JPH07179799A - Stenciling emulsion ink - Google Patents

Abstract

PURPOSE:To obtain the subject ink excellent in settability onto paper and preservability and capable of giving blur-free printed images, consisting of a water-in-oil emulsion with the emulsion particle size dispersed in the aqueous phase and the particle size of a pigment dispersed in the oily phase specified, respectively. CONSTITUTION:This ink is composed of 10-50wt.% of an oily phase and 90-50wt.% of an aqueous phase. In the ink, the diameter of the emulsion particles in the aqueous phase is <=10mum, and the average particle diameter of a pigment dispersed in the oily phase is <=0.4mum. The oily phase, for example, comprises an oily component such as paraffin oil, a pigment dispersant such as an alkylamine-based high-molecular compound, a pigment such as furnace carbon black and an emulsifier such as sorbitan sesquioleate; while, the aqueous phase, for example, comprises water, an electrolyte such as sodium sulfate, an antiputrefaction/antifungal agent and an antievaporating/antifreezing agent such as ethylene glycol.

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 specifically, it has excellent fixability on paper and storage stability, gives a printed image without bleeding, and is an ink which is deteriorated by being left in a drum. The present invention relates to an emulsion ink for stencil printing that does not drip outside the drum and contaminate the printed image or the inside of the machine.

[0002]

2. Description of the Related Art As is well known, a stencil printing method uses a stencil printing base paper, and by moving ink from one side of the base paper to the other side through a perforation portion of the base paper, a printing material such as paper is printed. Printing is performed on the surface. In recent years, rotary stencil printing machines have become more automated with microcomputers, etc., and have become easier to operate.
It is desired that good printed matter can be obtained immediately after starting printing in various environments. In addition, the ink storage conditions may be exposed to high temperatures such as in summer tents and shipping during export, and at that time, high temperature stability of the ink becomes a problem.

In the past, solid resins and the like have been added to emulsion inks in order to ensure stability and fixability. For example, by adding 3 or more resins to Pigment 1 to increase the oil phase viscosity, stability and fixing property of the ink have been secured. Further, sorbitan sesquioleate, sorbitan monooleate and the like have been favorably used as the surfactant (Japanese Patent Publication No. 5-62628). But,
Since these inks require a high concentration of resin in order to increase stability, there are problems that the viscosity of the ink becomes high and the temperature dependence becomes large. Further, the sorbitan-based low-molecular-weight surfactant alone has poor pigment dispersion stability, and in addition, sufficient fixability cannot be obtained.

Further, as a material that dries faster than plain paper and can prevent image deletion 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. A water-in-oil type emulsion ink having a distribution in the range of 0.1 to 20 μm (JP-A-4-183762) and plain paper, which does not cause bleeding and can provide high-quality printing, can be used as a pigment. Including resin emulsion,
The average particle diameter of the coloring component contained in the ink is 0.3 to 1.
Ink for inkjet recording having a thickness of 2 μm
No. 332774) has been proposed. However, the particle size of the micelle in the aqueous phase was effective for permeation only when the dye was used as the coloring material, and the effect was insufficient in the system using the pigment. Further, since the latter ink is not a W / O type emulsion ink but a water-based ink, the penetration into paper is different from that of W / O ink having different wettability to paper. That is, in the ink described in Japanese Patent Laid-Open No. 4-332774, a resin emulsion is used in combination, and the particle size of the pigment is finely adjusted to prevent bleeding. But,
In the case of W / O emulsion ink, due to the physical properties of the ink,
The problem with bleeding is relatively small. The W / O type emulsion ink has problems of fixing property, storage stability, and dripping from a roll, and these problems cannot be obtained only by reducing the particle size of the pigment. 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 Therefore, an object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to provide a printed image having excellent fixability and storage stability in a rotary stencil printing machine, and further having no bleeding, Another object of the present invention is to provide an emulsion ink for stencil printing in which the ink that has been left in the drum and deteriorated does not drip outside the drum and contaminate the printed image or the inside of the machine.

[0006]

According to the present invention, in a water-in-oil emulsion composed of about 10 to 50% by weight of an oil phase and about 90 to 50% by weight of an aqueous phase, the particle size of the emulsion in the water phase is 10 μm. Provided is an emulsion ink for stencil printing, wherein the average particle size of the pigment dispersed in the oil phase is 0.4 μm or less, and the average particle size of the pigment is 0.15 μm or more. An emulsion ink for stencil printing is provided.

The present inventors have conducted extensive studies to achieve the above object, and as a result, in the water-in-oil emulsion, the particle size of the emulsion in the water phase was 10 μm or less, and the average of the pigments in the oil phase was By making the particle size 0.4 μm or less,
It was found that an emulsion ink for stencil printing having excellent fixability and storage stability can be obtained, and by setting the average particle diameter of the above pigment to 0.15 μm or more, ink without bleeding and degenerated on standing can be removed from the drum. It has been found that an emulsion ink for stencil printing can be obtained which does not spill over to contaminate the printed image or the inside of the machine.

The reason is that the average particle size of the pigment is 0.4 μm.
By setting the following, the penetration of the pigment into the paper is improved and the fixing property is improved, and by reducing the average particle size, the dispersed state of the pigment is improved and the pigment particles aggregate due to sedimentation of the pigment. It is presumed that the stability as an ink is improved because of the small size. The average particle size of the pigment is 0.15
When the particle size is at least μm, the penetrability of the pigment into the paper can be controlled to suppress bleeding, and the average particle size of the pigment can be kept at 0.15 μm or more in the dispersed state of the pigment to make the ink oil It is possible to give a yield value to the phase component, the moisture evaporates when left standing, and the phenomenon in which even the ink that has become the oil phase only drips is suppressed by the oil phase having the yield value, which causes problems on the machine. It is supposed to be improved. In addition, since the size of the emulsion affects the permeation rate in the early stage of permeation, when the emulsion is destroyed during the permeation process, it is presumed that the emulsion particle size of the aqueous phase is also involved.

The present invention will be described in more detail below. The emulsion ink for stencil printing of the present invention has an oil phase of about 10 to 5
It consists of a water-in-oil emulsion composed of 0% by weight and an aqueous phase of about 90 to 50% by weight, and the oil phase is composed of an oil component, a pigment dispersant, a pigment, a resin, an emulsifier, and the like.
The aqueous phase is composed of water, electrolyte, antiseptic / antifungal agent, antioxidant, water evaporation inhibitor, water-soluble polymer and the like.
Known constituents that do not inhibit the formation of emulsion are used as these constituents.

As the oil component in the oil phase used in the present invention, conventionally known ones can be applied. For example, mineral oils such as liquid paraffin, spindle oil, light oil, kerosene, machine oil and lubricating oil; olive oil and rapeseed. Oils, vegetable oils such as castor oil and soybean oil are used. Also, synthetic oils can be used in the present invention. When using synthetic oils, various compounds are available. Representative synthetic vehicles include polyisobutylenes, hydrogenated polydecenes, trimethylolpropane esters, neopentyl esters 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, chain 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, for example, sorbitan higher fatty acid ester, polyoxyethylene sorbitan higher fatty acid ester, fatty acid monoglyceride, fatty acid diglyceride and higher alcohol, alkylphenol, fatty acid, etc. The ethylene oxide adducts of the above are listed alone or those having different HLB (hydrophilic / lipophilic balance)
By combining more than one species and increasing the HLB from 2 to 14,
Prepare a highly stable emulsion.

The pigment dispersant used in the present invention includes:
Those which do not inhibit the formation of emulsion are used, for example, alkylamine-based polymer compounds, aluminum chelate-based compounds, styrene / maleic anhydride-based copolymerized polymer compounds, polyacrylic acid partial alkyl esters, polyalkylenepolyamines, and aliphatic-based compounds. Polycarboxylic acid, amine salt of high molecular weight polyester, polyether, ester type anionic surfactant, long chain amine salt of high molecular weight polycarboxylic acid, salt of long chain polyaminoamide and high molecular weight polyester, polyamide compound, phosphoric acid Examples thereof include ester surfactants, alkylsulfocarboxylates, α-olefinsulfonates, dioctylsulfosuccinates 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. As the resin used in the present invention, phenol resin, malein resin, petroleum resin, rubber resin, alkyd resin, rosin-modified resin, etc. are used for the purpose of viscosity adjustment.

As described above, in the present invention, when the average particle size of the pigment in the oil phase is 0.4 μm or less, the fixability and storage stability are excellent. In order to improve the fixability, the average particle size of the pigment is preferably 0.29 μm or less, and more preferably 0.25 μm or less. The average particle size of the pigment is 0.15
When the thickness is at least μm, a printed image without bleeding is provided, and even when the printed image is deteriorated by being left unattended, it does not drip out of the drum and contaminate the printed image and the inside of the machine.

As the evaporation inhibitor and anti-caking agent in the aqueous phase used in the present invention, polyhydric alcohols such as ethylene glycol, sorbitol and glycerin, polyethylene glycol and the like are used. Examples of the antiseptic / antifungal agent include aromatic hydroxy compounds and chlorine compounds thereof, salicylic acid, phenolic acid, methyl p-oxybenzoate, ethyl p-oxybenzoate, sorbic acid, dehydroacetic acid and the like. In addition, as the electrolyte, for example, sodium sulfate, sodium hydrogen phosphate, sodium borate, or the like is used. As antioxidants such as resin,
For example, dibutylhydroxytoluene, propyl gallate, butylhydroxyanisole, etc. are used.

A water-soluble polymer may be used in the aqueous phase for the purpose of moistening or thickening. Specific examples of the water-soluble polymer include, for example, starch, mannan, sodium alginate, galactan, tragacanth gum, gum arabic, vullan, dextran, xanthan gum, glue, gelatin, collagen, casein, and other natural polymers; kilvoxymethyl cellulose, Semi-synthetic polymers such as methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, hydroxymethyl starch, carboxymethyl starch, dialdehyde starch; acrylic acid resins and sodium polyacrylate, acrylic acid such as polyacrylic acid triethanolamine Resin derivative, polyvinyl alcohol,
Examples thereof 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 combination with the water-soluble polymer. For example, as the thickening accelerator used in combination with acrylic acid resin, diisopropanolamine, di-2 (ethylhexyl) amine, triethanolamine, triamylamine, b-dimethylaminopropionitrile, dodecylamine, morphomorph Examples thereof include low molecular weight amines such as phosphorus and alkanolamines, and inorganic bases such as sodium hydroxide, potassium hydroxide and ammonium hydroxide.

In the preparation of the emulsion ink of the present invention, the oil phase is prepared by dispersing the pigment in a commonly known disperser and diluting it with oil or another oil phase composition. A known stirrer is usually used for the dilution. The aqueous phase composition is usually mixed with the stirrer in the aqueous phase. The finished oil phase and water phase are easily emulsified by using a known emulsifier. The manufacturing method and means such as dispersion, dilution, and emulsification can be changed as appropriate.

[0019]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. All parts shown below are based on weight.

Example 1 Raw materials having the formulations shown below were used. (Colorant) Furnace carbon black 4.0 parts (Solvent) Paraffin oil 23.5 parts (Emulsifier) Sorbitan sesquioleate 5.0 parts (HLB = 3.7) (Pigment dispersant) Alkylamine polymer 2.5 parts (Water) Ion exchange water 55.5 parts (Antifreeze) Ethylene glycol 10.0 parts

The pigment dispersion is prepared by kneading furnace carbon black, paraffin oil and pigment dispersant with a three-roll mill, and the pigment dispersion is further mixed with an emulsifying surfactant and oil, if necessary. Then, a varnish such as a rosin-modified phenolic resin was added to form an oil phase, and an aqueous phase was added to the oil phase to emulsify the 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 formulations were used. (Colorant) Furnace carbon black 5.0 parts (Solvent) Paraffin oil 24.5 parts (Emulsifier) Sorbitan sesquioleate 5.0 parts (HLB = 3.7) (Pigment dispersant) Alkylamine polymer 0.5 parts (Water) Ion-exchanged water 55.0 parts (Antifreeze) 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 raw materials were used. (Colorant) Furnace carbon black 5.0 parts (Solvent) Paraffinic oil 23.5 parts (Emulsifier) Sorbitan sesquiolate 5.0 parts (HLB = 3.7) (Pigment dispersant) Aluminum chelate high content 1.5 parts (Water) Ion exchange 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 formulations were used. (Colorant) Furnace carbon black 5.0 parts (Solvent) Paraffinic oil 24.3 parts (Emulsifier) Sorbitan sesquioleate 5.0 parts (HLB = 3.7) (Pigment dispersant) Amine salts of high molecular polyester 0.7 parts (Water) Ion exchange water 55.0 Part (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 raw materials having the following formulations were used. (Colorant) Cyanine blue 5.0 parts (Solvent) Paraffin oil 24.0 parts (Emulsifier) Sorbitan sesquioleate 5.0 parts (HLB = 3.7) (Pigment dispersant) Phosphate ester surfactant 1.0 part (Water) Ion-exchanged water 55.0 parts (Antifreeze) 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 raw materials having the following formulations were used. (Colorant) Furnace carbon black 5.0 parts (Solvent) Paraffin oil 23.5 parts (Emulsifier) Sorbitan sesquioleate 5.0 parts (Pigment dispersant) Aluminum chelate compound 1.5 parts (Water) Ion-exchanged 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 (antifreezing agent) 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 raw materials were used. (Colorant) Furnace carbon black 4.0 parts (Solvent) Paraffin oil 26.0 parts (Emulsifier) Sorbitan sesquiolate 5.0 parts (HLB = 3.7) (Water) Ion-exchanged 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 raw materials were used. (Colorant) Furnace carbon black 5.0 parts (Solvent) Paraffin oil 25.0 parts (Emulsifier) Sorbitan sesquioleate 5.0 parts (HLB = 3.7) (Water) Ion-exchanged 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 formulations were used. (Colorant) Furnace carbon black 5.0 parts (Solvent) Paraffin oil 25.5 parts (Emulsifier) Sorbitan sesquioleate 3.0 parts (Pigment dispersant) Aluminum chelate compound 1.5 parts (Water) Ion-exchanged 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 (antifreezing agent) ethylene glycol 10.0 parts

(Evaluation) With respect to the emulsion ink for stencil printing obtained above, the average particle size of the pigment in the oil phase was measured, and printing was carried out using these inks. The evaluation and the fixing ratio of the ink were calculated, and the storage stability of the ink was evaluated. Further, the ink dripping inside the drum was evaluated. The evaluation and measurement methods are as follows. The results are summarized 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 measuring instrument LA-7
00 was used, and the ink as a sample was diluted with a paraffinic solvent for measurement. Bleeding of printed matter Using these inks, sufficient printing was performed with a commercially available stencil printing machine (VT3500) manufactured by Ricoh Co., Ltd. to spread the ink in the printing machine, and then printing was performed. Bleeding was evaluated using the printed matter at this time. Ink Fixing Rate The print density of the above-mentioned printed matter was measured by a reflection type optical densitometer (RD914 manufactured by Macbeth Co., Ltd.), and the density measured portion was reciprocated 10 times by a clock meter equipped with an eraser.
The density after erasing in 10 seconds was also measured, and the ink fixing rate was obtained from (density after erasing) / (print density). Storage stability of ink Storage stability was evaluated from the oil separation rate when 1 g of ink was placed in a centrifugal sedimentation tube and centrifuged under the condition of 6300G. Ink dripping in the drum Put the ink on two rolls (diameter 5 cm and 1.5 cm), rotate the rolls 10 times each, and leave it for about 1 week,
The degree of ink dripping from the roll was evaluated. Emulsion particle size It was measured using Cryo-SEM (manufactured by Hitachi, Ltd.).

[0032]

[Table 1] ◯: Good ×: Bad

From the results shown in Table 1, when the emulsion particle size of 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 fixability and storage stability of the ink are improved. When the average particle size is improved and the average particle size is within the range of 0.15 to 0.4 μm, a printed image without bleeding can be obtained, and the ink that has deteriorated when left standing drips out of the drum to cause a printed image or the inside of the machine. It turns out that it will not be polluted. Furthermore, the average particle diameter is 0.29 μm or less, and further, the average particle diameter is 0.2.
It can be seen that when the thickness is 25 μm or less, the fixability of the ink is further improved.

[0024]

According to the emulsion ink for stencil printing of claim 1, 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.
Since it is as follows, it is excellent in fixing property to paper and storage stability.

In the emulsion ink for stencil printing according to claim 2, since the average particle diameter of the pigment is in the range of 0.15 to 0.4 μm, a print image further free from bleeding can be obtained, and the inside of the drum can be obtained. The effect is that the ink that has been left in place and deteriorated does not drip outside the drum and contaminate the printed image or the inside of the machine.

Claims (2)

[Claims] 1. An oil phase of about 10-50% by weight and an aqueous phase of about 90-.
In a water-in-oil emulsion composed of 50% by weight, the particle size of the emulsion in the water phase is 10 μm or less, and the average particle size of the pigment dispersed in the oil phase is 0.4 μm.
An emulsion ink for stencil printing characterized by the following: 2. The emulsion ink for stencil printing according to claim 1, wherein the average particle diameter of the pigment is 0.15 μm or more.