In order to reduce the influence of high-temperature aging of nylon powder on melt fluidity in a sintering process, the invention introduces the novel functionalized aromatic hydroxyl-terminated polyether end-capping modifier, thereby avoiding the reduction of melt fluidity caused by end group condensation in the high-temperature sintering process. An aromatic benzene ring structure is introduced to be conjugated with O and N atoms in amido bonds, and the introduced amido bonds enhance intermolecular force, so that the heat resistance and stability of a nylon molecular chain are better; and meanwhile, polyether flexible chain segments are introduced, so that molecular chain entanglement is effectively prevented.

The nylon has a long carbon chain structure and good flexibility, so that aromatic hydroxyl-terminated polyether with a novel structure is introduced as a terminated modifier, the direction of the added ether chain is consistent with the direction of a nylon main chain, the flexibility of the tail end of the nylon chain is properly increased by the ether chain, the molecular structure of the nylon chain is linear, and the distance between the tail ends of the nylon chain and the mean square is reduced, so that the entanglement degree of the tail ends of the nylon is effectively avoided, the toughness is improved, meanwhile, the molecular chain entanglement in the sintering process is reduced, and the flowability of nylon powder is increased; the benzene ring structure introduced at the tail end of the material increases the rigidity through the conjugation, reduces the reduction of the strength and the glass transition temperature caused by the introduction of a flexible chain segment, and improves the heat resistance of a molecular chain; the stability of the introduced amido bond can be effectively improved.

In the invention, the nylon monomer is a raw material for preparing one or more of PA6, PA11, PA12, PA66, PA610, PA612, PA1010, PA1012 and PA 1212; preferably, the molar ratio of the nylon monomer to the end capping modifier is (100-130): 1, and preferably (110-120): 1.

In the invention, the preparation steps of the end-capping modifier are as follows:

s1: placing monoamino polyetheramine and benzoic acid in an organic solvent I, adding a dehydrating agent to react with a catalyst, and washing and drying to obtain a compound A;

s2: dissolving the compound A in an organic solvent II, adding Lewis acid, cooling, heating for reaction, quenching after the reaction is finished, removing water, and drying to obtain the target end capping modifier.

In one embodiment, the reaction of the above-described end-capping modifier preparation step is as follows:

in the invention, the monoamine polyether amine S1 has the following structure:

among them, X =1 to 20, and preferably X =5 to 15.

In the invention, the organic solvent I in S1 is anhydrous Dimethylformamide (DMF) and/or Dichloromethane (DCM).

In the present invention, the dehydrating agent in S1 is a carbodiimide condensing agent, preferably 1- (3-dimethylaminopropyl) -3-Ethylcarbodiimide (EDCI).

In the present invention, the catalyst of S1 is a nucleophilic acylation catalyst, preferably 4-Dimethylaminopyridine (DMAP); preferably, the molar ratio of the monoamine polyether amine, the benzoic acid, the dehydrating agent and the catalyst is 1 (1-1.1) to 1-3) to 0.5-2;

in the present invention, S1 is washed with a saturated NaCl solution and then with anhydrous Na₂ SO₄ And (5) drying.

In the invention, the compound A of S1 has the following structure:

wherein X =1 to 20, preferably X =5 to 15.

In the invention, the organic solvent II in S2 is Dichloromethane (DCM) and/or N, N-Dimethylformamide (DMF).

In the invention, the Lewis acid S2 is boron tribromide and/or boron trifluoride; preferably, the molar ratio of the Lewis acid to the compound A is (1-2): 1.

In the invention, S2 is cooled by a dry ice-acetone bath and naturally heated to room temperature.

In the invention, S2 is stirred and reacts for 2-4 h.

In the invention, S2 is quenched by adding water.

Another object of the present invention is to provide a method for preparing a nylon powder for 3D printing with high multiplexing rate.

A preparation method of nylon powder for high-reusability 3D printing comprises the following steps:

optionally, for copolymerized nylons, nylon salt is first prepared, SS1: adding dibasic acid, diamine and water into a reaction kettle, filtering and drying to obtain nylon salt B;

and SS2: adding nylon salt B or a nylon monomer for homopolymerization, water, a termination modifier and a catalyst into a polymerization reaction kettle for reaction, and then carrying out bracing and grain cutting to obtain target nylon C;

and (4) SS3: and (3) dissolving the nylon C in an organic solvent IV, and filtering and drying to obtain nylon powder.

In the invention, the dibasic acid described in SS1 is one or more of adipic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid and tetradecanedioic acid.

In the invention, the diamine in SS1 is one or more of hexamethylene diamine, decamethylene diamine, undecamethylene diamine, dodecamethylene diamine, tridecamethylene diamine and tetradecamethylene diamine.

In the invention, the nylon monomer for homopolymerization in SS2 is one or more of caprolactam, undecyl amino undecanoic acid and laurolactam.

In the invention, the catalyst of SS2 is n-butyl zirconium and/or tetrabutyl titanate; preferably, the adding amount of the catalyst is 0.1-0.3% by mass of the nylon salt and/or the nylon monomer for homopolymerization.

In the present invention, the organic solvent IV described in SS3 is absolute ethyl alcohol and/or N, N-Dimethylformamide (DMF), preferably absolute ethyl alcohol.

In the invention, an antioxidant is added into SS3, the antioxidant is a composite antioxidant consisting of a hindered phenol antioxidant and a phosphite antioxidant, the hindered phenol antioxidant is preferably N, N' -bis- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexamethylene diamine (antioxidant 1098), and the phosphite antioxidant is preferably tris (2, 4-di-tert-butyl) phenyl phosphite (antioxidant 168).

In the invention, SS3 is added with a flow aid, and the flow aid is fumed silica and/or fumed alumina, preferably fumed silica.

Compared with the prior art, the invention has the advantages that:

(1) Effectively reducing the entanglement of nylon molecular chains in the sintering process and preventing the molecular weight from increasing in the process;

(2) The reduction of melt fluidity in the powder sintering process is avoided, the nylon powder reuse rate is improved, the reduction degree of the melt index is less than 20% after 8 times of sintering, and the reduction of the mechanical property is not obvious.

Drawings

FIG. 1 is a graph of melt index (235 deg.C, 2.16 kg) as a function of time during high temperature aging of nylon powders of example 1 (novel end-capping modifier) and nylon powders of comparative example 1 (adipic acid end-capping).

Detailed Description

The present invention is further illustrated by the following specific examples, which are intended to be purely exemplary of the invention and are not intended to limit its scope.

Information of main raw materials: monoamine polyetheramines, hensmei JEFF AMINE M series monoamines; benzoic acid, miuiou chemical reagents ltd, tianjin; carbodiimide hydrochloride (EDCI, analytical pure), beijing coupling technologies ltd; catalyst DMAP (analytical grade), shanghai tatatake technologies ltd; absolute ethyl alcohol, dichloromethane, dimethylformamide, sodium chloride and anhydrous sodium sulfate are analytically pure, national drug group chemical reagent limited; zirconium n-butoxide, tetrabutyl titanate, boron trifluoride and boron tribromide are all analytically pure, alatin; antioxidant 168, antioxidant 1098, basf; titanium dioxide TR52, hensmei.

Instrument and equipment information: melt index apparatus, 7026, ceast, italy; 3D printer, HT252P, chenna hua eosin gao kogao liability company; heating a high-temperature furnace, YJDQ-8-12, chongqingying Dada; universal testing machine, 5984, instron; pendulum impact tester, 9400, instron.

And (4) testing standard: tensile properties, reference standard ISO 527-1/2; impact strength of the simply supported beam notch, according to ISO 179/1eA standard.

Example 1

Preparing an end capping modifier:

s1: 120g of monoamine polyetheramine M-100, 122g of benzoic acid, 191g of dehydrating agent EDCI and 61.1g of catalyst DMAP (molar ratio 1₂ SO₄ Adding the mixture into the solution, standing for 1h, and filtering to obtain the product.

S2: adding the product S1 into 0.5L of anhydrous dichloromethane, placing the system into a dry ice-acetone bath, dropwise adding 250g of boron tribromide (the molar ratio is 1; separating the water phase and the organic phase by using a separating funnel, and carrying out rotary evaporation on the organic phase to obtain the target aromatic hydroxyl-terminated polyether end-capping modifier.

Preparing nylon powder:

SS1: adding 1.72kg of decamethylene diamine, 2.30kg of dodecanedioic acid and 4kg of deionized water into a reaction kettle (the molar ratio of amine to acid is 1.

And (4) SS2: adding 3.8kg of nylon 1012 salt, 3.8g of zirconium n-butyl alcohol and 18.2g of end-capping modifier into a polymerization kettle (the molar ratio of the sum of the nylon raw materials to the end-capping modifier is 110.

And SS3: adding 1kg of nylon 1012 granules, 5kg of ethanol, 1g of antioxidant 1098 and 1g of antioxidant 168 into a high-pressure reaction kettle (the weight ratio of the nylon 1012 to the ethanol solvent to the antioxidant 1098 to the antioxidant 168 is 1. After drying the nylon 1012 powder by a centrifuge, the powder is placed in a vacuum oven to remove residual solvent.

And adding the obtained dry nylon powder and fumed silica with the mass ratio of 0.1% into a high-speed mixer, and uniformly mixing to obtain the target nylon powder.

Evaluation of nylon powder:

the selective laser sintering environment was simulated in a heating furnace at 170 ℃ under nitrogen atmosphere, and the melt index (235 ℃,2.16 kg) of the powder changed with time during high temperature aging of the powder is shown in figure 1.

3D printing test is carried out on the powder continuously recycled for 8 times on the basis of not adding new powder, the recycling forming parameters of each time are the same, the temperature of a temperature field is set to be 170 ℃, the laser power is 45W, the scanning speed is 4000mm/s, the powder laying thickness is 0.1mm, sintering is carried out under the condition that the scanning distance is 0.1mm, and the melt index (235 ℃,2.16 kg), the tensile strength and the tensile breaking elongation of the powder are changed along with the sintering times as shown in Table 1:

TABLE 1 PA1012 powder melt index and variation of physical Properties of sintered article

Example 2

S1: 300g of monoamine polyetheramine M-300, 122g of benzoic acid, 382g of dehydrating agent EDCI and 122.2g of catalyst DMAP (molar ratio 1₂ SO₄ Adding the mixture into the solution, standing for 1h, and filtering to obtain the product.

S2: adding the product S1 into 0.5L of anhydrous dichloromethane, placing the system in a dry ice-acetone bath, dropwise adding 500g of boron tribromide (the molar ratio is 1; separating the water phase and the organic phase by using a separating funnel, and carrying out rotary evaporation on the organic phase to obtain the target aromatic hydroxyl-terminated polyether end-capping modifier.

Preparing nylon powder:

and SS2: adding 2.01kg of 11-aminoundecanoic acid, 6.0g of n-butyl zirconium and 25.0g of an end-capping modifier into a reaction kettle (the molar ratio of the 11-aminoundecanoic acid to the end-capping modifier is 120, the mass of the n-butyl zirconium is 0.3% of that of the 11-aminoundecanoic acid), adding 160g of deionized water (the weight of the deionized water is 8% of that of the 11-aminoundecanoic acid), replacing air in the kettle with nitrogen for three times after the deionized water is added, introducing nitrogen with the pressure of 0.2MPa (gauge pressure) as inert gas, heating to 220 ℃, keeping the pressure in the reaction kettle to be about 2.5MPa, maintaining the pressure for 1h, slowly reducing the pressure to normal pressure, cooling to 250 ℃, vacuumizing, reducing the pressure, draining water, continuing to react for 2h, stopping heating, and carrying out water-cooling and drawing strips, and then carrying out grain cutting to obtain nylon 11 granules.

And (4) SS3: adding 1kg of nylon 11 granules, 5kg of ethanol, 1g of antioxidant 1098 and 1g of antioxidant 168 into a high-pressure reaction kettle (the weight ratio of the nylon 11 to the ethanol solvent to the antioxidant 1098 to the antioxidant 168 is 1. After drying the nylon 11 powder by a centrifuge, placing the dried nylon 11 powder in a vacuum oven to remove residual solvent.

Evaluation of nylon powder:

3D printing test is carried out on the powder continuously recycled for 8 times on the basis of not adding new powder, the recycling forming parameters of each time are the same, the temperature of a temperature field is set to be 170 ℃, the laser power is 45W, the scanning speed is 4000mm/s, the powder laying thickness is 0.1mm, and sintering is carried out under the condition that the scanning distance is 0.1mm, and the melt index (235 ℃,2.16 kg), the tensile strength and the tensile breaking elongation of the powder are changed along with the sintering times as shown in Table 2:

TABLE 2 PA11 powder melt index and change in physical Properties of sintered article

Example 3

Preparing an end capping modifier:

s1: 600g of monoamine polyetheramine M-600, 134.2g of benzoic acid, 382g of dehydrating agent EDCI and 183.3g of catalyst DMAP (molar ratio 1:1.1:2: 1.5) were added to 0.5L of anhydrous dichloromethane, and after 12 hours of reaction with stirring at room temperature, a saturated aqueous NaCl solution was added and washed 3 times, and anhydrous Na₂ SO₄ Adding the mixture into the solution, standing for 1h, and filtering to obtain the product.

S2: adding the product S1 into 0.5L of anhydrous dichloromethane, placing the system in a dry ice-acetone bath, dropwise adding 67.8g of boron trifluoride (the molar ratio is 1; separating the water phase and the organic phase by using a separating funnel, and carrying out rotary evaporation on the organic phase to obtain the target aromatic hydroxyl-terminated polyether end-capping modifier.

Preparing nylon powder:

and (4) SS1: adding 1.72kg of decamethylenediamine, 2.02kg of sebacic acid and 3.74kg of deionized water into a reaction kettle (the molar ratio of amine to acid is 1.

And SS2: adding 3.6kg of nylon 1010 salt, 5.4g of tetrabutyl titanate and 100g of end-capping modifier into a polymerization kettle (the molar ratio of the sum of the nylon raw materials to the end-capping modifier is 120:1, the molar ratio of the nylon 1010 salt to the end-capping modifier is 60:1, and tetrabutyl titanate is 0.15% of the salt mass), adding 288g of deionized water (the weight of deionized water is 8% of the salt weight), replacing air in the kettle with nitrogen for three times after the deionized water is added, introducing nitrogen with the pressure of 0.2MPa (gauge pressure) as inert gas protection gas, heating to 210 ℃, keeping the pressure in the reaction kettle to be about 3MPa, maintaining the pressure for 1h, slowly reducing the pressure to normal pressure, heating to 250 ℃, vacuumizing, reducing the pressure, draining, continuing to react for 2h, stopping heating, and cutting into granules after water cooling and bracing to obtain nylon granules 66.

And SS3: adding 1kg of nylon 1010 granules, 5kg of ethanol, 1g of antioxidant 1098 and 1g of antioxidant 168 into a high-pressure reaction kettle (the weight ratio of the nylon 1010 to the ethanol solvent to the antioxidant 1098 to the antioxidant 168 is 1: 0.1%), stirring and heating to 150 ℃, keeping the temperature for 1h, maintaining the pressure at 0.8MPa, then cooling and reducing the pressure to normal pressure, and separating out nylon 1010 powder. After drying the nylon 1010 powder by a centrifuge, placing the dried nylon 1010 powder in a vacuum oven to remove residual solvent.

Evaluation of nylon powder:

3D printing test is carried out on the powder continuously recycled for 8 times on the basis of not adding new powder, the forming parameters of each recycling are the same, the temperature of a temperature field is set to be 185 ℃, the laser power is 45W, the scanning speed is 4000mm/s, the powder laying thickness is 0.1mm, and sintering is carried out under the condition that the scanning distance is 0.1mm, and the melt index (235 ℃,2.16 kg), the tensile strength and the tensile breaking elongation of the powder are changed along with the sintering times as shown in Table 3:

TABLE 3 PA1010 powder melt index and variation in physical Properties of sintered article

Example 4

S1: 950g of monoamine polyetheramine M-1000, 134g of benzoic acid, 573g of dehydrating agent EDCI and 244.4g of catalyst DMAP (molar ratio 1:1.1:3₂ SO₄ Adding into the solution and standingAfter 1h, the product was filtered.

S2: adding the product S1 into 0.8L of anhydrous dichloromethane, placing the system into a dry ice-acetone bath, dropwise adding 135.6g of boron trifluoride (molar ratio is 1: 2), naturally heating to room temperature, stirring for reaction for 3 hours, and adding 0.8L of pure water to quench the reaction; separating the water phase and the organic phase by using a separating funnel, and carrying out rotary evaporation on the organic phase to obtain the target aromatic hydroxyl-terminated polyether end-capping modifier.

Preparing nylon powder:

and (4) SS2: adding 1.97kg of laurolactam, 4.9g of tetrabutyl titanate and 90g of end-capping modifier into a reaction kettle (the molar ratio of the laurolactam to the end-capping modifier is 110.

And (4) SS3: adding 1kg of nylon 12 granules, 5kg of ethanol, 1g of antioxidant 1098 and 1g of antioxidant 168 into a high-pressure reaction kettle (the weight ratio of the nylon 12 to the ethanol solvent to the antioxidant 1098 to the antioxidant 168 is 1. Drying the nylon 12 powder by a centrifuge, and then placing the dried nylon 12 powder in a vacuum oven to remove residual solvent.

Evaluation of nylon powder:

the 3D printing test is carried out on the basis of continuously recycling for 8 times without adding new powder, the recycling forming parameters of each time are the same, the temperature of a temperature field is set to be 170 ℃, the laser power is set to be 45W, the scanning speed is 4000mm/s, the powder laying thickness is 0.1mm, and the sintering is carried out under the condition that the scanning distance is 0.1mm, and the melting index, the tensile strength and the tensile breaking elongation of the powder change along with the sintering times as shown in Table 4:

TABLE 4 PA12 powder melt index and change in physical Properties of sintered article

Comparative example 1

Compared with example 1, except that adipic acid was used as the end-capping agent.

Preparing nylon powder:

and (4) SS1: adding 1.72kg of decamethylene diamine, 2.30kg of dodecanedioic acid and 4kg of deionized water into a reaction kettle (the molar ratio of amine to acid is 1.

And (4) SS2: adding 3.8kg of nylon 1012 salt and 26.6g of adipic acid (end-capping agent) into a polymerization kettle (the molar ratio of the sum of the nylon raw material to the adipic acid is 110.

And (4) SS3: adding 1kg of nylon 1012 granules, 5kg of ethanol, 1g of antioxidant 1098 and 1g of antioxidant 168 into a high-pressure reaction kettle (the weight ratio of the nylon 1012 to the ethanol solvent to the antioxidant 1098 to the antioxidant 168 is 1. After drying the nylon 1012 powder by a centrifuge, the powder is placed in a vacuum oven to remove residual solvent.

Evaluation of nylon powder:

the selective laser sintering environment is simulated in a heating furnace, the temperature is 170 ℃ in the nitrogen atmosphere, and the melting index of the powder changes along with time in the high-temperature aging process of the powder, which is shown in figure 1.

3D printing test is carried out on the powder continuously recycled for 8 times on the basis of not adding new powder, the forming parameters of each recycling are the same, the temperature of a temperature field is set to be 170 ℃, the laser power is 45W, the scanning speed is 4000mm/s, the powder laying thickness is 0.1mm, and sintering is carried out under the condition that the scanning distance is 0.1mm, and the melt index (235 ℃,2.16 kg), the tensile strength and the tensile breaking elongation of the powder are changed along with the sintering times as shown in Table 5:

TABLE 5 PA1012 powder melt index and variation in physical Properties of sintered article

Compared with example 1, except that adipic acid is used as the end capping agent, it can be seen from table 5 that the melt index of PA1012 powder is significantly reduced, i.e. the melt flowability is significantly reduced, as the sintering times are increased; meanwhile, the tensile strength, the elongation at break and the impact toughness of the composite material are lower, but the tensile strength is increased to a certain extent along with the increase of the multiplexing times, and the elongation at break shows an obvious descending trend; the impact toughness of the material shows a trend of increasing and then decreasing along with the increase of the reuse times. The melt flowability and mechanical properties are poorer than those of the novel end capping modifier used in example 1.

Comparative example 2

The process is similar to example 4, except that adipic acid is used as the capping agent.

Preparing nylon powder:

and (4) SS2: adding 1.97kg of laurolactam and 13.3g of adipic acid (end-capping reagent) into a reaction kettle (the molar ratio of the laurolactam to the adipic acid is 110.

And (4) SS3: adding 1kg of nylon 12 granules, 5kg of ethanol, 1g of antioxidant 1098 and 1g of antioxidant 168 into a high-pressure reaction kettle (the weight ratio of the nylon 12 to the ethanol solvent to the antioxidant 1098 to the antioxidant 168 is 1: 0.1%), stirring and heating to 150 ℃, keeping the temperature for 1h, maintaining the pressure at 0.8MPa, then cooling and reducing the pressure to normal pressure, and separating out nylon 12 powder. After drying the nylon 12 powder by a centrifuge, placing the dried nylon 12 powder in a vacuum oven to remove residual solvent.

Evaluation of nylon powder:

the 3D printing test is carried out on the basis of continuously recycling for 8 times without adding new powder, the recycling forming parameters of each time are the same, the temperature of a temperature field is set to be 170 ℃, the laser power is set to be 45W, the scanning speed is 4000mm/s, the powder laying thickness is 0.1mm, and the sintering is carried out under the condition that the scanning distance is 0.1mm, and the melting index, the tensile strength and the tensile breaking elongation of the powder change along with the sintering times as shown in Table 6:

TABLE 6 PA12 powder melt index and change in physical Properties of sintered article

Compared with example 4, the difference is that adipic acid is used as the end-capping reagent, and as can be seen from table 6, as the sintering frequency increases, the melt index of the PA12 powder is significantly reduced, and meanwhile, the tensile strength, the elongation at break and the impact toughness are all lower, but as the multiplexing frequency increases, the tensile strength increases to a certain extent, and the elongation at break shows a significantly decreasing trend; the impact toughness of the material shows a trend of increasing firstly and then decreasing with the increase of the reuse times. The melt flowability and mechanical properties were inferior to those obtained by using the novel end-capping modifier in example 4.

After the nylon 12 powder prepared by the invention is repeatedly sintered for eight times, the melt index is reduced to 42.3g/10min from 48.8g/10min, and is reduced by 13.3 percent compared with the melt index of the new powder, the tensile strength and the elongation at break of a formed part prepared from the powder after end capping modification are not obviously reduced after being reused for 8 times, and the impact toughness is more stable. Therefore, the aromatic hydroxyl-terminated polyether end-capping modifier with a novel structure is introduced, so that the reduction of melt fluidity caused by the increase of molecular weight and molecular chain entanglement in the sintering process of nylon powder can be effectively avoided, the reusability of the powder is obviously improved, and the toughness of a formed part is enhanced.

Claims

1. The nylon powder for 3D printing with high multiplexing rate is characterized by being prepared from a nylon monomer and a blocking modifier, wherein the blocking modifier has the following structure:

among them, X =1 to 20, and preferably X =5 to 15.

2. The nylon powder of claim 1, wherein the nylon monomer is a raw material for preparing one or more of PA6, PA11, PA12, PA66, PA610, PA612, PA1010, PA1012, PA 1212;

preferably, the molar ratio of the nylon monomer to the end capping modifier is (100-130): 1, and preferably (110-120): 1.

3. The nylon powder of claim 1 or 2, wherein the end-capping modifier is prepared by:

4. The nylon powder of claim 3, wherein S1 the monoamine polyetheramine has the structure:

wherein, X =1 to 20, preferably X =5 to 15;

and/or S1, the organic solvent I is anhydrous dimethylformamide and/or dichloromethane;

and/or, the dehydrating agent of S1 is a carbodiimide condensing agent, preferably 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide;

and/or, the catalyst of S1 is a nucleophilic acylation catalyst, preferably 4-dimethylaminopyridine;

preferably, the molar ratio of the monoamine polyether amine, the benzoic acid, the dehydrating agent and the catalyst is 1 (1-1.1) to 1-3 to 0.5-2;

and/or, S1 is washed with saturated NaCl solution and anhydrous Na₂ SO₄ Drying;

and/or, S1 said compound A has the following structure:

among them, X =1 to 20, and preferably X =5 to 15.

5. The nylon powder according to claim 3, wherein the organic solvent II of S2 is dichloromethane and/or N, N-dimethylformamide;

and/or the Lewis acid S2 is boron tribromide and/or boron trifluoride;

preferably, the molar ratio of the Lewis acid to the compound A is (1-2): 1;

and/or, cooling the S2 by using a dry ice-acetone bath, and naturally heating to room temperature;

and/or stirring and reacting the S2 for 2-4 h;

and/or, S2 is quenched by addition of water.

6. A preparation method of nylon powder for 3D printing with high reuse rate, wherein the nylon powder is the nylon powder in any one of claims 1-5, and the method comprises the following steps:

and (4) SS2: adding nylon salt B or a nylon monomer for homopolymerization, water, a termination modifier and a catalyst into a polymerization reaction kettle for reaction, and then carrying out bracing and grain cutting to obtain target nylon C;

and SS3: and (3) dissolving the nylon C in an organic solvent IV, filtering and drying to obtain nylon powder.

7. The method for preparing nylon powder according to claim 6, wherein the dibasic acid described in SS1 is one or more of adipic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, and tetradecanedioic acid;

and/or the diamine in SS1 is one or more of hexamethylene diamine, decamethylene diamine, undecamethylene diamine, dodecamethylene diamine, tridecamethylene diamine and tetradecamethylene diamine.

8. The method for preparing nylon powder according to claim 6, wherein the nylon monomer for homopolymerization described in SS2 is one or more selected from caprolactam, undecylaminoundecanoic acid, and laurolactam;

and/or the SS2 catalyst is zirconium n-butyl alcohol and/or tetrabutyl titanate;

preferably, the adding amount of the catalyst is 0.1-0.3% by mass of the nylon salt and/or the nylon monomer for homopolymerization.

9. The method for preparing nylon powder of claim 6, wherein the organic solvent IV of SS3 is absolute ethanol and/or N, N-dimethylformamide, preferably absolute ethanol.