JPH111651A - Emulsion ink for stencil printing press - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink not suffering from oil separation after a long time and not undergoing blotting in a W/O stencil printing press emulsion ink containing titanium oxide. SOLUTION: In a W/O emulsion ink for stencil printing presses prepared by dispersing at least titanium oxide, a surfactant and water in a mineral oil or a vegetable oil in an oil phase and comprising about 10-90 wt.% oil phase and about 90-10 wt.% water phase, titanium oxide having an oil absorption of 30 ml/100 g or above and desirably having a primary particle diameter of 0.05 μm or below is used. It may further contain a polyglycerol fatty acid ester.

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 a stencil printing machine, and more particularly to an emulsion ink for a heat-sensitive stencil printing machine.

[0002]

2. Description of the Related Art A general water-in-oil emulsion ink for a stencil printing machine is an extremely complex and unstable system in which a solid pigment and liquid water are dispersed in an oil serving as a dispersion medium. It is. In this ink, "aggregation" and "union" peculiar to the dispersion system progress with time.

[0003] When titanium oxide (TiO ₂ ) is blended as a pigment component of this ink, macro oil separation occurs when the above-mentioned aggregation or coalescence proceeds.
Currently used titanium oxide pigments for printing ink generally have an oil absorption of about 20 (ml / 100 g) and a primary particle diameter of about 0.2 μm. When titanium oxide having a small oil absorption and a large primary particle size is used, bleeding occurs due to a small amount of oil taken in by the titanium oxide structurally, and also causes oil separation over time, and oil separation proceeds. The resulting ink greatly increases the bleeding of the printed image, resulting in a poor printed image.

[0004] To date, no effective technology has been disclosed for oil separation and bleeding deterioration over time. Further, as an emulsion ink for a stencil printing machine containing titanium oxide, an ink excellent in oil separation over time has been developed. , Not yet developed.

[0005]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a water-in-oil emulsion ink for a stencil printing machine containing titanium oxide, which does not cause oil separation with time.
An object of the present invention is to provide an ink that does not cause bleeding.

[0006]

The present inventors have conducted various studies to solve the above-mentioned problems of the prior art, and as a result, have found that a titanium oxide pigment having an oil absorption of 30 (ml / 100 g) or more is obtained. By using a titanium oxide pigment having a primary particle diameter of 0.05 μm or less, in addition to the above oil absorption, it is possible to obtain an ink which does not cause oil separation over time and does not cause bleeding. Reached the present invention.

That is, according to the present invention, first, at least titanium oxide, a surfactant and water are dispersed in mineral oil or vegetable oil, and about 10 to 90% by weight of an oil phase and about 90 to 10% of an aqueous phase are dispersed. A water-in-oil type stencil printing machine emulsion ink constituted by% by weight, wherein the oil absorption of said titanium oxide is 30 (ml / 100 g) or more. You.
Secondly, in the first aspect, there is provided an emulsion ink for a stencil printing machine, wherein the titanium oxide has a primary particle diameter of 0.05 μm or less. Thirdly, there is provided an emulsion ink for a stencil printing machine, wherein the emulsion ink according to the first or second aspect is blended with a polyglycerin fatty acid ester.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. As described above, the emulsion ink for a stencil printing machine of the present invention is a water-in-oil emulsion ink obtained by dispersing at least titanium oxide, a surfactant and water in a mineral oil or a vegetable oil. Characterized in that the amount is 30 (ml / 100g) or more

The emulsion ink of the present invention uses a titanium oxide pigment having an oil absorption of 30 (ml / 100 g) or more, so that it does not cause bleeding due to a large amount of oil taken in structurally. Since separation does not occur, there is no deterioration of bleeding, and a clear image can be obtained even with an ink that is somewhat old. When a titanium oxide pigment having an extremely large oil absorption is used, the fluidity of the ink is significantly impaired, so that the oil absorption is 30 to 70 (ml / 10
It is preferable to use 0 g) of a titanium oxide pigment.

Further, in the emulsion ink of the present invention, in addition to the above oil absorption, the primary particle diameter is 0.05 μm
When the following titanium oxide pigment is used, no bleeding occurs,
In addition, oil separation due to aging does not occur, and surface smoothness can be given to a printed image. If it is attempted to eliminate bleeding using a titanium oxide pigment having a conventional particle size (about 0.2 μm), the dispersion must be relatively agglomerated, resulting in an image having poor surface smoothness. In addition,
If the primary particle size is less than 0.01 μm, stable dispersion becomes difficult, so the primary particle size is 0.01 to 0.05.
It is particularly preferred to use a μm titanium oxide pigment.

Furthermore, in the emulsion ink of the present invention, when a polyglycerin fatty acid ester is blended, the polyglycerin fatty acid ester takes in oil as an interfacial film on the pigment surface, so that a greater effect on bleeding and oil separation can be obtained. Can be done.

The mineral oil used in the present invention includes, for example, petroleum solvents, liquid paraffin, spindle oil, light oil, kerosene, machine oil, gear oil, lubricating oil, motor oil and the like. Tall oil, corn oil, olive oil, rapeseed oil, castor oil, soybean oil, dehydrated castor oil, and the like. Also, polyisobutylenes, hydrogenated polydecenes, trimethylolpropane esters, neopentyl esters, pentaerythritol esters, siloxanes, silicones, fluorocarbons, alkyl-substituted diphenyl ethers, phthalate esters, phosphate esters And the like can also be used. As the petroleum-based solvent, a mixed solvent such as Exxon's Isopar or Nippon Oil Corporation's Nisseki Solvent may be used. These oils may be used alone or in combination of two or more.

As the colorant, titanium oxide having a specific oil absorption is used as described above, but it can be used alone or in combination with another colorant. As the coloring agent to be used in combination, conventionally known coloring agents can be arbitrarily used, for example, carbon black,
Azo pigments, phthalocyanine pigments, nitroso pigments,
Pigments such as nitro pigments, vat dye pigments, mordant dye pigments, basic dye pigments, acid dye pigments and natural dye pigments, and oil-soluble dyes such as diazo dyes and anthraquinone dyes. These dyes and pigments may be added alone or in combination of two or more. The amount of the colorant added to the ink is 1 to 15% by weight, preferably 2 to 10% by weight.

As the pigment dispersant used in the present invention, the above-mentioned polyglycerin fatty acid ester is most preferred. In this case, the constituent polyglycerin has a polymerization mole number of 2-1.
And four such as diglycerin, triglycerin, hexaglycerin, decaglycerin and the like. As the pigment dispersant other than the polyglycerin fatty acid ester, the following can be used alone or in combination as long as the effects are not impaired. Examples of the sorbitan fatty acid ester include sorbitan monolaurate, sorbitan monopalmitate, sorbitan sesquioleate, and polyoxyethylene sorbitan fatty acid ester. In addition, glycerin fatty acid ester, propylene glycol fatty acid ester, pentaerythritol fatty acid ester, polyoxyethylene sorbitol fatty acid ester, polyoxyethylene glycerin fatty acid ester, polyethylene glycol fatty acid ester, polyethylene alkyl ether, polyoxyethylene phytosterol ether, polyoxyethylene polyoxy Propylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene castor oil, polyoxyethylene hardened castor oil, polyoxyethylene lanolin derivative, polyoxyethylene alkylamine, polyoxyethylene fatty acid amide, polyoxyethylene alkylphenyl formaldehyde condensate, etc. Is exemplified. In addition, alkylamine polymer compounds, aluminum chelate compounds, styrene / maleic anhydride copolymers, partial alkyl esters of polyacrylic acid, polyalkylene polyamine aliphatic polycarboxylic acids, polyethers, ester-type anionic surfactants An agent, a long-chain amine salt of a high molecular weight polycarboxylic acid, a polyamide, a phosphate ester-based surfactant, an alkyl sulfocarboxylate, an α-olefin sulfonate, a dioctyl sulfosuccinate and the like can also be used in combination. These dispersants may be added alone or as a mixture of two or more, and the amount of the dispersant added is 40% or less of the weight of the colorant, preferably 2 to 35%.
% By weight.

As the emulsifier, it is preferable to use a nonionic surfactant. Specifically, as the sorbitan fatty acid ester, sorbitan monolaurate, sorbitan monopalmitate, sorbitan sesquioleate, polyoxyethylene sorbitan fatty acid ester Etc. are exemplified. In addition, glycerin fatty acid ester, polyglycerin fatty acid ester, propylene glycol fatty acid ester, pentaerythritol fatty acid ester, polyoxyethylene sorbite fatty acid ester, polyoxyethylene glycerin fatty acid ester, polyethylene glycol fatty acid ester, polyoxyethylene alkyl ether, polyoxyethylene phytosterol Ether, polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene castor oil, polyoxyethylene hardened castor oil, polyoxyethylene lanolin derivative, polyoxyethylene alkylamine, polyoxyethylene fatty acid amide, polyoxyethylene Examples include alkylphenyl formaldehyde condensates It is. These may be used alone or as a mixture of two or more kinds and added to the ink. The amount of addition may be 1 to 20% by weight of the ink weight.

In the present invention, in addition to the above, a resin, a gelling agent, an antioxidant and the like can be added to the oil phase as long as the formation of the emulsion is not hindered. In the aqueous phase, a water-soluble polymer, an antiseptic / fungicide, a water evaporation inhibitor, an antifreeze,
A pH adjuster, an electrolyte and the like can be added. In addition,
Water only needs to be clean, specifically, tap water,
Ion exchange water, distilled water, or the like may be used.

The resin added to the oil phase is a binder resin which has been conventionally added for the purpose of fixing the colorant to the printing material, dispersing the colorant, and improving the aging stability of the ink. Therefore, it is sufficient to add a conventionally added resin, and specifically, rosin-modified resins such as rosin, polymerized rosin, hydrogenated rosin, rosin ester, and rosin-esterified rosin; A resin, a phenol resin, a petroleum resin, an alkyd resin, a rubber derivative, a polymerized castor oil, or the like may be added alone or as a mixture of two or more. The amount of addition may be 20% by weight or less, preferably 1 to 7% by weight of the ink weight.

The gelling agent has a role of gelling the resin contained in the oil phase to improve the storage stability and fixability of the ink. The gelling agent added to the ink of the present invention includes:
Compounds that coordinate with the resin in the oil phase are preferred. Illustrating such compounds are Li, Na, K, Al, C
a, an organic acid salt containing a metal such as Co, Fe, Mn, Mg, Pb, Zn, and Zr, an organic chelate compound, a metal soap oligomer, and more specifically, a metal octylate such as aluminum octylate; Examples thereof include metal salts of naphthenic acid such as manganese acid, stearates such as zinc stearate, and organic chelate compounds such as aluminum diisopropoxide monoethyl acetoacetate. One or more of these gelling agents may be added to the oil phase,
The addition amount is 15% by weight or less, preferably 5 to 10% by weight of the resin in the oil phase.

Antioxidants added to the oil phase include dibutylhydroxytoluene, propyl gallate, butylhydroxyanisole, and the like. The addition of these additives prevents oxidation of the binder resin and the like in the oil phase, thereby reducing the viscosity of the ink. Ascent is prevented. The amount of addition is 2% by weight or less, preferably 0.1 to 1.0% by weight of the oil in the ink. The antioxidants may be used alone or in combination of two or more.

The water-soluble polymer added to the aqueous phase of the emulsion ink is added for moisturizing and thickening, and specifically, the following natural or synthetic polymers are added. Natural polymers such as starch, mannan, sodium alginate, galactan, tragacanth gum, gum arabic, pullulan, textran, xanthan gum, glue, gelatin, collagen, casein, carboxymethylcellulose, methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, Semi-synthetic polymers such as hydroxymethyl starch, carboxymethyl starch, dialdehyde starch, acrylic resin derivatives such as polyacrylic acid, sodium polyacrylate, triethanolamine polyacrylate, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylamide, polyethylene oxide ,
Synthetic polymers such as polyvinyl methyl ether and others. These water-soluble polymers may be used alone or in combination of two or more, and are added in an amount of 25% by weight or less, preferably 0.5 to 15% by weight of water contained in the ink.

The antiseptic / fungicide added to the aqueous phase is added to prevent the growth of bacteria and mold in the emulsion. When the emulsion is stored for a long period of time, the antiseptic / fungicide is usually added. is there. The amount of addition is 3% by weight or less of water contained in the ink, preferably 0.1 to 1.2% by weight. In addition, as an antiseptic and fungicide,
In addition to aromatic hydroxy compounds such as salicylic acid, phenols, methyl p-oxybenzoate and ethyl p-oxybenzoate and their chlorine compounds, sorbic acid and dehydroacetic acid are used, and these may be used alone or in combination of two or more. May be used.

The water evaporation inhibitor and the antifreezing agent can be used in combination. Chemicals added for these purposes include glycols such as ethylene glycol, diethylene glycol and propylene glycol, methanol, ethanol, isopropanol, butanol and isobutanol. And lower polyhydric alcohols such as glycerin and sorbitol. One or more of these chemicals may be added, and the added amount is 15% by weight or less, preferably 4 to 12% by weight of the weight of water in the ink.

The pH adjuster added to water is triethanolamine, sodium acetate, triamylamine, etc. If necessary, these pH adjusters are added to add p
H can be maintained at 6-8. If the pH of the aqueous phase is out of the above range, there is a problem that the effect is lost when a water-soluble polymer for a thickener is added.

The electrolyte added to the aqueous phase is added to enhance the stability of the emulsion. Therefore, it is preferable to add an electrolyte composed of ions having a high liquid-separation sequence effective for improving the stability of the emulsion. Anions with high syneresis are citrate ions,
Tartrate ion, sulfate ion, acetate ion, and the like, and the cation having a high liquid separation sequence is an alkali metal ion or an alkaline earth metal ion. Therefore, the electrolyte to be added here is at least an anion or a cation. Preference is given to salts of which one consists of said ions. Therefore, as the electrolyte added here, magnesium sulfate, sodium sulfate,
Sodium citrate, sodium hydrogen phosphate, sodium borate, sodium acetate and the like are preferred, and the amount of addition is 0.1 to 2% by weight, preferably 0.5 to 1.5% by weight of the aqueous phase.

In addition to the above, the water-in-oil emulsion ink for a stencil printing machine of the present invention is used to improve the separation between the printing paper and the printing drum during printing or to prevent the printing paper from rolling up. A wax can be added to the oil phase. Further, to the aqueous phase, triethanolamine, sodium hydroxide, or the like can be added to further increase the viscosity by adding a water-soluble polymer. Further, by adding a rust inhibitor or a defoaming agent to the aqueous phase, it is possible to prevent the printing press from rusting or bubbling of the ink during printing. Known additives added to the ink for a stencil printing machine may be added to these additives as needed, and the amount of these additives may be about the same as in the case of conventional products.

The emulsion ink of the present invention may be prepared by preparing an oil phase and an aqueous phase liquid in the same manner as in the conventional emulsion ink production, and emulsifying both of them in a known emulsifier to form an ink. That is, an oil in which additives such as a coloring agent, an emulsifier, and a resin to be added as needed are well dispersed is adjusted by a conventional method, and an antiseptic / antifungal agent, a water-soluble polymer, and the like are optionally added thereto. What is necessary is just to gradually add and emulsify the added aqueous solution.

[0027]

Next, the present invention will be described in more detail by way of examples. The parts shown below are based on weight.

Example 1 0.5 parts of carbon black 5.5 parts of titanium oxide [TTO-55 (B): Ishihara Sangyo: Oil absorption 35 (ml / 100g)] Nisseki A oil (mineral oil having a viscosity of 80 mPa · S) 5.5 parts Nisseki B oil (mineral oil having a viscosity of 240 mPa · S at 20 ° C.) 10.0 parts Alkyd resin 3.0 parts Polyoxyethylene castor oil 5.5 parts Water 69.0 parts MgSO ₄ 1.0 Parts Carbon black, titanium oxide, Nisseki A in the above ratio
Oil, Nisseki B oil, alkyd resin, and polyoxyethylene castor oil were mixed and dispersed with a three-roll mill to obtain an oil phase. As for the oil phase, a mill base can be prepared from polyoxyethylene castor oil, pigment and oil, and each additive can be mixed with the mill base to prepare an oil phase. While stirring the oil phase with a stirrer, water in which magnesium sulfate was dissolved was gradually added, and the mixture was emulsified to obtain a W / O emulsion.

Using this emulsion ink, printing was performed with a stencil printer Ricoh VT-3820 machine to obtain a printed image. Further, in this ink, the amount of centrifugal oil separation, the appearance oil separation (visual rank evaluation), and the bleeding of the printed image (visual rank evaluation) were evaluated at the initial stage of production and after leaving at 60 ° C. for one month. .

Example 2 0.5 parts of carbon black 5.5 parts of titanium oxide [TTO-55 (B): Ishihara Sangyo: Oil absorption 35 (ml / 100g)] Nisseki A oil (mineral oil having a viscosity of 80 mPa · S) 5.5 parts Nisseki B oil (mineral oil having a viscosity of 240 mPa · S at 20 ° C.) 10.0 parts Alkyd resin 3.0 parts Polyglycerin fatty acid ester 0.5 parts Polyoxyethylene castor oil 5.0 parts Water 69 0.0 parts MgSO ₄ 1.0 parts Carbon black, titanium oxide, Nisseki A
Oil, Nisseki B oil, alkyd resin, polyoxyethylene castor oil, and polyglycerin fatty acid ester were mixed, and the mixture was dispersed with a three-roll mill to obtain an oil phase. As for the oil phase, a mill base can be prepared from polyglycerin fatty acid ester, pigment and oil, and each additive can be mixed with the mill base to prepare an oil phase. While stirring the oil phase with a stirrer, water in which magnesium sulfate was dissolved was gradually added, and emulsified to obtain a W / O emulsion ink.

Using this emulsion ink, printing was performed with a stencil printer Ricoh VT-3820 machine to obtain a printed image. Further, in this ink, the amount of centrifugal oil separation, the appearance oil separation (visual rank evaluation), and the bleeding of the printed image (visual rank evaluation) were evaluated at the initial stage of production and after leaving at 60 ° C. for one month. .

Comparative Example 1 0.5 parts of carbon black 5.5 parts of titanium oxide [CR-50: Ishihara Sangyo: Oil absorption 18 (ml / 100 g)] Nisseki A oil (mineral oil having a viscosity of 80 mPa · S at 20 ° C.) 5.5 parts Nisseki B oil (mineral oil having a viscosity of 240 mPa · S at 20 ° C.) 10.0 parts Alkyd resin 3.0 parts Polyoxyethylene castor oil 5.0 parts Water 69.0 parts MgSO ₄ 1.0 part An ink was prepared from the product in the same manner as in Example 1, and the same evaluation as in Example 1 was performed.

Table 1 shows the results of Examples 1 and 2 and Comparative Example 1. In addition, the centrifugal oil separation amount shown in Table 1 means that 63
The centrifugal force of 00G was applied for 3 hours, and the ratio of the oil generated by the centrifugal force to the ink weight was expressed in%. In addition, the appearance oil separation shown in Table 1 ranks the apparent amount of oil in the ink pack, and the smaller the oil separation, the better, and in the descending order, (（: good ○: slightly good □: normal
Δ: somewhat poor ×: poor) In addition, the bleeding shown in Table 1 ranks the apparent bleeding amount of a printed image, and the smaller the bleeding, the better, and in order of goodness, (◎: good)
：: Somewhat good □: Normal △: Somewhat bad ×: Bad)

[0034]

[Table 1]

From the results shown in Table 1, it can be seen that by satisfying the conditions of the present invention, it is possible to obtain an ink which does not cause oil separation over time and does not cause bleeding.

[0036]

The emulsion ink for a stencil printing machine according to claim 1 is obtained by dispersing at least titanium oxide, a surfactant and water in a mineral oil or a vegetable oil in an oil phase. And an aqueous phase of about 90 to 10% by weight, the emulsion ink for a water-in-oil stencil printing machine having an oil absorption of 30 (ml / 100).
g) or more, oil separation with time does not occur, and no bleeding occurs.

The emulsion ink for a stencil printing machine according to claim 2, wherein the titanium oxide has a primary particle size of 0.05 μm.
Since the following requirement is added, the effect that surface smoothness can be given to a printed image is added.

Since the emulsion ink for a stencil printing machine according to the third aspect contains a polyglycerol fatty acid ester, it is considered that the ester is adsorbed on the surface of the pigment and structurally incorporates an oil component as an interface film. As a result, the effect of suppressing bleeding and oil separation is further improved.

Claims (3)

[Claims] An oil phase comprising at least titanium oxide, a surfactant and water dispersed in a mineral oil or a vegetable oil.
A water-in-oil type stencil printing machine emulsion ink comprising 0 to 90% by weight and about 90 to 10% by weight of an aqueous phase, wherein the titanium oxide has an oil absorption of 30 (ml / 100).
g) An emulsion ink for a stencil printing machine, characterized in that: 2. The emulsion ink for a stencil printing machine according to claim 1, wherein the titanium oxide has a primary particle size of 0.05 μm or less. 3. The emulsion ink for a stencil printing machine according to claim 1, wherein a polyglycerin fatty acid ester is blended.