JP2003312141A - Ink jet recording medium of plain paper type - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink jet recording medium of a plain paper type which has a high printing density and besides causes neither bleeding nor feathering. <P>SOLUTION: This recording medium is made by coating or impregnating at least one side of original paper with a coating solution constituted mainly of a water-soluble polymer, a sizing agent and a synthetic resin emulsion. The synthetic resin emulsion is made by using a surfactant of 1.5 pts.wt. or below to 100 pts.wt. of a polymerizable monomer. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plain paper type ink jet recording medium, and more particularly to an ink jet recording medium which does not cause bleeding or feathering despite high print density.

[0002]

2. Description of the Related Art Ink jet recording type recording media are
The texture is roughly classified into a plain paper type, which resembles so-called high-quality paper / PPC paper, and a coated paper type, which has an ink receiving layer. Among them, the plain paper type inkjet recording medium does not have an ink receiving layer, or has a very small amount, so that it is suitable for general writing such as an electrophotographic recording system, pencil, pen, etc. It is also inexpensive.

By the way, in general, the ink jet recording medium is required to have the following performance. : Good ink absorbency, ink droplets adhering to the surface of the recording medium quickly permeate into the paper layer, and appear to be in a dry state, and do not cause contamination due to contact with the recording device, other medium, or hands. . : The ink droplets do not diffuse or penetrate into the surface of the recording medium more than necessary, and the dots recorded by the ink droplets do not become too large or have a distorted shape.

If the above performances (1) and (2) are not satisfied, high quality printed matter cannot be obtained. For example, when the first performance is not satisfied, not only the contamination occurs but also bleeding (bleeding) occurs at a boundary portion of different colors in multicolor printing. If the second performance is not satisfied, the print density decreases and the ink is absorbed along the fibers on the paper surface, resulting in whisker-like bleeding (feathering).

Generally, in the case of a coated paper type ink jet recording medium, since the porous ink receiving layer is provided on the substrate sheet, it is relatively easy to achieve both the first and second performances described above. Can be achieved together. In contrast,
Since the plain paper type inkjet recording medium has no ink receiving layer, or has very few ink receiving layers, it is difficult to achieve both of the above performances at the same time.

In recent years, however, the use of plain paper type ink jet recording media has been expanding, and it has become necessary to print on plain paper types with high image quality comparable to that of coated paper types. Came. In response to such requirements, in a plain paper type inkjet recording medium, a base paper mainly composed of cellulose pulp,
An ink jet recording medium has been proposed in which a solution containing a styrene acrylic sizing agent and a water-soluble polymer is applied and dried to reduce feathering and uneven density of a solid print portion (Japanese Patent Laid-Open No. 8-216505). Gazette). Further, JP-A-2-188287 discloses an inkjet recording sheet obtained by coating or impregnating a coating material in which fine particle anhydrous silica and a cationic polymer are mixed.

However, even in these ink jet recording media, both the first performance and the second performance described above are satisfied at the same time, the problems of bleeding and feathering are solved at the same time, and the printing density is increased. I couldn't. Further, generally, when the size of the inkjet recording medium is increased, the ink droplets on the recording medium do not spread widely, so that feathering becomes smaller but ink absorption becomes slower and bleeding becomes larger. On the contrary, if the size of the inkjet recording medium is reduced, the ink absorption will be faster and the bleeding will be smaller, but the lateral absorption of the recording medium will also be larger.
Feather ring becomes larger. That is, feathering and bleeding are contradictory properties, and it is not possible to satisfy both by merely adjusting the size of the inkjet recording paper.

[0008]

The inventors of the present invention have diligently studied an ink jet recording medium for plain paper which satisfies both the first and second performances described above, and as a result, in producing an emulsion. By using the synthetic emulsion obtained by sufficiently reducing the amount of the surfactant to be used, the amount of the surfactant to be contained in the ink receiving layer can be sufficiently reduced, which is excellent. The present invention has been achieved by finding that various results can be obtained. Therefore, an object of the present invention is to provide a plain paper type inkjet recording medium which has a high print density and does not cause bleeding and feathering.

[0009]

The above objects of the present invention are as follows.
An ink jet recording medium, wherein at least one surface of a base paper is coated or impregnated with a coating solution containing a water-soluble polymer, a sizing agent, and a synthetic resin emulsion as a main component,
The present invention is achieved by a plain paper type inkjet recording medium, wherein the synthetic resin emulsion is an emulsion prepared by using 1.5 parts by weight or less of a surfactant with respect to 100 parts by weight of a polymerizable monomer. . In the present invention, in particular, in the coating liquid, (weight% of the surfactant contained in the synthetic resin emulsion) × (weight% of the synthetic resin emulsion in the coating liquid) is relative to the coating liquid. It is preferably 300 ppm or less, whereby a recording medium capable of realizing higher printing density can be obtained.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The base paper used in the present invention is an uncoated paper made of wood cellulose fiber as a raw material, and the paper is mainly composed of papermaking pulp. Examples of papermaking pulp include chemical pulp such as LBKP and NBKP, and G
Examples thereof include mechanical pulp such as P and TMP, and waste paper pulp, but the present invention is not particularly limited thereto, and they can be used in combination as necessary. The uncoated paper means a paper that does not have a coating layer containing a pigment on its surface.

In the present invention, various kinds of internal additives such as fillers, sizing agents, and paper strengthening agents to be internally added to the base paper are not particularly limited, and may be appropriately selected from known fillers and various internal additives. Can be used. Further, if necessary, a defoaming agent, a pH adjusting agent, a dye or a colored pigment for adjusting the hue, a fluorescent dye for improving the visual whiteness, etc. can be internally added.

The water-soluble polymer used in the coating liquid of the present invention is
It can be appropriately selected from known resins that are soluble in water and have film-forming properties. Specific examples thereof include starch, oxidized starch, phosphate esterified starch, cationized starch, fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, cation-modified polyvinyl alcohol, silanol-modified polyvinyl alcohol, anion-modified polyvinyl alcohol, and casein. I can do things. In the present invention, it is preferable to use polyvinyl alcohol or a modified product thereof from the viewpoint of increasing the printing density.

The synthetic resin emulsion of the present invention is a liquid in which fine particles of synthetic resin are dispersed in an aqueous solvent. Usually, a surfactant, a protective colloid, etc. are provided so that the fine particles of synthetic resin do not stick to each other to form a lump. Is blended.
In addition, as a method for producing a synthetic resin emulsion, generally, emulsion polymerization, suspension polymerization, dispersion polymerization and the like can be mentioned. Among them, the emulsion polymerization method using a surfactant (emulsifier) is such as a particle size. Since it is easy to control, it is suitable for stably producing a synthetic resin emulsion. However, since it is difficult to remove the surfactant from the emulsion-polymerized synthetic resin emulsion, in the present invention, it is necessary to sufficiently reduce the amount of the surfactant to be used especially at the time of charging the raw materials. There is a soap-free type method that does not use an emulsifier in the emulsion polymerization method,
In this case as well, it is common to add a surfactant in order to stabilize the final product.

In the synthetic resin emulsion used in the present invention, the amount of the surfactant used in the production is
It is necessary to be 1.5 parts by weight or less, and particularly preferably 1.0 parts by weight or less, relative to 100 parts by weight of the polymerized monomer. The composition of the synthetic resin emulsion and the method for preparing the synthetic resin emulsion are not particularly limited as long as aggregation does not occur during the production of the synthetic resin emulsion, in the coating liquid, or on the pulp fiber surface of the base paper. The synthetic resin emulsion has an effect of providing voids in the ink receiving layer that promote ink absorption, as described later.

The following are polymerizable monomers that can be used in the production of the synthetic resin emulsion used in the present invention,
Examples of surfactants (emulsifiers) and initiators are given. Examples of the polymerizable monomer include polymerized monomers such as aliphatic conjugated diolefin-based monomers, vinyl cyanide-based monomers, mono-olefin-based aromatic monomers, ethylenically unsaturated carboxylic acid alkyl ester monomers, and olefin-unsaturated carboxylic acid monomers. In the present invention, these may be used alone or in combination of two or more kinds. Specific examples of these polymerizable monomers include, for example, butadiene, isoprene, 2-chlorobutadiene, acrylonitrile, styrene, α-methylstyrene, chlorostyrene, dimethylstyrene,
Methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylic acid-
2-ethylhexyl, (meth) acrylic acid, crotonic acid, maleic acid, maleic acid alkyl monoester, fumaric acid, fumaric acid alkyl monoester, itaconic acid, itaconic acid alkyl monoester, glycidyl acrylate, hydroxyethyl acrylate, acrylic Examples thereof include hydroxypropyl acid, acrylamide, N-methylolacrylamide, N-methoxyacrylamide, vinyl acetate and the like.

The surfactant used in the production of the synthetic resin emulsion used in the present invention can be appropriately selected from known substances. Specific examples of such a surfactant include anionic surfactants such as alkyl sulfonate, alkyl benzene sulfonate, alkyl allyl sulfonate, alkyl sulfate, alkyl naphthalene sulfonate, alkyl saxnate sulfonate, diphenyl ether alkyl sulfonate, and polyoxyethylene alkyl ether. , Nonionic surfactants such as polyoxyethylene alkyl allyl ether and polyoxyethylene aliphatic ester, cationic surfactants such as monoalkyl ammonium chloride, dialkyl ammonium chloride, ethylene oxide adduct ammonium chloride, etc. Alternatively, two or more kinds may be used in combination. It is preferable to use anionic surfactants because nonionic surfactants may affect as environmental hormones and cationic surfactants may need to address toxicity. . Among the anionic surfactants,
Lauryl sulfate sodium salt, sodium dodecylbenzenesulfonate, and sodium dodecyl sulfate can be widely used in the present invention because they are compatible with most monomers.

Examples of the polymerization initiator include potassium persulfate, sodium persulfate, ammonium persulfate,
Hydrogen peroxide, diisobutylbenzoyl peroxide,
At least one oxidizing agent such as lauryl peroxide and cement hydroperoxide can be used, and these oxidizing agents can be used in combination with sodium sulfite, sodium bisulfite, sodium thiosulfate and the like.

The ink jet recording medium of the present invention contains the coating liquid containing the above-mentioned main component in a solid content of 0.5 per surface.
It is preferably applied so as to have a concentration of up to 5.0 g / m ² . With a coating amount within this range, a recording medium having a texture similar to that of plain paper can be obtained. Coating amount is 0.5
If it is less than g / m ² , the ink cannot be retained on the paper surface, and the resolution tends to decrease and the print density tends to decrease. On the other hand, when the coating amount is more than 5.0 g / m ^2, not only the texture of plain paper cannot be obtained, but also the ink absorbing capacity becomes excessive and the print density tends to be lowered.

In the present invention, a known sizing agent is added to the coating liquid. The sizing agent used in the present invention is, for example,
A styrene-acrylic sizing agent, an acrylic olefin sizing agent, a maleic acid sizing agent, a silicone-based water repellent, a fluorine-based water repellent, and the like can be appropriately selected and used. In the present invention, the Steckigt sizing degree is adjusted by selecting the addition amount and type of the sizing agent. Especially (Steecht size degree (seconds) /
(Basis weight (g / m ² )) It is preferable to adjust the value of ² × 1000 to be 1 to 10.

If the above value is less than 1, the ink permeation speed increases, and the ink may permeate into the inside of the base paper to lower the print density. Further, the spread of the ink on the surface of the recording medium becomes large, and the ink may diffuse along the fibers to increase the feathering. On the other hand, 10
If it exceeds, the penetration speed of the ink becomes slow, and there is a strong tendency that ink droplets stay on the surface for a long time. Therefore, in the case of multicolor recording, ink droplets of different colors may be mixed on the surface of the recording medium, and bleeding may increase. In the inkjet recording medium of the present invention, the Steckigt sizing degree (second) /
A particularly preferable value of (grammage (g / m ² ) of recording medium) ² is 3 to 8. Within this range, the feathering and the bleeding are well balanced, the printing density is high, and high quality printed matter can be obtained. In the present invention, the sizing degree can be adjusted by the addition amount and / or type of the sizing agent.

Dyes, water retention agents, water resistance agents, fluorescent whitening agents, pH adjusters, defoamers, lubricants, preservatives, surfactants, conductive agents, etc. are commonly used in the coating liquid. Additives may be contained. Further, it is preferable that the above coating liquid does not contain a pigment relating to ink absorption (specifically, fine powder silica, porous pigment such as alumina and colloidal silica, alumina sol). When such a pigment is added to the coating liquid, the ink is absorbed by the pigment and the printing density is lowered.

The mixing ratio of the water-soluble polymer to the synthetic resin emulsion in the present invention is preferably 5 parts by weight or more, and further 10 to 100 parts by weight, based on 100 parts by weight of the water-soluble polymer. Preferably there is. If the blending amount of the synthetic resin emulsion is 5 parts by weight or less with respect to 100 parts by weight of the water-soluble polymer, feathering is likely to occur. Further, if the blending ratio is more than 100 parts by weight, powder may fall off during cutting.

The surfactant derived from the synthetic resin emulsion in the coating liquid is preferably 300 ppm or less, and particularly preferably 250 ppm or less. By reducing the amount of the surfactant in the coating liquid, it is possible to balance feathering and bleeding when the print density is increased.

In the present invention, the particle size of the synthetic resin emulsion is not particularly limited, but is preferably 100 nm or more. If the particle size of the synthetic resin emulsion is smaller than 100 nm, it is necessary to increase the amount of the surfactant used to stabilize the synthetic resin emulsion. This is because the effect will be lost. It is considered that the role of the synthetic resin emulsion in the present invention is to make the film of the water-soluble polymer discontinuous and thereby generate apparent voids. Therefore, the minimum film-forming temperature of the synthetic resin emulsion is 50 ° C. or higher, preferably 70 ° C. or higher, and it is preferable that the synthetic resin film is not formed during the normal production of the inkjet recording medium.

The ink jet recording medium of the present invention is produced by a known impregnation method or coating method such as a method of impregnating the above-mentioned coating liquid on the base paper and then drying, or a method of coating on the surface of the base paper and then drying. be able to. As the impregnation method, for example, an impregnation type size press device can be used, and as the coating method, various blade coaters, roll coaters, air knife coaters, bar coaters, curtain coaters, gravure coaters, gate roll coaters, etc. A device can be used.

As a drying method, for example, a method using a usual heating means such as a steam heater, a gas heater, an infrared heater, an electric heater, a hot air heater, a microwave or a cylinder dryer is used, and after drying, it is necessary. Accordingly, smoothness can be imparted by a finishing process such as a super calender and a soft calender. In addition, in the present invention, general paper processing means can be appropriately used.

By doing so, both a feathering and a bleeding can be solved, and a good ink jet recording medium having a high printing density can be obtained. The reason for this is not clear, but while suppressing the lateral spread of the ink by adding a sizing agent, in addition to the swelling property of the water-soluble polymer itself, the voids of the water-soluble polymer film formed by the synthetic resin emulsion. From the above effect, it is considered that since the ink permeation speed into the recording medium is improved, the ink droplets ejected onto the recording medium do not spread laterally and can permeate into the recording medium appropriately. However, when the amount of the surfactant used for producing the synthetic resin emulsion is large, the effect of the sizing agent is lost, so that feathering and print density are reduced.

[0028]

INDUSTRIAL APPLICABILITY The ink jet recording medium of the present invention is an ink jet recording medium suitable for multi-color recording, which has less feathering and bleeding and can obtain a recorded image with high printing density. Further, since the texture of plain paper is maintained, it can be used for electrophotographic recording and general writing with a pencil or the like.

[0029]

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto. The "parts" and "%" in the examples are "parts by weight" and "% by weight" of the solid content unless otherwise specified.

(Production of Synthetic Resin Emulsion A) Deionized water 75 was placed in an autoclave equipped with a stirrer, which was replaced with nitrogen.
Parts, 0.05 parts of sodium lauryl sulfate and 0.6 parts of potassium persulfate were charged, and the temperature was raised to 70 ° C. On the other hand, 45 parts of deionized water, 0.5 part of sodium lauryl sulfate, 0.5 part of tertiary mercaptan, and a polymerizable monomer (10 parts of butadiene, 65 parts of styrene, and methyl methacrylate) were placed in another autoclave equipped with a stirrer and replaced with nitrogen. 20 parts, methacrylic acid 2 parts, itaconic acid 1 part, and acrylamide 2 parts) 100 parts in total were emulsified and dispersed, and the temperature was raised to 70 ° C. This emulsion was slowly and continuously charged into the above aqueous solution, and further polymerized while maintaining the temperature at 70 ° C. When the polymerization rate exceeded 98%, the emulsion was cooled to stop the reaction. Next, the pH was adjusted to 8 using a 25% aqueous sodium hydroxide solution, and steam stripping was performed to remove unreacted substances. Excess water was removed by vacuum using an evaporator and the solid content was adjusted to 48% to obtain a synthetic resin emulsion A.

(Production of Synthetic Resin Emulsion B) 75 g of deionized water was placed in an autoclave equipped with a stirrer and replaced with nitrogen.
Parts, 0.05 parts of sodium lauryl sulfate and 0.6 parts of potassium persulfate were charged, and the temperature was raised to 70 ° C. On the other hand, 45 parts of deionized water, 1.0 part of sodium lauryl sulfate, 0.5 part of tertiary mercaptan, and a polymerizable monomer (10 parts of butadiene, 65 parts of styrene, and methyl melamine) were placed in another autoclave equipped with a stirrer that was replaced with nitrogen. 20 parts of acrylate, 2 parts of methacrylic acid, 1 part of itaconic acid, and 2 parts of acrylamide) totaling 100 parts were emulsified and dispersed, and the temperature was raised to 70 ° C. This emulsion was slowly and continuously charged into the above aqueous solution, and polymerization was performed while maintaining the temperature at 70 ° C., and when the polymerization rate exceeded 98%, the mixture was cooled to stop the reaction. Next, the pH was adjusted to 8 using a 25% aqueous sodium hydroxide solution, and steam stripping was performed to remove unreacted substances. Excess water was removed by vacuum using an evaporator and the solid content was adjusted to 48% to obtain a synthetic resin emulsion B.

(Production of Synthetic Emulsion C) 75 parts of deionized water was placed in an autoclave equipped with a stirrer, which was replaced with nitrogen.
0.05 part of sodium lauryl sulfate and 0.6 part of potassium persulfate were charged, and the temperature was raised to 70 ° C. On the other hand, in another autoclave with a stirrer, which had been replaced with nitrogen, deionized water 4
5 parts, sodium lauryl sulfate 1.4 parts, tertiary mercaptan 0.5 parts, and polymerizable monomer (butadiene 10 parts, styrene 65 parts, methyl melacrylate 20)
Parts, methacrylic acid 2 parts, itaconic acid 1 part, and acrylamide 2 parts), a total of 100 parts was emulsified and dispersed, and the temperature was raised to 70 ° C. This emulsion was slowly and continuously charged into the above aqueous solution, and polymerization was performed while maintaining the temperature at 70 ° C., and when the polymerization rate exceeded 98%, the mixture was cooled to stop the reaction. Then, the pH was adjusted to 8 with a 25% aqueous sodium hydroxide solution, and steam stripping was performed to remove unreacted substances. Excess water was removed by vacuum using an evaporator,
The solid content was adjusted to 48% to obtain a synthetic resin emulsion C.

(Production of Synthetic Resin Emulsion D) 75 g of deionized water was placed in an autoclave equipped with a stirrer that was replaced with nitrogen.
Parts, 0.05 parts of sodium lauryl sulfate and 0.6 parts of potassium persulfate were charged, and the temperature was raised to 70 ° C. On the other hand, 45 parts of deionized water, 2.0 parts of sodium lauryl sulfate, 0.5 part of tertiary mercaptan, and a polymerizable monomer (10 parts of butadiene, 65 parts of styrene, and methyl melamine) were placed in another autoclave equipped with a stirrer and replaced with nitrogen. 20 parts of acrylate, 2 parts of methacrylic acid, 1 part of itaconic acid, and 2 parts of acrylamide) totaling 100 parts were emulsified and dispersed, and the temperature was raised to 70 ° C. This emulsion was slowly and continuously charged into the above aqueous solution, and the polymerization was continued while maintaining the temperature at 70 ° C. When the polymerization rate exceeded 98%, the mixture was cooled to stop the reaction. Then pH is adjusted using 25% caustic soda solution.
Was adjusted to 8 and steam stripping was performed to remove unreacted materials. Excess water was removed by vacuum using an evaporator and the solid content was adjusted to 48% to obtain a synthetic resin emulsion D.

(Preparation of base paper) Pulp slurry 1 made from hardwood bleached kraft pulp (freeness of 350 mlcsf)
8 parts of calcium carbonate as a filler, 0.05 part of internal sizing agent (Size Pine SA-862: trade name of Arakawa Chemical Co., Ltd.) and 0.5 part of cationic starch were added to 00 parts, and a twin wire type was added. After paper-making and drying with a paper machine of No. 2, machine calendering was carried out to prepare a base paper having a basis weight of 72 g / m ² .

Example 1. Add P to the base paper prepared as above.
A coating liquid containing 3% of VA (PVA 117, manufactured by Kuraray), 2.0% of synthetic resin emulsion A, and 0.25% of sizing agent (Polymaron KB, manufactured by Arakawa Chemical Co., Ltd.) in solid content was used to obtain 2 dry solids. An ink jet recording medium of Example 1 was prepared by impregnating and coating the solution to a size of 0.5 g / m ² using a size press machine and drying. The amount of the surfactant derived from the synthetic resin emulsion in this coating solution was 11
It was 0 ppm.

Example 2. On the base paper, PVA (PVA1
17, Kuraray) 3%, synthetic resin emulsion A2.0
% And sizing agent (Polymaron KB, Arakawa Chemical Co., Ltd.) 0.2
An ink jet recording medium of Example 2 was obtained by impregnating a coating liquid containing 5% of each solid content with a size press device so that the dry solid content was 0.9 g / m ^2, and drying. Was produced.

Example 3. On the base paper, PVA (PVA1
17, Kuraray) 3%, synthetic resin emulsion A2.0
% And sizing agent (Polymaron KB, Arakawa Chemical Co., Ltd.) 0.2
An ink jet recording medium of Example 3 was prepared by impregnating a coating liquid containing 5% of each solid content with a size press device so that the dry solid content would be 4.3 g / m ^2, and drying. Was produced.

Example 4. On the base paper, PVA (PVA1
17, Kuraray) 3%, synthetic resin emulsion B2.0
% And sizing agent (Polymaron KB, Arakawa Chemical Co., Ltd.) 0.2
An ink jet recording medium of Example 4 was prepared by impregnating a coating liquid containing 5% of each solid content with a size press device so that the dry solid content would be 2.5 g / m ^2, and drying. Was produced. The amount of the surfactant derived from the synthetic resin emulsion in this coating liquid was 210 ppm.

Example 5. On the base paper, PVA (PVA1
17, Kuraray) 3%, synthetic resin emulsion C2.0
% And sizing agent (Polymaron KB, Arakawa Chemical Co., Ltd.) 0.2
An ink jet recording medium of Example 5 was obtained by impregnating a coating liquid containing 5% of each solid content with a size press apparatus so that the dry solid content was 2.5 g / m ^2, and drying. Was produced. The amount of the surfactant derived from the synthetic resin emulsion in this coating liquid was 280 ppm.

Example 6. On the base paper, PVA (PVA1
17, Kuraray) 3%, synthetic resin emulsion C0.5
% And sizing agent (Polymaron KB, Arakawa Chemical Co., Ltd.) 0.2
An ink jet recording medium of Example 6 was obtained by impregnating a coating solution containing 5% of each solid content with a size press device so that the dry solid content was 2.5 g / m ^2, and drying. Was produced. The amount of the surfactant derived from the synthetic resin emulsion in this coating liquid was 70 ppm.

Example 7. On the base paper, PVA (PVA1
17, Kuraray) 3%, synthetic resin emulsion A8.0
% And sizing agent (Polymaron KB, Arakawa Chemical Co., Ltd.) 0.2
An ink jet recording medium of Example 7 was obtained by impregnating a coating solution containing 5% of each solid content with a size press device so as to obtain a dry solid content of 2.5 g / m ² , followed by drying. Was produced. The amount of the surfactant derived from the synthetic resin emulsion in this coating liquid was 430 ppm.

Example 8. On the base paper, PVA (PVA1
17, Kuraray) 3%, synthetic resin emulsion B4.0
% And sizing agent (Polymaron KB, Arakawa Chemical Co., Ltd.) 0.2
An ink jet recording medium of Example 8 was obtained by impregnating a coating solution containing 5% of each solid content with a size press device so that the dry solid content would be 2.5 g / m ^2, and drying. Was produced. The amount of the surfactant derived from the synthetic resin emulsion in this coating liquid was 410 ppm.

Comparative Example 1. On the base paper, PVA (PVA1
17, Kuraray) 3%, synthetic resin emulsion D2.0
% And sizing agent (Polymaron KB, Arakawa Chemical Co., Ltd.) 0.3
An inkjet recording medium of Comparative Example 1 was obtained by impregnating a coating solution containing 0% of each solid content with a size press device so that the dry solid content was 2.5 g / m ^2, and drying. Was produced. The amount of the surfactant derived from the synthetic resin emulsion in this coating liquid was 400 ppm.

Comparative Example 2. On the base paper, PVA (PVA1
17, a coating liquid containing 3% of Kuraray) and 0.25% of a sizing agent (Polymaron KB, manufactured by Arakawa Chemical Co., Ltd.) in solid contents, so that the dry solid content becomes 2.5 g / m ² The ink jet recording medium of Comparative Example 2 was prepared by impregnation coating using a pressing device and drying.

Comparative Example 3. The base paper itself used in Example 1 was used as the inkjet recording medium of Comparative Example 3. The constitutions and the Steckigt sizing degree of the ink jet recording media obtained in Examples and Comparative Examples are as shown in Table 1.
The Steckigt sizing degree was measured according to JIS-P8122.

[0046]

[Table 1] The inkjet recording media obtained in Examples and Comparative Examples were evaluated for print density, feathering and bleeding as follows, and the results are shown in Table 2.

(Print density) Printer (BJ-F21
0, a Canon product name) was used for solid printing (black), and after 24 hours, the printing density was measured with a Macbeth densitometer (RD918).

(Feathering) Printer (BJ-F
No. 210, a product name of Canon Inc.), a black thin line was printed and recorded, and visually judged. ◎ is good with little feathering and very little thickening of the upper line; ○ is good in a range where there is slight feathering and thickening of the line but there is no problem in practical use; △ is practical with feathering and thickening of the line There is a problem on the top; x means that the feathering and the thickening of the line are large and that the line is defective.

(Bleeding) Printer (BJ-F
No. 210, a product name of Canon Inc.), a black rectangle was recorded in the yellow solid part, and it was judged visually. ◎ is good with little bleeding at the boundary; ◯ is good in the range where there is a slight bleeding at the boundary but practically no problem; △ is bleeding at the boundary practically; x is the boundary It shows that the bleeding is large and defective.

[0050]

[Table 2] Table 2: Evaluation results The results in Table 2 demonstrate the effectiveness of the present invention.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takehiro Yoshimatsu             5-21-1 Oji, Kita-ku, Tokyo Nippon Paper Co., Ltd.             Company Product Research Center (72) Inventor Naruko Kumazawa             5-21-1 Oji, Kita-ku, Tokyo Nippon Paper Co., Ltd.             Company Product Research Center F-term (reference) 2C056 EA05 FC06                 2H086 BA15 BA21 BA31 BA34 BA35                       BA37

Claims (4)

[Claims] 1. An inkjet recording medium in which at least one surface of a base paper is coated or impregnated with a coating solution containing a water-soluble polymer, a sizing agent, and a synthetic resin emulsion as a main component, wherein the synthetic resin emulsion is A plain paper type ink jet recording medium, which is an emulsion produced by using 1.5 parts by weight or less of a surfactant with respect to 100 parts by weight of a polymerizable monomer. 2. In the coating liquid, (weight% of surfactant contained in synthetic resin emulsion) × (weight% of synthetic resin emulsion contained in coating liquid) is 300 p.
The plain paper type inkjet recording medium according to claim 1, which has a pm or less. 3. The plain paper type ink jet recording medium according to claim 1, wherein the water-soluble polymer is polyvinyl alcohol. 4. The coating amount of the coating liquid is 0.5 to 50 in terms of solid content.
The plain paper type inkjet recording medium according to any one of claims 1 to 3, having an amount of 5.0 g / m ² .