JPS6157380A - Ink jet recording medium - Google Patents

Abstract

PURPOSE:To enhance water resistance, light resistance or the like of water base ink images, by incorporating a porous inorganic pigment, a cationic resin and a difficultly soluble magnesium compound in an ink jet recording medium. CONSTITUTION:A porous inorganic pigment, a cationic resin and a difficultly soluble magnesium compound are dispersed or dissolved in water to prepare a coating liquid. The coating liquid is applied to a base such as a paper and a thermoplastic resin film by a coater such as a sprayer, followed by drying to produce the ink jet recording medium. Images are recorded on the recording medium by using a water base ink containing a water-soluble dye. The porous inorganic pigment may be synthetic silica, hydrated aluminum oxide or the like, and the cationic resin is, for example, a water-soluble resin containing a quaternary ammonium salt. The magnesium compound may be MgO, Mg(OH)2 or the like.

Description

Detailed Description of the Invention (5) Industrial Application Field This description relates to a recording medium recorded using ink, and in particular, the density of images and characters recorded on the medium is high, and the absorption and recording properties are high. This invention relates to an inkjet recording medium with excellent image storage stability.

CB) Prior art and its problems The inkjet recording method uses various operating principles to fly minute droplets of ink and make them adhere to a recording medium such as paper to record images, characters, etc. high speed,
It has features such as low noise, easy multicolor printing, great flexibility in recording patterns, and no need for development or fixing, making it suitable for elegant applications as a recording device for various shapes and color images, including kanji. It is rapidly becoming popular. Furthermore, images formed using the multicolor inkjet method can produce records that are comparable to multicolor printing using the corrugated plate method or printing using the color photographic method, and are ideal for applications that require fewer copies to be produced. Since it is cheaper than photographic technology, it is being widely applied to the field of full-color image recording.

Efforts have been made in terms of equipment and ink composition to use high-quality paper and coated paper, which are used for ordinary printing and post-recording, as the recording medium used in this inkjet recording method. However, as the performance of inkjet recording apparatuses increases, such as higher speeds, higher definitions, and full-color inkjet recording apparatuses, and their applications expand, more advanced characteristics are now required of recording media. In other words, the recording medium must have a high ink dot density, a bright and colorful color tone, ink absorption is fast, the diffusion towards the ink is not unnecessarily large, and the periphery is smooth and does not become blurred. . Furthermore, it is required that the resistance of the dye when the recorded image is exposed to ultraviolet rays, oxygen in the air, or water be not reduced, but preferably increased.

Several proposals have been made to solve these problems. For example, Japanese Patent Application Laid-Open No. 52-53012 discloses an inkjet recording paper made by moistening a low-sized base paper with a paint for surface treatment.
No. 113 discloses an inkjet recording paper in which a sheet containing a urea fraction formalin resin powder is impregnated with a water-soluble polymer. These pattern paper type inkjet recording papers are
Ink absorption is quick, but the drawbacks are that the periphery of the dots tends to become blurred and the dot aptitude is low.

Further, JP-A-55-5830 discloses an ink-jet recording paper in which an ink-absorbing coating layer is provided on the optical surface of the support, and % JP-A-55-51583 discloses a non-containing pigment as a pigment in the coating layer. An example using colloidal silica powder is disclosed, and furthermore, JP-A-55-11829 discloses an example of smear paper using a two-layer structure with different ink absorption speeds. These coated paper-type inkjet recording papers are improved over general paper-type inkjet papers in terms of dot diameter, dot shape, dot a degree, and color tone. Most of the inks applied to the media are water-based inks that use water-soluble dyes, and if an image formed on the recording medium is exposed to water, the dye will dissolve again and ooze out, reducing the value of the recorded material. There is a problem that significantly reduces the

Therefore, in order to improve this drawback, for example,
No. 53591 discloses an example in which a metal water-soluble salt is applied to the recording surface, and JP-A-56-84992 discloses an example of a recording medium containing a polycationic polymer electrolyte on the surface.
JP-A No. 55-150396 describes a method of applying a water-resistant agent that forms a lake with the dye in the ink after inkjet recording, and furthermore, JP-A No. 56-58869 discloses
Each of the above publications discloses a method of making a recording sheet coated with a water-soluble polymer waterproof by insolubilizing the water-soluble polymer after inkjet recording.

However, with these methods of making water resistant, the effect of making water resistant may be diminished, or the water resistant agent may react with the dye, reducing the shelf life of the dye, resulting in insufficient water and light resistance. It was quite difficult to achieve both.

0 Purpose of the Invention The present invention improves inkjet suitability as described above and also provides excellent water resistance and light resistance of water-based ink images, particularly light resistance and discoloration resistance of water-soluble black dyes and/or water-soluble magenta dyes. The purpose is to provide a recording medium with improved performance.

Q) Structure and operation of the invention In other words, the present invention provides an inkjet recording medium in which a recorded image is formed using an aqueous ink containing a water-soluble dye. This is an inkjet recording medium containing a magnesium compound.

The porous inorganic pigment referred to in the present invention is made by aggregating primary particles of synthetic silica or aluminum oxide to form a dry powder with an average secondary particle size of 0.5 μm to 30 μm. When synthesized in aqueous solution from water-living Ig, hydric aluminum oxide,
The secondary particles have a size of several meters to several hundred micrometers and are self-agglomerating, so they must be crushed and classified after drying, or they may be dried using a spray dryer or the like to achieve the intended purpose. By adjusting the particle size to a certain level, a porous inorganic pigment can be obtained.

In addition, if synthetic silica or water-use aluminum oxide is a fine powder of 1 μm or less, it can be dispersed in water, added with a binder or adhesive, dried, crushed, and classified, or spray-dried with a spray dryer. By doing so, it is also possible to obtain a porous inorganic pigment having an average secondary particle diameter of 0.5 μm to 30 μm.

Furthermore, in order to form fine water-dispersed substances such as colloidal silica and colloidal alumina into particles with a size of 0.5 μm or more, it is necessary to use a fine particle* suspension as shown in U.S.P-3,855,172. By producing a urea-formalin resin or the like in turbid water and adjusting the production conditions, a porous inorganic pigment granulated to a desired secondary particle size can be obtained.

The synthetic silica referred to in the present invention refers to dry process silica produced by thermal decomposition of silicon tetrachloride, so-called white carbon such as double decomposition precipitation products produced by sodium silicate acid, carbon dioxide, ammonium salt, etc., and produced by sodium silicate acid. Silica sol obtained by thermal decomposition or passing through an ion exchange resin layer, or colloidal silica obtained by heating and aging this silica sol, turns silica sol into gold gel, and by changing the formation conditions, primary particles ranging from several millimicrons to several tens of millimicrons can be produced. Using silica gel as a three-dimensional secondary particle with siloxane bonds, as well as silica sol, sodium silicate, sodium aluminate, etc. as starting materials,
It refers to synthetic silicon compounds mainly composed of silicon dioxide, such as so-called synthetic molecular sieves produced by heating at temperatures between 120°C and 120°C.

The porous water-containing aluminum oxide referred to in the present invention is
Neutralizing metals or ions from aqueous solutions of water-soluble aluminum compounds, such as aluminum salts such as aluminum sulfate, aluminum nitrate, aluminum chloride and the like, or alkali metal salts of aluminates, such as sodium or potassium salts of aluminate, or both. A gel obtained by ion exchange using an exchange resin is called a hydrogel, which is usually washed to remove salts and then dried to form a xerogel. By using spray drying or the like for drying, it can be made into a powder suitable for blending into a coating solution.

It is also possible to make a powder by drying it in block form and then crushing and classifying it. The water-containing oxides thus formed after drying have most, if not all, of their free water removed,9 and usually some of their bound water, with most of their structure intact. It sets irreversibly and becomes a porous solid. The pore diameter of the porous solid thus obtained usually ranges from 50A to 5000A, and when the secondary particles are dispersed in water, the surface charge becomes a positive charge (cationic).

In the present invention, the above porous inorganic pigment can also be used in combination with the following inorganic or organic pigments. In this case, the porous inorganic pigment is used in an amount of 20% by weight or more, preferably 40% by weight or more of the total pigment. Examples of inorganic pigments that can be used in combination include light calcium carbonate, heavy calcium carbonate, and kaolin (
Merck, calcium sulfate, barium sulfate, titanium oxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, cane earth, calcium silicate, magnesium silicate, synthetic amorphous silica, aluminum hydroxide, Examples of white pigments such as alumina and lithopone and atomized materials include styrene plastic pigments, acrylic plastic pigments, microcapsules, and urea resin pigments.

The cationic resin referred to in the present invention refers to a hexamer, oligomer, or polymer that dissociates and exhibits cationic properties when dissolved in water, preferably having a quaternary ammonium group, and particularly preferably having a quaternary ammonium group. It refers to a compound having a structure represented by the following general formulas (I) to (2).

(1) Cl40112- CH-00ni-i (
0112). .

几2 In the formula, R1, R, and R3 represent an alkyl group, m represents 1 to 7, n represents 2 to 10, and Y represents an acid group.

(11) ~GV)', -+ R1, 1t2b knee O in the formula
H3, -cx-t, -aH3, -0H2-CH2-OH
XY represents an acid group.

(V) Polyalkylene polyamine dicyandiamide ammonium salt Tsumugi compound Compounds represented by the general formula (1) are, for example, Nalpoly-607 (manufactured by Nalco Chemical Co., Ltd.) Rirui or Polyfix 601 (manufactured by Showa Tsutsuboshi Co., Ltd.) I can't stand it.

The compounds represented by general formulas (II) to Zeng are polydiallylamine derivatives, which are obtained by cyclization N-combination of diallylamine compounds, Percoll 1697 (Allied Colloid Co., Ltd.), C1at Floe (Calgon Corp)
, PAS (Nitto Boshi Co., Ltd.), Neofix RPD (manufactured by NICCA Chemical Co., Ltd.), and the like.

Further, the compound represented by the general formula (V) can be, for example, Neofix ILP-70 (manufactured by Parasol Chemical Co., Ltd.).

The content of the cationic J fat represented by these general formulas (1) to (to) is usually 0.1 to 4? /-1 preferably 1.
2-2? /m' to use.

The poorly soluble magnesium compound in the present invention refers to a magnesium compound such as magnesium oxide, magnesium hydroxide, magnesium carbonate, magnesium calcium carbonate, magnesium silicate, magnesium oxalate, etc., which has a solubility in water of 1% or less at room temperature. These double salts are also included. Preferably magnesium oxide, magnesium hydroxide,
It is magnesium carbonate. The content of these poorly soluble magnesium compounds in the recording medium ranges from 0.001 to 10%, preferably from 0.01 to 5%. /lr? , more preferably used with n1α concave of 0.1 to 3F/-.

In order to incorporate these porous inorganic pigments, cationic resins, and poorly soluble magnesium compounds into recording media, they are dispersed or dissolved in water, and if necessary, commonly used adhesives, inorganic pigments, and other additives are added. is added to form a coating solution, which is coated and dried using a conventional coating device such as a size press device, a Kate roll coater, an air knife coater, a blade coater, or a spray device. Examples of adhesives include oxidized reduced powder, etherified starch-carboxymethyl cellulose, cellulose derivatives such as hydroxyethyl cellulose, casein, gelatin, soybean protein, polyvinyl alcohol and its V5 conductor, maleic anhydride fat, and ordinary stainless steel. Conjugated diene polymer latex such as butadiene copolymer, methyl methacrylate-butadiene copolymer, etc., acrylic polymer latex such as polymer or copolymerization of acrylic acid ester and methacrylic acid ester, ethylene acetate vinyl copolymer, etc. Vinyl yarn polymer latex, or each of these a [combined with functional group-containing monomers such as carboxyl groups, self-supporting polymer latex, thermosetting synthetic resin systems such as melamine resin, urea resin, etc. Water-based adhesives such as, polymethyl methacrylate, polyurethane resin, unsaturated olopolyester resin, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, alkyd resin and other composite resin thread adhesives are used alone or in combination with a plate. These adhesives are used in an amount of 2 to 120 parts, preferably 5 to 50 parts, per 100 parts of the pigment, but the ratio of 7 is particularly limited as long as the amount is sufficient to bind the pigment. It's not a thing. However, if 120 parts or more of the adhesive is used, the adhesive film formation reduces the void structure or makes the voids extremely small, which is not desirable.

Other additives include pigment dispersants, thickeners, flow modifiers, antifoaming agents, foam inhibitors, mold release agents, foaming agents, penetrants, colored dyes, colored pigments, fluorescent whitening agents, and ultraviolet light. Absorbents, antioxidants, preservatives, anti-spill agents, waterproofing agents, etc. can also be blended as appropriate.

As the support, a sheet material such as paper or a thermoplastic resin film is used. Paper with no sizing agent added or with appropriate sizing may or may not contain filler.

In addition, in the case of thermoplastic films, polyester, polystyrene, polyvinyl chloride, polymethyl methacrylate,
A transparent film made of cellulose acetate, polyethylene, polycarbonate, etc., or a white opaque film filled with white pigment or made by fine foaming is used. Examples of white pigments to be filled include titanium oxide, calcium sulfate,
Calcium carbonate, silica, clay, Merck, sensitized zinc, etc. can be used.

1. It is also possible to use so-called laminated paper, which is made by pasting these resin films on the surface of paper or by processing it with molten resin. A subbing layer or corona discharge processing may be applied to improve the adhesion between the resin bottom (3) and the ink receiving layer.

A sheet simply coated on a support can even be used as a recording sheet according to the present invention; for example, it can be heated with a super calender, cross calender, etc.)J
ID/or under pressure - between one lunip? It is also possible to provide surface smoothness through the process. In this case, the degree of processing may be limited because excessive processing by supercalendering will result in a total decrease in absorbency due to the voids formed between the nine particles.

The water-based ink referred to in the present invention includes the following colorant and liquid medium,
Fill with recording liquid consisting of other calorific additives.

As the coloring agent, direct dyes, acid dyes, basic dyes, reactive dyes, or water-soluble dyes such as food colorings are preferably used.

For example, as a direct dye, 0.1. Direct Black 2.4.9.11
．． 14.17.19.22.27゜32, 36.38.
41.4 & 49.51.56゜62, 71.74.7
5.7? , 78.80.105, 106.107.1
08.11λ113,117, 132.146.154
．． 1940.1. Direct Yellow 1.2
．． 4.8.11.1&24.26.27゜28,33
．． 34.39.41.4 s 44, 48° 50, 51.5
EL 72185.86.87. , 88°9 & 100
．． 110 0.1. Direct Orange 6.8110
．． 26.29.39.41.49.51.102 0.1. Direct Red 1.2.4.8.
9.11.1 & 17.20.23, 24.28.31
．． 33.37.39.44゜46, 47.48.51.
59.6&6 formula 71% formula% 0.1 as an acid dye. Ac1d Black 1.2.7.16.
1? , 24.26.28.31゜41, 48.52.
5B, 60.63.9'4.107°109.114
118.119.121.12Z131, 155.15
6 0.1. Ac1d Yellow 1.3.4.7.
11.12.13+14.17゜18, 19.23.2
5.29.34.36.3&40.41.4 44.
49. 53. 55. 59°61,71,72,
76.7 & 99,111゜114.116,122
, 135, 161, 172°0.1. Ac1d Or
ange 7.8. 10. 33. 56.64
0.1. Ac1d Red 1. 4. 6.
8. 13. 14. 15. 18. 19°21
, 26. 27.30. 32.34. 35. 3
7゜40.42,51,5s 54.57.80. 8
2゜83.85,87,88,89,9λ 94,97
゜106.108,110,115,119,129゜131.133,134,135,154,155゜1
72,. 176.180,184,186,187゜2
43.249,254,256,260,289゜31
7.318 0.1. Ac1d Violet 7. 11.
15. 34. 35.41.43.49°75°C, 1, Ac1d Blue 1.7. 9.
22. 23125. 27. 29.40°41,
43. 45.49. 51. 53. 55. 56
゜59, 62. 78. 80.81. 83. 90
．． 92°93.102,104,111,113,1
17°120.124, 126, 145, 167.17
1°175.183,229,234,2360.1.
Ac1d Green 3. la 19.27
．． 41.9.16.20.250.1. Ac1d B
raun 4.14 0.1 as a basic dye. Ba5ic Blaclc λ80.1. B
aaic Yellow 1.2.11.12.14
．． 21.32.360.1. Ba5ic Orange
2.15.21.220.1. Baaic
d1. 2. 9. 12. 13. 37
0.1. Baaic Violet 1+ 3.7.
10.140.1. Baaic Blue 1.3
．． 5.7.9.24.25.26.28.290.1.
Baaic Green 1.40.1. Baaic
Braun 1.12 reactive dyes include: 0.1. Reactive Black 1.3.5.
6.8.121140.1. Raactlve Yell
low 1.2.3.13.14.15.170.1.
Reactive Orange 2. 5. 7.
16. 20. 240, I, 几active
Red 6.7.11.12+ 15.17.21.
23°24, 35.36.42.63.66 0.1. Reactive Violet 2.45
+ a19+0.1. Reactive Blue
2.5.7.12.13.14.15. ．． 17°18,
19. 20. 21. 25. 27.28°37
, 3B, 40.41.71 0.1. Reactive Green 5,70
．． 1. Reactive Braun 1. 7+
16 Furthermore, as a food coloring material, 0.1. Food Black 20.1. F
ood yellow 3. 4. 50.1.
Food Red 2.3.7.9.14゜52
,87,92194.102,104,105,106
0.1. Food Violet 20.1.
Food Blue 1, 20.1. Food
Green 2. Examples include 3.

The liquid medium for the aqueous ink includes water and water-based organic solvents such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isobutyl alcohol,
Alkyl alcohols having 1 to 4 carbon atoms such as n-butyl alcohol, 5ee-fluor alcohol, tert-butyl alcohol, and isobutyl alcohol; amides such as dimethylformamide and dimethylacetamide;
Ketones or ketone alcohols such as acetone and diacetone alcohol; Ethers such as tetrahydrofuran and dioxane; Polyalkylene glycols such as polyethylene glycol and polypropylene glycol; 1,2.6-hexandriol, thiodiglycol, hexylene glycol,
Alkylene glycols having 2 to 6 alkylene groups such as diethylene glycol; lower alkyl ethers of polyhydric alcohols such as glycerin, ethylene glycol methyl ether, diethylene glycol methyl (or ethyl) ether, and triethylene glycol monomethyl ether, etc. It will be done.

Among these many water-soluble organic solvents, polyhydric alcohols such as diethylene glycol and lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl ether and triethylene glycol monoethyl ether are preferred.

Examples of other additives include P L-1 regulators, sequestering agents, antifungal agents, viscosity modifiers, surface strength modifiers, moistening aphrodisiacs, surfactants, and rust preventives. It will be done.

According to the present invention, when recording is performed using a water-based ink containing a water-soluble dye on a recording medium containing a porous inorganic pigment, a cationic resin, and a poorly soluble magnesium compound, the absorbency of the water-based ink is sufficiently reduced. The obtained r[! The density and color properties of the Il image are extremely excellent, and the image has sufficient water resistance, and usually there is almost no decrease in the light resistance of the image due to water resistance. This is simply a porous inorganic pigment,
This effect was completely unexpected from the combination of the effects of the cationic resin and the polyvalent metal ions, and as a result, its value as an inkjet recording medium was dramatically improved. The reason why these combinations are effective in improving inkjet suitability, particularly in improving the light fastness of water-soluble dyes, is not clear.

Measurement of inkjet suitability is done by the method below.

The color density was determined using Macbeth for images obtained by printing with cyan (0), magenta (b), yellow (7), and black (BA) inks using a Sharp inkjet color image printer (IO-700). Warts measured with a densitometer D514 were used.

Light resistance is determined by Canon inkjet printer (A-1)
210), the image area obtained by solid printing with 0, MXY, and BA inks was measured at 40°C and 60 inches using a xenon fade meter (manufactured by Suga Test Instruments, FAL-25X-HOL type). Irradiated for 40 hours at an illuminance of 41 W/- and measured the color density before and after irradiation using a Macbeth densitometer RD514.
The light resistance (residual rate) was expressed as the percentage of the color density after irradiation divided by the color 1 before irradiation.

Light resistance was measured using the same Canon inkjet printer by printing with OlM, Y, and BA inks, immersing the image area in running water at 30°C for 3 minutes, and measuring the density before and after immersion using a Macbeth densitometer RD514. The water resistance value was determined by dividing the concentration after immersion (7 il) by the concentration before immersion. The higher the value, the better the water resistance.

To speed up ink absorption, use a Sharp or Canon inkjet printer, and immediately after solid red printing (magenta + yellow) is printed (about 1 second), feed the paper and bring it into contact with a paper presser roll or your finger. Judgment was made based on whether dirt appeared or not.

Furthermore, the absorption capacity was determined by contacting a certain area of the ink-receiving layer with a 1/1 solution of polyethylene glycol (PEG boiled 400)/water at 20°C for 10 seconds, and removing the excess liquid with absorbent paper. The weight of the solution absorbed into the ink receiving layer was measured and the value calculated as grams per square meter was used.

(Smell) Examples The present invention will be described below with reference to Examples, but the present invention is not limited to these examples. In the Examples, parts and parts refer to parts by weight and parts by weight.

Example 1 r water bottom 370ml csf 0LBKP 80 parts, 2I
The water level is 410r! Ltcaf's Nl3KF 20 parts, talc for internal filling 10 parts, clay for internal filling 3 parts, rosin sizing agent Kneefor 100 (manufactured by Knife Kui Saichi Cures) 0
．． Part 5, Banod'2. ．． From a slurry consisting of 5 parts, a basis weight of 68 t/lr is produced using a Fourdrinier paper machine. A base paper of
An acidic coated base paper was produced by subjecting it to ri. The Steckigt size degree of this base paper was 33 seconds.

As a coating liquid, 100 parts of synthetic silica (Syroid 620, Fuji Davison 1A), a porous inorganic pigment, 90 parts of polyvinyl alcohol (PVA117, manufactured by Kuraray Co., Ltd.), a water-soluble resin, Polyfix 601 (Showa High School), a cationic resin. Manufactured by Mosunsha Co., Ltd.) 10 parts, magnesium hydroxide (Mg(0
1-1) 2) Prepare an aqueous coating solution with a concentration of 16, consisting of 10 parts, other antifoaming agents, and a small amount of fluorescent agent, and coat it on the acidic base paper using an air knife coater to give 92/R for 11!1.1 type. It was smeared and kept dry.

The recording paper of Example 1 was then printed through a super calendar. The solid smoothness of this recording paper was 105 seconds. Figure 1 shows the results of evaluating the suitability for inkjet for this charm.

Comparative Example 1 A recording paper of Comparative Example 1 was obtained in exactly the same manner as in Example 1, except that the aqueous dispersion of magnesium was removed from the coating solution of Example 1. The Beck smoothness of this recording paper was 102 seconds. Table 1 shows the results of evaluating the inkjet suitability of this recording paper.

Comparative Example 2 A recording paper of Comparative Example 2 was obtained in exactly the same manner as in Example 1, except that the cationic resin was removed from the coating solution of Example 1. The Beck degree of this recording paper was 99 seconds. The results of evaluating the inkjet suitability of this recording paper are shown in Figure 1.

Comparative Example 3 Same as Example 1 except that the porous amorphous paint (Silo/F Dro 20) in the coating solution of Example 1 was replaced with 100 parts of kaolin for coating (Ultra White-90 Engelhard Co., Ltd. 1). Recording paper of Comparative Example 3 was obtained in exactly the same manner.

The Beck smoothness of this recording paper was 250 seconds. Table 1 shows the results of evaluating the inkjet suitability of this recording paper.

Comparative Example 4 A recording paper of Comparative Example 4 was obtained in exactly the same manner as in Example 1, except that calcium chloride was used in place of magnesium hydroxide in the coating solution of Example 1. The Beck smoothness of this recording paper was 110 seconds. The results of evaluating the inkjet suitability of this recording paper are shown in Figure 1.

Examples 2 to 7 LBKP 80 parts of door water bottom 3707caf, jj water variation 4
00ml csfNBKP 20 parts, heavy calcium carbonate 1
3 parts, cationic starch 1 part, alkyl ketene dimer sizing agent (Burcon W manufactured by Disoku Hercules) 0.1
From a slurry consisting of 2 parts of polyalkylene polyamine epichlorohydrin resin and 0.4 parts of polyalkylene polyamine epichlorohydrin resin, base paper with a basis weight of 6,817 m'' is made using a Fourdrinier paper machine, and during paper making, oxidized starch is added to a solid content of 1.5 η with a size press machine during paper making. A neutral coated base paper was produced by adhering the base paper.The Steckigt sizing degree of this base paper was 35 seconds.

As the first coating liquid, Tsubu Seal LP is added to the synthetic silica.
A slurry prepared by dispersing 100 parts (manufactured by Nippon Silikani Gyo Co., Ltd.) in 400 parts of water was passed through a Visco mill to crush the aggregated particles, and 15 parts of polyvinyl alcohol was added to make a 4% 18% aqueous first coating solution, which was coated with an air knife coater. The above-mentioned neutral coated base paper was smeared so that the solid content was 13 η, and dried to prepare an undercoated paper. Next, 100 parts of synthetic silica (Syroid 74, manufactured by Fuji Davison Co., Ltd.) was used as a second coating liquid, 40 parts of polyvinyl alcohol (PVA117, manufactured by Kuraray Co., Ltd.) as a water-soluble resin, and Neofix RPD (Nicca Chemical Co., Ltd.) as a cationic resin. ) 7 parts, magnesium oxide (M
gO) respectively 1 part, 5 parts, 10 parts, 20 parts, 40 parts, 6 parts
0 parts, and a small amount of antifoaming agent to make a second coating with a concentration of 13%. 1. Apply the first coating solution on the undercoat paper using an air knife coater so that the solid content is 52/R. , dried. Then each Example 2 was passed through a super calender.
．． 3, 4.5.6.7. Table 2 shows the results of evaluating the inkjet suitability of this recording paper.

Comparative Example 5 A recording sheet of Comparative Example 5 was prepared in the same manner as in Examples 2 to 7, except that no magnesium oxide was added to the second coating liquid used in Examples 2 to 7. Table 2 shows the results of evaluating the inkjet suitability of this recording paper.

Example 8 Magnesium oxide in the Sono 2 coating solution used in Examples 2 to 7 was replaced with 10 parts of magnesium carbonate.Other Examples 2 to 7
A recording sheet of Example 8 was prepared in exactly the same manner as described above. Table 2 shows the results of evaluating the inkjet suitability of this recording paper.
Shown below.

Example 9 A recording sheet of Example 9 was prepared in exactly the same manner as in Example 9, except that the magnesium carbonate used in Example 8 was replaced with magnesium silicate. Table 2 shows the results of evaluating the inkjet suitability of this recording paper.

Comparative Examples 6 to 10 In place of magnesium carbonate used in Example 8, K
CI! , Na C1, Na2SO4, CaC1!2”2
Recording sheets of Comparative Examples 6, 7, 8, 9, and 10 were obtained in exactly the same manner as in Example 8, except that H20 and ZnCl2 were used. Table 2 shows the results of evaluating the printing suitability of these recording papers.

(g) Effects of the invention In Examples 1 to 9 containing a porous inorganic pigment, a cationic resin, and a sparingly soluble magnesium compound, the color density,
Excellent in water resistance, light resistance, and absorbency.
Comparative example that does not particularly contain a hardly soluble magnesium compound, 1.
4.5.6.7.8.9.10 has poor light fastness for black and magenta, but in this example, this point is almost improved, and it has extremely excellent properties as an inkjet recording medium. It is recognized that

Claims (4)

[Claims] (1) An inkjet recording medium in which a recorded image is formed using a water-based ink containing a water-soluble dye, characterized in that the recording medium contains a porous inorganic pigment, a cationic resin, and a sparingly soluble magnesium compound. Inkjet recording media. (2) The inkjet recording medium according to claim 1, wherein the porous inorganic pigment is at least one pigment selected from synthetic silica and hydrated aluminum oxide. (3) The inkjet recording medium according to claim 1 or 2, wherein the cationic resin is a water-soluble resin containing a quaternary ammonium group. (4) The magnesium compound is magnesium oxide (MgO
), magnesium hydroxide (Mg(OH)_2), and magnesium carbonate.