A kind of nylon powder and its continuous preparation method

Abstract

The present invention provides a method for continuously preparing nylon powder, comprising: (1) rapidly heating nylon 12 resin in a solvent until it is dissolved, and then cooling it to 120-125°C; (2) transferring the reaction material to a first stirring tank, and controlling the temperature in the first stirring tank to be 116-118°C; (3) transferring the reaction material in the first stirring tank to a second stirring tank, and controlling the temperature in the second stirring tank to be 112-114°C; (4) transferring the reaction material in the second stirring tank to a third stirring tank, and controlling the temperature in the third stirring tank to be 65-75°C, and subjecting the reaction product to solid-liquid separation and drying to obtain nylon powder; wherein the solvent is a mixed solvent composed of an alcohol solvent and an amide solvent; and the nylon 12 resin is polymerized by laurolactam with a dibasic acid and a tribasic acid. The present invention enables the reaction material to be rapidly cooled, nucleated, and precipitated in large quantities by controlling the process conditions and selecting the nylon resin, thereby obtaining a nylon powder with a narrow distribution.

Description

Technical Field

[0001] The invention belongs to the technical field of preparing nylon powder, and in particular relates to a process for continuously preparing nylon powder. Background Art

[0002] Nylon powder is widely used in powder coatings, 3D printing and other technical fields due to its excellent chemical resistance and mechanical properties. In the prior art, there are two main methods for preparing nylon powder: solvent precipitation and cryogenic grinding. Among them, the nylon powder prepared by solvent precipitation has more regular particles and higher sphericity, which helps the nylon powder to obtain a higher bulk density.

[0003] The existing solvent precipitation process generally uses industrial ethanol as a solvent, such as the method described in CN1197082A. After mixing nylon resin with ethanol and heating to dissolve, the precipitation of nylon powder in the solution is divided into two stages. The first stage is reduced to nucleation without producing a large amount of precipitation, and the second stage is cooled to supersaturation until all the powder is precipitated, and finally nylon powder is obtained. The reactor of the above method is mostly a kettle type, and the preparation process is mostly an intermittent process. Therefore, different production batches of nylon powder are prone to large differences in powder particle size, morphology and other specifications. At the same time, its production capacity is small, which limits the large-scale use of nylon powder.

[0004] In the method of preparing nylon powder by solvent precipitation, the reaction system needs to be cooled at different cooling rates at different stages of the nylon powder cooling and precipitation process, and the jacket temperature needs to be cooled at the same cooling rate, while the temperature difference between the jacket and the reaction material needs to be within a suitable range. If continuous production is carried out according to a similar process, the complexity of the design will be greatly increased. Based on the currently known prior art, the continuous solvent precipitation process of nylon powder is quite difficult.

[0005] Therefore, there is a need for an improved method for continuously preparing nylon powder, which simplifies the production process and has high production efficiency, and can obtain nylon powder with a narrow particle size distribution. Summary of the invention

[0006] In order to overcome the deficiencies in the prior art, the present invention controls the process conditions and selects the nylon resin so that the reaction materials can be quickly cooled, nucleated and precipitated in large quantities to obtain nylon powder with a narrow particle size distribution.

[0007] In order to achieve the purpose of the present invention, the present invention adopts the following technical solutions:

[0008] The present invention provides a method for continuously preparing nylon powder in a first aspect, comprising the following steps:

[0009] (1) rapidly heating nylon 12 resin in a solvent until it is dissolved, and then cooling it to 120-125° C. to obtain a reaction mass;

[0010] (2) transferring the reaction material into a first stirring tank, and controlling the temperature in the first stirring tank to be 116-118° C.;

[0011] (3) transferring the reaction material in the first stirring tank to a second stirring tank, and controlling the temperature in the second stirring tank to be 112-114° C.;

[0012] (4) transferring the reaction material in the second stirring tank to a third stirring tank, controlling the temperature in the third stirring tank to be 65-75° C., and then subjecting the reaction product to solid-liquid separation and drying to obtain nylon powder;

[0013] In step (1), the solvent is a mixed solvent consisting of an alcohol solvent and an amide solvent;

[0014] The nylon 12 resin is polymerized by laurolactam, dibasic acid and tribasic acid. During the polymerization process, the usage ratio of laurolactam to the tribasic acid is 100:(0.1-0.3), for example, 100:0.2.

[0015] In some specific embodiments, the usage ratio of laurolactam to the dibasic acid during the polymerization of nylon 12 resin is 100:(0.25-0.7), for example, 100:0.3, 100:0.4, 100:0.5, 100:0.6.

[0016] In a specific embodiment of the method of the present invention, in step (1), the tribasic acid is selected from one or more of trimesic acid, hydroxytrisaccharic acid, trimesic acid or 1,2,4-trimesic acid, preferably trimesic acid.

[0017] In some specific embodiments, the mass ratio of the alcohol solvent to the amide solvent in the solvent in step (1) is 100:(5-15), for example, 100:5, 100:8, 100:10, 100:12; the amide solvent is selected from one or more of N-methylformamide, N-methylacetamide, N,N-dimethylformamide, N,N-dimethylacetamide or N-methylpyrrolidone; the alcohol solvent is an aliphatic alcohol with 1 to 3 carbon atoms. In some more specific embodiments, the alcohol solvent can be selected from industrial ethanol, and the amide solvent can be selected from N,N-dimethylformamide (abbreviated as "DMF").

[0018] In a specific embodiment of the method of the present invention, in step (1), the nylon 12 resin is first melted under heating conditions to obtain a melt state, and then mixed with the heated solvent to obtain a reaction material; specifically, the two materials can be circulated and fully mixed in a loop reactor at a certain feed rate. Then, the mixed materials can be quickly cooled through a shell-and-tube heat exchanger to obtain a reaction material.

[0019] In step (2) of the method of the present invention, the reaction materials enter the first stirring tank and react under the stirring action of the first stirring tank. In some specific embodiments, the stirring speed in the first stirring tank can be 70 to 90 rpm, for example, 75 rpm, 80 rpm; and the reaction pressure in the first stirring tank is controlled to be 365 to 395 KPa, for example, 370 KPa, 380 KPa, 385 KPa, 390 KPa by ethanol discharge.

[0020] In step (3) of the method of the present invention, the material after the reaction in the first stirring tank enters the second stirring tank for reaction. In some specific embodiments, the stirring speed in the second stirring tank can be 110-130 rpm, for example, 115 rpm, 120 rpm; and the reaction pressure in the second stirring tank is controlled to be 320-345 KPa, for example, 330 KPa, 340 KPa by ethanol discharge.

[0021] In step (4) of the method of the present invention, the reaction material in the second stirring tank is transferred to the third stirring tank. In some specific embodiments, the stirring speed in the third stirring tank can be 40 to 60 rpm, for example, 50 rpm; and the temperature in the third stirring tank is rapidly cooled to 65 to 75° C. by ethanol vaporization and jacket heat transfer.

[0022] In some specific embodiments, the first stirring tank and the second stirring tank are provided with jackets to remove the reaction heat in the stirring tanks; the jacket outside the third stirring tank is filled with cooling water at a temperature of 15°C to rapidly cool down the temperature in the third stirring tank. The residence time of the reaction materials in the first stirring tank, the second stirring tank and the third stirring tank is 10 to 30 minutes, for example, 15 minutes, 20 minutes.

[0023] In a second aspect, the present invention provides a nylon powder prepared by the method, wherein the median diameter (D50) of the nylon powder is 50 to 80 μm, for example, 60 μm, 75 μm, 80 μm; in some preferred embodiments, the median diameter (D50) of the nylon powder is 50 to 65 μm, for example, 55 μm, 60 μm, 62 μm.

[0024] The particle size distribution width (ie, D90-D10) of the nylon powder is 40 to 90 μm, for example, 50 μm, 60 μm, 70 μm, 80 μm; in some preferred embodiments, the particle size distribution width of the nylon powder is 45 to 55 μm, for example, 50 μm, 52 μm.

[0025] The above technical solution has the following technical effects:

[0026] The method of the present invention uses a nylon resin with a tribasic acid component containing a certain proportion of trifunctional groups as a matrix and a composition obtained by compounding a good solvent and a fatty alcohol as a solvent; at the same time, the method of the present invention controls the temperature and pressure conditions in each preparation process, so that the temperature range between the nucleation temperature and the bulk precipitation temperature in the cooling precipitation process is significantly narrowed, thereby simplifying the production process and realizing the continuous preparation of nylon powder. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 : A specific process flow chart for continuously preparing nylon powder used in the examples of the present invention;

[0028] Among them, 1. loop reactor, 2. shell and tube heat exchanger, 3. first stirring tank, 4. second stirring tank, 5. third stirring tank, 6. centrifuge, 7. dryer. DETAILED DESCRIPTION

[0029] In order to facilitate the understanding of the present invention, the present invention will be further described below in conjunction with examples. It should be understood that the following examples are only for a better understanding of the present invention and do not mean that the present invention is limited to the following examples.

[0030] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0031] Where specific experimental steps or conditions are not specified in the examples, the corresponding conventional experimental steps or conditions in the art can be used. The reagents or instruments used without specifying the manufacturer are all conventional products that can be purchased commercially.

[0032] The raw material sources of the following examples and comparative examples are as follows:

[0033] Lauryl lactam: Purchased from Wanhua Chemical;

[0034] Adipic acid: purchased from Henan Shenma;

[0035] Trimesic acid: purchased from Aladdin;

[0036] N,N-Dimethylformamide (DMF): purchased from Hualu Hengsheng.

[0037] The products obtained in the following examples and comparative examples are specifically tested using the following test methods:

[0038] D10 (μm), D50 (μm), D90 (μm): integrated particle size distribution measured by laser diffraction method;

[0039] Particle size distribution width: The difference between the integrated distribution functions D90 and D10, i.e. (D90-D10).

[0040] The following examples specifically use the Figure 1 In the continuous preparation process shown, specifically, nylon resin and solvent are mixed in a loop reactor 1, and transported to a shell-and-tube heat exchanger 2 through a pipeline for rapid cooling to obtain a reaction material; then the reaction material is transported to a first stirring tank 3 for reaction, and the reacted material is sequentially transported to a second stirring tank 4 and a third stirring tank 5 for further reaction. The reaction product obtained after the reaction in the third stirring tank 5 is separated into solid and liquid by a centrifuge 6, and finally dried in a dryer 7 to obtain a nylon powder product.

[0041] Comparative Example 1

[0042] In a 1m 3 Into a stirring container, 300 kg of lauryl lactam, 15 kg of water and 2.1 kg of adipic acid were added, the temperature was raised to 270°C and the polymerization was allowed to stand for 3 hours. After the system was depressurized to normal pressure, it was evacuated at 250°C for 1 hour (the vacuum degree was maintained below -85 KPa). After the system was cooled to 220°C, the material was discharged, water-cooled and pelletized to obtain nylon resin 1. The relative viscosity of nylon resin 1 was 1.62.

[0043] (1) The nylon resin 1 obtained above was used as a resin raw material, heated to 200° C. by a hot oil jacket to become a melt state, and then fed at a feed rate of 5 kg / h; at the same time, industrial ethanol was used as a solvent and heated to 180° C., and then fed at a feed rate of 20 kg / h;

[0044] The nylon resin 1 in a molten state is mixed with industrial ethanol in a loop reactor (circulated more than 10 times), and then rapidly cooled to 120° C. via a shell-and-tube heat exchanger to obtain a reaction material;

[0045] (2) The reaction material then enters the first stirring tank, the stirring speed in the first stirring tank is 75 rpm, the reaction pressure is controlled at about 393 KPa by ethanol discharge, and the reaction temperature is 118 ° C. The reaction material stays in the stirring tank for 30 minutes;

[0046] (3) The material in the first stirring tank then enters the second stirring tank through a pipeline. The stirring speed in the second stirring tank is 120 rpm. The reaction pressure is controlled at about 345 KPa by ethanol discharge, and the reaction temperature is 114° C. The reaction material stays in the stirring tank for 30 minutes.

[0047] (4) The material in the second stirring tank then enters the third stirring tank through a pipeline. The stirring speed in the third stirring tank is 50 rpm. The temperature in the third stirring tank is rapidly cooled to 75° C. by ethanol vaporization and jacket heat transfer. The reaction material stays in the stirring tank for 30 minutes. The reaction product is then separated into solid and liquid by a centrifuge and dried in a dryer to obtain a nylon powder product.

[0048] After testing, the nylon powder product obtained above had D10=15 μm, D50=87 μm, D90=143 μm; (D90-D10)=128 μm.

[0049] Comparative Example 2

[0050] This comparative example prepares nylon powder by referring to the method of comparative example 1, and the difference from the method of comparative example 1 is:

[0051] In step (1), industrial ethanol and DMF are used as a mixed solvent (mass ratio is 100:5);

[0052] The reaction pressure of the first stirring tank in step (2) is 391 KPa;

[0053] The reaction pressure of the second stirring tank in step (3) is 342 KPa.

[0054] After testing, the nylon powder product obtained in this comparative example has D10=23 μm, D50=81 μm, D90=136 μm; (D90-D10)=113 μm.

[0055] Comparative Example 3

[0056] In a 1m 3 In a stirring container, 300 kg of lauryl lactam, 15 kg of water, 1.65 kg of adipic acid and 0.3 kg of trimesic acid were added thereto, the temperature was raised to 270°C and the polymerization was allowed to stand for 3 hours. After the system was depressurized to normal pressure, it was evacuated at 250°C for 1 hour (the vacuum degree was maintained below -85 KPa). After the system was cooled to 220°C, the material was discharged, water-cooled and pelletized to obtain nylon resin 2. The relative viscosity of nylon resin 2 was 1.63.

[0057] The method of comparative example 1 was used to prepare nylon powder using nylon resin 2 as the resin raw material. The difference from the method of comparative example 1 was that:

[0058] The reaction pressure of the first stirring tank in step (2) is 392 KPa;

[0059] The reaction pressure of the second stirring tank in step (3) is 341 KPa.

[0060] After testing, the nylon powder product obtained in this comparative example has D10=25 μm, D50=81 μm, D90=132 μm; (D90-D10)=107 μm.

[0061] Example 1

[0062] This example prepares nylon powder by referring to the method of Comparative Example 1, and the difference from the method of Comparative Example 1 is that:

[0063] In step (1), nylon resin 2 is used as the resin raw material, and industrial ethanol and DMF are used as a mixed solvent (mass ratio is 100:5);

[0064] The reaction pressure of the first stirring tank in step (2) is 395 KPa;

[0065] The reaction pressure of the second stirring tank in step (3) is 345 KPa.

[0066] After testing, the nylon powder product prepared in this embodiment has D10=32 μm, D50=76 μm, D90=118 μm; (D90-D10)=86 μm.

[0067] Example 2

[0068] This example prepares nylon powder by referring to the method of Comparative Example 1, and the difference from the method of Comparative Example 1 is that:

[0069] In step (1), nylon resin 2 is used as the resin raw material, and industrial ethanol and DMF are used as a mixed solvent (mass ratio is 100:10);

[0070] The reaction pressure of the first stirring tank in step (2) is 392 KPa;

[0071] The reaction pressure of the second stirring tank in step (3) is 342 KPa.

[0072] After testing, the nylon powder product prepared in this embodiment has D10=32 μm, D50=76 μm, D90=109 μm; (D90-D10)=77 μm.

[0073] Example 3

[0074] This example prepares nylon powder by referring to the method of Comparative Example 1, and the difference from the method of Comparative Example 1 is that:

[0075] In step (1), nylon resin 2 is used as the resin raw material, and industrial ethanol and DMF are used as a mixed solvent (mass ratio is 100:15);

[0076] The reaction pressure of the first stirring tank in step (2) is 393 KPa;

[0077] The reaction pressure of the second stirring tank in step (3) is 343 KPa.

[0078] After testing, the nylon powder product prepared in this embodiment has D10=31 μm, D50=71 μm, D90=115 μm; (D90-D10)=84 μm.

[0079] Example 4

[0080] In a 1m 3 In a stirring container, 300 kg of lauryl lactam, 15 kg of water, 1.2 kg of adipic acid and 0.6 kg of trimesic acid were added thereto, the temperature was raised to 270°C and the polymerization was allowed to stand for 3 hours. After the system was depressurized to normal pressure, it was evacuated at 250°C for 1 hour (the vacuum degree was maintained below -85 KPa). After the system was cooled to 220°C, the material was discharged, water-cooled and pelletized to obtain nylon resin 3. The relative viscosity of nylon resin 3 was 1.61.

[0081] The nylon powder was prepared by referring to the method of Comparative Example 1, which differed from the method of Comparative Example 1 in that:

[0082] In step (1), the nylon resin 3 prepared above is used as the resin raw material, and industrial ethanol and DMF are used as a mixed solvent (mass ratio is 100:10);

[0083] The reaction pressure of the first stirring tank in step (2) is 392 KPa;

[0084] The reaction pressure of the second stirring tank in step (3) is 341 KPa.

[0085] After testing, the nylon powder product prepared in this embodiment has D10=35 μm, D50=67 μm, D90=103 μm; (D90-D10)=68 μm.

[0086] Example 5

[0087] In a 1m 3 Into a stirring container, 300 kg of lauryl lactam, 15 kg of water, 0.75 kg of adipic acid and 0.9 kg of trimesic acid were added, the temperature was raised to 270°C and the polymerization was allowed to stand for 3 hours. After the system was depressurized to normal pressure, it was evacuated at 250°C for 1 hour (the vacuum degree was maintained below -85 KPa). After the system was cooled to 220°C, the material was discharged, water-cooled and pelletized to obtain nylon resin 4. The relative viscosity of nylon resin 4 was 1.64.

[0088] The nylon powder was prepared by referring to the method of Comparative Example 1, which differed from the method of Comparative Example 1 in that:

[0089] In step (1), the nylon resin 4 prepared above is used as the resin raw material, and industrial ethanol and DMF are used as a mixed solvent (mass ratio is 100:10);

[0090] The reaction pressure of the first stirring tank in step (2) is 391 KPa;

[0091] The reaction pressure of the second stirring tank in step (3) is 343 KPa.

[0092] After testing, the nylon powder product prepared in this embodiment has D10=31 μm, D50=65 μm, D90=108 μm; (D90-D10)=77 μm.

[0093] Example 6

[0094] This example prepares nylon powder by referring to the method of Comparative Example 1, and the difference from the method of Comparative Example 1 is that:

[0095] In step (1), nylon resin 3 is used as the resin raw material, and industrial ethanol and DMF are used as a mixed solvent (mass ratio is 100:10);

[0096] In step (2), the reaction pressure of the first stirring tank is 378 KPa, and the reaction temperature is 117° C.;

[0097] The reaction pressure of the second stirring tank in step (3) is 342 KPa.

[0098] After testing, the nylon powder product prepared in this embodiment has D10=31 μm, D50=56 μm, D90=84 μm; (D90-D10)=53 μm.

[0099] Example 7

[0100] This example prepares nylon powder by referring to the method of Comparative Example 1, and the difference from the method of Comparative Example 1 is that:

[0101] In step (1), nylon resin 3 is used as the resin raw material, and industrial ethanol and DMF are used as a mixed solvent (mass ratio is 100:10);

[0102] In step (2), the reaction pressure of the first stirring tank is 380 KPa and the reaction temperature is 117° C.;

[0103] The reaction pressure of the second stirring tank in step (3) is 342 KPa.

[0104] After testing, the nylon powder product prepared in this embodiment has D10=32 μm, D50=55 μm, D90=83 μm; (D90-D10)=51 μm.

[0105] Example 8

[0106] This example prepares nylon powder by referring to the method of Comparative Example 1, and the difference from the method of Comparative Example 1 is that:

[0107] In step (1), nylon resin 3 is used as the resin raw material, and industrial ethanol and DMF are used as a mixed solvent (mass ratio is 100:10);

[0108] In step (2), the reaction pressure of the first stirring tank is 368 KPa, and the reaction temperature is 116° C.;

[0109] The reaction pressure of the second stirring tank in step (3) is 341 KPa.

[0110] After testing, the nylon powder product prepared in this embodiment has D10=31 μm, D50=61 μm, D90=91 μm; (D90-D10)=60 μm.

[0111] Example 9

[0112] This example prepares nylon powder by referring to the method of Comparative Example 1, and the difference from the method of Comparative Example 1 is that:

[0113] In step (1), nylon resin 3 is used as the resin raw material, and industrial ethanol and DMF are used as a mixed solvent (mass ratio is 100:10);

[0114] In step (2), the reaction pressure of the first stirring tank is 375 KPa, and the reaction temperature is 117° C.;

[0115] In step (3), the reaction pressure of the second stirring tank is 335 KPa, and the reaction temperature is 113°C.

[0116] After testing, the nylon powder product prepared in this embodiment has D10=35 μm, D50=52 μm, D90=79 μm; (D90-D10)=44 μm.

[0117] Example 10

[0118] This example prepares nylon powder by referring to the method of Comparative Example 1, and the difference from the method of Comparative Example 1 is that:

[0119] In step (1), nylon resin 3 is used as the resin raw material, and industrial ethanol and DMF are used as a mixed solvent (mass ratio is 100:10);

[0120] In step (2), the reaction pressure of the first stirring tank is 377 KPa, and the reaction temperature is 117° C.;

[0121] In step (3), the reaction pressure of the second stirring tank is 330 KPa, and the reaction temperature is 113°C.

[0122] After testing, the nylon powder product prepared in this embodiment has D10=34 μm, D50=54 μm, D90=77 μm; (D90-D10)=43 μm.

[0123] Embodiment 11

[0124] This example prepares nylon powder by referring to the method of Comparative Example 1, and the difference from the method of Comparative Example 1 is that:

[0125] In step (1), nylon resin 3 is used as the resin raw material, and industrial ethanol and DMF are used as a mixed solvent (mass ratio is 100:10);

[0126] In step (2), the reaction pressure of the first stirring tank is 380 KPa and the reaction temperature is 117° C.;

[0127] In step (3), the reaction pressure of the second stirring tank is 320 KPa, and the reaction temperature is 112°C.

[0128] After testing, the nylon powder product prepared in this embodiment has D10=32 μm, D50=55 μm, D90=87 μm; (D90-D10)=55 μm.

Claims

1. A method for continuously preparing nylon powder, characterized in that: The following steps are involved: (1) rapidly heating nylon 12 resin in a solvent until it is dissolved, and then cooling it to 120-125° C. to obtain a reaction mass; (2) transferring the reaction material into a first stirring tank, and controlling the temperature in the first stirring tank to be 116-118° C.; (3) transferring the reaction material in the first stirring tank to a second stirring tank, and controlling the temperature in the second stirring tank to be 112-114° C.; (4) transferring the reaction material in the second stirring tank to a third stirring tank, controlling the temperature in the third stirring tank to be 65-75° C., and then subjecting the reaction product to solid-liquid separation and drying to obtain nylon powder; In step (1), the solvent is a mixed solvent consisting of an alcohol solvent and an amide solvent, and the mass ratio of the alcohol solvent to the amide solvent is 100:(5-15); The amide solvent is selected from one or more of N-methylformamide, N-methylacetamide, N,N-dimethylformamide, N,N-dimethylacetamide or N-methylpyrrolidone; the alcohol solvent is selected from aliphatic alcohols having 1 to 3 carbon atoms; The nylon 12 resin is polymerized by laurolactam, dibasic acid and tribasic acid. During the polymerization process, the mass ratio of laurolactam to the tribasic acid is 100:(0.1-0.3).

2. The method according to claim 1, characterized in that In step (1), the tribasic acid is selected from one or more of trimesic acid, trimesic acid or 1,2,4-trisic acid.

3. The method according to claim 2, characterized in that The tribasic acid is selected from trimesic acid.

4. The method according to claim 1, characterized in that: The alcohol solvent is selected from industrial ethanol, and the amide solvent is selected from N,N-dimethylformamide.

5. The method according to any one of claims 1 to 4, characterized in that: During the polymerization of the nylon 12 resin, the mass ratio of the laurolactam to the dibasic acid is 100:(0.25-0.7).

6. The method according to any one of claims 1 to 4, characterized in that: The pressure of the first stirring tank is controlled to be 365-395 KPa; The pressure of the second stirring tank is controlled to be 320-345 KPa.

7. The method according to claim 6, characterized in that The residence time of the reaction materials in the first stirring tank, the second stirring tank and the third stirring tank is 10 to 30 minutes.

8. A nylon powder prepared by the method according to any one of claims 1 to 7, characterized in that: The median diameter D50 of the nylon powder is 50 to 80 μm.

9. The nylon powder according to claim 8, characterized in that The median diameter D50 of the nylon powder is 50 to 65 μm.

10. The nylon powder according to claim 8, characterized in that The particle size distribution width of the nylon powder is 40 to 90 μm.

11. The nylon powder according to claim 10, characterized in that The particle size distribution width of the nylon powder is 45 to 55 μm.

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