JP6874559B2 - Curable composition, manufacturing method of three-dimensional model and three-dimensional model - Google Patents

Description

The present invention relates to a curable composition, a method for producing a three-dimensional model, and a three-dimensional model.

In recent years, various methods have been developed that can relatively easily manufacture a three-dimensional model having a complicated shape. The material jet method is known as one of the methods for manufacturing a three-dimensional model. In the material jet method, a liquid and active photocurable composition (hereinafter, also simply referred to as “curable composition”) is used as a model material ink, and is ejected as droplets by an inkjet method, and the stage or lower level. A three-dimensional model is manufactured by irradiating the model material ink that has landed on the layer with active energy rays to form a model material layer formed by curing the model material ink, and stacking the model material layers. This is a method (for example, Patent Document 1). In the material jet method, when producing an overhanging portion or the like, a support material ink that is curable and can be peeled off from the modeled object layer after curing is ejected and cured to simultaneously produce a support modeled object that supports the modeled object layer from below. Sometimes.

Various curable compositions used as model material inks for the production of three-dimensional shaped objects by the material jet method have been studied. For example, Patent Document 2 describes a curable composition containing a fine cellulose fiber or a modified product thereof in which a natural cellulose fiber is oxidized in the presence of an N-oxyl compound to increase the carboxy group content to 0.1 mmol / g or more. Is stated to be able to increase the mechanical strength of the three-dimensional shaped product produced.

It should be noted that Patent Document 3 also describes that nanofibers of polysaccharides can increase the mechanical strength of a modeled product produced from a curable composition by an injection molding method, an extrusion molding method, or the like.

Japanese Unexamined Patent Publication No. 02-307728 Japanese Unexamined Patent Publication No. 2017-007116 Japanese Unexamined Patent Publication No. 2016-153470

As described in Patent Documents 2 and 3, if a curable composition containing fine-sized fibers (hereinafter, also simply referred to as “nanofibers”) is used, a three-dimensional model produced by the material jet method is used. It is expected that the strength of the can be further increased.

By the way, in the three-dimensional model manufactured by the material jet method, the strength between layers is unlikely to increase, and the strength in the stacking direction (hereinafter, also simply referred to as “height direction”) increases in the direction in which the surface of the layer spreads (hereinafter, referred to as “height direction”). There is a problem that the strength tends to be lower than the strength in the "horizontal direction". According to the studies by the present inventors, even a curable composition containing nanofibers as described in Patent Documents 2 and 3 cannot sufficiently increase the strength of the three-dimensional model to be produced in the stacking direction. could not.

The present invention has been made in view of the above problems, and is curable and can be used for manufacturing a three-dimensional model by a material jet method, which can further increase the strength of the three-dimensional model to be manufactured in the stacking direction. Its purpose is to provide the composition.

The present invention relates to the following curable composition, a method for producing a three-dimensional model, and a three-dimensional model.
[1] Formation of a molded product layer obtained by curing the curable composition by irradiating a curable composition that has been ejected by an inkjet method and landed on the surface of a stage or lower shaped product layer with active energy rays. In a curable composition for producing a three-dimensional model formed by laminating the model layers, the nanofiber contains an active energy ray-curable compound and nanofibers. A curable composition in which the ratio of the number of nanofibers having a branched structure to the total number is 5% or more.
[2] The curable composition according to [1], wherein the ratio of the number of nanofibers having the branched structure to the total number of the nanofibers is 10% or more.
[3] The curable composition according to [1] or [2], wherein the ratio of the number of nanofibers having the branched structure to the total number of the nanofibers is 20% or more.
[4] The curable composition according to any one of [1] to [3], wherein the average fiber diameter of the nanofibers is 2 nm or more and 100 nm or less.
[5] The curable composition according to any one of [1] to [4], wherein the average fiber length of the nanofibers is 0.2 μm or more and 100 μm or less.
[6] The curable composition according to any one of [1] to [5], wherein the nanofiber has an aspect ratio of 10 or more and 10000 or less.
[7] Any of [1] to [6], wherein the ratio of the mass of the nanofibers to the total mass of the active energy ray-curable compound is 0.05% by mass or more and 5.0% by mass or less. The curable composition according to.
[8] The curable composition according to any one of [1] to [7], wherein the nanofiber contains nanocellulose as a main component.
[9] The curable composition according to [8], wherein the nanocellulose contains cellulose nanofibers.
[10] The curable composition according to [8], wherein the nanocellulose contains cellulose nanocrystals.
[11] A step of ejecting a droplet of the curable composition according to any one of [1] to [10] from a nozzle of an inkjet head and landing it on the surface of a stage or a lower modeled object layer, and the landing. A step of irradiating the cured composition with active energy rays to form a molded product layer obtained by curing the curable composition, a step of landing the cured composition, and a step of forming the molded product layer. A method for manufacturing a three-dimensional model, in which the above-mentioned model layers are laminated by performing the above steps a plurality of times in this order.
[12] The droplet is cured by irradiating an inkjet head for ejecting a droplet of the curable composition according to any one of [1] to [10] from a nozzle, a stage, and active energy rays. A light source for forming a modeled object layer is provided, and the light source irradiates the droplets ejected from the inkjet head and landed on the modeled object layer on or below the stage with active energy rays to irradiate the liquid. A three-dimensional modeling device that newly forms a modeled object layer formed by hardening drops.

According to the present invention, there is provided a curable composition that can be used in the production of a three-dimensional model by a material jet method, which can further increase the strength of the three-dimensional model to be produced in the stacking direction.

FIG. 1A is a schematic view showing nanofibers having no branched structure, which can be contained in the curable composition of the present invention. 1B, 1C and 1D are schematic views showing nanofibers having a branched structure that can be contained in the curable composition of the present invention. FIG. 2 is an exemplary side view of a three-dimensional modeling apparatus by the material jet method.

The present inventor has made diligent studies in view of the above problems, and the nanofibers contained in the curable composition are discharged from the nozzle of the inkjet head and landed on the stage or the lower model layer in the curable composition. , Found that it is easier to orient in the horizontal direction than in the height direction. That is, when producing a three-dimensional model using a conventional curable composition containing nanofibers, most of the nanofibers are cured in the horizontally oriented curable composition after landing, so that the nanofibers are also nanofibers. The fibers tend to be oriented horizontally. Therefore, it is considered that the strength in the horizontal direction of the three-dimensional model is increased by the nanofibers, but the strength in the height direction is not easily increased by the nanofibers.

The present inventor further conducts experiments and studies based on the above findings, and is formed by increasing the amount of nanofibers having a branched structure among the nanofibers contained in the liquid curable composition. We have completed a curable composition that can be used in the production of three-dimensional shaped objects by the material jet method, which can reduce the ratio of the strength in the height direction to the strength in the horizontal direction of the three-dimensional shaped object.

One aspect of the present invention based on the above idea is that the curable composition is cured by irradiating the curable composition that has been ejected by an inkjet method and landed on the surface of a stage or a lower model layer with active energy rays. The present invention relates to a curable composition for producing a three-dimensional model formed by laminating the shaped object layers by forming the shaped object layer a plurality of times. The curable composition contains an active energy ray-curable compound and nanofibers, and the ratio of the number of nanofibers having a branched structure to the total number of the nanofibers is 5% or more.

1. 1. Curable Composition The curable composition contains an active energy ray-curable compound and nanofibers of a polysaccharide.

1-1. Active Energy Ray Curable Compound The active energy ray curable compound may be a liquid compound that is irradiated with active energy rays to polymerize, crosslink, and cure.

The active energy ray may be any energy ray capable of polymerizing and cross-linking a liquid compound to cure it. Examples of active energy rays include ultraviolet rays, X-rays, electron beams, γ-rays and the like. As long as the compound is curable, the active energy ray may be visible light.

Examples of active energy ray-curable compounds include radically polymerizable compounds and cationically polymerizable compounds. The photopolymerizable compound may be a monomer, a polymerizable oligomer, a prepolymer, or a mixture thereof. The active energy ray-curable compound may contain only one type in the curable composition, or may contain two or more types.

The radically polymerizable compound is preferably an unsaturated carboxylic acid ester compound, and contains an ethylene group, a propenyl group, a butenyl group, a vinylphenyl group, a (meth) acryloyl group, an allyl ether group, a vinyl ether group, a maleyl group, and a maleimide group. It is preferably a compound having a (meth) acrylamide group, an acetylvinyl group or a vinylamide group, and more preferably a (meth) acrylate. The radically polymerizable compound may contain only one type or two or more types in the curable composition. In the present invention, "(meth) acryloyl group" means an acryloyl group or a methacryloyl group, "(meth) acrylic" means acrylic or methacrylic, and "(meth) acrylate" means acrylate or methacrylate. Means.

Examples of (meth) acrylates include isoamyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, octyl (meth) acrylate, and isooctyl (meth) acrylate. , Isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, tridecyl (meth) acrylate, isomilstill (meth) acrylate, isostearyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, dicyclo Pentenyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, 2-ethylhexyl-diglycol (meth) acrylate, 2- (meth) acryloyloxyethyl hexa. Hydrophthalic acid, methoxyethoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxydiethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, methoxypropylene glycol (meth) acrylate, phenoxy Ethyl (meth) acrylate, pentachlorophenyl (meth) acrylate, pentabromophenyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, dicyclopentanyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, (Meta) acryloylmorpholine, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, glycerin (meth) acrylate, 7-amino-3,7-dimethyloctyl (meth) acrylate, 2-hydroxyethyl (meth) Acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, benzyl (meth) acrylate, 2- (2-ethoxyethoxy) ethyl (meth) ) Acrylate, 2-ethylhexyl carbitol (meth) acrylate, 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxyethyl phthalic acid, 2- (meth) acryloyloxyethyl-2- Monofunctional (meth) acrylates, including hydroxyethyl-phthalic acid, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, and t-butylcyclohexyl (meth) acrylates, triethylene glycol di (meth) acrylates, tetraethylene Glycoldi (meth) acrylate, polyethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol Di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, cyclohexanedi (meth) acrylate, cyclohexanedimethanol di (meth) acrylate, neopentyl glycol di (meth) acrylate, tricyclodecanediyl dimethylene di ( Meta) acrylate, dimethylol-tricyclodecanedi (meth) acrylate, polyester di (meth) acrylate, PO adduct di (meth) acrylate of bisphenol A, neopentyl glycol di (meth) acrylate of hydroxypivalate, polytetramethylene glycol Bifunctional acrylates, including di (meth) acrylates, polyethylene glycol di (meth) acrylates, tripropylene glycol di (meth) acrylates, and tricyclodecanedimethanol di (meth) acrylates, and trimethyl propantri (meth). ) Acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, ditrimethylol propanetetra (meth) acrylate, dipentaerythritol mono Includes trifunctional or higher functional acrylates, including hydroxypenta (meth) acrylates, glycerin propoxytri (meth) acrylates, and pentaerythritol ethoxytetra (meth) acrylates.

The (meth) acrylate may be a modified product. Examples of modified (meth) acrylates include triethylene ethylene glycol diacrylate, polyethylene glycol diacrylate, ethylene oxide-modified trimethyl propanetri (meth) acrylate, ethylene oxide-modified pentaerythritol tetraacrylate, and ethylene oxide-modified bisphenol A. Ethylene oxide-modified (meth) acrylate including di (meth) acrylate and ethylene oxide-modified nonylphenol (meth) acrylate, tripropylene ethylene glycol diacrylate, polypropylene glycol diacrylate, propylene oxide-modified trimethyl propantri (meth) acrylate, propylene Ethylene oxide-modified (meth) acrylate including oxide-modified pentaerythritol tetraacrylate and propylene oxide-modified glycerin tri (meth) acrylate, caprolactone-modified (meth) acrylate including caprolactone-modified trimethylol propantri (meth) acrylate, and caprolactam-modified. Includes caprolactam-modified (meth) acrylates and the like, including dipentaerythritol hexa (meth) acrylates and the like.

The (meth) acrylate may be a polymerizable oligomer. Examples of (meth) acrylates that are polymerizable oligomers include polybutadiene (meth) acrylate oligomers, polyisoprene (meth) acrylate oligomers, epoxy (meth) acrylate oligomers, aliphatic urethane (meth) acrylate oligomers, and aromatic urethane (meth). ) Acrylate oligomers, polyester (meth) acrylate oligomers, linear (meth) acrylic oligomers and the like.

Examples of the above compounds having an allyl ether group include phenylallyl ether, o-, m-, p-cresol monoallyl ether, biphenyl-2-all monoallyl ether, biphenyl-4-all monoallyl ether, and butyl allyl ether. , Cyclohexyl allyl ether, cyclohexane methanol monoallyl ether, diallyl phthalate ether, diallyl ether isophthalate, dimethanol tricyclodecanedialyl ether, 1,4-cyclohexanedimethanol diallyl ether, alkylene (2-5 carbon atoms) glycol diallyl ether , Polyethylene glycol diallyl ether, glycerin diallyl ether, trimethylolpropane diallyl ether, pentaerythritol diallyl ether, polyglycerin (polymerization degree 2-5) diallyl ether, trimethylolpropantriallyl ether, glycerin triallyl ether, pentaerythritol tetraallyl ether And tetraallyloxyethane, pentaerythritol triallyl ether, diglycerin triallyl ether, sorbitol triallyl ether and polyglycerin (polymerization degree 3 to 13) polyallyl ether and the like.

Examples of the compounds having a vinyl ether group include butyl vinyl ether, butyl propenyl ether, butyl butenyl ether, hexyl vinyl ether, 1,4-butanediol divinyl ether, ethylhexyl vinyl ether, phenylvinyl ether, benzyl vinyl ether, ethylethoxyvinyl ether, and acetylethoxy. Ethoxyvinyl ether, cyclohexyl vinyl ether, tricyclodecane vinyl ether, adamantyl vinyl ether, cyclohexanedimethanol divinyl ether, tricyclodecanedimethanol divinyl ether, EO adduct divinyl ether of bisphenol A, cyclohexanediol divinyl ether, cyclopentadiene vinyl ether, norbornyldi Methanol divinyl ether, divinyl resorcin, divinyl hydroquinone, ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, propylene glycol divinyl ether, dipropylene glycol vinyl ether, butylene vinyl ether, dibutylene glycol divinyl ether, 4-cyclohexanedivinyl ether , Oxanolbonandivinyl ether, neopentyl glycol divinyl ether, glycerin trivinyl ether, oxetane divinyl ether, glycerin ethylene oxide adduct trivinyl ether (additional moles of ethylene oxide 6), trimethylolpropane trivinyl ether, trivinyl ether ethylene oxide adduct trivinyl ether ( The number of added moles of ethylene oxide 3), pentaerythritol trivinyl ether, ditrimethylol propanehexavinyl ether and their oxyethylene adducts are included.

Examples of the above-mentioned compound having a maleimide group include phenylmaleimide, cyclohexylmaleimide, n-hexylmaleimide and the like.

Examples of the above compounds having a (meth) acrylamide group include (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, and N-hydroxyethyl ( Meta) acrylamide, N-butyl (meth) acrylamide, isobutoxymethyl (meth) acrylamide, diacetone (meth) acrylamide, bismethyleneacrylamide, di (ethyleneoxy) bispropylacrylamide, and tri (ethyleneoxy) bispropylacrylamide. included.

Examples of cationically polymerizable compounds include epoxy compounds, vinyl ether compounds, oxetane compounds and the like.

Examples of the above epoxy compounds include glycidyl (meth) acrylate, allyl glycidyl ether, 2-ethylhexyl glycidyl ether, phenol (polyethyleneoxy) 5-glycidyl ether, butylphenyl glycidyl ether, hexahydrophthalic acid glycidyl ester, and lauryl glycidyl ether. Monofunctional epoxy compounds including 1,2-epoxycyclohexane, 1,4-epoxycyclohexane, 1,2-epoxy-4-vinylcyclohexane and norbornene oxide, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, propylene glycol di Glycidyl ether, tripropylene glycol diglycidyl ether, bisphenol A diglycidyl ether, polypropylene glycol # 400 diglycidyl ether, neopentyl glycol diglycidyl ether, 4- (2,3-epoxypropan-1-yloxy) -N, N- Bis (2,3-epoxypropan-1-yl) -2-methylaniline, glycidyl methacrylate, alkylphenol monoglycidyl ether, 4,4-methylenebis [N, N-bis (oxylanylmethyl) aniline] and 1,6 Bifunctional epoxy compounds including hexanediol diglycidyl ether, polyglycerol triglycidyl ether, glycerin polyglycidyl ether, polyglycerin polyglycidyl ether, 3,4-epoxycyclohexylmethyl, 3,4-epoxycyclohexanecarboxylate, Ε-Caprolactone-modified 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexylsancarboxylate, trifunctional or higher functional epoxy compounds including sorbitol polyglycidyl ether and pentaerythritol polyglycidyl ether are included.

Examples of the above oxetane compounds include (3-ethyl-oxetane-3-yl) -methanol, 3- (3-ethyl-oxetane-3-ylmethoxy) -propane-1-ol, 4- (3-ethyl-oxetane). -3-Ilmethoxy) -butane-1-ol, 3- (3-ethyl-oxetane-3-ylmethoxy) -propane-1,2-diol, 1- (3-ethyl-oxetane-3-ylmethoxy) -propane- 2-ol, 1- [2- (3-ethyl-oxetane-3-ylmethoxy) -1-methyl-ethoxy-ethanol, 2- [2- (3-ethyl-oxetane-3-ylmethoxy) -ethoxy] -ethanol Xylylenebis oxetane, 3-ethyl-3 [([3-ethyloxetane-3-yl] methoxy] methyl] oxetane, 2-ethylhexyloxetane, 2- (3-oxetanyl) -1-butanol, 3- (2-) (2-Ethylhexyloxyethyl))-3-ethyloxetane, 3-ethyl-3- (vinyloxymethyl) oxetane, 3- (2-phenoxyethyl) -3-ethyloxetane and (3-ethyl-3-oxetane) Monofunctional oxetane compounds containing methoxymethyl methacrylate and the like, as well as 1,4-benzenedicarboxylic acid bis [(3-ethyl-3-oxetanyl) methyl] ester, 4,4-bis (3-ethyl-3-oxetanyl). Polyfunctional oxetane compounds including methoxymethyl) biphenyl, xylylene bisoxetane and 3,3'-(oxybismethylene) bis (3-ethyloxetane) are included.

1-2. Nanofibers Nanofibers are fibrous fillers having an average fiber diameter of 1000 nm or less. Nanofibers include nanofibers having a branched structure.

Since nanofibers have an average fiber diameter of 1000 nm or less, the increase in viscosity of the curable composition due to scattering of irradiated active energy rays is suppressed, and the decrease in the speed of three-dimensional modeling and the decrease in accuracy of the three-dimensional model are suppressed. At the same time, the strength of the three-dimensional model to be manufactured can be increased.

However, the ratio of the number of nanofibers having a branched structure to the total number of nanofibers is 5% or more. As mentioned above, the nanofibers tend to be oriented horizontally in the curable composition that has landed on the surface of the stage or lower shaped material layer. As a result, it is considered that the nanofibers increase the strength in the horizontal direction of the three-dimensional model, but it is difficult to increase the strength in the height direction. On the other hand, in the nanofiber having the above-mentioned branched structure, even if the main branch is oriented in the horizontal direction, the side branches are branched in a direction other than the horizontal direction (for example, the height direction), so that the three-dimensional model is horizontal. It is possible to increase the strength in directions other than the direction (including the height direction). When the ratio of the number of nanofibers having the branched structure is 5% or more, the ratio of the strength in the height direction to the strength in the horizontal direction derived from the orientation of the nanofibers is sufficiently small. Become. From the above viewpoint, the ratio of the number of nanofibers having the branched structure is preferably 10% or more, and more preferably 20% or more. Although the upper limit of the ratio of the number of nanofibers having a branched structure is not particularly limited, it is preferably 80% or less, preferably 70% or less, from the viewpoint of facilitating the preparation of nanofibers having a branched structure. Is preferable, and 60% or less is more preferable.

The average fiber diameter of the nanofibers is preferably 2 nm or more and 100 nm or less. When the average fiber diameter is 2 nm or more, the strength of the three-dimensional model can be further increased. When the average fiber diameter is 100 nm or less, the nanofibers do not increase the viscosity of the curable composition too much, and the nanofibers do not easily reduce the accuracy of the three-dimensional model. From the above viewpoint, the average fiber diameter of the nanofibers is more preferably 5 nm or more and 80 nm or less, further preferably 10 nm or more and 70 nm or less, and particularly preferably 20 nm or more and 60 nm or less.

The average fiber length of the nanofibers is preferably 0.2 μm or more and 100 μm or less. When the average fiber length is 0.2 μm or more, the nanofibers can sufficiently exert an action as a filler, and the strength of the three-dimensional model can be further increased. When the average fiber length is 100 μm or less, the ejection property is unlikely to be deteriorated due to the nanofibers being clogged with the ink flow path or the inkjet head. From the above viewpoint, the average fiber length of the nanofibers is more preferably 1 μm or more and 80 μm or less, further preferably 1.0 μm or more and 60 μm or less, and particularly preferably 1.0 μm or more and 40 μm or less.

The aspect ratio of the nanofibers is preferably 10 or more and 10000 or less. When the aspect ratio is 10 or more, the nanofibers can sufficiently exert an action as a filler, and the strength of the three-dimensional model can be further increased. When the aspect ratio is 10,000 or less, the nanofibers are less likely to be entangled with each other in the ink flow path, the inkjet head, or the like, resulting in a decrease in ejection property. From the above viewpoint, the aspect ratio of the nanofiber is more preferably 12 or more and 8000 or less, further preferably 15 or more and 2000 or less, particularly preferably 18 or more and 800 or less, and 30 or more and 700 or less. It is particularly preferable that there is, and it is particularly preferable that it is 50 or more and 700 or less.

The presence or absence of a branched structure and the average fiber diameter, average fiber length and aspect ratio of the nanofibers can be measured by analyzing an image obtained by imaging the curable composition with a transmission electron microscope (TEM). it can.

FIG. 1A is a schematic view of nanofiber 100 having no branched structure, and FIGS. 1C to 1D are schematic views of nanofibers 200, 300 and 400 having a branched structure.

Among the ends of these nanofibers, the combination of the ends having the longest length of the fibers connecting the ends is selected, and the fiber connecting these ends is used as the main branch of the nanofibers. When the nanofiber has a protrusion having a length of 50 nm or more that does not form the main branch, the protrusion is a side branch, and the nanofiber having the side branch is a nanofiber having a branched structure.

The nanofiber 100 shown in FIG. 1A has a main branch 110 connecting the ends AB, but does not have a side branch. The nanofiber 200 shown in FIG. 1B has a main branch 210 connecting the ends AB and a side branch 220. The nanofiber 300 shown in FIG. 1C has a main branch 310 connecting the ends AB and a side branch 320. The nanofiber 400 shown in FIG. 1D has a main branch 410 connecting the ends AB and side branches 420 and 430.

In FIGS. 1A to 1D, the nanofibers are shown to have a substantially linear shape for ease of understanding, but the nanofibers usually include many curved portions.

The ratio of the number of nanofibers having a branched structure is the ratio of the number of nanofibers having a branched structure out of 100 nanofibers arbitrarily selected from the images obtained by imaging the curable composition with a TEM. Can be calculated and obtained.

The fiber diameter of one nanofiber can be the sum of the maximum diameter and the minimum diameter measured from the main branch constituting the nanofiber. The average fiber diameter of the nanofibers contained in the curable composition may be the added average of the fiber diameters of 100 nanofibers arbitrarily selected from the images obtained by imaging the curable composition with a TEM. it can.

The fiber length of one nanofiber can be the length between the ends of the fibers constituting the main branch of the nanofiber (the length of the fiber between AB in FIGS. 1A to 1D). The average fiber length of the nanofibers contained in the curable composition may be the added average of the fiber lengths of 100 nanofibers arbitrarily selected from the images obtained by imaging the curable composition with a TEM. it can.

The aspect ratio of one nanofiber can be a value obtained by dividing the fiber length of the nanofiber by the fiber diameter. The aspect ratio of the nanofibers contained in the curable composition can be the summing average of the aspect ratios of 100 nanofibers arbitrarily selected from the images obtained by imaging the curable composition with a TEM. ..

When performing the above measurement, a curable composition diluted 1000 to 10000 times with a light-transmitting solvent such as methyl ethyl ketone that does not react with the nanofibers is imaged by TEM so that the nanofibers do not overlap with each other. It is preferable to do so. The TEM magnification may be adjusted so that 100 or more nanofibers can be imaged.

The curable composition preferably contains 0.05% by mass or more of nanofibers with respect to the total mass of the curable composition. When the content of the nanofibers is 0.05% by mass or more, the ratio of the strength in the height direction to the strength in the horizontal direction of the three-dimensional model derived from the orientation of the nanofibers is sufficiently reduced. Moreover, the strength of the three-dimensional model can be further increased. From the above viewpoint, the content of the nanofibers is preferably 0.08% by mass or more, more preferably 0.1% by mass or more, based on the total mass of the curable composition. It is more preferably 0.5% by mass or more, further preferably 1.0% by mass or more, particularly preferably 1.2% by mass or more, and particularly preferably 1.8% by mass or more.

The curable composition preferably contains 5.0% by mass or less of nanofibers with respect to the total mass of the curable composition. When the content of the nanofibers is 5.0% by mass or less, the ejection property from the nozzle of the inkjet head can be further improved. From the above viewpoint, the content of the nanofibers is preferably 4.0% by mass or less, more preferably 3.0% by mass or less, based on the total mass of the curable composition.

The material of the nanofiber is not particularly limited, and carbon, silica, glass fiber, alumina, alumina hydrate, magnesium oxide, magnesium hydroxide, barium sulfate, calcium sulfate, calcium carbonate, magnesium carbonate, silicate mineral, diatomaceous earth, Inorganic materials including silica sand, titanium oxide, bronze, potassium titanate whiskers, carbon whiskers, sapphire whiskers, beryllia whiskers, boron carbide whiskers, silicon carbide whiskers, silicon nitride whiskers and the like, and organic materials including polysaccharides and the like. But it may be. In particular, since it is lightweight, has high strength, and has a small coefficient of thermal expansion, its strength and heat resistance can be increased without significantly changing the weight of the three-dimensional model to be formed. Nanofibers are preferred.

Nanofibers of polysaccharides are acetylated, carboxylated, carboxymethylated, and silane-coupled with triethoxysilane in order to enhance the affinity with the active energy ray-curable compound or the resin obtained by curing the compound. It may be subjected to a hydrophobization treatment such as an agent treatment and a polyethylenediamine treatment. Further, the polysaccharide nanofiber may be an untreated polysaccharide nanofiber that has not been subjected to the above treatment.

Nanofibers having a high tendency to be hydrophilic, such as nanofibers of polysaccharides containing a large amount of hydroxyl groups, are dispersed in the curable composition and hydrophobized to the extent that the structure of the nanofibers does not collapse (for example, anhydrous). Substitution of hydroxyl groups with acetic anhydride, etc.) may be performed.

Examples of the above-mentioned polysaccharides include cellulose, hemicellulose, lignocellulose, chitin, chitosan and the like. Of these, cellulose and chitin are preferable, and cellulose is more preferable, from the viewpoint of further increasing the strength of the three-dimensional model.

Cellulose nanofibers (hereinafter, also simply referred to as "nanocellulose") are fibers obtained by plant-derived fibril or mechanical defibration of plant cell walls, biosynthesis by acetic acid bacteria, electrospinning method, or the like. Cellulose nanofibers containing nanofibrils as the main component, which are formed by aggregating the above-mentioned celluloses in the form, may be used. Further, nanocellulose is mainly composed of the above-mentioned nanofibrils crystallized in a whisker shape (needle shape) obtained by mechanically defibrating a plant-derived fiber or a plant cell wall and then treating with an acid or the like. Cellulose nanocrystals may be used, or other shapes may be used. The nanocellulose may contain cellulose as a main component, and may contain lignin, hemicellulose, and the like. Nanocellulose containing hydrophobic lignin without delignin treatment is preferable because it has a high affinity with the active energy ray-curable compound or a resin obtained by curing the compound.

Only one type of nanofiber may be contained in the curable composition, or two or more types may be contained. The above-mentioned preferable materials are preferable as long as they are the main components of nanofibers, because the above-mentioned effects can be obtained. When a material is the main component of nanofibers, the material is 50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass, based on the total mass of nanofibers. As mentioned above, it means that it is 99% by mass or more particularly preferably.

The shape of the nanofibers (including the presence or absence of a branched structure and the average fiber diameter, the average fiber length and the aspect ratio) can be adjusted to the above range by changing the method for producing the nanofibers by a known method. For example, when the nanofiber is nanocellulose, the method of defibration or synthesis (strength of defibration, etc.) and the number of defibration may be adjusted. Once a manufacturing method for obtaining a desired shape is obtained for each material, nanofibers may be manufactured by the method from the next time.

1-3. Other Components The resin composition may further contain other components including a photopolymerization initiator, a sensitizer, a photopolymerization initiator auxiliary agent, a polymerization inhibitor and a peeling accelerator. These components may be used alone or in combination of two or more.

1-3-1. Photopolymerization Initiator The photopolymerization initiator contains a photoradical initiator when the active energy ray-curable compound is a compound having a radically polymerizable functional group, and the active energy ray-curable compound is cationically polymerized. When it is a compound having a sex functional group, it contains a photoacid generator. The above-mentioned resin composition may contain only one kind of photopolymerization initiator, or may contain two or more kinds of photopolymerization initiators. The photopolymerization initiator may be a combination of both a photoradical initiator and a photoacid generator.

Examples of photoradical initiators include 2-hydroxy-2-methyl-1-phenylpropan-1-one (BASF, IRGACURE 1173 (“IRGACURE” is a registered trademark of the company)), 2-hydroxy-1. -{4- [4- (2-Hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propane-1-one (BASF, IRGACURE 127, etc.), 1- [4- (2) -Hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propane-1-one (BASF, IRGACURE 2959, etc.), 2,2-dimethoxy-1,2-diphenylethane-1-one (BASF) , IRGACURE 651, etc.), benzyl dimethyl ketal, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2) -Propyl) ketone, 1-hydroxycyclohexyl-phenylketone, 2-methyl-2-morpholino (4-thiomethylphenyl) propan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -Butanone, benzoin, benzoin methyl ether, benzoin isopropyl ether, diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, benzyl, methylphenylglioxy Estel, benzophenone, methyl-4-phenylbenzophenone o-benzoyl benzoate, 4,4'-dichlorobenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyl-diphenylsulfide, acrylicized benzophenone, 3,3', 4, 4'-tetra (t-butylperoxycarbonyl) benzophenone, 3,3'-dimethyl-4-methoxybenzophenone, 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone , Mihira-Ketone, 4,4'-diethylaminobenzophenone, 10-butyl-2-chloroacridone, 2-ethylanthraquinone, 9,10-phenanthrene quinone, phenylquinone and 2,4-diethyloxanthene-9. -Includes on and so on.

Examples of photoacid generators include triarylsulfonium hexafluorophosphate salt, iodonium (4-methylphenyl) (4- (2-methylpropyl) phenyl) hexafluorophosphate, triarylsulfonium hexafluoroantimonate, and 3- Includes methyl-2-butenyl tetramethylene sulfonium hexafluoroantimonate and the like.

The content of the photopolymerization initiator may be as long as the resin composition can be sufficiently cured, and may be, for example, 0.01% by mass or more and 10% by mass or less with respect to the total mass of the resin composition.

The above resin composition is a photosensitizer, as long as it enables the formation of a three-dimensional model by irradiation with active energy rays and does not significantly cause unevenness in intensity in the height direction of the formed three-dimensional model. It may contain any known additive selected from polymerization inhibitors, UV absorbers, antioxidants, coloring materials such as dyes and pigments, antifoaming agents and surfactants.

1-3-2. Sensitizer Examples of the sensitizer include those that exhibit a sensitizing function by light having a wavelength of 400 nm or more. Examples of such sensitizers include anthracenes including 9,10-dibutoxyanthracene, 9,10-diethoxyanthracene, 9,10-dipropoxyanthracene and 9,10-bis (2-ethylhexyloxy) anthracene. Derivatives are included. Examples of commercially available sensitizers include DBA and DEA manufactured by Kawasaki Kasei Chemicals, Inc.

1-3-3. Photopolymerization Initiator Auxiliary Agent Examples of the photopolymerization initiator auxiliary agent include aromatic tertiary amine compounds and other tertiary amine compounds. Examples of aromatic tertiary amine compounds include N, N-dimethylaniline, N, N-diethylaniline, N, N-dimethyl-p-toluidine, N, N-dimethylamino-p-benzoic acid ethyl ester, Includes N, N-dimethylamino-p-benzoic acid isoamylethyl ester, N, N-dihydroxyethylaniline, triethylamine and N, N-dimethylhexylamine.

1-3-4. Polymerization Inhibitors Examples of polymerization inhibitors include (alkyl) phenol, hydroquinone, catechol, resorcin, p-methoxyphenol, t-butylcatechol, t-butylhydroquinone, pyrogallol, 1,1-picrylhydrazyl, phenothiazine, p-benzoquinone, nitrosobenzene, 2,5-di-t-butyl-p-benzoquinone, dithiobenzoyl disulfide, picric acid, cuperon, aluminum N-nitrosophenyl hydroxylamine, tri-p-nitrophenylmethyl, N- (3) -Oxyanilino-1,3-dimethylbutylidene) aniline oxide, dibutyl cresol, cycloquinone oxime cresol, guayacol, o-isopropylphenol, butyraldoxime, methyl ethyl ketoxim and cyclohexanone oxime.

1-3-5. Peeling accelerator A peeling accelerator is used when a three-dimensional model is manufactured while supporting the model layer being manufactured from below by a support model in which the support material ink for three-dimensional modeling by the material jet method is cured. It is a compound that makes it easier to separate the modeled object from the support modeled object.

Examples of peeling accelerators include higher fatty acid esters containing silicone-based surfactants, fluorine-based surfactants and stearyl sebacate. From the viewpoint of facilitating peeling, the peeling accelerator is preferably a silicone surfactant. The content of the peeling accelerator is preferably 0.01% by mass or more and 3.0% by mass or less with respect to the total mass of the curable composition. By setting the content of the peeling accelerator to 0.01% by mass or more with respect to the total mass of the curable composition, a three-dimensional model in which the model material ink is cured and a support in which the support material ink is cured. The peelability from the modeled object can be further improved. By setting the content of the peeling accelerator to 3.0% by mass or less with respect to the total mass of the curable composition, the droplets of the curable composition after landing and before curing spread too much, resulting in a three-dimensional model. It is possible to make it difficult for the shape of the shape to be distorted.

2. Ink set The curable composition described above can be used as a model material ink for three-dimensional modeling by the material jet method. At this time, the model material ink and a known support material ink can be combined to form an ink set. it can. The ink set may be in a form that can be used to form the same three-dimensional model by packing and selling the model material ink and the support material ink. For example, the model material ink and the support material ink may be contained in a plurality of ink cartridges independently, or a plurality of ink accommodating portions may be integrally formed in each ink accommodating portion. It may be an ink cartridge containing the support material ink.

2-1. Support material ink The support material ink is a material that cures depending on the temperature and the cured product is thermally melted from the viewpoint of facilitating removal, or is photocurable and the cured product is water-soluble or water-swellable. It preferably contains a material.

Examples of materials that cure depending on the temperature and in which the cured product is thermally meltable include waxes including paraffin wax, microcrystalline wax, carnauba wax, ester wax, amide wax and PEG20000.

Examples of materials that are photocurable and whose cured product is water-soluble or water-swellable include a water-soluble compound having a photopolymerizable functional group, a cleavage-type radical initiator, and a photocurable resin composition containing water as a main component. Is included. The support material may further contain a water-soluble polymer.

Examples of water-soluble compounds having photopolymerizable functional groups that can be contained in the support material ink include polyoxyethylene di (meth) acrylate, polyoxypropylene di (meth) acrylate, (meth) achloroylmorpholine and hydroxyalkyl (meth). Included are water-soluble (meth) acrylates, including meta) acrylates, and water-soluble (meth) acrylamides, including (meth) acrylamide, N, N-dimethyl (meth) acrylamide and N-hydroxyethyl (meth) acrylamide. Examples of the cleaved radical initiator contained in the support material include the above-exemplified compounds. Examples of water-soluble polymers that can be included in the support material include polyethylene glycol, polypropylene glycol and polyvinyl alcohol.

3. 3. Method for manufacturing three-dimensional model In the method for manufacturing a three-dimensional model according to the present invention, in addition to using the above-mentioned curable composition as model material ink, model material ink is ejected from a nozzle of an inkjet head to form an uncured ink layer. Three-dimensional modeling in which the model material ink is cured, including the step of manufacturing and the step of irradiating the modeling region containing the model material ink contained in the formed uncured ink layer with active energy rays to form a model material layer. It can be carried out in the same manner as a known manufacturing method of a product. The uncured ink layer refers to a layer formed by ejected model material ink and arbitrarily ejected support material ink. By irradiating the modeling region containing at least the model material ink among the uncured ink layers with active energy rays, a modeling object layer which is each layer in which the three-dimensional modeling object to be manufactured is finely divided into flakes is produced. A three-dimensional model is produced by performing the steps of forming the uncured ink layer and the process of forming the model layer a plurality of times in this order and laminating the formed model layers in the height direction. ..

3-1. Step of forming uncured ink layer In the uncured ink layer, model material ink and optionally support material ink are ejected from the nozzle of the inkjet head and landed on the surface of the stage or the lower model layer or the lower support layer. Can be produced.

3-1-1. Discharge and landing of model material ink Model material ink is included in the uncured ink layer by being ejected based on the data of the position occupied by the model material in each layer of the three-dimensional model to be manufactured and landing at a predetermined position. Form a modeling area. The model material ink is ejected so as to land on the stage, on the modeled object layer already formed by being irradiated with light, or on the support layer arbitrarily formed. The modeling region included in each uncured ink layer is irradiated with active energy rays in a later step to cure the model material ink and form a modeling object layer.

From the viewpoint of further improving the ejectability from the nozzle, the amount of droplets per drop of the model material ink is preferably 1 pl or more and 70 pl or less. From the viewpoint of obtaining a three-dimensional model having higher resolution, it is more preferable that the amount of droplets per drop of the model material ink is 2 pl or more and 50 pl or less.

3-1-2. Discharge and landing of support material ink The support material ink is ejected based on the data of the position where it is desirable to arrange the support material to support the model material formed thereafter in each layer of the three-dimensional model to be manufactured. By landing at a predetermined position, a support region arbitrarily included in the uncured ink layer is formed. The support material ink is then cured to form a support layer. The support model formed by laminating the support layer fills the space portion of the three-dimensional model being manufactured and supports the model layer being manufactured from the lower part in the direction of gravity. As a result, the support model can prevent the three-dimensional model being manufactured from collapsing due to gravity from a portion where the model layer does not yet have sufficient strength, especially in an overhanging portion.

The support layer may be manufactured independently of the model layer. However, from the viewpoint of shortening the working time, it is preferable to form the modeled object layer and the support layer in the same ink layer at the same time. Specifically, the model material ink and the support material ink are ejected simultaneously or continuously to form the same uncured ink layer.

At this time, the inkjet head may be provided with a nozzle for the support material ink and a nozzle for the model material ink so that the model material ink and the support material ink are ejected from the same inkjet head, or the model material ink may be ejected. And the support material ink may be ejected from different inkjet heads. From the viewpoint of shortening the working time, it is preferable to eject the model material ink and the support material ink independently from different inkjet heads.

3-2. Step of Producing a Modeling Material Layer The formed uncured ink layer can be produced by irradiating an active energy ray from a light source to cure the model material ink contained in the modeling area. Examples of active energy rays that can be used to cure model material inks include ultraviolet and electron beams. When the uncured ink layer includes the support area, the support material ink contained in the support area can be cured to prepare the support layer.

Examples of light sources for irradiating ultraviolet rays include fluorescent tubes including low-pressure mercury lamps and germicidal lamps, cold cathode tubes, ultraviolet lasers, mercury lamps having an operating pressure within the range of 100 Pa or more and 1 MPa or less, metal halide lamps, and light emitting. Includes diodes (LEDs). From the viewpoint of curing the three-dimensional object faster, the light source is preferably a high-pressure mercury lamp, a metal halide lamp, and an LED capable of irradiating ultraviolet rays with ^{an illuminance of 100 mW / cm 2 or more, and among these, the power consumption is reduced.} From the viewpoint, LED is preferable. Specific examples of the LED include a 395 nm water-cooled LED manufactured by Phoseon Technology.

Examples of methods for generating electron beams include a scanning method, a curtain beam method, and a broad beam method. From the viewpoint of generating electron beams more efficiently, the curtain beam method is preferable. Examples of light sources capable of irradiating electron beams include Curetron EBC-200-20-30, manufactured by Nissin High Voltage, and manufactured by Min-EB and AIT.

When the active energy ray is an electron beam, the acceleration voltage of electron beam irradiation is preferably 30 kV or more and 250 kV or less, and more preferably 30 kV or more and 100 kV or less, from the viewpoint of sufficient curing. Further, from the viewpoint of sufficient curing, the electron beam irradiation amount is preferably 30 kGy or more and 100 kGy or less, and more preferably 30 kGy or more and 60 kGy or less. From the viewpoint of enhancing the adhesiveness between the upper and lower layers, the model material ink to be irradiated is not completely cured but becomes a semi-cured state, and when the model material ink ejected thereafter is irradiated with the active composition, the above-mentioned half is performed. The strength may be set so that the cured model material ink is completely cured.

When the support material ink is cured depending on the above-mentioned temperature and the cured product contains a material that is heat-meltable, the support material ink that has been heated and discharged and landed at the position to be the support region is cooled. As a result, a support layer is formed. When the support material ink contains the above-mentioned photocurable material whose cured product is water-soluble or water-swellable, the cured product layer and the support layer are formed by irradiating the cured region and the support region with active energy rays. Can be formed simultaneously or independently.

From the viewpoint of facilitating the formation of the next layer, the formed shaped object layer and the support layer may be flattened on the surface by a film thickness adjusting roller or the like.

3-3. Step of removing the support shaped object When the manufacturing method of the present invention includes the step of ejecting the support material ink, after forming all the shaped object layers and the support layer, the support shaped object formed by laminating the support layers is removed. Will be done.

When the support material ink contains a material that cures depending on the temperature and the cured product is heat-meltable, the three-dimensional model precursor is held in an environment of 60 ° C. or higher and 130 ° C. or lower for 1 minute or more and 5 minutes or less. By doing so, the support material can be removed. When the support material ink contains a material that is photocurable and the cured product is water-soluble or water-swellable, for example, in water at -30 ° C or higher and + 30 ° C or lower than the Tg of the support model for 10 minutes or more and 60. The support model is removed by immersing the precursor of the three-dimensional model for 10 minutes or more and leaving it in an environment with a relative humidity of 50% or more and 90% or less and a temperature of 40 ° C or more and 70 ° C or less for 10 minutes or more and 60 minutes or less. be able to.

4. Three-dimensional modeling device FIG. 2 is an exemplary side view of a three-dimensional modeling device by the material jet method. The three-dimensional modeling apparatus 500 is a model in which a stage 11 having a drive unit (not shown) for driving up and down (Z direction in the drawing) and a rail (not shown) movable left and right (in the XY direction in the drawing) are arranged. An inkjet device 12 for ejecting material ink or support material ink is provided.

The inkjet device 12 includes an inkjet head 13 for model material ink, an inkjet head 14 for support material ink, a film thickness adjusting roller 15, and a light source 16.

The model material ink inkjet head 13 and the support material ink inkjet head 14 each have a nozzle for ejection. The model material ink inkjet head 13 communicates with the pump 13b and the model material ink tank 13c via the pipe 13a. The model material ink can be filled in the model material ink tank 13c. The support material ink inkjet head 14 communicates with the pump 14b and the support material ink tank 14c via the pipe 14a. The support material ink can be filled in the support material ink tank 14c. A plurality of model material ink tanks 13c and support material ink tanks 14c may be provided, and an ink set number may be assigned to each.

The model material ink inkjet head 13 ejects the model material ink and lands the three-dimensional object at a position corresponding to each layer subdivided in the height direction. The support material ink inkjet head 14 ejects the support material ink and lands it at a position where the support layer is formed at the height of each of the above layers. As a result, an uncured ink layer is formed. The ejection of the model material ink from the model material ink inkjet head 13 and the ejection of the support material ink from the support material ink inkjet head 14 are controlled by the pump 13b and the pump 14b, respectively.

After that, the light source 16 irradiates the landed model material ink with active energy rays to cure the model material and form a modeled object layer. At this time, the support material ink that has landed at the same time may also be irradiated with active energy rays to form a support layer. From the viewpoint of making the thickness of the modeled object layer uniform, after irradiation with the active energy rays, the film thickness adjusting roller 15 polishes a thick portion of the modeled object layer or the support layer to form the thickness of the layer. May be uniform.

After that, the stage 11 moves downward by one layer having a thickness of the modeled object layer. When the stage 11 moves, an uncured ink layer is formed by ejecting the model material ink and the support material ink from the model material ink inkjet head 13 and the support material ink inkjet head 14, and the active energy rays are irradiated from the light source 16. The formation of the modeled object layer and the support layer, the polishing of the modeled object layer and the support layer by the film thickness adjusting roller 15, and the downward movement of the stage 11 are repeated to form a three-dimensional modeled object having the support modeled object.

Finally, the three-dimensional model provided with the support model is taken out from the three-dimensional model device 500, and the support material is removed to obtain the three-dimensional model.

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

1. 1. Nanofiber 1-1. Preparation of Nanofibers BiNFi-s, a cellulose nanofiber dispersion liquid manufactured by Sugino Machine Limited, was defibrated at a pressure of 150 MPa using a nanovita, a wet high-pressure disperser manufactured by Yoshida Kikai Kogyo Co., Ltd. It was confirmed that branching increased as the number of defibration treatments increased, but there was almost no difference in fiber length and fiber diameter. The defibration treatment was repeated until a predetermined branching ratio was obtained to obtain an aqueous dispersion of cellulose nanofibers 1 to cellulose nanofibers 4.

Wet high pressure manufactured by Yoshida Kikai Kogyo Co., Ltd. for a mixed solution containing 0.02% by weight of KC floc (manufactured by Nippon Paper Industries) as a cellulose raw material and 0.005% by weight of sodium polyacrylate as a dispersant. The fiber was defibrated at a pressure of 150 MPa using a nanovita, which is a disperser. It was confirmed that the fiber length became shorter as the number of defibration treatments increased. An aqueous dispersion of cellulose nanofibers 5 was obtained by repeating the defibration treatment until the average fiber length became constant.

The sugarcane residue (bagasse) was added to distilled water and defibrated at a pressure of 150 MPa using NanoVita, a wet high-pressure disperser manufactured by Yoshida Kikai Kogyo Co., Ltd. Two types of cellulose microfibrils were obtained by changing the number of defibration treatments. After adding a citrate buffer (pH 5.0) to these cellulose microfibril dispersions, heat-resistant endoglucanase (345UI / go bagasse) is added, and the mixture is stirred at a heating temperature of 85 ° C. for 72 hours. Obtained an aqueous dispersion of cellulose nanocrystal 1 and cellulose nanocrystal 2.

1-2. Hydrophobicization Cellulose nanofiber 1 is dispersed in N-methylpyrrolidone, and acetic anhydride and pyridine are added with stirring at 80 ° C. so that the hydroxyl group substitution rate (DS value) becomes 1.5, and the hydrophobization treatment is performed. went. Cellulose nanofibers 2 to 5 as well as cellulose nanocrystals 1 and cellulose nanocrystals 2 were also hydrophobized under the same conditions.

1-3. Evaluation of Nanofibers The above-mentioned cellulose nanofibers 1 to 5 and cellulose nanocrystals 1 to cellulose nanocrystals 2 were subjected to solvent substitution with methyl ethyl ketone, and the concentration of cellulose nanofibers or cellulose nanocrystals was 0.001 to 0. It was further diluted with methyl ethyl ketone until it reached about 0001% by mass. 20 μL of the obtained diluted solution was added dropwise to a glass plate, dried, and imaged with a transmission electron microscope (TEM). Based on 100 nanofibers arbitrarily selected from the captured image, the ratio of the number of nanofibers having a branched structure, the average fiber diameter of the nanofibers, the average fiber length of the nanofibers, and the aspect ratio of the nanofibers. Was measured.

At this time, the added average of the maximum diameter and the minimum diameter of the main branches constituting the nanofibers in the captured image is taken as the fiber diameter of the nanofibers, and the added average of the fiber diameters of the 100 nanofibers is taken as each. The average fiber diameter of cellulose nanofibers and cellulose nanocrystals was used.

Further, the length between the ends of the fibers constituting the main branch constituting the nanofibers in the captured image is taken as the fiber length of the nanofibers, and the added average of the fiber lengths of the above 100 nanofibers is taken as each of them. The average fiber length of cellulose nanofibers and cellulose nanocrystals was used.

Further, the value obtained by dividing the fiber length of the nanofibers in the captured image by the fiber diameter is used as the aspect ratio of the nanofibers, and the added average of the aspect ratios of the 100 nanofibers is taken as the respective cellulose. The aspect ratio of nanofibers and cellulose nanocrystals was used.

2. Preparation of Curable Composition An active energy ray-curable compound is added to a dispersion obtained by substituting the above-mentioned cellulose nanofibers 1 to 5 and cellulose nanocrystals 1 and cellulose nanocrystals 2 with methyl ethyl ketone. Isobornyl acrylate (light acrylate IB-XA, manufactured by Kyoeisha Chemical Co., Ltd.) and diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (IRGACURE TPO, manufactured by BASF) as a photopolymerization initiator. 1 part by mass was added to 100 parts by mass of the acrylate, and the mixture was mixed so that the content of the nanofibers was the concentration shown in Table 1 with respect to the isobornyl acrylate. After dispersing this mixed solution with a homogenizer, methyl ethyl ketone was devolatile with an evaporator to obtain curable composition 1 to curable composition 9.

Isobornyl acrylate and diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide are mixed in the same composition ratio as the curable composition 1 to the curable composition 9, and the curable composition 10 containing no nanofibers is mixed. Got

Table 1 shows the nanofibers added to the curable composition 1 to the curable composition 10, the raw material of the nanofibers, the branching ratio, the fiber diameter, the fiber length, the aspect ratio and the content.

3. 3. Manufacture of three-dimensional objects 1A to 10A of three-dimensional objects with a length of 10 mm, width of 80 mm, and thickness (lamination direction) of 4 mm, and three-dimensional objects 1B to 10B of length of 4 mm, width of 10 mm, and thickness of 80 mm (lamination direction). Manufactured by the following method.

A three-dimensional modeling system having an inkjet head (piezo head 512L, manufactured by Konica Minolta) and an ink tank communicating with the inkjet was prepared. The ink tank was filled with any of the curable composition 1 to the curable composition 10. While scanning the stage in the horizontal direction, the composition was ejected from the inkjet head and landed, and UV light was irradiated from the light source to cure the composition to form the first layer.

Then, the inkjet head and the light source were raised in the vertical direction, the composition was landed on the formed first layer and cured in the same manner, and the second layer was laminated. The step of laminating the second layer was repeated while changing the landing position of the composition as needed, and each three-dimensional model was manufactured.

The head temperature at the time of ink ejection was set to 75 ° C. The amount of one drop of ink at the time of ink ejection was 42 pl, and the frequency was 8 kHz. A 395 nm LED was used as the UV light source, and the conditions were set so that ^{each layer was irradiated with light at an illuminance of 100 mW / cm 2 for 1 second.}

4. Evaluation 4-1. Ratio of strength according to modeling direction The bending strength of each of the three-dimensional modeled object 1A and the three-dimensional modeled object 1B was measured according to JIS K 7171. The distance L between the fulcrums was 64 mm, the test speed v was 2 mm / min, and the indenter radius R1 was 5 mm.

The bending strength obtained from the three-dimensional model 1A is X, the bending strength obtained from the three-dimensional model 1B is Y, and the bending strength ratio: Y / X is used. The ratio of the strength of the three-dimensional model to be manufactured according to the modeling direction was evaluated. Similarly, the ratio of the strengths of the three-dimensional model 2A to the three-dimensional model 10A and the three-dimensional model 2B to the three-dimensional model 10B in the modeling direction was evaluated.
◎ Y / X is 0.95 or more ○ Y / X is 0.9 or more and less than 0.95 △ Y / X is less than 0.9 × Y / X is less than 0.85

4-2. Strength improvement rate Using the values of Y / Z obtained from the bending strength Z obtained from the three-dimensional model 10B and the bending strength Y obtained from the three-dimensional models 1B to 9B, the nanofibers are based on the following criteria. The improvement rate of the strength of the three-dimensional shaped objects 1B to 9B due to the addition was evaluated.
◎ Y / Z is larger than 1.2 ○ Y / Z is 1.05 or more and 1.2 or less △ Y / Z is less than 1.05

The results of the above evaluation are shown in Table 2.

As shown in Table 2, the three-dimensional modeling produced by using the curable composition 2 to the curable composition 9 in which the ratio of the number of nanofibers having a branched structure to the total number of nanofibers is 5% or more. The ratio of strength depending on the direction of the object was small, and the strength was greatly improved as compared with the three-dimensional model produced by using the comparative curable composition containing no nanofibers.

In particular, when the curable composition 4 in which the ratio of the number of nanofibers having a branched structure to the total number of nanofibers is 20% or more is used, the ratio of strength depending on the direction of the produced three-dimensional model is smaller. It was.

Further, the curable composition 1 to the curable composition 4 and the curable composition 6 to the curable composition 9 in which the content of the nanofibers with respect to the total mass of the active energy ray-curable compound is 0.5% by mass or more. When is used, the strength of the produced three-dimensional structure is increased, and the curable composition 6 in which the content of nanofibers with respect to the total mass of the active energy ray-curable compound is 1.2% by mass or more is obtained. When used, the strength of the manufactured three-dimensional model was further increased.

Further, when the curable composition 1 to the curable composition 4 having an aspect ratio of nanofibers of 50 or more was used, the strength of the produced three-dimensional model was higher.

On the other hand, when the curable composition 1 in which the ratio of the number of nanofibers having a branched structure to the total number of nanofibers is less than 5% is used, the ratio of the strength depending on the direction of the produced three-dimensional model becomes larger. Was there.

According to the curable composition of the present invention, a three-dimensional molded product having higher strength than the conventional one and a small ratio of the strength in the height direction to the strength in the horizontal direction can be produced by the material jet method. .. Therefore, the present invention is expected to broaden the range of applications for manufacturing a three-dimensional model by the material jet method and contribute to the advancement and popularization of technology in the same field.

11 Stage 12 Inkjet device 13 Inkjet head for model material ink 13a Piping 13b Pump 13c Model material ink tank 14 Inkjet head for support material ink 14a Piping 14b Pump 14c Support material ink tank 15 Roller for film thickness adjustment 16 Light source

Claims (12)

A plurality of formations of a molding layer obtained by curing the curable composition by irradiating a curable composition ejected by an inkjet method and landing on the surface of a stage or a lower molding layer with active energy rays. In a curable composition for producing a three-dimensional model formed by laminating the model layers by rotating the process.
Contains active energy ray-curable compounds and nanofibers,
A curable composition in which the ratio of the number of nanofibers having a branched structure to the total number of the nanofibers is 5% or more. The curable composition according to claim 1, wherein the ratio of the number of nanofibers having the branched structure to the total number of the nanofibers is 10% or more. The curable composition according to claim 1 or 2, wherein the ratio of the number of nanofibers having the branched structure to the total number of the nanofibers is 20% or more. The curable composition according to any one of claims 1 to 3, wherein the average fiber diameter of the nanofibers is 2 nm or more and 100 nm or less. The curable composition according to any one of claims 1 to 4, wherein the average fiber length of the nanofibers is 0.2 μm or more and 100 μm or less. The curable composition according to any one of claims 1 to 5, wherein the nanofiber has an aspect ratio of 10 or more and 10000 or less. The method according to any one of claims 1 to 6, wherein the ratio of the mass of the nanofibers to the total mass of the active energy ray-curable compound is 0.05% by mass or more and 5.0% by mass or less. Curable composition. The curable composition according to any one of claims 1 to 7, wherein the nanofiber contains nanocellulose as a main component. The curable composition according to claim 8, wherein the nanocellulose contains cellulose nanofibers. The curable composition according to claim 8, wherein the nanocellulose contains cellulose nanocrystals. A step of ejecting a droplet of the curable composition according to any one of claims 1 to 10 from a nozzle of an inkjet head and landing it on the surface of a stage or a lower modeled object layer.
A step of irradiating the landed curable composition with active energy rays to form a model layer formed by curing the curable composition.
The step of landing and the step of forming the modeled object layer are performed a plurality of times in this order to stack the modeled object layers.
A method for manufacturing a three-dimensional model. An inkjet head that ejects droplets of the curable composition according to any one of claims 1 to 10 from a nozzle.
The stage and
It is provided with a light source that irradiates an active energy ray to form a model layer formed by curing the droplets.
The light source irradiates the droplets ejected from the inkjet head and landed on the model layer on or below the stage with active energy rays to form a new model layer formed by curing the droplets. A three-dimensional modeling device to be formed.

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