JP7099473B2 - A resin composition and a method for producing a three-dimensional model using the resin composition. - Google Patents

Description

The present invention relates to a resin composition and a method for producing a three-dimensional model using the resin composition.

In recent years, various methods have been developed that can relatively easily produce three-dimensional objects having complicated shapes, and rapid prototyping and rapid manufacturing using such methods are attracting attention.

Conventionally, these methods for producing shaped objects have been widely used in the field of modeling, but in recent years, there has been an active movement to develop these methods directly into manufacturing. In order to directly use a three-dimensional model for direct production, it is required to have high strength, high ductility, and high modeling accuracy.

Among various methods for producing three-dimensional objects, it is known that a method using resin particles such as a powder bed melt-bonding method can produce a three-dimensional object with relatively high modeling accuracy as compared with other methods. .. For example, in the powder bed melt bonding method, resin particles are spread flat to form a thin layer. Then, the thin layer is irradiated with laser light in a pattern (a pattern in which a three-dimensional model is finely divided in the thickness direction). As a result, the resin particles in the region irradiated with the laser beam are selectively sintered or melt-bonded (hereinafter, also simply referred to as “melt-bonding”). Then, resin particles are further spread on the obtained modeled object layer, and laser light irradiation is performed in the same manner. By repeating these steps, the shaped object layers are piled up, and a three-dimensional shaped object having a desired shape can be obtained.

However, when the thin layer is formed, the resin particles are usually spherical even if the resin particles are arranged without gaps. Therefore, the contact area between the adjacent resin particles is very small, and it is difficult for heat to be transferred at the interface between the resin particles. Therefore, there is a problem that the molten state and the temperature tend to vary when the thin layer is irradiated with the laser beam. Similarly, the contact area between the already formed shaped object layer and the newly formed thin layer (resin particles) is also small. Therefore, it is difficult for heat to be transferred to each other even between them. Therefore, the degree of heat shrinkage differs between the previously formed model layer and the later model layer, and the warp (hereinafter, the warp generated in this way is also referred to as "heat warp"). There was also the problem that.

On the other hand, as a method for producing a three-dimensional model, a method in which a resin composition is melt-extruded into a filament and a thin layer obtained by finely dividing the three-dimensional model in the thickness direction is formed on a stage to obtain the three-dimensional model (heat). Fused deposition modeling method) is also known. It has been proposed to add various fillers to such a resin composition to impart conductivity to the obtained three-dimensional model and increase the elastic modulus of the obtained three-dimensional model (Patent Document 1). ..

Japanese Unexamined Patent Publication No. 2016-28887

Further, in recent years, the following methods have been proposed as another method for manufacturing a three-dimensional model using resin particles. First, the resin particles are spread flat to form a thin layer. Then, the binding fluid containing an infrared light absorber or the like is applied only to the region of the thin layer to be cured (a pattern in which a desired three-dimensional model is finely divided in the thickness direction). On the other hand, the exfoliation fluid, which absorbs less energy than the coupling fluid, is applied to the region where the coupling fluid is not applied. After that, irradiation with infrared light is performed, and only the powder material in the region coated with the binding fluid is heated and melted. Then, by repeating these steps, the shaped object layers are piled up to obtain a desired three-dimensional shaped object (hereinafter, the method is also referred to as "MJF method"). Even in this method, it is difficult to increase the thermal conductivity between adjacent particles, and problems such as variation in the molten state in the modeled object layer and thermal warpage are likely to occur.

Therefore, it is conceivable to include a filler inside the resin particles used in the above-mentioned method for manufacturing a three-dimensional model, as in Patent Document 1. However, it is difficult to increase the thermal conductivity between adjacent resin particles only by adding a general filler, and the addition of a filler tends to cause a problem that the ductility of a three-dimensional model is rather lowered. ..

The present invention has been made in view of the above problems. That is, the present invention provides a resin composition for obtaining a three-dimensional model having high strength, high ductility, no thermal warpage, and high dimensional accuracy, and a method for manufacturing the three-dimensional model using the resin composition. The purpose is to provide.

The present invention provides the following resin compositions.
[1] A resin composition used in a three-dimensional modeling method for forming a three-dimensional model by repeatedly forming a thin layer containing a particulate resin composition and repeatedly irradiating the thin layer with energy, and is a thermoplastic resin. A resin composition comprising particles containing, and flat particles having a thickness of 50 to 500 nm.

[2] The resin composition according to [1], wherein the flat particle has a width of 1 to 10 μm.
[3] The resin composition according to [1] or [2], wherein the flat plate-like particles are attached around the particles containing the thermoplastic resin.
[4] The resin composition according to any one of [1] to [3], wherein the flat plate-shaped particles are contained inside the particles containing the thermoplastic resin.

[5] The resin composition according to any one of [1] to [4], wherein the tabular particles are silicate compounds containing magnesium.
[6] The resin composition according to any one of [1] to [5], wherein the flat particle is talc.
[7] The resin composition according to any one of [1] to [6], wherein the thermoplastic resin is a crystalline resin.
[8] The resin composition according to any one of [1] to [7], wherein the thermoplastic resin is an olefin resin.

The present invention provides the following three-dimensional model and a method for manufacturing the three-dimensional model.
[9] A three-dimensional model containing a cured product of the resin composition according to any one of the above [1] to [8].
[10] A thin layer forming step of forming a thin layer containing the resin composition according to any one of the above [1] to [8], and the plurality of said thin layers by selectively irradiating the thin layer with laser light. A three-dimensional modeling is performed by repeating the thin layer forming step and the laser light irradiation step a plurality of times, including a laser light irradiation step of forming a shaped object layer in which the resin composition is melt-bonded, and laminating the shaped object layers. A method for manufacturing a three-dimensional model that forms an object.
[11] A thin layer forming step for forming a thin layer containing the resin composition according to any one of the above [1] to [8], a binding fluid containing an energy absorber, and energy absorption from the binding fluid. The thermoplasticity of the region in which the thinning fluid is applied to the regions adjacent to each other in the thin layer, and the thin layer is irradiated with energy after the fluid coating step and the binding fluid is applied. An energy irradiation step of melting a resin to form a shaped object layer is included, and the thin layer forming step, the fluid coating step, and the energy irradiation step are repeated a plurality of times, and the shaped object layer is laminated to form a three-dimensional structure. A method for manufacturing a three-dimensional model that forms a model.

According to the resin composition of the present invention, it is possible to produce a three-dimensional model having high strength, high ductility, no thermal warpage, etc., and high dimensional accuracy.

1. 1. Resin Composition The resin composition of the present invention is used in a method for producing a three-dimensional model by melt-bonding particles containing a resin, such as a powder bed melt-bonding method and an MJF method. The resin composition of the present invention includes particles containing a thermoplastic resin (hereinafter, also simply referred to as “resin particles”), and tabular particles. Here, in the present specification, the flat particle has two main planes facing each other, and the distance (thickness) between these two main planes is the maximum diameter (hereinafter, "width") of the main planes. ) And particles that are sufficiently small for the minimum diameter.

As described above, in the powder bed melt bonding method and the MJF method, a thin layer made of resin particles is formed, and the thin layer is irradiated with energy. As a result, the adjacent resin particles are melt-bonded to each other to obtain a modeled object layer in which the three-dimensional modeled object is finely divided in the thickness direction. However, since the resin particles are usually spherical, the contact area between the adjacent resin particles is very small, and heat is difficult to transfer. As a result, there is a problem that the molten state and temperature of each resin particle tend to vary in the modeled object layer. Further, there is also a problem that the thermal conductivity between the previously formed model layer and the later model layer is low, and thermal warpage is likely to occur due to the difference in the degree of heat shrinkage between them. ..

To solve such a problem, the resin composition of the present invention contains, together with the resin particles, flat-plate particles having a thickness of 50 nm to 500 nm. Since the flat plate-shaped particles are sufficiently thin, the temperature tends to be uniform in the flat plate-shaped particles. Then, such flat plate-shaped particles make it possible to make the temperatures of adjacent resin particles uniform. That is, in the resin composition of the present invention, the molten state of each resin particle tends to be uniform, and the dimensional accuracy and strength of the obtained three-dimensional model are improved.

Similarly, according to the resin composition of the present invention, the temperature of the previously formed shaped object layer and the thin layer containing the resin composition arranged on the previously formed layer can be easily made uniform. As a result, the degree of heat shrinkage is less likely to vary between the first formed model layer and the later formed model layer, and thermal warpage and the like are less likely to occur, which also enhances dimensional accuracy.

Further, when the obtained three-dimensional model contains the flat plate particles having the above thickness, the elastic modulus of the three-dimensional model is increased and the strength of the three-dimensional object is increased. Furthermore, when conventional general spherical ceramic particles are included in the three-dimensional model, when tensile stress or the like is applied to the three-dimensional model, the difference in elastic modulus between the resin and the ceramic particles causes the resin and the ceramic particles to be separated from each other. Gap and cracks are likely to occur. Then, by connecting such gaps and cracks, the three-dimensional model is likely to break. On the other hand, when a tensile stress is applied to a three-dimensional object containing flat plate-shaped particles, the flat plate-shaped particles have a property of arranging in parallel with the tensile direction thereof. Therefore, the three-dimensional model containing the flat-plate particles has an advantage that gaps and cracks are unlikely to occur between the resin and the flat-plate particles when a tensile stress is applied, and the ductility of the three-dimensional model is enhanced.

Further, in the resin composition of the present invention, when the thermoplastic resin contained in the resin particles is a crystalline resin, the thermoplastic resin melted during the formation of the model layer is crystallized by using the flat plate particles as a nucleating agent. It will be easier. As a result, the resin having a uniform crystal structure is likely to be contained in the three-dimensional model, and the strength and ductility of the three-dimensional model are likely to be uniform. In addition, by suppressing the distorted crystal growth, the dimensional accuracy is likely to be improved.

Here, in the resin composition of the present invention, the flat plate-like particles may be contained inside the resin particles. Further, the flat plate-shaped particles may be attached to the periphery of the resin particles. Further, the flat plate particles may be contained inside the resin particles and around the resin particles. However, if the flat plate-shaped particles are attached around the resin particles, the flat plate-shaped particles are likely to be included between the adjacent resin particles when the model layer is formed. As a result, it is preferable from the viewpoint that the temperature and the molten state of the adjacent resin particles are more likely to be made uniform. When the flat plate particles are also contained inside the resin particles, the strength of the obtained three-dimensional model is likely to increase.

When the flat plate-shaped particles are attached to the periphery of the resin particles, it is preferable that the flat plate-shaped particles are attached to a region of 10 to 80% of the surface area of the resin particles. When the area of the region to which the flat plate particles are attached is 80% or less with respect to the surface area of the resin particles, the resin particles are sufficiently easily melt-bonded to each other during the production of the three-dimensional model. On the other hand, when a region of 10% or more of the surface area of the resin particles is covered with the flat plate-shaped particles, the thermal conductivity of the flat plate-shaped particles is increased, and the temperature and the molten state of the adjacent resin particles are likely to be uniform. .. The extent to which the flat plate particles adhere to the periphery of the resin particles is determined by the particle size of the resin particles, the area when the flat plate particles are viewed in a plan view, the content ratio of the thermoplastic resin and the flat plate particles, etc. It can be calculated from. In addition, for the resin particles to which the flat plate particles are attached to the surroundings, the resin is dissolved with a solvent or the like to specify the content and shape of the flat plate particles, and these and the shape (particle size, etc.) of the resin particles are used. , The area to which the flat resin particles are attached may be calculated. Hereinafter, the flat particles and the thermoplastic resin contained in the resin composition, and other components and the like will be described in detail.

(Plate particles)
The flat plate-shaped particles contained in the resin composition of the present invention are not particularly limited as long as they have a thickness of 50 to 500 nm and are flat plate-shaped particles. The thickness of the tabular particles is more preferably 100 to 400 nm, and even more preferably 150 to 300 nm. When the thickness of the flat plate particles is 50 nm or more, the strength of the obtained three-dimensional model tends to increase. On the other hand, when the thickness of the flat plate particles is 500 nm or less, the thermal conductivity tends to be good.

The shape of the flat plate particles in a plan view may be a circular shape, an elliptical shape, or a polygonal shape. Among these, an elliptical shape is more preferable. The width (average maximum diameter) of the tabular particles when viewed in a plan view is preferably 1 to 10 μm, more preferably 2 to 8 μm, and even more preferably 3 to 6 μm. If the width (average maximum diameter) of the flat plate-shaped particles is excessively large, the dimensional accuracy of the three-dimensional model is lowered, and the flat plate-shaped particles tend to inhibit the melt-bonding of the resin particles. On the other hand, if the width (average maximum diameter) of the flat plate particles is too small, the flat plate particles may not sufficiently transfer heat to the adjacent resin particles.

Further, the average minimum diameter when the flat plate particles are viewed in a plan view is preferably 1 to 6 μm, and more preferably 2 to 5 μm.

The ratio (width / thickness) of the average thickness of the flat plate particles to the average maximum diameter (width) is preferably 5 to 15, and more preferably 10 to 12. On the other hand, the ratio (minimum diameter / thickness) of the average thickness of the flat plate particles to the average minimum diameter is preferably 5 to 13, and more preferably 6 to 11. When the ratio of the thickness of the flat plate particles to the width and the average minimum diameter is within the above range, the thermal conductivity of the flat plate particles tends to be good.

The thickness, maximum diameter, and width of the flat particle are specified as follows, for example. The thermoplastic resin is removed using a solvent or the like capable of dissolving the thermoplastic resin, and only the flat particles are taken out. If the resin is difficult to dissolve in the solvent, heat it if necessary. Then, it is dry-mixed with the propylene resin so that the amount of the flat plate particles is 15% by mass. Then, using a known small kneader and injection molding machine, for example, a dumbbell test piece having a length of 175 mm is produced. However, the shape of the test piece is not particularly limited as long as the cross section of the flat plate particles can be measured by 100 or more. Then, the test piece is immersed in liquid nitrogen for 10 minutes or more and cracked while freezing in the liquid nitrogen. For the flat plate particles existing in the fracture surface, 100 thicknesses, 100 maximum diameters (widths), 100 average minimum diameters, etc. are observed with an electron microscope (SEM), and a histogram is created. Then, the average value is calculated for each of these data, and the average value is adopted as the thickness, width, and average minimum diameter of the flat plate particles.

Examples of tabular particles include various particles generally referred to as layered clay minerals. Specific examples of the plate-like particles include kaolin; talc; mica; montmorillonite, byderite, hectrite, saponite, nontronite, stephensite and other smectite minerals; vermiculite; bentonite; canemite, kenyanite, macanite and the like. Sodium acid; Na-type tetrasilicic fluorine mica, Li-type tetrasilisic fluorine mica, Na-type fluorine teniolite, Li-type fluorine teniolite and other mica-type clay minerals; and the like are included. Such tabular particles may be obtained from natural minerals or may be chemically synthesized. Further, the surface of the flat plate particles may be modified (surface treated) with an ammonium salt or the like.

Among these, compounds having a thermal conductivity of 0.5 to 5.0 W · m ^-1 · K ^-1 are preferable. When the flat plate-shaped particles have the above-mentioned thermal conductivity, the temperature of the adjacent resin particles can be easily made uniform by the flat plate-shaped particles.

Further, from the viewpoint of particularly good thermal conductivity, a silicate compound containing magnesium is preferable, and talc and mica are preferable. The component analysis of the plate-shaped particles can be performed by, for example, X-ray photoelectron spectroscopy XPS (X-ray Photoelectron Spectroscopy) or ESCA (Electron Spectroscopy for Chemical Analysis, Esca). Specific devices include an ESCALAB-200R photoelectron spectroscope manufactured by VG Scientific.

The tabular particles are preferably contained in an amount of 5 to 40 parts by mass, more preferably 10 to 20 parts by mass, based on 100 parts by mass of the total amount of the resin composition. If the amount of the flat plate particles in the resin composition is too small, it may be difficult to sufficiently exhibit the above-mentioned thermal conductivity, or it may be difficult to sufficiently increase the strength of the three-dimensional model. On the other hand, when the amount of the flat plate particles is excessive, the amount of the thermoplastic resin is relatively reduced, so that the thermoplastic resin cannot be sufficiently melt-bonded, and the strength of the three-dimensional model may be lowered.

(Thermoplastic resin)
The type of the thermoplastic resin contained in the resin composition is appropriately selected according to the method for forming the three-dimensional model. The thermoplastic resin can be a resin contained in a resin composition for a general powder bed melt-bonding method or a resin contained in a resin composition for the MJF method, and the resin particles are thermoplastic. Only one type of resin may be contained, or two or more types may be contained.

However, if the melting temperature of the thermoplastic resin is too high, it may be necessary to irradiate energy to a high temperature in order to melt the resin particles when manufacturing the three-dimensional model, and it may take time to manufacture the three-dimensional model. be. Therefore, the melting temperature of the thermoplastic resin is preferably 300 ° C. or lower, more preferably 230 ° C. or lower. On the other hand, from the viewpoint of heat resistance and the like of the obtained three-dimensional model, the melting temperature of the thermoplastic resin is preferably 100 ° C. or higher, more preferably 150 ° C. or higher. The melting temperature can be adjusted depending on the type of the thermoplastic resin and the like.

Here, the thermoplastic resin may be a crystalline resin or an amorphous resin, but as described above, when the thermoplastic resin is a crystalline resin, the flat particles are nucleated. As an agent, it has an advantage that it becomes easy to form uniform crystals. Examples of the crystalline resin include polyamide 12, polylactic acid, polyolefin resins such as polypropylene, polyphenylene sulfide (PPS), polybutylene terephthalate and the like. Among these, polyamide 12 or an olefin resin is preferable, and polypropylene resin is particularly preferable, from the viewpoint that the crystal structure is close to that of the flat plate particles and the flat plate particles can be easily crystallized uniformly as a nucleating agent.

Here, the thermoplastic resin is preferably contained in an amount of 60 to 95 parts by mass, more preferably 80 to 90 parts by mass, based on 100 parts by mass of the total amount of the resin composition. If the amount of the thermoplastic resin in the resin composition is too small, the strength of the three-dimensional model tends to decrease. On the other hand, if the amount of the resin composition is too large, the amount of the flat plate-like particles is relatively reduced, and it becomes difficult to exhibit the above-mentioned thermal conductivity.

The shape of the resin particles containing the thermoplastic resin is not particularly limited, but the shape is preferably spherical from the viewpoint of improving the dimensional accuracy of the three-dimensional model. Further, the size (diameter) of the resin particles is preferably 20 to 100 μm, more preferably 30 to 70 μm. When the size of the resin particles is 100 μm or less, it is possible to produce a three-dimensional model having a fine structure. On the other hand, the size of the resin particles is preferably 20 μm or more from the viewpoint of having sufficient fluidity and improving manufacturing cost and handleability. The average particle size is the volume average particle size measured by the dynamic light scattering method. The volume average particle size can be measured by a laser diffraction type particle size distribution measuring device (MT3300EXII manufactured by Microtrac Bell) equipped with a wet disperser.

(Other ingredients)
The resin composition may contain components other than the above-mentioned flat particles and the thermoplastic resin as long as the object and effect of the present invention are not impaired. Examples of other components include various additives, fillers and the like.

Examples of various additives include antioxidants, acidic compounds and derivatives thereof, lubricants, UV absorbers, light stabilizers, nucleating agents, flame retardants, impact improvers, foaming agents, colorants, organic peroxides, and exhibitions. Includes dressing agents, adhesives, etc. The resin composition may contain only one of these, or may contain two or more of them. Further, these may be applied to the surface of the resin particles as long as the object of the present invention is not impaired.

Examples of the filler include inorganic particles that do not correspond to the above-mentioned flat particles, various fibers, and the like. Examples include talc, calcium carbonate, zinc carbonate, wallastnite, silica, alumina, magnesium oxide, calcium silicate, sodium aluminate, calcium aluminate, sodium aluminosilicate, magnesium silicate, glass balloons, glass cut fiber, Glass milled fiber, glass flakes, glass powder, silicon carbide, silicon nitride, gypsum, gypsum whisker, calcined kaolin, carbon black, zinc oxide, antimony trioxide, zeolite, hydrotalcite, metal fiber, metal whisker, metal powder, ceramic Inorganic fillers such as whiskers, potassium titanate, boron nitride, graphite and carbon fibers; organic fillers such as polysaccharide nanofibers; various polymers and the like are included. The resin composition may contain only one of these, or may contain two or more of them. However, these amounts are preferably smaller than the above-mentioned flat particles.

Further, the resin composition used in the powder bed melt bonding method may contain a laser absorber or the like. Examples of laser absorbers include carbon powders, nylon resin powders, pigments, dyes and the like. Only one kind of these laser absorbers may be contained in the resin composition, or two or more kinds thereof may be contained.

(Manufacturing method of resin composition)
The method for producing the resin composition is not particularly limited, and is appropriate depending on whether the tabular particles are attached to the periphery of the resin particles or the tabular particles are contained inside the resin particles. Be selected. For example, the resin composition in which the flat plate particles are attached around the resin particles can be prepared by preparing the resin particles in advance and mixing the resin particles and the flat plate particles by a known method. On the other hand, the resin composition in which the flat plate-shaped particles are contained inside the resin particles can be produced by melt-kneading the flat plate-shaped particles and the resin and pulverizing them with a freeze crusher or the like. Further, a resin composition in which the flat plate particles are present inside and around the resin particles can be produced by combining these methods.

2. 2. Method for Producing a Three-dimensional Model The above-mentioned resin composition can be used in a method for producing a three-dimensional model by a powder bed bond melting method or an MJF method as described above. Hereinafter, three-dimensional modeling methods using the above resin compositions will be described, but the present invention is not limited to these methods.

2-1. Method for manufacturing a three-dimensional model by a powder bed bond melting method The method for manufacturing a three-dimensional model by a powder bed bond melting method can be performed in the same manner as a normal powder bed bond melting method except that the resin composition is used. Specifically, (1) a thin layer forming step of forming a thin layer containing the above-mentioned resin composition, and (2) the thin layer containing the resin composition is selectively irradiated with laser light to form the particles. It can be a method including a laser light irradiation step of forming a molded product layer in which the resin compositions of the above are melt-bonded to each other. Then, by repeating the step (1) and the step (2) a plurality of times and laminating the modeled object layer, a three-dimensional modeled object can be manufactured. The method for producing the three-dimensional model may include other steps, if necessary, and may include, for example, a step of preheating the resin composition.

・ Thin layer forming step (step (1))
In this step, a thin layer containing the resin composition is formed. For example, the resin composition supplied from the powder supply unit of the three-dimensional modeling apparatus is spread flat on the modeling stage by a recoater. The thin layer may be formed directly on the build stage or may be formed so as to be in contact with the powder material already spread or the already formed build layer. If necessary, the resin composition may be separately mixed with a flow agent or a laser absorber.

The thickness of the thin layer is the same as the thickness of the desired model layer. The thickness of the thin layer can be arbitrarily set according to the accuracy of the three-dimensional model to be manufactured, but is usually 0.01 mm or more and 0.30 mm or less. By setting the thickness of the thin layer to 0.01 mm or more, it is possible to prevent the resin composition of the lower layer from being melt-bonded by laser light irradiation for forming the next modeled object layer, and further. It is possible to spread uniform powder. Further, by setting the thickness of the thin layer to 0.30 mm or less, the energy of the laser beam is conducted to the lower part of the thin layer, and the resin composition constituting the thin layer is sufficiently melt-bonded over the entire thickness direction. Can be made to. From the above viewpoint, the thickness of the thin layer is more preferably 0.01 mm or more and 0.10 mm or less. Further, from the viewpoint of melting and bonding the resin composition more sufficiently over the entire thickness direction of the thin layer and making it more difficult for the modeled object layer to crack, the thickness of the thin layer is the beam spot diameter of the laser beam described later. It is preferable to set so that the difference from the above is within 0.10 mm.

Here, examples of the laser absorber that can be mixed with the resin composition include carbon powder, nylon resin powder, pigment, dye and the like. The amount of the laser absorber can be appropriately set within a range that facilitates melt bonding of the resin composition. For example, it can be more than 0% by mass and less than 3% by mass with respect to the total mass of the thermoplastic resin. The laser absorber may be used alone or in combination of two or more.

On the other hand, the flow agent that can be mixed with the resin composition may be a material having a small friction coefficient and self-lubricating property. Examples of such flow agents include silicon dioxide and boron nitride. These flow agents may be used alone or in combination of two. The amount of the flow agent can be appropriately set within a range in which the fluidity of the resin particles and the like is improved and the melt bonds of the resin particles are sufficiently generated. For example, it can be more than 0% by mass and less than 2% by mass with respect to the mass of the thermoplastic resin.

-Laser light irradiation process (process (2))
In this step, among the thin layers containing the resin composition, the laser beam is selectively irradiated to the position where the modeled object layer should be formed, and the resin composition at the irradiated position is melt-bonded. The melted resin composition melts with the adjacent resin composition (resin particles) to form a melt-bonded body, and becomes a modeled product layer. At this time, since the resin composition (resin particles) that has received the energy of the laser beam is melt-bonded to the already formed shaped object layer, adhesion between adjacent layers also occurs.

The wavelength of the laser beam may be set within the range of the wavelength absorbed by the resin composition. At this time, it is preferable to make the difference between the wavelength of the laser beam and the wavelength at which the absorption rate of the resin composition is highest small, but in general, the thermoplastic resin absorbs light in various wavelength ranges. Therefore, it is preferable to use a laser beam having a wide wavelength band such as a CO ₂ laser. For example, the wavelength of the laser beam can be, for example, 0.8 μm or more and 12 μm or less.

The power at the time of output of the laser light may be set within a range in which the resin composition (resin particles) is sufficiently melt-bonded at the scanning speed of the laser light described later. Specifically, it can be 5.0 W or more and 60 W or less. From the viewpoint of lowering the energy of the laser beam, lowering the manufacturing cost, and simplifying the configuration of the manufacturing apparatus, the power at the time of outputting the laser beam is preferably 30 W or less, and 20 W or less. It is more preferable to have.

The scanning speed of the laser beam may be set within a range that does not increase the manufacturing cost and does not excessively complicate the device configuration. Specifically, it is preferably 1 m / sec or more and 10 m / sec or less, more preferably 2 m / sec or more and 8 m / sec or less, and further preferably 3 m / sec or more and 7 m / sec or less.
The beam diameter of the laser beam can be appropriately set according to the accuracy of the three-dimensional model to be manufactured.

-Repeat of steps (1) and (2) When manufacturing a three-dimensional model, the above steps (1) and (2) are repeated any number of times. As a result, the modeled object layers are laminated to obtain a desired three-dimensional modeled object.

-Preheating step As described above, in the method for producing a three-dimensional model by the powder bed bond melting method, a step of preheating the resin composition may be performed. The preheating of the resin composition may be performed after the thin layer formation (step (1)) or before the thin layer formation (step (1)). Moreover, you may do both of these.

The preheating temperature is set to a temperature lower than the melting temperature of the thermoplastic resin so that the resin compositions do not melt and bond with each other. The preheating temperature is appropriately selected according to the melting temperature of the thermoplastic resin, and can be, for example, 50 ° C. or higher and 300 ° C. or lower, more preferably 100 ° C. or higher and 230 ° C. or lower, and 150 ° C. or higher and 190 ° C. or lower. The following is more preferable.

At this time, the heating time is preferably 1 to 30 seconds, more preferably 5 to 20 seconds. By preheating at the above temperature for the above time, the time until the resin composition (resin particles) melts during laser energy irradiation can be shortened, and a three-dimensional model can be manufactured with a small amount of laser energy. It will be possible.

-Others From the viewpoint of preventing the strength of the three-dimensional model from being lowered due to oxidation of the resin composition during melt bonding, it is preferable to perform at least step (2) under reduced pressure or in an inert gas atmosphere. .. The pressure at the time of depressurization is preferably ^10-2 Pa or less, and more preferably 10 ^-3 Pa or less. Examples of the inert gas that can be used at this time include nitrogen gas and noble gas. Of these inert gases, nitrogen (N ₂ ) gas, helium (He) gas or argon (Ar) gas is preferable from the viewpoint of easy availability. From the viewpoint of simplifying the manufacturing process, it is preferable to perform both the step (1) and the step (2) under reduced pressure or in an atmosphere of an inert gas.

2-2. Method for producing a three-dimensional model by the MJF method The method for producing a three-dimensional model of the present embodiment includes (1) a thin layer forming step for forming a thin layer containing the above-mentioned resin composition, and (2) an energy absorber. A fluid coating step of applying a binding fluid and a peeling fluid having less energy absorption than the binding fluid to adjacent regions of the thin layer, and (3) irradiating the thin layer after the fluid coating step with energy to bond. It comprises an energy irradiation step of melting the thermoplastic resin in the application area of the fluid to form a model layer. The method for producing the three-dimensional model may include other steps, if necessary, and may include, for example, a step of preheating the resin composition.

(1) Thin layer forming step In this step, a thin layer mainly containing the above-mentioned resin composition is formed. The method for forming the thin layer is not particularly limited as long as a layer having a desired thickness can be formed. For example, this step can be a step of laying the resin composition supplied from the resin composition supply unit of the three-dimensional modeling apparatus flat on the modeling stage by a recoater. The thin layer may be formed directly on the build stage or may be formed so as to be in contact with the powder material already spread or the already formed build layer.

The thickness of the thin layer is the same as the thickness of the desired model layer. The thickness of the thin layer can be arbitrarily set according to the accuracy of the three-dimensional model to be manufactured, but is usually 0.01 mm or more and 0.30 mm or less. By setting the thickness of the thin layer to 0.01 mm or more, the already produced modeled object layer is melted by energy irradiation for forming a new modeled object layer (energy irradiation in the energy irradiation step described later). Can be prevented. Further, when the thickness of the thin layer is 0.01 mm or more, it becomes easy to spread the powder material uniformly. Further, by setting the thickness of the thin layer to 0.30 mm or less, it becomes possible to conduct energy (for example, infrared light) to the lower part of the thin layer in the energy irradiation step described later. This makes it possible to melt the thermoplastic resin in a desired region (region to which the binding fluid is applied) over the entire thickness direction. From the above viewpoint, the thickness of the thin layer is more preferably 0.01 mm or more and 0.20 mm or less.

(2) Fluid application step In this step, a binding fluid containing an energy absorber and a peeling fluid having less energy absorption than the binding fluid are applied to the regions adjacent to each other of the thin layers formed in the thin layer forming step. Apply. Specifically, the binding fluid is selectively applied to the position where the modeled object layer should be formed, and the peeling fluid is applied to the region where the modeled object layer is not formed. By applying the peeling fluid adjacent to the periphery of the region to which the bonding fluid is applied, it becomes difficult for the resin particles to be melt-bonded in the region to which the peeling fluid is applied. Either the binding fluid or the peeling fluid may be applied first, but from the viewpoint of the dimensional accuracy of the obtained three-dimensional model, it is preferable to apply the binding fluid first.

The method of applying the binding fluid and the peeling fluid is not particularly limited, and for example, coating by a dispenser, coating by an inkjet method, spray coating, or the like can be performed, but the bonding fluid and the peeling fluid can be applied to a desired region at high speed. From the viewpoint that the above can be applied, it is preferable to apply at least one by an inkjet method, and it is more preferable to apply both by an inkjet method.

The coating amounts of the binding fluid and the peeling fluid are preferably 0.1 to 50 μL, and more preferably 0.2 to 40 μL, respectively, per 1 mm ³ of the thin layer. When the application amount of the binding fluid and the peeling fluid is within the above range, the powder material in the region forming the shaped object layer and the region not forming the shaped object layer is sufficiently impregnated with the binding fluid and the peeling fluid, respectively. It is possible to form a three-dimensional model with good dimensional accuracy.

The binding fluid applied in this step can be the same as the binding fluid used in the conventional MJF method, and can be, for example, a composition containing at least an energy absorber and a solvent. The binding fluid may contain a known dispersant or the like, if necessary.

The energy absorber is not particularly limited as long as it can absorb the energy irradiated in the energy irradiation step described later and efficiently raise the temperature of the region to which the binding fluid is applied. Specific examples of energy absorbers include carbon black, infrared absorbers such as ITO (indium tin oxide) and ATO (antimony tin oxide), cyanine pigments, phthalocyanine pigments mainly composed of aluminum and zinc, various naphthalocyanine compounds, and flat surfaces. Infrared absorbing dyes such as nickel dithiolene complex having a tetracoordinate structure, squalium dye, quinone compound, diinmonium compound, and azo compound are included. Among these, an infrared absorber is preferable, and carbon black is more preferable, from the viewpoint of versatility and the ability to efficiently increase the temperature of the region to which the binding fluid is applied.

The shape of the energy absorber is not particularly limited, but it is preferably in the form of particles. The average particle size thereof is preferably 0.1 to 1.0 μm, more preferably 0.1 to 0.5 μm. If the average particle size of the energy absorber is excessively large, it becomes difficult for the energy absorber to enter the gaps between the resin particles when the bonding fluid is applied onto the thin layer. On the other hand, when the average particle size of the energy absorber is 0.1 μm or more, heat can be efficiently transferred to the thermoplastic resin in the energy irradiation step described later, and the surrounding thermoplastic resin can be melted. Become.

The binding fluid preferably contains an energy absorber in an amount of 0.1 to 10.0% by mass, more preferably 1.0 to 5.0% by mass. When the amount of the energy absorber is 0.1% by mass or more, it is possible to sufficiently raise the temperature of the region to which the binding fluid is applied in the energy irradiation step described later. On the other hand, when the amount of the energy absorbent is 10.0% by mass or less, the energy absorbent is less likely to aggregate in the binding fluid, and the coating stability of the binding fluid is likely to be improved.

On the other hand, the solvent is not particularly limited as long as it can disperse the energy absorber and is difficult to dissolve the thermoplastic resin or the like in the resin composition, and can be, for example, water.

The binding fluid preferably contains the above solvent in an amount of 90.0 to 99.9% by mass, more preferably 95.0 to 99.0% by mass. When the amount of the solvent in the binding fluid is 90.0% by mass or more, the fluidity of the binding fluid becomes high, and it becomes easy to apply by, for example, an inkjet method.

The viscosity of the binding fluid is preferably 0.5 to 50.0 mPa · s, more preferably 1.0 to 20.0 mPa · s. When the viscosity of the binding fluid is 0.5 mPa · s or more, diffusion when the binding fluid is applied to the thin layer is likely to be suppressed. On the other hand, when the viscosity of the coupling fluid is 50.0 mPa · s or less, the coating stability of the coupling fluid tends to increase.

On the other hand, the peeling fluid applied in this step may be a fluid having relatively less energy absorption than the coupling fluid, and may be, for example, a fluid containing water as a main component.

The exfoliating fluid preferably contains 90% by mass or more of water, and more preferably 95% by mass or more. When the amount of water in the peeling fluid is 90% by mass or more, it becomes easy to apply by, for example, an inkjet method.

(3) Energy irradiation step In this step, energy is collectively irradiated to the thin layer after the fluid coating step, that is, the thin layer coated with the binding fluid and the peeling fluid. At this time, in the region where the binding fluid is applied, the energy absorber absorbs the energy, and the temperature of the region partially rises. Then, only the thermoplastic resin in the region is melted to form a modeled object layer.

The type of energy to be irradiated in this step is appropriately selected according to the type of energy absorber contained in the binding fluid. Specific examples of the energy include infrared light, white light and the like. Among these, from the viewpoint that the thermoplastic resin can be efficiently melted in the region coated with the bonding fluid, while the temperature of the thin layer does not easily rise in the region coated with the stripping fluid. Infrared light is preferable, light having a wavelength of 780 to 3000 nm is more preferable, and light having a wavelength of 800 to 2500 nm is more preferable.

The time for irradiating energy in this step is appropriately selected depending on the type of the thermoplastic resin contained in the powder material, but is usually preferably 5 to 60 seconds, preferably 10 to 30 seconds. More preferred. By setting the energy irradiation time to 5 seconds or more, it becomes possible to sufficiently melt the thermoplastic resin and combine them. On the other hand, if the time is 60 seconds or less, it becomes possible to efficiently manufacture a three-dimensional model.

-Preheating step Also in the MJF method, a step of preheating the resin composition may be performed. The preheating of the resin composition may be performed after the thin layer formation (step (1)) or before the thin layer formation (step (1)). Moreover, you may do both of these. By performing preheating, it is possible to reduce the amount of energy to be irradiated in the (3) energy irradiation step. Furthermore, it becomes possible to efficiently form a modeled object layer in a short time. The preheating temperature is preferably a temperature lower than the melting temperature of the thermoplastic resin and lower than the boiling point of the solvent contained in (2) the bonding fluid or the peeling fluid to be applied in the fluid coating step. Specifically, the temperature is preferably 50 ° C. to 5 ° C. lower than the melting point of the thermoplastic resin and the boiling point of the solvent contained in the bonding fluid or the peeling fluid, and is preferably 30 ° C. to 5 ° C. lower. More preferred. At this time, the heating time is preferably 1 to 60 seconds, more preferably 3 to 20 seconds. By setting the heating temperature and the heating time within the above ranges, the amount of energy irradiation in the (3) energy irradiation step can be reduced.

Hereinafter, specific examples of the present invention will be described. It should be noted that these examples do not limit the scope of the present invention.

[Example 1]
As a thermoplastic resin, polyamide 12 (PA12, manufactured by Daicel Evonik, Daiamide L1600 (“Diamid” is a registered trademark of the same company) was prepared. The thermoplastic resin was measured by a laser diffraction type particle size distribution equipped with a wet disperser. It was pulverized by a mechanical pulverization method until the average particle size measured by an apparatus (HELOS manufactured by SYMPATEC) reached a value of 50 μm.
Next, kaolin (ASPR400P manufactured by Hayashi Kasei Co., Ltd.) was pulverized with a free crusher (M-2 manufactured by Nara Machinery Co., Ltd.) to a thickness of 50 nm and a width of 0.5 μm. Then, the flat plate particles were mixed with the above resin particles by a Henschel mixer (manufactured by Nippon Coke Industries, Ltd.) to prepare a resin composition 1. The mass ratio of the thermoplastic resin to the flat particles was 85:15.

[Example 2]
The same resin as in Example 1 except that kaolin (ASPR400P manufactured by Hayashi Kasei Co., Ltd.) was pulverized with a free crusher (M-2 manufactured by Nara Machinery Co., Ltd.) to a thickness of 500 nm and a width of 0.5 μm. Composition 2 was prepared.

[Example 3]
Kaolin (ASPR400P manufactured by Hayashi Kasei Co., Ltd.) was pulverized with a bead mill (UAM015 manufactured by Hiroshima Metal & Machinery Co., Ltd.), and the resin composition was pulverized to a thickness of 50 nm and a width of 1 μm, as in Example 1. 3 was prepared.

[Example 4]
Kaolin (ASPR400P manufactured by Hayashi Kasei Co., Ltd.) was pulverized with a bead mill (UAM015 manufactured by Hiroshima Metal & Machinery Co., Ltd.), and the resin composition was pulverized to a thickness of 300 nm and a width of 5 μm, as in Example 1. 4 was prepared.

[Example 5]
Kaolin (ASPR400P manufactured by Hayashi Kasei Co., Ltd.) was pulverized with a bead mill (UAM015 manufactured by Hiroshima Metal & Machinery Co., Ltd.), and the resin composition was pulverized to a thickness of 500 nm and a width of 10 μm, as in Example 1. 5 was prepared.

[Example 6]
Same as Example 1 except that mica (manufactured by Yamaguchi Mica, A-11) was crushed as flat particles instead of kaolin (manufactured by Hayashi Kasei Co., Ltd., ASPR400P) and mica having a thickness of 300 nm and a width of 5 μm was used. The resin composition 6 was used.

[Example 7]
Resin composition 7 as in Example 1 except that talc (manufactured by Hayashi Kasei Co., Ltd., Micron White # 5000) was used instead of kaolin (manufactured by Hayashi Kasei Co., Ltd., Micron White # 5000) and talc having a thickness of 300 nm and a width of 5 μm was used. Got

[Example 8]
As the thermoplastic resin, polypropylene resin pellets (PM600A manufactured by SunAllomer Ltd.) were used, and the thermoplastic resin was pulverized with a freeze crusher until the average particle size became 50 μm. On the other hand, talc (micron white # 5000 manufactured by Hayashi Kasei Co., Ltd.) was pulverized in the same manner as in Example 1 until the thickness became 300 nm and the width became 5 μm, and these were mixed to obtain a resin composition 8. The mass ratio of the thermoplastic resin to the flat particles was 85:15.

[Example 9]
90 parts by mass of polypropylene resin pellets (SunAllomer, PM600A) and 10 parts by mass of talc (Micron White # 5000 (thickness 3000 nm, width 10 μm), manufactured by Hayashi Kasei), using a kneader (Xplore, MC15). Kneading was performed to prepare talc-containing polypropylene resin pellets. Then, the polypropylene resin pellets were pulverized with a freeze crusher until the average particle size became 50 μm. On the other hand, talc (micron white # 5000 manufactured by Hayashi Kasei Co., Ltd.) was pulverized in the same manner as in Example 1 until the thickness became 300 nm and the width became 5 μm, and these were mixed to obtain a resin composition 9. The mass ratio of the thermoplastic resin to the flat particles was 85:15.

[Comparative Example 1]
The same resin as in Example 1 except that kaolin (ASPR400P manufactured by Hayashi Kasei Co., Ltd.) was pulverized with a free crusher (M-2 manufactured by Nara Machinery Co., Ltd.) to a thickness of 10 nm and a width of 0.5 μm. The composition 10 was prepared.

[Comparative Example 2]
The same resin as in Example 1 except that kaolin (ASPR400P manufactured by Hayashi Kasei Co., Ltd.) was pulverized with a free crusher (M-2 manufactured by Nara Machinery Co., Ltd.) to a thickness of 550 nm and a width of 0.5 μm. The composition 11 was prepared.

[evaluation]
For the above-mentioned resin compositions 1 to 11, three-dimensional shaped objects were prepared by the following powder bed melt-bonding method, and the elasticity improvement rate, breaking elongation, and warpage were evaluated.
(1) Preparation of three-dimensional model The prepared resin composition is spread on a modeling stage installed on a hot plate to form a thin layer with a thickness of 0.1 mm, and preheating is performed by adjusting the temperature of the hot plate. Each was heated to a temperature of 150 ° C. This thin layer was irradiated with laser light in a range of 15 mm in length × 20 mm in width from a CO ₂ laser equipped with a galvanometer scanner for YAG wavelength under the following conditions to prepare a modeled object layer. The above steps were repeated until the height reached 55 mm, and laminated three-dimensional objects were manufactured.
[Laser light emission conditions]
Laser output: 12W
Wavelength of laser light: 10.6 μm
Beam diameter: 170 μm on the thin layer surface
[Laser light scanning conditions]
Scanning speed: 2000 mm / sec
Number of lines: 1 line

(2) Measurement of elastic modulus and elongation at break The obtained three-dimensional model was installed in a tensile tester (Tencilon RTC-1250, manufactured by A & D Co., Ltd.) in the vertical direction (of the model layer) at a speed of 1 mm / min. It was pulled in the direction perpendicular to the stacking direction) and the elastic modulus was measured. Further, the device was used to pull in the vertical direction (perpendicular to the stacking direction of the model layer) at a speed of 50 mm / min, and the elongation at break was measured. Then, the elastic modulus and the elongation at break were evaluated according to the following criteria, respectively. The blank is a three-dimensional model produced by using the same resin particles as in the examples or each comparative example except that the flat particles are not included.

(Elastic modulus)
⊚: The elastic modulus was improved by 30% or more as compared with the elastic modulus of the blank.
◯: The elastic modulus was improved by 10% or more as compared with the elastic modulus of the blank.
X: The elastic modulus did not improve with respect to the elastic modulus of the blank.

(Breaking elongation)
⊚: Breaking elongation was 50% or more ○: Breaking elongation was 10% or more and less than 50% ×: Breaking elongation was less than 10%

(3) Evaluation of modeling characteristics (heat warpage)
The vertical and horizontal dimensions of the obtained three-dimensional model were measured with a digital caliper (manufactured by Mitutoyo Co., Ltd., Super Caliper CD67-S PS / PM, "Super Caliper" is a registered trademark of the same company). By averaging the difference between the dimensions to be manufactured (length 15 mm x width 20 mm x height 55 mm) and the measured length and width dimensions, the dimensional accuracy (presence or absence of thermal warpage) of the three-dimensional model is evaluated based on the following criteria. did.
⊚: The average dimensional difference was less than 0.1 mm ◯: The average dimensional difference was 0.1 mm or more and less than 0.5 mm ×: The average dimensional difference was 0.5 mm or more

As shown in Table 1, even if the flat plate-like particles were attached around the resin particles, the elastic modulus of the obtained three-dimensional model could not be improved if the thickness was thin (the elastic modulus of the obtained three-dimensional model could not be improved). Comparative example 1). If the flat particles are too thin, it is considered that the addition effect is not sufficiently exhibited. On the other hand, when the plate-like particles were thick and approached a spherical shape, the elongation at break was low and thermal warpage was likely to occur (Comparative Example 2).

On the other hand, according to the resin composition containing the flat plate particles having a thickness of 50 nm or more and 500 nm or less on the outside of the resin particles, the elastic modulus, the elongation at break, and the warp were all evaluated well (Example 1). ~ 9). It is considered that the strength of the obtained three-dimensional model was increased by including the flat-plate particles having the above thickness. Further, since the particles are flat, the flat particles are easily arranged in the elongation direction of the resin in the three-dimensional model when tensile strength is applied to the three-dimensional model, and the flat particles are between the resin and the flat particles. It is presumed that it was difficult to create a gap. Furthermore, since the flat plate particles are attached around the resin particles, the thermal conductivity between the resin particles and the space between the resin particles and the (already formed) modeled object layer are observed during the production of the three-dimensional object. It is presumed that the thermal conductivity in the above was improved and thermal warpage was less likely to occur.

Further, in Examples 8 and 9 using polypropylene and talc (plate-like particles) having similar crystal structures, the elongation at break was good and the thermal warpage was less likely to occur. In the resin composition, when the resin particles are melted during the production of the three-dimensional model, the flat plate-like particles become nucleating agents and are recrystallized. As a result, a large number of crystals having a uniform structure are contained in the three-dimensional model, and it is easy for heat to be transferred uniformly and a load to be applied uniformly, and it is presumed that these results are good.

This application claims priority under Japanese Patent Application No. 2017-213710 filed on November 6, 2017. All the contents described in the application specification are incorporated in the application specification.

According to the resin composition according to the present invention, it is possible to accurately form a three-dimensional model by either the powder bed melt-bonding method or the MJF method. Therefore, the present invention is considered to contribute to the further spread of the three-dimensional modeling method.

Claims (11)

A resin composition used in a three-dimensional modeling method for forming a three-dimensional model by repeatedly forming a thin layer containing a particulate resin composition and repeatedly irradiating the thin layer with energy.
It contains particles containing a thermoplastic resin and flat particles having a thickness of 50 to 500 nm and having a maximum diameter ratio of 5 to 20 with respect to the thickness .
The flat particles are layered clay minerals.
The amount of the flat particle is 10 to 40 parts by mass with respect to 100 parts by mass of the resin composition.
Resin composition. The flat particle has a maximum diameter of 1 to 10 μm.
The resin composition according to claim 1. The tabular particles are attached around the particles containing the thermoplastic resin.
The resin composition according to claim 1 or 2. The tabular particles are contained inside the particles containing the thermoplastic resin.
The resin composition according to any one of claims 1 to 3. The tabular particles are silicate compounds containing magnesium.
The resin composition according to any one of claims 1 to 4. The tabular particles are talc.
The resin composition according to any one of claims 1 to 5. The thermoplastic resin is a crystalline resin.
The resin composition according to any one of claims 1 to 6. The thermoplastic resin is an olefin resin.
The resin composition according to any one of claims 1 to 7. A cured product of the resin composition according to any one of claims 1 to 8.
Three-dimensional model. A thin layer forming step for forming a thin layer containing the resin composition according to any one of claims 1 to 8.
A laser light irradiation step of selectively irradiating the thin layer with a laser beam to form a molded product layer in which a plurality of the resin compositions are melt-bonded.
Including
The thin layer forming step and the laser light irradiation step are repeated a plurality of times, and the shaped object layer is laminated to form a three-dimensional shaped object.
Manufacturing method for three-dimensional objects. A thin layer forming step for forming a thin layer containing the resin composition according to any one of claims 1 to 8.
A fluid coating step of applying a binding fluid containing an energy absorber and a peeling fluid having less energy absorption than the binding fluid to adjacent regions of the thin layer.
An energy irradiation step of irradiating the thin layer after the fluid coating step with energy and melting the thermoplastic resin in the region to which the bonding fluid is applied to form a model layer.
Including
The thin layer forming step, the fluid coating step, and the energy irradiation step are repeated a plurality of times, and the shaped object layer is laminated to form a three-dimensional shaped object.
Manufacturing method for three-dimensional objects.