JP2007224079A - O/w emulsion ink for stencil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an O/W emulsion ink for a stencil excellent in water resistance after image formation, stability on a stencil printing machine and image resettability after leaving the machine to stand, and having high safety to an environment and a human organism. <P>SOLUTION: This O/W emulsion ink comprises an oil phase and an aqueous phase wherein the oil phase contains a coloring material. It is preferred that the aqueous phase contains an unsaturated carboxylic acid type water soluble polymer and its salt, a chelating agent and a humectant properly. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is an O / W type for stencil printing that has excellent water resistance after image formation, stability on a stencil printing machine, and excellent image restoration after being left on the printing press, and is highly safe for the environment and the human body. (Oil-in-water type) Emulsion ink.

  Ink used in conventional stencil printing uses a W / O type (water-in-oil) emulsion from the viewpoints of matching with stencil printing machines, image quality, and environmental considerations. Therefore, vegetable oils such as soybean oil have been used as the oil in the oil phase in the W / O emulsion ink.

In recent years, water-based inks tend to be required from the viewpoint of further safety to the environment and the human body, but water-based inks are more resistant to water and stencil printing after image formation than the W / O emulsion inks. There are problems such as stability on the press and image recoverability after leaving the press.
In a system in which a colorant is dispersed in water, such as water-based ink, water resistance after image formation is inferior, and there may be a problem that an image is blurred by water or a water-based pen.
In addition, the water-based ink is inferior in stability on a stencil printing machine, and the following problems may occur. Ink for stencil printing needs to maintain shape retention (yield value) on the ink roller, but in the case of water-based ink, shape retention cannot be maintained. It may leak out and may contaminate the rotating mechanism part beside the ink roller, or it may ooze out from the drum plate cylinder and cause stains on the non-image part of the image. In addition, the ink for stencil printing needs to maintain a certain yield value even when the ink is stored in a container such as a pack, but in the case of water-based ink, the yield value cannot be maintained and the ink It may hang down from the pack mouth and adhere to the floor or hands and become dirty.
In addition, after printing, water-based ink on ink rollers, screens, plate cylinders, etc. evaporates moisture, reduces the amount of ink, increases solid content concentration, increases viscosity, and prints after leaving the printing press. In this case, image restoration may be delayed or the screen may be clogged.

  Examples of the technology related to the water-based ink for stencil printing include, for example, an ink thickened with an acrylic acid derivative resin or the like (see Patent Document 1); water, β-thiodiglycol, and triethylene glycol; Ink containing 50% by mass or more (see Patent Document 2); ink containing an unsaturated carboxylic acid-based water-soluble polymer and triethylene glycol (see Patent Document 3); triethylene glycol and β-thiodiglycol An ink containing at least one of diethylene glycol and an unsaturated carboxylic acid-based water-soluble polymer (see Patent Document 4); a monovalent metal salt or amine salt of the unsaturated carboxylic acid-based water-soluble polymer; and ammonium of an alkali-soluble resin. Ink containing salt (see Patent Document 5); polyethylene having an average molecular weight in the range of 190 to 500 Ink containing at least one water-soluble organic solvent selected from lenglycol, polypropylene glycol having an average molecular weight in the range of 200 to 800, acetin, and the like (see Patent Document 6) has been proposed.

  However, the above proposal does not mention that it is excellent in water resistance after image formation, stability on a stencil printing machine, and image restoration after leaving the printing machine. In addition, the development of stencil printing inks that are excellent in the environment and highly safe for the environment and the human body is desired.

JP 2001-302955 A Japanese Patent No. 3639287 Japanese Patent No. 3639288 Japanese Patent No. 3639289 Japanese Patent No. 3639290 Japanese Patent No. 3673822

  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, the present invention is an O / W for stencil printing that is excellent in water resistance after image formation, stability on a stencil printing machine, and image restoration after being left on the printing press, and is highly safe for the environment and the human body. An object is to provide a type emulsion ink.

Means for solving the problems are as follows. That is,
<1> An O / W emulsion ink for stencil printing comprising an oil phase and an aqueous phase, wherein the oil phase contains a colorant.
The O / W type emulsion ink for stencil printing described in the above <1> comprises an oil phase and an aqueous phase, and contains a colorant in the oil phase. It is possible to improve the poor water resistance after image formation in the system dispersed in the resin. Moreover, the O / W type emulsion ink can improve the instability on the stencil printing machine of the water-based ink by containing the internal phase as an emulsion form. In other words, because the ink has a yield value, it has high shape retention on the ink roller, leakage to the side of the ink roller, contamination of the rotating mechanism side of the ink roller, seepage from the drum cylinder side, etc. Can be prevented. In addition, since the O / W emulsion ink contains an oil phase, it improves the delay in image restoration in printing after being left on the printing press due to the evaporation of water in the water-based ink and the decrease in the amount of ink mass. can do. The O / W emulsion ink is safe even when touched by the user because the continuous phase is water-based, and is excellent in environmental safety compared to the W / O emulsion ink.

<2> The water phase includes an unsaturated carboxylic acid-based water-soluble polymer and a base, and the unsaturated carboxylic acid-based water-soluble polymer is at least one kind of acrylic acid derivative resin. O / W emulsion ink for stencil printing.
The O / W type emulsion ink for stencil printing according to the above <2> is that the aqueous phase is thickened by containing an unsaturated carboxylic acid water-soluble polymer such as an acrylic acid derivative resin and a base. The stability on the stencil printing machine can be further improved. In other words, since the ink has a higher shape retention on the ink roller, leakage to the side of the ink roller, contamination of the rotating mechanism side of the ink roller, and seepage from the drum plate cylinder side are further prevented. Can do.

<3> Further, a chelating agent is contained in the aqueous phase, and the chelating agent contains citric acid, tartaric acid, malic acid, gluconic acid, succinic acid, ethylenediaminetetraacetic acid, hydroxyethylethylenediaminetriacetic acid, dihydroxyethylethylenediaminedioxide. At least one selected from the group consisting of acetic acid, propanediaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, nitrilotriacetic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, and aminotrimethylenephosphonic acid The O / W emulsion ink for stencil printing according to <2>.
The O / W type emulsion ink for stencil printing according to the above <3> has a specific chelating agent in the aqueous phase in addition to the unsaturated carboxylic acid-based water-soluble polymer and the base in the above <2>. Since it contains, especially the stability on the stencil printing machine after preservation | save of ink with time can be improved. The following factors can be considered as the reason why the stencil printing ink containing an unsaturated carboxylic acid-based water-soluble polymer and a base has a low viscosity with time due to storage in a container such as a pack. That is, the viscosity of the O / W emulsion ink for stencil printing in <2> is such that the unsaturated carboxylic acid water-soluble polymer is ionized by neutralization with a base, and the unsaturated carboxylic acid water-soluble polymer is A negative charge is generated along the polymer main chain, and the molecules in a coiled state are straightened by repulsion between the negative charges, and a thickened state is obtained. However, it is conceivable that the ink in the thickened state has a low viscosity due to the cation component of the salt in the ink crosslinking or precipitating the resin by being left or stored. Therefore, when a chelating agent as described above in <3> is further added to the O / W emulsion ink for stencil printing in <2>, the cation component of the salt in the ink is blocked, and the straightened state It is considered that the influence on the unsaturated carboxylic acid-based water-soluble polymer is reduced, and as a result, the thickened state can be maintained.

<4> The above <1> to <3, wherein the water phase contains a humectant, and the humectant is at least one selected from the group consisting of glycerin, xylitol, d-sorbitol, lactic acid, and urea. > The O / W emulsion ink for stencil printing according to any one of the above.
In the O / W emulsion ink for stencil printing described in <4>, the aqueous phase contains at least one humectant selected from the group consisting of glycerin, xylitol, d-sorbitol, lactic acid, and urea. Therefore, even if the O / W emulsion ink for stencil printing is left on an ink roller, a screen, a plate cylinder, etc., the amount of ink can be maintained by suppressing the water that evaporates. Also in printing, it is possible to further prevent a delay in the number of restored images.

  According to the present invention, conventional problems can be solved, water resistance after image formation, stability on a stencil printing machine, and excellent image recovery after leaving the printing machine, to the environment and the human body. A highly safe O / W emulsion ink for stencil printing can be provided.

(O / W emulsion ink for stencil printing)
The O / W type emulsion ink for stencil printing of the present invention (hereinafter sometimes referred to as “O / W type emulsion ink” or simply “ink”) includes an oil phase and an aqueous phase. Preferably, the water phase contains an unsaturated carboxylic acid-based water-soluble polymer and a base, a chelating agent, a humectant, and the oil phase or water as necessary. Each phase contains other components as appropriate.

<Content ratio of oil phase and water phase>
The content ratio of the oil phase and the aqueous phase in the O / W emulsion ink for stencil printing is not particularly limited and may be appropriately selected depending on the intended purpose. Preferably contains 10 to 90% by mass of the oil phase and 90 to 10% by mass of the aqueous phase, more preferably 20 to 80% by mass of the oil phase and 80 to 20% by mass of the aqueous phase. If the ratio of the oil phase is less than 10% by mass, the ink yield value may be low and the ink may not have sufficient shape retention. If the ratio exceeds 90% by mass, the mass ratio of the inner phase is too large. Emulsification may not work.

<Oil phase>
The oil phase contains at least a colorant, and further contains other components as necessary.

-Colorant-
There is no restriction | limiting in particular as said coloring agent, According to the objective, it can select suitably, For example, the well-known pigment, disperse dye, etc. of various color tones can be used. Specific examples of the colorant include, for example, carbon blacks such as acetylene black, channel black, and furnace black; metal powders such as aluminum powder and bronze powder; petals, yellow lead, ultramarine, chromium oxide, titanium oxide, and the like. Inorganic pigments; 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 pigments, quinacridone pigments, isoindolinone pigments, isoindoline pigments Condensed polycyclic pigments such as dyes, dioxazine dyes, selenium dyes, perylene dyes, perinone dyes, thioindigo dyes, quinophthalone dyes, metal complexes; organic pigments such as lakes of acidic or basic dyes; And oil-soluble dyes such as dyes and anthraquinone dyes That.

  The colorant is present in a dispersed state in the oil phase. There is no restriction | limiting in particular in the average particle diameter of the said coloring agent, Although it can select suitably according to the objective, 0.1-10 micrometers is preferable and 0.1-1 micrometer is more preferable. When the average particle size is less than 0.1 μm, a desired effect may not be obtained in the fixing rate and ink stability of the image related to the colorant particle size. When the average particle size exceeds 10 μm, the image is fixed. Rate and ink stability may be inferior.

The said colorant may be used individually by 1 type, and may use 2 or more types together.
Further, the content of the colorant is not particularly limited and may be appropriately selected according to the purpose. However, it is preferably 2 to 20% by mass, more preferably 3 to 15% by mass with respect to the total mass of the ink. . When the content is less than 2% by mass with respect to the total mass of the ink, the print density may be insufficient. When the content exceeds 20% by mass, the print density does not increase, which is disadvantageous in terms of cost. May be.

-Other components (oil phase)-
The other components in the oil phase are not particularly limited and may be appropriately selected depending on the purpose within a range not impairing the effects of the present invention. For example, oil components, resins, and dispersants for colorants , Gelling agents, antioxidants and the like.

-Oil component-
There is no restriction | limiting in particular as said oil component, According to the objective, it can select suitably, For example, well-known vegetable oil, mineral oil, etc. are mentioned. In addition, synthetic oil can be used as long as the effects of the present invention are not impaired. Among these, vegetable oil is preferable from the viewpoint of emphasizing the safety of ink, and esterified vegetable oil is particularly preferable as described later.

There is no restriction | limiting in particular as said vegetable oil, According to the objective, it can select suitably, For example, a soybean oil, a chrysanthemum oil, linseed oil, rapeseed oil, corn oil, sesame oil, tall oil, cottonseed oil, sunflower oil, safflower Oil, walnut oil, poppy oil, linseed oil, and the like. Among these, soybean oil is particularly preferable.
There is no restriction | limiting in particular as an iodine value of the said vegetable oil, Although it can select suitably according to the objective, It is preferable that it is 110-150. When the iodine value is within the preferable range, clogging of the screen and the plate cylinder caused by increase in viscosity due to oxidation of fatty acid can be suppressed.
In addition, as the vegetable oil, esterified vegetable oil can be used, and it is preferable in terms of safety and cost because it is unnecessary to use an antioxidant together. Examples of the ester include methyl ester, ethyl ester, and butyl ester.
The ester value of the esterified vegetable oil is preferably 80 to 260.
Moreover, it is preferable that melting | fusing point of the said esterified vegetable oil is less than 20 degreeC. If the melting point is less than 20 ° C., a good printed matter can be obtained even if printing is performed after ink storage at a low temperature.
The iodine value of the esterified vegetable oil is preferably 130 or less. When the iodine value exceeds 130, the ink tends to be easily dried.

  The mineral oil is not particularly limited and can be appropriately selected according to the purpose. For example, petroleum-based solvent, spindle oil, liquid paraffin, light oil, kerosene, machine oil, gear oil, lubricating oil, motor oil, etc. Is mentioned. As the petroleum solvent, for example, a mixed solvent such as Expar from Exxon or Nippon Oil Solvent from Nippon Petroleum may be used.

  The synthetic oil is not particularly limited and may be appropriately selected depending on the intended purpose. For example, polyisobutylenes, hydrogenated polydecenes, trimethylolpropane esters, neopentyl esters, pentaerythritol esters, siloxane , Silicones, fluorocarbons, alkyl-substituted diphenyl ethers, phthalates, phosphates, and the like.

The said oil component may be used individually by 1 type, and may use 2 or more types together.
There is no restriction | limiting in particular as content of the said oil component, Although it can select suitably according to the objective, 5-35 mass% is preferable with respect to the total mass of ink.
Among these, the oil component is soybean oil, and that the content of the soybean oil is 6% by mass or more based on the total mass of the ink satisfies the certification as a soybean oil ink of the American Soybean Association. In particular, it is preferable.

--Resin--
The resin is used, for example, for the purpose of fixing the colorant to the printing material, dispersing the colorant, and improving the temporal stability of the ink.
The resin is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include rosin; polymerized rosin, hydrogenated rosin, rosin ester, hydrogenated rosin ester and other rosin resins; rosin-modified phenolic resin and the like Rosin-modified resin; phenol resin; petroleum resin; alkyd resin; rubber derivative; polymerized castor oil;
The said resin may be used individually by 1 type, and may use 2 or more types together.
There is no restriction | limiting in particular as content of the said resin, Although it can select suitably according to the objective, It is preferable that it is 10 mass% or less with respect to the total mass of ink, and is 1-7 mass%. It is more preferable.

--Colorant dispersant--
The colorant dispersant is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include nonionic surfactants for emulsifiers, alkylamine polymer compounds, aluminum chelate compounds, styrene / anhydrous Maleic acid copolymer, Partial alkyl ester of polyacrylic acid, Polyalkylene polyamine, Aliphatic polycarboxylic acid, Polyether, Ester-type anionic surfactant, Long chain amine salt of high molecular weight polycarboxylic acid, Polyamide, Phosphate ester Surfactants, alkyl sulfocarboxylates, α-olefin sulfonates, dioctyl sulfosuccinates and the like.
The colorant dispersants may be used alone or in combination of two or more.
There is no restriction | limiting in particular as content of the dispersing agent of the said coloring agent, Although it can select suitably according to the objective, 40 mass% or less is preferable with respect to the mass of the said coloring agent, and 2-35 mass%. Is more preferable.

--Gelling agent--
The gelling agent is used for the purpose of improving the storage stability, fixability, fluidity, etc. of the ink by gelling the resin contained in the oil phase.
There is no restriction | limiting in particular as said gelatinizer, Although it can select suitably according to the objective, Among these, the compound which coordinates with the resin in the said oil phase is preferable. Examples of such compounds include organic acid salts containing 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. More specifically, metal octylates such as aluminum octylate, metal naphthenates such as manganese naphthenate, stearates such as zinc stearate, organic chelate compounds such as aluminum diisopropoxide monoethyl acetoacetate, etc. Is mentioned.
The said gelling agent may be used individually by 1 type, and may use 2 or more types together.
There is no restriction | limiting in particular as content of the said gelatinizer, Although it can select suitably according to the objective, 15 mass% or less is preferable with respect to the mass of the resin in the said oil phase, and 5-10 mass. % Is more preferable.

--Antioxidant--
The antioxidant is used for the purpose of preventing oxidation of the resin in the oil phase, thereby preventing an increase in ink viscosity.
There is no restriction | limiting in particular as said antioxidant, According to the objective, it can select suitably, For example, dibutylhydroxytoluene, propyl gallate, butylhydroxyanisole, etc. are mentioned.
The said antioxidant may be used individually by 1 type, and may use 2 or more types together.
There is no restriction | limiting in particular as content of the said antioxidant, Although it can select suitably according to the objective, 2 mass% or less is preferable with respect to the mass of the oil component in the said oil phase, 0.1% -1.0 mass% is more preferable.

<Water phase>
The aqueous phase is not particularly limited, and its composition can be appropriately selected according to the purpose, but preferably contains an unsaturated carboxylic acid-based water-soluble polymer and a base, a chelating agent, a moisturizing agent, and the like. Furthermore, other components are contained as necessary.

-Unsaturated carboxylic acid-based water-soluble polymer and base-
The unsaturated carboxylic acid-based water-soluble polymer and base are used for the purpose of thickening the aqueous phase and mainly improving the stability of the O / W emulsion ink for stencil printing on a stencil printing machine. The

The unsaturated carboxylic acid-based water-soluble polymer is at least one of acrylic acid derivative resins. There is no restriction | limiting in particular as said acrylic acid derivative resin, According to the objective, it can select suitably, For example, polyacrylic acid resin, polyacrylic acid sodium, polyacrylic acid triethanolamine etc. are mentioned.
The unsaturated carboxylic acid-based water-soluble polymer may be used alone or in combination of two or more.
The content of the unsaturated carboxylic acid-based water-soluble polymer is not particularly limited, and according to the type and molecular weight of the unsaturated carboxylic acid-based water-soluble polymer, the ink viscosity is optimal for matching with a printing press. However, it is preferably 0.05 to 10% by mass and more preferably 0.1 to 2% by mass with respect to the total mass of the ink. When the content is less than 0.05% by mass, a desired ink viscosity may not be obtained. Even when the content exceeds 10% by mass, no further thickening is observed in the ink, and the cost is low. It may be disadvantageous.
The pH of the aqueous phase is preferably adjusted to pH 5 to 10 from the viewpoint of thickening the ink, and a substance having a buffering action may be added to maintain the pH.

The base is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include inorganic bases such as potassium hydroxide and ammonium hydroxide, low molecular weight amines, alkanolamines, triethanolamine, low concentration ammonia and the like. Is mentioned.
The content of the base is also not particularly limited and can be appropriately selected so that the ink viscosity is optimal for matching with a printing machine, but is 0.01 to 3.0 mass relative to the total mass of the ink. % Is preferable, and 0.1 to 1.5% by mass is more preferable. When the content is less than 0.01% by mass, a desired ink viscosity may not be obtained. Even when the content exceeds 3.0% by mass, the ink does not show a certain viscosity increase, and the cost is low. May be disadvantageous.
Further, as described above, the pH of the aqueous phase is preferably adjusted to pH 5 to 10 from the viewpoint of thickening the ink, and the pH adjustment can be performed using the base.

-Chelating agent-
The chelating agent is mainly used for the purpose of maintaining the thickening of the aqueous phase over time.
The chelating agent is not particularly limited and may be appropriately selected depending on the purpose. For example, citric acid, tartaric acid, malic acid, gluconic acid, succinic acid, ethylenediaminetetraacetic acid, hydroxyethylethylenediaminetriacetic acid, Examples include dihydroxyethylethylenediaminediacetic acid, propanediaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, nitrilotriacetic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, and aminotrimethylenephosphonic acid.
The chelating agent may be used alone or in combination of two or more.
There is no restriction | limiting in particular in content of the said chelating agent, Although it can select suitably according to the objective, 0.001-0.01 mass% is preferable with respect to the total mass of ink. When the content is less than 0.001% by mass, a desired effect may not be obtained with respect to ink viscosity retention when the ink is stored. There is no effect of maintaining the above ink viscosity, which may be disadvantageous in cost.

-Humectant-
The humectant is mainly used for the purpose of suppressing water evaporation of the ink when the printing press is left after printing.
There is no restriction | limiting in particular as said moisturizer, According to the objective, it can select suitably, For example, glycerol (glycerol), a xylitol (xylit), d-sorbitol (sorbitol), lactic acid, urea etc. are mentioned.
The humectant may be used alone or in combination of two or more.
The content of the humectant is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 3 to 30% by mass, and more preferably 5 to 20% by mass with respect to the total mass of the ink. When the content is less than 3% by mass, the desired effect of the moisturizing agent may not be obtained. When the content exceeds 30% by mass, there is no certain effect, which may be disadvantageous in cost. is there.

-Other components (aqueous phase)-
The other components in the aqueous phase are not particularly limited and can be appropriately selected depending on the purpose within a range not impairing the effects of the present invention. For example, water, surfactant, unsaturated carbon Water-soluble polymers other than acid-based water-soluble polymers, O / W type resin emulsions, antiseptics and fungicides, antifreezing agents, antifoaming agents, organic solvents and the like can be mentioned.

--- Water--
The water is not particularly limited as long as it is clean, and can be appropriately selected according to the purpose. Examples thereof include tap water, ion exchange water, and distilled water.

--Surfactant--
There is no restriction | limiting in particular as said surfactant, Although it can select suitably according to the objective, Among these, a nonionic surfactant is preferable. The nonionic surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. For example, glycerin fatty acid ester, polyglycerin fatty acid ester, propylene glycol fatty acid ester, pentaerythritol fatty acid ester, polyoxyethylene sorbitan Fatty acid ester, polyoxyethylene sorbite 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, Polyoxyethylene castor oil, polyoxyethylene hydrogenated castor oil, polyoxyethylene lanolin derivative, poly Polyoxyethylene alkylamines, polyoxyethylene fatty acid amides, polyoxyethylene alkylphenyl formaldehyde condensates and the like.
Moreover, as the surfactant, those derived from vegetable oils are particularly preferable from the viewpoint of safety.
The said surfactant may be used individually by 1 type, and may use 2 or more types together.
There is no restriction | limiting in particular as content of the said surfactant, Although it can select suitably according to the objective, 1-10 mass% is preferable with respect to the total mass of ink, and 2-8 mass% is more. preferable.

--Water-soluble polymers other than unsaturated carboxylic acid-based water-soluble polymers--
The water-soluble polymer other than the unsaturated carboxylic acid-based water-soluble polymer is used, for example, for the purpose of moisturizing or assisting thickening.
The water-soluble polymer other than the unsaturated carboxylic acid-based water-soluble polymer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include natural polymers, semi-synthetic polymers, and synthetic polymers. Is mentioned.
The natural polymer is not particularly limited and may be appropriately selected depending on the intended purpose. , Casein and the like.
The semi-synthetic polymer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include carboxymethyl cellulose, hydroxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, hydroxymethyl starch, carboxy Examples include methyl starch and dialdehyde starch.
The synthetic polymer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include polyvinyl pyrrolidone, polyvinyl imide, polyvinyl alcohol, polyethylene imine, polyacrylamide, poly N-acryloyl pyrrolidine and poly N-isopropyl. Examples include poly N-alkyl-substituted acrylamides such as acrylamide, polyethylene oxide, polyvinyl methyl ether, styrene-maleic anhydride copolymers, styrene-acrylic acid copolymers, and the like. A block copolymer of polyethylene and polypropylene or polybutylene can also be used.

Among these, as the water-soluble polymer other than the unsaturated carboxylic acid-based water-soluble polymer, polyvinyl pyrrolidone is particularly preferable from the viewpoint of improving the stability on a stencil printing machine.
The K value of the polyvinyl pyrrolidone is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 30 or less. Here, the K value is a numerical value that serves as a standard for the molecular weight of polyvinylpyrrolidone, and can be obtained from, for example, a viscosity measurement value according to the Fikenscher equation. If the K value exceeds 30, the ink viscosity to which polyvinyl pyrrolidone is added becomes too high, which may inhibit ink suction from the ink pack and penetration into the paper during printing.

The water-soluble polymer other than the unsaturated carboxylic acid-based water-soluble polymer may be used alone or in combination of two or more.
The content of the water-soluble polymer other than the unsaturated carboxylic acid-based water-soluble polymer is not particularly limited and may be appropriately selected depending on the intended purpose, but is based on the mass of water in the aqueous phase. 25% by mass or less, and more preferably 0.2 to 15% by mass.

--O / W type resin emulsion--
The O / W type resin emulsion is used, for example, for the purpose of moisturizing and increasing the viscosity.
There is no restriction | limiting in particular as said O / W type resin emulsion, According to the objective, it can select suitably, For example, a synthetic polymer compound may be sufficient and a natural polymer compound may be sufficient.
The synthetic polymer compound is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include polyvinyl acetate, polymethacrylic acid ester, polyvinyl chloride, ethylene-vinyl acetate copolymer, vinyl chloride- A vinyl acetate copolymer, a polyurethane, etc. are mentioned.
The minimum film forming temperature of the O / W type resin emulsion is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 40 ° C. or lower.
The said O / W type | mold resin emulsion may be used individually by 1 type, and may use 2 or more types together.
There is no restriction | limiting in particular as content of the said O / W type | mold resin emulsion, Although it can select suitably according to the objective, 30 mass% or less is preferable with respect to the mass of the water in the said water phase, 0 2 to 15% by mass is more preferable.

--- Preservatives and fungicides--
The preservatives and fungicides are used for the purpose of preventing bacteria and fungi from growing in the O / W emulsion ink of the present invention. When the O / W emulsion ink is stored for a long period of time, it is preferable to use the preservative and the fungicide.
The antiseptic and fungicide are not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include aromatics such as salicylic acid, phenols, methyl p-oxybenzoate, and ethyl p-oxybenzoate. Hydroxy compounds, their chlorine compounds, sorbic acid, dehydroacetic acid, titania phosphate, chlorobutanol, chitosan derivatives and the like can be mentioned.
The preservatives and fungicides may be used alone or in combination of two or more.
There is no restriction | limiting in particular as content of the said antiseptic | preservative and antifungal agent, Although it can select suitably according to the objective, 3 mass% or less is preferable with respect to the mass of the water in the said water phase, 0 0.05 to 1.0 mass% or less is more preferable.

--- Anti-freezing agent--
The antifreeze agent is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include glycols such as ethylene glycol, diethylene glycol, dipropylene glycol, butylene glycol; methanol, ethanol, isopropanol, butanol, isobutanol. And lower saturated monohydric alcohols such as
The said antifreeze agent may be used individually by 1 type, and may use 2 or more types together.
The content of the antifreezing agent is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 30% by mass or less, and 6 to 25% by mass with respect to the mass of water in the aqueous phase. Is more preferable.

--- Antifoaming agent--
The antifoaming agent is used for the purpose of preventing foaming when the water-soluble polymer or the like is stirred in water.
There is no restriction | limiting in particular as said antifoamer, According to the objective, it can select suitably, For example, higher fatty acid amide, polyethyleneglycol, fatty acid lower alcohol ester, dimethylpolysiloxane etc. are mentioned.
The said antifoamer may be used individually by 1 type, and may use 2 or more types together.
The content of the antifoaming agent is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 0.1 to 1.5% by mass with respect to the total mass of the ink, 0.4 to 1.0 mass% is more preferable.
Moreover, ethylene glycol, lower alcohol, etc. can also be used as a carrier of the antifoaming agent.

-Organic solvent-
The organic solvent is used for the purpose of facilitating dissolution and dispersion of the water-soluble polymer in water.
There is no restriction | limiting in particular as said organic solvent, According to the objective, it can select suitably, For example, alcohols, such as isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, and butyl cellosolv, ester etc. are mentioned.
The said organic solvent may be used individually by 1 type, and may use 2 or more types together.
The content of the organic solvent is not particularly limited and may be appropriately selected depending on the purpose. It is preferably 0.1 to 5.0% by mass with respect to the mass of water in the aqueous phase, More preferably, it is 0.5 to 3.0% by mass.

<Manufacturing method>
There is no restriction | limiting in particular as a manufacturing method of the said O / W type emulsion ink for stencil printing, According to the objective, it can select suitably, For example, the said oil phase and an aqueous phase are prepared, respectively, Then, the said oil phase And an aqueous phase can be produced by emulsifying them in a known emulsifier.
That is, if necessary, the water, the unsaturated carboxylic acid-based water-soluble polymer, the base, the chelating agent, the humectant, the surfactant, the preservative and fungicide, the unsaturated An aqueous phase containing a water-soluble polymer other than a carboxylic acid-based water-soluble polymer is prepared by a conventional method, and then the colorant and, if necessary, the oil component, the oil component, The O / W emulsion ink for stencil printing can be produced by gradually adding and emulsifying an oil phase prepared by containing a colorant dispersant and the resin.
Further, the thickening of the aqueous phase with the base may be performed during preparation of the aqueous phase or after preparation of the aqueous phase, or may be performed after emulsification.

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

(Example 1: Preparation of O / W type emulsion ink for stencil printing)
According to the following composition, an oil phase liquid and an aqueous phase liquid were prepared. The composition is also shown in Table 1.
<Oil phase liquid composition>
Colorant: Carbon black (manufactured by Cabot Corporation: trade name Mogal L). . . 5.0 parts by weight dispersant of colorant: aluminum chelate (manufactured by Ajinomoto Fine Techno Co., Ltd .: trade name Plainact ALM). . . 0.5 parts by mass oil component: soybean oil butyl ester. . . 24.4 parts by mass antioxidant: dibutylhydroxytoluene. . . 0.1 part by mass <aqueous phase liquid composition>
Water: Ion exchange water. . . 59.9 parts by weight preservative and fungicide: methyl paraoxybenzoate. . . 0.1 part by mass surfactant: polyoxyethylene sorbitan fatty acid ester (manufactured by Kao Corporation: trade name Leodol TW-O120). . . 5.0 parts by mass Water-soluble polymer other than unsaturated carboxylic acid-based water-soluble polymer: 30% polyvinylpyrrolidone aqueous solution. . . 5.0 parts by weight

Carbon black, aluminum chelate, and dibutylhydroxytoluene were added to and mixed with soybean oil butyl ester, and the resulting mixture was stirred at a peripheral speed of 10 m / sec for 30 minutes using a high-speed dissolver. . Subsequently, using bead mill LMZ2 (manufactured by Ashizawa), dispersion treatment was performed under the following conditions to prepare an oil phase liquid.
<< Distributed processing conditions >>
Zirconia beads diameter: 1.5mm
Peripheral speed: 10m / s
Flow rate: 0.5 L / min
Moreover, polyoxyethylene sorbitan fatty acid ester, methyl paraoxybenzoate, and 30% polyvinylpyrrolidone aqueous solution were added to water and sufficiently dissolved to prepare an aqueous phase solution.
Next, an emulsification tester ET-3A type manufactured by Nikko Chemicals Co., Ltd. was used as an emulsifier, and an aqueous phase liquid was charged into the tester. 400r. p. While stirring the aqueous phase liquid at a speed of m, the oil phase liquid was gradually added and emulsified to obtain O / W emulsion ink for stencil printing of Example 1.

(Examples 2 to 7: Preparation of O / W emulsion ink for stencil printing)
O / W emulsion inks for stencil printing of each example were prepared in the same manner as in Example 1 except that the compositions of the oil phase liquid and the aqueous phase liquid were changed to the compositions shown in Tables 1 and 2 below. .
In addition, as shown in Tables 1 and 2, polyacrylic acid resin as an unsaturated carboxylic acid-based water-soluble polymer (manufactured by BF Goodrich: trade name Carbopol 940), ethylenediaminetetraacetic acid as a chelating agent, and Glycerin as a humectant was added to water and mixed during the preparation of the aqueous phase liquid, like the polyoxyethylene sorbitan fatty acid ester. Further, triethanolamine as a base was added while stirring the obtained O / W emulsion after the oil phase liquid was added to the aqueous phase liquid to complete emulsification.

(Comparative Example 1: Preparation of O / W emulsion ink for stencil printing)
According to the following composition, an oil phase liquid and an aqueous phase liquid were prepared. The composition is also shown in Table 2. In Comparative Example 1, the colorant was contained in the aqueous phase liquid.
<Oil phase liquid composition>
Aluminum chelate (manufactured by Ajinomoto Fine Techno Co., Ltd .: trade name Plainact ALM). . . 0.5 parts by mass oil component: soybean oil butyl ester. . . 29.4 parts by weight of antioxidant: dibutylhydroxytoluene. . . 0.1 part by mass <aqueous phase liquid composition>
Colorant: Carbon black (manufactured by Cabot Corporation: trade name Mogal L). . . 5.0 parts by mass of water: ion-exchanged water. . . 54.9 parts by weight preservative and fungicide: methyl paraoxybenzoate. . . 0.1 part by mass surfactant: polyoxyethylene sorbitan fatty acid ester (manufactured by Kao Corporation: trade name Leodol TW-O120). . . 5.0 parts by mass Water-soluble polymer other than unsaturated carboxylic acid-based water-soluble polymer: 30% polyvinylpyrrolidone aqueous solution. . . 5.0 parts by mass

An aluminum chelate and dibutylhydroxytoluene were added to soybean butyl ester and dissolved sufficiently to prepare an oil phase solution.
Further, carbon black, 30% polyvinyl pyrrolidone aqueous solution, methyl paraoxybenzoate, and polyoxyethylene sorbitan fatty acid ester are added to ion-exchanged water and mixed, and the resulting mixture is mixed with a high-speed dissolver at a peripheral speed. The mixture was stirred at 10 m / sec for 30 minutes. Subsequently, using bead mill LMZ2 (manufactured by Ashizawa Corporation), a dispersion treatment was performed under the following conditions to prepare an aqueous phase liquid.
<Distributed processing conditions>
Zirconia beads diameter: 1.5mm
Peripheral speed: 10m / s
Flow rate: 0.5 L / min
Next, an emulsification tester ET-3A type manufactured by Nikko Chemicals Co., Ltd. was used as the emulsifier, and an aqueous phase liquid was charged into the tester, and 400 r. p. While stirring the aqueous phase liquid at a speed of m, the oil phase liquid was gradually added and emulsified to obtain O / W type emulsion ink for stencil printing of Comparative Example 1.

[Evaluation]
Using the O / W type emulsion ink for stencil printing of Examples 1 to 7 and Comparative Example 1, the water resistance after image formation and the stability on the stencil printing machine (hanging to the side of the ink roller) are as follows. And dripping to the side of the ink roller after storage at 60 ° C. for 1 month) and image restoration after leaving the printing press. Each evaluation result is shown in Tables 3-4.

<Evaluation of water resistance>
After making a plate using the inks of Examples 1 to 7 and Comparative Example 1, the image on the 20th printed sheet was traced with an aqueous line marker one hour after printing. Visual evaluation was performed based on four-stage evaluation criteria.
For printing, a Ricoh printing press JP5500 was used. Moreover, OPTEX CARE (manufactured by ZEBRA) was used as the line marker, and the writing pressure was about 200 g, and a light color was selected so that the image under the handwriting could be visually observed.
-Evaluation criteria-
1 ... Bleeding is conspicuous even in bold and thin characters, unusable state 2 ... Bleeding is conspicuous in the bold portion but usable 3) Bleeding is faintly seen in the bold portion ..No bleeding

<Evaluation of stability on a stencil printing machine (hanging to the side of the ink roller)>
Using the inks of Examples 1 to 7 and Comparative Example 1, using a printing machine JP5500 manufactured by Ricoh Company, printing 10,000 sheets at a printing speed of 5 speeds at 30 ° C. Observed and evaluated visually based on the following four-stage evaluation criteria.
-Evaluation criteria-
1 ... Ink leaks to the side of the ink roller, leaks from the gap between the plate cylinders, and the printed image is contaminated. 2 ... Although it does not affect the printed image, it leaks to the side of the ink roller and damages the gears etc. State 3 is leaking to the side of the ink roller, but it is not reaching the gears beside the roller 4 State that is not leaking to the side of the ink roller

<Evaluation of stability on a stencil printing machine (dripping to the side of the ink roller after storage at 60 ° C. for one month)>
The inks of Examples 1 to 7 and Comparative Example 1 were stored in a thermostatic bath at 60 ° C. for one month in a state where they were filled in an ink pack, and then acclimatized to 30 ° C. Using a printing press JP5500, 10,000 sheets were printed at 30 ° C. at a printing speed of 5 speeds, and the sag to the side of the ink roller was observed and evaluated based on the same four-stage evaluation criteria as described above.

<Evaluation of image recovery after leaving the printing press>
Using the inks of Examples 1 to 7 and Comparative Example 1, printing was performed using a stencil printer JP5500 manufactured by Ricoh, and the drum was then left for 3 days (normal temperature and humidity) with the stencil printer. Later, printing was performed and the number of sheets until the image was completely restored was evaluated.

  From Tables 1 to 4, the O / W emulsion ink for stencil printing of Examples 1 to 7 containing a colorant in the oil phase is compared to the O / W emulsion ink for stencil printing of Comparative Example 1, It was found that water resistance after image formation, stability on a stencil printing machine, and image restoration after leaving the printing machine were excellent. In particular, Examples 5 to 7 containing an unsaturated carboxylic acid-based water-soluble polymer and a base in the aqueous phase are stable on a stencil printing machine, and Examples 6 and 7 further containing a chelating agent are after storage over time. It was found that the stability on the stencil printing press of Examples 4 and 7 containing a humectant was extremely excellent in the image restoration property after leaving the printing press.

The O / W emulsion ink for stencil printing of the present invention is excellent in all of water resistance after image formation, stability on the stencil printing machine, and image restoration after leaving the printing machine, and to the environment and human body. Therefore, it is very useful as an ink used for stencil printing by a rotary stencil printing machine.

Claims (4)

  An O / W emulsion ink for stencil printing, comprising an oil phase and an aqueous phase, and containing a colorant in the oil phase.   2. The stencil printing apparatus according to claim 1, wherein the aqueous phase contains an unsaturated carboxylic acid-based water-soluble polymer and a base, and the unsaturated carboxylic acid-based water-soluble polymer is at least one of acrylic acid derivative resins. O / W type emulsion ink.   Further, a chelating agent is contained in the aqueous phase, and the chelating agent is citric acid, tartaric acid, malic acid, gluconic acid, succinic acid, ethylenediaminetetraacetic acid, hydroxyethylethylenediaminetriacetic acid, dihydroxyethylethylenediaminediacetic acid, propane It is at least one selected from the group consisting of diaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, nitrilotriacetic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, and aminotrimethylenephosphonic acid Item 3. The O / W emulsion ink for stencil printing according to Item 2. The humectant is contained in the aqueous phase, and the humectant is at least one selected from the group consisting of glycerin, xylitol, d-sorbitol, lactic acid, and urea. O / W emulsion ink for stencil printing.