Resin mixture for 3d-printer manufacturing, 3d-printer manufacturing material, manufactured body, and manufacturing method

Abstract

Provided is a resin mixture for 3D-printer manufacturing, the mixture being capable of producing an 3D-printer manufacturing material that has excellent formability and is capable of producing a lightweight manufactured body. Provided is a resin mixture for 3D-printer manufacturing that contains a matrix resin and organic crosslinked hollow particles.

Description

Resin mixture for 3D printer modeling, material for 3D printer modeling, modeled object, and modeling method

[0001] The present invention relates to a resin mixture for 3D printer modeling, a material for 3D printer modeling, a modeled object, and a modeling method.

[0002] In recent years, 3D printer modeling technology (three-dimensional modeling technology) has been attracting attention as a method for manufacturing resin molded bodies. 3D printer modeling technology offers a high degree of design freedom, can produce a variety of objects with complex three-dimensional shapes, and can also reduce design time and costs, so it is being applied to an extremely wide range of applications.

[0003] For example, parts for mobile objects such as drones often have complex three-dimensional shapes and are sometimes manufactured using 3D printing technology. When manufacturing such parts, 3D printing materials are required to have excellent formability (i.e., the ability to reproduce complex three-dimensional shapes and obtain a molded object with sufficient strength). Meanwhile, mobile objects such as drones are also required to have improved operating times and lightweight parts.

[0004] For example, Patent Document 1 describes a method for manufacturing a three-dimensional object, which includes a layer-forming step of forming a layer using a three-dimensional modeling composition, and a binder liquid-applying step of applying a binder liquid containing a binder to a predetermined region of the layer, and which produces a three-dimensional object by sequentially repeating these steps, wherein the three-dimensional object is made of a material containing hollow particles having a first region and a second region as a hollow portion surrounded by the first region, and wherein the difference n1-n2 between the refractive index n1 of the material constituting the first region and the refractive index n2 of the material constituting the second region is 0.25 or more.

[0005] JP 2016-010914 A

[0006] However, after careful consideration by the present inventors, it was found that although the three-dimensional object in Patent Document 1 is composed of a material containing hollow particles having a first region and a second region as a hollow portion surrounded by the first region, there was a problem in that, depending on the method of 3D printer modeling, the weight reduction effect achieved by using hollow particles was not achieved.

[0007] An object of the present invention is to provide a resin mixture for 3D printer modeling that can provide a material for 3D printer modeling that has excellent modeling properties and can produce lightweight models.

[0008] The present inventors have conducted studies to achieve the above object and have found that the above object can be achieved by using organic crosslinked hollow particles as hollow particles in addition to a matrix resin, which has led to the completion of the present invention.

[0009] That is, according to the present invention, the following resin mixture for 3D printer modeling is provided.

[0010] [1] A resin mixture for 3D printer modeling, comprising a matrix resin and organic crosslinked hollow particles. [2] The apparent density of the organic crosslinked hollow particles is 0.2 to 0.9 g / cm ３ [3] The resin mixture for 3D printer modeling according to [1], wherein the content of the organic crosslinked hollow particles is 1 to 70 parts by weight per 100 parts by weight of the total content of the matrix resin and the organic crosslinked hollow particles. [4] The resin mixture for 3D printer modeling according to any one of [1] to [3], wherein the organic crosslinked hollow particles have a shell made of a shell polymer containing a crosslinkable monomer unit. [5] The resin mixture for 3D printer modeling according to any one of [1] to [4], wherein the shell polymer contains a heteroatom-containing crosslinkable monomer unit as the crosslinkable monomer unit.

[0011] The present invention also provides the following 3D printer modeling material, modeled object, and modeling method. [6] A 3D printer modeling material comprising the resin mixture for 3D printer modeling according to any one of [1] to [5]. [7] The 3D printer modeling material according to [6], which is used for fused deposition modeling 3D printer modeling. [8] The 3D printer modeling material according to [6] or [7], which is in a filament shape. [9] A modeled object obtained by 3D printer modeling using the 3D printer modeling material according to any one of [6] to [8].

[10] The modeled object according to [9], which is obtained by fused deposition modeling 3D printer modeling.

[11] A modeling method for 3D printer modeling using the 3D printer modeling material according to any one of [6] to [8].

[12] The modeling method according to

[11] , which performs 3D printer modeling using the fused deposition modeling 3D printer.

[0012] According to the present invention, it is possible to provide a resin mixture for 3D printer modeling that can provide a material for 3D printer modeling that has excellent modeling properties and can produce lightweight models.

[0013] FIG. 1 is a photograph showing the appearance of a 3D Benchy-shaped object obtained in Example 1.

[0014] <Resin Mixture for 3D Printer Modeling> The resin mixture for 3D printer modeling of the present invention contains a matrix resin and organic crosslinked hollow particles.

[0015] [Matrix Resin] The resin mixture for 3D printer modeling of the present invention contains a matrix resin.

[0016] The matrix resin may be any resin that can be used in 3D printer modeling, and is not particularly limited; however, thermoplastic resins are generally used. Specific examples of matrix resins include acrylonitrile-butadiene-styrene resins (ABS resins); acrylonitrile-styrene resins (AS resins); polylactic acid (PLA resins); polyolefin resins such as polypropylene and polyethylene; polyamide resins such as PA6, PA66, and PA12; polyimide resins such as polyimide, polyamideimide, and polyetherimide; polycarbonate resins; polystyrene resins; fluorine-based resins such as polyvinylidene fluoride and polytetrafluoroethylene; polyester resins; acrylic resins; polyvinyl chloride resins; polyether ketone ketone; poly(meth)acrylate; polyphenylene ether; polyphenylene sulfide; and silicone resins. These matrix resins can be used alone or in combination of two or more.

[0017] As the matrix resin, acrylonitrile-butadiene-styrene resin (ABS resin) and polylactic acid (PLA resin) are preferred from the viewpoint of small thermal shrinkage and easy production of a molded object with excellent reproducibility of the molded model. Furthermore, polylactic acid (PLA resin) is more preferred from the viewpoint of even smaller thermal shrinkage and easy production of a molded object with even better reproducibility of the molded model, while acrylonitrile-butadiene-styrene resin (ABS resin) is more preferred from the viewpoint of low density and easy production of a molded object with even lighter weight.

[0018] [Organic Crosslinked Hollow Particles] The resin mixture for 3D printer modeling of the present invention contains organic crosslinked hollow particles in addition to the matrix resin described above. The organic crosslinked hollow particles used in the present invention have a shell made of a shell polymer and a hollow portion.

[0019] The shell polymer has a three-dimensional crosslinked structure and is used to form the shell of the organic crosslinked hollow particles.

[0020] The shell polymer preferably contains a crosslinkable monomer unit. The crosslinkable monomer forming the crosslinkable monomer unit is a monomer having two or more polymerizable functional groups and forming a crosslink in the resin by a polymerization reaction. As the crosslinkable monomer, a compound having at least one ethylenically unsaturated bond as a polymerizable functional group is generally used.

[0021] The crosslinkable monomers that form the crosslinkable monomer units include crosslinkable hydrocarbon monomers and heteroatom-containing crosslinkable monomers.

[0022] The crosslinkable hydrocarbon monomer is not particularly limited, but examples thereof include bifunctional crosslinkable hydrocarbon monomers such as divinylbenzene, divinyldiphenyl, divinylnaphthalene, dicyclopentadiene, and ethylidenetetracyclododecene, with divinylbenzene being preferred. In addition, crosslinkable hydrocarbon monomers composed of polymers can also be used. Examples include polybutadiene, polyisoprene, styrene-butadiene block copolymers (SBS), and styrene-isoprene block copolymers (SIS).

[0023] The heteroatom-containing crosslinkable monomer is not particularly limited, and examples thereof include bifunctional heteroatom-containing crosslinkable monomers such as diallyl phthalate, allyl (meth)acrylate (meaning allyl acrylate and / or allyl methacrylate; the same applies hereinafter), ethylene glycol di(meth)acrylate, and pentaerythritol di(meth)acrylate; and trifunctional or higher functional heteroatom-containing crosslinkable monomers such as trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and dipentaerythritol poly(meth)acrylate.

[0024] Other examples of the heteroatom-containing crosslinkable monomer that can be used include polyisocyanate compounds such as tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, tetramethylxylylene diisocyanate, isophorone diisocyanate (IPDI), hydrogenated tolylene diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, m-phenylene diisocyanate, biphenylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, and dimers or trimers thereof. Furthermore, polyfunctional urethane (meth)acrylate compounds obtained by reacting a polyisocyanate compound with a hydroxyl group-containing (meth)acrylate having a hydroxyl group and a (meth)acryloyl group can also be used. Specific examples of hydroxyl group-containing (meth)acrylates include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, pentaerythritol tri(meth)acrylate, trimethylolpropane di(meth)acrylate, and dipentaerythritol penta(meth)acrylate; isocyanuric acid di(meth)acrylic acid esters, and ethylene oxide and caprolactone modified versions of these.

[0025] Of these, the heteroatom-containing crosslinkable monomer is preferably ethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol poly(meth)acrylate, or pentaerythritol tri(meth)acrylate, more preferably ethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, or pentaerythritol tetra(meth)acrylate, and even more preferably ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate, or pentaerythritol tetramethacrylate.

[0026] As the crosslinkable monomer, a crosslinkable hydrocarbon monomer, ethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol poly(meth)acrylate, and pentaerythritol tri(meth)acrylate are preferred, divinylbenzene, ethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and pentaerythritol tetra(meth)acrylate are more preferred, and divinylbenzene, ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate, and pentaerythritol tetramethacrylate are even more preferred.

[0027] The crosslinkable monomers can be used alone or in combination of two or more. In the organic crosslinked hollow particles used in the present invention, the shell polymer preferably contains a bifunctional crosslinkable monomer unit and a trifunctional or higher functional crosslinkable monomer unit, more preferably a bifunctional crosslinkable monomer unit and a trifunctional or higher functional heteroatom-containing crosslinkable monomer unit, and even more preferably a bifunctional heteroatom-containing crosslinkable monomer unit and a trifunctional or higher functional heteroatom-containing crosslinkable monomer unit. The trifunctional or higher functional crosslinkable monomer is not particularly limited, but is preferably a trifunctional to hexafunctional crosslinkable monomer, more preferably a trifunctional to pentafunctional crosslinkable monomer, and even more preferably a trifunctional to tetrafunctional crosslinkable monomer. Furthermore, in the organic crosslinked hollow particles used in the present invention, the shell polymer can also contain a crosslinkable hydrocarbon monomer unit and a heteroatom-containing crosslinkable monomer unit.

[0028] The shell polymer may consist essentially of crosslinkable monomer units alone, or may contain monofunctional monomer units in addition to crosslinkable monomer units.

[0029] The monofunctional monomer forming the monofunctional monomer unit is a monomer having only one polymerizable functional group, and a compound having an ethylenically unsaturated bond as the polymerizable functional group is generally used. Examples of the monofunctional monomer forming the monofunctional monomer unit include monofunctional hydrocarbon monomers and heteroatom-containing monofunctional monomers.

[0030] The monofunctional hydrocarbon monomer is not particularly limited, but examples thereof include aromatic vinyl monomers such as styrene, ethylvinylbenzene, vinyltoluene, α-methylstyrene, p-methylstyrene, and halogenated styrene; monoolefin monomers such as ethylene, propylene, butylene, and 4-methyl-1-pentene; and diene monomers such as butadiene and isoprene. Of these, styrene and ethylvinylbenzene are preferred.

[0031] The heteroatom-containing monofunctional monomer is not particularly limited, but examples thereof include hydrophilic monofunctional monomers; acrylic monovinyl monomers such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, and glycidyl (meth)acrylate; carboxylic acid vinyl ester monomers such as vinyl acetate; halogenated vinyl monomers such as vinyl chloride; halogenated vinylidene monomers such as vinylidene chloride; vinylpyridine monomers; urethane (meth)acrylate, and allyl glycidyl ether.

[0032] The hydrophilic monofunctional monomer preferably has a solubility in water of 1% by mass or more. The hydrophilic monofunctional monomer is not particularly limited, but examples thereof include monofunctional monomers having a hydrophilic group, such as acid group-containing monomers, hydroxyl group-containing monomers, amide group-containing monomers, and polyoxyethylene group-containing monomers.

[0033] The term "acid group-containing monomer" refers to a monomer containing an acid group. The acid group referred to here includes both a proton-donating group (Brønsted acid group) and an electron pair-accepting group (Lewis acid group). The acid group-containing monomer is not particularly limited as long as it has an acid group, and examples thereof include carboxyl group-containing monomers and sulfonic acid group-containing monomers. Examples of carboxyl group-containing monomers include ethylenically unsaturated carboxylic acid monomers such as acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, itaconic acid, fumaric acid, maleic acid, and butenetricarboxylic acid; and monoalkyl esters of unsaturated dicarboxylic acids such as monoethyl itaconate, monobutyl fumarate, and monobutyl maleate. Examples of sulfonic acid group-containing monomers include styrenesulfonic acid.

[0034] Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.

[0035] Examples of the amide group-containing monomer include acrylamide and dimethylacrylamide.

[0036] Examples of polyoxyethylene group-containing monomers include methoxypolyethylene glycol (meth)acrylate.

[0037] The monofunctional monomer units may be used either alone or in combination of two or more.

[0038] The content of the crosslinkable monomer unit in the shell polymer is not particularly limited, but is preferably 20 to 100% by mass, more preferably 40 to 100% by mass, even more preferably 60 to 100% by mass, and particularly preferably 80 to 100% by mass. By having the content of the crosslinkable monomer within the above range, a dense covalent bond network is formed in the shell, suppressing the occurrence of interconnected pores and shell defects in the shell. As a result, the resulting 3D printer modeling material can produce even lighter models while maintaining excellent modeling properties.

[0039] The content of the monofunctional monomer unit in the shell polymer is not particularly limited, but is preferably 0 to 80% by mass, more preferably 0 to 60% by mass, even more preferably 0 to 40% by mass, and particularly preferably 0 to 20% by mass.

[0040] The shell polymer may contain a heteroatom-containing monomer unit. Examples of the heteroatom-containing monomer that forms the heteroatom-containing monomer unit include the heteroatom-containing crosslinkable monomer and the heteroatom-containing monofunctional monomer described above. The content of the heteroatom-containing monomer unit in the shell polymer is not particularly limited, but is preferably 1 to 99% by mass, more preferably 5 to 95% by mass, and even more preferably 10 to 90% by mass.

[0041] The shell polymer is not limited to the above-mentioned ones, as long as it has a three-dimensional crosslinked structure and can form the shell of the organic crosslinked hollow particles. The shell polymer may be, for example, a phenolic resin, a melamine resin, a urea resin, an unsaturated polyester resin, an epoxy resin, a polyurethane resin, a silicon resin, an alkyd resin, a thermosetting modified polyphenylene ether resin, a thermosetting polyimide resin, a benzoxazine resin, a urea resin, an allyl resin, an aniline resin, a maleimide resin, a bismaleimide triazine resin, a liquid crystalline polyester resin, a vinyl ester resin, an unsaturated polyester resin, a cyanate ester resin, or a polyetherimide resin.

[0042] The organic crosslinked hollow particles used in the present invention are particles having a shell (outer shell) containing the above-mentioned shell polymer and a hollow portion surrounded by the shell. In the present invention, the hollow portion is a void space clearly distinguishable from the shell of the organic crosslinked hollow particle formed by a resin. The organic crosslinked hollow particles used in the present invention may have one or more hollow portions, but preferably have only one hollow portion in order to maintain a good balance between high porosity and mechanical strength.

[0043] The organic crosslinked hollow particles used in the present invention usually have a shell that has no interconnected pores or shell defects, and the hollow portion is isolated from the outside of the particle by the shell, but the shell may have one or more interconnected pores, and the hollow portion may communicate with the outside of the particle via the interconnected pores. Furthermore, the shell of the organic crosslinked hollow particles, and when the particles have two or more hollow portions, the partition walls separating adjacent hollow portions, may be porous. In this case, the hollow portions have a size that allows them to be clearly distinguished from the numerous minute spaces uniformly dispersed within the porous structure.

[0044] The hollow space of the organic crosslinked hollow particles used in the present invention may be filled with a gas such as air, or may contain a solvent.

[0045] The shape of the organic crosslinked hollow particles used in the present invention is not particularly limited as long as a hollow portion is formed inside. The outer shape of the organic crosslinked hollow particles is not particularly limited, but a spherical shape is preferred from the viewpoint of ease of production.

[0046] The external shape of the organic crosslinked hollow particles can be confirmed, for example, by observing the particles with an SEM or a TEM, and the internal shape of the organic crosslinked hollow particles can be confirmed, for example, by observing the cross section of the particles with an SEM or a TEM.

[0047] The true density of the organic crosslinked hollow particles used in the present invention is not particularly limited, but is preferably 0.95 to 1.4 g / cm ３ is preferably 1.0 to 1.3 g / cm ３ It is more preferable that the true density of the organic crosslinked hollow particles means the density of only the shell portion of the organic crosslinked hollow particles. The true density of the organic crosslinked hollow particles can be adjusted by adjusting the monomer composition of the shell polymer.

[0048] The apparent density of the organic crosslinked hollow particles used in the present invention is 0.2 to 0.9 g / cm ３ is preferably 0.25 to 0.8 g / cm ３ From the viewpoint of obtaining a lighter shaped body, the apparent density of the organic crosslinked hollow particles is more preferably 0.25 to 0.7 g / cm. ３ More preferably, it is 0.25 to 0.6 g / cm ３ It is particularly preferable that the density is 0.25 to 0.5 g / cm ３ On the other hand, from the viewpoint of further improving the modeling properties of the resulting 3D printer modeling material and increasing the mechanical strength of the resulting modeled body, the apparent density of the organic crosslinked hollow particles is preferably 0.3 to 0.8 g / cm. ３ More preferably, it is 0.35 to 0.8 g / cm ３ It is particularly preferable that the density is 0.4 to 0.8 g / cm ３ It is most preferable that:

[0049] The apparent density of the organic crosslinked hollow particles refers to the density of the entire organic crosslinked hollow particles, including the shell and hollow portions of the organic crosslinked hollow particles. The apparent density of the organic crosslinked hollow particles can be adjusted by adjusting the monomer composition of the shell polymer, the types and amounts of the dispersion stabilizer and hydrophobic organic solvent used in producing the organic crosslinked hollow particles by suspension polymerization, the suspension conditions, etc.

[0050] The true density of the organic crosslinked hollow particles is specifically measured by the following method. The organic crosslinked hollow particles are crushed in advance, and then crushed into a 100 cm ３ Approximately 10 g of crushed pieces of the organic crosslinked hollow particles is filled into a measuring flask, and the mass of the crushed pieces is accurately weighed. Next, in the same manner as in the measurement of the apparent density, isopropanol is added to the measuring flask, and the mass of the isopropanol is accurately weighed. The true density (g / cm) of the organic crosslinked hollow particles is calculated based on the following formula (I): ３ ) is calculated. ３ ) = [mass of crushed pieces of organic crosslinked hollow particles] ÷ (100 - [mass of isopropanol] ÷ [density of isopropanol at measurement temperature]) (I)

[0051] Apparent density D of organic crosslinked hollow particles １ The measurement method is as follows: First, a volume of 100 cm ３ About 30 cm ３ The volumetric flask is filled with organic crosslinked hollow particles, and the mass of the filled organic crosslinked hollow particles is accurately weighed. Next, the volumetric flask filled with the organic crosslinked hollow particles is accurately filled with isopropanol up to the marked line, taking care not to introduce air bubbles. The mass of isopropanol added to the volumetric flask is accurately weighed, and the apparent density D of the organic crosslinked hollow particles is calculated based on the following formula (II): １ (g / cm ３ ) is calculated. １ (g / cm ３ ) = [mass of organic crosslinked hollow particles] ÷ (100 - [mass of isopropanol] ÷ [density of isopropanol at measurement temperature]) (II)

[0052] The volume average particle diameter (Dv) of the organic crosslinked hollow particles used in the present invention is not particularly limited, but is preferably 1 to 50 μm, more preferably 1.5 to 40 μm, and even more preferably 2 to 30 μm. The particle size distribution (Dv / Dn) (volume average particle diameter (Dv) / number average particle diameter (Dn)) of the organic crosslinked hollow particles used in the present invention is not particularly limited, but is preferably 1.02 to 2.00, and more preferably 1.04 to 1.60.

[0053] The volume average particle size (Dv) and particle size distribution (Dv / Dn) of the organic crosslinked hollow particles can be adjusted by, for example, adjusting the monomer composition of the shell polymer, the type and amount of a dispersion stabilizer used in producing the organic crosslinked hollow particles by suspension polymerization, or the suspension conditions.

[0054] The volume average particle diameter (Dv) and number average particle diameter (Dn) of the organic crosslinked hollow particles can be determined by, for example, measuring the particle diameter of the organic crosslinked hollow particles using a laser diffraction particle size distribution analyzer, calculating the number average and volume average, respectively, and using the resulting values ​​as the number average particle diameter (Dn) and volume average particle diameter (Dv) of the particles. The particle diameter distribution (Dv / Dn) is defined as the value obtained by dividing the volume average particle diameter (Dv) by the number average particle diameter (Dn).

[0055] The thermal decomposition onset temperature of the organic crosslinked hollow particles used in the present invention is preferably 210 to 400°C, more preferably 220 to 350°C. Having a thermal decomposition onset temperature within the above range can further improve the moldability of the resulting 3D printer modeling material and increase the mechanical strength of the resulting modeled object. The thermal decomposition onset temperature of the organic crosslinked hollow particles is the temperature at which a 5% weight loss occurs. The thermal decomposition onset temperature of the organic crosslinked hollow particles can be measured using a TG-DTA device in an air atmosphere under conditions of an air flow rate of 230 mL / min and a heating rate of 10°C / min.

[0056] The content of the organic crosslinked hollow particles is not particularly limited, but is preferably 1 to 70 parts by weight, more preferably 2 to 60 parts by weight, and even more preferably 5 to 55 parts by weight, per 100 parts by weight of the total content of the matrix resin and the organic crosslinked hollow particles. Furthermore, from the viewpoint of obtaining a lighter shaped object, the content of the organic crosslinked hollow particles may be 10 parts by weight or more, 20 parts by weight or more, or even 30 parts by weight or more, per 100 parts by weight of the total content of the matrix resin and the organic crosslinked hollow particles. On the other hand, from the viewpoint of further improving the shaping properties of the resulting 3D printer shaping material and increasing the mechanical strength of the resulting shaped object, the content of the organic crosslinked hollow particles may be 50 parts by weight or less, 40 parts by weight or less, or 35 parts by weight or less, per 100 parts by weight of the total content of the matrix resin and the organic crosslinked hollow particles.

[0057] In 3D printer modeling, as the nozzle discharging the 3D printer modeling material moves, the 3D printer modeling material may continuously produce thin fibers, a phenomenon known as stringing. This stringing tends to be less likely to occur when using a 3D printer modeling material made from a 3D printer modeling resin mixture with a low content of organic crosslinked hollow particles. Therefore, if it is necessary to suppress stringing, the content of the organic crosslinked hollow particles is preferably 50 parts by weight or less, more preferably 40 parts by weight or less, and even more preferably 35 parts by weight or less, per 100 parts by weight of the total content of the matrix resin and the organic crosslinked hollow particles.

[0058] [Method for Producing Organic Crosslinked Hollow Particles] The organic crosslinked hollow particles used in the present invention can be preferably produced by a production method including the following steps: (A) a mixed solution preparation step, (B) a suspension step, (C) a polymerization step, and (D) a solvent removal step.

[0059] That is, the organic crosslinked hollow particles used in the present invention can be preferably produced by a production method including: (A) a mixed solution preparation step of preparing a mixed solution containing polymerizable monomers including a crosslinkable monomer, a hydrophobic organic solvent, a polymerization initiator, and an aqueous medium; (B) a suspending step of suspending the mixed solution obtained in the mixed solution preparation step to prepare a suspension in which droplets of a polymerizable monomer composition containing the polymerizable monomer, the hydrophobic organic solvent, and the polymerization initiator are dispersed in the aqueous medium; (C) a polymerization step of subjecting the suspension obtained in the suspending step to a polymerization reaction to prepare a precursor composition containing precursor particles having hollow portions and encapsulating the hydrophobic organic solvent in the hollow portions; and (D) a solvent removal step of removing the hydrophobic organic solvent encapsulated in the precursor particles obtained in the polymerization step.

[0060] (A) Mixed Liquid Preparation Step The mixed liquid preparation step is a step of preparing a mixed liquid containing polymerizable monomers including a crosslinkable monomer, a hydrophobic organic solvent, a polymerization initiator, and an aqueous medium. The organic crosslinked hollow particles used in the present invention are preferably produced by a production method including such steps.

[0061] (Polymerizable Monomer) As the polymerizable monomer, the above-mentioned crosslinkable monomer and, if necessary, the above-mentioned monofunctional monomer are used. The monomer composition of the polymerizable monomer may be any monomer composition that can obtain the monomer composition of the target shell polymer.

[0062] The content of the polymerizable monomer (total amount of the crosslinkable monomer and the monofunctional monomer) in the mixed liquid prepared in the mixed liquid preparation step is not particularly limited, but from the viewpoint of the balance between particle size and mechanical strength, it is preferably 15 to 55 mass %, more preferably 25 to 50 mass %, relative to 100 mass % of the total mass of the components in the mixed liquid excluding the aqueous medium.

[0063] (Hydrophobic Organic Solvent) A non-polymerizable, poorly water-soluble organic solvent is used as the hydrophobic organic solvent, which acts as a spacer material that forms hollow spaces inside the particles.

[0064] The hydrophobic organic solvent is not particularly limited, but a hydrocarbon solvent can be suitably used, and specific examples thereof include saturated hydrocarbon solvents such as butane, pentane, normal hexane, cyclohexane, heptane, and octane; aromatic hydrocarbon solvents such as benzene, toluene, and xylene; and relatively volatile solvents such as carbon disulfide and carbon tetrachloride.

[0065] The content of the hydrophobic organic solvent in the mixed solution is preferably 50 to 500 parts by mass, more preferably 60 to 400 parts by mass, still more preferably 80 to 350 parts by mass, and particularly preferably 100 to 300 parts by mass, relative to 100 parts by mass of the total mass of the polymerizable monomers.

[0066] (Polymerization initiator) It is preferable to use an oil-soluble polymerization initiator as the polymerization initiator. By using an oil-soluble polymerization initiator as the polymerization initiator, the polymerization initiator can be suitably incorporated into the interior of droplets of the polymerizable monomer composition in the suspension obtained in the suspension step described below.

[0067] The oil-soluble polymerization initiator is not particularly limited as long as it is lipophilic and has a solubility in water of 0.2% by mass or less, and examples of the oil-soluble polymerization initiator include benzoyl peroxide, lauroyl peroxide, t-butyl peroxide-2-ethylhexanoate, t-butyl peroxydiethyl acetate, t-butyl peroxypivalate, 2,2'-azobis(2,4-dimethylvaleronitrile), and azobisisobutyronitrile.

[0068] The content of the polymerization initiator is preferably 0.1 to 10 parts by mass, more preferably 0.2 to 5 parts by mass, and even more preferably 0.5 to 3 parts by mass, relative to 100 parts by mass of the total mass of the polymerizable monomers in the mixed solution. By setting the content of the polymerization initiator within the above range, the polymerization reaction can be sufficiently progressed, and there is little risk of the polymerization initiator remaining after completion of the polymerization reaction, and there is also little risk of an unexpected side reaction proceeding.

[0069] (Aqueous Medium) The aqueous medium may be a medium selected from the group consisting of water, a hydrophilic solvent, and a mixture of water and a hydrophilic solvent.

[0070] The hydrophilic solvent is not particularly limited as long as it is sufficiently miscible with water and does not cause phase separation, and examples thereof include alcohols such as methanol and ethanol; tetrahydrofuran (THF); dimethyl sulfoxide (DMSO); and the like.

[0071] Among aqueous media, water is preferred due to its high polarity. When a mixture of water and a hydrophilic solvent is used, it is preferable that the polarity of the entire mixture is not too low, from the viewpoint of properly forming droplets of a polymerizable monomer composition containing a polymerizable monomer, a hydrophobic organic solvent, and a polymerization initiator. When a mixture of water and a hydrophilic solvent is used, it is preferable that the mixing ratio (mass ratio) of water to hydrophilic solvent is 99:1 to 50:50.

[0072] In addition, in the mixed solution preparation step, it is preferable to use a dispersion stabilizer in addition to the polymerizable monomer, the hydrophobic organic solvent, the polymerization initiator, and the aqueous medium. That is, the mixed solution preparation step is preferably a step of preparing a mixed solution containing the polymerizable monomer, the hydrophobic organic solvent, the polymerization initiator, the aqueous medium, and the dispersion stabilizer.

[0073] The dispersion stabilizer is a compound that disperses droplets of the polymerizable monomer composition in an aqueous medium in the suspension step described below, and may be either an inorganic dispersion stabilizer or an organic dispersion stabilizer.

[0074] Examples of inorganic dispersion stabilizers include colloidal silica, magnesium hydroxide, calcium phosphate, calcium carbonate, barium sulfate, calcium oxalate, calcium carbonate, magnesium carbonate, barium carbonate, tricalcium phosphate, aluminum hydroxide, magnesium hydroxide, ferric hydroxide, hydroxyapatite, diatomaceous earth, clay, and bentonite.

[0075] Examples of organic dispersion stabilizers include methyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl cellulose, and starch.

[0076] Among these, inorganic dispersion stabilizers are preferred from the viewpoint of having a high dispersion stabilizing effect and making it easier to control the particle size of droplets of a polymerizable monomer composition containing a polymerizable monomer, a hydrophobic organic solvent, and a polymerization initiator. Among inorganic dispersion stabilizers, metal-containing dispersion stabilizers are preferred, and poorly water-soluble inorganic metal salts are more preferred. Furthermore, poorly water-soluble inorganic metal salts are preferably inorganic metal salts having a solubility of 0.5 g or less in 100 g of water, such as magnesium hydroxide, calcium hydroxide, barium hydroxide, calcium phosphate, etc., and among these, magnesium hydroxide is more preferred. Each dispersion stabilizer can be used alone or in combination of two or more.

[0077] In addition, from the viewpoint of further enhancing the dispersion stabilizing effect, it is preferable to use the dispersion stabilizer in the form of a dispersion or solution by dispersing or dissolving it in an aqueous medium. That is, in the mixed liquid preparation step, it is preferable to obtain the mixed liquid by mixing the dispersion stabilizer in the form of a dispersion or solution with the polymerizable monomer, the hydrophobic organic solvent, and the polymerization initiator. Note that the above-mentioned aqueous medium can be used.

[0078] In the dispersion or solution of the dispersion stabilizer, the mixing ratio of the dispersion stabilizer to the aqueous medium, in terms of the mass ratio of "dispersion stabilizer:aqueous medium", is preferably 0.7:100 to 7:100, more preferably 1.0:100 to 4.0:100, and even more preferably 1.4:100 to 3:100. By setting the mixing ratio of the dispersion stabilizer to the aqueous medium within the above range, the dispersion stabilization effect can be more appropriately enhanced.

[0079] As a method for preparing a dispersion or solution of a dispersion stabilizer, a method of directly mixing a dispersion stabilizer with an aqueous medium may be adopted, but a method of mixing two or more compounds that serve as precursors of the dispersion stabilizer (i.e., two or more precursor compounds) in an aqueous medium to cause a reaction and thereby produce the dispersion stabilizer is preferred.

[0080] The precursor compounds used when mixing two or more precursor compounds in an aqueous medium are not particularly limited. For example, when a poorly water-soluble hydroxide salt such as magnesium hydroxide, calcium hydroxide, or barium hydroxide is used as the dispersion stabilizer, examples of the two or more precursor compounds include a combination of a water-soluble polyvalent metal salt and an alkali metal hydroxide.

[0081] Examples of water-soluble polyvalent metal salts include hydrochlorides, sulfates, nitrates, acetates, etc. of polyvalent metals such as magnesium, calcium, aluminum, iron, copper, manganese, nickel, and tin. Among these, water-soluble salts of magnesium and calcium are preferred. Examples of alkali metal hydroxides include sodium hydroxide, potassium hydroxide, and lithium hydroxide. For example, when magnesium hydroxide is used as the dispersion stabilizer, a combination of magnesium chloride and sodium hydroxide is preferred as the two or more precursor compounds.

[0082] The method for mixing two or more precursor compounds in an aqueous medium is not particularly limited. However, in the case of a combination of a water-soluble polyvalent metal salt and an alkali metal hydroxide, a method is preferred in which an aqueous medium solution of the alkali metal hydroxide is added dropwise to an aqueous medium solution of the water-soluble polyvalent metal salt under stirring.

[0083] The content of the water-soluble polyvalent metal salt in the aqueous medium solution is preferably 2 to 8 parts by weight, more preferably 3 to 6 parts by weight, per 100 parts by weight of the aqueous medium solution. The content of the alkali metal hydroxide in the aqueous medium solution is preferably 6 to 20 parts by weight, more preferably 8 to 18 parts by weight, per 100 parts by weight of the aqueous medium solution. The aqueous medium may be any of those described above.

[0084] In the mixed solution preparation step, the above-mentioned components are mixed by stirring or the like to obtain a mixed solution. In this case, in addition to the above-mentioned components, other materials may be mixed as needed. In the mixed solution preparation step, a mixed solution is prepared in which an oil phase containing a polymerizable monomer, a hydrophobic organic solvent, and a lipophilic material such as a polymerization initiator is dispersed in an aqueous medium and an aqueous phase containing a dispersion stabilizer used as needed, with particles having a particle size of about several mm. The dispersion state of these components in the mixed solution can be observed with the naked eye, depending on the type of each component.

[0085] In addition, in the mixed solution preparation step, from the viewpoint that the composition of the shell portion is likely to be uniform, it is preferable to prepare the mixed solution in advance by preparing an oil phase containing a polymerizable monomer, a hydrophobic organic solvent, and a polymerization initiator, and mixing this with a dispersion or solution obtained by dispersing or dissolving a dispersion stabilizer in an aqueous medium.

[0086] (B) Suspension Step The suspension step is a step of preparing a suspension in which droplets of a polymerizable monomer composition containing a polymerizable monomer, a hydrophobic organic solvent, and a polymerization initiator are dispersed in an aqueous medium by suspending the mixed liquid obtained in the mixed liquid preparation step described above.

[0087] The method of suspending the polymerizable monomer composition to form droplets is not particularly limited, but a method of stirring the mixture obtained in the mixture preparation step described above using a stirring device capable of strong stirring is preferred.

[0088] In the suspending step, a suspension can be obtained in which droplets of the polymerizable monomer composition containing the lipophilic material are uniformly dispersed in an aqueous medium. Such droplets of the polymerizable monomer composition are difficult to observe with the naked eye and can be observed using known observation equipment such as an optical microscope. Furthermore, in the suspending step, phase separation occurs in the droplets of the polymerizable monomer composition, which makes it easy for the low-polarity hydrophobic organic solvent to collect inside the droplets. As a result, the resulting droplets contain the hydrophobic organic solvent in their interiors and materials other than the hydrophobic organic solvent distributed around their peripheries.

[0089] (C) Polymerization Step The polymerization step is a step of subjecting the suspension prepared in the suspension step described above to a polymerization reaction to prepare a precursor composition having hollow portions and encapsulating a hydrophobic organic solvent in the hollow portions.

[0090] In the polymerization process, the polymerizable monomer in the droplets of the polymerizable monomer composition is polymerized while the droplets still contain the hydrophobic organic solvent, thereby forming precursor particles having a shell containing a resin, which is a polymer of the polymerizable monomer, and a hollow portion filled with the hydrophobic organic solvent.

[0091] In the polymerization step, droplets of the polymerizable monomer composition are subjected to the polymerization reaction while encapsulating the hydrophobic organic solvent, which facilitates the polymerization reaction while maintaining the shape, and facilitates the adjustment of the size and porosity of the precursor particles. Furthermore, since the polymerizable monomer and the hydrophobic organic solvent are used in combination, the polarity of the hydrophobic organic solvent is low relative to the shell of the precursor particles, and the hydrophobic organic solvent is not easily compatible with the shell, which leads to sufficient phase separation and the formation of only one hollow portion.

[0092] The polymerization method is not particularly limited, and for example, a batch method, a semi-continuous method, a continuous method, etc. can be used. The polymerization temperature is preferably 40 to 90°C, more preferably 50 to 80°C. The polymerization reaction time is preferably 1 to 48 hours, more preferably 3 to 24 hours.

[0093] The polymerization step yields a precursor composition in which precursor particles encapsulating a hydrophobic solvent are dispersed in an aqueous phase containing an aqueous medium as the main component.

[0094] (D) Solvent Removal Step The solvent removal step is a step of removing the hydrophobic organic solvent contained in the precursor particles obtained by the polymerization step.

[0095] Before the solvent is removed in the solvent removal step, it is preferable to perform solid-liquid separation on the precursor composition obtained in the polymerization step in advance, and obtain a solid content containing precursor particles encapsulating the hydrophobic organic solvent by the solid-liquid separation. After obtaining a solid content containing the precursor particles by the solid-liquid separation, the hydrophobic organic solvent encapsulated in the precursor particles is removed in air, whereby the hydrophobic organic solvent inside the precursor particles is replaced with air, and organic crosslinked hollow particles filled with gas can be obtained.

[0096] The method for performing solid-liquid separation of the precursor composition is not particularly limited, and known methods can be used. Examples of solid-liquid separation methods include centrifugation, filtration, and static separation. Among these, centrifugation or filtration can be used, and centrifugation may be used from the viewpoint of ease of operation. After solid-liquid separation, an optional step such as a pre-drying step may be further employed. Examples of the pre-drying step include a step of pre-drying the solid content obtained after the solid-liquid separation step using a drying device such as a dryer or a drying appliance such as a hand dryer.

[0097] Furthermore, in the solvent removal step, "in the air" strictly refers to an environment in which no liquid is present outside the precursor particles, or an environment in which only a trace amount of liquid is present outside the precursor particles, so as not to affect the removal of the hydrophobic organic solvent. "In the air" can also be referred to as a state in which the precursor particles are not present in a slurry, or a state in which the precursor particles are present in a dry powder. That is, in the solvent removal step, it is desirable to remove the hydrophobic organic solvent in an environment in which the precursor particles are in direct contact with the external gas.

[0098] The method for removing the hydrophobic organic solvent from the precursor particles in air is not particularly limited, and known methods can be used, such as vacuum drying, heat drying, and flash drying, which may be used in combination. In particular, when heat drying is used, the heating temperature must be equal to or higher than the boiling point of the hydrophobic organic solvent and equal to or lower than the maximum temperature at which the shell structure of the precursor particles does not collapse. Therefore, depending on the shell composition and the type of hydrophobic organic solvent in the precursor particles, the heating temperature is preferably 50 to 200°C, more preferably 70 to 200°C, and even more preferably 100 to 200°C. The drying operation in air replaces the hydrophobic organic solvent inside the precursor particles with the external gas, resulting in organic crosslinked hollow particles whose hollow portions are filled with gas.

[0099] The drying atmosphere is not particularly limited and can be appropriately selected depending on the application of the organic crosslinked hollow particles. Examples of the drying atmosphere include air, oxygen, nitrogen, argon, etc. Alternatively, organic crosslinked hollow particles with a temporary vacuum interior can be obtained by first filling the interior of the organic crosslinked hollow particles with a gas and then drying under reduced pressure.

[0100] Alternatively, the hydrophobic organic solvent may be removed by replacing the hydrophobic organic solvent contained in the precursor particles with the aqueous medium of the slurry containing the precursor particles in the slurry without subjecting the slurry-like precursor composition obtained in the polymerization step to solid-liquid separation.

[0101] Comparing a method of obtaining organic crosslinked hollow particles having hollow spaces filled with gas by performing solid-liquid separation on a slurry-like precursor composition and then removing the hydrophobic organic solvent in the precursor particles in air, with a method of obtaining organic crosslinked hollow particles having hollow spaces filled with gas by replacing the hydrophobic organic solvent contained in precursor particles with the aqueous medium of the slurry in a slurry containing the precursor particles and an aqueous medium, performing solid-liquid separation, and removing the aqueous medium in the precursor particles in air, the former method has the advantage that the organic crosslinked hollow particles are less likely to be crushed in the step of removing the hydrophobic organic solvent, and the latter method has the advantage that less residual hydrophobic organic solvent remains due to bubbling with an inert gas.

[0102] Alternatively, as a method for removing the hydrophobic organic solvent contained in the precursor particles after the polymerization step and before the solid-liquid separation step without performing solid-liquid separation on the slurry precursor composition obtained in the polymerization step, for example, a method for evaporating and distilling off the hydrophobic organic solvent contained in the precursor particles from the precursor composition under a predetermined pressure (high pressure, normal pressure, or reduced pressure); or a method for introducing an inert gas such as nitrogen, argon, or helium, or water vapor, into the precursor composition under a predetermined pressure (high pressure, normal pressure, or reduced pressure) and evaporating and distilling off the hydrophobic organic solvent may be used.

[0103] (E) Other Steps The above manufacturing method may also include other steps, such as (E-1) a cleaning step and (E-2) a hollow portion re-replacement step.

[0104] (E-1) Washing Step The above-described production method preferably includes a washing step before or after the recovery step. For example, when a dispersion stabilizer is used, it is preferable to include a washing step in which an acid or alkali is added to wash the organic crosslinked hollow particle slurry containing the organic crosslinked hollow particles and the aqueous medium before the recovery step in order to remove any dispersion stabilizer remaining in the organic crosslinked hollow particle slurry. When the dispersion stabilizer used is an acid-soluble dispersion stabilizer, it is preferable to add an acid to the precursor composition containing the precursor particles to perform washing. On the other hand, when the dispersion stabilizer used is an alkali-soluble dispersion stabilizer, it is preferable to add an alkali to the precursor composition containing the precursor particles to perform washing.

[0105] Furthermore, when an acid-soluble dispersion stabilizer is used as the dispersion stabilizer, it is preferable to add an acid to the precursor composition containing the precursor particles to adjust the pH to preferably 6.5 or less, more preferably 6 or less. The acid to be added may be an inorganic acid such as sulfuric acid, hydrochloric acid, or nitric acid, or an organic acid such as formic acid or acetic acid, but sulfuric acid is particularly preferable because it has a high efficiency in removing the dispersion stabilizer and places a small burden on the production equipment.

[0106] (E-2) Hollow Portion Re-Substitution Process The hollow portion re-substitution process is a process of substituting the gas or liquid inside the organic crosslinked hollow particles with another gas or liquid. This substitution can change the environment inside the organic crosslinked hollow particles, selectively confine molecules inside the organic crosslinked hollow particles, or modify the chemical structure inside the organic crosslinked hollow particles depending on the application.

[0107] [Other Compounding Materials] The resin mixture for 3D printer modeling of the present invention may consist only of a matrix resin and organic crosslinked hollow particles, but may also contain other compounding materials as long as the object of the present invention is not impaired. Preferably, the resin mixture for 3D printer modeling of the present invention is substantially free of hollow particles other than organic crosslinked hollow particles (preferably the content of hollow particles other than organic crosslinked hollow particles is less than 1 wt %).

[0108] Other compounding materials that may be included include fillers including organic fillers and inorganic fillers, colorants including dyes and pigments, antistatic agents, end-capping agents, ultraviolet absorbers, ultraviolet inhibitors, heat stabilizers, light stabilizers, anti-fogging agents, anti-misting agents, plasticizers, flame retardants, color inhibitors, anti-staining agents, antioxidants, release agents (erucic acid amide, stearic acid amide, oleic acid amide, ethylene bisstearic acid amide, ethylene bisoleic acid amide, ethylene bislauric acid amide), moisture-proof agents, oxygen barrier agents, crystal nucleating agents, compatibilizers, etc. The above compounding materials may be used alone or in combination of two or more.

[0109] Examples of organic fillers include fibrous organic fillers such as aramid fiber, polyimide fiber, polybenzthiazole fiber, and polyethylene fiber; and plant fibers such as hemp and bamboo.

[0110] Examples of inorganic fillers include glass beads, glass fibers, flat cross-section glass fibers, milled glass fibers, ceramic beads, wollastonite, mica, synthetic mica, sericite, talc, clay, zeolite, bentonite, kaolinite, dolomite, silica, zeolite, feldspar powder, potassium titanate, finely powdered silicic acid, calcium carbonate, magnesium carbonate, barium sulfate, aluminum oxide, magnesium oxide, calcium oxide, titanium oxide, silicon oxide, aluminum silicate, zirconium silicate, gypsum, novaculite, dawsonite, montmorillonite, calcium sulfide, zinc oxide, boron nitride, glass flakes, metal flakes, metal fibers, basalt fibers, rock wool, ceramic fibers, slag potassium titanate, boron whiskers, aluminum borate, xonotlite, palygorskite (attapulgite), and sepiolite. Examples of inorganic fillers include carbon fibers such as carbon fiber, carbon milled fiber, and carbon nanotubes; carbon black; graphite; and carbon fillers such as carbon flakes.

[0111] The organic filler and inorganic filler are preferably not in the form of hollow particles, and specifically, are preferably in the form of fibers, particles or plates.

[0112] The content of other compounding materials in the resin mixture for 3D printer modeling is not particularly limited as long as it is within a range that does not impair the object of the present invention. However, the content is preferably 0 to 30 parts by weight, more preferably 0 to 10 parts by weight, and even more preferably 0 to 5 parts by weight, relative to 100 parts by weight of the total content of the matrix resin and the organic crosslinked hollow particles.

[0113] [Method for Producing a Resin Mixture for 3D Printer Modeling] The resin mixture for 3D printer modeling is obtained by mixing the matrix resin and organic crosslinked hollow particles described above with optional compounding agents. Specifically, the organic crosslinked hollow particles used in the present invention and optional compounding agents are preferably added to a molten matrix resin, followed by melt-kneading. In this case, all components may be fed independently to a melt-kneader. Alternatively, some components may be pre-mixed, and then the pre-mixed components and the remaining components may be fed independently to a melt-kneader.

[0114] The matrix resin, organic crosslinked hollow particles, and optional compounding agents can be kneaded using, for example, a kneader, a roll mill, a Brabender, a single-screw extruder, a twin-screw extruder, a multi-screw extruder, or the like. Among these, melt-kneading is preferably performed using an extruder such as a single-screw extruder, a twin-screw extruder, or a multi-screw extruder. Since a resin mixture for 3D printer modeling with excellent uniformity can be obtained with high production efficiency, melt-kneading is preferably performed using a twin-screw extruder. When melt-kneading is performed using an extruder, the cylinder temperature (twin-screw kneading temperature) is preferably 150 to 220°C, more preferably 170 to 210°C, and the die temperature (extrusion molding temperature) is preferably 160 to 220°C, more preferably 180 to 210°C.

[0115] <3D Printer Modeling Material> The present invention provides a 3D printer modeling material comprising the above-described resin mixture for 3D printer modeling of the present invention. The 3D printer modeling material of the present invention is capable of producing a shaped object with excellent modeling properties and excellent reproducibility of the modeled model with sufficient strength. In addition, the 3D printer modeling material of the present invention can produce a lightweight shaped object with an apparent density lower than the density of the matrix resin.

[0116] The 3D printer modeling material of the present invention is obtained by molding the above-described resin mixture for 3D printer modeling of the present invention into a shape that can be used in a 3D printer. Shapes that can be used in 3D printers include pellets and filaments. From the viewpoint of being applicable to general-purpose fused deposition modeling 3D printers, the 3D printer modeling material of the present invention may be in the form of a filament.

[0117] The apparent density of the 3D printer modeling material of the present invention is preferably 0.4 to 0.99 times, more preferably 0.45 to 0.98 times, and even more preferably 0.5 to 0.95 times the density of the matrix resin constituting the 3D printer modeling material of the present invention. According to the present invention, the 3D printer modeling material can be made to have excellent modeling properties and be lightweight as described above (i.e., the apparent density of the 3D printer modeling material is lower than the density of the matrix resin as described above), thereby enabling the resulting modeled object to be lightweight. The apparent density of the 3D printer modeling material can be measured using a method similar to that for measuring the apparent density of organic crosslinked hollow particles.

[0118] (Method for manufacturing 3D printer modeling material) The 3D printer modeling material of the present invention can be obtained, for example, by molding the above-mentioned resin mixture for 3D printer modeling of the present invention into a desired shape by a known molding method such as extrusion molding, injection molding, press molding, compression molding, etc. Among these, extrusion molding is preferred from the viewpoint of being able to produce filament-shaped and pellet-shaped 3D printer modeling materials that can be applied to general-purpose 3D printers with high production efficiency.

[0119] As described above, when the resin mixture for 3D printer modeling is produced using an extruder such as a twin-screw extruder, the kneaded resin mixture for 3D printer modeling can be extruded from the extruder and subsequently molded into pellets, filaments, or the like, thereby enabling the production of pellet-shaped, filament-shaped, or other 3D printer modeling materials with high production efficiency. In this case, the preferred cylinder and die temperatures are as described above.

[0120] The pellets can be obtained, for example, by extruding the resin mixture for 3D printer modeling of the present invention described above and cutting it directly into pellets, or by extruding the resin mixture for 3D printer modeling of the present invention described above into strands, cooling them, and then cutting them. The pellets can be used as pellet-shaped 3D printer modeling material as is, or they can be used to obtain 3D printer modeling material having a desired shape, such as a filament shape.

[0121] The filament-shaped 3D printer modeling material may be a monofilament or a multifilament, but is preferably a monofilament. The filament-shaped 3D printer modeling material may also be unstretched or stretched. The diameter of the filament-shaped 3D printer modeling material can be freely adjusted to suit the 3D printer being used, but is generally preferably 1.5 to 3.2 mm, and more preferably 1.6 to 3.1 mm.

[0122] The filament-shaped 3D printer modeling material can be produced, for example, by extruding a 3D printer modeling resin mixture into a filament and then cooling and solidifying it. The cooling and solidifying is usually carried out in a liquid bath at 0 to 100°C, preferably 20 to 80°C.

[0123] After extruding the resin mixture for 3D printer modeling into a filament, the extrudate may be stretched before or after cooling and solidifying. Examples of stretching methods include, but are not limited to, stretching at a stretch ratio of 2 to 5 times while performing a heat treatment at 170 to 250°C, and repeating such stretching as necessary. After stretching, it is preferable to perform a relaxation heat treatment (stretch ratio of 0.9 to 0.99 times) while performing a heat treatment at 130 to 200°C.

[0124] The filament-shaped 3D printer modeling material obtained in the manner described above is usually wound onto a bobbin or the like and then housed in a cartridge or the like.

[0125] (Uses of 3D Printer Modeling Material) The 3D printer modeling material of the present invention is applicable to 3D printers, which have a high degree of design freedom, and therefore can be used in a very wide range of applications. In particular, the 3D printer modeling material of the present invention has excellent modeling properties and can produce lightweight models, and therefore can be suitably used in applications where it is necessary to obtain models with complex three-dimensional structures with sufficient strength or where lightweight models are required.

[0126] Applications of the 3D printer modeling material of the present invention are not particularly limited, but include, for example, parts for moving objects such as aircraft, automobiles, trains, motorcycles, boats, bicycles, drones, satellites, and shuttles (e.g., space shuttles); parts for everyday items such as stationery, brushes, rings, jewelry, watches, cooking utensils, kitchen utensils, cleaning tools, home appliances, and toys; parts for wearable items such as shoes, clothing, zippers, buttons, snaps, gloves, shin guards, hats, knee pads, elbow pads, helmets, and headgear; and parts for wearable devices such as braces, assist suits, and wearable devices. parts for sports equipment such as rackets and grips; various materials such as agricultural supplies, gardening supplies, fishing supplies, civil engineering and construction materials; electrical and electronic parts such as electronic circuit boards and casings; industrial parts such as gears, motors, tools, propellers, impellers, wheels, machinery housings, gaskets, O-rings, piping, connectors and reflectors; medical parts such as medical equipment, stents, catheters, orthodontic appliances and artificial organs; containers such as food containers, mobile device covers and bottles; scale models of cars, houses and buildings; heat insulation materials; soundproofing materials; vibration damping materials; cushioning materials; etc.

[0127] In particular, parts for mobile objects such as drones often have complex three-dimensional shapes and are therefore often produced using 3D printers. Here, for parts for mobile objects such as drones, in addition to the need to obtain parts with complex three-dimensional structures with sufficient strength, there is also a very high demand for lightweight parts. Therefore, the 3D printer modeling material of the present invention can be suitably used for parts of mobile objects such as drones. More specifically, the 3D printer modeling material of the present invention can be suitably used for parts such as bodies, propellers, arms, and legs of mobile objects such as drones, as well as for various parts such as covers, guard parts, reinforcing parts, supports, and vibration-isolating members for protecting or supporting parts such as motors, batteries, cameras, propellers, and antennas provided on mobile objects.

[0128] <Modeled object> The modeled object of the present invention can be obtained by 3D printer modeling using the above-described 3D printer modeling material of the present invention.

[0129] The shaped object of the present invention is obtained using the 3D printer modeling material of the present invention, and therefore has a three-dimensional shape that is excellent in reproducibility of the modeled model, has sufficient strength, and is lightweight. The shaped object of the present invention can be obtained by the modeling method of the present invention described below.

[0130] <Modeling method> According to the present invention, there is provided a modeling method for performing 3D printer modeling using the above-described 3D printer modeling material of the present invention. The modeling method of the present invention allows the above-described shaped object of the present invention to be obtained.

[0131] Examples of 3D printer modeling methods include fused deposition modeling (FDM), powder sintering, inkjet, and stereolithography (SLA). Among these, the 3D printer modeling material of the present invention is suitable for fused deposition modeling. That is, the modeling method of the present invention is preferably for fused deposition modeling, and the modeled object of the present invention is preferably obtained by fused deposition modeling.

[0132] The following description will be given of a case where the fused deposition modeling method is used, but the modeling method of the present invention is not limited to this case.

[0133] First, the 3D printer modeling material of the present invention is supplied to a 3D printer. When a filament (filament-like 3D printer modeling material) is used, the filament is generally engaged with a driving roll such as a nip roll or a gear roll and supplied to an extrusion head while being pulled up.

[0134] The 3D printer modeling material supplied to the 3D printer is heated and melted in the extrusion head and extruded from the tip nozzle. The temperature of the extrusion head (nozzle temperature) is preferably 150 to 220°C, more preferably 170 to 210°C. The temperature of the 3D printer modeling material discharged from the extrusion head is preferably 160 to 220°C, more preferably 180 to 210°C. The substrate temperature is preferably 80°C or lower. By keeping the temperature of the 3D printer modeling material discharged from the extrusion head within the above range, lightweight models can be produced with excellent productivity and even better modeling performance. Furthermore, by keeping the temperature within the above range, problems such as thermal decomposition of the resin, burning, yellowing, smoke, odor, stickiness, and poor appearance can be easily prevented.

[0135] The 3D printer modeling material is preferably discharged from the extrusion head in the form of strands with a diameter of 0.01 to 1.0 mm, more preferably 0.02 to 0.5 mm. Discharging the 3D printer modeling material in such a shape is preferred because it tends to improve the reproducibility of the modeled model.

[0136] The shaped body of the present invention and the shaping method of the present invention can be suitably applied to the uses described above as the uses of the 3D printer shaping material of the present invention.

[0137] In addition, when using a 3D printer material for fused deposition modeling (FDM) 3D printer modeling, when creating a model by stacking strands of 3D printer material ejected from an extrusion head, the adhesion between the previously ejected strand of 3D printer material and the strand of 3D printer material ejected on top of it may be insufficient, resulting in insufficient strength of the resulting model. For example, when using a 3D printer material containing an inorganic component as its main component, the above-mentioned adhesion is likely to be insufficient, resulting in insufficient strength of the resulting model.

[0138] Furthermore, in 3D printer modeling materials consisting of a mixture containing a matrix resin and thermoplastic hollow particles, it is difficult to maintain the hollow shape derived from the hollow particles when manufacturing the 3D printer modeling material or when 3D printer modeling is performed using the 3D printer modeling material, and the weight reduction effect of the hollow particles is likely to be insufficient.

[0139] In contrast, the 3D printer modeling material made from the 3D printer modeling resin mixture of the present invention has good adhesion between 3D printer modeling materials and is able to easily maintain the hollow shape derived from the hollow particles, resulting in excellent modeling properties and the ability to produce lightweight models. Therefore, according to the present invention, it is possible to produce lightweight models with excellent modeling properties.

[0140] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. Parts and percentages are by mass unless otherwise specified. Various measurements were carried out according to the following methods.

[0141] <Apparent density> Volume 100 cm ３ About 30 cm ３ The volumetric flask was filled with isopropanol up to the marked line, taking care not to introduce air bubbles. The mass of the isopropanol added to the volumetric flask was accurately weighed, and the apparent density D of the sample was calculated based on the following formula (II):１ (g / cm ３ ) was calculated. In the case of a large sample size, ３ The apparent density of the sample was measured using other equipment instead of the volumetric flask. １ (g / cm ３ ) = [mass of sample] ÷ (100 - [mass of isopropanol] ÷ [density of isopropanol at measurement temperature]) (II)

[0142] <Modeling Performance> In each example and comparative example, the modeling performance when 3D printer modeling was performed using "3D Benchy" as the modeling model was evaluated according to the following criteria. A: A modeled object with excellent reproducibility of the model was obtained with a clean appearance and sufficient strength. B: A modeled object with excellent reproducibility of the model was obtained with sufficient strength, but some stringiness was observed due to nozzle movement during 3D printer modeling. C: After 3D printer modeling, the modeled object broke into multiple parts due to slight stress when removing the model from the 3D printer or when measuring the apparent density.

[0143] <Bending Test> Bending tests were carried out using the bending test samples obtained in each of the examples and comparative examples according to the following procedures (1) to (3).

[0144] (1) Flexural Strength According to JIS K7171, the flexural strength (flexural stress calculated based on the maximum load until breakage) of the bending test sample was measured.

[0145] (2) Deformation Using the same bending tester as used to measure bending strength, the bending test sample was bent at a test speed of 2 mm / min. After the deflection of the bending test sample reached 4 mm (i.e., 2 minutes after the start of bending), the sample was held at this deflection for 5 minutes. Next, the bending stress was released, and the deformation of the bending test sample after release (the amount of deflection remaining in the bending test sample) was measured.

[0146] (3) Evaluation of bending test results Based on the bending strength measured in (1) above and the deformation measured in (2), the bending test results were evaluated according to the following criteria: A The bending strength measured in (1) was 20 MPa or more and the deformation measured in (2) was less than 1 mm. B The bending strength measured in (1) was 5 MPa or more and less than 20 MPa and the deformation measured in (2) was less than 1 mm. C The bending strength measured in (1) was 5 MPa or more and less than 20 MPa and the deformation measured in (2) was 1 mm or more and less than 3 mm. D The bending strength measured in (1) was less than 5 MPa, The deformation measured in (2) was 3 mm or more, or The bending test sample was destroyed during the measurement of the deformation in (2), making it impossible to measure the displacement.

[0147] [Production Example 1 (Production Example of Organic Crosslinked Hollow Particles 1)] (1) Mixture Preparation Step First, the following materials were mixed to prepare an oil phase: Ethylene glycol dimethacrylate 31.85 parts (bifunctional heteroatom-containing crosslinkable monomer) Pentaerythritol tetraacrylate (tetrafunctional heteroatom-containing crosslinkable monomer) 9.1 parts Divinylbenzene (bifunctional crosslinkable hydrocarbon monomer) 4.37 parts Ethylvinylbenzene (monofunctional hydrocarbon monomer) 0.182 parts 2,2'-Azobis(2,4-dimethylvaleronitrile) (oil-soluble polymerization initiator) 1.04 parts Hexane 54.5 parts

[0148] Next, in a stirring tank, an aqueous solution of 16.5 parts of sodium hydroxide (alkali metal hydroxide) in 55 parts of ion-exchanged water was gradually added under stirring to an aqueous solution of 23.5 parts of magnesium chloride (a water-soluble polyvalent metal salt) in 225 parts of ion-exchanged water to prepare a magnesium hydroxide colloid (poorly water-soluble metal hydroxide colloid) dispersion, and an aqueous phase was obtained. The obtained aqueous phase and oil phase were mixed to prepare a mixed liquid.

[0149] (2) Suspension Step Next, the mixture obtained in the mixture preparation step was stirred and suspended for 1 minute using a disperser (manufactured by Primix Corporation, product name: Homomixer) at a rotation speed of 4,000 rpm to prepare a suspension in which monomer droplets encapsulating a hydrophobic organic solvent were dispersed in water.

[0150] (3) Polymerization step: The suspension obtained in the suspension step was heated to 65° C. in a nitrogen atmosphere and stirred for 24 hours at a temperature of 65° C. to carry out a polymerization reaction. This polymerization reaction yielded a precursor composition that was a slurry liquid in which precursor particles encapsulating a hydrophobic organic solvent were dispersed in water.

[0151] (4) Washing Step and Solid-Liquid Separation Step The precursor composition obtained in the polymerization step was washed with dilute sulfuric acid (25°C, 10 minutes) to adjust the pH to 5.5 or less. Next, water was separated by filtration, and 200 parts of ion-exchanged water was added to re-slurry the mixture. The water washing treatment (washing, filtration, dehydration) was repeated several times at room temperature (25°C), and a solid was separated by filtration.

[0152] (5) Drying Step The precursor particles obtained in the solid-liquid separation step were heat-treated in a vacuum dryer at 200°C for 24 hours to remove moisture and the encapsulated solvent, thereby obtaining organic crosslinked hollow particles 1. The monomer composition of the shell polymer in the obtained organic crosslinked hollow particles 1 was roughly consistent with the composition of the polymerizable monomers used in the polymerization. The apparent density of the obtained organic crosslinked hollow particles 1 was 0.4 g / cm ３ It was.

[0153] [Production Example 2 (Production Example of Organic Crosslinked Hollow Particles 2)] First, the following materials were mixed to prepare an oil phase: 31.85 parts ethylene glycol dimethacrylate, 9.1 parts pentaerythritol tetraacrylate (tetrafunctional heteroatom-containing crosslinkable monomer), 4.37 parts divinylbenzene (bifunctional crosslinkable hydrocarbon monomer), 0.182 parts ethylvinylbenzene (monofunctional hydrocarbon monomer), 1.04 parts 2,2'-azobis(2,4-dimethylvaleronitrile) (oil-soluble polymerization initiator), 34.5 parts hexane. Organic crosslinked hollow particles 2 were obtained in the same manner as in Production Example 1, except that the obtained oil phase was used. The monomer composition of the shell polymer in the obtained organic crosslinked hollow particles 2 was roughly consistent with the composition of the polymerizable monomers used in the polymerization. The apparent density of the obtained organic crosslinked hollow particles 2 was 0.6 g / cm. ３ It was.

[0154] The matrix resin and hollow particles used in each example and comparative example are as follows: [Matrix resin] PLA resin: polylactic acid, density 1.25 g / cm ３ ABS resin: acrylonitrile-butadiene-styrene resin, density 1.07 g / cm ３ [Hollow particles] Organic crosslinked hollow particles 1: hollow particles obtained in Production Example 1, apparent density 0.4 g / cm ３ Organic crosslinked hollow particles 2: hollow particles obtained in Production Example 2, apparent density 0.6 g / cm ３ Non-crosslinked organic hollow particles: hollow particles having a shell composed of a styrene-acrylic copolymer (thermoplastic resin) and a hollow portion, trade name "Techpolymer MBP-8", manufactured by Sekisui Plastics Co., Ltd., apparent density 0.4 g / cm ３ Inorganic hollow particles: Shirasu balloons, trade name "Winlight (registered trademark) SC-50", manufactured by Sila Fine Co., Ltd., apparent density 0.7 g / cm ３

[0155] [Example 1] As a matrix resin, PLA resin (polylactic acid, density 1.25 g / cm ３ ) was used, and the organic crosslinked hollow particles 1 obtained in Production Example 1 were used as the hollow particles. The matrix resin and hollow particles were supplied to a twin-screw kneading extruder in a ratio of 90 parts matrix resin to 10 parts hollow particles. Then, twin-screw kneading and extrusion were performed under conditions of a twin-screw kneading temperature of 190°C and an extrusion molding temperature of 200°C to obtain a filament (a material for 3D printer modeling). The apparent density of the obtained filament was measured according to the measurement method described above. The results are shown in Table 1.

[0156] Using the obtained filament, 3D printer modeling was performed under the following conditions to obtain a 3D Benchy-shaped object. The appearance of the obtained object is shown in Figure 1. The apparent density of the obtained object was also tested by bending using the method described above. The results are shown in Table 1. 3D printer: fused deposition modeling 3D printer (product name "Da Vinci 1.0 Pro", manufactured by XYZ Printing Japan) Nozzle temperature: 200°C Modeling model: 3D Benchy (standard model for 3D printer modeling performance tests)

[0157] In addition, bending test samples were obtained under the same conditions as above, except that the shaped model was changed to a bending test sample model (80 mm x 10 mm x 4 mm height). The obtained bending test samples were subjected to a bending test according to the measurement method described above. The results are shown in Table 1.

[0158] [Examples 2 to 9 and Comparative Examples 1 and 2] Filaments (3D printer modeling materials) were obtained in the same manner as in Example 1, except that the types of matrix resin and hollow particles, and their blending ratios, were changed as shown in Table 1. Then, a 3D Benchy-shaped object and a bending test sample were obtained in the same manner as in Example 1, except that the obtained filaments were used. Measurements and tests were performed in the same manner as in Example 1 using the obtained filaments, the shaped object, and the bending test sample. The results are shown in Table 1.

[0159] The object (3D Benchy) manufactured in Comparative Example 2 was broken into multiple parts when it was removed from the 3D printer after 3D printing or when slight stress was applied during apparent density measurement, and its apparent density could not be measured.

[0160]

[0161] As is clear from Table 1, the resin mixture for 3D printer modeling containing the matrix resin and the organic crosslinked hollow particles has excellent modeling properties and can provide a 3D printer modeling material that can produce a lightweight modeled object (Examples 1 to 9).

[0162] On the other hand, when non-crosslinked organic hollow particles were used as the hollow particles, a lightweight shaped body could not be obtained (Comparative Example 1).

[0163] Furthermore, when inorganic hollow particles were used as the hollow particles, the resulting 3D printer modeling material had poor modeling properties (Comparative Example 2).

Claims

1. A resin mixture for 3D printing containing a matrix resin and organic crosslinked hollow particles.

2. The apparent density of the aforementioned organic crosslinked hollow particles is 0.2 to 0.9 g / cm³. ３ The resin mixture for 3D printing according to claim 1.

3. The resin mixture for 3D printing according to claim 1 or 2, wherein the content of the organic crosslinked hollow particles is 1 to 70 parts by weight with respect to 100 parts by weight of the total content of the matrix resin and the organic crosslinked hollow particles.

4. The resin mixture for 3D printing according to claim 1 or 2, wherein the organic crosslinked hollow particles are provided with a shell made of a shell polymer containing crosslinkable monomer units.

5. The resin mixture for 3D printing according to claim 4, wherein the shell polymer includes heteroatom-containing crosslinkable monomer units as the crosslinkable monomer units.

6. A 3D printer material comprising the resin mixture for 3D printing described in claim 1 or 2.

7. A 3D printing material according to claim 6, used in fused deposition modeling (FDM) 3D printing.

8. The 3D printing material according to claim 6, which is in the form of a filament.

9. A molded body obtained by 3D printing using the 3D printing material described in claim 6.

10. The fabricated body according to claim 9, obtained by fused deposition modeling (FDM) 3D printing.

11. A method for performing 3D printing using the 3D printing material described in claim 6.

12. The fabrication method according to claim 11, which involves performing 3D printing using a fused deposition modeling (FDM) method.