JP2002256195A - W/o emulsion ink for stencil printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a W/O emulsion ink for stencil printing excellently preventing offset and hand rubbing and hardly affected by an environmental temperature. SOLUTION: The W/O emulsion ink for stencil printing is composed of 10-90 wt.% of an oily phase and 90-10 wt.% of an aqueous phase, and comprises in the oily phase a polymeric material having a viscosity of at least 2,500 mPa.s (25 deg.C) in combination with a solvent having a viscosity of not higher than 10 mm<2> /s (40 deg.C) and a paraffinic component ratio (Cp), as measured by the ring analysis, of at least 90%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a stencil printing W / O.
The present invention relates to an emulsion ink, and more particularly to a W / O emulsion ink for stencil printing which is excellent in preventing set-off and hand rubbing, has low temperature dependency, and is excellent in preventing oil separation.

[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 base paper to the other side through a perforated portion of the stencil printing paper, thereby forming a printing material such as paper. This is for printing on the surface.

[0003] Conventionally used inks are water-in-oil emulsion inks, which include volatile solvents, non-volatile solvents, resins, coloring agents, surfactants, water, deicing agents,
It is composed of an electrolyte, a preservative, and the like.

[0004] In recent years, rotary stencil printing machines have also been automated by microcomputers and the like, and their operations have become simpler. As a result, the use of stencil printing has been increasing, and the demand for printing quality has also become high. .

[0005] On the other hand, a method of using a solvent containing a small amount of aromatic components and an alkyd resin has been proposed for drying inks in order to prevent set-off and hand rubbing. -107998 (Toyo Ink) and JP-A-8-100142 (Ideal Science) >>.

However, both of the above-mentioned inventions are effective in preventing set-off and rubbing under certain conditions, but use a material containing a large amount of a naphthene component as a solvent. There is a problem that the ink is easily affected by the environmental temperature, the ink ejection amount is insufficient in a low temperature environment, and the solid filling of the image is deteriorated.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned disadvantages of the prior art and, when applied to a rotary stencil printing machine, have excellent prevention of set-off and hand rubbing, and have low temperature dependence. Another object of the present invention is to provide a stencil printing W / O emulsion ink which is excellent in preventing oil separation.

[0008]

Means for Solving the Problems The present inventors have conducted various studies in order to achieve the above object, and by adopting the following means, the stencil printing W / W which has solved the above technical problems has been solved.
The present inventors have found that an O emulsion ink can be easily provided, and have reached the present invention.

A first aspect of the present invention is a W / O emulsion ink for stencil printing, comprising 10 to 90% by weight of an oil phase and 90 to 10% by weight of an aqueous phase, and having at least 2500 mPa · s (25%) in the oil phase. C.) or more and a solvent having a viscosity of 10 mm ² / s (40 ° C.) or less and a paraffin component (Cp) ratio of 90% or more by ring analysis are used in combination.

In the present invention, by adopting the first means, the stencil printing W / O, which is not easily affected by temperature during printing, in addition to being excellent in the effect of preventing set-off and hand rubbing. An emulsion ink was obtained.
These effects are achieved by using a polymer material having a viscosity of 2500 mPa · s (25 ° C.) or more and a solvent having a viscosity of 10 mm ² / s (40 ° C.) or less, so that the resin improves the adhesion between the pigment and the paper. That it has improved prevention of hand rubbing,
On the other hand, if only the resin is used, it is considered that the oil phase of the emulsion becomes too high in viscosity and the permeation rate is suppressed from being lowered, and it is effective in preventing set-off. In addition, if the solvent used at that time contains a large amount of naphthene component, the molecular chain of the emulsifier adsorbed at the emulsion interface is widened, and it can be estimated that the temperature dependence of the ink itself is deteriorated. Therefore, the paraffin component (Cp) ratio is 90%. It is considered that the use of the above-mentioned solvent has an excellent effect on temperature dependency.

A second aspect of the present invention is the first stencil printing W.
/ O emulsion ink, the viscosity 2500
The polymer material having a mPa · s (25 ° C.) or higher is a polymer material having a carboxyl group in a molecule. In the present invention, by adopting the second means, a W / O emulsion ink for stencil printing which is more excellent in stability against oil separation can be obtained. Viscosity 2500 mPa · s (25 ° C.) or more, preferably 500
A polymer material of 0 to 50,000 mPa · s (25 ° C.)
By having a carboxyl group in the molecule, in addition to the effect of the first aspect described above, the polymer material having a carboxyl group can be easily adsorbed on the pigment surface. Since the force is increased, it is considered that the effect that the oil separation preventing property is excellent can be further provided.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The water phase of the emulsion of the W / O emulsion ink for stencil printing includes water, an electrolyte, an antifungal agent, a water evaporation inhibitor, an antifreeze agent, a water-soluble polymer, an oil-in-water resin emulsion, a colorant, and a colorant dispersion. The oil phase comprises an oil component, a colorant dispersant, a colorant, an extender, a resin, an emulsifier, and the like. Known components that do not inhibit the formation of the emulsion are used as these components.

The polymer materials used in the present invention include:
A general oil-soluble polymer having a viscosity of 2500 mPa · s (25 ° C.) or more can be used. Specifically, rosin; polymerized rosin, hydrogenated rosin, rosin ester, rosin polyester resin, hydrogenated rosin ester, and the like Rosin-modified resins such as rosin-modified alkyd resin, rosin-modified maleic resin; rosin-modified phenolic resin; maleic acid resin; phenolic resin; petroleum resin; rubber derivative resin such as cyclized rubber; Resin; polymerized castor oil, high molecular weight polyglycerin fatty acid ester, etc., may be added alone or in admixture of two or more.
Typical resins are Tamanol 353, Tamanol 403, Tamanol 361 and Tamanol 3 manufactured by Arakawa Chemical Co., Ltd.
87, Tamanor 340, Tamanor 400, Tamanor 39
6, Tamanor 354, KG836, KG846, KG1
And rosin-modified phenol resins such as 834 and KG1801.

The viscosity used in the present invention is 10 mm ² / s
(40 ° C.) or less, preferably ² to 6 mm ² / s (40
° C) and a solvent having a paraffin component (Cp) ratio of 90% or more by ring analysis includes Isopar series (C, E, G, H, L, M) manufactured by Exxon Chemical Co., Ltd. In consideration of stability, it is preferable to use those oil components having less than 3% by mass of a polycyclic aromatic component which is an aromatic hydrocarbon containing three or more condensed aromatic rings.

The ring analysis used in the present invention is described in, for example, Lubrication Handbook, edited by The Japan Lubrication Society, Yokendo version, p.
344, and the test method is based on the ndM method. Also, ring analysis is based on structural group analysis.
p analysis). % Indicates the ratio of the carbon derived from the paraffin component to the carbon of the whole oil (paraffin, naphthene, allomer). Units of ring analysis is _{usually,% C A,% C N} ,% C P is used,
The meaning of each of these symbols is as follows. % C _A = 100 fraction of aromatic carbon number to total carbon number% C _N = 100 fraction of naphthenic carbon number to total carbon number% C _P = 100 fraction of paraffin carbon number to total carbon number

As the colorant used in the present invention, known pigments and disperse dyes having various colors can be used, and carbon blacks such as acetylene black, channel black and furnace black, and metal powders such as aluminum powder and bronze powder. Inorganic pigments such as red iron oxide, graphite, ultramarine blue, chromium oxide and titanium oxide; azo pigments such as insoluble azo pigments, azo lake pigments and condensed azo pigments; phthalocyanine pigments such as metal-free phthalocyanine pigments and copper phthalocyanine pigments; anthraquinone Quinacridone-based, isoindolinone-based, isoindoline-based, dioxazine-based, sulene-based, perylene-based, perinone-based, thioindigo-based, quinophthalone-based, condensed polycyclic pigments such as metal complexes, and lakes of acidic or basic dyes Oils such as organic pigments such as diazo dyes and anthraquinone dyes Sexual dyes, fluorescent pigments and the like.

As the fluorescent pigment, during or after bulk polymerization of a synthetic resin, a fluorescent dye which develops various hues is dissolved or dyed, and the obtained colored bulk resin is pulverized and refined. As a synthetic resin solid solution type, examples of the synthetic resin carrying a dye include a fluorescent pigment carrying a melamine resin, a urea resin, a sulfonamide resin, an alkyd resin, a polyvinyl chloride resin, or the like on the dye.

These dyes and pigments may be added to the oil phase, or both of the oil phase and the aqueous phase, or may be added alone or as a mixture of two or more. The average particle size of the insoluble colorant dispersed in the oil phase and the aqueous phase is 10 to 0.1 μm, preferably 1 to 0.1 μm.
m is desirable. The amount can be added according to the required amount, but is usually 2 to 15% by weight.

With respect to carbon black, an acidic carbon black having a pH of less than 5, preferably 2 to 4 when added to the oil phase, a pH of 5 or more when added to the aqueous phase,
It is preferable to use alkaline carbon black having a pH of preferably 6 to 10, more preferably a pH of 7 to 9 to show a uniform and fine dispersion state.
In addition, the ink stability is good, which is desirable.

A typical carbon black is MA
-100, MA-7, MA-77, MA-11, # 4
0, # 44 (Mitsubishi Chemical Corporation) Raven 1100, Ra
venl080, Raven1255, Raven76
0, Raven 410 (manufactured by Colombian Carbon) and the like.

In the present invention, it is also possible to use the following oils in addition to the solvent for the purpose of controlling the degree of volatilization and physical properties. Examples of the oil include petroleum solvents, liquid paraffin, spindle oil, machine oil, lubricating oil, mineral oil; linseed oil, tall oil, corn oil, olive oil, rapeseed oil, castor oil, dehydrated castor oil, soybean oil, Vegetable oils such as coconut oil and the like, specifically, for example, Gargo Oil Arctic Series (1010, 102
2, 1032, 1046, 1068, 1100, 303
2, 3046, 3068), Nippon Mitsubishi Spar Oil Series (B, C, D, E, etc.), Idemitsu Kosan Diana Process Oil (PX-32, PX-90, etc.)
PW-32, PW-90, PW-380, PS-32,
PS-90, PS-430, etc.), Diana Fresia series (S-32, S-90, P-32, P-90, P
-150, P-180, P-430, etc.).

A mutagenicity index MI of less than 1.0;
Preferably 0 to 0.7, 20 Alomar content (% C _A) is
55%, an aniline point of 100 ° C. or lower and benzo [a] anthracene, benzo [b] fluoranthene, benzo [j] fluoranthene based on the total weight of the oil;
The content of polycyclic aromatics such as benzo [k] fluoranthene, benzo [a] pyrene, dibenzo [a, j] acridine is individually 10 ppm by weight or less, and the total content is 50 ppm by weight or less; Preferably 0 to 30 weight p
pm, a highly safe allomer-based oil
If necessary, it may be used for the purpose of improving the dispersibility of the colorant. The mutagenicity index MI is defined as “Standard Tes” defined in ASTM-E-1687-95.
t forDetermining Carcinogenic Potential of Virgin
Base Oils in Metalworking Fluids.

The emulsifier used in the present invention is used for the purpose of forming a water-in-oil emulsion, and may be any of an anionic surfactant, a cationic surfactant, an amphoteric surfactant and a nonionic surfactant. As long as it has an effect on stability, it may be a low molecular weight or a high molecular weight, or may be used in combination. Among them, preferred are nonionic surfactants, for example, sorbitan monooleate, sorbitan sesquiolate, sorbitan triolate, sorbitan fatty acid esters such as sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan triolate Polyoxyethylene sorbitan fatty acid esters, such as glyceryl monostearate, decaglyceryl triolate, hexaglycerin polyricinoleate, etc. (poly) glycerin fatty acid esters, polyoxyethylene sorbit fatty acid esters, polyoxyethylene glycerin vegetable oil fatty acid esters, etc. Oxyethylene glycerin fatty acid ester, polyethylene glycol fatty acid ester, polyoxyethylene alkyl ether, Oxyethylene alkyl phenyl ether, polyoxyethylene alkylamine / fatty acid amide, polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene castor oil / hardened castor oil, higher alcohols, etc., and can be stored alone or in combination of two or more. To prepare an emulsion with high potency. The addition amount is usually 0.5 to 15% by weight, preferably 1 to 3% by weight of the ink weight.

In addition to the above, a resin, a dispersant for a colorant, an extender,
A gelling agent, an antioxidant and the like can be added. The above-mentioned emulsifier is also included in the oil phase. In addition, in the aqueous phase, an insoluble colorant dispersant, a water-soluble polymer, an antiseptic / fungicide, a water evaporation inhibitor, as long as the formation of the emulsion is not hindered,
Antifreezing agents, pH adjusters, electrolytes, extenders and the like can be added.

As the colorant dispersant for the colorant dispersed in the oil phase, those which do not inhibit the formation of an emulsion can be used, and the above-mentioned nonionic surfactants for emulsifiers and water-soluble polymers can also be used. Examples of the dispersant include nonionic surfactants such as sorbitan fatty acid esters such as sorbitan sesquiolate and polyglycerin fatty acid esters such as hexaglycerin polyricinoleate, alkylamine-based polymer compounds, aluminum chelate-based compounds, and styrene-maleic anhydride. Acid-based copolymeric polymer compound, polycarboxylic acid ester type polymer compound, aliphatic polycarboxylic acid, amine salt of high molecular polyester, ester type anionic surfactant, long chain amine salt of high molecular weight polycarboxylic acid, Salts of long-chain polyaminoamides and high-molecular acid polyesters, polyamide compounds, phosphate ester surfactants, alkyl sulfocarboxylates, α-olefin sulfonates, dioctyl sulfosuccinates, polyethylene imine, alkylolamine salts, and Insoluble colorants such as Rukido resins, even a resin having a dispersing ability. In addition to these, ionic surfactants and amphoteric surfactants may be used as long as the storage stability of the ink is not impaired.

These dispersants may be added alone or as a mixture of two or more kinds. The amount of the colorant dispersant other than the polymer and resin is 40% by weight or less, preferably 2 to 35% by weight of the colorant. %. 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 another dispersant, the amount of the resin added is insoluble. Agent 1
Is preferably 0.05 or more.

The gelling agent has a role of gelling the resin contained in the oil phase to improve the storage stability, fixability and fluidity of the ink. The gelling agent added to the ink of the present invention is oil. Compounds that coordinate with the resin in the phase are preferred. Illustrating such compounds are Li, Na, K, Al,
Organic acid salts containing metals such as Ca, Co, Fe, Mn, Mg, Pb, Zn, and Zr; organic chelate compounds; metal soap oligomers; specifically, metal octylates such as aluminum octylate; Examples include metal salts of naphthenic acid such as manganese acid, stearic acid salts such as zinc stearate, and organic chelate compounds such as ethyl acetoacetate aluminum diisopropylate. One or more of these gelling agents may be added to the oil phase,
The addition amount is 15% or less of the resin in the oil phase, preferably 5%.
-10% by weight.

Antioxidants added to the oil phase include dibutylhydroxytoluene, propyl gallate, butylhydroxyanisole, and the like. The addition of these additives prevents the oxidation of the binder resin and the like in the oil phase, thereby reducing the viscosity of the ink. Is prevented from rising. The amount of addition is 2% by weight or less, preferably 0.1 to 1.0% by weight of the oil in the ink. The antioxidants may be used alone or in combination of two or more.

An extender pigment can be added to the ink for adjusting the viscosity. As the extender pigment added to the ink, clay, silica, talc, clay, calcium carbonate, barium sulfate, titanium oxide, alumina white, diatomaceous earth,
Inorganic fine particles such as kaolin, mica, aluminum hydroxide and the like, and organic fine particles such as polyacrylate, polyurethane, polyester, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, polysiloxane, phenol resin, epoxy resin and the like. Fine particles made of a copolymer are exemplified. Specific examples include Aerosil 200, Aerosil R972 (Nippon Aerosil), NEW D ORBEN (Shiraishi Kogyo), BEN-GEL, S-BEN, ORGANI.
TE etc. (Toyojun Yokosha), TIXOGEL series (V
P, DS, GB, VG, EZ-100, etc.), OPTI
GEL (Nissan Gardler Catalyst Co., Ltd.) and the like. These may be added to the oil phase, the aqueous phase or both phases. The addition amount is preferably from 0.1 to 50% by weight, more preferably from 1 to 5% by weight, based on the ink.

A water-soluble polymer 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.
Specific examples of the water-soluble polymer include the following natural or synthetic polymers. For example, natural polymers such as starch, mannan, sodium alginate, galactan, tragacanth gum, gum arabic, burlan, dextran, xanthan gum, glue, gelatin, collagen, casein;
Semi-synthetic polymers such as carboxymethylcellulose, hydroxymethylcellulose, methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, hydroxymethylstarch, carboxymethylstarch and dialdehyde starch; neutralized products such as acrylic resin and sodium polyacrylate , Polyvinyl imide, polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene imine, polyacrylamide, poly N-alkyl-substituted acrylamide such as poly N-acryloylpyrrolidine and poly N-isopropylacrylamide, polyethylene oxide,
Polyvinyl methyl ether, styrene-maleic anhydride copolymer, styrene-acrylic acid copolymer and polymers partially hydrolyzed with alkyl groups, and substituents are partially substituted for acrylamide polymers and acrylic polymers Alternatively, a copolymer type polymer which is made hydrophobic with an alkyl group may be used. Alternatively, a block copolymer of polyethylene and polypropylene or polybutylene can be used. These water-soluble polymers may be used alone or as a mixture of two or more kinds.
Preferably, 0.5 to 15% by weight is added.

The O / W resin emulsion may be a synthetic polymer or a natural polymer. As the polymer, vinyl acetate, acrylic ester, methacrylic ester, vinyl chloride, ethylene-vinyl acetate copolymer, vinyl acetate-
Acrylic ester copolymers, styrene-acrylic ester copolymers, vinylidene chloride-acrylic ester copolymers, vinyl chloride-vinyl acetate copolymers, urethanes and the like can be mentioned. 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, a surfactant, It may be synthesized by soap-free emulsion polymerization. These O
The minimum film forming temperature of the / W resin emulsion is desirably 40 ° C. or lower.

Preservatives and fungicides added to the aqueous phase are added to prevent the growth of bacteria and mold in the emulsion, and it is desirable to add a preservative and fungicide when the emulsion is stored for a long period of time. The addition amount of the water contained in the ink is 3% by weight or less, preferably 0.1 to 1.2% by weight. Salicylic acid, phenols, methyl p-oxybenzoate, p-
In addition to aromatic hydroxy compounds such as ethyl oxybenzoate and chlorine compounds thereof, sorbic acid, dehydroacetic acid and the like are used, and these may be used alone or in combination of two or more.

The anti-evaporation agent and the anti-freeze agent for water can be used in combination. Chemicals added for these purposes include glycol-methanol such as ethylene glycol, diethylene glycol and propylene glycol, ethanol, isopropanol, butanol and isobutanol. Lower saturated monohydric alcohols; polyhydric alcohols such as glycerin and sorbitol; One or two of these chemicals may be added, and the added amount is 15% by weight or less, preferably 4 to 12% by weight of the weight of water in the ink.

The pH adjusters added to the aqueous phase are triethanolamine, sodium acetate, triamylamine, etc. When necessary, these pH adjusters are added to maintain the pH of the aqueous phase at 6-8. Can be. If 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 a thickener is added. When added to the aqueous phase, it is added to enhance the storage 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 citrate ion, tartrate ion,
It is preferable that the electrolyte contains an anion such as a sulfate ion or an acetate ion, or an alkali metal ion or an alkaline earth metal ion. Therefore, the electrolyte added here is preferably aluminum sulfate, magnesium sulfate, sodium sulfate, sodium citrate, sodium hydrogen phosphate, sodium borate, sodium acetate, and the like,
The addition amount is 0.1 to 2% by weight of the aqueous phase, preferably 0.1 to 2% by weight.
5 to 1.5% by weight.

In addition to the above, the water-in-oil 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 as necessary to these additives, and the amounts of these additives may be about the same as those of conventional products.

The 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 conventional emulsion ink production, and emulsifying both in a known emulsifying machine to form an ink. That is, an oil phase in which additives such as a coloring agent, an emulsifier, and a resin to be added as needed are dispersed well is prepared, and a coloring agent, a preservative, a fungicide, a water-soluble polymer, and the like are added to the oil phase as needed. What is necessary is just to gradually add and emulsify the added aqueous solution.

[0038]

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 and 2 and Comparative Examples 1 and 2 O / W emulsion inks were prepared using colorants, oils or solvents,
An insoluble colorant dispersant, a surfactant for emulsification, a polymer material, and the like are added, and the mixture is milled with a three-roll mill to form an oil phase, to which an aqueous phase including water, an antifreezing agent, an electrolyte, and the like is added and emulsified. Thus, an emulsion ink for a stencil printing machine was obtained.
If necessary, another component such as an extender may be added. The viscosity of the ink can be adjusted by the stirring conditions. The viscosity of the ink is not particularly limited as long as it is suitable for the system, but the viscosity at a shear rate of 20 s ^-1 is 3 to 40 Pa.
S is desirable, and preferably 10 to 30 Pa · s.

The amount of carbon black used in the examples and comparative examples was RAMB manufactured by Colombian Carbon.
VEN1100, the pigment dispersant was Plainact AL-M manufactured by Ajinomoto Co., the emulsifier (sorbitan sesquiolate) was SO-15 manufactured by Nikko Chemicals, and the solvent was ISOPAR M (viscosity 2.3%, Cp99%) by Exxon Chemical Co., Ltd. Stone AF Solvent No. 4 (viscosity 2.4, Cp22%), 40 motor oil manufactured by Sanyu Chemical Industry Co., Ltd. (viscosity 141.3, C
p68%), polymer material is Ajispar PN4 manufactured by Ajinomoto Co.
11. Harima Chemicals' soybean oil-modified alkyd resin, ethylene glycol and magnesium sulfate were commercially available, and tap water was used as water. Table 1 shows the formulations of Examples 1 and 2 and Comparative Examples 1 and 2. (Evaluation of emulsion ink) Using these inks,
Printing was performed sufficiently by using a commercially available stencil printing machine made by Ricoh (VT3920) to spread the ink into the printing machine, and then printing was performed.

The set-off is evaluated by visually observing the back side of the printed solid portion, and the badly offset stains from the immediately preceding printed matter are marked as x, the relatively small stains are marked as ◎, and x △ The evaluation was made in four steps of ◎. Hand rubbing was carried out by rubbing the image surface 30 minutes after printing with a finger, and evaluation was made on a scale of ×× ○○ with x having a lot of dirt and ◎ with a relatively small dirt. For the solid filling, the solid filling ratio of a solid portion of an image printed in an environment of 10 ° C. and 30 ° C. was measured using a Macbeth densitometer. The solid filling ratio has a numerical value of 0% to 100%, and the larger the numerical value, the better the solid filling. Oil separation was performed by visually observing the ink in the ink pack that had been left at 60 ° C. for 3 months.
A relatively small number was evaluated as ◎, and evaluated on a four-point scale of × △ ○ ◎. Table 2 shows the evaluation results of Examples 1 and 2 and Comparative Examples 1 and 2.

[0042]

[Table 1]

From Example 1 and Comparative Example 1 in Table 2, it was found that the oil phase had a polymer material having a viscosity of at least 2500 mPa · s (25 ° C.), a viscosity of 10 mm ² / s (40 ° C.) or less, and a ring analysis. When used in combination with a solvent having a paraffin component (Cp) ratio of 90% or more, in addition to being excellent in the effect of preventing set-off and hand rubbing, the effect of being less affected by temperature during printing is the effect of viscosity. 2500 mPa · s (2
The effect that the polymer material having a temperature of 5 ° C. or higher has a carboxyl group in the molecule has a further excellent oil separation preventing property.

[0044]

[Table 2]

[0045]

According to the first aspect of the present invention, there is provided a stencil printing W / O emulsion ink which is excellent in prevention of set-off and hand rubbing and which is less affected by environmental temperature. According to the second aspect of the present invention, there is provided a stencil printing W / O emulsion ink which has the effect of preventing oil separation in addition to the effect of the first aspect.

Claims (2)

[Claims] 1. An oily phase 10-90% by weight and an aqueous phase 90-1.
0% by weight and at least 2% in the oil phase
Use of a polymer material having a viscosity of 500 mPa · s (25 ° C.) or more and a solvent having a viscosity of 10 mm ² / s (40 ° C.) or less and a paraffin component (Cp) ratio of 90% or more by ring analysis is used in combination. Characteristic W / O emulsion ink for stencil printing. 2. The stencil printing W according to claim 1, wherein the polymer material having a viscosity of 2500 mPa · s (25 ° C.) or more has a carboxyl group in the molecule.
/ O emulsion ink.