KR20170132012A - PI powder for SLS-3D printer and Manufacturing method thereof - Google Patents

Abstract

The present invention relates to a PI powder for an SLS-3D printer and a method of manufacturing the same, and more specifically, it relates to a PI powder for an SLS-3D printer, which can reduce the crystallinity of a PI material, The present invention relates to a PI powder for an SLS-3D printer which can be applied as an SLS-3D printing material, and a method for commercial production thereof.

Description

Technical Field [0001] The present invention relates to a PI powder for an SLS-3D printer,

The present invention relates to a powder for a polyimide (PI) -based SLS-3D printer and a method of manufacturing the same, which is used for SLS (Selective Laser Sintering) 3D printing.

Recently, 3D printers have been increasingly interested in the possibility of using 3D printers. Since the first development of the 3D printers in 1984, the range of applications from product models to prototypes has been continuously increasing. Recently, the United States and other countries have announced 3D printing with production technology that will lead the global megatrend of manufacturing, and the feature of small quantity production of customized multi-product of 3D printing has been attracting much attention, It is used for product development in various industries such as automobile, aerospace, defense industry and medical equipment which have high technical difficulties such as jewelery, toys, fashion and entertainment industry and the fusion technology with culture, life and nano science. In addition, as the worldwide patent pending stratasys patent expires in February 2014, an open source project such as RepRap in the UK has begun, and important technical data for the production of printers have been uploaded to the Internet This area is exploding explosively as it is shared.

Such 3D printers can be classified as solid-based extrusion lamination FDM (fused deposition modeling), powder based SLS (selective laser sintering), 3DP (Powder bed and inkjet head printing), EBM These materials are divided into Stereolithography (SLA), Digital Light Processing (DLP), Polyjet (Photopolymer jetting) and Laminated LOM (Laminated Object Manufacturing). These printers are used for printing Materials such as filaments, powders, and liquid resins play an important role.

Powder-based SLS printing is a method of manufacturing a three-dimensional shaped product by repeatedly forming a sintered layer by irradiating a light beam (directional energy beam, for example laser) onto a predetermined portion of the powder layer, Including a state having a large number of voids (holes) and / or a state in which the metal composition is substantially completely dissolved and solidified, that is, a state having a density (sintered density) of about 100% It is a 3D printing method that can obtain a sculpture.

Various materials such as metal powders and polymer powders are used as SLS-3D printing materials, and polyimide, which is a super plastic material, is recently applied as a 3D printing material. However, polyimide is not yet applied to SLS-3D printing materials because polyamide and / or polyimide powder has poor processability due to poor melt flowability and high strength parts SLS-3D printing is limited due to the impossibility of manufacturing, and it is difficult to realize material properties due to low packing density.

Korean Unexamined Patent Publication No. 2002-0087250 (published November 22, 2002)

S.Koskins, 3D printing for artists, desiners and makers, Bloomsbury, 2013.

The present inventors have found that when the crystallinity of the polyimide is lowered or eliminated and the degree of imidization of the polyimide is controlled, it is possible to secure the proper melt flowability of the polyimide powder during SLS-3D printing and secure the packing density of the material And it is found that a solvent such as m-cresol having different compatibility is not required to be used in order to remove water generated when the polyamic acid is converted into polyimide, thereby completing the present invention. That is, the present invention provides a polyimide powder applicable as a material for an SLS-3D printer and a method of manufacturing the same.

In order to solve the above-mentioned problems, the material for an SLS-3D printer of the present invention is a polyimide powder imidized with a polyamic acid resin obtained by polymerizing a diamine represented by the following formula (1) and an acid anhydride represented by the following formula

[Chemical Formula 1]

,

,

또는

이며, 상기 R¹은 수소원자, C1 ~ C3의 알킬기, -OH 또는 -COOR²이고, R²는 수소원자 또는 C1 ~ C3의 알킬기이며,In formula (1), A represents a straight chain alkylene group of C1 to C5, a branched alkylene group of C3 to C5,

,

,

or

R ¹ is a hydrogen atom, a C ¹ to C 3 alkyl group, -OH or -COOR ² , R ² is a hydrogen atom or a C 1 to C 3 alkyl group,

(2)

이고, R³는 수소원자, 메틸기, -CH₂F, -CHF₂ 또는 -CF₃이다.In formula (2), B represents an oxygen atom or

And R ³ is a hydrogen atom, a methyl group, -CH ₂ F, -CHF ₂ or -CF ₃ .

,

또는

이고, R¹은 수소원자 또는 COOR²이고, R²는 수소원자 또는 C1 ~ C2의 알킬기일 수 있다.As a preferred embodiment of the present invention, A in the above formula

,

or

, R ¹ is a hydrogen atom or COOR ² , and R ² is a hydrogen atom or an alkyl group having 1 to ² carbon atoms.

이고, R³는 CH₂F, -CHF₂ 또는 -CF₃일 수 있다.In one preferred embodiment of the present invention, B in the above formula (2) is an oxygen atom or

And R ³ can be CH ₂ F, -CHF ₂ or -CF ₃ .

In one preferred embodiment of the present invention, the polyamic acid resin may be one obtained by polymerizing the diamine and the acid anhydride in a molar ratio of 1: 1 to 1.4.

In one preferred embodiment of the present invention, the polyamic acid resin may have a solid content of 18 to 25% by weight.

In one preferred embodiment of the present invention, the polyimide is an amorphous polyimide, and the imidization degree may be 50% to 85%.

In one preferred embodiment of the present invention, the polyimide powder may include particles (powders) having a size of 0.1 mu m to 200 mu m.

In one preferred embodiment of the present invention, the polyimide powder may have a particle size distribution D10 of 10 mu m to 20 mu m, a D50 of 20 mu m to 40 mu m, and a D90 of 40 mu m to 60 mu m.

In one preferred embodiment of the present invention, the polyimide powder may have a melting point (T _m ) of 310 ° C. to 350 ° C. and a thermal decomposition temperature (T _d 5 wt%) of 570 ° C. to 590 ° C.

In one preferred embodiment of the present invention, the polyimide powder may have an apparent density of 0.300 or more and a tap density of 0.400 or more.

Another object of the present invention is to provide a method for producing a polyimide powder as a material for SLS-3D printer described above, wherein a diamine represented by the following general formula (1) and an acid anhydride represented by the following general formula (2) A step of preparing a resin; A step of aging the polyamic acid resin; A third step of preparing a polyimide solid by performing an imidation reaction on the aged polyamic acid resin; Washing the polyimide solid to remove unreacted monomers and impurities; A fifth step of heat-treating the washed polyimide solid to remove the solvent; And 6) pulverizing and solidifying the heat-treated polyimide solid body.

[Chemical Formula 1]

,

,

또는

이며, 상기 R¹은 수소원자, C1 ~ C3의 알킬기, -OH 또는 -COOR²이고, R²는 수소원자 또는 C1 ~ C3의 알킬기이며,In formula (1), A represents a straight chain alkylene group of C1 to C5, a branched alkylene group of C3 to C5,

,

,

or

R ¹ is a hydrogen atom, a C ¹ to C 3 alkyl group, -OH or -COOR ² , R ² is a hydrogen atom or a C 1 to C 3 alkyl group,

(2)

이고, R³는 수소원자, 메틸기, -CH₂F, -CHF₂ 또는 -CF₃이다.In formula (2), B represents an oxygen atom or

And R ³ is a hydrogen atom, a methyl group, -CH ₂ F, -CHF ₂ or -CF ₃ .

In one preferred embodiment of the present invention, the solvent of the first step is at least one selected from the group consisting of N-methylpyrrolidone (NMP), N-ethylpyrrolidone (NEP), dimethylacetamide (DMAc), 3-methoxy- Methoxy-N, N-dimethylpropionamide or 3-butoxy-N, N-dimethylpropionamide.

In one preferred embodiment of the present invention, the polyamic acid resin of the first stage may be one obtained by polymerizing the diamine and the acid anhydride in a molar ratio of 1: 1 to 1.4.

In one preferred embodiment of the present invention, the polyamic acid resin of the first step may have a solid content of 18 to 25% by weight.

As a preferred embodiment of the present invention, the two stages of aging can be carried out at 130 ° C to 150 ° C for 1 hour to 3 hours.

In one preferred embodiment of the present invention, the imidization reaction in three steps can be carried out at 180 ° C to 210 ° C for 1 hour to 3 hours.

As a preferred embodiment of the present invention, the heat treatment in five steps may be performed at 220 ° C to 250 ° C.

As a preferred embodiment of the present invention, the 6-step pulverization can be carried out using ACM (Air Classifying Mill), HSM (High Speed Mill) or TAM (Tubo Air Mill).

In one preferred embodiment of the present invention, the powdered polyimide in six steps may be an amorphous polyimide having an imidization degree of 50% to 85%.

The polyimide powder producing method of the SLS-3D printer according to the present invention does not use a solvent which inhibits the compatibility of m-cresol or the like for removing water generated in the imidization process when producing the polyimide powder, The polyimide powder of the present invention has an optimal imidization degree and thus voids generated during the SLS 3D printing process. In addition, the polyimide powder of the present invention is excellent in melt flowability and melt processability because of low crystallinity, Can be minimized and / or prevented, has high apparent density and tap density, and has excellent packing properties. Accordingly, it is an invention capable of providing a printing mold having high strength and high heat resistance.

1 is a scanning electron microscope photograph of the PI powder prepared in Example 1. Fig.
2 is a scanning electron microscope photograph of the PI powder prepared in Comparative Example 1. Fig.
3 is a scanning electron microscope photograph of the PI powder prepared in Comparative Example 2. Fig.
4 is a scanning electron microscope photograph of the PI powder prepared in Comparative Example 3. Fig.
5 shows the results of XRD measurements of Example 1 and Comparative Example 2 measured in Experimental Example 5.
6 shows the imidation degree evaluation results of Example 1 and Comparative Example 2 measured in Experimental Example 6. Fig.
FIG. 7A is a photograph of the SLS-3D printing formed product manufactured in Production Example 1, and FIG. 7B is a photograph of the SLS-3D printing molded product manufactured in Comparative Production Example 1. FIG.

The term " C1 ", "C2 ", etc. used in the present invention means a carbon number. For example," C1 to C5 alkyl "means an alkyl group having 1 to 5 carbon atoms.

"로 표현된 화학식에서 "*"표시는 치환기가 연결되는 부위를 의미한다.Further, in the present invention,

Quot; in the chemical formula represented by "" means a site to which a substituent is connected.

Hereinafter, the PI powder for SLS-3D printer of the present invention will be described in more detail.

The PI powder for an SLS-3D printer of the present invention comprises the steps of: 1) preparing a polyamic acid resin by polymerizing a diamine represented by the following formula (1) and an acid anhydride represented by the following formula (2) in a solvent; A step of aging the polyamic acid resin; A third step of preparing a polyimide solid by performing an imidation reaction on the aged polyamic acid resin; Washing the polyimide solid to remove unreacted monomers and impurities; A fifth step of heat-treating the washed polyimide solid to remove the solvent; And 6) pulverizing and pulverizing the heat-treated polyimide solid body.

[Chemical Formula 1]

,

,

또는

이며, 바람직하게는

,

또는

이고, 더욱 바람직하게는

이다. 그리고, 화학식 1의 상기 R¹은 수소원자, C1 ~ C3의 알킬기, -OH 또는 -COOR²이고, 바람직하게는 수소원자 또는 COOR²이고, 더욱 바람직하게는 수소원자이다. 또한, 상기 R²는 수소원자 또는 C1 ~ C3의 알킬기이며, 바람직하게는 수소원자이다.In Formula 1, A is a straight chain alkylene group having 1 to 5 carbon atoms, a branched alkylene group having 3 to 5 carbon atoms,

,

,

or

, And preferably

,

or

, And more preferably

to be. R ¹ in formula (1) is a hydrogen atom, an alkyl group having ¹ to 3 carbon atoms, -OH or -COOR ² , preferably a hydrogen atom or COOR ² , more preferably a hydrogen atom. R ² is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, preferably a hydrogen atom.

(2)

이고, 바람직하게는 산소원자이다. 그리고, R³는 -CHF₂ 또는 -CF₃이다.In the general formula (2), B represents an oxygen atom or

And is preferably an oxygen atom. And R ³ is -CHF ₂ or -CF ₃ .

Step 1 is a step of synthesizing polyamic acid, wherein the solvent is at least one selected from the group consisting of N-methylpyrrolidone (N-methylpyrrolidone), N-ethylpyrrolidone (NEP), dimethylacetamide (DMAc), 3-methoxy-N, N-dimethypropionamide N-dimethylpropionamide or 3-butoxy-N, N-Dimethylpropionamide, preferably NMP, Mac, 3-methoxy- Dimethipropionamide or 3-butoxy-N, N-dimethylpropionamide is preferably used.

In the first step polymerization, the diamine is added to a solvent, and then the acid anhydride is added and polymerized at a temperature of 15 ° C to 35 ° C, preferably 18 ° C to 30 ° C to prepare a polyamic acid resin can do.

The amount of the diamine and the acid anhydride to be used is preferably from 1: 1 to 1.4, more preferably from 1: 1 to 1.2, and the amount of the acid anhydride is less than 1 mol, Is too low to cause the imidization rate to drop to 50% or less in the imidization reaction, and if it exceeds 1.4 molar ratio, the unreacted acid anhydride is excessively generated. Therefore, the use of the diamine and the acid anhydride within the above- Polymerization is preferred.

The polyamic acid resin thus prepared may have a solid content of 18 to 25% by weight, preferably 18 to 23% by weight.

Step 2 is a step of aging the polyamic acid resin prepared in Step 1 to imidize the polyamic acid resin. The polyamic acid resin prepared in Step 1 is heated at 130 ° C to 150 ° C, preferably 135 ° C to 145 ° C for 1 to 3 hours And allowed to stand for aging. At this time, if the aging temperature is less than 130 ° C, the imidization rate may decrease. If the aging temperature exceeds 150 ° C, solidification may occur. Therefore, aging may be performed under the above temperature range.

Step 3 is a step of preparing a polyimide solid by subjecting an aged polyamic acid resin to an imidation reaction. The imidization reaction is carried out at 180 ° C to 210 ° C, preferably at 185 ° C to 200 ° C for 1 hour to 3 hours It is good to do. If the imidization reaction temperature is lower than 180 deg. C, the imidization reaction takes too long, the imidization is too small, and the imidization of the polyimide solid is too low to solidify during the reaction. The imidization proceeds too much, and the imidization of the polyimide solid is too high, so that carbonization of unreacted monomers may occur.

Step 4 is a step of removing the unreacted monomers and impurities of the polyimide solid produced in Step 3 and may be carried out by a general washing method used in the art. For example, polyimide solid is dissolved in acetone And the cleaning can be carried out by repeating this operation several times.

Step 5 is a step of performing a heat treatment for removing a cleaning solution remaining in the solvent, a residual solvent, moisture, and the like, and may be performed by a general heat drying process used in the related art. As a specific example, The solid body can be put into an oven at 220 ° C to 250 ° C.

Step 6 is a step of pulverizing the PI solid of step 5, and the pulverization method is not particularly limited as long as it is capable of pulverizing the PI solid body evenly. However, the method of pulverizing the PI solid is not limited to ACM (Air Classifying Mill), HSM (Tubo Air Mill) to be powdered.

The PI powder for an SLS-3D printer of the present invention prepared by pulverization as described above is an amorphous polyimide having an imidization degree of 50% to 85%, preferably an imidization degree of 54% to 80% The strength is somewhat reduced, but the melt processability is excellent.

The PI powder for an SLS-3D printer of the present invention includes a powder having a particle size of 0.1 to 200 탆, preferably a powder having a particle size of 10 to 200 탆, more preferably a particle size of 10 탆 To 100 [mu] m.

The PI powder for the SLS-3D printer may have a particle size distribution D10 of 10 to 20 占 퐉, a D50 of 20 to 40 占 퐉, a D90 of 40 to 60 占 퐉, 11.5 占 퐉 to 18 占 퐉, D50 of 22 占 퐉 to 35 占 퐉, D90 of 37 to 60 占 퐉, more preferably D10 of 12 占 퐉 to 15 占 퐉, and D50 of 24 占 퐉 to 30 占 퐉 , And D90 may be 38 to 50 mu m.

Therefore, the PI powder for the SLS-3D printer of the present invention can have a high bulk density and a tap density because the particle distribution is narrow and the particle shape is close to spherical.

Specifically, the PI powder for SLS-3D printer of the present invention may have a bulk density of 0.420 or more, preferably 0.425 to 0.480. In addition, the PI powder for SLS-3D printer of the present invention may have a tap density of 0.600 or more, preferably 0.620 to 0.690. Therefore, the PI powder for SLS-3D printer of the present invention has excellent packing property due to high bulk density and tap density.

The PI powder for the SLS-3D printer of the present invention may have a melting point (T _m ) of 310 ° C. to 350 ° C., preferably 315 ° C. to 340 ° C., and a pyrolysis temperature (T _{d 5 wt%} ) of 570 ° C. To 590 캜, preferably from 575 캜 to 590 캜.

The SLS-3D printer molded product manufactured using the PI powder for the SLS-3D printer of the present invention described above has excellent moldability and excellent mechanical properties such as tensile strength because there is no or little void in 3D printing .

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples should not be construed as limiting the scope of the present invention, and should be construed to facilitate understanding of the present invention.

[ Example ]

Example  One : SLS Manufacture of PI powder for -3D printer

560 g of NMP and the diamine 67.911 represented by the following formula 1-1 were added to a 1 L double jacket reaction tank and stirred at a temperature of 20 ° C and a speed of 150 rpm for 30 minutes. Then, 72.907 g of an acid anhydride represented by the following formula And then subdivided. Stirring was continued for 3 hours after the last acid anhydride was added, and the molar ratio of the acid anhydride to the diamine was 1.02: 1.

NMP and PAA (poly amic acid) varnish polymerized with 20 wt% solids were placed in a 1 L beaker type reactor, and then the temperature was raised from room temperature (24 ° C to 25 ° C) to 140 ° C and then aged at 140 ° C for 2 hours. No PI powder was formed during aging.

Next, the temperature was raised to 190 캜 and imidized at 190 캜 for 2 hours.

Next, the imidation reaction product was precipitated in 3 liters of acetone and washed 6 times to remove unreacted monomers and impurities to obtain a PI solid.

Next, the PI solid was heat-treated at 240 ° C to remove the solvent.

Next, the heat-treated PI solid was pulverized with an ACM (Air Classifying Mill) at a Mill Speed of 12,000 rpm for 20 minutes to obtain a pale brown PI powder.

[Formula 1-1]

이며, 상기 R¹은 수소원자이다.In formula (1-1), A represents

And R < ¹ > is a hydrogen atom.

[Formula 2-1]

In formula (2), B is an oxygen atom.

Comparative Example  One

560 g of NMP and 69.780 g of the diamine represented by the formula 1-1 of Example 1 were added to a 1 L double jacket reaction vessel and stirred at a temperature of 20 ° C at a speed of 150 rpm for 30 minutes. Then, 71.634 g of BPDA (biphenyl-tetracarboxylic acid dianhydride) 3 times. Stirring was continued for 3 hours after the addition of the last BPDA, wherein the molar ratio of acid anhydride to diamine was 1.02: 1.

NMP and PAA (poly amic acid) varnish polymerized with 20 wt% solids were placed in a 1 L beaker type reactor, and then the temperature was raised from room temperature (24 ° C to 25 ° C) to 140 ° C and then aged at 140 ° C for 2 hours.

Next, the temperature was raised to 190 캜 and imidized at 190 캜 for 2 hours.

Next, the imidation reaction product was precipitated in 3 liters of acetone and washed 6 times to remove unreacted monomers and impurities to obtain a PI solid.

Next, the PI solid was heat-treated at 240 ° C to remove the solvent.

Next, the heat-treated PI solid was treated at 14,000 rpm for 2 minutes and at 300 rpm for 30 seconds using a Powder Mixer to obtain yellow PI powder.

Comparative Example  2

392 g of m-cresol (m-Cresol) and 168 g of NMP were stirred in a 1 L double jacket reactor at 60 ° C and 150 rpm for 1 hour to prepare a mixed solvent.

Subsequently, 69.780 g of the diamine represented by the formula 1-1 of Example 1 was added to the mixed solvent, stirred at a temperature of 60 ° C at a speed of 150 rpm for 30 minutes, and then 71.634 g of BPDA was subdivided into three times. Stirring was continued for 3 hours after the last BPDA addition, wherein the molar ratio of acid anhydride to diamine was 1.02: 1.

Next, NMP and a PAA varnish polymerized with 20 wt% solids were placed in a 1 L beaker type reactor, and then the temperature was raised from room temperature (24 캜 to 25 캜) to 140 캜, followed by aging at 140 캜 for 2 hours.

During aging, PI powder was partially formed. In order to increase the particle size, it was re-reacted to 200 ° C and imidized at 200 ° C for 2 hours.

Next, the imidation reaction product was precipitated in 3 L of acetone and washed three times to remove unreacted monomers and impurities to obtain PI powder

Next, the PI solid was heat-treated at 240 ° C to remove the solvent, thereby obtaining yellow PI powder.

Comparative Example  3

The PI solid produced by the same method as in Example 1, and the heat-treated PI solid were pulverized under the same conditions as in Comparative Example 1 to obtain pale brown PI powder.

Experimental Example  1: melting point of the polyimide powder ( T _m ) And the thermal decomposition temperature (T _d )Measure

The melting point of the PI powder prepared in Example 1 and Comparative Examples 1 to 3 was measured using DSC, and the thermal decomposition temperature of the weight reduction 5 wt% portion was measured using TGA. .

division Melting point
( T _m , ° C) Pyrolysis temperature
(T _d , ° C) Example  One 328.5 578.3 Comparative Example  One 392.8 566.7 Comparative Example  2 389.7 558.9 Comparative Example  3 328.5 578.3

Experimental Example  2: Measurement of particle distribution of polyimide powder

The particle distribution of the PI powder prepared in Example 1 and Comparative Examples 1 to 3 was measured using a particle size analyzer. The results are shown in Table 2 below.

division D10 (占 퐉) D50 (占 퐉) D90 (占 퐉) Example  One 13.56 26.20 41.96 Comparative Example  One 24.88 86.90 166.60 Comparative Example  2 22.75 109.40 287.30 Comparative Example  3 28.26 121.60 313.30

Experimental Example  3: Measurement of apparent density and tap density of polyimide powder

Apparent density and tap density of the PI powder prepared in Example 1 and Comparative Examples 1 to 3 were measured according to ASTM D 1895 and ISO 3953, Respectively.

division Apparent density (g / cm ³ ) Tap density (g / cm ³ ) Example  One 0.432 0.662 Comparative Example  One 0.344 0.439 Comparative Example  2 0.473 0.587 Comparative Example  3 0.506 0.679

Experimental Example  4: Morphology measurement of polyimide powder

Samples of the PI powders of Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 were shown in the order of FIGS. 1 to 4, respectively.

The photograph of FIG. 1 shows that the particles are very dense, but the particles of FIGS. 2 to 4 are relatively large in comparison with those of FIG. 1.

As a result, the powder of Example 1 exhibits a dense particle size and a spherical shape close to spherical shape, so that it is possible to realize high physical properties through good packing in 3D printing.

Experimental Example  5: Polyimide powder XRD  Measure

The PI powders of Example 1 and Comparative Example 2 were subjected to XRD measurement, and the results are shown in FIG.

Referring to FIG. 5, it can be seen that the peak of Comparative Example 2 shows a sharp peak at around 15 degrees, which indicates that the PI of Comparative Example 2 exists in a crystalline region.

On the contrary, in the case of Example 1, it was confirmed that it represents a typical amorphous halo.

Experimental Example  6: Polyimide powder Imidazole  Measure

The imidization degree of the PI powder of Example 1 and Comparative Example 2 was calculated by Equation (1) and the PI film sample heat-treated at 450 ° C for 30 minutes was used as a reference. The results are shown in FIG. 5 and the imidization degree of Example 1 and Comparative Example 2 are shown in Table 4 below.

[Equation 1]

In the above formula (1), A _1370CN means that the influence of the base line pretreatment is minimized and that the imide is formed. A _1500BZ means a benzene peak of diamine.

division Imidazole ( % ) Example  One 56.41% Comparative Example  2 56.23%

Manufacturing example  One : SLS -3D Printing Mold Manufacture

The PI powder of Example 1 was developed using a CO ₂ laser-based SLS-3D printer. The laser power was 40 W, the frequency was 100 KHz, the scan speed was 500 mm / sec, the temperature in the chamber was 200 15 layer having a thickness of 200 탆 was laminated to prepare a SLS-3D printing mold having a thickness of 3.2 mm as shown in Fig. 7 (a).

Comparative Manufacturing Example  One

In the same manner as in Preparation Example 1, SLS-3D printing moldings were manufactured using the PI powder of Comparative Example 2 instead of the PI powder of Example 1, and a photograph thereof is shown in FIG. 7B. In FIG. 7b, the middle part of the molded product was fragmented. This is because the PI powder of Comparative Example 2 was not melted by laser irradiation and thus, it was unsuitable for use as an SLS-3D printing material.

Experimental Example  7: Measurement of tensile strength of molding

The tensile strength of each of the SLS-3D printing moldings of Production Example 1 and Comparative Production Example 1 was measured at a test speed of 50 mm / min after preparing a dumbbell type No. 1 test piece according to the ASTM D638 method. Respectively.

division The tensile strength( Mpa ) Manufacturing example  One 49.5 Comparative Manufacturing Example  One Not measurable

As a material for an SLS-3D printer, the PI powder of the present invention has a high bulk density and a high tap density, has excellent packing properties, is excellent in melt flowability and melt processability, It was confirmed that SLS-3D printing moldings with high strength and high heat resistance can be provided.

Claims (16)

A PI powder for an SLS-3D printer comprising a polyimide powder imidized with a polyamic acid resin obtained by polymerizing a diamine represented by the following formula (1) and an acid anhydride represented by the following formula (2);
[Chemical Formula 1]

In formula (1), A represents a straight chain alkylene group of C1 to C5, a branched alkylene group of C3 to C5,

,

,

or

R ¹ is a hydrogen atom, a C ¹ to C 3 alkyl group, -OH or -COOR ² , R ² is a hydrogen atom or a C 1 to C 3 alkyl group,
(2)

In formula (2), B represents an oxygen atom or

And R ³ is a hydrogen atom, a methyl group, -CH ₂ F, -CHF ₂ or -CF ₃ .
The compound according to claim 1, wherein A in the formula (1)

,

or

, R ¹ is a hydrogen atom or COOR ² , R ² is a hydrogen atom or a C 1 -C ² alkyl group,
B in the formula (2) represents an oxygen atom or

And R ³ is CH ₂ F, -CHF ₂ or -CF ₃ ;
The PI powder for an SLS-3D printer according to claim 1, wherein the polyamic acid resin has a solid content of 18 to 25% by weight.
The PI powder for an SLS-3D printer according to claim 1, wherein the diamine and the acid anhydride are present in a molar ratio of 1: 1 to 1.4.
The PI powder for an SLS-3D printer according to claim 1, wherein the polyimide is an amorphous polyimide having an imidization degree of 50% to 85%.
The PI powder for an SLS-3D printer according to claim 1, wherein the polyimide powder comprises particles having a size of 0.1 mu m to 200 mu m.
The PI powder for an SLS-3D printer according to claim 6, wherein the polyimide powder has a particle size distribution D10 of 10 mu m to 20 mu m, a D50 of 20 mu m to 40 mu m, and a D90 of 40 to 60 mu m .
The SLS-3D printer according to claim 1, wherein the polyimide powder has a melting point (T _m ) of 310 ° C. to 350 ° C. and a thermal decomposition temperature (T _{d, 5 wt%)} of 570 ° C. to 590 ° C. For PI powder.
The PI powder for an SLS-3D printer according to claim 1, wherein the polyimide powder has an apparent density of 0.300 or more and a tap density of 0.400 or more.
A step of polymerizing a diamine represented by the following formula (1) and an acid anhydride represented by the following formula (2) in a solvent to prepare a polyamic acid resin;
A step of aging the polyamic acid resin;
A third step of preparing a polyimide solid by performing an imidation reaction on the aged polyamic acid resin;
Washing the polyimide solid to remove unreacted monomers and impurities;
A fifth step of heat-treating the washed polyimide solid to remove the solvent; And
6. A method of producing a PI powder for an SLS-3D printer, comprising grinding and pulverizing a heat-treated polyimide solid body,
[Chemical Formula 1]

In formula (1), A represents a straight chain alkylene group of C1 to C5, a branched alkylene group of C3 to C5,

,

,

or

R ¹ is a hydrogen atom, a C ¹ to C 3 alkyl group, -OH or -COOR ² , R ² is a hydrogen atom or a C 1 to C 3 alkyl group,
(2)

In formula (2), B represents an oxygen atom or

And R ³ is a hydrogen atom, a methyl group, -CH ₂ F, -CHF ₂ or -CF ₃ .
The method of claim 10, wherein the solvent is at least one selected from the group consisting of N-methylpyrrolidone (NMP), N-ethylpyrrolidone (NEP), dimethylacetamide (DMAc), 3-methoxy- 3-butoxy-N, N-Dimethylpropionamide), characterized in that it comprises 3-butoxy-N, N-dimethylpropionamide or 3-butoxy-N.
The method according to claim 10, wherein the two stages of aging are performed at 130 ° C to 150 ° C for 1 hour to 3 hours.
11. The method according to claim 10, wherein the imidization reaction in three steps is performed at 180 ° C to 210 ° C for 1 hour to 3 hours.
The method according to claim 10, wherein the heat treatment in step 5 is performed at 220 ° C to 250 ° C.
11. The method according to claim 10, wherein the pulverization in the six steps is carried out using ACM (Air Classifying Mill), HSM (High Speed Mill) or TAM (Tubo Air Mill) .
The polyamic acid resin composition according to claim 10, wherein the polyamic acid resin of the first stage has a solid content of 18 to 25%
Wherein the powdered polyimide in step 6 is an amorphous polyimide having an imidization degree of 50% to 85%.

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