JP2008246990A - Inkjet recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording medium, which has high surface strength, high color developing properties, high print density and ink absorbency and causes few image defects such as color non-uniformity at printing, even under the condition that silica and cationic polymeric ink fixing agent are simultaneously blended with one another in an ink receiving layer coating material. <P>SOLUTION: In the inkjet recording medium, an ink receiving layer containing an inorganic pigment, an organic polymeric binding agent and a cationic ink fixing agent is provided on a substrate. The ink receiving layer is obtained by coating on the substrate a coating material prepared by a further addition of the cationic ink fixing agent, after the mixed dispersion of the inorganic pigment and the organic polymeric binding agent. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ink jet recording medium suitably used for ink jet recording.

  In general, inkjet recording systems have spread rapidly due to the ease of full-color printing, less printing noise, and the need for processing such as development and fixing. In recent years, they have faded into multicolor printing by plate-making and printing by color photography. It became possible to obtain images without. In this method, fine droplets of ink are ejected from a nozzle toward a recording medium at high speed, and images and characters are recorded, and the ink contains a large amount of solvent. Therefore, it is necessary for the recording medium to absorb ink promptly.

  Recently, with the widespread use of high-resolution digital video, digital cameras, scanners, and personal computers, there are many opportunities to handle high-definition images, and these hard copies are often output by inkjet printers. As a result, the required characteristics of recording media have been diversified, and in particular, image quality, glossiness, and the like that are similar to silver halide photography have been demanded.

From such a background, the ink jet recording medium requires high color development, resolution and color reproducibility, and in order to cope with this, an ink receiving layer is provided on the surface of the recording medium to provide high color development and ink absorption. Inkjet recording media have been developed. Various methods have been proposed so far in order to improve the color developability. For example, a method of containing amorphous silica in the ink receiving layer has been proposed (see Patent Document 1). In addition, an ink jet recording medium is required to have a high color developability in a printed image and to be free from image defects such as unevenness of the image, blurring at the boundary, white spot missing, and the like. In order to solve this, auxiliary agents such as an ink fixing agent and a sizing agent are generally used, and many methods for reducing defects and improving quality by limiting the composition and molecular weight are proposed ( Patent Document 2). In addition, ink jet recording media have a problem that the coating layer strength is weak. For this reason, papers with improved binder strength by increasing the amount of binder have been reported, but such recording papers have insufficient ink absorption capacity, resulting in noticeable bleeding and reduced image quality. there were. Therefore, in JP-A-62-288076, an attempt is made to improve the adhesive strength by using a water-insoluble resin obtained by reacting polyvinyl alcohol, acrylic acid and methyl methacrylate. However, since the water-insoluble resin is anionic, the fixability of the ink fixing agent, which is mainly anionic, is poor.

A method for producing a high-quality inkjet recording paper satisfying these characteristics by a cast coating method has already been proposed (see Patent Documents 3 and 4).
In the cast coating method, a coating liquid mainly composed of a pigment and a binder is coated on a base paper to provide a coating layer that serves as an ink receiving layer, and the coating layer in a plastic state after being wetted is cast drum. This is a method of pressing against the mirror-finished surface and gloss finishing. This method includes (1) a wet casting method (direct method) in which a coating layer is pressed against a heated drum that has been mirror-finished while the coating layer is wet (direct method), and (2) a wet coating layer is temporarily (half) Re-wet cast method (re-wetting method), which is swelled and plasticized with a re-wetting liquid after drying, and pressed onto a mirror-finished heated drum (drying method). (3) The wet coating layer is converted into a gel state by coagulation treatment. Generally, it can be divided into three types, that is, a gelling cast method (coagulation method) in which a heated drum is pressed and dried.
Patent Documents 5 and 6 describe cationic ink fixing agents synthesized by a so-called dispersion type (suspension polymerization) using diallyldimethylammonium chloride as a main monomer and an appropriate addition of acrylamide as an auxiliary monomer as an ink fixing agent. ing.

JP-A-8-310110 Japanese Patent Laid-Open No. 11-277877 JP-A-62-95285 JP-A-5-59694 U.S. Pat. No. 4,929,655 US Patent No. 5,0065,990

When a cationic polymer ink fixing agent is added to the ink-receiving layer coating in order to obtain high color development and defect-free printing quality, the hydroxyl group on the surface of an inorganic pigment such as silica and the cationic functional group in the ink fixing agent There was a disadvantage that the stability of the paint was lowered by the interaction between the two. Furthermore, when the cationization degree of the ink fixing agent is high, the binder distribution in the obtained ink receiving layer becomes more non-uniform, the coating layer strength decreases, and the pigment and the ink fixing agent aggregate non-uniformly. Problems such as unevenness in absorbability and image defects occur.

  Therefore, the present invention has a high surface strength, high color developability, high print density and high ink absorbency even when silica and a cationic polymer ink fixing agent are blended in the ink receiving layer coating. An object of the present invention is to provide an ink jet recording medium having few image defects such as color unevenness when printed.

As a result of investigations to solve the above problems, the inventors have found that the problems can be achieved by the following configuration. That is, the present invention is an ink jet recording medium in which an ink receiving layer containing an inorganic pigment, an organic polymer binder, and a cationic ink fixing agent is provided on a support, and the ink receiving layer is an inorganic pigment. An ink jet recording medium prepared by further adding a cationic ink fixing agent after mixing and dispersing an organic polymer binder and coating a coating on a support.
Further, the organic polymer binder is preferably polyvinyl alcohol, and the cationic ink fixing agent is preferably a polyallylamine polymer.

Hereinafter, embodiments of the present invention will be described.
(Support)
As the support used in the present invention, a sheet-like material such as paper, cloth, resin film, and resin-coated paper can be preferably used, but preferably paper (coated paper, uncoated paper, etc.). Is used. As the raw material pulp of the paper, chemical pulp (coniferous bleached or unbleached kraft pulp, hardwood bleached or unbleached kraft pulp, etc.), mechanical pulp (ground pulp, thermomechanical pulp, chemithermomechanical pulp, etc.), deinked pulp Etc. can be used alone or in admixture at any ratio. The pH of the paper may be acidic, neutral or alkaline. In addition, when a filler is included in the paper, the opacity of the paper tends to be improved. Therefore, it is preferable to include a filler. Examples of the filler include hydrated silicic acid, white carbon, talc, kaolin, clay, calcium carbonate. Well-known fillers such as titanium oxide and synthetic resin fillers can be used.

(Ink receiving layer)
The ink receiving layer contains at least an inorganic pigment, an organic polymer binder, and a cationic polymer ink fixing agent.

1. Inorganic pigment
The pigment contributes to the adsorption of the dye ink and the pigment ink colorant and the absorbability of the ink solvent, and has a function of serving as a carrier for other auxiliary agents. Examples of the inorganic fine particles used in the present invention include synthetic amorphous silica, colloidal silica, colloidal alumina, vapor phase silica, vapor phase method alumina, boehmite, pseudoboehmite, water synthesized by a wet method, a vapor phase method, and the like. Aluminum oxide, alumina, lithopone, zeolite, hydrous halloysite, magnesium carbonate, magnesium hydroxide, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, white carbon, light calcium carbonate, heavy calcium carbonate, kaolin, calcined kaolin, talc, Clay, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white and the like can be used. In addition, inorganic fine particles that have been modified such as cationization or silylation or whose shape has been changed can also be used. Further, one or more of the above inorganic fine particles can be used in combination. In particular, it is preferable to use synthetic amorphous silica from the viewpoint of improving transparency, strength, and color density of the printed portion.

Synthetic amorphous silica can be roughly classified into wet method silica and gas phase method silica depending on the production method. Synthetic amorphous silica produced by a wet process (hereinafter referred to as “wet process silica” where appropriate) is inferior to gas-phase process silica in terms of pigment transparency, but is excellent in paint stability when used in combination with polyvinyl alcohol. Furthermore, compared with gas phase method silica having no internal voids, wet method silica has good dispersibility in the liquid and can increase the coating concentration. Therefore, when wet method silica is used as the pigment of the ink receiving layer, the pigment ratio in the ink receiving layer can be increased to increase the absorbability of the ink receiving layer, so that the ink absorbability can be improved and the coloring property of the dye ink can be improved. Can be improved.
Further, as the wet method silica, there are “gel method silica” produced by a gel method and “precipitation method silica” produced by a precipitation method. As the pigment of the ink receiving layer, either gel method silica or precipitation method silica may be used alone, or these may be used in combination.

2. Organic polymer binder The water-soluble binder is used to maintain the properties of the ink receiving layer as a coating film. Examples of the water-soluble binder used in the present invention include polyvinyl alcohol (hereinafter, appropriately referred to as “PVA”), silyl-modified polyvinyl alcohol, and polyvinyl alcohol such as cation-modified polyvinyl alcohol, and modified products thereof, oxidized starch, acetyl. Water-soluble polymer binders such as starches such as modified starch and etherified starch and derivatives thereof, proteins such as casein, gelatin, and soy protein, cellulose derivatives such as polyvinylpyrrolidone, carboxymethylcellulose, and hydroxyethylcellulose; Polymer binders such as SB latex, NB latex, acrylic latex, vinyl acetate latex, ethylene vinyl acetate latex, polyurethane, and unsaturated polyester resin can be used. In particular, it is preferable to use polyvinyl alcohol from the viewpoint of improving transparency, strength, and color density of the printed portion, and it is particularly preferable to use completely saponified polyvinyl alcohol. When the saponification degree is 90% or less, the stability of the paint tends to deteriorate. Further, polyvinyl alcohol and one or more of the above polymer binders can be mixed and used.

  The amount of the organic polymer binder in the ink receiving layer is preferably 3 to 40 parts by weight with respect to 100 parts by weight of the inorganic pigment. When the blending amount of the organic polymer binder is less than 3 parts by weight, the strength of the ink receiving layer surface becomes insufficient, and when it exceeds 40 parts by weight, the ink absorbability is inhibited.

3. Ink fixing agent Ink fixing agent is used to hold ink in the ink receiving layer by combining with ink when an image is printed by a printer, and is cationic so as to easily hold an anionic ink. Ink fixing agents are often used. Examples of cationic ink fixing agents include diallyldimethylammonium chloride polymer, dicyandiamide / formaldehyde resin, dicyandiamide / alkylamine polymer, diethylenetriamine / dicyandiamide / ammonium chloride condensate, (meth) acryloyloxyalkyltrialkylammonium chloride polymerization. Products, ethyleneimine polymer, diallylamine polymer, ammonia / epichlorohydrin / dimethylamine copolymer, polymethacrylic acid quaternary ammonium salt derivatives, and the like.

Of these, polyallylamine polymers are particularly preferred from the viewpoints of compatibility with ethylene vinyl acetate and silica, color development and water resistance of printer prints. The cationization density of this polyallylamine polymer needs to be about 10 meq / g. When the cationization density is low, the water resistance of the printed image is insufficient, and the molecular weight of the polyallylamine is preferably 1000 to 30000. When the molecular weight is 30000 or more, there is a problem that the drug itself is highly viscous and difficult to handle. Examples of the polyallylamine polymer that can be used in the present invention include PAA-HCl-01 / PAA-HCl-03 / PAA-HCl-05 / PAA-HCl-3L (all manufactured by Nitto Boseki Co., Ltd.). . The structural formula of the polyallylamine polymer is shown below.

  The weight average molecular weight (Mw) of the ink fixing agent was measured by gel permeation chromatography (GPC) using a Hitachi L-6000 type high performance liquid chromatograph. The eluent flow path pump is Hitachi L-6000, the detector is Shodex RI SE-61 differential refractive index detector, the column is Asahi Pack's water-based gel filtration type GS-220HQ (exclusion limit molecular weight 3,000) and GS- 620HQ (exclusion limit molecular weight 2 million) and a double connection were used. The sample was adjusted to a concentration of 0.5 g / 100 ml with an eluent, and 20 μl was used. A 0.4 mol / l sodium chloride aqueous solution was used as an eluent. The column temperature was 30 ° C. and the flow rate was 1.0 ml / min. A calibration curve is obtained using polyethylene glycol having a molecular weight of 106, 194, 440, 600, 1470, 4100, 7100, 10300, 12600, 23000 or the like as a standard sample, and the weight average molecular weight (Mw) of the copolymer is determined based on the calibration curve. )

The ink fixing agent cationization density was measured with a particle surface charge measuring device (MUTEC TOLEDO DL-50) using a 0.001 mol / L polyvinyl potassium sulfate (PVSK) solution as a titrant. It is the value obtained by the formula.

5. Other Components In addition to the above components, a known pigment or a known binder can be used in combination with the ink receiving layer as long as the effects of the present invention are not impaired. Other additives include dye fixing agents, pigment dispersants, thickeners, fluidity improvers, antifoaming agents, antifoaming agents, mold release agents, foaming agents, penetrating agents, colored dyes, colored pigments, fluorescent enhancers. A white agent, an ultraviolet absorber, an antioxidant, an antiseptic, an antibacterial agent, a water resistant agent, a wet paper strength enhancer, a dry paper strength enhancer, and the like can be appropriately blended in the ink receiving layer.

(Production method)
As a method of applying the ink receiving layer coating material on the support, known coatings such as blade coater, air knife coater, roll coater, brush coater, kiss coater, squeeze coater, curtain coater, die coater, bar coater, gravure coater, etc. What was suitably selected from the coating methods using a machine is mentioned.

(Layer structure)
The ink receiving layer may be provided with two or more ink receiving layers by coating the ink receiving layer coating in two or more times for functional separation of the layers. Further, when it is desired to provide a gloss layer having gloss on the outermost surface, the gloss layer can be provided by using a cast coating method described below. When providing a plurality of ink receiving layers, the ink receiving layer other than the outermost layer (in the case of two ink receiving layers, the ink receiving layer in contact with the support) is particularly referred to as an under layer. By providing the under layer, high ink absorbability can be obtained, which is preferable for improving the quality of the inkjet medium. In addition, if there are minute cracks or dot-like coating defects on the surface of the under layer, they will appear as image defects even after the glossy layer is applied.

(Ink-receptive layer paint)
The ink-receptive layer paint affects the quality of the finished coated paper, depending on the order in which materials are added during preparation. In the present invention, it is preferable to prepare a coating material by adding and mixing a dispersion medium such as water, an inorganic pigment, an organic polymer binder, and a cationic ink fixing agent in this order. When paints obtained by mixing in the above order are used, paints mixed in any other order (for example, dispersion medium such as water, cationic ink fixing agent, inorganic pigment, organic polymer binder) The strength of the formed coating layer is improved and the unevenness of ink absorption at the time of printing is reduced as compared with the case where a coating material or the like is used.

(Cast coat method)
In the present invention, an ink receiving layer is preferably provided by a so-called cast coating method from the viewpoint that an ink jet recording medium having high gloss can be obtained. The cast coating method is a method in which the surface of the coating layer formed by applying the coating solution for the ink receiving layer to the surface on which the ink receiving layer is applied is wet and the metal is heated while the coating layer is in a plastic state. This is a method of pressing against a mirror surface (cast drum, etc.) to give a glossy finish.
As the cast coating method, any of the direct method, the coagulation method, and the rewet method can be used. However, the coagulation method is reproducible from the viewpoint of improving the productivity because high gloss can be obtained. A wet method is preferred.

  When the ink receiving layer is provided by the coagulation method cast coating method, the ink receiving layer coating solution is applied on the under layer or the support, and while the coating layer is in a wet state, A treatment liquid having an action of coagulating (or cross-linking) the binder is applied on the coating layer, and then the coating layer is pressure-bonded to a heated mirror surface to give gloss. For example, when polyvinyl alcohol is used as the binder, any aqueous solution containing a compound capable of coagulating polyvinyl alcohol can be used. In particular, a treatment liquid containing boric acid and borate is preferable. By mixing and using boric acid and borate, it is easy to obtain a solidified state with an appropriate hardness, and a cast coated paper for ink jet recording having a good gloss feeling can be obtained.

  When the ink-receiving layer is provided by the re-wetting method cast coating method, the ink-receiving layer coating solution is applied on the under layer or the support and dried, and the dried coating layer is bonded to the coating layer in the coating layer. A treatment liquid having an action of plasticizing the adhesive is applied, and then the coating layer is pressure-bonded to the heated mirror surface to give gloss. In the case of the rewet cast coating method, the ink-receiving layer is in a dry state when the treatment liquid is applied, so it is difficult to copy the mirror drum surface, and there are many minute irregularities on the surface, resulting in slight glossiness. Although it tends to fall, the coating speed can be increased as compared with other methods, so that productivity is improved.

The coating amount of the ink receiving layer can be arbitrarily adjusted within the range that covers the surface of the support and sufficient ink absorbency is obtained, and is usually about 5 to 30 g / m ^{2 in} terms of solid content per side. It can be. From the viewpoint of achieving both recording density and ink absorbency, a more preferable range of the coating amount of the ink receiving layer is 10 to ²⁰ g / m ² .
When using a cast coating method to make the ink receiving layer glossy, the under layer coating amount can be arbitrarily adjusted as long as the surface of the base paper is covered and sufficient ink absorption is obtained. In general, it can be about 5 to 30 g / m ^{2 in} terms of solid content per one side. The coating amount of the glossy layer can be arbitrarily adjusted within a range that covers the surface of the under layer and sufficient ink absorbability is obtained, and is usually about 5 to 30 g / m ^{2 in} terms of solid content per one side. can do. From the viewpoint of achieving both recording density and ink absorbability, a more preferable range of the coating amount of the ink receiving layer is 3 to 15 g / m ² . When the coating amount of the ink receiving layer exceeds 30 g / m ² , the peelability of the ink receiving layer from the mirror drum may be reduced, and problems such as adhesion of the under layer to the mirror drum may occur.

  In the present invention, if necessary, a back coat layer for imparting writing property, antistatic property, antifouling property, slipperiness, etc. is provided on the surface of the support opposite to the surface on which the ink receiving layer is provided. Is also possible.

  In addition, the coating liquid for forming the ink receiving layer, and the treatment liquid for forming the ink receiving layer in the cast coat may include a pigment dispersant, a water retention agent, a thickener, an antifoaming agent, an antiseptic, as necessary. A colorant, a water-resistant agent, a wetting agent, a fluorescent dye, an ultraviolet absorber, a cationic polymer electrolyte, and the like can be appropriately added.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example. Unless otherwise specified, “part” and “%” described below represent “part by mass” and “% by mass”, respectively.

<Example 1>
(Manufacture of support)
A pulp slurry consisting of 100 parts of hardwood bleached kraft pulp (L-BKP) with a beating degree of 285 ml, 10 parts of talc, 1.0 part of aluminum sulfate, 0.1 part of a synthetic sizing agent, and 0.02 part of a yield improver. It was added and paper was made with a paper machine. At the time of papermaking, starch was applied on both sides so that the solid content per side was 2.5 g / m ² to obtain a support having a basis weight of 170 g / m ² .
(Ink receiving layer)
On one side of this support, coating liquid A was applied with a blade coater so that the coating amount was 15 g / m ² and dried by blowing at 140 ° C. to form an ink receiving layer.
Coating liquid A: 50 parts of precipitated silica (Fine Seal X-12: manufactured by Tokuyama Co., Ltd.) and 50 parts of gel method silica (Mizukasil P-50: manufactured by Mizusawa Chemical Co., Ltd.) are dispersed as pigments in an appropriate amount of water. The mixture was stirred for about 1 hour after dispersion. Then, 5 parts of completely saponified polyvinyl alcohol (PVA-117, polymerization degree 1700, saponification degree 98%, manufactured by Kuraray Co., Ltd., abbreviated as “PVA”) and ethylene / vinyl acetate copolymer emulsion ( 30 parts of AM-3150, manufactured by Showa Polymer Co., Ltd., abbreviated as “EVA”, and 0.5 parts of a glycerin ester antifoaming agent (Nopco 1407-K: San Nopco Co., Ltd.) as an antifoaming agent. In addition, thoroughly mixed. Finally, 10 parts of polyallylamine-based cationic ink fixing agent (PAA-HCl-05, molecular weight 5000, cationization density 10.7 meq / g, manufactured by Nitto Boseki Co., Ltd.) is mixed and stirred for about 30 minutes to obtain a solid content. A 25% coating solution was prepared.

<Example 2>
Instead of polyallylamine cationic ink fixing agent (PAA-HCl-05, molecular weight 5000, cationization density 10.7 meq / g, manufactured by Nitto Boseki Co., Ltd.) of coating liquid A for ink receiving layer An ink jet recording medium was prepared in the same manner as in Example 1 except that 10 parts of a conductive ink fixing agent (PAA-HCl-3L, molecular weight 15000, cationization density 10.7 meq / g, manufactured by Nitto Boseki Co., Ltd.) was blended. Obtained.
<Comparative Example 1>

  In the preparation of the coating liquid A for the ink receiving layer, Example 1 and Example 1 were changed except that 10 parts of the polyallylamine-based cationic ink fixing agent added last was added first. An ink jet recording medium was obtained in exactly the same manner.

<Comparative example 2>
In preparing the coating liquid A for the ink receiving layer, a polyallylamine cationic ink fixing agent (PAA-HCl-) was used instead of the polyallylamine cationic ink fixing agent (PAA-HCl-05, manufactured by Nitto Boseki Co., Ltd.). 3 L, manufactured by Nitto Boseki Co., Ltd.) An ink jet recording medium was obtained in the same manner as Comparative Example 1 except that 10 parts were blended.
<Comparative Example 3>

  In the preparation of the coating liquid A for the ink receiving layer, diallyldimethylammonium chloride polymer (TDK-) was used instead of the polyallylamine-based cationic ink fixing agent (PAA-HCl-05, manufactured by Nitto Boseki Co., Ltd.) added first. 129, manufactured by Seiko PMC Co., Ltd. was used, and an ink jet recording medium was obtained in the same manner as Comparative Example 1.

<Comparative Example 4>
The polyallylamine cationic ink fixing agent (PAA-HCl-05, manufactured by Nitto Boseki Co., Ltd.) of the coating liquid A for the ink receiving layer was not blended, but instead diallyldimethylammonium chloride polymer (TDK-171, molecular weight) An ink jet recording medium was obtained in the same manner as in Example 1 except that 10 parts of 30000, a cationization density of 6.3 meq / g, manufactured by Seiko PMC Co., Ltd. were blended.
<Comparative Example 5>

  An inkjet recording medium was obtained in exactly the same manner as in Comparative Example 1 except that the amount of PVA was 10 parts in adjusting the coating liquid A for the ink receiving layer.

<Comparative Example 6>
An inkjet recording medium was obtained in exactly the same manner as in Comparative Example 1 except that the amount of EVA blended was 35 parts in the adjustment of the coating liquid A for the ink receiving layer.

The ink jet recording media of each Example and Comparative Example were evaluated by the following method.
(1) Dispersibility The pigment dispersibility of the ink-receiving layer coating liquid A was evaluated according to the following criteria. The dispersibility was visually evaluated, and the evaluation criteria are shown below.
○: Dispersibility is not particularly problematic
△: Inferior dispersibility but possible to be dispensed ×: Dispersibility is extremely inferior and discontinuation of the dispensation is not possible (2) Paint stability It was evaluated with. If the evaluation is Δ or ○, there is no practical problem.
○: B-type viscosity increase when the mixture is allowed to stand overnight after adjustment and re-stirring is 1000 cps or less. Δ: B-type viscosity increase when the mixture is allowed to stand overnight after adjustment and re-stirring is 1000 cps or more. After the adjustment, the mixture was allowed to stand overnight, and agglomerates remained even after re-stirring. The B-type viscosity was measured using a B-type viscometer (BM type VISCOMETER: manufactured by TOKIMEC INC.) According to JIS Z8803. .
(3) Coating layer strength The strength of the coating layer prepared using the ink receiving layer coating solution A was evaluated according to the following criteria. If the evaluation is Δ or ○, there is no practical problem.
○: Measurement load is 700 gf / 18 mm or more Δ: Measurement load is 400 to 700 gf / 18 mm
X: The coating layer is removed when the measurement load is less than 400 gf / 18 mm. The coating layer strength is an adhesive tape that is an adhesive tape on the surface of the ink receiving layer according to the method defined in IS-K6854 (Nichiban width 18 mm). ), Leaving the end, and rolling the roller with its own weight of 5 kg back and forth 5 times on the surface of the tape to attach the tape, and then 180 degrees so that the end of the tape that is not attached becomes U-shaped when viewed from the side. It was turned around. On the other hand, a holding plate was bonded to the back surface of the inkjet recording paper. The tape end is attached to the moving head of a constant speed tensile tester (manufactured by ORIENTEC, TENSILON RTC-1210A), the gripping plate is attached to the fixed head, and the moving head is attached to the surface of the ink receiving layer at a speed of 100 mm / min. The tape was peeled off from the surface of the ink receiving layer by moving in parallel with the tape, and the load at that time was measured.
(4) Water resistance When a predetermined pattern is recorded using an ink jet printer (PM-950C: trade name, manufactured by Epson Corporation), a drop of deionized water is dropped on the next day after printing, and left to stand until the next day. The print quality of the recorded image portion was visually evaluated according to the above criteria.
○: No blurring Δ: Slight blurring is observed ×: Blemish generation is noticeable (5) Print quality Predetermined pattern using an ink jet printer (PM-950C: trade name of Epson Corporation) Recording was performed, and the print quality of the recorded image portion was visually evaluated according to the following criteria.
○: No blurring, vivid △: Slight blurring or slightly inferior in vividness ×: Blemishing or invisible

  The obtained results are shown in Tables 1 and 2.

As is clear from Tables 1 and 2, in the case of the ink jet recording medium of each Example, there were no problems in all of the coating stability, surface strength, water resistance, and print quality, and high evaluation was obtained.
On the other hand, in the case of Comparative Examples 1 to 5, since the addition order of the ink fixing agent was first changed, the dispersibility was improved, but the coating stability and the surface strength were significantly reduced. This is presumably because the interaction between the pigment and the ink fixing agent works because the degree of cationization of the ink fixing agent is large, and PVA and EVA to be added thereafter do not play a role as a binder.

Moreover, in the case of the comparative example 3, although the surface strength was strong, printing quality and water resistance were inferior. This is presumably because the constituent material of the ink fixing agent is diallyldimethylammonium chloride polymer, and the degree of cationization is low.
In Comparative Examples 5 to 6, a good ink jet recording medium could not be obtained because bleeding occurred after printing. This is considered to be caused by an excessive amount of binder added to obtain surface strength.

Claims (3)

  An ink jet recording medium comprising an ink receiving layer containing an inorganic pigment, an organic polymer binder, and a cationic ink fixing agent on a support, wherein the ink receiving layer comprises an inorganic pigment and an organic polymer binder. An ink jet recording medium comprising: a coating material coated on a support prepared by further adding a cationic ink fixing agent after mixing and dispersing the agent.   2. The ink jet recording medium according to claim 1, wherein the organic polymer binder is polyvinyl alcohol.   The inkjet recording medium according to claim 1, wherein the cationic ink fixing agent is a polyallylamine polymer.