JP7136186B2 - Method for producing thermoplastic resin-containing particles, resin composition for three-dimensional modeling, and method for producing three-dimensional object using the same - Google Patents

Description

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

In recent years, various methods have been developed to relatively easily manufacture three-dimensional objects with complicated shapes, and rapid prototyping and rapid manufacturing using such methods have attracted attention.

Conventionally, these modeled object manufacturing methods have been widely used in the field of modeling, but in recent years there has been an active movement to apply these methods directly to manufacturing. For example, the production of functional prostheses and the like is also under consideration. However, prostheses and the like are required to have high mechanical strength, thin wall thickness, and high elastic modulus.

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

One method of manufacturing such three-dimensional objects is the powder bed fusion method. In the powder bed fusion method, resin particles are spread evenly to form a thin layer, and the thin layer is irradiated with laser light in a pattern (a pattern obtained by subdividing a three-dimensional object in the thickness direction). As a result, the resin particles in the region irradiated with the laser light are selectively melted and bonded. Further, resin particles are further spread over the obtained modeled article layer, and laser light irradiation is repeated in the same manner to obtain a three-dimensionally shaped article having a desired shape.

Another example of the method for producing a three-dimensional object using resin particles is the Multi Jet Fusion method (hereinafter also referred to as the "MJF method") (for example, Patent Document 1). In the MJF method, resin particles are first spread flat to form a thin layer. Then, in the thin layer, an energy absorbing agent or the like is applied to a region where the resin particles are to be melt-bonded (hereinafter also referred to as a “curing region”), and energy is irradiated. Further, resin particles are further spread over the obtained modeled article layer, and the same steps are repeated to obtain a three-dimensionally shaped article having a desired shape.

The physical properties of the three-dimensional object obtained by the above-described powder bed fusion method and MJF method greatly depend on the type and physical properties of the resin particles used. Resin particles have conventionally been prepared by, for example, dissolving a thermoplastic resin in a solvent heated to a high temperature and then precipitating the solution with stirring. However, resins with high mechanical strength and high elastic modulus generally have high melting temperatures. Therefore, when resin particles are prepared by this method, the solvent and the resin must be heated to a high temperature, resulting in a problem of low production efficiency.

On the other hand, a method of kneading a thermoplastic resin and a water-soluble resin has been proposed as a method for preparing resin particles used in the powder bed fusion method and the MJF method (for example, Patent Documents 1 and 2). . In this method, the desired thermoplastic resin-containing particles are obtained by dispersing the thermoplastic resin in the water-soluble resin by kneading and then removing the water-soluble resin. Polyethylene glycol, polyethylene oxide, and the like have been proposed as the water-soluble resin.

Japanese Patent Application Laid-Open No. 2006-321711 JP 2007-277546 A

However, it is difficult to disperse a highly viscous resin 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 Documents 1 and 2. rice field.

The present invention has been made in view of the above problems. That is, the present invention provides a method for efficiently producing thermoplastic resin-containing particles by a simple method, a resin composition for three-dimensional modeling containing the thermoplastic resin-containing particles obtained by the method, and three-dimensional object production using the same. It aims at providing 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 resistance temperature of 130 ° C. or higher and 200 ° C. or lower to obtain a mixture; a cooling step of cooling the kneaded product below the softening point; 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 added to the first solvent; 1. A method for producing thermoplastic resin-containing particles, comprising a dissolving step of dissolving in the solvent of No. 1, and a separating step of separating the solid content after the dissolving step to obtain thermoplastic resin-containing particles.

[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 or more and 150,000 or less.
[4] The method for producing thermoplastic resin-containing particles according to any one of [1] to [3], wherein the thermoplastic resin contains polypropylene.
[5] The method for producing thermoplastic resin-containing particles according to [4], wherein the polypropylene has an elastic modulus of 1500 MPa or more and 2500 MPa or less at 27°C.
[6] Any one 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. 3. The method for producing the thermoplastic resin-containing particles according to .

[7] The thermoplastic resin according to any one of [1] to [6], further comprising a washing step of washing the thermoplastic resin-containing particles with a second solvent containing water or an organic solvent after the separating step. A method for producing the contained particles.
[8] In [7], 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 weight of the thermoplastic resin-containing particles is 5% by mass or less. A method for producing the thermoplastic resin-containing particles described.
[9] The washing step is a step of washing the thermoplastic resin-containing particles with an organic solvent, and after the washing step, the organic solvent and the water-soluble resin are separated to recover the organic solvent. The method for producing thermoplastic resin-containing particles according to [7] or [8], further including 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 to recover the organic solvent. The method for producing thermoplastic resin-containing particles according to any one of [1] to [9], further comprising steps.
[11] to [9] or [10], wherein 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; A method for producing the thermoplastic resin-containing particles described.

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

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

The present invention provides the following method for manufacturing a three-dimensional object.
[17] A thin layer forming step of forming a thin layer containing the three-dimensional modeling resin composition according to any one of the above [12] to [16], and selectively irradiating the thin layer with laser light, and a laser light irradiation step of forming a modeled article layer in which a plurality of the thermoplastic resin-containing particles are melt-bonded, and the thin layer forming step and the laser light irradiation step are repeated multiple times to laminate the modeled article layers. A method for manufacturing a three-dimensional object, wherein the three-dimensional object is formed by
[18] 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] above; a step of applying a fluid to a specific region; and irradiating energy to the thin layer after the step of applying the fluid to form a modeled object layer in which the thermoplastic resin-containing particles in the region to which the bonding fluid is applied are melted. and an energy irradiation step, wherein 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 object by laminating the object layers. 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. Also provided are a resin composition for three-dimensional modeling containing the thermoplastic resin-containing particles obtained by the method, and a method for producing a three-dimensional object using the same.

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 resistance temperature of 130 ° C. or higher and 200 ° C. or lower, and kneading the mixture. A kneading step of obtaining a product, a cooling step of cooling the obtained kneaded product, a dissolving step of dissolving the water-soluble resin in the kneaded product in a first solvent, separating the solid content, and separating the thermoplastic resin-containing particles and a separation step of obtaining. The method for producing the thermoplastic resin-containing particles may optionally include a washing step of washing the obtained thermoplastic resin-containing particles with a second solvent. Moreover, a solvent recovery step of recovering the first solvent and the second solvent may be included after the dissolving step and the washing step.

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 the water-soluble resin in the form of particles. However, it is difficult to uniformly disperse a thermoplastic resin having a high viscosity or a thermoplastic resin having a high elastic modulus in polyethylene glycol or the like, and conventional methods cannot obtain desired thermoplastic resin-containing particles. was there.

In general, thermoplastic resins with high viscosity and high elastic modulus are considered to be dispersed in water-soluble resins such as polyethylene glycol by kneading for a long time or heating to a high temperature. be done. However, as a result of extensive studies by the present inventors, when a thermoplastic resin is kneaded together with polyethylene glycol or the like, the viscosity of the polyethylene glycol or the like is excessively lowered during kneading, making it difficult to mix with the thermoplastic resin, or the polyethylene glycol or the like decomposes. It became clear that If kneading is continued in such a state, it is difficult for the thermoplastic resin to form uniform particles. On the other hand, a water-soluble resin having a heat resistance temperature of 130° C. or more and 200° C. or less is less likely to excessively decrease in viscosity during kneading, and is less likely to be decomposed by heat. Therefore, it was found that the thermoplastic resin is easily dispersed uniformly, and the desired thermoplastic resin-containing particles can be obtained.

Each step of the method for producing thermoplastic resin-containing particles of the present invention will be described in detail below.

1-1. Mixing Step In the mixing step, a thermoplastic resin and a water-soluble resin having a heat resistance temperature of 130° C. or higher and 200° C. or lower are mixed to obtain a mixture. The method of mixing the thermoplastic resin and the water-soluble resin is not particularly limited, and can be carried out using a known mixing/stirring device. Further, the thermoplastic resin and the water-soluble resin may be mixed at room temperature or while being heated.

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 4:5 to More preferably 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 later-described kneading step. It becomes easy to disperse in the 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.

Although the thermoplastic resin is not particularly limited, it should be a relatively highly elastic thermoplastic resin from the viewpoint of sufficiently obtaining the effects of the present invention and from the viewpoint of increasing the elastic modulus of the resulting three-dimensional model. is preferred. Specifically, the elastic modulus of the thermoplastic resin at 27° C. is preferably 1400 MPa or more, more preferably 1700 MPa or more. On the other hand, when the elastic modulus is excessively high, it tends to be difficult to disperse in the water-soluble resin. Therefore, the elastic modulus of the thermoplastic resin at 27° C. is preferably 2500 MPa or less, more preferably 2300 MPa or less. The elastic modulus of a thermoplastic resin is measured using a tensile tester in accordance with ISO527-1:2017.

Examples of the thermoplastic resins 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 preferred, and polypropylene is particularly preferred, from the viewpoint of high elastic modulus and high mechanical strength. In addition, only 1 type may be used and a thermoplastic resin may be used in combination of 2 or more types.

Here, when the thermoplastic resin is polypropylene, the elastic modulus of polypropylene at 27° C. 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. More preferred. When the elastic modulus of polypropylene is within this range, it becomes easier to obtain a three-dimensionally shaped article with high versatility.

The shape of the thermoplastic resin to be mixed in this step is not particularly limited, and may be, for example, in the form of lumps, particles, or pellets.

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 resistance temperature of 130° C. or higher and 200° C. or lower, has water solubility, and has low compatibility with the thermoplastic resin. Here, in this 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 the storage modulus changes with a rheometer. value. Moreover, "having water solubility" refers to the case where 10 g or more is dissolved in 100 g of water.

From the viewpoint of uniformly dispersing the thermoplastic resin in the water-soluble resin in the later-described kneading step, it is preferable to select a water-soluble resin having fluid behavior similar to that of the thermoplastic 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 by a rheometer when the temperature is raised from 100°C to 200°C.

Specific examples of water-soluble resins include ethylene oxide/propylene oxide copolymers, polyacrylamide, and the like. One type of water-soluble resin may be used, or two or more types may be mixed and used. Among these, ethylene oxide/propylene oxide copolymers are particularly preferred from the viewpoints of being able to be dissolved in an organic solvent in the dissolving step described below and having high heat resistance.

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, even more preferably 50,000 to 100,000. The weight average molecular weight is the 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 become difficult to dissolve in water or an organic solvent. Further, 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 tend to be close to each other during kneading.

The ethylene oxide/propylene oxide copolymer may be obtained by copolymerizing an ethylene oxide monomer and a propylene oxide monomer. preferably 8:1 to 7:1, even more preferably 6:1 to 5:1. When the ethylene oxide monomer-derived structure is contained at a certain level or more, the solubility of the ethylene oxide/propylene oxide copolymer in water and organic solvents is improved in the dissolution step described later.

The shape of the water-soluble resin to be mixed in this step is also not particularly limited, and may be, for example, in the form of lumps, particles, or pellets.

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

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

Further, the kneading time is not particularly limited as long as the thermoplastic resin can be dispersed in the water-soluble resin until it has a desired average particle size. It can be usually 10 to 40 minutes, more preferably 10 to 30 minutes, even more preferably 15 to 20 minutes. If the kneading time is excessively long, the production efficiency may be lowered, or the water-soluble resin may be easily decomposed. On the other hand, if the kneading time is too short, it will be difficult to sufficiently disperse the thermoplastic resin.

In this step, the average particle size of the thermoplastic resin dispersed in the water-soluble resin is preferably about 20 to 100 μm, more preferably about 30 to 70 μm. preferable. If the average particle size of particles containing a thermoplastic resin (also referred to as “thermoplastic resin-containing particles” in the present application) is 100 μm or less, the thermoplastic resin-containing particles are used to produce a three-dimensional object with a fine structure. becomes possible. On the other hand, it is preferably 20 μm or more from the viewpoint of imparting sufficient fluidity to the thermoplastic resin-containing particles and improving handleability when producing a three-dimensional object. Moreover, it is preferable that the particle size distribution of the particle size 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, even more preferably 1.5 or less. The weight average molecular weight (Mw) and 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 tends to be low.

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

Here, the kneading method in this step is not particularly limited, and examples thereof include rolls, Banbury mixers, kneaders, single-screw extruders, twin-screw extruders, and the like. Among these, a twin-screw extruder is preferable from the viewpoint of making the average particle size of the obtained thermoplastic resin-containing particles uniform. The kneaded product after kneading may be left as a mass, but may be processed into various shapes such as sheet, strand, pellet, and the like.

1-3. Cooling Step After the kneading step, the kneaded material is cooled below its softening point. In this step, the kneaded product is preferably cooled to a temperature lower than the softening point by 110°C or more, and more preferably cooled to a temperature lower than the softening point by 120°C or more. Sufficient cooling in the cooling step solidifies the thermoplastic resin, making it difficult for the thermoplastic resin-containing particles (thermoplastic resin) to fuse together in the dissolution step, separation step, etc. described below. In addition, in the cooling step, it is preferable to cool the inside of the kneaded material to a uniform temperature.

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

1-4. Dissolving Step After the cooling step, the kneaded product is mixed with a first solvent containing water or an organic solvent to dissolve the water-soluble resin 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, and ethyl acetate. can be used as an organic solvent. The first solvent may contain one of these, or may contain two or more of them. Among these, acetonitrile, dichloromethane, methanol, ethanol, toluene, tetrahydrofuran, and acetone are preferable from the viewpoint of being easy to dissolve the water-soluble resin.

As a method of dissolving the water-soluble resin in the first solvent, a method of immersing the kneaded product 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 material is immersed, the first solvent may be stirred if necessary.

The temperature of the first solvent when mixing the first solvent and the kneaded material may be a temperature equal to or lower 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 increasing the solubility of the water-soluble resin in the first solvent, and the kneaded product It is preferred to mix with On the other hand, when other solvents are used, the first solvent and the kneaded material may be mixed at room temperature.

The time for contacting the first solvent and the kneaded product is appropriately selected according to the solubility of the water-soluble resin, etc., but it can usually be 1 to 5 hours, 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 let When the amount of the water-soluble resin is 0.001% to 5% by mass or less, when a three-dimensional object is produced using the thermoplastic resin-containing particles, the strength of the three-dimensional object tends to be sufficiently high. 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 may be, for example, centrifugation, 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, if necessary, a washing step for washing the obtained thermoplastic resin-containing particles may be performed. The washing step can be, for example, a step of washing the thermoplastic resin-containing particles with a second solvent containing 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 thermoplastic resin in the thermoplastic resin-containing particles can be increased. As a result, it is possible to increase the strength of a three-dimensional object produced using the thermoplastic resin-containing particles.

The washing step can be, for example, a step of immersing the thermoplastic resin-containing particles separated in the separating step in the second solvent. As the second solvent, the same solvent as the above-described first solvent can be used. In addition, the first solvent and the second solvent may be the same or different.

Moreover, the temperature of the second solvent when performing the washing step may be a temperature equal to or lower 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 increasing the solubility of the water-soluble resin in the second solvent. On the other hand, when using another solvent, 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, when a three-dimensional object is produced using the thermoplastic resin-containing particles, the strength of the three-dimensional object tends to be sufficiently high. The amount of 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)
Further, after the above-described dissolving step and washing step, if necessary, a solvent recovery step of recovering the first solvent and/or the second solvent (collectively referred to simply as "solvent") may be performed. . 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, and for example, a method of separating the solvent and the water-soluble resin by distillation or the like and fractionating the solvent can be used. In addition, when the first solvent and the second solvent are the same, they may be collected together.

2. Resin composition for three-dimensional modeling The thermoplastic resin-containing particles produced by the method described above can be applied to a resin composition for three-dimensional modeling. A three-dimensional modeling resin composition containing thermoplastic resin-containing particles will be described below. The resin composition for three-dimensional modeling of the present invention is used in a method for producing three-dimensional objects by fusion-bonding thermoplastic resin-containing particles, such as the powder bed fusion method and the MJF method. The three-dimensional modeling resin composition can be a composition containing thermoplastic resin-containing particles and, if necessary, various additives, a flow agent, and the like.

The thermoplastic resin-containing particles contain a thermoplastic resin and a water-soluble resin having a heat resistance temperature of 130° C. or higher and 200° C. or lower, 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. It is 5% by mass or less. When the thermoplastic resin-containing particles contain 0.001% by mass or more of the water-soluble resin, the water-soluble resin in the thermoplastic resin-containing particles softens during molding, thereby improving the interfacial fusion bondability and breaking elongation. has the effect of improving Furthermore, the water-soluble resin has the effect of suppressing the crystallization of the surface of the modeled object. 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 produced three-dimensional object are improved. The amount of the water-soluble resin is more preferably 0.001 to 3% by mass, even more preferably 0.001 to 1% by mass. Since the thermoplastic resin-containing particles are produced by the method for producing thermoplastic resin-containing particles described above, detailed description thereof is omitted here.

The filler that is optionally contained in the three-dimensional modeling resin composition is not particularly limited as long as it does not impair the object and effect of the present invention. When a filler is contained in the resin composition for three-dimensional modeling, the energy to be irradiated during production of a three-dimensional modeled article can be easily transmitted, and the strength of the three-dimensional modeled article obtained can be 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, and carbon fibers; organic fillers such as polysaccharide nanofibers; and various polymers. The three-dimensional modeling resin composition may contain only one type of filler, or may contain two or more types.

The average particle size of the filler is preferably about 0.01 to 50 μm from the viewpoint of not interfering with the bonding of the thermoplastic resin-containing particles when producing a three-dimensional object. The average particle size of the filler is the volume average particle size, which is specified by measuring with a laser diffraction particle size distribution analyzer after removing the thermoplastic resin-containing particles from the three-dimensional modeling resin composition with a solvent or the like. can.

Among the above, the filler is a spherical particle having a diameter of 1 to 1000 nm from the viewpoint that the energy to be irradiated when producing a three-dimensional object has good conductivity and that the mechanical strength and ductility of the three-dimensional object can be easily increased. , tabular particles having a thickness of 1 to 1000 nm, or fibrous particles having a fiber diameter of 1 to 1000 nm.

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

When the filler is tabular grains, the thickness of the tabular grains is more preferably 50 to 500 nm, still more preferably 100 to 400 nm, and particularly preferably 150 to 300 nm. In the present specification, a tabular grain is a grain having two main planes facing each other, and the distance (thickness) between the two main planes is sufficiently small relative to the maximum and minimum diameters of the main planes. Say.

The shape of the main plane of the tabular grain may be circular, elliptical, or polygonal. The width of the major planes of tabular grains is preferably 1 to 10 μm, more preferably 2 to 8 μm. The ratio of the maximum diameter of the major planes to the thickness of the tabular grain (maximum diameter of the major planes/thickness) is preferably 5-15, more preferably 10-12. When the ratio between the maximum diameter of the major planes and the thickness of the tabular particles is within 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 particles include the above-mentioned layered clay minerals (e.g., kaolin; talc; mica; smectite minerals such as montmorillonite, beidellite, hectorite, saponite, nontronite, stevensite; vermiculite; bentonite; lamellar sodium silicates such as night and macanite; mica group clay minerals such as Na-type tetrasilicic fluoromica, Li-type tetrasilicic fluoromica, Na-type fluoroteniolite, Li-type fluoroteniolite, etc.). Such tabular grains may be obtained from natural minerals or chemically synthesized. Further, the tabular grains may be modified (surface-treated) 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. The fiber length of the fibrous filler is preferably 200-10000 nm, more preferably 250-10000 nm. When the fiber length is 10,000 nm or less, the appearance of the three-dimensional model tends to be good. In addition, when the fiber length is 200 nm or more, the strength of the three-dimensional object to be obtained tends to increase. Here, examples of fibrous fillers include carbon fibers, polysaccharide nanofibers, and the like.

The amount of the filler in the three-dimensional modeling resin composition 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. It is preferably from 15 to 20 parts by mass, and more preferably from 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 object obtained from the resin composition for three-dimensional modeling tends to increase. On the other hand, when the amount of the filler is 30 parts by mass or more, the ductility of the obtained three-dimensional molded article tends to decrease.

On the other hand, examples of various additives optionally contained in the three-dimensional modeling resin composition include antioxidants, acidic compounds and their derivatives, lubricants, ultraviolet absorbers, light stabilizers, nucleating agents, flame retardants, impact It includes modifiers, blowing agents, coloring agents, organic peroxides, spreading agents, adhesives, and the like. The three-dimensional modeling resin composition may contain only one of these, or may contain two or more of them. Moreover, these may be applied to the surface of the thermoplastic resin-containing particles within a range that does not impair the object of the present invention.

Also, the flow agent may be any material as long as it has a small coefficient of friction and self-lubricating properties. Examples of such flow agents include silicon dioxide and boron nitride. The three-dimensional modeling resin composition may contain only one type of flow agent, or may contain both types. The amount of the flow agent can be appropriately set within a range that improves the fluidity of the thermoplastic resin-containing particles and the like and sufficiently causes fusion bonding of the thermoplastic resin-containing particles. 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.

In addition, the resin composition for stereolithography used in the powder bed fusion bonding method described below may contain a laser absorber or the like. Examples of laser absorbers include carbon powder, nylon resin powder, pigments, dyes, 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. Method for producing a three-dimensional object As described above, the three-dimensional object forming resin composition can be used in a method for producing a three-dimensional object by the powder bed bonding fusion method or the MJF method. Three-dimensional modeling methods using the resin composition will be described below, but the present invention is not limited to these methods.

3-1. Method for manufacturing three-dimensional object by powder bed bonding melting method In the method for manufacturing three-dimensional object by powder bed bonding melting method, except for using the resin composition for three-dimensional modeling, it is performed in the same manner as the usual powder bed bonding melting method. can be done. Specifically, (1) a thin layer forming step of forming a thin layer containing the three-dimensional modeling resin composition described above, and (2) selectively irradiating the thin layer with a laser beam to obtain a thermoplastic resin containing and a laser beam irradiation step of forming a modeled article layer in which particles are fused and bonded together. By repeating the step (1) and the step (2) a plurality of times to stack the modeled object layers, a three-dimensional modeled object can be manufactured. In addition, the manufacturing method of the said three-dimensional model may include another process as needed, for example, the process of preheating the resin composition for three-dimensional shaping, etc. may be included.

・Thin layer forming step (step (1))
In this step, a thin layer containing the three-dimensional modeling resin composition is formed. For example, the three-dimensional modeling resin composition supplied from the powder supply section of the three-dimensional modeling apparatus is evenly spread on the modeling stage by a recoater. The thin layer may be formed directly on the modeling stage, or may be formed on the three-dimensional modeling resin composition that has already been spread, or on the modeled article layer that has already been formed. If necessary, a thin layer may be formed by mixing a flow agent or a laser absorber with the three-dimensional modeling resin composition.

The thickness of the thin layer should be the same as the thickness of the desired build layer. The thickness of the thin layer can be arbitrarily set according to the accuracy of the three-dimensional object to be manufactured, but is usually 0.01 mm or more and 0.30 mm or less. By setting the thickness of the thin layer to 0.01 mm or more, it is possible to prevent the three-dimensional modeling resin composition of the lower layer from being melted and bonded by laser light irradiation for forming the next modeled object layer. Furthermore, it becomes possible to spread evenly. In addition, by setting the thickness of the thin layer to 0.30 mm or less, the energy of the laser light is conducted to the bottom of the thin layer, and the three-dimensional modeling resin composition constituting the thin layer is sufficiently spread over the entire thickness direction. can be melt-bonded to From the above viewpoint, the thickness of the thin layer is more preferably 0.01 mm or more and 0.10 mm or less. In addition, from the viewpoint of sufficiently melting and bonding the resin composition for three-dimensional modeling and making it more difficult for cracks to occur in the modeled object layer, the difference between the thickness of the thin layer and the beam spot diameter of the laser beam, which will be described later, is 0.10 mm. It is preferable to set the thickness of the thin layer to be within the range.

・Laser light irradiation step (step (2))
In this step, of the thin layer containing the resin composition for three-dimensional modeling, a laser beam is selectively irradiated to the position where the modeled object layer is to be formed, and the thermoplastic resin-containing particles at the irradiated position are melted and bonded. Form a model layer. At this time, the resin composition for three-dimensional modeling (thermoplastic resin-containing particles) that has received the energy of the laser beam melts and bonds with the layer of the object that has already been formed, so adhesion between adjacent layers also occurs.

The wavelength of the laser light may be set within the range of wavelengths absorbed by the three-dimensional modeling resin composition (thermoplastic resin-containing particles). At this time, it is preferable to set the difference between the wavelength of the laser light and the wavelength at which the resin composition for three-dimensional modeling has the highest absorption rate. Since light is absorbed, it is preferable to use a laser beam with a wide wavelength band such as a CO ₂ laser. For example, the wavelength of the laser light can be, for example, 0.8 μm or more and 12 μm or less.

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

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

- About repetition of a process (1) and a process (2) In the case of manufacture of a three-dimensional molded article, the above-mentioned process (1) and a process (2) are repeated arbitrary times. As a result, the layers of the modeled object are laminated to obtain a desired three-dimensional modeled object.

Preheating step As described above, in the method for producing a three-dimensional object by the powder bed bonding melting method, a step of preheating the resin composition for three-dimensional modeling may be performed. 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)). Alternatively, both of these methods may be used.

The preheating temperature is lower than the melting temperature of the thermoplastic resin contained in the thermoplastic resin-containing particles so that the three-dimensional modeling resin composition (thermoplastic resin-containing particles) is not melt-bonded. The preheating temperature is appropriately selected according to the melting temperature of the thermoplastic resin. More preferably:

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 is possible to manufacture things.

・Other In addition, from the viewpoint of preventing the strength of the three-dimensional model from decreasing due to oxidation of the three-dimensional model resin composition during fusion bonding, at least step (2) is performed under reduced pressure or in an inert gas atmosphere. is preferred. The pressure when reducing the pressure is preferably 10 ⁻² Pa or less, more preferably 10 ⁻³ Pa or less. Examples of inert gases that can be used at this time include nitrogen gas and noble gases. 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 manufacturing process, it is preferable to perform both steps (1) and (2) under reduced pressure or in an inert gas atmosphere.

3-2. Method for producing a three-dimensional object by the MJF method The method for producing a three-dimensional object according to the present embodiment includes (1) a thin layer forming step of forming a thin layer containing the three-dimensional object forming resin composition described above, and (2) energy absorption. (3) applying energy to the thin layer after the fluid application step to apply a binding fluid containing an agent to a specific region of the thin layer; and an energy irradiation step of fusing and bonding the particles to form the model layer. In addition, the manufacturing method of the said three-dimensional model may include another process as needed, for example, the process of preheating the resin composition for three-dimensional shaping, etc. may be included.

(1) Thin Layer Forming Step In this step, a thin layer mainly containing the three-dimensional modeling resin composition described above is formed. A method for forming the thin layer is not particularly limited as long as a layer having a desired thickness can be formed. For example, this step can be a step of evenly spreading the resin composition for three-dimensional modeling supplied from the resin composition supply section of the three-dimensional modeling apparatus on the modeling stage by a recoater. The thin layer may be formed directly on the modeling stage, or may be formed so as to be in contact with the three-dimensional modeling resin composition that has already been spread or the modeled article layer that has already been formed.

The thickness of the thin layer should be the same as the thickness of the desired build layer. The thickness of the thin layer can be arbitrarily set according to the accuracy of the three-dimensional object to be manufactured, but is usually 0.01 mm or more and 0.30 mm or less. By setting the thickness of the thin layer to 0.01 mm or more, it is possible to prevent melting of the already-fabricated object layer by energy irradiation for forming a new object layer (energy irradiation in the energy irradiation step described later). can be prevented. Moreover, when the thickness of the thin layer is 0.01 mm or more, it becomes easier to evenly spread the resin composition for three-dimensional modeling. Further, by setting the thickness of the thin layer to 0.30 mm or less, it becomes possible to conduct energy (for example, infrared light) to the lower portion of the thin layer in the energy irradiation step described later. This makes it possible to melt the thermoplastic resin-containing particles in the 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 bonding fluid containing an energy absorbing agent is applied to specific regions of the thin layer formed in the thin layer forming step. At this time, if necessary, a stripping fluid that absorbs less energy than the bonding fluid may be applied to the areas not coated with the bonding fluid. Specifically, the binding fluid may be selectively applied to the positions where the model layer should be formed, and the release fluid may be applied to the regions where the model layer is not to be formed. By applying the release fluid adjacent to and around the area to which the bonding fluid is applied, the thermoplastic resin-containing particles are less likely to melt bond in the area to which the release fluid is applied. Either of the bonding fluid and the separating fluid may be applied first, but it is preferable to apply the bonding fluid first from the viewpoint of the dimensional accuracy of the three-dimensional molded article to be obtained.

The method of applying the bonding fluid and the detachment fluid is not particularly limited. can be applied, at least one of them is preferably applied by an inkjet method, and both are more preferably applied by an inkjet method.

The coating amount of the bonding fluid and the stripping 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 coating amounts of the bonding fluid and the releasing fluid are within the above ranges, the bonding fluid and the releasing fluid are applied to the three-dimensional modeling resin composition in the region where the modeled object layer is to be formed and the region where the modeled object layer is not formed. can be sufficiently impregnated, and a three-dimensional object with good dimensional accuracy can be formed.

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

The energy absorbing agent is not particularly limited as long as it can absorb the energy irradiated in the energy irradiation step described below and efficiently raise the temperature of the region coated with the bonding fluid. Specific examples of energy absorbers include infrared absorbers such as carbon black, ITO (indium tin oxide) and ATO (antimony tin oxide), cyanine dyes, phthalocyanine dyes mainly containing aluminum and zinc, various naphthalocyanine compounds, planar Infrared absorption dyes such as nickel dithiolene complexes having a four-coordinated structure, squalium dyes, quinone compounds, diimmonium compounds and azo compounds are included. Among these, the infrared absorbing agent is preferable, and carbon black is more preferable, from the viewpoint of versatility and ability to efficiently raise the temperature of the region coated with the bonding fluid.

Although the shape of the energy absorber is not particularly limited, it is preferably particulate. Also, the average particle size is preferably 0.1 to 1.0 μm, more preferably 0.1 to 0.5 μm. If the average particle size of the energy absorbing agent is excessively large, it becomes difficult for the energy absorbing agent to enter the interstices of the thermoplastic resin-containing particles when the bonding fluid is applied on a thin layer. On the other hand, when 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. becomes possible.

The coupling fluid preferably contains 0.1 to 10.0% by weight, more preferably 1.0 to 5.0% by weight, of the energy absorber. When the amount of the energy absorbing agent is 0.1% by mass or more, it is possible to sufficiently raise the temperature of the region coated with the bonding fluid in the energy irradiation step described later. On the other hand, when the amount of the energy absorbing agent is 10.0% by mass or less, the energy absorbing agent is less likely to agglomerate in the coupling fluid, and the application stability of the coupling fluid tends to be improved.

On the other hand, the solvent is not particularly limited as long as it is capable of dispersing the energy absorber and is difficult to dissolve the thermoplastic resin-containing particles (especially thermoplastic resin) in the three-dimensional modeling resin composition. can be

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

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

On the other hand, the stripping fluid applied in this step may be any fluid that absorbs relatively less energy than the bonding fluid, such as a fluid containing water as its main component.

The stripping fluid preferably contains 90% by mass or more of water, more preferably 95% by mass or more. When the amount of water in the stripping fluid is 90% by mass or more, it can be easily applied by, for example, an ink jet method.

(3) Energy Irradiation Step In this step, the thin layer after the fluid applying step, that is, the thin layer coated with the bonding fluid and the separating fluid is collectively irradiated with energy. At this time, in the area where the coupling fluid is applied, the energy absorber absorbs energy, and the temperature of the area partially increases. Then, only the thermoplastic resin-containing particles in the region are melted to form a model layer.

The type of energy irradiated in this step is appropriately selected according to the type of energy absorber contained in the coupling fluid. Specific examples of the energy include infrared light, white light, and the like. Among these areas, the thermoplastic resin-containing particles can be efficiently melted in the areas coated with the bonding fluid. On the other hand, in the region where the stripping fluid is applied, infrared light is preferable from the viewpoint that the temperature of the thin layer is less likely to rise, and light with a wavelength of 780 to 3000 nm is more preferable, and a wavelength of 800 to 2500 nm. is more preferable.

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

- Preheating step In the MJF method, a step of preheating the resin composition for stereolithography may be performed. 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)). Alternatively, both of these methods may be used. By performing preheating, it is possible to reduce the amount of energy irradiated in the (3) energy irradiation step. Furthermore, it is possible to efficiently form the modeled object layer in a short time. The preheating temperature is preferably lower than the melting temperature of the thermoplastic resin and lower than the boiling point of the solvent contained in the bonding fluid or the separating fluid applied in the (2) 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 or the boiling point of the solvent contained in the bonding fluid or the separating fluid, and preferably 30° C. to 5° C. °C lower temperature is more preferred. At this time, the heating time is preferably 1 to 60 seconds, more preferably 3 to 20 seconds. By setting the heating temperature and the heating time within the above ranges, the amount of energy irradiation in the (3) energy irradiation step can be reduced.

Specific examples of the present invention are described below. The scope of the present invention should not be construed as being limited by these examples.

1. Preparation of Thermoplastic Resin-Containing Particles (Resin Composition for Stereolithography) The elastic modulus of the thermoplastic resin was measured at 27° C. using a tensile tester in accordance with ISO527-1:2017.
Moreover, the weight average molecular weight of the water-soluble resin was specified by gel permeation (GPC, converted to styrene).
The heat-resistant temperature of the water-soluble resin was specified by raising the temperature with a rheometer until the storage modulus changed.
The softening point of the mixture was measured by a differential scanning calorimeter (DSC) by heating from 0°C to 200°C at a rate of 10°C/min, annealing for 10 minutes, cooling from 200°C to 0°C, and further to 0°C. It was specified by raising the temperature from to 200°C.

[Example 1]
Metallocene polypropylene resin (manufactured by Japan Polypropylene Corporation, WMH02, elastic modulus 2300 MPa) 45 parts by mass, ethylene oxide / propylene oxide (EO / PO) copolymer (manufactured by Meisei Chemical Industry Co., Ltd., EP1010N, heat resistance temperature 200 ° C., molecular weight about 100,000) and 55 parts by mass were mixed. 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 (manufactured by Xplore, MC15).
Then, after the kneaded product was cooled to 30°C, it was mixed with 10 L of ethyl acetate (first solvent) heated to 70°C. As a result, the ethylene oxide/propylene oxide copolymer was dissolved in ethyl acetate. After that, the solution was centrifuged to separate thermoplastic resin-containing particles containing polypropylene resin.
Further, the thermoplastic resin-containing particles were washed with ethyl acetate (second solvent) to obtain thermoplastic resin-containing particles 1 containing polypropylene resin. The average particle size of the thermoplastic resin-containing particles 1 was 40 μm. Moreover, the amount of the ethylene oxide/propylene oxide copolymer in the thermoplastic resin-containing particles 1 was 0.01% by mass.

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

[Example 3]
Thermoplastic resin-containing particles 3 were obtained in the same manner as in Example 1, except that water was used as the first solvent and the second solvent, and the temperature of the first solvent during mixing with the kneaded product was 27°C. rice field. The average particle diameter of the thermoplastic resin-containing particles 3 was 50 μm. Moreover, 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 (Daimid L1600, elastic modulus 1430 MPa, manufactured by Daicel-Evonik) and 55 parts by mass of ethylene oxide/propylene oxide copolymer (EP1010N, manufactured by Meisei Chemical Industry Co., Ltd., heat resistance temperature 200 ° C., molecular weight of about 100,000) and mixed. 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 (manufactured by Xplore, MC15).
Then, after the kneaded product was cooled to 30°C, it was immersed in ethyl acetate (first solvent) heated to 70°C. As a result, the ethylene oxide/propylene oxide copolymer was dissolved in ethyl acetate. After that, the solution was centrifuged to separate the thermoplastic resin-containing particles containing the polyamide resin.
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 size of the thermoplastic resin-containing particles 4 was 40 μm. Moreover, the amount of the ethylene oxide/propylene oxide copolymer in the thermoplastic resin-containing particles 4 was 0.01% by mass.

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

[Example 6]
Thermoplastic resin-containing particles 6 were obtained in the same manner as in Example 4, except that water was used as the first solvent and the second solvent, and the temperature of the first solvent during mixing with the kneaded product was 27°C. rice field. The average particle size of the thermoplastic resin-containing particles 6 was 50 μm. Moreover, the amount of the ethylene oxide/propylene oxide copolymer in the thermoplastic resin-containing particles 6 was 0.1% by mass.

[Comparative Example 1]
Polyamide resin (manufactured by Daicel-Evonik, Daiamide L1600, elastic modulus 1430 MPa) 45 parts by mass and ethylene oxide (manufactured by Meisei Chemical Industry Co., Ltd., R1000, heat resistance temperature 120 ° C., molecular weight 25 to 400,000) 55 parts by mass Mix. 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 (manufactured by Xplore, MC15).
Then, after the kneaded product was cooled to 30°C, it was mixed with 10 L of ethyl acetate (first solvent) at 70°C. This caused the ethylene oxide to dissolve in the ethyl acetate. After that, the solution was centrifuged to separate the thermoplastic resin-containing particles containing the polyamide resin.
Furthermore, 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. Moreover, 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 (PM600A, elastic modulus 1320 MPa, manufactured by SunAllomer Co., Ltd.) and 55 parts by mass of polyethylene glycol (R150, manufactured by Meisei Chemical Industry Co., Ltd., heat resistance 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 (manufactured by Xplore, MC15).
Then, after the kneaded product was cooled to 30°C, it was mixed with 10 L of ethyl acetate (first solvent) at 70°C. This caused the polyethylene glycol to dissolve in the ethyl acetate. After that, the solution was centrifuged to separate thermoplastic resin-containing particles containing polypropylene resin.
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 size of the thermoplastic resin-containing particles 8 was 20 μm. Moreover, the amount of polyethylene glycol in the thermoplastic resin-containing particles 8 was 10% by mass.

[Comparative Example 3]
Polyamide resin (manufactured by Daicel-Evonik, Daimid L1600, modulus of elasticity 1430 MPa) was used instead of polypropylene resin (manufactured by SunAllomer, PM600A, modulus of elasticity 1320 MPa). A thermoplastic resin-containing particle 9 was obtained. The average particle size of the thermoplastic resin-containing particles 9 was 20 μm. Moreover, 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 (WMH02, modulus of elasticity 2300 MPa, manufactured by Nippon Polypropylene Co., Ltd.) and 55 parts by mass of polyethylene glycol (R150, manufactured by Meisei Chemical Industry Co., Ltd., heat resistance temperature 120° C., molecular weight 20000) were mixed. The softening point of the mixture was 160°C.
When the mixture was heated to 200° C. and kneaded with a small kneader (manufactured by Xplore, MC15), the polypropylene resin did not become particulate.

2. Evaluation The thermoplastic resin-containing particles (three-dimensional modeling resin composition) produced in each example and comparative example, or the state at the production stage thereof, was evaluated as follows. Table 1 shows the results.

[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, no kneaded material (lumps) remained in the water.
◯: After several hours, no kneaded material (lumps) remained in the water.
Δ: Over several days, no kneaded material (lumps) remained in the water.

[Solvent recyclability]
The recyclability of the first solvent and the second solvent was evaluated by the solvent fractionation rate. Evaluation was performed as follows.
⊚: The solvent and water-soluble resin were separated by a distillation method, and the solvent could be fractionated, and the fractionation rate was 70% or more.
○: It was possible to separate the solvent and the water-soluble resin by distillation, and the fractionation rate was 10% or more and less than 70%.
x: Fractionation of the solvent was impossible, or the fractionation rate was less than 10%.

[Amount of water-soluble resin]
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 (elongation at break)]
(Production of three-dimensional object)
The thermoplastic resin-containing particles (three-dimensional modeling resin composition) produced in the above Examples and Comparative Examples were spread over a modeling stage placed on a hot plate to form a thin layer with a thickness of 0.1 mm. Each was heated to a preheating temperature of 160° C. by adjusting the temperature of the hot plate. Under the following conditions, this thin layer was irradiated with a laser beam from a CO ₂ laser equipped with a YAG wavelength galvanometer scanner in a range of 15 mm long×20 mm wide to prepare a model layer. The above steps were repeated until a height of 55 mm was reached to manufacture each of the stacked three-dimensional objects.
<Laser beam emission conditions>
Laser output: 12W
Wavelength of laser light: 10.6 μm
Beam diameter: 170 μm on thin layer surface
<Laser beam scanning conditions>
Scanning speed: 2000mm/sec
Number of lines: 1 line

(Measurement of tensile strength (elongation at break))
The tensile strength of the three-dimensional object produced as described above was measured using a universal testing machine model-5582 manufactured by Inslon Co., Ltd. under the conditions of a tensile speed of 1 mm/min, a gripper distance of 60 mm, and a test temperature of 23°C. And the said tensile strength was evaluated as follows.
◎: Elongation at break is 10% or more (suitable for braces)
○: Breaking elongation is 5% or more and less than 10% (can be used for braces)
×: Breaking elongation is less than 5% (cannot be used for braces)

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

On the other hand, when trying to produce thermoplastic resin-containing particles by mixing a thermoplastic resin with a relatively high elastic modulus and a water-soluble resin with a heat resistance temperature of less than 130° C., the thermoplastic resin is sufficiently dispersed. Moreover, the water-soluble resin decomposed. In other words, when these were combined, desired thermoplastic resin-containing particles could not be obtained (Comparative Example 4).

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

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

According to the three-dimensional modeling resin composition containing the thermoplastic resin-containing particles produced by the method according to the present invention, three-dimensional objects can be formed with high accuracy by any method such as the powder bed fusion bonding method and the MJF method. It is possible. In addition, the three-dimensional object obtained has both high mechanical strength and high elastic modulus. Therefore, it is believed that the present invention contributes to the further spread of stereolithography.

Claims (14)

A mixing step of mixing a thermoplastic resin and a water-soluble resin having a heat resistance temperature of 130° C. or higher and 200° C. or lower to obtain a mixture;
A kneading step of heating and kneading the mixture to a softening point or higher of the mixture to obtain a kneaded product;
a cooling step of cooling the kneaded product below the softening point;
After the cooling step, a dissolving step of mixing the kneaded product with a first solvent containing water or an organic solvent and dissolving the water-soluble resin in the first solvent;
After the dissolution step, a separation step of separating the solid content to obtain thermoplastic resin-containing particles;
including
The water-soluble resin contains an ethylene oxide/propylene oxide copolymer having a weight average molecular weight of 50000 or more and 150000 or less.
A method for producing thermoplastic resin-containing particles. wherein the thermoplastic resin comprises polypropylene;
The method for producing thermoplastic resin-containing particles according to claim 1 . The elastic modulus of the polypropylene at 27° C. is 1500 MPa or more and 2500 MPa or less.
The method for producing thermoplastic resin-containing particles according to claim 2 . 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.
A method for producing thermoplastic resin-containing particles according to any one of claims 1 to 3 . After the separation step, further comprising a washing step of washing the thermoplastic resin-containing particles with a second solvent containing water or an organic solvent.
A method for producing thermoplastic resin-containing particles according to any one of claims 1 to 4 . 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 weight 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,
7. The method for producing thermoplastic resin-containing particles according to claim 5 or 6 . The dissolving step is a step of dissolving the water-soluble resin in an organic solvent,
Further comprising a first solvent recovery step of separating the organic solvent and the water-soluble resin after the dissolving step and recovering the organic solvent,
A method for producing thermoplastic resin-containing particles according to any one of claims 1 to 7 . The organic solvent contained in the first solvent and/or the organic solvent contained in the second solvent is selected from the group consisting of acetonitrile, dichloromethane, methanol, ethanol, toluene, tetrahydrofuran, acetone, and ethyl acetate.
The method for producing thermoplastic resin-containing particles according to claim 7 or 8 . a thermoplastic resin;
a water-soluble resin having a heat resistance temperature of 130° C. or higher and 200° C. or lower;
containing 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,
The water-soluble resin contains an ethylene oxide/propylene oxide copolymer having a weight average molecular weight of 50000 or more and 150000 or less.
A resin composition for three-dimensional modeling. wherein the thermoplastic resin comprises polypropylene;
The resin composition for stereolithography according to claim 10. The elastic modulus of the polypropylene at 27° C. is 1500 MPa or more and 2500 MPa or less.
The resin composition for three-dimensional modeling according to claim 11 . A thin layer forming step of forming a thin layer containing the three-dimensional modeling resin composition according to any one of claims 10 to 12 ;
a laser beam irradiation step of selectively irradiating the thin layer with a laser beam to form a modeled object layer in which a plurality of the thermoplastic resin-containing particles are melt-bonded;
including
Repeating the thin layer forming step and the laser light irradiation step a plurality of times to form a three-dimensional object by stacking the object layers,
A method for manufacturing a three-dimensional object. A thin layer forming step of forming a thin layer containing the three-dimensional modeling resin composition according to any one of claims 10 to 12 ;
a fluid application step of applying a bonding fluid comprising an energy absorbing agent to specific areas of the thin layer;
an energy irradiation step of irradiating the thin layer after the fluid application step with energy to form a modeled object layer in which the thermoplastic resin-containing particles in the region to which the bonding fluid is applied are melted;
including
Repeating the thin layer forming step, the fluid applying step, and the energy irradiation step a plurality of times to form a three-dimensional modeled object by stacking the modeled object layers;
A method for manufacturing a three-dimensional object.