JP2005219372A - Inkjet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording method which hardly causes the strike-through and feathering of ordinary paper, which can prevent color bleeding in long storage, and which can enhance image reproducibility. <P>SOLUTION: In this inkjet recording method, a recording medium fluid, which contains at least a coloring agent, polysaccharides with a molecule including a carboxyl group, water and a nonaqueous solvent with a boiling point of 150°C or higher, is printed on the ordinary paper, containing a water-soluble polyvalent metal salt, by using an inkjet system. In the recording medium fluid, a mass ratio between the water and the nonaqueous solvent with the boiling point of 150°C or higher is in the range of 50:50-5:95. The amount of the water-soluble polyvalent metal salt, which is contained in the ordinary paper, is set to be in the range of 0.1-5.0 g/m<SP>2</SP>. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ink jet recording method excellent in image reproducibility in which show-through and feathering on plain paper hardly occur and color bleeding during long-term storage is prevented.

  In recent years, the ink jet recording system can create images easily and inexpensively, and thus has been applied to various printing fields such as photographs, various printing, marking, and special printing such as color filters. In particular, ink jet recording devices that emit and control fine dots, ink with improved color reproduction gamut, durability, and emission suitability, ink absorbency, coloring material color development, surface gloss, etc. are dramatically improved. It is also possible to obtain image quality comparable to silver halide photography using special paper.

  However, in an inkjet image recording system that requires dedicated paper, there are problems in that the recording media that can be used are limited and the cost of the recording media is increased.

  On the other hand, in the office, there is an increasing need for a system capable of performing full color printing at high speed without being restricted by a recording medium (for example, plain paper, coated paper, art paper, plain paper double-sided printing, etc.).

  As for the composition of inkjet ink, it can print at high speed, has good character reproducibility on plain paper, and shows through when printing (a phenomenon in which the printed ink passes through the recording medium and the image appears on the back), feathering Various studies have been made from the viewpoints of no occurrence of image bleeding, rapid penetration into paper, and quick drying.

  As one of the methods, a solvent-based ink that can perform printing at high speed has been studied. That is, by using an oil-based ink (solvent ink jet ink) that contains a volatile solvent and has improved drying properties, even when printing on plain paper, the penetration into the recording medium is fast and the drying time is short. High-speed printing is possible without curling or the like. However, solvent-based inks have a strong penetrability into plain paper media, and therefore have poor character reproducibility and show-through in recording media, which is a major obstacle especially when printing on both sides of plain paper. It was.

  On the other hand, as a method for fixing a pigment to plain paper, a method using an ink containing a water-soluble dye having a sulfone group or a carboxyl group salt in the molecule is disclosed on plain paper provided with a water-soluble metal salt. (For example, refer to Patent Document 1). However, if the content of the water-soluble metal salt in plain paper is increased in order to improve the fixability, the dye diffuses into the unprinted area where the ink has not landed, or when stored for a long period of time. I have a problem that causes color bleeding.

  Also, after ejecting a liquid containing a polyvalent metal salt onto the recording medium, the dye penetrates the recording medium and immediately after it disappears from the surface of the recording medium, a dye having an acidic group is added to the area to which the liquid is applied. There has been proposed a method for suppressing color bleeding on a non-image portion by printing the contained ink (see, for example, Patent Document 2). However, the proposed method further requires a liquid discharge recording head containing a polyvalent metal in the ink jet recording apparatus, leading to an increase in cost and maintenance cost of the ink jet recording apparatus, and is practical. Is hard to say.

In addition, for the purpose of assisting the dye fixing property of ink that lands on the recording medium, a method for improving fixing property and show-through is proposed by including a water-soluble alginic acid derivative, borneols, celluloses, and polysaccharides in the ink. (See, for example, Patent Documents 3 and 4). However, the fixing ability of the dye and the polysaccharide such as alginic acid compete for the polyvalent metal salt in the recording medium, and the effect is not sufficient, and further development of an improved technique is demanded.
JP-A-55-53591 JP 63-299970 A JP 59-98175 A JP-A-5-295310

  SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide an ink jet recording method excellent in image reproducibility, which prevents back-through and feathering on plain paper and prevents color bleeding during long-term storage. I will provide a.

  The above object of the present invention is achieved by the following configurations.

(Claim 1)
Inkjet printing on a plain paper containing a water-soluble polyvalent metal salt with a recording medium solution containing at least a colorant, a polysaccharide having a carboxyl group in the molecule, water and a non-aqueous solvent having a boiling point of 150 ° C. or higher by an inkjet method. A recording method, wherein the mass ratio of the water and the non-aqueous solvent having a boiling point of 150 ° C. or higher in the recording medium liquid is 50:50 to 5:95, and the plain paper contains An ink jet recording method, wherein the amount of the valent metal salt is 0.1 g / m ² or more and 5.0 g / m ² or less.

(Claim 2)
The ratio (Vs / Vw) of the penetration rate Vs of the non-aqueous solvent having a boiling point of 150 ° C. or more into the plain paper and the penetration rate Vw of water is 11> Vs / Vw> 6, The inkjet recording method according to claim 1.

(Claim 3)
The inkjet recording method according to claim 1, wherein the recording medium liquid does not contain a water-soluble surfactant.

(Claim 4)
The inkjet recording method according to claim 1, wherein the polysaccharide has a boiling point of 5 g / L or less in a non-aqueous solvent having a boiling point of 150 ° C. or higher.

  According to the present invention, it is possible to provide an ink-jet recording method excellent in image reproducibility in which show-through and feathering on plain paper hardly occur and color bleeding during long-term storage is prevented.

  Hereinafter, the best mode for carrying out the present invention will be described in detail.

As a result of intensive investigations in view of the above problems, the present inventors have found that plain paper containing a water-soluble polyvalent metal salt has at least a colorant, a polysaccharide having a carboxyl group in the molecule, water, and a boiling point of 150 ° C. An ink jet recording method for printing a recording medium liquid containing the above non-aqueous solvent by an ink jet method, wherein a mass ratio of the water and the non-aqueous solvent having a boiling point of 150 ° C. or higher in the recording medium liquid is 50:50 to 5:95, and the amount of the water-soluble polyvalent metal salt contained in the plain paper is 0.1 g / m ² or more and 5.0 g / m ² or less. It has been found that an ink jet recording method excellent in image reproducibility can be realized in which omission and feathering hardly occur and color bleeding during long-term storage is prevented.

  That is, a recording medium liquid containing a polysaccharide in a dissolved state (hereinafter also referred to as ink) is contained in the recording medium liquid by emitting and printing on plain paper containing polyvalent metal ions at a high density. The polysaccharide reacts with the polyvalent metal ions contained in the plain paper at an extremely high speed to gel, and as a result, the migration of the pigment is prevented.

  In particular, the recording medium liquid contains a high concentration of a non-aqueous solvent having a boiling point of 150 ° C. or higher. Specifically, the mass ratio of water to a non-aqueous solvent having a boiling point of 150 ° C. or higher is 50:50 to 5:95. When the form of the recording medium liquid included in the range is used, the non-aqueous solvent component penetrates faster than water on plain paper, and exhibits the effect of concealing the polyvalent metal salt existing site in the non-printing part. As a result, the diffusion of the color material and polysaccharide contained in the recording medium liquid is suppressed, and the bleeding resistance when the printed image is stored for a long time is also improved. In particular, by using a polyvalent metal salt that is difficult to dissolve in a non-aqueous solvent component, a high concentration of polyvalent metal ions is contained in a small amount of water in the recording medium liquid printed and landed on plain paper. By dissolving and binding with polysaccharides present in the same aqueous phase efficiently and at high speed, it can be gelled at a very high speed.

  Details of the present invention will be described below.

  First, plain paper, which is a recording material used in the ink jet recording method of the present invention, will be described.

The plain paper according to the present invention is characterized in that the amount of water-soluble polyvalent metal salt is 0.1 g / m ² or more and 5.0 g / m ² or less.

  In general, as an inkjet image recording medium, for example, plain paper, coated paper, cast coated paper, glossy paper, glossy film, OHP film, inkjet special paper, etc. are widely used, but in the inkjet recording method of the present invention, One characteristic is that the paper is a plain paper represented by office paper such as copy paper. In the present invention, by combining with the recording medium liquid according to the present invention described later, the ink characteristics are sufficiently exerted, and through-through and feathering are suppressed without requiring special paper, and color during long-term storage It is possible to prevent bleeding and form an image with good image reproducibility.

  The plain paper referred to in the present invention is preferably 80 to 200 μm uncoated paper belonging to a part of non-coated paper, special printing paper and information paper.

  The construction of the plain paper according to the present invention is made by a conventional method using mainly chemical pulps represented by LBKP and NBKP, sizing agents and fillers, and using other paper making aids as necessary. As the pulp material used for the plain paper according to the present invention, mechanical pulp and recycled paper recycled pulp may be used in combination, and there is no problem even if these are used as the main material.

  Examples of the sizing agent internally added to the plain paper according to the present invention include rosin size, AKD, Alnicel succinic anhydride, petroleum resin-based size, epichlorohydrin, cationic starch, and acrylamide.

  Examples of the filler internally added to the plain paper according to the present invention include finely divided silicic acid, aluminum silicate, diatomaceous earth, kaolin, kaolinite, halloysite, nacrite, dickite, pyrophyllite, sericite, titanium dioxide, bentonite and the like. Can be mentioned.

In the present invention, the above-mentioned plain paper contains a water-soluble polyvalent metal salt amount of 0.1 g / m ² or more and 5.0 g / m ² or less What is a water-soluble polyvalent metal salt that can be used in the present invention? This is a polyvalent metal salt that has the property of releasing and diffusing from plain paper into the aqueous phase when it is immersed in water, and there is no particular limitation as long as it has such properties. , Magnesium, zinc, iron, strontium, barium, nickel, copper, scandium, gallium, indium, titanium, zirconium, tin, lead, and other metal salts, sulfate, nitrate, formate, succinate, malonate, chloro It is added as a salt such as acetate or p-toluenesulfonate. Further, a water-soluble inorganic polymer such as polyaluminum chloride may be used as a salt of a water-soluble polyvalent metal ion. The water solubility is preferably at least 0.1% by mass, more preferably 1% by mass. Among these, a water-soluble salt composed of aluminum, calcium, aluminum, magnesium, and zinc is preferable because its metal ion is colorless. Particularly preferred are aluminum chloride, aluminum sulfate, aluminum nitrate, aluminum acetate, calcium chloride, calcium sulfate, calcium nitrate, calcium acetate, magnesium chloride, magnesium sulfate, magnesium nitrate, magnesium acetate, zinc chloride, zinc sulfate, zinc nitrate, Zinc acetate.

  Further, in particular, when providing the water-soluble polyvalent metal salt in the plain paper according to the present invention, the internal addition method in which the water-soluble polyvalent metal salt is kneaded in advance before the paper making step, the surface of the plain paper in the middle of drying Examples include a size press method for imparting a water-soluble polyvalent metal salt to the surface, or an overcoat for imparting a water-soluble polyvalent metal salt to the dried plain paper surface. If it is a method, this invention is not specifically limited only to these methods.

  As a method for determining the amount of the water-soluble polyvalent metal salt in plain paper defined in the present invention, for example, it can be measured according to the following method.

Specifically, 20 cm ² of plain paper is cut out accurately, put in a petri dish, and further 20 ml of ultrapure water is added and left for 1 hour. Next, the whole amount of the aqueous solution in the petri dish was taken out with a spoid, transferred to a 50 ml volumetric flask, and further 20 ml of ultrapure water was added to the petri dish, and the plain paper was lightly stirred and washed. In addition to the flask, the total volume was adjusted to 50 ml with ultrapure water. Next, the solution diluted appropriately is analyzed using an ICP emission analyzer (manufactured by Seiko Denshi, SPS4000). The analysis wavelength is, for example, Ca: 396.847 nm, Mg: 279.553 nm, Al: 396.152 nm, the output is 1.3 kW, and measurement is performed using a calibration curve method, and the respective atomic contents are obtained. For the standard solution, a reagent for atomic absorption analysis (manufactured by Kanto Chemical Co., Inc.) is diluted with ultrapure water and used.

  Next, the recording medium liquid according to the present invention will be described.

  The recording medium liquid according to the present invention contains at least a colorant, a polysaccharide having a carboxyl group in the molecule, water, and a non-aqueous solvent having a boiling point of 150 ° C. or higher.

  First, the polysaccharide having a carboxyl group in the molecule will be described.

  The polysaccharide having a carboxyl group in the molecule that can be used in the present invention is not particularly limited, and examples thereof include generally known natural simple polysaccharides, natural complex polysaccharides, synthetic simple polysaccharides, and synthetic complex polysaccharides. For details of these polysaccharides, reference can be made to “Biochemical Dictionary (2nd edition), Tokyo Chemical Doujinshi”, “Food Industry”, Vol. 31 (1988), p.

  Typical polysaccharides include, for example, β1-4 glucan (eg, carboxymethyl cellulose, carboxyethyl cellulose, etc.), galactan (eg, agarose, agaropectin, etc.), galactomannoglycan (eg, locust bean gum, guaran, etc.) ), Xyloglucan (eg, tamarind gum, etc.), glucomannoglycan (eg, salmon mannan, wood-derived glucomannan, xanthan gum, etc.), galactoglucomannoglycan (eg, softwood-derived glycan), arabinogalactoglycan ( For example, soybean-derived glycan, microorganism-derived glycan, etc.), glucaronoglycan (eg, gellan gum, etc.), glycosaminoglycan (eg, hyaluronic acid, keratan sulfate, etc.), alginic acid, alginic acid salt, etc.

  The polysaccharide having a carboxyl group in the molecule according to the present invention preferably has a solubility in a non-aqueous solvent having a boiling point of 150 ° C. or higher, which will be described later, of 5 g / L or less, more preferably 0.1 to 2 g / L. is there. When a polysaccharide having a solubility in a non-aqueous solvent exceeding 5 g / L is used, the amount of polysaccharide distributed to the non-aqueous solvent increases. As a result, the polysaccharide diffuses in the non-aqueous solvent without being ionized for binding to the polyvalent metal salt, and the increase in viscosity and gelation due to the polysaccharide are suppressed, thereby effectively achieving the object effect of the present invention. It will be a hindrance to show.

  Next, the colorant used in the recording medium liquid according to the present invention will be described.

  As the hue of the colorant used in the present invention, yellow, magenta, cyan, black, blue, green, and red colorants are preferably used, and yellow, magenta, cyan, and black colorants are particularly preferable.

  In the present invention, a dye recording medium liquid in which the colorant is a water-soluble dye, or a pigment recording medium liquid in which the colorant is a pigment that is insoluble in the solvent constituting the recording medium liquid and forms a fine dispersion, The dispersion may be a dispersion recording medium liquid composed of a dispersion of a colored polymer.

  Examples of water-soluble dyes that can be used in the present invention include azo dyes, methine dyes, azomethine dyes, xanthene dyes, quinone dyes, phthalocyanine dyes, triphenylmethane dyes, diphenylmethane dyes, and specific compounds thereof. Examples thereof include the dyes exemplified in JP-A No. 2002-264490.

  For oil-soluble dyes that form colored fine particles together with polymers and the like and become colorants, dyes that are soluble in organic solvents that do not have a water-soluble group such as carboxylic acid and sulfonic acid and are insoluble in water, for example, A disperse dye or the like is selected. Moreover, the dye which shows oil solubility by salt-forming a water-soluble dye with a long-chain base is also contained. For example, acid dyes, direct dyes, and salt-forming dyes of reactive dyes and long chain amines are known.

  However, in the present invention, it is preferable to use a pigment as the colorant, and a pigment that does not have solubility in water and a non-aqueous solvent having a boiling point of 150 ° C. or higher is bonded with hydrogen to the solvent-based plain paper (cellulose). And the like are less likely to change depending on the colorant, and can be easily controlled.

  As the pigment that can be used in the present invention, conventionally known pigments can be used without particular limitation, and any of water-dispersible pigments, solvent-dispersible pigments, and the like can be used, for example, organic pigments such as insoluble pigments and lake pigments, An inorganic pigment such as carbon black can be preferably used.

  The insoluble pigment is not particularly limited. Dioxazine, thiazole, phthalocyanine, diketopyrrolopyrrole and the like are preferable.

  Specific pigments that can be preferably used include the following pigments.

  Examples of the magenta or red pigment include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.

  Examples of the pigment for orange or yellow include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 15: 3, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 94, C.I. I. And CI Pigment Yellow 138.

  Examples of the pigment for green or cyan include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.

In addition to the above, when red, green, blue and intermediate colors are required, the following pigments are preferably used alone or in combination. I. Pigment Red 209, 224, 177, 194;
C. I. Pigment Orange 43;
C. I. Vat Violet 3;
C. I. Pigment Violet 19, 23, 37;
C. I. Pigment Green 36, 7;
C. I. Pigment Blue 15: 6;
Etc. are used.

Examples of black pigments include C.I. I. Pigment black 1, C.I. I. Pigment black 6, C.I. I. Pigment Black 7 and the like can be mentioned. The pigment used in the present invention is preferably used after being dispersed by a dispersing machine together with a dispersant and other necessary additives according to various desired purposes. As the disperser, a conventionally known ball mill, sand mill, line mill, high-pressure homogenizer, or the like can be used.

  The average particle diameter of the pigment dispersion used in the recording medium liquid according to the present invention is preferably 10 nm to 200 nm, more preferably 10 nm to 100 nm, and still more preferably 10 nm to 50 nm. If the average particle size of the pigment dispersion exceeds 100 nm, the dispersion becomes unstable. Further, even when the average particle diameter of the pigment dispersion is less than 10 nm, the stability of the pigment dispersion tends to deteriorate, and the storage stability of the recording medium liquid tends to deteriorate.

  The particle size of the pigment dispersion can be determined by a commercially available particle size measuring device using a light scattering method, an electrophoresis method, a laser Doppler method or the like. It is also possible to obtain a particle image with a transmission electron microscope on at least 100 particles and perform statistical processing on the image using image analysis software such as Image-Pro (manufactured by Media Cybernetics). Is possible.

  Next, the non-aqueous solvent having a boiling point of 150 ° C. or higher according to the present invention will be described.

  The non-aqueous solvent having a boiling point of 150 ° C. or higher according to the present invention is not particularly limited, but is preferably a non-aqueous solvent having a boiling point of 180 ° C. or higher, more preferably a non-aqueous organic solvent having a boiling point of 180 to 350 ° C. It is. A non-aqueous solvent having a boiling point of less than 150 ° C. has a problem that the evaporation rate becomes too fast, causing poor colorant dispersion in the recording medium liquid, formation of aggregates, and accompanying clogging of the nozzles of the recording head. There is concern to cause.

  Examples of the non-aqueous solvent having a boiling point of 150 ° C. or higher according to the present invention include ethylene glycol monoalkyl ethers (boiling point: 150 to 250 ° C., for example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, etc. ), Diethylene glycol monoalkyl ethers (boiling point: 150-250 ° C., for example, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, etc.), triethylene glycol monoalkyl ethers (boiling point: 249-300 ° C., for example, tri Ethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, etc.), propylene Glycol monoalkyl ethers (boiling point: 190 to 250 ° C., for example, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, etc.), dipropylene recall monoalkyl ethers (boiling point: 189 to 280 ° C., for example, , Dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monobutyl ether, etc.), tripropylene recall monoalkyl ethers (boiling point: 243 to 300 ° C., for example, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl) Ethers, tripropylene glycol monobutyl ether, etc.), alkyl ether acetates of alkylene glycols Boiling point: 150 to 300 ° C.), can be exemplified pyrrolidone, and the like, but is not limited only to these in the present invention. In addition, the non-aqueous solvent having a boiling point of 150 ° C. or higher according to the present invention may be used singly or in combination of two or more.

  In the recording medium liquid according to the present invention, as the content of the non-aqueous solvent having a boiling point of 150 ° C. or higher according to the present invention described above, the mass ratio of water to the non-aqueous solvent having a boiling point of 150 ° C. or higher is 50:50. It is one of the characteristics that it is set to ˜5: 95, preferably the mass ratio of water to a non-aqueous solvent having a boiling point of 150 ° C. or higher is 40:60 to 5:95, more preferably water and the boiling point. The mass ratio with the non-aqueous solvent at 150 ° C. or higher is 40:60 to 10:90. By setting the content of the non-aqueous solvent at 150 ° C. or higher in the above-described range, it is possible to more effectively prevent back-through and feathering when printed on plain paper, and further prevent color bleeding during long-term storage. It can be improved further.

  In the present invention, when the penetration rate of a non-aqueous solvent having a boiling point of 150 ° C. or higher into plain paper is Vs and the penetration rate of water is Vw, the ratio (Vs / Vw) is 11> Vs. It is preferable that / Vw> 6, and more preferably 11> Vs / Vw> 8. That is, when a non-aqueous solvent having a permeation rate into plain paper of more than 6 times that of water and a boiling point of less than 11 times of 150 ° C. or higher is selected, when the recording medium liquid lands on the plain paper, The aqueous solvent penetrates into plain paper at a faster penetration rate than water, and this non-aqueous solvent effectively masks the non-printing portion polyvalent metal salt present in a large amount in plain paper, thereby providing a colorant. In addition, the diffusion (bleeding) of the polysaccharide to the non-printing portion can be prevented.

  The permeation rate of each solvent specified in the present invention can be determined according to the following method.

  In the present invention, the Bristow method shown below can be used as a method for measuring the permeation rate of the non-aqueous solvent and water.

  The Bristow method referred to in the present invention is a method for measuring the liquid absorption behavior of paper and paperboard in a short time. TAPPI paper pulp test method no. Measured according to 51-87 paper or paperboard liquid absorbency test method (Bristow method). In the measurement, it is possible to color a non-aqueous solvent or pure water used for convenience of measurement. For coloring, see J.H. TAPPI Paper Pulp Test Method No. In addition to malachite green described in the 51-87 Bristow method, water-soluble dyes such as Direct Blue 199 and oil-soluble dyes such as Oil Black 1 can be preferably used in accordance with the hydrophobicity and hydrophilicity of the solvent. As a method for measuring the amount of solvent transfer, it can be obtained by measuring the stained area using a microdensitometer.

From the measurement results obtained by the above method and the physical property values of each solvent, the vertical axis is the transition amount and the horizontal axis is (surface tension × wetting time / viscosity) ^1/2 . Linear approximation was performed, and the obtained slope was defined as the Bristow absorption rate Vs of each solvent.

  The measurement principle of the permeation rate of each solvent to plain paper by the Bristow method is shown below.

  Each solvent was weighed with a 40 μl microsyringe and p (nozzle gap) = 1 mm, w (nozzle width) = 1.75 cm from the nozzle opening, υ (paper moving speed) = 0.5-50 mm / Permeate and transfer on plain paper rotating at a speed of sec. When the transition length at this time is L (cm), the solvent permeation amount V is obtained by the following formula 1.

The transition time t at that time is t = p / υ = 1.0 / υ (sec)
It is. The following Lucas Washburn relational expression (formula 2) is known as a theoretical formula when the penetration of the solvent proceeds in the paper capillary by the penetration of the solvent.

In the formula, γ: paper capillary radius γ, L: surface tension of solvent, θ: contact angle of solvent with solvent, η: viscosity of solvent. Therefore, it is expected that V and √t are proportional. In practice, ink transfer occurs instantaneously due to the roughness of the paper surface. If this transition amount is V ₀ , the following equation 3 is obtained.

The permeation rate is determined as d (V−V ₀ ) / d√t (ml / m ² · sec ^1/2 ).

  In addition to the above description, the recording medium liquid according to the present invention may be used in accordance with the purpose of improving the emission stability, print head and ink cartridge compatibility, storage stability, image storage stability, and other various performances as necessary. Various known additives such as viscosity modifiers, specific resistance modifiers, film forming agents, ultraviolet absorbers, antioxidants, anti-fading agents, anti-fouling agents, rust inhibitors, etc. are appropriately selected and used. For example, oil droplet fine particles such as liquid paraffin, dioctyl phthalate, tricresyl phosphate, silicone oil, ultraviolet absorbers described in JP-A Nos. 57-74193, 57-87988, and 62-261476, JP-A-57-74192, JP-A-57-87989, JP-A-60-72785, JP-A-61-146591, JP-A-1-95091 and JP-A-3-13376 Anti-fading agents, fluorescent whitening agents described in JP-A Nos. 59-42993, 59-52689, 62-280069, 61-242871, and JP-A-4-219266 Can be mentioned.

  However, it is preferable not to contain a surfactant from the viewpoint of more effectively exerting the object effect of the present invention. When the recording medium liquid according to the present invention contains a surfactant, the penetration of the water component in the ink into plain paper is promoted by the effect of the surfactant diffused in water, and the ink according to the present invention contained in the ink. This hinders the effective hiding effect of the water-soluble polyvalent metal salt by the non-aqueous solvent.

  When an image is formed by ejecting the recording medium liquid according to the present invention on the plain paper according to the present invention, the ink jet head to be used may be an on-demand system or a continuous system. In addition, as a discharge method, an electro-mechanical conversion method (for example, a single cavity type, a double cavity type, a bender type, a piston type, a shear mode type, a shared wall type, etc.), an electro-thermal conversion method (for example, thermal ink jet) Any ejection method such as a mold, a bubble jet (R) mold, or the like may be used.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. The “%” below represents “% by mass” unless otherwise specified.

<< Preparation of recording materials 1-8 >>
On one side of the first class plain paper manufactured by Konica Minolta Business Technology, a 5% aqueous solution of calcium chloride, which is a polyvalent metal salt heated to 80 ° C., is applied in the amount (ml / m ² ) shown in Table 1. In this way, coating was performed by a bar coating method, and drying was immediately performed using a hot air dryer. Next, in the same manner, the surface opposite to the coated surface was coated and dried, and the recording materials 1 to 8 having the polyvalent metal salt application amount (total amount on both sides) shown in Table 1 were obtained. Was made.

  The quantification of the polyvalent metal salt in each recording material was determined by measurement according to the method described above.

<< Preparation of recording medium liquids 1 to 13 >>
Recording medium liquids 1 to 13 were prepared according to the following method. In addition, the following sodium alginate (polysaccharide having a carboxyl group) used Kimika Algin ULV-L3 manufactured by Kimika Co., Ltd., and the alginic acid used ULV having the same molecular weight as ULV-L3 manufactured by Kimika Co., Ltd. Further, Delta Gel S200 manufactured by Nippon Biocon Co., Ltd. was used as carrageenan (polysaccharide having no carboxyl group). As an aqueous solution of a water-soluble dye, Nippon Kayaku Co., Ltd. JPD Cyan KN-11 (hereinafter referred to as KN-11) was used. In addition, preparation of each recording medium liquid prepared and stirred with the following prescription, and filtered with the 0.8 micrometer membrane filter. After filtration, each recording medium liquid was filled in an ink liquid cartridge of an ink jet printer MC 2000 manufactured by Seiko Epson Corporation.

[Preparation of recording medium liquid 1]
Water-soluble dye: KN-11 aqueous solution 15%
15% ultrapure water
Dipropylene glycol monomethyl ether (boiling point: 189 ° C) 69%
Polysaccharide: Kimika Argin ULV-L3 1%
[Preparation of recording medium liquid 2]
Water-soluble dye: KN-11 aqueous solution 15%
15% ultrapure water
Dipropylene glycol monomethyl ether (boiling point: 189 ° C) 70%
[Preparation of recording medium liquid 3]
Water-soluble dye: KN-11 aqueous solution 15%
15% ultrapure water
Dipropylene glycol monomethyl ether (boiling point: 189 ° C) 69%
Polysaccharide: Delta Gel S200 1%
[Preparation of recording medium liquid 4]
Water-soluble dye: KN-11 aqueous solution 15%
15% ultrapure water
Ethylene glycol (boiling point: 189 ° C) 69%
Polysaccharide: Kimika Argin ULV-L3 1%
[Preparation of recording medium liquid 5]
Water-soluble dye: KN-11 aqueous solution 15%
60% ultrapure water
Glycerin (boiling point: 290 ° C) 24%
Polysaccharide: Kimika Argin ULV-L3 1%
[Preparation of recording medium liquid 6]
Water-soluble dye: KN-11 aqueous solution 15%
15% ultrapure water
Tripropylene glycol (boiling point: 268 ° C) 69%
Polysaccharide: Kimika Argin ULV-L3 1%
[Preparation of recording medium liquid 7]
Water-soluble dye: KN-11 aqueous solution 15%
15% ultrapure water
Tripropylene glycol monomethyl ether (boiling point: 243 ° C) 69%
Polysaccharide: Kimika Argin ULV-L3 1%
[Preparation of recording medium liquid 8]
Water-soluble dye: KN-11 aqueous solution 15%
15% ultrapure water
Dipropylene glycol monobutyl ether (boiling point: 231 ° C) 69%
Polysaccharide: Kimika Argin ULV-L3 1%
[Preparation of recording medium liquid 9]
Water-soluble dye: KN-11 aqueous solution 15%
15% ultrapure water
Dipropylene glycol monomethyl ether (boiling point: 189 ° C) 68%
Polysaccharide: Kimika Argin ULV-L3 1%
Surfactant: Surfynol 465 1%
[Preparation of recording medium liquid 10]
A recording medium liquid 10 was prepared in the same manner as in the preparation of the recording medium liquid 2 except that instead of ULV-L3, which is sodium alginate, Kimika Argin ULV-L3G manufactured by Kimika Co., Ltd. was used.

[Preparation of recording medium liquid 11]
In the preparation of the recording medium liquid 2, recording was performed in the same manner except that Bistop D-1382, an LM pectin manufactured by Saneigen FFI Co., Ltd., was used instead of ULV-L3, which is sodium alginate. Medium solution 11 was prepared.

[Preparation of recording medium liquid 12]
Recording medium liquid 2 was prepared in the same manner as in the preparation of recording medium liquid 2, except that Bistop D-402, a pectin made by Saneigen FFI Co., Ltd., was used instead of ULV-L3, which is sodium alginate. Liquid 12 was prepared.

[Preparation of recording medium liquid 13]
Water-soluble dye: KN-11 aqueous solution 15%
15% ultrapure water
Dipropylene glycol monomethyl ether (boiling point: 189 ° C) 66%
Polysaccharide: Kimika Algin ULV (manufactured by Kimika Co., Ltd., alginate derivative) 1%
Triethanolamine 2%
Surfactant: Surfynol 465 1%
Example 1
<Inkjet image recording>
The recording materials 1 to 7 and the recording medium liquids 1 to 4 produced according to the method described above were combined with each other as shown in Table 2, and each solid image of 10 cm × 10 cm square using an ink jet printer MC 2000 manufactured by Seiko Epson Corporation A line drawing having a width of 1 mm was output, and images 1 to 11 were created.

<Evaluation of formed image>
The following evaluations were performed on each of the created images.

[Evaluation of through-hole resistance]
For each of the solid images thus formed, the respective densities of the image portion and the non-image portion on the front and back surfaces of the recording material were measured, and the strike-through density ratio was measured according to the following formula, and this was used as a measure for the strike-through resistance. The smaller the value, the better the show-through resistance.

Back-through density ratio = (Back surface image density−Recording material density of back surface unprinted area) / (Surface image density−Recording material density of front surface unprinted area) × 100 (%)
The back-through density ratio is preferably 15% or less, more preferably 10% or less, and most preferably 7% or less.

[Evaluation of bleeding resistance after storage]
About the line drawing of each image created above, the line width immediately after printing and the line width after standing for 3 days in an environment of 60 ° C. and 80% relative humidity after printing are respectively measured using a KEYENCE microdensitometer. And the line width change rate of each sample was determined according to the following formula. The line width change rate is preferably 10% or less, more preferably 7% or less, and particularly preferably 4% or less.

Line width change rate = (line width after saving−line width before saving) / (line width before saving) × 100 (%)
[Evaluation of cockling resistance]
Each solid image portion created above was visually observed for the occurrence of cockling (waviness or wrinkles in the recording material) due to printing, and the cockling resistance was evaluated according to the following criteria.

○: The occurrence of cockling is a high-quality characteristic. △: The occurrence of cockling is somewhat recognized, but the quality is practically acceptable. Quality

As is clear from the results in Table 2, a plain paper containing 0.1 g / m ² or more and 5.0 g / m ² or less of a water-soluble polyvalent metal salt contains a polysaccharide having a carboxyl group in the molecule. The image of the present invention formed by using a recording medium solution having a mass ratio of water and a non-aqueous solvent having a boiling point of 150 ° C. or higher is 50:50 to 5:95 is compared with the comparative example in terms of see-through resistance and storage. It can be seen that the bleeding resistance is excellent and the occurrence of cockling is small.

Example 2
<< Creation of images 12-17 >>
Using the prepared recording medium liquids 4 to 9 to the produced recording material 5, images with widths of 1 mm, 3 mm, and 5 mm were respectively output by an ink jet printer MC 2000 manufactured by Seiko Epson Corporation. 17 was created. Images 12A to 17A were prepared in the same manner as in the preparation of the images 12 to 17, except that the recording material was changed to Photo-like QP, which is a void-type inkjet recording material manufactured by Konica Minolta Photo Imaging.

<< Measurement of Vs / Vw >>
Regarding the non-aqueous solvent and water constituting the recording media 4 to 9 used in the image formation, J. Org. TAPPI paper pulp test method no. Vw and Vs were measured according to the above-mentioned method according to the liquid absorptivity test method for 51-87 paper or paperboard (Bristow method), and the permeation rate ratio Vs / Vw was determined.

<Evaluation of resistance to feathering>
The image line widths of 1 mm, 3 mm, and 5 mm of the images 12 to 17 and 12A to 17A created above were measured using a Micro Densitometer manufactured by Keyence Corporation (the width of the portion where the reflection density is 50% of the maximum density). Was defined as the line width). Next, when the image line widths of 1 mm, 3 mm, and 5 mm of the images 12A to 17A are set to 100%, the image line widths (line width increase rate) of the images 12 to 17 of 1 mm, 3 mm, and 5 mm are obtained. The average value was calculated and used as a measure of feathering resistance. The line width increase rate is preferably 110% or less, more preferably 107% or less, and particularly preferably 104% or less.

  The results obtained as described above are shown in Table 3.

  In addition, the detail of the non-aqueous solvent of Table 3 is as follows.

* A: Tripropylene glycol * B: Tripropylene glycol monomethyl ether * C: Dipropylene glycol monobutyl ether * D: Dipropylene glycol monomethyl ether

  As is apparent from the results shown in Table 3, among the structures defined by the ink jet recording method of the present invention, the penetration speed Vs of a non-aqueous solvent having a boiling point of 150 ° C. or higher as the recording medium liquid, and the penetration speed Vw of water It can be seen that the ratio (Vs / Vw) is 11> Vs / Vw> 6, or that the image formed under the condition where no surfactant is used has more improved resistance to feathering.

Example 3
<< Creation of images 18-22 >>
A solid image of 10 cm × 10 cm square was created on the produced recording material 5 using the prepared recording medium liquids 2 and 10 to 13 using an ink jet printer MC 2000 manufactured by Seiko Epson Corporation.

<Measurement of polysaccharide solubility>
1 g of each polysaccharide used in the preparation of recording medium solutions 2 and 10 to 13 was added to 99 g of dipropylene glycol monomethyl ether, stirred at room temperature for 1 hour, and then filtered through a 0.8 μm filter. Was collected. 5 g of a 2 mol / L hydrochloric acid aqueous solution was added to the collected filtrate and stirred. The resulting precipitate was then filtered, dried and weighed. The polysaccharide solubility S (g / L) was measured from the obtained weighed value W according to the following equation.

S = 10W
[Evaluation of transcription resistance]
After creating a solid image of 10 cm × 10 cm square by the above combination, an unprinted recording material 5 is overlaid on the solid image, and a 50 g weight with a bottom surface area of 4 cm ² is placed on the solid image, at 25 ° C. and 55% RH. It was left in the environment for 2 hours. Thereafter, the unprinted recording material 5 was peeled off, the degree of transfer of the recording medium liquid onto the overlapping surface was visually observed, and the transfer resistance was evaluated according to the following criteria.

◎: Image transfer to unprinted recording material is not recognized at all ○: Slight image transfer to the unprinted recording material is recognized, but the quality is acceptable for practical use ×: Clear to unprinted recording material Table 4 shows the results obtained with the above-mentioned quality that is problematic in practical use.

  As is apparent from the results shown in Table 4, it can be seen that the transfer resistance at the time of lamination after printing is improved by using the recording medium liquid containing polysaccharide. Specifically, it can be seen that by using a polysaccharide having a solubility in a non-aqueous organic solvent of 5 g / L or less, preferably 1.0 g / L, the transfer resistance to the back surface when laminated is further improved. .

Claims (4)

Inkjet printing on a plain paper containing a water-soluble polyvalent metal salt with a recording medium solution containing at least a colorant, a polysaccharide having a carboxyl group in the molecule, water and a non-aqueous solvent having a boiling point of 150 ° C. or higher by an inkjet method. A recording method, wherein the mass ratio of the water and the non-aqueous solvent having a boiling point of 150 ° C. or higher in the recording medium liquid is 50:50 to 5:95, and the plain paper contains An ink jet recording method, wherein the amount of the valent metal salt is 0.1 g / m ² or more and 5.0 g / m ² or less. The ratio (Vs / Vw) of the penetration rate Vs of the non-aqueous solvent having a boiling point of 150 ° C. or more into the plain paper and the penetration rate Vw of water is 11> Vs / Vw> 6, The inkjet recording method according to claim 1. The inkjet recording method according to claim 1, wherein the recording medium liquid does not contain a water-soluble surfactant. The inkjet recording method according to claim 1, wherein the polysaccharide has a boiling point of 5 g / L or less in a non-aqueous solvent having a boiling point of 150 ° C. or higher.