JP2000086957A - Recording solution for image display and image formation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a recording solution for image display having neither oozing of image on a recording paper nor clogging in a nozzle and to provide a method for forming an image by using the recording solution. SOLUTION: A recording solution for image display comprising water, a colorant and a humectant is mixed with a silanol group modified polyvinyl alcohol. Preferably the vapor pressure at 25 deg.C is preferably <=0.1 mmHg. Preferably the content of the humectant is >=10 wt.% and <=90 wt.% based on the recording solution for image display. An image is formed by using the recording solution for image display by an ink-jet method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a recording liquid for image display, and more particularly to a recording liquid for image display suitable for forming an image by an ink jet recording method.

[0002]

2. Description of the Related Art In recent years, an ink jet system has been attracting attention as an output device of an information device such as a computer as a system having a low running cost, high definition and easy color. Conventionally, aqueous dye solutions have been mainly used as inks for inkjet. However, when the ink ejected from the nozzles and flies onto the recording paper,
There is a problem that the ink bleeds on the recording paper and becomes larger dots than ink droplets formed at the time of flying, and that the density of the recorded image is low. In addition, solid matter is generated from a part of the ink component in the nozzle, and the flying direction of the ink is disturbed,
There is a problem that nozzle clogging occurs.

In order to solve such a problem, JP-A-5-208548 discloses a technique using a reactive dye, and JP-A-6-128514 discloses a technique in which coagulation and precipitation occur upon contact with ink. A technique for separately printing components on ink has been disclosed. However, the former technique using a reactive dye is not suitable for full-color printing because the kind of the dye is limited. The latter technique of separately printing the agglomerated component can improve water resistance and reduce bleeding. However, since one kind of ink required for printing is added, the printing apparatus becomes large, and printing time is increased. There was a problem that it was slow. Further, in these techniques, since the ejection direction is disturbed and clogged, a cleaning mechanism and a capping mechanism are required, and the system is complicated.

A humectant is generally added to ink in order to improve the formation of clogs and clogging in such nozzles. JP-A-6-16984 discloses a technique in which the vapor pressure of a humectant is set to 0.01 mmHg or less, and JP-A-8-295834 discloses a technique in which a specific penetrant and a humectant are combined. . However,
Although the clogging is eliminated by these methods, the problem that bleeding occurs because the humectant does not evaporate on the paper surface remains.

For the purpose of solving both the problems of image bleeding and clogging, Japanese Patent Application Laid-Open No. Hei 10-7962 discloses a technique in which glycerin is added to ink at 8% by weight or more and alginate. ing. However, there is a problem that the viscosity of the ink is increased by the action of alginic acid and a large load is applied to the ejection.

Further, in order to reduce clogging and bleeding due to evaporation of water in a water-based ink at room temperature, Japanese Patent Application Laid-Open No.
Japanese Patent No. 94779 discloses a technology using an organic compound such as a hydrocarbon resin which is incompatible with water at room temperature solid.
Japanese Patent Publication No. 35641 discloses a technique using ink solidified by adding a gelling agent. However, when a hydrocarbon-based resin is used at room temperature as a dispersion medium as in the former technique, when printing is performed by heating and melting, low-molecular-weight hydrocarbons contained in the hydrocarbon resin are partially evaporated to give off-odor. And the possibility of polluting the air in the office environment. In addition, since images with this ink do not have sufficient image intensity, and furthermore, dispersible dyes are limited to oil-soluble dyes. Could not be used. Further, when using an ink solidified by adding a gelling agent as in the latter technique, it is common to combine an aqueous gelling agent with an aqueous dispersion medium and a non-aqueous gelling agent with a non-aqueous dispersion medium. Therefore, an optimal gelling agent for a mixed system as in an actual ink has not been selected. For this reason, even when the gelled ink is used, the ink oozes out from the inside of the gel on the paper and causes bleeding, or the ink is set off, which is not suitable for practical use.

[0007]

As described above, the conventional ink-jet ink satisfies both the requirements of obtaining a high-quality image without bleeding and obtaining the reliability of ejection directionality and clogging. I couldn't let it. Therefore, the present invention solves the above-mentioned problems of the prior art, and does not cause ink bleeding on recording paper, especially plain paper,
In addition, without causing precipitation or clogging in the nozzle of the inkjet printer, a recording liquid for image display capable of obtaining high reliability of the head, particularly a recording liquid for image display suitable for an inkjet method. And an image forming method using the same.

[0008]

The present inventor believes that the cause of ink bleeding is the humectant that permeates and spreads inside the paper without evaporating, and suppresses the penetration of the humectant to form the ink on the paper. I searched for a way to stay. As a result of intensive research on the gelling agent as an additive for the ink that solidifies on the paper, as a result, if the gelling agent has both the property of solidifying the ink and the property of reacting with the paper, It has been found that elution can be controlled. Furthermore, the silanol group-modified polyvinyl alcohol has a gelling property,
In addition, they have found that they react with metal salts contained in paper and solidify. Further, they have found that an ink having suitable evaporation characteristics can be obtained by regulating the vapor pressure and the amount of addition of the humectant, and completed the present invention based on these findings.

Accordingly, the present invention provides an image display recording liquid characterized by containing water, a colorant, a humectant and a silanol group-modified polyvinyl alcohol, and recording the image display recording liquid by an ink jet method. The image forming method or the ink jet method is a thermal type ink jet method.

As described in Maruyama (Hitoshi Maruyama: Polymer, Vol. 47, January, 38 (1998)), silanol group-modified polyvinyl alcohol has been developed as a new polyvinyl alcohol for paper processing agents. When a conventional polyvinyl alcohol aqueous solution penetrates into the paper at the time of application to the paper, when an aqueous solution of silanol group-modified polyvinyl alcohol is applied to the paper, clay, silica, calcium carbonate contained as a filler of the paper are contained. Etc., and thickens and solidifies in the surface layer without permeating into the paper. The present inventor has further found that silanol group-modified polyvinyl alcohol has a property of gelling when added to a humectant used for a recording liquid. That is, when a silanol group-modified polyvinyl alcohol is added to a recording liquid containing water, a colorant and a humectant, when the recording liquid lands on the paper, the recording liquid itself gels on the paper, and further, the paper and the gelling agent It has been found that the interface has the two characteristics of solidifying with the reaction of silanol groups. Therefore, by adding the silanol group-modified polyvinyl alcohol to the recording liquid, bleeding of the image can be prevented, and the image can be of high image quality without dot bleeding or intercolor bleeding. Further, the evaporation of the ink can be prevented by defining the vapor pressure related to the evaporation characteristics of the added humectant and the amount of addition. As a result, when the recording liquid is used in an ink jet printer, clogging of nozzles does not occur, and an unpleasant odor due to evaporation does not occur, so that reliability and environmental resistance can be improved.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The present invention is a recording liquid for image display, characterized by adding a silanol group-modified polyvinyl alcohol to a recording liquid for image display containing water, a colorant and a humectant.

The silanol-modified polyvinyl alcohol used in the recording liquid for image display of the present invention is a polymer (A) having at one end a functional group selected from silicon-containing groups which can be converted to silanol groups in the presence of water. A resin composition obtained by saponifying a vinyl ester polymer (B) in the presence thereof, which is described in JP-A-8-188621.

The polymer (A) having at one end a functional group selected from silicon-containing groups that can be converted to silanol groups in the presence of water is defined as a polymer having a silicon-containing group that can be converted to silanol groups in the presence of water. And a polymer bonded only to one end of the polymer by a silicon-carbon bond. The silanol group is represented by the following formulas I to III.

[0014]

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[0015]

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[0016]

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A silicon-containing group which can be converted to a silanol group in the presence of water (hereinafter simply referred to as "silicon-containing group")
May be any silicon-containing group that can be converted to the silanol group represented by the above formulas I to III by hydrolysis in the presence of water, and the polymer (A) may be water or water. A group that can be converted to a silanol group when hydrolyzed in a mixed liquid of a solvent and an organic solvent (toluene, xylene, acetone, etc.) under the conditions of a reaction time of 10 minutes to 2 hours and a reaction temperature of room temperature to 150 ° C means.

As a typical example of such a silicon-containing group,
Examples include a trialkoxysilyl group represented by the following formula IV, a dialkoxyalkylsilyl group represented by the following formula V, and an alkoxydialkylsilyl group represented by the following formula VI.

[0019]

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[0020]

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[0021]

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(Wherein R ¹ , R ² and R ³ are an aliphatic hydrocarbon group (for example, a linear or branched alkyl group or alkenyl group having 1 to 20 carbon atoms), an alicyclic hydrocarbon group) (e.g., cycloalkyl group, cycloalkenyl group), an aromatic hydrocarbon group (e.g., phenyl group, biphenyl group) ^{represents, R 1, R 2, R} 3 may be the same or different. also, R ¹ , R ² and R ³ may have other groups such as a carboxyl group and a halogen atom.)

Specific examples of the silicon-containing groups represented by the above formulas IV to VI include trimethoxysilyl, triethoxysilyl, triisopropoxysilyl, dimethoxymethylsilyl, diethoxymethylsilyl, methoxydimethyl And a silyl group and an ethoxydimethylsilyl group.

The polymer (A) is not particularly limited as long as it has at one end a functional group selected from silicon-containing groups which can be converted to silanol groups in the presence of water. Polymer, aromatic vinyl polymer,
Acrylamide polymer, methacrylamide polymer,
N-vinylamide polymers, oxyalkylene polymers, vinyl ester polymers, vinyl cyanide polymers, vinyl halide polymers, vinyl ether polymers and the like can be used.

The monomers constituting these polymers include methacrylic acid and its salts, methyl methacrylate,
Methacrylic acids such as ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, n-dodecyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, monoglycerin methacrylate; styrene, α-methylstyrene, t-butylstyrene And aromatic vinyls such as vinylnaphthalene; N-alkylacrylamides such as acrylamide and N-isopropylacrylamide; N, N-dimethylacrylamide; 2-acrylamidopropanesulfonic acid and its salts; acrylamidopropyldimethylamine; Acrylamides such as quaternary salts; N-alkylmethacrylamides such as methacrylamide and N-isopropylmethacrylamide; N, N-dimethylmethacrylamide; 2-methacrylic Amide propane sulfonic acid and its salts, methacrylamide propyl dimethylamine, its salts and methacrylamides of such quaternary salts; N-
N-vinylamides such as vinylpyrrolidone, N-vinylformamide and N-vinylacetamide; oxyalkylenes such as oxyethylene, oxypropylene and oxytetramethylene; vinyl formate, vinyl acetate, vinyl propionate, vinyl versatate and pivalic acid Vinyl esters such as vinyl; vinyl cyanides such as acrylonitrile and methacrylonitrile; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl fluoride and vinylidene fluoride; methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether and butyl vinyl ether ,
Examples thereof include vinyl ethers such as hydroxyethyl vinyl ether, hydroxypropyl vinyl ether, hydroxybutyl vinyl ether, and methoxyethyl vinyl ether. The molecular weight of the polymer (A) is not particularly limited,
It is preferably from 50 to 100,000, more preferably from 100 to 50,000.

The vinyl ester polymer (B) which saponifies in the presence of a polymer (A) having at one end a functional group selected from silicon-containing groups which can be converted to a silanol group in the presence of water includes: Examples include homopolymers and copolymers of vinyl esters such as vinyl formate, vinyl acetate, vinyl propionate, vinyl versatate, and vinyl pivalate.

Further, the vinyl ester polymer (B) is
As long as the effects of the present invention are not impaired, the copolymer may be copolymerized with another unsaturated monomer copolymerizable with the vinyl ester. The unsaturated monomers include propylene excluding ethylene, 1
Olefins such as butene and isobutene; acrylic acid,
Methacrylic acid, crotonic acid, itaconic acid, maleic acid,
Unsaturated acids such as maleic anhydride, salts thereof, and mono- or dialkyl esters having 1 to 18 carbon atoms; acrylamide, N-alkylacrylamide having 1 to 18 carbon atoms, N, N-dimethylacrylamide, 2-acrylamidepropanesulfone Acrylamides such as acids and salts thereof, acrylamidopropyldimethylamine, acid salts and quaternary salts thereof; methacrylamide, having 1 to 1 carbon atoms
Methacrylamides such as N-alkyl methacrylamide, N, N-dimethyl methacrylamide, 2-methacrylamidopropanesulfonic acid and salts thereof, methacrylamidopropyldimethylamine, acid salts and quaternary salts thereof; N-vinyl; N-vinylamides such as pyrrolidone, N-vinylformamide, N-vinylacetamide;
Allyl compounds such as allyl acetate, allyl chloride and allyl alcohol 8-hydroxy-1-octene; vinyl cyanides such as acrylonitrile and methacrylonitrile; alkyl vinyl ethers having 1 to 18 carbon atoms, hydroxyalkyl vinyl ethers and alkoxyalkyl vinyl ethers Vinyl ethers; vinyl chloride, vinylidene chloride,
And vinyl halides such as vinyl fluoride and vinylidene fluoride.

The degree of polymerization of the vinyl ester polymer (B) is not particularly limited, and the degree of polymerization of polyvinyl alcohol obtained by completely saponifying the polymer is preferably 50 to 30,000. It is more preferably 10,000, and particularly preferably 100 to 5,000.

Specific examples of the silanol group-modified polyvinyl alcohol which can be used in the recording liquid for image display of the present invention include R-1130, R-2105 and R-2130 which are Kuraray functional polymers manufactured by Kuraray Co., Ltd. Etc. can be used. The content of the silanol group-modified polyvinyl alcohol in the recording liquid for image display depends on the solubility in the recording liquid, the viscosity at the time of ejection, and the like. %, More preferably 0.5 to 10% by weight. If the content of the silanol group-modified polyvinyl alcohol is less than 0.1% by weight, the recording liquid may not be completely gelled, which may cause image bleeding, making it difficult to obtain a high quality image. It is not preferable. On the other hand, if it exceeds 20% by weight, the excess gelling agent becomes difficult to dissolve and may precipitate. Further, even when heated, the viscosity tends to be insufficiently reduced, and the ejection tends to be unstable, which is not preferable. One type of silanol-modified polyvinyl alcohol may be used alone, or two or more types may be used in combination when they are completely mixed when dissolved in a solvent to form one phase.

In addition, for the purpose of assisting gelation,
A gelling agent other than silanol-modified polyvinyl alcohol can be added to the recording liquid for image display of the present invention. Gelling agents that can be used in combination with silanol group-modified polyvinyl alcohol include water-soluble gelling agents, oil-soluble Any of the gelling agents can be used. But,
If a gelling agent such as a calcium or aluminum salt of a higher alkyl or alkene fatty acid has a structure that reacts with silanol groups, it may thicken and solidify in the recording liquid before reacting with the paper. Is not preferred.

Accordingly, gelling agents that can be added include polysaccharides such as gelatin, carrageenan, agarose, guar gum and locust bean gum, aluminum di-n-butoxide monoethyl acetate, aluminum di-mono-butoxide monoethyl. Acetate, derivative of aluminum alkoxide, n-lauroyl-L-glutamic acid-α, γ-di-n-phthalamide, dicaproyl lysine lauryl amide, lauroyl phenylalanine lauryl amide, lauroyl glutamic acid stearyl amide, dicaproyl lysine lauryl ester, dica Proyl lysine amine salt, lauroyl valine butyramide,
Acyl amino acid derivatives such as lauroylphenylalanine laurylamide, 12-hydroxystearic acid, dibenzylidene sorbitol and the like. One of these gelling agents may be used alone, or two or more thereof may be used in combination when they are mixed in a solvent to form a complete phase.

The humectant contained as an essential component in the recording liquid for image display of the present invention is not particularly limited, but it is preferable to use a humectant having a lower evaporation rate than water. Examples of such humectants include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, butylene glycol, pentamethylene glycol, hexylene glycol, which have high wettability (hygroscopicity). Examples thereof include alkylene glycols such as octylene glycol, polyalkylene glycols such as polyethylene glycol and polypropylene glycol, glycerin, and amines such as triethanolamine and diethylethanolamine.

In order to sufficiently prevent clogging, it is preferable to use a humectant having a vapor pressure at a temperature of 25 ° C. of 0.1 mmHg or less, more preferably 0.01 mmHg or less. Examples of such humectants include diethylene glycol, triethylene glycol, dipropylene glycol, pentamethylene glycol, octylene glycol, polyethylene glycol, polypropylene glycol, glycerin, triethanolamine, and the like.

One type of humectant may be used alone, or two or more types may be used in combination when they are completely mixed to form one phase. The content of the humectant in the recording liquid for image display is preferably an amount capable of controlling the evaporation of the recording liquid for image display, and is preferably from 10% by weight to 90% by weight of the recording liquid for image display, more preferably about 30% by weight.
８０80% by weight, more preferably about 50-75% by weight. If the amount of the humectant is less than 10% by weight, a sufficient moisturizing effect cannot be exhibited, which is not preferable. Also, 9
Exceeding 0% by weight is not preferred because the solubility of the dye is reduced or the viscosity is increased to make ejection difficult.

The coloring agent contained as an essential component in the recording liquid for image display of the present invention includes various dyes, pigments, and colored polymers.
Wax or the like can be used. Among these, it is preferable to use a water-soluble dye. The water-soluble dye may be any of an acid dye, a direct dye, a basic dye, a reactive dye and the like, but an acid dye and a direct dye are preferred.

Examples of these dyes include C.I. I. Direct Black-2, -4, -9, -11, -17,-
19, -22, -32, -80, -151, -154,
-168, -171 and -194, C.I. I. Direct Blue-1, -2, -6, -8, -22, -34,-
70, -71, -76, -78, -86, -112,-
142, -165, -199, -200, -201,-
202, -203, -207, -218, -236 and -287, C.I. I. Direct Red-1, -2,-
4, -8, -9, -11, -13, -15, -20,-
28, -31, -33, -37, -39, -51, -5
9, -62, -63, -73, -75, -80, -8
1, -83, -87, -90, -94, -95, -9
9, -101, -110 and -189, C.I. I. Direct Yellow-1, -2, -4, -8, -11, -1
2, -26, -27, -28, -33, -34, -4
1, -44, -48, -58, -86, -87, -8
8, -135, -142 and -144, C.I. I. Food black-1 and -2, C.I. I. Acid Black-1, -2, -7, -16, -24, -26, -28,
-31, -48, -52, -63, -107, -11
2, -118, -119, -121, -156, -17
2, -194 and -208, C.I. I. Acid Blue-1, -7, -9, -15, -22, -23, -27,
-29, -40, -43, -55, -59, -62,-
78, -80, -81, -83, -90, -102,-
104, -111, -185, -249 and -25
4, C.I. I. Acid Red-1, -4, -8, -1
3, -14, -15, -18, -21, -26, -3
5, -37, -110, -144. -180, -249
And -257, and C.I. I. Acid Yellow-
1, -3, -4, -7, -11, -12, -13, -1
4, -18, -19, -23, -25, -34, -3
8, -41, -42, -44, -53, -55, -6
1, -71, -76, -78, -79 and -122.

These dyes can be used alone,
Two or more kinds may be mixed, or a custom color such as red, blue, and green may be used in addition to the four primary colors of cyan, magenta, yellow, and black.

Pigments can be used as the colorant of the present invention, for example, carbon black, brilliant carmine BS, lake carmine FB, brilliant fast scarlet, disazo yellow, permanent red R, fast yellow 10G, phthalocyanine blue, blue Lakes, yellow lakes, rhodamine lakes and the like can be used.

The content of the colorant in the recording liquid for image display is determined depending on the type of the colorant, the type of the solvent, and the characteristics required for the recording liquid for image display. In order to exhibit the function, the content is generally 0.1 to 20% by weight, more preferably 1 to 10% by weight, based on the recording liquid.

As the water which is an essential component of the recording liquid for image display of the present invention, distilled water, ion-exchanged water, pure water and the like can be used.

The recording liquid of the present invention may further contain other additives in addition to these essential components. For example, a low molecular surfactant may be added to further stabilize the dissolution or dispersion state of the dye or pigment. The surfactant may be any of nonionic, anionic, cationic and amphoteric surfactants. Examples of nonionic surfactants include polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester,
Polyoxyethylene sorbitan fatty acid esters, fatty acid alkylolamides and the like can be used.

Examples of the anionic surfactant include alkyl benzene sulfonate, alkyl phenyl sulfonate,
Alkyl naphthalene sulfonate, higher fatty acid salt, higher fatty acid ester sulfate, higher fatty acid ester sulfonate, higher alcohol ether sulfate, sulfonate, higher alkyl sulfosuccinate and the like may be used. it can.

Examples of the cationic surfactant include the first to third cationic surfactants.
As an amphoteric surfactant such as a grade amine salt or a quaternary ammonium salt, betaine, sulfobetaine, sulfate betaine, or the like can be used.

The addition amount of these surfactants is preferably twice or less, more preferably equal to or less than the addition amount of the silanol group-modified polyvinyl alcohol so as not to hinder the effect of the gelling agent. .

The recording liquid for image display of the present invention further includes:
As a solubilizer, urea, acetamide, etc. may be contained, and as a pH adjuster, acids such as hydrochloric acid, sulfuric acid, nitric acid, acetic acid, citric acid, bases such as sodium hydroxide, potassium hydroxide, ammonia, and phosphorus Various buffers such as acid salts, oxalates and amine salts may be contained. Further, as a physical property modifier, polyethyleneimine, polyamines, polyvinylpyrrolidone, polyethylene glycol, cellulose derivatives, etc., may include cyclodextrin, macrocyclic amines, crown ethers and the like as inclusion compounds, and further if necessary. In addition, a fungicide may be contained.

The production of the recording liquid for image display of the present invention can be carried out by the following procedure, but is not limited thereto. That is, water, a colorant and a humectant are dispersed in a ball mill, and it is confirmed by microscopic observation that the colorant particles are in a monodispersed or completely dissolved state, and thereafter, the silanol group-modified polyvinyl alcohol and other if necessary. Add additives such as gelling agent and dispersant,
Dissolve completely. At this time, it may be heated to the melting temperature of the gelling agent, if necessary. Next, this dispersion is heated, if necessary, and filtered in a solution state using, for example, a membrane filter having a pore diameter of 10 μm to remove dust and coarse particles to obtain a recording liquid for image display.

For printing the recording liquid of the present invention on recording paper, an ink jet printer that performs printing by discharging ink from nozzles can be used, but is not limited thereto. In addition, as an inkjet discharging method,
Any of a thermal inkjet type (bubble jet type) and a piezo type may be used, but a thermal inkjet type is preferable because the ink is heated at the time of ejection and the ink can be ejected smoothly. When the recording liquid is a solid at room temperature, it is also possible to use a melt-type ink jet type in which the ink is heated once and discharged in a dissolved state.

[0048]

The recording liquid for image display of the present invention contains a polyvinyl alcohol modified with a silanol group, and therefore gels on the paper, and further the silanol group-modified portion reacts with the paper to prevent the recording liquid from penetrating into the paper. be able to. Therefore, no bleeding or set-off occurs in the image formed on the recording paper. Also, by using a humectant having a constant vapor pressure, the generation of deposits due to the evaporation of the recording liquid in the nozzles is eliminated, so that there is no clogging and the reliability is high. Further, since a special system for solidifying the ink and a nozzle cleaning system are not required, the size of the apparatus is not increased, and the system is simple and the speed can be increased.

[0049]

The present invention will be described below in more detail with reference to examples. However, the present invention is not limited by these examples. The “parts” used in the examples are “parts by weight” unless otherwise specified.

(Example 1) Water 30 parts Diethylene glycol 70 parts Cyan dye (CI Acid Blue-9: manufactured by Mitsubishi Chemical Corporation) 2 parts Silanol group-modified polyvinyl alcohol (R-2105: manufactured by Kuraray Co., Ltd.) 3 parts The above composition was heated to 90 ° C. in an Erlenmeyer flask, and heated to 30 ° C. using a magnetic stirrer equipped with a heating device.
The mixture was stirred for 1 minute and then filtered under pressure at a heating temperature of 90 ° C. using a membrane filter having a pore size of 10 μm to obtain a recording liquid 1 for image display.

(Example 2) Water 70 parts Glycerin 30 parts Cyan dye (CI Acid Blue-9: manufactured by Mitsubishi Chemical Corporation) 2 parts Silanol group-modified polyvinyl alcohol (R-2105: manufactured by Kuraray Co., Ltd.) 3 parts Using the above composition, in the same manner as in Example 1,
An image display recording liquid 2 was obtained.

(Comparative Example 1) 78 parts of water 5 parts of diethylene glycol monobutyl ether 5 parts of glycerin 5 parts of cyan dye (CI acid blue-9: manufactured by Mitsubishi Chemical Corporation) 2 parts The above composition was heated to 40 ° C. in a water bath. In this state, the mixture was stirred using a magnetic stirrer and filtered under pressure using a membrane filter having a pore size of 0.25 μm to obtain a recording liquid 3 for image display.

(Comparative Example 2) Water 30 parts Glycerin 70 parts Cyan dye (CI Acid Blue-9: manufactured by Mitsubishi Chemical Corporation) 2 parts Polyvinyl alcohol (500 (completely saponified): manufactured by Wako Pure Chemical Industries) 3 Part Using the above composition, a recording liquid 4 for image display was obtained in the same manner as in Example 1.

(Example 3) Water 30 parts Ethylene glycol 70 parts Cyan dye (CI Acid Blue-9: manufactured by Mitsubishi Chemical Corporation) 2 parts Silanol group-modified polyvinyl alcohol (R-1130: manufactured by Kuraray Co., Ltd.) 3 Part Using the above composition, a recording liquid 5 for image display was obtained in the same manner as in Example 1.

Comparative Example 3 Polyvinyl alcohol (500) was used instead of the silanol group-modified polyvinyl alcohol.
(Completely saponified type: manufactured by Wako Pure Chemical Industries, Ltd.) except that the image display recording liquid 6 was used in the same manner as in Example 1.
I got

Comparative Example 4 Polyvinyl alcohol (500) was used instead of the silanol group-modified polyvinyl alcohol.
(Completely saponified type) manufactured by Wako Pure Chemical Industries, Ltd., except that the image display recording liquid 7 was obtained in the same manner as in Example 2.

(Test Examples) The recording liquids prepared in Examples 1 to 3 and Comparative Examples 1 to 4 were evaluated in the following A to D. A Evaporation test Each recording solution was sealed in a capillary tube having a capacity of 0.5 μl and a length of 30 mm, both ends were opened, and left for 1 week in an environment of a temperature of 25 ° C. and a humidity of 65%, and recording immediately after and 1 week after the sealing. The change of each recording solution of the solution was confirmed by microscopic observation.

B Bleeding Test Using the recording droplet dropping device 1 shown in FIG.
(Plain paper L: Fuji Xerox Co., Ltd.)
Was dropped from the syringe 3 and the change over time in the dot diameter 8 of each recording liquid formed on the paper 7 was measured. Fig. 4 shows the results.
Shown in In FIG. 2, 5 indicates a gel, and 6 indicates a humectant that has permeated from the gel. The ratio d ₄₈ / d ₀ between the diameter of the dropped droplet and the diameter of the dot after 48 hours was calculated.

C: Show-through, curl test Each recording solution was applied to paper (plain paper L: Fuji Xerox Co., Ltd.) using a wire bar No. 10 (coating thickness: 25.4 μm). A 5 cm square patch was cut out from this sample as a measurement sample, and after 3 hours, show-through of the ink was visually confirmed. As shown in FIG. 3, the curl of the paper is set by placing the measurement sample 9 on the horizontal reference table 10 and
The flexural height h ₁ (mm) 11 at the right end of the sample and the flexural height h ₂ (mm) 12 at the left end were measured, and the average value h (m) was obtained.
m) was determined, and this was taken as the degree of curl. In addition, 4
After 8 hours, the state of the paper was visually checked.

D Actual Machine Test A commercially available ink jet printer was filled with each recording liquid in a modified printing apparatus capable of heating printing, and a printing test of each recording liquid on an ink jet paper (JP-C100A: manufactured by Sanwa Supply Co., Ltd.) was performed. . The reflection optical density (ID) of the solid image of the sample printed in this manner was measured using X-Rite 310 (manufactured by X-Rite). Furthermore, the head was filled with each recording liquid and left for one month without a cap in an environment of 40 ° C.
A printing test was performed again in that state. The results of these tests are shown in Table 1 below.

[0061]

[Table 1]

The recording liquids of Examples 1 and 2 were Comparative Examples 1, 2, 3, 4
In comparison with the recording liquid of No. 1, the liquid did not easily evaporate and gave a high image density. Further, in Example 3 using the humectant having a low vapor pressure, compared to Examples 1 and 2, maintenance was unnecessary, and a higher quality image was provided. Further, when the cross-sectional views of the images of Examples 1, 2, and 3 were observed with an optical microscope, the recording liquid was solidified on the paper surface and did not permeate into the inside. This can be said to be the result of the reaction between the silica fine particles present on the surface of the inkjet paper and the silanol groups of the silanol group-modified polyvinyl alcohol, which effectively controlled the penetration of the recording liquid. In Example 1,
Since the permeation of the recording liquids 2 and 3 is controlled by the silanol group-modified polyvinyl alcohol on the paper surface, no curling or paper wrinkling caused by excessive water permeating into the paper was generated.

[0063]

The recording liquid for image display of the present invention comprises a recording paper,
In particular, since it hardens on plain paper, reacts with components in the recording paper, and does not penetrate into the recording paper, a high-quality image without bleeding can be provided. Furthermore, the use of a humectant with a low vapor pressure eliminates the need for a special system for solidifying the ink and a nozzle cleaning system, so that it is possible to provide an inkjet printer that is compact, has a simple system, and can be operated at high speed. Become.

[Brief description of the drawings]

FIG. 1 is a diagram showing a recording liquid dropping device used for a bleeding test.

FIG. 2 is a diagram illustrating a measurement model of a dot diameter in a bleeding test.

FIG. 3 is a diagram showing a measurement model in a curl test.

FIG. 4 is a graph showing a change in dot diameter over time in a blur test.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Heating apparatus 2 Recording liquid 3 Syringe 4 Droplet 5 Gel 6 Moisturizer oozing from gel 7 Recording paper 8 Dot diameter 9 Measurement sample 10 Horizontal reference board 11 Right deflection height h ₁ 12 Left deflection height h ₂

Claims (3)

[Claims] 1. A recording liquid for image display, comprising: water, a colorant, a humectant, and a polyvinyl alcohol modified with a silanol group. 2. The recording liquid for image display according to claim 1,
An image forming method, wherein recording is performed using an ink jet system. 3. The ink jet system is a thermal type ink jet system.
The image forming method as described in the above.