JP2013035928A - Emulsion ink and ink cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide emulsion ink having storage stability in addition to fixing properties and curling resistance, and an ink cartridge having the ink stored in a container.SOLUTION: (1) The emulsion ink is composed of an oil phase and an aqueous phase, and includes a coloring agent and a dispersant contained in at least one of the oil phase and the aqueous phase; and 5-20 wt.%, relative to the whole ink, of an amphipathic solvent contained in the aqueous phase. (2) In the emulsion ink of (1), the amphipathic solvent is bis-ethoxydiglycol succinate. (3) The emulsion ink of (1) or (2) further includes an ester oil contained in the aqueous phase.

Description

  The present invention relates to an emulsion ink and an ink cartridge containing the ink in a container.

A general emulsion ink is obtained by emulsifying an oil phase mainly composed of oil and an aqueous phase mainly composed of water using a surfactant. In the aqueous phase, glycerin is widely used as a water-soluble organic solvent in addition to water, in order to maintain environmental performance, cost, and performance as an emulsion ink. However, since glycerin has a strong hydrophilicity, when ink is printed on printing paper, it breaks hydrogen bonds in cellulose together with water, resulting in paper curling and cockling. It was. For example, there are water-soluble organic solvents that are slightly more hydrophobic than glycerin, such as 3-methyl-1,3-butanediol, but are significantly inferior to glycerin in terms of storage stability. Therefore, conventionally, it has been impossible to achieve both curl resistance and storage stability.
On the other hand, Patent Document 1 discloses an invention relating to an oil agent containing an ester of a dibasic acid such as bisethoxydiglycol succinate which is the same as that used in the present invention. However, its applications are limited to lubricants, humectants, and external preparations, and no description or suggestion has been made on emulsion inks.

  An object of the present invention is to provide an emulsion ink having storage stability in addition to fixability and curl resistance, and an ink cartridge containing the ink in a container.

３） 更に水相にエステル油を含有することを特徴とする１）又は２）記載のエマルジョンインキ。
４） エステル油が、大豆油脂肪酸メチルエステル、大豆油脂肪酸ブチルエステル、大豆油脂肪酸オクチルエステルから選ばれた少なくとも１種であることを特徴とする３）記載のエマルジョンインキ。
５） エステル油の含有量が、コハク酸ビスエトキシジグリコールの含有量に対して、１０〜３０重量％であることを特徴とする３）又は４）記載のエマルジョンインキ。
６） 更に水相にグリセリンを含有することを特徴とする１）〜５）のいずれかに記載のエマルジョンインキ。
７） 更に油相に界面活性剤を含有することを特徴とする１）〜６）のいずれかに記載のエマルジョンインキ。
８） １）〜７）のいずれかに記載のエマルジョンインキを容器内に収容したことを特徴とするインキカートリッジ。 The above problems are solved by the following inventions 1) to 8).
1) It consists of an oil phase and an aqueous phase, and contains a colorant and a dispersant in at least one of the oil phase and the aqueous phase, and the aqueous phase contains 5 to 20% by weight of an amphiphilic solvent based on the total ink. Emulsion ink characterized by
2) The emulsion ink according to 1), wherein the amphiphilic solvent is bisethoxydiglycol succinate represented by the following general formula.

3) The emulsion ink according to 1) or 2), wherein the aqueous phase further contains an ester oil.
4) The emulsion ink according to 3), wherein the ester oil is at least one selected from soybean oil fatty acid methyl ester, soybean oil fatty acid butyl ester, and soybean oil fatty acid octyl ester.
5) The emulsion ink according to 3) or 4), wherein the content of the ester oil is 10 to 30% by weight based on the content of bisethoxydiglycol succinate.
6) The emulsion ink according to any one of 1) to 5), wherein the aqueous phase further contains glycerin.
7) The emulsion ink according to any one of 1) to 6), wherein the oil phase further contains a surfactant.
8) An ink cartridge comprising the emulsion ink according to any one of 1) to 7) contained in a container.

  ADVANTAGE OF THE INVENTION According to this invention, the emulsion ink which has storage stability in addition to fixing property and curl resistance, and the ink cartridge which accommodated this ink in the container can be provided.

The figure which shows an example of the container of the ink for stencil printing. The figure which shows an example of the container of the ink for ink jets.

Hereinafter, the present invention will be described in detail.
In the present invention, an emulsion ink having not only fixability and curl resistance but also storage stability can be obtained by incorporating an amphiphilic solvent that is a water-soluble organic solvent and has strong hydrophobicity in the aqueous phase. A preferred amphiphilic solvent is bisethoxydiglycol succinate, and a compound represented by the above general formula is particularly preferred.
Since bisethoxydiglycol succinate has a hydrophilic part and a hydrophobic part in its structure, it is easier to adapt to printing paper than a general water-soluble organic solvent, and the fixing property after printing is improved. In addition, bisethoxydiglycol succinate has a characteristic that it dissolves in the aqueous phase while dissolving the ester oil due to its structure. By the effect of the hydrophobic part of bisethoxydiglycol succinate and the ester oil, It is considered that the probability of breaking hydrogen bonds is lowered, and as a result, the curl resistance is improved.
The content of bisethoxydiglycol succinate is 5 to 20% by weight of the total ink. If it exceeds 20% by weight, emulsification becomes difficult during the production of the emulsion ink. Further, if it is less than 5% by weight, the effect of containing bisethoxydiglycol succinate is not sufficiently exhibited.

Further, curling of printing paper occurs when hydrogen bonds in cellulose are broken by water or a water-soluble organic solvent. However, when ester water is contained in the aqueous phase, the curling resistance is further improved.
The ester oil is dissolved in bisethoxydiglycol succinate and added to the aqueous phase. The ester oil is preferably at least one selected from soybean oil fatty acid methyl ester, soybean oil fatty acid butyl ester, and soybean oil fatty acid octyl ester.
The amount of the ester oil dissolved in bisethoxydiglycol succinate is preferably 10 to 30% by weight, more preferably 20 to 30% by weight, based on bisethoxydiglycol succinate.
Further, the emulsion ink of the present invention can suppress curling of printing paper even in high-speed printing, and enables high-speed conveyance and high-speed double-sided printing.

  Furthermore, when glycerin is contained in the aqueous phase, the storage stability is further improved. However, since bisethoxydiglycol succinate is not mixed with glycerin, it is necessary to prepare a mixed solution of water and glycerin in advance and mix bisethoxydiglycol succinate there. The mixing ratio is not particularly limited. Naturally, increasing the glycerin ratio deteriorates the curl resistance, and conversely decreasing the glycerin ratio results in somewhat poor storage stability. It is necessary to determine the ratio.

  Known colorants can be used, such as carbon blacks such as acetylene black, channel black and furnace carbon, metal powders such as aluminum powder and bronze powder, petals, yellow lead, ultramarine, chromium oxide and titanium oxide. Inorganic pigments, insoluble azo pigments, azo lake pigments, azo pigments such as condensed azo pigments, phthalocyanine pigments such as metal-free phthalocyanine pigments and copper phthalocyanine pigments, anthraquinone, quinacridone, isoindolinone, isoindoline, dioxazine , Selenium, perylene, perinone, thioindigo, quinofuranone, condensed polycyclic pigments such as metal complexes, organic pigments such as acid or basic dye lakes, oil-soluble dyes such as diazo dyes and anthraquinone dyes And fluorescent pigments. Colorant particles obtained by coating inorganic particles with an organic pigment or carbon black may also be used. Since the dye has a problem in terms of light resistance, it is preferable to use an insoluble colorant. However, it may be added for the purpose of supplementing the color, or the dye and the pigment may be used depending on the color.

Representative carbon blacks include MA-100, MA-7, MA-70, MA-77, MA-11, # 40, # 44 (Mitsubishi Chemical Corporation), Raven1100, Raven1080, Raven1255, Raven760, Raven410 ( Colombian Carbon Co.).
As the fluorescent pigment, a so-called synthetic resin solid solution type obtained by dissolving or dyeing a fluorescent dye that develops various hues during or after bulk polymerization of a synthetic resin, and then pulverizing and refining the resulting colored bulk resin Examples of synthetic resins that carry dyes include fluorescent pigments that carry melamine resin, urea resin, sulfonamide resin, alkyd resin, polyvinyl chloride resin and the like on the dye.
These dyes and pigments may be used alone or in combination of two or more.
The average particle size of the dispersed colorant is preferably 0.1 to 10 μm, and more preferably 0.1 to 1.0 μm.
The addition amount of the colorant is preferably 1.0% by weight or more, more preferably 4 to 10% by weight, based on the whole ink.

  Examples of the colorant dispersant include alkylamine polymer compounds, aluminum chelate compounds, styrene-maleic anhydride copolymer polymers, polycarboxylic acid ester polymer compounds, fatty acid polyvalent carboxylic acids, and polymer polyesters. Amine salts, ester type anionic surfactants, long chain amine salts of high molecular weight polycarboxylic acids, salts of long chain polyaminoamides and high molecular acid polyesters, polyamide compounds, phosphate ester surfactants, alkyl sulfocarboxylates , Α-olefin sulfonates, dioctyl sulfosuccinates, polyethyleneimine, alkylolamine salts, and resins having insoluble colorant dispersion ability such as alkyd resins.

  In addition, an ionic surfactant, an amphiphilic surfactant, or the like may be used as a dispersant for the colorant as long as it does not impair the storage stability of the ink. These dispersants may be added alone or in admixture of two or more. The amount of the dispersant other than the polymer and the resin is 40% by weight or less, preferably 2 to 35% by weight of the colorant weight. That's fine. Alkyd resins are particularly effective for the dispersion stability of insoluble colorants when high molecular weight resins are added, but the amount of resin added when using alkyd resins alone or in combination with other dispersants is The ratio is preferably 0.05 or more with respect to the insoluble colorant 1.

The oil component in the present invention is preferably vegetable oil and its derivatives, and known ones can be used. Examples thereof include soybean oil, rapeseed oil, corn oil, sesame oil, tall oil, palm oil, cottonseed oil, sunflower oil, sunflower oil, walnut oil, poppy oil, linseed oil and the like. These may be used alone or in combination of two or more.
However, the oil contained in the aqueous phase must be an esterified vegetable oil such as methyl, butyl, isopropyl, propyl, octyl.
As other oil components, various industrial solvents, motor oil, gear oil, light oil, kerosene, spindle oil, machine oil, liquid oil, and other mineral oils, as well as synthetic oils can be used. The oil component is used by mixing a plurality of oils having different volatility in order to improve the storage stability of the ink. However, since the volatile oil may adversely affect the global environment, it is better not to use it as much as possible.

The vegetable oils include dry oil, semi-dry oil, and non-dry oil, and are classified according to iodine value. The iodine value is expressed in grams of iodine adsorbed on 100 g of oil. The larger the iodine value, the more the unsaturated bonds are present, and the more the iodine value becomes.
Considering the ink fixing property and storage stability after printing, it is preferable that the iodine value of the vegetable oil or its derivative in the ink satisfies the following formula, assuming that oil A to oil Z are used.

In general, rot due to oxidation is a chain reaction. Once one molecule of fat is oxidized, the other molecules are sequentially oxidized and the reaction continues. The oxidation reaction of fats and oils consists of the steps represented by the following simple equations.

  As described above, the oxidation is initiated by the catalytic effect of the unsaturated lipid “RH” losing hydrogen bonds to form the free radical “R.” (Equation 1). This free radical "R." reacts with oxygen molecules to form a peroxide radical "ROO." (Formula 2), and then hydroperoxide "ROOH" by reaction of "ROO." And "RH" And a free radical “R.” is generated (Formula 3). The chain reaction continues, the amount of peroxide increases, and the rate of auto-oxidation becomes increasingly faster. Equations 4 and 5 are termination reactions.

  In dry oils and semi-dry oils having a high iodine value, the oxidation reaction as described above occurs remarkably, whereby the drying (solidification) of the oil proceeds, and the oily ink containing the vegetable oil is also solidified. When ink solidifies, problems such as ejection failure may occur. Especially when using vegetable oils with high iodine value (containing many unsaturated bonds), fatty acids (linolenic acid, linoleic acid, olein in vegetable oil) It is preferable to contain an antioxidant in order to prevent oxidation of acid and the like.

In the presence of the antioxidant “AH” (H is a hydrogen that is easily separated), hydrogen is given to the free radical “R.” and the peroxide radical “ROO.”, And the antioxidant itself becomes the radical “A.” The chain reaction is interrupted (Formula 6, Formula 7). The radical “A.” of the antioxidant is stable by reacting with each other to form a dimer (Formula 8), or reacting with the free radical “R.” or the peroxide radical “ROO.” A compound is produced (Formula 9, Formula 10).
6). R ・ + AH → RH + A ・
7). ROO ・ + AH → ROOH + A ・
8). A ・ + A ・ → AA
9. A ・ + R ・ → RA
10. A ・ + ROO ・ → ROOA

By adding an antioxidant, the above-described antioxidant mechanism is generated, and drying (solidification) of the oil is suppressed, and thus solidification of the oil-based ink containing the vegetable oil is also suppressed.
As the antioxidant, known compounds can be used, and examples thereof include amine compounds such as diphenylphenylenediamine and isopropylphenylphenylenediamine, phenolic compounds such as tocopherol and dibutylmethylphenol, and sulfur compounds such as mercaptomethylbenzimidazole. . These may be used alone or in combination of two or more. However, when an extremely small amount of antioxidant is added to the vegetable oil content, an appropriate antioxidant effect cannot be expected. Conversely, a large amount of antioxidant is added to the vegetable oil content at once. If it does, it may act as an oxidation accelerator. Therefore, it is preferable to add a synergist to suppress the oxidation of vegetable oil even with a small amount of antioxidant.

A synergist itself has little antioxidant action, but when used in combination with an antioxidant, it enhances its action. It is an acidic substance that has several hydroxyl or carboxyl groups. A compound. Synergists can be divided into two types according to their mechanism of action.
The first type shows a true synergistic action and is recognized when the antioxidant A and the synergist B are used in combination. Synergist B has a much weaker chain termination action than antioxidant A, but since synergist B acts as a hydrogen donor to radical A. of antioxidant (Equation 11), apparently synergist B Seems to have an antioxidant action like antioxidant A.
7). ROO ・ + AH → ROOH + A ・
11. A ・ + BH → AH + B ・

  The second type is a metal deactivator that enhances the action of the main antioxidant by inhibiting the activity of the metal as a catalyst for auto-oxidation. Citric acid and polyphosphoric acid are metal deactivators, but are known to work cooperatively with phenolic antioxidants even in the absence of metal.

  Synergists include methionine, ascorbic acid, threonine, leucine, milk protein hydrolyzate, norvaline, ascorbyl palmitate, phenylalanine, cystine, tryptophan, proline, alanine, glutamic acid, valine, pancreatic protein pepsin digestion solution, asparagine, arginine Well-known ones such as barbituric acid, asphenamine, ninhydrin, propanidin, histidine, norleucine, glycerophosphoric acid, casein trypsin hydrolyzed solution, and casein hydrochloric acid hydrolyzed solution can be used. These may be used alone or in combination of two or more.

  Regarding the addition amount of the synergist, when the addition amount of the synergist is much larger than the addition amount of the antioxidant, the reactions of the above formulas 7 and 11 occur with a considerable probability, and in the vegetable oil even if time passes. There is a possibility that the unsaturated bond is not oxidized and the merit that the color does not easily fall off due to friction in the image after printing may be reduced. However, for vegetable oils with a high iodine value, there is an advantage that problems such as ejection failure due to solidification of ink are solved. Therefore, by making the addition amount of the synergist within the range of 50 to 150% by weight with respect to the addition amount of the antioxidant, it is possible to use vegetable oil having a high iodine value, and to adjust the degree of oxidation. As a result, it is possible to leave the merit that the color is not easily lost due to friction in the image after printing.

  Oil phase includes glycerin fatty acid ester, sorbitan fatty acid ester, propylene glycol fatty acid ester, pentaerythritol fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbit fatty acid ester, polyethylene glycerin fatty acid ester, polyethylene glycol fatty acid ester, polyoxyethylene Alkyl ether, polyoxyethylene phytosterol, polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene castor oil, polyoxyethylene hydrogenated castor oil, polyoxyethylene lanolin, polyoxyethylene lanolin alcohol, polyoxyethylene alkyl Amine, polyoxyethylene fatty acid amide, poly A nonionic surfactant such as alkoxy alkylphenyl formaldehyde condensates may be used. The added amount is preferably 1 to 8% by weight, more preferably 2.2 to 6.0% by weight of the total ink.

  The oil phase includes rosin, polymerized rosin, hydrogenated rosin, rosin ester, rosin polyester resin, hydrogenated rosin ester and other rosin resins, rosin modified alkyd resin, rosin modified maleic resin, rosin modified phenolic resin, petroleum A resin, a rubber derivative resin such as cyclized rubber, a resin such as a terpene resin, an alkyd resin, or a polymerized castor oil may be added singly or in combination. The amount of resin added is preferably 2 to 50% by weight, more preferably 5 to 20% by weight, from the cost of ink and printability. When the weight average molecular weight of the resin is small or when the addition amount is small, the effect on the fixing property is small, and when the weight average molecular weight is too large or the resin addition amount is large, the printing screen is clogged. A malfunction will occur.

The alkyd resin containing a carboxyl group is composed of fats and oils, a polybasic acid, and a polyhydric alcohol. Examples of fats and oils include semi-drying oils such as soybean oil and these fatty acids, and alkyd resins comprising non-drying oils or semi-drying oils having an iodine value of 80 or less, such as coconut oil, palm oil, olive oil, castor oil, rice bran oil, and cottonseed oil. Can be used as long as there is no problem.
Examples of the polybasic acid include unsaturated polybasic acids such as phthalic anhydride, isophthalic acid, terephthalic acid, succinic acid, adipic acid, sebacic acid, tetrahydrophthalic acid, fumaric acid, itaconic acid, and citraconic anhydride.
Polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, glycerin, trimethylolpropane, neopentyl glycol, diglycerin, triglycerin, pentaerythritol, diethylene Examples include pentaery slit, mannit, and sorbit.
The oil length of the alkyd resin is indicated by the weight% in the resin when the fatty acid in the fat is present as triglyceride.

As the alkyd resin containing a carboxyl group, it is preferable to use a resin having an iodine value of 80 or more, such as soybean oil-modified alkyd resin, in view of ink fixability. Also, oils having an oil length of 60 to 90 and an iodine value of 80 or less can be used as long as there is no hindrance. The oil length of the alkyd resin is preferably from 60 to 90 and an iodine value of around 80, but the weight average molecular weight of the alkyd resin is preferably less than 30,000, and more preferably 10,000 or less. Specifically, Arachid 5301X-50, Arachid 8012, Arachide 5350 (manufactured by Arakawa Chemical Co., Ltd.) and the like are preferable. Moreover, the addition amount is preferably 1 to 10% by weight, more preferably 2 to 5% by weight based on the whole oil-based ink.
The addition form of the alkyd resin containing a carboxyl group may be a form in which a pigment as a colorant is included in the resin, or a form in which a colorant is dispersed.

A gelling agent may be added to the ink. The gelling agent is preferably a compound that has a role of improving the storage stability, fixability, and fluidity of the ink by gelling the resin contained in the ink and that coordinates with the resin in the ink. Examples include organic acid salts containing metals such as Li, Na, K, Al, Ca, Co, Fe, Mn, Mg, Pb, Zn, and Zr, organic chelate compounds, and metal soap oligomers. Include octylic acid metal salts such as aluminum octylate, naphthenic acid metal salts such as manganese naphthenate, stearates such as zinc stearate, and organic chelate compounds such as aluminum diisopropoxide monoethyl acetoacetate. .
These gelling agents may be used alone or in combination of two or more.
The amount added is preferably 15% by weight or less of the resin in the ink, and more preferably 5 to 10% by weight.

An extender pigment may be added to the ink to prevent bleeding or to adjust the viscosity. Examples of extender pigments include white clay, silica, talc, clay, calcium carbonate, barium sulfate, titanium oxide, white alumina, diatomaceous earth, kaolin, mica, aluminum hydroxide, organic bentonite, and polyacrylic acid esters, Examples thereof include organic fine particles such as polyurethane, polyester, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, polysiloxane, phenol resin, and epoxy resin, or fine particles made of a copolymer thereof.
The amount of extender added is preferably from 0.1 to 50% by weight, more preferably from 1 to 5% by weight of the total ink.

In the present invention, when there is no material that is affected by the electrolyte in the aqueous phase, it is preferable to add the electrolyte to the aqueous phase in order to increase the storage stability of the emulsion. The addition amount is preferably 0.1 to 2% by weight of the aqueous phase.
The electrolyte preferably contains an anion such as citrate ion, tartrate ion, sulfate ion or acetate ion, or an alkali metal ion or alkaline earth metal ion. For example, magnesium sulfate, sodium sulfate, sodium citrate, sodium hydrogen phosphate, sodium borate, sodium acetate and the like are preferable. These electrolytes may be used alone or in combination of two or more.

An antibacterial agent may be added to the aqueous phase as necessary. Examples thereof include aromatic hydroxy compounds such as salicylic acid, phenols, methyl p-oxybenzoate, ethyl p-oxybenzoate and their chlorine compounds, sorbic acid and dehydroacetic acid, MIT (methylisothiazoline), BIT (butylisothiazoline). ), Thiazoline-based compounds such as OIT (octylisothiazoline), organic nitrogen sulfur compounds, and the like. These may be used alone or in combination of two or more. The amount added is preferably 3% by weight or less, more preferably 0.1 to 1.2% by weight of water contained in the ink.
Further, a water evaporation inhibitor and an antifreeze agent may be added to the aqueous phase. These can be used in combination, for example, glycols such as ethylene glycol, diethylene glycol and propylene glycol, lower saturated monohydric alcohols such as methanol, ethanol, isopropanol, butanol and isobutanol, and polyhydric alcohols such as glycerin and sorbitol. These may be used alone or in combination of two or more. The addition amount is preferably 15% by weight or less of water in the ink, and more preferably 4 to 12% by weight.

In addition, a water-soluble polymer compound may be added to the aqueous phase for moisture retention and viscosity. Examples include starch, mannan, sodium alginate, galactan, tragacanth gum, gum arabic, bull run, dextran, xanthan gum, glue, gelatin, collagen, casein and other natural polymer compounds, carboxymethylcellulose, methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose. , Semi-synthetic polymer compounds such as piroxypropylmethylcellulose, piroxymethyl starch, carboxymethyl starch, dialdehyde starch, neutralized products such as acrylic acid resin and sodium polyacrylate, polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl pyrrolidone and poly Acrylic acid copolymer, polyacrylamide, poly N-alkyl substituted acrylamide, polyethylene oxide, poly Synthetic polymer compounds such as vinyl methyl ether.
These may be used alone or in combination of two or more. The amount added is preferably 25% by weight or less, more preferably 0.5 to 15% by weight of the total ink.

The ink cartridge of the present invention contains the ink of the present invention in a container, and has other members or the like appropriately selected as necessary.
The container is not particularly limited, and its shape, structure, size, material and the like can be appropriately selected according to the purpose. For example, an ink bag formed of a plastic container, an aluminum laminate film, a resin film, etc. The thing which has is mentioned.
1 and 2 show examples of the configuration of the ink container.
FIG. 1 is an example of a stencil ink container. After the ink is filled into the ink bag 101 from the ink injection port 102, the cap 103 is closed. At the time of use, the cap 103 is removed and the ink injection port 102 is set in the holder of the apparatus main body to supply ink to the apparatus. The ink bag 101 is formed of a packaging member such as a plastic film. The ink bag 101 is accommodated in a cartridge case 104 made of normal paper, and is used as an ink cartridge 105 that is detachably attached to an image forming apparatus.

  FIG. 2 shows an example of an ink jet ink container. After the ink is filled into the ink bag 201 from the ink injection port 202 and exhausted, the ink injection port 202 is closed by fusion. In use, ink is supplied to the apparatus by inserting a needle of the apparatus main body into the ink discharge port 203 made of a rubber member. The ink bag 201 is formed of a packaging member such as a non-permeable aluminum laminate film. The ink bag 201 is usually accommodated in a cartridge case 204 made of plastic, and is used as an ink cartridge 205 that is detachably attached to the image forming apparatus.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, unless it deviates from the technical idea of this invention, this invention is not limited by these Examples.

Examples 1-14, Comparative Examples 1-4
<Preparation of emulsion ink>
The emulsion ink of the present invention can be produced by preparing an oil phase and an aqueous phase in the same manner as in conventional emulsion ink production, and emulsifying both in a known emulsifier.
That is, a colorant, a dispersant, and a surfactant shown in the columns of Examples and Comparative Examples in Tables 1 to 3 were kneaded to form a dispersion, and an oil was mixed with this to prepare an oil phase.
On the other hand, a colorant, a dispersant, ion-exchanged water, a water-soluble organic solvent, an amphiphilic solvent, an electrolyte, an antibacterial agent, and oil were mixed to prepare an aqueous solution (aqueous phase).
Next, the above aqueous solution was gradually added to the oil phase and emulsified to obtain an emulsion ink.

Details of the materials used in the examples and comparative examples are as follows.
Carbon black: Raven 1080 made by Colombian Carbon
Copper phthalocyanine: manufactured by Dainichi Seika Co., Ltd., SEIKALIGHT BLUE A612
・ Polyglycerin fatty acid ester: Nikko Chemicals, NIKKOL Tetrag
lyn 1-SV (HLB = 6.0)
・ Sorbitan monooleate: Nikko Chemicals, NIKKOL SO-10V
Polyvinyl pyrrolidone: manufactured by Nippon Shokubai Co., Ltd., K-30W
・ Glycerin: manufactured by NOF Corporation ・ 1,3-butanediol: manufactured by Kanto Chemical Co., Ltd. ・ bisethoxydiglycol succinate (compound represented by the above general formula)
: High alcohol star DCS, manufactured by Higher Alcohol Industry
Dilauroyl glutamic acid lysine sodium: manufactured by Asahi Kasei Chemicals, Perisea LB-10
Magnesium sulfate: manufactured by Kanto Chemical Co., Ltd. Organic nitrogen-based sulfur compound (antibacterial agent): Dell Top 512 manufactured by Nippon Enviro Chemicals
Soybean oil fatty acid methyl ester: Vertec Biosolvents, Ver.
tecbio Gold # 4 (Iodine value = 119.5)
・ Soybean oil fatty acid butyl ester: Venesol MB manufactured by Kaneda
Soybean oil fatty acid octyl ester: # 5090 (Iodine number = 86.3) manufactured by Kaneda Corporation

<Evaluation of emulsion ink>
Various characteristics of each emulsion ink were evaluated as follows. Since Comparative Example 4 could not be emulsified, the evaluation of characteristics was omitted. The results are summarized in Tables 1 to 3.

Ink fixability A stencil printing machine manufactured by Tohoku Ricoh Co., Ltd .: A Priport N500 was used to print an image in which solid images of 10 mm × 10 mm were arranged at a total of five locations at the four corners and the center of the recording medium at a speed of 120 rpm.
Next, the image density of the solid portion at the center was measured with a reflection optical densitometer (Macbeth: RD914).
Next, the solid portion at the center was rubbed 10 times with a clock meter manufactured by Yasuda Seiki Seisakusho with an eraser, and the image density was measured again with a reflective optical densitometer.
Then, a value obtained by dividing the image density difference before and after rubbing by the initial image density was calculated as a fixing rate. In addition, it is excellent, so that this figure is large.

-Paper curl amount Stencil printing machine manufactured by Tohoku Ricoh Co., Ltd .: Using a Priport N500, a solid image of 100 mm × 190 mm (tip margin 10 mm, left margin 10 mm each) was printed at a speed of 60 rpm, and the tenth image was output. The curl amount after 10 seconds was measured. In consideration of paper variation, the average value when the same operation was repeated three times was adopted.

・ High temperature storage stability Each emulsion ink is allowed to stand for 45 days at 60 ° C., and the viscosity of the ink before and after being left is measured with a viscometer (Bohlin: CSR-10). It was evaluated according to the evaluation criteria.
○: Little difference in viscosity before and after standing.
Δ: Some difference in viscosity is observed before and after standing.
X: A significant difference in viscosity is observed before and after standing.

From each of Examples and Comparative Examples 1 to 3, it can be seen that storage stability is improved in addition to fixability and curl resistance by containing an amphiphilic solvent in the aqueous phase.
From Examples 1-2 and Comparative Example 4, it can be seen that emulsification is possible if the bisethoxydiglycol succinate content is 20% by weight or less of the total ink, but it is impossible to emulsify if it exceeds 20% by weight. .
From Examples 3 to 8 and Example 1, it can be seen that curling resistance is improved by adding various ester oils to the aqueous phase.
From Examples 3 to 7 and Example 8, it can be seen that when glycerin is further added to the aqueous phase, the curl resistance and the storage stability are improved.

DESCRIPTION OF SYMBOLS 101 Ink bag 102 Ink inlet 103 Cap 104 Cartridge case 105 Ink cartridge 201 Ink bag 202 Ink inlet 203 Ink discharge port 204 Cartridge case 205 Ink cartridge

International Publication No. 2008-96845

Claims (8)

  It consists of an oil phase and an aqueous phase, and a colorant and a dispersant are contained in at least one of the oil phase and the aqueous phase, and the aqueous phase contains 5 to 20% by weight of an amphiphilic solvent based on the whole ink. Emulsion ink. The emulsion ink according to claim 1, wherein the amphiphilic solvent is bisethoxydiglycol succinate represented by the following general formula.

  The emulsion ink according to claim 1 or 2, further comprising an ester oil in the aqueous phase.   The emulsion ink according to claim 3, wherein the ester oil is at least one selected from soybean oil fatty acid methyl ester, soybean oil fatty acid butyl ester, and soybean oil fatty acid octyl ester.   The emulsion ink according to claim 3 or 4, wherein the content of the ester oil is 10 to 30% by weight based on the content of the bisethoxydiglycol succinate.   The emulsion ink according to any one of claims 1 to 5, further comprising glycerin in an aqueous phase.   Furthermore, surfactant is contained in an oil phase, The emulsion ink in any one of Claims 1-6 characterized by the above-mentioned.   An ink cartridge comprising the emulsion ink according to claim 1 contained in a container.

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