JP5264661B2 - Manufacturing method of coated paper for offset and gravure printing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To produce coated paper for both offset/gravure printing, improved, in a well-balanced manner, in printing strength, blister resistance and smoothness in gravure printing, and ameliorating poor operability stemmed from streaks. <P>SOLUTION: A method for producing coated paper by coating base paper with an aqueous coating composition containing a pigment and an adhesive as the main ingredients followed by drying and finishing the thus coated paper is provided. In the method, the aqueous coating composition is in the form of a coating liquid containing 60-100 pts.mass of a wet ground calcium carbonate as the pigment and containing 4.5-7.5 pts.mass, based on the whole amount of pigment, of the adhesive. The method includes the following process: a film metering size press apparatus is used on web produced by papermaking with a gap former paper machine to coat the web with 0.5-2.0 g/m<SP>2</SP>, on a bone dry basis, of a starch-based sizing liquid followed by drying the thus coated web and then subjecting the resultant web to double-sided coating with 8-13 g/m<SP>2</SP>, on single-sided bone dry basis, of the coating liquid followed by drying and then finishing the resulting web with an on-machine soft calender so as to be 0.6 &mu;m or less in smoothness as determined by Parker printsurf. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a coated paper for printing, and more specifically, a coated paper for offset / gravure printing that can be used for both offset printing and gravure printing (hereinafter also referred to as “printed coated paper”). )), Printing strength is good, blister resistance in offset rotation (hereinafter also referred to as “off wheel”) printing, and excellent smoothness in gravure printing. Related to coated paper.

  Conventionally, offset printing has been used in commercial printing and publication printing. There are two types of offset printing, sheet-fed and rotary, but in any method, a thicker ink is used than gravure ink, so paper with higher surface strength than gravure-coated paper is used. Needed. Since the ink transfer is performed through a blanket that is rich in elasticity, the printing finish is good. Therefore, the coated paper for offset printing is not required to be as smooth as the coated paper for gravure printing.

  Conventional coated paper for offset printing does not have smoothness suitable for gravure printing, and when used for gravure printing, there is a disadvantage that halftone dots called misdots occur, resulting in poor printed surface finish. It could not be used as a gravure printing application.

  In this way, unlike the characteristics suitable for offset printing and the characteristics suitable for gravure printing, they are individually marketed as printing paper suitable for each printing method, that is, coated paper for offset printing and coated paper for gravure printing. Has been.

  However, when using dedicated recording papers for various printers such as ink jet recording system and thermal transfer recording system and electrostatic photocopying (PPC) copying machines, such as information recording paper, for example, each printer and copying machine It was necessary to manage inventory of recording paper, which was complicated.

  In recent years, these shared information recording sheets have been launched and management complexity has been improved. There has been a demand for a function that can be used in combination with each printing method without regard to such shareable functions, that is, for gravure printing, offset printing, or the type of printing paper.

  On the other hand, for paper manufacturers, it is necessary to manufacture coated paper in the same lot in order to improve the efficiency and resource saving of manufacturing operations such as changing work by changing paint (coating liquid) composition and reducing material loss. It has been demanded.

  Therefore, there has been an urgent need to develop a coated paper having both characteristics suitable for offset printing and characteristics suitable for gravure printing.

  For example, a coated paper for printing is disclosed in which a specific paint is applied to a coated base paper that is not subjected to surface sizing, and the surface smoothness is finished to 0.6 μm or less (see, for example, Patent Document 1). . Also, offset and gravure common whiteboard is disclosed (for example, see Patent Documents 2 to 4).

  Furthermore, a method for producing a rotary offset printing paper in which a specific amount of a specific cationic starch is blended into a base paper and the adhesive is surface-sized pressed at a specific concentration is disclosed (for example, see Patent Document 5).

  By the way, recently, speeding up of the paper machine has been increasingly demanded in order to increase the productivity, and a production system (on-machine system) that consistently performs base paper papermaking, coating, and finishing exceeding 1300 m / min is performed. It's getting on. In such high-speed base paper making, the reform of the wire part of the paper machine greatly contributed, and the stock slurry discharged from the inlet was supplied to the gap formed by the top wire and the bottom wire, and from the beginning, the upper and lower sides High-speed papermaking has become possible with a gap former paper machine in which a sheet of wire is dewatered and a paper layer is formed.

Japanese Patent Laid-Open No. 2005-314821 JP-A-6-65898 JP 2002-363877 A JP 2006-9184 A Japanese Patent Laid-Open No. 10-280296

  However, in the technique described in Patent Document 1, since the hollow pigment is used or the wet heavy calcium carbonate content is small, the fluidity of the paint deteriorates at a high solid content, causing a streak. There remains a problem that good operability cannot be obtained.

  In addition, all of the techniques described in Patent Documents 2 to 4 provide two coating layers on the base paper surface of white paperboard, and use a specific kaolin and a specific light calcium. The problem remains that the fluidity deteriorates and good operability cannot be obtained.

  Patent Document 5 does not describe anything about gravure suitability.

  And for high-speed papermaking with a gap former paper machine, the paper stock obtained with this gap former tends to collect fine fibers and fillers on both surfaces of the paper stock compared to conventional long web and on-top formers. , Both surface layers tend to be dense and have poor permeability. Therefore, when a coated paper is produced by providing a coating layer on a paper base obtained by a gap former, the air permeability is further deteriorated, resulting in a coated paper having poor blister suitability, and is not suitable for offset rotary printing. .

  As described above, in the production of a coated paper for use as an offset printer and a gravure printer, particularly in a coated paper produced by a gap former, the offset printing sheet-fed system is used. Ensuring printing strength and improving blister resistance with the winding method are conflicting measures, and it is extremely difficult to improve both of them, and it is even more difficult to provide high smoothness in gravure printing. It is.

  Therefore, in the present invention, in the production of a coated paper for use as both an offset printer and a gravure printer, the printing strength in offset printing, blister resistance, and smoothness in gravure printing are balanced. The present invention provides an improved combined printing paper and a production method with improved operability due to streak.

  The present inventors have newly found that smoothness is likely to occur when a coating liquid is finished by applying a coating liquid to a base paper made by a gap former. In particular, it has been found that when the paper size is treated with starch, it becomes more prominent.

  Compared to conventional long web and on-top formers, the paper stock obtained with the gap former tends to collect fine fibers and fillers on both surfaces of the base paper, making both surfaces dense and poorly permeable. On the other hand, it has a tendency to become a paper sheet having a higher smoothness than conventional long webs and on-top formers.

  When the coating liquid is applied to a base paper with both surface layers obtained by the gap former and coated into a coated paper, the coating liquid is less likely to penetrate into the web, and the smoothness of the coated paper is likely to increase. It is thought to be.

  On the other hand, when it is applied to a paper web by a gap former, the air permeability resistance of the coated paper becomes high and the blister resistance during off-ring printing is inferior. Even the means described in Patent Document 5 can improve blister resistance to some extent, but in the case of a coating liquid formulation as used conventionally, blister resistance is further deteriorated particularly when the coating liquid is made highly smooth.

As a result of earnest research on the production of coated paper for use as an offset printer and a gravure printer, the inventors have made use of the characteristics of the gap former to make use of the features of the gap former. The inventors have reached the following invention. That is, the method for producing a combined coated paper for offset / gravure printing according to the present invention is a method for producing a coated paper in which an aqueous coating composition mainly comprising a pigment and an adhesive is applied and dried. the aqueous coated composition, 75 to 100 parts by weight of the total pigment 100 parts by weight of the wet ground calcium carbonate as a pigment, the proportion of 4.5 to 7.5 parts by weight of the adhesive with respect to the total pigment 100 parts by weight A coating liquid having a solid content concentration of 66% by mass or more, and a film liquid made with a gap former paper machine, a film metalling size press apparatus is used to apply a sizing liquid mainly composed of starch. 0.5-2.0 g / m ² was applied and dried at an absolute dry coating amount, and then the coating solution was applied on both sides at an absolute dry coating amount of 8-13 g / m ² and dried. Later, Parker pudding on the on-machine soft calendar Characterized in that to finish the smoothness by the surf to 0.6μm or less.

In the method for producing a combined coated paper for offset / gravure printing according to the present invention, the content of the water-soluble adhesive as the adhesive is preferably 1.5 parts by mass or less with respect to 100 parts by mass of the total pigment. . It is easy to give white paper gloss and smoothness.

  The method for producing a combined coated paper for offset / gravure printing according to the present invention can provide a combined coated paper for printing in which printing strength in offset printing, blister resistance and smoothness in gravure printing are improved in a well-balanced manner.

  Next, the present invention will be described in detail with reference to embodiments, but the present invention is not construed as being limited to these descriptions. As long as the effect of the present invention is exhibited, the embodiment may be variously modified.

The method for producing a combined coated paper for offset / gravure printing according to the present embodiment is a method for producing a coated paper in which an aqueous coating composition mainly composed of a pigment and an adhesive is applied and dried to finish. In the coating composition, wet heavy calcium carbonate as a pigment is 75 to 100 parts by mass of 100 parts by mass of the total pigment, and the adhesive is in a ratio of 4.5 to 7.5 parts by mass with respect to 100 parts by mass of the total pigment. Contain a coating solution with a solid content concentration of 66% by mass or more, and use a film metering size press to remove the sizing solution mainly composed of starch on a paper sheet made with a gap former paper machine. After applying 0.5 to 2.0 g / m ² in dry coating amount and drying, and then applying both sides of the coating solution at a dry coating amount of 8 to 13 g / m ² on one side and drying Parker print server at on-machine soft calendar 0.6μm below the smoothness by: finish (ISO 8791-4 1992 measured pressure 2000kPa). This provides a coated paper that can be shared for offset and gravure printing.

By the film metering size press to apply the size liquid mainly starch 0.5 to 2.0 g / m ² on both sides in the web, little generation of streaks when coating for coated liquid, offset It is possible to secure printing strength and impart blister resistance during printing. The coating amount of the size liquid is more preferably 0.7 to 1.6 g / m ² , and still more preferably 0.9 to 1.6 g / m ² . When starch is applied at less than 0.5 g / m ² on both sides with a film metering size press, the occurrence of streaks when applying the coating liquid is increased, and further, from the coated paper surface called piling during offset printing. This causes the pigment to fall off and a satisfactory printing strength cannot be obtained. When starch is applied on both sides in excess of 2.0 g / m ² , the air resistance increases and blister suitability in off-ring printing cannot be obtained.

  By finishing the coated paper to a smoothness of 0.6 μm or less by Parker Print Surf by soft calender treatment with high temperature (150 ° C. to 220 ° C.) and high linear pressure (250 kN / m to 330 kN / m) on-machine. This makes it possible to sufficiently reduce the number of miss dots in gravure printing. The smoothness by Parker Print Surf is more preferably 0.57 to 0.45 μm, and further preferably 0.55 to 0.50 μm. If the smoothness by Parker Print Surf exceeds 0.6 μm, misdots are conspicuous and the value as a product after printing is lost.

The coating solution contains wet heavy calcium carbonate as a pigment in a ratio of 75 to 100 parts by mass out of 100 parts by mass of the total pigment, and an adhesive in a ratio of 4.5 to 7.5 parts by mass with respect to 100 parts by mass of the total pigment. what the solid concentration 6 of 6 mass% or more, is coated on one side absolute dry laydown 8~13g / ^{m 2.} More preferably, wet heavy calcium carbonate is 75-90 mass parts, More preferably, it is 75-85 mass parts. The solid content concentration is more preferably 66 to 72% by mass, and still more preferably 67 to 71% by mass. Furthermore, the single-sided absolute dry coating amount is more preferably 9 to 12 g / m ² , and still more preferably 10 to 11 g / m ² .

If the wet heavy calcium carbonate is less than 75 parts by mass, blister suitability in off-ring printing cannot be obtained, and the fluidity of the coating liquid at a solid content concentration of 66 % or more is inferior. There is. However, when the wet heavy calcium carbonate is 75 parts by mass or more, by including the adhesive in a proportion of 4.5 to 7.5 parts by mass with respect to the total pigment, it is excellent in strength in offset printing and smoothness. And the blister suitability can be balanced, and the fluidity of the coating liquid is excellent and the occurrence of streaks is small.

  When the adhesive is contained at a ratio of less than 4.5 parts by mass with respect to the total pigment, the pigment is detached from the coated paper surface called “piling” in offset printing, and the printing workability is not sufficient. Problems arise. On the other hand, when the adhesive is contained in an amount exceeding 7.5 parts by mass with respect to the total pigment, no piling occurs in offset printing, but the air permeability resistance of the coated paper increases, and during off-ring printing. The blister resistance of deteriorates.

If the absolute dry coating amount is less than 8 g / m ^{2 on} one side, it becomes difficult to finish the coated paper to have a smoothness of 0.6 μm or less by Parker Print Surf, and the occurrence of misdots in gravure printing becomes remarkable. On the other hand, if the absolute dry coating amount exceeds 13 g / m ² on one side, there is no problem with misdots in gravure printing, but the air resistance of the coated paper is further increased and blister resistance during off-ring printing is improved. Getting worse.

  As described above, after applying starch to the base of paper using a film metering size press on base paper using a gap former, it is suitable for offset and gravure printing by applying a specific coating solution and smoothing it. Coated paper can be produced.

  Next, a preferable example of the combined printing paper for printing according to this embodiment will be specifically described. The coated base paper used in the present embodiment is made of chemical pulp such as hardwood bleached kraft pulp, softwood bleached kraft pulp, mechanical pulp such as GP and TMP, and pulp derived from waste paper as a raw material. The paper is made with a mer and gap former.

  In the paper stock when making the base paper, paper strength enhancers such as cationic starch and polyacrylamide, rosin size, alkenyl succinic anhydride, alkyl ketene dimer, sizing agent such as synthetic sizing agent, talc, calcium carbonate, In addition to synthetic zeolite, fillers such as titanium, yield improvers such as colloidal silica, polyacrylamide, and polyethylene oxide, paper making aids such as filtering agents, and hue adjusting chemicals such as fluorescent dyes and colored dyes are also included.

  After a web is formed on the wire, it is dehydrated in a press part and dried in a predryer part. After the pre-dryer, starch is applied and dried with a film metering size press.

Examples of the starch applied by the film metering size press include thermochemically modified starch, carbamate starch, oxidized starch, and esterified starch. If necessary, substances other than pigments and / or starch can be blended, but it is necessary that the dry coating amount of starch is 0.5 to 2.0 g / m ^2. is there.

  After the starch is applied with a film metering size press and dried, the coating solution is applied with a blade coating machine.

The coating liquid composition is composed of a pigment, an adhesive, and an auxiliary agent. As the pigment, 75 to 100 parts by mass of wet heavy calcium carbonate is used out of 100 parts by mass of the total pigment . As wet heavy calcium carbonate, commercially available products with a mass accumulation ratio of 60%, 90%, 97% and 100% with a particle size under 2 μm are used, and so-called engineered wet weight with a uniform particle size distribution. Calcium carbonate can also be used, but from the viewpoint of white paper gloss and smoothness, it is preferable to use a material with a particle diameter under 2 μm and a mass cumulative ratio of 90% or more. Except when wet heavy calcium carbonate is used as the total pigment, kaolin, light calcium carbonate, titanium oxide, plastic pigment, and the like are used as necessary.

  There is no restriction | limiting in particular as a kind of adhesive agent, A well-known binder can be used. For example, various copolymer latexes such as styrene / butadiene, styrene / acrylic, vinyl acetate / acrylic, butadiene / methylmethacrylic, etc., or polyvinyl alcohol, oxidized starch, esterified starch, thermochemically modified starch, enzyme-modified starch And water-soluble adhesives such as cold water soluble starch, casein, and dextrin obtained by flash drying them. The adhesive is contained at a ratio of 4.5 to 7.5 parts by mass with respect to the total pigment. The content of the water-soluble adhesive contained in the adhesive is 1.5 parts by mass or less, preferably 1 part by mass or less. When the content of the water-soluble adhesive exceeds 1.5 parts by mass, it becomes difficult to obtain white paper gloss and smoothness. Further, the copolymer latex is preferably a styrene / butadiene latex that easily develops strength.

  As auxiliary agents, fluorescent dyes, colored pigments and dyes are appropriately used in addition to pH adjusters, antifoaming agents, dispersants, lubricants, printability improvers, thickeners, and water retention agents.

  After coating the coating liquid, it is dried by a drying method such as hot air drying, infrared drying, drum drying, etc. with a known dryer, and then smoothed and glossed with a soft calender to produce a combined printing paper for printing. can get.

  EXAMPLES Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto. In Examples and Comparative Examples, “%” means mass%. The composition of the coating liquid composition (coating liquid) is shown in parts.

Example 1
Content of light calcium carbonate (trademark TP121 made by Okutama Kogyo Co., Ltd.) per 90% dry pulp mass in 90% of freeness 450ml CSF (Canadian standard freeness) hardwood bleached kraft pulp, 10% freeness 550ml CSF conifer bleached kraft pulp 10%, cationic starch (trademark Neotac 40T made by Nippon Food & Chemicals Co., Ltd.) as a paper strength agent is added at 0.8% per 100% of dry pulp mass, further dye is added, and a gap fore is added using a yield improver. A paper sheet having a basis weight of 45 g / m ² was made at a speed of 1,400 m / min. Next, after drying the web on-machine, the film metalizing size press machine was used as a sizing solution with a 14% solid content of phosphate esterified starch (MS # 4600, manufactured by Nippon Shokuhin Kako Co., Ltd.) in a dry coating amount of 1 .6 g / m ² was coated on both sides and dried to obtain a base paper. Thereafter, the coated solution was applied on both sides by 10 g / m ² on one surface absolute dry laydown by a blade coater has a paper machine and the integral, dried, soft calender four became production lines integrally Was used at a temperature of 180 ° C. and a linear pressure of 250 kN / m to finish the combined use paper for printing of Example 1. The composition of the coating solution used in the blade coating machine was as follows.
(Composition composition of coating solution)
Pigment Fine kaolin clay (from USA, average particle size 0.4 μm) 20 parts Wet heavy calcium carbonate Carbital 90 (Imeris, average particle size 1.0 μm, particle size 2 μm under mass cumulative rate 90%) 80 parts Phosphate esterified starch MS # 4600 (manufactured by Nippon Shokuhin Kako Co., Ltd.) 1 part ・ Styrene butadiene latex S2788K (manufactured by JSR) 6 parts ・ Lubricant DEF783TF (manufactured by Nisshin Chemical Co., Ltd.) 0.6 part ・ Printability improver PA6502 (Manufactured by Starlight PMC Co., Ltd.) 0.3 part solid content concentration 68.0% by mass

The streak condition at the time of coating and the physical properties of the obtained coated paper for printing were evaluated and measured by the following methods, and are summarized in Table 1.
(1) Glossiness of white paper The glossiness of the white paper portion of the 75 ° coated surface of paper / paperboard according to JIS P 8142: 2005 “Paper and paperboard—Measurement method of 75 ° specular gloss” was measured.
(2) Smoothness The smoothness was measured by Parker Print Surf (described in ISO 8791-4: 1992) under a pressure of 2000 kPa under measurement conditions. It shows that smoothness is so high that a numerical value is low.
(3) Offset printing sheet machine (printing strength)
After printing 5,000 sheets of double-use coated paper at a printing speed of 12,000 sheets / hour on a Mitsubishi 4K diamond four-color machine, visually check for blanket stains and paper smudges to determine marketability. It was. The ink used was Fusion-G manufactured by DIC.
Judgment criteria ○ ・ ・ There is no dirt on the blanket or paper blur, and there is marketability.
△ ・ ・ Blanket is dirty and paper is missing, but it is marketable at the lowest level.
× ・ Blanket is dirty, paper is missing, and there is no marketability.
(4) Offset (printing) rotary press (blister resistant)
A double coated paper for printing was printed at a printing speed of 600 rpm with a lithopia 4-color machine manufactured by Mitsubishi Heavy Industries, Ltd., and evaluation was made with ○ indicating that no blister occurred at a paper surface temperature of 140 ° C. and × indicating generated. As the ink, WEB REX IMPACT manufactured by Dainichi Seika Kogyo Co., Ltd. was used.
(5) Printing was performed using a net gravure plate by a Ministry of Finance Printing Bureau type gravure printing aptitude tester (manufactured by Kumagai Riki Kogyo Co., Ltd.), and the missing dots at 10 to 70% halftone dots were visually evaluated. As the ink, OGH91 Sumi manufactured by Toyo Ink Manufacturing Co., Ltd. was used.
Criteria ○ ・ ・ There is no missing dot and there is marketability.
△ ・ ・ There is a missing dot, but there is marketability at the lower limit level.
× ・ ・ Missing dots with no marketability.
(6) Streak When the coating solution was applied with a blade coating machine, the occurrence of streaks was visually evaluated.
Judgment criteria ○ ・ ・ No streak.
△ ・ ・ Streak is generated, but there is no problem.
× ・ ・ There is a streak and there is a problem in operability.

(Example 2)
The combined printing paper of Example 2 was finished in the same manner as in Example 1 except that the absolute dry coating amount of the coating solution of the blade coating machine was 8 g / m ^{2 on} one side.

(Example 3)
The combined printing paper of Example 3 was finished in the same manner as in Example 1 except that the absolute dry coating amount of the coating liquid of the blade coating machine was 12.5 g / m ^{2 on} one side.

Example 4
The combined printing paper of Example 4 was finished in the same manner as in Example 1 except that the absolute dry coating amount of the sizing liquid of the film metering size press was 0.5 g / m ^{2 on} both sides.

(Example 5)
The combined printing paper of Example 5 was finished in the same manner as in Example 1 except that the absolute dry coating amount of the sizing liquid of the film metering size press was 2.0 g / m ^{2 on} both sides.

( Reference Example 6)
Blade coating machine coated liquid 40 parts by mass of fine kaolin clay, wet heavy 60 parts by weight of calcium carbonate, except for using 65 wt% solids concentration, of Reference Example 6 in the same manner as in Example 1 The coated paper for printing was finished.

(Example 7)
The combined printing paper of Example 7 was used in the same manner as in Example 1 except that 100 parts by weight of wet heavy calcium carbonate as the coating liquid of the blade coating machine was used and the solid content concentration was 70% by weight. Finished.

(Example 8)
Implemented in the same manner as in Example 1 except that 0.5 parts by mass of phosphate esterified starch, 4 parts by mass of styrene / butadiene latex, and 70% by mass of the solid content in the coating solution of the blade coating machine were used. The combined printing paper of Example 8 was finished.

Example 9
The combined printing paper of Example 9 was finished in the same manner as in Example 1 except that 6.5 parts by mass of styrene / butadiene latex as the coating solution of the blade coating machine was used.

(Comparative Example 1)
The coated paper for printing of Comparative Example 1 was finished in the same manner as in Example 1 except that the dry coating amount of starch in the film metering size press was not used.

(Comparative Example 2)
A coated paper for printing of Comparative Example 2 was finished in the same manner as in Example 1 except that the starch dry coating amount on a film metalling size press was 2.5 g / m ^{2 on} both sides.

(Comparative Example 3)
Comparative Example 3 was finished in the same manner as Example 1 except that the absolute dry coating amount of the coating solution of the blade coating machine was 7 g / m ² .

(Comparative Example 4)
Comparative Example 4 was finished in the same manner as in Example 1 except that the absolute dry coating amount of the coating solution of the blade coating machine was 13.5 g / m ² .

(Comparative Example 5)
Comparative Example 5 in the same manner as in Example 1 except that the fine kaolin clay of the coating solution of the blade coating machine was 45 parts by mass, the wet heavy calcium carbonate was 55 parts by mass, and the solid content concentration was 65% by mass. The coated paper for printing was finished.

(Comparative Example 6)
The coated paper for printing of Comparative Example 6 was finished in the same manner as in Example 1 except that 8 parts by mass of styrene / butadiene latex as the coating liquid of the blade coating machine was used.

(Comparative Example 7)
The coated paper for printing of Comparative Example 7 was finished in the same manner as in Example 1 except that 3 parts by mass of styrene / butadiene latex as the coating solution of the blade coating machine was used.

As can be seen from Table 1, Examples 1 to 5 and 7 to 9 have no streak, good white paper gloss, excellent smoothness, printing strength, blister resistance, and low misdots. Was balanced about. On the other hand, since the comparative example 1 made the starch completely dry coating amount in a film metalizing size press, streak occurred, it was inferior in smoothness, and inferior in printing strength. In Comparative Example 2, blister resistance was inferior because the starch dry coating amount in a film metering size press was as large as 2.5 g / m ² . In Comparative Example 3, since the absolute dry coating amount of the coating solution was as small as 7 g / m ² , the smoothness was inferior and the generation of misdots occurred. In Comparative Example 4, the absolute dry coating amount of the coating solution was as large as 13.5 g / m ² , so the blister resistance was inferior. In Comparative Example 5, since there was little wet heavy calcium carbonate in the pigment, streaks occurred and blister resistance was poor. Since the comparative example 6 had many adhesive agents , it was inferior in smoothness and inferior in blister resistance. Comparative Example 7 was inferior in printing strength because there was little adhesive .

Claims (2)

In a coated paper manufacturing method in which an aqueous coating composition mainly composed of a pigment and an adhesive is applied and dried to finish,
The aqueous coating composition is composed of 75 to 100 parts by mass of wet heavy calcium carbonate as a pigment in 100 parts by mass of the total pigment, and 4.5 to 7.5 parts by mass of the adhesive with respect to 100 parts by mass of the total pigment. A coating solution containing at a ratio and having a solid content concentration of 66% by mass or more ,
Using a film metering size press, apply a sizing liquid mainly composed of starch to 0.5 to 2.0 g / m ² in an absolutely dry coating amount on a paper sheet made with a gap former paper machine. Dry,
Subsequently, both sides of the coating solution are applied at an absolute dry coating amount of 8 to 13 g / m ² on one side and dried, and then the smoothness by Parker Print Surf is finished to 0.6 μm or less with an on-machine soft calendar. A method for producing a combined coated paper for offset / gravure printing. The content of the water-soluble adhesive as an adhesive, the offset gravure printing shared coated paper according to claim 1, characterized in that 1.5 parts by mass or less relative to the total pigment 100 parts by weight Production method.