JP2000053903A - W/o type emulsion ink for mimeographic printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a W/O type emulsion ink for mimeographic printing having good filling property, free from bleeding to water, excellent in storage stability, free from color blur to color tone and excellent in fixing property. SOLUTION: This W/O type emulsion ink for mimeographic printing is composed of 10-90 wt.% oil phase and 90-10 wt.% water phase. The W/O type emulsion contains coloring agents (preferably having same color tone, <=2 difference of specific gravity of both phases, >=0.1 μm and <1 μm average particle diameter and 5-95 wt.% ratio of coloring agent in water phase to total coloring agent) which is insoluble in both phases of oil phase and water phase.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a stencil printing W / O.
More specifically, the present invention relates to a W / O emulsion ink for stencil printing which has good solid filling, little change in color tone, and is excellent in water resistance, storage stability and fixability.

[0002]

2. Description of the Related Art As is well known, a stencil printing method uses a stencil printing paper and moves ink from one side of the stencil to the other side of the stencil through a perforated portion of the stencil. Is to be printed. In recent years, a rotary stencil printing machine has been automated by a microcomputer or the like, and the operation has been simplified, and accordingly, the use of stencil printing has been increased. Also, there is a tendency to reduce the amount of ink attached to the paper in consideration of set-off and the ripple of the printed paper.

The W / W for stencil printing proposed so far has
O-type emulsion inks are obtained by adding an insoluble colorant to an oil phase (JP-A-8-218023) or by adding an insoluble colorant to an aqueous phase (JP-A-7-188598).
Publication No.) has been used. However, in these inks, the pigment does not adhere to the paper fiber to which the pigment-free phase has adhered, so that the insoluble colorant cannot uniformly adhere to the paper fiber, resulting in a locally uneven image. In addition to not being able to obtain images with good solid filling like electrophotography and offset printing, it is necessary to increase the amount of applied ink to increase image density. Defects such as a reduction in set-off and a phenomenon in which color flows due to rubbing due to excessive pigment on the paper surface have also been caused. In addition, when the printed image is locally viewed, the insoluble colorant cannot completely cover the paper fibers, so that the image density is limited.

To solve this problem, Japanese Patent Application Laid-Open No. HEI 5-117565 has been proposed.
In the publication, a W / O emulsion ink for stencil printing in which a water-soluble dye is added to an aqueous phase is proposed. However, the aqueous dye has poor weather resistance and water resistance, and has a problem that the color is discolored and the dye bleeds when the printed matter is wet with water. In addition, when color materials having different color tones are added to the oil phase and the aqueous phase, there are problems such as difficulty in matching colors due to the difference in coloring properties between the insoluble colorant and the dye. An excellent ink is desired.

Japanese Patent Laid-Open Publication No. Hei 8-30226 discloses that
A W / O emulsion ink for stencil printing in which an extender pigment is contained in an oil phase and a colorant is contained in an aqueous phase has been proposed. However, some extender pigments used in the oil phase can be used as white pigments, but when used as a colorant, they hinder the color development of the colorant that is added separately, and cause color particles. It is necessary to use one that does not inhibit the color development of The extender used here is distinguished from the colorant in particular because it is intended only to control the penetration of the ink into the paper. In addition, since the extender pigment needs to be colorless, even when a colorant component is contained in the aqueous phase, there is no ability to color the oil phase component, and the coloring of the paper fiber to which the oil phase component is attached is insufficient, and the solid color is not solid. The filling was also insufficient.

Further, Japanese Patent Application Laid-Open No. 9-255908 discloses a stencil printing W / O emulsion ink containing a pearlescent pigment in an oil phase and / or an aqueous phase.
However, the pearlescent pigment used here is a pigment intended to give a luster, and it is necessary to add a pigment that does not inhibit the coloring of the coloring agent, and is distinguished from the coloring agent. In the case of a colorant, it is possible to create an intermediate color by using a different colorant, but in the case of a pearlescent pigment, it is possible to control the intensity of gloss but not to obtain an intermediate color. Be distinguished. And when the pearlescent pigment was added to the opposite phase to the colorant, not only the merit of adding the colorant in both phases was not obtained, but also the solid filling was insufficient because the colorant was only in one phase. .

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned disadvantages of the prior art and to provide a transfer stencil printing machine with good solid filling, no bleeding, excellent storage stability, oil phase, water phase Even if a color material is added to both phases, there is no color shift with respect to the target color tone, and the stencil printing W is excellent in fixability.
/ O emulsion ink is provided.

[0008]

According to the present invention, an oil phase 1 is provided.
A W / O emulsion ink composed of 0 to 90% by weight and an aqueous phase of 90 to 10% by weight, characterized in that both the oil phase and the aqueous phase contain an insoluble colorant. An O-type emulsion ink is provided.
Further, according to the present invention, the color tone of the insoluble colorant present in the oil phase and the color tone of the insoluble colorant present in the aqueous phase are the same. C. I. Pigment colors are the same,
Further, Co1orIndex No. C. I.
Pigment Color No. Wherein the W / O emulsion ink for stencil printing is provided. Further, according to the present invention, any one of the W / O emulsions for stencil printing described above, wherein the specific gravity difference between the insoluble colorant present in the oil phase and the insoluble colorant present in the aqueous phase is 2 or less. An ink is provided. Furthermore,
According to the present invention, there is provided the W / O emulsion ink for stencil printing, wherein the insoluble colorant dispersed in the oil phase and the aqueous phase has an average particle size of 0.1 μm or more and less than 1 μm. . Furthermore, according to the present invention, the ratio a (% by weight) of the insoluble colorant present in the aqueous phase to the total insoluble colorant in the ink is in the range of 5 to 95% by weight, preferably the ratio a (% By weight) further satisfies the following expression (1) with the ratio W (% by weight) of the aqueous phase in the emulsion ink: W−45 ≦ a ≦ W + 45 (1) In particular, the ratio a (weight) %) Further satisfies the ratio W (% by weight) of the aqueous phase in the emulsion ink and the following formula (2): W-20 emulsion emulsion ink for stencil printing, W-20 ≦ a ≦ W + 20 (2) is provided.

That is, the present inventors have conducted various studies in order to achieve the above object, and have found that both the oil phase and the aqueous phase contain an insoluble colorant, especially the color tone of the insoluble colorant present in both phases. By being the same, it is excellent in solid filling,
At this time, Color Index No. C.
I. Pigment color type, and No. It was found that by adding the same color to both the oil phase and the aqueous phase, the change in the target color tone could be reduced even when the color material was added to both the oil phase and the aqueous phase, and the specific gravity difference between the insoluble colorants present in both phases. Is 2 or less, it is found that the storage stability is excellent, and further, the average particle size of the insoluble colorant dispersed in both phases is 0.1 μm or more and less than 1 μm. Furthermore, by setting the ratio a (% by weight) of the insoluble colorant present in the aqueous phase to the total insoluble colorant in the ink to 5 to 95% by weight, the ratio W (%) of the aqueous phase in the ink at this time is obtained. % By weight) and preferably in the range of 5 to 95% by weight of the insoluble colorant present in the aqueous phase with respect to all the insoluble colorants in the ink. Of aqueous phase W (% by weight) It has been found that the effect of solid filling is more excellent when the content is in the range of -20% by weight or more and + 20% by weight or less, and the present invention has been completed.

In the present invention, the reason why such an effect is exhibited is not clear, but is considered as follows. It is thought that when the ink penetrates the paper, the oil phase and the water phase separate and permeate.However, when the insoluble colorant is present only in the oil phase, the paper fibers with the water phase repel the oil phase. As a result, the insoluble colorant does not exist, and when viewed locally, a white portion exists in the form of a paper fiber, and a uniform color cannot be obtained. The same applies to the case where a colorant is added to the aqueous phase, and the paper fiber to which the oil phase has adhered may have a place where the aqueous phase does not adhere and the colorant does not exist. On the other hand, when a coloring agent is added to both the oil phase and the aqueous phase, both the paper fibers to which the oil phase is attached and the paper fibers to which the aqueous phase is attached are colored. It is considered that the density of solid filling is increased because the fibers are uniformly colored. In addition, bleeding can be suppressed by using an insoluble colorant.

When the difference in specific gravity between the insoluble colorant in the oil phase and the insoluble colorant in the aqueous phase is larger than 2, the difference in specific gravity in the aqueous phase dispersed in the oil phase becomes large, and the water phase may settle or float in the oil phase. However, it is considered that the movement of the aqueous phase can be suppressed by setting the specific gravity difference to 2 or less. Furthermore,
Regarding the average particle size of the insoluble colorant, it is considered that by reducing the average particle size of the insoluble colorant, it is possible to penetrate the paper and improve the fixability, but it is possible to improve the fixability in either the oil phase or the aqueous phase. If the dispersed particle size of the pigment is large, it is considered that the pigment remains on the paper in a filtered form, and the fixability is lowered. On the other hand, if the average particle size of the insoluble colorant is too small, the insoluble colorant penetrates deep into the paper, reducing the efficiency of color development and causing problems such as strikethrough. In addition, if the dispersion of the pigment in the oil phase is insufficient, the pigment may aggregate and the storage stability may decrease.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The aqueous phase of the emulsion comprises water, an insoluble colorant,
Insoluble colorant dispersant, electrolyte, fungicide, water evaporation inhibitor,
Water-soluble polymer, oil-in-water type resin emulsion, antifreezing agent, pH adjuster, etc., and the oil phase is composed of an oil component, an insoluble colorant, an insoluble colorant dispersant, an extender pigment, a resin, an emulsifier, and an anti-gelling agent. , An emulsifier, an antioxidant and the like. Known components that do not inhibit the formation of the emulsion are used as these components.

The insoluble colorant used in the present invention includes carbon black, titanium oxide, azo and diazo pigments,
Examples include phthalocyanine pigments, nitroso pigments, nitro pigments, vat dye pigments, mordant dye pigments, basic dye pigments, acid dye pigments, and natural dye pigments. These insoluble colorants may be added alone or as a mixture of two or more.

For example, with respect to carbon black, an acidic carbon black having a pH of less than 5 when added to an oil phase, a pH of 5 or more, preferably a pH of 6 to 10, more preferably a pH of 7 to 9 when added to an aqueous phase. It is desirable to use alkaline carbon black. Representative carbon blacks are MA-100, MA-7,
MA-77, MA-11, # 40, # 44 (Mitsubishi Kasei) Raven1080, Raven1255, Rav
en760 and Raven410 (manufactured by Colombian Carbon).

Titanium oxide can be divided into coloring titanium oxide having low visible light transmittance and ultrafine titanium oxide having high transmittance. Titanium oxide used as an insoluble coloring agent is composed of primary particles of titanium oxide. Average particle size is 0.1μm
Not less than 1.0 μm and not less than 0.2 μm.
It is desirable to use one having a size of 5 μm or less. Typical titanium oxides for coloring agents include TIPAQUE (Taipaque) R series, CR series, and TY series (Ishihara Sangyo Co., Ltd.).

In the present invention, when an insoluble colorant of the same color is added to the oil phase and the aqueous phase, the same color tone, particularly the colorant of the insoluble colorant, is used to reduce the deviation of the color material from the target color tone. Color is Co1or Index No. C. I. Pigment is preferably the same, and C.I. I. Pigment No. Are preferably used.

Further, an insoluble colorant dispersed in the oil phase,
The difference in specific gravity from the insoluble colorant dispersed in the aqueous phase is preferably 2 or less, more preferably 1 or less, in order to maintain the stability of the emulsion.

Further, the average particle size of the insoluble colorant dispersed in the oil phase and the aqueous phase is preferably from 0.1 μm to 10 μm, more preferably from 0.1 μm to less than 1 μm, further preferably from 0.1 to 0 μm. 0.5 μm.

In the present invention, the ratio a (% by weight) of the insoluble colorant present in the aqueous phase to the total insoluble colorant in the ink is in the range of 5 to 95% by weight in view of the solid filling effect. Is preferred. In terms of the solid filling effect, it is more preferable that the relationship between the a (weight%) and the ratio W (weight%) of the aqueous phase in the ink satisfies the following equation (1). It is more preferable to satisfy. W−45 ≦ a ≦ W + 45 (1) W−20 ≦ a ≦ W + 20 (2)

In the present invention, the total amount of the insoluble colorant can be selected according to the required amount, but it is 2 to 30% by weight, preferably 3 to 15% by weight of the total amount of the ink. In addition, although it is dispersed or added to the oil phase and the aqueous phase, two or more insoluble colorants may be added to the same phase as long as the stability of the ink is not impaired.

In the present invention, a gloss pigment may be added for the purpose of giving gloss in addition to the insoluble colorant. Examples of pearlescent pigments include metal oxide-coated mica, natural pearl essence, basic carbon salts, lead arsenate, and bismuth chloride. In particular, metal oxide-coated mica such as titanium oxide-coated mica in which the surface of flaky particles of muscovite is covered with titanium oxide with a uniform thickness, and iron oxide-coated mica in which iron oxide is coated is desirable. The luster pigment is added to the oil or water phase,
Preferably, it is better to add to the oil phase. The gloss pigment has an average particle size of 1 to 30 μm, preferably 2 to 15 μm. The addition amount is 1 to the total amount of the emulsion ink.
It is in the range of 20% by weight, preferably 2-15% by weight.
The hiding power of the gloss pigment is 1000 cm ² / g or less, preferably 500 cm ² / g or less.

As the colorant dispersant for the colorant dispersed in the oil phase and the aqueous phase, those which do not inhibit the formation of an emulsion can be used, and the following nonionic surfactants for emulsifiers, resins and water-soluble polymers are also used. can do. Examples of the dispersant include alkylamine-based polymer compounds, aluminum chelate-based compounds, styrene-maleic anhydride-based copolymerized polymer compounds, polycarboxylic acid ester-type polymer compounds, aliphatic polycarboxylic acids, and polymer polyesters. Amine salts, ester-type anionic surfactants, long-chain amine salts of high-molecular-weight polycarboxylic acids, salts of long-chain polyaminoamides and high-molecular-weight polyesters, polyamide-based compounds, phosphate-based surfactants, alkyl sulfocarboxylates, α
-Olefin sulfonates, dioctyl sulfosuccinates, polyethylene imine, alkylolamine salts,
And a resin having an insoluble colorant dispersing ability, such as an alkyd resin. In addition to these, ionic surfactants and amphoteric surfactants may be used as long as the stability of the ink is not impaired.

These dispersants may be added alone or in admixture of two or more. The amount of the colorant dispersant other than the resin is 40% by weight or less, preferably 2 to 35% by weight of the colorant.
% By weight. The alkyd resin has a particularly effective effect on the dispersion stability of the insoluble colorant when a high molecular weight resin is added, but when the alkyd resin is used alone or in combination with other dispersants, the amount of the resin added is insoluble. The amount is preferably 0.05 part by weight or more based on 1 part by weight of the agent.

The oil used in the oil phase of the W / O emulsion ink for stencil printing of the present invention is petroleum solvent, liquid paraffin, spindle oil, machine oil, lubricating oil, mineral oil; linseed oil, tall oil, Vegetable oils such as corn oil, olive oil, rapeseed oil, castor oil, dehydrated castor oil, soybean oil, and coconut oil are used. Further, in the present invention, synthetic oils can be used together as long as they do not impair the safety, storage stability, solubility of the resin and the like.

As the non-volatile oil, Nippon Oil Corporation's Meseki Super Oil Series (B, C, D, E, etc.) and Mobil Oil's Gargoyle Arctic Series (1010, 1022, 1032, 1046, 106)
8, 1100), Gargoyle Arctic Oil Series (Light, C Heavy, 155, 300ID, etc.) and Mobil Vacuolin Extra Heavy, Mobil D
TE Extra Heavy, Sun Oil's sampler oil series (110, 115, 120, 130, 150, 21
00, 2280, etc.), Sansen Oil Series (31
0, 415, 430, 380, 3125, 4130, 4
240); S. O aroma 790, Nitoprene 720
L, Circolite R.L. P. O, Idemitsu Oil's Diana Process Oil Series (PX-32, PX-90, PW-
32, PW-90, PW-380, PS-32, PS-
90, PS-430, NS-100, NS-24, NM
-26, NM-280, NP-24, AC-12, AC
-460, AH-16, AH-58).

Examples of petroleum solvents include Exxon Isopar series (C, E, G, H, L, M, etc.) and Exol (D-30, D-40, D-80, D-110, D-110).
-130 etc.) and AF Solvent Series (Nos. 4, 5, 6, and 7) of Nippon Oil Corporation. These oils may be used alone or in combination of two or more. The non-volatile component having a viscosity of 10 cSt (at 40 ° C.) or more is 30% by weight or more, preferably 50% by weight or more of the oil phase component.

The emulsifier used in the oil phase in the present invention is preferably a nonionic surfactant, such as higher sorbitan fatty acid ester, higher polyoxyethylene sorbitan fatty acid ester, fatty acid monoglyceride, polyglycerin fatty acid ester, or fatty acid. Diglycerides and ethylene oxide adducts such as higher alcohols, alkylphenols and fatty acids;
An emulsion having high stability is prepared by combining two or more kinds of substances having different LBs. The HLB of the surfactant in the ink is preferably 3.0 to 5.5, and the amount added is usually 0.5 to 15% by weight, preferably 2 to 5.5% by weight of the ink weight.

The resin added to the oil phase in the present invention includes:
The following are mentioned. Rosin; rosin resin such as polymerized rosin, hydrogenated rosin, rosin ester, hydrogenated rosin ester; rosin modified alkyd resin, rosin modified maleic resin; rosin modified resin such as rosin modified phenol resin; maleic acid resin; One or more of petroleum resins; rubber derivative resins such as cyclized rubbers; terpene resins; alkyd resins; polymerized castor oil; Typical resins are Tamanol 353, Tamanol 403 and Tamanol 3 manufactured by Arakawa Chemical Co., Ltd.
61, Tamanor 387, Tamanor 340, Tamanor 40
0, Tamanor 396, Tamanor 354, KG836, K
Rosin-modified phenolic resins such as G846, KG1834 and KG1801.

The molecular weight of the resin is preferably from 30,000 to 150,000, more preferably from 550,000 to 10000, from the viewpoint of fixability and printability.
These resins have a solubility of at least 1.4 g / g in Nisseki No. 0 Solvent H (manufactured by Nippon Oil Co., Ltd.). Are compatible). The amount of the resin used in the oil phase is 2 to 50% by weight of the oil phase, more preferably 5 to 2%, in view of the cost and printability of the ink.
0% by weight. If the molecular weight of the resin is low or the amount added is small, the effect on the fixing property is small.If the molecular weight is too high or the amount of the resin added is large, the viscosity of the ink becomes high, and the rear end of the drum The problem of printability such as leakage of ink from the printer occurs.

Among the above resins, alkyd resins are preferred from the viewpoint of stabilizing the dispersion of the colorant. The alkyd resin used in the present invention is composed of fats and oils, polybasic acids and polyhydric alcohols. Examples of fats and oils include non-drying oils or semi-drying oils having an iodine value of 80 or less such as coconut oil, palm oil, olive oil, castor oil, rice bran oil, cottonseed oil and the like, and soybean oil, linseed oil, tung oil and the like. A drying oil may be partially used in the range where the iodine value of the alkyd resin is 80 or less. As polybasic acids, phthalic anhydride, isophthalic acid, terephthalic acid, succinic acid, adipic acid, sebacic acid, saturated polybasic acids such as tetrahydrophthalic acid, and maleic acid,
Unsaturated polybasic acids such as maleic anhydride, fumaric acid, itaconic acid and citraconic anhydride can be used. Polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, trimethylene glycol,
Tetramethylene glycol, glycerin, trimethylolpropane, neopentyl glycol, diglycerin,
Triglycerin, pentaerythrit, dipentaerythlit, mannitol, sorbit and the like can be used. The oil length of the alkyd resin is indicated by weight% in the resin when the fatty acid in the fat is present as triglyceride. The alkyd resin has an oil length of 60 to 90 and an iodine value of 80 due to problems such as dispersion stability and clogging of a plate cylinder screen due to film formation.
The following is preferred. The alkyd resin preferably has a molecular weight of less than 30,000, more preferably 10,000 or less.

The gelling agent used in the oil phase in the present invention has a role of gelling the resin contained in the oil phase to improve the storage stability, fixability and fluidity of the ink. As the gelling agent to be added to the ink of the present invention, a compound that coordinates with the resin in the oil phase is preferable. Examples of such compounds include Li, Na, K, A1, Ca, Co, Fe, Mn,
Organic acid salts containing metals such as Mg, Pb, Zn, and Zr, organic chelate compounds, metal soap oligomers, and the like; specifically, metal octylates such as aluminum octylate; and metal naphthenates such as manganese naphthenate And organic chelate compounds such as aluminum diisopropoxide monoethyl acetoacetate. One or two of these gelling agents may be used.
More than one kind may be added to the oil phase, and the amount added is 15% by weight or less, preferably 5 to 10% by weight of the resin in the oil phase.

In the present invention, the antioxidant added to the oil phase is
Dibutylhydroxytoluene, propyl gallate, butylhydroxyanisole and the like, and the addition thereof prevents oxidation of the binder resin and the like in the oil phase, thereby preventing the viscosity of the ink from increasing. Also, the amount of addition is 2% by weight or less of the oil in the ink, preferably 0.1 to 10%.
1.0% by weight. The antioxidants may be used alone or in combination of two or more.

In the present invention, extenders may be added to the oil phase to prevent bleeding in the ink or to adjust the viscosity. White clay as the extender pigment added to the ink,
Inorganic fine particles such as silica, talc, clay, calcium carbonate, barium sulfate, titanium oxide, alumina white, diatomaceous earth, kaolin, mica, aluminum hydroxide, and polyacrylates, polyurethane, polyester, polyethylene, polypropylene, polyvinyl chloride,
Polyvinylidene chloride, polystyrene, polysiloxane,
Organic fine particles such as a phenolic resin and an epoxy resin, and fine particles composed of a copolymer thereof, which do not inhibit the color tone of the colorant, may be used.

Titanium oxide can be divided into titanium oxide for colorants having low transmittance of visible light and ultrafine titanium oxide having high transmittance. Titanium oxide used as an extender is an average particle of primary particles of titanium oxide. It is desirable to use highly permeable ultrafine titanium oxide having a diameter of less than 0.1 μm, preferably 0.05 μm or less. Specific examples of extenders include Aerosil 200, Aerosil R972 (Nippon Aerosil), NEW D ORBEN (Jishiishi Kogyo), BEN-GEL, S-BEN, ORGANIT.
E (Toyokawa Yokosha), TIXOGEL series (V
P, DS, GB, VG, EZ-100, etc.), OPTI
GEL (Nissan Gardler), TIPAQUE (Taipaek) TTO-51, Series TTO-55 series,
TTO-F series (TTO-51 (A), TTO-5
5 (A), TTO-F-1, etc.) (Ishihara Sangyo).

These may be added not only to the oil phase but also to the aqueous phase or both phases. The extender may be used alone or as a mixture of two or more kinds.
To 50% by weight, more preferably 0.1 to 10% by weight.
% By weight.

In the present invention, a water-soluble polymer or an O / W resin emulsion may be added to the aqueous phase of the emulsion ink for moisturizing, thickening and dispersing and fixing the insoluble colorant and extender pigment. Specific examples of the water-soluble polymer include the following natural or synthetic polymers. For example, starch, mannan, sodium alginate, galactan, tragacanth gum, gum arabic, burlan, dextran, xanthan gum, glue, gelatin, collagen,
Natural polymers such as casein; carboxymethylcellulose, hydroxymethylcellulose, methylcellulose,
Semi-synthetic polymers such as hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, hydroxymethyl starch, carboxymethyl starch, dialdehyde starch; neutralized products such as acrylic resin and sodium polyacrylate; polyvinyl imide; polyvinyl alcohol; Pyrrolidone, polyethylene imine, polyacrylamide, poly N
Poly (N-alkyl-substituted acrylamides such as acryloylpyrrolidine and poly (N-isopropylacrylamide), polyethylene oxide, polyvinyl methyl ter, styrene-maleic anhydride copolymer, styrene-acrylic acid copolymer and these partially with an alkyl group. As for a hydrophobic polymer, an acrylamide polymer and an acrylic polymer, a copolymer type polymer in which a substituent is partially hydrophobized by an alkyl group may be used. Alternatively, a block copolymer of polyethylene and polypropylene or polybutylene can be used. As these polymers, a water-soluble synthetic polymer having a surface activity such that the surface tension of a 1 g / dL aqueous solution is 65 mN / m or less is used. These water-soluble polymers may be used alone or as a mixture of two or more, and 25% by weight of water contained in the ink.
Hereinafter, 0.5 to 15% by weight is preferably added.

The O / W type resin emulsion may be a synthetic polymer or a natural polymer. Polymers include vinyl acetate, acrylate, methacrylate, vinyl chloride, ethylene-vinyl acetate copolymer, vinyl acetate-acrylate copolymer, styrene-acrylate copolymer, vinylidene chloride-acrylic acid Ester copolymer, vinyl chloride-vinyl acetate copolymer,
Urethane and the like. Examples of natural products include polymers that can be added to the oil phase. These may be used in combination of two or more as long as the stability of the water-in-oil emulsion ink is not impaired, and the dispersing method may be the addition of a dispersant, a protective colloid, and a surfactant. A product synthesized by soap-free emulsion polymerization may be used. The minimum film forming temperature of these O / W type resin emulsions is desirably 40 ° C. or lower.

The antiseptic / fungicide added to the aqueous phase in the present invention is added in order to prevent the propagation of pongus or fungi in the emulsion. When the emulsion is stored for a long period of time, the antiseptic / fungicide is usually added. Added. Examples of such preservatives and fungicides include salicylic acid, phenols, aromatic hydroxy compounds such as methyl p-oxybenzoate and ethyl p-oxybenzoate and chlorine compounds thereof, and sorbic acid and dehydroacetic acid. These may be used alone or in combination of two or more. The amount of addition is 3% by weight or less of water contained in the ink, preferably 0.1 to 1.2% by weight.

In the present invention, an anti-evaporation agent and an anti-freezing agent for water added to the aqueous phase can be used in combination, and compounds added for these purposes include glycols such as ethylene glycol, diethylene glycol and propylene glycol; methanol, ethanol and the like. Lower saturated monohydric alcohols such as isopropanol, butanol and isobutanol; polyhydric alcohols such as glycerin and sorbitol; One or more of these compounds may be added, and the amount added is 15% by weight or less, preferably 4 to 12% by weight of the weight of water in the ink.

The pH adjuster added to the aqueous phase is triethanolamine, sodium acetate, triamylamine, etc. If necessary, these pH adjusters may be added to the aqueous phase to adjust the pH of the aqueous phase.
H can be maintained at 6-8. The pH adjuster also acts as a thickening accelerator for the water-soluble polymer, and when the pH of the aqueous phase is out of the above range, the effect is increased when the water-soluble polymer for a thickener is added. There are problems such as being damaged.

The electrolyte added to the aqueous phase in the present invention is added to enhance the stability of the emulsion.
Therefore, it is desirable to use when the material affected by the electrolyte is not present in the aqueous phase. The electrolyte is preferably an electrolyte containing an anion such as a citrate ion, a tartrate ion, a sulfate ion, or an acetate ion, or an alkali metal ion or an alkaline earth metal ion. Therefore, as the electrolyte added here, magnesium sulfate, sodium sulfate, sodium citrate, sodium hydrogen phosphate, sodium borate, sodium acetate, and the like are preferable, and the amount of addition is 0.1 to 2% by weight of the aqueous phase. Preferably it is 0.5 to 1.5% by weight.

In addition to the above, the W / O emulsion ink for stencil printing of the present invention has an oil phase for improving the separation between the printing paper and the printing drum during printing or for preventing the printing paper from rolling up. Wax can be added. Further, to the aqueous phase, triethanolamine, sodium hydroxide, or the like can be added to further increase the viscosity by adding a water-soluble polymer. Further, by adding a rust inhibitor or a defoaming agent to the aqueous phase, it is possible to prevent the printing press from being rusted by the ink during printing, or from foaming the ink. Known additives added to the stencil printing ink may be added to these stencil printing inks as needed, and the amount of these additives may be about the same as in the case of conventional products.

The W / O emulsion ink of the present invention comprises:
In the same manner as in the production of a conventional emulsion ink, it can be produced by preparing an oil phase and an aqueous phase liquid and emulsifying both in a known emulsifying machine. That is, an oil in which additives such as a coloring agent, a coloring dispersing agent, an emulsifier and a resin added as needed are well dispersed is adjusted at room temperature, and a coloring agent, a coloring dispersing agent, an antiseptic / fungicide and An aqueous solution to which a water-soluble polymer or the like is added as needed may be gradually added to emulsify. The viscosity of the ink can also be adjusted by the stirring conditions, and is not particularly limited as long as it is suitable for the system. However, the viscosity at a shear rate of 20 s ^-1 is preferably 5 to 35 Pa · s. When an insoluble colorant, resin, extender or the like is added to the oil phase, the viscosity of the oil phase at a shear rate of 20 s ^-1 is 0.1.
It is desirably from 0.5 to 20 Pa · s, preferably from 0.1 to 3 Pa · s.

[0044]

Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. The parts described below are parts by weight.

Examples 1 to 21 and Comparative Examples 1 to 5 The W / O emulsion inks of Examples 1 to 21 and Comparative Examples 1 to 5 were prepared according to the formulations shown in Tables 1 to 5. The adjustment of the ink, the components used, and the evaluation of the ink will be described in detail below. In Examples 15 to 21 and Comparative Example 5, Co1or of the insoluble colorant pigment used was used.
Index No. Co1or In with target color
The dex No. is shown in Table 6, and the deviation from the target color tone was also evaluated. The results are shown in Tables 7 to 10. Table 7
Among 10, y, s, W, a and b mean the following. y: Content of insoluble colorant in oil phase with respect to ink (% by weight) s: Content of insoluble colorant in aqueous phase with respect to ink (% by weight) W: Ratio of aqueous phase (% by weight) a: Total insolubility Ratio of the colorant contained in the aqueous phase (% by weight) a = s / (y + s) b: Difference between the ratio of the insoluble colorant present in the aqueous phase and the ratio of the aqueous phase (% by weight) b = a-W

<Preparation of W / O Emulsion Ink> A W / O emulsion ink containing an insoluble colorant in the oil phase, an insoluble colorant is prepared by kneading a colorant, an oil and an insoluble colorant dispersant with three rolls. The dispersion is adjusted, and a surfactant for emulsification, a varnish such as oil and resin are added to this insoluble colorant dispersion (hereinafter, insoluble colorant dispersion) to form an oil phase, and water, an antifreeze, and an antibacterial agent are added thereto. A W / O emulsion ink for stencil printing was obtained by adding and emulsifying an aqueous phase comprising an agent, an electrolyte or a water-soluble resin. If necessary, another component such as an extender may be added.

A W / O emulsion ink containing an insoluble colorant in the aqueous phase. An insoluble colorant, a water-soluble polymer, and / or a colorant dispersant, and water are added, and the mixture is stirred for 24 hours using a ball mill. A phase dispersion was prepared, and an antifreezing agent and an antibacterial agent were added thereto to obtain an aqueous phase. Oil that has been created in advance,
The aqueous phase was stirred, mixed and emulsified with an oil phase composed of an emulsifying surfactant, varnish and the like to obtain a stencil printing W / O emulsion ink. If necessary, another component such as an extender may be added.

A W / O emulsion ink containing an insoluble colorant in both an oil phase and an aqueous phase. Dispersions of the insoluble colorants in the oil phase and the aqueous phase are prepared.
The aqueous phase was stirred and mixed with the oil phase and emulsified to obtain a W / O emulsion ink for stencil printing. If necessary, another component such as an extender may be added.

<Description of each component> Alkyd resin: 76 parts of coconut oil, pentaerythritol 7
And 17 parts of isophthalic acid. AF Solvent 5: Viscosity 4.2cSt@40° C., Aniline point 88.2 ° C., aromatic component 0.2% Gargoyle Arctic Oil C Heavy: Mobile Oil, Sansen Oil 410: Sun Oil Rosin polyester (Pencel (PE) -PL, Mw = 1
Man Arakawa Chemical Co., Ltd., rosin-modified phenolic resin: Tamanol 361, KG84
6 Arakawa Chemical Co., Ltd., carbon black MA-77: pH = 3.0, Mitsubishi Kasei Co., Ltd., Raven 760: pH = 7.4, manufactured by Colombian Carbon Co., Ltd., Aerosil R972: manufactured by Nippon Aerosil Co., Ltd., sodium polyacrylate: Carbopol 940 BF
Goodrich, polyvinylpyrrolidone: BASF K30, titanium oxide: Taipe CR-50, Taipe CR-
90: Ishihara Sangyo Co., Ltd.

Particle Size of Insoluble Colorant The particle size of the insoluble colorant was measured using a particle size distribution analyzer LA-700 manufactured by Horiba Seisakusho Co., Ltd. In the case of the aqueous phase, it was diluted with water and measured. The specific gravity of the pigment is JIS K 5101-19.
78.

<Evaluation of Emulsion Ink> Printing Density A sufficient printing was performed using a stencil printing machine (VT3920) manufactured by Ricoh Co., Ltd., and the ink was spread in the printing machine. At this time, the print density of the printed matter was measured by a reflection optical densitometer (RD914 manufactured by Macbeth). Solid Filling The printed sample was observed with an optical head microscope, and the evaluation was given on a five-point scale, with 1 having no uncolored portion in the fiber and 5 having no uncolored portion. Fixability The change in print density when the printed portion was rubbed with an eraser was evaluated. Bleeding on water The bleeding on water was evaluated by evaluating the bleeding of the image when water was attached to the print sample. Storage Stability of Ink The storage stability of the ink was evaluated at 1 to 5 when the ink was stored at room temperature for one year and the separation was small, and 5 when the storage was large. Color Tone Change The color shift from the target insoluble colorant was evaluated, and one having no color shift from the target color tone was rated as 1, and the one with many color shifts was rated as five.

[0052]

[Table 1]

[0053]

[Table 2]

[0054]

[Table 3]

[0055]

[Table 4]

[0056]

[Table 5]

[0057]

[Table 6]

[0058]

[Table 7]

[0059]

[Table 8]

[0060]

[Table 9]

[0061]

[Table 10]

From the results of Tables 1 to 10, the following is clear. That is, from Example 1 and Comparative Examples 1-2, and 4, it can be seen that the solid filling effect is improved by adding an insoluble colorant to both the oil phase and the aqueous phase of claim 1. Further, from Example 1 and Examples 16 to 20, the color tone of the insoluble colorant present in the oil phase and the color tone of the insoluble colorant present in the aqueous phase according to claim 2 were made the same to further produce Example 1.
5. The insoluble colorant present in the oil phase and the Co1or of the insoluble colorant present in the aqueous phase according to claim 3 and from Examples 16 and 17.
Index No. C. I. Pigment
By using the same kind of color, particularly in Example 16,
17 and Examples 18, 19, and 20 indicate that the insoluble colorant present in the oil phase and the insoluble colorant present in the aqueous phase according to claim 1 of Co4 Index No. C. I. Pi
gment Coor No. It can be understood that the effect of reducing the change in color tone can be obtained by making the same. Further, from Examples 11 and 21, the storage stability is excellent by setting the difference between the color tone of the insoluble colorant present in the oil phase and the specific gravity of the insoluble colorant present in the aqueous phase to 2 or less according to claim 5. It can be seen that the effect is obtained. Furthermore, the average particle size of the insoluble colorant dispersed in the oil phase and the aqueous phase according to Example 9 and Examples 12, 13, and 14 is 0.1 μm.
It can be seen that an effect of excellent fixability can be obtained when the thickness is less than 1 μm. Further, from Examples 2 and 3 and Examples 4 and 5, the ratio of the insoluble colorant present in the aqueous phase to the total insoluble colorant in the ink according to claim 7 was 5 to 95.
By setting the weight% range, the ratio of the insoluble colorant present in the aqueous phase to the total amount of the insoluble colorant in the ink according to Examples 8 and 5 and from Examples 7 and 8 is 5-9.
In the range of 5% by weight and the proportion of the aqueous phase in the ink -45.
In particular, from Examples 7 and 8 and Examples 9 and 10, the ratio of the insoluble colorant present in the aqueous phase to the total insoluble colorant in the ink of claim 9 is 5% by weight or more and + 45% by weight or less. It can be seen that the solid filling effect is more excellent when the content is in the range of about 95% by weight and the proportion of the aqueous phase in the ink is -20% by weight or more and + 20% by weight or less.

[0063]

According to the present invention, the W / O emulsion ink for stencil printing which contains an insoluble colorant in both the oil phase and the aqueous phase has the effect of solid filling and no bleeding in water. In addition, the color tone of the insoluble colorants of the two phases of the present invention is the same, and furthermore, ColorIndex N
o. C. I. Pigment color, especially C.I. I. Pigment No. The W / O emulsion ink for stencil printing has the same effect as described above. In addition, the W / O emulsion ink for stencil printing of the present invention in which the difference in specific gravity between the insoluble colorants of the two phases is 2 or less has an effect of being excellent in storage stability. Further, the W / O emulsion ink for stencil printing of the present invention in which the insoluble colorant has an average particle diameter of 0.1 μm or more and less than 1 μm has an effect of being excellent in fixability. Furthermore, the W / O emulsion ink for stencil printing, in which the ratio of the insoluble colorant present in the aqueous phase to the total insoluble colorant in the ink of the present invention is in the above-mentioned specific range, has the effect of further improving the solid filling effect. .

Claims (9)

[Claims] 1. An oily phase of 10 to 90% by weight and an aqueous phase of 90 to 1%.
What is claimed is: 1. A W / O emulsion ink for stencil printing, comprising an insoluble colorant in both an oil phase and an aqueous phase, comprising 0% by weight. 2. The W / O emulsion ink for stencil printing according to claim 1, wherein the color tone of the insoluble colorant present in the oil phase and the color tone of the insoluble colorant present in the aqueous phase are the same. 3. The color tone of the insoluble colorant present in the oil phase and the color tone of the insoluble colorant present in the aqueous phase are Co1or In.
dex No. C. I. 3. The W / O emulsion ink for stencil printing according to claim 2, wherein the colors of the pigments are the same. 4. The color tone of the insoluble colorant present in the oil phase and the color tone of the insoluble colorant present in the aqueous phase are Co1or In.
dex No. C. I. Pigment Co
1 or No. Are the same.
The W / O emulsion ink for stencil printing according to the above. 5. The stencil printing W according to claim 1, wherein a specific gravity difference between the insoluble colorant present in the oil phase and the insoluble colorant present in the aqueous phase is 2 or less. /
O-type emulsion ink. 6. The stencil printing W according to claim 1, wherein the insoluble colorant dispersed in the oil phase and the aqueous phase has an average particle size of 0.1 μm or more and less than 1 μm.
/ O emulsion ink. 7. The ratio a (% by weight) of the insoluble colorant present in the aqueous phase to the total insoluble colorant in the ink is 5 to 9%.
The W / O emulsion ink for stencil printing according to any one of claims 1 to 6, wherein the content is 5% by weight. 8. The stencil printing according to claim 7, wherein the ratio a (% by weight) further satisfies the following expression (1) with the ratio W (% by weight) of the aqueous phase in the emulsion ink. W / O emulsion ink. W−45 ≦ a ≦ W + 45 (1) 9. The stencil printing according to claim 8, wherein the ratio a (% by weight) further satisfies the following expression (2) with the ratio W (% by weight) of the aqueous phase in the emulsion ink. W / O emulsion ink. W−20 ≦ a ≦ W + 20 (2)