WO2019172003A1 - Method for producing thermoplastic-resin-containing particles, resin composition for three-dimensional forming, and method for producing three-dimensional shape from said resin composition - Google Patents

Abstract

The present invention addresses the problem of providing: a method for easily and efficiently producing thermoplastic-resin-containing particles; a resin composition for three-dimensional forming which includes thermoplastic-resin-containing particles obtained by the method; and a method for producing a three-dimensional shape from the resin composition. For solving the problem, the method for producing thermoplastic-resin-containing particles comprises: a mixing step in which a thermoplastic resin is mixed with a water-soluble resin having a heat resistance temperature of 130-200°C to obtain a mixture; a kneading step in which the mixture is heated to a temperature not lower than the softening point of the mixture and kneaded to obtain a kneaded mixture; a cooling step in which the kneaded mixture is cooled to a temperature lower than the softening point; a dissolution step in which after the cooling step, the kneaded mixture is mixed with a first solvent, which comprises water or an organic solvent, thereby dissolving the water-soluble resin in the first solvent; and a separation step in which after the dissolution step, the solid matter is taken out to obtain thermoplastic-resin-containing particles.

Description

Method for producing thermoplastic resin-containing particles, resin composition for three-dimensional modeling, and method for producing three-dimensional molded article using the same

The present invention relates to a method for producing thermoplastic resin-containing particles, a resin composition for three-dimensional modeling, and a method for manufacturing a three-dimensional model using the same.

In recent years, various methods capable of relatively easily manufacturing a three-dimensional object having a complicated shape have been developed, and rapid prototyping and rapid manufacturing using such a method have attracted attention.

Conventionally, these three-dimensional object manufacturing methods have been widely used in the field of modeling, but in recent years, there has been an active movement to directly apply these techniques to manufacturing. For example, the production of functional prosthetic orthoses and the like has been studied. However, a prosthetic limb orthosis or the like is required to have high mechanical strength, and to be thin and have a high elastic modulus.

Here, in one of the methods for producing a three-dimensional structure, a thin layer made of resin particles containing a thermoplastic resin is formed, and resin particles in a desired region are sintered or melt bonded (hereinafter simply referred to as “melt bonding”). And a method of obtaining a three-dimensional model. Among the manufacturing methods of various three-dimensional modeled objects, the three-dimensional modeled manufacturing method using resin particles can produce a three-dimensional modeled object with relatively high modeling accuracy compared to other methods.

One of the methods for manufacturing such a three-dimensional model is a powder bed fusion bonding method. In the powder bed fusion bonding method, resin particles are laid flat to form a thin layer, and the thin layer is irradiated with laser light in a pattern (a pattern obtained by finely dividing a three-dimensional structure in the thickness direction). As a result, the resin particles in the region irradiated with the laser beam are selectively melt-bonded. Further, resin particles are further spread on the obtained shaped article layer, and laser light irradiation is repeated in the same manner to obtain a three-dimensional shaped article having a desired shape.

Further, as another example of a method for manufacturing a three-dimensional structure using resin particles, there is a Multi Jet Fusion method (hereinafter also referred to as “MJF method”) (for example, Patent Document 1). In the MJF method, first, resin particles are laid flat to form a thin layer. In the thin layer, an energy absorbent or the like is applied to a region where the resin particles are melt-bonded (hereinafter also referred to as “cured region”), and energy is irradiated. Furthermore, resin particles are further spread on the obtained shaped article layer, and the same process is repeated to obtain a three-dimensional shaped article having a desired shape.

The physical properties of the three-dimensional structure obtained by the above-described powder bed fusion bonding method and MJF method greatly depend on the type and physical properties of the resin particles used. Conventionally, resin particles have been prepared by dissolving a thermoplastic resin in a solvent heated to a high temperature and then precipitating it with stirring. However, a resin having a high mechanical strength and a high elastic modulus generally has a high melting temperature. Therefore, when preparing the resin particles by the method, the solvent and the resin must be heated to a high temperature, and there is a problem that the production efficiency is low.

On the other hand, a method of kneading a thermoplastic resin and a water-soluble resin has also been proposed as a method for preparing resin particles used in the powder bed melt bonding method and the MJF method (for example, Patent Document 1 and Patent Document 2). . In this method, a thermoplastic resin is dispersed in a water-soluble resin by kneading, and then the water-soluble resin is removed to obtain desired thermoplastic resin-containing particles. As the water-soluble resin, polyethylene glycol, polyethylene oxide and the like have been proposed.

JP 2006-321711 A JP 2007-277546 A

However, it is difficult to disperse a resin having a high viscosity or a resin having a high elastic modulus in polyethylene glycol or the like, and it is difficult to prepare uniform resin particles by the methods described in Patent Document 1 and Patent Document 2. It was.

The present invention has been made in view of the above problems. That is, the present invention relates to a method for efficiently producing thermoplastic resin-containing particles by a simple method, a resin composition for three-dimensional modeling including the thermoplastic resin-containing particles obtained thereby, and a three-dimensional molded article using the same. The purpose is to provide a method.

The present invention provides the following method for producing thermoplastic resin-containing particles.
[1] A mixing step of mixing a thermoplastic resin and a water-soluble resin having a heat resistant temperature of 130 ° C. or higher and 200 ° C. or lower to obtain a mixture, and heating and kneading the mixture to a temperature above the softening point of the mixture. A kneading step to obtain, a cooling step for cooling the kneaded material below the softening point, and after the cooling step, the kneaded material is mixed with a first solvent containing water or an organic solvent, and the water-soluble resin is mixed with the first water-soluble resin. The manufacturing method of the thermoplastic resin containing particle | grains including the melt | dissolution process melt | dissolved in 1 solvent, and the isolation | separation process of isolate | separating solid content after the said melt | dissolution process and obtaining a thermoplastic resin containing particle | grain.

[2] The method for producing thermoplastic resin-containing particles according to [1], wherein the water-soluble resin contains an ethylene oxide / propylene oxide copolymer.
[3] The method for producing thermoplastic resin-containing particles according to [2], wherein the ethylene oxide / propylene oxide copolymer has a weight average molecular weight of 50,000 to 150,000.
[4] The method for producing thermoplastic resin-containing particles according to any one of [1] to [3], wherein the thermoplastic resin includes polypropylene.
[5] The method for producing thermoplastic resin-containing particles according to [4], wherein the polypropylene has an elastic modulus at 27 ° C. of 1500 MPa to 2500 MPa.
[6] Any of [1] to [5], wherein the mixing step is a step of mixing the thermoplastic resin and the water-soluble resin at a mass ratio of 1: 9 to 5: 5 to obtain the mixture. The manufacturing method of the thermoplastic resin containing particle | grains as described in any one of.

[7] The thermoplastic resin according to any one of [1] to [6], further including a washing step of washing the thermoplastic resin-containing particles with water or a second solvent containing an organic solvent after the separation step. Production method of contained particles.
[8] The washing step is a step of washing the thermoplastic resin-containing particles until the content of the water-soluble resin with respect to the mass of the thermoplastic resin-containing particles is 5% by mass or less. The manufacturing method of the thermoplastic resin containing particle | grains of description.
[9] The washing step is a step of washing the thermoplastic resin-containing particles with an organic solvent. After the washing step, the organic solvent and the water-soluble resin are separated, and the organic solvent is recovered. The method for producing thermoplastic resin-containing particles according to [7] or [8], further comprising a solvent recovery step.

[10] The dissolving step is a step of dissolving the water-soluble resin in an organic solvent, and after the dissolving step, the organic solvent and the water-soluble resin are separated, and the first solvent recovery for recovering the organic solvent The method for producing thermoplastic resin-containing particles according to any one of [1] to [9], further comprising a step.
[11] In [9] or [10], the first solvent and / or the second solvent is selected from the group consisting of acetonitrile, dichloromethane, methanol, ethanol, toluene, tetrahydrofuran, acetone, and ethyl acetate. The manufacturing method of the thermoplastic resin containing particle | grains of description.

The present invention provides the following three-dimensional modeling resin composition.
[12] A thermoplastic resin-containing particle comprising a thermoplastic resin and a water-soluble resin having a heat resistant temperature of 130 ° C. or higher and 200 ° C. or lower, wherein the amount of the water-soluble resin is 0.001% by mass to 5% by mass. A resin composition for three-dimensional modeling.

[13] The resin composition for three-dimensional modeling according to [12], wherein the water-soluble resin includes an ethylene oxide / propylene oxide copolymer.
[14] The resin composition for three-dimensional modeling according to [13], wherein the ethylene oxide / propylene oxide copolymer has a weight average molecular weight of 50,000 to 150,000.
[15] The resin composition for three-dimensional modeling according to any one of [12] to [14], wherein the thermoplastic resin includes polypropylene.
[16] The resin composition for three-dimensional modeling according to [15], wherein the polypropylene has an elastic modulus at 27 ° C. of 1500 MPa to 2500 MPa.

The present invention provides the following manufacturing method of a three-dimensional model.
[17] A thin layer forming step of forming a thin layer containing the three-dimensional modeling resin composition according to any one of [12] to [16], and selectively irradiating the thin layer with laser light, A laser beam irradiation step of forming a molded article layer in which a plurality of the thermoplastic resin-containing particles are melt-bonded, and the thin layer forming step and the laser beam irradiation step are repeated a plurality of times to laminate the molded article layer The manufacturing method of a three-dimensional molded item which forms a three-dimensional molded item by doing.
[18] A thin layer forming step for forming a thin layer containing the resin composition for three-dimensional modeling according to any one of [12] to [16] above, and a binding fluid containing an energy absorbing agent Applying a fluid to the specific area and irradiating the thin layer after the fluid application process with energy to form a shaped article layer in which the thermoplastic resin-containing particles are melted in the area where the binding fluid is applied. Manufacturing a three-dimensional structure including an energy irradiation step, forming the three-dimensional structure by repeating the thin layer forming step, the fluid application step, and the energy irradiation step a plurality of times and laminating the three-dimensional object layer. Method.

According to the method for producing thermoplastic resin-containing particles of the present invention, thermoplastic resin-containing particles can be efficiently produced by a simple method. Moreover, the resin composition for three-dimensional modeling containing the thermoplastic resin containing particle obtained by the said method, and the manufacturing method of a three-dimensional molded item using the same are provided.

1. Method for Producing Thermoplastic Resin-Containing Particles The method for producing thermoplastic resin-containing particles of the present invention includes a mixing step of obtaining a mixture of a thermoplastic resin and a water-soluble resin having a heat resistant temperature of 130 ° C. or higher and 200 ° C. or lower, and kneading of the mixture. A kneading step for obtaining the product, a cooling step for cooling the obtained kneaded product, a dissolving step for dissolving the water-soluble resin in the kneaded product in the first solvent, and separating the solids, and containing the thermoplastic resin-containing particles. A separation step to be obtained. In addition, the manufacturing method of the said thermoplastic resin containing particle | grains may include the washing | cleaning process etc. which wash | clean the obtained thermoplastic resin containing particle | grains with a 2nd solvent as needed. Moreover, the solvent collection | recovery process which collect | recovers a 1st solvent or a 2nd solvent may be included after a melt | dissolution process and a washing | cleaning process.

As described above, conventionally, a method has been proposed in which a thermoplastic resin is kneaded with a water-soluble resin such as polyethylene glycol or polyethylene oxide, and the thermoplastic resin is dispersed in a particulate form in the water-soluble resin. However, a thermoplastic resin having a high viscosity or a thermoplastic resin having a high modulus of elasticity is difficult to uniformly disperse in polyethylene glycol or the like, and the conventional method cannot obtain desired thermoplastic resin-containing particles. was there.

In general, a thermoplastic resin having a high viscosity or a thermoplastic resin having a high elastic modulus is considered to be dispersed in a water-soluble resin such as polyethylene glycol by kneading for a long time or heating to a high temperature. It is done. However, as a result of intensive studies by the present inventors, when a thermoplastic resin is kneaded with polyethylene glycol or the like, the viscosity of polyethylene glycol or the like is excessively lowered during kneading, and it is difficult to mix with the thermoplastic resin, or polyethylene glycol or the like decomposes. It became clear that. When kneading is continued in such a state, it is difficult for the thermoplastic resin to become uniform particles, and even if they become particles, they tend to bond again. On the other hand, a water-soluble resin having a heat resistant temperature of 130 ° C. or higher and 200 ° C. or lower is less likely to have an excessively low viscosity at the time of kneading, and is not easily decomposed by heat. Therefore, it has been found that the thermoplastic resin is easily dispersed uniformly and desired thermoplastic resin-containing particles can be obtained.

Hereinafter, each step of the method for producing the thermoplastic resin-containing particles of the present invention will be described in detail.

1-1. Mixing Step In the mixing step, a thermoplastic resin and a water-soluble resin having a heat resistant temperature of 130 ° C. or higher and 200 ° C. or lower are mixed to obtain a mixture. The mixing method of the thermoplastic resin and the water-soluble resin is not particularly limited, and can be performed with a known mixing / stirring apparatus. The mixing of the thermoplastic resin and the water-soluble resin may be performed at room temperature or while heating.

Here, the mixing ratio (mass ratio) of the thermoplastic resin and the water-soluble resin is preferably 1: 9 to 5: 5, more preferably 4: 6 to 5: 5, and more preferably 4: 5 to 5. More preferably, it is 5: 5. If the amount of the thermoplastic resin is excessively large, it becomes difficult to sufficiently disperse the thermoplastic resin in the water-soluble resin in the kneading step described later. However, if the mixing ratio is 5: 5 or less, the thermoplastic resin is water-soluble. It becomes easy to disperse in the functional resin. On the other hand, from the viewpoint of productivity of the thermoplastic resin-containing particles, the mixing ratio is preferably 1: 9 or more.

The thermoplastic resin is not particularly limited, but is a relatively high elasticity thermoplastic resin from the viewpoint of sufficiently obtaining the effects of the present invention, and further from the viewpoint of increasing the elastic modulus of the resulting three-dimensional structure. Is preferred. Specifically, the elastic modulus at 27 ° C. of the thermoplastic resin is preferably 1400 MPa or more, and more preferably 1700 MPa or more. On the other hand, when the elastic modulus is excessively high, it is difficult to disperse in the water-soluble resin. Therefore, the elastic modulus at 27 ° C. of the thermoplastic resin is preferably 2500 MPa or less, and more preferably 2300 MPa or less. The elastic modulus of the thermoplastic resin is measured by a tensile tester according to ISO 527-1: 2017.

Examples of the thermoplastic resin include polyamide 12, polypropylene, polylactic acid, polyethylene, polyethylene terephthalate, polystyrene, acrylonitrile / butadiene / styrene copolymer thia, ethylene / vinyl acetate copolymer, styrene / acrylonitrile copolymer, and poly Caprolactone and the like are included. Among these, polyamide 12 and polypropylene are preferable, and polypropylene is particularly preferable from the viewpoints of high elastic modulus and high mechanical strength. In addition, a thermoplastic resin may use only 1 type and may use it in combination of 2 or more type.

Here, when the thermoplastic resin is polypropylene, the elastic modulus at 27 ° C. of the polypropylene is preferably 1500 MPa or more and 2500 MPa or less, more preferably 2000 MPa or more and 2500 MPa or less, and 2300 MPa or more and 2500 MPa or less. Further preferred. When the elastic modulus of polypropylene is within this range, a highly versatile three-dimensional modeled object can be easily obtained.

The shape of the thermoplastic resin mixed in this step is not particularly limited, and may be, for example, a lump shape, a particle shape, or a pellet shape.

On the other hand, the water-soluble resin to be mixed in this step is not particularly limited as long as it has a heat resistant temperature of 130 ° C. or higher and 200 ° C. or lower, is water-soluble, and has low compatibility with the above-described thermoplastic resin. Here, in the present specification, the “heat-resistant temperature” of the water-soluble resin means the upper limit of the decomposition temperature of the water-soluble resin, and is measured by raising the temperature until a change in storage elastic modulus occurs with a rheometer. Value. Further, “having water solubility” means a case where 10 g or more is dissolved in 100 g of water.

In the kneading step described later, it is preferable to select a water-soluble resin having a fluidity behavior close to that of the thermoplastic resin from the viewpoint of uniformly dispersing the thermoplastic resin in the water-soluble resin. For example, when the viscosity of the thermoplastic resin at 150 ° C. is 1, the viscosity of the water-soluble resin at 150 ° C. is preferably 0.8 to 1.2, more preferably 0.9 to 1. . The viscosity is a value measured when the temperature is raised to 100 ° C. to 200 ° C. with a rheometer.

Specific examples of the water-soluble resin include ethylene oxide / propylene oxide copolymer, polyacrylamide and the like. Only one kind of water-soluble resin may be used, or two or more kinds of water-soluble resins may be mixed and used. Among these, an ethylene oxide / propylene oxide copolymer is preferable from the viewpoint that it can be dissolved in an organic solvent and has high heat resistance in the dissolution step described later.

Here, the ethylene oxide / propylene oxide copolymer preferably has a weight average molecular weight of 50,000 to 150,000, more preferably 50,000 to 120,000, and even more preferably 50,000 to 100,000. The weight average molecular weight is a molecular weight (in terms of styrene) measured by gel permeation chromatography (GPC). If the weight average molecular weight of the ethylene oxide / propylene oxide copolymer is excessively large, it may be difficult to dissolve in water or an organic solvent, but if it is 150,000 or less, it can be sufficiently dissolved therein. When the weight average molecular weight of the ethylene oxide / propylene oxide copolymer is 50000 or more, the viscosity of the ethylene oxide / propylene oxide and the viscosity of the thermoplastic resin at the time of kneading tend to be close.

The ethylene oxide / propylene oxide copolymer may be any copolymer of an ethylene oxide monomer and a propylene oxide monomer, but the polymerization ratio of the ethylene oxide monomer to the propylene oxide monomer is 12: 1 to 10: 1. Preferably, it is 8: 1 to 7: 1, more preferably 6: 1 to 5: 1. If the structure derived from the ethylene oxide monomer is contained in a certain amount or more, the solubility of the ethylene oxide / propylene oxide copolymer in water or an organic solvent is improved in the dissolution step described later.

In addition, the shape of the water-soluble resin at the time of mixing in this step is not particularly limited, and may be, for example, a lump shape, a particle shape, or a pellet shape.

1-2. Kneading step The mixture prepared in the above-described mixing step is heated and kneaded at a temperature equal to or higher than the softening point of the mixture. The softening point of the mixture was raised from 0 ° C. to 200 ° C. under a differential scanning calorimeter (DSC) at 10 ° C./min, annealed for 10 minutes, lowered from 200 ° C. to 0 ° C., and further 0 ° C. To 200 ° C.

The temperature at the time of kneading may be equal to or higher than the softening point of the above-mentioned mixture, but is preferably 10 to 200 ° C. higher than the softening point, more preferably 20 to 150 ° C. higher. When the temperature at the time of kneading is 10 ° C. or more higher than the softening point, the thermoplastic resin is easily dispersed uniformly in the water-soluble resin. On the other hand, by setting the temperature during kneading to a temperature that is 200 ° C. or less higher than the softening point, it becomes difficult for the water-soluble resin or thermoplastic resin to decompose during kneading.

The kneading time is not particularly limited as long as the thermoplastic resin can be dispersed in the water-soluble resin until a desired average particle size is obtained. Usually, it can be 10 to 40 minutes, more preferably 10 to 30 minutes, and further preferably 15 to 20 minutes. When the kneading time is excessively long, the production efficiency is lowered, or the water-soluble resin is easily decomposed. On the other hand, if the kneading time is excessively short, it is difficult to sufficiently disperse the thermoplastic resin.

In this step, the thermoplastic resin dispersed in the water-soluble resin is preferably kneaded so that the average particle size is about 20 to 100 μm, more preferably about 30 to 70 μm. preferable. When the average particle diameter of particles containing a thermoplastic resin (also referred to as “thermoplastic resin-containing particles” in the present application) is 100 μm or less, a three-dimensional structure having a fine structure is produced using the thermoplastic resin-containing particles. It becomes possible. On the other hand, it is preferable that it is 20 micrometers or more from a viewpoint of providing sufficient fluidity | liquidity to a thermoplastic resin containing particle at the time of preparation of a three-dimensional molded item, and making a handleability favorable. Moreover, it is preferable that the particle size distribution of the particle diameter of each thermoplastic resin containing particle is narrow. The polydispersity (Mw / Mn) of the thermoplastic resin-containing particles is preferably 2.0 or less, more preferably 1.8 or less, and even more preferably 1.5 or less. The weight average molecular weight (Mw) and the number average molecular weight (Mn) of the thermoplastic resin-containing particles can be measured by GPC. When the polydispersity (Mw / Mn) is low, the particle size distribution of the particle size is likely to be low.

The average particle size can be specified by extracting a part of the kneaded material, dissolving the water-soluble resin in the first solvent described later, and then measuring the average particle size of the remaining particulate component. Specifically, the volume average particle diameter is measured by a dynamic light scattering method. The volume average particle diameter can be measured by a laser diffraction particle size distribution measuring apparatus (manufactured by Microtrack Bell Co., Ltd., MT3300EXII) equipped with a wet disperser.

Here, the kneading method in this step is not particularly limited and includes, for example, a roll, a Banbury mixer, a kneader, a single screw extruder, a twin screw extruder, and the like. Among these, a twin screw extruder is preferable from the viewpoint of making the average particle diameter of the obtained thermoplastic resin-containing particles uniform. The kneaded material after kneading may be left in a lump shape, but may be processed into various shapes such as a sheet shape, a strand shape, and a pellet shape.

1-3. Cooling step After the kneading step, the kneaded product is cooled to below its softening point. In this step, the kneaded product is preferably cooled to a temperature 110 ° C. or more lower than the softening point, and more preferably 120 ° C. or lower. By sufficiently cooling in the cooling step, the thermoplastic resin is solidified, and the thermoplastic resin-containing particles (thermoplastic resin) are hardly fused in the dissolution step and the separation step described later. In the cooling step, it is preferable to cool the kneaded product so that the temperature is uniform.

The kneaded product may be slowly cooled or rapidly cooled. The method for cooling the kneaded product is not particularly limited. For example, the kneaded product may be cooled by leaving it at room temperature, or may be cooled using a known cooling device or the like. Slowly cooling the kneaded product is preferable because the particles grow slowly, and a method of leaving the mixture at room temperature is particularly preferable.

1-4. Dissolution Step After the cooling step, the kneaded product is mixed with a first solvent containing water or an organic solvent, and the water-soluble resin is dissolved in the first solvent.

The first solvent may be any solvent that can dissolve the water-soluble resin and does not dissolve the thermoplastic resin, such as water, acetonitrile, dichloromethane, methanol, ethanol, toluene, tetrahydrofuran, acetone, ethyl acetate, or the like. It can be an organic solvent. One kind of these may be contained in the first solvent, or two or more kinds thereof may be contained. Among these, acetonitrile, dichloromethane, methanol, ethanol, toluene, tetrahydrofuran, and acetone are preferable from the viewpoint that the water-soluble resin is easily dissolved.

As a method of dissolving the water-soluble resin in the first solvent, a method of immersing the kneaded material in the first solvent can be used. At this time, the kneaded product may be crushed with a crusher or the like and then immersed in the first solvent so that the water-soluble resin is easily dissolved. Furthermore, after the kneaded product is immersed, the first solvent may be stirred as necessary.

The temperature of the first solvent at the time of mixing the first solvent and the kneaded material may be a temperature not higher than the boiling point of the first solvent, and may be heated as necessary. For example, when ethyl acetate or ethanol is used as the first solvent, the first solvent is heated to 50 ° C. or higher from the viewpoint of enhancing the solubility of the water-soluble resin in the first solvent, and then kneaded. It is preferable to mix with. On the other hand, when other solvents are used, the first solvent and the kneaded material described above may be mixed at room temperature.

The time for bringing the first solvent into contact with the kneaded product is appropriately selected according to the solubility of the water-soluble resin and the like, but can be usually 1 to 5 hours, and more preferably 3 to 7 hours. preferable. In the dissolving step, the water-soluble resin is dissolved so that the amount of the water-soluble resin in the thermoplastic resin-containing particles is 0.001% to 5% by mass or less with respect to the mass of the thermoplastic resin-containing particles. It is preferable to make it. When the amount of the water-soluble resin is 0.001% to 5% by mass or less, the strength or the like of the three-dimensional model is likely to be sufficiently high when the three-dimensional model is manufactured using the thermoplastic resin-containing particles. The amount of the water-soluble resin in the thermoplastic resin-containing particles can be specified by comparing the peak derived from the thermoplastic resin and the peak derived from the water-soluble resin by NMR measurement.

1-5. Separation step After the dissolution step, the solid content contained in the solution is separated to obtain thermoplastic resin-containing particles. The solid content separation method is not particularly limited, and can be, for example, centrifugal separation, filtration, or a combination thereof. If necessary, the thermoplastic resin-containing particles may be dried by a known drying method.

1-6. Washing step After the separation step described above, a washing step for washing the obtained thermoplastic resin-containing particles may be performed as necessary. The washing step can be a step of washing the thermoplastic resin-containing particles with a second solvent containing, for example, water or an organic solvent.

By performing the washing step, the water-soluble resin in the thermoplastic resin-containing particles can be further removed, and the amount of the thermoplastic resin in the thermoplastic resin-containing particles can be increased. As a result, it is possible to increase the strength of the three-dimensional structure produced using the thermoplastic resin-containing particles.

The washing step can be a step of immersing the thermoplastic resin-containing particles separated in the separation step in a second solvent. As the second solvent, the same solvents as those described above can be used. Note that the first solvent and the second solvent may be the same or different.

Further, the temperature of the second solvent at the time of performing the washing step may be a temperature not higher than the boiling point of the second solvent, and may be appropriately heated as necessary. For example, when ethyl acetate or ethanol is used as the second solvent, it is preferable to heat the second solvent to 50 ° C. or higher from the viewpoint of enhancing the solubility of the water-soluble resin in the second solvent. On the other hand, when other solvents are used, the second solvent and the thermoplastic resin-containing particles may be mixed at room temperature.

In the dissolving step, the thermoplastic resin-containing particles are preferably washed so that the amount of the water-soluble resin in the thermoplastic resin-containing particles is 5% by mass or less with respect to the mass of the thermoplastic resin-containing particles. When the amount of the water-soluble resin is 5% by mass or less, the strength and the like of the three-dimensional model are likely to be sufficiently high when the three-dimensional model is manufactured using the thermoplastic resin-containing particles. The amount of the water-soluble resin in the thermoplastic resin-containing particles can be specified by the same method as described above.

1-7. Solvent recovery step (first solvent recovery step and second solvent recovery step)
In addition, after the above-described dissolution step and washing step, a solvent recovery step for recovering the first solvent and / or the second solvent (collectively referred to simply as “solvent”) may be performed as necessary. . In this step, the water-soluble resin is removed from the first solvent and the second solvent in which the water-soluble resin is dissolved, and each solvent is reused.

The method for recovering the solvent is not particularly limited. For example, the solvent and the water-soluble resin can be separated by distillation or the like, and the solvent can be collected. In addition, when the 1st solvent and the 2nd solvent are the same, you may collect | recover these collectively.

2. Three-dimensional modeling resin composition The thermoplastic resin-containing particles produced by the above-described method can be applied to a three-dimensional modeling resin composition. Hereinafter, the resin composition for three-dimensional model | molding containing a thermoplastic resin containing particle is demonstrated. The resin composition for three-dimensional model | molding of this invention is used for the method of melt-bonding thermoplastic resin containing particle | grains, such as a powder bed fusion | bonding method and a MJF method, and manufacturing a three-dimensional molded item. The three-dimensional modeling resin composition can be a composition containing thermoplastic resin-containing particles and various additives, a flow agent, and the like as necessary.

The thermoplastic resin-containing particles include a thermoplastic resin and a water-soluble resin having a heat resistant temperature of 130 ° C. or more and 200 ° C. or less, and the amount of the water-soluble resin with respect to the total amount of the thermoplastic resin-containing particles is 0.001% by mass or more. 5% by mass or less. If the thermoplastic resin-containing particles contain 0.001% by mass or more of a water-soluble resin, the water-soluble resin in the thermoplastic resin-containing particles is softened during molding, thereby improving the interfacial fusion property and breaking elongation. Has the effect of improving. Furthermore, there is an effect that crystallization of the surface of the molded article is suppressed by the water-soluble resin. On the other hand, since the amount of the water-soluble resin is 5% by mass or less, the heat resistance and mechanical strength of the three-dimensional model to be manufactured are improved. The amount of the water-soluble resin is more preferably 0.001 to 3% by mass, and further preferably 0.001 to 1% by mass. Since the thermoplastic resin-containing particles are produced by the above-described method for producing thermoplastic resin-containing particles, detailed description thereof is omitted here.

The filler included in the three-dimensional modeling resin composition as needed is not particularly limited as long as the object and effect of the present invention are not impaired. When the filler is contained in the three-dimensional modeling resin composition, the energy irradiated at the time of three-dimensional modeling is easily transmitted, or the strength of the three-dimensional modeling obtained is increased.

Examples of fillers include talc, calcium carbonate, zinc carbonate, wollastonite, silica, alumina, magnesium oxide, calcium silicate, sodium aluminate, calcium aluminate, sodium aluminosilicate, magnesium silicate, glass balloon, glass cut fiber , Glass milled fiber, glass flake, 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, Inorganic fillers such as ceramic whiskers, potassium titanate, boron nitride, graphite, layered clay minerals, carbon fibers; organic fillers such as polysaccharide nanofibers; various polymers, and the like. In the three-dimensional modeling resin composition, only one kind of filler may be contained, or two or more kinds may be contained.

The average particle diameter of the filler is preferably about 0.01 to 50 μm from the viewpoint of not inhibiting the bonding between the thermoplastic resin-containing particles during the production of the three-dimensional structure. The average particle diameter of the filler is the volume average particle diameter, and is determined by measuring with a laser diffraction particle size distribution measuring device after removing the thermoplastic resin-containing particles from the three-dimensional resin composition with a solvent or the like. it can.

Among the above, the filler is a spherical particle having a diameter of 1 to 1000 nm from the viewpoint of good conductivity of the energy irradiated during preparation of the three-dimensional structure, and easy improvement of the mechanical strength and ductility of the three-dimensional structure. Further, it is preferably a tabular particle having a thickness of 1 to 1000 nm or a fiber particle having a fiber diameter of 1 to 1000 nm.

The spherical particles may be either particles made of an inorganic material or particles made of an organic material, and examples thereof include silica fine particles, alumina fine particles, titanium oxide fine particles, zirconia fine particles and the like.

When the filler is a tabular grain, the thickness of the tabular grain is more preferably 50 to 500 nm, further preferably 100 to 400 nm, and particularly preferably 150 to 300 nm. In this specification, tabular grains have two main planes facing each other, and the distance (thickness) between these two main planes is sufficiently small with respect to the maximum diameter and minimum diameter of the main plane. Say.

In addition, the shape of the main plane of the tabular grains may be circular, elliptical, or polygonal. The width of the main plane of the tabular grains is preferably 1 to 10 μm, and more preferably 2 to 8 μm. The ratio of the maximum diameter of the main plane to the thickness of the tabular grains (maximum diameter / thickness of the main plane) is preferably 5 to 15, and more preferably 10 to 12. When the ratio between the maximum diameter of the main plane and the thickness of the tabular grains is in the above range, the energy conductivity with respect to the thermoplastic resin-containing particles tends to be good, and the thermoplastic resin-containing particles are easily melt-bonded.

Examples of tabular grains include the above-mentioned layered clay minerals (for example, kaolin; talc; mica; smectite minerals such as montmorillonite, beidellite, hectorite, saponite, nontronite, stevensite; vermiculite; bentonite; kanemite, Kenya. Layered sodium silicate such as knight and macanite; mica group clay minerals such as Na type tetrasilicic fluorine mica, Li type tetrasilicic fluorine mica, Na type fluorine teniolite, Li type fluorine teniolite). Such tabular grains may be obtained from natural minerals or may be chemically synthesized. Further, the tabular grains may be those whose surfaces are modified (surface treatment) with an ammonium salt or the like.

On the other hand, when the filler is fibrous, the fiber diameter is preferably 3 to 30 nm, more preferably 5 to 20 nm from the viewpoint of dispersibility and the like. Further, the fiber length of the fibrous filler is preferably 200 to 10,000 nm, and more preferably 250 to 10,000 nm. When the fiber length is 10000 nm or less, the appearance of the three-dimensional structure tends to be good. Moreover, the intensity | strength of the three-dimensional molded item obtained as the fiber length is 200 nm or more becomes easy to increase. Here, examples of the fibrous filler include carbon fiber, polysaccharide nanofiber, and the like.

The amount of the filler in the resin composition for three-dimensional modeling is preferably 5 to 30 parts by mass, more preferably 10 to 25 parts by mass, when the content of the thermoplastic resin-containing particles is 100 parts by mass. The amount is preferably 15 to 20 parts by mass. When the amount of the filler is 5 parts by mass or more, the mechanical strength of the three-dimensional structure obtained from the three-dimensional resin composition is likely to increase. On the other hand, when the amount of the filler is 30 parts by mass or more, the ductility of the three-dimensional structure to be obtained tends to decrease.

On the other hand, examples of various additives included in the three-dimensional modeling resin composition as necessary include antioxidants, acidic compounds and derivatives thereof, lubricants, ultraviolet absorbers, light stabilizers, nucleating agents, flame retardants, and impacts. An improving agent, a foaming agent, a coloring agent, an organic peroxide, a spreading agent, an adhesive, and the like are included. Only one of these may be contained in the three-dimensional modeling resin composition, or two or more of them may be contained. Moreover, these may be apply | coated to the surface of the thermoplastic resin containing particle | grains in the range which does not impair the objective of this invention.

Further, the flow agent may be a material having a small friction coefficient and self-lubricating property. Examples of such flow agents include silicon dioxide and boron nitride. The resin composition for three-dimensional modeling may contain only one type of flow agent or two types of flow agents. The amount of the flow agent can be appropriately set within a range in which the fluidity of the thermoplastic resin-containing particles and the like is improved and the melt bonding of the thermoplastic resin-containing particles is 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-containing particles.

Further, the three-dimensional modeling resin composition used in the powder bed melt bonding method described later may contain a laser absorber or the like. Examples of the laser absorber include carbon powder, nylon resin powder, pigment, dye, and the like. The three-dimensional modeling resin composition may contain only one type of laser absorber, or may contain two or more types.

3. Manufacturing method of three-dimensional modeled object As described above, the resin composition for three-dimensional modeled object can be used in a method for manufacturing a three-dimensional modeled object by the powder bed bonding melting method or the MJF method. Hereinafter, although the three-dimensional modeling method using the said resin composition is each demonstrated, this invention is not restrict | limited to these methods.

3-1. Method for manufacturing a three-dimensional structure by a powder bed bonding melting method In a method for manufacturing a three-dimensional structure by a powder bed bonding melting method, the method is the same as a normal powder bed bonding melting method except that the resin composition for three-dimensional modeling is used. Can do. Specifically, (1) a thin layer forming step of forming a thin layer containing the resin composition for three-dimensional modeling described above, and (2) a thermoplastic resin containing by selectively irradiating the thin layer with laser light And a laser beam irradiation step of forming a shaped article layer in which particles are melt-bonded. And a three-dimensional molded item can be manufactured by repeating a process (1) and a process (2) in multiple times, and laminating | stacking a molded article layer. In addition, the manufacturing method of the said three-dimensional molded item may include the other process as needed, for example, may include the process etc. which preheat the resin composition for three-dimensional modeling.

・ Thin layer formation process (process (1))
In this step, a thin layer containing the three-dimensional modeling resin composition is formed. For example, the resin composition for three-dimensional modeling supplied from the powder supply unit of the three-dimensional modeling apparatus is laid flat on the modeling stage by a recoater. The thin layer may be formed directly on the modeling stage, or may be formed on the resin composition for three-dimensional modeling that has already been spread, or on the modeling object layer that has already been formed. In addition, you may mix a flow agent and a laser absorber with the said resin composition for three-dimensional modeling separately as needed, and may form a thin layer.

The thickness of the thin layer is the same as the thickness of the desired object layer. Although the thickness of a thin layer can be arbitrarily set according to the precision of the three-dimensional molded item to manufacture, it is 0.01 mm or more and 0.30 mm or less normally. By making the thickness of the thin layer 0.01 mm or more, it is possible to prevent the resin composition for three-dimensional modeling of the lower layer from being melt-bonded by laser light irradiation for forming the next modeled product layer, Furthermore, uniform spread is possible. In addition, 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 portion of the thin layer, and the three-dimensional modeling resin composition constituting the thin layer is sufficient over the entire thickness direction. Can be melt bonded. 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 sufficiently melt-bonding the resin composition for three-dimensional modeling and making it difficult to cause cracks in the modeled object layer, the difference between the thickness of the thin layer and the beam spot diameter of the laser beam described later is 0.10 mm. It is preferable to set the thickness of the thin layer so as to be within the range.

・ Laser beam irradiation process (process (2))
In this process, among the thin layers containing the resin composition for three-dimensional modeling, the laser beam is selectively irradiated to the position where the molded article layer is to be formed, and the thermoplastic resin-containing particles at the irradiated position are melt-bonded. A model layer is formed. At this time, since the resin composition for three-dimensional modeling (thermoplastic resin-containing particles) that has received the energy of the laser beam is also melt-bonded to the already formed model layer, adhesion between adjacent layers also occurs.

What is necessary is just to set the wavelength of a laser beam within the range of the wavelength which the resin composition for three-dimensional modeling (thermoplastic resin containing particle | grains) absorbs. At this time, it is preferable to set so that the difference between the wavelength of the laser beam and the wavelength at which the absorption rate of the three-dimensional modeling resin composition is the highest, but in general, the thermoplastic resin has various wavelength ranges. In order to absorb light, it is preferable to use laser light having a wide wavelength band such as a CO ₂ laser. For example, the wavelength of the laser beam can be, for example, not less than 0.8 μm and not more than 12 μm.

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

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

-About repetition of a process (1) and a process (2) In the case of manufacture of a three-dimensional molded item, the above-mentioned process (1) and a process (2) are repeated arbitrary times. Thereby, a modeling object layer is laminated | stacked and a desired three-dimensional modeling object will be obtained.

-Preheating process As mentioned above, in the manufacturing method of the three-dimensional molded item by a powder bed coupling | bonding fusion method, you may perform the process of preheating the three-dimensional modeling resin composition. The preheating of the three-dimensional modeling resin composition may be performed after the thin layer formation (step (1)) or before the thin layer formation (step (1)). Moreover, you may carry out by both of these.

The preheating temperature is set to a temperature lower than the melting temperature of the thermoplastic resin contained in the thermoplastic resin-containing particles so that the resin composition for three-dimensional modeling (thermoplastic resin-containing particles) is not melt-bonded. 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. More preferably, it is as follows.

At this time, the heating time is preferably 1 to 30 seconds, more preferably 5 to 20 seconds. By performing preheating at the above temperature for the above time, it is possible to shorten the time until the resin composition for three-dimensional modeling (thermoplastic resin-containing particles) melts at the time of laser energy irradiation, and three-dimensional modeling with a small amount of laser energy. It becomes possible to manufacture a thing.

-Others From the viewpoint of preventing the strength of the three-dimensional structure from decreasing due to oxidation of the resin composition for three-dimensional modeling during melt bonding, at least step (2) is performed under reduced pressure or in an inert gas atmosphere. It is preferable. The pressure at which the pressure is reduced is preferably 10 ⁻² Pa or less, and more preferably 10 ⁻³ Pa or less. At this time, examples of the inert gas that can be used include nitrogen gas and rare gas. Among these inert gases, nitrogen (N ₂ ) gas, helium (He) gas, or argon (Ar) gas is preferable from the viewpoint of availability. From the viewpoint of simplifying the production process, it is preferable to perform both step (1) and step (2) under reduced pressure or in an inert gas atmosphere.

3-2. Manufacturing method of three-dimensional modeled object by MJF method The manufacturing method of the three-dimensional modeled object of this embodiment is (1) the thin layer formation process which forms the thin layer containing the resin composition for three-dimensional modeling mentioned above, and (2) energy absorption. A fluid application step in which a bonding fluid containing an agent is applied to a specific region of the thin layer; and (3) a thermoplastic resin in the region where the bonding fluid is applied by irradiating energy to the thin layer after the fluid application step. An energy irradiation step of forming particles by melting and bonding the particles. In addition, the manufacturing method of the said three-dimensional molded item may include the other process as needed, for example, may include the process etc. which preheat the resin composition for three-dimensional modeling.

(1) Thin layer formation process In this process, the thin layer which mainly contains the above-mentioned three-dimensional modeling 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 in which the resin composition for three-dimensional modeling supplied from the resin composition supply unit of the three-dimensional modeling apparatus is laid flat on the modeling stage by the recoater. The thin layer may be formed directly on the modeling stage, or may be formed so as to be in contact with the resin composition for three-dimensional modeling that has already been laid or the modeling object layer that has already been formed.

The thickness of the thin layer is the same as the thickness of the desired object layer. Although the thickness of a thin layer can be arbitrarily set according to the precision of the three-dimensional molded item to manufacture, it is 0.01 mm or more and 0.30 mm or less normally. By setting the thickness of the thin layer to 0.01 mm or more, the already formed object layer is melted by energy irradiation for forming a new object layer (energy irradiation in the energy irradiation process described later). Can be prevented. Moreover, it becomes easy to spread the resin composition for three-dimensional modeling uniformly as the thickness of a thin layer is 0.01 mm or more. In addition, by setting the thickness of the thin layer to 0.30 mm or less, energy (for example, infrared light) can be conducted to the lower portion of the thin layer in the energy irradiation process described later. Thereby, it becomes possible to melt the thermoplastic resin-containing particles in a desired region (region where the bonding 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 absorbent is applied to a specific region of the thin layer formed in the thin layer formation step. At this time, if necessary, a peeling fluid that absorbs less energy than the bonding fluid may be applied to a region where the bonding fluid is not applied. Specifically, the bonding fluid may be selectively applied to a position where the shaped article layer is to be formed, and the peeling fluid may be applied to a region where the shaped article layer is not formed. By applying the peeling fluid adjacent to the periphery of the region where the bonding fluid is applied, the thermoplastic resin-containing particles are hardly melt-bonded in the region where the peeling fluid is applied. Either the binding fluid or the peeling fluid may be applied first, but from the viewpoint of dimensional accuracy of the three-dimensional structure to be obtained, it is preferable to apply the binding fluid first.

The method for applying the bonding fluid and the peeling fluid is not particularly limited. For example, the bonding fluid and the peeling fluid can be applied by a dispenser, the ink jet method, the spray coating, and the like. It is preferable to apply at least one by the ink jet method from the viewpoint that it can be applied, and it is more preferable to apply both by the ink jet method.

The application amount of the bonding fluid and the peeling fluid is preferably 0.1 to 50 μL, more preferably 0.2 to 40 μL per 1 mm ^{3 of the} thin layer. When the application amounts of the bonding fluid and the peeling fluid are within the ranges, the bonding fluid and the peeling fluid are respectively added to the three-dimensional modeling resin composition in the region where the modeling object layer is formed and in the region where the modeling layer is not formed. Can be sufficiently impregnated, and a three-dimensional modeled object with good dimensional accuracy can be formed.

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 absorbent and a solvent. The binding fluid may contain a known dispersant or the like as necessary.

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

The shape of the energy absorber is not particularly limited, but is preferably particulate. The average particle diameter 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, the energy absorber will not easily enter the gap between the thermoplastic resin-containing particles when the binding fluid is applied onto the thin layer. On the other hand, if the average particle size of the energy absorbent is 0.1 μm or more, heat can be efficiently transferred to the thermoplastic resin-containing particles in the energy irradiation step described later, and the surrounding thermoplastic resin-containing particles are melted. It becomes possible.

The binding fluid preferably contains 0.1 to 10.0% by mass of energy absorber, and more preferably 1.0 to 5.0% by mass. When the amount of the energy absorbent is 0.1% by mass or more, it is possible to sufficiently increase the temperature of the region where the binding fluid is applied in the energy irradiation process 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 coupling fluid, and the application stability of the coupling fluid is likely to increase.

On the other hand, the solvent is not particularly limited as long as it can disperse the energy absorber and does not dissolve the thermoplastic resin-containing particles (particularly thermoplastic resin) in the resin composition for three-dimensional modeling. It can be.

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

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

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

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

(3) Energy irradiation process In this process, energy is collectively irradiated to the thin layer after the fluid application process, that is, the thin layer coated with the bonding fluid and the peeling fluid. At this time, in the region where the binding fluid is applied, the energy absorber absorbs energy, and the temperature of the region partially rises. And only the thermoplastic resin containing particle | grains of the said area | region fuse | melt, and a molded article layer is formed.

The type of energy irradiated in this step is appropriately selected according to the type of energy absorbent included in the binding fluid. Specific examples of the energy include infrared light and white light. Among these, in the region where the bonding fluid is applied, the thermoplastic resin-containing particles can be efficiently melted. On the other hand, in the region where the peeling fluid is applied, infrared light is preferable from the viewpoint that the temperature of the thin layer does not rise easily, light having a wavelength of 780 to 3000 nm is more preferable, and a wavelength of 800 to 2500 nm is preferable. More preferably, it is light.

The time for irradiating energy in this step is appropriately selected according to the type of thermoplastic resin-containing particles (particularly thermoplastic resin) contained in the three-dimensional modeling resin composition, but is usually 5 to 60 seconds. It is preferably 10 to 30 seconds. By setting the energy irradiation time to 5 seconds or more, it becomes possible to sufficiently melt the thermoplastic resin-containing particles and bond them. On the other hand, it becomes possible to manufacture a three-dimensional molded item efficiently by setting it as 60 seconds or less.

-Preheating process You may perform the process of preheating the three-dimensional modeling resin composition also in a MJF system. The preheating of the three-dimensional modeling resin composition may be performed after the thin layer formation (step (1)) or before the thin layer formation (step (1)). Moreover, you may carry out by both of these. By performing preheating, it is possible to reduce the amount of energy irradiated in the (3) energy irradiation step. Furthermore, it becomes possible to form a molded article layer efficiently in a short time. The preheating temperature is preferably a temperature lower than the melting temperature of the thermoplastic resin and (2) a temperature lower than the boiling point of the solvent contained in the bonding fluid or the peeling fluid applied in the fluid application step. Specifically, the temperature is preferably 50 ° C. to 5 ° C. lower than the melting point of the thermoplastic resin in the thermoplastic resin-containing particles and the boiling point of the solvent contained in the bonding fluid or the peeling fluid, and 30 ° C. to 5 ° C. It is more preferable that the temperature is lower. At this time, the heating time is preferably 1 to 60 seconds, more preferably 3 to 20 seconds. By making heating temperature and heating time into the said range, the energy irradiation amount in (3) energy irradiation process can be reduced.

Hereinafter, specific examples of the present invention will be described. These examples do not limit the scope of the present invention.

1. Production of Thermoplastic Resin-Containing Particles (Resin Composition for Three-Dimensional Modeling) The elastic modulus of the thermoplastic resin was measured at 27 ° C. with a tensile tester according to ISO 527-1: 2017.
Moreover, the weight average molecular weight of water-soluble resin was specified by gel permeation (GPC, styrene conversion).
The heat-resistant temperature of the water-soluble resin was specified by raising the temperature until a change in storage elastic modulus occurred with a rheometer.
The softening point of the mixture was raised from 0 ° C. to 200 ° C. under a differential scanning calorimeter (DSC) at 10 ° C./min, annealed for 10 minutes, lowered from 200 ° C. to 0 ° C., and further 0 ° C. To 200 ° C.

[Example 1]
45 parts by mass of a metallocene polypropylene resin (manufactured by Nippon Polypro, WMH02, elastic modulus 2300 MPa), an ethylene oxide / propylene oxide (EO / PO) copolymer (manufactured by Meisei Chemical Industry Co., Ltd., EP1010N, heat resistant temperature 200 ° C., molecular weight of about 100,000) and 55 parts by mass. The softening point of the mixture was 160 ° C. The mixture was heated to 180 ° C. and kneaded for 20 minutes with a small kneader (Xplore, MC15).
The kneaded product was cooled to 30 ° C. and then mixed with 10 L of ethyl acetate (first solvent) heated to 70 ° C. Thereby, the ethylene oxide / propylene oxide copolymer was dissolved in ethyl acetate. Thereafter, the solution was centrifuged, and thermoplastic resin-containing particles containing polypropylene resin were collected.
Further, the thermoplastic resin-containing particles were washed with ethyl acetate (second solvent) to obtain thermoplastic resin-containing particles 1 containing a polypropylene resin. The average particle diameter of the thermoplastic resin-containing particles 1 was 40 μm. The amount of the ethylene oxide / propylene oxide copolymer in the thermoplastic resin-containing particles 1 was 0.01% by mass.

[Example 2]
The thermoplastic resin-containing particles 2 were obtained in the same manner as in Example 1 except that the temperature of the first solvent when mixing with the kneaded product was 27 ° C. The average particle diameter of the thermoplastic resin-containing particles 2 was 40 μm. The amount of the ethylene oxide / propylene oxide copolymer in the thermoplastic resin-containing particles 2 was 7% by mass.

[Example 3]
The thermoplastic resin-containing particles 3 are obtained in the same manner as in Example 1 except that the first solvent and the second solvent are water and the temperature of the first solvent when mixing with the kneaded product is 27 ° C. It was. The average particle diameter of the thermoplastic resin-containing particles 3 was 50 μm. Further, the amount of the ethylene oxide / propylene oxide copolymer in the thermoplastic resin-containing particles 3 was 0.1% by mass.

[Example 4]
45 parts by mass of polyamide resin (manufactured by Daicel-Evonik Co., Ltd., Daiamide L1600, elastic modulus 1430 MPa), 55 parts by mass of ethylene oxide / propylene oxide copolymer (manufactured by Meisei Chemical Industry Co., Ltd., EP1010N, heat resistant temperature 200 ° C., molecular weight about 100,000) Part. The softening point of the mixture was 160 ° C. The mixture was heated to 200 ° C. and kneaded for 20 minutes with a small kneader (Xplore, MC15).
The kneaded product was cooled to 30 ° C. and then immersed in ethyl acetate (first solvent) heated to 70 ° C. Thereby, the ethylene oxide / propylene oxide copolymer was dissolved in ethyl acetate. Thereafter, the solution was centrifuged, and thermoplastic resin-containing particles containing a polyamide resin were collected.
Furthermore, the thermoplastic resin-containing particles were washed with ethyl acetate (second solvent) to obtain thermoplastic resin-containing particles 4 containing a polyamide resin. The average particle diameter of the thermoplastic resin-containing particles 4 was 40 μm. The amount of the ethylene oxide / propylene oxide copolymer in the thermoplastic resin-containing particles 4 was 0.01% by mass.

[Example 5]
The thermoplastic resin-containing particles 5 were obtained in the same manner as in Example 4 except that the temperature of the first solvent when mixing with the kneaded product was 27 ° C. The average particle diameter of the thermoplastic resin-containing particles 5 was 40 μm. The amount of the ethylene oxide / propylene oxide copolymer in the thermoplastic resin-containing particles 5 was 7% by mass.

[Example 6]
The thermoplastic resin-containing particles 6 are obtained in the same manner as in Example 4 except that the first solvent and the second solvent are water and the temperature of the first solvent when mixing with the kneaded product is 27 ° C. It was. The average particle diameter of the thermoplastic resin-containing particles 6 was 50 μm. The amount of the ethylene oxide / propylene oxide copolymer in the thermoplastic resin-containing particles 6 was 0.1% by mass.

[Comparative Example 1]
45 parts by mass of polyamide resin (manufactured by Daicel-Evonik Co., Ltd., Daiamide L1600, elastic modulus 1430 MPa) and 55 parts by mass of ethylene oxide (manufactured by Meisei Chemical Industry Co., Ltd., R1000, heat resistant temperature 120 ° C., molecular weight 25 to 400,000) did. The softening point of the mixture was 160 ° C. The mixture was heated to 180 ° C. and kneaded for 20 minutes with a small kneader (Xplore, MC15).
The kneaded product was cooled to 30 ° C. and then mixed with 10 L of ethyl acetate (first solvent) at 70 ° C. Thereby, ethylene oxide was dissolved in ethyl acetate. Thereafter, the solution was centrifuged, and thermoplastic resin-containing particles containing a polyamide resin were collected.
Further, the thermoplastic resin-containing particles were washed with ethyl acetate (second solvent) to obtain thermoplastic resin-containing particles 7 containing a polyamide resin. The average particle diameter of the thermoplastic resin-containing particles 7 was 30 μm. The amount of ethylene oxide in the thermoplastic resin-containing particles 7 was 10% by mass.

[Comparative Example 2]
45 parts by mass of polypropylene resin (manufactured by Sun Aroma Co., Ltd., PM600A, elastic modulus 1320 MPa) and 55 parts by mass of polyethylene glycol (manufactured by Meisei Chemical Industry Co., Ltd., R150, heat resistant temperature 120 ° C., molecular weight 20000) were mixed. The softening point of the mixture was 145 ° C. The mixture was heated to 160 ° C. and kneaded with a small kneader (Xplore, MC15).
The kneaded product was cooled to 30 ° C. and then mixed with 10 L of ethyl acetate (first solvent) at 70 ° C. As a result, polyethylene glycol was dissolved in ethyl acetate. Thereafter, the solution was centrifuged, and thermoplastic resin-containing particles containing polypropylene resin were collected.
Furthermore, the thermoplastic resin-containing particles were washed with ethyl acetate (second solvent) to obtain thermoplastic resin-containing particles 8 containing a polypropylene resin. The average particle diameter of the thermoplastic resin-containing particles 8 was 20 μm. The amount of polyethylene glycol in the thermoplastic resin-containing particles 8 was 10% by mass.

[Comparative Example 3]
A polyamide resin is included as in Comparative Example 2 except that a polyamide resin (manufactured by Daicel-Evonik, Daiamide L1600, elastic modulus 1430 MPa) is used instead of the polypropylene resin (manufactured by Sun Allomer, PM600A, elastic modulus 1320 MPa). Thermoplastic resin-containing particles 9 were obtained. The average particle diameter of the thermoplastic resin-containing particles 9 was 20 μm. The amount of polyethylene glycol in the thermoplastic resin-containing particles 9 was 10% by mass.

[Comparative Example 4]
45 parts by mass of a metallocene polypropylene resin (manufactured by Nippon Polypro Co., Ltd., WMH02, elastic modulus 2300 MPa) and 55 parts by mass of polyethylene glycol (manufactured by Meisei Chemical Industry Co., Ltd., R150, heat resistant temperature 120 ° C., molecular weight 20000) were mixed. The softening point of the mixture was 160 ° C.
The mixture was heated to 200 ° C. and kneaded with a small kneader (manufactured by Xplore, MC15). As a result, the polypropylene resin did not become particles.

2. Evaluation About the thermoplastic resin containing particle (resin composition for three-dimensional modeling) produced by each Example and the comparative example, or the state in the manufacturing stage, it evaluated as follows. The results are shown in Table 1.

[Evaluation of solubility of water-soluble resin]
The solubility of the water-soluble resin in the first solvent when producing the thermoplastic resin-containing particles was visually evaluated. And it evaluated as follows.
A: Within a few minutes, the kneaded product (lumps) did not remain in water.
○: The kneaded product (lumps) was not left in the water over several hours.
(Triangle | delta): It became the state which the kneaded material (lump) did not remain in water over several days.

[Solvent recyclability]
The recyclability of the first solvent and the second solvent was evaluated based on the fraction of the solvent. Evaluation was performed as follows.
(Double-circle): A solvent and water-soluble resin were isolate | separated by the distillation method, it was possible to fractionate a solvent, and the fractionation rate was 70% or more.
A: The solvent and the water-soluble resin were separated by a distillation method, and the solvent could be fractionated, and the fractionation rate was 10% or more and less than 70%.
X: Solvent separation was impossible or the fractionation rate was less than 10%.

[Water-soluble resin amount]
The water-soluble resin in the obtained thermoplastic resin-containing particles was quantified by comparing the peak derived from the thermoplastic resin and the peak derived from the water-soluble resin by NMR measurement.

[Evaluation of tensile strength (breaking elongation)]
(Production of 3D objects)
The thermoplastic resin-containing particles (resin composition for three-dimensional modeling) produced in the above-described examples and comparative examples were spread on a modeling stage placed on a hot plate to form a thin layer having a thickness of 0.1 mm. By adjusting the temperature of the hot plate, each was heated to a preheating temperature of 160 ° C. This thin layer was irradiated with laser light in a range of 15 mm long × 20 mm wide from a CO ₂ laser equipped with a galvanometer scanner for YAG wavelength under the following conditions to produce a shaped article layer. The above steps were repeated until the height reached 55 mm, and each of the stacked three-dimensional objects was manufactured.
<Laser beam emission conditions>
Laser output: 12W
Laser light wavelength: 10.6 μm
Beam diameter: 170 μm on the surface of the thin layer
<Laser beam scanning conditions>
Scanning speed: 2000mm / sec
Number of lines: 1 line

(Measurement of tensile strength (elongation at break))
With respect to the three-dimensional model manufactured as described above, the tensile strength was measured using a universal testing machine model-5582 manufactured by Inslon Corporation under the conditions of a tensile speed of 1 mm / min, a gripping tool distance of 60 mm, and a test temperature of 23 ° C. And the said tensile strength was evaluated as follows.
A: Elongation at break is 10% or more (suitable for orthosis)
○: Elongation at break is 5% or more and less than 10% (can be used for orthoses)
X: Elongation at break is less than 5% (cannot be used for braces)

As shown in Table 1, when a thermoplastic resin-containing particle is produced by mixing a thermoplastic resin having a relatively high elastic modulus and a water-soluble resin having a heat resistant temperature of 130 ° C. or higher and 200 ° C. or lower, In any case, thermoplastic resin-containing particles having a desired average particle diameter could be obtained (Examples 1 to 6). Moreover, when the three-dimensional molded item was produced from the three-dimensional molded resin composition containing the thermoplastic resin-containing particles, the elongation at break was excellent. It is considered that even when a small amount of the water-soluble resin is contained, the fusion property of the interface at the time of three-dimensional modeling is improved and the elongation at break is improved. Moreover, when the surface of the three-dimensional molded item was observed with a polarizing microscope, crystallization of the surface was also suppressed by the water-soluble resin. In addition, when the organic solvent was used as the first solvent or the second solvent, it was possible to recycle after recovery (Examples 1, 2, 4, and 5).

In contrast, when a thermoplastic resin-containing particle is prepared by mixing a thermoplastic resin having a relatively high elastic modulus and a water-soluble resin having a heat resistant temperature of less than 130 ° C., the thermoplastic resin is sufficiently dispersed. In addition, the water-soluble resin was decomposed. That is, when these were combined, desired thermoplastic resin-containing particles could not be obtained (Comparative Example 4).

Further, when thermoplastic resin-containing particles are produced by mixing a thermoplastic resin having a relatively low elastic modulus and a water-soluble resin having a heat-resistant temperature of less than 130 ° C., the desired thermoplastic resin-containing particles are obtained. The evaluation of elongation at break was low, and it was difficult to apply it to uses requiring durability such as an orthosis (Comparative Examples 1 to 3).

This application claims priority based on Japanese Patent Application No. 2018-043183 filed on Mar. 9, 2018. All the contents described in the application specification are incorporated herein by reference.

According to the three-dimensional modeling resin composition including the thermoplastic resin-containing particles produced by the method according to the present invention, the three-dimensional modeling object is accurately formed by any method such as the powder bed fusion bonding method or the MJF method. It is possible. Moreover, the three-dimensional molded item obtained has both high mechanical strength and high elastic modulus. Therefore, it is considered that the present invention contributes to further spread of the three-dimensional modeling method.

Claims (18)

A mixing step of mixing a thermoplastic resin and a water-soluble resin having a heat resistant temperature of 130 ° C. or higher and 200 ° C. or lower to obtain a mixture;
A kneading step of heating the mixture above the softening point of the mixture and kneading to obtain a kneaded product;
A cooling step for cooling the kneaded material below the softening point;
After the cooling step, the kneaded product is mixed with a first solvent containing water or an organic solvent, and a dissolving step of dissolving the water-soluble resin in the first solvent;
A separation step of separating the solid content and obtaining thermoplastic resin-containing particles after the dissolution step. The water-soluble resin contains an ethylene oxide / propylene oxide copolymer,
The manufacturing method of the thermoplastic resin containing particle | grains of Claim 1. The ethylene oxide / propylene oxide copolymer has a weight average molecular weight of 50,000 to 150,000,
The manufacturing method of the thermoplastic resin containing particle | grains of Claim 2. The thermoplastic resin comprises polypropylene;
The method for producing thermoplastic resin-containing particles according to any one of claims 1 to 3. The elastic modulus at 27 ° C. of the polypropylene is 1500 MPa or more and 2500 MPa or less.
The manufacturing method of the thermoplastic resin containing particle | grains of Claim 4. The mixing step is a step of mixing the thermoplastic resin and the water-soluble resin at a mass ratio of 1: 9 to 5: 5 to obtain the mixture.
The method for producing thermoplastic resin-containing particles according to any one of claims 1 to 5. After the separation step, further includes a washing step of washing the thermoplastic resin-containing particles with a second solvent containing water or an organic solvent.
The method for producing thermoplastic resin-containing particles according to any one of claims 1 to 6. The heat according to claim 7, wherein the washing step is a step of washing the thermoplastic resin-containing particles until the content of the water-soluble resin with respect to the mass of the thermoplastic resin-containing particles is 5% by mass or less. A method for producing plastic resin-containing particles. The washing step is a step of washing the thermoplastic resin-containing particles with an organic solvent;
After the washing step, further comprising a second solvent recovery step of separating the organic solvent and the water-soluble resin and recovering the organic solvent;
The manufacturing method of the thermoplastic resin containing particle | grains of Claim 7 or 8. The dissolving step is a step of dissolving the water-soluble resin in an organic solvent;
After the dissolving step, further comprising a first solvent recovery step of separating the organic solvent and the water-soluble resin and recovering the organic solvent;
The method for producing thermoplastic resin-containing particles according to any one of claims 1 to 9. The organic solvent included in the first solvent and / or the organic solvent included in the second solvent is selected from the group consisting of acetonitrile, dichloromethane, methanol, ethanol, toluene, tetrahydrofuran, acetone, and ethyl acetate.
The manufacturing method of the thermoplastic resin containing particle | grains of Claim 9 or 10. A thermoplastic resin;
A water-soluble resin having a heat-resistant temperature of 130 ° C. or higher and 200 ° C. or lower;
Including thermoplastic resin-containing particles, wherein the amount of the water-soluble resin is 0.001% by mass or more and 5% by mass or less.
Three-dimensional modeling resin composition. The water-soluble resin contains an ethylene oxide / propylene oxide copolymer,
The resin composition for three-dimensional modeling according to claim 12. The ethylene oxide / propylene oxide copolymer has a weight average molecular weight of 50,000 to 150,000,
The resin composition for three-dimensional modeling according to claim 13. The thermoplastic resin comprises polypropylene;
The resin composition for three-dimensional modeling according to any one of claims 12 to 14. The elastic modulus at 27 ° C. of the polypropylene is 1500 MPa or more and 2500 MPa or less.
The resin composition for three-dimensional model | molding of Claim 15. A thin layer forming step of forming a thin layer comprising the resin composition for three-dimensional modeling according to any one of claims 12 to 16;
A laser beam irradiation step of selectively irradiating the thin layer with a laser beam to form a shaped article layer in which a plurality of the thermoplastic resin-containing particles are melt-bonded;
Including
The thin layer forming step and the laser light irradiation step are repeated a plurality of times to form a three-dimensional modeled object by laminating the modeled object layer,
Manufacturing method of a three-dimensional molded item. A thin layer forming step of forming a thin layer comprising the resin composition for three-dimensional modeling according to any one of claims 12 to 16;
A fluid application step of applying a binding fluid containing an energy absorber to a specific region of the thin layer;
An energy irradiation step of irradiating the thin layer after the fluid application step with energy and forming a shaped article layer in which the thermoplastic resin-containing particles in the region where the binding fluid is applied are melted;
Including
The thin layer forming step, the fluid application step, and the energy irradiation step are repeated a plurality of times to form a three-dimensional modeled object by laminating the modeled object layer,
Manufacturing method of a three-dimensional molded item.