CN114349989B - Micro-crosslinked polyamide powder for 3D printing and preparation method and application thereof - Google Patents
Micro-crosslinked polyamide powder for 3D printing and preparation method and application thereof Download PDFInfo
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Abstract
The invention discloses micro-crosslinked polyamide powder for 3D printing and a preparation method and application thereof, wherein the preparation method comprises the following steps: 1) Polycondensation is carried out by taking laurolactam as a polymerization monomer and in the presence of a blocking cross-linking agent containing polyamine oligomer or polyamine adduct, thus obtaining micro-crosslinking polyamide resin; 2) And (3) dissolving and precipitating the micro-crosslinked polyamide resin to obtain micro-crosslinked polyamide powder. The invention takes polyamine oligomer or polyamine adduct as the end-capping cross-linking agent of laurolactam ring-opening polymerization, and can prepare micro-crosslinking polyamide powder with wide processing window, good manufacturability and excellent mechanical property.
Description
Technical Field
The invention relates to polyamide powder, in particular to micro-crosslinked polyamide powder for 3D printing and a preparation method and application thereof.
Background
Selective Laser Sintering (SLS) is an important 3D printing technique. At present, polyamide powder is an important consumable material for SLS technology, has a certain sintering window as a crystalline polymer, and is suitable for a selective laser sintering process. Preparing a 3D printing product by using polyamide powder, wherein equipment needs to preheat the polyamide powder (about 170 ℃), and the temperature of a region is close to the melting point of a material; according to the given interface structure information of the component, the high-intensity laser beam irradiates the solid part of the component, the irradiated polyamide powder is quickly heated to the melting point and solidified after being cooled, after the sintering of one layer of interface is finished, a new layer of powder material is paved, the interface is sintered again selectively and fused with the formed part below, then the interface is continuously circulated and piled layer by layer, finally the polyamide powder of the non-solid part is removed, and the three-dimensional solid component with the expected design is obtained.
This requires a relatively wide solid-liquid-solid processing window (difference between melting temperature and crystallization temperature) for the polyamide powder, which is flowable after melting and can be rapidly consolidated; meanwhile, the higher processing window prevents the high-temperature sintering from melting and agglomerating the polyamide powder on the surface layer of the solid part, so that the surface appearance of the product and the recycling of the powder are affected, and the product has good mechanical properties to meet the application requirements of different products. In view of the deficiencies of the current art, there is a need to provide a solution.
Disclosure of Invention
In order to solve the technical problems, the invention provides micro-crosslinked polyamide powder for 3D printing and a preparation method and application thereof. The invention takes polyamine oligomer or polyamine adduct as the end-capping cross-linking agent of laurolactam ring-opening polymerization, and can prepare micro-crosslinking polyamide powder with wide processing window, good manufacturability and excellent mechanical property.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
the preparation method of the micro-crosslinked polyamide powder for 3D printing comprises the following steps:
1) Preparation of micro-crosslinked Polyamide resin
The micro-crosslinking polyamide resin is prepared by using laurolactam as a polymerization monomer and performing polycondensation in the presence of a blocking crosslinking agent containing polyamine oligomer or polyamine adduct;
2) Preparation of micro-crosslinked Polyamide powder
And (3) dissolving and precipitating the micro-crosslinked polyamide resin to obtain micro-crosslinked polyamide powder.
Further, the micro-crosslinked polyamide has a number average molecular weight of 15000 to 50000, preferably 15000 to 30000, and a relative viscosity of 1.5 to 3.1, preferably 1.7 to 2.1.
Further, the preparation method of the micro-crosslinked polyamide resin in the step 1) comprises the following steps:
adding laurolactam, a blocking cross-linking agent and optionally an antioxidant into a water-containing reaction kettle, carrying out ring-opening reaction at high temperature and high pressure after nitrogen substitution, and then carrying out normal-pressure polycondensation reaction to prepare micro-crosslinked polyamide;
the ring-opening reaction conditions are as follows: the reaction temperature is 230-310 ℃, preferably 250-290 ℃, the reaction pressure is 2-8Mpa, preferably 3-6Mpa, and the reaction time is 1-10h, preferably 2-6h;
the polycondensation reaction conditions are as follows: the reaction temperature is 200-280 ℃, preferably 220-280 ℃ under normal pressure, and the reaction time is 2-12h, preferably 4-12h.
Further, in step 1), the end-capping cross-linking agent is used in an amount of 2-14% by mass, preferably 3-12% by mass, of dodecalactam;
preferably, the end-capping cross-linking agent contains at least one or more of diaminodiphenylmethane oligomer, phenyldimethylamine oligomer, diaminodicyclohexylmethane oligomer, cyclohexyldimethylamine oligomer, hexamethylenediamine oligomer, diaminodiphenylmethane epoxy adduct, diaminodicyclohexylmethane epoxy adduct, isophoronediamine epoxy adduct, hexamethylenediamine epoxy adduct, preferably at least one or more of diaminodiphenylmethane oligomer, phenyldimethylamine oligomer, diaminodicyclohexylmethane oligomer, cyclohexyldimethylamine oligomer, diaminodiphenylmethane epoxy adduct, diaminodicyclohexylmethane epoxy adduct;
preferably, the end-capping cross-linking agent further comprises optionally a small molecule polyfunctional amine, preferably one or more of diaminodiphenylmethane, diaminodicyclohexylmethane, triethylenetetramine, hexamethylenediamine, isophoronediamine.
The end-capped cross-linking agent selected by the invention is polyamine containing trifunctional or higher, especially a mixture of trifunctional or higher polyamine and other polyamine, for example, polyamine oligomer is a mixture of various different-functionality polyamines (including trifunctional amine), polyamine adduct can also be compounded with other small-molecule polyamines to form a mixture, and the polyamine of the type is used for polymerization reaction of laurolactam and used as an end-capping agent, so that polyamide with a micro-crosslinked structure can be prepared. The inventors of the present invention have unexpectedly found in the study that when the micro-crosslinked polyamide resin is produced into crystalline powder and used as a 3D printing material, the micro-crosslinked polyamide resin has the characteristics of wide sintering window of a product, no caking on the surface, good mechanical properties, and particularly excellent elongation at break.
Further, the blocked crosslinking agent of the present invention is preferably the aforementioned alicyclic or aromatic polyamine or a mixture thereof, and has excellent processing window and mechanical properties, and industrial applicability, compared with the derivative structure of aliphatic amine polyamine.
Further, the dosage of the antioxidant is 1-8% of the mass of the laurolactam, preferably 2-6%;
preferably, the antioxidant is a compound antioxidant consisting of hindered phenol antioxidants and phosphite antioxidants, and the mass ratio of the hindered phenol antioxidants to the phosphite antioxidants is (1-5): 1, a step of;
more preferably, the hindered phenol antioxidant is one or two of 2, 6-di-tert-butyl-4-methyl-phenol and N, N' -bis- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexamethylenediamine; the phosphite antioxidant is one or more of 2' -ethylbis (4, 6-di-tert-butylphenyl) fluorophosphite and tri (2, 4-di-tert-butylphenyl) phosphite.
Further, the method for preparing the micro-crosslinked polyamide powder by adopting the dissolution precipitation method in the step 2) comprises the following steps:
adding the micro-crosslinked polyamide resin and the nucleating agent into a crystallization kettle containing ethanol, heating to 130-150 ℃, stirring at constant temperature for 1-4h, and fully dissolving; then slowly reducing the temperature of the system to 110-120 ℃, and stirring at constant temperature for 1-5h; then the system temperature is reduced to below 60 ℃ to obtain suspension; centrifuging to remove the solvent, and vacuum drying to obtain micro-crosslinked polyamide solid; grinding the solid and sieving to obtain micro-crosslinked polyamide powder;
preferably, the micro-crosslinked polyamide powder has an average particle size of 30-100 microns, preferably 50-70 microns.
The micro-crosslinked polyamide powder prepared by the method has the advantages of low average particle size, good fluidity after melting, good adhesion among powder particles and contribution to improving the mechanical properties of a finished product.
Further, in the step 2), the amount of the nucleating agent is 1 to 5% by mass of the micro-crosslinked polyamide resin. The ethanol consumption can be 5-10 times of the mass of the micro-crosslinked polyamide resin.
Further, the nucleating agent is one or more of nano silicon dioxide, nano titanium dioxide, talcum powder, graphite, kaolin, montmorillonite, clay, nano aluminum oxide, nano zirconium oxide, nano calcium carbonate, neodymium oxide whisker, magnesium oxide whisker, zinc oxide whisker, magnesium sulfate whisker, sodium phenylphosphinate, sodium benzoate, amide, polycarbonate, polyphenylene sulfide and carbon fiber, preferably nano silicon dioxide.
The invention also provides a micro-crosslinked polyamide powder prepared by the method.
The invention also provides application of the micro-crosslinked polyamide powder prepared by the method as a 3D printing material.
The invention has the beneficial effects that:
1) By introducing polyfunctional amine into the molecular structure as a crosslinking point, polyamide resin with a micro-crosslinking structure can be prepared, and compared with the traditional linear polyamide, the polyamide resin has improved melting point and mechanical property, particularly obviously increased elongation at break and reduced glass transition temperature, and is beneficial to widening a processing window;
2) The micro-crosslinked polyamide powder prepared by the invention has low average particle size, good fluidity of the melted product and good adhesion among powder particles, and is beneficial to improving the mechanical properties of the finished product.
3) The micro-crosslinked polyamide powder prepared by the invention can meet different performance requirements of 3D printing products by regulating and controlling monomers and the addition proportion of the micro-crosslinked structure, thereby expanding the downstream application market.
Detailed Description
The invention will now be further illustrated by means of specific examples which are given solely by way of illustration of the invention and do not limit the scope thereof.
The raw materials in each example and comparative example of the invention are obtained through commercial sources unless otherwise specified.
Test standards and apparatus for samples prepared in each example:
the number average molecular weight was tested using a gel chromatograph (GPC);
relative viscosity: taking m-cresol as a solvent, measuring the flowing time of 0.5g/100ml of polymer dilute solution in an Ubbelohde viscosity tube, and calculating the ratio of the flowing time of the polymer dilute solution to the flowing time of the pure solvent;
glass transition temperature: mettler DSC 1.5 mg of sample was measured on an N-meter using a differential scanning calorimeter 2 Heating to 250 ℃ at a heating rate of 5 ℃/min under the atmosphere, maintaining for 3 minutes to eliminate the heat history, cooling to room temperature at 10 ℃/min to perform non-isothermal crystallization, heating to 250 ℃ at 10 ℃/min, and recording a melting curve after the non-isothermal crystallization.
Average particle diameter: rise-2008 type laser particle sizer.
Tensile properties: the stretching rate is 10mm/min by adopting a UTM4000 type universal tester according to the standard GB/T1040.1-2006 test.
[ example 1 ]
(1) Preparation of micro-crosslinked Polyamide resin
200g of laurolactam, 30g of water, 4g of antioxidant (1098/168 mass ratio is 1:1) and 20g of diamino dicyclohexylmethane oligomer (diamino dicyclohexylmethane device tower bottom liquid, wherein the dimer content is 34.51%, the bis [ (2-aminocyclohexyl) methyl ] cyclohexylamine content is 28.23%, the diamino dicyclohexylmethane content is 14.8%, and Wanhua chemistry) are sequentially added into a reaction kettle, nitrogen is replaced for three times, ring-opening reaction is carried out for 4 hours at 280 ℃ and 4MPa, then the temperature is reduced to 270 ℃, the pressure is reduced to normal pressure, polycondensation is carried out for 6 hours, and the micro-crosslinked polyamide resin is obtained through traction granulation and drying. The molecular weight of the product is 25000, the relative viscosity is 2.1, the glass transition temperature Tg is 45 ℃, and the melting point is 183 ℃.
(2) Preparation of micro-crosslinked Polyamide powder
Adding 1kg of ethanol into a high-pressure crystallization kettle, then adding 10g of nucleating agent nano silicon dioxide, starting stirring, adding 200g of micro-crosslinked polyamide resin into the crystallization kettle, replacing nitrogen for 3 times, starting heating, keeping the temperature of the materials to 130 ℃, and then keeping the temperature for 1h to enable the micro-crosslinked polyamide resin to be fully dissolved; the system temperature is reduced from 130 ℃ to 110 ℃ at a temperature control rate of 5 ℃/h, stirred for 4h, and then reduced to below 60 ℃ at a temperature reduction rate of 30 ℃/h, so as to obtain the suspension of the micro-crosslinked polyamide powder. The solvent was removed by a centrifuge, and then transferred to a vacuum drum for drying, and ground and sieved by a sieve separator to obtain a micro-crosslinked polyamide powder having an average particle size of 55. Mu.m.
[ example 2 ]
(1) Preparation of a micro-crosslinked polyamide resin:
200g of laurolactam, 26g of water, 6g of antioxidant (1010/168 mass ratio is 2:1) and 10g of phenyl dimethylamine tower bottom liquid (phenyl dimethylamine tower bottom liquid, wherein the phenyl dimethylamine accounts for 55.34 percent, the phenyl dimethylamine accounts for 44.62 percent and the Wanhua chemistry) are sequentially added into a reaction kettle, nitrogen is replaced for three times, ring-opening reaction is carried out for 3 hours at 260 ℃ and 4MPa, then the temperature is reduced to 240 ℃ and the pressure is reduced to normal pressure for polycondensation for 10 hours, and the micro-crosslinked polyamide resin is obtained through traction granulation and drying. The molecular weight of the product is 20000, the relative viscosity is 1.9, the glass transition temperature Tg is 43 ℃, and the melting point is 180 ℃.
(2) Preparing micro-crosslinking polyamide powder:
adding 1kg of ethanol into a high-pressure crystallization kettle, then adding 3g of nucleating agent nano titanium dioxide, starting stirring, adding 120g of micro-crosslinked polyamide resin into the crystallization kettle, replacing nitrogen for 3 times, starting heating, keeping the temperature of the material to 135 ℃, and then keeping the temperature for 2 hours to enable the micro-crosslinked polyamide resin to be fully dissolved; the system temperature is reduced from 135 ℃ to 110 ℃ at a temperature control rate of 5 ℃/h, and is stirred for 5h, and then the system temperature is reduced to below 60 ℃ at a temperature reduction rate of 30 ℃/h, so as to obtain the suspension of the micro-crosslinked polyamide powder. The solvent was removed by a centrifuge, and then transferred to a vacuum drum for drying, and ground and sieved by a sieve separator to obtain a micro-crosslinked polyamide powder having an average particle size of 52. Mu.m.
[ example 3 ]
(1) Preparation of a micro-crosslinked polyamide resin:
isophorone diamine and 1, 6-hexanediol diglycidyl ether are mixed according to a molar ratio of 2:1 in a flask at 60℃for 4h to give isophorone diamine epoxy adduct. Sequentially adding 200g of laurolactam, 20g of water, 8g of antioxidant (1096/168 mass ratio is 2:1) and 14g of isophorone diamine epoxy adduct into a reaction kettle, replacing nitrogen for three times, carrying out ring-opening reaction for 6 hours at 270 ℃ and 4MPa, then reducing the temperature to 250 ℃, reducing the pressure to normal pressure for polycondensation for 4 hours, and carrying out traction granulation and drying to obtain the micro-crosslinked polyamide resin. The molecular weight of the product was 15000, the relative viscosity was 1.7, the glass transition temperature Tg was 46℃and the melting point was 179 ℃.
(2) Preparing micro-crosslinking polyamide powder:
adding 1kg of ethanol into a high-pressure crystallization kettle, then adding 5g of nucleating agent nano silicon dioxide, starting stirring, adding 150g of micro-crosslinked polyamide resin into the crystallization kettle, replacing nitrogen for 3 times, starting heating, keeping the temperature of the material to 140 ℃, and then preserving heat for 3 hours to enable the micro-crosslinked polyamide resin to be fully dissolved; the system temperature is reduced from 140 ℃ to 115 ℃ at a temperature control rate of 5 ℃/h and stirred for 3h, and then the system temperature is reduced to below 60 ℃ at a temperature reduction rate of 30 ℃/h, so as to obtain the suspension of the micro-crosslinked polyamide powder. The solvent was removed by a centrifuge, and then transferred to a vacuum drum for drying, and ground and sieved by a sieve separator to obtain a micro-crosslinked polyamide powder having an average particle size of 60. Mu.m.
[ example 4 ]
(1) Preparation of a micro-crosslinked polyamide resin:
200g of laurolactam, 36g of water, 10g of antioxidant (1010/168 mass ratio is 4:1) and 6g of hexamethylenediamine oligomer (hexamethylenediamine device tower bottom liquid, wherein N- (6-aminocaproyl) -hexamethylenediamine accounts for 85.21 percent, 2-amino-3, 4,5, 6-di (trimethylene) pyridine is 4.03 percent, shenma practice) are sequentially added into a reaction kettle, nitrogen is replaced for three times, ring-opening reaction is carried out for 5 hours at the temperature of 250 ℃ and the pressure of 5MPa, then the temperature is reduced to 220 ℃, the pressure is reduced to normal pressure for polycondensation for 12 hours, and the micro-crosslinked polyamide resin is obtained through traction granulation and drying. The molecular weight of the product is 20000, the relative viscosity is 2.0, the glass transition temperature Tg is 47 ℃, and the melting point is 178 ℃.
(2) Preparing micro-crosslinking polyamide powder:
adding 1kg of ethanol into a high-pressure crystallization kettle, then adding 7g of nucleating agent nano zirconia, starting stirring, adding 180g of micro-crosslinked polyamide resin into the crystallization kettle, replacing nitrogen for 3 times, starting heating, keeping the temperature of the material to 145 ℃, and then keeping the temperature for 1h to enable the micro-crosslinked polyamide resin to be fully dissolved; the temperature of the system is reduced from 145 ℃ to 115 ℃ at a temperature control rate of 5 ℃/h, and the system is reduced to below 60 ℃ at a temperature reduction rate of 30 ℃/h, so as to obtain the suspension of the micro-crosslinked polyamide powder. The solvent was removed by a centrifuge, and then transferred to a vacuum drum for drying, and ground and sieved by a sieve separator to obtain a micro-crosslinked polyamide powder having an average particle size of 65. Mu.m.
[ example 5 ]
(1) Preparation of a micro-crosslinked polyamide resin:
sequentially adding 200g of laurolactam, 40g of water, 12g of antioxidant (1010/168 mass ratio is 5:1), 18g of triethylene tetramine and 6g of hexamethylenediamine into a reaction kettle, replacing nitrogen for three times, carrying out ring-opening reaction for 2 hours at 290 ℃ and 3MPa, then reducing the temperature to 280 ℃ and the pressure to normal pressure for polycondensation for 8 hours, and carrying out traction granulation and drying to obtain the micro-crosslinked polyamide resin. The molecular weight of the product is 30000, the relative viscosity is 2.0, the glass transition temperature Tg is 47 ℃, and the melting point is 176 ℃.
(2) Preparing micro-crosslinking polyamide powder:
adding 1kg of ethanol into a high-pressure crystallization kettle, then adding 1g of nucleating agent nano silicon dioxide, starting stirring, adding 100g of micro-crosslinked polyamide resin into the crystallization kettle, replacing nitrogen for 3 times, starting heating, keeping the temperature of the materials to 150 ℃, and then keeping the temperature for 2 hours to enable the micro-crosslinked polyamide resin to be fully dissolved; the system temperature is reduced from 150 ℃ to 120 ℃ at a temperature control rate of 5 ℃/h, and is stirred for 1h, and then the system temperature is reduced to below 60 ℃ at a temperature reduction rate of 30 ℃/h, so as to obtain the suspension of the micro-crosslinked polyamide powder. The solvent was removed by a centrifuge, and then transferred to a vacuum drum for drying, and ground and sieved by a sieve separator to obtain a micro-crosslinked polyamide powder having an average particle size of 70. Mu.m.
Comparative example 1
(1) Preparation of Linear Polyamide resins
Sequentially adding 200g of laurolactam, 30g of water, 4g of antioxidant (1098/168 mass ratio is 1:1) and 20g of decanediamine into a reaction kettle, replacing nitrogen for three times, carrying out ring-opening reaction for 4 hours at 280 ℃ and 4MPa, then reducing the temperature to 270 ℃, reducing the pressure to normal pressure for polycondensation for 6 hours, and carrying out traction granulation and drying to obtain the micro-crosslinked polyamide resin. The molecular weight of the product was 15000, the relative viscosity was 1.7, the glass transition temperature Tg was 49℃and the melting point was 175 ℃.
(2) Preparation of Linear Polyamide powder
Adding 1kg of ethanol into a high-pressure crystallization kettle, then adding 10g of nucleating agent nano silicon dioxide, starting stirring, adding 200g of linear polyamide resin into the crystallization kettle, replacing nitrogen for 3 times, starting heating, keeping the temperature of the materials to 130 ℃, and preserving heat for 1h to fully dissolve the micro-crosslinked polyamide resin; the system temperature is reduced from 130 ℃ to 110 ℃ at a temperature control rate of 5 ℃/h, stirred for 4h, and then reduced to below 60 ℃ at a temperature reduction rate of 30 ℃/h, so as to obtain the suspension of the micro-crosslinked polyamide powder. The solvent was removed by a centrifuge, and then transferred to a vacuum drum for drying, and ground and sieved by a sieve separator to obtain a micro-crosslinked polyamide powder having an average particle size of 77. Mu.m.
Comparative example 2
(1) Preparation of Star-shaped Polyamide resin
8.7g of pyromellitic anhydride l, 157g of laurolactam and 32g of deionized water are added into a high-pressure reaction kettle at one time, after nitrogen replacement is performed for three times, the temperature of the reaction kettle is raised to 230 ℃, the temperature is regulated to be constant at 1.8MPa for 30min, stirring is started, the pressure is released after reaction is carried out for 10 hours, the pressure in the kettle is kept lower than 1X 10 < -4 > MPa by vacuumizing and is kept constant for 20min, finally high-pressure nitrogen is filled to enable the pressure in the kettle to reach 1.8MPa, the polymer in the reaction kettle is extruded, water cooling is carried out, pelleting is carried out, vacuum drying is carried out at 100 ℃ for 24h, and the four-arm star PA12 with the molecular weight of 8000 and the relative viscosity of 1.4 is obtained, DSC test shows no obvious glass transition and is an amorphous material with the melting point of 172 ℃.
(2) Preparation of Star-shaped Polyamide powder
Adding 1kg of ethanol into a high-pressure crystallization kettle, then adding 10g of nucleating agent nano silicon dioxide, starting stirring, adding 200g of star-shaped polyamide resin into the crystallization kettle, replacing nitrogen for 3 times, starting heating, keeping the temperature of the materials to 130 ℃, and then keeping the temperature for 1h to enable the micro-crosslinked polyamide resin to be fully dissolved; the system temperature is reduced from 130 ℃ to 110 ℃ at a temperature control rate of 5 ℃/h, stirred for 4h, and then reduced to below 60 ℃ at a temperature reduction rate of 30 ℃/h, so as to obtain the suspension of the micro-crosslinked polyamide powder. The solvent was removed by a centrifuge, and then transferred to a vacuum drum for drying, and ground and sieved by a sieve separator to obtain a micro-crosslinked polyamide powder having an average particle size of 75. Mu.m.
The polyamide powders prepared in each of examples and comparative examples were molded by a laser sintering machine and tested in table 1, with the following test results:
TABLE 1 Performance test results
| Sample of | Tensile Strength/Mpa | Elongation at break/% | Surface appearance of articles |
| Example 1 | 56 | 17.3 | No caking |
| Example 2 | 57 | 15.6 | No caking |
| Example 3 | 53 | 16.5 | No caking |
| Example 4 | 47 | 14.2 | No caking |
| Example 5 | 49 | 11.4 | Slight orange peel phenomenon |
| Comparative example 1 | 45 | 6.4 | Slight orange peel phenomenon |
| Comparative example 2 | 42 | 6.5 | Obvious skinning phenomenon |
From the test results, the invention can be seen that by introducing the micro-crosslinking structure into the polyamide powder, compared with the orange peel agglomeration phenomenon on the surface of the product prepared by the traditional process (comparative example 1), the tensile strength of the printed product is improved, the elongation at break is obviously increased, the requirements of products with different performance indexes and various complex structures can be met, and the downstream application market is expanded. In comparative example 2, the star polyamide has a higher molecular weight due to the first formation of crosslinking points, and the product with an amorphous structure has lower performance, and the polyamide powder on the surface layer of the solid part is melted and agglomerated due to high-temperature sintering, so that the surface has obvious skinning phenomenon.
In addition, as can be seen from the test results, in examples 1 to 3, alicyclic/aromatic polyamine is selected as the end-capping cross-linking agent, and compared with examples 4 to 5, the end-capping cross-linking agent is selected from aliphatic polyamine, the processing window is wider, the particle size of the powder is lower, the mechanical property of the obtained product is higher, and the surface effect is better.
The foregoing is merely a preferred embodiment of the present invention, and it should be noted that modifications and additions may be made to those skilled in the art without departing from the method of the present invention, which modifications and additions are also to be considered as within the scope of the present invention.
Claims (23)
1. The preparation method of the micro-crosslinked polyamide powder for 3D printing is characterized by comprising the following steps of:
1) Preparation of micro-crosslinked Polyamide resin
The micro-crosslinking polyamide resin is prepared by using laurolactam as a polymerization monomer and performing polycondensation in the presence of a blocking crosslinking agent containing polyamine oligomer or polyamine adduct;
the end-capped cross-linking agent at least contains one or more of diamino diphenyl methane oligomer, phenyl dimethylamine oligomer, diamino dicyclohexylmethane oligomer, cyclohexyl dimethylamine oligomer, hexamethylenediamine oligomer, diamino diphenyl methane epoxy adduct, diamino dicyclohexylmethane epoxy adduct, isophorone diamine epoxy adduct and hexamethylenediamine epoxy adduct;
2) Preparation of micro-crosslinked Polyamide powder
And (3) dissolving and precipitating the micro-crosslinked polyamide resin to obtain micro-crosslinked polyamide powder.
2. The method for producing a micro-crosslinked polyamide powder for 3D printing according to claim 1, wherein the micro-crosslinked polyamide has a number average molecular weight of 15000 to 50000 and a relative viscosity of 1.5 to 3.1.
3. The method for producing a micro-crosslinked polyamide powder for 3D printing according to claim 2, wherein the micro-crosslinked polyamide has a number average molecular weight of 15000 to 30000 and a relative viscosity of 1.7 to 2.1.
4. A method for producing a micro-crosslinked polyamide powder for 3D printing according to any one of claims 1 to 3, wherein the method for producing a micro-crosslinked polyamide resin in step 1) is:
adding laurolactam, a blocking cross-linking agent and optionally an antioxidant into a water-containing reaction kettle, carrying out ring-opening reaction at high temperature and high pressure after nitrogen substitution, and then carrying out normal-pressure polycondensation reaction to prepare micro-crosslinked polyamide;
the ring-opening reaction conditions are as follows: the reaction temperature is 230-310 ℃, the reaction pressure is 2-8Mpa, and the reaction time is 1-10h;
the polycondensation reaction conditions are as follows: normal pressure, reaction temperature of 200-280 ℃ and reaction time of 2-12h.
5. The method for producing a micro-crosslinked polyamide powder for 3D printing according to claim 4, wherein the ring-opening reaction conditions in step 1) are: the reaction temperature is 250-290 ℃, the reaction pressure is 3-6MPa, and the reaction time is 2-6h.
6. The method for producing a micro-crosslinked polyamide powder for 3D printing according to claim 4, wherein the polycondensation reaction conditions in step 1) are: normal pressure, 220-280 deg.c and 4-12 hr.
7. The method for producing a micro-crosslinked polyamide powder for 3D printing according to claim 4, wherein in step 1), the end-capping crosslinking agent is used in an amount of 2 to 14% by mass of dodecalactam.
8. The method for producing a micro-crosslinked polyamide powder for 3D printing according to claim 7, wherein in step 1), the end-capping crosslinking agent is used in an amount of 3 to 12% by mass of dodecalactam.
9. The method for producing a micro-crosslinked polyamide powder for 3D printing according to claim 1, wherein the end-capping crosslinking agent contains at least one or more of diaminodiphenylmethane oligomer, phenyldimethylamine oligomer, diaminodicyclohexylmethane oligomer, cyclohexyldimethylamine oligomer, diaminodiphenylmethane epoxy adduct, diaminodicyclohexylmethane epoxy adduct, isophorone diamine epoxy adduct.
10. The method of preparing a micro-crosslinked polyamide powder for 3D printing according to claim 7, wherein the end-capping crosslinker further comprises an optionally small molecule polyfunctional amine.
11. The method for producing a micro-crosslinked polyamide powder for 3D printing according to claim 10, wherein the small molecule polyfunctional amine is one or more selected from the group consisting of diaminodiphenylmethane, diaminodicyclohexylmethane, triethylenetetramine, hexamethylenediamine and isophoronediamine.
12. The method for preparing micro-crosslinked polyamide powder for 3D printing according to claim 4, wherein the antioxidant is used in an amount of 1-8% by mass of dodecalactam.
13. The method for preparing micro-crosslinked polyamide powder for 3D printing according to claim 12, wherein the amount of the antioxidant is 2-6% of the mass of dodecalactam.
14. The method for preparing micro-crosslinked polyamide powder for 3D printing according to claim 12, wherein the antioxidant is a compound antioxidant composed of hindered phenol antioxidants and phosphite antioxidants, and the mass ratio of the two is (1-5): 1.
15. the method for producing a micro-crosslinked polyamide powder for 3D printing according to claim 14, wherein the hindered phenol antioxidant is one or two of 2, 6-di-t-butyl-4-methyl-phenol, N' -bis- (3, 5-di-t-butyl-4-hydroxyphenyl) propionyl) hexamethylenediamine; the phosphite antioxidant is one or more of 2' -ethylbis (4, 6-di-tert-butylphenyl) fluorophosphite and tri (2, 4-di-tert-butylphenyl) phosphite.
16. A method for preparing a micro-crosslinked polyamide powder for 3D printing according to any one of claims 1-3, wherein the method for preparing the micro-crosslinked polyamide powder in step 2) by using a dissolution precipitation method is as follows:
adding the micro-crosslinked polyamide resin and the nucleating agent into a crystallization kettle containing ethanol, heating to 130-150 ℃, stirring at constant temperature for 1-4h, and fully dissolving; then slowly reducing the temperature of the system to 110-120 ℃, and stirring at constant temperature for 1-5h; then the system temperature is reduced to below 60 ℃ to obtain suspension; centrifuging to remove the solvent, and vacuum drying to obtain micro-crosslinked polyamide solid; the solid was ground and then sieved to obtain a micro-crosslinked polyamide powder.
17. The method for producing a micro-crosslinked polyamide powder for 3D printing according to claim 16, wherein the micro-crosslinked polyamide powder has an average particle diameter of 30 to 100 μm.
18. The method for producing a micro-crosslinked polyamide powder for 3D printing according to claim 17, wherein the micro-crosslinked polyamide powder has an average particle diameter of 50 to 70 μm.
19. The method for preparing a micro-crosslinked polyamide powder for 3D printing according to claim 16, wherein the nucleating agent is used in an amount of 1-5% by mass of the micro-crosslinked polyamide resin in step 2).
20. The method for preparing micro-crosslinked polyamide powder for 3D printing according to claim 16, wherein the nucleating agent is one or more of nano silica, nano titanium dioxide, talcum powder, graphite, kaolin, montmorillonite, clay, nano alumina, nano zirconia, nano calcium carbonate, neodymium oxide whisker, magnesium oxide whisker, zinc oxide whisker, magnesium sulfate whisker, sodium phenylphosphinate, sodium benzoate, amide, polycarbonate, polyphenylene sulfide, and carbon fiber.
21. The method of preparing a micro cross-linked polyamide powder for 3D printing according to claim 20, wherein the nucleating agent is nano silica.
22. A micro-crosslinked polyamide powder prepared according to the method of any one of claims 1-21.
23. Use of a micro-crosslinked polyamide powder prepared according to the method of any one of claims 1-21 as a 3D printing material.
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