JPH08144193A - Highgrade printing paper - Google Patents

Abstract

PURPOSE: To obtain highgrade printing paper having touch feeling of uncoated paper and capable of developing ink concentration equivalent to that of at least lightweight coated paper or higher than that thereof. CONSTITUTION: The characteristic of this highgrade printing paper comprises providing a coated layer containing 100 pts.wt. of pigment consisting essentially of a mixture of kaolin with an organic synthetic pigment having adhesive force or a mixture of two or more kinds of pigments selected from kaolin, a flat type organic synthetic pigment and an urethane resin based fiber and 5-30 pts.wt. of styrene-butadiene copolymer latex as an additive and 20-50 pts.wt. of phosphated starch and/or acetylated starch and having 3-10g/m<2> coated amount based on absolute dry weight onto a base paper containing wood pulp as a main raw material by air knife coater or bar coater.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to high quality printing paper.
More specifically, the present invention is mainly applied to commercial art prints, publication prints, packaging material prints, and paper container prints, and the white surface has a texture of uncoated paper, and the ink density of the printing surface is light coated paper. The present invention relates to high-quality printing paper which is equivalent or higher.

[0002]

2. Description of the Related Art Recently, in the fields of commercial / art printing such as calendars and pamphlets, publication printing of visual magazines and photo books, and packaging printing of shopping bags, fashion bags (paper bags), and paper containers such as pharmaceuticals and cosmetics. The trend toward higher quality and individuality is progressing further. In particular, in the field of offset printing used for a wide range of printing, high-definition printing of 300 to 900 lines / inch, which is excellent in transparency and sharpness, is becoming widespread with respect to a conventional halftone dot plate material of 200 lines / inch or less. is there. On the other hand, progress toward higher quality is unavoidable, such as an increase in gravure printing, which is excellent in the stereoscopic effect of printed images.

The printing papers in the classification classification of the Japan Paper Association are roughly classified into non-coated printing papers, slightly coated printing papers and coated printing papers. Non-coated printing paper is classified into high-grade printing paper, intermediate-grade printing paper and lower-grade printing paper, etc. by blending the raw pulp, and since the whole paper is composed of wood pulp fibers, it has a natural surface texture and high bulk. While it has the advantage of high rigidity (rigidity), it has a drawback that the ink penetrates into the paper layer and the ink density becomes extremely low when printing because of its rough structure and large liquid absorption.

On the other hand, for the purpose of improving the printing quality when paper is used as a printing medium, pigment coating is applied to a base paper mainly made of wood pulp. These pigment-coated papers are classified into fine-coated printing papers and coated printing papers according to the coating amount, and coated printing papers have a large coating amount and gradually increase the coating amount from art paper that exhibits the highest print quality. There are few coated papers and lightweight coated papers. These pigment-coated papers have a coating layer containing fine pigments as the main component that completely covers the surface of the base paper that is mainly made of wood pulp. In comparison, it shows an extremely high ink density. However, as described above, since the base paper surface mainly composed of wood pulp is completely covered with the coating layer containing the pigment as the main component, the texture of the paper such as the uncoated printing paper is, of course, completely untouched. Lost.

As described above, the texture of uncoated printing paper is maintained in all fields of commercial / art printing, publication printing and packaging printing, against the backdrop of higher quality and individualization of print quality. In addition, there is a strong demand for high-quality printing paper that can obtain an ink density as close as possible to coated printing paper.
However, the texture of uncoated paper due to the rough structure rich in voids and the high ink density developed by the dense pigment coating layer are in conflict with each other, so products that satisfy this are still on the market. In fact, even the concept of the manufacturing method is not disclosed.

[0006]

In view of the above situation, the present inventors have considered that the present situation is such that high-quality printing having the texture of uncoated printing paper and capable of exhibiting a high ink density at least as high as that of lightweight coated paper or higher. It provides paper.

[0007]

[Means for Solving the Problems] Kaolin, a mixture of organic synthetic pigments having adhesiveness, or at least 2 selected from kaolin, flat organic synthetic pigments, and urea resin-based fillers on a base paper mainly made of wood pulp. 5 to 30 parts by weight of a styrene-butadiene copolymer latex as an adhesive with respect to 100 parts by weight of a pigment containing a mixture of one or more kinds as a main component,
Absolute dry coating amount of 3 to 10 g / containing 20 to 50 parts by weight of phosphoric esterified starch and / or acetylated starch
It is a high-grade printing paper characterized in that the coating layer of m ² is provided by an air knife coater or a bar coater.

[0008]

In order to obtain a high-quality printing paper which maintains the texture of the uncoated printing paper and has a printing surface whose ink density after printing is equal to or higher than that of the light weight coated paper,
The present inventors have made intensive studies mainly on the composition of the coating layer formed on the base paper and the method of forming the coating layer. As a result, kaolin, which is easy to form a plate-like and dense structure, is used as the pigment of the coating layer formed on the base paper, and an organic synthetic pigment or urea resin-based filler that has a high affinity with ink without impairing the dense structure. To improve the ink transfer from the plate to the paper, and in addition to the styrene-butadiene copolymer latex that is usually used as an adhesive for the coating layer of coated printing paper, the paper of the transferred ink The object of the present invention is to form a coating layer in which a phosphate esterified starch and / or an acetylated starch having the property of suppressing penetration into the interior and holding the ink on the surface is used by an air knife coater or a bar coater. To obtain a high-grade printing paper that maintains the texture of non-coated printing paper, which has a high printing surface, and has an ink density after printing that is equal to or higher than that of lightweight coated paper. It found that can be, and have completed the present invention.

The base paper used in the present invention is chemical pulp such as bleached hardwood kraft pulp and bleached softwood kraft pulp,
Using a mechanical pulp such as GP, RGP, TMP as a raw material, a well-known fourdrinier multi-cylinder paper machine, fourdrinier Yankee paper machine,
It includes high-quality paper, medium-quality paper, neutral-glossy paper, acidic paper such as kraft paper, neutral paper, and alkaline paper, which are produced by a cylinder paper machine or the like. The base paper contains papermaking auxiliary agents such as a paper-strengthening agent, a sizing agent, a filler and a retention aid. The surface of the above-mentioned base paper can be subjected to a smoothing treatment with a finishing equipment such as a machine calender or a super calender if necessary, but if the excessive smoothing treatment is performed, the texture of the uncoated paper is impaired after coating. Therefore, J. TAPPI paper pulp test method No. It is preferable to finish with Oken type smoothness defined in 5 m-74 for 100 seconds or less.

The base paper used in the present invention is mainly a base paper having a texture of non-coated paper, but various base papers can be used depending on the use and purpose of use of the coated product. For example, in order to give the coated product a feeling of bulky handiness, it is possible to select a rough paper having a lower tenacity and a lower smoothness as the base paper. Particularly preferably, when a bulky paper used as a fancy paper, that is, a base paper having a smoothness of 10 to 30 seconds and a tightness of about 0.7 is used, and the coated paper is finished without supercalendering, The present invention exerts a great effect. .

The coating layer composition provided on the base paper of the present invention is mainly composed of a pigment and an adhesive, and both the pigment and the adhesive play an important role. The composition of the coating liquid must meet the following conditions in order to maintain the texture of uncoated paper, transfer the printed ink to the paper sufficiently, and quickly dry it on the surface to suppress its penetration into the paper. There is.

That is, in order to maintain the texture of uncoated paper, kaolin, a mixture of organic synthetic pigments having adhesive strength,
Alternatively, 5 to 30 parts by weight of a styrene-butadiene copolymer latex used as an adhesive is added to 100 parts by weight of a pigment containing a mixture of at least two kinds selected from kaolin, flat organic synthetic pigments and urea resin fillers as a main component. 20 to 50 parts by weight of the phosphate esterified starch and / or the acetylated starch used in combination therewith. By the way, when the styrene-butadiene copolymer latex is less than 5 parts by weight, the pigment in the coating layer becomes excessive and the surface of the base paper containing wood pulp as a main component is covered with the pigment, so that This results in a loss of texture. On the other hand, if the styrene-butadiene copolymer latex exceeds 30 parts by weight, the styrene-butadiene copolymer latex will form a continuous film layer, and the ink will be retained on the surface, and the ink will be dried. Be extremely slow. Further, since the water absorption also decreases, a so-called water loss phenomenon occurs, which makes it difficult for ink to adhere to a portion of the paper surface where the dampening water is attached during offset printing, which makes printing practically difficult.

When the amount of the phosphoric acid esterified starch and / or the acetylated starch is less than 20 parts by weight, the effect of preventing ink penetration of the coated layer is not sufficiently exerted, and the printed ink promptly develops the coated layer. Because it penetrates inside,
The high ink density desired by the present invention cannot be obtained. On the other hand, when the amount of phosphate esterified starch and / or acetylated starch exceeds 50 parts by weight, styrene-
As in the case of the butadiene copolymer latex, the continuity of the coating layer is increased and the ink drying becomes extremely slow, which makes printing practically difficult.

The kaolin used in the present invention includes, for example, special grade kaolin for paper coating commercially available from Engelhard Co., Ltd. of the United States of America, ECC Co., Georgia Kaolin Co., Ltd., Comarco Co., Ltd. of Australia, and the like. Primary and secondary kaolins can be used individually and as a mixture, and delaminated kaolin in which kaolin particles having a laminated structure are mechanically exfoliated can also be blended, but a coating layer having a dense structure is formed. For this reason, it is important that the kaolin particles are calcined at 900 ° C. and the particles whose surfaces are melted are re-aggregated to easily give a porous structure when blended in the coating layer. -267371 and JP-A-63-278986, the quaternary ammonium polymer salt, diallylammonium chloride, and porphyrin produced by the method described in JP-A-63-278986. The amount of polyelectrolyte per weight 0.03 to 0.15% of range of kaolin selected from among amines are processed added to the kaolin, 0.77 to 0.95
Kaolin having a bulky structure such as calcined clay having a sedimentation volume of ml / g is not suitable because it cannot suppress the permeation of printing ink into the coating layer.

On the other hand, kaolin for the present invention may be used in combination with other pigments. The type of the pigment is not particularly limited, and may be an appropriate inorganic inorganic pigment such as general heavy calcium carbonate, light calcium carbonate, aluminum hydroxide, satin white, titanium dioxide, etc. The blending amount is preferably limited to such an extent that it does not hinder the formation of a dense coating layer, that is, 50 parts by weight or less of the total pigment.

In the present invention, for the purpose of increasing the uniformity of the coating layer and further improving the transferability and acceptability of the ink, an organic synthetic pigment having a high affinity with the ink as a pigment,
A urea resin-based filler is used, but as the organic synthetic pigment, it is necessary to use an organic synthetic pigment having adhesiveness or a flat organic synthetic pigment. Organic synthetic pigments are called plastic pigments and have a particle size of 0.1 to 0.5 μm, which is generally produced by emulsion polymerization with polystyrene as the main component.
m particles. By blending the organic synthetic pigment in the coating layer, the surface properties and printability of the coating layer can be significantly improved, and the organic synthetic pigment has a lower specific gravity than ordinary inorganic pigments, so that the strength of the coated paper can be improved. Can be made low and can be finished in bulk.

As the organic synthetic pigment, generally, spherical particles, sugar particles such as konpeito are widely available on the market, for example, "ROOPAKE HP-91" manufactured by Rohm and Haas Co., Ltd., "Gloss" manufactured by Mitsui Toatsu Kagaku Co., Ltd. Dale 201-S "," Grossdale 110-M "and the like correspond to this, but when these organic synthetic pigments are used for the coating layer, the surface strength of the coating layer is significantly weakened and scratches easily occur. turn into. The organic synthetic pigment having an adhesive force used in the present invention is generally called a binder pigment, and the organic synthetic pigment containing polystyrene as a main component is coated with a styrene-butadiene copolymer latex, a so-called core-. It has a shell structure, for example, "L- manufactured by Asahi Kasei Corporation.
8808 ”corresponds to this. This binder pigment imparts excellent scratch resistance without lowering the surface strength of the coating layer. Further, as an organic synthetic pigment capable of imparting excellent ink transfer property and scratch resistance without lowering the surface strength of the coating layer, a flat organic synthetic pigment used in the present invention can also be mentioned. Examples of the flat organic synthetic pigment include “Grossdale 240-V” manufactured by Mitsui Toatsu Chemicals, Inc., and the like.

The urea resin filler is a condensate containing formaldehyde and urea as a main component and an aqueous solution of an acid catalyst in an amount of 30 to 70.
The gel-like material obtained by mixing under the condition of ° C is roughly pulverized to obtain a slurry liquid, free formaldehyde is removed, and then wet finely pulverized to control the average diameter of the aggregate to 5 µm. That is, in the urea resin-based filler, non-porous spherical particles having a diameter of 0.1 to 0.3 μm are coalesced with each other to form an aggregate (porous secondary particles) having an average diameter of about 5 μm. Due to the high light scattering performance due to this void structure, when used as a coating layer, it significantly suppresses the gloss of the coated surface and gives a natural surface when used in combination with a flat organic synthetic pigment. Express the texture. Furthermore, this void structure has the effect of quickly absorbing the printed ink to prevent bleeding and permeation into the interior of the paper, and as a result, the opacity after printing and the printability such as the sharpness of printing can be improved. It effectively contributes to the improvement. Examples of the urea resin-based filler include “Upearl C-2” manufactured by Mitsui Toatsu Chemicals, Inc.
01 "," Eupearl C-120 "," Eupearl C- "
122R ”and the like.

The blending ratio of the inorganic pigment and the organic synthetic pigment having adhesive strength is not particularly limited, and may be arbitrarily blended depending on the desired printability. Further, the blending ratio of the inorganic pigment, the flat organic synthetic pigment, and the urea resin-based filler is not particularly limited, and may be arbitrarily blended according to the desired printability. It is necessary to mix at least two kinds, more preferably three kinds, selected from organic synthetic pigments and urea resin fillers.

The styrene-butadiene copolymer latex used for the coating layer in the present invention includes aromatic vinyl monomers such as styrene and α-methylstyrene, 1,3 butadiene, 2-methyl-1,3 butadiene and the like. Aliphatic conjugated diene monomer, acrylic acid, ethylenically unsaturated acid monomer such as methacrylic acid, acrylonitrile monomer and ethylenically unsaturated carboxylic acid alkyl ester, ethylenically unsaturated carboxylic acid amide, other It is obtained by copolymerizing a copolymerizable monomer such as an organic carboxylic acid and its derivative by a known method, and can be arbitrarily selected from those commercially available for paper coating. .

The phosphoric acid esterified starch and the acetylated starch used in the present invention further complement the film forming properties of the styrene-butadiene copolymer latex and contribute to the formation of a strong continuous film. Alternatively, they can be used as a mixture, and for example, the former is “Neil gum A-85” commercially available from Matsutani Chemical Co., Ltd.,
"Neil gum A-55" and the latter include "National 78-0338" marketed by National Starch and Chemicals Co., Ltd. and the like. still,
If necessary, auxiliary chemicals such as a dispersant, a water-proofing agent, a defoaming agent, a lubricant, a coloring agent, and a preservative can be optionally added to the coating liquid to form a coating material by a known preparation method. .

As a coating facility, it is necessary to use an air knife coater or a bar coater to maintain the texture of uncoated paper. The air knife coater scrapes off the excessively applied paint with an air jet so as to obtain a predetermined coating amount, and the bar coater scrapes the excessively applied paint with a Mayer bar so as to obtain a prescribed coating amount. It is something to drop. These coating methods have less penetration of the paint into the inside of the base paper and can form a coating layer (contour coating) of almost the same thickness along the roughness of the base paper surface. A coating layer can be effectively formed with a low coating amount without impairing it, and exhibits excellent performance as the coating equipment of the present invention, and it is particularly preferable to use an air knife coater for coating. Incidentally, gate roll coaters, blade coaters, etc. are also widely used as paper coating equipment.However, when a gate roll coater is used, the ink barrier that allows the paint to permeate the inside of the base paper remarkably during the nip passage process between rolls is used. Therefore, the desired ink density cannot be obtained because the desired properties cannot be obtained. When a blade coater is used, since the excessively applied paint is scraped off by a metal blade so as to have a predetermined coating amount, the smoothness of the coated surface is excessively increased and the printability becomes good. The texture of uncoated printing paper cannot be maintained.

Further, in order to maintain the texture of the uncoated printing paper and obtain a high ink density, the absolutely dry coating amount of the coating layer needs to be in the range of 3 to 10 g / m ² . By the way, if the coating amount is less than 3 g / m ² , the texture of the uncoated paper is good, but a uniform coating layer cannot be formed on the surface of the base paper, and uneven absorption of ink is likely to occur, which is high as desired. The ink density cannot be obtained. On the other hand, when the coating amount exceeds 10 g / m ² , the printability is good, but an excessive coating layer covers the surface of the base paper, which makes it impossible to maintain the texture of the uncoated printing paper.

The coated paper coated in this manner can be dried with a known dryer and then directly printed to obtain a high ink density. In addition, if necessary, smoothing treatment may be performed with a coating surface finishing equipment such as a super calender, but in this case, extreme finishing treatment increases the surface smoothness and gloss, and further increases the stiffness of paper. Since it lowers the texture of uncoated paper, the J. TAPPI paper pulp test method No.
5m-74, Oken's smoothness is 100 seconds or less, and the specular gloss of incident light flux / reflected light flux = 75 ° / 75 ° specified by JIS P8142 is 15% or less. It should be kept below 9 If these requirements are not satisfied, printability will be good, but the texture of uncoated paper cannot be maintained. Therefore, in many cases, the coated paper according to the present invention is preferably not subjected to the supercalendering treatment, and basically, when a fancy paper having low tenacity and low smoothness is used as the base paper, the supercalendering treatment is basically not performed. Not performed.

The above-mentioned coated paper is printed, but there is no restriction on the printing method, ink, and printing conditions (printing pressure, speed, etc.), and usually commercial art prints, publication prints, packaging material prints and It is possible to freely perform planographic printing, intaglio printing, and letterpress printing such as offset printing, gravure printing, and flexographic printing, which are used for printed matter on paper containers, according to the purpose.

A mixture of kaolin and an organic synthetic pigment having adhesiveness, or at least two kinds selected from kaolin, a flat organic synthetic pigment, and a urea resin-based filler, on the base paper of the present invention, which is mainly composed of wood pulp. Containing 5 to 30 parts by weight of styrene-butadiene copolymer latex and 20 to 50 parts by weight of phosphoric esterified starch and / or acetylated starch as an adhesive with respect to 100 parts by weight of the pigment containing the above mixture as a main component Absolute dry coating amount 3 to 10 g / m
^Since the coating layer of ² is provided by the air knife coater or the bar coater, the white paper surface has the texture of uncoated printing paper as never before, and the density of the printing surface is equivalent to the lightweight coated paper, Alternatively, it is possible to provide high-quality printing paper having a higher price.

[0027]

EXAMPLES The present invention will be described more specifically with reference to the following examples, but it should be understood that the present invention is not limited by these examples. In the following,% means% by weight.

Example 1 A talc content of 10% was added to a wood pulp raw material consisting of 20% of 470 ml csf bleached softwood kraft pulp and 80% of 470 ml csf free bleached kraft pulp. In addition, 0.3% of reinforced rosin size (trademark: SPE, manufactured by Arakawa Chemical Industry Co., Ltd.) and 2% of sulfuric acid band were added, and a base paper with a basis weight of 80 g / m ^{2 was} produced by a fourdrinier cylinder type paper machine. Paper-made. The Oken type smoothness of this base paper was 59 seconds. Next, kaolin (trademark: UW-90, manufactured by Engelhard Co., USA) 90% and binder pigment (trademark: L-8808, manufactured by Asahi Kasei Co., Ltd.) 10% were used as pigments, and the dry pigment weight per weight was measured. Acrylic dispersion (trademark: Poise 520, manufactured by Kao Corporation) 2.5% was added to give a solid content of 5
Dispersed using a high speed deleter at 0%. Further, styrene-butadiene copolymer latex (trademark: JSR-0619, manufactured by Japan Synthetic Rubber Co., Ltd.) and phosphate esterified starch (trademark: Neil gum A-8) as an adhesive agent.
5, manufactured by Matsutani Chemical Co., Ltd.) and mixed by 20% and 35%, respectively, based on the weight of the dry pigment in terms of solid content, and mixed, and further a lubricant (trademark: Nopcoat C-104, manufactured by San Nopco Ltd.)
1.0%, antifoaming agent (trademark: DEF122NS, manufactured by San Nopco Co., Ltd.) 0.03%, fluorescent dye (trademark: FoL, manufactured by Nippon Kayaku Co., Ltd.) 0.10% were added and mixed, and 5 % Aqueous solution of caustic soda to adjust the pH to 8.5 to produce a paint having a solid content of 40%. The above coating composition was coated on a base paper with an air knife coater so that the absolute dry coating weight was 7.5 g / m ^2, and dried to obtain a coated paper. The tenacity of this coated paper was 0.76. The super calendar treatment was not performed.

Example 2 A coated paper was obtained by coating and drying in the same manner as in Example 1 except that the compounding ratio of the styrene-butadiene copolymer latex in the coating material of Example 1 was 28 parts. The tenacity of this coated paper was 0.78. Example 3 Coating was carried out in the same manner as in Example 1 except that the blending ratio of the phosphate esterified starch in the coating material of Example 1 was 48 parts.
A coated paper was obtained by drying. The tenacity of this coated paper was 0.77. Example 4 Example 1 except that the coating amount of Example 1 was 5 g / m ^2.
Coating and drying were carried out in the same manner as above to obtain coated paper. The tenacity of this coated paper was 0.74.

Example 5 Example 1 was repeated except that the coating amount in Example 1 was 9 g / m ^2.
Coating and drying were carried out in the same manner as above to obtain coated paper. The tenacity of this coated paper was 0.77. Example 6 The pigment in the paint of Example 1 was treated with Kaolin (trademark: UW-9).
0, American Engelhard Co., Ltd. 40%, flat organic synthetic pigment (Trademark: Grosdale 240-V, Mitsui Toatsu Chemical Co., Ltd.) 30%, urea resin filler (Trademark: Eupearl C-122R). Co., Ltd., manufactured by Mitsui Toatsu Chemical Co., Ltd., and coated and dried in the same manner as in Example 1 to obtain a coated paper. The tenacity of this coated paper was 0.77. Example 7 The pigment in the paint of Example 1 was treated with Kaolin (trademark: UW-9).
0, manufactured by Engelhard Co., Ltd., USA 70%, binder pigment (trademark: L-8808, manufactured by Asahi Kasei Corporation) 1
Coated paper was obtained by coating and drying in the same manner as in Example 1 except that the content was 0%, and the wet-ground heavy calcium carbonate (trademark: Hydrocarb-90, manufactured by Shiraishi Calcium Co., Ltd.) was 20%. . The tenacity of this coated paper was 0.78.

Example 8 The pigment in the coating material of Example 1 was mixed with kaolin (trademark: UW-9).
0, American Engelhard Co., Ltd. 30%, wet ground heavy calcium carbonate (trademark: Hydrocarb-90, Shiraishi Calcium Co., Ltd.) 30%, flat organic synthetic pigment (trademark: Grosdale 240-V) Manufactured by Mitsui Toatsu Chemicals, Inc.
20%, urea resin filler (trademark: Eupearl C-122)
R, manufactured by Mitsui Toatsu Chemicals, Inc.) was coated and dried in the same manner as in Example 1 to obtain coated paper. The tenacity of this coated paper was 0.79. Example 9 The coated paper of Example 1 is passed through a super calender and pressure-contacted to the surface of the coated paper to make incident light flux / reflected light flux = 75 ° / 7.
14% at 5 ° specular gloss and 90 at Oken smoothness
A coated paper was obtained by coating and drying in the same manner as in Example 1 except that the finishing was completed in seconds. The tenacity of this coated paper was 0.88. Example 10 The base paper of Example 1 was changed to fancy paper 120 g / m ² (trademark: OK Shimonomono Muse, manufactured by Abegawa Paper Co., Ltd., tenacity 0.70, Oken smoothness 10 seconds, gloss 4.5). %) Was applied and dried in the same manner as in Example 1 to obtain a coated paper. The tenacity of this coated paper was 0.70.

Comparative Example 1 A coated paper was obtained by coating and drying in the same manner as in Example 1 except that the content of the styrene-butadiene copolymer latex in the coating material of Example 1 was changed to 3 parts. The tenacity of this coated paper was 0.78. Comparative Example 2 A coated paper was obtained by coating and drying in the same manner as in Example 1 except that the compounding ratio of the styrene-butadiene copolymer latex in the coating material of Example 1 was 40 parts. The tenacity of this coated paper was 0.76. Comparative Example 3 Coating was carried out in the same manner as in Example 1 except that the blending ratio of the phosphate esterified starch in the coating material of Example 1 was changed to 18 parts.
A coated paper was obtained by drying. The tenacity of this coated paper was 0.75.

Comparative Example 4 Coating was conducted in the same manner as in Example 1 except that the compounding ratio of the phosphoric acid esterified starch in the coating material of Example 1 was changed to 60 parts.
A coated paper was obtained by drying. The tenacity of this coated paper was 0.77. Comparative Example 5 Example 1 except that the coating amount of Example 1 was 2 g / m ^2.
Coating and drying were carried out in the same manner as above to obtain coated paper. The tenacity of this coated paper was 0.74. Comparative Example 6 A coated paper was obtained by coating and drying in the same manner as in Example 1 except that the coating amount in Example 1 was 13 g / m ² . The tenacity of this coated paper was 0.80.

Comparative Example 7 Instead of the binder pigment in the coating material of Example 1,
Hollow spherical organic synthetic pigment (trademark: Lowpaque HP-91,
A coated paper was obtained by coating and drying in the same manner as in Example 1 except that Rohm and Haas Co., Ltd. (USA) was used.
The tenacity of this coated paper was 0.75. Comparative Example 8 The pigment in the paint of Example 1 was mixed with Kaolin (trademark: UW-9).
0, American Engelhard Co., Ltd.) 20%, binder pigment (trademark: L-8808, Asahi Kasei Co., Ltd.) 1
Coated paper was obtained by coating and drying in the same manner as in Example 1 except that 0% and 70% of wet ground ground calcium carbonate (trademark: Hydrocarb-90, manufactured by Shiraishi Calcium Co., Ltd.) were used. . The tenacity of this coated paper was 0.78. Comparative Example 9 The pigment in the paint of Example 1 was mixed with Kaolin (trademark: UW-9).
0, 20% manufactured by Engelhard Co., USA, wet ground heavy calcium carbonate (trademark: Hydrocarb-90, manufactured by Shiraishi Calcium Co., Ltd.) 60%, flat organic synthetic pigment (trademark: Grosdale 240-V) Manufactured by Mitsui Toatsu Chemicals, Inc.
10%, urea resin filler (trademark: Eupearl C-122)
R, manufactured by Mitsui Toatsu Chemicals, Inc.) 10%, and coated and dried in the same manner as in Example 1 to obtain a coated paper. The tenacity of this coated paper was 0.74.

Comparative Example 10 The coated paper of Example 1 was passed through a super calender and pressure contacted to the surface of the coated paper to make incident light flux / reflected light flux = 75 ° / 7.
19% with 5 ° specular gloss and 190 with Oken smoothness
A coated paper was obtained by coating and drying in the same manner as in Example 1 except that the finishing was completed in seconds. The tenacity of this coated paper was 0.93. Comparative Example 11 A coating paper similar to that of Example 1 was coated and dried except that the coating equipment of Example 1 was a gate roll coater to obtain a coated paper. The tenacity of this coated paper was 0.78.

Comparative Example 12 Except that the coating equipment of Example 1 was changed to a blade coater,
The same paint as in Example 1 was applied and dried to obtain coated paper.
The tenacity of this coated paper was 0.75. Comparative Example 13 Instead of the coated paper of Example 1, uncoated printing paper (trademark:
The quality was evaluated using Sunflower and Shin-Oji Paper Co., Ltd. The tightness of this uncoated printing paper was 0.80. Comparative Example 14 Instead of the coated paper of Example 1, lightweight coated paper (trademark: O
The quality was evaluated using K coat L and Shin Oji Paper Co., Ltd. The tenacity of this lightweight coated paper was 0.94.

The 24 types of coated papers thus obtained were subjected to the following quality evaluations. Table 1 shows the evaluation results. (Printing surface ink density) Printed on the coated paper using the RI printing machine manufactured by Akira Seisakusho Co., Ltd. and on the ink using Graf-G (red) manufactured by Dainippon Ink and Chemicals, Inc. (ink supply amount 0 ．
3 ml), and 24 hours after printing, the reflection density was measured using a Macbeth densitometer. (Drying property of ink) By using the RI printer manufactured by Akira Mfg. Co., Ltd. for coated paper, the ink manufactured by Dainippon Ink and Chemicals, Inc. G
Printing using raf-G (red) (ink supply 0.5
60 minutes after printing, the finger was lightly contacted with the printing surface, and when the ink did not adhere to the finger, the drying property was determined to be good, and when the ink adhered, the drying property was determined to be poor, and was evaluated as x.

(Handle of uncoated paper) It was judged by a total of 10 persons, 5 persons each for men and women, whether or not the texture of uncoated paper was left on the coated paper, and it was evaluated that 8 or more persons were left. The case was judged as ◯, and the case of less than 8 people was judged as x. (Scratches on the coated surface) The surface of the coated paper is strongly rubbed with a fingertip and the condition of the scratches on the surface is visually observed. When the scratches are not so noticeable, the scratches are markedly problematic in practical use. When it was considered to be, it was judged as x.

(Glossiness of coated surface) JIS of coated paper surface
The specular glossiness of incident light flux / reflected light flux = 75 ° / 75 ° defined in P8142 was measured by a gloss meter manufactured by Murakami Color Research Laboratory Co., Ltd. (Smoothness of coated surface) J. TAPPI N
o. The Oken type smoothness specified by 5 m-74 was measured.

[0040]

[Table 1]

As is clear from Table 1, the high-grade printing paper according to the present invention has an ink density after printing which is equal to or higher than that of the light weight coated paper, and the ink is dried quickly and has excellent print quality. . In addition, the texture of uncoated paper, which is easily damaged by coating, was sufficiently retained, and the object of the present invention was sufficiently satisfied (Examples 1 to 1).
0). On the other hand, when the composition ratio of the paint is not within the range of the present invention (Comparative Examples 1 to 4), and when the coating amount is not within the range of the present invention (Comparative Examples 5 to 6), the composition and the finished surface of the present invention When the conditions are not satisfied (Comparative Examples 7 to 12), all of them are inconvenient and unpractical. Incidentally, as a matter of course, the general non-coated printing paper has a good texture, but the desired printing density cannot be obtained because the ink penetrates into the paper (Comparative Example 13), and the weight is light. Good printing can be obtained with coated paper, but the surface of the coated paper is completely covered with a coating layer, and the texture of uncoated paper is high, and the texture of uncoated paper is completely impaired (Comparative Example 1).
4).

[0042]

EFFECTS OF THE INVENTION According to the present invention, a mixture of kaolin and an organic synthetic pigment having adhesiveness, or kaolin, a flat organic synthetic pigment, and a urea resin-based filler is selected on a base paper mainly made of wood pulp. 5 to 30 parts by weight of a styrene-butadiene copolymer latex as an adhesive, 20 to 50 parts by weight of phosphorylated esterified starch and / or acetylated starch, relative to 100 parts by weight of a pigment containing a mixture of at least two kinds as main components. Dry coating amount of 3 to 10 parts
Since the coating layer of g / m ² is provided by the air knife coater or the bar coater, the white paper surface has the texture of uncoated paper and the density of the printed surface is the same as that of the lightweight coated paper. It is possible to obtain high-quality printing paper that is equivalent or higher.

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Claims (3)

[Claims] 1. A styrene-butadiene copolymer latex 5 as an adhesive, on 100 parts by weight of a pigment containing a mixture of kaolin and an organic synthetic pigment having an adhesive force as a main component, on a base paper mainly made of wood pulp. To 30 parts by weight and 20 to 50 parts by weight of phosphoric esterified starch and / or acetylated starch, an absolute dry coating weight of 3 to 10 g / m
A high-grade printing paper, wherein the coating layer of ² is provided by an air knife coater or a bar coater. 2. On 100 parts by weight of a pigment whose main component is a mixture of at least two or more kinds selected from kaolin, flattened organic synthetic pigments and urea resin-based fillers, on a base paper whose main raw material is wood pulp. 5 to 30 parts by weight of styrene-butadiene copolymer latex as an adhesive, and phosphoric acid esterified starch and / or acetylated starch 20 to 50
A high-grade printing paper, characterized in that a coating layer having an absolute dry coating weight of 3 to 10 g / m ² is provided by an air knife coater or a bar coater. 3. The method according to J. TAPPI paper pulp test method No. The Oken smoothness specified in 5m-74 is 1
The specular glossiness is 00 seconds or less, and the incident light flux / reflected light flux = 75 ° / 75 ° specified by JIS P-8142 has a specular gloss of 15% or less and a tightness of 0.9 or less. The high-quality printing paper according to claim 1.