ES2874473T3 - Resin powder for solid freeform fabrication and device for solid freeform fabrication object - Google Patents

Abstract

A resin powder for the manufacture of a solid free form, comprising: resin particles having a significantly columnar-like shape, including resin particles having a concave portion on a circumferential lateral surface, wherein the resin powder has an angle of repose, measured according to the description, of 55 degrees or less.

Description

DESCRIPTION

Resin powder for solid freeform fabrication and device for solid freeform fabrication object

Background

Technical field

The present invention relates to a resin powder for the manufacture of a solid free form and a device for the manufacture of a solid free form object of manufacture.

Description of Related Art

Additive powder manufacturing is a layer-by-layer solidification manufacturing method by applying a laser or binder to a powdery material.

The method of applying a laser is called powder bed fusion (PBF) which includes known methods such as a selective laser sintering (SLS) method of forming an object. of solid freeform fabrication with selective irradiation of laser beams and a selective mask sintering (SMS) method of applying laser beams in a flat shape using a mask. The method of using a binder includes, for example, binder jet, including discharging ink containing a binder resin by ink jet, and so on. to form a solid freeform crafting object.

Of these, a device employing the PBF method selectively irradiates a thin layer of metal, ceramic or resin powder with laser beams to melt the powder and cause it to adhere to each other to form a layer and repeats this operation to laminate sequentially. the layer to get a solid freeform crafting object (3D object).

Currently, polyamide resins are commonly used in the PBF method. In particular, polyamide 12 is preferably used because it has a relatively low melting point among polyamides, undergoes less heat shrinkage, and has poor water absorbency.

In addition, the demand for manufacturing not only prototypes, but also products, has been increasing, so that research and development and the launch of various types of resins are planned.

WO 2009/135521 A2 discloses fibers for producing a molded body consisting of interconnected layers according to a solid free form manufacturing method. The fiber particles are obtained by cutting fibers having a diameter preferably in the range of 0.01 to 0.1 µm, to give particles having a diameter-length ratio of preferably 0.5 to 3. The fibers are made from thermoplastic materials such as polypropylene (PP) or polyethylene terephthalate (PET). The fibers can be circular, elliptical or irregular in shape.

Summary

In accordance with the present invention, there is provided an improved resin powder for the manufacture of a solid free form that includes resin particles having a significantly columnar-like shape including resin particles having a concave portion on the circumferential side surface, wherein the resin powder has an angle of repose of 55 degrees or less.

Brief description of the various views of the drawings

Various other objects, features, and consequent advantages of the present invention will be more fully appreciated as the same is better understood from the detailed description when considered in connection with the accompanying drawings, in which similar reference characters designate similar corresponding parts in all of them and where:

FIG. 1A is a diagram illustrating a schematic perspective view of an example of a resin particle having a significantly columnar-like shape having a concave portion on its circumferential side surface;

FIG. 1B is a diagram illustrating a side view of the resin particle having a significantly columnar-like shape illustrated in FIG. 1A; and

FIG. 2A is a diagram illustrating a schematic perspective view of an example of the resin particle having a significantly columnar-like shape;

FIG. 2B is a diagram illustrating a side view of the resin particle having a shape significantly columnar type illustrated in FIG. 2A;

FIG. 2C is a diagram illustrating a side view of an example of the resin particle having a significantly columnar-like shape having no apex at the ends;

FIG. 3 is a schematic diagram illustrating an example of the method of measuring an angle of repose; FIG. 4 is a schematic diagram illustrating an example of the device for making a solid free-form object of manufacture for use in the method of making a solid free-form object; and

FIG. 5A is a schematic diagram illustrating an example of the process of forming a layer of powder having a smooth surface;

FIG. 5B is a schematic diagram illustrating an example of the process of forming a layer of powder having a smooth surface;

FIG. 5C is a schematic diagram illustrating an example of the dripping process of a liquid material for the manufacture of a solid free form;

FIG. 5D is a schematic diagram illustrating an example of the process of forming a new layer of resin powder in a powder storage tank for the manufacture of a solid free form;

FIG. 5E is a schematic diagram illustrating an example of the process of forming a new layer of resin powder in a powder storage tank for the manufacture of a solid free form; and FIG. 5F is a schematic diagram illustrating an example of the process of dripping a liquid material to make a solid free form again.

The accompanying drawings are intended to represent exemplary embodiments of the present invention and should not be construed as limiting the scope thereof. The accompanying drawings are not to be considered drawn to scale unless explicitly stated. Likewise, identical or similar reference numerals designate identical or similar components throughout the various views.

Description of the achievements

In describing the embodiments illustrated in the drawings, specific terminology is used for the sake of clarity. However, the disclosure of the present specification is not intended to be limited to the specific terminology so selected and each specific element is to be understood to include all technical equivalents that serve a similar function, operate in a similar manner, and achieve a similar result.

As used herein, the singular forms "a", "an", "the", and "the" are also intended to include the plural forms, unless the context clearly indicates otherwise.

Moreover, imaging, registration, printing, modeling, etc. in the present invention they have the same meaning, unless otherwise specified.

Resin powder for the manufacture of a solid free form

The resin powder for the manufacture of a solid free form (hereinafter referred to as resin powder) of the present invention contains resin particles having a significantly columnar-like shape, including resin particles having a portion concave on its circumferential side surface, where the resin powder has an angle of repose of 55 degrees or less, and other optional components.

The resin powder for making a solid free form of the present invention was manufactured with the knowledge that normally, without adding a flow agent, the resin powder for making a solid free form would impart poor smoothness to the surface of the powder during coating a powder layer and degraded the surface property of an obtained solid free-form fabrication object.

It is preferable that the resin powder for making a solid free form of the present invention does not contain significantly any inorganic particles. "Does not contain significantly any inorganic particles" means that the amount of inorganic particles is less than 0.05 mass percent and preferably 0 mass percent (detection limit or less) of the total amount of the powder of resin for the manufacture of a solid free form.

Resin particle having a significantly columnar-like shape

The resin particle having a significantly columnar-like shape has a concave portion formed along the circumferential direction at the significantly central site of the circumferential side surface.

The resin particle having a significantly columnar-like shape includes a base and a top surface with a columnar-like shape or a tubular shape. The shape of the base or top surface has no particular limit and can be conveniently selected to suit a particular application. For example, a resin particle having a significantly cylindrical shape (columnar-type significantly circular shape) or a column-type polygonal shape is allowed. The resin particle having a significantly cylindrical shape includes an article having a circular or ellipsoidal base and a surface top, and the resin particle having a column-like polygonal shape includes an article having, for example, a square or hexagonal base and a top surface. As long as the portion between a base and an upper surface has a columnar-like area or a tubular area, the shape of the base and the shape of the upper surface are not necessarily the same. Furthermore, resin particles having a straight solid element in which the columnar portion (lateral surface) is orthogonal to the base or the upper surface or an inclined solid element in which the columnar portion (lateral surface) is not allowed are allowed. it is orthogonal to the base or top surface.

The resin powder for making a solid free form contains the resin particle having a significantly columnar-like shape and having a concave portion formed along the circumferential direction at the significantly central site of the circumferential side surface. Therefore, the powder has a small angle of repose and a good smoothness of the powder surface during coating. As a result, the surface property of an obtained solid free-form fabrication object can be further enhanced.

As the resin particle having a significantly columnar-like shape, in terms of productivity and manufacturing stability, an article close to a straight solid resin particle having a base and a top surface significantly parallel to each other is preferable. The shape of the resin particle having a significantly columnar-like shape can be observed and determined by, for example, a scanning electron microscope (S4200, manufactured by Hitachi Ltd), a wet process particle size and shape analyzer. (FPIA-3000, manufactured by Sysmex Corporation), etc.

The concave portion formed along the circumferential direction at the significantly central site of the circumferential lateral surface on the resin particle, having a significantly columnar-like shape and having a concave portion formed along the circumferential direction at the significantly central site of the circumferential side surface represents a portion having a smaller diameter than those of the base and top surface as illustrated in FIGS. 1A and 1B. FIG. 1A is a diagram illustrating a schematic perspective view of an example of the resin particle having a significantly columnar-like shape and having a concave portion formed along the circumferential direction at the significantly central site of the lateral surface. circumferential. FIG. 1B is a diagram illustrating a side view of the resin particle having a significantly columnar-like shape illustrated in FIG. 1A. A concave portion 100 is formed at least partially at the significantly central site of the circumferential lateral surface of the resin particle having a significantly columnar-like shape and preferably on the entire circumferential lateral surface. The significantly central site is allowed to be anywhere between the base and the upper surface and the concave portion 100 may be in contact with the upper surface of the base.

In addition, the concave portion 100 can form a constriction shape smoothly and continuously connected to the top surface and the base. The resin particle having a significantly columnar-like shape has the concave portion 100 formed along the circumferential direction, at the significantly central site of the circumferential side surface. Therefore, the resin particle has a smaller contact area with other particles, so that the strength of the particles is lowered, thereby improving the flowability of the resin particle. Furthermore, to further decrease the strength of the particles and improve flowability, the particle preferably has no tips at the ends.

As the resin powder for making a solid free form, it is preferable that it only contains the resin powder having a significantly columnar-like shape. However, the resin powder may contain other optional particles and other optional components.

Resin particle that is significantly cylindrical in shape

There is no specific limit to the significantly cylindrical shape. It can be conveniently selected to suit a particular application. For example, resin particles having a true cylindrical shape and resin particles having a cylindrical-like shape are preferable. Of these, resin particles having a shape closer to the true cylindrical shape are preferable. In addition, the significantly cylindrical (significantly circular) shape of the resin particle having a significantly cylindrical shape has a major axis to minor axis ratio of 1 to 10 and also includes an article having a partially chipped portion.

The resin particle having a significantly cylindrical shape preferably has significantly circular planes facing each other. The size of the circles facing each other may not be identical. However, the ratio of the diameter of the large circle to the small circle is preferably 1.5 or less and more preferably 1.1 or less, to increase the density.

The long side of the resin particle base having a significantly cylindrical shape has no particular limit and can be conveniently selected to suit a particular application. For example, it is preferably 5 to 200 pm. The long side of the base in the resin particle that has a significantly cylindrical shape means the diameter of the base. When the circular portion of the resin particle having a significantly cylindrical shape is an ellipse, the long side means the major axis. Height (length between the base and top surface) of the significantly cylindrical shape has no particular limit and can be conveniently selected to suit a particular application. For example, the height is preferably 5 to 200 pm. When the long side of the base is within the range, the flying of the resin powder that occurs during the formation of a powder layer can be reduced. As a result, the surface of the powder layer becomes smooth. In addition, the gaps between the resin powder can be reduced, thereby further enhancing the surface property and dimensional accuracy of a solid free-form fabrication object.

The resin particle may have a long base side and a height of less than 5 pm or greater than 200 pm. However, the content ratio of said resin particles is preferably lower. To be more specific, the proportion of the particles having a long side of the base and a height of 5 to 200 pm is preferably 50 percent or more and more preferably 75 percent or more with respect to all the particles.

It is preferable that the long side of the base and the height in the resin particle having a significantly cylindrical shape are closer to each other. For example, the ratio of the height to the long side of the resin particle base is preferably 0.5 to 2.0, and more preferably 0.7 to 1.5. In the above-specified range of the ratio of the height to the long side of the base of the resin particle, when a layer of a resin powder is formed for the manufacture of a solid free form during the manufacture of a free form solid, there are fewer voids and the resin powder for making a solid free form tends to be densely packed. This is effective in enhancing the strength and dimensional accuracy of an obtained solid freeform fabrication object.

The resin particle having a significantly columnar-like shape has a columnar-like shape having a base and a top surface. Preferable shapes do not have any tips at the ends. The tip means an angled portion that exists in the form of a columnar type. For example, FIG. 2A is a diagram illustrating a schematic perspective view of an example of the resin particle having a significantly columnar-like shape. FIG. 2B is a side view of the resin particle having a significantly columnar-like shape illustrated in FIG. 2A. In this case, the columnar type shape has a rectangular shape with four angled portions, that is, tips (apices). FIG. 2C is a diagram illustrating an example of a shape without such tips. It can be checked whether a resin particle having a significantly columnar-like shape has a tip by a projected image of the lateral surface of the resin particle. For example, the lateral surface of a resin particle having a significantly columnar-like shape is observed by a scanning electron microscope (S4200, manufactured by Hitachi Ltd), etc. to get a two-dimensional image of it. In this case, the projected image has four sides. When the portion formed by two adjacent sides is defined as a terminal part, if the terminal part is formed by only two adjacent straight lines, an angle is formed so that the particle has a point. If the terminal part is arched as illustrated in FIG. 2C, no point is formed.

Such a resin particle having a significantly columnar-like shape has a smaller angle of repose, enhances flowability, and further improves the smoothness of the powder surface of a solid free-form fabrication object. That is, this is extremely suitable for improving the surface property of a solid free-form fabricated object.

It is more preferable that, as the resin powder for the manufacture of a solid free form, the proportion of the resin particle having a significantly columnar-like shape and having a concave portion formed along the circumferential direction at the site significantly central of the circumferential lateral surface is high. Specifically, the proportion of the resin particle having a significantly columnar-like shape and having a concave portion formed along the circumferential direction at the significantly central site of the circumferential lateral surface with respect to the entire resin particle that has a significantly columnar-like shape, it is preferably 50 percent or more, more preferably 75 percent or more, and particularly preferably 90 percent or more. At the rate of 50 percent or more, the flowability of the resin powder for making a solid free form is enhanced so that without a flow agent, the smoothness of the surface of the powder during coating becomes excellent and the property of the surface of a solid freeform fabrication object can be improved.

It can be determined whether the resin particle having a significantly columnar-like shape has a concave portion formed along the circumferential direction at the significantly central site of the circumferential lateral surface, for example, as described above, by observation of the resin powder for the manufacture of a solid free form with a scanning electron microscope (S4200, manufactured by Hitachi Ltd.), etc. to obtain two-dimensional images and calculate the proportion of the particle having a concave portion formed along the circumferential direction at the significantly central site of the circumferential lateral surface with respect to the entire resin particle having a significantly columnar-like shape from the two-dimensional images. For example, the two-dimensional images of 10 fields of view are obtained by the method described above to obtain the proportion of the resin particle having a significantly columnar-like shape and having a concave portion formed along the circumferential direction in the significantly central site of the circumferential lateral surface with respect to the entire resin particle having a significantly columnar-like shape, followed by an average for its determination.

The resin particle having a significantly columnar-like shape and having a concave portion formed along the circumferential direction at the significantly central site of the circumferential lateral surface does not necessarily have significantly cylindrical shapes or net column-like polygonal shapes, Rather, it may include a shape having an elongated end portion, a flattened shape, or a twisted or curved shape.

To change the resin particle, which has a significantly columnar-like shape in the resin powder for making a solid free form, into the resin particle which has a significantly columnar-like shape and has a concave portion formed to Along the circumferential direction at the significantly central site of the circumferential lateral surface, any method capable of applying a physical force to the resin particle having a significantly columnar-like shape can be applied. For example, it is possible to use a known processing device using high-speed rotary or high-speed impact mechanical pulverization or a ball mill.

Angle of repose

The angle of repose of the resin powder for making a solid free form is 55 degrees or less. At an angle of repose of 55 degrees or less, the flowability of the resin powder for making a solid free form can be ensured, and the smoothness of the surface of the powder during coating can be enhanced.

The angle of repose is, as illustrated in FIG. 3, an angle 13 formed between the ground surface and the slope of a mountain that forms a resin powder 12 'for the manufacture of a solid free form on a base 14 when a resin powder 12 for the manufacture of a free form Solid sieved through a sieve 10 falls freely from a funnel 11 to the base 14. Angle of repose is a flow index of a resin powder for the manufacture of a solid free form and a smaller angle of repose indicates greater flowability. The powder in a device for the manufacture of a solid free form is smoothed by a rotating roller to form additive layers. Although resin powder having good flowability can form a smooth surface, resin powder having poor flowability forms a rough surface on the layers. This has an adverse effect on the surface texture of a final solid free-form fabricated object, so that the surface property thereof is deteriorated.

The angle of repose can be measured, as illustrated in FIG. 3, measuring angle 13 using sieve 10 (based on JIS Z8801-1-2000 format, 125 pm aperture diameter) and an apparent specific weight measuring device (Z-2504, manufactured by "Kuramochi Kagaku Kikai Seisakusho ") which includes the funnel 11 and the base 14. The sieve 10 is arranged above the specific gravity measuring device and the powder to be measured is passed through, and the powder accumulates on the platform 14. As a diameter of Apparent specific gravity, an article is used that fits a 2.5 mm opening diameter of the funnel 11, and the base 14 having a columnar-like shape having a diameter of 30 mm is arranged below the funnel 11. The resin powder 12 for the manufacture of a solid free form is loaded into the sieve 10 from above and passed through the funnel 11 and forms a mountain of the resin powder 12 'for the manufacture of a solid free form on the base 14. The resin powder 12 for the manufacture of a form l The free solid is charged in an amount such that at least the resin powder 12 'for the manufacture of a solid free form is poured onto the base 14 and the shape of a cone can be seen from the side. The angle of repose is measured by capturing images using a camera. The camera is positioned 60mm from the base 14 (from the lens) and at the same height as the top surface of the base 14 (based on the height of the lens). The lateral surface of the mountain is then recorded by the camera. The angle formed by the surface of the base and the slope of the mountain is the angle of repose. This angle is calculated from the image obtained using trigonometry. The measurement is performed twice and the average is determined as the angle of repose.

Average Circularity

The average circularity of the resin powder for making a solid free form is preferably 0.80 or higher, more preferably 0.83 or higher, and further preferably 0.85 or higher in the particle size range of 0. , 5 to 200 pm. The upper limit of the average circularity is preferably 1.0 or less and more preferably 0.98 or less. Average circularity is an index of the degree of circularity and average circularity of 1 means a true circle. To determine the average circularity, the circularity is first obtained by the following relation 1, where S represents an area (number of pixels) and L represents a perimeter. The arithmetic mean of it is obtained as the average circularity.

Circularity = 4nS / L2 Ratio 1

Average circularity can be easily obtained by, for example, measurement-based digitization using a wet process flow type particle size and shape analyzer (FPIA-3000, manufactured by Sysmex Corporation). This wet process flow type particle size and shape analyzer images high speed particles in a liquid suspension flowing in a glass cell using a charge coupled device (CCD). ) and analyzes the images of individual particles in real time. This device, which is capable of taking images of said particles and analyzing the images, is suitable for obtaining the average circularity. The number of measurement counts of the particles has no particular limit and is preferably 1,000 or more, and more preferably 3,000 or more.

50 percent cumulative volume particle diameter

The thickness of the powder layer in a solid freeform manufacturing device employing additive powder manufacturing is preferably about 5 to about 500 µm and more preferably about 50 to about 200 µm.

The 50 percent cumulative volume particle diameter of the resin powder for making a solid free form is preferably 5 to 200 µm and more preferably 20 to 150 µm in terms of dimensional stability.

Within the range specified above for the 50 percent cumulative volume particle diameter (D50), the flight of the resin powder that occurs during the formation of a powder layer can be reduced. As a result, the surface of the powder layer becomes smooth. Furthermore, the voids between the resin powder can be reduced, thereby further enhancing the surface property of a solid free-form fabrication object.

The 50 percent cumulative volume particle diameter can be measured by, for example, a wet process flow type particle size and shape analyzer (FPIA-3000, manufactured by Sysmex Corporation) or a measuring device. particle size distribution measurement (microtrac MT3300 EXII, manufactured by MicrotracBEL Corp).

The proportion of the resin particle having a significantly columnar-like shape is preferably 50 percent or more, more preferably 75 percent or more, and 90 percent or more with respect to the total content of the resin powder for the making a solid free form. When the ratio is 50 percent or more, the packing density can be significantly increased, which is extremely effective in enhancing the dimensional accuracy and strength of an obtained solid free-form fabrication object. The proportion of the resin particle having a significantly columnar-like shape can be obtained, for example, by collecting resin powder for the manufacture of a solid free form, observing it with the scanning electron microscope (SEM) and counting the number of the resin particle having a significantly columnar-like shape and having a long base side and a height of 5 to 200 pm with respect to the number of all particles in the obtained SEM images.

Fluidizer

The flow agent partially or fully covers the surface of the resin powder for making a solid free form to improve the flowability of the resin powder for making a solid free form. Such a flow agent coats the surface of the resin powder to take effect. Some of them may be embedded in the resin powder to make a solid free form.

An example of the fluidizer is an inorganic particle.

The inorganic particle has no specific limitation and is conveniently selected to suit a particular application. For example, titania, zinc oxide, alumina, silica, and hydroxyapatite can be used.

The volume average particle diameter of the inorganic particle has no particular limit and can be conveniently selected to suit a particular application. For example, the volume average particle diameter is preferably less than 10 pm. The volume average particle diameter can be measured using, for example, a particle size analyzer (FPIA-3000, manufactured by Sysmex Corporation).

The proportion of the inorganic particle as flow agent is preferably less than 0.05 mass percent, more preferably less than 0.03 mass percent, and in particular preferably 0 mass percent (detection limit or lower). with respect to the total mass of the resin powder for the manufacture of a solid free form. When the proportion is less than 0.05 mass percent, the fluidizer does not decompose during manufacturing, so that it can be prevented from remaining in a solid free-form object of manufacture as an impurity, thereby preventing deterioration of the strength and purity of a solid freeform crafting object.

As the resin particle having a significantly columnar-like shape of the resin powder for making a solid free form, articles close to monodispersion formed as a solid are preferable. collective entity having a uniform height without deviation in shape and size. Due to this, the dimensional accuracy and strength of a solid free-form fabrication object can be further improved.

Specifically, the ratio of the particle diameter (Mv / Mn) of the volume average particle diameter (Mv) of the resin powder for the manufacture of a solid free form to the number average particle diameter (Mn) of the resin powder. resin for the manufacture of a solid free form is preferably 2.00 or less, more preferably 1.5 or less, and particularly preferably 1.2 or less.

The volume average particle diameter Mv of the resin powder for the manufacture of a solid free form is preferably 5 to 200 pm and more preferably 20 to 100 pm.

The number average particle diameter Mn of the resin powder for making a solid free form is preferably 2.5 to 200 µm and more preferably 10 to 100 µm.

Volume average particle diameter (Mv) and number average particle diameter (Mn) can be measured using a particle size distribution measuring instrument (Microtrac MT3300EXII, manufactured by MicrotracBEL Corp.).

Specific weight

The specific gravity of the resin powder for the manufacture of a solid free form is preferably 0.8 or more. When the specific gravity is 0.8 or more, it is possible to avoid secondary agglomeration of the particles during coating. Instead, the specific gravity is preferably 3.0 or less to meet the needs for light weight as a metal substitute. The specific gravity can be obtained by measuring the actual specific gravity. The actual specific gravity is obtained by measuring the density of a sample by measuring the mass of the sample from the volume of the sample. The volume is obtained by changing the volume and pressure of the gas (He gas) at a constant temperature using a dry process pycnometer (AccuPyc 1330, manufactured by Shimadzu Corporation) using a gas phase replacement method.

As the resin for use in the resin particle having a significantly columnar-like shaped powder, it is preferable to use a thermoplastic resin. Thermoplastic resin plasticizes and melts when heat is applied. Of the thermoplastic resin, a crystalline resin is preferable. Crystalline resin has a melting peak measured according to ISO 3146 (plastic transition temperature measurement method, JIS K7121 format).

The resin powder for the manufacture of a solid free form preferably has a melting point of 100 degrees C or higher, measured according to ISO 3146. It is preferable that the melting point of the resin powder for the manufacture of a solid free form measured according to ISO 3146 is 100 degrees C or higher, as it covers the temperature range of outdoor heat resistance of products, etc. The melting point can be measured according to ISO 3146 (plastic transition temperature measurement method, JIS K7121 format) using a differential scanning calorimeter (CDB). When there are a plurality of melting points, the melting point of the higher temperature side is used.

As the crystalline resin, a controlled glass thermoplastic resin is preferable. As a crystalline thermoplastic resin, for example, it can be obtained by a known method using external stimuli such as heat treatment, stretching, crystalline nuclear material and ultrasonic wave treatment. Crystalline thermoplastic resins having a controlled crystal size and crystal orientation are preferable in terms that the error that occurs during coating can be reduced.

The manufacturing method of the crystalline thermoplastic resin has no particular limit and can be conveniently selected to suit a particular application. For example, resin powder having a solid free-form fabrication is heated to the glass transition temperature or higher of each resin and subsequently annealed to increase crystallinity or the addition of a crystal nucleating agent to further increase crystallinity before annealing. Similarly, it is convenient to use an ultrasonic wave treatment or dissolve a resin in a solvent and evaporate it slowly to enhance crystallinity. On the other hand, a method of applying an external electric field to grow crystals and a processing method such as spraying and cutting a further stretched article are suitable for higher crystallization and orientation.

In annealing, for example, the resin is heated to a temperature 50 degrees higher than its glass transition temperature for three days and then slowly cooled to room temperature.

In the drawing, for example, using an extruder, the molten resin is stretched into fibrous form while stirring at temperatures above the melting point by 30 degrees C or more. To be specific, a molten resin is stretched from about 1/1 to about 1/10 to make a fiber. The cross-sectional shape of the fiber can be determined by the shape of the nozzle hole of the extruder. In the present invention, when the Resin particle having a significantly columnar-like shape is a resin particle having a significantly cylindrical shape, a circular-shaped nozzle hole is used. In the case of a column-type polygon shape, a nozzle orifice having a column-type polygonal shape is used. Productivity is expected to increase in proportion to the number of nozzles. Regarding stretching, the maximum stretching ratio can be changed depending on the viscosity of the resin and the melt.

In the application of ultrasonic waves, for example, the solvent glycerin (reagent grade, manufactured by Tokyo Chemical Industry Co. Ltd.) is added to a resin in an amount five times that of the resin, followed by heating to a temperature 20 degrees C higher than the melting point. Subsequently, ultrasonic waves are applied to them by an ultrasound generator (ultrasonicator UP200S, manufactured by Hielscher Ultrasonics GmbH) at a frequency of 24 KHz and an amplitude of 60 percent for two hours. The resulting product is then rinsed with an isopropanol solvent at room temperature, preferably followed by drying under vacuum.

As an external electric field application, for example, after heating a resin powder for the manufacture of a solid free form to the glass transition temperature or higher, an alternating electric field (500 Hz) of 600 V / cm is applied to the resin powder for one hour, followed by slow cooling.

In the powder bed fusion (PBF) method, a large temperature difference (temperature window) of about the crystalline layer change is preferable to avoid warping, thereby enhancing the manufacturing stability. To obtain this large temperature difference, it is preferable to use a resin powder for the manufacture of a solid free form that has a greater difference between the melting start temperature and the recrystallization temperature during cooling. The above-mentioned crystalline thermoplastic resin is particularly preferable.

The crystalline thermoplastic resin can be determined to meet at least one of the following relationships (conditions) (1) to (3).

(1): Tmf1> Tmf2, where Tmfq represents a melting start temperature of an endothermic peak when the resin powder is heated to a temperature 30 degrees C higher than the melting point of the resin powder, at a rate of increase temperature of 10 degrees C per minute, and Tmf2 represents a melting start temperature of an endothermic peak when the resin powder is heated to a temperature 30 degrees C higher than the melting point of the resin powder, at a rate temperature rise of 10 degrees C per minute, cooled to -30 degrees C or lower, at a rate of temperature rise of 10 degrees C per minute, and heated to temperature 30 degrees C higher than the set point melting at a rate of increase in temperature of 10 degrees C per minute for one second, and both Tmf1 and Tmf2 are measured by differential scanning calorimetry according to ISO 3146. The melting start temperature of peak end othermic represents a temperature at a point -15 mW lower than a straight line drawn parallel to the X axis from a site where the amount of heat becomes constant after the endotherm at the melting point ends on a lower temperature side.

(2): Cd1> Cd2, where Cd1 represents a crystallinity obtained from an amount of energy of the endothermic peak when the resin powder is heated to a temperature 30 degrees C higher than the melting point of the resin powder, at a speed increase in temperature of 10 degrees C per minute, and Cd2 represents a crystallinity obtained from an amount of energy of the endothermic peak when the resin powder is heated to a temperature 30 degrees C higher than the melting point of the resin powder , At a rate of temperature rise of 10 degrees C per minute, it is cooled to -30 degrees C or lower at a rate of temperature rise of 10 degrees C per minute, and heated to the temperature of 30 degrees C higher to the melting point at a rate of increase in temperature of 10 degrees C per minute for one second, and both Cd1 and Cd2 are measured by differential scanning calorimetry according to ISO 3146.

(3): C x 1> C x 2, where C x 1 represents a crystallinity of the resin powder obtained by measurement of X-ray diffraction and C x 2 represents a crystallinity obtained by measurement of X-ray diffraction when the powder of Resin is heated to a temperature 30 degrees C higher than its melting point, at a rate of increase in temperature of 10 degrees C per minute, cooled to -30 degrees C or lower, at a rate of decrease in temperature of 10 degrees C per minute, and subsequently heated to a temperature 30 degrees C above the melting point, at a rate of temperature rise of 10 degrees C per minute, under a nitrogen atmosphere.

In relationships (1) to (3), the properties of the identical resin powder for the manufacture of a solid free form are regulated from different points of view. Relations (1) to (3) are relevant to each other. Whether a resin powder for the manufacture of a solid free form of the present invention can be determined as a crystalline thermoplastic resin depends on whether the resin powder for the manufacture of a solid free form meets at least one of the relationships (1) to (3). Relationships (1) to (3) can be measured by the following method:

Method of measuring the melting start point of condition 1 according to differential scanning calorimetry measurement

The differential scanning calorimetry (CDB) melting onset temperature measurement method of the Condition (1) is based on the measurement method of ISO 3146 (plastic transition temperature measurement method, JIS K7121 format). A differential scanning calorimeter (for example, CDB-60A, manufactured by Shimadzu Corporation) is used to measure the melt onset temperature (Tmfl) of the endothermic peak when the resin powder is heated to the temperature 30 degrees C higher than melting point thereof, at a rate of increase in temperature of 10 degrees C per minute. Subsequently, the resin powder is cooled to -30 degrees C or lower, at a rate of decrease in temperature of 10 degrees C per minute, and heated to the temperature 30 degrees C higher than the melting point, at a rate of temperature increase of 10 degrees C per minute, to measure the melting start temperature (Tmf2) of the endothermic peak. The melting start temperature of the endothermic peak represents a temperature at a point -15 mW lower than a straight line drawn parallel to the X axis from a place where the amount of heat becomes constant, after the endotherm at the point of Melting ends on the lower temperature side.

Method of measuring the crystallinity of condition 2 according to the measurement by differential scanning calorimetry

The differential scanning calorimetry (CDB) crystallinity measurement method of condition (2) is based on the measurement method according to ISO 3146 (plastic transition temperature measurement method, JIS K7121 format). The amount of energy (amount of heat of fusion) of an endothermic peak is measured when it is heated to a temperature 30 degrees C higher than the melting point of the powdered resin, at a rate of increase in temperature of 10 degrees C per minute, to obtain the crystallinity (Cd1) from the amount of heat of fusion to the amount of heat of complete crystallization. Subsequently, the resin powder is cooled to -30 degrees C or lower, at a rate of temperature increase of 10 degrees C per minute, and heated to the temperature 30 degrees C higher than the melting point, at a rate of increase in temperature of 10 degrees C per minute, to measure the amount of energy of the endothermic peak so that the crystallinity (Cd2) can be obtained as the ratio of the amount of heat of fusion to the amount of heat of complete crystallization .

Method of measuring the crystallinity of condition 3 using an X-ray analyzer

The crystallinity of the resin powder from condition 3 is obtained by placing the resin powder on a glass plate to measure the crystallinity (C x 1) of the same by an X-ray analyzer (e.g. Discover 8, manufactured by Bruker) , which includes a two-dimensional detector in a range of 20 from 10 to 40 at room temperature. Then, in the CBD, under a nitrogen atmosphere, the resin is heated to 30 degrees C higher than its melting point at a rate of temperature increase of 10 degrees C per minute. The temperature is maintained for 10 minutes and the temperature of the sample (resin powder) returns to room temperature cooling to -30 degrees C at a rate of temperature increase of 10 degrees C per minute. The crystallinity (C x 2) can be measured as in the case of C x 1.

The thermoplastic resin for use in the resin powder for the manufacture of a solid free form has no particular limit and can be conveniently selected to suit a particular application. Concrete examples include, but are not limited to, polymers such as polyolefin, polyamide, polyester, polyether, polyaryl ketone, poly (phenylene sulfide), a liquid crystal polymer (LCP), polyacetal (POM), polyimide, and a fluorochemical resin. They can be used alone or in combination.

Specific examples of the polyolefin include, but are not limited to, polyethylene and polypropylene. They can be used alone or in combination.

Polyamide includes aromatic polyamides.

Specific examples include, but are not limited to, polyamide 410 (PA410), polyamide 6 (PA6), polyamide 66 (PA66), polyamide 610 (PA610), polyamide 612 (PA612), polyamide 11 (Pa 11), polyamide 12 (pA12) , semi-aromatic polyamide 4T (pA4T), polyamide MXD6 (Pa MXd 6), polyamide 6T (PA6T), polyamide 9T (PA9T) and polyamide 10T (PA10T). They can be used alone or in combination.

PA9T is also called polynonamethylene terephthalamide, consisting of a diamine having 9 carbon atoms and a monomer of terephthalic acid. In general, since the acidic side of carbon is an aromatic series, PA9T is called a semi-aromatic series. On the other hand, the polyamide in the present invention includes aramid, consisting of p-phenylenediamine, and a monomer of terephthalic acid as aromatic series, in which the diamine side is also aromatic.

Concrete examples of the polyester include, but are not limited to, polyethylene terephthalate (PET), polybutadiene terephthalate (PBT), and polylactic acid (PLA). To convey heat resistance, polyester is also conveniently used, which includes the aromatic series that partially includes terephthalic acid or isophthalic acid.

Specific examples of polyethers include, but are not limited to, polyether ether ketone (PEEK), polyether ketone (PEK), polyether ketone ketone (PEKK), polyaryl ether ketone (PAEK), polyether ether ketone ketone (PEEKK), and polyether ketone ether ketone ketone (PEKEKK) .

In addition to the polyether mentioned above, crystalline polymers are also suitable. Specific examples include, but are not limited to, polyacetal, polyimide, and polyether sulfone. It is also suitable to use polyamide that has two melting peaks, such as PA9T (it is necessary to increase the temperature of a resin to the second or higher melting peak to fully melt the resin).

The resin powder for the manufacture of a solid free form may include resin powder containing non-crystalline resin or an additive such as a flame retardant, a plasticizer, a stabilizer and a crystal nucleating agent other than the aforementioned thermoplastic resin. . They can be used alone or in combination. They can be mixed with the thermoplastic resin so that they are present in the resin powder for the manufacture of a solid free form or they can be attached to the surface thereof.

As the resin powder for the manufacture of a solid free form, it is possible to include, for example, a hardening agent. Hardening agents are added to primarily enhance strength and are contained as filler. As the curing agent, glass filler, glass beads, carbon fiber, aluminum balls and items listed in patent brochure WO 2008/057844 are used. They can be used alone or in combination and can be contained in a resin.

It is preferable to use suitably dried resin powder as the resin powder for the manufacture of a solid free form of the present invention. To dry the resin powder before use it is suitable to use a vacuum dryer or silica gel.

In addition, the resin powder for the manufacture of a solid free form can be used in the SLS method or in the SMS method and has properties that achieve a balance between parameters such as particle size, particle size distribution, heat transfer properties, melt viscosity, bulk density, flowability, melting temperature, and recrystallization temperature.

To facilitate the degree of laser sintering in the PBF method, the bulk density of the resin powder for making a solid free form is preferably large even though the density of the resin varies. For example, the packing density is preferably 0.35 g / ml or more, more preferably 0.40 g / ml or more, and particularly preferably 0.5 g / ml or more.

A solid free-form fabrication object formed by laser sintering using the resin powder for the fabrication of a solid free-form has excellent surface property and mechanical strength.

Furthermore, it is preferable that the solid free-form fabrications formed by laser sintering using the resin powder for the fabrication of a solid free-form are free from inappropriate process properties, such as warping, distortion, and fumes, caused by phase changes between sintering and cooling after sintering.

Method of manufacturing a resin particle having a significantly columnar-like shape and having a concave portion on the circumferential lateral surface

To obtain the resin particle having a significantly columnar-like shape, it is possible to use any method of manufacturing the resin particle having a significantly columnar-like shape. For example, the resin particle having a significantly columnar-like shape can be manufactured by a method of preparing fiber from a resin, followed by cutting to directly obtain a resin particle having a significantly cylindrical shape or a polygonal-like shape. column, a method of manufacturing a resin particle having a significantly columnar-like shape from a film shape, or a method of subjecting an obtained resin particle having a column-like polygonal shape to further processing for obtain a resin particle having a significantly cylindrical shape.

The way to prepare the fiber is, for example, using an extruder, drawing molten resin into a fibrous form during stirring at temperatures above the melting point by 30 degrees C or higher. It is preferable to stretch the molten resin at about 1/1 to about 1/10 to obtain the fiber. The shape of the resin particle base having a significantly columnar-like shape is determined by the shape of the nozzle orifice of an extruder. For example, if the shape of the base of a column, that is, the cross section of the fiber, is circular, a nozzle having a circular orifice is used. For a column-type polygonal shape, the nozzle orifice is selected according to the shape. It is preferable that the precision of the dimensions of a solid freeform fabrication object is higher. The circular shape of a flat portion has a radius of at least 10 percent or less. Also, it is preferable to have more nozzle holes to increase productivity.

For cutting, a cutting machine employing a guillotine method, in which both the upper and lower edges are knives, or a cutting machine employing a straw cutting method with an upper edge without a blade, can be used. but with a board arranged on the underside. It is also preferable to use a known device that directly cuts the fiber at 0.005 to 0.2mm or a CO ² laser to cut the fiber, etc.

Energy is applied to the staple fiber using a known device, such as a mechanical stirrer, which has a rotor that rotates at high speed by electricity, or a ball mill in which beads, etc. they are repeatedly collided with dust over a specified period of time. As a result, the terminal portion of the particle surface is processed and deformed so that a resin particle can be manufactured having a significantly columnar-like shape and having a concave portion formed along the circumferential direction in a significantly central site of the circumferential lateral surface.

Method of manufacturing a solid freeform crafting object and device for crafting a solid freeform crafting object

The method of manufacturing a solid free form manufacturing object includes a layering process to form a layer containing the resin powder for manufacturing a solid free form of the present invention and a powder adhesion process for causing the resin powder for making a solid free form to adhere to each other in a selected area of the layer, and repeating the layering process and the powder bonding process, and may further optionally include other processes.

The device for making a solid free-form fabricator includes a layer-forming device for forming a layer containing the resin powder for the solid free-form fabricator of the present invention and a powder adhering device for causing the resin powder for the manufacture of a solid free form to adhere to each other in a selected area of the layer, and may also optionally include other devices.

The method of manufacturing a solid freeform fabrication object can be conveniently executed by the device for fabricating a solid freeform fabrication object. As a resin powder for making a solid free form, it is possible to use the same resin powder for making a solid free form of the present invention.

The resin powder for making a solid free form can be used for any device for making a solid free form manufacturing object using a powder additive manufacturing method. The device for manufacturing a solid free-form manufacturing object employing a powder additive manufacturing method forms a powder layer, and subsequently makes the resin powder in a selected area adhere to each other with a different device depending on methods. For example, there is an electromagnetic device (irradiator for emitting electromagnetic waves) that employs the SLS method or the SMS method and a liquid discharge device that employs a binder jet method. The resin powder for making a solid free form of the present invention can be applied to any and all devices for making a solid free form, including a device for powder additive manufacturing.

For the device to fabricate a solid free-form fabrication object by employing the SLS method or SMS method, using electromagnetic wave irradiation as the electromagnetic wave irradiation source for use in electromagnetic irradiation, for example, it is possible use a laser that emits ultraviolet rays, visible light, infrared rays, etc., microwave, discharge, electron beams, a radiant heater, an LED lamp, or a combination thereof.

In addition, for the method of making the resin powder for making a solid free form selectively adhere to each other using electromagnetic wave irradiation, the absorption of the electromagnetic wave can be modified in terms of efficiency. For example, it is possible to make the resin powder for manufacturing a solid free form to contain an absorbent or retarder.

An example of the device for making a solid freeform fabrication object is described with reference to FIG. 4. FIG. 4 is a schematic diagram illustrating an example of the device for making a solid free-form fabrication object. As illustrated in FIG. 4, the powder is stored in a supply tank 5 for powder and supplied to a laser scan space 6 using a roller 4 in proportion to the amount of use. It is preferable that the temperature of the supply tank 5 is controlled by a heater 3. The laser scan space 6 is irradiated with the laser beams emitted from an electromagnetic wave irradiation source 1 using a reflection mirror 2. The dust It is sintered with the heat of the laser beams to obtain a solid free-form fabrication object.

The temperature of the supply tank 5 is preferably 10 degrees C or more lower than the melting point of the powder.

The temperature of the part bed in the laser scan space 6 is preferably lower than the melting point of the powder by 5 degrees C or more.

The power of the laser has no particular limit and can be conveniently selected to suit a particular application. For example, it is preferably 10 to 150 W.

In another embodiment, solid free-form fabrications of the present invention may be fabricated using selective mask sintering (SMS) technologies. The SMS process is described in, for example, US Patent Specification No. 6,531,086.

In the SMS process, the powder layers are partially and selectively irradiated with infrared, which is selectively shielded using a protective mask. When using the SMS process to manufacture a solid free-form fabrication object from the resin powder for the manufacture of a solid free-form of the present invention, it is possible and preferable to include material to enhance the infrared absorption of the powder. of resin for the manufacture of a solid free form. For example, the resin powder for making a solid free form may contain at least one type of dark-colored and / or heat-absorbing material (such as carbon fiber, carbon black, carbon nanotube, and cellulose nanofiber. ).

In yet another embodiment, using the resin powder for making a solid free form of the present invention, a solid free form manufacturing object can be manufactured by the device for making a solid free form using the binder jet. previously mentioned. The method of manufacturing a solid free form manufacturing object includes a layering process to form a layer containing the resin powder for manufacturing a solid free form of the present invention and a powder adhesion process for discharging liquid into a selected area of the layer, followed by drying to adhere them to each other, and repeating the layering process and the powder bonding process, and may also optionally include other processes.

The device for manufacturing a solid free-form manufacturing object includes a layer-forming device for forming a layer including the resin powder for manufacturing a solid free-form of the present invention and a liquid discharge device for discharging liquid to a selected area of the layer and may also optionally include other devices. As a discharge device for discharging liquid, it is preferable to employ the ink jet method in terms of precision of dimensions and speed of manufacturing of an obtained solid free-form manufacturing object.

FIG. 5 (FIG. 5A to FIG. 5F) is a schematic diagram illustrating an example of the binder jet method process. The device for fabricating a solid freeform fabrication illustrated in FIG. 5 includes a powder storage tank 111 for manufacturing and a powder storage tank 112 for supply. Each of these powder storage tanks 111 and 112 has a platform 113 that can move up and down and places the resin powder for making a solid free form of the present invention on the platform 113 to form a layer. formed by the resin powder for the manufacture of a solid free form. A manufacturing liquid supply device 115 is arranged on the manufacturing powder storage tank 111 to discharge a liquid material 116 for manufacturing a solid free form into the resin powder for manufacturing a solid free form in the powder storage tank. Furthermore, the device for making a solid free-form manufacturing includes a resin powder layering device 114 (hereinafter also referred to as a coater), capable of supplying the resin powder for manufacturing a solid free form from the powder storage tank 112 for supplying to the powder storage tank 111 for manufacturing and smoothing the surface of the resin powder layer in the powder storage tank 111 for manufacturing.

FIGS. 5A and 5B are diagrams illustrating the stage of supplying the resin powder from the powder storage tank 112, to supply it to the powder storage tank 111 for manufacturing, and the stage of forming the resin powder layer that it has a smooth surface. Each platform 113 of the powder storage tank 111 for manufacturing and the powder storage tank 112 for delivery is controlled to adjust the space between them to obtain a desired layer thickness. Subsequently, the resin powder layering device 114 is moved from the powder storage tank 112 to supply the powder storage tank 111 for manufacturing to form a resin powder layer in the powder storage tank 11. powder for manufacturing.

FIG. 5C is a diagram illustrating the process of dripping the liquid material 116 for manufacturing from a solid free form to the resin powder layer in the powder storage tank 111 for manufacturing, using a manufacturing liquid supply device. 115 for the fabrication of a solid free form. At this point, the position where the liquid material 116 for making a solid free form is dripped into the resin powder layer is determined based on the two-dimensional image data (cut data) obtained by cutting the object. flat multilayer solid free-form fabrication.

In FIGS. 5D and 5E, the platform 113 of the powder storage tank 112 for supply is raised and the platform 13 of the powder storage tank 111 for manufacturing is lowered, while controlling the space between them to obtain a layer thickness wanted. Subsequently, the resin powder layering device 114 is moved again from the powder storage tank 112 to supply it to the powder storage tank 111 for manufacturing. As a result, a new layer of dust is formed from resin in the powder storage tank 111 for the manufacture of a solid free form.

FIG. 5F is a diagram illustrating the process of dripping the liquid material 116 for manufacturing a solid free form back into the resin powder layer in the powder storage tank 111 for manufacturing, using the liquid supply device manufacturing 115. This series of processes is repeated. After optional drying, the resin powder to which no liquid material is attached for making a solid free form is removed as additional powder to obtain a solid free form fabrication object.

It is preferable that it contains an adhesive to make the resin powder adhere to each other. The adhesive can be dissolved in liquid to be discharged. Alternatively, the adhesive can be mixed with the resin powder as an additive particle. The adhesive is preferably dissolved in liquid to be discharged. For example, the adhesive is water-soluble if the liquid is mainly water.

Examples of the water-soluble adhesive are polyvinyl alcohol (PVA) resins, polyvinylpyrrolidone, polyamides, polyacrylic amides, polyethylene imine, polyethylene oxides, polyacrylate resins, cellulose resins and gelatin. Of these, polyvinyl alcohol is most preferably used to enhance the strength and dimensional accuracy of a solid free-form fabricated object.

The resin powder for making a solid free-form has a good fluidity, so that the surface property of an obtained solid free-form manufacturing object can be enhanced. This is not limited to the method using electromagnetic irradiation, but can be applied to all solid free form manufacturing devices employing powder additive manufacturing, such as a binder jet method.

Solid Freeform Fabrication Object

The solid freeform fabrication object can be suitably manufactured by executing the solid freeform fabrication method of fabrication using the resin powder for solid freeform fabrication of the present invention.

Having generally described the preferred embodiments of the present disclosure, a greater understanding may be obtained by reference to certain specific examples which are provided herein for purposes of illustration only and are not intended to be limiting. In the descriptions of the following examples, the numbers represent weight ratios in parts, unless otherwise specified.

Examples

In the following, embodiments of the present invention are described in detail with reference to, but not limited to, Examples.

Angle of repose, 50 percent cumulative volume particle diameter, average circularity, and specific gravity were measured as follows. The results are shown in Table 1.

Angle of repose

The angle of repose was measured as illustrated in FIG. 3.

As illustrated in FIG. 3, the measuring device includes 10 sieve (based on JIS Z8801-1-2000 format, 125 pm aperture diameter) and apparent specific gravity measuring device (Z-2504, manufactured by "Kuramochi Kagaku Kikai Seisakusho "). For the diameter of the apparent specific gravity, an article that fit the 2.5 mm opening diameter of the funnel 11 was used, and the base 14 that had a columnar-type shape and that had a diameter of 30 mm was placed underneath. of the funnel 11. The resin powder 12 for the manufacture of a solid free form was loaded from above into the sieve 10, passed through the funnel 11, and a mountain of the resin powder 12 'was formed for the manufacture of a solid free form. solid free form on the base 14. The resin powder 12 for the manufacture of a solid free form was charged in such an amount that at least the resin powder 12 'for the manufacture of a solid free form was poured onto the base 14 and from the side the shape of a cone was noted. The angle of repose was measured by image capture using a camera. The camera was arranged 60mm from the base 14 (from the lens) and at the same height as the top surface of the base 14 (based on the height of the lens). Subsequently, the lateral surface of the mountain was recorded by the camera. The angle formed by the surface of the base and the slope of the mountain is the angle of repose. This angle was calculated from the image obtained using trigonometry.

The measurement was performed twice and the average was determined as the angle of repose.

50 percent cumulative volume particle diameter

The volume average particle diameter was measured using a particle distribution measuring instrument. particle size (Microtrac MT3300EXII, manufactured by MicrotracBEL Corp.) using a drying process method (atmosphere) without using a solvent, using the particle refractive index per resin powder for the manufacture of a solid free form, to calculate the cumulative volume particle diameter of 50 percent. The particle refractive index was set at 1.57 polybutylene terephthalate (PBT) resin.

Average Circularity

Using a wet process flow type particle size and shape analyzer (FPIA-3000, manufactured by Sysmex Corporation), particle shape images were taken in a state that the count number of the particles of powder was 1,000 or more to obtain the average circularity of the resin particle having a columnar type shape in the particle diameter range of 0.5 to 200 pm. The circularity was measured twice for each and the average of the two was determined as the average circularity.

Specific weight

Specific gravity was obtained by measuring the density of a sample. Density was obtained by measuring the mass of the sample from its volume. The volume was obtained by changing the volume and pressure of the gas (He gas) at a constant temperature using a dry process pycnometer (AccuPyc 1330, manufactured by Shimadzu Corporation) using a gas phase replacement method.

Example 1

Using an extruder (manufactured by The Japan Steel Works, LTD.), Polybutylene terephthalate (PBT) resin granules (NOVADURAN® 5020, melting point 218 degrees C, glass transition temperature 43 degrees C, manufactured by Mitsubishi Engineering-Plastics Corporation) at a temperature 30 degrees C higher than the melting point, and then fiber was obtained using a nozzle having an orifice of a circular shape. The number of fibers extruded by the die was 100. The microgranule was stretched approximately four times to obtain a resin fiber having a fiber diameter of 60 µm with an accuracy of -4 to 4 µm.

The resin fiber obtained in this way was cut to a fiber length of 60 pm by a cutting device (NJ type 1200 series, manufactured by OGINO SEIKI CO, LTD.) Using the straw cutting method to obtain resin powder. containing resin particles having a significantly cylindrical shape. This powder was subjected to a treatment by means of a spheroidization device (MP MP5A / 1 type mixer, manufactured by NIPPON COKE & ENGINEERING. CO., LTD.) At a stirring speed of 9600 rpm for 5 minutes.

The resin powder thus obtained for the manufacture of a solid free form was checked by a scanning electron microscope (S4200, manufactured by Hitachi, Ltd). Most of the particles were resin particles having a significantly columnar-like shape and having a concave portion formed along the circumferential direction at the significantly central site of the circumferential lateral surface, and the depth of the concave portion was from about 1 pm. Furthermore, the height of the resin particle having a significantly cylindrical shape was measured. It was from 50 to 70 pm. Using the scanning electron microscope, two-dimensional images were obtained in 10 fields of view. The proportion of the resin particle having a significant cylindrical shape to all the particles in each field of view was 88 percent on average.

Example 2

The resin powder for the manufacture of a solid free form was obtained in the same manner as in Example 1, except that the stirring time of the spheroidization device was changed from 5 to 20 minutes. The resin powder thus obtained for the manufacture of a solid free form was checked in the same way as in Example 1. Most of the particles had a concave portion formed along the circumferential direction at the significantly central site. from the circumferential lateral surface, and the depth of the concave portion was approximately 5 pm. Furthermore, the height of the resin particle having a significantly cylindrical shape was measured. It was from 50 to 70 pm. The proportion of the resin particle having a significant cylindrical shape to all the particles in each field of view was 98 percent on average.

Comparative Example 1

A polybutylene terephthalate (PBT) resin (NOVADURAN® 5020, melting point: 218 degrees C, glass transition temperature: 43 degrees C, manufactured by Mitsubishi Engineering-Plastics Corporation) was subjected to freeze crushing at -200 degrees C using a cold spray system (LINREX MILL LX1, manufactured by Hosokawa Micron Corporation) to obtain a resin powder for the manufacture of a solid free form having a particle diameter of 5 to 200 pm.

The resin powder thus obtained for the manufacture of a solid free form was observed with a scanning electron microscope (S4200, manufactured by Hitachi, Ltd.). Particles of various shapes were present, such as an ellipsoidal shape, a bar-like shape, and a plate-like shape. However, there was no particle that had a concave portion formed along the circumferential direction at the significantly central site of the circumferential lateral surface.

Comparative Example 2

A resin powder for the manufacture of a solid free form was manufactured in the same manner as in Example 1, except that the resin powder was not stirred. The resin powder thus obtained for the manufacture of a solid free form was checked in the same way as in Example 1. There was no particle having a significantly cylindrical shape having a concave portion formed along the direction circumferential at the significantly central site of the circumferential lateral surface.

Comparative Example 3

0.1 mass percent silica (AEROSIL RX200, HMDS surface preparation agent, 12 nm primary particle average diameter, manufactured by Nippon Aerosil Co., Ltd.) was mixed as a flow agent with the resin powder for the Manufacture of a solid free form obtained in Comparative Example 1 using a stirrer (Tubula system of type T2F, manufactured by Willya bachofen) to obtain a resin powder for the manufacture of a solid free form containing the fluidizer. The stirring speed in the shaker was 100 rpm and the stirring time was five minutes.

The resin powder thus obtained for the manufacture of a solid free form was observed with a scanning electron microscope (S4200, manufactured by Hitachi, Ltd.). Particles having various shapes, such as an ellipsoidal shape, a bar-like shape and a plate-like shape, were present and were not different from the shapes of the resin powder of Comparative Example 1.

Reference Example 1

0.1 mass percent silica (AEROSIL RX200, HMDS surface preparation agent, 12 nm primary particle average diameter, manufactured by Nippon Aerosil Co., Ltd.) was mixed as a flow agent with the resin powder for the Manufacture of a solid free form obtained in Comparative Example 2 in the same manner as in Comparative Example 3 to obtain a resin powder to obtain a resin powder for the manufacture of a solid free form containing the fluidizer.

The resin powder thus obtained for the manufacture of a solid free form was observed with a scanning electron microscope (S4200, manufactured by Hitachi, Ltd.). The powder consisted of particles that had a significantly cylindrical shape and were not different from the shapes of the resin powder of Comparative Example 2.

The fabrication of the solid free-form fabricator and the solid free-form fabricator thus obtained were evaluated with respect to the coating (smoothness) and the surface property. The results are shown in Table 1.

Coating Property (Smoothness)

The surface of the laminated layers was visually observed during the manufacture of a solid free form to evaluate the coating property. The temperature during additive manufacturing (lamination) was the actual condition in which an object of manufacture of a target material can be manufactured.

Evaluation criteria

A (Good): Visually very smooth coating surface and no rough portions are recognized

B (Marginal): A slightly rough portion is recognized on the coating surface

C (Bad): Rough portion clearly visualized and thick surface recognized on the coating surface

Fabrication of the Solid Freeform Fabrication Object

A solid free-form fabrication object was manufactured by a fabrication device by the method of SLS (AM S5500P, manufactured by Ricoh Company, Ltd.) using the resin powder obtained for the fabrication of a solid free-form. The conditions were: average layer thickness of 0.1mm, a laser output of 10 to 150 W, a laser scan gap of 0.1 mm, and a workpiece bed temperature of -3 degrees C below of the melting point. Based on data such as CAD of a cuboid solid freeform fabrication object (sample for dimensions) (mm) having a side of 5 cm and an average thickness of 0.5 cm, the above-mentioned sample was fabricated.

Surface property

The surface of the obtained solid free-form fabrication object was visually checked, observed with an optical microscope, and subjected to an organoleptic test. In the organoleptic test, the sample was touched with the hands and the property of the surface, in particular the smoothness, was evaluated from the tactile impression. These results were collectively checked to evaluate the property of the surface based on the following evaluation criteria.

Evaluation criteria

A (Excellent): Very smooth surface without any rough portion or annoying rough surface

B (Good): No problem about surface smoothness and allowable roughness and coarse surface C (Marginal): No smooth surface with rough portion and rough surface clearly visible

D (Bad): Surface with hooks and many defects such as roughness and surface distortion are recognized

According to the present invention, there is provided an improved resin powder for the manufacture of a solid free form which is capable of imparting excellent smoothness to the surface of the powder during coating of a powder layer, and a good property of surface, to a solid free-form fabrication object obtained without adding a flow agent.

Claims (14)

1. A resin powder for the manufacture of a solid free form, comprising: resin particles having a significantly columnar-like shape, including resin particles having a concave portion on a circumferential lateral surface, wherein the resin powder has an angle of repose, measured in accordance with the description, of 55 degrees or less. The resin powder according to claim 1, wherein the resin powder has a cumulative volume particle diameter of 50 percent from 5 to 200 pm. The resin powder according to claim 1 or claim 2, wherein the resin powder has an average circularity of 0.80 or greater in a particle diameter range of 0.5 to 20 pm. The resin powder according to any one of claims 1 to 3, wherein the resin powder has an average circularity of 0.83 or higher in a particle diameter range of 0.5 to 200 pm. The resin powder according to any one of claims 1 to 4, wherein the resin powder has a particle diameter ratio of a volume average particle diameter to a number average particle diameter of 2.00 or less. The resin powder according to any one of claims 1 to 5, wherein the resin powder has a specific gravity of 0.8 or more. The resin powder according to any one of claims 1 to 6, further comprising at least one member selected from the group consisting of polyolefin, polyamide, polyester, polyether, polyaryl ketone, poly (phenylene sulfide), a polymer liquid crystal, polyacetal, polyimide and a fluorochemical resin. 8. The resin powder according to claim 7, wherein the polyamide includes an aromatic polyamide. The resin powder according to claim 7 or claim 8, wherein the polyamide includes at least one member selected from the group consisting of polyamide 410, polyamide 4T, polyamide 6, polyamide 66, polyamide MXD6, polyamide 610, polyamide 6T, polyamide 11, polyamide 12, polyamide 9T, polyamide 10T and aramid. The resin powder according to any one of claims 7 to 9, wherein the polyester includes at least one member selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate and polylactate. The resin powder according to any one of claims 7 to 10, wherein the polyether includes at least one member selected from the group consisting of polyether ether ketone, polyether ketone and polyether ketone ketone. The resin powder according to any one of claims 1 to 11, satisfying at least one of the following relationships (1) to (3): (1): Tmf1> Tmf2, where Tmf1 represents a melting start temperature of an endothermic peak when the resin powder is heated to a temperature 30 degrees C higher than the melting point of the resin powder at a rate of increase of the temperature of 10 degrees C per minute, and Tmf2 represents a melting start temperature of an endothermic peak when the resin powder is heated to a temperature 30 degrees C higher than the melting point of the resin powder at a rate of increase from the temperature of 10 degrees C per minute, it is cooled to -30 degrees C or lower at a rate of decrease in temperature of 10 degrees C per minute, and heated to the temperature 30 degrees C higher than the melting point at a rate of temperature increase of 10 degrees C per minute for a second time, and both Tmf1 and Tmf2 are measured by differential scanning calorimetry measuring according to ISO 3146, where the starting temperature of the Endothermic peak melting represents a temperature at a point -15 mW lower than a straight line drawn parallel to the X-axis from a location where the amount of heat becomes constant after the endotherm at the melting point ends on a temperature side more low, (2): Cd1> Cd2, where Cd1 represents a crystallinity obtained from an amount of energy of the endothermic peak when the resin powder is heated to a temperature 30 degrees C higher than the melting point of the resin powder at a speed of temperature increase of 10 degrees C per minute, and Cd2 represents a crystallinity obtained from an amount of energy of the endothermic peak when the resin powder is heated to a temperature 30 degrees C higher than the melting point of the resin powder at a temperature increase rate of 10 degrees C per minute, cooled to -30 degrees C or lower at a temperature decrease rate of 10 degrees C per minute, and heated to the temperature 30 degrees C higher than the point melting at a rate of increase in temperature of 10 degrees C per minute for one second, and both Cd1 as Cd2 are measured by differential scanning calorimetry measuring according to ISO 3146, and (3): C x 1> C x 2, where C x 1 represents a crystallinity of the resin powder obtained by X-ray diffraction measurement , and C x 2 represents a crystallinity obtained by measurement of X-ray diffraction when the resin powder is heated to a temperature 30 degrees C higher than its melting point at a rate of increase in temperature of 10 degrees C per minute , is cooled to -30 degrees C or less at a temperature decrease rate of 10 degrees C per minute, and subsequently heated to a temperature of 30 degrees C above the melting point at a temperature rise rate of 10 degrees C per minute in a nitrogen atmosphere. 13. A device for fabricating a solid free-form fabricated object, comprising: a layer-forming device including the resin powder of any of claims 1-12 configured to form a layer; and a powder bonding device configured to make the resin powder adhere to each other in a selected area of the layer. The device according to claim 13, wherein the powder adhesion device includes an electromagnetic wave irradiation device.