JP2001181541A - Emulsion ink and printing process using this - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-in-oil emulsion ink for stencil printing, especially for heat-sensitive stencil printing which has an excellent shelf stability, allows no blur of images nor set-off, shows an excellent adhesion, allows no run of ink images caused by waterdrops and yields a clear printed image, and a printing process using this. SOLUTION: The water-in-oil emulsion ink for stencil printing contains a photocurable compound component within its oil phase (outer phase) and a colorant component within its oil phase and aqueous phase (inner phase).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a water-in-oil emulsion ink for stencil printing and a stencil printing method using the same.

[0002]

2. Description of the Related Art As is well known, a stencil printing method uses a stencil sheet for stencil printing, forms an image pattern by finely perforating the stencil sheet to form a printing plate, and passes the printing plate from one side to the other through the printing plate. The printed matter is obtained on the printing medium by moving the ink toward the printing medium such as paper. Further, in recent years, a heat-sensitive stencil printing method of perforating with a thermal head or the like has been widely performed.

[0003] Rotary heat-sensitive stencil printing presses include a two-body type having a blanket and a single-body type having no blanket. In the former case, using a soft ink does not cause much trouble, but in the latter case, if a soft ink is used, the ink is supplied unnecessarily and the show-through easily occurs, or the ink is applied to the master rear end. Various problems occur such as leaking press rollers and soiling of printed matter. In addition, a high boiling point solvent is used in the conventionally used emulsion ink in order to prevent the perforated portion from being clogged by drying on the plate cylinder while being left on the machine. However, when this ink is left in the printing press,
Only the water in the ink evaporates, the ink viscosity decreases, or the ink softens, and the print density becomes higher than normal,
A drawback occurs in which show-through and image bleeding occur.

[0004] Various proposals have conventionally been made to improve such disadvantages. For example, JP-A-61-2
Japanese Patent Application Laid-Open No. 63-27569 discloses an ink in which a medium-boiling solvent is contained in an ink to evaporate oil while evaporating water to maintain a balance between an oil phase and an aqueous phase. Japanese Patent Application Laid-Open No. 63-277287 discloses a composition in which a carboxylic acid is contained to control the viscosity.
Japanese Patent Application Publication No. 3-4137 discloses an ultraviolet curable ink containing no water and containing an acrylic resin powder.
Japanese Patent Application Laid-Open No. 2-8 discloses an ultraviolet curable ink containing no water and containing silicone oil.
No. 6,667, proposes a device using powdered ink.

Japanese Patent Application Laid-Open No. Hei 4-233980 discloses a method in which an oil phase is gelled to have properties as thixotropic and ink viscosity is stabilized.
No. 29 discloses that the ink contains a salt of a carboxylic acid derivative of pyrrolidone having a high hygroscopic property or uses an oil having a small surface tension as an oil phase so that the viscosity of the ink is not changed and the contact leakage between the paper and the ink is reduced. Which improved ink penetration into paper,
JP-A-5-247397 discloses an oil phase containing a volatile solvent having an initial distillation point of 150 to 210 ° C.
In Japanese Patent Application Laid-Open No. HEI 6-172691, JP-A-6-172691 discloses a method of reducing the yield value by adding a cyclized rubber to ink and reducing the fluidity at high shear. It has been proposed to include them.

As described above, various inks have been proposed for use in general heat-sensitive stencil printing. However, in a rotary-type heat-sensitive stencil printing machine, the ink leaks from a plate cylinder when the ink is left on the printing machine. The colorant is required to be hard when the printing machine is stationary so as not to contaminate the inside, and to be soft during operation so that the ink sufficiently passes through the fine holes of the perforated stencil sheet at the time of printing. ,solvent,
An emulsion ink composed of an oil phase and an aqueous phase, which is composed of an emulsifier, an emulsifier, or water, is often used.
In particular, in the case of high-speed printing with a rotary rotary stencil printing machine, since the drying and fixing properties of the ink are further required, a photocurable emulsion ink using a photocurable compound that can be cured instantaneously has been proposed. ing. For example, JP-A-8-3
No. 501 proposes an emulsified ultraviolet curable ink in which a water phase mainly composed of water, which does not contain a colorant, is added to a conventional oil-based ultraviolet curable ink containing a colorant.

However, despite these proposals,
Problems still remain in the drying and fixing properties of the ink during high-speed printing in a rotary rotary stencil printing machine. In particular,
As can be seen from the above-mentioned ultraviolet-curable ink, the conventional photocurable emulsion ink contains a colorant in the continuous phase of the external phase, so that the ink is irradiated with light such as ultraviolet rays when fixing and drying the ink. However, there is a problem that the colorant acts as a filter and blocks light, and the light cannot penetrate sufficiently to the inside of the ink and cannot be fixed and dried (cured) effectively. In addition, there has been a problem of blurring or show-through of the image. Furthermore, in recent years, with the progress of computer and other technologies, the printing press body and peripheral devices have made remarkable progress, and higher speeds have been required than ever before, and improvements in these problems have been demanded.

[0008]

SUMMARY OF THE INVENTION According to the present invention, stencil printing can be performed satisfactorily without image bleeding or show-through and without leakage of ink, storage stability is high, and water droplets after printing are reduced. An object of the present invention is to provide an emulsion ink for stencil printing having high stability, in which an ink image hardly flows even when attached, and a stencil printing method using the same.

[0009]

As described above, a conventional water-in-oil type ink for stencil printing in which a water phase not containing a colorant component is added to an oil-based ultraviolet curable ink (oil phase) containing a colorant component as described above. Emulsion inks have problems such that light reaches only the surface layer due to self-absorption (shielding action) of the colorant during fixing and drying of the ink by light irradiation, and uncured and curing speed is slow.

Therefore, the present inventor has previously proposed a water-in-oil droplet for stencil printing in which the photocurable compound component is contained only in the oil phase (outer phase) and the colorant component is contained only in the aqueous phase (inner phase). Type emulsion ink (Japanese Patent Application No. 10-8793)
No. 7). However, although this ink should solve the problem of self-absorption of light by the colorant component, it has surprisingly still not a sufficiently high curing speed, and has a problem that solid images are poorly buried. are doing.

The present inventor has solved the above-mentioned problems of the conventional water-in-oil type emulsion ink for stencil printing, and as a result of intensive studies to achieve the above object, as a result, the water-in-oil type emulsion composed of an oil phase and an aqueous phase. In the ink, the curing rate of the ink is increased by including a photocurable compound component in the continuous oil phase (outer phase) and a colorant component in both the oil phase and the aqueous phase (inner phase). The present invention has been found to be able to increase the speed, to provide excellent fixing and drying properties, to provide a clear image with no show-through, and to be able to fill solid images well, thereby completing the present invention.

That is, according to the present invention, first, in a water-in-oil emulsion ink for stencil printing containing a colorant component and a photocurable compound component, the photocurable compound component is contained in an oil phase (outer phase). The present invention provides a water-in-oil emulsion ink for stencil printing, wherein a colorant component is contained in an oil phase and an aqueous phase (inner phase). Secondly, the water-in-oil emulsion ink for stencil printing, wherein the colorant component in the aqueous phase comprises an aqueous dye or an aqueous-treated pigment. Is provided. Third, the water-in-oil emulsion ink for stencil printing is provided, wherein the colorant component in the aqueous phase comprises a pigment obtained by subjecting the pigment of the colorant component in the oil phase to an aqueous treatment. Fourth, the water-in-oil emulsion ink for stencil printing according to any one of the above, wherein the aqueous phase is gelled. Fifth, the stencil plate according to any one of the above, wherein the photocurable compound component in the oil phase is at least one type of photocurable compound selected from the group consisting of acrylic monomers, oligomers, and polymers. A water-in-oil emulsion ink for printing is provided. Sixth, there is provided the water-in-oil emulsion ink for stencil printing according to any of the above, wherein the oil phase contains an oil having a boiling point of 150 ° C. or higher. Seventh, there is provided a water-in-oil emulsion ink for stencil printing according to any one of the above, wherein a nonionic surfactant is contained in the oil phase. Eighth, a step of imagewise perforating a stencil sheet for thermal stencil printing using a thermal head or a laser beam having a heating action, a step of setting the perforated stencil sheet on a stencil printing plate cylinder, a perforating section of the stencil sheet A stencil comprising a step of passing the water-in-oil emulsion ink according to any one of the above, a step of transferring the passing ink to printing paper, and a step of irradiating the transferred ink with an electromagnetic wave containing ultraviolet rays. A printing method is provided.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
Like a general water-in-oil emulsion ink, the water-in-oil emulsion ink containing the colorant component and the photocurable compound component of the present invention also has an oil phase composed of an oil component and an aqueous phase composed of an aqueous component. The oil phase and the aqueous phase are dispersed and emulsified by adding an appropriate emulsifier, and have a water phase component having an oil phase component in an outer phase that is a continuous phase and an aqueous phase component in a droplet-shaped inner phase. In the form of an emulsion. Usually, the water-in-oil type emulsion ink of the present invention is 10 to 70%.
It is preferable to use an emulsion ink in which 90 to 30% by weight of an aqueous phase component is added to a weight% of an oil phase component and dispersed and emulsified.

The emulsion ink of the present invention has a basic constitution comprising a high boiling solvent as an oil phase component, water as an aqueous phase component, an emulsifier, a coloring material for coloring, and a photocurable compound. In this case, the high boiling point solvent is an inert solvent that does not substantially contribute to photocuring. A part or all of the high boiling point solvent may be replaced with a photocurable compound and used as an oil phase. In addition, viscosity control, water volatilization suppression, aqueous gel, additives for preventing freezing, fungicides, antioxidants, or dispersants for dispersing colorant components, photopolymerization initiators, reaction acceleration As necessary, a sensitizer for imparting thixotropy, a white colorant for imparting thixotropy, an additive for improving stability over time, and the like. These may use known compounds.

In the present invention, the photocurable compound component is contained in a continuous external phase. Further, the colorant component is contained in both phases in the droplets of the external phase and the internal phase. The reason why the water-in-oil type emulsion ink of the present invention can achieve the above object of the present invention is considered as follows. That is, it is particularly clear when the emulsion ink of the present invention is compared with the conventional emulsion ink in which the colorant component is present only in the external phase “with the same pigment content of the entire ink”. For example, when the pigment content of the whole water-in-oil type emulsion ink in which the volume ratio of the oil phase and the water phase is 50/50 is 5% by volume, the “water-in-oil type emulsion ink of the present invention” has the oil phase And the aqueous phase has a pigment content of 5% by volume. However, in the “conventional water-in-oil type emulsion ink in which the coloring component is present only in the external phase”, the pigment content of the oil phase and the pigment content of the aqueous phase are 10% by volume and 0% by volume, respectively, and contain the photocurable compound component. Since the pigment content of the oil phase component increases, the light transmittance decreases, which is inconvenient for photocuring. Therefore, the ink of the present invention is
As compared with the “conventional emulsion ink in which only the color component is present in the external phase”, light that acts on curing can be transmitted to the inside of the ink film, so that the photocurable compound component can be cured with a smaller amount of light. In this manner, the emulsion ink of the present invention allows the curing reaction of the photocurable compound component to proceed sufficiently and effectively.

When the emulsion ink of the present invention is compared with the emulsion ink in which the colorant component is present only in the inner phase of the prior application, the reason is not clear. Compared to the emulsion ink of the application, although the curing speed is expected to be slow due to the filter effect of the colorant component present in the external phase, the curing speed is surprisingly fast, and photocuring with a smaller amount of light The active compound component can be cured. Furthermore, although the reason is unknown, the emulsion ink of the present invention is
As compared with the emulsion ink of the prior application, the solid image has good filling properties.

The emulsion ink of the present invention is
Since the evaporation of water can be suppressed by using the continuous phase of the external phase as the oil phase, the storage stability over a long period of time and the storage stability are excellent.

In the present invention, as the photocurable compound, a known compound having a double bond can be used. Examples include those that are cured by irradiation with ultraviolet light or the like described in “Yoneho Tabata, Radox Kenkyukai” supervised by “Application of UV / EB curing technology and market”. As the photocurable compound, it is particularly preferable to use an ultraviolet curable resin (UV resin) such as an acrylic monomer, oligomer, or polymer. Examples of such a photocurable compound include the following. Styrene, vinyltoluene, α-methylstyrene, chlorostyrene,
Monovinyl compounds such as 2-vinylpyridine, methyl methacrylate, n-butyl methacrylate, glycidyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, acrylic acid, and methacrylic acid;
Divinylbenzene, ethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, dimethacrylate of polyethylene glycols, neopentyl glycol dimethacrylate, neopentyl glycol diacrylate, 1,3-butylene glycol dimethacrylate,
1,3-butylene glycol diacrylate, 1,6 hexanediol methacrylate, divinyl compounds such as 1,6 hexanediol diacrylate, trimethylolethane trimethacrylate, trimethylolpropane trimethacrylate, trivinyl compounds such as trimethylolpropane triacrylate, Tetravinyl compounds such as tetramethylolmethanetetramethacrylate and tetramethylolmethanetetraacrylate, and vinyl compounds derived therefrom. These photocurable compounds can be used alone or in combination of two or more.

The compounding amount of the photocurable compound component is 20 to 90% by weight, preferably 3% by weight, based on the total solid content of the ink.
0 to 80% by weight. If the amount is less than this, the curability becomes poor. If it is more than this, the properties of the emulsion ink are not maintained.

Known photopolymerization initiators and sensitizers are added to the photocurable compound. Preferably, they are added to the phase to which the photocurable compound has been added. The addition amount of the photopolymerization initiator is 60 to 2% by weight, preferably 40 to 5% by weight based on the total amount of the photocurable compound. The addition amount of the sensitizer is 50 to 1% by weight, preferably 20 to 10% by weight based on the photopolymerization initiator.

Examples of such a photopolymerizable initiator include 2-
Hydroxy-2-methyl-1-phenylpropane-1-
On, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenyl ketone, 2
-Methyl-2-morpholino (4-thiomethylphenyl)
Acetophenone ketals such as propyn-1-one and 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone, benzophenones such as benzophenone and methyl o-benzoylbenzoate, and benzoin ethers such as benzoin isobutyl ether. System, 2,4-
Thioxaton-based acylphosphine oxides such as diethyloxanthon, and special systems such as camphorquinone are exemplified.

As sensitizers, triethanolamine,
Methyldiethanolamine, isoamyl 4-dimethylbenzoate, 4,4-diethylaminobenzophenone, N,
Known sensitizers such as N-dimethylaminoethyl methacrylate are exemplified.

As described above, an inert solvent which does not contribute to photocuring can be used as the oil phase component of the present invention. Examples of the solvent include vegetable oils such as castor oil, linseed oil, tall oil, and soybean oil; petroleum oils such as machine oil and spindle oil; and high-boiling and medium-boiling oils obtained by separating and purifying these oils. Synthetic oils can also be used, and these may be used as a mixture. Among the preferred solvents are machine oils, ISO
15 to 1000 in VG display, more preferably 32 to 22
0. As a guide when mixed and used, the distillation range is 150 ° C. or higher, preferably 180 ° C. or higher as indicated by the initial boiling point. In the present invention, since the solvent is usually contained in a smaller amount than the photocurable compound, a high-viscosity one may be used, and the initial boiling point may be close to 150 ° C. The mixed solvent can be selected, but is determined by the properties of the ink, the properties of the finished printed matter, and the like. Such solvents include Isopar G, Isopar H, Isobar L, Isopar M, Exozol D130 (Exxon), White Spirits Laws, Shellsol 7
0, Shellsol MC331 (Shell Oil), Moresco White P-100, P-200, P-300P (Matsumura Oil), Gargoyle SHC226, SHC230, SH
C234 (Mobile Oil) and the like.

Further, a resin which is not cured by light may be added to the water phase and / or the oil phase. The resin component can be added for the purpose of dispersing the colorant, fixing the colorant to the printing medium, and the like. Examples of such a resin include oil-based resins such as rosin-modified phenol resin, alkyd resin, and phenol resin, and water-soluble resins.

As the coloring agent, known dyes and pigments or dyes and pigments subjected to aqueous treatment can be used. The aqueous-treated pigment can be obtained, for example, by kneading the pigment with an aqueous resin or, more recently, increasing the hydrophilicity by subjecting the pigment surface to hydrophilic treatment with plasma or the like. Specific examples include pigments, black ink, and aqueous dispersions of fine carbon particles for ink-jet, which are dispersed in an aqueous acrylic resin. When a pigment having relatively poor hydrophilicity is contained in the aqueous phase, an auxiliary may be added for dissolution or dispersion.
Such adjuvants include, for example, glycols such as ethylene glycol and diethylene glycol, polyhydric alcohols such as glycerin, pentaerythritol and sorbit, monoethanolamine, diethanolamine,
Examples include amino alcohol amines such as triethanolamine. The content of the colorant with respect to the total amount of the ink is 0.5 to 20% by weight. In the present invention, since pigments are contained in the oil phase and the aqueous phase, it is preferable that the same kind of pigment is contained in each phase as much as possible because of necessity of uniform color tone.
For example, if fine oil is contained in the oil phase, it is preferable that the fine carbon is subjected to aqueous treatment and then contained in the aqueous phase by containing an aqueous black dye in the aqueous phase.

As described above, in the water-in-oil emulsion ink of the present invention, the photocurable compound component is added to the oil phase, and the colorant is added to both the oil phase and the aqueous phase.
An oily colorant is added to the oil phase, and an aqueous colorant or an oily one is added to the aqueous phase by aqueous treatment. In this case, the aqueous phase is gelled because of the destruction of the emulsified oily water. It is preferable from the viewpoint of preventing separation or from the viewpoint that the loosening of the ink due to the volatilization of water in the aqueous phase can be controlled. Furthermore,
It is preferable that the pigment and the dye are fixed in the aqueous gel particles. That is, a form in which the colored aqueous gel particles are present in the oil phase is preferable.

Various known gelling agents can be used.
It may be added for the purpose of increasing the viscosity of the ink in addition to the gelling effect. Such gelling agents include starch, mannan, sodium alginate, tran gum, gum arabic, pullulan, dextran, glue, and the like in aqueous polymers.
Natural polymers such as collagen and casein; modified celluloses such as carboxymethylcellulose, methylcellulose, hydroxyethylcellulose and hydroxymethylstarch;
Or modified starch; polyacrylic acid derivatives such as polyacrylic acid, sodium polyacrylate, and triethanolamine polyacrylate; and synthetic polymers such as polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, polyethylene oxide, and polyvinyl methyl ether. .

According to the present invention, an emulsifier may be contained in the oil phase. As such an emulsifier, any known emulsifier can be used, and nonionic surfactants such as sorbitan fatty acid ester, glycerin fatty acid ester, and polyglycerin fatty acid ester are particularly preferable. The addition amount is preferably 20% by weight or less based on the total amount of the ink solids.

To produce the water-in-oil emulsion ink of the present invention, for example, an aqueous phase obtained by mixing or dispersing or dissolving an aqueous treatment pigment or aqueous dye in water together with other additives is mixed with a solvent and a coloring agent. A photocurable compound, a photopolymerization initiator, and other additives are mixed and dispersed, and if necessary, a solvent is added to the mixed or dispersed or dissolved oil phase, followed by stirring and emulsification. The water can be similarly produced by replacing the water with an aqueous gel. Known emulsifiers and dispersers can be used.

The process using the ink of the present invention is not limited to stencil printing and screen printing, but can also be applied to printing processes such as letterpress, intaglio or gravure printing. Taking the stencil printing process as an example, a thermosensitive sheet for stencil mainly composed of a thermoplastic film is pierced using a thermal head or a laser beam having a heating action to form an image pattern composed of an aggregate of fine perforations. Printing plate. This printing plate is set, for example, on a plate cylinder of a rotary stencil printing machine, ink is supplied from the inside, and when printing pressure is applied through paper, the ink is transferred from the perforated portion of the plate, and an image corresponding to the perforation pattern is obtained as a printed material. Can be When an electromagnetic wave or light corresponding to the excitation wavelength of the photopolymerization initiator is applied to the printed matter immediately after being obtained, the photocurable compound is polymerized and the ink is rapidly dried and fixed.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments. Parts represent parts by weight. % Represents% by weight.

Example 1 (Ink containing an oil phase and an aqueous phase containing a blue pigment) <Aqueous phase> 15 parts of an aqueous blue pigment (micropigmo, about 2.0% pigment, manufactured by Orient Chemical Co.) containing an aqueous resin was used. And 105 parts of a 1.0% gel of triethanolamine polyacrylate (solvent water: ethylene glycol = 6: 1) and stirred to obtain an aqueous phase component consisting of 120 parts of a colored gel containing 3 parts of a pigment. Was. <Oil phase> Blue pigment (copper phthalocyanine, manufactured by Toyo Ink Co., Ltd.), spindle oil, and emulsifier (sorbitan triolate) were mixed in a weight ratio of 30:20:40, kneaded with three rolls, and 90 parts of the primary dispersion was mixed. Obtained. Next, the primary dispersion, the UV resin (Ecolacoat 200DA, manufactured by Material Science) and the spindle oil were mixed at 9:60:11 (parts).
To obtain 80 parts of a colored oil phase component containing 3 parts of a blue pigment. <Emulsion> 80 parts of the oil phase was stirred, and 120 parts of the aqueous phase was added little by little to the mixture.
200 parts water-in-oil emulsion ink having a ratio of 6/4, a UV resin content of the oil phase of 75%, a pigment content of 3.75%, and a pigment content of the aqueous phase of 2.5%. Was. The UV resin content of the entire ink is 30%, and the colorant content is 3.0%.

Comparative Example (Ink containing pigment only in oil phase) <Aqueous phase> 1.0% triethanolamine polyacrylate
Gel (solvent water: ethylene glycol = 6: 1) 120
A non-colored aqueous phase component was obtained. <Oil Phase> A primary dispersion was prepared in the same manner as in Example 1 except that 6 parts of a blue pigment obtained by mixing a UV resin and spindle oil were mixed.
0 parts of an oil phase component were obtained. <Emulsion> A water-in-oil type emulsion ink having a W / O ratio of 6/4, a UV resin content of the oil phase of 75%, a pigment content of 7.5%, and no pigment in the water phase was obtained. Was. The UV resin content of the entire ink is 30%, and the colorant content is 3.0%.

Table 1 below shows the UV resin and pigment content in each of the oil phase and the aqueous phase of Example 1 and Comparative Example. Both contain the same amount of UV resin and pigment in the whole ink,
In Example 1, since a part of the pigment was contained in the aqueous phase, the pigment content of the oil phase was lower than that of the comparative example.

[0035]

[Table 1]

The inks of Example 1 and Comparative Example were coated on a PET film using a film applicator having a gap of 25.4 μm to form an ink film. Using a UV irradiation device (80 W / cm, distance 10 cm),
Exposure at an energy of 50 mj / cm ² (365 nm) yielded a blue ink cured film. In Example 1, the ink film was cured not only on the surface but also on the inside. However, when the sample of the comparative example was touched by hand, the surface of the ink film was cured, but the inside was in an uncured state. Is easy to tear.

Example 2 (Ink containing black pigment in oil phase and aqueous phase) <Aqueous phase> The aqueous blue pigment of Example 1 was replaced with an aqueous black pigment containing no aqueous resin (Microjet C type, about 20% pigment) (Manufactured by Orient Chemical Co., Ltd.) to obtain an aqueous phase component consisting of 120 parts of a colored gel containing 3 parts of a pigment. <Oil phase> A primary dispersion was obtained in the same manner as in Example 1 except that carbon was used as the pigment. The UV resin and the spindle oil were mixed to obtain 80 parts of a colored oil phase component containing 3 parts of a black pigment. <Emulsion> As in Example 1, the W / O ratio was 6 /
4. UV resin content of oil phase is 75%, pigment content is 3.
75% and the aqueous phase has a pigment content of 2.5% 20
0 parts of a water-in-oil emulsion ink was obtained. The colorant content of the entire ink is 3.0%.

Example 3 (Ink with different oil type) <Aqueous phase> In the same manner as in Example 1, an aqueous phase component consisting of 120 parts of a colored gel containing 3 parts of an aqueous blue pigment was obtained. <Oil phase> A primary dispersion was obtained in the same manner as in Example 1, except that a paraffinic oil (initial boiling point: 190 ° C) was used instead of the spindle oil. This is mixed with the following UV resin and polymerization initiator U
V resin (Arakawa Chemical Co.) Pozoacrylate monomer (Beamset 720) 50 parts Polyurethane acrylate oligomer (Beamset 550B) 45 parts Benzophenone (polymerization initiator) 5 parts Mixed paraffinic oil (initial boiling point 156 ° C, 190 ° C, 22
A solvent consisting of a 6 ° C. solvent and a weight ratio of 1: 2: 2) was mixed to obtain 80 parts of an oil phase component containing 3 parts of a blue pigment. The viscosity of the primary dispersion decreased, and the emulsification operation became easy. <Emulsion> An emulsion ink comprising the above oil phase and aqueous phase was prepared in the same manner as in Example 1.

The inks of Examples 1 to 3 and Comparative Example were mounted on a rotary stencil printing machine (manufactured by Preport, Ricoh) and printed on plain paper to obtain printed matter. The printed matter was a clear image without image bleeding. An ultraviolet irradiation device (80 W
/ Cm, at a distance of 10 cm), irradiating 80 mJ / cm ² of ultraviolet light, rolling a rubber roller of about 300 g over white paper, applying a printing pressure, and examining show-through. Also, one week later, there was no ink leakage from the plate cylinder,
Table 2 also shows the ink stability after standing at room temperature for a week. Further, Table 2 also shows the result of observing the water resistance by spraying water on the printing surface by spraying. Insufficient curing causes alcohol and water phase ink to flow.

[0040]

[Table 2]

[0041]

The water-in-oil emulsion ink for stencil printing of the present invention has high storage stability, excellent fixability to a printing medium, and excellent drying properties, has no image bleeding or set-off, and is free from ink droplets. There is no leakage or ink flow, and a clear printed image can be given. The emulsion ink of the present invention can be suitably used for heat-sensitive stencil printing.

Claims (8)

[Claims] 1. A water-in-oil emulsion ink for stencil printing containing a colorant component and a photocurable compound component, wherein the photocurable compound component is contained in an oil phase (outer phase), and the colorant component is contained in an oil phase. A water-in-oil emulsion ink for stencil printing, characterized by being contained in an aqueous phase (inner phase). 2. The colorant component in the aqueous phase comprises an aqueous dye or an aqueous-treated pigment.
A water-in-oil emulsion ink for stencil printing according to the above. 3. The water-in-oil emulsion ink for stencil printing according to claim 2, wherein the colorant component in the aqueous phase is a pigment obtained by subjecting the pigment of the colorant component in the oil phase to an aqueous treatment. . 4. The water-in-oil emulsion ink for stencil printing according to claim 1, wherein the aqueous phase is gelled. 5. The photocurable compound component in the oil phase is at least one type of photocurable compound selected from the group consisting of acrylic monomers, oligomers, and polymers. The water-in-oil emulsion ink for stencil printing according to any one of the above. 6. The water-in-oil emulsion ink for stencil printing according to claim 1, wherein an oil having a boiling point of 150 ° C. or higher is contained in the oil phase. 7. The water-in-oil emulsion ink for stencil printing according to claim 1, wherein a nonionic surfactant is contained in the oil phase. 8. A step of perforating a thermal stencil sheet for image formation by a thermal head or a laser beam having a heating action, a step of setting the perforated plate for stencil printing on a stencil plate cylinder, and a step of perforating the base paper. A step of passing the water-in-oil emulsion ink according to any one of claims 1 to 7, transferring the passed ink to printing paper, and irradiating the transferred ink with an electromagnetic wave containing ultraviolet light. A stencil printing method, characterized in that: