. It is designed and manufactured according to ISO 2409-1992 standard, and is suitable for GB / T9286-98, BS 3900E6 / ASTM D3359.

[0045] Example 1

[0046] Nylon 12 (L2000) particles 20 kg, ethanol 100 kg were added into a precipitation device, the temperature was raised to 160°C, the stirring paddle speed was set to 100 r / min, until the nylon 12 was completely dissolved; then, while stirring, slowly cooled to 130°C, the nylon 12 particles were precipitated to form spherulitic powder; the obtained powder was vacuum dried at 80°C for 6h to remove the ethanol solvent; then the dried powder was added to a grinding device and ground for 1h, the caked powder was ground and dispersed; finally, the ground powder was added to a screening device, the upper limit of the screen size was set to 300 microns, and the lower limit of the screen size was set to 50 microns, to obtain the base nylon 12 powder, the powder particle size D50 was 150 microns.

[0047] Twelve lactam, caprolactam, hexamethylene diamine, adipic acid, a total of 10 kg were added into a polymerization reactor, the copolymerized nylon 12 was PA6 / 66 / 12 copolymer, the copolymerization ratio PA6 / 66 / 12 mass ratio was 15:75:10, the water amount was 20wt% of the total monomer mass, the end-capping agent benzoic acid was 0.4% of the total monomer mass, the catalyst sodium hypophosphite was 0.3% of the total monomer mass, the obtained copolymerized nylon 12 melting point was 175°C, the temperature of the reactor was set to 250°C for ring-opening reaction for 5h, the pressure was slowly released to normal pressure, and then the temperature was slowly reduced to 200°C, and the copolymerized nylon 12 particles were obtained by discharging.

[0048] The copolymerized nylon 12 particles were dissolved in benzyl alcohol to prepare a copolymerized nylon 12 dilute solution with a concentration of 5%. 8L of the above solution was atomized and sprayed into 20 kg of nylon 12 powder at a speed of 4L / h, then a high-speed mixer was used, the speed was set to 150 r / min, and the dispersion treatment was carried out for 30 min, the mass of the copolymerized nylon accounted for 2% of the total mass of the nylon 12 powder. The treated nylon 12 powder was vacuum dried at 80°C for 6h, then added to a screening device, the upper limit of the screen size was set to 300 microns, and the lower limit of the screen size was set to 50 microns, to obtain a powder with a particle size D50 of 150 microns. Coated on the sample plate and tested by the grid test.

[0049] Example 2

[0050] Nylon 12 (L2000) particles 20 kg, ethanol 100 kg were added to a precipitation device, heated to 160°C, and the stirring paddle speed was set to 100 r / min until the nylon 12 was completely dissolved. Then, while stirring, the temperature was slowly reduced to 130°C, and the nylon 12 particles were precipitated to form spherulitic powder. The obtained powder was vacuum dried at 80°C for 6 h to remove the ethanol solvent. Then, the dried powder was added to a grinding device to grind and disperse the caked powder. Finally, the ground powder was added to a screening device, and the upper limit of the screen size was set to 300 microns and the lower limit of the screen size was set to 50 microns to obtain the base nylon 12 powder. The powder particle size D50 was 150 microns.

[0051] A total of 10 kg of lauryl lactam, caprolactam, hexamethylene diamine, and adipic acid were added to a polymerization reactor. The copolymerized nylon 12 was a PA6 / 66 / 12 copolymer, and the copolymerization ratio of PA6 / 66 / 12 was 15:75:10 by mass. The amount of water was 20 wt% of the total monomer mass, the amount of end-capping agent benzoic acid was 0.4% of the total monomer mass, and the amount of catalyst sodium hypophosphite was 0.3% of the total monomer mass. The melting point of the obtained copolymerized nylon 12 was 175°C. The temperature of the reactor was set to 250°C for ring-opening reaction for 5 h, and then the pressure was slowly released to normal pressure. After that, the temperature was slowly reduced to 200°C, and the copolymerized nylon 12 particles were discharged.

[0052] The copolymerized nylon 12 particles were dissolved in benzyl alcohol to prepare a copolymerized nylon 12 dilute solution with a concentration of 5%. 16 L of the above solution was atomized and sprayed into 20 kg of nylon 12 powder at a speed of 4 L / h, and then a high-speed mixer was used for dispersion treatment at a speed of 150 r / min for 30 min. The mass of the copolymerized nylon 12 accounted for 4% of the total mass of the nylon 12 powder. The treated nylon 12 powder was vacuum dried at 80°C for 6 h, and then added to a screening device. The upper limit of the screen size was set to 300 microns and the lower limit of the screen size was set to 50 microns to obtain a powder with a particle size D50 of 150 microns. The powder was coated onto a sample plate and subjected to a grid test.

[0053] Example 3

[0054] Nylon 12 (L2000) particles 20 kg, ethanol 100 kg were added to a precipitation device, heated to 160°C, and the stirring paddle speed was set to 100 r / min until the nylon 12 was completely dissolved. Then, while stirring, the temperature was slowly reduced to 130°C, and the nylon 12 particles were precipitated to form spherulitic powder. The obtained powder was vacuum dried at 80°C for 6 h to remove the ethanol solvent. Then, the dried powder was added to a grinding device to grind and disperse the caked powder. Finally, the ground powder was added to a screening device, and the upper limit of the screen size was set to 300 microns and the lower limit of the screen size was set to 50 microns to obtain the base nylon 12 powder. The powder particle size D50 was 150 microns.

[0055] Put 10 kg of laurolactam, caprolactam, hexamethylene diamine, adipic acid into the polymerization reactor, the copolymerized nylon 12 is PA6 / 66 / 12 copolymer, the copolymerization ratio of PA6 / 66 / 12 is 15:75:10, the water amount is 20 wt% of the total monomer mass, the end-capping agent benzoic acid is 0.4% of the total monomer mass, the catalyst sodium hypophosphite is 0.3% of the total monomer mass, the obtained copolymerized nylon 12 has a melting point of 175℃, the temperature of the reactor is set to 250℃ for ring-opening reaction for 5h, the pressure is slowly released to normal pressure, and then the temperature is slowly reduced to 200℃, and the copolymerized nylon 12 particles are obtained by discharging.

[0056] The copolymerized nylon 12 particles are dissolved in benzyl alcohol to prepare a copolymerized nylon 12 dilute solution with a concentration of 5%. 24L of the above solution is atomized and sprayed into 20 kg of nylon 12 powder at a speed of 4L / h, and then a high-speed mixer is used for dispersion treatment for 30 min, with a rotation speed of 150 r / min. The mass of the copolymerized nylon accounts for 6% of the total mass of the nylon 12 powder. The treated nylon 12 powder is vacuum dried at 80℃ for 6h, and then a screening device is added, with the upper limit of the screen size set to 300 microns and the lower limit of the screen size set to 50 microns, to obtain a powder with a particle size D50 of 150 microns. Coating is performed on a sample plate, and a cross-hatch test is performed.

[0057] Example 4

[0058] Put 20 kg of nylon 12 (L2000) particles and 100 kg of ethanol into a precipitation device, heat to 160℃, and set the stirring paddle rotation speed to 100 r / min until the nylon 12 is completely dissolved; then, while stirring, slowly cool to 130℃, and the nylon 12 particles are precipitated to form spherulitic powder; the obtained powder is vacuum dried at 80℃ for 6h to remove the ethanol solvent; then, the dried powder is added to a grinding device to grind and disperse the caked powder; finally, the ground powder is added to a screening device, with the upper limit of the screen size set to 300 microns and the lower limit of the screen size set to 50 microns, to obtain the base nylon 12 powder, with a powder particle size D50 of 150 microns.

[0059] Put 10 kg of laurolactam, caprolactam, hexamethylene diamine, adipic acid into the polymerization reactor, the copolymerized nylon 12 is PA6 / 66 / 12 copolymer, the copolymerization ratio of PA6 / 66 / 12 is 15:75:10, the water amount is 20 wt% of the total monomer mass, the end-capping agent benzoic acid is 0.4% of the total monomer mass, the catalyst sodium hypophosphite is 0.3% of the total monomer mass, the obtained copolymerized nylon 12 has a melting point of 175℃, the temperature of the reactor is set to 250℃ for ring-opening reaction for 5h, the pressure is slowly released to normal pressure, and then the temperature is slowly reduced to 200℃, and the copolymerized nylon 12 particles are obtained by discharging.

[0060] The copolymerized nylon 12 particles were dissolved in benzyl alcohol to prepare a copolymerized nylon 12 dilute solution with a concentration of 5%. 32 L of the above solution was atomized and sprayed into 20 kg of nylon 12 powder at a speed of 4 L / h, and then a high-speed mixer was used for dispersion treatment at a speed of 150 r / min for 30 min, and the mass of the copolymerized nylon accounted for 8% of the total mass of the nylon 12 powder. The treated nylon 12 powder was vacuum dried at 80°C for 6 h, and then a screening device was added, with the upper limit of the screen size being set to 300 microns and the lower limit of the screen size being set to 50 microns, to obtain a powder with a particle size D50 of 150 microns. The powder was coated on a sample plate for a grid test.

[0061] Example 5

[0062] Nylon 12 (L2000) particles 20 kg, ethanol 100 kg were added to a precipitation device, and the temperature was raised to 160°C, and the stirring paddle was set to a speed of 100 r / min, until the nylon 12 was completely dissolved; then, while stirring, the temperature was slowly reduced to 130°C, and the nylon 12 particles were precipitated to form spherulitic powder; the obtained powder was vacuum dried at 80°C for 6 h to remove the ethanol solvent; then the dried powder was added to a grinding device to grind and disperse the caked powder; finally, the ground powder was added to a screening device, with the upper limit of the screen size being set to 300 microns and the lower limit of the screen size being set to 50 microns, to obtain a basic nylon 12 powder with a powder particle size D50 of 150 microns.

[0063] A total of 10 kg of lauryl lactam, caprolactam, hexamethylene diamine, and adipic acid were added to a polymerization reactor, the copolymerized nylon 12 was a PA6 / 66 / 12 copolymer, the copolymerization ratio of PA6 / 66 / 12 was 15:75:10 by mass, the water amount was 20 wt% of the total monomer mass, the end-capping agent benzoic acid was 0.4% of the total monomer mass, and the catalyst sodium hypophosphite was 0.3% of the total monomer mass, the obtained copolymerized nylon 12 had a melting point of 175°C, the temperature of the reactor was set to 250°C for ring-opening reaction for 5 h, the pressure was slowly released to normal pressure, and then the temperature was slowly reduced to 200°C, and the copolymerized nylon 12 particles were obtained.

[0064] The copolymerized nylon 12 particles were dissolved in benzyl alcohol to prepare a copolymerized nylon 12 dilute solution with a concentration of 5%. 32 L of the above solution was atomized and sprayed into 20 kg of nylon 12 powder at a speed of 4 L / h, and then a high-speed mixer was used for dispersion treatment at a speed of 150 r / min for 30 min, and the mass of the copolymerized nylon accounted for 8% of the total mass of the nylon 12 powder. The treated nylon 12 powder was vacuum dried at 80°C for 6 h, and then a screening device was added, with the upper limit of the screen size being set to 300 microns and the lower limit of the screen size being set to 50 microns, to obtain a powder with a particle size D50 of 150 microns. The powder was coated on a sample plate for a grid test.

[0065] Example 6

[0066] Nylon 12 (L1000) particles 20 kg, ethanol 70 kg were added to a precipitation device, the temperature was raised to 140°C, the stirring paddle speed was set to 100 r / min, until the nylon 12 was completely dissolved; then, while stirring, slowly cooled to 60°C, the nylon 12 particles were precipitated to form spherulitic powder; the obtained powder was vacuum dried at 80°C for 6h to remove the ethanol solvent; then the dried powder was added to a grinding device, the agglomerated powder was ground and dispersed; finally, the ground powder was added to a screening device, the upper limit of the screen size was set to 300 microns, and the lower limit of the screen size was set to 50 microns, to obtain the base nylon 12 powder, the powder particle size D50 was 190 microns.

[0067] Twelve lactam, caprolactam, hexamethylene diamine, adipic acid, a total of 10 kg were added to a polymerization reactor, the copolymerized nylon 12 was PA6 / 66 / 12 copolymer, the copolymerization ratio PA6 / 66 / 12 mass ratio was 15:75:10, the water amount was 10wt% of the total monomer mass, the end-capping agent benzoic acid was 1.0% of the total monomer mass, the catalyst sodium hypophosphite was 1.0% of the total monomer mass, the obtained copolymerized nylon 12 melting point was 175°C, the temperature of the reactor was set to 250°C for ring-opening reaction for 5h, the pressure was slowly released to normal pressure, and then the temperature was slowly reduced to 200°C, and the copolymerized nylon 12 particles were discharged.

[0068] The copolymerized nylon 12 particles were dissolved in benzyl alcohol to prepare a copolymerized nylon 12 dilute solution with a concentration of 10%. 20L of the above solution was atomized and sprayed into 20kg of nylon 12 powder at a speed of 2L / h, then a high-speed mixer was used, the speed was set to 150r / min, and the copolymerized nylon was dispersed for 30min, the mass of the copolymerized nylon accounted for 10% of the total mass of the nylon 12 powder. The treated nylon 12 powder was vacuum dried at 80°C for 6h, then added to a screening device, the upper limit of the screen size was set to 300 microns, and the lower limit of the screen size was set to 50 microns, to obtain a powder with a particle size D50 of 190 microns. Coated on a sample plate for hatch testing.

[0069] Example 7

[0070] Nylon 12 (L3000) particles 20 kg, ethanol 200 kg were added to a precipitation device, the temperature was raised to 190°C, the stirring paddle speed was set to 100 r / min, until the nylon 12 was completely dissolved; then, while stirring, slowly cooled to 138°C, the nylon 12 particles were precipitated to form spherulitic powder; the obtained powder was vacuum dried at 80°C for 6h to remove the ethanol solvent; then the dried powder was added to a grinding device, the agglomerated powder was ground and dispersed; finally, the ground powder was added to a screening device, the upper limit of the screen size was set to 300 microns, and the lower limit of the screen size was set to 50 microns, to obtain the base nylon 12 powder, the powder particle size D50 was 110 microns.

[0071] The total amount of laurolactam, caprolactam, hexamethylenediamine and adipic acid is 10 kg, which is added into a polymerization reactor, the copolymerized nylon 12 is PA6 / 66 / 12 copolymer, the copolymerization ratio of PA6 / 66 / 12 is 15:75:10, the amount of water is 30 wt% of the total monomer mass, the amount of end-capping agent benzoic acid is 0.2% of the total monomer mass, and the amount of catalyst sodium hypophosphite is 0.1% of the total monomer mass, the melting point of the obtained copolymerized nylon 12 is 175℃, the temperature of the reactor is set to 250℃ for ring-opening reaction for 5h, the pressure is slowly released to normal pressure, and then the temperature is slowly reduced to 200℃, and the copolymerized nylon 12 particles are obtained by discharging.

[0072] The copolymerized nylon 12 particles are dissolved in benzyl alcohol to prepare a copolymerized nylon 12 dilute solution with a concentration of 2%. 100L of the above solution is atomized and sprayed into 20kg of nylon 12 powder at a speed of 10L / h, and then a high-speed mixer is used for dispersion treatment for 30min, with the rotation speed set to 150r / min, the mass of the copolymerized nylon accounts for 10% of the total mass of the nylon 12 powder. The treated nylon 12 powder is vacuum dried at 80℃ for 6h, and then a screening device is added, with the upper limit of the screen size set to 300 microns and the lower limit of the screen size set to 50 microns, to obtain a powder with a particle size D50 of 110 microns. Coating onto a sample plate is performed for the cross-hatch test.

[0073] Example 8

[0074] Nylon 12 (L2000) particles 20kg, ethanol 100kg are added into a precipitation device, the temperature is raised to 160℃, and the stirring paddle rotation speed is set to 100r / min, until the nylon 12 is completely dissolved; then, while stirring, the temperature is slowly reduced to 130℃, and the nylon 12 particles are precipitated to form spherulitic powder; the obtained powder is vacuum dried at 80℃ for 6h to remove the ethanol solvent; then the dried powder is added to a grinding device to grind and disperse the caked powder; finally, the ground powder is added to a screening device, with the upper limit of the screen size set to 300 microns and the lower limit of the screen size set to 50 microns, to obtain the base nylon 12 powder, with a powder particle size D50 of 150 microns.

[0075] The total amount of laurolactam, caprolactam, hexamethylenediamine and adipic acid is 10 kg, which is added into a polymerization reactor, the copolymerized nylon 12 is PA11 / 66 / 12 copolymer, the copolymerization ratio of PA11 / 66 / 12 is 10:80:10, the amount of water is 30 wt% of the total monomer mass, the amount of end-capping agent benzoic acid is 0.4% of the total monomer mass, and the amount of catalyst phosphoric acid is 0.3% of the total monomer mass, the melting point of the obtained copolymerized nylon 12 is 169℃, the temperature of the reactor is set to 250℃ for ring-opening reaction for 5h, the pressure is slowly released to normal pressure, and then the temperature is slowly reduced to 200℃, and the copolymerized nylon 12 particles are obtained by discharging.

[0076] Copolymer nylon 12 particles were dissolved in hexafluoroisopropanol to prepare a 5% copolymer nylon 12 solution. 40 L of this solution was atomized and sprayed onto 20 kg of nylon 12 powder at a rate of 4 L / h. The powder was then dispersed for 30 min using a high-speed mixer at 150 rpm, with the copolymer nylon accounting for 10% of the total mass of the nylon 12 powder. The treated nylon 12 powder was vacuum dried at 80°C for 6 h. After drying, it was added to a sieving device with an upper limit of 300 μm and a lower limit of 50 μm, yielding powder with a particle size D50 of 150 μm. This powder was then coated onto a sample for a cross-cut adhesion test.

[0077] Example 9

[0078] 20 kg of Nylon 12 (L2000) particles and 100 kg of ethanol were added to a precipitation apparatus and heated to 160°C. The stirring speed was set to 100 r / min until the Nylon 12 was completely dissolved. Then, while stirring, the temperature was slowly lowered to 130°C, and the Nylon 12 particles precipitated to form spherulite powder. The obtained powder was vacuum dried at 80°C for 6 hours to remove the ethanol solvent. The dried powder was then added to a grinding device to grind and disperse the agglomerated powder. Finally, the ground powder was added to a sieving device with the upper limit of the sieve size set to 300 micrometers and the lower limit of the sieve size set to 50 micrometers to obtain basic Nylon 12 powder with a particle size D50 of 150 micrometers.

[0079] A total of 10 kg of dodecyl lactam, caprolactam, hexamethylenediamine, and adipic acid were added to a polymerization reactor. The copolymer nylon 12 was a PA6 / 66 / 12 copolymer with a copolymerization ratio of PA6 / 66 / 12 of 10:25:65 by mass. The amount of water was 20 wt% of the total monomer mass, the end-capping agent benzoic acid was 0.4% of the total monomer mass, and the catalyst sodium hypophosphite was 0.3% of the total monomer mass. The resulting copolymer nylon 12 had a melting point of 139℃. The reactor temperature was controlled at 250℃ for 5 hours for ring-opening reaction. After slowly releasing the pressure to atmospheric pressure, the temperature was slowly reduced to 200℃, and the copolymer nylon 12 particles were discharged.

[0080] Copolymer nylon 12 particles were dissolved in benzyl alcohol to prepare a 5% copolymer nylon 12 dilute solution. 40 L of this solution was atomized and sprayed onto 20 kg of nylon 12 powder at a rate of 4 L / h. The powder was then dispersed for 30 min using a high-speed mixer at 150 rpm, with the copolymer nylon accounting for 10% of the total mass of the nylon 12 powder. The treated nylon 12 powder was vacuum dried at 80°C for 6 h. After drying, it was added to a sieving device with an upper limit of 300 μm and a lower limit of 50 μm for the sieve size, yielding powder with a particle size D50 of 150 μm. This powder was then coated onto a sample for a cross-cut adhesion test.

[0081] Example 10

[0082] Nylon 12 (L2000) particles 20 kg, ethanol 100 kg were added into a precipitation device, the temperature was raised to 160 °C, the stirring paddle speed was set to 100 r / min, until the nylon 12 was completely dissolved; then, while stirring, slowly cooled to 130 °C, the nylon 12 particles were precipitated to form spherulitic powder; the obtained powder was vacuum dried at 80 °C for 6 h to remove the ethanol solvent; then the dried powder was added to a grinding device, and the caked powder was ground and dispersed; finally, the ground powder was added to a screening device, the upper limit of the screen size was set to 300 microns, and the lower limit of the screen size was set to 50 microns, to obtain the base nylon 12 powder, and the powder particle size D50 was 150 microns.

[0083] Twelve lactam, caprolactam, hexamethylene diamine, adipic acid, a total of 10 kg were added into a polymerization reactor, the copolymerized nylon 12 was a PA6 / 66 / 12 copolymer, the copolymerization ratio of PA6 / 66 / 12 was 15:75:10 by mass, the water amount was 20 wt% of the total monomer mass, the end-capping agent benzoic acid was 0.4% of the total monomer mass, and the catalyst sodium hypophosphite was 0.3% of the total monomer mass, the obtained copolymerized nylon 12 had a melting point of 175 °C, the temperature of the reactor was set to 250 °C for ring-opening reaction for 5 h, the pressure was slowly released to normal pressure, and then the temperature was slowly reduced to 200 °C, and the copolymerized nylon 12 particles were obtained by discharging.

[0084] The copolymerized nylon 12 particles were dissolved in benzyl alcohol to prepare a copolymerized nylon 12 dilute solution with a concentration of 5%. 40 L of the above solution was uniformly dropped into 20 kg of nylon 12 powder at a speed of 1 L / h, and then a high-speed mixer was used for dispersion treatment for 30 min, with a speed of 150 r / min, and the mass of the copolymerized nylon 12 accounted for 10% of the total mass of the nylon 12 powder. The treated nylon 12 powder was vacuum dried at 80 °C for 6 h, and then added to a screening device, with the upper limit of the screen size set to 300 microns and the lower limit of the screen size set to 50 microns, to obtain a powder with a particle size D50 of 150 microns. Coating onto a sample plate was performed for cross-hatch testing.

[0085] Comparative Example 1

[0086] Prior art preparation.

[0087] Nylon 12 particles 20 kg, ethanol 100 kg were added to the precipitation device, the temperature was raised to 160°C, the stirring paddle speed was set to 100 r / min, until the nylon 12 was completely dissolved; then, while stirring, slowly cool to 130°C, the nylon 12 particles precipitate to form spherulitic powder; the obtained powder was vacuum dried at 80°C for 6h, to remove the ethanol solvent; then the dried powder was added to the grinding equipment, the agglomerated powder was ground and dispersed; finally, the ground powder was added to the screening device, the upper limit of the screen size was set to 300 microns, and the lower limit of the screen size was set to 50 microns, to obtain the base nylon 12 powder, the powder particle size D50 was 150 microns. Coated on the sample plate, and tested by the grid test.

[0088] Comparative Example 2

[0089] Compared with Example 5, the difference is that a non-comonomer is used for coating.

[0090] Nylon 12 particles 20 kg, ethanol 100 kg were added to the precipitation device, the temperature was raised to 160°C, the stirring paddle speed was set to 100 r / min, until the nylon 12 was completely dissolved; then, while stirring, slowly cool to 130°C, the nylon 12 particles precipitate to form spherulitic powder; the obtained powder was vacuum dried at 80°C for 6h, to remove the ethanol solvent; then the dried powder was added to the grinding equipment, the agglomerated powder was ground and dispersed; finally, the ground powder was added to the screening device, the upper limit of the screen size was set to 300 microns, and the lower limit of the screen size was set to 50 microns, to obtain the base nylon 12 powder, the powder particle size D50 was 150 microns.

[0091] 10 kg of caprolactam was added to the polymerization reactor, the amount of water was 20 wt% of the total mass of the monomer, the amount of end-capping agent benzoic acid was 0.4% of the total mass of the monomer, and the amount of catalyst sodium hypophosphite was 0.3% of the total mass of the monomer. The melting point of the obtained nylon 6 was 224°C, the temperature of the reactor was set to 250°C for ring-opening reaction for 5h, the pressure was slowly released to normal pressure, and then the temperature was slowly reduced to 200°C, and the nylon 6 particles were discharged.

[0092] The copolymerized nylon 12 particles were dissolved in benzyl alcohol to prepare a 5% nylon 6 dilute solution. 40L of the above solution was atomized and sprayed into 20kg of nylon 12 powder at a speed of 4L / h, then a high-speed mixer was used, the speed was set to 150r / min, and the dispersion treatment was carried out for 30min, the mass of nylon 6 accounted for 10% of the total mass of nylon 12 powder. The treated nylon 12 powder was vacuum dried at 80°C for 6h, and then added to the screening device, the upper limit of the screen size was set to 300 microns, and the lower limit of the screen size was set to 50 microns, to obtain a powder with a particle size D50 of 150 microns. Coated on the sample plate, and tested by the grid test.

[0093] Comparative Example 3

[0094] Comparing with Example 5, the difference is that the comonomer beyond the melting point range is used for coating.

[0095] Put 20 kg of nylon 12 particles and 100 kg of ethanol into a precipitation device, heat to 160℃, set the stirring paddle speed to 100 r / min, until the nylon 12 is completely dissolved; then, while stirring, slowly cool to 130℃, the nylon 12 particles are precipitated to form spherulitic powder; the obtained powder is vacuum dried at 80℃ for 6h to remove the ethanol solvent; then the dried powder is added to a grinding device, and the caked powder is ground and dispersed; finally, the ground powder is added to a screening device, set the upper limit of the screen size to 300 microns, and the lower limit of the screen size to 50 microns, to obtain the base nylon 12 powder, the powder particle size D50 is 150 microns.

[0096] Put 10 kg of lauryl lactam, caprolactam, hexamethylene diamine, and adipic acid into a polymerization reactor, the copolymerized nylon 12 is PA6 / 66 / 12 copolymer, the copolymerization ratio of PA6 / 66 / 12 is 20:75:5 by mass, the water amount is 20wt% of the total monomer mass, the end-capping agent benzoic acid is 0.4% of the total monomer mass, and the catalyst sodium hypophosphite is 0.3wt% of the total monomer mass, the obtained copolymerized nylon 12 has a melting point of 190℃, the temperature of the reactor is set to 250℃ for ring-opening reaction for 5h, the pressure is slowly released to normal pressure, and then the temperature is slowly reduced to 200℃, and the copolymerized nylon 12 particles are obtained by discharging.

[0097] The copolymerized nylon 12 particles are dissolved in benzyl alcohol to prepare a copolymerized nylon 12 dilute solution with a concentration of 5%. 40L of the above solution is atomized and sprayed into 20 kg of nylon 12 powder at a speed of 4L / h, then a high-speed mixer is used for dispersion treatment for 30min, the mass of the copolymerized nylon 12 accounts for 10% of the total mass of the nylon 12 powder. The treated nylon 12 powder is vacuum dried at 80℃ for 6h, and then added to a screening device, set the upper limit of the screen size to 300 microns, and the lower limit of the screen size to 50 microns, to obtain a powder with a particle size D50 of 150 microns. Coated on a sample plate for hatch test.

[0098] The test results of Comparative Examples 1-3 and Examples 1-5 are as follows:

[0099]

[0100] In summary, the prepared nylon 12 powder coating can effectively improve the adhesion. Those skilled in the art can understand that some modifications or adjustments can be made to the present application under the guidance of the present specification. These modifications or adjustments should also be within the scope defined by the claims of the present application.

Claims

1. A process for the preparation of a high build nylon 12 powder coating characterized in that, The method comprises the following steps: Optionally, S1: mixing nylon 12 particles and solvent, warming to dissolve, lowering to crystallization temperature, and precipitating nylon 12 powder; S2: adding lauryl lactam, comonomer, end-capping agent, catalyst, and water into a polymerization reactor to polymerize and obtain copolymerized nylon 12 particles; S3: dissolving the copolymerized nylon 12 particles in a solvent to form a solution, the solution adheres to the surface of the nylon 12 powder, and after separation, drying, and screening, high-adhesion nylon 12 powder coating is obtained; The copolymerized nylon 12 particles in S2 have a melting point range of 80-180℃.

2. The production method according to claim 1, characterized by, The relative viscosity of the nylon 12 in S1 ranges from 1.4 to 2.5; And / or, the solvent in S1 is a polar alcohol solvent; And / or, the temperature for warming in S1 is 140℃-200℃; And / or, the concentration of the solution obtained by dissolving in S1 is 1-60wt%; And / or, the crystallization temperature in S1 is 25℃-139℃.

3. The method of claim 2, wherein, The relative viscosity of the nylon 12 in S1 ranges from 1.6 to 2.1; And / or, the solvent in S1 is one or more of ethanol, benzyl alcohol, and hexafluoroisopropyl alcohol; And / or, the concentration of the solution obtained by dissolving in S1 is 10-40wt%.

4. The method of claim 1, wherein, The comonomer in S2 is a combination of lactam monomers, organic diacid monomers, and organic diamine monomers; And / or, the mass proportion of lauryl lactam in all comonomers in S2 is 1%-99%; And / or, the end-capping agent in S2 is an organic carboxylic acid; And / or, the catalyst in S2 is an oxygen-containing phosphorus-based catalyst; And / or, the amount of water added in S2 is 1-30wt%, based on the total mass of added lauryl lactam monomers.

5. The preparation method according to claim 4, characterized in that, The comonomer in S2 is a combination of C6-C12 lactam monomers, C2-C30 organic diacid monomers, and C2-C30 organic diamine monomers; The molar ratio of carboxyl groups to amino groups in the combination is 1:1; And / or, the end-capping agent in S2 is an organic monoacid and / or an organic diacid; The amount of end-capping agent added in S2 is 0.1-3wt%, based on the total mass of added lauryl lactam monomers and comonomers; And / or, the catalyst in S2 is one or more of phosphate-containing, phosphite-containing, and hypophosphite-containing; The amount of catalyst added in S2 is 0.1-3wt%, based on the total mass of lauryl lactam monomers, comonomers, and end-capping agent.

6. The production method according to claim 5, wherein The comonomer in S2 is caprolactam, and one or more of hexamethylenediamine, pentanediamine, decanediamine, and dodecanediamine, and one or more of adipic acid, sebacic acid, dodecanedioic acid, tridecanedioic acid, and tetradecanedioic acid.

7. The preparation method according to claim 1, wherein the solvent in S3 is a polar polyol; And / or, the amount of copolymerized nylon 12 adhered in S3 is 0.1-99.9wt%, based on the total mass of nylon 12 powder; And / or, the copolymerized nylon 12 solution in S3 adheres to the nylon 12 powder by one or more of dropwise addition with stirring, atomization spraying, and powder immersion.

8. The preparation method according to claim 7, wherein the solvent in S3 is one or more of benzyl alcohol, hexafluoroisopropyl alcohol, and ethanol; The concentration of the copolymerized nylon 12 solution is 1-40wt%; and / or, the adhered copolymerized nylon 12 in S3 accounts for 1-10wt% of the total mass of the nylon 12 powder; and / or, the copolymerized nylon 12 solution in S3 is sprayed on the nylon 12 powder by atomization.

9. A high-tack nylon 12 powder coating obtained using the production process according to any one of claims 1 to 8, characterized in that The powder coating is the nylon 12 powder to which copolymerized nylon 12 is adhered; and / or, the D50 particle size of the powder coating is 100-200 microns.

10. Use of the high-adhesion nylon 12 powder coating obtained by the method of any one of claims 1-8 or the powder coating of claim 9, for powder coating of conveying pipes, containers, kitchen and bathroom, and industrial mechanical parts.

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