JPS6143593A - Ink jet recording medium - Google Patents

Abstract

PURPOSE:To enhance water resistance and light resistance of water base ink images and ensure high speed, high minuteness and excellent preservability, by incorporating a porous inorganic pigment, a cationic resin and magnesium sulfate and/or a double salt thereof in a recording medium. CONSTITUTION:A porous inorganic pigment, a cationic resin and magnesium sulfate and/or a double salt thereof are incorporated in a recording medium for recording images by using a water base ink comprising at least one water- soluble dye selected from direct dyes, acid dyes, reactive dyes, basic dyes and food dyes. The pigment is capable of enhancing a water base ink absorbing capability and enhancing color density and properties of color. The cationic resin functions to insolubilize the water-soluble dye in the ink and to enhance water resistance. Magnesium sulfate is capable of preventing the light resistance from being lowered due to the cationic resin or is capable of enhancing the light resistance.

Description

Detailed Description of the Invention (5) Field of Industrial Application The present invention relates to a recording medium recorded using ink, and is particularly concerned with recording media that are recorded on the medium and have a high density of fixed images and characters, and have excellent absorbency and recording properties. The present invention relates to a recording medium for storing images and prizes that has excellent image storage properties.

(B) Prior art and its problems The original inkjet method uses various operating principles to fly minute droplets of ink and attach them to a recording medium such as a piece of paper to record one image, one character, etc. But fast,
It has features such as low noise, easy multicolor f-hi, great flexibility in recording patterns, and no need for development or fixing, making it suitable for a variety of applications as a recording device for various shapes and color images, including kanji. It is rapidly becoming popular. Furthermore, the images released using the multicolor inkjet method are records that are comparable to multicolor printing using the plate-making method or printing using the color photographic method. In applications where the number of copies to be produced is small, the use of photographic technology is also inexpensive and is therefore being widely applied to the field of full-color image recording.

Efforts have been made in terms of equipment and ink composition to use the high-quality paper and coated paper used for regular printing and writing as the recording medium used in this inkjet recording method. However, as the performance of inkjet recording devices increases, such as higher speeds, Bf printing, and full-color inkjet recording devices, and the use of inkjet recording devices expands, advanced characteristics are now required of recording media. In other words, the recording medium must have high ink dot density, bright and colorful tones, and absorb ink quickly so that even when ink dots overlap, the ink will not run out. In addition, the lateral diffusion of the ink dots should not be unduly large, and the periphery should be smooth and not blurry.Furthermore, the recorded image should not be affected by the resistance of the dye when exposed to ultraviolet rays, oxygen in the air, or water. It is required to not allow it to occur, but preferably to enhance it.

Several proposals have been made in the past to try to solve all of 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 coating material for surface treatment.
In No. 113, urea-formalin resin powder was added internally and fc
An inkjet recording paper in which a sheet is impregnated with a water-soluble polymer is disclosed. These patterned paper-type inkjet recording papers absorb ink quickly, but
The drawbacks are that the periphery of the dot tends to be blurred and the dot density is low.

Further, JP-A-55-5830 discloses an inkjet recording paper in which an ink-absorbing coating layer is provided on the surface of the support, and JP-A-55-51583 discloses a pigment in the coating layer. In addition, Japanese Patent Laid-Open No. 11829/1982 discloses an example of a smearing paper using a two-layer structure having different ink absorption speeds. These coated paper-type inkjet recording papers are improved over general paper-type inkjet paper in terms of dot diameter, dot shape, dot degree, and color tone reproducibility, but it is difficult to apply them to these recording media. Many of the inks used are water-based inks that use water-soluble dyes, and if the image formed on the recording medium is exposed to water, the dye may dissolve again and ooze out, significantly reducing the value of the recorded material. There is a problem.

So, is this a drawback? In order to improve the
No. 53591 has an example of applying a metal water arch salt to the recording surface, and JP-A-56-84992 has a polycationic polymer electrolyte? Examples of the recording medium contained on the surface are also:
JP-A-55-150396 discloses a water-resistant agent that forms a lake with the dye in the ink after inkjet recording. The method of applying the method is further described in Japanese Patent Application Laid-Open No. 56-58869.

Is it a water-soluble polymer? Each method discloses a method of making the recording sheet water resistant by insolubilizing it in the water-soluble polymer after inkjet recording on the recording sheet.

However, these water resistance ratio methods have a weak effect on water resistance, or there may be some kind of reaction between the water resistance agent and the dye. Is it possible to reduce the shelf life of the dye and provide sufficient water resistance and light resistance? It was quite difficult to achieve both.

(C) Purpose of the Invention The present invention improves the water resistance and light resistance of an aqueous ink image in an inkjet recording medium in which an aqueous ink is jetted onto the recording medium to form a recorded image. Our goal is to provide high-speed, high-definition, and long-lasting sound recording media.

q Structure and operation of the invention That is, the present invention forms a recorded image using an aqueous ink containing at least one water-soluble dye selected from direct dyes, acidic dyes, reactive dyes, basic dyes, and food colorings. Does the recording medium contain a porous inorganic pigment, a cationic resin, and magnesium sulfate and/or its double salt? This is a characteristic inkjet recording medium.

In the present invention, the porous inorganic pigment has the ability to improve the absorption capacity of water-based ink and improve the brown density and color property. Does cationic resin insolubilize water-soluble dyes in water-based ink and make it water resistant? It has seven roles to improve. However, these cationic resins have the property of reducing the original resistance ratio, and although the cationic resins used in the present invention are selected to have a relatively small reduction rate, this influence cannot be avoided.

Magnesium sulfate has the ability to prevent or improve the reduction in light resistance caused by cationic resins, but the reason for this is not clear.

The porous inorganic pigment referred to in the present invention is a dry powder obtained by agglomerating primary particles of synthetic silica or hydrated aluminum oxide and having an average secondary particle size of 0.5 μm to 30 μm. Alternatively, when hydrated aluminum oxide is formed from water-soluble raw materials in a water bath, the missing particles have a size ranging from several microns to several hundred microns, and are self-agglomerating? Because of this, porous inorganic pigments can be made into porous inorganic pigments by drying, pulverizing, and classifying, or by using a spray dryer or the like during drying to adjust the particle size to the desired size.

Also, if synthetic silica or hydrated aluminum oxide is a fine powder of 1 μm or less, it can be used as a binder or adhesive after being dispersed in water. In addition, it is also possible to obtain a porous inorganic pigment having an average secondary particle diameter of 0.5 μm to 30 μm by drying, pulverizing, classifying, and spray drying with a spray dryer.

Furthermore, in order to form fine water-dispersed substances such as colloidal silica and colloidal alumina into particles of 70.5 μm or more, it is necessary to form them into particles with a particle size of 70.5 μm or more by suspending the fine particles in water as disclosed in U.S.P-3,855,172. By leaving a urea-formalin resin in the room and adjusting its production conditions, it is possible to obtain a porous inorganic pigment granulated to a desired secondary particle size.

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 metathesis precipitation products such as sodium silicate acid, carbon dioxide, and ammonium salts, and sodium silicate acid. Pyrolysis or ion exchange resin layer due to etc.? or colloidal silica obtained by heating and aging with this silica sol, gelling the silica sol, and the formation conditions? By changing the primary particles of several millimicrons to several tens of millimicrons, siloxane bonds became three-dimensional secondary particles of silica gel, and furthermore, silica sol, sodium silicate, aluminum/sodium acid, etc. were used as starting materials.
It is produced by heating at ℃ ~ 120 ℃, so-called Kaisei Molecule Sheep, etc.

Silicon dioxide? Refers to synthetic silicon-based hardware.

The porous hydrated aluminum oxide referred to in the present invention is an aluminum salt such as aluminum sulfate, aluminum nitrate, aluminum chloride, and the like, or an alkali metal salt of aluminate such as sodium or potassium aluminate salt, or the like. Neutralization of both water-soluble aluminum compounds from the water bath solution or ion exchange resin? The gel obtained by ion exchange using
It is usually obtained by washing to remove salts and then drying (7) 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.

After drying in the form of a block, crush it into 1 grade? It is also possible to make it into powder by doing this. The hydrated oxide thus obtained after drying has most, if not all, of its free water removed, and usually some of its bound water as well.

Most of the structure is irreversibly set into a porous solid. The pore diameter of the porous solid thus obtained is usually 50A to 5000A, and the surface charge when the secondary particles are dispersed in water becomes a glass charge (cationic).

In the present invention, the above-mentioned porous inorganic pigment can also be used in combination with organic 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 (
white clay), Merck, calcium sulfate, barium sulfate, titanium oxide, zinc oxide, zinc sulfide, zinc carbonate, spotted/white.

aluminum silicate, diatomaceous earth, calcium silicate,
Magnesium silicate, synthetic amorphous silica, water Iffff
Examples of white pigments such as Hyaluminum Lumina and Litopone and M pigments include thread-based glass pigments, acrylic plastic pigments, microcapsules,
There are urea resin pigments, etc.

Does the cationic resin referred to in the present invention dissociate and become cationic when dissolved in water? It refers to monomers, oligomers, or polymers, preferably having a quaternary ammonium group, and particularly preferably compounds having structures represented by the following general formulas (I) to (V).

CI+ 01 %0H2-OH-0 +nH(
OH2)m In the formula, 1, 2 and R3 are alkyl groups 1m and 1 to 7, n
is 2-10. Y represents an acid group.

In the formulas of (n) to (foundation), FL1 and R2 are -OH, -〇H
2-OH, -0H2-0) (2-OH, Y represents an acid group.

■) Polyalkylene/polyamine disia/diamid ammonium salt condensate (VD polyamide epichlorohydrin resin general formula (
The compound represented by I) is, for example, Nalpoly-607 (
(manufactured by Nalco Chemical) or Polyfix 601 (manufactured by Nalco Chemical)
(manufactured by Showa Kobunshi Co., Ltd.).

The compounds represented by the general formulas (11) to (11) are polydiallylamine derivatives, which are obtained by cyclization polymerization of diallylamine compounds.
), PA8 (Nitto Boseki Co., Ltd.), Neofix RPD (manufactured by Nikka Rhigakusha Co., Ltd.), etc.? I can list them.

Further, examples of the compound represented by the general formula (V) include Neofix P-70 (manufactured by NICCA Chemical Co., Ltd.).

Further, the f-hardware represented by the general formula (6) is Evinox 1301A (Dick Vercules), Kaimen 5
57H (Tick Bercules), Polyfix 3
01 (I18 Wa Kobunshisha) etc.? I can list them. The content of the cationic resins represented by these general formulas (I) to (I) is usually 0.1 to 4jI, preferably 0.2 to
By using 2 f/rrl, the water resistance according to the present invention can be improved.

Magnesium sulfate and/or its double salt referred to in the present invention are anhydrous magnesium sulfate, crystal water, etc. Magnesium sulfate, as well as various crystalline double salts such as potassium magnesium sulfate, sodium magnesium sulfate, and ammonium magnesium sulfate? Finger. The content of these magnesium sulfate and/or its salts should be 0.01 to 20% as magnesium sulfate (Mg804), preferably 0.02 to 10 f/ffI', so that the light resistance decreases. It can be prevented.

These porous inorganic pigments, cationic resins, magnesium sulfate and/or their double salts can be applied to recording media by dispersing or dissolving them in tap water, and if necessary using commonly used adhesives, inorganic pigments and other Add additives to make a coating liquid, size press IT, gate roll coater.
Apply and dry using an air knife coater, blade coater, spray, etc. As the adhesive, for example, acid (lZn
Cellulose n6 bodies such as M powder, ether f starch, carboxymethyl cellulose, hydroxyethyl cellulose,
Conjugated diene polymer latex such as casein, gelatin, Taitoyu/white, polyvinyl alcohol and its derivatives, maleic anhydride resin, ordinary styrene-butadiene co-TL complex, methyl methacrylate-butadiene copolymer,
Acrylic polymer latex such as a polymer or copolymer of acrylic acid ester and methacrylic acid ester, vinyl polymer latex such as ethylene vinyl acetate copolymer,
Alternatively, functional group-modified polymer latex using monomers containing functional groups such as carboxyl groups of these various polymers, water-based adhesives such as thermosetting synthetic resins such as melamine resins and urea resins, and polymethyl methacrylate, polyurethane resin,
Synthetic resin-based N absorbers such as unsaturated polyester resins, vinyl chloride-vinyl acetate copolymers, polyvinyl butyral, and alkyd resins are used alone or as a printing plate.

These adhesives are used in an amount of 2 parts to 100 parts, preferably 5 parts to 30 parts, per 100 parts of the pigment, but the ratio is not particularly limited as long as the amount is sufficient to bind the pigment. But over 100 parts of glue? If used, the adhesive film formation will reduce the void structure or make the void r extremely small, which is not preferable.

Other additives include pigment dispersants and thickeners.

Flowability modifier, antifoaming agent, foam inhibitor, mold release agent, foaming agent.

Penetrants, coloring dyes, N-color pigments, fluorescent whitening agents, ultraviolet absorbers, antioxidants, preservatives, anti-piping 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. In the case of paper, it is paper with no sizing agent added or with appropriate sizing, whether or not filler is included.

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. As a white pigment to be filled.

For example, many materials such as titanium acid, calcium sulfate, calcium carbonate, silica, clay, Merck, zinc oxide, etc. are used.

In addition, these resin films are pasted on the surface of the paper 7'
It is also possible to use so-called laminated paper, which is processed using carbon-based resin. A subbing layer or corona discharge machining may be applied to improve the contact between the resin surface and the ink receiving layer.

A sheet simply formed on a support can be used as a recording sheet according to the present invention as it is, for example, by heating it with a super calender, cross calender, etc. and/or passing it through a roll nip under pressure to ensure smoothness of the surface. It is also possible to give. In this case, the degree of processing may be limited because excessive processing, such as supercalender processing, will reduce the ink absorbency due to the voids between the particles that have been formed.

The aqueous ink referred to in the present invention is a recording liquid consisting of the following color increase mj, liquid medium, and other additives.

The coloring agent may be a direct dye, an acid dye, a basic dye, a reactive dye, or a water-soluble dye such as food coloring.

For example, direct dyes include C, 1, Direct Black Z, 4.9.1
1.14.17.19.22127゜32, 36.38
．． 41.48.49.51.56゜62, 71.74.
75.77, 78.80.105.106.107.1
08.112.113.117, 132.146.15
4.194C, 1, Direct Yellow 1
．． 2.4. & 11.12.24+ 26.27゜2
8, 33.3439.41.42.44.4 & 50, 5
1.513.7s85.86.87.88°98,10
0.110 C, I, Direct Orange 6. F3.1
0,26.29.39.41.49.51.102 C,1,DirectRed 1.2.4.8.9.
11.13.17.20.23, 2428.31.33
．． 37.39.44゜46147, 48.51.59.
6th 63,73°75,77.8o, al, sa,
's4.85.90゜94.99,101.10a
110,145゜189,197,220,224,
225,226.227,230 C, I, Direct Violet 1.7.9.
12.35.48.51.90.94C,LDirec
t Blue 1.2.6.8.15.22.25
．． 34.69°70, 71. 72. 75. 76,
78. 80.81, 82.83. 86.90.
98. 106. 108.110,120,123,
158,163゜165.1921193,194,1
95,196.199,200,201,202,20
3□207.2HL 236,237,239,246
．． 258 C, 1, Direct Green 1.6.8.2
8.3 & 37.63.64C, 1, Direct B
raun IA+ 2.6.25.27.44.58
．． 95°100.101,106,112.173,1
94.195,209,210,211 C,1,Ac1d Black 1.2.7.16.
17.24.26.28.31゜41, 48.52.5
to60.63194.107゜109,112.11&
119.124.122゜131.155,156 C, 1, AcidYellow 1.3.4.7.1
1.12.13.14. 1? , 18, 19.23
．． 25.29.34.36.38.40, 41.42
．． 44. 49. 53. 55. 59.61.7
1,72,76.78,99,111,114°116
．． 122, 135, 161, 172°C, LAcidO
Range? , 8.10.33.56.64C,
LAcidRed 1.46.8. 13. 1
41! lh l& 19.21゜26.27,30,
32,3435.37,40°4λ51.52.54.
5? , 80.82.83゜85.87.88,89
,92,9497,106°10JL 110,11!
li, 119,129,131゜13 turtle 134,13
5,154 155,172゜176.180.184
To 18 187,249°25 ton 25a 317
, 318 C, LAcid Violet 7. IL 15.3
435.4L 43.49.75C, 1, Ac1dB1
ue 1.7.9.2L 23.25.27.29
．． 40°41.4 & 45,49,51,53,55,
56°59.6s 78.80.81.83.90.9
2゜9&10s 104 11L 113,117
゜120.124, 126, 145, 167.171.
175,183,229,234,236e'l-Ac
1d Green a, 12.19.27.41
．． 9.16.20.25C,1,Ac1d Braun
4.14 Basic dyes include C,1,Ba5ic 131ack 2. BC,
l-Ba5ic Yellow 1.2. IL 1
2.14.2L 32.36C, 1, BasicOra
nge 2.15.21.22C,1,Ba5ic
Red 1.2.9.12.13.37C, 1,
Ba5ic Violet 1.3.7.10.14
C, LBaSiCBBlue 1.3.5.7.9,
24,25,26,28,29C,1,Ba5icGr
een 1,4C,I, Ba5ic Braun
1.12 Reactive dyes include C,1, Reactive Black 1.3.5
．． 6. & 1214C, I+Reactive Ye
low 1.2.3s 13.14.15.17C,
I, Reactive Orange 2, 5.7.1
t+, 20.24C,l,I(,active
ILed 6.7.11.12.1s, 17.21
．． 23゜24, 35.36.4 & 63.66 C, 1, active Violet 2.4.5
．． 8.9C, 1, 几active Blue
2.5.7. 1.2+ 13.14 15.17゜1B, 19.20.21.25.27.28゜37
, 38.40.41 C, 1, Reactive Green 5.7C
,1,Reactive Braun 1.7.1
6 Furthermore, food colorants include C, I, Food Black 2C, 1, Fo
od Yellow 3.45C, 1, Food
Red 2. & 7.9.145L 87.
9λ94102, 104105.106 C, 1, Food Violet 2 (:, 1.
Food Blue 1.2°C, 1, Food
Examples include Green 213.

Examples of the aqueous liquid medium include water and various water-soluble solvents, such as methyl alcohol.

Ethyl alcohol, n-propyl alcohol, inglobil alcohol, rl-7' ethyl alcohol, Sec
- Alkyl alcohols with 1 to 4 carbon atoms such as phthyl alcohol, tert-butyl alcohol, and isobutyl alcohol; amides such as dimethylformamide and dimethylacetamide; 1 ketones or ketone alcohols such as acetone and diacetone alcohol; ,
Ethers such as dioxane; polyethylene glycol,
Polyalkylene/glycols such as polypropylene glycol; ethylene glycol, propylene glycol, futhylenochlicol, triethylene glycol, 1,2.
Alkylene/glycols having 2 to 6 alkylene groups such as 6-hexandriol, thiodiglycol, hexylene glycol, diethylene glycol; chrycerin, ethylene glycol methyl ether, diethylene f IJ
Ko-A/ mef A/ (also 1f9f le) knee f)v
, ) lower alkyl ethers of polyhydric alcohols such as 7 f IJ col monomethyl ether, and the like.

Among these many water-soluble organic solvents, polyhydric alcohols such as diethylene glycol, and 1Jk class alkyl ethers of O polyhydric flucols such as triethylene glycol monomethyl ether and triethylene glycol monoethyl ether are preferred.

Examples of other additives include PH regulators, sequestering agents, antifungal agents, viscosity modifiers/surface tension modifiers, wetting agents, surfactants, and rust preventives.

Measurement of inoculation aptitude can be done using the following method.

The color densities were obtained by printing with a Sharp Color Image Printer (IO-700) in cyan (0), magenta (goods), yellow (2), and black (BL). The density of the image was measured using a Macbeth densitometer RD514 and used in a laboratory.

The light resistance is Canon's A/Kujietsu Toguri/Tar (A-1).
210) The image area obtained by printing with O, M, Y, and Bt inks using a xeno/fade meter (manufactured by Suga Test Instruments, Model FAL-25X-HCL) at 40°C. Irradiated for 40 hours at 60% and illumination intensity of 41w/ll,
Color intensity before and after irradiation Macbeth/Sitometer 81) 5
Measured at 14, what is the color after irradiation? The percentage of the value divided by the color before irradiation was expressed as light resistance (/A survival rate).

Light resistance was determined by immersing the image obtained by printing with OlM, Y, and Bt printing using the same Canon Y/KJET PR/Ter Purple in running water at 30°C for 3 minutes. This T Makpesude/Sitometer D 514 and 64
1, and the percentage of the dipping role's politeness and the dazzling percentage? The value was taken as the water resistance value. The higher the value, the better the water resistance.

The ink absorption speed is determined by using a Sharp or Canon inkjet printer, feeding the paper immediately after solid printing (about 1 second) of red printing (maze/red + yellow), and touching the paper presser roll or finger. The judgment was made based on whether dirt appeared or not.

Furthermore, the absorption capacity is higher than that of polyethylene glycol (PEGA).
400) /ZK 1 / 1 (7) Place the plate in contact with a fixed area of the receiving layer at 20°C for 10 seconds.

Excess lees was removed with a vacuum cleaner, and the amount of lees absorbed into the receiving layer was measured, and used as the number of grams drawn by Hiraki.

(5) Examples The present invention will be described below with reference to examples, but the invention is not limited to these examples. Note that parts and percentages shown in the examples mean parts by weight and percentages by weight.

Example 1 80 parts of LBKP with a water content of 370 rrt csf, FyF, 20 parts of NBKP with a water content of 4101 ntcsf, 10 parts of Merck for internal filling, 3 parts of clay for internal filling, rosin sizing agent of Kneefor 100 (manufactured by Deitzk Harkieless) 0
．． From the slurry consisting of 5 parts and 2.5 parts of band, base paper with a basis weight of 68 υ is made using a long rope paper machine, and during paper making, oxidized starch i 1.5 ? /ff1' was attached and a coated base paper R was made. I was impressed with the size of this base paper in 33 seconds.

As a coating liquid, 100 parts of synthetic silica (Syroid 620, manufactured by Fuji Doug 4 Fufu Co., Ltd.), which is a porous inorganic pigment, and polyvinyl alcohol (PVA117, manufactured by Kuraray Co., Ltd.), which is a water-soluble resin.
90 parts, 10 parts of cationic resin Polyfix 601 (Shoorokobunshishasaku), crystalline magnesium sulfate (MgS
Prepare an aqueous coating solution 7 with a concentration of 16% consisting of 10 parts of o 4.7H20), other antifoaming agents, and a small amount of fluorescent agent, and coat the acidic base paper with an air knife coater to a solid content of 9? /n? Smear it on the sea urchin and let it dry. Then, lightly run it through a super calendar and use it as the recording paper of Example 1. The Beck smoothness of this recording paper was 105 seconds. Is this recording paper suitable for inkjet printing? The evaluation results are shown in Table 1 above.

Comparative Example 1 Crystalline magnesium sulfate from the coating solution of Example 1? A recording paper of Comparative Example 1 was obtained in the same manner as in Example 1 except for the removal of the paper. The Beck smoothness of this recording paper was 102 seconds and 0.
Table 1 shows the results of evaluating the suitability of this recording paper for inoculation.

Comparative Example 2 Cationic resin from the coating solution of Example 1? A recording paper of Comparative Example 2 was obtained in the same manner as in Example 1 except that the paper was removed. The Beck smoothness of this recording paper was 95 seconds. Table 1 shows the results of evaluating the suitability of this recording paper.
Shown below.

Comparative Example 3 Porous inorganic pigment (Syroid 62) in the coating solution of Example 1
A recording paper of Comparative Example 3 was obtained in exactly the same manner as in Example except that 100 parts of kaolin for coating 0)7 (Ultra White-90 manufactured by Engelhard) was used.

The Bekk smoothness of this recording paper was 260 seconds and 9. Results 7 of evaluating the inkjet suitability of this recording paper
It is shown in Table 1.

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 sulfate in the coating solution of Example 1. The Beck smoothness of this recording paper is 1
It's 10 seconds. This recording paper was evaluated for inkjet suitability and the results are shown in Table 1.

Examples 2 to 7 LBKP 80 parts of F Suisan 370 dcsf, P Suisan 40
0g csf of NBKP 20 parts, heavy calcium carbonate 13
part, 1 part cation/starch, alkyl ketene dimer t,
', m+<Burcon W Manufactured by Deutsukunohecules Co., Ltd.)
A base paper with a basis weight of 68 t/m is made from a slurry consisting of 12 parts of 0.0° and 0.4 parts of polyalkylene/polyamine epichlorohydrin resin using a long paper machine, and during paper making, a size press machine is used to convert solids into oxidized powder. Neutral coated base paper R was produced by adhering 1.5η to the spine.The Steckigt size degree of this base paper was 35 seconds.

As a 7J1 coating liquid, a slurry in which 100 parts of synthetic silica (Tubushial LP (manufactured by Nippon Silikani Gyo Co., Ltd.)) was dispersed in 400 parts of water. Grind the agglomerated particles through a Viscomill, add 15 parts of polyvinyl alcohol, and add 18 parts of aqueous
A coating solution was prepared and the solid content was 13'j/rr? applied to the neutral coated base paper using an air knife coater. I smeared it so that it looked like this, dried it, and made 9 base coats of paper. Next, 100 parts of synthetic silica (Syroid 74, manufactured by Fuji Devine Co., Ltd.) as a second conditioning liquid, 40 parts of polyvinyl alcohol (PVA 117°, manufactured by Kuraray Co., Ltd.) as a water-soluble resin, and Neofix RPD (manufactured by Nicca Chemical Co., Ltd.) as a cationic resin. ) 7 parts, anhydrous magnesium sulfate (Mg5Oa)k 1 part, 5 parts, 10 parts, 20 parts respectively
Make a second coating with a concentration of 13% consisting of a small amount of antifoaming agent, and use an air knife coater to coat the undercoat with the first coating solution until the solid content is 5η. It was smeared with sea urchin, dried, and then passed through a super calendar to obtain recording sheets of Examples 2, 3, 4.5, and 6.7, respectively.

This recording paper was evaluated for inkjet suitability, and the results are shown in Table 2.

Comparative Example 5 The anhydrous magnesium sulfate in the second coating solution used in Examples 2 to 7 was added, and the recording paper of Comparative Example 5 was prepared in the same manner as in Examples 2 to 7. The paper was evaluated for inkjet suitability and is shown in Table 2.

Example 8 Sulfur-stage magnesium potassium (K2 Mgz (80a)s) was used in place of the anhydrous magnesium sulfate used in Example 4.
10m'! ! - A recording sheet of Example 8 was obtained in exactly the same manner as in Examples 2 to 7 except that the following was used. The inkjet suitability of this recording paper was evaluated and the results are shown in Table 2.

Comparative Examples 6 to 10 In place of 7iC magnesium potassium sulfate used in Example 8, KCL, Na0L, Na280a, 0aO
L2・2H20, ZnCtz rf nine pieces are Example 8
Comparative Example 6. 7.8.9.10 recording paper t! Also. These recording papers were evaluated for inkjet suitability, and the results are shown in Table 2.

(G) Effects of the Invention In Examples 1 to 8 in which the porous inorganic pigment, cationic resin, and magnesium sulfate according to the present invention were mixed with gold dust, the ink absorption ability, color density, and storage stability (light resistance and water resistance) were improved. Extremely excellent in all aspects.

Especially magnesium sulfate? It is clear that the light resistance (Bt and maze/liquidity) was significantly improved compared to the comparative example which was not used, and it was excellent as an inkjet paper at 7'C%.

Claims (4)

[Claims] (1) In an inkjet recording medium that forms a recorded image using an aqueous ink containing at least one water-soluble dye selected from direct dyes, acid dyes, basic dyes, reactive dyes, and food colorings, The recording medium is a porous inorganic pigment,
An inkjet recording medium characterized by containing a cationic resin and magnesium sulfate and/or its double salt. (2) The inkjet recording medium according to claim 1, wherein the porous inorganic pigment is a pigment selected from at least one of 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 content of magnesium sulfate and/or its double salt is in the range of 0.01 to 20 g/m^2 as magnesium sulfate content, according to any one of claims 1 to 3. Inkjet recording media.