The present invention relates to additive manufacturing powder and a method of manufacturing the additive manufacturing powder.
What Is Particle Size Distribution Weighting: How to Get Fooled about What. = At each y-value of the differential volume-weighted distribution. The size distribution function n n (r) is dened such that n n (r)dr is the total concentration (number per unit volume of air, 2 1 INTRODUCTION or # m 3) of particles with sizes in the domain r;r +dr.
A group of technologies to manufacture three-dimensional objects using solid form data created by three dimensional computer aided design system (3D CAD), etc. is referred to as rapid prototyping technologies. By using molding technique for heat-resisting powder of these technologies, molds or cores can be manufactured without using a model or pattern so that casting production processes becomes extremely short. The rapid prototyping technologies are also referred to as additive manufacturing methods, by which a 3D object is produced by laminating cross sections thereof. In addition, the rapid prototyping technologies includes various layer manufacturing methods (powder fixing methods) using powder as a material.
Conventionally, artificial bones are made of metal materials such as stainless and titanium alloy and abrasion resisting plastic and used for bone replacement operation. These artificial bones substitute malfunctioning joints to fulfill joint function. However, metal materials and wear resistant plastic deteriorate with age due to abrasion, corrosion, swelling, etc. so that they are not suitable for use for a long period of time. Ceramics based on calcium phosphate are now used instead of these materials. Currently, such ceramics are used to provide a scaffold to form bones or promote formation of new bones while being absorbed in bones with time to be substituted with the bones in the future.
As bone prosthetic materials to provide a scaffold for bone formation, for example, materials such as hydroxyapatite having excellent affinity with bone tissue and directly bondable with bone tissue without inclusion are used in many cases. By embedding the bone prosthetic material into the bone defect portion, bone repair is conducted quickly using the bone prosthetic material as a scaffold.
However, bone replacement does not occur by simple hydroxyapatite, hyroxyapatite remaining in a biological body may cause a problem. On the other hand, when the bone prosthetic material with which substitutes bones is embedded into bone tissue, osteogenetic function of the bone tissue is promoted, so that the bone is repaired more easily and more quickly.
As the bone prosthetic material with which bones are substituted, a specific example thereof is tricalcium phosphate (TCP). The degree of tricalcium phosphate absorbed in bones depends on the form of tricalcium phosphate compact. That is, porous tricalcium phosphate has large specific surface area in terms of form and are easily absorbed in bone tissue and are vulnerable to attack of phagocytic cells. To the contrary, dense tricalcium phosphate is extremely slowly absorbed and not easily attacked by phagocytic cells. By combining porous portions and dense portions utilizing such form differences, expression of desired biological compatibility is expected. However, such a combined material is not strong enough to be applied to bones such as thighbone receiving heavy burden. Moreover, it takes longer hours to mold and process the material into a desired form and in particular in the case of a structure having an inside structure, fine processing is impossible by cutting (slicing).
These powder additive manufacturing methods are advantageous in terms of fine processing but requires some devisal to shape a material such as ceramics or carbon fiber which has an extremely high melting point and is not melted by typical laser beams
The present invention provides an improved additive manufacturing powder contains a core-shell type particle containing a core particle comprising a first binder resin and a filler and a shell present on the surface of the core particle. The shell contains a second binder resin. The powder has a particle size distribution Dv/Dn of 1.5 or less and an average circularity in the range of from 0.800 to 0.980, the average circularity being represented by the following relation: Average circularity = a perimeter of a circle having same area as a projected image of a particle / the perimeter of the projected image of the particle × 100.
Moreover,
- Preferably, A/B < 0.8
- More preferably to improve granularity, A/B < 0.7
- Furthermore preferably, A/B < 0.6.
- ▪ X ray tube: Cu
- ▪ Voltage: 40 kV
- ▪ Current: 40 mA
- ▪ Start angle: 3 degree
- ▪ End angle: 80 degree
- ▪ Scanning speed: 0.5 degree/min
- Adduct of bisphenol A with 2 mole of ethylene oxide: 67 parts
- Adduct of bisphenol A with 3 mole of propylene oxide: 84 parts
- Terephthalic acid: 274 parts
- Dibutyltin oxide: 2 parts
- Device: GPC-8020 (manufactured by TOSOH CORPORATION)
- Column: TSK G2000 HXL and G4000 HXL (manufactured by TOSOH
- Temperature: 40 °C
- Solvent: Chloroform
- Flow speed: 1.0 mL/minute
- Sample container: Aluminum sample pan (with a lid)
- Sample amount: 5 mg
- Reference: Aluminum sample pan (alumina 10 mg)
- Atmosphere: nitrogen (flow amount: 50 ml/min)
- Temperature Conditions
- Water: 683 parts
- Sodium salt of sulfuric acid ester of an adduct of methacrylic acid with ethyleneoxide (EREMINOR RS-30, manufactured by Sanyo Chemical Industries, Ltd.): 16 parts
- Styrene: 83 parts
- Methacrylic acid: 83 parts
- Butyl acrylate: 110 parts
- Ammonium persulfate: 1 part.
Moreover,
In addition,
'A method for manufacturing artificial bone' or 'An artificial bone forming method' is also referred to as inkjet type powder additive manufacturing.
The present invention is to provide additive manufacturing powder that can fabricate a laminate object having a complex solid free form with high level of mechanical strength and good dimension accuracy.
The additive manufacturing powder and the method of manufacturing an additive manufacturing object using the additive manufacturing powder are described in detail below. Incidentally, it is to be noted that the following embodiments are not limiting the present disclosure and any deletion, addition, modification, change, etc. can be made within a scope in which man in the art can conceive including other embodiments, and any of which is included within the scope of the present disclosure as long as the effect and feature of the present disclosure are demonstrated.
An embodiment of the additive manufacturing powder of the present disclosure contains a core-shell type particle containing a core particle containing a first binder resin and a filler and a shell present on the surface of the core particle. The shell contains a second binder resin. The powder has a particle size distribution Dv/Dn of 1.5 or less and an average circularity in the range of from 0.800 to 0.980. The average circularity is represented by the following relation.
The additive manufacturing powder of the present disclosure contains a core-shell type particle containing a core particle containing a first binder resin and a filler and a shell present on the surface of the core particle. The shell contains a second binder resin. The powder has a particle size distribution Dv/Dn of 1.5 or less and an average circularity in the range of from 0.800 to 0.980. The average circularity is represented by the following relation. Average circularity = a perimeter of a circle having same area as that of a projected image of a particle / the perimeter of the projected of the particle × 100.
An embodiment of the additive manufacturing powder of the present disclosure is described below. A solution or liquid dispersion is prepared in which the core particle containing the first binder resin (e.g., polyester resin) and the filler (e.g., calcium phosphate based material, carbon based material) are dissolved or dispersed in an organic solvent. The solution or liquid dispersion is added to, for example, to an aqueous medium containing the second binder resin (e.g., styrene-acrylic resin) having an average particle diameter in the range of from 20 nm to 60 nm to prepare an emulsion or liquid dispersion. Thereafter, by removing the organic solvent from the emulsion or the liquid dispersion to form particles (core-shell type particle) for additive manufacturing, the additive manufacturing particles are dispersed by deionized water to prepare a liquid dispersion. Moreover, the liquid dispersion is heated while being stirred to obtain additive manufacturing powder.
The thus-obtained additive manufacturing powder contains a core-shell type particle including the shell containing the second binder resin present on the surface of the core particle containing the first binder resin and the filler. The core particle can be covered with the shell or the shell can adhere to the core particle.
In the core-shell type particle, the first binder resin is contained in the core particle and the second binder resin is contained in the shell. In the present disclosure, it is preferable that the second binder resin is incompatible with the first resin and swelling to ethyl acetate.
In addition, as described in detail below, the first binder resin is preferably a polyester resin and the second binder resin is a styrene-acrylic resin.
As the first binder resin, it is preferable for the first binder resin to have a wavelength that absorbs a laser beam used during additive manufacturing and emulsification property. The first binder resin can be selected to a particular application. Of these, a polyester resin is preferable. As the first binder resin, multiple resins can be combined. Moreover, it is also preferable to have near 1,000 cm-1 as the absorption wavelength in the case of, for example, CO2 laser.
As the polyester-based resin for use in the present disclosure, it is possible to use a resin obtained by polyesterification of at least one polyol represented by the following chemical formula 1 and at least one polycarboxylic acid represented by the following chemical formula 2.
A-(OH)m Chemical formula 1
A-(OH)m Chemical formula 1
In the Chemical formula 1, a symbpl 'A' represents an alkyl group having 1 to 20 carbon atoms, an alkylene group, a substituted or non-substituted aromatic group, or a substituted or non-substituted heterocyclic aromatic group. A symbol 'm' represents an integer in the range of from 2 to 4.
B-(COOH)n Chemical formula 2
B-(COOH)n Chemical formula 2
In the Chemical formula 2, a symbol 'B' represents an alkyl group having 1 to 20 carbon atoms, an alkylene group, a substituted or non-substituted aromatic group, or a substituted or non-substituted heterocyclic aromatic group. A symbol 'n' represents an integer in the range of from 2 to 4.
Specific examples of the polyol represented by Chemical formula 1 include, but are not limited to, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butane diol, neopentyl glycol, 1, 4-butene diol, 1,5-pentane diol, 1,6-hexane diol, 1,4-cyclohexane dimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butane triol, 1,2,5-pentane triol, glycerol, 2-methylpropane triol, 2-methyl-1,2,4-butane triol, trimethylol ethane, trimethylol propane, 1,3,5-trihydroxy benzene, bisphenol A, an adduct of bisphenol A with propylene oxide, hydrogenated bisphenol A, an adduct of hydrogenated bisphenol A with ethylene oxide, and an adduct of hydrogenated bisphenol A with propylene oxide.
Specific examples of the polycarboxylic acid represented by Chemical formula 2 include, but are not limited to, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthtalic acid, terephthalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, maronic acid, n-dodecenyl succinic acid, isooctyl succinic acid, isododecenyl succinic acid, n-octenyl succinic acid, n-octyl succinic acid, isooctenyl succinic acid, 1,2,4-benzene tricarboxylic acid, 2,5,7-naphthalene tricarboxylic acid, 1,2,4-naphthalene tricarboxylic acid, 1,2,4-butane tricarboxylic acid, 1,2,5-hexane tricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylene carboxy propane, 1,2,4-cyclohexane tricarboxylic acid, tetra(methylenecarboxyl)methane, 1,2,7,8-octane tetracarboxylic acid, pyromellitic acid, Empol® trimer acid, cyclohexane dicarboxylic acid, cyclohexene dicarboxylic acid, butane tetracarboxylic acid, diphenyl sulfone tetracarboxylic acid, and ethylene glycol bis(trimellitic acid).
It is preferable that the polyester resin satisfies the following requisites.
The glass transition temperature thereof is preferably from 30 degrees C to 80 degrees C.
The acid value of the polyester resin is preferably from 10 mgKOH/g to 30 mgKOH/g.
The weight average molecular weight Mw of polyester resin is preferably from 4,000 to 20,000.
The content of the polyester resin to the additive manufacturing powder is preferably from 1 percent by weight to 50 percent by weight.
Within this range, the polyester resin fulfills the features as binder resin.
In addition, in addition to the polyester resins specified above, for example, polyols can also be used.
Second Binder Resin
The second binder resin can be any rein that can form an aqueous liquid dispersion in an aqueous medium. The second binder resin can be selected to a specific application from known resins without a particular limitation. Of these, styrene-acrylic resins are preferable.
Styrene-acrylic resins can be thermoplastic resins or thermocurable resins.
Specific examples thereof include, but are not limited to, vinyl resins, polyurethane resins, epoxy resins, polyester resins, polyamide resins, polyimide resins, silicone resins, phenolic resins, melamine resins, urea resins, aniline resins, ionomer resins, and polycarbonate resins. These can be used alone or in combination.
Of these resins, it is preferable to use at least one kind of resin selected from the group consisting of vinyl resins, polyurethane resins, epoxy resins, and polyester resins to form the second resin because an aqueous liquid dispersion including fine spherical particles can be easily prepared. Specific examples of the vinyl resins include, but are not limited to, polymers, which are prepared by polymerizing a vinyl monomer or copolymerizing vinyl monomers, such as styrene-(meth)acrylate resins, styrene-butadiene copolymers, (meth)acrylic acid-acrylate copolymers, styrene-acrylonitrile copolymers, styrene-maleic anhydride copolymers, and styrene-(meth)acrylic acid copolymers.
Anionic styrene-acrylic resins are preferable. Such styrene-acrylic resins are manufactured by using an anionic activator or introducing an anionic group such as a carboxylic acid group or a sulfonic acid group into a resin in the method specified later. It is preferable that styrene-acrylic resins have particle forms. The average primary particle diameter thereof is preferably from 20 nm to 60 nm to control the particle diameter and the particle size distribution of emulsified particles. More preferably, the particle diameter ranges from 30 nm to 50 nm.
The particle diameter can be measured by scanning electron microscopy (SEM), transmission electron microscopy (TEM), a light scattering method, etc. Preferably, using LA-920 (manufactured by Horiba Ltd.) according to a laser scattering measuring method, the particle diameter is measured after suitable dilution for an appropriate measuring range. The volume average particle diameter is measured as the particle diameter.
Styrene-acrylic resin particulates can be obtained through polymerization using any suitably selected known method. It is preferred to obtain as an aqueous liquid dispersion of styrene-acrylic resin particulates. For example, as the method of preparing an aqueous liquid dispersion of the styrene-acrylic resin particulates, the following methods are suitable.
There is no specific lower limit but 0.2 or greater is preferable. The volume average particle diameter is obtained by the method described later.
Calcium phosphate and carbon material are described in detail.
There is no specific limit to calcium phosphatethe having a particle form or powder form. It can be selected to a particular application.
Specific examples of the materials for calcium phosphate include, but are not limited to, hydroxyapatite (HAp), carbonate apatite, fluoroapatite, α-tricalcium phosphate (α-TCP), β-tricalcium phosphate (β-TCP), tetracalcium phosphate, and octacalcium phosphate (OCP). These can be used alone or in combination.
Of these, in terms of obtaining an additive manufacturing object (solid free form) replaced with bones, hydroxyapatite (HAp), α-tricalcium phosphate (α-TCP), β-tricalcium phosphate (β-TCP), and octacalcium phosphate (OCP) are preferable.
It is possible to use particles or powder of products available on market formed of these materials as the calcium phosphate. Specific examples of the products include, but are not limited to, α-TCP and β-TCP. Calcium phosphate treated with known surface (modification) treatment can be also used to improve agglomeration property.
There is no specific limit to the manufacturing method of the calcium phosphate. It can be selected to a particular application. For example, precipitation method, etc. are used, which are suitably used in synthesis of hydroxyapatite (HAp).
There is no specific limit to the carbon material. It can be suitably selected to a particular application. For example, the content of carbon is preferably in the range of from 85 percent by weight to 100 percent by weight. Specific examples thereof include, but are not limited to, polyacrylonitrile (PAN) based carbon fiber, rayon-based carbon fiber, lignin-based carbon fiber, pitch-based carbon fiber, vapor-grown carbon fiber, carbon black, fullerene, graphene, carbon nanotube, and carbon nanohorn.
Of these, fullerene, graphene, carbon nanotube are preferable.
There is no specific limit to the form and structure of the carbon material. It can be suitably selected to a particular application. In terms of forms, for example, multi-layer carbon nanotube and single-layered carbon nanotube are suitable. When it comes to size, sub-micron order is preferable at most considering being encapsulated in the first binder resin (for example, polyester resin).
There is no specific limitation to the selection of the other known components that can be contained in the additive manufacturing powder. A suitable component can be selected to a particular application. Specific examples thereof include, but are not limited to, a chelate agent, fluidizer, a leveling agent, and a sintering additive.
Adding a fluidizer to the additive manufacturing powder is preferable because layers of the additive manufacturing powder are efficiently formed with ease.
Adding a leveling agent to the additive manufacturing powder is preferable because the wettability of the additive manufacturing powder is improved, so that handling becomes easy.
Adding a sintering additive to the additive manufacturing powder is preferable because sintering at lower temperatures is made possible in sintering treatment for obtained cured material (additive manufacturing object and cured material for sintering).
The volume average particle diameter Dv of the additive manufacturing powder preferably ranges from 4.0 µm to 10.0 µm and more preferably from 4.5 µm to 7.0 µm. When the volume average particle diameter Dv is 4.0 µm or greater, it is possible to suppress the interparticle action and agglomeration property, thereby improving the manufacturing efficiency of additive manufacturing object. To the contrary, when a thin layer is formed using the additive manufacturing powder having a volume average particle diameter Dv 10.0 µm or less, it is possible to increase the filling rate of the additive manufacturing powder in the thin layer, meaning reducing the void rate, so that the voids in the additive manufacturing object can be reduced. Incidentally, the average particle diameter of the additive manufacturing powder can be adjusted by the conditions of emulsification and/or dispersion by stirring, etc. of an aqueous medium in the emulsification process.
The volume average particle diameter of the additive manufacturing powder can be measured according to known methods using a known particle diameter measuring instrument such as Multisizer III (manufactured by Beckman Coulter, Inc.) and FPIA 3000 (manufactured by Sysmex Corporation).
The particle size distribution Dv/Dn, the rate of the volume average particle diameter Dv to the number average particle diameter Dn, is 1.5 or less, preferably 1.25 or less, and more preferably 1.15 or less. When the particle size distribution Dv/Dn surpasses 1.5, coarse particles may cause noises when forming a thin layer of the additive manufacturing powder and also fine powder increases, which may promote self agglomeration.
The particle size distribution Dv/Dn of the additive manufacturing powder can be measured according to known methods using a known particle diameter measuring instrument such as Multisizer III (manufactured by Beckman Coulter, Inc.) and FPIA 3000 (manufactured by Sysmex Corporation).
The average circularity of the additive manufacturing powder represented by the following relation is 0.800 or greater, preferably from 0.940 to 0.980, and more preferably from 0.960 to 0.970. The average circularity is defined as follows: Average circularity = a perimeter of circle having same area as a projected image of a particle / the perimeter of the projected image of the particle × 100.
When the average circularity is less than 0.800, the additive manufacturing powder easily agglomerates and also the filling rate thereof in the thin layer when forming a thin layer is insufficient so that voids tend to appear. That is, the object for additive manufacturing tends to have voids.
To the contrary, when the upper limit of the average circularity is suppressed to 0.980 or lower, removing uncured powder present inside becomes easy by air blow after additive manufacturing.
![Particle size distribution methods Particle size distribution methods](http://www.eng.uc.edu/~beaucag/Classes/Nanopowders/ParticleSizeDistribuhtml/ParticleSizeDistribu_files/image030.gif)
The average circularity can be measured according to known methods using a known circularity measuring instrument such as FPIA 3000 (manufactured by Sysmex Corporation).
There is no specific limit to the method of adjusting the value of Dv/Dn. For example, it can be adjusted by classification.
There is no specific limit to the method of adjusting the value of the average circularity. For example, it can be adjusted by classification.
The additive manufacturing powder of the present disclosure is used to fabricate various molded objects or structures easily and efficiently.
Method of Manufacturing Additive Manufacturing Object and Manufacturing Apparatus of Additive Manufacturing Object
The method of manufacturing the additive manufacturing object of the present disclosure includes a process of forming a powder layer for additive manufacturing using the additive manufacturing powder of the present disclosure and other optional processes.
The apparatus of manufacturing the object of additive manufacturing of the present disclosure includes at least a device of forming a powder layer for additive manufacturing using the additive manufacturing powder of the present disclosure and other optional devices.
The method of manufacturing the object of additive manufacturing of the present disclosure can be conducted by a manufacturing apparatus for the object for additive manufacturing. The process of forming a powder layer for additive manufacturing can be conducted by a device forming the powder layer for additive manufacturing. The other optional processes can be executed by the other optional devices.
Process of Forming Powder Layer for Additive Manufacturing and Device for Forming Powder Layer for Additive Manufacturing
The process of forming the powder layer for additive manufacturing is to form a powder layer for additive manufacturing having a desired thickness on a substrate using the additive manufacturing powder of the present disclosure.
The device to form the powder layer for additive manufacturing is to form a powder layer for additive manufacturing having a desired thickness on a substrate using the additive manufacturing powder of the present disclosure.
There is no specific limit to the substrate the additive manufacturing powder can be placed thereon. It can be selected to a particular application. For example, a board having a surface for the additive manufacturing powder or a base plate illustrated in FIG. 1 of
There is no specific limit to the method of depositing the additive manufacturing powder on a substrate. It can be selected to a particular application. For example, such a thin layer can be formed by a method using a known counter rotation mechanism (counter roller) for use in a selective laser sintering method described in
Using the counter rotation mechanism (counter roller), the brush, the blade, or the pressing member, a thin layer of the additive manufacturing powder can be formed on a substrate, for example, in the following manner:
In the outer frame (also referred to as 'form', 'hollow cylinder' 'tubular structure', etc.), the additive manufacturing powder is placed by the counter rotation mechanism (counter roller), the brush, the blade, the pressing member, etc. onto the substrate arranged to move up and down slidably in the inside wall of the outer frame. At this point, when a substrate movable up and down in the outer frame is used, the substrate illustrated in FIG. 1 mentioned above is arranged slightly lower than the upper open mouth of the outer frame. That is, while placing the substrate with a layer thickness of the additive manufacturing powder below the open mouth, the additive manufacturing powder is placed on the substrate. Thus, a thin layer of the additive manufacturing powder can be placed on the substrate.
Process of Sintering Powder Layer for Additive Manufacturing and Device for Sintering Powder Layer for Additive Manufacturing
In the method of manufacturing an object of additive manufacturing of the present disclosure, it is preferable to include a process of sintering the powder layer for additive manufacturing placed as the thin layer by irradiation of the powder layer with a laser beam or electron beam.
The additive manufacturing powder is cured upon application of such a laser beam or electron beam. On the thin layered cured material (hereinafter referred to as bottom layer for convenience), the additive manufacturing powder is placed again as described above (hereinafter referred to as top layer for convenience). To the powder layer (top layer) for additive manufacturing placed as a thin layer, the layer or the electron beam is applied again to cure the top layer. This curing occurs not only to the top layer but also to the interface with the bottom layer. As a consequence, the cured material (object of additive manufacturing) having a thickness corresponding to about two layers of the top layer and the bottom layer is obtained.
In addition, the additive manufacturing powder can be automatically and easily arranged to form a thin layer on the substrate by a known powder laminating device. A typical powder laminating device has a recoater to laminate the additive manufacturing powder, movable supplying tank to supply the additive manufacturing powder onto the substrate, and a movable layer forming tank to form and laminate a thin layer of the powder.
In the powder laminating device, the surface of the supplying tank can be elevated slightly above the surface of the forming tank by moving up the supplying tank, moving down the forming tank, or both. In addition, the additive manufacturing powder is arranged to form a thin layer using the recoater from the supplying tank and by repeating moving the recoater, the additive manufacturing powder of the thin layer is laminated.
There is no specific limitation to the thickness of the powder layer for additive manufacturing. It can be determined to a particular application. The average thickness of the thin layer is preferably from 3 µm to 200 µm and more preferably from 10 µm to 100 µm. When the average thickness is 3 µm or greater, the time to be taken to obtain an object of additive manufacturing can be shortened and the degree of problem of frame collapse during processing such as sintering and/or handling can be lowered. When the average thickness is 200 µm or less, the dimension accuracy of an object of additive manufacturing is improved. Incidentally, the average thickness can be measured by a known method.
The laser for use in the laser irradiation has an absorption wavelength range for calcium phosphate. It can be selected to a particular application. For example, CO2 laser, Nd-YAG laser, fiber laser, and semi-conductor laser can be used.
There is no specific limitation to the condition for the laser emission. It can be selected to a particular application. For example, when a small-sized laser is used, it is not possible to melt calcium phosphate, so that it is preferable that an adhesive (polyester) is mixed and melted by laser irradiation to form an object. In such a case, it is preferable to use CO2 laser.
As the irradiation conditions, for example, it is preferable that the laser power is 15 W, the wavelength is 10.6 µm and the beam diameter is about 0.4 mm.
There is no specific limitation to the electron beams if the beams melt calcium phosphate. It can be selected to a particular application. When the additive manufacturing powder is irradiated with an electron beam, the powder is placed in a vacuum condition. The device for manufacturing the powder layer is the same as above.
There is no specific limitation to the conditions of irradiation of electron beams. It can be determined to a particular application. For example, it is preferable that the laser power is 1,500 W, the beam diameter is about 0.1 mm, and the vacuum degree is about 1.0 × 10-5 mbar.
In addition, formed cured materials can be sintered by a known sintering furnace. As a result, the cured materials become an integrated molded object (i.e., object of additive manufacturing).
The other processes include a surface protection treatment process, a coating process, etc.
The other devices include a surface protection treatment device, a coating device, etc.
The surface protection treatment process means the cured material forming process or a process of forming a protection layer on an object formed in the sintering process. By executing the surface protection treatment process, durability is imparted to the surface of the fabricated object to the degree that, for example, the object can be used as is. Specific examples of the protection layer include, but are not limited to, a water-resistant layer, a weather resistant layer, a light resistant layer, a heat insulation layer, and a gloss layer. Specific examples of the surface protection treatment device include, but are not limited to, known surface protection treatment devices such as a spraying device and a coating device.
The coating process executes coating to the object of additive manufacturing. By this coating process, the object is colored in a desired color. Specific examples of the coating device include, but are not limited to, known coating devices using a spray, a roller, a brush.
By the manufacturing method and the manufacturing device of manufacturing an object of additive manufacturing, a complicated solid free-form object can be fabricated easily and efficiently with good dimension accuracy without frame collapse before sintering using the additive manufacturing powder of the present disclosure. Since the thus-obtained object of additive manufacturing has a sufficient strength and excellent dimension accuracy, representing fine roughness and curved planes, the object has aesthetic aspect with high quality and can be suitably used for various purposes.
Having generally described preferred embodiments of this invention, further understanding can be obtained by reference to certain specific examples which are provided herein for the purpose of illustration only and are not intended to be limiting. In the descriptions in the following examples, the numbers represent weight ratios in parts, unless otherwise specified.
The present disclosure is described in detail with reference to Examples and Comparative Examples. However, the present disclosure is not limited to these Examples.
0.342 mol/dm3 phosphoric acid aqueous solution was sent at a flow speed of 6 mL/min. to a 0.513 mol/dm3 calcium hydroxide suspension liquid stirred at 160rpm using a paddle available on market followed by adjusting pH around 8.7 by ammonium. Thereafter, subsequent to 72 hour aging in an incubator at 37 degrees C, the resultant was filtered followed by drying to obtain powder. After one hour baking at 800 degrees C, the resultant was ball-mill pulverized by zirconia bead having a diameter of 3 mm.
This ball-mill pulverization was conducted by BM-6 type roller ball mil (manufactured by Glen Creston Ltd.) for 30 minutes followed by screening with 75 µm mesh to obtain fine powder. Thereafter, the fine powder was baked at 1,400 degrees C for five hours followed by rapid cooling to obtain α-tricalcium phosphate (α-TCP) as Filler 1.
Identification of the crystal phase of the prepared α-tricalcium phosphate was conducted by X-ray powder diffraction instrument (RINT1100, manufactured by Rigaku Corporation) under the following conditions. The crystal phase was found to be α. Measuring Conditions
α-tricalcium phosphate (α-TCP) as [Filler 1] was measured according to the same method as the method for [Additive manufacturing powder 1] described later. The volume average particle diameter Dv was 4.7 µm.
The following components are placed in a container equipped with a condenser, a stirrer and a nitrogen introducing tube to conduct a reaction at 230 degrees C at normal pressure for 8 hours:
Thereafter, the resultant was caused to conduct 5 hour reaction with a reduced pressure of 10 mm Hg to 15mm Hg to synthesize a polyester resin. The thus-obtained non-crystalline polyester has an acid value of 17 mg/KOH, a weight average molecular weight Mw of 5,600, and a glass transition temperature of 50 degrees C.
The weight average molecular weight Mw of the synthesized polyester resin is measured by a gel permeation chromatography (GPC) under the following conditions: Measuring Conditions
1 mL of the sample having a concentration of 0.5 percent by weight was infused into the column and the weight average molecular weight Mw was calculated by using the molecular weight calibration curve obtained based on a simple dispersion polystyrene standard sample from the molecular weight distribution of the polymer measured under the conditions specified above. Incidentally, in the analysis, the polyester resin was dissolved in chloroform at 0.15 percent by weight followed by 0.2 µm filter. The filtrate was used as the sample.
In addition, the glass transition temperature Tg of the synthesized polyester resin was measured under the following conditions using TA-60WS and DSC-60, both manufactured by Shimadzu Corporation.
Starting Temperature: | 20 degrees C |
Heating speed: | 10 degrees C/min |
Ending temperature: | 150 degrees C |
Holding time: | None |
Cooling speed: | -10 degrees C/min |
Ending temperature: | 20 degrees C |
Holding time: | None |
Heating speed: | 10 degrees C/min |
Ending temperature: | 150 degrees C |
The measuring results were analyzed by using data analysis software (TA-60, version 1.52, manufactured by Shimadzu Corporation). To be specific, by assigning a range of from +5 degrees C to -5 degrees C relative to the maximum peak on the lowest temperature side of DrDSC curve representing the DSC differential curve in the second temperature rise, the peak temperature is obtained using a peak analysis feature of the analysis software. Next, in the range of from +5 degrees C to -5 degrees C relative to the peak temperature of the DSC curve, the maximum endothermic peak of the DSC curve using the peak analysis feature of the analysis software. The temperature shown here corresponds to the glass transition temperature Tg of the polyester resin.
40 parts by weight of [Filler 1] and 60 parts of the polyester resin were placed in a twin-shaft kneader (PCM-43, manufactured by Ikegai Corp.). [Powder material for additive manufacturing] was obtained by mixing and kneading at a rotation speed of 200 rpm and the mixing and kneading temperature of 190 degrees C. The supplying speed of the raw materials into the kneader was 10 kg/h and the average detention time was one minute.
100 parts by weight of [Powder material for additive manufacturing] (60 parts of polyester resin + 40 parts of [Filler 1]) and 130 parts of ethyl acetate were charged into a beaker followed by stirring for dissolution. Next, using a bead mill (ULTRA VISCO MILL, manufactured by IMEX Co., Ltd.), [Solution or liquid dispersion of material] was prepared under the conditions of a liquid sending speed of 1 kg/h, a disk perimeter speed of 6 m/s, 80 percent by volume filling of 0.5 mm zirconia beads, and 3 passes.
The following recipe was placed in a reaction container equipped with a stirrer and a thermometer and stirred at 400 rpm for 15 minutes to obtain a white emulsion:
The system was heated to 75 degrees C to conduct reaction for five hours. Furthermore, 30 parts of 1 percent ammonium persulfate aqueous solution was added followed by aging at 75 degrees C for five hours to obtain an aqueous liquid dispersion [Liquid dispersion of styrene acrylic resin particulate A] of a vinyl resin (copolymer of styrene-methacrylic acid-butyl acrylate-sodium salt of sulfuric acid ester of an adduct of methacrylic acid with ethylene oxide). [Liquid dispersion of styrene acrylic resin particulate A] had a volume average particle diameter (measured by LA-920, manufactured by Horiba Corporation) of 44 nm, an acid value of 180 mgKOH/g, a weight average molecular weight Mw of 500,000, and a Tg of 62 degrees C.
Thereafter, [Liquid dispersion of styrene acrylic resin particulate B] was synthesized in the same manner as in [Liquid dispersion of styrene acrylic resin particulate A] except that the stirring speed was changed to 600 rpm. [Liquid dispersion of styrene acrylic resin particulate B] had a volume average particle diameter (measured by LA-920, manufactured by Horiba Corporation) of 20 nm, an acid value of 180 mgKOH/g, a weight average molecular weight Mw of 500,000, and a Tg of 62 degrees C.
Thereafter, [Liquid dispersion of styrene acrylic resin particulate C] was synthesized in the same manner as in [Liquid dispersion of styrene acrylic resin particulate A] except that the stirring speed was changed to 300 rpm. [Liquid dispersion of styrene acrylic resin particulate C] had a volume average particle diameter (measured by LA-920, manufactured by Horiba Corporation) of 60 nm, an acid value of 180 mgKOH/g, a weight average molecular weight Mw of 500,000, and a Tg of 62 degrees C.
The styrene-acrylic resins as the second binder resin were added to a screw vial (30 mL, manufactured by AS ONE Corporation.) in such a manner that each of the resins reached 20 mL from the bottom followed by charging of 10 mL of ethyl acetate with pipette. After the resultant was left still for 24 hours, it was phase-separated in such a manner that an emulsion of white resin particulates was to the bottom and ethylacetate to the top. Swelling to ethylacetate was evaluated by observing the height of the white resin particulate emulsion from the bottom of the screw vial. A higher height reading means higher swelling. The degree of swelling was evaluated by observing the height of the resin particulate emulsion as follows: 'Swelling' means the subject to be evaluated as A, B, or C.
A: 21 mm or greater | Swelling |
B: 20 mm to less than 21 mm | Insufficiently swelling |
C: Less than 20 mm | No swelling |
Table 1 | |||
---|---|---|---|
Swelling | Compatibility with first binder resin | Volume average particle diameter | |
Liquid dispersion of styrene acrylic resin particulate A | A | Non-compatible | 44 nm |
Liquid dispersion of styrene acrylic resin particulate B | A | Non-compatible | 20 nm |
Liquid dispersion of styrene acrylic resin particulate C | A | Non-compatible | 60 nm |
660 parts of water, 25 parts of [Liquid dispersion of styrene acrylic resin particulate A], 25 parts of 48.5 percent by weight aqueous solution of sodium dodecyldiphenyl etherdisulfonate (EREMINOR MON-7, manufactured by Sanyo Chemical Industries, Ltd.), and 60 parts of ethyl acetate were mixed and stirred to obtain milk white liquid (aqueous phase).
150 parts of the aqueous medium phase was placed in a container and stirred at 12,000 rpm by a TK type HOMOMIXER (manufactured by PRIMIX Corporation). 100 parts of [Solution or liquid dispersion of material] was added thereto followed by mixing for 10 minutes to prepare an emulsion and/or liquid dispersion (emulsion slurry).
100 parts of the emulsion slurry was placed in a flask equipped with a pipe for degassing, a stirrer, and a thermometer and stirred at a stirring speed of 20 m/min to remove the solvent at 30 degrees C with a reduced pressure for 12 hours to obtain a solvent-removed slurry.
After all of the solvent-removed slurry was filtered with a reduced pressure, 300 parts of deionized water was added to the filtered cake and mixed and re-dispersed by a TK HOMOMIXER at 12,000 rpm for 10 minutes followed by filtration. 300 parts of deionized water was added to the thus-obtained filtered cake and the resultant was mixed by a TK HOMOMIXER at 12,000 rpm for 10 minutes followed by filtration, which was repeated three times. The resultant having a conductivity of the re-dispersed slurry ranging from 0.1 µS/cm to 10 µS/cm was defined as washed slurry.
The obtained filtered cake was dried by a circulation drier at 45 degrees C for 48 hours. The dried cake was sieved using a screen having an opening diameter of 75 µm to obtain [Additive manufacturing powder 1]. [Additive manufacturing powder 1] had a core-shell type particle having a shell on the surface of a core particle.
The volume average particle diameter Dv and the number average particle diameter Dn of the obtained [Additive manufacturing powder 1] were measured by a particle size measuring instrument (MULTISIZER III, manufactured by BECKMAN COULTER INC.) with an aperture diameter of 100 µm and the measuring results were analyzed by an analysis software (BECKMAN COULTER MULTISIZER 3 VERSION 3.51). To be specific, 0.5 ml of 10 percent by weight surfactant (alkylbenzene sulfonate, NEOGEN SC-A, manufactured by Daiichi Kogyo Co., Ltd.) was charged into a glass beaker (100 ml). 0.5 g of [Additive manufacturing powder 1] was added into the beaker and stirred by a microspatula. Thereafter, 80 ml of deionized water was added to the mixture. The thus-obtained liquid dispersion was subject to dispersion treatment for ten minutes using an ultrasonic wave dispersion device (W-113MK-II, manufactured by Honda Electronics). The liquid dispersion was measured by using the MULTISIZER III using ISOTON® III (manufactured by BECKMAN COULTER INC.) as the measuring solution. The sample liquid dispersion of [Additive manufacturing powder 1] was dripped such that the concentration indicated by the measuring device was from 6 percent to 10 percent. In this measuring method, it is suitable to keep the concentration in the range mentioned above in terms of measuring reproducibility. The measured particle diameter can be obtained without an error when the concentration is within that range.
The particle size distribution Dv/Dn was obtained from the thus-obtained volume average particle diameter Dv and the number average particle diameter Dn.
The average circularity of the obtained [Additive manufacturing powder 1] is defined as follows: Average circularity = a perimeter of a circle having same area as a projected image of a particle / the perimeter of the projected image of the particle × 100.
The average circularity is measured and calculated by measuring the particles by a flow type particle image analyzer (FPIA-2100, manufactured by Sysmex Corporation) followed by analysis using an analysis software (FPIA-2100 Data Processing Program For FPIA Version 00-10).
To be specific, 0.1 ml to 0.5 ml of 10 percent by weight surfactant (alkylbenzene sulfonate, NEOGEN SC-A, manufactured by Daiichi Kogyo Co., Ltd.) was charged into a glass beaker (100 ml). 0.1 g to 0.5 g of [Additive manufacturing powder 1] was added into the beaker and stirred by a microspatula. Thereafter, 80 ml of deionized water was added to the mixture. The thus-obtained liquid dispersion was subject to dispersion treatment for three minutes by an ultrasonic wave dispersion device (manufactured by Honda Electronics). The form and distribution of [Additive manufacturing powder 1] were measured by measuring the liquid dispersion by FPIA-2100 until the concentration was 5,000 particles/µl to 15,000 particles/µl.
In this measuring method, it is suitable to make the concentration of the liquid dispersion from 5,000 particles/µl to 15,000 particles/µl in terms of the measuring reproducibility of the average circularity. To obtain the concentration of the liquid dispersion, it is suitable to change the conditions of the liquid dispersion, that is, the amount of the surfactant to be added and the amount of [Additive manufacturing powder 1] are changed. The suitable amount of the surfactant varies depending on the hydrophobicity of [Additive manufacturing powder 1] as in the measuring of the particle diameter thereof. If an excessively large amount is added, the noise ascribable to bubbles tends to occur. If an excessively small amount is added. [Additive manufacturing powder 1] tends to be insufficiently wet, which leads to insufficient dispersion.
In addition, the addition amount of [Additive manufacturing powder 1] depends on the particle diameter. In a case of a small particle diameter, the amount is required to increase and, a large particle diameter, decrease. When the particle diameter of [Additive manufacturing powder 1] is from 3 µm to 7 µm, the addition amount of [Additive manufacturing powder 1] is 0.1 g to 0.5 g, thereby adjusting the concentration of the liquid dispersion to be 5,000 particles/µl to 15,000 particles/µl.
The measuring results are shown in Table 2.
0.342 mol/dm3 phosphoric acid aqueous solution was sent at 6 mL/min. to a suspension liquid of 0.513 mol/dm3 calcium hydroxide stirred at 160rpm by a paddle available on market followed by stabilizing the pH around 8.7 by ammonium. Thereafter, subsequent to 72 hour aging in an incubator at 37 degrees C, the resultant was filtered followed by drying to obtain powder. After one hour baking at 800 degrees C, the resultant was (ball-mill) pulverized by zirconia bead having a diameter of 3 mm.
This ball-mill pulverization was conducted by BM-6 type roller ball mil (manufactured by Glen Creston Ltd.) for 30 minutes followed by screening with 75 µm mesh to obtain fine powder. Thereafter, the fine powder was baked at 1,100 degrees C for five hours followed by rapid cooling to obtain β-tricalcium phosphate (β-TCP) as [Filler 2].
β-TCP as the thus-obtained [Filler 2] was measured in the same manner as in Preparation of [Filler 1]. The volume average particle diameter Dv was 5.0 µm.
0.342 mol/dm3 phosphoric acid aqueous solution was sent at 6 mL/min. to a suspension liquid of 0.455 mol/dm3 calcium hydroxide stirred at 160rpm using a paddle available on market followed by adjusting pH around 8.7 by ammonium. Thereafter, subsequent to 72 hour aging in an incubator at 37 degrees C, the resultant was filtered followed by drying to obtain powder. After one hour baking at 800 degrees C, the resultant was ball-mill pulverized by zirconia bead having a diameter of 3 mm. This ball-mill pulverization was conducted by BM-6 type roller ball mil (manufactured by Glen Creston Ltd.) for 30 minutes followed by screening with 75 µm mesh to obtain fine powder. Thereafter, the fine powder was baked at 1,100 degrees C for five hours followed by rapid cooling to obtain octacalcium phosphate (OCP) as [Filler 3].
OCP as the thus-obtained [Filler 3] was measured in the same manner as in Preparation of [Filler 1]. The volume average particle diameter Dv was 7.0 µm.
0.300 mol/dm3 phosphoric acid aqueous solution was sent at 6 mL/min. to a suspension liquid of 0.500 mol/dm3 calcium hydroxide stirred at 160rpm using a paddle available on market followed by adjusting pH around 8.7 by ammonium. Thereafter, subsequent to 72 hour aging in an incubator at 37 degrees C, the resultant was filtered followed by drying to obtain powder. After one hour baking at 800 degrees C, the resultant was (ball-mill) pulverized by zirconia bead having a diameter of 3 mm.
This ball-mill pulverization was conducted by BM-6 type roller ball mil (manufactured by Glen Creston Ltd.) for 30 minutes followed by screening with 75 µm mesh to obtain fine powder. Thereafter, the fine powder was baked at 1,000 degrees C for five hours to obtain hydroxyapatite (HAp) as [Filler 4].
HAp as the thus-obtained [Filler 4] was measured in the same manner as in Preparation of [Filler 1]. The volume average particle diameter Dv was 5.0 µm.
With regard to [Additive manufacturing powder 1], [Additive manufacturing object 1] was fabricated using an outer frame.
Second binder resin | |||||
Kind of resin | Tg (degrees C) | Acid value (mgKOH/g) | Mw | Particle diameter (nm) | |
Example 1 | St/Ac | 62 | 180 | 500,000 | 44 |
Example 2 | St/Ac | 62 | 180 | 500,000 | 44 |
Example 3 | St/Ac | 62 | 180 | 500,000 | 44 |
Example 4 | St/Ac | 62 | 180 | 500,000 | 44 |
Example 5 | St/Ac | 62 | 180 | 500,000 | 44 |
Example 6 | St/Ac | 62 | 180 | 500,000 | 44 |
Example 7 | St/Ac | 62 | 180 | 500,000 | 44 |
Example 8 | St/Ac | 62 | 180 | 500,000 | 44 |
Example 9 | St/Ac | 62 | 180 | 500,000 | 44 |
Example 10 | St/Ac | 62 | 180 | 500,000 | 44 |
Example 11 | St/Ac | 62 | 180 | 500,000 | 44 |
Example 12 | St/Ac | 62 | 180 | 500,000 | 44 |
Example 13 | St/Ac | 62 | 180 | 500,000 | 44 |
Example 14 | St/Ac | 62 | 180 | 500,000 | 44 |
Example 15 | St/Ac | 62 | 180 | 500,000 | 44 |
Example 16 | St/Ac | 62 | 180 | 500,000 | 44 |
Example 17 | St/Ac | 62 | 180 | 500,000 | 44 |
Example 18 | St/Ac | 62 | 180 | 500,000 | 44 |
Example 19 | St/Ac | 50 | 150 | 620,000 | 38 |
Example 20 | St/Ac | 58 | 250 | 430,000 | 52 |
Example 21 | St/Ac | 64 | 221 | 480,000 | 20 |
Example 22 | St/Ac | 68 | 163 | 680,000 | 60 |
Example 23 | St/Ac | 36 | 237 | 200,000 | 47 |
Example 24 | St/Ac | 77 | 155 | 800,000 | 55 |
Example 25 | St/Ac | 30 | 204 | 230,000 | 31 |
Example 26 | St/Ac | 80 | 169 | 770,000 | 36 |
Example 27 | St/Ac | 62 | 180 | 500,000 | 44 |
Example 28 | St/Ac | 62 | 180 | 500,000 | 44 |
Example 29 | St/Ac | 62 | 180 | 500,000 | 44 |
Example 30 | St/Ac | 62 | 180 | 500,000 | 44 |
Example 31 | St/Ac | 62 | 180 | 500,000 | 44 |
Comparative Example 1 | St/Ac | 62 | 180 | 500,000 | 44 |
Comparative Example 2 | Ac | 77 | 192 | 440,000 | 61 |
Comparative Example 3 | St/Ac | 62 | 180 | 500,000 | 44 |
Comparative Example 4 | None | - | - | - | - |
Comparative Example 5 | None | - | - | - | - |
Comparative Example 6 | St/Ac | 62 | 180 | 500,000 | 44 |
Additive manufacturing powder | Additive manufacturing object | |||||
Particle diameter (µm) | A/B | Particle size distribution | Circularity | Strength | Dimension Accuracy | |
Example 1 | 5.2 | 0.66 | 1.15 | 0.966 | B | C |
Example 2 | 4.8 | 0.71 | 1.18 | 0.969 | B | C |
Example 3 | 5.9 | 0.68 | 1.24 | 0.958 | B | C |
Example 4 | 5.6 | 0.43 | 1.21 | 0.960 | B | C |
Example 5 | 5.4 | 0.69 | 1.22 | 0.957 | B | C |
Example 6 | 5.8 | 0.72 | 1.24 | 0.951 | B | C |
Example 7 | 6.4 | 0.55 | 1.23 | 0.948 | B | C |
Example 8 | 4.0 | 0.73 | 1.15 | 0.972 | B | B |
Example 9 | 10.0 | 0.57 | 1.21 | 0.946 | B | B |
Example 10 | 6.3 | 0.60 | 1.25 | 0.944 | B | B |
Example 11 | 6.1 | 0.61 | 1.24 | 0.940 | B | B |
Example 12 | 4.2 | 0.71 | 1.14 | 0.980 | B | B |
Example 13 | 5.2 | 0.66 | 1.19 | 0.958 | B | C |
Example 14 | 5.6 | 0.64 | 1.21 | 0.951 | B | C |
Example 15 | 8.5 | 0.60 | 1.22 | 0.943 | B | B |
Example 16 | 6.6 | 0.61 | 1.23 | 0.945 | B | B |
Example 17 | 5.2 | 0.67 | 1.14 | 0.967 | B | C |
Example 18 | 7.4 | 0.62 | 1.18 | 0.977 | B | B |
Example 19 | 9.3 | 0.58 | 1.24 | 0.941 | B | C |
Example 20 | 8.8 | 0.61 | 1.24 | 0.942 | B | C |
Example 21 | 6.8 | 0.63 | 1.23 | 0.948 | B | C |
Example 22 | 8.4 | 0.61 | 1.24 | 0.971 | B | B |
Example 23 | 6.0 | 0.67 | 1.22 | 0.961 | B | B |
Example 24 | 5.3 | 0.68 | 1.16 | 0.974 | B | B |
Example 25 | 5.0 | 0.69 | 1.15 | 0.977 | B | B |
Example 26 | 5.7 | 0.65 | 1.16 | 0.975 | B | B |
Example 27 | 5.2 | 0.66 | 1.15 | 0.966 | B | C |
Example 28 | 5.7 | 0.68 | 1.29 | 0.857 | B | B |
Example 29 | 5.4 | 0.66 | 1.42 | 0.895 | B | B |
Example 30 | 5.2 | 0.67 | 1.16 | 0.967 | B | B |
Example 31 | 6.9 | 0.79 | 1.24 | 0.940 | B | B |
Comparative Example 1 | Unable to granulate | A | A | |||
Comparative Example 2 | Unable to granulate | A | A | |||
Comparative Example 3 | Unable to granulate | A | A | |||
Comparative Example 4 | Unable to granulate | A | A | |||
Comparative Example 5 | 27.8 | A | 0.725 | B | A | |
Comparative Example 6 | 9.4 | A | 0.784 | A | A |
According to the present invention, provided is additive manufacturing powder that can fabricate a laminate object having a complex solid free form with high mechanical strength and good dimension accuracy.
Having now fully described embodiments of the present invention, it will be apparent to one of ordinary skill in the art that many changes and modifications can be made thereto without departing from the spirit and scope of embodiments of the invention as set forth herein.