JP2008223202A - Coated paper for web offset printing and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coated paper for web offset printing excellent in glossiness, base paper-coating property and printing surface feeling and scarcely generating wavy wrinkle and blister, and to provide a method for producing the coated paper. <P>SOLUTION: The coated paper for web offset printing has a coated layer mainly consisting of a pigment and an adhesive on a polyvinyl alcohol coated layer obtained by applying a coating liquid containing expanded polyvinyl alcohol having an average foam diameter of ≥10 μm and ≤1,000 μm at a coating amount of ≥0.5g/m<SP>2</SP>and ≤8.0g/m<SP>2</SP>as a solid content, expressed in terms of polyvinyl alcohol, based on one side of the base paper onto the one side or both sides of a base paper. The method for producing the coated paper is also provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to coated paper for rotary offset printing. More specifically, the present invention relates to a coated paper for rotary offset printing, which is excellent in glossiness, base paper coverage, and printing surface feel, and has less generation of creases and blisters during rotary offset printing, and a method for producing the same.

  In recent years, in the field of offset printing, simultaneous multi-color printing and speeding up of printing have been promoted in accordance with the increasing demand for printed materials and labor savings, and the demands for operability and printing quality for printing paper have become increasingly severe. Yes. In particular, in rotary offset printing, the printed matter is forced to dry at high temperatures, and therefore, wrinkles and blisters not found in other printing methods are likely to occur. Since the generation of the elbow and blister significantly deteriorates the appearance of the printed matter and greatly impairs the commercial value, a technology corresponding to the elbow and blister is required for the coated paper for rotary offset printing.

  A blister is a state in which, when offset rotary printing is applied to a coated paper for printing, the moisture contained in the base paper is instantly evaporated and the coating layer swells during forced drying at high temperature. This is because the vapor escape area is insufficient in the printing section, so that the water vapor pressure is superior to the paper layer strength, and the paper layer is destroyed and expanded. As a method for suppressing blisters, a method for increasing the internal bond strength of the base paper, a method for increasing the air permeability of the printing coated paper in the direction of good air permeability, etc. by making the coating layer porous are proposed.

  On the other hand, Hijiwa is a wavy wrinkle in the flow direction of the paper that occurs when the ink on the paper is subjected to high-temperature forced drying after applying the offset rotary printing to the coated paper for printing, which significantly deteriorates the appearance of the printed matter. Is. Many studies have been made on the cause of the occurrence of wrinkles, and it is thought that this is caused by the difference in the amount of drying shrinkage between the printed part and the non-printed part in the drying process. In the printing and non-printing areas covered with ink, during high-temperature forced drying, the non-printing area has a faster evaporation rate of moisture in the paper, so the shrinkage starts first, and the printing area has a lateral compressive force. As a result, wrinkles occur in the printing unit.

  Several methods have been proposed to control bulges. A method has been proposed in which the freeness of the pulp of the base paper in the coated paper for offset rotary printing is maintained in a specific range, and the air permeability is restricted to a region having good air permeability (see, for example, Patent Document 1). However, since freeness and air permeability are inversely correlated, it is difficult to adjust the operability within the production cost.

  In addition, a technique for eliminating or reducing wrinkles has been proposed by defining the internal bond strength between the winding water and the base paper (see, for example, Patent Document 2). However, reducing the internal bond strength promotes the generation of blisters, which is another problem with coated paper for offset rotary printing. In order to prevent this, it is necessary to lower the water content of the coated paper, but a phenomenon that the surface of the coated layer breaks easily in the subsequent folding process. In addition, the take-up moisture is likely to fluctuate due to many factors, and it is difficult to adjust the take-up moisture.

  In addition, a method has been proposed in which shrinkage during high-temperature forced drying in offset rotary printing is suppressed and wrinkles are reduced by using a base paper coated with a specified amount of a polyvinyl alcohol aqueous solution having a specific saponification degree (for example, And Patent Document 3). Also proposed is a method for reducing wrinkles by applying a polyvinyl alcohol aqueous solution having a specific viscosity to a base paper so that the drying shrinkage of the coated paper for rotary offset printing falls within a specific range. (For example, see Patent Document 4). In these methods, by covering the base paper with a resin film of an aqueous polyvinyl alcohol solution, during the high-temperature forced drying applied after printing of the coated paper, the evaporation of moisture from the non-printing part is suppressed, and the printing part and The purpose is to eliminate the difference in drying shrinkage of the non-printed part.

However, such a coated paper for rotary offset printing is effective for suppressing wrinkles, but on the other hand, printing unevenness is likely to occur as the ink acceptability deteriorates, and is further provided on the top of the polyvinyl alcohol layer. The print surface quality may be impaired due to generation of characteristic pores in the layer. In addition, when applying a polyvinyl alcohol aqueous solution to the base paper, it may be possible to adjust the size of the base paper to suppress the penetration of the polyvinyl alcohol aqueous solution into the base paper and improve the printing surface quality. Such a coated paper for printing has poor coating properties on the base paper of polyvinyl alcohol, and since the penetration is insufficient, the decrease in internal bond strength is conspicuous, which is another problem of coated paper for offset rotary printing. Helps generate a blister.
JP 58-186700 A JP-A-9-291696 JP-A-11-350391 JP 2000-45199 A

  An object of the present invention is to provide a coated paper for rotary offset printing, which is excellent in gloss, base paper coverage, and printing surface feel, and is less likely to generate wrinkles and blisters during rotary offset printing, and a method for producing the same.

As a result of intensive studies in view of the above, the present inventor has obtained a polyvinyl alcohol-containing coating liquid in which the average cell diameter is 10 μm or more and 1000 μm or less on one side or both sides of the base paper, and the amount of coating on one side solid content in terms of polyvinyl alcohol Web offset printing characterized by having a coating layer mainly composed of a pigment and an adhesive on a polyvinyl alcohol coating layer formed by coating at 0.5 g / m ² or more and 8.0 g / m ² or less. Came to invent coated paper.

  ADVANTAGE OF THE INVENTION According to this invention, the coated paper for rotary offset printing which is excellent in glossiness, base paper coverage, and printing surface feeling, and there are few generation | occurrence | production of a wrinkle and a blister at the time of rotary offset printing is provided.

  Hereinafter, the coated paper for rotary offset printing of the present invention will be described in detail.

The present inventor applied a polyvinyl alcohol-containing coating liquid foamed with an average cell diameter of 10 μm or more and 1000 μm or less on one side or both sides of a base paper to a polyvinyl alcohol equivalent single-side solid content coating amount of 0.5 g / m ² or more 8 By providing a coating layer mainly composed of a pigment and an adhesive on a polyvinyl alcohol coating layer formed by coating at a rate of 0.0 g / m ² or less, the gloss, base paper coverage, and printing surface feel are excellent. In addition, it has been found that a coated paper for offset rotary printing can be provided that generates less wrinkles and blisters during offset rotary printing.

  The coated web for offset rotary printing of the present invention is a conventional coated web for rotary offset printing, except that the base paper is coated with a foamed polyvinyl alcohol-containing coating solution so that the average cell diameter is 10 μm or more and 1000 μm or less. Similarly to paper, it can be produced by providing a coating layer mainly composed of a pigment and an adhesive on one side or both sides of a base paper provided with layers of polyvinyl alcohol on both sides.

  In the present invention, the “base paper” refers to a paper sheet before applying the polyvinyl alcohol-containing coating solution, and the “base paper” is provided with a coating layer containing polyvinyl alcohol on one or both sides of the base paper. A sheet that is a sheet and is not provided with a coating layer mainly composed of a pigment and an adhesive, and is distinguished from a “base paper”.

  Since the base paper used for the coated paper for printing is usually composed of a hydrophilic fibrous compound, it is hydrophilic, has many voids for absorbing moisture, and has high water absorption. Therefore, when the polyvinyl alcohol-containing coating solution is applied directly to the base paper, dehydration of water in the polyvinyl alcohol-containing coating solution starts from the moment when the polyvinyl alcohol-containing coating solution comes into contact with the base paper. Dehydration occurs toward the center of the base paper. In addition, when coating a polyvinyl alcohol-containing coating solution on the base paper, the film transfer coater such as size press, gate roll, shim sizer, air knife coater, rod coater, blade coater, etc. Pressure is applied. Therefore, the polyvinyl alcohol-containing coating liquid falls into the gaps in the base paper due to these dehydration and pressure. In addition, polyvinyl alcohol is contained until most of the voids of the base paper are filled with the solid component of the coating liquid, or until the coating liquid is dehydrated and the dispersed components are aggregated and solidified, that is, the immobilization phenomenon occurs. The drop of the coating liquid will continue.

  In order to suppress the drop of the polyvinyl alcohol-containing coating solution, methods such as increasing the solid content concentration of the polyvinyl alcohol-containing coating solution or adjusting the voids of the base paper are generally used. Disadvantages such as deterioration of coating operability and surface quality are likely to occur due to thickening of the working fluid. Moreover, if the coating amount of the polyvinyl alcohol-containing coating solution is increased, a coated paper for printing having good coverage of the polyvinyl alcohol on the base paper can be obtained. However, the liquid cost is increased and the drying load of the coating solution is increased. There is a problem that is large. Eventually, a technique for improving the coverage of the base paper without increasing the coating amount of the polyvinyl alcohol-containing coating solution has not been found.

  The present inventor studied to directly apply a polyvinyl alcohol-containing coating solution which was foamed so that the average cell diameter was 10 μm or more and 1000 μm or less on the base paper. When foam is included in the coating liquid, the foam is pushed in the direction of the base paper by the pressure applied. For this reason, the pressure of the void inside the base paper increases, the drop of the coating liquid into the base paper is suppressed, the contact area between the base paper and the coating liquid is reduced, and the coating liquid undergoes dehydration behavior. The degree is reduced. Therefore, the coverage with respect to the base paper is good without increasing the coating amount of the polyvinyl alcohol-containing coating solution, and further, at the time of high-temperature forced drying applied after printing of the coated paper, the printing part and the non-printing part In order to reduce the drying shrinkage difference, it is possible to obtain a coated paper for printing that is effective in suppressing wrinkles.

In the present invention, a polyvinyl alcohol-containing coating liquid foamed so that the average cell diameter is 10 μm or more and 1000 μm or less on one side or both sides on a base paper is 0.5 g / m ² on a single-sided solid content coating amount in terms of polyvinyl alcohol. above 8.0 g / m ² but characterized in that it is coated in the following ranges, the average cell diameter of the polyvinyl alcohol-containing coating liquid is less 1000μm or more 10μm applied to a layer provided directly on the base paper By maintaining the range, the effect of suppressing the dropping of the coating liquid into the inside of the base paper is easily exhibited, and the effect of improving the coverage of polyvinyl alcohol on the base paper is obtained. When the average bubble diameter is larger than 1000 μm, the pressure of the voids inside the base paper is not high enough to prevent the coating liquid from dropping into the base paper. On the other hand, if the average bubble diameter is less than 10 μm, the pressure becomes too high to enter the base paper and it is difficult to impart blister resistance.

  In the present invention, a polyvinyl alcohol-containing coating solution is directly applied to a base paper so as to have an average cell diameter of 10 μm or more and 1000 μm or less. Since the polyvinyl alcohol aqueous solution has good foaming properties, it is easy to generate fine bubbles and the stability of the bubbles is good. It can be provided in a held state, and compared to other media, the effect of suppressing the coating liquid from dropping into the inside of the base paper is easily exhibited, and the effect of improving the coverage of the base paper is easily obtained.

  Here, the measuring method of the average diameter of the foam contained in the polyvinyl alcohol containing coating liquid is described. The coating solution is placed on a uniform film-like substrate having no affinity for the solvent component of the coating solution, and freeze-dried. This is observed with an electron microscope, the diameter of 100 randomly selected bubbles is measured, and the average value is taken as the average diameter of the bubbles.

  In the present invention, foam is intentionally added to improve the covering property of the polyvinyl alcohol on the base paper, and the surface of the polyvinyl alcohol layer is likely to be disturbed, but on the polyvinyl alcohol layer having a good covering property. By providing a coating layer mainly composed of a pigment and an adhesive, the glossiness and the printing surface feeling as a coated paper for printing are greatly improved. Furthermore, the polyvinyl alcohol-containing coating layer as described above provided directly on the base paper has a sufficient covering property, and the dehydration behavior that is received before the coating layer provided on the upper layer of the polyvinyl alcohol is immobilized. As a result, a coating layer which is smooth and has a uniform coating layer film pressure and a uniform coating layer internal structure can be obtained. By applying foam to the polyvinyl alcohol aqueous solution, the coating property of polyvinyl alcohol on the base paper is improved, and by providing a coating layer on the upper part, the printing coating with good base paper coverage is finally obtained. You can get crafted paper.

The polyvinyl alcohol-containing coating solution according to the present invention is applied to one side or both sides of a base paper in a range of a polyvinyl alcohol equivalent single-sided solid content coating amount of 0.5 g / m ² or more and 8.0 g / m ² or less. When the coating amount of single-sided solid content in terms of polyvinyl alcohol is less than 0.5 g / m ² , the coverage of polyvinyl alcohol on the base paper is not good. Moreover, when there are more polyvinyl alcohol conversion single-sided solid content coating amounts than 8.0 g / m < ² >, there exists a problem that the liquid cost increases and the drying load of a coating liquid is large.

  In the present invention, the method of directly providing the polyvinyl alcohol layer on the base paper is not limited at all, and various film transfer coaters such as size press, gate roll, shim sizer, blade coater, air knife coater, rod coater, curtain coater. Etc. However, when applying a coating solution containing polyvinyl alcohol containing foam, the curtain coater is weaker in pressure than the other coater, and the amount of falling into the base paper is insufficient to impart blister resistance. Is difficult. In addition, when a size press coater manufactures a base paper with a paper machine, it can be surface-treated on the paper machine, which is preferable in terms of ease of manufacture and simplification of the manufacturing process. Moreover, the coating method of the coating layer provided in the upper part of the layer of polyvinyl alcohol is not restrict | limited at all.

  The polyvinyl alcohol used in the present invention is not particularly limited, and commercially available products having a saponification degree of 80 to 100% and a polymerization degree of 200 to 2,500 can be used. In addition to unmodified polyvinyl alcohol, various modified polyvinyl alcohols such as carboxy-modified, sulfone-modified, acetoacetyl-modified, cation-modified, silanol-modified and terminal alkyl-modified can also be used. Moreover, the solid content concentration of the polyvinyl alcohol aqueous solution is not particularly limited, but is in the range of 5 to 30% by mass, and preferably in the range of 10 to 20% by mass. When there is more polyvinyl alcohol than that, the viscosity of a paint will rise rapidly and handling and actual operation will become difficult, and it is not preferable.

  In the aqueous polyvinyl alcohol solution according to the present invention, a pigment, a dispersant, a lubricant, an adhesive, and a thickener are used as long as the average cell diameter of the foam contained in the coating liquid after foaming is in the range of 10 μm to 1000 μm. Various auxiliary agents such as the above may be combined as appropriate and then foamed. If the average cell diameter of the foam contained in the coating liquid after foaming is finally within the above range, various aids such as pigments, dispersants, lubricants, adhesives, thickeners, etc., during foaming or after foaming. An agent may be added and mixed.

  The base paper used in the present invention includes chemical pulps such as LBKP and NBKP, mechanical pulps such as GP, PGWRMP, TMP, CTMP, and CGP, and various pulps such as waste paper pulp, light calcium carbonate, heavy calcium carbonate, Various fillers such as talc, clay and kaolin, various sizing agents such as sizing agent, fixing agent, retention agent and paper strength enhancer are suitably blended to make paper, and any of acidic, neutral and alkaline papers can be used.

  As the paper machine in the paper making method of the base paper in the present invention, a paper machine known in the paper industry such as a long paper machine, a twin wire paper machine, a combination paper machine, a circular paper machine, and a Yankee paper machine can be used as appropriate.

  The present invention relates to a coated paper for printing, and generally any material used for producing a coated paper for printing may be blended. The pigment blended in the coating layer mainly composed of the pigment and adhesive according to the present invention is not particularly limited. For example, kaolin, clay, heavy calcium carbonate, light calcium carbonate, titanium dioxide, satin white, Examples include talc, aluminum hydroxide, and plastic pigment. These may be used alone, and the use of a plurality of these in combination is not limited.

  The adhesive compounded in the coating layer mainly composed of the pigment and the adhesive according to the present invention is not particularly limited, and examples thereof include ordinary starch, oxidized starch, phosphate esterified starch, enzyme-modified starch and the like. Fresh water-dried starch such as cold water soluble starch, various copolymer latexes such as styrene-butadiene, acrylic and vinyl acetate, polyvinyl alcohol, sodium polyacrylate, polyethylene oxide, polyacrylamide, urea or melamine Water-soluble synthetic compounds such as / formalin resin, polyethyleneimine, polyamidepolyamine / epichlorohydrin, natural products such as wax, casein, soybean protein, and those obtained by cationizing these. These may be used alone, and the use of a plurality of these in combination is not limited.

  In addition, the coating liquid for forming the coating layer mainly composed of the pigment and the adhesive according to the present invention includes, for example, carboxymethyl cellulose, sodium alginate, methyl cellulose, hydroxyethyl cellulose, casein, poly, as a thickener. Water-soluble polymers such as sodium acrylate, polyacrylates, synthetic polymers such as styrene-maleic anhydride copolymers, silicates, etc. may be used in combination, and if necessary, dispersant, pH adjustment Agents, lubricants, antifoaming agents, water resistance agents, surfactants, antifoaming agents, mold release agents, foaming agents, penetrants, coloring dyes, fluorescent whitening agents, UV absorbers, antioxidants, preservatives, Various auxiliaries such as anti-biking agents, and those obtained by cationizing these various auxiliaries can also be used.

The coating amount of the coating layer mainly composed of the pigment and the adhesive according to the present invention is not particularly limited, but is generally 1.0 g / m ² or more and 25.0 g / m ² or less per side. Preferably, it is the range of 3.0 g / m ² or more and 12.0 g / m ² or less. In addition, the method of providing a coating layer mainly composed of a pigment and an adhesive is not limited at all, and various film transfer coaters such as size press, gate roll, shim sizer, blade coater, air knife coater, rod coater, curtain Examples include coaters.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

The physical properties of the coated paper for printing in each example and comparative example were evaluated by the following methods.
<Evaluation method>
1) Glossiness The glossiness of the coated paper for printing was evaluated based on white paper glossiness at an angle of 75 ° -75 ° reflectance according to JIS P8142. However, in the present invention, four or more points are the objects of the invention.
5 points: White paper gloss of 74% or more 4 points: White paper gloss of 70% or more and less than 74% 3 points: Blank paper gloss of 66% or more but less than 70% 2 points: Blank paper gloss of 62% or more but less than 66% 1 point: Blank paper gloss Is less than 62%

2) Base Paper Coverage The obtained coated paper for printing was cut into A4 size and immersed in a solution of deionized water / ethanol / ammonium chloride = 50/45/5 (mass ratio) for 1 hour. Thereafter, the coated paper for printing was taken out of the solution and sandwiched with filter paper to wipe off the excess solution. Further, it was put in a dryer at 150 ° C. for 3 hours and then taken out. As a result, the base paper portion made of organic matter was burnt brown, and the portion covered with the coating layer remained white. The more white parts, the better the base paper is covered with the coating layer. This degree was judged visually and evaluated in the range of 1 to 5 points. However, in the present invention, four or more points are the subject of the invention.
5 points: There are almost no brown parts and almost all are white parts.
4 points: The brown part is present but slightly visible, and the white part is overwhelming.
3 points: The brown part is visible, but the white part is more.
2 points: The ratio of the brown part to the white part is about the same.
1 point: There are more brown parts.

3) Printing surface feel Using an offset rotary printing press (Mitsubishi Heavy Industries, Ltd., Lithopia BT-2-600), offset rotary printing ink (Dainippon Ink & Chemicals, Inc., Web World Terrace N black) , Indigo, red, and yellow), the solid printed portion was visually determined, and the printing surface feeling was evaluated in the range of 1 to 5 points. 5 points are the printing surface is flat and there is no unevenness and there is no opacity unevenness and ink receiving unevenness, 1 point is the state where the printing surface is uneven due to the unevenness of the base paper, and there are many opacity unevenness and ink receiving unevenness Indicates that However, in the present invention, four or more points are the subject of the invention.

4) Hijiwa Offset rotary printing press (Mitsubishi Heavy Industries, Ltd., Lithopia BT-2-600 type), Printing ink for rotary offset (Dainippon Ink Chemical Co., Ltd., Web World Terrace N black and indigo) , Red, and yellow), and the flow direction of the solid print portion was visually evaluated. The evaluation of Hijiwa was written as follows.
A: Almost no wrinkles are generated.
○: Mild crease is observed.
(Triangle | delta): Although generation | occurrence | production of a wrinkle is recognized, it is a level which can be practically endured.
X: Occurrence of tight wrinkles is observed.
However, in the present invention, the allowable range is Δ or more.

5) Blister suitability Using an offset rotary printing press (Mitsubishi Heavy Industries, Ltd., Lithopia BT-2-600), offset rotary printing ink (Dainippon Ink Chemical Co., Ltd., Web World Terrace N black) Indigo, red, and yellow) were used to check for the occurrence of blisters. The evaluation of blister was described as follows.
○: Little blister occurs.
Δ: Mild blistering is observed.
X: Generation | occurrence | production of a tight blister is recognized.
However, in the present invention, the allowable range is Δ or more.

The base paper was prepared with the following composition, and a base paper for coating having a basis weight of 89 g / m ² was made. A mass part here is the solid content mass ratio of each material with respect to 100 mass parts of total pulp solid content.
<Base paper formulation>
LBKP (freeness 440 mlcsf) 70 parts by mass NBKP (freeness 490 mlcsf) 30 parts by mass <Internally added chemicals>
Light calcium carbonate (indicated by ash content in base paper) 6.0 parts by mass Commercial cationized starch 1.0 part by mass Commercially available cationic polyacrylamide yield improver 0.030 parts by mass

Example 1
Polyvinyl alcohol obtained by adding water so as to have a solid content concentration of 20% by mass with respect to a commercially available polyvinyl alcohol having a polymerization degree of 400 and a saponification degree of 98 mol%, and heat gelatinizing the base paper obtained as above Using a continuous foaming machine (TARBO-MIX manufactured by Aikosha Co., Ltd.), the aqueous solution was mixed with bubbles having an average cell diameter of 100 μm by adjusting the amount of compressed air sent. This polyvinyl alcohol-containing coating solution was applied using a size press coater under the conditions of an operation speed of 100 m / min, a single-side solid content coating amount of 4.0 g / m ² , and both sides of 8.0 g / m ² , A base paper was used.

  The coating liquid for providing the coating layer above the polyvinyl alcohol layer provided by the size press coater was prepared as follows. A mass part here is a solid content mass ratio of each material with respect to 100 mass parts of total pigment solid content in a coating liquid. To 50 parts by mass of commercially available wet heavy calcium carbonate and 50 parts by mass of commercially available primary kaolin, 0.10 parts by mass of a commercially available polyacrylic acid-based dispersant was added and dispersed with a disperser at a solid content concentration of 72% by mass. As an adhesive, 10 parts by mass of commercially available styrene-butadiene copolymer latex, 4.0 parts by mass of commercially available phosphate esterified starch, 0.50 parts by mass of commercially available calcium stearate, and pH 9.6 with sodium hydroxide are added. To obtain a coating solution. The obtained coating liquid was adjusted to a solid concentration of 64% by mass with adjusted water.

Using the blade coater, the coating liquid prepared as described above was applied to the base paper produced as described above at an operation speed of 100 m / min, a single-side solid content coating amount of 4.0 g / m ² , both sides. The coating was directly applied onto the polyvinyl alcohol layer directly provided on the base paper under the condition of 8.0 g / m ² and dried. The coated paper thus obtained was subjected to a soft calendering process (using a soft calender consisting of a metal roll heated to 60 ° C. with a hardness of Hs of 84 degrees and a surface roughness of 0.3 S and an elastic roll made of Elaglass with a hardness of 90 ShD. Was applied to the heated metal roll surface at a rate of 80 kN / m once each on the front and back surfaces to produce a coated paper for printing. The evaluation results of the obtained printing coated paper are shown in Table 1.

Example 2
The same procedure as in Example 1 was conducted except that the aqueous polyvinyl alcohol solution used in Example 1 was used for coating after mixing bubbles having an average cell diameter of 15 μm. The evaluation results of the obtained printing coated paper are shown in Table 1.

Example 3
The same procedure as in Example 1 was conducted except that the aqueous polyvinyl alcohol solution used in Example 1 was used for coating after mixing bubbles having an average cell diameter of 500 μm. The evaluation results of the obtained printing coated paper are shown in Table 1.

Example 4
The same procedure as in Example 1 was performed except that the aqueous polyvinyl alcohol solution used in Example 1 was used for coating after mixing bubbles having an average cell diameter of 950 μm. The evaluation results of the obtained printing coated paper are shown in Table 1.

Example 5
In Example 1, the polyvinyl alcohol-containing coating liquid, single-sided coating amount as the solid content 0.8 g / m ^2, except that the coating under the condition of 1.6 g / m ² on both sides, in the same manner as in Example 1 I went. The evaluation results of the obtained printing coated paper are shown in Table 1.

Example 6
In Example 1, a polyvinyl alcohol-containing coating solution was applied in the same manner as in Example 1 except that the coating amount was 7.5 g / m ² on one side solid content and 15.0 g / m ^{2 on} both sides. I went. The evaluation results of the obtained printing coated paper are shown in Table 1.

Comparative Example 1
The same procedure as in Example 1 was conducted except that the aqueous polyvinyl alcohol solution used in Example 1 was used for coating after mixing bubbles having an average cell diameter of 8 μm. The evaluation results of the obtained printing coated paper are shown in Table 1.

Comparative Example 2
The same procedure as in Example 1 was performed except that the aqueous polyvinyl alcohol solution used in Example 1 was used for coating after mixing bubbles having an average cell diameter of 1100 μm. The evaluation results of the obtained printing coated paper are shown in Table 1.

Comparative Example 3
In Example 1, one side solid coating amount 0.4 g / m ^2, except that the coating under the condition of 0.8 g / m ² on both sides was performed in the same manner as in Example 1. The evaluation results of the obtained printing coated paper are shown in Table 1.

Comparative Example 4
In Example 1, single-sided coating amount as the solid content 8.5 g / m ^2, except that the coating under conditions of 17.0 g / m ² on both sides was performed in the same manner as in Example 1. The evaluation results of the obtained printing coated paper are shown in Table 1.

Comparative Example 5
All were carried out in the same manner as in Example 1 except that the aqueous polyvinyl alcohol solution used in Example 1 was coated without mixing bubbles. The evaluation results of the obtained printing coated paper are shown in Table 1.

Comparative Example 6
Except for changing the aqueous polyvinyl alcohol solution used in Example 1 to a commercially available oxidized starch aqueous solution obtained by adding water so as to have a solid concentration of 20% by mass and adjusting the gelatinization, all the same operations as in Example 1 were performed. I went. The evaluation results of the obtained printing coated paper are shown in Table 1.

  Table 1 shows the conditions and evaluation results of Examples 1 to 6 and Comparative Examples 1 to 6.

As is clear from the results in Table 1, a polyvinyl alcohol-containing coating liquid foamed with an average cell diameter of 10 μm or more and 1000 μm or less on one side or both sides of the base paper is coated with 0.5 g of polyvinyl alcohol equivalent on one side. / m ² or more 8.0 g / m ² or less made by coating polyvinyl alcohol coating layer, examples 1 to 6 in which a coating layer mainly composed of pigment and adhesive, gloss, It is possible to obtain a coated paper for rotary offset printing that has excellent base paper coverage and printing surface feel, and is free from generation of wrinkles and blisters during rotary offset printing. On the other hand, Comparative Example 1 having an average bubble diameter of less than 10 μm was effective against elbows but was inferior in blister resistance. On the contrary, in Comparative Example 2 having an average cell diameter larger than 1000 μm, the blister resistance was good, but the wrinkles were inferior. Moreover, even if the average cell diameter was 10 μm or more and 1000 μm or less, Comparative Example 3 in which the coating amount on one side of polyvinyl alcohol was less than 0.5 g / m ² did not work for both wrinkles and blister resistance. . According to the comparison between Example 6 and Comparative Example 4, even if the coating amount on one side of the polyvinyl alcohol conversion exceeds 8.0 g / m ² , no improvement in hiding or blister resistance is observed, and the coating containing polyvinyl alcohol is not performed. The liquid drying load only increased. Furthermore, when polyvinyl alcohol was replaced with oxidized starch, it did not work for both creases and blister resistance.

Claims (2)

Polyvinyl alcohol-containing coating liquid foamed with an average cell diameter of 10 μm or more and 1000 μm or less on one side or both sides of the base paper is coated with a solid content on one side of 0.5 g / m ^{2 to} 8.0 g / m ^2. A coated paper for rotary offset printing, comprising a coating layer mainly composed of a pigment and an adhesive on a polyvinyl alcohol coating layer formed by coating as described below. A coating liquid containing polyvinyl alcohol on one side or both sides of the base paper and foamed to an average cell diameter of 10 μm or more and 1000 μm or less is coated with a solid content of 0.5 g / m ² or more in terms of polyvinyl alcohol. A method for producing a coated paper for offset rotary printing, comprising coating in a range of 0 g / m ² or less and then laminating a coating layer mainly composed of a pigment and an adhesive.