JP2011012224A - Method for producing pigment dispersed composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an increase in viscosity and gelation when a pigment dispersed liquid having high pigment concentration is prepared by using a dispersing device of a bead mill system and to prevent an increase in viscosity and gelation when the pigment dispersed liquid is stored.SOLUTION: The method for producing a pigment dispersed composition containing a pigment, a dispersant, a polymerizable compound and a polymerization inhibitor includes: a process for preparing a mixture containing the pigment, the dispersant, the polymerizable compound and a first polymerization inhibitor; and a process for dispersing each component of the mixture by treating the mixture with a dispersing device. The dispersing device is of a bead mill system, and adopts a circulation system as a liquid feed method of the mixture. The sealing liquid of the dispersing device contains a second polymerization inhibitor. The first and second polymerization inhibitors each contains at least one compound selected from the group comprising hindered amine compounds, nitroso-amine compounds, and quinone compounds.

Description

  The present invention relates to a method for producing a pigment dispersion composition used for an energy beam curable inkjet ink.

  The ink jet recording method is a recording method in which printing is performed by ejecting liquid ink from a nozzle toward a recording medium by using pressure, heat, electric field or the like as a driving source. Such a recording method has recently been expanding the market because of its low running cost, high image quality, and the ability to print various inks according to the application.

  As ink applied to the ink jet recording method, water-based inks mainly composed of water and oil-based inks composed mainly of organic solvents have been used. However, in order to suppress bleeding of printed matter, an ethylenic double medium is used. A solventless energy ray curable inkjet ink that uses a polymerizable compound such as a monomer having a bond and cures the ink by irradiation with energy rays (for example, ultraviolet rays) has attracted attention.

  Dyes are also used as the colorant used in this type of energy ray curable inkjet ink, but the use of pigments has been studied in order to form high-definition images with excellent color developability. In pigment-based energy ray curable inkjet inks, it is necessary to finely disperse pigments in the medium in order to ensure ejection stability when printing by the inkjet recording method. The pigment concentration in the type inkjet ink is as low as about 1 to 5 mass%. Therefore, when the pigment is dispersed with the final composition of the ink, the dispersion for a long time is required, and the production efficiency is lowered.

  From the above viewpoint, in order to improve dispersibility, a mixture containing a pigment and at least one selected from a resin, a dispersant, and a polymerizable compound is dispersed with a two-roll mill to prepare a pigment dispersion with a high pigment concentration Then, a method for producing an energy ray-curable inkjet ink by diluting the pigment dispersion with a polymerizable compound and a photopolymerization initiator has been proposed (for example, see Patent Document 1).

JP 2003-306622 A

  However, since the dispersion apparatus composed of the two-roll mill as described above does not sufficiently take a share in the mixture, the pigment fine particles tend to be insufficient.

  On the other hand, in order to improve the dispersibility of the pigment, it is also conceivable to use a bead mill type dispersion apparatus that can obtain high dispersion energy using dispersion media such as glass beads and ceramic beads. However, the high dispersion apparatus using the dispersion medium as described above can obtain a large dispersion energy, but the heat generated in the dispersion process and the mechanochemical effect can be obtained even if no photopolymerization initiator is added to the pigment dispersion. The radical generated in the polymer easily initiates the polymerization reaction, causing problems such as increase in viscosity and gelation.

  Further, in the bead mill type dispersion device, a mechanical seal method using a seal liquid is adopted to prevent liquid leakage and back flow of the pigment dispersion liquid. In this case, the polymerizable compound undergoes polymerization due to heat generated during dispersion treatment in the mechanical seal portion or radicals generated mechanochemically, resulting in an inappropriate gap in the mechanical seal portion, or clogging of the polymer, thereby causing the rotation shaft. There is a problem that the pigment dispersion liquid leaks or flows backward due to a load on the rotation of the pigment dispersion.

  In Patent Document 1, it is also proposed to use a polymerization inhibitor in order to prevent an increase in viscosity at dispersion or gelation, and a polymerizable compound is obtained by using a phenolic antioxidant among the polymerization inhibitors. It is disclosed that the polymerization reaction can be suppressed. However, when a mixture with a high pigment concentration to which such an antioxidant type polymerization inhibitor is added is dispersed with a high dispersion apparatus using a dispersion medium, the effect of inhibiting the polymerization reaction is small, and the viscosity of the pigment dispersion is high. There is a problem that it is easy to become. Further, there is a problem that the use of the polymerization inhibitor described in Patent Document 1 cannot prevent the pigment dispersion liquid from leaking or backflowing at the mechanical seal portion.

  Furthermore, even when an antioxidant type polymerization inhibitor is added, the viscosity of the prepared pigment dispersion increases remarkably due to aging, and the pigment dispersion becomes a gel when stored for a long time. When preparing an ink industrially by preparing a pigment dispersion with a high pigment concentration as described above and diluting it, after producing a large amount of the pigment dispersion, store it for a certain period, and if necessary It is preferable in production to dilute the pigment dispersion. Therefore, a pigment dispersion excellent in storage stability is required. In addition, pigment dispersions that have once increased in viscosity or gelated due to storage as described above do not recover fluidity even when diluted with a polymerizable compound, and have a low viscosity suitable for ink jet recording, and the pigment is finely dispersed. There is a problem that the produced ink cannot be manufactured.

  The method for producing a pigment dispersion composition of the present invention is a method for producing a pigment dispersion composition comprising a pigment, a dispersant, a polymerizable compound, and a polymerization inhibitor, the pigment, the dispersant, and the polymerizable property. A step of preparing a mixture containing a compound and a first polymerization inhibitor; and a step of treating the mixture with a dispersing device to disperse each component of the mixture, wherein the dispersing device is a bead mill method. And the dispersion apparatus which uses a circulation system as the liquid feeding method of the mixture, the seal liquid of the dispersion apparatus contains a second polymerization inhibitor, the first polymerization inhibitor and the second polymerization inhibitor are And at least one compound selected from the group consisting of a hindered amine compound, a nitrosamine compound and a quinone compound.

  According to the present invention, it is possible to prevent an increase in viscosity and gelation when preparing a pigment dispersion liquid having a high pigment concentration using a bead mill type dispersion apparatus, and the viscosity when the pigment dispersion liquid is stored. Increase and gelation can be prevented.

FIG. 3 is a schematic cross-sectional view showing an example of a bead mill type dispersion apparatus that uses a circulation system as a method for feeding a mixture. It is a schematic cross section which shows an example of the mechanical seal part of a dispersion device.

  The method for producing a pigment dispersion composition of the present invention is a method for producing a pigment dispersion composition comprising a pigment, a dispersant, a polymerizable compound, and a polymerization inhibitor, the pigment, the dispersant, and the polymerizable property. A step of preparing a mixture containing a compound and a first polymerization inhibitor; and a step of treating the mixture with a dispersing device to disperse each component of the mixture. And the dispersion apparatus which uses a circulation system as the liquid feeding method of the said mixture, the sealing liquid of the said dispersion apparatus contains the 2nd polymerization inhibitor, and the said 1st polymerization inhibitor and the said 2nd polymerization inhibitor are And at least one compound selected from the group consisting of a hindered amine compound, a nitrosamine compound and a quinone compound.

  According to the method for producing a pigment dispersion composition of the present invention, it is possible to prevent an increase in viscosity and gelation when preparing a pigment dispersion liquid (pigment dispersion composition) having a high pigment concentration using a bead mill type dispersion apparatus. In addition, it is possible to prevent viscosity increase and gelation when the pigment dispersion is stored. In particular, polymerization of the polymerizable compound in the mechanical seal portion of the dispersing device can be suppressed, and liquid leakage and backflow from the mechanical seal portion can be prevented.

  Hereinafter, embodiments of the present invention will be described in detail.

(Embodiment 1)
First, an embodiment of a method for producing a pigment dispersion composition of the present invention will be described. The production method of the present embodiment includes a step of preparing a mixture containing a pigment, a dispersant, a polymerizable compound, and a first polymerization inhibitor, and the mixture as a method for feeding the mixture by a bead mill method. And a step of dispersing each component of the mixture by treating with a dispersion apparatus using a circulation system. Thereby, the surface of the pigment can be wetted in advance with a dispersant or a polymerizable compound, and even in the case of a mixture having a high pigment concentration, the pigment can be highly dispersed in the dispersion step.

  As said pigment, it is preferable to use either an inorganic pigment, an organic pigment, or both from a weather-resistant viewpoint.

  Specific examples of the inorganic pigment include, for example, titanium oxide, zinc white, zinc oxide, tripone, iron oxide, aluminum oxide, silicon dioxide, kaolinite, montmorillonite, talc, barium sulfate, calcium carbonate, silica, alumina, Cadmium Red, Red, Molybdenum Red, Chrome Vermilion, Molybdate Orange, Yellow Lead, Chrome Yellow, Cadmium Yellow, Yellow Iron Oxide, Titanium Yellow, Chromium Oxide, Pyridian, Cobalt Green, Titanium Cobalt Green, Cobalt Chrome Green, Ultramarine Blue, Examples include ultramarine blue, bitumen, cobalt blue, cerulean blue, manganese violet, cobalt violet, and mica.

  Specific examples of the organic pigment include azo, azomethine, polyazo, phthalocyanine, quinacridone, anthraquinone, indigo, thioindigo, quinophthalone, benzimidazolone, and isoindoline organics. And pigments. Carbon black made of acidic, neutral or basic carbon may also be used. Furthermore, a hollow particle of a crosslinked acrylic resin or the like may be used as the organic pigment.

  Specific examples of the cyan pigment include C.I. I. Pigment blue 1, C.I. I. Pigment blue 2, C.I. I. Pigment blue 3, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 15: 4, C.I. I. Pigment blue 16, C.I. I. Pigment blue 22, C.I. I. And CI Pigment Blue 60. Among these, from the viewpoint of weather resistance and coloring power, C.I. I. Pigment blue 15: 3, C.I. I. Either or both of Pigment Blue 15: 4 are preferred.

  Specific examples of the pigment having the magenta color include C.I. I. Pigment red 5, C.I. I. Pigment red 7, C.I. I. Pigment red 12, C.I. I. Pigment red 48 (Ca), C.I. I. Pigment red 48 (Mn), C.I. I. Pigment red 57 (Ca), C.I. I. Pigment red 57: 1, C.I. I. Pigment red 112, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 168, C.I. I. Pigment red 184, C.I. I. Pigment red 202, C.I. I. Pigment red 209, C.I. I. Pigment red 254, C.I. I. Pigment violet 19 and the like. Among these, from the viewpoint of weather resistance and coloring power, C.I. I. Pigment red 122, C.I. I. Pigment red 202, C.I. I. Pigment red 209, C.I. I. Pigment red 254, and C.I. I. At least one selected from the group consisting of CI Pigment Violet 19 is preferred.

  Specific examples of the pigment having a yellow color include C.I. I. Pigment yellow 1, C.I. I. Pigment yellow 2, C.I. I. Pigment yellow 3, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14C, C.I. I. Pigment yellow 16, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 73, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 75, C.I. I. Pigment yellow 83, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 95, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 98, C.I. I. Pigment yellow 109, C.I. I. Pigment yellow 110, C.I. I. Pigment yellow 114, C.I. I. Pigment yellow 120, C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 129, C.I. I. Pigment yellow 130, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 139, C.I. I. Pigment yellow 147, C.I. I. Pigment yellow 150, C.I. I. Pigment yellow 151, C.I. I. Pigment yellow 154, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 185, C.I. I. Pigment yellow 213, C.I. I. And CI Pigment Yellow 214. Among these, from the viewpoint of weather resistance, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 83, C.I. I. Pigment yellow 109, C.I. I. Pigment yellow 110, C.I. I. Pigment yellow 120, C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 139, C.I. I. Pigment yellow 150, C.I. I. Pigment yellow 151, C.I. I. Pigment yellow 154, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 213, and C.I. I. At least one selected from the group consisting of CI Pigment Yellow 214 is preferred.

  Specific examples of the pigment having the black color include, for example, HCF, MCF, RCF, LFF, and SCF manufactured by Mitsubishi Chemical Corporation; Monarch and Legal manufactured by Cabot; Color black and special black manufactured by Degussa Huls , Printex; Toka Black manufactured by Tokai Carbon Co., Ltd., Raven manufactured by Columbia, etc. Among these, HCF # 2650, HCF # 2600, HCF # 2350, HCF # 2300, MCF # 1000, MCF # 980, MCF # 970, MCF # 960, MCF88, LFFMA7, MA8, MA11, MA77 manufactured by Mitsubishi Chemical Corporation MA100 and Degussa Huls, Printex 95, Printex 85, Printex 75, Printex 55, Printex 45, and at least one selected from the group consisting of Printex 45 are preferable.

  The blending amount of the pigment in the mixture is preferably 8 to 30% by mass, more preferably 10 to 25% by mass with respect to the total amount of the mixture in order to impart high dispersion energy to the pigment during the dispersion step. If it is an inorganic pigment, 20-70 mass% is preferable, and 30-60 mass% is more preferable. According to the production method of the present embodiment, even when such a mixture having a high pigment concentration is dispersed with a high dispersion energy using a dispersion medium, an increase in viscosity or gelation of the pigment dispersion can be sufficiently suppressed. When the amount of the pigment is too small, the mixture has a low viscosity, and the dispersion is likely to be insufficiently dispersed in the dispersion step. Therefore, dispersion for a long time is required, and the production efficiency is lowered. On the other hand, when the amount of the pigment is too large, the viscosity of the pigment dispersion tends to increase in the dispersion step, the fluidity tends to be impaired, and the dispersibility tends to decrease.

  The mixture contains a dispersant in order to improve the dispersibility of the pigment. By previously mixing the pigment and the dispersant before the dispersion step, the surface of the pigment can be appropriately wetted with the dispersant. Specific examples of such a dispersant include ionic or nonionic surfactants and anionic, cationic or nonionic polymer compounds. Among these, a polymer compound containing a cationic group or an anionic group is preferable from the viewpoint of dispersion stability. Examples of commercially available dispersants include “SOLSPERSE” manufactured by Lubrizol, “DISPERBYK” manufactured by BYK Chemie, “EFKA” manufactured by Fuka Additives, and the like. Although the blending amount of the dispersant in the mixture depends on the blending amount of the pigment, it is usually preferably 0.05 to 15% by mass with respect to the total amount of the mixture.

  As the polymerizable compound, a monofunctional monomer or a polyfunctional monomer having one or more ethylenic double bonds in a molecule having a property of being cured by energy rays can be used. In the mixing and stirring step, it is preferable to use a polymerizable compound containing a monofunctional monomer or a bifunctional monomer as a main component. Monofunctional monomers and bifunctional monomers are less reactive than trifunctional or higher polyfunctional monomers, and thus can further suppress an increase in viscosity or gelation during the dispersion process or storage of the pigment dispersion.

  Specific examples of the monofunctional monomer having one ethylenic double bond in the molecule include amyl (meth) acrylate, isoamyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, Decyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, isomyristyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, tridecyl (meth) acrylate, 2-ethylhexyl-diglycol (meth) acrylate, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, neopentyl glycol (meth) acrylic acid benzoate, butoxyethyl (meth) acrylate, ethoxy-diethylene glycol (meth) acrylate, Xy-triethylene glycol (meth) acrylate, methoxy-polyethylene glycol (meth) acrylate, methoxydipropylene glycol (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxy-polyethylene glycol (meth) acrylate, nonylphenol ethylene oxide adduct ( (Meth) acrylate, tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 2-hydroxy-3 -Phenoxypropyl (meth) acrylate, 2- (meth) acryloyloxyethyl-succinic acid, 2- (meth) acryloyloxyethyl-phthalate , 2- (meth) acryloyloxyethyl-2-hydroxyethyl - and phthalic acid. These may be used alone or in combination. The monomer may be substituted with a functional group such as phosphorus or fluorine. Among these, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and tridecyl (meth) acrylate are particularly preferable because of their low viscosity.

  Specific examples of the bifunctional monomer having two ethylenic double bonds in the molecule include 1,3-butylene glycol di (meth) acrylate, 1,4-butylene glycol di (meth) acrylate, Diethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tripropylene glycol diacrylate, cyclohexane dimethanol di (meth) Examples thereof include acrylate and dipropylene glycol di (meth) acrylate. These may be used alone or in combination.

  Specific examples of the polyfunctional monomer having three ethylenic double bonds in the molecule include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, and tris (2-hydroxyethyl). Examples include isocyanurate tri (meth) acrylate, glyceryl tri (meth) acrylate, ethylene oxide-modified products, propylene oxide-modified products, caprolactone-modified products, and the like. These may be used alone or in combination.

  Specific examples of the polyfunctional monomer having four ethylenic double bonds in the molecule include ditrimethylolpropane tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, and modified ethylene oxides thereof. , Propylene oxide modified products, caprolactone modified products, and the like. These may be used alone or in combination.

  Specific examples of the polyfunctional monomer having five ethylenic double bonds in the molecule include, for example, dipentaerythritol hydroxypenta (meth) acrylate, ethylene oxide-modified products, propylene oxide-modified products, and caprolactone. Examples include modified products. These may be used alone or in combination.

  Specific examples of the polyfunctional monomer having 6 ethylenic double bonds in the molecule include dipentaerythritol hexa (meth) acrylate, ethylene oxide modified products, propylene oxide modified products, and caprolactone modified products. Examples include the body. These may be used alone or in combination.

  The above mixture may further contain an oligomer or a prepolymer as the polymerizable compound. Specific examples of such an oligomer or prepolymer include Ebecryl 230, Ebecryl 244, Ebecryl 245, Ebecryl 270, Ebecryl 280 / 15IB, Ebecryl 284, Ebecryl 284, Ebecryl 284, Ebecryl 284, Ebecryl 284, Ebecryl 284, Ebecryl 284, Ebecryl 284 , Ebecryl 4858, Ebecryl 4883, Ebecryl 8402, Ebecryl 8803, Ebecryl 8800, Ebecryl 254, Ebecryl 264, Ebecryl 265, Ebecryl 294 / 35HD, Ebecryl 1259, Ebecryl 1264, Ebecryl 4866, Ebecryl 9260, Ebecryl 8210, Ebecryl 1290, Ebecryl 1290K, Ebecryl 5129, Ebecryl 2000, Ebecryl 2001, Ebecryl 2002, Ebecryl 2100, KRM7222, KRM7735, KRM4842, KRM210, KRM215, KRM4827, KRM4849, KRM6700, KRM6700-20T, KRM204, KRM205, KRM6602, KRM220, KRM4450 , KRM770, IRR567, IRR81, IRR84, IRR83, IRR80, IRR657, IRR800, IRR805, IRR808, IRR810, IRR812, IRR1657, IRR1810, IRR302, IRR450, IRR670, IRR830, IRR835, I R870, IRR1830, IRR1870, IRR2870, IRR267, IRR813, IRR483, IRR813, IRR436, IRR438, IRR446, IRR505, IRR524, IRR525, IRR554W, IRR584, IRR586, IRR745, IRR767, IRR767, IRR767, IRR767 IRR604, IRR605, IRR607, IRR608, IRR609, IRR600 / 25TO, IRR616, IRR645, IRR648, IRR860, IRR1606, IRR1608, IRR1629, IRR1940, IRR2958, IRR2959, IRR3200, IRR3201, IRR3404, IRR3201, IRR3404 RR3412, IRR3415, IRR3500, IRR3502, IRR3600, IRR3603, IRR3604, IRR3605, IRR3608, IRR3700, IRR3700-20H, IRR3700-20T, IRR3700-25R, IRR3701-20R, IRD3702, IRD6302 CN104, CN120, CN124, CN136, CN151, CN2270, CN2271E, CN435, CN454, CN970, CN971, CN972, CN9782, CN981, CN9873, CN991; Laromer ro13L87L, AE87L made by BASF aromer LR8986, Laromer PE56F, Laromer PE44F, Laromer LR8800, Laromer PE46T, Laromer LR8907, Laromer PO43F, Laromer PO77F, Laromer PE55F, Laromer LR8967, Laromer LR8981, Laromer LR8982, Laromer LR8992, Laromer LR9004, Laromer LR8956, Laromer LR8985, Laromer LR8987 , Laromer UP35D, Laromer UA19T, Laromer LR9005, Laromer PO83F, Laromer PO33F, Laromer PO84F, Laromer PO94F, Laromar LR8863, Laromar LR8869, Laromar LR8889, Laromar LR8997, Laromar LR8996, Lamarmer LR9013, Laromar LR9019, Laromar LR9019, Laromar PO9026V, Laromar PO9026V, PE9026V, PE Photomer 5010, Photomer 5429, Photomer 5430, Photomer 5432, Photomer 5562, Photomer 5806, Photomer 5930, Photomer 6008, Photomer 6010, Photomer 6019, Photomer 6184, Photomer 6210, Photomer 6217, Photomer Photomer 6230, Photomer 6891, Photomer 6892, Photomer 6893-20R, Photomer 6363, Photomer 6572, Photomer 3660; Art Resin UN-9000HP, Art Resin UN-9000PEP, Art Resin UN-9200A, Art Resin UN- 7600, Art Resin UN-5200, Art Resin UN-1003, Art Resin UN-1255, Art Resin UN-3320HA, Art Resin UN-3320HB, Art Resin UN-3320HC, Art Resin UN-3320HS, Art Resin UN-901T, Art Resin UN-1200TPK, Art Resin UN-6060PTM, Art Resin UN-6060P; Purple Light UV-6630B manufactured by Nippon Synthetic Chemical Co., Ltd. V-7000B, purple light UV-7510B, purple light UV-7461TE, purple light UV-3000B, purple light UV-3200B, purple light UV-3210EA, purple light UV-3310B, purple light UV-3500BA, purple light UV-3520TL, purple light UV-3700B, purple light UV-6100B, purple light UV-6640B, purple light UV-1400B, purple light UV-1700B, purple light UV-6300B, purple light UV-7550B, purple light UV-7605B, purple light UV-7610B, purple light UV-7620EA, purple light UV-7630B, purple light UV-7640B, purple light UV-2000B, purple light UV-2010B, purple light UV-2250EA, purple light UV-2750B; Kayrad R-280, Kayarad R-146, Kayarad R131, Kayarad R-205, Kayala from Nippon Kayaku Co., Ltd. EX2320, Kayarad R190, Kayarad R130, Kayarad R-300, Kayarad C-0011, Kayarad TCR-1234, Kayarad ZFR-1122, Kayarad UX-2201, Kayarad UX-2301, Kayarad UX3204, Kayarad UX-3301, Kayarad UX-4 Kayarad UX-6101, Kayarad UX-7101, Kayarad MAX-5101, Kayarad MAX-5100, Kayarad MAX-3510, Kayarad UX-4101, and the like.

  Although the compounding quantity of the polymeric compound in the said mixture will not be specifically limited if the compounding quantity of the said pigment can be ensured, 40-90 mass% is preferable with respect to the mixture whole quantity, and 40-70 mass% is more preferable.

  The said mixture contains the 1st polymerization inhibitor containing the at least 1 sort (s) of compound selected from the group which consists of a hindered amine compound, a nitrosamine compound, and a quinone compound. By containing the polymerization inhibitor in the mixture, an increase in viscosity or gelation in the dispersion step can be suppressed even when the mixture having a high pigment concentration is dispersed with a high dispersion energy using a dispersion medium. Moreover, by using the said polymerization inhibitor, even if the prepared pigment dispersion is preserve | saved for a fixed period, the increase in the viscosity of a pigment dispersion and gelatinization are few. Further, when an ink is produced by diluting the pigment dispersion after storage, an ink in which fine viscosity pigments are hardly dispersed can be obtained.

  As the hindered amine compound, a compound having a 2,2,6,6-tetramethylpiperidinyloxy group is preferable. Specifically, for example, bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate, bis (2,2,6,6-tetramethyl-1-decanoic acid) (Octyloxy) -4-piperidinyl) ester and the like. These may be used alone or in combination. Among these, bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate having an N-hydroxy-2,2,6,6-tetramethylpiperidinyl group is preferable. . Examples of the polymerization inhibitor comprising a hindered amine compound having a 2,2,6,6-tetramethylpiperidinyloxy group available on the market include “IRGASTAB UV-10” manufactured by Ciba.

  The quinone compound is preferably a compound having an alkyl group. Specifically, for example, 2,5-di-tert-butyl-1,4-benzoquinone, 2,6-di-tert-butyl-1,4-benzoquinone, 2,5-di-tert-amylbenzoquinone, Examples include 2-tert-butyl-1,4-benzoquinone, 2,5-cyclohexadien-1-one, 2,6-bis (1,1-dimethylethyl) -4- (phenylethylene)-(9Cl), and the like. It is done. These may be used alone or in combination. Among these, 2,5-cyclohexadien-1-one, 2,6-bis (1,1-dimethylethyl) -4- (phenylethylene)-(9Cl) is preferable. As a polymerization inhibitor comprising 2,5-cyclohexadien-1-one, 2,6-bis (1,1-dimethylethyl) -4- (phenylethylene)-(9Cl), which is commercially available, Ciba "IRGASTAB UV-22" manufactured by the company is mentioned.

  Examples of the nitrosamine compound include N-nitroso-N-phenylhydroxylamine, N-nitroso-N-phenylhydroxylamine aluminum salt, N-nitroso-N-phenylhydroxylamine cerium salt, and the like. These may be used alone or in combination.

  The blending amount of the polymerization inhibitor in the mixture depends on the type and blending amount of the polymerizable compound, but is preferably 0.01 to 3% by mass, and 0.05 to 2% by mass with respect to the total amount of the mixture. More preferred. If the amount of the polymerization inhibitor is 0.01% by mass or more, radicals generated during the storage of the dispersion process and the pigment dispersion can be sufficiently captured, and the viscosity and gelation of the pigment dispersion are increased. Further suppression can be achieved. On the other hand, when the blending amount of the polymerization inhibitor is 3% by mass or less, a decrease in polymerization reaction at the time of energy ray irradiation can be suppressed, and an ink having excellent curability can be obtained.

  If the said mixture contains the said polymerization inhibitor, you may further contain a phenolic antioxidant and phosphorus antioxidant. Although the compounding quantity of the said antioxidant in the said mixture is not specifically limited, 0.1-4 mass% is preferable with respect to the mixture whole quantity.

  In preparing the mixture, a conventional mixing stirrer can be used. Specifically, examples of such a mixing stirrer include a disperser, a kneader, and a planetary mixer.

  Next, in order to refine the pigment in the mixture prepared as described above, a dispersion step is performed in which the mixture is dispersed by a bead mill type dispersion apparatus filled with a dispersion medium. By dispersing the mixture having a high pigment concentration with the dispersing device, the pigment can be made into fine particles and a pigment dispersion in which the pigment is dispersed with a small particle diameter can be prepared. As the dispersing device, a conventional bead mill type dispersing device can be used. Specific examples include attritors, ball mills, pin mills, sand mills, dyno mills, and the like. As the dispersion media, conventional dispersion media such as glass beads, ceramic beads, and metal beads (including those whose surfaces are coated with a resin) can be used. Among these, beads made of ceramics such as alumina, zirconia, and titania are preferable. The particle size of the dispersion medium is preferably 0.05 to 2.0 mm, more preferably 0.1 to 1.0 mm, and particularly preferably 0.1 to 0.5 mm.

  The filling rate of the beads into the bead mill type dispersion device is not particularly limited, but is generally 40 to 90%, and preferably 60 to 80% from the viewpoint of the viscosity and particle size of the dispersion. The peripheral speed of the dispersing device is generally 3 to 40 m / s, preferably 3 to 20 m / s from the viewpoint of the viscosity and particle size of the dispersion, and particularly 5 to 12 m / s. preferable.

  As a dispersion processing method (mixing solution feeding method) by the above-mentioned bead mill type dispersion apparatus, a circulation method in which the mixture (slurry) is circulated between the holding tank and the bead mill, and a continuous mixture (slurry) in the bead mill. However, as the dispersing device of this embodiment, a circulation method suitable for a difficult-to-disperse mixture having good workability and a long processing time is used. FIG. 1 is a schematic cross-sectional view showing an example of a bead mill type dispersion apparatus using a circulation system as a mixture feeding method. In FIG. 1, a dispersing device 1 includes a holding tank 3 that prepares a mixture 2 by stirring a pigment, a dispersant, a polymerizable compound, and a polymerization inhibitor, and a dispersion treatment of the mixture to disperse the mixture. A bead mill 4 for dispersing each component, a circulation pipe 5 for connecting the holding tank 3 and the bead mill 4, and a circulation pump 6 are provided. The prepared mixture 2 is dispersed by the bead mill 4 and then returned to the holding tank 3 again, and the same processing as described above is repeated as many times as necessary. In the bead mill 4, in order to make the pigment particles finer and sharpen the particle size distribution, it is better that the number of circulations is larger for the same dispersion time. Moreover, since dispersion | distribution progresses with time in the said circulating operation, particle size control and an automatic operation | movement are enabled, and the progress of dispersion | distribution can be confirmed during operation | movement, and an additive etc. can also be arbitrarily performed.

  The dispersion time varies depending on the kind of the pigment and the polymerizable compound, the processing amount and the composition of the dispersion, and is preferably 30 to 600 minutes. Further, at the time of dispersion, in order to prevent the pigment dispersion from becoming high temperature, it is preferable to prepare the pigment dispersion while cooling the dispersion device.

  The viscosity of the pigment dispersion immediately after the dispersion step is preferably 15 to 100 mP · s at 25 ° C. Further, the dispersion average particle diameter of the pigment immediately after the dispersion step is preferably 20 to 300 nm. The dispersion average particle diameter can be determined using a particle size distribution measuring apparatus.

Moreover, the sealing liquid of the said dispersion apparatus may contain the polymeric compound of the same kind as the said polymeric compound contained in the said pigment dispersion liquid. The above-mentioned “contains the same kind of polymerizable compound as the above-mentioned polymerizable compound” means that both of the polymerizable compounds are in common.
The sealing liquid contains a second polymerization inhibitor containing at least one compound selected from the group consisting of the above-mentioned hindered amine compounds, nitrosamine compounds and quinone compounds. Thereby, it is possible to prevent the polymerizable compound from causing polymerization due to heat generated at the time of dispersion processing in the mechanical seal portion of the dispersion apparatus or radicals generated mechanochemically, and an inappropriate gap is generated in the mechanical seal portion, It is possible to solve the problem that the pigment dispersion liquid leaks or backflows due to a load applied to the rotation of the rotating shaft due to clogging of the polymer.

  The amount of the polymerization inhibitor in the sealing liquid is preferably 1 to 20% by mass, more preferably 2 to 10% by mass, based on the total amount of the sealing liquid, although it depends on the type and the amount of the polymerizable compound. . When the blending amount of the polymerization inhibitor is 1% by mass or more, radicals generated in the dispersion process can be sufficiently captured, and leakage and backflow of the pigment dispersion can be suppressed.

  Here, the mechanical seal will be briefly described with reference to the drawings. FIG. 2 is a schematic cross-sectional view showing an example of a mechanical seal portion of the dispersing device. In FIG. 2, the mechanical seal portion 10 of the dispersion apparatus includes a seal liquid tank 11 filled with a seal liquid 11 a, a dispersion tank 12 filled with a pigment dispersion liquid 12 a, and a rotating shaft 13. A stirring propeller (not shown) is attached to the upper portion of the rotating shaft 13, and this rotates to stir the pigment dispersion 12 a and disperse each component. Further, the lower part of the rotating shaft 13 is filled with the sealing liquid 11a, thereby preventing the liquid leakage and backflow of the pigment dispersion liquid 12a. The seal liquid 11a contains, for example, the same type of polymerizable compound as the polymerizable compound contained in the pigment dispersion 12a, and the same kind of polymerization inhibitor as the polymerization inhibitor contained in the pigment dispersion 12a, for example. By including the polymerization inhibitor in the seal liquid 11a, it is possible to prevent the polymerizable compound from causing polymerization due to heat generated during the dispersion treatment in the mechanical seal portion 10 or radicals generated mechanochemically.

  Further, since the sealing liquid 11a contains the same type of polymerizable compound and polymerization inhibitor as those contained in the pigment dispersion liquid 12a, even if the sealing liquid 11a and the pigment dispersion liquid 12a are mixed somewhat, the pigment dispersion liquid 12a It can prevent affecting the characteristics.

(Embodiment 2)
Next, an embodiment of the pigment dispersion composition of the present invention will be described. The pigment dispersion composition of the present embodiment includes a pigment, a dispersant, a polymerizable compound, and a polymerization inhibitor, and the polymerization inhibitor is selected from the group consisting of a hindered amine compound, a nitrosamine compound, and a quinone compound. And at least one compound that corresponds to the pigment dispersion produced by the production method of Embodiment 1. Since each component of the pigment dispersion composition of this embodiment is the same as that described in Embodiment 1, the description thereof is omitted.

  When producing an energy ray curable inkjet ink using the pigment dispersion composition of this embodiment, a polymerizable compound and a photopolymerization initiator are further mixed with the pigment dispersion composition (pigment dispersion) of this embodiment. What is necessary is just to prepare the ink by performing the dilution process which stirs. By such a dilution step, the pigment concentration in the ink can be reduced, and a low-viscosity ink suitable for the ink jet recording method can be obtained. The blending amount of the pigment in the final composition of the ink is preferably 1 to 5% by mass and more preferably 1 to 2% by mass with respect to the total amount of the ink, although it depends on the type and use of the pigment.

  In the present specification, both a pigment dispersion having a high pigment concentration and an ink diluted with the pigment dispersion are treated as an ink material made of a pigment dispersion composition.

  As the polymerizable compound used in the dilution step, the same type of polymerizable compound as that contained in the pigment dispersion composition can be used. Among these, it is preferable to use a polymerizable compound containing a polyfunctional monomer as a main component in order to obtain a highly curable ink. The blending amount of the entire polymerizable compound in the final composition of the ink is not particularly limited as long as the blending amount of the pigment can be secured, but is preferably 60 to 95% by mass with respect to the total amount of the ink.

  Examples of the photopolymerization initiator include acylphosphine oxides, α-aminoalkylphenones, thioxanthones, arylalkyl ketones, oxime ketones, acyl phosphonates, thiobenzoic acid S-phenyls, titanocenes, and aromatics. Examples include ketones, benzyls, quinone derivatives, and ketocoumarins. Among these, when used together with the polymerizable compound, at least one light selected from the group consisting of acylphosphine oxides, α-aminoalkylphenones, and thioxanthones capable of initiating polymerization with low energy. A polymerization initiator is preferable, and acylphosphine oxides or a mixture of α-aminoalkylphenones and thioxanthones is more preferable.

  Specific examples of the acylphosphine oxides include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,6-dimethoxybenzoyldiphenylphosphine oxide, 2,6-dichlorobenzoyldiphenylphosphine oxide, and 2,3. , 5,6-tetramethylbenzoyldiphenylphosphine oxide, 2,6-dimethylbenzoyldiphenylphosphine oxide, 4-methylbenzoyldiphenylphosphine oxide, 4-ethylbenzoyldiphenylphosphine oxide, 4-isopropylbenzoyldiphenylphosphine oxide, 1-methylcyclohexyl Sanoylbenzoyldiphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine 2,4,6-trimethylbenzoylphenylphosphinic acid methyl ester, 2,4,6-trimethylbenzoylphenylphosphinic acid isopropyl ester, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide Etc. These may be used alone or in combination. Examples of commercially available acylphosphine oxides include “Lucivin TPO” manufactured by BASF.

  Specific examples of the α-aminoalkylphenones include 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1 -(4-morpholinophenyl) butanone-1,2-methyl-1- [4- (methoxythio) -phenyl] -2-morpholinopropan-2-one and the like. These may be used alone or in combination. Examples of α-aminoalkylphenones available on the market include “IRGACURE 369” and “IRGACURE 907” manufactured by Ciba.

  Specific examples of the thioxanthones include thioxanthone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4. -Diethylthioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone and the like. These may be used alone or in combination. Examples of thioxanthones available on the market include “KAYACURE DETX-S” manufactured by Nippon Kayaku Co., Ltd. and “Chivacure ITX” manufactured by Double Bond Chemical.

  The blending amount of the photopolymerization initiator in the final composition of the ink is preferably 2 to 15% by mass based on the total amount of the ink, although it depends on the type and blending amount of the polymerizable compound. When the blending amount of the photopolymerization initiator is 2% by mass or more, an ink having excellent curability and adhesion can be obtained even with low energy irradiation. On the other hand, if the blending amount of the photopolymerization initiator is 15% by mass or less, remaining of unreacted components can be suppressed.

  In the dilution step, it is preferable to add a polymerization inhibitor such as the hindered amine compound. The storage stability of the ink composition can be further improved by adding the polymerization inhibitor in the dilution step.

  In addition, in the dilution step, for the purpose of improving other properties, a surface conditioner, a surfactant, a leveling agent, an antifoaming agent, a pH adjuster, a charge imparting agent, a bactericide, an antiseptic, a deodorant, General additives such as charge control agents, wetting agents, anti-skinning agents, and fragrances may be further added.

  As a mixing stirrer used at the said dilution process, the thing similar to the mixing stirrer used at the mixing stirring process of the above-mentioned mixture can be used.

  The dispersion average particle diameter of the pigment in the ink produced as described above is preferably 20 to 300 nm, and more preferably 50 to 230 nm. Since the pigment dispersion composed of the pigment dispersion composition of the present embodiment has a highly dispersed pigment and excellent dispersion stability of the pigment even at a high pigment concentration, the pigment dispersion that has been stored for a long period of time is diluted. Even when an ink is prepared, it is possible to obtain an ink in which fine pigments as described above are dispersed. If the dispersion average particle size is less than 20 nm, the particles are too fine, and the weather resistance of the printed matter tends to decrease. On the other hand, if the dispersion average particle size exceeds 300 nm, it causes ejection failure in the ink jet.

  In addition, the pigment dispersion comprising the pigment dispersion composition of the present embodiment has little increase in viscosity even when dispersed with high dispersion energy, and is excellent in storage stability. Therefore, after the pigment dispersion is stored for a certain period of time, Can produce an ink having a low viscosity of about 4 to 30 mPa · s at 25 ° C. In addition, the ink has a low viscosity even without heating, and also has good dispersion stability of the pigment, little increase in viscosity and gelation during storage and use, and precipitation of the pigment. It has good storage stability without causing any problems. For this reason, even if it does not substantially contain a diluting solvent such as an organic solvent, in the ink jet recording system, stable ejection can be obtained at room temperature without heating the ink.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example, this invention is not limited to these Examples. In the following, “part” means “part by mass”.

  First, each component used in each example and comparative example is shown in Table 1 below. The display of the composition of Table 2, Table 4, and Table 6 shows that it is the same as the display in the parenthesis of the kind column in Table 1.

<Preparation of pigment dispersion>
In a stainless steel tank, pigments, dispersants, polymerizable compounds, and polymerization inhibitors were weighed out at the blending ratios shown in Table 2, mixed and stirred to prepare 1000 g of each of the mixtures 1 to 7.

  The above mixtures 1 to 7 were dispersed for 2 hours using bead mill type and circulation type dispersing devices 1 to 3 shown in Table 3. In that case, the sealing liquids 1-4 shown in Table 4 were used for the mechanical seal part of each dispersion apparatus. After dispersion, the contents were suction filtered using a glass filter (manufactured by Kiriyama Seisakusho), and pigment dispersions of Examples 1 to 10 and Comparative Examples 1 to 5 shown in Table 5 were prepared.

  The pigment dispersions of Examples 1 to 10 and Comparative Examples 1 to 5 obtained immediately after the preparation as described above were evaluated as follows. The results are also shown in Table 5.

<Dispersing process>
Each dispersion process was observed and the quality of the dispersion process was evaluated according to the following criteria.
A: The dispersion did not flow backward into the seal liquid tank.
B: The dispersion flowed back into the seal liquid tank.

  From Table 5, in Comparative Examples 1-5, since the dispersion liquid flowed back into the seal liquid tank, the following evaluation was not performed on the pigment dispersion liquids of Comparative Examples 1-5.

<Viscosity>
The viscosity of the pigment dispersion immediately after preparation was measured using an R100 viscometer (manufactured by Toki Sangyo Co., Ltd.) under the conditions of 25 ° C. and cone rotation speed 20 rpm.

<Viscosity change>
The pigment dispersion immediately after preparation is stored at 70 ° C. for 7 days, the viscosity of the pigment dispersion after storage is measured in the same manner as described above, and the presence or absence of a change in viscosity is observed. Sex was evaluated.
A: Increase in viscosity by less than 20% B: Increase in viscosity by 20% or more and less than 40%

<Average particle size>
The dispersion average particle diameter of the pigment in the pigment dispersion immediately after preparation was measured using a particle size distribution measuring apparatus FPER-1000 (manufactured by Otsuka Electronics Co., Ltd.).

<Change in particle size>
The pigment dispersion immediately after the preparation is stored for 7 days under the condition of 70 ° C., the dispersion average particle size of the pigment dispersion after storage is measured in the same manner as described above, and the presence or absence of the particle size change is observed. The storage stability was evaluated according to the standard.
A: Increase in dispersion average particle diameter of less than 10% B: Increase in dispersion average particle diameter of 10% or more and less than 20%

  From Table 5, the pigment dispersions of Examples 1 to 10 can prevent an increase in viscosity and gelation when preparing a pigment dispersion with a high pigment concentration using a bead mill type dispersion apparatus, and the above pigments It can be seen that viscosity increase and gelation can be prevented when the dispersion is stored.

  On the other hand, in Comparative Example 1 in which the polymerization inhibitor was not added to the seal liquid, the dispersion flowed back into the seal liquid tank immediately after the start of the dispersion process. Further, in Comparative Example 2 in which the polymerization inhibitor was not added to the pigment dispersion, a small amount of the dispersion flowed back into the seal liquid tank after the dispersion step, and the dispersion also thickened. Furthermore, in Comparative Examples 3 to 5 in which the polymerization inhibitor was not added to both the seal liquid and the pigment dispersion, the dispersion flowed back into the seal liquid tank immediately after the start of the dispersion process.

<Manufacture of ink>
Next, using the pigment dispersions of Examples 1 to 10 just prepared as described above, each pigment dispersion was diluted so that the final composition became the ink composition shown in Table 6 below, to produce each ink. did. As for the polymerization inhibitor, the same polymerization inhibitor as that used at the time of preparing the pigment dispersion was used.

  Using each of the inks immediately after production produced as described above, the continuous discharge property and curability were evaluated as follows.

<Continuous discharge property>
Using an ink jet recording apparatus equipped with a piezo ink jet nozzle, a discharge property test for discharging ink was performed and evaluated. This ink jet recording apparatus includes an ink tank, a supply pipe, a front chamber ink tank immediately before the head, and a piezo head as an ink supply system. In discharging the ink, the ink was heated by a temperature control system in the inkjet recording apparatus so that the viscosity of the ink was 8 to 13 mPa · s at the optimum discharge viscosity at the head. Further, the ink jet recording apparatus was driven at a driving frequency of 28 KHz so that the ink could be ejected with a droplet size of about 6 pl and a resolution of 1200 × 1200 dpi.

  As a result, all of the inks did not cause ejection failure, and did not cause satellites or flight bending.

<Curing property>
The ink was printed on each film made of polycarbonate (PC) by a bar coater to form a printing film having a thickness of 3 μm (bar coater: # 3). This printed film was cured by irradiating with ultraviolet rays so that the total irradiation light quantity was 500 mJ / cm ² using an ultraviolet LED (“NLBU21W01-E2” manufactured by Nichia Corporation) as an irradiation means. Thereafter, the printed film thus cured was touched with a finger, and the presence or absence of ink adhesion to the finger was examined visually. As a result, all the inks were sufficiently cured without sticking to the fingers.

  As described above, it can be seen that the inks prepared by diluting the pigment dispersions of Examples 1 to 10 have no problem even when used in the ink jet recording apparatus.

  According to the present invention, it is possible to prevent an increase in viscosity and gelation when preparing a pigment dispersion liquid having a high pigment concentration using a bead mill type dispersion apparatus, and the viscosity when the pigment dispersion liquid is stored. Increase and gelation can be prevented. In addition, a highly reliable energy ray curable inkjet ink can be provided using the pigment dispersion.

DESCRIPTION OF SYMBOLS 1 Dispersing apparatus 2 Mixture 3 Holding tank 4 Bead mill 5 Circulation pipe 6 Circulation pump 10 Mechanical seal part 11a Seal liquid 11 Seal liquid tank 12a Pigment dispersion liquid 12 Dispersion tank 13 Rotating shaft

Claims (4)

A method for producing a pigment dispersion composition comprising a pigment, a dispersant, a polymerizable compound, and a polymerization inhibitor,
Preparing a mixture comprising a pigment, a dispersant, a polymerizable compound, and a first polymerization inhibitor;
Treating the mixture with a dispersing device to disperse each component of the mixture,
The dispersion device is a dispersion device using a bead mill method and a circulation method as a method of feeding the mixture,
The dispersion liquid of the dispersion device contains a second polymerization inhibitor;
The pigment dispersion composition, wherein the first polymerization inhibitor and the second polymerization inhibitor contain at least one compound selected from the group consisting of a hindered amine compound, a nitrosamine compound, and a quinone compound. Manufacturing method.   The method for producing a pigment dispersion composition according to claim 1, wherein the hindered amine compound has a 2,2,6,6-tetramethylpiperidinyloxy group.   The method for producing a pigment dispersion composition according to claim 1, wherein the quinone compound has an alkyl group.   The pigment dispersion according to any one of claims 1 to 3, further comprising a step of mixing and stirring a polymerizable compound and a photopolymerization initiator in the mixture after dispersing each component of the mixture. A method for producing the composition.

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