JP2022001432A - Polymer powder used in powder bed melt bonding method and method for producing three-dimensional molded object - Google Patents

Abstract

To provide polymer powder which makes a surface of a three-dimensional molded object produced by a power bed melt bonding method smooth by controlling the ratio of apparent density to tapped density within a certain range to show high powder filling property and fluidity, and which has excellent penetrability of a melting aid, etc., and also can increase strength of the obtained molded object by controlling the ratio of the tapped density to actual density within a certain range to have a moderate gap between the powders.SOLUTION: In polymer powder for producing a three-dimensional molded object by a powder bed melt bonding method, the ratio of apparent density to tapped density of the powder is 0.75 or higher and 1.00 or lower, and the ratio of the tapped density to actual density of the powder is 0.50 or higher and 0.70 or lower.SELECTED DRAWING: None

Description

The present invention relates to a polymer powder suitable as a polymer powder used in a powder bed melt-bonding method, and a method for producing a three-dimensional model.

As a technique for manufacturing a three-dimensional modeled object (hereinafter, may be referred to as a modeled object), a material extrusion method, a powder bed melt bonding method, a liquid tank photopolymerization method, a sheet laminating method and the like are known. In these manufacturing methods, a three-dimensional model is formed directly from an intangible material such as a liquid or powder, or an intermediate-shaped material such as a pellet or a filament, based on a data model on a computer. In particular, polymer powder is suitable as an intangible material used in the powder bed melt bonding method.

In the powder bed fusion bonding method, after the powder layer is provided, the position corresponding to the cross section of the object is selectively melted, and these layers are bonded and laminated to form a three-dimensional model. Here, as a method for selectively melting the powder, a selective laser sintering method using a laser, a selective absorption sintering method using a melting aid, a selective suppression sintering method for masking a place where the powder is not melted, or the like. There is.

A technique of using a polymer powder having a large surface area for modeling as a polymer powder suitable for these powder bed melt-bonding methods is disclosed (Patent Document 1).

Japanese Unexamined Patent Publication No. 2018-59093

Since the technique of Patent Document 1 uses only spherical particles, the powder is densely packed and there are no voids, the adsorption and energy absorption of the melt aid and the inhibitor are insufficient, and the melt sintering is not sufficient. rice field.

The technique of Patent Document 2 has a problem that since the surface area is large, holes are likely to be generated in the modeled object, and the strength of the modeled object is lowered.

As a result of studying in the present invention, it is an object to produce a high-density model by excellent fluidity of powder, which is indispensable for application to a powder bed melt-bonding method, and enabling sufficient melt sintering. It has been achieved.

In order to solve the above problems, the polymer powder used in the powder bed melt bonding method of the present invention has the following constitution. That is,
<1> A polymer powder for producing a three-dimensional model by a powder bed melt-bonding method, wherein the ratio of the apparent density to the tap density of the powder is 0.75 or more and 1.00 or less, and the powder is the same. A polymer powder for producing a three-dimensional model in which the ratio of tap density to true density is 0.50 or more and 0.70 or less.
<2> The polymer powder for producing a three-dimensional model according to <1>, which is a polymer powder for producing a three-dimensional model by a selective absorption sintering method or a selective suppression sintering method.
<3> The difference between the infrared absorption rate A1 of the polymer powder and the infrared absorption rate A2 of the powder obtained by adsorbing the melting aid on the polymer powder A2-A1 is 10% or more and 40% or less. The polymer powder for producing the three-dimensional model according to <1> or <2>.
<4> The polymer comprises polyethylene, polypropylene, polyester, polyamide, polyphenylene sulfide, polyetheretherketone, polyetherimide, polyamideimide, polyethersulfone, polytetrafluoroethylene or a mixture thereof. A polymer powder for producing the three-dimensional model according to any one of <1> to <3>.
<5> A method for producing a three-dimensional model by a powder bed melt-bonding method using the polymer powder according to any one of <1> to <4>.
<6> The method for producing a three-dimensional model according to <5> 4, wherein the powder bed melt-bonding method is a selective absorption sintering method or a selective suppression sintering method.

The polymer powder of the present invention exhibits high powder filling property and fluidity by controlling the ratio of the apparent density to the tap density within a certain range, and the surface of the three-dimensional shaped object produced by the powder bed melt bonding method is formed. Become smooth. Further, by controlling the ratio of the tap density to the true density within a certain range, there is an appropriate gap between the powders, the permeability of the melting aid and the like is excellent, and the strength of the obtained modeled product can be increased.

Hereinafter, the present invention will be described in detail.

The ratio of the apparent density to the tap density of the polymer powder of the present invention is 0.75 or more and 1.00 or less. If the ratio of the apparent density to the tap density is less than 0.75, the fluidity of the powder is insufficient, the powder surface is not uniform when the powder is laminated, and the surface of the modeled object becomes rough. The lower limit of the ratio of the apparent density to the tap density of the polymer powder is preferably 0.78 or more, more preferably 0.80 or more, still more preferably 0.82 or more. Since the apparent density never exceeds the tap density in principle, the upper limit is 1.00.

The apparent density of the polymer powder indicates the mass per unit volume when the powder is filled in a container. Here, the apparent density is a measurement of the polymer powder in accordance with Japanese Industrial Standards (JIS standard) JIS K 7365 (1999) "How to determine the apparent density of a material that can be poured from a specified funnel".

The tap density of the polymer powder indicates the mass per unit volume when the powder is gently filled in a container and then densely filled by tapping. Japanese Industrial Standards (JIS standard) JIS K 7370 (2000) The polymer powder was measured according to "How to determine the bulk density".

The ratio of the tap density to the true density of the polymer powder of the present invention is 0.50 or more and 0.70 or less. If the ratio of the tap density to the true density is less than 0.50, the filling of the powder is insufficient, pores are likely to be generated during melt sintering, and the strength of the modeled object is lowered. Further, the voids increase in the state where the polymer powder is filled in the molding chamber, and it becomes difficult to obtain contrast when the melting aid or the like is adsorbed, and the molding accuracy is lowered. Therefore, the lower limit of the ratio of the tap density to the true density of the polymer powder is preferably 0.52 or more, more preferably 0.55 or more, and even more preferably 0.58 or more. Further, when the ratio of the tap density to the true density is larger than 0.70, the powder is in a densely packed state, so that the melting aid and the melting inhibitor do not easily permeate, resulting in insufficient sintering. The upper limit of the ratio of the tap density to the true density of the polymer powder is preferably 0.67 or less, more preferably 0.65 or less, still more preferably 0.63 or less.

The true density of the polymer powder was measured according to Japanese Industrial Standards (JIS standard) JIS Z 8807 (2012) "Method for measuring solid density and specific gravity".

In the present invention, the contrast when the melting aid or the like is adsorbed is the difference between the infrared absorptivity A1 of the polymer powder alone and the infrared absorptivity A2 of the polymer powder adsorbing the melting aid A2-A1. It can be evaluated from. When A2-A1 is large, only the portion where the melting aid is adsorbed can be selectively melted, the molding accuracy is improved, and a shaped product having a smooth surface can be obtained. In the present invention, the value of A2-A1 is preferably 8% or more, more preferably 10% or more, still more preferably 13% or more, and particularly preferably 15% or more. The upper limit of A2-A1 is preferably 40% or less, more preferably 35% or less, still more preferably 30% or less, in that an excessive coating amount of the melting aid inhibits sintering between polymer powders. Particularly preferably, it is 25% or less.

The infrared absorptivity of the polymer powder can be evaluated by infrared spectroscopic measurement using a diffuse reflection method. Specifically, the reflectance (%) of the polymer powder and the transmittance of the polymer powder that transmits light are measured, and then the absorptance is calculated by 100%-(reflectance (%) + transmittance (%)). do. In the present invention, the infrared absorptivity is not particularly limited as long as the polymer powder can be evaluated in the powder state, but the method is not particularly limited. It can be evaluated by installing a reflection measuring device (DRS-8000), filling a cell with a sample obtained by diluting a polymer powder 100 times with potassium bromide, and performing infrared spectroscopy (IR measurement). As a sample for measuring the infrared absorptivity when a melting aid is adsorbed, for example, a polymer powder mixed with 0.5% by weight of carbon black is evaluated by infrared spectroscopy by a diffuse reflection method. Can be done.

The D50 particle size of the polymer powder of the present invention can be preferably in a size that can obtain a desired apparent density and tap density and can be used in a powder bed melt-bonding method, and is preferably in the range of 1 to 100 μm. Is. When the D50 particle size exceeds 100 μm, the tap density / true density becomes large and it becomes difficult for the melting aid and the like to permeate, which causes a decrease in strength, and the particle size becomes larger than the modeling surface and the surface becomes rough. When the D50 particle diameter is 1 μm or less, the apparent density becomes small because it is fine, and it easily adheres to a coater or the like at the time of modeling, and the modeling chamber cannot be raised to the required temperature. The upper limit of the D50 particle size of the polymer powder is more preferably 90 μm or less, further preferably 80 μm or less, and particularly preferably 70 μm or less. The lower limit is more preferably 5 μm or more, further preferably 10 μm or more, and particularly preferably 20 μm or more.

The D50 particle size of the polymer powder is a particle size (D50 particle size) at which the cumulative frequency from the small particle size side of the particle size distribution measured by the laser diffraction type particle size distribution meter is 50%.

The particle shape of the powder of the present invention is not particularly limited as long as a desired apparent density and tap density can be obtained. For example, a substantially spherical powder or a mixture of a spherical powder and a crushed powder can be used. In particular, in the present invention, it is preferable to use a mixture of a spherical powder and a pulverized powder in that the apparent density and the tap density are adjusted to desired ranges.

The lower limit of the amount of the spherical powder added, which can be suitably used in the present invention, is 10 parts by mass or more with respect to 100 parts by mass of the polymer powder in that the smaller the surface area of the particles, the higher the fluidity. preferable. More preferably, it is 20 parts by mass or more, further preferably 30 parts by mass or more, and particularly preferably 40 parts by mass or more. The upper limit is preferably 99 parts by mass or less because if the surface area is too small, the melting aid and the melting inhibitor are difficult to permeate and the sintering becomes insufficient. It is more preferably 97 parts by mass or less, further preferably 95 parts by mass or less, and particularly preferably 90 parts by mass or less.

The sphericity of the polymer powder in the present invention is 70 or more in that the surface area thereof can be reduced, the friction between the particles can be reduced, and as a result, high fluidity is exhibited and the surface of the obtained modeled product becomes smooth. Is preferable. If the sphericity is less than 70, the fluidity deteriorates and the surface of the modeled object becomes rough. The sphericity is more preferably 75 or more, still more preferably 78 or more, and particularly preferably 80 or more. Further, the upper limit is preferably 96 or less, more preferably 94 or less, still more preferably 92 or less, and particularly preferably 92 or less, in that if the surface area is too small, the melting aid and the melting inhibitor do not easily permeate and the sintering becomes insufficient. Is 90 or less.

The sphericity of the powder is determined by observing 30 particles at random from a scanning electron micrograph and following the following formula from the minor axis and the major axis.

In addition, S: sphericity, a: major diameter, b: minor diameter, n: measurement number 30.

The smoothness of the surface and the internal solidity of the polymer powder in the present invention are not particularly limited as long as the desired apparent density and tap density can be obtained. The smoothness of the surface of the powder and the internal solidity can be expressed by the BET specific surface area due to gas adsorption, and the smoother the surface, the smaller the BET specific surface area. ^{The upper limit is preferably 10 m 2} / g or less, more preferably 5 m ² / g or less, still more preferably 3 m ² / g, in that pores are less likely to occur in the obtained three-dimensional model. It is less than or equal to, and particularly preferably 1 m ² / g or less. The lower limit, in that melting aid or melting inhibitors is likely to penetrate, is preferably 0.01 m ² / g or more, more preferably 0.05 m ² / g or more, more preferably 0 .10m and ² / g or more, particularly preferably 0.15 m ² / g or more.

The BET specific surface area is measured according to Japanese Industrial Standards (JIS standard) JIS R 1626 (1996) "Method for measuring specific surface area by gas adsorption BET method".

Further, the solidity of the particles can be evaluated by the following formula showing the ratio of the BET specific surface area to the theoretical surface area calculated from the D50 particle diameter. The closer the above ratio is to 1, the more the adsorption occurs only on the outermost surface of the particle, indicating that the particle has a smooth surface and is solid. 5 or less is preferable, 4 or less is more preferable, 3 or less is further preferable, and 2 or less is most preferable.

The ratio of R: surface area, D: D50 particle size, α: density of polyamide, and A: BET specific surface area are shown.

The polymer constituting the polymer powder of the present invention is a polymer suitable for producing a three-dimensional model by a powder bed melt-bonding method, and is polyethylene, polypropylene, polyester, polyamide, polyphenylene sulfide, polyether ether ketone, or polyether. It preferably contains imide, polyamideimide, polyethersulfone, polytetrafluoroethylene or a mixture thereof. Polyester, polyamide, polyphenylene sulfide, polyether ether ketone, polyetherimide, polyamideimide, polyethersulfone, and polytetrafluoroethylene are more preferable, and melting point and crystallization are preferable in that the obtained three-dimensional model has excellent heat resistance. Polyester, polyamide, polyphenylene sulfide, polyether ether ketone, and polytetrafluoroethylene are more preferable because of their clear temperature difference and excellent formability and reproducibility, and among them, polyester, polyamide, and polyphenylene sulfide are relatively inexpensive. Is particularly preferable.

The polyester in the present invention is obtained by polycondensing with a polybasic acid or a polybasic acid dialkyl ester using a polyhydric alcohol as a main raw material. Here, the main raw material indicates that the constituent unit of the polybasic acid or the polybasic acid dialkyl ester in the polymer and the polyhydric alcohol is 25% by weight or more. The constituent unit of the polybasic acid or the polybasic acid dialkyl ester in the polymer and the polyhydric alcohol is preferably 40% by weight or more, more preferably 50% by weight or more. Here, the polyhydric alcohol is not particularly limited, and for example, propylene glycol such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, dipropylene glycol, butanediol such as 1,4-butanediol, and the like. Alkylene glycols (aliphatic glycols) such as neopentyl glycol and 1,6-hexanediol and their alkylene oxide adducts, bisphenols such as bisphenol A and hydrogenated bisphenol, and phenolic glycols of these alkylene oxide adducts, Examples thereof include alicyclic diols such as monocyclic or polycyclic diols, aromatic diols, triols such as glycerin and trimethylolpropane, and the like. These can be used alone or in combination of two or more.

Examples of the polybasic acid (polycarboxylic acid) include malonic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, itaconic acid, phthalic acid and its modified acid (for example, hexahydrochloride phthalic acid). Saturated or unsaturated (or aromatic) polyvalent basic acids such as acid), isophthalic acid, terephthalic acid, trimellitic acid, trimesic acid, pyromellitic acid, acid anhydrides thereof, lower alkyl esters and the like. These can be used alone or in admixture of two or more.

Among these polyester resins, PBT resin is preferably used. The PBT resin is composed of PBT in an amount of 80% by weight or more, preferably 85% by weight or more, and may be a copolymer or a mixture of resins other than the PBT resin. Further, the PBT in the present invention is a polyester containing a butylene terephthalate component as a main repeating unit. The main repeating unit here means 80 mol% or more, preferably 85 mol% or more of all the repeating units. Other acid components include aromatic dicarboxylic acids such as isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid and sodium sulfoisophthalic acid, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid and decalindicarboxylic acid, oxalic acid and malonic acid. , Succinic acid, sebacic acid, adipic acid, dodecanedioic acid and other aliphatic dicarboxylic acids, and other diol components, specifically, for example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol. , Neopentyl glycol, 1,6-hexanediol, polypropylene glycol, aliphatic diol such as polytetramethylene glycol, alicyclic diol such as 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 2,2- Some aromatic diols such as bis (4'-hydroxyphenyl) propane can also be used. It is preferable that these copolymerization components are 40 mol% or less with respect to terephthalic acid or 1,4-butanediol, respectively.

The polyamide in the present invention is obtained by polycondensing a three-membered ring or more of lactam, a polymerizable aminocarboxylic acid, a dibasic acid and a diamine or a salt thereof, or a mixture thereof. Specific examples of such a polyamide include polycaproamide (polyamide 6), polyundecamide (polyamide 11), polylauroamide (polyamide 12), polyhexamethylene adipamide (polyamide 66), and polydeca. Methylene sebacamide (polyamide 1010), polydodecamethylene dodecamide (polyamide 1212), polyhexamethylene sebacamide (polyamide 610), polyhexamethylene dodecamide (polyamide 612), polydecamethylene adipamide (polyamide 106) , Polydodecamethylene adipamide (polyamide 126), polyhexamethylene terephthalamide (polyamide 6T), polydecamethylene terephthalamide (polyamide 10T), polydodecamethylene terephthalamide (polyamide 12T), polycaproamide / polyhexamethylene azi. Pamide copolymer (polyamide 6/66), polycaproamide / polylauroamide copolymer (6/12), and as amorphous polyamide, isophthalic acid, terephthalic acid, metaxylylene diamine, 1,3 -Bisaminomethylcyclohexane, isophoronediamine, 2,2,4- or 2,4,4-trimethylhexamethylenediamine, 4,4'-diaminodicyclohexylmethane, 3,3'-dimethyl-4,4'-diaminodicyclohexyl Examples thereof include a copolymer having a kind of component selected from methane and 4,4'-diaminodicyclohexylpropane as constituent components. Examples of commercially available products include the "GRILAMID (registered trademark)" TR series manufactured by EMS-GRIVORY and the "TROGAMID (registered trademark)" series manufactured by EVONIC. From the viewpoint of easy control to a true spherical shape, polycaproamide (polyamide 6), polylauroamide (polyamide 12), polyhexamethylene adipamide (polyamide 66), and polydecamethylene sebacamide (polyamide 1010) are preferable. , Polydodecamethylene dodecamide (polyamide 1212), polyhexamethylene sebacamide (polyamide 610), polyhexamethylene dodecamide (polyamide 612), EMS-GRIVORY "GRILAMID (registered trademark)" TR series, EVONIK The "TROGAMID (registered trademark)" series and the like are mentioned, and polycaproamide (polyamide 6), polylauroamide (polyamide 12), and polyhexamethylene azimuth are given because of their heat resistance during modeling and thermal properties suitable for modeling. Pamide (polyamide 66) is particularly preferred.

These may be copolymerized as long as the effects of the present invention are not impaired. As the copolymerizable component, an elastomer component such as polyolefin or polyalkylene glycol that imparts flexibility, a rigid aromatic component that improves heat resistance and strength, and the like can be appropriately selected. Also, as will be described later, monocarboxylic acids such as acetic acid, hexaneic acid, lauric acid and benzoic acid, and monoamines such as hexylamine, octylamine and aniline, whose terminal groups are adjusted to reuse the polymer powder by the powder bed melt bonding method. Is mentioned as a copolymerization component.

The polyphenylene sulfide in the present invention is a homopolymer or a copolymer having the repeating unit represented by the formula (1) as a main constituent unit.

Ar of the general formula (1) is an aromatic group, and examples of Ar include formulas (2) to (4) (R ¹ and R ² are groups selected from hydrogen, an alkyl group, an alkoxyl group, and a halogen group. Is).

As long as this repetition is the main constituent unit, a branched bond or a crosslinked bond represented by the formula (5) or the like, or a crosslinked bond, or

It can also contain a copolymerization component represented by the formulas (6) to (14) (where R ¹ and R ² are substituents selected from hydrogen, an alkyl group, an alkoxyl group and a halogen group).

A particularly preferably used PPS is a copolymer of a p-phenylene sulfide unit represented by the formula (15) and an m-phenylene sulfide unit or an o-phenylene sulfide unit as the main constituent unit of the polymer.

The melting point of the polymer powder in the present invention is preferably 150 ° C. or higher, more preferably 170 ° C. or higher, still more preferably 190 ° C. or higher, and particularly preferably 210 ° C. or higher in terms of excellent heat resistance of the modeled product.

Further, the difference between the crystallization temperature and the melting point of the polymer powder is preferably 20 ° C. or higher. If the difference between the crystallization temperature and the melting point is small, the temperature conditions in the production of the three-dimensional model become strict, and the model tends to warp, which is not preferable. The difference between the crystallization temperature and the melting point of the polymer powder is more preferably 25 ° C. or higher, further preferably 30 ° C. or higher, particularly preferably 35 ° C. or higher, and most preferably 40 ° C. or higher.

In the present invention, the melting point and crystallization temperature of the polymer powder are set from 30 ° C. to higher than the melting point of the polymer by using a differential scanning calorimeter (DSC, for example, DSCQ20 manufactured by TA Instruments). For melting when the temperature range up to a temperature exceeding 30 ° C. is raised once at a heating rate of 20 ° C./min and then held for 1 minute, then lowered to 30 ° C. at 20 ° C./min and held for 1 minute. It refers to the peak of the heat absorption peak that accompanies and the exothermic peak that accompanies crystallization.

As a method for producing a polymer powder according to the present invention, a known method can be used, and a method of dissolving a polymer in a solvent and precipitating it by cooling or concentration, a method of scattering it into a mist and drying it, There is a method of adding a poor solvent to precipitate, and a method of mechanically grinding the polymer. Specific examples of the crushing treatment method include a jet mill, a bead mill, a hammer mill, a ball mill, a sand mill, a turbo mill, and a freezing crushing method.

The spherical powder, which is particularly preferably used in the present invention, is specifically obtained by dissolving a polymer in an organic solvent, adding it to water to form an O / W emulsion, and then drying and removing the organic solvent under reduced pressure to remove fine particles. A method for producing fine particles, which is described in International Publication No. 2012/043509, is prepared by dissolving a polymer and a second polymer in an organic solvent to form an emulsion, and then contacting the mixture with water, which is a poor solvent for the polymer, to produce fine particles. There is a way to do it. Further, in the production of the polymer powder of the present invention, the polyamide monomer (B) described in International Publication WO2018 / 207728, which was previously disclosed by the present inventors, is used in the presence of the polymer (A). , A method of polymerizing at a temperature higher than the crystallization temperature of the polyamide obtained by polymerizing the monomer (B), washing and drying the powder can also be used.

The effect of the polymer powder of the present invention is that the polymer powder exhibits high fluidity. The index can be adopted by any known measuring method. A specific example is the angle of repose, which is 40 degrees or less. It is preferably 37 degrees or less, more preferably 33 degrees or less, and particularly preferably 30 degrees or less. The lower limit is usually 20 degrees or more.

The polymer powder of the present invention may be added with other formulations as long as the present invention is not impaired. Examples of the compounding agent include an antioxidant and a heat-resistant stabilizer in order to suppress thermal deterioration due to heating during molding by the powder bed melt-bonding method. Examples of antioxidants and heat-stabilizing agents include hindered phenols, hydroquinones, phosphites and their substitutes, phosphite, hypophosphite and the like. Others include pigments and dyes for coloring, plasticizers for adjusting viscosity, flow aids for fluidity modification, antistatic agents for imparting functions, flame retardants and carbon black, silica, titanium dioxide, glass fiber and glass. Examples include fillers such as beads and carbon fibers. Known substances can be used as these, and they may be present inside or outside the polymer powder.

Such a formulation preferably includes a filler in that the strength of the modeled product can be further improved as described later. The preferred filler used in the present invention refers to a substance that suppresses aggregation of the polymer powder due to the adhesive force between the polymer powders. By including such a filler, the fluidity of the polymer powder can be improved, and the filling property of the polymer powder becomes high when it is formed into a model, so that defects that cause mechanical properties are reduced, which is preferable. Further, for this reason, there is a tendency that the strength of the obtained modeled object can be further improved.

Such fillers include, for example, fused silica, crystalline silica, silica (silicon dioxide) such as amorphous silica, alumina (alumina oxide), alumina colloid (alumina sol), alumina such as alumina white, light calcium carbonate, heavy calcium carbonate, and fine powder. Calcium carbonate, calcium carbonate such as special calcium carbonate-based filler, calcined clay such as Kasumi stone flash stone fine powder, montmorillonite, bentonite, clay (aluminum silicate powder) such as silane modified clay, talc, diatomaceous soil, Silica-containing compounds such as silica sand, crushed products of natural minerals such as light stone powder, light stone balloon, slate powder, mica powder, minerals such as barium sulfate, lithopon, calcium sulfate, molybdenum disulfide, graphite (graphite), and glass fiber. , Glass beads, glass flakes, glass fillers such as foamed glass beads, fly ash balls, volcanic glass hollows, synthetic inorganic hollows, potassium monocrystal titanate, carbon fibers, carbon nanotubes, carbon hollow spheres, fullerene, smokeless charcoal powder , Artificial ice crystal (cryolite), titanium oxide, magnesium oxide, basic magnesium carbonate, dolomite, potassium titanate, calcium sulfite, mica, asbestos, calcium silicate, molybdenum sulfide, boron fiber, silicon carbide fiber, etc. Be done. More preferably, silica, alumina, calcium carbonate powder, glass-based filler, and titanium oxide are used. Particularly preferably, silica and alumina are mentioned because they are hard and can contribute to strength improvement and fluidity improvement.

Commercially available products of such silica include fumed silica "AEROSIL" (registered trademark) series manufactured by Nippon Aerosil Co., Ltd., dry silica "Leorosil" (registered trademark) series manufactured by Tokuyama Corporation, and Zolgel silica powder X manufactured by Shin-Etsu Chemical Co., Ltd. The -24 series and the like can be mentioned.

The average particle size of the filler is preferably 20 nm or more and 1 μm or less. The upper limit of the average particle size of the filler is preferably 1 μm, more preferably 500 nm, more preferably 400 nm, particularly preferably 300 nm, and remarkably preferably 250 nm. The lower limit is preferably 20 nm, more preferably 30 nm, more preferably 50 nm, and particularly preferably 100 nm. When the average particle size of the filler is within the above range, the fluidity of the polymer powder can be improved and the filler can be uniformly dispersed in the polymer powder.

The blending amount of the filler is preferably more than 0.01 part by mass and less than 5 parts by mass with respect to 100 parts by mass of the polymer powder. The upper limit of the blending amount is preferably less than 3 parts by mass, more preferably less than 1 part by mass, further preferably less than 0.5 parts by mass, particularly preferably less than 0.3 parts by mass, and remarkably preferably less than 0.1 parts by mass. .. The lower limit of the blending amount is preferably more than 0.02 parts by mass, more preferably more than 0.03 parts by mass, and even more preferably more than 0.04 parts by mass. When the blending amount of the filler exceeds 0.01 parts by mass, the fluidity of the polymer powder is further improved and the filling property at the time of modeling is increased, so that voids that become defects in the mechanical properties are less likely to occur and can be obtained. The model tends to develop high strength. Further, when the blending amount of the filler is less than 5 parts by mass, sintering is not hindered by covering the surface of the polymer powder with the filler, and a high-strength molded product tends to be obtained.

Further, in the powder bed melt-bonding method, a modeled product is produced from a part of the polymer powder used, and a large amount of polymer powder remains. Reusing the polymer powder is important in terms of cost. For that purpose, it is important not to change the properties of the polymer powder during the heating and modeling process. As such a method, for example, a stabilizer such as an antioxidant is blended inside the particles to suppress thermal deterioration, or a method of modifying the terminal group of the polymer to suppress a change in molecular weight during modeling. And so on. By appropriately using such adjustments, it tends to be possible to achieve both formability and reuse.

The polymer powder of the present invention is a material useful for producing a three-dimensional model by a powder bed melt-bonding method.

The manufacturing of the modeled product by the powder bed melt-bonding method is a thin layer forming process in which the polymer powder is developed into a thin layer, and the thin layer is selectively melted into a shape corresponding to the cross-sectional shape of the object to be modeled. By repeating the cross-section forming step in sequence, a three-dimensional model is formed. In the cross-section forming step, a selective laser sintering method of irradiating a laser beam to bond the polymer powder, a selective absorption sintering method of printing an energy absorption accelerator and binding the polymer powder using electromagnetic radiation, There is also a selective suppression sintering method in which an energy absorption inhibitor is printed and masked in a place where it is not melted, and the polymer powder is bonded using electromagnetic radiation. Among these, the selective absorption sintering method and the selective suppression sintering method are preferable because the molding speed is high and the productivity is excellent.

The electromagnetic radiation used in the selective absorption sintering method and the selective suppression sintering method may be any as long as it does not impair the quality of the polymer powder or the modeled object, but it is relatively inexpensive. Infrared rays are preferable because energy suitable for modeling can be obtained. Also, electromagnetic radiation may or may not be coherent.

In the present invention, the energy absorption accelerator used in the selective absorption sintering method is a substance that absorbs electromagnetic radiation. Examples of such substances include carbon black, carbon fiber, copper hydroxyphosphate, near-infrared absorbent dye, near-infrared absorbent pigment, metal nanoparticles, polythiophene, poly (p-phenylene sulfide), polyaniline, poly (pyrrole), and the like. Polyacetylene, poly (p-phenylene vinylene), polyparaphenylene, poly (styrene sulfonate), poly (3,4-ethylenedioxythiophene) -poly (styrene phosphonate) p-diethylaminobenzaldehyde diphenylhydrazone, anti-9-isopropylcarbazole , Or a conjugated polymer composed of a combination of these can be exemplified, and these may be used alone or in combination of two or more.

In the present invention, the energy absorption inhibitor used in the selective suppression sintering method is a substance that does not easily absorb electromagnetic radiation. Examples of such substances include substances that reflect particle electromagnetic radiation such as titanium, heat insulating powders such as mica powder and ceramic powder, and water, which may be used alone or in combination of two or more. ..

These selective absorbents or selective inhibitors may be used alone or in combination.

Selective Absorbent or Selective Inhibitor In the step of printing into a shape corresponding to the cross-sectional shape of the object to be modeled, a method such as inkjet can be used. In this case, the selective absorbent or selective inhibitor may be used as it is, or may be dispersed or dissolved in a solvent.

Hereinafter, the present invention will be described based on examples, but the present invention is not limited thereto.

(1) Apparent density and tap density of the polymer powder The apparent density of the polymer powder is determined ^{by dropping 50 g of the polymer powder from the funnel into a 100 cm 3} graduated cylinder in accordance with the Japanese Industrial Standard (JIS standard) JIS Z 7365 (1999). , The volume was read and the weight of the polymer powder was divided by the volume. The tap density of the polymer powder is according to Japanese Industrial Standards (JIS standard) JIS Z 7370 (2000). 50 g of the polymer powder is ^{dropped from the funnel into a 100 cm 3} measuring cylinder, and the volume after tapping is read to read the polymer. The value was obtained by dividing the weight of the powder by the volume.

(2) True density of polymer powder According to Japanese Industrial Standards (JIS standard) JIS Z 8807 (2012), the true density of polymer powder is about 10 g of polymer powder in a Gerusac type specific gravity bottle (pycnometer), which is higher than that of polymer powder. A small solvent was introduced, and the weights of only the specific density bottle, the specific density bottle powder, the specific density bottle + powder + solvent, and the specific density bottle + solvent were measured and calculated according to the following formula.

In addition, d: powder true density, d0: solvent density, Wa: specific gravity bottle weight, Wb: specific gravity bottle + powder weight, Wc: specific gravity bottle + powder + solvent weight, Wd: specific gravity bottle + solvent weight.

(3) D50 particle size of polymer powder Measure a dispersion in which about 100 mg of polymer powder is dispersed in about 5 mL of deionized water in advance on a laser diffraction type particle size distribution meter measuring device (Microtrac MT3300EXII) manufactured by Nikkiso Co., Ltd. After adding until the concentration becomes possible and ultrasonically dispersing at 30 W for 60 seconds in the measuring device, the cumulative frequency from the small particle size side of the particle size distribution measured in 10 seconds is 50%. The particle size was defined as the D50 particle size. The refractive index at the time of measurement was 1.52, and the refractive index of the medium (deionized water) was 1.333.

(4) Gravity of polymer powder The sphericity of polymer powder is determined by observing 30 particles at random from a scanning electron microscope (scanning electron microscope JSM-6301NF manufactured by JEOL Ltd.). It was calculated from the diameter and the major axis according to the following formula.

In addition, S: sphericity, a: major diameter, b: minor diameter, n: measurement number 30.

(5) BET specific surface area of polymer powder According to Japanese Industrial Standards (JIS standard) JISR1626 (1996), about 0.2 g of polymer powder is placed in a glass cell using BELSORP-max manufactured by Nippon Bell, and the temperature is 80 ° C. for about 5 hours. After degassing under reduced pressure, the krypton gas adsorption isotherm at the liquid nitrogen temperature was measured and calculated by the BET method.

(6) Crystallization temperature and melting point of polymer powder Using a differential scanning calorimeter (DSCQ20) manufactured by TA Instruments, the temperature is 20 ° C from 30 ° C to 30 ° C higher than the endothermic peak indicating the melting point of the polymer under a nitrogen atmosphere. The endothermic peak associated with melting and the peak of the exothermic peak associated with crystallization when the temperature is raised once at a heating rate of / min and then held for 1 minute, then lowered to 30 ° C at 20 ° C / min and held for 1 minute. Point to. The polymer powder required for the measurement is about 8 mg.

(7) Measurement of the angle of repose of the polymer powder Using the Seishin Enterprise Multitester MT-1, 100 g of the polymer powder was dropped from the funnel onto a flat plate and measured from the angle between the slope of the mountain and the plate. If the angle of repose is 40 degrees or less, it is good, and if it exceeds 40 degrees, it is evaluated as bad.

(8) Measurement of infrared absorptivity of polymer powder A diffuse reflection measuring device (DRS-8000) was installed in a Fourier transform infrared spectrophotometer (IRPrestig-21) manufactured by Shimadzu Corporation, and the polymer powder was measured with potassium bromide. A 100-fold diluted sample was filled in the cell and IR measurement was performed to determine the absorption rate% at a wavelength of 2750 nm. The result of measuring the polymer powder is A1, the result of measuring the powder obtained by adding 0.5% by weight of carbon black as an energy absorber to the polymer powder is A2, and A2-A1 is good at 10% or more and bad at less than 10%. I evaluated it.

(9) Surface roughness of the modeled object Using an optical microscope (VHX-5000) manufactured by KEYENCE CORPORATION and a VH-ZST (ZS-20) objective lens, the surface of the modeled object was observed at a magnification of 200 times. After three-dimensional imaging of the unevenness of the surface of the modeled object in the automatic composition mode using the software (system version 1.04) attached to the device, the height profile of the cross section is acquired over a length of 1 mm or more, and the surface is roughened by arithmetic averaging. The degree Ra was calculated. The smaller the surface roughness Ra, the better the smoothness of the surface.

(10) Bending strength of the model The bending strength of the three-dimensional model produced using the polymer powder is as follows. It was prepared and measured using a Tensilon universal tester (TENSIRON TRG-1250, manufactured by A & D Co., Ltd.). According to JIS K7171 (2008), a three-point bending test was measured under the conditions of a distance between fulcrums of 64 mm and a test speed of 2 mm / min, and the bending strength was measured. The measurement temperature was room temperature (23 ° C.), the number of measurements was n = 5, and the average value was calculated.

[Manufacturing Example 1] (Manufacturing of true sphere polyamide powder)
400 g of ε-caprolactam as a polyamide monomer, 600 g of polyethylene glycol, and 1000 g of water were added to an autoclave equipped with a 3 L helical ribbon-type stirring blade to form a uniform solution, which was then sealed and replaced with nitrogen. Then, the stirring speed was set to 40 rpm and the temperature was raised to 210 ° C. At this time, ^{after the pressure of the system reached 10 kg / cm 2} , the pressure was controlled while slightly releasing the water vapor so as to maintain the pressure at 10 kg / cm ^2. After the temperature reached 210 ° C., the pressure was released at a rate of ^{0.2 kg / cm 2 · min.} Then, the temperature was maintained for 1 hour while flowing nitrogen to complete the polymerization, and the slurry was discharged into a 2000 g water bath to obtain a slurry. After dissolving the lysate, filtration was performed, 2000 g of water was added to the filter medium, and the mixture was washed at 80 ° C. Then, the slurry liquid from which the agglomerates had been passed through a 200 μm sieve was filtered again, and the isolated filter was dried at 80 ° C. for 12 hours to prepare 280 g of polyamide 6 powder. The melting point of the obtained powder was 215 ° C., which was the same as that of polyamide 6, and the crystallization temperature was 173 ° C. The D50 particle size was 53 μm and the sphericity was 98.

[Manufacturing Example 2] (Manufacturing of true sphere PPS powder)
1L autoclave, PPS (melting point 284 ° C) 17.5 g, polyvinyl alcohol (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., G-type "Gosenol (registered trademark)" GM-14, weight average molecular weight 29,000) 52.5 g, N 280 g of -methyl-2-pyrrolidone was added, and the mixture was heated to 250 ° C. for about 1 hour while stirring at 400 rpm of the paddle blade, and stirred for 1 hour while being held at 250 ° C. Subsequently, the temperature of the system was set to 210 ° C., and while stirring at 400 rpm, 350 g of ion-exchanged water as a poor solvent was added dropwise at a speed of 2.92 g / min via a liquid feed pump. The obtained suspension was filtered, washed with 350 g of ion-exchanged water, filtered off, and vacuum dried at 80 ° C. to obtain a white powder of PPS fine particles. The melting point of the obtained powder was 284 ° C., which was the same as that of the raw material PPS, and the crystallization temperature was 215 ° C. The D50 particle size was 34 μm and the sphericity was 94.

[Manufacturing Example 3] (Manufacturing of crushed polyamide powder)
Polyamide "Amilan (registered trademark)" CM1007 manufactured by Toray Industries, Inc. was pulverized with a jet mill (100AFG manufactured by Hosokawa Micron) for 120 minutes to obtain polyamide 6 powder having a D50 particle diameter of 50 μm.

[Example 1]
The true sphere polyamide 6 powder of Production Example 1 and the crushed polyamide 6 powder of Production Example 3 are mixed so that the amount of the true sphere polyamide 6 powder is 50 parts by mass with respect to 100 parts by mass of the polymer powder, and the average particle size is 170 nm as a filler. Trimethylsilylated amorphous silica (X-24-9500 manufactured by Shin-Etsu Chemical Industry Co., Ltd.) was added in an amount of 0.1 part by mass. The obtained polymer powder had a D50 particle size of 52 μm and a melting point of 218 ° C. The apparent density 0.58 g / cm ^3, a tap density of 0.68 g / cm ^3, the true density of 1.11 g ^/ cm 3, BET specific surface area of 0.7 m ² / g of the polymer powder, angle of repose 32 degrees, The absorption rate% at a wavelength of 2750 nm was 3% for A1 and 18% for A2.

Using 5 kg of this polymer powder, a three-dimensional model was manufactured using a powder bed fusion coupling device (HP Jet Fusion 3D 4200) manufactured by Hewlett-Packard Company. The temperature was set so that the component floor temperature was -15 ° C from the melting point and the supply tank temperature was -5 ° C. The surface roughness Ra of the obtained model was 10 μm, the bending strength was 83 MPa, and the appearance was good with no voids. The characteristics are shown in Table 1.

[Example 2]
A polymer powder was prepared in the same manner as in Example 1 except that the true sphere polyamide 6 powder was mixed so as to be 80 parts by mass with respect to 100 parts by mass of the polymer powder. Table 1 shows the characteristics of the obtained polymer powder and the model.

[Example 3]
A polymer powder was prepared in the same manner as in Example 1 except that the true sphere polyamide 6 powder was mixed so as to be 100 parts by mass with respect to 100 parts by mass of the polymer powder. Table 1 shows the characteristics of the obtained polymer powder and the model.

[Example 4]
A polymer powder was prepared in the same manner as in Example 2 except that the stirring speed in Production Example 1 was 32 rpm, the D50 particle diameter of the spherical polyamide 6 powder was 74 μm, and the sphericity was 97. Table 1 shows the characteristics of the obtained polymer powder and the model.

[Example 5]
A polymer powder was prepared in the same manner as in Example 3 except that the stirring speed in Production Example 1 was 80 rpm, the D50 particle diameter of the spherical polyamide 6 powder was 21 μm, and the sphericity was 96. Table 1 shows the characteristics of the obtained polymer powder and the model.

[Example 6]
D50 of the obtained true sphere polyamide 66 powder was obtained by changing ε-caprolactam in Production Example 1 to 223 g of adipic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) and 354 g of a 50% hexamethylenediamine aqueous solution (manufactured by Tokyo Chemical Industry Co., Ltd.). A true spherical polyamide powder was produced in the same manner as in Production Example 1 except that the particle size was 45 μm and the sphericity was 96. Further, the polyamide "Amilan (registered trademark)" CM1007 in Production Example 3 was changed to CM3006 to obtain a pulverized polyamide 66 powder having a D50 particle diameter of 50 μm.

A polymer powder was obtained in the same manner as in Example 2 except that the spherical polyamide 6 powder in Example 2 was the spherical polyamide 66 powder and the crushed polyamide 6 powder was the crushed polyamide 66 powder. The properties of the polymer powder and the model are shown in Table 1.

[Example 7]
The ε-caprolactam in Production Example 1 was changed to aminododecanoic acid, and a spherical polyamide powder was produced in the same manner as in Production Example 1 except that the obtained spherical polyamide 12 powder had a D50 particle diameter of 50 μm and a sphericity of 98. .. Further, the polyamide "Amilan (registered trademark)" CM1007 in Production Example 3 was changed to "Lilsan (registered trademark)" AESNTL manufactured by Arkema Co., Ltd. to obtain crushed polyamide 12 powder having a D50 particle diameter of 50 μm.

A polymer powder was obtained in the same manner as in Example 2 except that the spherical polyamide 6 powder in Example 2 was the spherical polyamide 12 powder and the crushed polyamide 6 powder was the crushed polyamide 12 powder. The properties of the polymer powder and the model are shown in Table 1.

[Example 8]
The polyamide "Amilan (registered trademark)" CM1007 in Production Example 3 was changed to PPS "Trelina (registered trademark)" A900 manufactured by Toray Industries, Inc. to obtain a pulverized PPS powder having a D50 particle diameter of 70 μm.

A polymer powder was obtained in the same manner as in Example 2 except that the true sphere polyamide 6 powder in Example 2 was the true sphere PPS powder of Production Example 2 and the crushed polyamide 6 powder was the above crushed PPS powder. The properties of the polymer powder and the model are shown in Table 1.

[Comparative Example 1]
A polymer powder was prepared in the same manner as in Example 1 except that the true sphere polyamide 6 powder was not mixed with 100 parts by mass of the polymer powder. At the time of molding the obtained polymer powder, the fluidity was poor and the molding surface was rough. The properties of the polymer powder and the model are shown in Table 1.

[Comparative Example 2]
The pulverization in Production Example 3 was carried out for 60 minutes, and a polymer powder was prepared in the same manner as in Comparative Example 1 except that the pulverized polyamide 6 powder having a D50 particle diameter of 150 μm and a sphericity of 70 was used. At the time of molding the obtained polymer powder, coarse particles were present on the molding surface, and the permeability of the melting aid was poor and sintering was insufficient. The properties of the polymer powder and the model are shown in Table 1.

[Comparative Example 3]
A polymer powder was prepared in the same manner as in Example 2 except that the stirring speed in Production Example 1 was 90 rpm, the D50 particle diameter of the spherical polyamide 6 powder was 15 μm, and the sphericity was 97. At the time of molding the obtained polymer powder, it was not possible to selectively melt-sinter only the portion where the melting aid was adsorbed, and the surface of the molded product became rough. The characteristics are shown in Table 1.

The polymer powder of the present invention exhibits high powder filling property and fluidity by controlling the apparent density and tap density within a certain range, and the surface of the three-dimensional model produced by the powder bed fusion bonding method is smooth. Become. In addition, by controlling the ratio of tap density to true density within a certain range, it is possible to have an appropriate gap between the powders, to have excellent permeability of the melting aid, etc., and to increase the density of the obtained modeled product. ..

Claims (6)

It is a polymer powder for producing a three-dimensional model by a powder bed melt-bonding method, and the ratio of the apparent density to the tap density of the powder is 0.75 or more and 1.00 or less, and the tap density of the powder is used. A polymer powder for producing a three-dimensional model having a true density ratio of 0.50 or more and 0.70 or less. The polymer powder for producing a three-dimensional model according to claim 1, which is a polymer powder for producing a three-dimensional model by a selective absorption sintering method or a selective suppression sintering method. The claim is characterized in that the difference A2-A1 between the infrared absorption rate A1 of the polymer powder and the infrared absorption rate A2 of the powder obtained by adsorbing the melting aid on the polymer powder is 10% or more and 40% or less. The polymer powder for producing the three-dimensional model according to Item 1 or 2. 1. The polymer comprises polyethylene, polypropylene, polyester, polyamide, polyphenylene sulfide, polyetheretherketone, polyetherimide, polyamideimide, polyethersulfone, polytetrafluoroethylene or a mixture thereof. A polymer powder for producing the three-dimensional model according to any one of 3 to 3. A method for producing a three-dimensional model by a powder bed melt-bonding method using the polymer powder according to any one of claims 1 to 4. The method for producing a three-dimensional model according to claim 5, wherein the powder bed melt-bonding method is a selective absorption sintering method or a selective suppression sintering method.