JP2006150942A - Sheet for inkjet recording - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet for inkjet recording capable of clearly printing a highly fine and precise image excellent in color developing properties even when either one of inks based on a dyestuff ink or a pigment ink is used, and in particular, to provide a matte type sheet for inkjet recording. <P>SOLUTION: The sheet for inkjet recording is provided with an ink receiving layer on a substrate. The sheet for inkjet recording comprises a pigment, an adhesive, an ink fixing agent, and a terpolymer comprising an alkyl (meth)acrylate, N-methylol acrylamide and styrene in the ink receiving layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an inkjet recording sheet.

The ink jet recording method in which ink is ejected from a fine nozzle toward the surface of the recording body to form an image on the surface of the recording body has low noise during recording, easy formation of a full color image, and high speed recording. It is widely used in terminal printers, facsimiles, plotters, form printing, and the like because it is possible and the recording cost is lower than other printing apparatuses.
In recent years, the demand for printed materials (inkjet printed materials) printed by the inkjet recording method has increased rapidly as media with a design property such as large posters, displays, and flyers. It is also used for large format posters.
Therefore, in addition to the sharpness of printing and high printing density (color development), inkjet recording sheets have higher recording characteristics, such as printed images that do not fade due to the influence of light, ozone in the air, etc. There are demands for characteristics such as (printing storage stability such as printing light resistance and printing ozone resistance), and that ink does not ooze out when water is applied (printing water resistance).

In general, water-based ink is used for printing in the ink jet recording system, and the water-based ink is classified into a dye ink using a dye and a pigment ink using a pigment.
At present, dye inks are mainly used from the viewpoint of image sharpness, and most of the commercially available inkjet recording sheets are for dye inks.
However, dye ink is easily oxidized by ultraviolet rays, ozone, and the like, and has low printing light resistance and printing ozone resistance. For this reason, it has been pointed out that ink-jet prints using dye inks have poor light storage properties, ozone resistance, etc., because the images are faded during display and the appearance is deteriorated. The use of pigment ink is increasing.
However, as described above, the pigment ink is inferior in image sharpness to the dye ink, and particularly when printed on an ink jet recording sheet for dye ink, there is a problem that the sharpness becomes very poor. .

Therefore, there is a demand for an ink jet recording sheet that exhibits excellent recording characteristics even when printed with either dye ink or pigment ink.
A method for containing a water-soluble metal salt in a coating liquid (see, for example, Patent Document 1) and a coating layer as an inkjet recording sheet exhibiting excellent suitability even when printed with either dye ink or pigment ink. A method of providing two or more layers (for example, refer to Patent Documents 2 to 5), a method for controlling the coating layer surface to a specific roughness (for example, refer to Patent Document 6), and a specific particle size in the coating layer. A method of using a coating layer made of a porous organic resin having a specific pore radius and pore volume and having a specific pH range (for example, patents) Reference 8) is proposed.
Japanese Patent Laid-Open No. 2002-274022 JP 2000-94831 A JP 2000-168228 A JP 2002-347330 A JP-A-10-278411 JP 2000-158804 A JP 2001-270238 A JP 2001-246841 A

  However, the ink jet recording sheet described in the above-mentioned patent document has a problem in color developability such as insufficient print density when either dye ink or pigment ink is used.

  The present invention has been made in view of the above circumstances, and provides an ink jet recording sheet that is excellent in color developability when any one of dye ink and pigment ink is used. In particular, the present invention provides a recording paper satisfying the above-mentioned quality in a mat type ink jet recording sheet.

As a result of repeated studies, the present inventors have found that these problems can be solved by blending a specific ternary copolymer, and have completed the present invention.
The present invention includes the following embodiments.
That is, an ink jet recording sheet having an ink receiving layer provided on a support, the ink receiving layer comprising a pigment, an adhesive, an ink fixing agent, and an alkyl (meth) acrylate, N-methylolacrylamide, and styrene. An ink-jet recording sheet comprising a terpolymer.
Here, the ink receiving layer preferably contains a water-soluble metal salt. Furthermore, the water-soluble metal salt is preferably zinc chloride and / or zinc sulfate.
The ink receiving layer preferably contains silica having a surface treated with a surfactant.

  INDUSTRIAL APPLICABILITY The present invention provides an ink jet recording sheet that is excellent in color developability when any of dye ink and pigment ink is used, and that enables high-definition images to be printed clearly. Sheets can be provided.

≪Layer structure≫
The ink jet recording sheet of the present invention comprises an ink receiving layer having a specific composition on a support.
In addition, you may provide the same ink receiving layer on both surfaces of a support body. In this case, clear printing can be performed on both sides of the inkjet recording sheet.
The ink receiving layer may be composed of a plurality of layers. An undercoat layer may be provided between the support and the ink receptive layer. On the ink receptive layer, an overcoat layer for increasing the storage stability or the surface glossiness as long as the recording properties of the ink receptive layer are not impaired. A gloss layer may be formed to increase the brightness.

≪Support body≫
The support is not particularly limited as long as it is a support that can be used as a normal inkjet recording sheet. Fine paper, art paper, coated paper, cast coated paper, foil paper, craft paper, baryta paper, Paper such as impregnated paper, vapor-deposited paper, resin film, resin is uniaxially stretched or biaxially stretched to form a paper-like layer, generally called synthetic paper, and one or more layers are laminated on a substrate layer such as paper Resin-coated paper, such as a laminated paper, a nonwoven fabric, a resin film bonded to a coated paper or a high-quality paper via an adhesive, or a paper laminated with a resin, is used.

≪Ink receiving layer≫
The ink receiving layer contains a ternary copolymer composed of a pigment, an adhesive, an ink fixing agent, and an alkyl (meth) acrylate, N-methylolacrylamide, and styrene. The ink receiving layer preferably contains at least one zinc compound selected from water-soluble metal salts, particularly zinc chloride and zinc sulfate.

[Pigment]
The pigment used in the ink receiving layer is not particularly limited as long as it is a pigment conventionally used in the coating layer of an inkjet recording sheet and the ink receiving layer. For example, silica, light calcium carbonate, heavy Calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, aluminum hydroxide, alumina, pseudoboehmite, lithopone, Inorganic pigments such as zeolite, hydrous halloysite, magnesium carbonate, magnesium hydroxide; acrylic or methacrylic resins, vinyl chloride resins, vinyl acetate resins, polyester resins, styrene-acrylic resins, styrene-butadiene resins, styrene- Isopre Organic pigments made of resins such as epoxy resins, polycarbonate resins, silicone resins, urea resins, melamine resins, epoxy resins, phenol resins, diallyl phthalate resins, etc. These pigments may be spherical or amorphous It may be nonporous or porous. These pigments may be used alone or in combination of two or more.

  Among these pigments, silica, alumina, pseudo-boehmite, light calcium carbonate, and zeolite are preferably selected because of excellent color developability and ink absorbability. Among these, silica, alumina, pseudo-boehmite are preferable, and silica is preferable. Most preferred.

  As silica, amorphous silica is preferred. The method for producing silica is not particularly limited, and may be produced by any method of an electric arc method, a dry method, and a wet method (precipitation method, gel method), but wet method silica is an ink jet recording for dye ink. This is preferable because it is suitable for both the ink-jet sheet and the ink-jet recording sheet for pigment ink.

When wet silica is used as silica, the average particle diameter of secondary particles of wet silica is preferably 2 to 12 μm, and more preferably 4 to 10 μm. When the average particle diameter is less than 2 μm, when this is used for an ink jet recording sheet for dye ink, the dye ink absorbability of the sheet tends to be lowered, and the light transmittance is further increased. There is a tendency that the light resistance of the recording with ink decreases or the strength of the coating film decreases. Further, when this is used for an ink jet recording sheet for pigment ink, there may be an adverse effect that the fixability of the pigment ink is lowered.
On the other hand, when the average particle diameter of the secondary particles of wet silica exceeds 12 μm, both the ink-jet recording sheet for dye ink and the ink-jet recording sheet for pigment ink have a noticeable decrease in image sharpness and surface roughness. There is a tendency that printing unevenness is likely to occur.
In addition, in this invention, the average particle diameter of a silica is a thing by the Cole counter method, and represents the volume average particle diameter measured by using as a sample what dispersed silica for 30 seconds in distilled water.

  In the present invention, it is preferable to use a pigment whose surface is treated with a surfactant for at least a part of the pigment contained in the ink receiving layer. That is, all of the pigments may be pigments whose surfaces are treated with a surfactant, and both pigments whose surfaces are treated with a surfactant and untreated pigments may be used. Since the untreated pigment is the same as the pigment explained above, the explanation is omitted.

As the pigment whose surface is treated with a surfactant, the same pigment as described above is used, and similarly, silica, alumina, pseudo-boehmite, light calcium carbonate and zeolite are preferably selected. Alumina and pseudoboehmite are preferred, and silica is most preferred.
The surfactant for treating the surface of the pigment is not particularly limited, but a nonionic surfactant is particularly preferable. Specific examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyethylene polyoxypropylene copolymer, polyoxyethylene polyoxypropylene alkyl ether, and the like. Among these, those having an HLB value of 8.0 to 15.0 are preferable, and those of 10.0 to 12.0 are more preferable.

As a method for treating the surface of the pigment with the surfactant, for example, a method described in JP-A-9-25440 can be employed. That is, it is possible to employ a dry mixing method in which a pigment, for example, wet process silica, and a surfactant, for example, a multi-chain nonionic surfactant, are mixed with a mixer such as a high-speed flow mixer. In this case, the surfactant may be directly added to the pigment and mixed, or the surfactant diluted with a volatile solvent such as ethanol may be added and mixed.
In addition, a wet processing method in which a predetermined amount of a surfactant, for example, a nonionic surfactant, is added to and mixed with an emulsified slurry liquid of a pigment, for example, wet method silica, followed by spray drying or the like can also be employed. . In the case of a wet processing method, if the surfactant is poorly soluble in water, it should be strongly dispersed in advance to form an emulsion, and this emulsion is added to the pigment emulsified slurry liquid and thoroughly stirred and mixed before drying. Is preferred.
Silica whose surface is treated with a surfactant by such a method is considered to be in a state where the surface is coated with the surfactant.

  The amount of the surfactant added to the silica is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 20 parts by mass per 100 parts by mass of the pigment. Preferably, when silica coated with a surfactant is blended in such a range, the color developability is improved and a clear image can be obtained.

〔adhesive〕
The adhesive used for the ink receiving layer is not particularly limited, and conventionally known adhesives generally used for inkjet recording can be used. Examples of such an adhesive include proteins such as casein, soybean protein, and synthetic protein; various starches such as starch and oxidized starch; polyvinyl alcohol and derivatives thereof; cellulose derivatives such as carboxymethylcellulose and methylcellulose; styrene-butadiene. Resin, conjugated diene resin such as methyl methacrylate-butadiene copolymer; acrylic resin that is a polymer or copolymer of acrylic acid, methacrylic acid, acrylic ester, methacrylic ester, etc .; ethylene-vinyl acetate copolymer And vinyl resins such as Of these, polyvinyl alcohol and derivatives thereof are particularly preferable because they are suitable for use in combination with a terpolymer composed of alkyl (meth) acrylate, N-methylolacrylamide and styrene. These adhesives may be used alone or in combination of two or more.

[Ink fixing agent]
The ink fixing agent used in the ink receiving layer is not particularly limited, and conventionally known ink fixing agents generally used for inkjet recording can be used. Examples of such an ink fixing agent include water-soluble metal salts and cationic polymers. These ink fixing agents may be used alone or in combination of two or more.

  Examples of water-soluble metal salts include 1) water-soluble salts of aluminum (nitrates, chlorides, acetates, sulfates, lactates, etc.) 2) water-soluble salts of magnesium (chlorides, sulfates, nitrates, acetic acid) 3) Water-soluble salt of sodium (nitrate, chloride, acetate, sulfate, lactate, etc.) 4) Water-soluble salt of potassium (nitrate, chloride, acetate, sulfate, Examples thereof include commercially available products such as water-soluble salts of zinc (chlorides, sulfates, nitrates, acetates, lactates, etc.).

Examples of the cationic polymer include 1) polyalkylene polyamines such as polyethylene polyamine and polypropylene polyamine or derivatives thereof, and 2) acrylic polymers having secondary amino groups, tertiary amino groups, and quaternary ammonium groups. 3) polyvinyl amine, polyvinyl amidine, 5-membered ring amidines, 4) dimethylamine - epichlorohydrin copolymer, 5) diallyldimethylammonium -SO ₂ copolymer, 6) diallylamine salt -SO ₂ copolymer, 7) Examples include dimethyldiallylammonium chloride polymer, 8) polymer of allylamine salt, 9) dialkylaminoethyl (meth) acrylate quaternary salt copolymer, 10) acrylamide-diallylamine copolymer, and the like.

Among these ink fixing agents, it is particularly preferable to contain a water-soluble metal salt. The combination of the water-soluble metal salt and the terpolymer composed of alkyl (meth) acrylate, N-methylolacrylamide and styrene is not clear for reasons, but the color developability is improved for both the dye ink and the pigment ink. When printing with pigment ink, a very clear image can be obtained.
Among water-soluble metal salts, zinc compounds are preferably selected because of their excellent ink absorbability and image sharpness, and zinc chloride and zinc sulfate are particularly preferred.

  3-40 mass parts is preferable with respect to 100 mass parts of pigments, and, as for the compounding quantity of water-soluble metal salt, More preferably, it adjusts in the range of 5-35 mass parts. When the amount of the water-soluble metal salt is less than 3 parts by mass, the color developability of the image, particularly the color developability of the image with the pigment ink is lowered, and when it exceeds 40 parts by mass, the ink absorptivity decreases, the printing unevenness, and the image sharpness. Deterioration of printing property and deterioration of printing water resistance are likely to occur.

[Ternary copolymer]
In the present invention, the ink receiving layer contains a terpolymer composed of alkyl (meth) acrylate, N methylolacrylamide, and styrene.
Here, examples of the alkyl (meth) acrylate include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, iso-propyl (meth) acrylate, and (meth) acrylic. N-butyl acid, iso-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-amyl (meth) acrylate, iso-amyl (meth) acrylate, hexyl (meth) acrylate, (meth ) 2-ethylhexyl acrylate, octyl (meth) acrylate, iso-nonyl (meth) acrylate, decyl (meth) acrylate and dodecyl (meth) acrylate, tridecyl (meth) acrylate, stearyl (meth) acrylate These may be used, and one or more of these may be used in appropriate combination. Of these, alkyl groups having 1 to 12 carbon atoms are particularly preferred from the viewpoint of production stability.

  The ternary copolymer preferably has a glass transition temperature of -80 to + 50 ° C, more preferably -50 to + 30 ° C. If it is less than −80 ° C., the ink absorbability tends to decrease, and if it exceeds + 50 ° C., the bending strength of the coating layer tends to be weakened.

  As for the compounding quantity of each component in this ternary copolymer, 5-90 mass parts is preferable with respect to 100 mass parts of the whole ternary copolymer, N-methylol acrylamide is 5-90 mass parts. 90 parts by mass is preferable, and styrene is preferably 5 to 90 parts by mass. When the alkyl (meth) acrylate is less than 5 parts by mass, the bending strength of the coating layer is weakened, and the coating layer is liable to be broken. Is likely to occur. If N-methylol acrylamide is less than 5 parts by mass, ink absorbency decreases and uneven printing tends to occur. If it exceeds 90 parts by mass, the bending strength of the coating layer is weakened, and the coating layer is broken or powdered off. It tends to happen. When the styrene is less than 5 parts by mass, the rubbing strength of the coating layer is weakened, and the powder of the coating layer is likely to fall off. . The terpolymer may be a block copolymer or a random copolymer.

  5-50 mass parts is preferable with respect to 100 mass parts of pigments, and, as for the compounding quantity of (meth) acrylic-alkyl-N methylol acrylamide-styrene copolymer, More preferably, it adjusts in the range of 10-30 mass parts. When the amount is less than 5 parts by mass, the surface strength of the coating layer becomes weak, and the coating layer is liable to fall off or be broken. When the amount exceeds 50 parts by mass, the ink absorbency is lowered and uneven printing tends to occur. .

  The blending amount of the terpolymer composed of alkyl (meth) acrylate, N-methylolacrylamide and styrene is preferably 40 to 160 parts by mass, and 80 to 120 parts by mass per 100 parts by mass of the adhesive. More preferred. Preferably, when the ternary copolymer of the present invention is blended in such a range, the color developability is improved and a clear image can be obtained.

[Other optional ingredients]
For the ink-receiving layer, thickeners, antifoaming agents, wetting agents, surfactants, colorants, antistatic agents, light fastness aids, UV absorbers, antioxidants used in general coated paper production Various auxiliary agents such as preservatives and preservatives are appropriately added.

≪Method for producing inkjet recording sheet≫
The ink receiving layer is formed by applying and drying the ink receiving layer coating liquid containing the various components described above on at least one surface of the support.
Although the coating amount of the ink receiving layer is not particularly limited, it may preferably be 2 to 30 g / ^{m 2,} and more preferably, 5 to 20 g / ^{m 2.}
If the coating amount is less than the above lower limit, ink absorbency, image sharpness, and print storage stability tend to be lowered, and if the coating amount is larger than the above upper limit, the coating strength and image sharpness tend to be lowered.
Note that a plurality of ink receiving layers may be laminated, and in this case, the ink receiving layer composition may be different between the layers.

Coating of the ink receiving layer can be formed by various known coating apparatuses such as a blade coater, an air knife coater, a roll coater, a bar coater, a gravure coater, a rod blade coater, a lip coater, a curtain coater, and a die coater. . After coating, finishing may be performed using a calendar such as a machine calendar, a super calendar, or a soft calendar.
Note that after the ink receiving layer is formed, for example, a cast gloss layer may be provided on the ink receiving layer.

According to the present invention, an inkjet recording sheet, particularly a mat type inkjet recording sheet, which is excellent in coating film strength, printing water resistance, printing density, ink absorbability, and excellent in color development of both dye ink and pigment ink. Can be provided. Furthermore, since it can be applied to a paper substrate using recycled paper recycled pulp as a support, it is possible to effectively use limited resources.
Further, the back surface of the ink jet recording sheet of the present invention can be subjected to adhesive processing to form a label, or a magnetic card or IC card can be obtained by combining magnetic processing or an IC chip.

  Hereinafter, the present invention will be described in more detail using examples, but the present invention is not limited to these examples. Moreover, unless otherwise indicated, "part" and "%" in an example are solid content except water, and show a mass part and mass%, respectively.

Example 1
[Preparation of surface-treated silica A]
900 g of wet silica (trade name: Fine Seal X-60, manufactured by Tokuyama Corporation) is suspended in water and slurried (about 10 to 15%), and a surfactant (polyoxyethylene lauryl ether, trade name: Neugen ET-102, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., HLB: 10.8) 100 g of an aqueous suspension was added and mixed with stirring for 1 hour. Subsequently, it was spray-dried and pulverized and classified to obtain surface-treated silica A of the present invention. The average secondary particle diameter of the obtained surface-treated silica A was 6 μm.

[Preparation of ink receiving layer coating solution]
Wet silica (manufactured by Tokuyama Corporation, trade name: Fine Seal X-60) as a pigment and 20 parts of the surface-treated silica A obtained above, and silyl-modified PVA (manufactured by Kuraray, trade name: R-1130) 20 as an adhesive 10 parts of an aqueous zinc sulfate solution as an ink fixing agent (manufactured by Wako Pure Chemical Industries, Ltd .: zinc sulfate heptahydrate dissolved in water and used as 5%), 10 parts of a terpolymer, n-butyl acrylate N methylol A coating liquid was prepared by mixing and dispersing 20 parts of an acrylamide-styrene copolymer (emulsion type) and water.

<Preparation of inkjet recording sheet>
An ink-receiving layer coating solution was applied to one side of a high-quality paper having a basis weight of 170 g / m ^{2 so} that the coating amount was 10 g / m ² and dried to prepare an ink jet recording sheet.
The following evaluation was performed about the obtained sheet | seat for inkjet recording. The results are shown in Table 1.

(Example 2)
Except for changing the zinc sulfate aqueous solution in the ink-receiving layer coating liquid of Example 1 to 10 parts of zinc chloride aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd .: zinc chloride heptahydrate dissolved in water and used as 5%). In the same manner as in Example 1, an inkjet recording sheet was produced.

(Example 3)
Except for changing the zinc sulfate aqueous solution in the ink receiving layer coating liquid of Example 1 to 10 parts of magnesium chloride aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd .: use magnesium chloride hexahydrate dissolved in water as 5%). In the same manner as in Example 1, an inkjet recording sheet was produced.

Example 4
The zinc sulfate aqueous solution in the ink receiving layer coating liquid of Example 1 was changed to 10 parts of a magnesium sulfate aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd .: magnesium sulfate heptahydrate dissolved in water and used as 5%). In the same manner as in Example 1, an inkjet recording sheet was produced.

(Example 5)
The ink fixing agent in the ink-receiving layer coating liquid of Example 1 is 5 parts of an aqueous zinc sulfate solution (manufactured by Wako Pure Chemical Industries, Ltd .: zinc sulfate heptahydrate dissolved in water and used as 5%) and dicyandiamide-polyethylene. An ink jet recording sheet was prepared in the same manner as in Example 1 except that the amine copolymer (trade name: Neofix IJ-117, manufactured by Nikka Chemical Co., Ltd.) was changed to 5 parts.

(Example 6)
Inkjet recording sheet in the same manner as in Example 1, except that the pigment in the ink-receiving layer coating liquid of Example 1 was changed to 100 parts of wet silica (trade name: Fine Seal X-60, manufactured by Tokuyama Corporation). Was made.

(Example 7)
The same as Example 1 except that the ternary copolymer in the ink-receiving layer coating liquid of Example 1 was changed to 8 parts of n-butyl acrylate-N methylolacrylamide-styrene copolymer (emulsion type). Thus, an inkjet recording sheet was prepared.

(Example 8)
Same as Example 1 except that the ternary copolymer in the ink receiving layer coating liquid of Example 1 was changed to 40 parts of n-butyl acrylate-N methylolacrylamide-styrene copolymer (emulsion type). Thus, an inkjet recording sheet was prepared.

Example 9
An ink jet recording sheet was prepared in the same manner as in Example 1 except that 10 parts of the zinc sulfate aqueous solution in the ink receiving layer coating liquid of Example 1 was changed to 5 parts.

(Example 10)
An ink jet recording sheet was prepared in the same manner as in Example 1 except that 10 parts of the zinc sulfate aqueous solution in the ink receiving layer coating liquid of Example 1 was changed to 35 parts.

(Example 11)
Except that the ternary copolymer in the ink-receiving layer coating liquid of Example 1 was changed to 20 parts of octyl acrylate-N methylolacrylamide-styrene copolymer (emulsion type), the same as Example 1 was carried out. An ink jet recording sheet was prepared.

(Example 12)
[Preparation of cationic fine pigment]
Commercially available vapor phase silica (trade name: Leolosil QS-30, average primary particle size 9 nm, specific surface area 300 m ² / g, manufactured by Tokuyama Co., Ltd.) was dispersed in water with a sand grinder and then nanomizer (trade name: nanomizer) , Manufactured by Nanomizer Co., Ltd.), and repeated pulverization and dispersion. After classification, a 10% dispersion having an average secondary particle size of 80 nm was prepared.
To this dispersion, 10 parts of diallyldimethylammonium chloride-acrylamide copolymer (trade name: PAS-J-81, manufactured by Nitto Boseki Co., Ltd.) as an ink fixing agent (cationic compound) was added, and pigment aggregation and After the viscosity of the dispersion was increased, pulverization and dispersion were repeated using a nanomizer again to prepare a 12% dispersion having an average secondary particle diameter of 300 nm to obtain a cationic fine pigment.

[Preparation of gloss layer lower layer coating solution]
100 parts of the above cationic fine pigment, 20 parts of polyvinyl alcohol (trade name: PVA145, manufactured by Kuraray Co., Ltd.) and 0.1 part of an antifoaming agent were mixed and dispersed to prepare a coating solution having a solid content concentration of 10%.
[Preparation of gloss layer upper layer coating solution]
Composite emulsion of acrylic emulsion having a glass transition point of 100 ° C. and colloidal silica (trade name: Aquabrid 906, manufactured by Daicel Corporation; acrylic emulsion and colloidal silica have a mass ratio of 20:80, and the average particle size of colloidal silica is 20 to 30 nm. , Emulsion particle size 40 nm) and 1 part of a release agent (potassium stearyl phosphate, trade name: Wopol 1800, manufactured by Matsumoto Yushi Co., Ltd.) were mixed and dispersed to prepare a coating solution.

<Preparation of inkjet recording sheet>
On the ink-receiving layer of the ink jet recording sheet obtained in Example 1, the gloss layer lower layer coating solution was coated and dried to an absolute dry mass of 5 g / m ^2. Formed.
On the lower layer of the gloss layer, the gloss layer upper layer coating solution is applied so as to have an absolute dry mass of 1 g / m ² , and in a wet state, pressed against a mirror drum having a surface temperature of 100 ° C. It was dried and finished to produce an ink jet recording sheet.

(Comparative Example 1)
Example except that the ternary copolymer in the ink-receiving layer coating liquid of Example 1 was changed to 20 parts of a vinyl acetate polymer (manufactured by Nissin Chemical Industry Co., Ltd., trade name: Vinibrand 1080, emulsion type). In the same manner as in Example 1, an inkjet recording sheet was prepared.

(Comparative Example 2)
Except that the ternary copolymer in the ink-receiving layer coating liquid of Example 1 was changed to 20 parts of an acrylic resin (Rohm and Haas, trade name: Primal P-376), the same as Example 1 Thus, an inkjet recording sheet was produced.

(Comparative Example 3)
The same as Example 1 except that the ternary copolymer in the ink receiving layer coating liquid of Example 1 was changed to 20 parts of SBR (manufactured by JSR, trade name: 0589, Tg: 0 ° C., emulsion type). Thus, an inkjet recording sheet was prepared.

(Comparative Example 4)
Except for changing the ternary copolymer in the ink-receiving layer coating liquid of Example 1 to 20 parts of a styrene-acrylic copolymer (manufactured by Clariant Polymer Co., Ltd., trade name: Mobile 880, Tg: 3 ° C., emulsion type). In the same manner as in Example 1, an inkjet recording sheet was produced.

(Comparative Example 5)
The same as Example 1 except that the ternary copolymer in the ink-receiving layer coating liquid of Example 1 was changed to 20 parts of a styrene polymer (manufactured by Daicel Finechem, trade name: Sebian A 47050, emulsion type). Thus, an inkjet recording sheet was prepared.

≪Evaluation≫
The printing density, bleed, surface strength and crease strength of the ink jet recording sheets obtained in each of the examples and comparative examples were evaluated by the methods shown below.
In the evaluation, printing on the inkjet recording sheet was performed as follows.
・ Printer A
Commercially available inkjet printer (manufactured by EPSON, trademark: PM-G800, ink: use of dye ink, printing mode: photo matte paper / high definition)
・ Printer B
Commercially available inkjet plotter (trade name: PX-9000, manufactured by EPSON, ink: pigment ink / matte black, printing mode: PXMC premium matte paper / clean)
・ Printer C
Commercially available inkjet plotter (manufactured by HP, trademark: DesignJet 5500PS, ink: pigment ink used, print mode: highest quality)

[Print density]
An image issued by the Japanese Standards Association (“High-Definition Color Digital Standard Image XYZ / JIS-SCID”, identification symbol: S6, image name: color chart) is printed on three printers A, B, and C. For the highest color tone portion, the print density was measured with RD-914 manufactured by Guretag Macbeth.

[Nijimi]
An image ("High-definition color digital standard image XYZ / JIS-SCID", identification symbol: S6, image name: color chart) issued by the Japanese Standards Association is printed on printer A, and the degree of blurring is evaluated by sensory evaluation. , ◯-, △, and × (○: best, ○-: slightly inferior but within practical range, △: inferior, x: most inferior. evaluated.

[Surface strength]
The surface of each inkjet recording sheet is rubbed with a nail, and its strength is evaluated by sensory evaluation in four stages of ○, ○ −, Δ, and × (○: best, ○ −: slightly inferior, but within practical range, Δ: Inferior, x: Most inferior.

[Fracture strength]
Each ink jet recording sheet is folded in four, and the cracked state of the coating layer at the corner portion folded in four is evaluated by sensory evaluation in four stages of ○, ○ −, Δ, × (○: most excellent, ○ −: Slightly inferior, but within practical range, Δ: Inferior, ×: Inferior, ○ − or higher is the level that can withstand practical use.

As is apparent from Table 1, Examples 1 to 3 wherein the ink receiving layer containing a pigment, an adhesive, and an ink fixing agent contained a terpolymer composed of alkyl (meth) acrylate, N-methylolacrylamide, and styrene. The No. 12 ink jet recording sheet had a high printing density with respect to both the dye ink and the pigment ink, had excellent color developability, and was a clear image. Moreover, it was excellent also in terms of bleeding, surface strength, and bending strength.
On the other hand, the inkjet recording sheets of Comparative Examples 1 to 5 that did not use the ternary copolymer of the present invention had a low printing density, particularly for dye inks, and were inferior in image sharpness.

Claims (4)

  An ink jet recording sheet having an ink receiving layer provided on a support, wherein the ink receiving layer includes a pigment, an adhesive, an ink fixing agent, and a ternary comprising (meth) acrylic acid alkyl, N methylolacrylamide, and styrene. An ink jet recording sheet comprising a copolymer.   2. The ink jet recording sheet according to claim 1, wherein the ink receiving layer contains a water-soluble metal salt.   The inkjet recording sheet according to claim 2, wherein the water-soluble metal salt is zinc chloride and / or zinc sulfate.   The ink jet recording sheet according to any one of claims 1 to 3, wherein the ink receiving layer contains silica having a surface treated with a surfactant.