JP2012144629A - Inkset and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkset that has environment load, comprising a first ink that does not contain a toxic colorant comprising an environmentally harmful copper and a second ink that contains a resin causing no degradation in biodegradability when a recycled paper is made; and to provide an image forming method using the same.SOLUTION: The image forming method includes: making the first ink adhere to a medium to be recorded through an inkjet system; and then making the second ink containing a polylactic acid-based resin aqueous dispersion adhere to the medium. The first ink comprises: ferric ferrocyanide; and an alkylene oxide adduct-type nonionic surfactant or an alkylene oxide adduct phosphate ester-type anionic surfactant, both having a hydrophile-lipophile balance (HLB) of 15 or more.

Description

  The present invention relates to an ink set and an image forming method using the ink set.

Inks used for ink jet recording generally contain water as a main component and contain a colorant and a wetting agent. A dye is mainly used as the colorant. However, in the case of the dye-based ink, the light resistance of the image is inferior, and there is a problem with plain paper not provided with a protective layer containing an ultraviolet absorber or the like. Therefore, in order to improve weather resistance, light resistance has been improved by using a phthalocyanine copper derivative having good light resistance as a dye.
In recent years, ink using a pigment as a colorant has begun to be used, and defects such as light resistance have been greatly improved. As a cyan pigment, a phthalocyanine copper pigment has better color development and a better hue than conventional ones. Therefore, in the inkjet method, cyan printing is generally performed using a phthalocyanine copper pigment.
However, by using a phthalocyanine copper derivative or a phthalocyanine copper pigment, the color developability and light resistance are improved, but the copper in the colorant is discharged into the environment every time the printed matter is discarded. Although there is little concern that copper ions accumulate in the living body, the water pollution control method is supposed to keep it at 3 mg / L or less, and it is obliged to keep it at 1.0 mg / L or less as a tap water quality standard. .

On the other hand, when making recycled paper, in ink jet printing, the printed part cannot be recovered by flotation by separating the printed part from the paper as in the conventional printing method. There is no way to improve whiteness. For this reason, a large amount of washing wastewater contaminated by the ink-jet ink is generated to produce recycled paper.
Further, when microbial treatment is performed to purify the waste water, copper contained in the colorant may act as a poison against the microorganisms, reducing the activity of the microorganisms and possibly hindering the purification process. Furthermore, the toxicity of copper may become a problem when waste paper recycling of ink-jet printed matter is performed in the future. Currently, the biodegradable plastic standards of the Japan Bioplastics Association (clean plastic standards), Cd: 0.5 mg / kg, As: 3.5 mg / kg, Hg: 0.5 mg / kg, in accordance with toxic metals Cu: 37.5 mg / kg, Se: 0.75 mg / kg, Ni: 25 mg / kg, Zn: 150 mg / kg, Mo: 100 mg / kg The upper limit of content is determined, Control of toxic metals is being sought.

In addition, in order to improve the weather resistance and fixability of the ink-jet printed matter, and to impart texture and gloss, a treatment liquid containing a resin is applied before and after printing. Resin components such as toner and printing ink are peeled off and separated and recovered from the paper in the process of recycling used paper, but the resin treated with the solvent impregnates the fiber, so it cannot be peeled off from the paper and recycled as paper. Make it difficult. For this reason, it will be discarded without being recycled, but since the impregnated resin will reduce the biodegradability that paper originally had, it is difficult to proceed with decomposition in the soil, and only the combustion process is possible. is there.
In addition, although the coating agent using the ink using a bitumen and polylactic acid-type resin is well-known (refer patent documents 1-3), there is no example used combining these for the objective like this invention.

  The present invention provides an environmental load consisting of a first ink that does not contain a colorant containing copper that is toxic and harmful to the environment, and a second ink that contains a resin that does not reduce biodegradability when making recycled paper. It is an object to provide a low ink set and an image forming method using the ink set.

The above problems are solved by the following inventions 1) to 4).
1) a first ink containing ferric ferrocyanide and an alkylene oxide adduct type nonionic surfactant having an HLB of 15 or more or an alkylene oxide adduct phosphate ester type anionic surfactant; and polylactic acid An ink set comprising a second ink containing a water-based resin aqueous dispersion.
2) The ink set according to 1), wherein the alkylene oxide adduct type nonionic surfactant is a β-naphthalene alkylene oxide adduct.
3) A first ink containing ferric ferrocyanide and an alkylene oxide adduct having an HLB of 15 or more or an alkylene oxide adduct phosphate ester type anionic surfactant is adhered to a recording medium by an inkjet method. Then, a second ink containing the polylactic acid resin aqueous dispersion is adhered to a recording medium.
4) The image forming method according to 3), wherein the alkylene oxide adduct type nonionic surfactant is a β-naphthalene alkylene oxide adduct.

  According to the present invention, an environmental load comprising a first ink that does not contain a colorant containing copper that is toxic and harmful to the environment, and a second ink that contains a highly biodegradable resin when making recycled paper. And an image forming method using the ink set.

Hereinafter, the present invention will be described in detail.
The ink set of the present invention includes a first ink and a second ink.
<First ink>
The first ink according to the present invention is not limited to the normal recording ink, but liquefies within the durable temperature range of the head member such as a resist, a DNA sample in the medical field, and a resin lens material in the optical field depending on the intended use. Any material can be used.
As the colorant of the first ink, ferric ferrocyanide of the pigment is used from the viewpoint of safety after being released to the natural world and water resistance, but a pigment containing no other harmful metal may be used in combination. .
Usually, the pigment is added as a dispersion. The pigment dispersion is obtained by dispersing pigment particles in a solvent such as water or a solvent. The pigment particles are highly dispersed in a solvent with high hydrophobicity so that the pigment particles are stably dispersed in the solvent. It is processed into a state.
Examples of pigments used in combination include water-dispersible pigments added to correct the color tone of cyan, and a self-dispersing pigment in which at least one hydrophilic group is bonded to the pigment surface directly or through another atomic group And polymer emulsions in which water-insoluble or poorly soluble pigments are contained in resin fine particles, water-dispersible pigments that are dispersed and stabilized by a surfactant or a water-soluble polymer compound having an average molecular weight of 50000 or less.
Such water-dispersible pigments have excellent water resistance, light resistance, and gas resistance because the pigment particles are in an aggregated state (including crystal state) or coexist with resin molecules and do not exist as single molecules. Contributes to improving image storage stability. In particular, when the self-dispersing pigment or polymer emulsion is used, the ink viscosity with respect to the colorant solid content can be kept low, so that a large amount of water-dispersible resin or wetting agent can be added.

  As pigments other than ferric ferrocyanide, organic pigments and inorganic pigments can be used, and organic pigments are particularly preferred in terms of specific gravity. A mixture of these pigments may be used. The volume average particle diameter of the pigment is preferably from 0.01 to 0.30 μm. If the particle size is less than 0.01 μm, the light resistance and feathering will deteriorate due to the particle size approaching that of the dye. If it exceeds 0.30 μm, the discharge port will be clogged and the filter inside the printer will be clogged. Stability cannot be obtained.

The first ink contains an alkylene oxide adduct type nonionic surfactant having an HLB of 15 or more or an alkylene oxide adduct phosphate type anionic surfactant as a pigment dispersant.
In order to disperse the pigment in the solvent, a surfactant having an HLB of 15 to 19.5 is preferable. If the HLB is less than 15, the compatibility of the surfactant with the dispersion medium is poor and the dispersion stability tends to deteriorate. If the HLB exceeds 19.5, the surfactant becomes difficult to adsorb on the pigment, so that the dispersion stability is also reduced. There is a tendency to deteriorate.
The surfactant HLB (Hydrophile-Lipophile Balance) is generally calculated by the Griffin method. The calculation formula is HLB value = 20 × (weight% of hydrophilic group). If an anionic group is included, it cannot be directly calculated by the Griffin method. Therefore, the value calculated by the Devices method, the Oda method using an organic conceptual diagram, etc. (introduction to immersion surfactant) is appropriately converted to the value by the Griffin method. The value obtained in this way is used.

Examples of the alkylene oxide adduct type nonionic surfactant include an alkylene oxide adduct ether type nonionic surfactant and an alkylene oxide adduct ester type nonionic surfactant.
Examples of the alkylene oxide adduct ether type nonionic surfactant include polyoxyethylene lauryl ether, polyoxyethylene myristyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether and other polyoxyethylene oleyl ethers. Polyoxyethylene alkyl phenyl ethers such as ethylene alkyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene-α-naphthyl ether, polyoxyethylene-β-naphthyl ether, polyoxyethylene monostyryl phenyl Ether, polyoxyethylene distyryl phenyl ether, polyoxyethylene alkyl naphthyl ether, polyoxyethylene monos Examples include polyoxyethylene aromatic ethers such as tyryl naphthyl ether and polyoxyethylene distyryl naphthyl ether.

Examples of alkylene oxide adduct ester type nonionic surfactants include polyoxyethylene alkyl esters such as polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene monooleate, polyethylene glycol distearate, Polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monooleate, polyoxyethylene coconut fatty acid glyceryl, polyoxyethylene hydrogenated castor oil, polyoxyethylene triisostearin Examples include glyceride ethylene oxide adducts such as acids, and sorbite ethylene oxide adducts such as polyoxyethylene tetraoleic acid. .
Examples of alkylene oxide adduct phosphate ester type anionic surfactants include polyoxyethylene alkyl ether phosphate, polyoxyethylene alkyl phenyl ether phosphate, polyoxyethylene monostyryl phenyl ether phosphate, Examples include polyoxyethylene distyryl phenyl ether phosphate.

In addition to these, nonionic or anionic surfactant dispersants, polymer dispersants and the like other than those described above can be used as appropriate. Also used are surfactants in which a part of polyoxyethylene in the above surfactant is replaced with polyoxypropylene, and surfactants condensed with a compound having an aromatic ring such as polyoxyethylene alkylphenyl ether with formalin. it can.
Examples of such anionic surfactants include polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl phenyl ether sulfate, polyoxyethylene monostyryl phenyl ether sulfate, polyoxyethylene distyryl phenyl ether sulfate, Polyoxyethylene alkyl ether carboxylate, polyoxyethylene alkyl phenyl ether carboxylate, polyoxyethylene monostyryl phenyl ether carboxylate, polyoxyethylene distyryl phenyl ether carboxylate, naphthalene sulfonate formalin condensate, melanin Sulfonate formalin condensate, dialkyl sulfosuccinic acid ester salt, sulfosuccinic acid alkyl disalt, polyoxyethylene alkyl sulfosuccinic acid disalt, alkyl sulfo Acid salts, α-olefin sulfonates, alkylbenzene sulfonates, alkylnaphthalene sulfonates, alkyl sulfonates, N-acyl amino acid salts, acylated peptides, soaps, etc., among these, polyoxyethylene Alkyl ether, polyoxyethylene alkylphenyl ether, and sulfate of polyoxyethylene distyryl phenyl ether have a high dispersion stabilizing ability and can be added within a range that does not affect the dispersion.

  Examples of polymer dispersants include aqueous polymers such as gum arabic, tragan gum, guar gum, karaya gum, locust bean gum, arabinogalactone, pectin, quince seed starch, etc., alginic acid, carrageenan. , Seaweed polymers such as agar, animal polymers such as gelatin, casein, albumin and collagen, microbial polymers such as xanthene gum and dextran, methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, carboxy in semisynthetic systems Fibrin polymers such as methylcellulose, starch polymers such as sodium starch glycolate and sodium starch phosphate, and seaweed systems such as sodium alginate and propylene glycol alginate In molecule, pure synthetic system, polyacrylic acid, polymethacrylic acid, acrylic acid-acrylonitrile copolymer, vinyl acetate-acrylic acid ester copolymer, acrylic acid-alkyl acrylate copolymer, styrene-acrylic acid copolymer , Styrene-methacrylic acid copolymer, styrene-acrylic acid-alkyl acrylate copolymer, styrene-methacrylic acid-alkyl acrylate copolymer, styrene-α-methylstyrene-acrylic acid copolymer, styrene- α-methylstyrene-acrylic acid copolymer-alkyl acrylate ester copolymer, styrene-maleic acid copolymer, vinylnaphthalene-maleic acid copolymer, vinyl acetate-ethylene copolymer, vinyl acetate-fatty acid vinyl ethylene Copolymer, vinyl acetate-maleic acid ester Coalescence, vinyl acetate - crotonic acid copolymer, vinyl acetate - acrylic acid copolymer and the like.

The amount of the surfactant added is preferably about 10 to 50% by weight of the pigment. If the addition amount is less than 10% by weight, the storage stability of the pigment dispersion and the ink may be reduced, or the dispersion may take an extremely long time. If the addition amount exceeds 50% by weight, the ink viscosity becomes too high, and the ink jet ink. As a result, the discharge stability tends to decrease.
Further, a surfactant can be added to adjust the physical properties of the ink. As such a surfactant, an anionic surfactant having a HLB of less than 15, a nonionic surfactant, and an amphoteric surfactant are used. A surfactant that does not impair the dispersion stability of the pigment is selected depending on the combination of the colorant, the wetting agent, and the water-soluble organic solvent.
Examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, oxalate sulfonate, laurate, and polyoxyethylene alkyl ether sulfate.

Nonionic surfactants include, for example, polyoxyethylene alkyl ether, polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene alkyl ester, polyoxyethylene polyoxypropylene alkyl ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene Examples thereof include alkylphenyl ether, polyoxyethylene alkylamine, and polyoxyethylene alkylamide.
Examples of amphoteric surfactants include lauryl aminopropionate, lauryl dimethyl betaine, stearyl dimethyl betaine, and lauryl dihydroxyethyl betaine. Specific examples include lauryl dimethylamine oxide, myristyl dimethylamine oxide, stearyl dimethylamine oxide, dihydroxyethyl lauryl amine oxide, polyoxyethylene coconut oil alkyl dimethyl amine oxide, dimethyl alkyl (coconut) betaine, dimethyl lauryl betaine, and the like. However, it is not limited to these.
These surfactants are Nikko Chemicals Co., Ltd., Nippon Emulsion Co., Ltd., Nippon Shokubai Co., Ltd., Toho Chemical Co., Ltd., Kao Co., Ltd., Adeka Co., Ltd., Lion Co., Ltd., Aoki Yushi Co., Ltd. ), Sanyo Kasei Co., Ltd., and NOF Corporation.

In addition to the above, an acetylene glycol surfactant may be used. For example, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3, Examples include acetylene glycols such as 6-diol and 3,5-dimethyl-1-hexyn-3-ol (for example, Surfynol 104, 82, 465, 485 or TG from Air Products (USA)). Surfinol 104, 465 and TG show good print quality.
Further, a fluorosurfactant may be used, such as perfluoroalkyl sulfonate, perfluoroalkyl carboxylate, perfluoroalkyl phosphate ester, perfluoroalkyl ethylene oxide adduct, perfluoroalkyl betaine, perfluoroalkyl. Examples thereof include amine oxide compounds, polyoxyalkylene ether polymers having a perfluoroalkyl ether group in the side chain, sulfate salts thereof, and fluorine-based aliphatic polymer esters.
Commercially available products of such fluorosurfactants include Surflon S-111, S-112, S-113, S121, S131, S132, S-141, S-145 (manufactured by Asahi Glass Co., Ltd.), Fullrad FC-93. , FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431, FC-4430 (manufactured by Sumitomo 3M), FT-110, 250, 251, 400S (Neos) Zonyl FS-62, FSA, FSE, FSJ, FSP, TBS, UR, FSO, FSO-100, FSN N, FSN-100, FS-300, FSK (manufactured by Dupont), Polyfox PF-136A , PF-156A, PF-151N (manufactured by OMNOVA), and the like, and can be easily obtained from each company.

The surfactant is not limited to these, and may be used alone or in combination. Even if it is not easily dissolved by itself in the recording liquid, it can be solubilized by mixing and exist stably.
In order to exert a penetrating effect as a surfactant for adjusting ink physical properties, the addition amount is desirably 0.01 to 5% by weight. If it is less than 0.01% by weight, the added effect is not obtained. If it is more than 5.0% by weight, the permeability to the recording medium is unnecessarily high, causing problems such as a decrease in image density and occurrence of show-through. Furthermore, 0.5 to 2% by weight is more preferable for dealing with plain paper having various physical properties.

A resin may be added to the first ink, but depending on the type of resin, adding a large amount reduces biodegradability, so a smaller amount is desirable. The resin used is not particularly limited, but the dispersible resin tends to increase in viscosity as the volume average particle size is smaller. Therefore, the volume average particle size is preferably 50 nm or more so as not to have an excessively high viscosity.
Furthermore, since the ink flow path and nozzle opening of the ink jet head are small, if large particles are present in the ink, the discharge property is deteriorated. Therefore, the volume average particle diameter is preferably 500 nm or less so as not to deteriorate the discharge property. 150 nm or less is more preferable.
The water-dispersible resin desirably has a function of fixing the water-dispersible colorant on the paper surface. In order to improve the fixability, the minimum film-forming temperature (MFT) is preferably 20 ° C. or lower. However, when the glass transition point (Tg) is less than −40 ° C., the resin film becomes more viscous and the printed matter is tacky. Therefore, a water dispersible resin having a glass transition point of −40 ° C. or higher is desirable.

In order to make the first ink have desired physical properties or to prevent clogging of the nozzles of the recording head due to drying, it is preferable to add a water-soluble organic solvent in addition to the colorant. The water-soluble organic solvent includes a wetting agent and a penetrating agent. These solvents are used alone or in combination with water.
The wetting agent is added for the purpose of preventing clogging of the nozzles of the recording head due to drying.
The penetrant is added for the purpose of improving the wettability between the recording ink and the recording medium and adjusting the penetration speed. Examples of penetrants include polyoxyethylene alkylphenyl ether surfactants, acetylene glycol surfactants, fluorine surfactants, silicon surfactants, polyoxyethylene alkyl ether surfactants, polyoxyethylene polyoxy A propylene alkyl ether surfactant is mentioned. Since these compounds can reduce the surface tension of the liquid, the wettability can be improved and the penetration rate can be increased.

An antiseptic / antifungal agent may be added to the first ink. By adding an antiseptic / antifungal agent, the growth of bacteria can be suppressed, and the storage stability and image quality stability can be improved.
A rust inhibitor may be added to the first ink. By adding a rust preventive agent, a coating can be formed on the metal surface in contact with the liquid such as a head and corrosion can be prevented.
An antioxidant may be added to the first ink. By adding an antioxidant, even when a radical species that causes corrosion is generated, the antioxidant can be eliminated so that the corrosion can be prevented.
A pH adjuster may be added to the first ink. The pH of the first ink is preferably 3 to 11, and more preferably 4 to 7 from the viewpoint of ferric ferrocyanide. The pH of the first ink can be adjusted to a preferred range by the pH adjuster.
The surface tension of the first ink is preferably 20 to 60 mN / m, and more preferably 30 to 50 mN / m from the viewpoint of achieving both wettability with the recording medium and droplet formation.
The viscosity of the first ink is preferably 1.0 to 20.0 mPa · s, and more preferably 2.0 to 10.0 mPa · s from the viewpoint of ejection stability.

The first ink, as an inkjet head, uses a piezoelectric element as pressure generating means to pressurize the ink in the ink flow path, and deforms the diaphragm that forms the wall surface of the ink flow path to change the volume in the ink flow path. A so-called piezo type that discharges ink droplets (refer to Japanese Patent Laid-Open No. 2-51734), or a so-called thermal type that generates bubbles by heating ink in an ink flow path using a heating resistor ( JP, 61-59911, A), the diaphragm and the electrode which form the wall surface of an ink channel are arranged facing, and the diaphragm is deformed by the electrostatic force generated between the diaphragm and the electrode, Any printer equipped with an ink jet head such as an electrostatic type (see Japanese Patent Application Laid-Open No. 6-71882) that changes the volume of the ink flow path to eject ink droplets. It can be used for good.
The first ink can be applied to various fields, but can be particularly suitably used for an image forming apparatus (printer or the like) based on an ink jet recording method. For example, the recording paper and the first ink can be heated at 50 to 200 ° C. before and after printing or printing, and can be used for a printer having a function of promoting print fixing.

<Second ink>
The second ink is attached to form a resin film for protecting the image formed by the first ink. Depending on the type of the resin, the biodegradability is lowered by the addition, so it is desirable to add the biodegradable resin in an amount of 50 wt% or more, and more desirably 70 wt% or more.
Although it does not specifically limit as resin to be used, Polylactic acid and its modified material are preferable as biodegradable resin. Polylactic acid has a polyester skeleton, is easily modified by copolymerization with other polyester monomers, can control crystallinity by controlling the ratio of optical isomers, and can easily control resin properties. In addition, since it is a water-insoluble resin, it does not easily swell when exposed to water when a film is formed, and is optimal for applications requiring water resistance such as surface treatment for printed images as in the present invention. .
It is also possible to add a biodegradable resin other than polylactic acid, and examples of such biodegradable resins include polycaprolactone, polyglycolic acid, modified polyvinyl alcohol, casein, modified starch, cellulose, and modified cellulose. It is done. In addition, they may be inferior to persistent resins in terms of durability and physical properties, and in order to improve their properties, general resins may be added or copolymerized with the above biodegradable resins. It is possible to modify with.

  The ratio of polylactic acid contained in the biodegradable resin is preferably 50% by weight or more, more preferably 80% by weight or more of the biodegradable resin. When the addition amount is less than 50% by weight, the water resistance of the formed resin layer tends to be low, and the durability of the image is low. In addition, many biodegradable resins other than polylactic acid are in aqueous solution, and when the addition ratio of these increases, the viscosity of the second ink becomes too high, making it difficult to increase the resin ratio in the ink. Further, when the viscosity is high, there is a drawback that the ink coating method is limited. Therefore, it is preferable to keep the ink viscosity low by increasing the amount of polylactic acid added to 80% by weight or more and to increase the resin ratio in the ink.

As a characteristic of the resin used for the second ink, it is necessary to form a film for forming an image protective layer, and it is desirable to form a dry film from room temperature to a low temperature state. When the resin ink is heated and dried after application, it is a water-based ink, so even if the drying temperature is set to 100 ° C. or higher, the temperature hardly rises to 100 ° C. or higher while liquid water is present. If the film forming temperature of the resin is 100 ° C. or less, the film can be formed in the process of eliminating liquid water, and there is an effect that a film can be formed in a short time and with energy saving. Therefore, the minimum film forming temperature is desirably 100 ° C. or lower, but more preferably 20 ° C. or lower. Here, the minimum film-forming temperature refers to the lowest temperature at which a transparent continuous film is formed when a polylactic acid resin aqueous dispersion is thinly cast on a metal plate such as aluminum and the temperature is raised. . As the measuring apparatus, a minimum film forming temperature measuring apparatus manufactured by Shimakawa Seisakusho can be used.
Although the minimum film-forming temperature varies depending on the resin, it is possible to adjust the minimum film-forming temperature by adding a film-forming temperature regulator that acts on the resin emulsion interface during the drying process or a plasticizer that softens the resin. It can be used for other resins.

Among such biodegradable resins, a water-dispersed polyester resin having lactic acid as a skeleton is preferable because it is easy to copolymerize with other components and easily introduce an ionic skeleton useful for water dispersion. In addition, if an emulsion is used, the ink viscosity when added to the second ink can be reduced, and coating can be performed at a high resin concentration.
The resin particle size in the emulsion is several μm to several tens of nm, but in the case of inkjet coating, the volume average particle size is preferably 500 nm or less, and 150 nm or less so as not to affect the nozzle mouth and restrictor. Is more preferable.
The method for applying the second ink is not particularly limited, and any method such as roller coating, spray coating, and sublimation coating may be used, and spray coating by an ink jet method is also possible. In the case of inkjet coating, the coating amount and coating position can be controlled with high accuracy and ease.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated further more concretely, this invention is not limited by these Examples.

なお、上記表１中の「Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｂｌｕｅ ２７」はフェロシアン化第二鉄・水和物であり、「Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｂｌｕｅ １５：３」はフタロシアニン銅である。
また、界面活性剤は下記表２に示すとおりであり、「Ｄ、Ｅ」はアルキレンオキサイド付加物型非イオン性界面活性剤、「Ｃ」はアルキレンオキサイド付加物リン酸エステル型アニオン性界面活性剤であり、「Ａ、Ｂ」は何れにも該当しない界面活性剤である。

<Preparation of pigment dispersion>
Preparation Examples 1-6
The pigment dispersion was prepared by the following procedure.
A predetermined amount of surfactant shown in each column of Preparation Examples 1 to 6 in Table 1 below was mixed with water and dissolved by stirring with a stirrer. Next, the pigment was added and stirred for 10 minutes, and then the mixed solution was placed in an ultrasonic cleaner, and dispersion was performed for up to 3 hours while measuring the pigment particle diameter every hour.

In Table 1, “CI Pigment Blue 27” is ferric ferrocyanide and hydrate, and “CI Pigment Blue 15: 3” is phthalocyanine copper.
Further, the surfactants are as shown in Table 2 below, “D, E” are alkylene oxide adduct type nonionic surfactants, and “C” is alkylene oxide adduct phosphate ester type anionic surfactants. “A, B” are surfactants that do not fall under any of the above.

上記表中の「ＵＳ」は超音波照射時間の略である。 The measurement results of the dispersion process are shown in Table 3 below.
In Preparation Examples 1 to 3 and 6, the particle diameter did not increase regardless of the dispersion time, and the pigment could be stably dispersed. Preparation Examples 4 and 5 were not able to disperse at all, and the pigment settled out by simply suspending ultrasonic irradiation and allowing to stand for 1 minute.

“US” in the above table is an abbreviation for ultrasonic irradiation time.

なお、上記表４中のＣ．Ｉ．Ａｃｉｄ Ｂｌｕｅ ９は、下記〔化１〕に示す化合物である。

また、溶剤の「１，３−ＢＤ」は１，３−ブタンジオール、「Ｇｌｙ」はグリセリンであり、界面活性剤の「エマルゲンＬＳ−１０６」は花王社製のポリオキシアルキレンアルキルアルコールエーテル、「Ｚｏｎｙｌ ＦＳＯ−１００」はＤｕｐｏｎｔ社製のポリオキシアルキレンパーフロロアルキルアルキルアルコールエーテルである。 <Preparation of the first ink>
Preparation Examples 7-14
The first ink was prepared according to the following procedure.
A predetermined amount of the solvent, surfactant and water shown in the columns of Preparation Examples 7 to 14 in Table 4 below were stirred and mixed uniformly with a stirrer. Next, after adding a colorant and stirring for 1 hour, the mixed solution was pressure filtered through a 5 μm filter (MILLEX SV manufactured by Nippon Pole Co., Ltd.) to obtain a first ink.

In Table 4, C.I. I. Acid Blue 9 is a compound shown in the following [Chemical Formula 1].

The solvent “1,3-BD” is 1,3-butanediol, “Gly” is glycerin, the surfactant “Emulgen LS-106” is a polyoxyalkylene alkyl alcohol ether manufactured by Kao Corporation, “ “Zonyl FSO-100” is a polyoxyalkylene perfluoroalkyl alkyl alcohol ether manufactured by Dupont.

なお、上記表５中の樹脂は下記表６、表７に示すとおりである。表中の「プラセマＬ１１０」「ランディＰＬ３０００」「テラマックＬＡＥ−０１３Ｎ」が本願発明におけるポリ乳酸系樹脂水性分散体に該当する。また、「プラセマＬ１１０」のＭＦＴ（最低造膜温度）は１１０℃と高いため、サプセラマＰＣＺを可塑剤として混合し、４０℃に下げて用いた。また、「ニッポールＬＸ４０７ＢＰ」は、０℃と１００℃の２つのＴｇを有するため「０／１００」と記載した。この樹脂はコアシェル型の構造を有し、主構成モノマーからなる単一ポリマーのＴｇのうち、ポリスチレンのＴｇが約１００℃、ポリブタジエンのＴｇが−５５℃であり、ポリスチレンとスチレン・ブタジエン共重合体がコアシェルのエマルジョンを形成した結果、０℃と１００℃のＴｇを示す。

<Preparation of second ink>
Preparation Examples 15-19
The second ink was prepared by the following procedure.
A predetermined amount of surfactant and water shown in the columns of Preparation Examples 15 to 19 in Table 5 below were stirred and mixed uniformly with a stirrer. Subsequently, after adding a resin emulsion and stirring for 1 hour, the mixed solution was pressure filtered through a 5 μm filter (MILLEX SV manufactured by Nippon Pole Co., Ltd.) to obtain a second ink.

The resins in Table 5 are as shown in Tables 6 and 7 below. “Placema L110”, “Randy PL3000”, and “Teramac LAE-013N” in the table correspond to the polylactic acid resin aqueous dispersion in the present invention. In addition, since MFT (minimum film-forming temperature) of “Placema L110” is as high as 110 ° C., supcerama PCZ was mixed as a plasticizer and used after being lowered to 40 ° C. “Nippol LX407BP” is described as “0/100” because it has two Tg of 0 ° C. and 100 ° C. This resin has a core-shell structure, and of the single polymer Tg composed of the main constituent monomer, the Tg of polystyrene is about 100 ° C., the Tg of polybutadiene is −55 ° C., and polystyrene / styrene-butadiene copolymer. Shows a Tg of 0 ° C. and 100 ° C. as a result of forming a core-shell emulsion.

Examples 1-7, Comparative Examples 1-8
<Printing method>
The firmware was changed so that the ink ejection force of the ink jet printer (IPSIO GX3000, manufactured by Ricoh Co., Ltd.) could be freely changed, and used as an evaluation printer.
Replace the ink in the printer's ink supply path and ink in the head with pure water, and replace the original ink with the first ink of Preparations 7 to 10 in place of the KCMY cartridge. After the operation, the head refreshing operation was repeated 10 times, and the ink in the ink supply path and the head was replaced with the first ink. Thereafter, a nozzle check pattern was printed, and a head refreshing operation was performed until there was no missing nozzle.
My paper (manufactured by Ricoh) was used as the evaluation paper, and “no color correction in normal paper standard fast mode” was selected as the print mode with the driver attached to the printer.
Further, a 100 cm ² single-color solid chart was printed on the fine paper manufactured by EPSON in the above-mentioned printing mode, and the discharge force of the printer was adjusted so that the amount of adhesion was 0.09 g.
Under the above conditions, a 20 cm × 20 cm single-color solid chart and 12-point single-color characters created with Microsoft Word 2000 were launched.
After the above printing, the ink supply path is similarly replaced with pure water, the first ink of Preparation Examples 11 to 14 is filled again, and the image is adjusted by the same method so that the adhesion amount is constant. Printed.

<Application of second ink>
On My Paper (Ricoh Co., Ltd.) printed with the first ink, the second ink was quickly applied using a wire bar so that the application amount was 5 g / m ^2, and then 25 ° C. × 12 hours. Dried. Then, with the printing surface in contact with the mirror-finished SUS plate, a dry iron was applied from the back side of the paper at a speed of 10 cm / sec to prepare an evaluation sample with a smooth printing surface.
Combinations of the first ink and the second ink are as shown in the columns of Examples 1 to 7 and Comparative Examples 1 to 8 in Table 8 below.

About the evaluation sample of an Example and a comparative example, it evaluated as follows.
〔Evaluation methods〕
<Water resistance test>
The character string of the evaluation sample is immersed in water at 30 ° C. for 30 minutes, and the water after the immersion is absorbed by a filter paper of 5A. From the bleeding of the character string of the evaluation sample and the ink transferred to the filter paper, the following criteria are used. evaluated. Comparative Example 7 was not evaluated because there was no image.

A: There is no bleeding.
○: There is no bleeding visually, but there is ink bleeding up to about 0.05 mm around the character.
(Triangle | delta): There exists a blur of the grade recognized visually.
X: The more the ink is transferred to the filter paper, the more the ink oozes out and the lower the character density.

<Fixability test>
After the evaluation sample was brought into contact with JISL 0803 cotton No. 3 using a clock meter CM-1 and rubbed 10 times, the ink adhering to the cotton cloth was measured with a spectrocolorimetric densitometer (Model-938 manufactured by X-Rite). The following criteria were used to evaluate the color density relative to the initial cotton cloth color. Comparative Example 7 was not evaluated because there was no image.

○: Concentration increase of cotton cloth is less than 0.1 ×: Concentration increase of cotton cloth is 0.1 or more

<Biodegradability test>
The evaluation sample was buried in pseudocompost and allowed to stand at 30 ° C. for 1 month, and then the state of the evaluation sample was evaluated according to the following criteria.

○: The shape of the sample is not maintained.
X: The sample shape is maintained.

<Soil contamination test>
The first ink used for preparing the evaluation sample was analyzed with an ICP emission spectroscopic analyzer, and Cd: 0.5 mg / kg, As: 3.5 mg / kg, Hg according to the Clean Plastic Standard of the Japan Bioplastics Association. : Evaluation of whether or not the reference upper limit values of 0.5 mg / kg, Cu: 37.5 mg / kg, Se: 0.75 mg / kg, Ni: 25 mg / kg, Zn: 150 mg / kg, Mo: 100 mg / kg are satisfied did. Table 9 shows the evaluation results. ND in the table indicates the detection sensitivity or lower. Further, since the second ink does not contain a color material, it is easy to remove heavy metals, and it is technically easy to avoid soil contamination.

○: Both are less than the reference upper limit ×: More than the reference upper limit

JP 2008-069304 A Special table 2001-508482 gazette JP 2006-263916 A

Claims (4)

  A first ink containing ferric ferrocyanide and an alkylene oxide adduct-type nonionic surfactant or an alkylene oxide adduct phosphate ester-type anionic surfactant having an HLB of 15 or more, and a polylactic acid resin An ink set comprising a second ink containing an aqueous dispersion.   The ink set according to claim 1, wherein the alkylene oxide adduct type nonionic surfactant is a β-naphthalene alkylene oxide adduct.   A first ink containing ferric ferrocyanide and an alkylene oxide adduct-type nonionic surfactant having an HLB of 15 or more or an alkylene oxide adduct phosphate ester-type anionic surfactant is coated by an inkjet method. An image forming method, comprising: adhering to a recording medium, and then adhering a second ink containing a polylactic acid resin aqueous dispersion to the recording medium.   The image forming method according to claim 3, wherein the alkylene oxide adduct type nonionic surfactant is a β-naphthalene alkylene oxide adduct.