JP2000160082A - Emulsion ink for stencil printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an emulsion ink for stencil printing for causing no offset, little oil-separation of the ink and having excellent storage stability, particularly stability in a hot environment by blending an aluminum chelate compound and a polyglycerin fatty acid ester with an ink consisting of an oil and an aqueous components in specific proportions. SOLUTION: This emulsion ink for stencil printing is obtained by blending an aluminum chelate compound represented by formula I wherein R1 is isopropyl group, sec-butyl group or isobutyl group; R2 is oleyl group or octadecyl group; (n) is 1 or 2 and a polyglycerin fatty acid ester with a W/O emulsion ink consisting of an oil phase of 10-90 wt.% and an aqueous phase of 90-10 wt.%. A content of the aluminum chelate compound is 0.5-100 wt.% on the basis of a pigment and a content of the polyglycerin fatty acid ester is 0.5-100 wt.%. The aluminum chelate compound is obtained by a reaction of formula II using an aluminum alcoholate and an acetoacetic acid ester as raw materials.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stencil emulsion ink, and more particularly, to a stencil emulsion ink which has a low oil separation and excellent storage stability at high temperatures.

[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.

As a form of ink used in this printing method, W / O in consideration of matching with a printing machine is used.
Emulsion ink is mainly used. The W / O emulsion ink is a complicated system in which pigment particles and water phase particles are dispersed in a micro phase separated state in oil as a dispersion medium. Oil separation easily occurs in the ink, and as a result, oil bleeds on an image. It is very difficult to satisfy the required quality of the ink and to secure the initial quality for a long period of time, especially when the ink is used in tents in summer or when shipping during export. When the ink is exposed to a high temperature environment (50 ° C. to 70 ° C.), the ink undergoes remarkable aging, and the aggregation of the pigment particles as a dispersoid and the coalescence of the aqueous phase particles are accelerated, thereby further maintaining the initial quality. Because of the difficulty, it has been desired to develop an ink having excellent stability.

[0004] As an emulsion ink for stencil printing which solves these problems, for example, a rosin-modified phenol resin having a tolerance of 4.0 to 20.0 (g / g) by No. 5 solvent is contained to improve the storage stability. Improved drying properties after printing (JP-A-9-268268),
Emulsifiers containing polyglycerol, oxyfatty acid esters of polyhydric alcohols selected from sugars and sugar alcohols, and improved drying and stability due to high water content (Japanese Patent Publication No. 3-78433), and aluminum chelate compounds To improve the storage stability and fixability of the ink (JP-A-6-128518),
Known are those containing a surfactant having an LB of 3.0 to 5.5 and having a thickened aqueous phase (No. 2585927).

[0005] However, the conventional inks described above do not have sufficient effects of suppressing oil separation and imparting stability during high-temperature storage. That is, in the ink containing No. 5 solvent and rosin phenol, the viscosity increases during storage at high temperature, and the permeability after storage deteriorates, so that set-off deteriorates. In addition, an ink using an oxyfatty acid ester of a polyhydric alcohol selected from polyglycerin, sugars and sugar alcohols as an emulsifier has poor emulsion stability during high-temperature storage, and causes loosening of the ink and water separation. Further, in an ink containing an aluminum chelate compound, pigment aggregation easily occurs during high-temperature storage, so that set-off after storage is poor. Furthermore, in the ink using a surfactant in which the HLB contains 3.0 to 5.5 in the oil phase of the surfactant and the aqueous phase is thickened, the stability during high-temperature storage is good. However, there is a problem that oil separation is large and oil bleeding easily occurs on an image. Thus, there is a demand for the development of an ink that has little oil separation and has excellent storage stability, especially stability in a high-temperature environment.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned disadvantages of the prior art, has no set-off, hardly causes oil separation of ink, and has excellent storage stability, especially in a high-temperature environment. An object of the present invention is to provide an emulsion ink for stencil printing.

[0007]

According to the present invention, an oil phase 1 is provided.
Stencil printing, characterized in that a water-in-oil emulsion ink composed of 0 to 90% by weight and an aqueous phase of 90 to 10% by weight contains an aluminum chelate compound represented by the following general formula and a polyglycerin fatty acid ester. A water-in-oil emulsion ink is provided.

Embedded image (In the formula, R ₁ represents an isopropyl group, a sec-butyl group or an isobutyl group, R ₂ represents an oleyl group or an octadecyl group, and n represents 1 or 2.) Further, according to the present invention, the carbon content of naphthenic components in the carbon distribution by ring analysis C _N 35% or more,
4. The stencil printing according to claim 1, wherein a non-volatile mineral oil having a paraffin component carbon content _CP of 50% or less is contained alone or in combination with another oil. A W / O emulsion ink is provided.

The present inventors have conducted various studies to achieve the above object. As a result, by containing the aluminum chelate compound represented by the above general formula and polyglycerin fatty acid ester, the oil separation of the ink was reduced and the stencil printing W / O emulsion ink having excellent high-temperature storage stability can be obtained, further the content C _N of carbon naphthenic components in the carbon distribution due to ring analysis of 35% or more, and the carbon content of paraffin components C It has been found that the above effects can be further improved by adding a non-volatile mineral oil having a _P content of 50% or less, alone or in combination with another oil, thereby completing the present invention.

In the present invention, the reason for having such an effect is not clear, but an aluminum chelate compound having excellent adsorptivity to the pigment surface does not disperse and finely disperse the pigment particles, and at the same time has a strong steric hindrance effect. Since the glycerin fatty acid ester forms a thick solvation layer while maintaining fluidity, it prevents re-aggregation of pigment particles and can maintain a good dispersion state for a long time even in a high temperature environment. It can be considered that the improvement of the oil wrapping power can reduce oil separation and prevent oil bleeding on an image. Further, the carbon content of naphthenic component C _N is less than 35%, and by the content C _P carbon paraffinic components used nonvolatile mineral oil is 50% or less, good for the above dispersion It is considered that the above-mentioned dispersion and dispersion stabilization effects are further improved, probably because the solvent has good compatibility.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The contents of an aluminum chelate compound and a polyglycerin fatty acid ester to be added to the W / O emulsion ink for stencil printing of the present invention are each 0.5 to 100% by weight based on the pigment. Is preferred. If the addition amount of the aluminum chelate compound is less than 0.5% by weight based on the pigment, dispersion is insufficient, and
If it exceeds 100% by weight, the effect will not change and the cost will increase. Therefore, the addition amount is preferably 0.5 to 100% by weight based on the pigment. If the amount of the polyglycerin fatty acid ester is less than 0.5% by weight of the pigment, the effect of the present invention is not sufficient, and if it exceeds 100% by weight, there is a problem that the ink viscosity is too high. Is preferably 0.5 to 100% by weight based on the weight of the pigment. Furthermore, the content C _P carbon paraffinic component content C _N at less than 35% of carbon naphthenic components poor little compatibility with oil more than 50%, the stabilizing effect is small, the naphthenic component of the carbon It is desirable to use an oil having a content of 35% _CN or more and a carbon content of a paraffin component of 50% _CP or less.

Hereinafter, the present invention will be described in more detail.
The aqueous phase of the emulsion includes water, an electrolyte, a water evaporation inhibitor, a water-soluble polymer, an oil-in-water resin emulsion (hydrophobic polymer), a fungicide, and the like. The oil phase includes an oil component, a pigment, a pigment, and the like. It is composed of a dispersant, an emulsifier, a resin and the like. Known components that do not inhibit the formation of the emulsion are used as these components.

The aluminum chelate compound represented by the above general formula used in the emulsion ink of the present invention is used as a dispersant for a pigment. The compound is prepared by using aluminum alcoholate and acetoacetate as raw materials. 1 can be obtained.

[Table 1] (In the formula, R ₁ , R ₂ , and n are the same as above.) Commercial products include aluminum chelate M manufactured by Kawaken Fine Chemical Co., Ltd., and Plenact AL-M manufactured by Ajinomoto Co., Inc. The aluminum chelate compound is used as an oil phase component.

The polyglycerin fatty acid ester used in the emulsion ink of the present invention is synthesized from polyglycerin and a fatty acid. The polyglycerin preferably has a degree of polymerization of 2 to 14, and examples thereof include diglycerin, triglycerin, hexaglycerin, and decaglycerin. As the fatty acid, a saturated or unsaturated fatty acid having 1 to 40 carbon atoms is preferable, and examples thereof include ricinoleic acid. In the present invention, as the polyglycerin aliphatic ester, the number of ester bonds between the polyglycerin and the aliphatic is from 1 to 32,
Preferably it is 2-10.

The oil used in the oil phase of the emulsion ink of the present invention is a mineral oil or a vegetable oil. Examples of the mineral oil include petroleum solvents, liquid paraffin, spindle oil, light oil, kerosene, machine oil, Gear oil, lubricating oil, motor oil and the like, and vegetable oils include, for example, linseed oil, tall oil, corn oil, olive oil, rapeseed oil, castor oil, dehydrated castor oil, soybean oil and the like. In the present invention, a synthetic oil can also be used. Representative synthetic oils include phthalic acid esters such as polyisobutylenes, hydrogenated polydecenes, trimethylolpropane esters, neopentyl esters, pentaerythritol esters, dibutyl phthalate, and phosphorus such as fluorocarbons and phosphate esters. Esters of contained acids, siloxanes, silicones (polysiloxanes), and alkyl-substituted diphenyl ethers represented by butyl-substituted bis (p-phenoxyphenyl) ethers, and the like. As a petroleum-based solvent, a mixed solvent such as Isopar manufactured by Exxon or a solvent such as AF5 solvent manufactured by Nippon Oil Co., Ltd. may be used. Then, these oils may be used as a mixture of two or more types alone, preferably the carbon content of naphthenic component C _N is less than 35%, and the content C _P carbon paraffin component 50% It is preferable to use the oil of

The pigments used in the present invention (the pigments and dyes used as colorants in the present invention are collectively referred to as pigments) are carbon black, titanium oxide; azo pigments, phthalocyanine pigments, nitroso pigments, nitro pigments. Vat dye pigments, mordant dye pigments, basic dye pigments, acid dye pigments and natural dye pigments; oil-soluble dyes such as diazo dyes and anthraquinone dyes; These pigments may be added alone or as a mixture of two or more. The amount of the pigment to be added is 1 to 15% by weight, preferably 2 to 10% by weight based on the weight of the ink.

As the emulsifier used in the present invention, it is preferable to use a nonionic surfactant.
Examples of the sorbitan fatty acid ester include sorbitan monolaurate, sorbitan monopartate, sorbitan sesquioleate, and polyoxyethylene sorbitan fatty acid ester. In addition, glycerin fatty acid ester, polyglycerin fatty acid ester, propylene glycol fatty acid ester, pentaerythritol fatty acid ester, polyoxyethylene sorbite fatty acid ester,
Polyoxyethylene glycerin fatty acid ester, polyethylene glycol fatty acid ester, polyethylene alkyl ether, polyoxyethylene phytosterol ether, polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene castor oil, polyoxyethylene hardened castor oil, poly Oxyethylene lanolin derivatives,
Examples thereof include polyoxyethylene alkylamine, polyoxyethylene fatty acid amide, and polyoxyethylene alkylphenylformaldehyde condensate. These may be added to the ink singly or as a mixture of two or more kinds as long as the effect is not impaired, and the addition amount may be 1 to 20% by weight of the ink weight.

In addition to the above, a resin, a pigment dispersant, a gelling agent, an antioxidant, and the like can be added to the oil phase as long as the formation of the emulsion is not hindered. In addition, the coloring agent and the emulsifier are also included in the oil phase. Further, a water-soluble polymer, a preservative / fungicide, a water evaporation inhibitor, an antifreezing agent, a pH adjuster, an electrolyte, and the like can be added to the aqueous phase as long as the formation of the emulsion is not hindered. It is sufficient that the water is clean, and specifically, tap water, ion-exchanged water, distilled water, or the like can be used.

The resin added to the oil phase is a binder resin which has been conventionally added for the purpose of fixing the pigment to the printing material, dispersing the pigment, and improving the aging stability of the ink. Therefore, a conventionally added resin may be added, and specifically, rosin; rosin-based resin such as polymerized rosin, hydrogenated rosin, rosin ester, hydrogenated rosin ester; rosin-modified resin such as rosin-modified phenolic resin Resin; phenolic resin; petroleum resin, alkyd resin, rubber derivative; polymerized castor oil;
Seeds can be mixed and added. The addition amount is 20% by weight or less, preferably 1 to 7% by weight of the ink weight.

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 and the like, specifically, metal octylates such as aluminum octylate; Naphthenate metal salts such as manganese naphthenate, stearates such as zinc stearate,
Organic chelate compounds such as aluminum diisopropoxide monoethyl acetoacetate are exemplified. One or more of these gelling agents may be added to the oil phase, and the amount added is 15% or less, preferably 5 to 10% by weight of the resin in the oil phase.

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.

The water-soluble polymer added to the aqueous phase of the emulsion ink of the present invention is added for moisturizing and thickening, and can be used within a range that does not impair the effects of the present invention. Specifically, the following natural or synthetic polymers are added. 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, methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, hydroxymethyl starch, carboxymethyl starch, dialdehyde starch; polyacrylic acid, sodium polyacrylate, polyethanol triethanolamine, etc. Acrylic resin derivative, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, N,
N-alkyl-substituted acrylamides such as N-dimethylacrylamide and N-ethylacrylamide, synthetic polymers such as polyethylene oxide, polyvinyl methyl ether and polyvinyl acetate, and water-soluble synthetic polymers synthesized from two or more different monomers Are used. These water-soluble polymers may be used alone or as a mixture of two or more kinds, and 25% by weight or less, preferably 0.5 to 15% by weight of water contained in the ink is added.

An oil-soluble polymer can be added to the aqueous phase in a state of being dispersed in water for the purpose of improving the fixability of the ink.
This polymer may be a synthetic polymer or a natural polymer.
It may be added as a W-type resin emulsion. As the polymer, vinyl acetate polymer, acrylate polymer, methacrylate polymer, vinyl chloride polymer,
Ethylene-vinyl acetate copolymer, vinyl acetate-acrylate copolymer, styrene-acrylate copolymer, vinylidene chloride-acrylate copolymer, vinyl chloride-vinyl acetate copolymer, urethane, etc. Can be 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 W / O emulsion ink is not impaired. The dispersing method may be such that a dispersant, a protective colloid and a surfactant may be added. It may be synthesized by free emulsion polymerization. When used as a resin emulsion, it is desirable that the minimum film-forming temperature be 40 ° C. or lower and that the blending amount be 0.5 to 45% by weight in terms of solid content relative to the total emulsion ink.

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

The electrolyte added to the aqueous phase is added to enhance the stability of the emulsion. Therefore,
It is preferable to add an electrolyte composed of ions having a high syneresis sequence effective for improving the stability of the emulsion. Anions with a high liquid separation sequence are citrate ions, tartrate ions, sulfate ions, and acetate ions, and cations with a high liquid separation sequence are alkali metal ions and alkaline earth metal ions. As the electrolyte to be used, a salt in which at least one of the anion and the cation is the above-mentioned ion is preferable. 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 0.5 to 1.5% by weight
It is.

The antiseptic / fungicide added to the aqueous phase is added to prevent the growth of bacteria and fungi in the emulsion. When the emulsion is stored for a long period of time, an antiseptic / fungicide is usually added. . The amount of addition is 3% by weight or less of water contained in the ink, 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.

In addition to the above, a pH adjuster, an antifreezing agent and the like can be added to the aqueous phase within a range that does not hinder the formation of the emulsion. The pH adjusters added to the aqueous phase are triethanolamine, sodium acetate, triamylamine, and the like. If necessary, these pH adjusters can be added to maintain the pH of the aqueous phase at 6 to 8. it can. PH of aqueous phase
Is out of the above range, there is a problem that the effect is impaired when a water-soluble polymer for a thickener is added.

In addition to the above, the W / O emulsion ink for stencil printing of the present invention contains an oil wax to improve the separation between the printing paper and the printing drum during printing or to prevent the printing paper from rolling up. Can be added.
Further, to the aqueous phase, triethanolamine, ammonia, 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.

In the emulsion ink of the present invention, the oil phase and the aqueous phase are adjusted in the same manner as in the conventional emulsion ink production, and each is stirred and dispersed by a stirrer, a three-roll mill, a ball mill, or the like. What is necessary is just to emulsify in a well-known emulsifying machine and to make it an ink. That is, an oil phase in which additives such as a coloring agent, an emulsifier, and a resin to be added as necessary are dispersed well is adjusted at room temperature, and a preservative, a fungicide, a water-soluble polymer, and the like are added as necessary. What is necessary is just to gradually add and emulsify the added aqueous solution.

[0029]

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. For the ink preparation procedure of each Example and Comparative Example, the following raw material components were used, and the pigment dispersion was adjusted by a colorant, an oil,
A pigment dispersant is milled with three rolls, and an emulsifier, an oil, etc. are added to the pigment dispersion to form an oil phase, which comprises water, an antifreezing agent, a preservative / antifungal agent, an electrolyte, and the like. An aqueous phase was added and emulsified to obtain an emulsion ink for stencil printing.

Example 1 Colorant: carbon black 7.0 parts Dispersant: aluminum chelate compound (Ajinomoto) 0.5 part: hexaglycerin polyricinoleate (Nikko Chemicals) 0.5 part Oil: Nisseki Super Oil B ( Oil Corporation) 22.0 parts _{(C N: 28.0%, C} P: 65.0%) emulsifier: sorbitan monooleate 5.0 parts water: ion-exchanged water 54.0 parts antifreeze agent: ethylene glycol 10. 0 parts Electrolyte: magnesium sulfate 0.9 parts Preservative: methyl p-oxybenzoate 0.1 parts

Example 2 Colorant: carbon black 7.0 parts Dispersant: aluminum chelate compound (Ajinomoto) 0.5 part: hexaglycerin polyricinolate (Nikko Chemicals) 0.5 part Oil: Sansen Oil 430 (Sun Petroleum) ) 22.0 parts _{(C N: 43.0%, C} P: 45.0%) emulsifier: sorbitan monooleate 5.0 parts water: ion-exchanged water 54.0 parts antifreeze agent: ethylene glycol 10.0 parts Electrolyte: magnesium sulfate 0.9 part Preservative: methyl p-oxybenzoate 0.1 part

Example 3 Colorant: carbon black 7.0 parts Dispersant: aluminum chelate compound (Ajinomoto) 0.03 parts: hexaglycerin polyricinolate (Nikko Chemicals) 0.5 part Oil: Nisseki Super Oil B ( Oil Corporation) 22.47 parts _{(C N: 28.0%, C} P: 65.0%) emulsifier: sorbitan monooleate 5.0 parts water: ion-exchanged water 54.0 parts antifreeze agent: ethylene glycol 10. 0 parts Electrolyte: magnesium sulfate 0.9 parts Preservative: methyl p-oxybenzoate 0.1 parts

Example 4 Colorant: carbon black 7.0 parts Dispersant: aluminum chelate compound (Ajinomoto) 0.5 part: hexaglycerin polyricinolate (Nikko Chemicals) 0.03 parts Oil: Nisseki Super Oil B ( Oil Corporation) 22.47 parts _{(C N: 28.0%, C} P: 65.0%) emulsifier: sorbitan monooleate 5.0 parts water: ion-exchanged water 54.0 parts antifreeze agent: ethylene glycol 10. 0 parts Electrolyte: magnesium sulfate 0.9 parts Preservative: methyl p-oxybenzoate 0.1 parts

[0034] Comparative Example 1 Colorant: Carbon black 7.0 parts Dispersant: aluminum chelate compound (Ajinomoto) 0.5 parts Oil: Oil Super oil B (Nippon Oil) 22.5 parts (C _N: 28.0 %, C _P: 65.0%) emulsifier: sorbitan monooleate 5.0 parts water: ion-exchanged water 54.0 parts antifreeze agent: ethylene glycol 10.0 parts electrolyte: 0.9 parts preservative magnesium sulfate: p -Methyl oxybenzoate 0.1 part

[0035] Comparative Example 2 Colorant: Carbon black 7.0 parts dispersant: hexaglycerin polyricinoleate (Nikko Chemicals) 0.5 parts of oil: Oil Super oil B (Nippon Oil) 22.5 parts (C _{N : 28.0%, C P: 65.0} %) emulsifier: sorbitan monooleate 5.0 parts water: ion-exchanged water 54.0 parts antifreeze agent: ethylene glycol 10.0 parts electrolyte: 0.9 parts of magnesium sulfate Preservative: 0.1 part of methyl p-oxybenzoate

[0036] Comparative Example 3 Colorant: Carbon black 7.0 parts oil: Oil Super oil B (Nippon Oil) 23.0 parts _{(C N: 28.0%, C} P: 65.0%) Emulsifier: Sorbitan Monoolate 5.0 parts Water: ion-exchanged water 54.0 parts Antifreeze: ethylene glycol 10.0 parts Electrolyte: magnesium sulfate 0.9 parts Preservatives: methyl p-oxybenzoate 0.1 parts

[0037] Comparative Example 4 Colorant: Carbon black 7.0 parts Dispersant: aluminum chelate compound (Ajinomoto) 0.5 parts Oil: San Sen Oil 430 (Sun Oil) 22.5 parts (C _N: 43.0%, C _P: 45.0%) emulsifier: sorbitan monooleate 5.0 parts water: ion-exchanged water 54.0 parts antifreeze agent: ethylene glycol 10.0 parts electrolyte: 0.9 parts preservative magnesium sulfate: p-oxy Methyl benzoate 0.1 part

[0038] Comparative Example 5 Colorant: Carbon black 7.0 parts Dispersant: hexaglycerin polyricinoleate (Nikko Chemicals) 0.5 parts Oil: San Sen Oil 430 (Sun Oil) 22.5 parts (C _N: 43. _{0%, C P: 45.0%} ) emulsifier: sorbitan monooleate 5.0 parts water: ion-exchanged water 54.0 parts antifreeze agent: ethylene glycol 10.0 parts electrolyte: 0.9 parts preservative magnesium sulfate: 0.1 parts of methyl p-oxybenzoate

[0039] Comparative Example 6 Colorant: Carbon black 7.0 parts Oil: San Sen Oil 430 (Sun Oil) 23.0 parts _{(C N: 43.0%, C} P: 45.0%) Emulsifier: Sorbitan monooleate 5.0 parts Water: Ion-exchanged water 54.0 parts Antifreeze: Ethylene glycol 10.0 parts Electrolyte: Magnesium sulfate 0.9 parts Preservatives: methyl p-oxybenzoate 0.1 parts

(Evaluation of Emulsion Ink) The inks of the above Examples and Comparative Examples were evaluated as follows.
Table 1 shows the results. <Offset resistance> Using each ink, at the time of preparation and one month after 60 ° C., a commercially available Ricoh stencil printing machine (Preport VT395)
In step 0), the printing was performed sufficiently to allow the ink to pass through the printing press, followed by printing to obtain a printed image. Regarding the image,
The set-off resistance was evaluated according to 10 ranks from 1 to 10. (10: excellent ~ 1: inferior) <Oil separation> As a measurement of the amount of oil separation of each ink at the time of preparation and after storage at 60 ° C for one month, a centrifuge (manufactured by Kubota) was used.
7000G is added for 2 hours, and the amount of separation is expressed in%.
The amount of oil separation was obtained. <Storage stability> The set-off resistance and the amount of oil separation were evaluated by comparing the evaluation results at the time of preparation and after storage at 60 ° C for one month.

[0041]

[Table 2]

[0042]

The W / O emulsion ink for stencil printing of the present invention is prepared by combining the above-mentioned aluminum chelate compound having a specific structure with a polyglycerin fatty acid ester, so that set-off resistance and oil separation of the ink are reduced. It has an excellent effect on high-temperature storage stability (Examples 1 to 4). Further, by further containing the oil having the specific composition of the present invention, the above effect is further improved (Example 2).

Claims (4)

[Claims] 1. An oily phase of 10 to 90% by weight and an aqueous phase of 90 to 10% by weight.
What is claimed is: 1. A W / O emulsion ink for stencil printing, which comprises an aluminum chelate compound represented by the following general formula and a polyglycerin fatty acid ester in a W / O emulsion ink constituted by weight%. Embedded image (In the formula, R ₁ represents an isopropyl group, a sec-butyl group or an isobutyl group, R ₂ represents an oleyl group or an octadecyl group, and n represents 1 or 2.) 2. The stencil printing W / O emulsion ink according to claim 1, wherein the content of the aluminum chelate compound is 0.5 to 100% by weight with respect to the pigment. 3. The stencil printing W / O emulsion ink according to claim 1, wherein the content of the polyglycerin fatty acid ester is 0.5 to 100% by weight with respect to the pigment. 4. Further, the carbon content of naphthenic components in the carbon distribution by ring analysis C _N is less than 35%, and the paraffin component nonvolatile mineral oil content C _P is 50% or less of carbon, The W / O emulsion ink for stencil printing according to claim 1, 2 or 3, which is contained alone or in combination with another oil.