JP2969037B2 - Emulsion ink for stencil printing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an emulsion ink for stencil printing, and more particularly, to an ink having excellent fixability to paper and storage stability, giving a printed image free from bleeding, and capable of leaving a deteriorated ink when left in a drum. The present invention relates to an emulsion ink for stencil printing which does not hang out of a drum and contaminate a printed image or the inside of a machine.

[0002]

2. Description of the Related Art As is well known, a stencil printing method uses a stencil printing paper, and moves ink from one side of the base paper to the other side through a perforated portion of the stencil printing paper, thereby forming a printing material such as paper. This is for printing on the surface. In recent years, rotary stencil printing machines have also been automated by microcomputers and the like, and operation has become simpler.
It is demanded that a good printed matter can be obtained immediately after the start of printing in various environments. In addition, the ink storage conditions may be exposed to high temperatures such as in a tent in summer or shipping during export, in which case the high-temperature stability of the ink is a problem.

Heretofore, solid resins and the like have been added to emulsion inks in order to ensure stability and fixability. For example, by adding three or more resins to Pigment 1 and increasing the oil phase viscosity, the stability and fixability of the ink have been ensured. Also, sorbitan sesquioleate, sorbitan monooleate, and the like have been favorably used as surfactants (Japanese Patent Publication No. 5-62628). But,
These inks require a high-concentration resin in order to increase the stability, and thus have problems such as an increase in the viscosity of the ink and an increase in temperature dependency. In addition, the pigment dispersion stability was poor only with a sorbitan-based low molecular surfactant, and sufficient fixability could not be obtained.

[0004] Further, as a material which dries quickly on plain paper and can prevent image bleeding and ink strike-through, the water phase component is mainly composed of water and an aqueous dye, and the particle size of micelles composed of the water phase component is considered. Pigments such as water-in-oil emulsion ink having a distribution in the range of 0.1 to 20 μm (Japanese Patent Application Laid-Open No. 4-183762) and those which do not cause bleeding on plain paper and provide high quality printing are Including resin emulsion,
The color component contained in the ink has an average particle size of 0.3 to 1.
2 μm inkjet recording ink (Japanese Unexamined Patent Publication No.
No. 332774) has been proposed. However, the particle size of the micelle in the aqueous phase had an effect on permeation only when a dye was used as a coloring material, and the effect using a pigment was insufficient. In addition, since the latter ink is not a W / O emulsion ink but an aqueous ink, the penetration into paper differs from W / O ink having different wettability to paper. That is, in the ink described in Japanese Patent Application Laid-Open No. 4-332774, a resin emulsion is used in combination and the pigment particle size is finely controlled to prevent bleeding. But,
In the case of W / O emulsion ink, due to the physical properties of the ink,
The problem for bleeding is relatively small. W / O emulsion inks have problems of fixability, storage stability, and dripping from a roll. To reduce these problems, simply reducing the particle size of the pigment cannot provide an effect. Therefore, W / O
It was necessary to control the particle size of the pigment in consideration of the particle size of the emulsion.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to eliminate the above-mentioned disadvantages of the prior art, and to provide a rotary stencil printing machine which has excellent fixability and storage stability and gives a printed image free from bleeding. Another object of the present invention is to provide an emulsion ink for stencil printing in which the degraded ink left in the drum does not drip outside the drum and contaminate the printed image or the inside of the machine.

According to the present invention, in a water-in-oil emulsion composed of 10 to 50% by weight of an oil phase and 90 to 50% by weight of an aqueous phase, the particle size of the emulsion in the aqueous phase is 10 μm.
m, and the average particle size of the pigment dispersed in the oil phase is 0.4 μm or less. An emulsion ink for stencil printing is provided, and the average particle size of the pigment is 0.15 μm or more. A stencil printing emulsion ink is provided. In the present invention,
"The average particle size of the pigment dispersed in the oil phase" refers to the
When present in the aggregated state, the average particle of aggregated particles (secondary particles)
The diameter of the primary particles when the pigment is not present in an agglomerated state.
Mean average particle size.

The present inventors have conducted intensive studies to achieve the above object, and as a result, in a water-in-oil emulsion, the particle size of the emulsion in the aqueous phase was 10 μm or less, and the average of the pigment in the oil phase was By making the particle size 0.4 μm or less,
It has been found that an emulsion ink for stencil printing having excellent fixability and storage stability can be obtained. Further, by adjusting the average particle size of the pigment to 0.15 μm or more, ink without bleeding and which has been altered by standing can be removed from the drum. It was found that an emulsion ink for stencil printing could be obtained without dripping onto the printed image or contaminating the inside of the machine.

[0008] The reason is that the average particle size of the pigment is 0.4 μm
By setting the content to be less than the above, the permeability of the pigment to the paper is improved and the fixing property is improved, and by reducing the average particle size, the dispersion state of the pigment is improved and the aggregation of the pigments due to sedimentation of the pigment is performed. , It is estimated that the stability as an ink is improved. Further, the average particle size of the pigment is 0.15.
By controlling the average particle diameter of the pigment to 0.15 μm or more in the dispersed state of the pigment, the oil permeability of the ink can be controlled by controlling the penetration of the pigment into the paper by controlling the pigment to be at least 0.15 μm. Yield value can be given to the phase component, and moisture evaporates on standing, and even the ink that has become only the oil phase can suppress the phenomenon of dripping by having the yield value of the oil phase, which causes problems on the machine. It is presumed to be improved. In addition, since the size of the emulsion affects the permeation speed in the early stage of permeation in which the emulsion destroyed in the permeation process is not destroyed, it is presumed that the emulsion particle size of the aqueous phase is also involved.

Hereinafter, the present invention will be described in more detail. The stencil emulsion ink of the present invention has an oil phase of 10 to 50.
A water-in-oil emulsion composed of 90% by weight and an aqueous phase of 90 to 50% by weight. The oil phase is composed of an oil component, a pigment dispersant, a pigment, an emulsifier, and the like. Therefore, the resin does not have to be contained. The aqueous phase is composed of water, an electrolyte, an antiseptic / antifungal agent, an antioxidant, a water evaporation inhibitor, a water-soluble polymer and the like. Known components that do not inhibit the formation of the emulsion are used as these components.

As the oil component in the oil phase used in the present invention, conventionally known oil components can be applied, for example, mineral oils such as liquid paraffin, spindle oil, light oil, kerosene, machine oil, lubricating oil; olive oil, rapeseed Vegetable oils such as oil, castor oil and soybean oil are used. In the present invention, a synthetic oil can also be used. When using synthetic oils, various compounds are available. Representative synthetic vehicles include polyisobutylenes, hydrogenated polydecenes, trimethylolpropane esters, neopentyl and pentaerythritol esters, di (2-ethylhexyl) sebacate, di (2-ethylhexyl) adipate, dibutyl phthalate, Fluorocarbons, silicon esters, silanes, esters of phosphorus-containing acids, liquid urea, ferrocene derivatives, hydrogenated synthetic oils, linear polyphenyls, siloxanes and silicons (polysiloxanes), butyl-substituted bis Examples thereof include alkyl-substituted diphenyl ethers represented by (p-phenoxyphenyl) ethers and phenoxyphenyl ethers.

The emulsifier used in the present invention is preferably a nonionic surfactant, such as sorbitan higher fatty acid ester, polyoxyethylene sorbitan higher fatty acid ester, fatty acid monoglyceride, fatty acid diglyceride and higher alcohol, alkylphenol, fatty acid and the like. Ethylene oxide adducts of the same type or those having different HLB (hydrophilic-lipophilic balance).
By changing the HLB from 2 to 14 by combining more than one kind,
Prepare a highly stable emulsion.

The pigment dispersant used in the present invention includes:
Emulsions that do not inhibit the formation of emulsions are used, for example, alkylamine-based polymer compounds, aluminum chelate-based compounds, styrene / maleic anhydride-based copolymerized polymer compounds, polyalkyl acrylate partial alkyl esters, polyalkylene polyamines, and aliphatic-based compounds. Polyvalent carboxylic acids, amine salts of high molecular weight polyesters, polyethers, ester type anionic surfactants, long chain amine salts of high molecular weight polycarboxylic acids, salts of long chain polyaminoamides and high molecular weight polyesters, polyamide compounds, phosphoric acid Examples include ester surfactants, alkyl sulfocarboxylates, α-olefin sulfonates, dioctyl sulfosuccinates, and the like.

Examples of the pigment used in the present invention include organic and / or inorganic pigments such as furnace carbon black, lamp black, cyanine blue, cyanine green, lake red, titanium oxide, and calcium carbide. In addition, as the resin used as required in the present invention, a phenol resin, a maleic resin, a petroleum resin, a rubber resin, an alkyd resin, a rosin-modified resin, or the like is used for the purpose of adjusting the viscosity.

As described above, in the present invention, by setting the average particle size of the pigment in the oil phase to 0.4 μm or less, excellent fixability and storage stability can be obtained. In order to improve the fixability, the average particle size of the pigment is preferably set to 0.29 μm or less, and more preferably 0.25 μm or less. Further, the average particle size of the pigment is 0.15.
When the thickness is at least μm, a printed image without bleeding will be given, and even if the image is deteriorated by being left, it will not hang out of the drum and contaminate the printed image and the inside of the machine.

As the anti-evaporation and anti-coagulant in the aqueous phase used in the present invention, polyhydric alcohols such as ethylene glycol, sorbitol and glycerin, and polyethylene glycol are used. As the antiseptic / fungicide, for example, an aromatic hydroxy compound and its chlorine compound, salicylic acid, phenolic acid, methyl p-oxybenzoate, ethyl p-oxybenzoate and the like, sorbic acid, dehydroacetic acid and the like are used. Further, as the electrolyte, for example, sodium sulfate, sodium hydrogen phosphate, sodium borate and the like are used. As an antioxidant such as resin,
For example, dibutylhydroxytoluene, propyl gallate, butylhydroxyanisole and the like are used.

[0016] The aqueous phase may be used a water-soluble polymer for moisturizing or thickening. Specific examples of the water-soluble polymer include, for example, natural polymers such as starch, mannan, sodium alginate, galactan, tragacanth gum, gum arabic, burlan, dextran, xanthan gum, glue, gelatin, collagen, casein; Semi-synthetic polymers such as methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, hydroxymethylstarch, carboxymethylstarch and dialdehyde starch; acrylic resins and acrylic acids such as sodium polyacrylate and triethanolamine polyacrylate Resin derivative, polyvinyl alcohol,
Examples include synthetic polymers such as polyvinylpyrrolidone, polyacrylamide, polyethylene oxide, and polyvinyl methyl ether.

In order to increase the viscosity of the aqueous phase, a thickening accelerator can be used in addition to the water-soluble polymer. For example, as the thickening accelerator used in the case of acrylic acid resin, diisopropanolamine, di-2 (ethylhexyl) amine, triethanolamine, triamylamine, b-dimethylaminopropionitrile, dodecylamine, morpholine Examples thereof include low molecular amines such as phosphorus, alkanolamines, and the like, and inorganic bases such as sodium hydroxide, potassium hydroxide, and ammonium hydroxide.

In preparing the emulsion ink of the present invention, the oil phase is usually prepared by dispersing a pigment using a known disperser and diluting the pigment with oil or another oil phase composition. A known stirrer is usually used for dilution. The aqueous phase is usually mixed with an aqueous phase composition using a stirrer. The completed oil phase and aqueous phase are easily emulsified using a known emulsifier. Production methods and means such as dispersion, dilution, and emulsification can be appropriately changed.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto.
In addition, all the parts shown below are based on weight. Also,
As the colorant furnace carbon black, primary particles
The one with 0.028 μm size as cyanine blue
Used primary particles having a particle size of 0.095 μm.

Example 1 Raw materials having the following formulation were used. (Colorant) Furnace carbon black 4.0 parts (Solvent) Paraffin oil 23.5 parts (Emulsifier) Sorbitan sesquiolate 5.0 parts (HLB = 3.7) (Pigment dispersant) Alkylamine polymer 2.5 parts (Water) Ion exchange water 55.5 parts (Anti-freezing agent) Ethylene glycol 10.0 parts

The pigment dispersion is prepared by kneading the furnace carbon black, paraffin oil and pigment dispersant with three rolls, and adding an emulsifying surfactant and oil to the pigment dispersion, if necessary. A varnish such as a rosin-modified phenolic resin was added to obtain an oil phase, and an aqueous phase was added thereto to emulsify, thereby obtaining an emulsion ink for stencil printing.

Example 2 An emulsion ink for stencil printing was obtained in the same manner as in Example 1 except that the raw materials having the following formulation were used. (Colorant) Furnace carbon black 5.0 parts (Solvent) Paraffin oil 24.5 parts (Emulsifier) Sorbitan sesquiolate 5.0 parts (HLB = 3.7) (Pigment dispersant) Alkylamine polymer 0.5 parts (Water) Ion exchange water 55.0 parts (Anti-freezing agent) Ethylene glycol 10.0 parts

Example 3 An emulsion ink for stencil printing was obtained in the same manner as in Example 1 except that the following ingredients were used. (Coloring agent) Furnace carbon black 5.0 parts (Solvent) Paraffin oil 23.5 parts (Emulsifier) Sorbitan sesquiolate 5.0 parts (HLB = 3.7) (Pigment dispersant) Aluminum chelate compound 1.5 Part (water) ion-exchanged water 55.0 parts (antifreeze) ethylene glycol 10.0 parts

Example 4 An emulsion ink for stencil printing was obtained in the same manner as in Example 1 except that the raw materials having the following formulation were used. (Colorant) Furnace carbon black 5.0 parts (Solvent) Paraffin oil 24.3 parts (Emulsifier) Sorbitan sesquiolate 5.0 parts (HLB = 3.7) (Pigment dispersant) Polymer polyester amine salts 0.7 parts (Water) Ion exchange water 55.0 Parts (antifreeze) Ethylene glycol 10.0 parts

Example 5 An emulsion ink for stencil printing was obtained in the same manner as in Example 1 except that the following ingredients were used. (Coloring agent) Cyanine blue 5.0 parts (Solvent) Paraffin oil 24.0 parts (Emulsifier) Sorbitan sesquiolate 5.0 parts (HLB = 3.7) (Pigment dispersant) Phosphate ester surfactant 1.0 part (Water) Ion exchange water 55.0 parts (Anti-freezing agent) Ethylene glycol 10.0 parts

Example 6 An emulsion ink for stencil printing was obtained in the same manner as in Example 1 except that the following ingredients were used. (Colorant) Furnace carbon black 5.0 parts (Solvent) Paraffin oil 23.5 parts (Emulsifier) Sorbitan sesquiolate 5.0 parts (Pigment dispersant) Aluminum chelate compound 1.5 parts (Water) Ion exchange water 24.17 parts (Water soluble polymer) 1% polyacrylic acid aqueous solution 30.0 parts (thickening accelerator) 10% sodium hydroxide aqueous solution 0.83 parts (antifreeze) ethylene glycol 10.0 parts

Comparative Example 1 An emulsion ink for stencil printing was obtained in the same manner as in Example 1, except that the following ingredients were used. (Coloring agent) Furnace carbon black 4.0 parts (Solvent) Paraffin oil 26.0 parts (Emulsifier) Sorbitan sesquiolate 5.0 parts (HLB = 3.7) (Water) Ion exchange water 55.0 parts (Anti-freezing agent) Ethylene glycol 10.0 parts

Comparative Example 2 An emulsion ink for stencil printing was obtained in the same manner as in Example 1 except that the following ingredients were used. (Colorant) Furnace carbon black 5.0 parts (Solvent) Paraffin oil 25.0 parts (Emulsifier) Sorbitan sesquiolate 5.0 parts (HLB = 3.7) (Water) Deionized water 55.0 parts (Anti-freezing agent) Ethylene glycol 10.0 parts

Comparative Example 3 An emulsion ink for stencil printing was obtained in the same manner as in Example 1 except that the raw materials having the following formulation were used. (Colorant) Furnace carbon black 5.0 parts (Solvent) Paraffin oil 25.5 parts (Emulsifier) Sorbitan sesquiolate 3.0 parts (Pigment dispersant) Aluminum chelate compound 1.5 parts (Water) Ion exchange water 24.17 parts (Water soluble polymer) 1% polyacrylic acid aqueous solution 30.0 parts (thickening accelerator) 10% sodium hydroxide aqueous solution 0.83 parts (antifreeze) ethylene glycol 10.0 parts

(Evaluation) With respect to the stencil emulsion ink obtained above, the average particle size of the pigment in the oil phase was measured, and printing was performed using these inks. The evaluation and calculation of the fixing rate of the ink were performed, and the storage stability of the ink was evaluated. Further, ink dripping in the drum was evaluated. The evaluation and measurement methods are as follows. The results are shown in Table 1.

Average particle size of pigment in oil phase Laser particle size analysis system LPA- manufactured by Otsuka Electronics Co., Ltd.
3000, HORIBA, Ltd. particle size distribution analyzer LA-7
Using a sample No. 00, the sample ink was diluted in a paraffinic solvent and measured. Bleeding of printed matter Using these inks, printing was sufficiently performed with a commercially available stencil printing machine (VT3500, manufactured by Ricoh Co., Ltd.) to spread the inks into the printing machine, and then printing was performed. Bleeding was evaluated using the printed matter at this time. Fixing rate of ink The print density of the printed matter was measured by a reflection optical densitometer (RD914 manufactured by Macbeth Co.), and the part where the density was measured was reciprocated 10 times with a clock meter equipped with an eraser.
The density after erasing in 10 seconds was also measured, and the ink fixing rate was determined from (density after erasing) / (print density). Storage stability of the ink 1 g of the ink was put into a centrifugal sedimentation tube, and the storage stability was evaluated from the oil separation rate when centrifuged at 6,300 G. Drip of ink in the drum Place the ink on two rolls (5 cm and 1.5 cm in diameter), turn each roll 10 times, and leave it for about a week.
Evaluation was made based on the degree of ink dripping from the roll. The particle size of the emulsion was measured using Cryo-SEM (manufactured by Hitachi, Ltd.).

[0032]

[Table 1] 〇: good ×: bad

From the results shown in Table 1, when the particle size of the emulsion in the aqueous phase is 10 μm or less and the average particle size of the pigment in the oil phase is 0.4 μm or less, the fixing property and the storage stability of the ink become poor. When the average particle diameter is in the range of 0.15 to 0.4 μm, a print image without bleeding is obtained, and the deteriorated ink drips out of the drum by leaving the print image and the inside of the machine. It can be seen that there is no contamination. Furthermore, the average particle size is 0.29 μm or less,
It can be seen that when the thickness is 25 μm or less, the fixability of the ink is further improved.

[0024]

The emulsion ink for stencil printing according to claim 1, wherein the particle size of the emulsion in the aqueous phase is 10 μm or less, and the average particle size of the pigment dispersed in the oil phase is 0.4 μm.
Based on the following, it is excellent in fixability to paper and storage stability.

The stencil printing emulsion ink according to claim 2 has an average particle size of the pigment in the range of 0.15 to 0.4 μm, so that it provides a print image with no further bleeding, In addition, there is an effect that the deteriorated ink that has been left as it is does not hang out of the drum and contaminate the printed image and the inside of the machine.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C09D 11/00-11/14

Claims (3)

(57) [Claims] 1. An oil phase containing a pigment dispersant in an amount of 10 to 50% by weight.
Water-in-oil emulsion composed of 90% to 50% by weight of an aqueous phase, the particle size of the aqueous phase emulsion is 10%.
An emulsion ink for stencil printing, wherein the average particle diameter of the pigment dispersed in the oil phase is 0.4 μm or less. 2. The stencil printing emulsion ink according to claim 1, wherein the pigment has an average particle size of 0.15 μm or more. 3. The stencil printing emulsion ink according to claim 1, wherein the oil phase does not contain a resin component.