JPH0813569B2 - Recording medium and recording method using the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a recording material suitably used in an ink jet recording method, and in particular, it is excellent in absorptivity and color development of water-based ink, and the sharpness of a recorded image obtained. Excellent recording material.

Furthermore, the present invention relates to a recording material that provides a recorded image with little indoor discoloration of the image and excellent storage stability, and a recording method that provides the above-described recorded image.

Furthermore, the present invention relates to a recording material that provides a recorded image with little indoor discoloration of the image and excellent storage stability, and a recording method that provides the above-described recorded image.

[Conventional technology]

As a recording material for conventional ink jet, (1) a general paper containing pulp as a main component, which is made into a paper having a low size, such as a filter paper or a blotter paper, (2) As described in Japanese Patent Laid-Open No. 56-148585, a coating layer is provided on a substrate using a pigment that is porous and has a large oil absorption such as zeolite and that adsorbs a coloring component in the ink, and the like. There is.

Although the recording material (1) can be produced at low cost, the ink absorbability is excellent, but since the ink penetrates deeply into the fiber layer of the paper, the coloring of the coloring agent in the ink is poor, and the ink is on the paper surface. Since the particles are absorbed along the fibers, a phenomenon called feathering occurs, resulting in a phenomenon that dots are not rounded and jagged, and the resolution is lowered, so that a high quality image cannot be obtained.

For this reason, such non-coated type paper has been mainly used for monochrome recording, personal computer terminals, and the like, which do not necessarily require an image of relatively low resolution and high density.

In the recording material (2), since the ink absorbing layer is a porous layer and uniform, it is possible to obtain a material having an appropriate ink absorbing property and excellent dot shape and resolution.

However, in a recording method that requires a higher-quality and high-resolution color image, it is further overlapped on the side of the recording material, and (1) multicolor ink droplets adhere to the same spot in an overlapping manner. Also, it must have enough ink absorption capacity that dots do not flow out and spread more than necessary.

(2) It should have an ink absorption speed and ink fixability so that the adhered ink droplets will not bleed even if they are rubbed immediately.

(3) The color development of the recording material in the ink received in the ink absorbing layer is excellent.

(4) The area around the adhered ink dots is smooth and the shape is close to a perfect circle.

In addition to the above requirements, it is also required that the obtained recorded images have storability such as water resistance and light resistance.

In JP-A-59-185690 and JP-A-59-230787, attention is paid to the pigment physical properties of the ink absorbing layer in order to obtain more excellent dye color development, and a specific surface area of 200 m ² / g or more is provided. Recording materials using silica or silica having an acid value of 240 mg · mol / kg or more have been introduced.

Further, in JP-A-56-84992, as a method of enhancing the water resistance of an ink jet recorded image, an acid / direct dye is used for recording on a recording medium containing a polycationic polyelectrolyte in an ink absorbing layer to form a recorded image. There is described a method of preventing these dyes attached to the ink absorbing layer from flowing out even when the ink is immersed in water.

The light resistance of an image is a problem of discoloration of a recorded image due to photodecomposition of a dye, and until now it was considered to be a problem of the dye itself which is a recording agent. Are known to promote photodecomposition of dyes, and for example, in JP-A-60-11389 and JP-A-60-49990, polycations with little promotion of dye photolysis are disclosed. A recording material containing a polycation, and a recording material containing a polycation and an ultraviolet absorber or an antioxidant are introduced in JP-A-60-72785.

[Problems to be solved by the invention]

However, recently, in addition to such water resistance and light resistance, a new problem regarding image storability such as indoor discoloration of recorded images has been highlighted. The problem of indoor discoloration is also considered to be a problem caused by decomposition of the dye, but it cannot be solved by the conventionally known recording material.

Conventionally, the fading of an image, which has been a problem, is a phenomenon in which a dye in a recorded image is decomposed by visible light and ultraviolet light, and does not occur in a portion not exposed to direct sunlight. Also, in places exposed to sunlight, so-called general ppc paper or the above (1),
It is known that an image recorded on any type of recording material of (2) is discolored and accelerated when the recording material contains a polycationic substance.

On the other hand, the indoor discoloration referred to in the present invention proceeds even without direct sunlight, and does not occur in images recorded on plain paper or non-coated paper. Further, even if a polycation having a small influence on the light resistance as described above is used or an ultraviolet absorber or the like is contained, there is no significant effect, and discoloration of an image occurs.

The term "fading" as used herein refers to a phenomenon in which the saturation of a printed matter is reduced, and "discoloration" refers to a phenomenon mainly due to a change in hue without a decrease in saturation.

As described above, the problem of indoor discoloration referred to in the present invention is a phenomenon peculiar to coated paper having an ink absorbing layer, but no clear cause and no countermeasure has yet been known.

Therefore, an object of the present invention is to provide a recording material which is excellent in ink absorbency and color developability of a dye and which can provide a high-quality and high-resolution image.

It is another object of the present invention to provide a recording material that gives a recorded image which is less likely to be stored, particularly, deterioration caused by discoloration in a room, and a recording method for forming such an image.

The above and other objects of the present invention are achieved by the following present invention.

[Means and Actions for Solving Problems]

That is, the present invention has a porous ink absorbing layer containing a substrate and a pigment and a binder provided on the substrate, and the discoloration ΔE ^* ab of the CI hood black 2 by the ozone test is 20.
The following is a recording material characterized by the following, and a recording method of recording with an ink containing a water-soluble dye using the recording material.

As a result of various investigations on indoor discoloration, the present inventors have found that (1) it does not occur on non-coated paper, but only on coated paper having an ink receiving layer (hereinafter referred to as a coat layer) containing a pigment and a binder, In particular, it occurs remarkably on coated paper which is excellent in ink jet recording characteristics such as color development of the recording material and ink absorption.

(2) It is considered that the color fades when exposed to strong light such as sunlight, whereas the color change occurs in the indoor color change and the decomposition mechanism of the dye as a recording agent is different.

(3) Even if the type of recording material is changed to acidic dye, basic dye, direct dye, and food dye, the tendency of (1) and (2) does not change.

Due to the above reasons, indoor discoloration is (1) decomposition of dye by light and oxygen.

(2) The coat layer has a catalytic effect on this phenomenon,
In particular, coated paper, which is excellent in ink jet recording suitability, exhibits a strong action.

I reached the reasoning.

Based on this reasoning, the following ozone test method was devised as a method for measuring the catalytic activity of the coat layer.

The ozone test is considered to be a method for evaluating and measuring the catalytic activity of the coating layer when the dye is decomposed by oxygen, and is a method for evaluating and measuring new physical properties that could not be measured by various conventionally known methods. is there.

In the present invention, the ozone test is carried out by the following procedure.

(A) Preparation of test piece (i) As a test solution, 2 parts by weight of CI Food Black 2 as a dye is dissolved in a solvent consisting of 70 parts by weight of deionized water and 30 parts by weight of diethylene glycol.

(Ii) The test solution is applied to the coating layer at a rate of 0.4 μl to 0.5 μl / cm ² . As a method, a droplet is directly attached with a dropper or a pipet, an ink is transferred with a stamp or the like, an ink is applied with a bar coater or the like, and a droplet is attached with an ink jet recording method. There are methods.

(B) Test conditions (i) The test tank shall be shielded from light, and new ozone shall be supplied from inside or outside the tank without interruption, so that the concentration shall always be kept within the range of 0.1 ± 0.05 (volume)%.

In addition, the air inside is set so as to always cause convection by the fan.

(Ii) Environmental conditions in the tank are temperature 20 ℃ ± 2 ℃, humidity 65% ±
Set so that it is kept within the range of 3% RH. In order to complete the evaporation of the volatile components in the ink and to keep the amount of adsorbed water in the test piece constant, the test piece used should be stored in the above environment for two days after the preparation.

(Iii) After setting the conditions of (i) and (ii), expose to ozone in the test tank for 15 minutes.

(C) Method of outputting measured value (i) The color difference ΔE ^* ab of the test piece before and after ozone exposure for 15 minutes in the above test tank is determined by JISZ8730, and the color change ΔE ^* ab of the CI hood black 2 is obtained.

By using a recording material having a color difference (ΔE ^* ab) of 20 or less of the test piece obtained by the above ozone test, a recording material that provides an image without room discoloration, which is the object of the present invention, can be obtained. can get.

If the discoloration of CI Food Black 2 by the ozone test is 20 or more, the effect on the discoloration in the room is poor, which is not preferable. It is more preferably 10 or less.

CI food black used in ozone test 2
The same as the pH indicator and the redox indicator has a function as an indicator and can evaluate and measure the catalyst drop activity of the coat layer by the ozone test.

It is well known that dyes are decomposed by ozone, for example, J.Soc.Dyers.Color, Vol.100 (1984), No.4,
There are documents such as P.125 to 127 (M. Matsui et.al.).

However, the uncoated paper does not show a significant color change even when subjected to the ozone test, and the coated paper shows a significant color change, and therefore it is considered that the coated layer also has some catalytic action. Also, the decomposition of dye by ozone
It is considered that it will change greatly depending on the surrounding environment such as pH and ionic strength and the adsorption state of the dye in the coating layer such as Van der Waalsca, hydrogen bonding, etc., and it may be decomposed under certain conditions, for example, ozone is decomposed before attacking the dye. Or
When the coating layer adsorbs the dye so as to protect it from ozone attack, it is presumed that the decomposition of the dye tends to be suppressed.

The recording material of the present invention in which the color change of the CI hood black 2 by the ozone test is 20 or less is also considered to be the recording material having such a special coat layer.

On the other hand, it is unlikely that ozone directly contributes to indoor discoloration due to the fact that the ozone concentration in the familiar air is a few pphm and the lethal dose is 50 ppm. Since the oxygen of the oxygen molecule is in the triplet state and the oxygen of ozone is in the singlet state, it is considered that the decomposition mechanism is different, and it is presumed that it is difficult to directly connect the ozone test with the indoor discoloration. .

As mentioned above, some inferences have been introduced regarding the relationship between the ozone test and the indoor discoloration, but it is needless to say that the correctness of these inferences has nothing to do with the present invention.

Anyway, according to the knowledge of the present inventors, a recording material having a coat layer having a discoloration ΔE ^* ab of CI food black 2 of 20 or less by the ozone test described above is applied to an office or a household wall for one to several months. It does not cause discoloration in the room even if it is stored or stored in the drawer of a desk, and it has excellent ink jet recording suitability such as ink absorption and color development of recording material as a recording material with an ink absorption layer. It was a thing.

Hereinafter, a general configuration for obtaining the recording material of the present invention will be described, but it goes without saying that the discoloration ΔE ^* ab of the CI hood black 2 in the ozone test of the obtained recording material must be 20 or less. .

Examples of the substrate used in the present invention include conventionally known substrates such as paper, synthetic paper, plastic film, etc.
In particular, paper having a basis weight of 50 to 250 g / m ² and a Steckigt sizing degree of 0 to 100 seconds is suitable. If the grammage is less than 50 g / m ² , the paper is not firm and there is a problem with the paper feeding / discharging property in the printer. Further, if the basis weight exceeds 250 g / m ² , the powder falling off of the coat layer becomes severe, which is a problem. If the sizing degree of the paper exceeds 100 seconds, the adhesion between the coat layer and the base paper will decrease, and the powder will also fall off.

The paper as the base material used in the present invention is a sheet containing a fibrous substance and, if necessary, a filler, and is made within the above range by a conventionally known acidic papermaking method or neutral papermaking method with an appropriate sizing agent. Any thing can be used.

The fibrous material constituting the above paper used in the present invention is
Mainly wood pulp represented by LBKP and NBKP,
If necessary, various synthetic fibers or glass fibers may be mixed.

The coat layer is formed by using a coating liquid in which a pigment, a binder and, if necessary, various additives are mixed on the base material.

As the pigment used in the present invention, silica-based pigments such as silica, silicate minerals and synthetic silicate compounds having a pH of 7 or more are preferably used, and more preferably pH 8
That is all.

In the present invention, the pH of the pigment is measured by a pH meter while adding 100 g of ion-exchanged water (pH 5.8 to 6.4) to a 200 cc beaker, adding 10 g of the pigment and stirring for 5 minutes with a stirrer, while the pigment is suspended. Say the pH. The pH of silica-based pigments is usually about 5.5 to 6.5 depending on the production method. For example, silica produced by the dry method is weakly acidic because it adsorbs a small amount of by-produced HCl.

As a method of adjusting the pH of such a pigment to 7 or more, (1) a method of producing silica by reacting sodium silicate and a mineral acid in an aqueous solution, and sodium when purifying the silica produced in the step By keeping the concentration high, sodium is adsorbed on silica and the pH is raised.

(2) When silica is salted out and purified by the method of producing silica by reacting sodium silicate and salts in an aqueous solution, by maintaining a high concentration of basic oxides and unreacted salts, pH
Raise.

(3) Add Na, Mg, Ca, B to a suspension of purified pigment such as silica.
A metal salt such as a or Zn or a metal soap is added to coat the silanol groups on the surface in the form of salt.

(4) A basic oxide such as MgO, CaO, or BaO is included in the crystal structure of the pigment.

There is a method such as. By these methods, a pigment having a pH of 7 or more can be obtained.

When a pigment having a pH of less than 7 is used, the recorded image obtained has large indoor discoloration, and in particular, the indoor discoloration significantly occurs.
The cause of this is not clear, but the dye adsorbed on the pigment (especially the azo dye) is oxidized by oxygen in the air and becomes a decomposed product and changes color, that is, the active sites on the pigment surface catalyze the oxidative decomposition of the dye. It is considered to be promoting.
This catalytic effect changes greatly depending on the pH of the pigment, and promotes oxidative decomposition at a pH of less than 7, but decreases the catalytic activity at a pH of 7 or more, and is considered to be inactive and thus prevent discoloration or brown discoloration of the black dye. To be

Furthermore, the specific surface area of the pigment used in the present invention is 35 to 650 m ² /
g, more preferably 60 to 350 m ² / g.

When a recording material is formed by using a pigment having a specific surface area of less than 35 m ² / g, the chromaticity and ink absorbency of a recorded image are lowered, and when the specific surface area exceeds 650 m ² / g. Even if the pH is 7 or more, the discoloration in the room cannot be improved because the catalytic activity on the surface is too strong.

Next, as the binder used in the present invention, for example, polyvinyl alcohol, starch, oxidized starch, cationized denpin, casein, carboxymethyl cellulose,
Water-soluble polymers such as gelatin and hydroxyethyl cellulose, and water-dispersible polymers such as SBR latex, MBR latex, vinegar acetate, acrylic emulsion, etc.
One kind or a mixture of two or more kinds is used.

In the present invention, the use ratio (weight ratio) of the pigment and the binder is preferably in the range of 1/2 to 20/1. If the amount of binder is more than 1/2, the ink absorbency of the coat layer will decrease,
If the amount of pigment is more than 20/1, the powder drop of the coat layer will be a serious problem.

Further, in the present invention, a dye fixing agent (waterproofing agent), a fluorescent sensitizer, a surfactant, a defoaming agent, a P
It may contain H regulators, fungicides, ultraviolet absorbers, antioxidants and the like.

According to the knowledge of the present inventors, as a dye fixing agent, particularly when a polycationic substance is contained, the water resistance of a recorded image is enhanced and an effect of suppressing indoor discoloration is exhibited, and therefore, it is more preferable to use these. It is desirable to contain it.

As such a cationic substance, any conventionally known waterproofing agent for ink jet paper having a quaternized amine in its structure can be used. It is desirable to use such a waterproofing agent (dye fixing agent) in an amount of about 0.5 to 15% by weight based on the pigment. If it is contained in an amount of 15% by weight or more, it is not preferable since it is effective in discoloring the image indoors, but the light resistance is significantly deteriorated.

Further, in order for the recording material of the present invention to have more excellent ink absorbability, dye color development, resolution, etc., it is necessary to have two or more coating layers and separate the functions of each layer. Is good. According to the knowledge of the inventor of the present invention, it is desirable to select a material for the outermost layer with a focus on color developability of a colorant, roundness of dots, surface strength of a coating layer, etc. It is preferable to design with the absorption capacity as the main focus.

As a method for applying the water-based coating liquid obtained by mixing the above-mentioned materials onto the above-mentioned substrate, any conventionally known method such as a bar coater, a blade coater, an air knife coater or a reverse roll coater can be used.

The dry coating amount of the water-based coating liquid is preferably ² to 50 g / m ² .

That is, if it is ² g / m ² or less, there is a problem of feathering in which the ink absorbency is lowered or the ink bleeds along the fibers exposed on the surface, and when coated at 50 g / m ² or more, the coating layer becomes brittle and powder falls off. Problem occurs.

After applying the horizontal coating liquid under the above conditions, a conventionally known drying method such as a hot air drying furnace or a heating drum is also dried to obtain a recording material. This step may be repeated if the number of coat layers is two or more.

Further, in order to smooth the surface of the coat layer or increase the surface strength of the coat layer, a super calendar may be used in the process.

According to the recording method of recording on the recording material having the above-mentioned structure, the ink jet recording method is used to record with a multicolored water-based ink such as yellow (Y), magenta (M), cyan (C), black (BK), etc. Thus, the obtained image does not undergo discoloration in the room, and a recorded image having excellent storability can be obtained.

In the method of the present invention, the ink itself applied to the specific recording material as described above by the ink jet recording method may be a known one, for example, a direct dye, an acid dye, a basic dye, a reactive dye, an edible pigment, etc. It is a water-soluble dye that is particularly suitable as an ink for ink jet recording systems, and meets the required performance such as fixability, color developability, vividness, stability, light fastness, etc. in combination with the above recording material. Preferred as giving an image, for example, CI Direct Black 17,19,32,51,71,108,146 CI Direct Blue 6,22,25,71,86,90,106,199 CI Direct Red 1,4,17,28,83 CI Direct Yellow 12,24,26,86,98,142 CI Direct Orange 34,39,44,46,60 CI Direct Violet 47,48 CI Direct Brown 109 CI Direct Green 59 and other direct dyes, CI Assisted Black 2,7,24, 26,31,5 2,63,112,118 CI Assisted Blue 9,22,40,59,93,102,104,113,117,12
0,167,229,234 CI Assisted Thread 1,6,32,37,51,52,80,85,87,92,94,1
15,180,256,317,315 CI Acid Yellow 11,17,23,25,29,42,61,71 CI Acid Orange 7,19 CI Acid Blue Oleate 49 Acid dyes such as CI are preferred, other CI basic black 2 CI basic blue 1 , 3,5,7,9,24,25,26,28,29 CI basic cleats 1,2,9,12,13,14,37 CI basic violet 7,14,27 CI food black 1,2 etc. Can also be used.

The above dye examples are particularly preferable for the ink applicable to the recording method of the present invention, and the dye for the ink used in the present invention is not limited to these dyes.

Such a water-soluble dye is generally used at a ratio of about 0.1 to 20% by weight in a conventional ink, and the same may be used in the present invention.

The solvent used in the water-based ink used in the present invention is water or a mixed solvent of water and a water-soluble organic solvent, and particularly preferable is a mixed solvent of water, a water-soluble organic solvent, and a water-soluble organic solvent. It contains a polyhydric alcohol having an ink drying preventing effect. As the water, it is preferable to use deionized water instead of general water containing various ions.

The content of the water-soluble organic solvent in the ink is generally 0 to 95% by weight based on the total weight of the ink, preferably
It is in the range of 10-80% by weight, more preferably 15-50% by weight.

In addition, the ink used in the present invention may further include a surfactant, a viscosity modifier, a surface tension modifier, and the like, if necessary, in addition to the above components.

In the method of the present invention, the ink jet recording method for applying the above-mentioned ink to the specific recording material to perform the recording is such that the ink is effectively detached from the nozzles, and the ink is applied to the recording material which is a projectile. Any method may be used as long as the method can be given, and a typical one of those methods is:
For example, IEEE Trans Transactions on Industry Applications (IEEE Trans
actions on Industry Applications) Vol.JA-13, No.1
(February and March, 1977 issue), Nikkei Electronics 1976 April
19th, 29th January 1973 and 6th May 1974. The methods described in these are suitable for the method of the present invention, some of which are first described as an electrostatic attraction method. In this method, there is a gap between a nozzle and an accelerating electrode placed a few mm in front of the nozzle. A strong electric field is applied to atomize the ink from the nozzle, and the ink is withdrawn one after another, and an information signal is applied to the deflection electrode while the drawn ink flies between the deflection electrodes for recording, and information is recorded without deflecting the ink particles. There is a method of ejecting ink particles in response to a signal, both of which are effective for the method of the present invention.

The second method is a method of forcibly ejecting minute ink particles by applying a high pressure to the ink with a small pump and mechanically vibrating the nozzle with a crystal oscillator or the like. At the same time, it is charged according to the information signal. When the charged ink particles pass between the deflection electrode plates, they are deflected according to the charge amount. Another method using this method is called the microdot ink jet method. In this method, ink pressure and excitation conditions are maintained at a certain range of appropriate values, and two types of ink droplets, large and small, are ejected from the nozzle tip. It is generated, and only the medium and small diameter droplets are used for recording. The feature of this method is that a fine droplet group can be obtained even with a nozzle diameter as large as the conventional one.

A third method is a piezo element method. In this method, a piezo element is used as the pressure means for applying ink to the ink, instead of a mechanical means such as a pump as in other methods. In this method, an electric signal is applied to the piezo element to cause mechanical displacement, thereby applying pressure to the ink and ejecting it from the nozzle.

Further, by the method described in JP-A-54-59936,
The ink subjected to the action of thermal energy causes a rapid volume change, and the ink jet method in which the ink is ejected from the nozzle by the acting force due to this state change can also be effectively used.

〔The invention's effect〕

The recording material of the present invention contains a large amount of a pigment having a high ink-absorbing ability in the surface layer, so that the ink droplets have a high probability of being trapped and absorbed by the pigment, and therefore ink bleeding and diffusion are suppressed, As a result, the dot shape is improved and excellent ink absorption, resolution, color development, color density, etc. are exhibited.

Further, the present invention has the ink jet recording suitability as the coated paper as described above, but has less problem of image storability peculiar to the coated paper, and the recording method by the ink jet recording method using the recording material of the present invention and multicolor ink In this case, the problem of room discoloration does not occur when the obtained image is stored for one to several months in an office wall or a drawer where it is not exposed to direct sunlight.

〔Example〕

Next, the present invention will be described more specifically with reference to Examples and Comparative Examples. In the text, "part" or "%" is based on weight unless otherwise specified.

Examples 1 to 8 and Comparative Examples 1 to 7 Basis weight 100 g / m ² , sizing degree 22 seconds was used as a base material, and the following coating composition was dried on the base material at a dry coating amount of 20 g / m ^2. So as to obtain a recording material of the present invention and a recording material for comparison by hot-air drying at 110 ° C. for 5 minutes.

(Coating liquid composition 1) Pigment 25 parts Polyvinyl alcohol (PVA-117 Kuraray) 3 Polyvinyl alcohol (PVA-105 Kuraray) 3 Silane-modified polyvinyl alcohol (R-1130 Kuraray)
4 Water 200 (Coating liquid composition 2) Pigment 25 parts Polyvinyl alcohol (PVA-117 Kuraray) 5 Cation-modified polyvinyl alcohol (PVA-C-118-2A Kuraray) 5 Polyamine waterproofing agent (Polyfix 601 Showa High Polymer) ) <60% aqueous solution> 3 Fluorescent whitening agent (Kaycoll BRAL, manufactured by Nisso Kako) 0.3 Water 200 (Coating liquid composition 3) Pigment 27 parts Polyvinyl alcohol (PVA-117 Kuraray) 6 Polyvinyl alcohol (PVA-105 Kuraray) 12) Polyamine-based water resistant agent (PAS-A Nitto Boseki) <50% aqueous solution> 3 Optical brightener (Kaycoll BRAL, manufactured by Nisso Chemical Co., Ltd.) 0.3 Water 200 The composition of the above coating liquid and the pigment of Table 2 Table 1 shows the formulations of the examples of the present invention and the comparative examples according to the combination.

In Table 1, A: silicate mineral C: magnesium silicate E: magnesium carbonate O: aluminum oxide P: titanium dioxide, and samples B, D, F to N are all silica.

Among these, N is silica manufactured by a dry method (gas phase method), and the others are silica manufactured by a wet method.

Example 9 Coating composition 1 using Pigment F was coated by a bar coater method so that the dry coating amount was 20 g / m ^2, and a coating layer was formed on a substrate in the same manner as in Examples 1-8. After the formation, an upper layer having a dry coating amount of 8 g / m ² was similarly formed on the coating layer by using the pigment B and the coating composition 3 to obtain a recording material of the present invention.

Comparative Example 8 A recording material for comparison was obtained in the same manner as in Example 9 except that the pigment L was used in place of the pigment F, and the pigment K was used in place of the pigment B.

Comparative Examples 9 and 10 Commercially available ink jet coated paper NM (made by Mitsubishi Paper Mills), F
C-3 (made by Tojo Paper Co., Ltd.) was used as a recording material for comparison.

Examples 10 to 12 Recording materials of the present invention were obtained in the same manner as in Example 9 except that the pigments used and the dry coating amounts were as shown in the table below.

Lower layer Upper layer Example 10 D: 20 g / m ² G: 8 g / m ² 11 E: 24 g / m ² N: 4 g / m ² 12 J: 14 g / m ² A: 14 g / m ² Ink jet of the above recording material Recording suitability is 1 in 1mm
An ink jet printer (a) having four colors of Y, M, C, and BK with 128 ink jet heads at a nozzle spacing of 6 nozzles and 24 nozzles at an interval of 8 per 1 mm. Using an ink jet printer (b) having four colors, ink jet recording was performed with the ink having the following composition and evaluated.

◎ Ink composition (I) Dye 2 parts Ethanol 5 parts Diethylene glycol 15 parts Water 78 parts Dye (Ink I) Y: CI Direct Yellow 86 M: CI Acid Red 35 C: CI Direct Blue 199 BK: CI Direct Black 17 ◎ Ink Composition ( II) Dye 2 parts Diethylene glycol 20 parts Polyethylene glycol # 200 15 parts n-Methyl-2-pyrrolidone 10 parts Water 53 parts Dye (Ink II) Y: CI Acid Yellow 42 M: CI Acid Red 92 C: CI Direct Blue 86 BK : CI direct black 51 ◎ Ink composition (III) CI composition black as a dye in ink composition (II)
26 was used.

The following items were evaluated. The results are shown in Table 3.

Measurement and Evaluation Method (1) Discoloration ΔE ^* ab of CI food black 2 by ozone test was measured by the above method.

(2) Ink absorbency was evaluated using an ink jet printer (a) using the ink (I). In the mixed color portion of the two color inks of the recorded image, the one having a thicker line thickness than the single color portion was marked with X, the one having no line was marked with ◯, the one having a slight line was marked with Δ, and the one not having the mixed color portion of three colors was marked with ◎.

(3) Image clarity is ink (I), printer (a)
When printed using, the image having a sharp edge without any feathering and the like was obtained, and the image not having the image was given as x.

(4) In the room storability (1), a color image was formed using the inks (I), (II) and the printer (a), and the color image was placed on the wall of the office and left for 6 months. Same image for 6
When the discoloration compared to the images stored in the clear month pocket file is not good, the discoloration is severe, and the middle one is bad.

(5) The indoor storability (2) is obtained by printing a solid pattern of BK using the ink (III) and the printer (b), and (4)
I left it on the office wall for a month as well. Difference ΔE between the chromaticity of this image and the chromaticity of the image immediately after printing The ab was obtained and the indoor discoloration property was evaluated.

Claims (10)

[Claims] 1. A color ink having a porous ink-receiving layer containing a base material and a pigment and a binder provided on the base material, and having a discoloration ΔE ^* ab of CI food black 2 of 20 or less by an ozone test. Recording material characterized by. 2. The discoloration ΔE ^* ab of the CI food black is 1.
The recording material according to claim 1, which is 0 or less. 3. The recording material according to claim 1, wherein the pigment contains a silica-based pigment. 4. The recording material according to claim 1, wherein the pH of the pigment is 7 or more. 5. The recording material according to claim 1, wherein the pH of the pigment is 8 or more. 6. The recording material according to claim 1, wherein the ink receiving layer contains a dye fixing agent. 7. The recording material according to claim 6, wherein the dye fixing agent is a cationic resin. 8. The recording material according to claim 1, wherein the ink receiving layer has a multilayer structure. 9. A recording method for recording by causing ink droplets containing a water-soluble dye to adhere to a recording material, wherein the recording material has a porous ink receiving layer containing a pigment and a binder. A recording method characterized by using a CI food black 2 having a discoloration ΔE ^* ab of 20 or less by an ozone test. 10. A discoloration Δ of the recording material by an ozone test.
The recording method according to claim 9, wherein E ^* ab is 10 or less.