JP2002138389A - Coated paper for printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare a coated paper for printing having excellent flexibility in spite of having bulkiness, hardly causing web break in a printing machine, and excellent in workability. SOLUTION: This coated paper for printing comprising a coated layer containing a pigment and an adhesive on a base paper is characterized in that the product of four of weight, density, Young's modulus in the papermaking direction and length at break in the papermaking direction is >=1.0×1021 g2.N/m6 and <=4.0×1021 g2.N/m6, preferably >=2.0×1021 g2.N/m6 and <=3.5×1021 g2.N/m6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated paper for printing, and more particularly, to a coated paper having high bulk (low density) and excellent flexibility.

[0002]

2. Description of the Related Art In recent years, visualization and colorization of printed matter have been advanced, and demand for higher quality of printing paper has been increased. On the other hand, there is also a high demand for weight reduction of printed materials in order to reduce transportation and mailing costs. Conventionally, these two demands are contradictory, and high-quality print-coated paper has a large basis weight and coating amount of base paper, and has a higher density compared to the same basis weight due to smoothing by surface treatment. Was something. To reduce the weight of the printed matter, it is possible to select a paper having a low basis weight. However, if the density is the same, the paper thickness decreases with the weight reduction, and the volume feeling of the booklet is deteriorated. For this reason, a high-quality coated paper that is bulky, that is, has a higher paper thickness compared with the same basis weight or a lower basis weight as compared with the same paper thickness, and satisfies the requirements of coated paper for high-grade printing applications. It has been demanded.

[0003] In recent years, there has been a tendency to prefer information magazines called mooks and pocket guides, which are small in size and easy to carry. Flexibility is important as a characteristic required for these papers. When rigid paper is used, the smaller the plate type of the booklet, the easier it is to stand when turning the page, and it is very inconvenient to open and read the booklet with one hand, for example, on the go. As an indicator of paper flexibility,
Clark stiffness is used, but the stiffness increases in proportion to the cube of the paper thickness. It has been considered extremely difficult to balance bulkiness.

[0004] As a technique for increasing the bulk, there are techniques for increasing the bulk of a coated paper base paper by using a bulky pulp and a bulky filler, reducing a coating amount of a coating liquid composition, and obtaining a surface of a coated paper obtained. It is possible to alleviate the processing.

[0005] As pulp for papermaking, there are chemical pulp obtained by extracting lignin in fibers with chemicals, groundwood pulp obtained by grinding wood with a grinder without using chemicals, and thermomechanical pulp obtained by disintegrating wood with a refiner. Mechanical pulp. In general, mechanical pulp is more rigid and more effective in reducing the density than chemical pulp. However, these mechanical pulps have a problem in terms of blending with high-quality paper in terms of specifications, and even medium-grade paper is liable to cause printing defects such as paper waste due to binding fibers and the like, and therefore its blending amount is limited. In addition, wastepaper pulp is increasingly used in recent years because of the growing tendency to protect the environment and the need to protect resources. However, wastepaper pulp is generally mixed with high-quality paper, newsprint, magazines, coated paper, etc., and is often pulped. Therefore, compared with virgin (unused paper pulp) mechanical pulp, High density. As described above, it is difficult to achieve sufficient bulking of the paper only on the pulp surface in consideration of protection of wood resources and quality design of the paper. In addition, it is impossible to impart sufficient flexibility to the paper because only the above-mentioned pulp is blended and the rigidity is increased together with the bulkiness.

[0006] Further, use of a bulky filler is considered as bulking of the base paper for coated paper. For example, JP-A-5-339898 discloses a method of lowering the density by blending a hollow synthetic organic substance capsule. However, such a synthetic organic substance lowers paper strength, so that there are problems such as paper scorching and paper breakage at the time of printing, and it is necessary to use a high blending ratio in order to obtain a sufficient bulking effect, thereby increasing the manufacturing cost. There were also problems such as. JP-A-52-74001 proposes a method using a shirasu balloon. However, this has a problem that the mixing property with paper pulp is poor, and that the paper containing the pulp also causes uneven printing. Further, it has not been possible to impart flexibility to paper even by using the above method.

[0007] The coated layer of the coated paper is generally higher in density than the base paper. Therefore, the density of the coated paper is higher than that of the printing paper having no coating layer. The bulking of the coated paper can also be achieved by reducing the coating amount of the coating composition. This is because the ratio of the coating layer to the entire coated paper becomes small. However, reducing the number of coating layers also reduces the coverage of the base paper with the coating layers,
In order to reduce print quality such as blank gloss, smoothness, and print gloss, there is a limit to reducing the coating amount while maintaining target quality.

[0008] In order to improve the print quality of coated paper, in particular, the ink deposit density and the glossiness of the image area (hereinafter referred to as print glossiness), it is effective to increase the smoothness of the coated paper. It is one of the means. For this reason, it is common to apply a surface smoothing treatment such as a super calender or soft nip calender on coated papers with a blank white glossiness between glossy coated paper and glossy paper called glossy paper or dull tone. It is. But,
Since these treatments increase the smoothness of the surface by pressing the paper, the thickness of the paper is reduced at the same time, and it may not be possible to achieve sufficient bulkiness to obtain the target print quality.

As described above, it has not been possible to obtain a coated paper for printing which is bulky (low density) and excellent in flexibility by using the conventional techniques alone or in combination alone.

[0010]

SUMMARY OF THE INVENTION In view of such circumstances, an object of the present invention is to improve the flexibility while being bulky.
Another object of the present invention is to provide a coated paper for printing which is less likely to cause paper breakage in a printing machine and has good workability.

[0011]

The inventors of the present invention have conducted intensive studies in the above difficult situation, and as a result, have found that a coated paper for printing having a coated layer containing a pigment and an adhesive on a base paper. , The product of the basis weight, density, Young's modulus in the papermaking direction, and tear length in the papermaking direction of the paper is 1.0 × 10 ²¹ g ² ·
N / m ⁶ or more and 4.0 × 10 ²¹ g ² · N / m ⁶ or less, more preferably 2.0 × 10 ²¹ g ² · N / m ⁶ or more and 3.5 × 10
^By specifying so as to be ²¹ g ² · N / m ⁶ , a coated paper that is bulky and excellent in flexibility, hardly causes paper breakage in a printing machine, and has good workability can be obtained. It was found that it could be obtained. In the present invention, especially when the coating amount of the coating layer is at least 9 to 25 g / m ² per one side, a coated paper having high bulk, flexibility and good print quality can be obtained. Is something that can be done.

The present inventors have focused on the ease of turning a booklet when examining the flexibility of paper. Generally, the stiffness of paper is quantitatively evaluated in terms of clarity, pure bending stiffness, and the like. As a result of investigating the correlation between the ease of page turning by the subject and the pure bending stiffness in the papermaking direction and width direction for various booklets, paper with low stiffness tended to be flexible, but even if stiffness was equal Some papers had different sensory evaluations of the ease of turning pages. That is, it was found that the flexibility of the paper cannot be evaluated only by the bending stiffness.

When a page is turned, a bending stress is applied to the sheet, and a tensile stress is applied to the convex surface and a compressive stress is applied to the concave surface. Therefore, the correlation between the Young's modulus in the width direction and the papermaking direction and the ease of turning was determined. As a result, it was confirmed that even when the pure bending stiffness in the width direction was equal, the pages were more likely to turn as the Young's modulus in the width direction and the papermaking direction were lower. In many papers tested, the Young's modulus in the width direction and papermaking direction had a positive correlation,
In particular, when the Young's modulus in the papermaking direction is low, in addition to the fact that the pages are easily turned and flexible, when printing with an offset rotary printing machine, there is little fluctuation in the tension in the paper feeding unit and the cooling roll unit, etc. The running stability of the paper web increases,
It has been found that breakage hardly occurs.

The present inventors have also investigated the relationship between paper strength and flexibility. As a result, it was found that, when comparing papers having the same paper thickness, paper having a shorter tearing length tends to have higher flexibility. For example, in the case of paper having a long tearing length, the amount of hydrogen bonds formed between the pulp fibers in the paper is large, and the paper strength tends to be relatively strong. It is considered that the bending stress or the tensile stress required to obtain the bending strain or the tensile strain becomes relatively large, which makes it difficult to turn the page.

From the above, the Young's modulus and tear length of paper
Of paper at the same time
Increased flexibility, which is bulky, ie
That the method is applicable to thicker paper
I found it. After further diligent studies, the target flexibility
The range of Young's modulus and breaking length at which
The higher the basis weight of the paper, the higher the Young's modulus or
Does not provide good flexibility without reducing the breaking length
won. In other words, paper flexibility depends on basis weight, density, papermaking method.
Of the product of the Young's modulus in the papermaking direction and the tear length in the papermaking direction
And good correlation was found. The product of the four is 1.0
× 10^{twenty one}g^Two・ N / m⁶4.0 × 10 or more ^{twenty one}g^Two・ N / m⁶
Or less, preferably 2.0 × 10^{twenty one}g^Two・ N / m⁶3 above.
5 × 10 ^{twenty one}g^Two・ N / m⁶Produce printed materials in the following ranges:
The page is easy to turn when you make a booklet,
It is bulky and voluminous.
It is a coated paper for printing that has little work paper and good workability.
I found that. Conventional technology alone or in combination
The flexibility that could not be obtained by increasing the bulk of paper
Achieved by lowering the cutting rate and breaking length in a well-balanced manner,
In addition, paper having good workability in a printing press was obtained.

Compared with the same basis weight, paper having a normal density and a product of four products less than 1.0 × 10 ²¹ g ² · N / m ⁶ has an excessively low Young's modulus. Or, because the tear length is too short, the paper is too flexible, so it is difficult to turn the page because it is too flexible, or the paper strain increases due to the tension in the printing press, and the paper that has exceeded the elastic limit is broken. The paper is easily cut. Further, when compared with the same basis weight, the paper having a normal value of Young's modulus and a breaking length and a value of a product of four members of less than 1.0 × 10 ²¹ g ² · N / m ⁶ is:
It is a paper having an excessively low density, and it is necessary to extremely reduce the pressure of the press and calendering in the paper making process, and therefore, the smoothness is extremely low and it is difficult to print.

On the other hand, when compared with the same basis weight, paper having a normal density and a product value of the product of the four exceeding 4.0 × 10 ²¹ g ² · N / m ⁶ is excessively torn. Long length or high Young's modulus means that the paper is rigid and flexible paper cannot be obtained.In addition, if the Young's modulus is high, it becomes rigid and, in addition, it cannot absorb tension fluctuations during printing and partially Troubles such as paper breakage are likely to occur because high stress is applied.
Compared with the same basis weight, paper having a normal value of Young's modulus and a breaking length of more than 4.0 × 10 ²¹ g ² · N / m ⁶ with a product of four has extremely high density. This is high and does not result in a bulky and voluminous printing coated paper which is the object of the present invention.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The product of the basis weight, density, Young's modulus in the papermaking direction, and tear length in the papermaking direction of a paper is 1.0 ×
In order to fall within the range of 10 ²¹ g ² · N / m ⁶ or more and 4 × 10 ²¹ g ² · N / m ⁶ or less, the paper density, the Young's modulus in the paper making direction, and the tear length in the paper making direction are each reduced. It is preferable to combine the means for performing the above. As a method of reducing the density of the paper, a method of improving the compounding ratio of the low-density pulp and the low-density filler, or the use of bulky chemicals, or the reduction of the press pressure in the papermaking process and the processing linear pressure of the machine calender, etc. No. As a method for lowering the Young's modulus of the paper, use of a softening agent and the like can be mentioned. Examples of a method for reducing the breaking length of the paper in the papermaking direction include a method of increasing the compounding ratio of the filler.

The softening agent used in the present invention has an action of inhibiting the bond between pulp fibers or softens the fibers themselves. For example, a compound having a hydrophobic group and a hydrophilic group, such as an oil-based nonionic surfactant, a sugar alcohol-based nonionic surfactant, a sugar-based nonionic surfactant, a polyhydric alcohol-type nonionic surfactant, Alcohol, ester compound of polyhydric alcohol and fatty acid, polyoxyalkylene adduct of higher alcohol or higher fatty acid, polyoxyalkylene adduct of higher fatty acid ester, polyoxyalkylene adduct of polyhydric alcohol and fatty acid ester compound, fatty acid polyamide Amines and the like can be used. It is preferable to be able to decrease the pure bending stiffness and the density in addition to decreasing the Young's modulus, and it is preferable to use an ester compound of a polyhydric alcohol and a fatty acid.

In the present invention, the type of pulp blended in the base paper is, for example, hardwood bleached kraft pulp (hereinafter referred to as LB).
KP), softwood bleached kraft pulp (NBKP),
Thermomechanical pulp, groundwood pulp, waste paper pulp and the like are used. In order to improve roughening on a printing press, it is preferable to use LBKP or NBKP chemical pulp. In addition, when a filler is contained in the paper, the Young's modulus tends to decrease. Therefore, it is preferable to include the filler. Examples of the filler include heavy calcium carbonate, light calcium carbonate, kaolin, clay, talc, and hydrate. Known fillers such as silicic acid, white carbon, titanium oxide, and synthetic resin fillers can be used. The amount of filler used is preferably 6% by weight per pulp weight, more preferably 10% by weight.
% By weight or more. If necessary, sulfate band,
It may contain a sizing agent, a paper strength enhancer, a softening agent, a retention improver, a colorant, a dye, an antifoaming agent and the like.

Further, a surface treatment agent containing a water-soluble polymer as a main component may be applied to the base paper for the purpose of improving the surface strength and size as long as the density, the Young's modulus and the breaking length are not affected. . As the water-soluble polymer, oxidized starch, hydroxyethyl etherified starch, enzyme-modified starch, polyacrylamide, polyvinyl alcohol, and the like, which are commonly used as surface treatment agents, can be used alone, or a mixture thereof can be used. . In addition to the water-soluble polymer, a paper strength enhancer for improving water resistance and surface strength and an external sizing agent for imparting size can be added to the surface treating agent. The surface treatment agent can be applied by a coating machine such as a two-roll size press coater, a gate roll coater, and a blade metalling size press coater, and a rod transfer type roll coater such as a shim sizer. it can. Further, the pH of the base paper for coated paper for printing used in the present invention may be any of acidic, neutral and alkaline.

In the present invention, a coating layer having a pigment and an adhesive is provided on the base paper within a range that does not affect the density, the Young's modulus, and the breaking length.

Kaolin, clay, delaminated clay, heavy calcium carbonate, light calcium carbonate, talc, titanium dioxide, barium sulfate, calcium sulfate conventionally used for coated paper as a pigment used in the coating layer , Zinc oxide, silicic acid, silicates, colloidal silica, inorganic pigments such as satin white, and organic pigments such as plastic pigments. These pigments can be used by appropriately selecting one or more as necessary. I can do it.

The adhesive used in the present invention is a styrene-butadiene-based, styrene-acrylic, ethylene-vinyl acetate-based adhesive conventionally used for coated paper.
Various copolymers such as butadiene / methyl methacrylate and vinyl acetate / butyl acrylate, and synthetic adhesives such as polyvinyl alcohol, maleic anhydride copolymer, and acrylic acid / methyl methacrylate copolymer; casein, soy protein, synthetic Proteins such as proteins; etherified starches such as oxidized starch, positive starch, urea phosphate esterified starch and hydroxyethyl etherified starch, starches such as dextrin; cellulose derivatives such as carboxymethyl cellulose, hydroxyethyl cellulose and hydroxymethyl cellulose. One or more types of adhesives for coated paper are appropriately selected and used. These adhesives are used in an amount of 5 to 50 parts by weight, more preferably about 5 to 25 parts by weight, per 100 parts by weight of the pigment. If necessary, various auxiliaries to be added to ordinary pigments for coated paper, such as a dispersant, a thickener, a water retention agent, a defoaming agent, a waterproofing agent, and a coloring agent, are appropriately used.

The coating layer provided on the base paper may be provided as a single layer or two or more layers on one or both sides of the base paper as long as the coating does not affect the density, Young's modulus and breaking length. The coating amount of the coating layer is more preferably 10 per side.
２０20 g / m ² .

As a method for applying the coating composition to the base paper, there are two roll size press coaters, gate roll coaters, blade metalling size press coaters, rod metalling size press coaters, films such as shim sizers and the like. Transfer type roll coater, flooded nip / blade coater, jet fountain / blade coater, short dwell time application coater, rod metering coater using grooved rod, plain rod, etc. instead of blade, curtain It can be coated with a known coater such as a coater and a die coater.

Further, in order to improve the smoothness of the paper and the print quality, the coated paper obtained by the above-mentioned method can be subjected to a surface treatment within a range not affecting the density. As a surface treatment method, a known surface treatment device such as a super calender using a cotton roll as an elastic roll or a soft nip calender using a synthetic resin roll as an elastic roll can be used. The soft nip calender can be set at a high temperature because the heat resistance temperature of the surface of the synthetic resin roll can be set higher than that of the cotton roll.
When the same smoothness is targeted, the processing linear pressure can be set lower than that of the super calender, and thus a coated paper with lower density and higher smoothness can be obtained, which is preferable.
The printing coated paper of the present invention preferably has a density of 1.00 g.
/ Cm ³ or less, more preferably 0.90 g / cm ³ or less.

[0028]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. Unless otherwise specified, parts and% in the examples indicate parts by weight and% by weight, respectively.
The obtained coated printing paper was tested based on the following evaluation method. <Evaluation method> (Basic weight) According to JIS P 8124: 1998. (Density) According to JIS P 8118: 1998. (Young's modulus) According to JIS P 8113: 1998, the tensile modulus was measured, and this value was defined as the Young's modulus. (Tear length) According to JIS P 8113: 1998 (Flexibility: Easiness of page turning) 100 blank sheets of A5
Cut to the size of the plate, create a booklet model by sandwiching it with clips, and turn the page when turning it with 10 monitors, ◎ very excellent, ○ excellent, △ slightly problematic, × problematic The evaluation was made in four steps. (Workability in printing machine) The sample winding was performed by an offset rotary printing machine at a printing speed of 250 m / min.
A length of 000 m was printed, and the tension fluctuation between the in-feed portion and the cooling roll portion during printing was evaluated in three stages: ○ small, Δ slightly large, × large, or breakage. [Example 1] 100 chemical pulp as pulp for papermaking
Parts, 12 parts of light calcium carbonate as a filler, and an ester compound of a polyhydric alcohol and a fatty acid (KB) as a softening agent.
-110, manufactured by Kao Corporation).
80 parts of heavy calcium carbonate as a pigment and 10 parts of secondary kaolin and 10 parts of fine kaolin were added to 4 g / m ² base paper.
Parts, 0.05 part of sodium polyacrylate as a dispersant,
11 parts of carboxy-modified styrene-butadiene latex and 4 parts of phosphorylated esterified starch were added as binders,
The coating liquid adjusted to a concentration of 65% by weight by further adding water,
Coating is performed on both sides with a blade coater at a coating speed of 800 m / min so that the coating amount is 14 g / m ² per side,
A coated paper for printing was obtained. [Example 2] A coated paper for printing was obtained in the same manner as in Example 1, except that 80 parts of heavy calcium carbonate and 20 parts of fine kaolin were used as pigments contained in the coating liquid. [Example 3] 100 chemical pulp was used as a paper pulp.
Parts, 12 parts of light calcium carbonate as a filler, and an ester compound of a polyhydric alcohol and a fatty acid (KB) as a softening agent.
-110, manufactured by Kao Corporation).
6 g / m ² base paper, 65 parts of heavy calcium carbonate as a pigment, 7 parts of secondary kaolin, 28 parts of fine kaolin,
Coating solution prepared by adding 0.05 parts of sodium polyacrylate as a dispersant, 9 parts of carboxy-modified styrene butadiene latex as a binder, and 2.5 parts of phosphorylated esterified starch, and further adding water to adjust the concentration to 64%. Is adjusted so that the coating amount is 13 g / m ² per side.
Coating was performed on both sides with a blade coater at 0 m / min to obtain a coated paper for printing. [Practical example 4] 100 chemical pulp as pulp for papermaking
Parts, 12 parts of light calcium carbonate as a filler, and an ester compound of a polyhydric alcohol and a fatty acid (KB) as a softening agent.
-115, manufactured by Kao Corporation).
80 parts of heavy calcium carbonate as a pigment and 10 parts of secondary kaolin and 10 parts of fine kaolin were added to 4 g / m ² base paper.
Parts, 0.05 part of sodium polyacrylate as a dispersant,
11 parts of carboxy-modified styrene-butadiene latex and 4 parts of phosphorylated esterified starch were added as binders,
Further, the coating liquid adjusted to a concentration of 65% by adding water was coated at a coating speed of 8 such that the coating amount was 14 g / m ² per one side.
Coating was performed on both sides with a blade coater of 00 m / min to obtain a coated paper for printing. Example 5 100 Chemical Pulp as Paper Pulp
Parts, 12 parts of light calcium carbonate as a filler, and an ester compound of a polyhydric alcohol and a fatty acid (KB) as a softening agent.
-110, manufactured by Kao Corporation).
80 g of heavy calcium carbonate as a pigment, 20 parts of fine kaolin, 0.05 parts of sodium polyacrylate as a dispersant, 11 parts of carboxy-modified styrene-butadiene latex as a binder, 11 parts of phosphoric acid ester on a 4 g / m ² base paper 4 parts of the modified starch was added, and water was further added to adjust the concentration to 65%. The coating amount was 12 g / m2 per side.
^The coating was performed on both sides with a blade coater at a coating speed of 800 m / min to obtain a coated paper for printing. [Comparative Example 1] 100 chemical pulp as a papermaking pulp
Parts, base paper having a basis weight of 76 g / m ² containing 12 parts of light calcium carbonate as a filler, 80 parts of heavy calcium carbonate as a pigment, 10 parts of secondary kaolin, and 1 part of fine kaolin as a pigment.
0 parts, 0.05% sodium polyacrylate as a dispersant
Parts, 11 parts of a carboxy-modified styrene-butadiene latex as a binder, 4 parts of a phosphorylated esterified starch, and water were added to adjust the concentration to 65% by weight. The coating amount was 14 g / m ² per side. The coating was performed on both sides with a blade coater at a coating speed of 800 m / min to obtain a coated paper for printing. Comparative Example 2 Base paper having a basis weight of 103 g / m ² containing 100 parts of chemical pulp as a pulp for papermaking and 12 parts of light calcium carbonate as a filler, 65 parts of heavy calcium carbonate as a pigment, and secondary kaolin as a filler. 7 parts, 2 fine kaolin
8 parts, 0.05 of sodium polyacrylate as a dispersant
Parts, 9 parts of a carboxy-modified styrene-butadiene latex as a binder, 2.5 parts of a phosphorylated esterified starch, and water were added to adjust the coating weight to 64% by weight. The coating amount was 13 g / m2 per side. ^The coating was performed on both sides with a blade coater at a coating speed of 500 m / min to obtain a coated paper for printing. Comparative Example 3 Base paper having a basis weight of 55 g / m ² containing 100 parts of chemical pulp as paper pulp and 12% of light calcium carbonate as a filler, 95 parts of heavy calcium carbonate as a pigment, and secondary kaolin 5 parts by weight, 0.05 parts of sodium polyacrylate as a dispersant, and 4 parts of carboxy-modified styrene-butadiene latex as a binder.
Parts, 20 parts of a phosphorylated esterified starch, and further, water was added to adjust the coating solution to a concentration of 40%. A coating speed of 1000 m / mi was applied so that the coating amount was 3 g / m ² per side.
n on both sides using a film transfer roll coater, and heavy calcium carbonate as a pigment
Parts, 20 parts of fine kaolin, 0.05 parts of sodium polyacrylate as a dispersing agent, 11 parts of carboxy-modified styrene-butadiene latex as a binder, 4 parts of phosphorylated starch, and further 64% concentration by adding water. The coating liquid was adjusted on both sides with a blade coater at a coating speed of 900 m / min so that the coating amount was 11 g / m ^{2 on} one side to obtain a coated paper for printing. Comparative Example 4 Except that the basis weight of the base paper was 82 g / m ² ,
A coated paper for printing was obtained in the same manner as in Comparative Example 3. Comparative Example 5 A coated paper for printing was obtained in the same manner as in Example 1 except that the basis weight of the base paper was 40 g / m ² and the coating amount was 12 g / m ² per one side.

The basis weight, density, Young's modulus in the papermaking direction, and tear length in the papermaking direction of the coated printing paper manufactured under the above conditions were measured, and the product of the four was calculated. Further, evaluation of ease of page turning and evaluation of workability in a printing press when binding the same paper into a booklet were performed. The results are shown in Table 1.

[0030]

[Table 1] As is apparent from Table 1, the product of the basis weight, density, Young's modulus in the papermaking direction, and the breaking length in the papermaking direction is 1.0.
× 10 ²¹ g ² · N / m ⁶ or more 4.0 × 10 ²¹ g ² · N / m ⁶
If it is in the following range, regardless of the composition of the base paper and the pigment coating layer, it is excellent in flexibility and easy to turn pages, is bulky, and has excellent workability with a printing machine It is clear that

[0031]

According to the present invention, it is possible to obtain a coated paper for printing which is bulky (low density), excellent in flexibility, hardly causes paper breakage in a printing machine, and has good workability.

Continued on the front page (72) Inventor Takehide Kasahara 5-2-1-1, Oji, Kita-ku, Tokyo Nippon Paper Industries Within the Technical Research Institute (72) Inventor Takashi Ochi 5-2-1-1, Oji, Kita-ku, Tokyo Nippon Paper Co., Ltd. (72) Inventor Hirokazu Morii 5-21-1, Oji, Kita-ku, Tokyo Nippon Paper Industries Co., Ltd. F-term (reference) 4L055 AC05 AG11 AG12 AG27 AG34 AG48 AG63 AG76 AG89 AH01 AH02 AH37 AH50 AJ04 BE08 EA06 EA14 FA16 GA19

Claims (3)

[Claims] 1. A printing coated paper having a coating layer containing a pigment and an adhesive on a base paper, the product of four of a basis weight, a density, a Young's modulus in a paper making direction and a tear length in a paper making direction. Is 1.
0 × 10 ²¹ g ² · N / m ⁶ or more 4.0 × 10 ²¹ g ² · N /
coated paper for printing, wherein m ⁶ or less. 2. The product of the basis weight, density, Young's modulus in the papermaking direction, and tear length in the papermaking direction is 2.0 × 10 ²¹ g ² · N.
^{2. The} coated paper for printing according to claim 1, wherein the coating paper has a density of not less than / m ^{6 and not} more than 3.5 × 10 ²¹ g ² · N / m ⁶ . 3. The coated paper for printing according to claim 1, wherein the coating amount of the coating layer is at least 9 to 25 g / m ² per one side.