JPH01222987A - Material to be recorded and recording method using said material - Google Patents

Abstract

PURPOSE:To obtain superior ink absorptivity and dye color forming properties to realize a high-quality image with a high resolving power, by a method wherein, a substrate and a porous ink accepting layer which contains a pigment and a binder and is disposed on the substrate are provided, and a degree of discoloration (DELTAb*) by a [4,4'-methylene-bis-2,6-(di-tertiary butyl phenol)] (BHT2) spot test is specified. CONSTITUTION:As a substrate, a paper, a synthetic paper, a plastic film, and others can be used, but a paper with a basis weight of approximately 50-250g/m<2> is preferably used. A coating layer is formed on the substrate by using a coating liquid of a mixture of a pigment, a binder, and various types of additives, as necessary. In the process of producing a silica by causing a silicate or soda to react with a mineral acid in a water solution a water-soluble metal salt of Mg, Ca, Zn, or Ba is added thereto. The use of a pigment incorporating the metal in a part of the crystal structure of the silica in the above manner regulates a value DELTAb* by a spot test to 10 or less to make a material to be recorded available with little room discoloration.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a recording material suitably used in an inkjet recording method, and particularly to a recording material having good absorbency of water-based ink.

The present invention relates to a recording material with excellent color development and excellent clarity of recorded images obtained.

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

[Conventional technology]

Conventional recording materials for inkjet use include: (1) general paper containing valves as its main component, which is made into a small size paper such as filter paper or blotting paper; (2) JP-A-Sho. As disclosed in Japanese Patent No. 56-148585, a coating layer is provided on a substrate using a porous pigment such as silica or zeolite that has a large oil absorption capacity and adsorbs the coloring components in the ink. .

Recording material (1) can be produced at low cost, but although it has excellent ink absorption, the ink penetrates deeply into the fiber layer of the paper, resulting in poor color development of the colorant in the ink, and the ink does not adhere to the surface of the paper. Since it is absorbed along the fibers, a phenomenon called feathering occurs, which causes the dots to become jagged instead of circular, and the resolution to deteriorate, making it impossible to obtain high-quality images.

For this reason, such uncoated paper has been used for applications that do not necessarily require relatively low-resolution (high-density images), such as monochrome recording and personal computer terminals.

Since the ink absorbing layer of the recording material (2) is porous and uniform, it is possible to obtain an appropriate ink absorbency and excellent dot shape and resolution.

However, in recording methods that require higher quality and higher resolution color images, (1) multicolored ink droplets are deposited on the same spot overlappingly on the recording material side. It also has an ink absorption capacity that prevents dots from flowing out and from spreading more than necessary.

(2) The ink absorption speed and ink fixing properties should be such that the attached ink droplets will not smear even if they are rubbed immediately afterwards.

(3) The recording agent in the ink received by the ink absorbing layer has excellent coloring properties.

(4) The periphery of the attached ink dot should be smooth and the shape should be close to a perfect circle.

In addition to the above requirements, the resulting recorded images must also be water resistant.

Preservability such as light resistance is also required.

JP-A-59-185690 and JP-A-59-230
Publication No. 787 focuses on the physical properties of pigments in the ink absorbing layer in order to obtain better coloring properties of dyes, and uses silica having a specific surface area of 200 rrf/g or more and 240 mg-moj!
A recording material using silica having an acid value of /kg or more has been introduced.

Furthermore, Japanese Patent Application Laid-Open No. 56-84992 discloses a method of enhancing the water resistance of inkjet recorded images by recording with an acidic/direct dye on a recording medium containing a polycationic polymer electrolyte in the ink absorbing layer. A method is described for preventing these dyes attached to the ink absorbing layer from flowing out even when a recorded image is immersed in water.

The light fastness of images is a problem of discoloration and discoloration of recorded images due to photodecomposition of dyes, and until now it was thought that the problem was a problem of the dye itself, which is a recording agent, but water fastening agents such as the above, especially polycationic substances It has come to be known that polycations promote the photodecomposition of dyes. The recording material to be
No. 0-72785 introduces recording materials containing polycations, ultraviolet absorbers, and antioxidants.

[Problem that the invention seeks to solve]

However, recently, such water resistance has become available.

In addition to light fastness, a new problem related to image storage stability, ie, indoor discoloration of recorded images, has been brought into focus. The problem of indoor discoloration is also considered to be a problem caused by the decomposition of dyes, but this problem cannot be solved with conventionally known recording materials.

Visible light causes image fading, which has traditionally been a problem.

This phenomenon occurs when the dye in the recorded image decomposes due to ultraviolet light, and does not occur in areas that are not exposed to direct sunlight.

In addition, when exposed to sunlight, images recorded on so-called general PPC paper or any of the recording materials mentioned in (1) and (2) above will fade, and if the recording material contains polycationic substances, known to be promoted.

On the other hand, the indoor discoloration referred to in the present invention progresses even in the absence of direct sunlight, and does not occur in images recorded on general paper or non-coated paper. Further, even if a polycation, which has little effect on light resistance as mentioned above, is used or an ultraviolet absorber is contained, there is no significant effect (discoloration of the image occurs).

Note that fading here refers to a phenomenon in which the saturation of a printed matter decreases, and discoloration refers to a phenomenon in which the saturation does not decrease, but rather changes in hue.

As described above, the problem of indoor discoloration referred to in the present invention is a phenomenon unique to coated paper having an ink absorbing layer, but its clear cause and countermeasure are not yet known.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a recording material that has excellent ink absorption properties and dye coloring properties, and is capable of producing high-quality, high-resolution images.

Another object of the present invention is to provide a recording material that provides a long shelf life of recorded images, particularly a recorded image that is less likely to deteriorate due to indoor discoloration, and a recording method for forming such an image.

The above and other objects of the invention are achieved by the invention as follows.

[Means and effects for solving the problems] That is, the present invention has a base material and a porous ink receiving layer provided on the base material containing a pigment and a binder, and Δb* according to the BHT2 spot test is 10 or less, and a recording method in which recording is performed using an ink containing an acidic and/or direct dye using the recording material.

As a result of numerous investigations into indoor discoloration, the inventors of the present invention found that (1) discoloration does not occur on uncoated paper, but occurs only on coated paper that has an ink-receiving layer (hereinafter referred to as coat layer) containing pigment and binder; This phenomenon is particularly noticeable on coated paper which has excellent inkjet recording properties such as color development and ink absorption of the recording agent.

(2) Discoloration occurs when exposed to strong light such as sunlight, whereas discoloration occurs indoors, and it is thought that the decomposition mechanism of the dye used as the recording agent is different.

(3) Types of recording media: acidic dyes and basic dyes.

Even if it is replaced with direct dye 9 food coloring, the above (L), (2)
The trend remains unchanged.

Due to reasons such as indoor discoloration, (1) Dye decomposition by light and oxygen.

(2) The coated layer exhibits a catalytic effect against this phenomenon, and coated paper, which is particularly suitable for inkjet recording, exhibits a strong effect.

I came to the conclusion that.

Based on this reasoning, we devised a method called the BHT2 spot test shown below as a method for measuring the catalytic activity of the coat layer.

According to the findings of the present inventors, the catalytic activity of the coating layer is determined by the surface acid value of the pigment itself forming the coating layer, the pore structure and coverage of the binder to the pigment, the type of binder, the pore structure of the coating layer itself, and the pore structure of the coating layer itself. The presence or absence of additives (water-resistant agents, antioxidants, etc.).

It is thought that it is influenced by the content of one type and the distribution state of the binder and these additives within the coating layer, and is also determined by the influence from the base material.

Therefore, the catalytic activity of the coat layer cannot be measured by measuring individual physical properties using conventionally known methods.

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

In the present invention, the BHT2 spot test refers to a test conducted according to the following procedure.

(a) Preparation of test solution and test piece (i) BBr2 (,4,4'-Methylen
-bis-2,6-ditert-buthylphe
Nol) (reagent) is dissolved in ethanol to prepare l (weight)% BHT2 reagent.

(11) Drop 20 μl of the BHT2 reagent described above onto the recording surface of the recording paper so that it spreads in a circle with a diameter of 20±5 mm. The BHT2 reagent is dropped using a conventional method using, for example, a volumetric pipette, a whole pipette, etc., and its spread on the recording surface is
This is the level normally obtained by such a method.

(b) Test conditions (i) The test piece prepared above was shielded from light and the temperature was 23.
The product was left for 100 hours in a normal environment adjusted to ℃±3°C, 55%±5% RH, and the activity was evaluated based on the degree of coloring of the dripped area, which was colored after being left for 100 hours.

(ii) The recording paper used in this test is one that has been stored in the above environment for two days or more in order to keep the amount of adsorbed moisture constant, and is tested under the above environment.

(c) How to obtain measured values (i) CIE CA of the colored area after 100 hours
The CIE CAB of B (L*+ a** b*) and the white background part (undropped part) is determined, and the difference Δb tree between the yellow component of both: b tree is determined, and it is set as Δb* by the spot test.

As mentioned above, the spot test is a very simple method to measure the catalytic activity of the coated layer, and in this way, the
Δb* of the test piece obtained by T 2 spot test is 1
By using a recording material of 0 or less, a recording material that provides an image free of indoor discoloration, which is the object of the present invention, can be obtained.

Discoloration (Δb*) of BIT2 by spot test was '10
Anything over 20% is less effective against indoor discoloration, so
Undesirable. More preferably, it is 7 or less.

BIT2 used in this test has a function as an indicator like a pH indicator, a redox indicator, etc., and can evaluate and measure the catalytic activity of the coat layer. BIT
2 (4,4'-methylene-bis-(2,6-di-tert-butylphenol)) itself is used as an antioxidant in polypropylene, polyethylene films, etc. for food packaging, etc. is publicly known.

It is known to some extent that phenolic antioxidants, including BIT2, turn yellow over time, and although the mechanism itself is not clear, for example, BIT (3,
5-di-tert-butyl-4-hydroxy-toluene) etc. are oxidized to form a dimer with a quinone structure, resulting in a yellow color (
It is thought to be colored.

According to the study results of the present inventor, for example, it has been found that yellow coloring is accelerated when the above-mentioned test piece is placed in an ozone atmosphere, and it is unlikely that this yellow colored substance is due to the oxidation of BIT2. it is obvious. The value of Δb8 determined by the spot test of the present invention is used to quantify the degree of oxidation of BIT2.

Furthermore, when the inventor conducted the above-mentioned spot test on various recording papers, the BIT2 discoloration did not occur on non-coated paper or plain paper, but only on so-called coated paper for IJ, which provides high-density images. The coloring of BIT2 (Δb*
), there is also less indoor discoloration of the image (we discovered that there is a strong correlation between the two, leading to the present invention).

In other words, the yellowing caused by the oxidation of BIT2 is a reaction that progresses using the adsorbed coating layer as a catalyst, and like indoor discoloration,
It is thought that coated paper having a coating layer with high catalytic activity is particularly effective.

According to the findings of the present inventors, the catalytic activity of the coating layer is obtained as a result of a combination of various factors as described above, and the B of the recording paper finally obtained by combining these factors. ) By configuring the recording paper so that Δb* of the IT2 spot test is 10 or less, it will last for one to several months.
An ink-receiving layer that does not cause indoor discoloration when placed on the wall inside an office or stored in a desk drawer, and has excellent ink absorption and recording agent coloring properties. It is possible to obtain coated paper with

The general structure for obtaining the recording material of the present invention will be described below, but it goes without saying that the obtained recording material must have a Δb* of 10 or less in the BHT 2 spot test.

The base material used in the present invention includes conventionally known base materials such as paper 2 synthetic paper, plastic film, etc., but paper having a basis weight of about 50 to 250 g/rrr is particularly suitable.

The paper used as a base material in the present invention is a sheet containing a fibrous substance and, if necessary, a filler, and is made into paper within the above range using a suitable sizing agent by a conventionally known acidic papermaking method or neutral papermaking method. You can use any of them.

The fibrous material constituting the above paper used in the present invention is L
The main material is wood bulbs such as BKP and NBKP, but various synthetic fibers, glass fibers, etc. may be mixed if necessary.

The coating layer is formed on the base material using a coating liquid containing a pigment, a binder, and, if necessary, various additives.

Examples of specific preferred embodiments of the coating layer for carrying out the present invention are shown below.

Examples of the pigment used in the present invention include silica pigments, that is, synthetic silicon-containing pigments such as synthetic silica and synthetic silicate compounds. The silicon-containing pigment referred to herein is one containing 50% by weight or more of SiO2 as a component of particles. Pigments with a content of less than 50% by weight are undesirable because both ink absorption and dye color development are low.

In the present invention, as a preferred embodiment (1) in which Δb* in the spot test is 10 or less, Mg in the particles is
The recording surface contains a silicon-containing pigment containing 0.1% by weight or more of a metal selected from the group of , Ca, Zn, and Ba,
Specifically, such pigments include: (1) The above-mentioned Mg and Ca are used during the process of producing silica by reacting sodium silicate and mineral acid in an aqueous solution.

Silica containing the above metals in part of its crystal structure by adding water-soluble metal salts such as Zn and Ba.

(2) Mg and Ca are added to the step of purifying silica in the above process or to a commercially available silica suspension.

After adding metal salts such as Zn and Ba, metal soaps, and metal oxides, the surface of silica is coated with these metals by heating and drying.

etc., but ■ is more effective.

By using such a pigment, it is possible to adjust Δb* in a spot test to 10 or less and provide a recording material with little indoor discoloration. However, these pigments have the problem of not being able to obtain high image density compared to silica for inkjet coated paper, such as Siloid (trade name, manufactured by Fuji Davison).
Therefore, embodiment (1) is a method that sacrifices image density to some extent.

Next, as an example (2), as a method of compensating for the decrease in image density when such a pigment is used, example (1)
An example of this method is to use a cationic substance in combination with the pigment used in .

As for the cationic substance, when using a cationic substance as a binder, when the above-mentioned pigment is cationized so that the pigment itself doubles as a cationic substance, when using a separate cationic pigment, when using a cationic substance as an additive, Examples include cases where substances are included.

As the cationic binder, cationic functional group,
For example, primary to tertiary amines, quaternary ammonium salts, pyridine, pyridine, imidazole.

Examples include cationically modified polymers containing imidazolinium, sulfonium, phosphonium, etc., such as cationically modified polyvinyl alcohol, quaternized polyvinylpyrrolidone, cationic SBR latex, cationic starch, and cationic polyacrylamide.

As a method for cationizing the pigment, a silane coupling agent having the functional group listed above, such as octadecyldimethyl[3-()rimethoxysilyl)propyl]ammonium chloride, or titanate coupling may be used. Examples include a method of cationizing the surface with an agent or an aluminum compound.

A cationic pigment is a pigment having a positive surface potential, and a typical example thereof is alumina, and other pigments can also be obtained in the same manner as above.

Examples include those obtained by cationizing conventionally known pigments.

Examples of the cationic substance as an additive include polymers and oligomers having a cationic functional group as described above, and these also include polymers commercially available as waterproofing agents. Other examples include organic aluminum compounds, but in any case, low molecular weight compounds with a molecular weight of 500 or less are undesirable because they cause a decrease in the coating strength of the coating layer.

Examples of cationic substances include those mentioned above, and according to the findings of the present inventors, it is clear that these have the effect of improving image density. The influence of these materials is unknown, and for this reason, materials with Δb* of 10 or less according to a spot test and those with no adverse effects should be selected and used.

Furthermore, it is generally known that cationic substances, particularly amine-based substances, have an adverse effect on the lightfastness of images, and therefore embodiment (2) is a method that sacrifices image density and/or lightfastness to some extent. .

Embodiment (3) contains silica such as the conventionally used Thyroid (trade name, manufactured by Fuji Davison) and additives. The silica used in such inkjet paper has a large Δb* in a spot test,
Indoor discoloration is also extremely bad, so as an additive, Δ
A material that lowers b* is used.

There are two types of such additives: (1) antioxidants and (2) water-soluble metal salts.

Hindered Fer is an antioxidant.

Examples include fers such as bis-fers, thioethers, phosphites, and hindered amines, but among these, thioethers are the ones that lower Δb* in the spot test, so the ones that can be used are: , thioether only.

However, in order to reduce Δb to 10 or less using normal inkjet silica and antioxidants, it is necessary to use thioethers with a pigment ratio of 20% or more. The decrease in absorbency is particularly significant. Therefore, this method sacrifices image density and ink absorption.

In addition, water-soluble metal salts include Mg, Ca, and Ba.

Refers to metal salts such as Ni, Ti, Fe, Cu, Co, Zn, etc., but according to the knowledge of the present inventor, Ni
, Cu.

Since metals such as Fe deteriorate the color development of dyes, especially magenta dyes, metal salts of alkaline earth metals such as Mg, Ca, and Ba are preferred.

However, in order to similarly reduce Δb* to 10 or less using ordinary inkjet silica and a water-soluble metal salt, the metal salt is required to have a pigment ratio of 10 to 15% or more, and in this case, the coating layer strength, especially Water resistance strength when wet is reduced.

Embodiment (4) includes a method of using a binder that reduces Δb* in combination with the above-mentioned inkjet silica. According to the study results of the present inventor, examples of such a binder include SDR latex, but in this case as well, it is necessary to use the amount of 50 to 100% by weight or more based on the pigment, resulting in a decrease in ink absorption. Furthermore, there arises the problem of decreased color development. In this case, it is thought that the latex binder plays the role of an antioxidant.

As an example (5), silica (Si) on the recording surface
Usage ratio of pigment and binder (B) S i / B
One example is to increase the pigment coverage of the binder by setting the ratio to 1.5 or less, more preferably 1.0 or less, but in this case, the ink absorbency is significantly sacrificed.

As a method for reducing the catalytic activity of the recording material, we have discussed some examples that were found to be effective using the index Δb tree in the spot test, but none of these methods can be used alone. It also comes with side effects. Of course, it is possible to optimally design the coating layer by combining the above methods or other methods, but in that case,
As mentioned above, there is more than one factor that influences the catalytic activity of the coat layer, and estimating the total amount of catalytic activity is complicated and difficult.

According to the present invention, when designing paper that suppresses indoor discoloration by combining the above methods, it is possible to reduce the catalytic activity of the coating layer, which causes indoor discoloration when images are stored indoors for a long time. can be easily measured, and by designing the catalyst activity amount to be below a certain value (Δb*=10), it can be used even if images are left indoors for 2 months to several months or more. , Bk, which does not cause discoloration.

Next, binders used in the present invention include, for example, water-soluble polymers such as vinyl alcohol, starch, oxidized starch, cationized starch, casein, carboxymethyl cellulose, gelatin, and hydroxyethyl cellulose, and SBR latex, MBR latex, and vinyl acetate emulsion. or a mixture of two or more water-dispersible polymers such as acrylic emulsions.

Furthermore, in the present invention, a dye fixing agent (waterproofing agent), a fluorescent sun increasing agent, and a surfactant are added to the coating layer as necessary.

It may also contain antifoaming agents, pH adjusters, fungicides, ultraviolet absorbers, antioxidants, and the like.

A bar coater, a blade coater, or an air knife coater □ can be used to coat the aqueous coating liquid obtained by mixing the above-mentioned materials onto the above-mentioned substrate.

All conventionally known methods such as reverse roll coater, gate roll coater and size press method can be used.

In the present invention, the preferred dry coating amount of the aqueous coating liquid is 0.5 to 8 g/rrf. That is, since the coat layer itself acts as a catalyst, it is preferable that the coating amount of the coat layer itself be small in order to lower the catalytic activity. Further, if the coating amount exceeds 8 g/rd, the coating layer becomes brittle and the problem of powder falling off occurs. If the coating amount is less than 0.5 g/r&, there are problems such as a decrease in ink absorption and feathering in which the ink bleeds along the base paper fibers exposed on the surface.

Therefore, the recording agent of the present invention provides a coating layer on a base paper having a high Steckigt sizing degree, such as general high-quality paper, and
Rather than a type in which all the ink is absorbed and retained by the coat layer, it is preferable to use a type in which the coat layer is provided on a low-sized base paper so that even the base paper absorbs and retains the ink.

In this case, the preferred size degree of the recording material of the present invention is 0 to 15.
Seconds. When the Steckicht sizing degree exceeds 15 seconds, the ink absorbency of the coat layer is significantly reduced in the above-mentioned coating amount range.

In addition, in the case of the above-mentioned base paper absorption type recording paper, the properties of the base paper are also an important factor.

The base material used in the present invention is mainly composed of fibrous substances and fillers. It is constructed as such and is abridged by a conventionally known method.

Specific examples of the filler used in the present invention include clay, talc, kaolinite, titanium oxide, calcium carbonate, etc. used for boat fishing, but in terms of printing quality such as ink absorption, shape of the obtained dots, bleeding rate, etc. Preferably, calcium carbonate is used.

These fillers have an ash content of JIS-P-8128, 2
% or more, preferably 2 to 15%, more preferably 4 to 1
One of the requirements for realizing the present invention is that the content is in the range of 0%.

According to the findings of the present inventors, in particular, the bleeding and dot shape of ink droplets adhering to the recording material are greatly affected by the ash content of the base paper, and when the ash content is less than 2%, the adhering ink droplets are However, since the ink droplets bleed along the fiber direction of the surface of the base paper, the shape of the dots is poor and the ink droplets bleed more than necessary.

Also, if it exceeds 15%, the recording material itself will not be stiff (
As a result, there is a risk that powder may fall off from the base paper, which is not preferable.

In addition to these materials, the base paper of the present invention is made using conventionally known paper making aids, sizing agents, 1 retention improver, 9 paper strength enhancers, etc., as necessary.

Further, after the aqueous coating liquid is applied to the base paper, a conventional drying method such as a hot air drying oven is used.

It is dried using a heat drum or the like to form a recording material.

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

Yellow (Y) and magenta (M) are printed using the inkjet recording method on the recording material having the above structure.

According to the recording method of recording with water-based inks of multiple colors such as cyan (C) and black (Bk), the resulting images do not undergo discoloration indoors, and recorded images with excellent storage stability can be obtained.

In the method of the present invention, the ink itself applied to the above-mentioned specific recording material by the inkjet recording method may be a known ink, such as a direct dye.

These are water-soluble dyes represented by acid dyes, basic dyes, 1 reactive dye, 1 food coloring, etc., and are particularly suitable as inks for inkjet recording methods, and when combined with the above-mentioned recording materials, they improve fixation, color development, Clarity.

For example, C, 1, Direct Black 17, 19, 32, 51, 71, 10 are preferable for providing an image satisfying stability, light fastness, and other required properties.
8°C, 1, Direct Blue 6.22, 25, 71,
86, 90, 106°C, 1, Direct Red 1, 4
．． 17, 28.83C, 1, Direct Yellow 12,
Direct dyes such as 24, 26, 86, 98, 142C, 1, Direct Orange 34, 39, 44, 46, 60C, 1, Direct Violet 47.48C, 1, Direct Brown 109 C, 1, Direct Green 59, C , 1, acid black 2, 7, 24, 26, 31,
52,63゜112.118 C,1, Acid Blue 9.22,40,59,93,
102,104゜113.117,120,167.2
29,234C,1, Acid Red 1,6,32,3
7,51,52,80,85゜87.92,94,11
5,180,256,317,315C,1, Acid Yellow 11.17,23,25,29,42°61.
Acidic dyes such as 71 C,1, Acid Orange 7.19 C,1, Acid Violet 49 are preferred; others include: C,1, Basic Black 2 C,1, Basic Blue 1.3, 5, 7, 9, 24 ，
25, 26° 28.29 C, 1, Basic Red 1, 2, 9, 12, 13, 1
4,37C,1, Food Black 1.2, etc. can also be used.

The above examples of dyes are particularly preferable for inks applicable to the recording method of the present invention, but dyes for inks used in the present invention are not limited to these dyes.

Such water-soluble dyes are generally used in a proportion of about 0.1 to 20% by weight in conventional inks, and this proportion may be the same 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 preferred is a mixed solvent of water and a water-soluble organic solvent, and a water-soluble organic solvent is particularly suitable. It contains a polyhydric alcohol which has the effect of preventing ink from drying. Further, the water is not ordinary water containing various ions (it is preferable to use deionized water).

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

In addition to the above-mentioned components, the ink used in the present invention may optionally contain a surfactant, a viscosity modifier, a surface tension modifier, and the like.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples. In the text, parts or percentages are based on weight unless otherwise specified.

A base material was prepared as follows.

C, S, F 380ml L as raw material pulp
BKP 95th division.

Using 5 parts of NBKP of C, S, F410mf, calcium carbonate (trade name Niscalon #20) was used as a filler.
(manufactured by Sankyo Seifun), neutral sizing agents (A, Ni, D Dick),
(manufactured by Percules) and cationized starch to obtain low size base paper A with an ash content of 8%.

A coating liquid with the following composition was applied on base paper A with a dry coating amount of 5 g/
The recording material of the present invention was obtained by applying the coating using a Nakabar coater method so as to obtain a RD and drying at 100° C. for 5 minutes.

(Coating liquid composition) Synthetic silicate (Mizukanite P-1 manufactured by Mizusawa Chemical)*'
10 parts fine powder silica (Thyroid 72 manufactured by Fuji Davison) 5 parts cationized hydroxyethyl cellulose (manufactured by Leoguard GP Lion) 10 parts cationic resin (FAA-1C3 manufactured by Nittobo)
1 part magnesium chloride reagent
1 part water
300 parts*l: Mizuriki Knight P-1 contains about 30% MgO, BET specific area 600
It is a synthetic silicate with ~700 rrr/g.

Example 2 A sample was prepared in the same manner as in Example 1 except that the following coating liquid was used.

(Coating liquid composition) Synthetic silicate (Mizukanite P-3 manufactured by Mizusawa Chemical) Wood 2
10 parts fine powder silica (Syroid 72 manufactured by Fuji Davison) 5 parts cationic SBR latex (JSR
0652 Japan Synthetic Rubber) solid content conversion>
5 parts Hydroxyethylcellulose (HECAH-15 manufactured by Fuji Chemical) 0.5 parts Water
2
00 parts A 5% isopropanol solution of an organic aluminum compound (manufactured by Aluminum Chelate D Yoken Fine Chemical Co., Ltd.) was applied in a dry coating amount of 0.5 on the sheet obtained as above.
Coating with a bar coater method so that g/rrr is 11
The recording material of the present invention was prepared by drying at 0° C. for 5 minutes.

*2: Mizuriki Knight P-3 is a synthetic silicate containing about 30% MgO and having a BTE specific surface area of 500 to 600/g.

Example 3 A recording material of the present invention was obtained in the same manner as in Example 1 except that the following coating composition was used.

(Coating liquid composition) Synthetic silicate (Mizuriki Night P-1 manufactured by Mizusawa Chemical)
9 parts fine powder silica (Thyroid 72 manufactured by Fuji Davison) 9 parts cation-modified polyvinyl alcohol (PVA-C-118-2A manufactured by Kuraray)
12 parts cationic resin (#AA-1O3 manufactured by Nittobo)
2 parts magnesium chloride (reagent)
2 parts water
200 parts Example 4 A sample was prepared in the same manner as in Example 1 except that the following coating liquid was used.

Synthetic silicate (Mizuriki Night P-1 manufactured by Mizusawa Chemical)
5 parts fine powder silica (Thyroid 72 manufactured by Fuji Davison) 10 parts cation-modified polyvinyl alcohol (PVA-C-118-2A manufactured by Kuraray)
12 parts cationic resin (FAA-100 manufactured by Nittobo)
2 parts water
200 parts A thioether type antioxidant (MARK
LX-45 manufactured by Adeka Argus Chemical Co., Ltd.) was applied using a bar coater method at a dry coating weight of 0.5 g/i.
The recording material of the present invention was obtained by drying at 110° C. for 5 minutes.

Example 5 As a pigment, a synthetic silicate (Mizuriki Night P-1 manufactured by Mizusawa Chemical Co., Ltd.) was cationized by the method shown below.

Octadecyl dimethyl [3-0
Add 30 parts of a 1.5% methyl cellosolve solution of rimethoxysilyl)propyl]ammonium chloride (silane coupling agent AY43-006 manufactured by Torre Silicone) and dry at 110°C for 20 minutes to form a cation-treated silica B.
I got it.

A recording material of the present invention was obtained in the same manner as in Example 1 except that the following coating liquid was used.

Cation treated silica B
18 parts cation-modified polyvinyl alcohol (PVA-C-118-2A manufactured by Kuraray)
10 parts cationic resin (FAA-100 manufactured by Nittobo)
1 part water
200 copies Example 6 A recording material of the present invention was prepared in the same manner as in Example 1 except that the following coating liquid was used.

Synthetic silicate (Fluorite R manufactured by Tokuyama Soda) 1 book
6 parts cation modified polyvinyl alcohol water
200 parts*3 General formula 2CaO* 3Si02 ・
m5i02 fist nH2Q (1<m<2.2<n<3
), is a special silica-based pigment with a BET specific surface area of 100 to 130 rrr/g, and is a highly liquid-absorbing pigment with a petal-shaped crystal structure.

Example 7 A sample was prepared in the same manner as in Example 1 except that the following coating liquid was used.

Fine powder silica (made by Solex CM Tokuyama Soda) 10 parts Fine powder silica (Thyroid 72 made by Fuji Davison)
5 parts cation-modified hydroxyethyl cellulose (manufactured by Leogard GP Lion) 8 parts cationic resin (FAA-100 manufactured by Nittobo)
1 part water
200 parts of thioether type antioxidant (MARK LX-457
(manufactured by Deka Argus Chemical) in a dry coating amount of 0.5g/rd.
The recording material of the present invention was obtained by coating with a bar coater method and drying at 110° C. for 5 minutes.

Comparative Example 1.2 A comparative recording material was obtained in the same manner as in Example 1 except that the following coating liquid was used.

(Coating liquid composition) Comparative example 1 Fine powder silica (Syroid 72 manufactured by Fuji Davison)
12 parts polyvinyl alcohol (PVA-110 manufactured by Kuraray) 6 parts water
10.0 parts Comparative Example 2 Synthetic silicate (Mizuriki Night P-1 manufactured by Mizusawa Chemical) 12 parts Polyvinyl alcohol (PVA-110 manufactured by Kuraray)
6 parts water
100 copies Comparative Example 3 General high-quality paper Kinyo (trade name: Sanyo Kokusaku Pulp) as the base material
A comparative recording material was obtained in the same manner as in Comparative Example 1 except that .

Comparative Examples 4 to 6 Two types of commercially available inkjet coated paper, NM paper (manufactured by Mitsubishi Paper Mills) and FC-3 paper (manufactured by Jujo Paper Mills) were used as recording materials for comparison (Comparative Examples 4.5) and general PPC paper (
Canon NP paper) was used as it was as a recording material for comparison (Comparative Example 6).

The suitability for inkjet recording of the above recording material is Y, M, and C inkjet heads equipped with 128 nozzles at a nozzle interval of 16 nozzles per 1 mm.

Using an inkjet printer (a) that has 4 Bk colors and an inkjet printer (b) that has 24 nozzles at 8 intervals of 1 mm for 4 colors, inkjet recording was performed using ink with the following composition and evaluated. .

◎Ink composition (1) Dye 2 parts diethylene glycol 25 parts water
73 parts Dye (Ink I) Y: C, 1, Direct Yellow 86M: C,
1, Acid Red 35 C: C, 1, Direct Blue 199 8: C, 1, Direct Black 17 ◎ Ink composition (
n) Dye 2 parts diethylene glycol 20 parts polyethylene glycol 820
0 15 parts n-methyl-2-pyrrolidone 10 parts Water 53 parts Dye (ink ■) Y: C, 1, Acid Yellow 42M: C, 1
, Acid Red 92 C: C, 1, Direct Blue 86 Bk: C, 1, Direct Black 51 ◎ Ink composition (
m) Ink composition (n) used C.1 and Food Black 2 as dyes.

Evaluation was performed on the following items. The results are shown in Table 1.

Measurement and evaluation method (1) BHT as an index for measuring the catalytic activity of the coating layer
The amount of discoloration Δb of RHT2 in the two-spot test was measured by the method described above.

(2) Ink absorbency was evaluated using an inkjet printer (a) using ink (I).

In the recorded image, where the two-color ink is mixed, the line thickness is worse than the monochrome area: ×, where there is no line: ○, where it is slightly thicker: △
And so.

(3) Image clarity: When printed using ink (I) and printer (a), an image with clear edges without feathering etc. was rated as ○, and another with clear edges was rated as X.

(4) Indoor storage stability (1) is ink (I), (■).

A color image was formed using the printer (a), hung on the wall of the office, and left for 6 months. Comparing the same image with an image similarly saved in the 6-month clear pocket file, those with no noticeable discoloration were rated ○, those with severe discoloration were rated ×, and those with moderate discoloration were rated △.

(5) Indoor storage stability (2): A Bk solid pattern was printed using ink (■) and a printer (b), and as in (4), it was hung on the wall of an office and left for 2 months. The difference ΔE*ab between the chromaticity of this image and the chromaticity of the image immediately after printing was determined, and indoor discoloration was evaluated.

(d) Color properties are yellow (Y) and magenta (M) of printer (a) using the above ink (1).

The saturation of each solid printed portion of cyan (C) was determined using a high-speed color analyzer CA-35 (Murakami Color Science Model).

(7) Steckicht sizing degree was determined by a method based on JIS-P-8128.

Table 1 Example (1) Spot test (Δb 4.3 2.1 4.3
5.8 3.0 2.6 4.1 (2) Ink absorption ○ ○ ○ ○ O△ ○(
3) Image clarity ○ ○ ○ 0000 (4) Indoor storage stability (I) ○ ○ ○ ○ 000 (II)
○ O○ ○ ○ ○ ○ (5) Indoor storage stability (m
) (ΔEab 6.2 2.3 7.6
9.6 3.6 2.4 8.8 (6) Color Y 70.271,068.365.269.8
70.171.0M 67.0 66.3
66.0 64.3 66.7 67.2 65.2C
59,157,257,155,05B, 4 58.2
59.7 (7) Steckicht size degree 7 seconds 5 seconds
7 seconds 8 seconds 5 seconds 10 seconds 5 seconds I No. 2 1.5 Table 1 Comparative Example (1) Spot test (Δb 30.4 1.7 28.2
54.7 50.2 1.2 (2) Ink absorption
0 0 × ○ O × (3) Image clarity ○ ○ X O○ × (4) Indoor storage stability (■) × ○ ××× ○ (II) x Q x x
x ○(5) Indoor storage stability (m) (ΔEabtsu 25.0 1.8 22.3
33.2 30.9 0.8 (6) Chromaticity Y
70.054.361.070.169.648.1
M 66.4 57.1 59.4 66.
9 67.1 50.3C56,146,252,15
8,056,038,3(7) Steckicht size degree
6 seconds 5 seconds 28 seconds --27 seconds [Effect of the invention] Since the recording material of the present invention contains a large amount of pigment with high ink absorption ability in the surface layer, the probability that ink droplets are captured and absorbed by the pigment is low. Therefore, ink bleeding and diffusion are suppressed, and as a result, the dot shape is improved and exhibits excellent ink absorption, resolution, color development, and color density.

Furthermore, the present invention has the suitability for inkjet recording as a coated paper as described above, but also has fewer problems in image preservation peculiar to coated paper. This method eliminates the problem of indoor discoloration when the resulting images are stored for one to several months in an office wall or drawer out of direct sunlight.

Claims (8)

[Claims] (1) A porous ink-receiving layer comprising a base material and a pigment and a binder provided on the base material, and [4,4'-methylene-bis-2,6-(di-tert-butylphenol)] (
BHT_2) A recording material characterized by having Δb^* of 10 or less in a spot test. (2) The recording material according to claim 1, wherein Δb^* as determined by the spot test is 7 or less. (3) The recording material according to claim 1, wherein the pigment is a silicon-containing pigment. (4) The recording surface of the ink receiving layer is made of Mg, Ca, Zn.
The recording material according to claim 1, which contains a silicon-containing pigment containing 0.1% by weight or more of a metal selected from the group consisting of , Ba, and a cationic substance. (5) The recording material according to claim 1, wherein the recording material has a Steckigt sizing degree according to JIS-P-8122 in the range of 0 to 15 seconds. (6) The base material is made of a fibrous substance and a filler, and
The recording material according to claim 1, wherein the ash content according to P-8128 is in the range of 2 to 15% by weight. (7) The recording material according to claim 6, wherein the filler is calcium carbonate. (8) In a recording method in which recording is performed by applying droplets of ink containing an acid dye and/or direct dye to a recording material, the recording material is a base material and a porous ink provided on the base material. has a receptive layer, and [4,4'-methylene-bis-2,6-(
di-tert-butylphenol)] (BHT_2) A recording method characterized in that Δb^* is 10 or less according to a spot test.