JP2019073833A - Coated paper for printing - Google Patents

Abstract

To provide a coated paper for printing having sufficient whiteness, tone jump resistance, color density unevenness resistance, and fogging resistance.SOLUTION: The coated paper for printing contains a base paper and a coating layer on at least one side of the base paper: in the coating layer, the outermost coating layer positioned at the outermost from the base paper as the standard contains a white pigment, a binder and a fluorescent dye; in the outermost coating layer, at least 2 kinds of the white pigment contains kaolin and calcium carbonate; a mass ratio of kaolin and calcium carbonate in the outermost coating layer (kaolin:calcium carbonate) is 1:9-6:4; at least 2 kinds of the binder contains styrene-butadiene copolymer resin and starch; and a mass ratio of the styrene-butadiene copolymer resin and the starch in the outermost coating layer (styrene-butadiene copolymer resin:starch) is 6:4-9:1.SELECTED DRAWING: None

Description

  The present invention relates to a coated paper for printing that can be printed by an inkjet printer while it is a coated paper for printing for offset printing.

The ink jet recording method is a method of recording by forming ink dots by discharging ink droplets from a fine nozzle onto a recording sheet and causing the ink droplets to land on the sheet.
Ink jet recording systems are used in small printers for home and SOHO, wide format printers used in POP and poster production, and on demand printers used in the production of commercial prints. The coated paper for printing used has various glossiness from mat tone to gloss tone. Coated paper for printing for producing commercial printed matter such as business documents, DM, books, booklets, flyers, brochures, catalogs, and photographic paper developed as a substitute for silver salt photography in the inkjet recording system, printed matter In terms of cost, print productivity and print handling, the required quality is different.

A white pigment, an adhesive, and a fluorescent brightening agent on at least one surface of a base paper mainly comprising pulp as a coated paper for printing having sufficient whiteness and ink receptivity and excellent printing strength. And the coated amount of the coating layer is 1 g / m ² or more and 5 g / m ² or less in terms of solid content per one side of the base paper, and the white color 5% by mass or more and 35% by mass or less of the pigment is kaolin, and contains 4.5% by mass or more and 11% by mass or less of polyvinyl alcohol having a degree of polymerization of 1000 to 2000 as an adhesive to the white pigment On the other hand, coated printing papers characterized in that the adhesive is contained in an amount of 20% by mass to 40% by mass are known (for example, see Patent Document 1).

Printing plate printers, such as offset printers and letterpress printers, require a "plate" on which a printed image is formed. On the other hand, on-demand printers do not require "plates." That is, in an on-demand printer, the image forming apparatus prints directly on a sheet of paper along with digital information on the image.
There are on-demand printers, i.e., inkjet printers, that use an inkjet recording scheme. Examples of the inkjet printer include Truepress Jet from SCREEN Graphic Solutions, Inc., MJP series from Miyakoshi, Prosper and VERSAMARK from Kodak, JetPress from Fujifilm, ColorInkjetWebPress from Hewlett-Packard, and the like.

  Although such an inkjet printer depends on printing conditions, it has a color printing speed as high as 10 times to several tens times and a printing speed of 15 m as compared with small-sized inkjet printers for home and SOHO and wide format inkjet printers. / Min or faster, faster than 100 m / min. For this reason, inkjet printers are distinguished from small-sized inkjet printers and wide-format inkjet printers for home and SOHO.

Unexamined-Japanese-Patent No. 2017-057528

With the spread of on-demand printers, coated paper for printing needs to correspond to not only printing plate printers but also on-demand printers. In particular, it is necessary to be applicable to an offset printing machine often used for the production of commercial printed matter and an ink jet printing machine.
In an offset printing press, ink attached to a printing plate is transferred onto a coated printing paper in contact via a blanket and transferred to produce a printed matter. An inkjet printer discharges ink droplets onto coated printing paper from fine nozzles that are not in contact with the paper to produce printed matter. Because of such differences in printing mechanism, the ink of the offset printing press is tacky and has a high colorant content concentration. The ink of the inkjet printer is fluid and has a low colorant content concentration.

The coated paper for printing for the conventional offset printing press, when used in an ink jet printing press, is a state in which jumps are recognized in the gradation of the printing part that should originally form smooth gradation in the printing part having gradual tone change , And so-called "tone jump" may occur. This phenomenon is caused by the fact that the ink jet printer expresses the gradation with a collection of minute ink droplets, and the ink fixability of the coated paper for printing with respect to the landed ink droplets, the ink absorbability and the ink drying property, etc. Is thought to be caused by environmental factors. The phenomenon of tone jump can be improved by image processing of the ink jet printer or control of ink drops. However, improvement is also desired by paper. In addition, color density unevenness may occur in a single color printing portion. “Color density unevenness” means that as the printing speed of the ink jet printer becomes faster, the ink absorption of the coated paper for printing partially varies, and as a result, a portion of the printing portion that should be originally formed in a single color Is a phenomenon in which light and shade of color are visually recognized. In addition, the color of the printed portion may become dull and cause a decrease in saturation. In general, physical elements constituting a color include "hue", "saturation" and "density", and "saturation" and "density" are different elements.
These are considered to be due to the difference between the printing method and ink of the offset printer and the ink jet printer. Tone jumps and color density irregularities reduce the value of commercial prints.

An object of the present invention is to provide a coated paper for printing having the following qualities for an inkjet printer, aiming to be able to print with the inkjet printer while being a coated paper for printing having suitability for offset printing. It is.
(1) Having sufficient whiteness.
(2) Tone jump is suppressed in the print portion having gradual tone change (tone jump resistance).
(3) Suppression of color density unevenness of a single color print portion (color density unevenness resistance).
(4) A reduction in saturation of the printed portion is suppressed (damp resistance).

As a result of intensive studies conducted by the inventor, the object of the present invention is achieved by the following.
[1] A base paper and a coating layer on at least one side of the base paper, and an outermost coating layer positioned outermost with respect to the base paper in the coating layer contains at least a white pigment, a binder and a fluorescent dye In the outermost coating layer, at least two of the white pigments contain kaolin and calcium carbonate, and the content ratio (kaolin: calcium carbonate) in the outermost coating layer of kaolin and calcium carbonate is 1: 9 to 6: 4 and at least two of the binders contain a styrene-butadiene copolymer resin and a starch, and the content ratio in the outermost coating layer of a styrene-butadiene copolymer resin and a starch (styrene -Coated coated paper having a butadiene copolymer resin: starches of 6: 4 to 9: 1.

[2] The content of the fluorescent dye in the outermost coating layer is not less than 0.06 parts by mass and not more than 0.25 parts by mass with respect to 100 parts by mass of the white pigment in the outermost coating layer per one side. The coated paper for printing as described in 1].

  According to the present invention, it is possible to provide a coated paper for printing having sufficient whiteness and having tone jump resistance, color density unevenness and dulling resistance.

The present invention will be described in detail below.
The coated paper for printing of the present invention has a base paper and a coated layer on at least one side of the base paper. The outermost coating layer positioned outermost with respect to the base paper in the coating layer is kaolin and calcium carbonate as at least two of white pigments, styrene-butadiene copolymer resin and starches as at least two of binders, And at least a fluorescent dye.
In the present invention, “having a coating layer” refers to a sheet having a clear coating layer that can be distinguished from a base sheet when a cross section of the sheet is observed by an electron microscope. For example, the resin component and the polymer component are coated, and the coated component is a small amount and absorbed in the base paper, and as a result, a clear layer which can be distinguished from the base paper when the cross section of the paper is observed by an electron microscope. When it does not have it, it does not correspond to "having a coating layer".

  The base paper is a chemical pulp such as LBKP (Leaf Bleached Kraft Pulp), NBKP (Needle Bleached Kraft Pulp), GP (Groundwood Pulp), PGW (Pressure GroundWood pulp), RMP (Refiner Mechanical Pulp), TMP (ThermoMechanical Pulp), CTMP Light calcium carbonate, ground calcium carbonate, at least one kind of pulp selected from mechanical pulps such as (ChemiThermoMechanical Pulp), CMP (ChemiMechanical Pulp), CGP (ChemiGroundwood Pulp), and recycled paper pulp such as DIP (DeInked Pulp) Various fillers such as talc, clay and kaolin, as well as various additives such as sizing agent, fixing agent, retention agent, cationic agent such as cationic resin and polyvalent cation salt, paper strength agent, etc. It is a papermaking made from paper stock. Furthermore, the base paper includes high-quality paper obtained by subjecting papermaking paper to calendering, surface sizing with starch, polyvinyl alcohol or the like, or surface treatment. Further, the base paper includes high quality paper which has been subjected to surface sizing or surface treatment and then calendered.

  In the stock, other additives such as pigment dispersants, thickeners, flow improvers, antifoams, foam inhibitors, mold release agents, foaming agents, penetrants, colored dyes, colored pigments, UV absorption One or more of an agent, an antioxidant, an antiseptic agent, an anti-biocide, a water proofing agent, a wet strength agent, a dry strength agent, etc., within the range not impairing the desired effect of the present invention, It can be suitably blended.

The coating layer can be provided on at least one side of the base paper by coating and drying the coating layer coating liquid. The coating layer is one layer or two or more layers. In the coating layer, the coating layer located outermost with respect to the base paper is referred to as the outermost coating layer. When the coating layer is one layer, the coating layer is the outermost coating layer. When the coating layer is two or more layers, the coating layer present between the base paper and the outermost coating layer is not particularly limited with respect to the presence or absence of each of the white pigment, the binder and the various additives, and the type thereof.
The respective coating amounts of the coating layer are not particularly limited. The preferable coating amount is in the range of 5 g / m ² or more and 30 g / m ² or less per one side on a dry solid basis. When the coating layer is two or more layers, it is the value of those totals. When the coating layer is two or more layers, it is preferable that the outermost coating layer occupies 70% by mass of the coating amount per one side in dry solid content.

  The coated layer may be provided on one side or both sides of the base paper. In the case of one side, the base paper may have a conventionally known back coat layer on the side opposite to the side having the coating layer.

  The method for providing the coating layer on the base paper is not particularly limited. For example, the method of coating and drying a coating layer coating liquid can be mentioned using a conventionally well-known coating apparatus and drying apparatus in the papermaking field. Examples of the coating apparatus include a comma coater, a film press coater, an air knife coater, a rod blade coater, a bar coater, a blade coater, a gravure coater, a curtain coater, an E bar coater, a film transfer coater and the like. Examples of drying devices include various drying devices such as linear tunnel dryers, arch dryers, air loop dryers, hot air dryers such as sine curve air float dryers, infrared heating dryers, dryers using microwaves, etc. Can.

The coated layer can be calendered.
Calendering is a process of averaging smoothness and thickness by passing paper between rolls. As an apparatus of a calendering process, a machine calendar, a soft nip calendar, a super calender, a multistage calendar, a multi nip calendar etc. can be mentioned, for example. The coated paper for printing of the present invention does not include the coated paper for printing in which the outermost coating layer is cast-treated.

  The outermost coating layer contains kaolin and calcium carbonate as at least two types of white pigments. The mass ratio of kaolin to calcium carbonate in the outermost coating layer is kaolin: calcium carbonate = 1: 9 to 6: 4. Calcium carbonate is preferably ground calcium carbonate from the viewpoint of printability for an ink jet printer.

The outermost coating layer can contain conventionally known white pigments in addition to kaolin and calcium carbonate. Examples of conventionally known white pigments include talc, satin white, lithopone, titanium oxide, zinc oxide, silica, alumina, aluminum hydroxide, inorganic white pigments such as activated white clay and diatomaceous earth, and organic white pigments such as plastic pigments. It can be mentioned. The outermost coating layer can be contained in combination with kaolin and calcium carbonate by combining one or more of these white pigments.
The proportion of kaolin and calcium carbonate in the white pigment of the outermost coating layer is preferably 80% by mass or more.

  The outermost coating layer contains a styrene-butadiene copolymer resin and starches as at least two of the binders.

Starches are polysaccharides in which glucose is polymerized by glycosidic linkage and polysaccharides in which glucose is polymerized by glycosidic linkage in which the hydroxyl group of glucose is modified by various substituents. Examples of starches include starches, oxidized starches, enzyme-modified starches, etherified starches, cationic starches, esterified starches such as amphoteric starches, dialdehyde starches, phosphated starches and urea phosphated starches, hydroxyethylated Examples include starch, as well as hydroxybutylated starch and the like. The starches are preferably urea phosphated starches.
Urea phosphate esterified starch is starch which has a phosphate ester group and a carbamate ester group in glucose. Examples of a method of introducing a phosphate group include a method of adding a phosphate such as sodium tripolyphosphate alone to be subjected to roasting reaction, and examples of a method of introducing a phosphate group and a carbamate group include inorganic compounds. There may be mentioned a method in which urea is added together with phosphoric acids to cause a roasting reaction. Urea phosphate esterified starch can obtain the thing of various degrees of urea substitution mainly by the method of carrying out the calcination reaction of the latter inorganic phosphoric acids and urea.

  The urea phosphated starch preferably has a urea substitution degree average value of 0.005 or more and 0.05 or less. The "urea substitution degree" is the substitution degree of a carbamate group in the hydroxyl group of the glucose unit constituting starch. For example, the degree of substitution of urea = 0.02 means that there are two substituents per 100 glucose units constituting starch. The degree of urea substitution is a value conventionally known in starch and can be determined by a known method. For example, it can be determined from the nitrogen content using a thermal decomposition GC method or a CHN elemental analyzer. In addition, "starch science and experiment method", Shigeo Suzuki and Moral Nakamura, 1979, 1st edition publication, Asakura Shoten publication can be referred to.

  The styrene-butadiene copolymer resin is a copolymer resin in which a styrene-based monomer and butadiene occupy 70% by weight or more as monomers constituting the styrene-butadiene copolymer resin. The styrene-based monomer is a styrene derivative having a substituent on a vinyl group such as styrene and α-methylstyrene, and a derivative having a substituent on a benzene ring such as vinyl toluene and p-chlorostyrene.

  The styrene-butadiene copolymer resin can be possessed as a monomer constituting a styrene-based monomer and a monomer other than butadiene. Examples of the monomer include acrylonitrile, acrylic acid, acrylic acid salt, acrylic acid ester, methacrylic acid, methacrylic acid salt, methacrylic acid ester, and maleic acid.

  The content ratio by mass of the styrene-butadiene copolymer resin and the starches in the outermost coating layer is, as a dry solid content, styrene-butadiene copolymer resin: starch is 6: 4 to 9: 1.

The outermost coating layer can contain a conventionally known binder in addition to the styrene-butadiene copolymer resin and the starches. Examples of binders include conjugated diene resins such as acrylonitrile-butadiene copolymers other than styrene-butadiene copolymers, polymers of acrylic esters, polymers of methacrylic esters, methyl methacrylate-butadiene copolymers, etc. Acrylic resins, vinyl resins such as ethylene-vinyl acetate copolymer and vinyl chloride-vinyl acetate copolymer, polyurethane resin, alkyd resin, unsaturated polyester resin, and functional groups such as carboxyl group of these various copolymers Functional group modified resin with group-containing monomer, natural rubber, cellulose derivative such as carboxymethyl cellulose and hydroxyethyl cellulose, natural polymer resin such as casein, gelatin and soybean protein and derivatives thereof, polyvinyl pyrrolidone, polyvinyl alcohol and various modifications thereof Mention may be made of polyvinyl alcohol, polypropylene glycol, and a polyethylene glycol. The outermost coating layer can contain one or more selected from the group consisting of these binders in combination with the styrene-butadiene copolymer resin and the starch.
In the outermost coating layer, the content of the styrene-butadiene copolymer resin and the starch is preferably 80% by mass or more in the binder of the outermost coating layer. Moreover, it is preferable that content of the binder of outermost coating layer is 5 mass parts or more and 13 mass parts or less with respect to 100 mass parts of white pigments in the outermost coating layer containing kaolin and a calcium carbonate.

The outermost coating layer contains a fluorescent dye. Examples of fluorescent dyes include fluorescein compounds, thioflavine compounds, eosin compounds, rhodamine compounds, coumarin compounds, imidazole compounds, oxazole compounds, triazole compounds, carbazole compounds, pyridine compounds, and imidazolone compounds. Naphthalic acid derivatives, stilbene sulfonic acid derivatives, stilbene tetrasulfonic acid derivatives, stilbene hexasulfonic acid derivatives, etc. can be mentioned. The fluorescent dye is preferably a stilbene sulfonic acid derivative. Fluorescent dyes are commercially available from, for example, Clariant, Nippon Kayaku, Kemira Japan, Ciba Japan, and the like.
The preferable content of the fluorescent dye in the outermost coating layer is 0.06 parts by mass or more and 0.25 parts by mass or less based on 100 parts by mass of the white pigment in the outermost coating layer containing kaolin and calcium carbonate per one side. It is.

  The outermost coating layer preferably contains a dispersant. The reason for this is mainly that the color density unevenness is improved. The dispersant is a material for dispersing a water-insoluble substance such as a pigment in an aqueous solution, and is a conventionally known dispersant. Examples of conventionally known dispersants include polycarboxylic acid resins such as sodium polycarboxylate, acrylic resins such as sodium polyacrylate, styrene-acrylic resins, isobutylene-maleic acid resins, sulfonated polystyrene resins And polyvinyl alcohol, modified polyvinyl alcohol, condensed phosphate and the like. The outermost coating layer can contain one or more selected from among these dispersants. The dispersant for the outermost coating layer is preferably one or more selected from the group consisting of polycarboxylic acid resins and acrylic resins.

  The preferable content of the dispersant in the outermost coating layer is 0.02 parts by mass or more and 0.3 parts by mass or less based on 100 parts by mass of the white pigment in the outermost coating layer containing kaolin and calcium carbonate per one side. It is. The dispersant is a material that overlaps the binder. However, the material used as the dispersant can be distinguished because the content in the outermost coating layer is clearly smaller than that of the binder, and the dispersant has a smaller molecular weight than that of the binder.

The outermost coating layer preferably contains a lubricant. The reason for this is mainly that the resistance to dullness is improved. The lubricant is a conventionally known lubricant. Examples of conventionally known lubricants include higher fatty acid salts, waxes and organic silicon compounds. As higher fatty acid salts, for example, higher fatty acid metal salts such as laurate, oleate, palmitate, stearate, myristate (eg, sodium salts, potassium salts, zinc salts, calcium salts thereof) Also, higher fatty acid ammonium salts such as ammonium laurate, ammonium oleate, ammonium palmitate, ammonium stearate, ammonium myristate and the like. Waxes include, for example, vegetable waxes, animal waxes, montan waxes, paraffin waxes, synthetic waxes (hydrocarbon synthetic waxes, polyethylene emulsion waxes, higher fatty acid esters, fatty acid amides, ketones / amines, hydrogen-cured oil, etc. And aliphatic hydrocarbons such as polypropylene and polytetrafluoroethylene polymers, and derivatives thereof. Examples of organic silicon compounds include polyalkylsiloxanes and derivatives thereof, dimethyl silicone oils, methylphenyl silicone oils, alkyl-modified silicone oils, alkyl / aralkyl-modified silicone oils, amino-modified silicone oils, polyether-modified silicone oils, higher fatty acid-modified A silicone oil, a carboxyl modified silicone oil, a fluorine modified silicone oil, an epoxy modified silicone oil etc. can be mentioned. The outermost coating layer can contain one or more selected from the group consisting of these lubricants.
The lubricant for the outermost coating layer is preferably a higher fatty acid salt.

  The preferable content of the lubricant in the outermost coating layer is 0.25 parts by mass or more and 0.6 parts by mass or less with respect to 100 parts by mass of the white pigment in the outermost coating layer containing kaolin and calcium carbonate per one side. is there.

The outermost coating layer preferably contains a cationic resin. The reason for this is mainly that the color density unevenness is improved. The cationic resin is a conventionally known cationic resin. Preferred cationic resins are polymers or oligomers containing primary to tertiary amines or quaternary ammonium salts, which are easy to be coordinated with protons and dissociate when dissolved in water to exhibit cationic properties. In addition, a preferred cationic resin is a low cation having a degree of cationization of more than 0 meq / g and not more than 3 meq / g or a highly cationic resin having a degree of cationization of more than 3 meq / g. Here, the degree of cationization is a value measured by colloid titration.
Examples of conventionally known cationic resins include polyethylene imine, polyamine and modified polyamine, polyvinyl pyridine, polyamide amine, polyvinyl amine, modified polyamide, polyacrylamide, polyallyl amine, polydialkylaminoethyl methacrylate, polydialkylaminoethyl acrylate, poly Aliphatic monoamines such as dialkylaminoethyl methacrylamide, polydialkylaminoethyl acrylamide, polyvinyl benzyl trimethyl ammonium chloride, polydiallyl dimethyl ammonium chloride, copolymers of allyl dimethyl ammonium chloride and acrylamide, etc., dimethylamine-epichlorohydrin polycondensate, etc. Polycondensate with epihalohydrin compound or diethylenetriamine-epichrome Polycondensate of aliphatic polyamine and epihalohydrin compound such as hydrin polycondensate, polyamine polyamide epichlorohydrin, dicyandiamide-formalin polycondensate, dicyandiamide diethylene triamine polycondensate, polyepoxyamine, polyamide-epoxy resin, melamine resin, urea system Resin etc. can be mentioned. The outermost coating layer can contain one or more selected from the group consisting of these cationic resins. The average molecular weight of the cationic resin is not particularly limited. 500 or more and 100000 or less are preferable, and 1000 or more 60000 or less of an average molecular weight are more preferable.
The cationic resin of the outermost coating layer is preferably a modified polyamine or a modified polyamide.

  The preferable content of the cationic resin in the outermost coating layer is 0.25 parts by mass or more and 0.5 parts by mass with respect to 100 parts by mass of the white pigment in the outermost coating layer containing kaolin and calcium carbonate per one side. It is below.

  In the coated paper for printing of the present invention, the outermost coating layer contains at least a white pigment, a binder and a fluorescent dye, contains kaolin and calcium carbonate as a white pigment in a specific ratio, and uses styrene-butadiene copolymer as a binder It contains coalescing resin and starches in a specific ratio. By these synergetic effects, the coated paper for printing has sufficient whiteness, and can obtain tone jump resistance, color density nonuniformity resistance, and dullness resistance. When any of the above does not fall within the above range, the coated paper for printing has sufficient whiteness and can not obtain at least one of tone jump resistance, color density unevenness resistance, and dullness resistance. .

  The outermost coating layer can further contain various additives conventionally known in the coated paper field as required. Examples of additives include thickeners, flow improvers, antifoams, foaming agents, penetrants, color pigments, color dyes, UV absorbers, antioxidants, preservatives, anti-biocides, etc. Can.

  Hereinafter, the present invention will be described in more detail by way of examples. The present invention is not limited to these examples. Here, "parts by mass" and "% by mass" represent "parts by mass" and "% by mass" of the dry solid amount or the amount of the substantial component, respectively. The coating amount of the coating layer represents the dry solid content.

<Base paper>
8 parts by mass of calcium carbonate as a filler, 1.0 parts by mass of amphoteric starch, 0.8 parts by mass of a sulfuric acid band, and an internally added sizing agent are added to a pulp slurry consisting of 100 parts by mass of LBKP with 400 ml cs freeness to adjust the stock The paper stock was made with a Fourdrinier paper machine, starch was attached to both sides of the obtained paper-made paper with a size press and machine calendered to produce a base paper.

Outermost Coating Layer Coating Liquid
The outermost coating layer coating liquid was prepared according to the following contents.
The number of kaolin parts is described in Table 1. The number of calcium carbonate parts is described in Table 1. The number of silica parts is described in Table 1 The types and parts are described in Table 1 The latex types and parts are described in Table 1 Dispersed agent of acrylic resin based on Table 1 0.3 parts by mass Calcium lubricant lubricant 0.6 parts by mass Modified polyamide cationic resin 0.5 parts by mass The above contents are mixed, dispersed and mixed with water. The concentration was adjusted to 48% by mass.

(Coated paper for printing)
Coated paper for printing was produced according to the following procedure.
The outermost coating layer coating liquid was coated on both sides with a blade coater on a base paper, and then dried. After further drying, it was calendered. The coating amount was 14 g / m ² per side.

<Evaluation of Whiteness>
The whiteness is measured according to JIS P 8148: 2001 "Paper, paperboard and pulp-measurement of ISO whiteness", using Nippon Denshoku Kogyo Co., Ltd., SPECTRO COLOR METER MODEL PF-10, using a C / 2 light source. , Without using a UV cut filter. The measurement of the whiteness was performed by overlapping the coated papers for printing as needed so as to be a thickness of 250 μm or more. Evaluation was performed according to the following criteria. In the present invention, in the case of the evaluation 2 or 3, the coated paper for printing has sufficient whiteness.
3: Whiteness 90% or more 2: Whiteness 88% or more and less than 90% 1: Whiteness less than 88%

<Evaluation of tone jump resistance>
An evaluation image was printed using an ink jet printer MJP 20 MX-7000 manufactured by Miyakoshi Co., Ltd. with an aqueous pigment ink at a printing speed of 150 m / min and at a speed of 6000 m. The evaluation image was an image on which a gradation image consisting of black, cyan, magenta, and yellow single colors was disposed. The tone jump resistance was visually observed from the printed portion of the gradation image of each color, and was evaluated according to the following criteria from the extent that the tone jump was visually recognized. In the present invention, in the case of the evaluations 4 and 5, the coated paper for printing has tone jump resistance.
5: Good without tone jump.
4: A tone jump inferior to the above "5" is slightly recognized, but is generally good.
3: A tone jump slightly inferior to the above "4" but relatively good.
2: A tone jump inferior to the above "3" is recognized, but there is no problem in practical use.
1: A tone jump is recognized and there is a problem in practical use.

<Evaluation of color density unevenness>
An evaluation image was printed using an ink jet printer MJP20MX-7000 manufactured by Miyakoshi Co., Ltd. with an aqueous pigment ink at a printing speed of 150 m / min for 6000 m. The evaluation image is a 3 cm × 3 cm square pattern of a solid image portion pattern of a total of seven colors (red, green, blue) by single colors of black, cyan, magenta and yellow and other three colors except black. It was an image arranged without gaps in a row. The color density unevenness was observed visually with respect to the printed portion of each color solid part image, and evaluated according to the following criteria. In the present invention, in the case of the evaluations 4 and 5, the coated paper for printing has the resistance to color density unevenness.
5: The color density is uniform.
4: The density is slightly nonuniform depending on the color.
3: The color density is slightly nonuniform.
2: The color density is partially nonuniform.
1: The color density is uneven throughout the printing portion.

<Evaluation of dulling resistance>
An evaluation image was printed using an ink jet printer MJP20MX-7000 manufactured by Miyakoshi Co., Ltd. with an aqueous pigment ink at a printing speed of 150 m / min for 6000 m. The evaluation image is a 3 cm × 3 cm square pattern of a solid image portion pattern of a total of seven colors (red, green, blue) by single colors of black, cyan, magenta and yellow and other three colors except black. It was an image arranged without gaps in a row. The blur resistance was evaluated by visual observation of the printed portion of each color solid image, and the degree of reduction in saturation as compared with the printed portion and the standard color sample according to the following criteria. In the present invention, in the case of the evaluations 4 and 5, the coated paper for printing is considered to have dulling resistance.
5: Good 4: Almost good.
3: A slight decrease in saturation is observed. However, there is no problem in practical use.
2: A slight decrease in saturation is observed.
1: A drop in saturation is observed.

  The evaluation results are shown in Table 1.

From Table 1, it is understood that Examples 1 to 20 corresponding to the present invention have sufficient whiteness and have tone jump resistance, color density unevenness and dulling resistance. On the other hand, Comparative Examples 1 to 7 which do not satisfy the configuration of the present invention are found to be incapable of satisfying at least one of these effects.
Also, mainly from the comparison between Examples 2 to 6, the content of the fluorescent dye in the outermost coating layer is at least 0.06 parts by mass with respect to 100 parts by mass of the white pigment in the outermost coating layer. It is understood that less than or equal to 25 parts by weight is preferred.

Claims (2)

  A base paper and a coating layer on at least one side of the base paper, and an outermost coating layer positioned outermost with respect to the base paper in the coating layer contains at least a white pigment, a binder and a fluorescent dye, In the outer coating layer, kaolin and calcium carbonate are contained in at least two of the white pigments, and the content ratio (kaolin: calcium carbonate) in the outermost coating layer of kaolin and calcium carbonate is 1: 9 to 6: 4. And the styrene-butadiene copolymer resin and the starches in at least two of the binders, and the content ratio in the outermost coating layer of the styrene-butadiene copolymer resin and the starches (styrene-butadiene copolymer Polymeric resin: Coated paper for printing having a starch ratio of 6: 4 to 9: 1.   Content of the fluorescent dye in the outermost coating layer is 0.06 mass parts or more and 0.25 mass parts or less with respect to 100 mass parts of white pigments in the outermost coating layer per one side. Of coated paper for printing.