JP4851701B2 - Emulsion ink for stencil printing - Google Patents

Description

  The present invention relates to a water-in-oil type (W / O type) emulsion ink for stencil printing having excellent fixability and good storage stability.

  As is well known, a stencil printing method uses a stencil printing paper (stencil) having a perforated portion, and moves the ink from one side of the stencil to the other side through the perforated portion of the stencil, so that the paper This is a method for printing on the surface of a substrate. This stencil printing method is usually a water-in-oil type (W / O type) containing a volatile solvent, a non-volatile solvent, a resin, a colorant, a surfactant, water, an antifreezing agent, an electrolyte, and a preservative. The emulsion ink is used.

As a method for improving fixability and storage stability in the emulsion ink, for example, an emulsion ink containing a resin having at least one of a phenolic or alcoholic hydroxyl group and a gelling agent for the resin has been proposed (Patent Document). 1). In addition, an emulsion ink containing an expensive dispersant such as an aluminum chelate for enhancing the dispersibility of the pigment has been proposed (see Patent Document 2).
However, these conventional techniques are not yet satisfactory in terms of both fixability and storage stability, and further, since expensive additives are used, there is a problem that the manufacturing cost increases.

  Therefore, an excellent water-in-oil type (W / O type) emulsion ink for stencil printing having excellent fixability and storage stability has not yet been obtained, and its rapid provision is desired. is the current situation.

Japanese Patent No. 3008724 Japanese Patent No. 2926455

  This invention is made | formed in view of this present condition, and makes it a subject to solve the said various problems in the past and to achieve the following objectives. That is, an object of the present invention is to provide an inexpensive water-in-oil (W / O type) emulsion ink for stencil printing, which has excellent fixability and good storage stability.

  As a result of intensive studies by the inventor in order to solve the above problems, the following knowledge has been obtained. That is, it comprises 10 to 90% by mass of an oil phase and 90 to 10% by mass of an aqueous phase. In the aqueous phase, 2-alkyl-4-isothiazolin-3-one (wherein the alkyl moiety has 2 or more carbon atoms) And the presence of a polyhydric alcohol is a finding that a water-in-oil type (W / O type) emulsion ink for stencil printing having excellent fixability and good storage stability can be obtained.

The present invention is based on the above knowledge of the present inventor, and means for solving the above problems are as follows. That is,
<1> 2-alkyl-4-isothiazolin-3-one comprising 10 to 90% by mass of an oil phase and 90 to 10% by mass of an aqueous phase, and represented by the following structural formula (1) in the aqueous phase; And an emulsion ink for stencil printing, comprising a polyhydric alcohol.
However, in the structural formula (1), R represents an alkyl group having 2 or more carbon atoms.

In the emulsion ink for stencil printing of the present invention, the aqueous phase contains 2-alkyl-4-isothiazolin-3-one represented by the structural formula (1). The 2-alkyl-4-isothiazolin-3-one has a large surface tension reducing ability and can increase the penetrating power of the colorant in the emulsion ink for stencil printing to the paper, thereby improving the fixability. The Also, since the surface tension of the aqueous phase emulsion is lowered by lowering the surface tension of the aqueous phase to approach the low surface tension of the oil phase, a more stable emulsion ink can be produced. Furthermore, 2-alkyl-4-isothiazolin-3-one is used as an isothiazolone antibacterial agent, and this antibacterial action is also involved in improving the stability of the emulsion. And since said 2-alkyl-4-isothiazolin-3-one is hardly soluble in water, it is effective to use a polyhydric alcohol as a dissolution aid together.
<2> The emulsion ink for stencil printing according to <1>, wherein 2-alkyl-4-isothiazolin-3-one is 2-N-octyl-4-isothiazolin-3-one.
<3> The emulsion ink for stencil printing according to <1>, wherein the content of 2-alkyl-4-isothiazolin-3-one in the aqueous phase is 0.005 to 0.1% by mass.

  <4> The emulsion ink for stencil printing according to any one of <1> to <2>, wherein the aqueous phase contains polyvinylpyrrolidone. In the emulsion ink for stencil printing according to <4>, by adding polyvinyl pyrrolidone in the aqueous phase, the ink film for forming an image can be strengthened by the film forming performance of the polyvinyl pyrrolidone, and fixing It can contribute to the improvement of sex.

  According to the present invention, water-in-oil type (W / O type) emulsion inks for stencil printing, which can solve various problems in the past, have excellent fixability and good storage stability, can be provided.

  The emulsion ink for stencil printing of the present invention comprises 10 to 90% by mass of an oil phase and 90 to 10% by mass of an aqueous phase, and 2-alkyl-4-isothiazolin-3-one (provided that alkyl) The carbon number of the portion is 2 or more) and a polyhydric alcohol, and further contains other components as necessary.

In this case, the emulsion ink for stencil printing contains 10 to 90% by mass of an oil phase and 90 to 10% by mass of an aqueous phase, preferably 20 to 50% by mass of an oil phase and 50 to 80% by mass of an aqueous phase.
If the mixing ratio of the oil phase is less than 10% by mass, it may not be possible to take the form of a W / O emulsion, and if it exceeds 90% by mass, the physical properties of the W / O emulsion are insufficiently effective. May end up.

<Water phase>
The aqueous phase contains 2-alkyl-4-isothiazolin-3-one (wherein the alkyl moiety has 2 or more carbon atoms), a polyhydric alcohol, polyvinylpyrrolidone, and other water-soluble polymer compounds. , Water and, if necessary, other components such as an evaporation inhibitor or antifreezing agent for water, an electrolyte, an O / W resin emulsion, an antiseptic / antifungal agent, and a pH adjuster.

-2-alkyl-4-isothiazolin-3-one-
The 2-alkyl-4-isothiazolin-3-one is represented by the following structural formula (1).

In the structural formula (1), R is preferably an alkyl group having 2 or more carbon atoms, particularly 6 to 10 carbon atoms.
The alkyl group is not particularly limited and may be appropriately selected depending on the intended purpose.For example, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, a pentyl group, a neopentyl group, A hexyl group, a cyclohexyl group, an octyl group, a nonyl group, a decyl group, etc. are mentioned, Among these, an octyl group is preferable at the point with the following high effects.

  The 2-alkyl-4-isothiazolin-3-one (wherein the alkyl moiety has 2 or more carbon atoms) has a large surface tension reducing ability, and the penetrating power of the colorant in the emulsion ink for stencil printing to paper. Can be increased. As a result, the fixability is improved. Further, the 2-alkyl-4-isothiazolin-3-one reduces the surface tension of the aqueous phase to approach the low surface tension of the oil phase and lowers the interfacial energy of the aqueous phase emulsion. Can be manufactured. Furthermore, the 2-alkyl-4-isothiazolin-3-one is used as an isothiazolone antibacterial agent, and this antibacterial action is also considered to contribute to the improvement of emulsion stability.

  The content of the 2-alkyl-4-isothiazolin-3-one (wherein the alkyl moiety has 2 or more carbon atoms) in the aqueous phase is preferably 0.005 to 0.1% by mass, -0.07 mass% is more preferable. If the content is less than 0.05% by mass, the sustainability of the addition effect may be reduced, and even if added in excess of 0.1% by mass, it is not sufficient in terms of fixability and ink stability. The above effects cannot be obtained, and the cost may be increased.

  Since the 2-alkyl-4-isothiazolin-3-one is hardly soluble in water, the 2-alkyl-4-isothiazolin-3-one is used after being dissolved in a polyhydric alcohol as a dissolution aid and diluted with water, an additive or the like.

-Polyhydric alcohol-
As described above, the polyhydric alcohol is used as a dissolution aid in the aqueous phase of the 2-alkyl-4-isothiazolin-3-one (wherein the alkyl moiety has 2 or more carbon atoms).
The polyhydric alcohol is not particularly limited and may be appropriately selected depending on the intended purpose.For example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, glycerin, Examples include trimethylolpropane, neopentyl glycol, diglycerin, triglycerin, pentaerythlit, dipentaerythlit, mannit, and sorbit. These may be used individually by 1 type and may use 2 or more types together.

  0.5-20 mass% is preferable and, as for the addition amount in the said water phase of the said polyhydric alcohol, 3-15 mass% is more preferable. If the amount added is less than 0.5% by mass, it may be insufficient as a solubilizing agent for 2-N-octyl-4-isothiazolin-3-one, and even if added in excess of 20% by mass. Further effects as a solubilizing agent cannot be obtained, and on the contrary, the cost may increase.

-Polyvinylpyrrolidone-
There is no restriction | limiting in particular as said polyvinylpyrrolidone (PVP), It can select suitably from well-known things, A commercial item may be sufficient and what was synthesize | combined suitably may be sufficient. The film forming property of the polyvinyl pyrrolidone can contribute to improvement of fixing property.
As said polyvinylpyrrolidone (PVP), what is represented by following Structural formula (2) can be used suitably, for example.

However, in said structural formula (2), n represents a polymerization degree.

  The polyvinyl pyrrolidone preferably has a K value of 15-30. Here, the K value means a numerical value serving as a standard for the average molecular weight, the degree of polymerization, and the intrinsic viscosity of polyvinylpyrrolidone. When the K value exceeds 30, the viscosity of the aqueous phase to which polyvinyl pyrrolidone is added becomes too high, and the ink viscosity becomes high, which inhibits the suction of ink from the ink pack and the penetration into the paper during printing. There is.

The K value can be derived from the measured value of the polyvinyl pyrrolidone viscosity, and can be calculated based on the Fikenscher formula of the following formula 1.
<Formula 1>
However, in the said Numerical formula 1, c represents the density | concentration in a g / 100ml solution. ηrel represents the viscosity of the solution compared to the solvent.

  The addition amount of the polyvinylpyrrolidone in the aqueous phase is preferably 0.5 to 6.0% by mass in terms of solid concentration. When the addition amount is less than 0.5% by mass, the effect on the fixing property and storage stability may be insufficient, and even if the addition amount exceeds 6.0% by mass, no further effect is obtained. On the other hand, the cost may increase.

  In addition to the polyvinyl pyrrolidone, other water-soluble polymer compounds can be added to the aqueous phase as necessary. There is no restriction | limiting in particular as this other water-soluble high molecular compound, According to the objective, it can select suitably, For example, a natural high molecular compound, a semi-synthetic high molecular compound, a synthetic high molecular compound etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together.

Examples of the natural polymer compound include starch, mannan, sodium alginate, galactan, tragacanth gum, gum arabic, pullulan, dextran, xanthan gum, glue, gelatin, collagen, casein and the like.
Examples of the semi-synthetic polymer compound include carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, hydroxymethyl starch, carboxymethyl starch, and dialdehyde starch.
Examples of the synthetic polymer compound include acrylic acid resin derivatives such as polyacrylic acid, sodium polyacrylate, and triethanolamine polyacrylate; synthetic polymer compounds such as polyvinyl alcohol, polyacrylamide, polyethylene oxide, and polyvinyl methyl ether. Etc.

  If it is clean, there will be no restriction | limiting in particular if it is clean, According to the objective, it can select suitably, For example, a tap water, ion-exchange water, distilled water etc. can be used.

The water evaporation inhibitor or antifreeze agent is not particularly limited and may be appropriately selected from known ones. Examples thereof include lower saturated monohydric alcohols, glycols and polyhydric alcohols. . These may be used individually by 1 type and may use 2 or more types together.
Examples of the lower saturated monohydric alcohol include methanol, ethanol, isopropanol, butanol, isobutanol and the like. Examples of the glycol include ethylene glycol, diethylene glycol, and propylene glycol. Examples of the polyhydric alcohol include glycerin and sorbitol.
Among these, the effect of suppressing the deterioration of the ink with time due to volatilization of the aqueous phase and the effect of stabilizing the emulsion, while maintaining the effect of the alkyd resin against the stains of the roller, the ink of the ink when left in the drum for a long time is maintained. Glycerin is particularly preferable in that the alteration can be reduced.
The amount of the water evaporation inhibitor or antifreezing agent added to the aqueous phase is, for example, preferably 15% by mass or less, and more preferably 4-12% by mass.

The electrolyte is added to increase the stability of the emulsion, and it is preferable to add an electrolyte composed of ions having a high liquid separation permutation effective for improving the stability of the emulsion. Anions having a high liquid separation permutation are citrate ions, tartaric acid ions, sulfate ions, acetate ions, and the like. Cations having a high liquid separation permutation are alkali metal ions and alkaline earth metal ions. The electrolyte added here is preferably a salt in which at least one of an anion and a cation is composed of the above ions, such as magnesium sulfate, sodium sulfate, sodium citrate, sodium hydrogen phosphate, sodium borate, sodium acetate, etc. Is mentioned. Among these, a divalent anion-containing compound is preferable, and magnesium sulfate is particularly preferable. These may be used individually by 1 type and may use 2 or more types together.
The amount of the electrolyte added in the aqueous phase is, for example, preferably 0.1 to 2% by mass, and more preferably 0.5 to 1.5% by mass.

The oil-in-water (O / W) resin emulsion is not particularly limited and may be appropriately selected from known ones, and may be a synthetic polymer compound or a natural polymer compound. Examples of the synthetic polymer compound include vinyl acetate resin, acrylic ester resin, methacrylic ester resin, vinyl chloride resin, ethylene-vinyl acetate copolymer, vinyl acetate-acrylic ester copolymer, styrene-acrylic acid. Examples thereof include ester copolymers, vinylidene chloride-acrylic acid ester copolymers, vinyl chloride-vinyl acetate copolymers, and urethane resins. Examples of the natural polymer compound include a polymer compound that can be added to an oil phase commonly used in emulsion inks for stencil printing. These may be used individually by 1 type and may use 2 or more types together.
Further, the dispersion method of the oil-in-water resin emulsion is not particularly limited, and a dispersant, a protective colloid, and a surfactant may be added, or may be synthesized by soap-free emulsion polymerization. There is no restriction | limiting in particular in the minimum film forming temperature of the said oil-in-water resin emulsion, According to the objective, it can select suitably, 40 degrees C or less is preferable.

The antiseptic / antifungal agent is added to prevent bacteria and fungi from growing in the emulsion, and is effective when the emulsion is stored for a long period of time. The antiseptic / antifungal agent is not particularly limited and may be appropriately selected from known ones. Examples include salicylic acid, phenols, methyl p-oxybenzoate, ethyl p-oxybenzoate, and the like. Aromatic hydroxy compounds or chlorinated compounds thereof, sorbic acid, dehydroacetic acid and the like, and these may be used alone or in combination of two or more.
The amount of the antiseptic / antifungal agent added to the aqueous phase is preferably 3% by mass or less, and more preferably 0.1 to 1.2% by mass.

  There is no restriction | limiting in particular as said pH adjuster, Although it can select and use suitably from well-known things, For example, a triethanolamine, sodium acetate, a triamylamine etc. are mentioned suitably. These pH adjusters can be added as necessary to maintain the pH of the aqueous phase at 6-8. If the pH of the aqueous phase deviates from the above range, the effect may be impaired when a water-soluble polymer compound is added.

<Oil phase>
There is no restriction | limiting in particular as said oil phase, According to the objective, it can select suitably, Other components, such as a coloring agent, a coloring agent dispersing agent, resin, antioxidant, an emulsifier, vegetable oil, mineral oil, extender, etc. It contains.

-Colorant-
The colorant can be added to both the aqueous phase and the oil phase.
As the colorant, known pigments of various colors, disperse dyes and the like can be used, and among these, pigments are particularly preferable. Examples of the colorant include carbon blacks such as acetylene black, channel black, and furnace black; metal powders such as aluminum powder and bronze powder; inorganic pigments such as petals, yellow lead, ultramarine blue, chromium oxide, and titanium oxide; Azo pigments such as insoluble azo pigments, azo lake pigments, condensed azo pigments; phthalocyanine pigments such as metal-free phthalocyanine pigments and copper phthalocyanine pigments; anthraquinone pigments, quinacridone pigments, isoindolinone pigments, isoindoline pigments, dioxane Gin dyes, selenium dyes, perylene dyes, perinone dyes, thioindigo dyes, quinophthalone dyes, condensed polycyclic pigments such as metal complexes; acid or basic dye lakes and other organic pigments; diazo dyes, anthraquinones Oil-soluble dyes such as dyes; fluorescent pigments, etc. Is, it may be used alone or in combination of two or more thereof.

  As the fluorescent pigment, a so-called synthetic resin solid solution obtained by dissolving or dyeing a fluorescent dye that develops various hues after bulk polymerization of a synthetic resin or by pulverizing and refining the obtained colored bulk resin Examples of synthetic resins that carry dyes include melamine resins, urea resins, sulfonamide resins, alkyd resins, and polyvinyl chloride resins.

  When carbon black as the colorant is added to the oil phase, acidic carbon black having a pH of less than 5 is preferred. On the other hand, when carbon black is added to the aqueous phase, the pH of the carbon black is preferably 5 or more, more preferably 6 to 10, and even more preferably 7 to 9. A commercial item can be used as said carbon black, for example, MA-100, MA-7, MA-77, MA-11, # 40, # 44 (all are Mitsubishi Chemical Corporation make), Raven1100, Raven1080. , Raven 1255, Raven 760, Raven 410 (all manufactured by Colombian Carbon Co., etc.).

The average particle diameter of the insoluble colorant is preferably 0.01 to 1.0 μm, and more preferably 0.01 to 0.5 μm.
There is no restriction | limiting in particular in the addition amount in the emulsion ink for stencil printing of the said coloring agent, According to the objective, it can select suitably, Usually, 2-15 mass% is preferable.

-Colorant dispersant-
The colorant dispersant is not particularly limited as long as it does not inhibit the formation of the emulsion, and can be appropriately selected depending on the purpose. For example, the nonionic surfactant for an emulsifier described later, an alkylamine-based polymer Molecular compound, aluminum chelate compound, styrene-maleic anhydride copolymer, partial alkyl ester of polyacrylic acid, polyalkylene polyamine, aliphatic polyvalent carboxylic acid, polyether, ester type anionic surfactant, high molecular weight polycarboxylic acid Long chain amine salts, polyamide compounds, phosphate ester surfactants, alkyl sulfocarboxylates, α-olefin sulfonates, dioctyl sulfosuccinates, polyethylenimine, alkylolamine salts, inhibits ink storage stability Ionic surfactant, amphoteric interface if not Well as sexual agents may be used, these may be used alone or in combination of two or more thereof.
Among these, the aluminum chelate compound is more effective for stains due to the dispersibility of the pigment (the synergistic effect of the adsorption effect of the aluminum chelate compound and the steric hindrance effect of the polyglycerin fatty acid ester compound). And at least one selected from polyglycerin fatty acid ester compounds are preferred.

  There is no restriction | limiting in particular in the addition amount of the said coloring agent dispersing agent, According to the objective, it can select suitably, 40 mass% or less of the total mass of a coloring agent is preferable, and 2-35 mass% is more preferable.

-Resin-
The resin is not particularly limited and may be appropriately selected from known ones according to the purpose. For example, alkyd resin, rosin; polymerized rosin, hydrogenated rosin, rosin ester, rosin polyester resin, hydrogenated rosin Rosin resins such as esters; Rosin-modified alkyd resins, rosin-modified maleic resins, rosin-modified resins such as rosin-modified phenol resins; maleic resins; phenol resins; petroleum resins; rubber derivative resins such as cyclized rubbers; Polymerized castor oil and the like can be mentioned, and these may be used alone or in combination of two or more. Among these, alkyd resins are particularly preferable.

The weight average molecular weight of the resin is preferably 30,000 to 150,000, more preferably 55,000 to 150,000, from the viewpoint of fixability and printability. These resins are preferably resins having a solubility of 1 g / g or more (1 g or more of No. 0 solvent is compatible with 1 g of resin) having solubility in the Nisseki No. 0 solvent. Moreover, the addition amount of the resin in the oil phase is preferably 2 to 50% by mass and more preferably 5 to 20% by mass from the viewpoint of the cost of the ink and printing suitability.
When the weight average molecular weight of the resin is low and when the addition amount is small, the effect on fixability may be small, while when the weight average molecular weight is too high or the addition amount of the resin is large, the ink In some cases, the viscosity becomes high, and printability problems such as ink leakage from the rear end of the drum may occur.

The alkyd resin has an acid value of 15 or less, and more preferably 10 or less. Further, the iodine value is preferably 80 or less, and more preferably 80 to 110. Moreover, the oil length of the said alkyd resin is represented by the mass% in resin when the fatty acid in the said fats and oils exists with a triglyceride, and 60-90 mass% is preferable normally. The weight average molecular weight of the alkyd resin is preferably 30,000 or less, and more preferably 10,000 or less.
Here, the acid value of the alkyd resin can be measured, for example, according to JIS K0070. The iodine value of the alkyd resin can be measured, for example, according to JIS K0070.

The alkyd resin is not particularly limited as long as it satisfies the above physical properties, and can be appropriately selected according to the purpose. Usually, the alkyd resin contains an oil, a polybasic acid, and a polyhydric alcohol. Examples of the fats and oils include coconut oil, palm oil, olive oil, castor oil, rice bran oil, cottonseed oil, soybean oil, linseed oil, and tung oil. Among these, soybean oil is particularly preferable. As the polybasic acid, either a saturated polybasic acid or an unsaturated polybasic acid can be used. Examples of the saturated polybasic acid include phthalic anhydride, isophthalic acid, terephthalic acid, succinic acid, adipic acid, sebacic acid, tetrahydrophthalic acid and the like. Examples of the unsaturated polybasic acid include maleic acid, maleic anhydride, fumaric acid, itaconic acid, citraconic anhydride, and the like.
Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, glycerin, trimethylolpropane, neopentyl glycol, diglycerin, triglycerin, and pentaerythritol. Examples include slits, dipentaery slits, mannits, and sorbits.

-Antioxidant-
The antioxidant is not particularly limited and can be appropriately selected from known ones. For example, nordihydroguaiaretic acid (NDGA), citrate ester, extracted tocopherol, tocopherol, butylhydroxytoluene , Gallic acid, dibutylhydroxytoluene, propyl gallate, butylhydroxyanisole, sulfites, thiosulfate, ascorbic acid, ascorbate, ascorbic acid derivatives and the like, and these may be used alone. Two or more kinds may be used in combination.
The amount of the antioxidant added in the oil phase is preferably 2% by mass or less, and more preferably 0.1 to 1.0% by mass.

-Emulsifier-
The emulsifier is not particularly limited as long as it can form a water-in-oil emulsion and can be appropriately selected according to the purpose. Examples of the nonionic surfactant include sorbitan fatty acid ester and glycerin. Fatty acid ester, polyglycerin fatty acid ester, propylene glycol fatty acid ester, pentaerythritol fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbit fatty acid ester, polyoxyethylene glycerin fatty acid ester, polyethylene glycol fatty acid ester, polyoxyethylene alkyl ether, Polyoxyethylene phytosterol ether, polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene alkylphenyl ether, Reoxyethylene castor oil, polyoxyethylene hydrogenated castor oil, polyoxyethylene lanolin derivatives, polyoxyethylene alkylamines, polyoxyethylene fatty acid amides, polyoxyethylene alkylphenyl formaldehyde condensates, and the like. You may use, and may use 2 or more types together.

  There is no restriction | limiting in particular in the addition amount in the said emulsion ink for stencil printing of the said emulsifier, According to the objective, it can select suitably, 0.5-15 mass% is preferable, and 2-8 mass% is more preferable.

-Vegetable oil-
The vegetable oil is not particularly limited and can be appropriately selected from known ones according to the purpose.For example, soybean oil, corn oil, sunflower oil, rapeseed oil, safflower oil, sesame oil, castor oil, dehydrated castor oil, Camellia oil, olive oil, palm oil, rice oil, cottonseed oil, palm oil, bonito oil, palm kernel oil, tung oil, camelia oil, grape seed oil, sweet almond oil, pistachio nut oil, jojoba oil, macadamia nut oil, Meadow home oil and the like can be mentioned, and these may be used alone or in combination of two or more.
Examples of the esterified vegetable oil include those obtained by esterifying the vegetable oil. Examples of the ester include methyl ester, ethyl ester, and butyl ester. As the esterified vegetable oil, for example, esterified soybean oil is particularly preferable.
By using soybean oil fatty acid alkyd resin whose fat is soybean oil as the alkyd resin and using esterified soybean oil, the total of soybean oil-derived components exceeds 6%. Certification can be obtained, which is also advantageous in terms of safety.

  The amount of vegetable oil added to the emulsion ink for stencil printing is preferably 1 to 35% by mass, and more preferably 5 to 25% by mass.

-Mineral oil-
The mineral oil is not particularly limited and can be appropriately selected according to the purpose. For example, paraffinic oil, naphthenic oil, petroleum solvent, spindle oil, liquid paraffin, light oil, kerosene, machine oil, gear Oils, lubricating oils, motor oils and the like can be mentioned. Among these, paraffinic oils, naphthenic oils, and petroleum solvents are particularly preferable.
Commercially available products can be used as the paraffinic oil, for example, Gargo Oil Arctic series manufactured by Mobil Oil Co., Nippon Oil Super Oil Series manufactured by Nippon Oil Corporation, Diana Process Oil manufactured by Idemitsu Kosan Co., Ltd. And Diana Fresia series.
The naphthenic oil has a naphthene component carbon content (CN) of 30% or more by ring analysis, an aromatic component carbon content (CA) of 20% or less, and a paraffin component carbon content. A quantity (CP) of 55% or less is suitable, for example, Gargo Oil Arctic Oil 155 and 300ID manufactured by Mobil Oil, Gargo Oil Arctic Oil Light, Gargo Oil Arctic Oil C Heavy; The company's Diana Process Oil, Diana Fresia Series; Nippon San Oil Co., Ltd.
Commercially available products can be used as the petroleum-based solvent, for example, Isopar series (C, E, G, H, L, M, etc.) and Exol (D30, D40, D80, D110, manufactured by Exxon Chemical Co., Ltd.) D130 etc.); AF solvent series (No. 4, No. 5, No. 6, No. 7, etc.) manufactured by Nippon Oil Corporation.

When considering the stability of the ink, these mineral oils preferably use those having a polycyclic aromatic component that is an aromatic hydrocarbon containing three or more condensed aromatic rings of less than 3% by mass. . Further, the mutagenicity index (MI) is less than 1.0, the aroma content (% C _A ) is 20 to 55%, the aniline point is 100 ° C. or less, and benzo [a] anthracene based on the total mass of the oil, The content of polycyclic aromatics such as benzo [b] fluoranthene, benzo [j] fluoranthene, benzo [k] fluoranthene, benzo [a] pyrene, dibenzo [a, j] acridine is 10 ppm or less and total content The amount is 50 ppm or less.
Note that a highly safe aroma oil (for example, JP-A-11-80640) can be used as necessary.

  There is no restriction | limiting in particular in the addition amount in the said emulsion ink for stencil printing of the said mineral oil, According to the objective, it can select suitably, 1-35 mass% is preferable and 5-25 mass% is more preferable.

-Gelling agent-
The gelling agent has a role of improving the storage stability, fixability, fluidity, etc. of the ink by gelling the resin contained in the oil phase, and is preferably a compound that coordinates with the resin in the oil phase. . Examples of the gelling agent include organic acid salts containing organic metals such as Li, Na, K, Al, Ca, Co, Fe, Mn, Mg, Pb, Zn, and Zr, organic chelate compounds, and metal soap oligomers. Can be mentioned. Specifically, octylic acid metal salts such as aluminum octylate, naphthenic acid metal salts such as manganese naphthenate, stearates such as zinc stearate, organic chelate compounds such as aluminum diisopropoxide monoethyl acetoacetate, etc. Can be mentioned. These may be used individually by 1 type and may use 2 or more types together.

  There is no restriction | limiting in particular in the addition amount of the said gelatinizer, According to the objective, it can select suitably, 15 mass% or less is preferable with respect to the total amount of resin in an oil phase, and 5-10 mass% is more preferable.

-Extender pigment-
The extender pigment can be added to the oil phase, the aqueous phase, or both phases for preventing bleeding and adjusting the viscosity in the ink, and either inorganic fine particles or organic fine particles are preferable. Examples of the inorganic fine particles include clay, silica, talc, clay, calcium carbonate, barium sulfate, titanium oxide, alumina white, diatomaceous earth, kaolin, mica, and aluminum hydroxide. Examples of the organic fine particles include polyacrylate resin, polyurethane resin, polyester resin, polyethylene resin, polypropylene resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polysiloxane resin, phenol resin, epoxy resin, or these A copolymer, and the like.
There is no restriction | limiting in particular in the addition amount in the said emulsion ink for stencil printing of the said extender, According to the objective, it can select suitably, 0.1-50 mass% is preferable, and 1-5 mass% is more preferable.

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

The method for producing the emulsion ink for stencil printing of the present invention is not particularly limited and can be appropriately selected from known methods according to the purpose. For example, the oil phase and the aqueous phase liquid are previously prepared by a conventional method. It can be prepared by separately preparing, adding an aqueous phase to the oil phase, and emulsifying in a known emulsifier such as a disper mixer, a homomixer, or a high-pressure homogenizer.
Specifically, a colorant, a solvent, and an emulsifier were mixed and stirred with a high-speed dissolver. Thereafter, a dispersion treatment is performed using a bead mill to prepare an oil phase. On the other hand, a polyhydric alcohol and 2-alkyl-4-isothiazolin-3-one (wherein the alkyl moiety has 2 or more carbon atoms) are mixed, and this mixed solution is well dissolved in water to prepare an aqueous phase. To do. Next, an emulsion ink for stencil printing can be produced by using an emulsifier and gradually adding and emulsifying the aqueous phase liquid while charging the oil phase liquid and stirring the liquid.

The emulsion ink for stencil printing of the present invention preferably has a viscosity of 3 to 40 Pa · s, more preferably 10 to 30 Pa · s at a shear rate of 20 sec ⁻¹ .
As described above, the emulsion ink for stencil printing of the present invention has excellent fixability and good storage stability, and is suitably used for stencil printing by a rotary stencil printing machine.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

( Reference Example 1)
-Preparation of emulsion ink for stencil printing-
The oil phase liquid was mixed with a colorant, a solvent and an emulsifier having the following composition and stirred with a high-speed dissolver. Then, it prepared by performing a dispersion process using bead mill (LMZ2, Ashizawa Finetech Co., Ltd.).
The aqueous phase solution was prepared by mixing polyhydric alcohol and 2-N-octyl-4-isothiazolin-3-one and dissolving this mixture well in water.
Next, using the emulsifier (Nikko Chemicals Co., Ltd., Emulsification tester ET-3A type), the water phase liquid was gradually added while charging the oil phase liquid and stirring the liquid. Thus, the emulsion ink for stencil printing of Reference Example 1 was produced.

<Composition of oil phase>
Colorant (Channel Black): 6.00 parts by mass Solvent (# 30 motor oil): 19.00 parts by mass Emulsifier 1 (sorbitan sesquioleate): 4.00 parts by mass Emulsifier 2 (Sorbitan monooleate) 2.00 parts by mass <Composition of aqueous phase>
・ Water (ion-exchanged water): 64.95 parts by mass ・ Polyhydric alcohol (glycerin): 4.00 parts by mass ・ 2-N-octyl-4-isothiazolin-3-one: 0.05 Parts by mass

(Example 2)
-Preparation of emulsion ink for stencil printing-
In Reference Example 1, the emulsion ink for stencil printing of Example 2 was prepared in the same manner as in Reference Example 1, except that the composition of the oil phase and the aqueous phase was changed as shown below.

<Composition of oil phase>
Colorant (Channel Black): 6.00 parts by mass Solvent (# 30 motor oil): 19.00 parts by mass Emulsifier 1 (sorbitan sesquioleate): 4.00 parts by mass Emulsifier 2 (Sorbitan monooleate) 2.00 parts by mass <Composition of aqueous phase>
-Water (ion exchange water) ... 59.95 parts by mass-Polyhydric alcohol (glycerin) ... 4.00 parts by mass-2-N-octyl-4-isothiazolin-3-one ... 0.05 30 parts by mass Polyvinylpyrrolidone aqueous solution ... 5.00 parts by mass (solid content in aqueous phase: 2.2% by mass)

(Comparative Example 1)
-Preparation of emulsion ink for stencil printing-
In Reference Example 1, a stencil printing emulsion ink of Comparative Example 1 was prepared in the same manner as Reference Example 1, except that the composition of the oil phase and the aqueous phase was changed as shown below.

<Composition of oil phase>
Colorant (Channel Black): 6.00 parts by mass Solvent (# 30 motor oil): 19.00 parts by mass Emulsifier 1 (sorbitan sesquioleate): 4.00 parts by mass Emulsifier 2 (Polyoxyethylene sorbitan monooleate) 2.00 parts by mass <Composition of aqueous phase>
-Water (ion exchange water)-64.95 parts by mass-Polyhydric alcohol (glycerin)-4.00 parts by mass-2-Methyl-4-isothiazolin-3-one (preservative)-0 .05 parts by mass

(Comparative Example 2)
-Preparation of emulsion ink for stencil printing-
In Reference Example 1, a stencil printing emulsion ink of Comparative Example 2 was prepared in the same manner as Reference Example 1, except that the composition of the oil phase and the aqueous phase was changed as shown below.

<Composition of oil phase>
-Colorant (Channel Black)-6.00 parts by mass-Solvent (# 30 motor oil)-19.00 parts-Emulsifier 1 (sorbitan sesquioleate)-4.00 parts by mass-Emulsifier 2 ( Polyoxyethylene sorbitan monooleate) ... 2.00 parts by mass <Composition of aqueous phase>
・ Water (ion exchange water) ・ ・ ・ 65.00 mass parts ・ Polyhydric alcohol (glycerin) ・ ・ ・ 4.00 parts

  Next, the obtained emulsion ink for stencil printing was evaluated for fixability and storage stability as follows. The results are shown in Table 1.

<Evaluation of fixability>
Each emulsion ink for stencil printing obtained, Saterio A400 - using (Co. Rico Ltd.), and plate making in a document having a solid area 100 cm ^2, was printed quality paper 55K, 30 sheets. At that time, the 30th solid portion of the printed image was measured with a reflective optical densitometer (RD914, manufactured by Macbeth Co., Ltd.), and the ID of 9 solid portions was measured, and the average value was defined as the image density before rubbing.
Further, after measuring the image density, the ID measured image surface was rubbed back and forth 10 times with a clock meter equipped with an eraser, and after rubbing, the ID of 9 solid portions was measured in the same manner, and the average value was taken as the image density after rubbing. .
From the obtained image density results before and after rubbing, the fixing rate was calculated by the following formula 1.
<Formula 1>
Fixing rate (%) = (image density after rubbing / image density before rubbing) × 100

<Evaluation of storage stability>
Each emulsion ink for stencil printing was placed in a sealed container and left in a thermostatic bath at 50 ° C. for 1 month, and the separation and alteration of the ink components due to the standing were visually observed and evaluated according to the following criteria.
〔Evaluation criteria〕
○: Ink separation or alteration is not observed.
Δ: Oil or water oozes from the ink.
X: The ink component is completely separated.

From the results of Table 1, Comparative Example 1 shows that 2-N-octyl-4-isothiazoline-3-
2-methyl-4-isothiazoline-3 in which the alkyl moiety has one carbon instead of on
-Due to the inclusion of ON, the fixing rate is low and the storage stability is slightly inferior. Comparative Example 2 is 2
Since -N-octyl-4-isothiazolin-3-one is not contained, the fixing rate is low and the storage stability is poor.
In contrast, Reference Example 1 and Example 2 containing 2-N-octyl-4-isothiazolin-3-one and polyhydric alcohol in the aqueous phase have a higher fixing rate than Comparative Examples 1 and 2. It was confirmed that the storage stability was good. Furthermore, it can be seen that Example 2 in which polyvinylpyrrolidone was added to the aqueous phase further improved the fixability.

Since the emulsion ink for stencil printing of the present invention has excellent fixing properties and good storage stability, it is suitably used for stencil printing by a rotary stencil printing machine.

Claims (3)

2-alkyl-4-isothiazolin-3-one represented by the following structural formula (1) in the aqueous phase, comprising 10 to 90% by mass of the oil phase and 90 to 10% by mass of the aqueous phase, and polyvalent An emulsion ink for stencil printing comprising alcohol and polyvinylpyrrolidone in the aqueous phase .

However, in the structural formula (1), R represents an alkyl group having 2 or more carbon atoms. The emulsion ink for stencil printing according to claim 1, wherein 2-alkyl-4-isothiazolin-3-one is 2-N-octyl-4-isothiazolin-3-one. The content of 2-alkyl-4-isothiazolin-3-one in the aqueous phase is 0.005 to
The emulsion ink for stencil printing according to claim 1, wherein the emulsion ink is 0.1% by mass.