CN111849244A

CN111849244A - Water-in-oil type emulsion ink for porous printing

Info

Publication number: CN111849244A
Application number: CN202010069984.4A
Authority: CN
Inventors: 今市悠貴
Original assignee: Riso Kagaku Corp
Current assignee: Riso Kagaku Corp
Priority date: 2019-04-25
Filing date: 2020-01-21
Publication date: 2020-10-30
Anticipated expiration: 2040-01-21
Also published as: JP2020180211A; JP7098568B2; CN111849244B

Abstract

The invention relates to a water-in-oil emulsion ink for porous printing. The invention provides a water-in-oil emulsion ink for stencil printing, which can prevent ink from leaking from a plate cylinder of a printing device even if the stencil printing device is placed in a non-use state. A water-in-oil emulsion ink for stencil printing, comprising: an oil phase containing an oil-soluble resin having a carboxyl group, and an aqueous phase containing a compound represented by the following formula (1) and a water-soluble divalent metal salt. R-C (CH)₂OH)₂‑NH₂… (1). In the formula (1), R is a hydrogen atom or an alkyl group having 1-2 carbon atoms optionally substituted with a hydroxyl group.

Description

Water-in-oil type emulsion ink for porous printing

Technical Field

The present invention relates to a water-in-oil type emulsion ink used in a stencil printing apparatus.

Background

Compared with printing methods such as offset printing, intaglio printing and relief printing, the stencil printing method does not require complicated operations such as cleaning after use, does not require a professional operator, and has good operability and simplicity. After a thermal plate making method using a thermal head as a device is used, digitization of image processing is targeted in a stencil printing method, and a high-quality printed matter can be obtained easily in a short time, and therefore, convenience thereof is confirmed as an information processing terminal. In particular, rotary stencil printing apparatuses, in which automatic control is performed on plate making/setting/layout operations of stencil sheet (master), ink supply operations, printing operations, and the like, are widely used in offices, schools, and the like under the name of digital stencil printers and the like.

Water-in-oil (W/O) emulsion inks are generally used as inks for stencil printing. The water-in-oil type emulsion ink has a function of suppressing the change in the composition and physical properties of the ink even when the ink inside the printing apparatus comes into contact with the atmosphere when the stencil printing apparatus is left unused. That is, water as an internal phase component of the emulsion ink is covered with oil as an external phase component, and thus the evaporation rate thereof is suppressed.

However, if the stencil printing apparatus is left unused for a long time, the water in the emulsion gradually evaporates from the ink remaining inside the plate cylinder of the printing apparatus, and the ratio of the water phase to the oil phase decreases, thereby decreasing the ink viscosity. As a result of softening of the ink, the ink leaks from the plate cylinder of the printing apparatus, and maintenance work such as cleaning may be required.

In order to solve such a problem, for example, an emulsion ink for stencil printing has been proposed in which an extender pigment is further contained in a water-in-oil emulsion ink containing a dye as a colorant (patent document 1). Further, a water-in-oil emulsion ink for stencil printing has been proposed, in which a water-in-oil emulsion ink containing an oil phase and a water phase contains a coloring pigment having an oil absorption of 50ml/100g or less at normal temperature in the oil phase, and further contains an extender pigment having an oil absorption of 60ml/100g or more at normal temperature in the oil phase (patent document 2).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2000-191970

Patent document 2: japanese patent laid-open publication No. 2001-311027

Disclosure of Invention

Problems to be solved by the invention

However, in the ink of patent document 1, it is necessary to contain a large amount of extender pigment, and the particle concentration in the ink becomes high accordingly, so that it is difficult to use the pigment as the colorant. In the case of an ink containing a large amount of particles such as an extender pigment or a pigment, when the water content in the ink is reduced by leaving the stencil printing apparatus unused, the particle concentration is further increased. As a result, when printing is performed using ink left unused, clogging is likely to occur in a screen or the like wound around a plate cylinder, and there is a concern that a printed image may be intermittent. The ink of patent document 2 is also concerned similarly, and therefore it is necessary to contain a pigment having specific characteristics, and the content of the extender pigment is also small. Further, there is a problem in terms of ink production, such as the need to provide a step of dispersing the extender pigment in order to blend the extender pigment into the ink.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a water-in-oil emulsion ink for stencil printing which can prevent ink from leaking from a plate cylinder of a printing apparatus even when the stencil printing apparatus is left unused.

Means for solving the problems

An embodiment of the present invention is a water-in-oil emulsion ink for stencil printing, comprising: an oil phase containing an oil-soluble resin having a carboxyl group, and an aqueous phase containing a compound represented by the following formula (1) and a water-soluble divalent metal salt.

R-C(CH₂OH)₂-NH₂…(1)

In the formula (1), R is a hydrogen atom or an alkyl group having 1-2 carbon atoms optionally substituted with a hydroxyl group.

The oil-soluble resin having a carboxyl group preferably comprises an alkyd resin or a rosin-modified phenol resin.

The ratio of the content of the compound represented by formula (1) to the water-soluble divalent metal salt is preferably 2: 8-7: 3.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to provide a water-in-oil emulsion ink for stencil printing which prevents ink from leaking from a plate cylinder of a printing apparatus even when the stencil printing apparatus is left unused.

Detailed Description

The water-in-oil emulsion ink for stencil printing (hereinafter also simply referred to as ink) according to the embodiment of the present invention includes: an oil phase containing an oil-soluble resin having a carboxyl group, and an aqueous phase containing a compound represented by the following formula (1) and a water-soluble divalent metal salt.

R-C(CH₂OH)₂-NH₂…(1)

When the stencil printing apparatus is left unused, the water in the emulsion gradually evaporates from the ink remaining inside the plate cylinder of the printing apparatus, and the concentration of the compound represented by formula (1) contained in the water phase of the emulsion in the water phase gradually increases. Therefore, the amount of the compound represented by formula (1) present in the vicinity of the interface of the oil phase and the water phase of the emulsion increases. On the other hand, the oil-soluble resin having a carboxyl group contained in the oil phase has a property of being easily oriented at the interface between the oil phase and the water phase due to its polar group. As described above, the amount of the oil-soluble resin having a carboxyl group and the compound represented by formula (1) increases in the vicinity of the interface between the oil phase and the water phase, and therefore, the carboxyl group, which is the acidic functional group of the oil-soluble resin having a carboxyl group, and the amino group, which is the basic functional group of the compound represented by formula (1), are easily subjected to a neutralization reaction. When the neutralization reaction proceeds, the hydrophilicity of the oil-soluble resin having a carboxyl group increases, and the oil-soluble resin having a carboxyl group is more likely to be oriented at the interface between the oil phase and the water phase.

The water-soluble divalent metal salt also gradually increases in concentration in the aqueous phase as the water in the emulsion gradually evaporates. The water-soluble divalent metal salt is an electrolyte, and the carboxyl group of the oil-soluble resin having a carboxyl group, the hydrophilicity of which has been improved by neutralization reaction, easily forms a complex with a divalent metal atom. When the carboxyl group of the oil-soluble resin having a carboxyl group forms a complex with the divalent metal atom and the divalent metal atom further forms a complex with a plurality of carboxyl groups, the oil-soluble resin having a carboxyl group forms a polymer compound which is apparently aggregated. As described above, the oil-soluble resin having a carboxyl group forms an aggregate of the polymer compound, and therefore, the ink begins to have high elasticity as the water in the emulsion evaporates. It can therefore be considered that: even if the stencil printing apparatus is left unused for a long period of time, ink remaining inside the plate cylinder of the printing apparatus is not easily dropped, thereby preventing the ink from leaking from the plate cylinder.

In the ink according to the embodiment of the present invention, the oil phase is preferably 15 to 55 mass%, and the water phase is preferably 85 to 45 mass%. The oil phase preferably contains an oil-soluble resin having a carboxyl group, an oil component, an emulsifier, and the like, and the aqueous phase preferably contains a compound represented by the following formula (1), a water-soluble divalent metal salt, water, and the like. The colorant may be contained in either the oil phase or the aqueous phase. Hereinafter, the components of the ink according to the embodiment of the present invention will be described in order.

R-C(CH₂OH)₂-NH₂…(1)

< oil phase >

[ oil-soluble resin having carboxyl group ]

In the present embodiment, the oil phase contains an oil-soluble resin having a carboxyl group. The oil-soluble resin having a carboxyl group may be a solid resin or a liquid resin. Examples of the oil-soluble resin having a carboxyl group include an oil-soluble resin using rosin as a raw material, an oil-soluble resin using a polybasic acid (e.g., a dibasic acid) as a raw material, and an oil-soluble resin using rosin and a polybasic acid (e.g., a dibasic acid) as a raw material. As the oil-soluble resin using rosin as a raw material, for example, rosin ester, rosin-modified phenol resin, and the like are preferable. As the oil-soluble resin using a polybasic acid as a raw material, for example, alkyd resin, maleic acid resin, phthalic acid resin, and the like are preferable. As the oil-soluble resin using rosin and a polybasic acid as raw materials, for example, a rosin-modified maleic acid resin and the like are preferable. Among these, rosin-modified phenol resins and alkyd resins are preferable because the ink can be more effectively prevented from leaking out of the plate cylinder.

The rosin-modified phenol resin is a resin obtained by modifying a phenol resin with a natural rosin, and is a resin composed of rosin, an alkylphenol, formaldehyde, and a polyol. As the alkylphenol, p-tert-butylphenol, p-tert-octylphenol, p-nonylphenol, p-dodecylphenol or the like can be used, and as the polyhydric alcohol, pentaerythritol, glycerin or the like can be used. The alkyd resin is a synthetic resin produced by polycondensation of a polybasic acid and a fatty acid (or a fatty oil) with a polyhydric alcohol, and glycerin, pentaerythritol, and the like can be used as the polyhydric alcohol, phthalic anhydride, maleic anhydride, and the like can be used as the polybasic acid, and unsaturated fatty acids contained in linseed oil, soybean oil, castor oil, and the like can be used as the fatty oil. In addition, in the present embodiment, a reaction product of an alkyd resin or rosin-modified resin and an aluminum chelate compound or aluminum alkoxide may also be preferably used.

The oil-soluble resin having a carboxyl group may be used alone, or two or more kinds thereof may be suitably used in combination. The content of the oil-soluble resin is preferably 1 to 20 mass%, more preferably 3 to 15 mass%, and still more preferably 7 to 15 mass% of the entire ink, because the ink can be more effectively prevented from leaking out of the plate cylinder.

[ oil component ]

In the present embodiment, as the oil component, various industrial solvents, mineral oils such as engine oil, gear oil, gas oil, kerosene, spindle oil, machine oil, and liquid paraffin; vegetable oils such as olive oil, rapeseed oil, linseed oil, castor oil, salad oil, soybean oil, rice bran oil, and the like; and synthetic oils and the like.

Any industrial solvent may be used as long as it is a water-insoluble organic solvent. Preferred examples thereof include petroleum hydrocarbon solvents such as aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, and aromatic hydrocarbon solvents. As the aliphatic hydrocarbon Solvent and alicyclic hydrocarbon Solvent, can cite alkane series, isoparaffin series, naphthenic hydrocarbon series, such as water-insoluble organic Solvent, as the commercial products, preferably include 0 number Solvent L, 0 number Solvent M, 0 number Solvent H, Cactus Normal Paraffin N-10, Cactus Normal Paraffin N-11, Cactus Normal Paraffin N-12, Cactus Normal Paraffin N-13, Cactus Normal Paraffin N-14, Cactus Normal Paraffin N-15H, Cactus Normal Paraffin YHNP, Cactus Normal Paraffin SHNP, Isozol 300, oozol 400, TECCLEAN N-16, TECLEAN N-20, TEN-22, CLEAN 4, 5, 6, Solvent Naphson K, 2, 220, the trade name of the product name of the product Naphson, Solvot AF, 2, 220, the product name of the product Naphson and the Solvent AF; ISOPAR G, ISOPAR H, ISOPAR L, ISOPAR M, Exor D40, Exor D60, Exor D80, Exor D95, Exor D110, and EXXSOL D130 (all trade names manufactured by Exxon Mobil Corporation); COSMO ALLPUS 32, COSMO ALLPUS46, COSMO ALLPUS 56, COSMO ALLPUS 68, cosmooaallpus 100, COSMO ALLPUS 150, COSMO ALLPUS 220, COSMO ALLPUS 320, COSMO ALLPUS460 (both trade names made by COSMO OIL lumnicants co., ltd.), and the like. Preferred examples of the aromatic hydrocarbon solvent include Grade alkenone L and Grade alkenone 200P (both trade names available from JXTG energy co.); SOLVESSO100, SOLVESSO 150, SOLVESSO 200ND (all trade names made by Exxon Mobil Corporation), and the like. The initial distillation boiling point of the petroleum-based hydrocarbon solvent is preferably 100 ℃ or higher, more preferably 150 ℃ or higher, and still more preferably 200 ℃ or higher. The initial distillation point can be measured in accordance with JIS K0066 "test method for distillation of chemical products".

Further, as the oil component, organic solvents such as fatty acid ester solvents, higher alcohol solvents, higher fatty acid solvents, and the like can be preferably used. Examples thereof include fatty acid ester solvents having 13 or more carbon atoms in 1 molecule, preferably 16 to 30 carbon atoms, such as isononyl isononanoate, isodecyl isononanoate, methyl laurate, isopropyl laurate, hexyl laurate, isopropyl myristate, isopropyl palmitate, hexyl palmitate, isooctyl palmitate, isostearyl palmitate, methyl oleate, ethyl oleate, isopropyl oleate, butyl oleate, hexyl oleate, methyl linoleate, ethyl linoleate, isobutyl linoleate, butyl stearate, hexyl stearate, isooctyl stearate, isopropyl isostearate, 2-octyldecyl pivalate, soybean oil methyl ester, soybean oil isobutyl ester, tall oil methyl ester, and tall oil isobutyl ester; higher alcohol solvents having 6 or more carbon atoms, preferably 12 to 20 carbon atoms, in 1 molecule such as isomyristyl alcohol, isopalmitol, isostearyl alcohol, oleyl alcohol, isoeicosyl alcohol, decyltetradecyl alcohol; and higher fatty acid solvents having 12 or more carbon atoms, preferably 14 to 20 carbon atoms, in 1 molecule, such as lauric acid, isomyristic acid, palmitic acid, isopalmitic acid, α -linolenic acid, linoleic acid, oleic acid, and isostearic acid. The boiling point of the organic solvent such as a fatty acid ester solvent, a higher alcohol solvent, or a higher fatty acid solvent is preferably 150 ℃ or higher, more preferably 200 ℃ or higher, and still more preferably 250 ℃ or higher. The organic solvent having a boiling point of 250 ℃ or higher also includes an organic solvent not having a boiling point.

These oil components may be used alone, or two or more of them may be used in combination as long as they form a single phase.

[ emulsifiers ]

In the present embodiment, the emulsifier is used to form a water-in-oil emulsion, and a lipophilic emulsifier having an HLB value of preferably 3 to 8, more preferably 3.5 to 6.5 can be used. As the emulsifier, anionic surfactant, cationic surfactant, amphoteric surfactant, and nonionic surfactant can be used. Among these, nonionic surfactants are preferably used from the viewpoint of emulsifiability and storage stability of the water-in-oil emulsion. Specific examples thereof include sorbitan fatty acid esters such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monooleate, sorbitan sesquioleate, and sorbitan monoisostearate, and (poly) glycerol fatty acid esters such as glycerol monostearate, hexaglycerol tetraoleate, hexaglycerol pentaoleate, decaglycerol decaoleate, decaglycerol pentahydroxystearate, decaglycerol pentaisostearate, and decaglycerol condensed ricinoleate, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene glycerol fatty acid esters, polyoxyethylene sorbitol fatty acid esters, propylene glycol fatty acid esters, (poly) ethylene glycol fatty acid esters, polyoxyethylene alkyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl phenyl ethers, and the like, Polyoxyethylene (hydrogenated) castor oil, and the like. The emulsifiers may be used alone or in combination of two or more. The content of the emulsifier is preferably 0.1 to 10% by mass, more preferably 1 to 5% by mass, based on the total amount of the ink.

[ coloring agent ]

In the present embodiment, the oil phase preferably contains a colorant. As the colorant, pigments and dyes are cited, and pigments are preferably contained. As the pigment, organic pigments such as azo pigments, phthalocyanine pigments, polycyclic pigments, and dye lake pigments, and inorganic pigments can be used. Examples of the azo pigment include soluble azo lake pigments, insoluble azo pigments, and condensed azo pigments. Examples of the phthalocyanine pigment include metal phthalocyanine pigments such as copper phthalocyanine blue and copper phthalocyanine green, and metal-free phthalocyanine pigments. Examples of the polycyclic pigment include quinacridone pigments, perylene ketone pigments, isoindoline pigments, isoindolinone pigments, dioxazine pigments, thioindigo pigments, anthraquinone pigments, quinophthalone pigments, metal complex pigments, and Diketopyrrolopyrrole (DPP). As the inorganic pigment, a metal pigment such as carbon black, titanium oxide, brass powder, or the like is typically used. Examples of the dye include oil-soluble dyes such as azo dyes, metal complex salt dyes, naphthol dyes, anthraquinone dyes, indigo dyes, carbonium dyes, quinonimine dyes, xanthene dyes, cyanine dyes, quinoline dyes, nitro dyes, nitroso dyes, benzoquinone dyes, naphthoquinone dyes, phthalocyanine dyes, and metal phthalocyanine dyes.

These pigments and dyes may be used alone or in combination of two or more. The content of the colorant is preferably 0.1 to 20% by mass, more preferably 1 to 10% by mass, based on the total amount of the ink.

[ other oil phase Components ]

In the present embodiment, the oil phase may further contain, as appropriate, an oil-soluble resin other than the oil-soluble resin having a carboxyl group, an extender pigment, a pigment dispersant, an antioxidant, a gelling agent, and the like. As the oil-soluble resin other than the oil-soluble resin having a carboxyl group, for example, hard asphalt, phenol resin, petroleum resin, acrylic resin, amino resin, urethane resin, cellulose resin, natural rubber derivative resin, or the like can be used. As the extender pigment, for example, talc, diatomaceous earth, calcium carbonate, barium sulfate, alumina white, silica, kaolin, mica, acid clay, activated clay, bentonite, and the like can be used. Examples of the pigment dispersant include carboxylic acid esters containing a hydroxyl group, salts of long-chain polyaminoamides with high-molecular-weight acid esters, salts of high-molecular-weight polycarboxylic acids, salts of long-chain polyaminoamides with polar acid esters, high-molecular-weight unsaturated acid esters, high-molecular copolymers, modified polyurethanes, modified polyacrylates, polyether ester type anionic surfactants, polyoxyethylene alkyl phosphate esters, polyester polyamines, copolymers of vinyl pyrrolidone and long-chain olefins, and nitrogen-containing graft copolymers having polyester side chains. Examples of the antioxidant include dibutylhydroxytoluene, propyl gallate, tocopherol, butylhydroxyanisole, nordihydroguaiaretic acid, phenothiazine, and the like.

< aqueous phase >

[ Compound represented by the formula (1) ]

In the present embodiment, the aqueous phase contains a compound represented by the following formula (1).

R-C(CH₂OH)₂-NH₂…(1)

The compound represented by the formula (1) is a basic compound. The compound represented by the formula (1) has R having 0 to 2 carbon atoms, and when the compound represented by the formula (1) has 3 to 5 carbon atoms, it is difficult to form a sparingly soluble salt with a divalent metal atom of a water-soluble divalent metal salt, and it is easy to cause a neutralization reaction with a carboxyl group of an oil-soluble resin having a carboxyl group, and therefore, leakage of ink from a plate cylinder can be prevented.

Preferred examples of the compound represented by the formula (1) include 2-amino-1, 3-propanediol, 2-amino-2-methyl-1, 3-propanediol, 2-amino-2-ethyl-1, 3-propanediol, 2-amino-2-hydroxymethyl-1, 3-propanediol, and 2-amino-2-hydroxyethyl-1, 3-propanediol.

The compounds represented by the formula (1) may be used alone, or two or more kinds thereof may be used in combination as appropriate. The content of the compound represented by formula (1) is preferably 0.05 to 5% by mass, more preferably 0.1 to 2% by mass, based on the total amount of the ink, because the ink can be more effectively prevented from leaking out of the plate cylinder.

[ Water-soluble divalent Metal salt ]

In this embodiment, the aqueous phase comprises a water-soluble divalent metal salt. The water-soluble divalent metal salt is an electrolyte. By including a water-soluble compound belonging to a divalent metal salt in the aqueous phase, a complex is easily formed with the oil-soluble resin having a carboxyl group, and leakage of the ink from the plate cylinder can be prevented.

Examples of the water-soluble divalent metal salt include magnesium sulfate, zinc sulfate, iron sulfate, nickel sulfate, copper sulfate, magnesium thiosulfate, calcium nitrate, magnesium nitrate, zinc nitrate, iron nitrate, nickel nitrate, lead nitrate, copper nitrate, calcium chloride, magnesium chloride, barium chloride, zinc chloride, iron chloride, nickel chloride, and copper chloride, and hydrates thereof may also be used. The divalent metal atom of the water-soluble divalent metal salt is preferably magnesium, calcium, or the like, because the ink can be more effectively prevented from leaking out of the plate cylinder.

The water-soluble divalent metal salt may be used alone, or two or more thereof may be used in combination as appropriate. The content of the water-soluble divalent metal salt is preferably 0.01 to 5% by mass, more preferably 0.05 to 2% by mass, based on the total amount of the ink, because the ink can be more effectively prevented from leaking out of the plate cylinder. Here, the water-soluble divalent metal salt is a content in terms of the amount of water and water molecules removed when the water-soluble divalent metal salt is a hydrate.

Further, the ratio of the content of the compound represented by formula (1) to the water-soluble divalent metal salt (in the case of a hydrate, the amount after removing already water and water molecules) is preferably 1: 9-9: 1. more preferably 2: 8-7: 3, because ink leakage from the plate cylinder can be prevented more effectively.

[ Water ]

In the present embodiment, water is preferably the main component of the aqueous phase. The water is not particularly limited as long as it is clean, and ion-exchanged water, distilled water, purified water, tap water, groundwater, or the like can be used. The content of water is preferably 40 to 80% by mass, more preferably 50 to 70% by mass, based on the total amount of the ink.

[ Water-soluble organic solvent ]

In this embodiment, the aqueous phase may further contain a water-soluble organic solvent. As the water-soluble organic solvent, an organic compound which is liquid at room temperature and soluble in water can be used. Examples of the solvent include lower alcohols having 1 to 4 carbon atoms such as methanol, ethanol, 1-propanol, isopropanol, 1-butanol, 2-butanol, isobutanol, and 2-methyl-2-propanol; glycols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, and polypropylene glycol; glycerols such as glycerol, diglycerol, triglycerol and polyglycerin; glycerol acetates such as monoacetin and diacetin; glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monopropyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, etc.; triethanolamine, 1-methyl-2-pyrrolidone, 1, 3-dimethyl-2-imidazolidinone, β -thiodiglycol, sulfolane, and the like. These water-soluble organic solvents may be used alone, or two or more thereof may be used in combination as long as a single phase is formed. As the water-soluble organic solvent, a water-soluble organic solvent which is uniformly mixed with an equal volume of water at 20 ℃ under 1 atm is preferably used. The boiling point of the water-soluble organic solvent is preferably 100 ℃ or higher, more preferably 150 ℃ or higher. The water-soluble organic solvent having a boiling point of 150 ℃ or higher also includes a water-soluble organic solvent not having a boiling point.

[ coloring agent ]

In this embodiment, the aqueous phase may contain a colorant. As the colorant, pigments and dyes can be cited. As the pigment, the same pigment as the pigment contained in the oil phase can be used. As the dye, for example, a water-soluble dye among a basic dye, an acid dye, a direct dye, a soluble vat dye, an acid mordant dye, a reaction dye, a vat dye, a sulfur dye, and the like, and a water-soluble dye which is water-soluble by reduction or the like can be preferably used. In addition, azo, anthraquinone, azomethine, nitro and other disperse dyes can also be preferably used.

[ other Water phase Components ]

In the present embodiment, the aqueous phase may further contain a preservative, an antioxidant, a pH adjuster, an electrolyte other than the water-soluble divalent metal salt, a water-soluble resin, a water-dispersible resin, an extender pigment, a surfactant, a pigment dispersant, and the like as appropriate. The preservative can prevent the deterioration of the ink and improve the storage stability. As the preservative, for example, isothiazolone-based preservatives such as 5-chloro-2-methyl-4-isothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one and 1, 2-benzisothiazolin-3-one; triazine-based preservatives such as hexahydro-1, 3, 5-tris (2-hydroxyethyl) s-triazine; pyridine-quinoline preservatives such as sodium 2-pyridinethiolate-1-oxide and 8-hydroxyquinoline; dithiocarbamate preservatives such as sodium dimethyldithiocarbamate; organic bromine-based preservatives such as 2, 2-dibromo-3-nitrilopropionamide, 2-bromo-2-nitro-1, 3-propanediol, 2-dibromo-2-nitroethanol, and 1, 2-dibromo-2, 4-dicyanobutane; methyl paraben, ethyl paraben, potassium sorbate, sodium dehydroacetate, salicylic acid and the like. Examples of the antioxidant include L-ascorbic acid, sodium L-ascorbate, sodium erythorbate, sulfurous acid, potassium sulfite, sodium sulfite, ammonium bisulfite, sodium thiosulfate, sodium dithionite, and sodium metabisulfite.

< Properties and the like >

The viscosity of the water-in-oil emulsion ink for stencil printing of the present embodiment is preferably in the range of 0.5 to 20Pa · s (viscosity at 20 ℃ c and a shear rate of 100/sec) in general, although the range of applicability varies depending on the printing pressure of the stencil printing apparatus and the like, and (pseudo) plastic fluidity is suitable for stencil printing applications.

The water-in-oil emulsion ink for stencil printing of the present embodiment is generally produced by slowly adding the aqueous phase composition to the oil phase composition using a known emulsification apparatus and emulsifying the mixture. The aqueous phase composition and the oil phase composition are preferably prepared separately in advance, and then the aqueous phase composition is added to the oil phase composition and emulsified. When a pigment is contained as the colorant, the pigment is preferably dispersed by a known dispersing device such as a ball mill, an attritor, a sand mill, a roll mill, or a bead mill when preparing the oil phase composition or the water phase composition. The preparation of the oil phase composition and the preparation of the aqueous phase composition may be carried out by mixing the total amount of the components together, or by mixing a part of the components and then mixing the remaining components. The ink can be produced by using a known emulsifying apparatus such as a dispersion mixer, a homomixer, or a colloid mill.

The water-in-oil emulsion ink for stencil printing of the present embodiment can be suitably used for printing paper such as plain paper, coated paper, and special paper. Among the printing papers, plain paper is suitable. Here, plain paper refers to paper on which an ink receiving layer, a film layer, and the like are not formed on ordinary paper. Examples of plain paper include high-quality paper, medium-grade paper, PPC paper, wood pulp paper, and recycled paper.

Examples

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples as long as the technical idea of the present invention is not exceeded. The components not specifically described are available from fuji film and Wako pure chemical industries, etc.

< preparation of Water-in-oil emulsion ink for stencil printing >

[ example 1]

First, a phthalocyanine pigment (TOYO INK co., ltd. "LIONOL BLUE FG-7330") 5.0 mass%, an alkyd resin (Arakawa Chemical Industries, ltd. "ARAKYD 251") 13.0 mass%, mineral OIL a (Naphtesol 200, "JXTG energy co., ltd.) 5.0 mass%, mineral OIL B (COSMO OIL l britsco., ltd." COSMO all 460 ") 10.0 mass%, decaglycerol pentaoleate (Nikko Chemical co., ltd.," NIKKOL Decaglyn 5-OV ") 1.0 mass% were mixed, and pigment dispersion was performed using a three-roll mill to prepare an OIL phase. Subsequently, 0.5 mass% of 2-amino-2-methyl-1, 3-propanediol, 1.0 mass% of magnesium sulfate heptahydrate, and 64.5 mass% of ion-exchanged water were mixed to prepare an aqueous phase. The prepared oil phase was put into an emulsifying apparatus, and the prepared aqueous phase was slowly dropped while rotating a stirring blade, and further, emulsification was performed by continuously rotating the stirring blade, thereby preparing the water-in-oil emulsion ink for stencil printing of example 1.

[ example 2]

A water-in-oil emulsion ink for stencil printing of example 2 was prepared in the same manner as in example 1, except that 2-amino-2-methyl-1, 3-propanediol was changed to 2-amino-2-ethyl-1, 3-propanediol.

[ example 3]

A water-in-oil emulsion ink for stencil printing of example 3 was prepared in the same manner as in example 1, except that 2-amino-2-methyl-1, 3-propanediol was changed to 2-amino-2-hydroxymethyl-1, 3-propanediol.

[ example 4]

A water-in-oil emulsion ink for stencil printing of example 4 was produced in the same manner as in example 1, except that 2-amino-2-methyl-1, 3-propanediol was changed to 2-amino-1, 3-propanediol.

[ examples 5 to 8]

8.0 mass% of a rosin-modified phenol resin ("HARIPHENOL 512" manufactured by HARIMA CHEMICAL CO., LTD.) and 5.0 mass% of mineral oil A ("Naphtesol 200" manufactured by JXTG ENERGY CO., LTD.) were mixed, heated to 180 ℃ and dissolved, and then cooled to room temperature. An OIL phase was prepared by mixing 5.0 mass% of a phthalocyanine pigment (TOYO INK CO., manufactured by LTD. "LIONOL BLUE FG-7330"), 10.0 mass% of a mineral OIL B (COSMO OIL LUBRICATS CO., manufactured by LTD. "COSMO ALLPUS 460"), and 1.0 mass% of decaglycerol pentaoleate (Nikko Chemicals Co., manufactured by Ltd. "NIKKOL Decaglyn 5-OV"). Except for this, water-in-oil emulsion inks for stencil printing of examples 5 to 8 were prepared in the same manner as in examples 1 to 4, respectively.

[ examples 9 to 12]

Water-in-oil emulsion inks for stencil printing of examples 9 to 12 were produced in the same manner as in examples 1 to 4, except that magnesium sulfate heptahydrate was changed to calcium nitrate tetrahydrate.

[ example 13]

A water-in-oil emulsion ink for stencil printing of example 13 was produced in the same manner as in example 1 except that 13.0 mass% of the alkyd resin was changed to 10.0 mass%, 0.5 mass% of 2-amino-2-methyl-1, 3-propanediol was changed to 0.1 mass%, 1.0 mass% of magnesium sulfate heptahydrate was changed to 0.7 mass%, and 64.5 mass% of ion-exchanged water was changed to 68.2 mass%.

[ example 14]

A water-in-oil emulsion ink for stencil printing in example 14 was produced in the same manner as in example 1 except that 13.0 mass% of the alkyd resin was changed to 16.0 mass%, 0.5 mass% of 2-amino-2-methyl-1, 3-propanediol was changed to 1.5 mass%, 1.0 mass% of magnesium sulfate heptahydrate was changed to 1.5 mass%, and 64.5 mass% of ion-exchanged water was changed to 60.0 mass%.

[ example 15]

A water-in-oil emulsion ink for stencil printing in example 15 was produced in the same manner as in example 1 except that 1.0 mass% of decaglycerol pentaoleate was changed to 0.5 mass% of sorbitan monooleate and 0.5 mass% of sorbitan sesquioleate ("SPAN 83" manufactured by Tokyo Chemical Industry co., ltd.).

[ example 16]

A water-in-oil type emulsion ink for stencil printing in example 16 was prepared in the same manner as in example 1 except that 5.0 mass% of the mineral oil a and 10.0 mass% of the mineral oil B were changed to 10.0 mass% of a vegetable oil (a "rice oil" manufactured by Nisshin oigilroup, ltd.), 1.0 mass% of decaglycerol pentaoleate was changed to 3.0 mass%, 0.5 mass% of 2-amino-2-methyl-1, 3-propanediol was changed to 0.2 mass%, 1.0 mass% of magnesium sulfate heptahydrate was changed to 0.5 mass%, and 64.5 mass% of ion-exchanged water was changed to 68.3 mass%.

[ example 17]

A water-in-oil emulsion ink for stencil printing in example 17 was produced in the same manner as in example 16 except that 3.0 mass% of decaglycerol pentaoleate was changed to 1.5 mass% of sorbitan monooleate and 1.5 mass% of sorbitan sesquioleate ("SPAN 83" manufactured by Tokyo Chemical Industry co., ltd.).

Comparative example 1

A water-in-oil emulsion ink for stencil printing of comparative example 1 was produced in the same manner as in example 1 except that 2-amino-2-methyl-1, 3-propanediol and magnesium sulfate heptahydrate were not added and 64.5 mass% of ion-exchanged water was changed to 66.0 mass%.

Comparative example 2

A water-in-oil emulsion ink for stencil printing of comparative example 2 was prepared in the same manner as in example 5 except that 2-amino-2-methyl-1, 3-propanediol and magnesium sulfate heptahydrate were not blended and 64.5 mass% of ion-exchanged water was changed to 66.0 mass%.

Comparative example 3

A water-in-oil emulsion ink for stencil printing of comparative example 3 was prepared in the same manner as in example 1, except that the alkyd resin was not blended and 10.0 mass% of the mineral oil B was changed to 23.0 mass%.

Comparative example 4

A water-in-oil emulsion ink for stencil printing of comparative example 4 was prepared in the same manner as in example 1, except that 2-amino-2-methyl-1, 3-propanediol was changed to sodium hydroxide.

Comparative example 5

A water-in-oil emulsion ink for stencil printing of comparative example 5 was prepared in the same manner as in example 1, except that the magnesium sulfate heptahydrate was changed to lithium sulfate.

Comparative example 6

A water-in-oil emulsion ink for stencil printing of comparative example 6 was prepared in the same manner as in example 9, except that calcium nitrate tetrahydrate was changed to aluminum nitrate nonahydrate.

< evaluation >

Each of the inks thus prepared was printed with a stencil printing apparatus ("RISOGRAPH RZ 670" manufactured by Ideal Seiko K.K.) at a temperature of 23 ℃ and a relative humidity of 50%, and then left for 1 week. When it was visually confirmed whether or not the ink leaked from the outer periphery of the plate cylinder, the inks of examples 1 to 17 did not leak, whereas the inks of comparative examples 1 to 6 leaked.

From the above results, it can be seen that: each ink of the examples is an ink containing a resin having a carboxyl group in an oil phase and a compound represented by formula (1) and a water-soluble divalent metal salt in an aqueous phase, and therefore, even when a printing apparatus is left unused, the ink can be prevented from leaking out of a plate cylinder of the printing apparatus.

Claims

1. A water-in-oil emulsion ink for stencil printing, comprising:

an oil phase containing an oil-soluble resin having a carboxyl group; and

an aqueous phase comprising a compound represented by the following formula (1) and a water-soluble divalent metal salt,

R-C(CH₂OH)₂-NH₂…(1)

2. The water-in-oil emulsion ink for stencil printing as described in claim 1, wherein the oil-soluble resin having a carboxyl group comprises an alkyd resin or a rosin-modified phenol resin.

3. The water-in-oil emulsion ink for stencil printing as claimed in claim 1 or 2, wherein the ratio of the content of the compound represented by the formula (1) to the water-soluble divalent metal salt is 2: 8-7: 3.