JP2017002224A - W/o type emulsion ink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily provide a W/O type emulsion ink excellent in fixability and also excellent in emulsion stability.SOLUTION: Provided is a W/O type emulsion ink having an oil phase and a water phase, in which the water phase includes a 4-6C alkanediol, urethane resin particles, and a coloring agent that is a pigment containing a carboxy group, or a carboxy group-containing polymer fine particles containing a pigment.SELECTED DRAWING: None

Description

  The present invention relates to a W / O type emulsion ink.

As is well known, the stencil printing method uses stencil printing base paper, and moves the ink from one side of the base paper to the other side through the perforated portion of the base paper, thereby printing on the surface of the substrate such as paper. Is.
Conventionally used inks are water-in-oil (W / O) emulsion inks, which are volatile solvents, non-volatile solvents, polymers, colorants, surfactants, water, antifreeze agents, electrolytes, Consists of preservatives. In recent years, a rotary stencil printing press has been automated by a microcomputer and the like, and the operation has been simplified, and the general use of stencil printing at home and abroad is increasing. However, the drying principle of the ink relies on penetrating drying, and most of the color material does not participate in image formation and penetrates into the recording medium, resulting in poor image density and image quality. As a countermeasure, there is a means for increasing the color material concentration in the ink and increasing the amount of the color material remaining on the surface of the recording medium. However, the remaining coloring material is often a pigment, so that the ink that has not been dried due to the rubbing during handling after printing or rubbing during bookbinding or the stacking immediately after printing is transferred to the back side of the printed matter, so-called There is concern about setback.

For this reason, for example, Patent Document 1 proposes a W / O emulsion ink that contains an electrolyte having a monovalent cation in the aqueous phase, prevents aggregation of water-insoluble components, and improves fixability.
In Patent Document 2, a polymer for dispersion and polymer particles made of a linear acrylic polymer having film-forming performance are used in a solvent that dissolves the polymer for dispersion but does not dissolve the polymer particles. Thus, a resin composition for stencil ink having improved fixability has been proposed.
Patent Document 3 proposes a water-based ink for stencil printing that uses a self-dispersing pigment as a colorant and suppresses poor ink recovery.
Patent Document 4 proposes a W / O emulsion ink that contains a copolymer of N-vinylpyrrolidone and vinyl acetate in the aqueous phase and has improved dispersibility of the colorant, water resistance, and stability of the emulsion. ing.
Patent Document 5 discloses an emulsion ink for stencil printing in which the viscosity at a shear rate of 500 s ⁻¹ of the aqueous phase is set to 2.0 mPa · s or more at 23 ° C., and the emulsion stability and the drying property after printing are improved. Proposed.
However, the above-described prior art has not yet provided a W / O type emulsion ink that can ensure sufficient fixability and emulsion stability.

  Accordingly, an object of the present invention is to provide a W / O type emulsion ink having excellent fixability and excellent emulsification stability.

The above problem is solved by the following invention.
A W / O emulsion ink having an oil phase and an aqueous phase, wherein the aqueous phase is an alkanediol having 4 to 6 carbon atoms, urethane resin particles, and a pigment having a carboxy group or a polymer fine particle having a carboxy group. A W / O emulsion ink comprising a colorant containing a pigment.

  According to the present invention, it is possible to provide a W / O type emulsion ink that is excellent in fixability and excellent in emulsion stability.

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

  As described above, the W / O emulsion ink of the present invention contains at least an alkanediol having 4 to 6 carbon atoms as a water-soluble organic solvent component, urethane resin particles, and a pigment or carboxy having a carboxy group in the aqueous phase. It is characterized by containing a colorant containing a pigment in a polymer fine particle having a group, and when contact-transferred to the printing paper, the oil component of the oil phase is permeated and absorbed into the printing paper, and the water in the aqueous phase evaporates. In addition, water-soluble organic solvent components in the aqueous phase are also absorbed and absorbed into the printing paper. As a result, resin particles and colorants that are mainly solids remain on the printing paper, and the remaining resin particles are bound and formed into a film. The pigment is fixed on the printing paper by the function.

  If the water-soluble organic solvent component is an alkanediol having 4 to 6 carbon atoms, it has a relatively low viscosity, so that penetration and absorption into the printing paper as a water-soluble organic solvent component is ensured and is relatively lipophilic. Therefore, the affinity between the resin particles that are the residual solid and the colorant is low, the water-soluble organic solvent component is easily separated from the resin particles and the pigment in the aqueous phase, and the water-soluble organic solvent component together with the oil component into the printing paper. The penetration absorption is promoted, and as a result, the fixing of the pigment to the printing paper by the binding of the resin particles and the film forming ability is ensured. Further, if the alkanediol having 4 or more and 6 or less carbon atoms is 3-methyl-1,3-butanediol, it has a sufficiently low viscosity and a sufficient lipophilicity. Fixation of the pigment to the printing paper is promoted.

  Further, if the resin particles are urethane resin particles, the flexibility derived from the soft segment composed of the polyol having weak cohesion and the adhesion derived from the hard segment composed of the urethane and urea bond having strong cohesion. Fixation to the printing paper is ensured by the property and wear resistance. This is a characteristic that cannot be obtained with other acrylic resin particles, polyester resin particles, and the like. Furthermore, if the urethane resin particles are self-emulsifying urethane resin particles, the urethane resin particles are self-dispersed in the aqueous phase by the functional group modified with the urethane resin particles, and as a result, the use of the pigment dispersant can be suppressed. Here, considering the structure of the dispersant in the case where the urethane resin particles are dispersed in water, the lipophilic group needs to adhere to the urethane resin particles, and the hydrophilic group needs to be able to diffuse to the moisture surrounding the urethane resin particles. is there. A substance having such a structure has a characteristic of dispersing an oleophilic substance in moisture and constituting an oil-in-water (= O / W) emulsion. However, the ink of the present invention has a water-in-oil type (= W / O). ) Since it is an emulsion ink, if a dispersant having the characteristics of an oil-in-water (= O / W) emulsion as described above is used, the water-in-oil (= W / O) emulsion is combined and transferred. The stability of the physical properties of the water-in-oil (= W / O) emulsion ink is impaired. That is, in a water-in-oil (= W / O) emulsion ink, it is desirable to suppress the use of a dispersant in water, and it is desirable to use self-emulsifying urethane resin particles.

Further, if the colorant is a pigment having a carboxy group, the carboxy group assists the dispersion in the aqueous phase, and as a result, the use of the pigment dispersant can be suppressed. Considering the structure of the pigment dispersant in the case of dispersing the pigment in water, it is necessary that the lipophilic group adheres to the pigment and the hydrophilic group can affinity diffuse to the moisture surrounding the pigment. A substance having such a structure has a characteristic of solubilizing a lipophilic substance in moisture and constituting an oil-in-water (= O / W) emulsion, but the ink of the present invention has a water-in-oil type (= W / W). O) Since it is an emulsion ink, the use of a pigment dispersant having the above-described characteristics constituting an oil-in-water (= O / W) emulsion makes the water-in-oil (= W / O) emulsion unite. , Phase inversion, and the physical property stability of the water-in-oil (= W / O) emulsion ink is impaired. That is, in a water-in-oil (= W / O) emulsion ink, it is desirable to suppress the use of a pigment dispersant in water, and it is desirable to use a pigment having a carboxy group. In addition, a pigment having a carboxy group contains a pigment in a colorant that is a self-dispersing pigment in which a carboxy group is bonded to the surface of the pigment directly or through another atomic group, or polymer fine particles having a carboxy group. Sufficient dispersibility is ensured if the colorant is used, and the use of the pigment dispersant in water can be suppressed, and the physical property stability of the water-in-oil (= W / O) emulsion ink can be secured. .
The “self-dispersing pigment” in the present invention refers to a pigment that can be dispersed in a solvent without using a dispersing agent for assisting dispersion.

Examples of the alkanediol having 4 to 6 carbon atoms used in the present invention include 1,2-butanediol, 1,3-butanediol, 1,2-pentanediol, 1,2-hexanediol, 3- Examples thereof include methyl-1,3-butanediol, 4-methyl-1,2-pentanediol, and 3,3-dimethyl-1,2-butanediol. Among them, as described above, the effect of the present invention is remarkable. 3-methyl-1,3-butanediol is particularly preferable from the viewpoint of improving the viscosity. These alkanediols having 4 or more and 6 or less carbon atoms can be used in combination of two or more, and the addition amount thereof is, for example, 15% by mass or less, preferably 4% by mass of the water mass in the W / O type emulsion ink. The content is 12% by mass or less. In addition, water-soluble organic solvents other than alkanediol having 4 to 6 carbon atoms can be used, for example, glycols such as ethylene glycol, zetylene glycol, and propylene glycol; methanol, ethanol, isopropanol, butanol, isobutanol, and the like. Lower saturated monohydric alcohols; polyhydric alcohols such as glycerin and sorbitol;
In the whole water-soluble organic solvent used in the W / O emulsion ink of the present invention, the proportion of the alkanediol having 4 to 6 carbon atoms is preferably 25% by mass or more.

Examples of the urethane resin particles used in the present invention include those dispersed by the use of an emulsifier and self-emulsifying urethane resin particles having a functional group introduced in the resin molecular structure, both of which can be used. In the invention, as described above, self-emulsifying resin particles are preferable.
Commercially available products of such self-emulsifying urethane resin particles include Superflex 130, Superflex 126, Superflex 150, Superflex 150HS, Superflex 170, Superflex 300, Superflex 210, Superflex 500M, Superflex 620. , Superflex 420, Superflex 460, Superflex 470, Superflex 650 (above, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.).
The blending amount of the urethane resin particles in the water phase of the W / O type emulsion ink is 2% by mass or more and 20% by mass or less, preferably 4% by mass or more and 16% by mass or less. In the W / O emulsion ink of the present invention, resin particles other than urethane resin particles can be used. For example, vinyl acetate, acrylate ester, methacrylate ester, vinyl chloride, ethylene-vinyl acetate copolymer Resin particles made of vinyl acetate-acrylic acid ester copolymer, styrene-acrylic acid ester copolymer, vinylidene chloride-acrylic acid ester copolymer, vinyl chloride-vinyl acetate copolymer, etc. may be added as appropriate. Good.
In addition, it is preferable that the ratio for which the urethane resin particle accounts in the whole resin particle used for the W / O type | mold emulsion ink of this invention is 20 mass% or more.
The average particle size of the urethane resin particles is preferably 5 nm to 200 nm.

  Examples of the colorant used in the present invention include a pigment having a carboxy group. For example, a pigment having a carboxy group bonded to the surface of the pigment directly or via another atomic group. The term “having a carboxy group” as used in the present invention means that the acid group amount obtained in accordance with the acid group amount measurement method described in JP-A-2007-3454 is 0.05 [meq / g. ] Points to the above. That is, 3 g of the solid content of the sample is weighed into a 300 ml polyethylene beaker with a poly dropper, and the weighed value is accurately recorded to the fourth decimal place (0.0001 g range). Next, ion exchange water is poured into the polyethylene beaker until 100 g is reached. Furthermore, a stir bar is put, and it sets to a magnetic stirrer and stirs. Then, the electrode and the temperature assurance electrode are immersed. The tip of the titration nozzle is higher than the liquid level, and is separated from the electrode by about 2 cm so that the titration reagent does not reach the electrode. Pipet an appropriate amount of 1 mol / l aqueous potassium hydroxide solution with a pipette. After stirring for 10 minutes, the personal computer instructs the titration start to the potentiometric automatic titrator. After the measurement is completed, meq / g is calculated from the titration amount at the equivalent point automatically printed on the obtained titration curve.

  Examples of the pigment used in the present invention include organic pigments and inorganic pigments. For example, for black and white, carbon blacks such as furnace black, lamp black, acetylene black, and channel black (CI pigment black 7) are used. ), Or a metal such as copper, iron (CI pigment black 11), titanium oxide, or an organic pigment such as aniline black (CI pigment black 1). Further, for color use, C.I. I. Pigment Yellow 1 (Fast Yellow G), 3, 12 (Disazo Yellow AAA), 13, 14, 17, 24, 34, 35, 37, 42 (Yellow Iron Oxide), 53, 55, 81, 83 (Disazo Yellow HR) ), 95, 97, 98, 100, 101, 104, 108, 109, 110, 117, 120, 138, 153, C.I. I. Pigment orange 5, 13, 16, 17, 36, 43, 51, C.I. I. Pigment Red 1, 2, 3, 5, 17, 22 (Brilliant First Scarlet), 23, 31, 38, 48: 2 (Permanent Red B (Ba)), 48: 2 (Permanent Red 2B (Ca)), 48 : 3 (Permanent Red 2B (Sr)), 48: 4 (Permanent Red 2B (Mn)), 49: 1, 52: 2, 53: 1, 57: 1 (Brilliant Carmine 6B), 60: 1, 63: 1, 63: 2, 64: 1, 81 (Rhodamine 6G rake), 83, 88, 101 (Bengara), 104, 105, 106, 108 (Cadmium red), 112, 114, 122 (Quinacridone magenta), 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 185, 190, 193, 209, 219, C.I. I. Pigment violet 1 (rhodamine lake), 3, 5: 1, 16, 19 (quinacridone red), 23, 38, C.I. I. Pigment Blue 1, 2, 15 (phthalocyanine blue R), 15: 1, 15: 2, 15: 3 (phthalocyanine blue G), 15: 4, 15: 6 (phthalocyanine blue E), 16, 17: 127 (bitumen ), 28 (cobalt blue), 29 (ultraviolet), 56, 60, 63, C.I. I. Pigment Green 1, 4, 7, 8, 10, 17, 18, 36, etc., but is not limited thereto.

The pigment having a carboxy group used in the present invention can be obtained by surface-modifying the above-mentioned pigment. For example, a carboxyl group is chemically bonded to the surface of the pigment by a known method, or hypoxia is used. Examples include a method of wet oxidation using a halogen acid or a salt thereof.
In addition, as the self-dispersing pigment, commercially available pigments can be used, and examples thereof include Cab-O-Jet200 and Cab-O-Jet300 (manufactured by Cabot).

  The average particle diameter of the pigment having a carboxy group used in the present invention is, for example, 0.1 μm to 10 μm, and preferably 0.1 μm to 3 μm.

In the present invention, it is also possible to use a colorant in which a pigment is contained in polymer fine particles having a carboxy group.
Here, “pigment is contained” means either or both of a state in which the pigment is encapsulated in the polymer fine particles and a state in which the pigment is adsorbed on the surface of the polymer fine particles. In this case, it is not necessary for all pigments blended in the emulsion ink of the present invention to be encapsulated or adsorbed in polymer fine particles, and even if the pigment is dispersed in the emulsion as long as the effects of the present invention are not impaired. Good. The pigment is not particularly limited as long as it is water-insoluble or poorly water-soluble, and examples thereof include the organic pigments and inorganic pigments described above. In this specification, water-insoluble or poorly water-soluble means that the coloring material does not dissolve 10 parts by mass or more with respect to 100 parts by mass of water at 20 ° C. This means that no separation or sedimentation is observed.

  As the polymer fine particles, those having a carboxy group, for example, polyacrylic acid and polymethacrylic acid are used. For example, the average particle diameter is 0.1 μm to 10 μm. In relation to the blending amount of the polymer fine particles, the blending amount of the pigment is preferably about 10% by mass or more and 200% by mass or less, particularly preferably about 25% by mass or more and 150% by mass or less with respect to the mass of the polymer fine particles. .

  In the aqueous phase of the W / O type emulsion ink of the present invention, the amount of the colorant is 1% by mass or more and 30% by mass or less, preferably mass% or more and 25% by mass or less, more preferably 7% by mass or more. It is 20 mass% or less.

  In the W / O emulsion ink of the present invention, various additives can be blended as necessary. For example, an antiseptic and fungicidal agent can be included in the aqueous phase, and the antiseptic and fungicidal agent added to this aqueous phase is added to prevent bacteria and fungi from growing in the aqueous phase, and stencil printing When the W / O emulsion ink is stored for a long period of time, it is desirable to add an antiseptic and fungicidal agent. The addition amount is 3% by mass or less, preferably 0.01% by mass or more and 0.1% by mass or less of water contained in the ink. Examples of antiseptics and fungicides include 1,2-benzisothiazol-3 (2H) -one, 2-methyl-4-isothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one, 5- In addition to aromatic hydroxy compounds such as chloro-2-methylisothiazol-3 (2H) -one, salicylic acid, phenols, methyl p-oxybenzoate and ethyl p-oxybenzoate and their chlorine compounds, sorbic acid and dehydro Acetic acid or the like is used, and these may be used alone or in combination of two or more.

  It is also possible to contain a pH adjusting agent in the aqueous phase, and the pH adjusting agent added to the aqueous phase is triethanolamine, sodium acetate, triamylamine, etc. A regulator can be added to keep the pH of the aqueous phase at 6 or more and 8 or less. When the pH of the aqueous phase deviates from the above range, there is a problem that the effect is impaired when a water-soluble polymer for thickener is added.

  It is also possible to contain an electrolyte in the aqueous phase. The electrolyte added to the aqueous phase is added to enhance the storage stability of the emulsion ink, but is affected by the introduction of the electrolyte. Care must be taken to ensure that no material is present in the aqueous phase. The electrolyte preferably contains anions such as citrate ions, tartrate ions, sulfate ions, acetate ions, or alkali metal ions or alkaline earth metal ions. As a result, magnesium sulfate, sodium sulfate, sodium citrate, phosphoric acid, etc. Sodium hydrogen, sodium borate, sodium acetate and the like are preferable. For example, the amount of magnesium sulfate added is 0.1 to 2% by mass, preferably 0.5% by mass or more and 1.5% by mass or less of the aqueous phase.

  The oil phase of the W / O emulsion ink of the present invention is composed of oil or a solvent component, an emulsifier, an oily polymer, and other additives as required.

As the oil or solvent component used in the oil phase, known ones can be arbitrarily used and may be mixed. For example, naphthenic oils (Mobil Petroleum's Gargo Oil Arctic Oil 155 and 300ID, Wright, C Heavy, Idemitsu Kosan's Diana Process Oil NP-24, NR-26, NR-68, NS-90S, NM-280 Diana Fresia N-28, N-90, N-17.0, U-46, U-56, U-68, U-130, U-170, U-260, Sansen Oil 410 of Nippon San Oil Co., Ltd., 420, 47.0, 480, 3125, 4240), paraffinic oil (Gargo Oil Arctic 1010, 1022, 1032, 1046, 1068, 1100, 3032, 3046, 3068 from Mobil Oil Co., Ltd. Oil B, C, D, E, Diana Process Oil PX-32, PX-9 from Idemitsu Kosan , PW-32, PW-90, PW-380, PS-32, PS-90, PS-430, Diana Fresia S-32, S-90, P-32, P-90, P-17.0, P -180, P-430), petroleum solvents (Exxon Chemical's Isopar C, E, G, H, L, M, and Exol D30, D40, D80, D110, D130, Japan Oil Company AF Solvent No. 4, No.5, No.6, No.7), vegetable oil (steamed oil, tall oil, corn oil, olive oil, rapeseed oil, castor oil, dehydrated castor oil, soybean oil, palm oil), etc., liquid paraffin, spindle oil, Machine oil, lubricating oil, and the like. In consideration of product safety, it is desirable to use those components having a polycyclic aromatic component that is an aromatic hydrocarbon containing three or more condensed aromatic rings and having a content of less than 3% by mass. However, a highly safe aroma oil, that is, a mutagenicity index MI of less than 1.0, an aroma content (% C _A ) of 20% to 55%, an aniline point of 100 ° C. or less, and a polycyclic aromatic The content of certain benzo [a] anthracene, benzo [b] fluoranthene, benzo [j] fluoranthene, benzo [k] fluoranthene, benzo [a] pyrene, dibenzo [a, j] acridine and the like is 10 based on the total weight of each individual oil. Mass ppm or less The total amount of which is 5.0 mass ppm or less (Japanese Patent Laid-Open No. 11-80640) may be used if necessary.

  Moreover, it is also possible to contain an oil-soluble polymer in the oil phase. As this oil-soluble polymer, known ones can be arbitrarily used and may be mixed. For example, rosin, polymerized rosin, hydrogenated rosin, rosin ester, rosin polyester polymer, rosin polymer such as hydrogenated rosin ester, rosin modified alkyd polymer, rosin modified maleic acid polymer, rosin modified phenolic polymer, etc. Rosin-modified polymers, maleic acid polymers, phenol polymers, petroleum polymers, cyclized rubber and other rubber derivative polymers, terpene polymers, alkyd polymers, polymerized castor oil, and the like. Examples of the rosin-modified phenol polymer include TAMANOL 353, TAMANOL 403, TAMANOL 361, TAMANOL 387, TAMANOL 340, TAMANOL 400, TAMANOL 396, TAMANOL 354, KG836, KG846, KG1834, and KG1801 manufactured by Arakawa Chemical Co., Ltd. When the weight average molecular weight of the oil-soluble polymer is low or when the addition amount is small, the effect on the fixing property is small, and when the weight average molecular weight is too high or the addition amount of the oil-soluble polymer is large, the ink is used. As a result, the plastic viscosity of the ink becomes high, causing problems of printability such as ink leakage from the rear end of the drum. The alkyd polymer is composed of fats and oils, polybasic acids and polyhydric alcohols, and when the fatty acids in the fats and oils are present as triglycerides, the mass% in the polymer is called the oil length, and the oil length is 60 or more with a large colorant dispersibility. Those having an iodine value of 90 or less, an iodine value of 80 or less, and a mass average molecular weight of 10,000 or less are preferably used in W / O emulsion inks for stencil printing. Such an alkyd polymer is rich in room temperature fluidity, and can be said to be an oil solvent component. Examples of oils and fats of such alkyd polymers include coconut oil, palm oil, olive oil, castor oil, rice bran oil, cottonseed oil and the like, iodine, 80 or less non-drying oil or semi-drying oil, and these fatty acids. Dry oils such as linseed oil and tung oil may be partially used when the iodine value of the alkyd polymer is 80 or less. Polybasic acids include phthalic anhydride, isophthalic acid, terephthalic acid, succinic acid, adipic acid, sebacic acid, tetrahydrophthalic acid and other saturated polybasic acids, and maleic acid, maleic anhydride, fumaric acid, itaconic acid, citraconic anhydride Examples thereof include unsaturated polybasic acids such as acids. In addition, polyhydric alcohols include ethylene glycol, zetylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, glycerin, trimethylolpropane, neopentyl glycol, diglycerin, triglycerin, pentaerythritol. Slits, dipentaery slits, mannits, sorbits and the like can be mentioned.

  It is also possible to contain a gelling agent in the oil phase, and this gelling agent has a role of gelling the polymer contained in the oil phase to improve the storage stability, fixability and fluidity of the ink. In addition, the gelling agent added to the ink of the present invention is preferably a compound that coordinates with a polymer in the oil phase. Examples of such compounds are organic acid salts containing organic metals such as Li, Na, K, Al, Ca, Co, Fe, Mn, Mg, Pb, Zn, and Zr, organic chelate compounds, and metal soap oligomers. Specifically, octylic acid metal salts such as aluminum octylate, naphthenic acid metal salts such as manganese naphthenate, stearates such as zinc stearate, organic chelate compounds such as aluminum diisopropoxide monoethyl acetoacetate, etc. Can be mentioned. One or two or more of these gelling agents may be added to the oil phase, and the amount added is 15% by mass or less, preferably 5% by mass or more and 10% by mass or less of the polymer in the oil phase. .

  It is also possible to contain an antioxidant in the oil phase, and this antioxidant is dibutylhydroxytoluene, propyl gallate, butylhydroxyanisole, etc., and by adding these, a binder polymer in the oil phase, etc. This prevents the ink from increasing in viscosity and the like. Moreover, the addition amount is 2 mass% or less of the oil phase in ink, Preferably it is 0.1 mass% or more and 1.0 mass% or less. In addition, you may use antioxidant alone or in mixture of 2 or more types.

  It is also possible to contain a colorant in the oil phase, and for this colorant, known pigments and disperse dyes of various colors can be used. Carbon blacks such as acetylene black, channel black, furnace black, Metal powders such as aluminum powder and bronze powder, petals, inorganic pigments such as yellow lead, ultramarine, chromium oxide and titanium oxide, azo pigments such as insoluble azo pigments, azo lake pigments and condensed azo pigments, metal-free phthalocyanine pigments and copper Phthalocyanine pigments such as phthalocyanine pigments, condensed polycyclic systems such as anthraquinone, quinacridone, isoindolinone, isoindoline, dioxazine, perylene, perylene, thioindigo, quinophthalone, metal complexes, etc. Pigments, organic pigments such as acid or basic dye lakes, diazo dyes, anthra Oil-soluble dyes such as non dyes, fluorescent pigments; and the like are. Further, as the fluorescent pigment, when the synthetic polymer is bulk polymerized or after polymerization, a fluorescent dye that develops various hues is dissolved or dyed, and the obtained colored bulk polymer is pulverized and refined. It is a so-called synthetic polymer solid solution type. As the synthetic polymer carrying the dye, melamine polymer, urea polymer, sulfonamide polymer, alkyd polymer, polyvinyl chloride polymer, etc. are carried on the dye. And fluorescent pigments. These dyes and pigments may be added alone or in combination of two or more. The average particle size of the insoluble colorant dispersed in the oil phase is 0.1 μm or more and 10 μm or less, preferably 0.1 μm or more and 1 μm or less. The amount used can be added according to the required amount, but is usually 2% by mass or more and 15% by mass or less in the oil phase. Two or more kinds of colorants may be added as colorants having similar properties. When carbon black is added to the oil phase, it is desirable to use acidic carbon black having a pH of less than 5. Typical carbon blacks are MA-100, MA-7, MA-77, MA-11, # 40, # 44 (Mitsubishi Chemical) Raven1100, Raven1080, Raven1255, Raven760, Raven410 (Colombian Carbon) Etc.

  It is also possible to contain a pigment dispersant in the oil phase. As the pigment dispersant, an agent that does not inhibit the formation of the emulsion can be used in an amount that does not inhibit the formation of the emulsion. Surfactants and water-soluble polymers can also be used. Specifically, alkylamine polymer compounds, aluminum chelate compounds, styrene-maleic anhydride copolymer polymers, polycarboxylic acid ester polymer compounds, aliphatic polycarboxylic acids, amines of polymer polyesters Salt, ester type anionic surfactant, long chain amine salt of high molecular weight polycarboxylic acid, salt of long chain polyaminoamide and polymer polyester, polyamide compound, phosphate ester surfactant, alkylsulfocarboxylate, α- Examples include olefin sulfonates, dioctyl sulfosuccinates, polyethyleneimine, alkylolamine salts, and polymers having insoluble colorant dispersion ability such as alkyd polymers. In addition, ionic surfactants, amphoteric surfactants and the like may be used as long as they do not impair the storage stability of the ink. These dispersants may be added alone or in admixture of two or more. The addition amount of the colorant dispersant other than the polymer and the polymer is 40% by mass or less, preferably 2% by mass or more and 35% by mass. % Or less. Alkyd polymers are particularly effective for the dispersion stability of insoluble colorants when high molecular weight polymers are added, but the addition of polymers when using alkyd polymers alone or in combination with other dispersants The amount is preferably 0.05 or more with respect to the insoluble colorant 1.

  It is also possible to include extender pigments in the oil phase. Examples of extender pigments include clay, silica, talc, clay, calcium carbonate, barium sulfate, titanium oxide, alumina white, diatomaceous earth, kaolin, mica, water. Inorganic fine particles such as aluminum oxide and organic fine particles such as polyacrylate, polyurethane, polyester, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, polysiloxane, phenolic polymer, epoxy polymer, etc. Fine particles made of coalesced are listed. Specific examples include Aerosil 200, Aerosil R972 (Nippon Aerosil Co., Ltd.), NEW D ORBEN (Shiraishi Kogyo Co., Ltd.), BEN-GEL, S-BEN, ORGANITE, etc. (Toyoshun Yoko Co., Ltd.), TIXOGEL series (VP, DS , GB, VG, EZ-100, etc.), OPTIGEL (Nissan Gardler Catalyst). These may be added to the oil phase, aqueous phase or both phases. The addition amount is preferably 0.1% by mass or more and 7.0% by mass or less, and more preferably 1% by mass or more and 5% by mass or less with respect to the ink.

  The emulsifier used as an oil phase component in the present invention is used for the purpose of forming a W / O type emulsion, and various emulsifiers are mixed within a range not impairing storage stability. In this case, any of an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant may be used. For example, sorbitan fatty acid esters such as sorbitan monooleate, sorbitan sesquioleate, sorbitan trioleate, sorbitan monostearate, polyoxyethylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, (Poly) glycerin fatty acid ester such as glyceryl monostearate, decaglyceryl trioleate, hexaglycerin polyricinoleate, polyoxyethylene glycerin fatty acid ester such as polyoxyethylene sorbit fatty acid ester, polyoxyethylene glycerin vegetable oil fatty acid ester, polyethylene glycol fatty acid Esters, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers Ether, polyoxyethylene alkylamine, fatty acid amides, polyoxyethylene polyoxypropylene alkyl ethers, polyoxyethylene castor oil, hardened castor oil and higher alcohols, and the like.

  In addition to the above, in the W / O type emulsion ink of the present invention, wax should be added to the oil phase in order to improve separation of the printing paper and the printing drum during printing or to prevent the printing paper from rolling up. Can do. Further, triethanolamine, sodium hydroxide or the like can be added to the aqueous phase to further increase the viscosity by adding a water-soluble polymer. Furthermore, a rust preventive agent or an antifoaming agent can be added to the water phase to prevent the printing press from being rusted by ink or causing ink to foam. These additives may be added as necessary to known products added to the stencil printing ink, and the amount added may be the same as that of conventional products.

The W / O emulsion ink of the present invention may be prepared by preparing an oil phase and an aqueous phase liquid in the same manner as in the production of conventional emulsion inks, and emulsifying both in a known emulsifier. That is, an oil phase in which each component such as oil or solvent component, emulsifier, oily polymer, and other various additives added as needed is well dispersed and dissolved is prepared, and water, water-soluble organic What is necessary is just to gradually add and emulsify a water phase in which a solvent, resin particles, a colorant and other various additives added as necessary are well dispersed and dissolved.
The W / O emulsion ink of the present invention is composed of, for example, 10 to 90% by mass of an oil phase and 90 to 10% by mass of an aqueous phase.
The W / O emulsion ink of the present invention is preferably used for stencil printing because it is excellent in fixability and excellent in emulsion stability.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited by these examples.

Preparation of Colorant Including Pigment in Polymer Fine Particles Having Carboxy Group The colorant was prepared according to Preparation Example 1 of JP-A No. 2001-139849. The preparation method is as follows.
(1) Preparation of polymer solution After thoroughly replacing nitrogen gas in a 1 L flask equipped with a mechanical stirrer, thermometer, nitrogen gas inlet tube, reflux tube and dropping funnel, 11.2 g of styrene, 2.8 g of acrylic acid, 12.0 g of lauryl methacrylate, 4.0 g of polyethylene glycol methacrylate, 4.0 g of styrene macromer (manufactured by Toa Gosei Co., Ltd., trade name: AS-6) and 0.4 g of mercaptoethanol were charged, and the temperature was raised to 65 ° C.
Next, 100.8 g of styrene, 25.2 g of acrylic acid, 108.0 g of lauryl methacrylate, 36.0 g of polyethylene glycol methacrylate, 60.0 g of hydroxyethyl methacrylate, 36.0 g of styrene macromer (manufactured by Toagosei Co., Ltd., trade name: AS-6), mercapto A mixed solution of 3.6 g of ethanol, 2.4 g of azobisdimethylvaleronitrile and 18 g of methyl ethyl ketone was dropped into the flask over 2.5 hours.
After completion of dropping, a mixed solution of 0.8 g of azobisdimethylvaleronitrile and 18 g of methyl ethyl ketone was dropped into the flask over 0.5 hours. After aging at 65 ° C. for 1 hour, 0.8 g of azobisdimethylvaleronitrile was added and further aging was performed for 1 hour.
After completion of the reaction, 364 g of methyl ethyl ketone was added to the flask to obtain 800 g of a polymer solution having a concentration of 50%.
A part of the polymer solution was dried and measured by gel permeation chromatography (standard: polystyrene, solvent: tetrahydrofuran), and the weight average molecular weight was 15000.
(2) Preparation of aqueous dispersion (colorant) of carbon black-containing polymer fine particles 28 g of polymer solution obtained in the above (1), carbon black (trade name: Monarch880) 26 g, 1 mol / L, produced by Cabot 13.6 g of an aqueous potassium hydroxide solution, 20 g of methyl ethyl ketone and 30 g of ion-exchanged water were sufficiently stirred, and then kneaded 20 times using a three roll mill [trade name: NR-84A, manufactured by Noritake Co., Ltd.]. After putting the obtained paste into 200 g of ion-exchanged water and stirring sufficiently, methyl ethyl ketone and water were distilled off using an evaporator to obtain 160 g of an aqueous dispersion of carbon black-containing polymer fine particles having a solid content of 20.0% by weight. It was. The average particle size (D50%) of the polymer fine particles measured by Microtrac UPA was 104 nm. Moreover, the amount of acid groups obtained in accordance with the acid group amount measurement method described in JP-A-2007-3454 was 0.33 [meq / g].

Preparation of W / O type emulsion ink The components used for the preparation of the oil phase are shown in Table 1 below, and the components used for the preparation of the aqueous phase are shown in Table 2 below.
In the formulations shown in Tables 3 and 4 below, each component of the oil phase is weighed and mixed to prepare an oil phase, and then each component of the aqueous phase is weighed, mixed, and emulsified into this oil phase to create an emulsion ink for stencil printing. did. The units of numerical values shown in Tables 3 and 4 are parts by mass.

Evaluation A method for evaluating the fixing property will be described below. Printing is sufficiently performed with a commercially available Ricoh Co., Ltd. stencil printing machine (Satelio A650), and the ink is dispersed in the printing machine. Thereafter, a solid image printing sample is formed and left for 24 hours. Thereafter, the solid portion of the print sample is rubbed with a clock meter (manufactured by Toyo Seiki Seisakusho), and the image density of the friction portion and the non-friction portion is measured using a reflection spectral densitometer (X-Rite / X-Rite 939), The difference between the image density of the frictional part and the image density of the non-frictional part is small, that is, it has excellent fixing properties, and is ranked in five levels. The most excellent fixability is 5. The printing test paper used is Type 6200 (manufactured by Ricoh Co., Ltd.). The evaluation environment was a temperature of 23 ± 0.5 ° C. and a humidity of 55 ± 5% RH. The results are shown in Table 5.

  The method for evaluating the emulsion stability will be described below. The viscometer (manufactured by Toki Sangyo Co., Ltd., RB-85L (measurement condition: 25 ° C.)) was used to measure the viscosities before and after accelerated storage for elapsed time. At this time, 2 g of ink was sealed in a glass bottle with an inner diameter of 20 mm and stored at a high temperature of 60 ° C./30 days. The results are shown in Table 5, and the viscosity change details are shown in Table 6.

From the results of Table 5, the aqueous phase contains an alkanediol having 4 to 6 carbon atoms, urethane resin particles, and a pigment having a carboxy group-containing pigment or a carboxy group-containing polymer fine particle. It was revealed that the W / O type emulsion ink is excellent in fixability and excellent in emulsion stability.
In particular, when Example 1 and Example 2 are compared, it is clear that Example 1 in which the alkanediol having 4 to 6 carbon atoms is 3-methyl-1,3-butanediol has further excellent fixability. became.
Moreover, when Example 1 and Example 5 were compared, it became clear that Example 1 using the self-emulsifying type urethane resin particles is more excellent in emulsion stability.
In addition, when Example 1 and Comparative Example 5 were compared, it was revealed that Example 1 containing a self-dispersing pigment as a pigment was more excellent in emulsion stability.
In Comparative Examples 1 and 2, since a water-soluble organic solvent having 3 carbon atoms was used in the aqueous phase, the fixability deteriorated.
Since Comparative Example 3 is an example using an acrylic resin emulsion, both fixability and emulsion stability were deteriorated.
Since Comparative Example 4 is an example using an acrylic-styrene resin emulsion, both the fixing property and the emulsion stability were deteriorated.
Since the comparative example 5 is an example using the pigment which does not have a carboxy group, the emulsion stability deteriorated.

JP 2003-268282 A JP 2002-167539 A JP 2007-84583 A JP 2007-70559 A JP-A-11-1648

Claims (5)

  A W / O emulsion ink having an oil phase and an aqueous phase, wherein the aqueous phase is an alkanediol having 4 to 6 carbon atoms, urethane resin particles, and a pigment having a carboxy group or a polymer fine particle having a carboxy group. A W / O emulsion ink comprising a colorant containing a pigment.   The W / O emulsion ink according to claim 1, wherein the alkanediol having 4 to 6 carbon atoms contains 3-methyl-1,3-butanediol.   The W / O emulsion ink according to claim 1, wherein the urethane resin particles are self-emulsifying urethane resin particles.   4. The self-dispersing pigment according to claim 1, wherein the pigment having a carboxy group is a self-dispersing pigment having a carboxy group bonded to the surface of the pigment directly or via another atomic group. W / O type emulsion ink. The W / O type emulsion ink according to any one of claims 1 to 4, which is used for stencil printing.