JP2004131922A - Coated paper for printing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coated paper for printing, simultaneously having bulkiness and excellent flexibility, hardly causing paper break in a printer. <P>SOLUTION: The coated paper for printing has, on base paper, a coat containing a pigment and an adhesive and has the product of four items i.e. basis weight, density, longitudinal Young's modulus and longitudinal break length and of ≥1.0×10<SP>21</SP>g<SP>2</SP>N/m<SP>6</SP>but ≤4.0×10<SP>21</SP>g<SP>2</SP>N/m<SP>6</SP>, wherein the coat contains 5-50 pts. wt. adhesive per 100 pts. wt. pigment. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a coated paper for printing, and more particularly to a coated paper for printing which is bulky (low density) and excellent in flexibility.

In recent years, visualization and colorization of printed materials have been progressing, and demands for high quality printing paper have been increasing. 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 thickness of the paper decreases as the weight is reduced, and the volume of the booklet is spoiled, which is not preferred. 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.

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 for the page to be turned when turning the page. For example, it is very inconvenient to open and read the booklet with one hand when going out. As an index of paper flexibility, Clark stiffness and the like are used.Since stiffness increases in proportion to the cube of the paper thickness, when the paper thickness increases at the same basis weight due to bulkiness, the stiffness increases accordingly. Therefore, it has been considered that it is extremely difficult to achieve both flexibility and bulkiness of paper.

Techniques for bulking include bulking of base paper for coated paper by using bulky pulp and bulky filler, reduction of coating liquid composition coating amount, and relaxation of surface treatment of coated paper obtained. And so on.

As pulp for papermaking, there are chemical pulp obtained by extracting lignin in fibers with chemicals, mechanical pulp such as groundwood pulp obtained by grinding wood with a grinder without using chemicals and thermomechanical pulp obtained by disintegrating wood with a refiner It is roughly divided into. Generally, mechanical pulp has more rigid fibers and is more effective in reducing the density than chemical pulp. However, the blending of these mechanical pulp with high quality paper is problematic in terms of specifications, and even with medium quality paper, printing defects such as paper waste due to binding fibers are liable to occur. In addition, wastepaper pulp has been increasingly used in recent years due to 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. Further, since only the above-mentioned pulp is blended, bulkiness and rigidity are increased, so that it was impossible to impart sufficient flexibility to paper.

Furthermore, use of a bulky filler is considered as bulking of the base paper for coated paper. For example, Patent Literature 1 discloses a method of lowering the density by blending a hollow synthetic organic substance capsule. However, such synthetic organic substances lower the paper strength, so that there are problems such as paper scumming and paper breakage during printing, and it is necessary to use a high content to obtain a sufficient bulking effect, so that the production cost increases. There were also problems such as. Patent Document 2 proposes a method using a shirasu balloon. However, this has a problem that the mixing property with the papermaking pulp is poor and that the paper containing the pulp also causes uneven printing. Further, it has not been possible to impart flexibility to the paper even by using the above method.

塗 The coating layer of the coated paper is generally higher in density than the base paper. For this reason, the density of the coated paper is higher than that of the printing paper having no coating layer. The bulkiness 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 at the same time reduces the coverage of the base paper with the coating layers, and lowers the printing quality such as glossiness, smoothness, and printing glossiness of the white paper. However, there is a limit to reducing the coating amount.

In order to improve the printing quality of coated paper, particularly the ink deposition density and the glossiness of the image area (hereinafter referred to as printing glossiness), it is an effective means to increase the smoothness of the coated paper. One. For this reason, it is common to apply a surface smoothing treatment such as a super calender or soft nip calender to coated papers having a blank white glossiness between glossy coated paper and glossy paper called glossy paper or dull tone. It is. However, these treatments increase the smoothness of the surface by pressing the paper, and at the same time, the thickness of the paper is reduced, so that sufficient bulking may not be achieved to obtain the target print quality. Was.

(4) As described above, it was impossible 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.

JP-A-5-339898 JP-A-52-74001

In view of such circumstances, it is an object of the present invention to provide a coated paper for printing which is bulky, has excellent flexibility, hardly causes paper breakage in a printing machine, and has good workability. is there.

The present inventors have conducted intensive studies in such difficult situations as described above, and as a result, on a base paper, a printing coated paper having a coating layer containing a pigment and an adhesive, the basis weight, density, The product of the Young's modulus in the papermaking direction and the breaking length in the papermaking direction being not less than 1.0 × 10 ²¹ g ² · N / m ^{6 and not} more than 4.0 × 10 ²¹ g ² · N / m ⁶ ; By containing 5 to 50 parts by weight of the adhesive with respect to 100 parts by weight, it is bulky, excellent in flexibility, hardly causes paper breakage in a printing machine, and has good workability. We found that paper was obtained. It is preferable that the product of the four is specified to be 2.0 × 10 ²¹ g ² · N / m ⁶ or more and 3.5 × 10 ²¹ g ² · N / m ⁶ or less. 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. It is something that can be done.

The present inventors paid attention to the ease of turning a booklet in examining the flexibility of paper. Generally, the stiffness of paper is quantitatively evaluated by Clark stiffness, 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 differed in sensory evaluation 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, bending stress is applied to the paper, and tensile stress is applied to the convex surface and 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 the papermaking direction had a positive correlation, but especially when the Young's modulus in the papermaking direction was low, in addition to being easy to turn pages and being flexible, in addition to the offset rotary printing press It was found that, when printing with, the fluctuation of the tension in the paper feeding section, the cooling roll section, and the like was small, so that the running stability of the web was increased, and the breakage of paper was less likely to occur.

The present inventors also investigated the relationship between paper strength and flexibility. As a result, it was found that, when compared with paper 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 pulp fibers in the paper is large, and the paper strength tends to be relatively strong, but the degree of freedom of the fibers decreases, but the same It is considered that the bending stress or the tensile stress required to obtain the bending strain or the tensile strain becomes relatively large, thereby making it difficult to turn the page.

From the above, by simultaneously reducing the Young's modulus and the breaking length of the paper in a well-balanced manner, the flexibility of the paper is improved, which is a bulky paper, that is, a paper having a higher paper thickness compared with the same basis weight. It was found that the method could be applied to As a result of further intensive studies, the range of Young's modulus and tear length at which the desired flexibility is obtained depends on the density and basis weight, and the higher the basis weight of the paper, the lower the Young's modulus or tear length must be reduced. , Good flexibility could not be obtained. That is, it was found that the flexibility of the paper showed a good correlation with the product of the basis weight, density, Young's modulus in the papermaking direction, and the breaking length in the papermaking direction. The product of the four is 1.0 × 10 ²¹ g ² · N / m ⁶ or more and 4.0 × 10 ²¹ g ² · N / m ⁶ or less, preferably 2.0 × 10 ²¹ g ² · N / m ⁶ or more When the range is 3.5 × 10 ²¹ g ² · N / m ⁶ or less, the pages are easy to turn when a printed matter is bound and made into a booklet. It has been found that it is a coated paper for printing which has little occurrence of paper breakage at the time and has good workability. Flexibility that could not be obtained by increasing the bulk of paper by the conventional technology alone or in combination is achieved by reducing the Young's modulus and the breaking length in a well-balanced manner, and also obtains paper with good workability in a printing press. Was done.

Compared with the same basis weight, paper having a normal density and a product value of a product of four members of less than 1.0 × 10 ²¹ g ² · N / m ⁶ has an excessively low Young's modulus or tear. The length is low and the paper is too flexible to make it difficult to turn over the page, or the paper strain increases due to the tension in the printing press, and the paper that has stretched beyond the elastic limit is broken. Therefore, the sheet is likely to break. Further, when compared with the same basis weight, paper having a normal value of Young's modulus and a breaking length and a product of four products of less than 1.0 × 10 ²¹ g ² · N / m ⁶ has excessive density. Of such paper, it is necessary to extremely reduce the pressure of 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, 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 has an excessively high breaking length. Or, the Young's modulus is high, the paper becomes rigid and flexible paper cannot be obtained.If the Young's modulus is high, the paper becomes rigid. Troubles, such as paper breakage, are likely to occur because of the hanging. 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 members has an extremely high density. This is high, and does not provide a bulky and voluminous printing coated paper which is the object of the present invention.

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.

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 × 10 ²¹ g ² · N / m. ^In order to achieve the range of ⁶ or less, it is preferable to combine means for reducing the density of the paper, the Young's modulus in the papermaking direction, and the tear length in the papermaking direction. As a method of reducing the density of the paper, a method of improving the blending ratio of the low-density pulp and the low-density filler, or the use of a bulky chemical, or a reduction in the press pressure in the papermaking process or a reduction in the processing linear pressure of the machine calender, etc. No. As a method for lowering the Young's modulus of paper, use of a softening agent and the like can be mentioned. As a method for reducing the tearing length of the paper in the papermaking direction, there is a method of increasing the compounding ratio of the filler.

に お い て In the present invention, it is preferable to use a softening agent. The softening agent used has an effect of inhibiting the binding 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, and a higher alcohol. An ester compound of a polyhydric alcohol and a fatty acid, a polyoxyalkylene compound of a higher alcohol or a fatty acid, a polyoxyalkylene adduct of an ester compound of a polyhydric alcohol and a fatty acid, a fatty acid polyamidoamine, and the like can be used. It is preferable to be able to lower the pure bending stiffness and the density in addition to lowering the Young's modulus, and it is preferable to use an ester compound of a polyhydric alcohol and a fatty acid.

種類 As the type of pulp blended in the base paper in the present invention, for example, hardwood bleached kraft pulp (hereinafter, LBKP), softwood bleached kraft pulp (hereinafter, 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 filler is contained in paper, the Young's modulus tends to decrease. Therefore, it is preferable to include filler, and as the filler, heavy calcium carbonate, light calcium carbonate, kaolin, clay, talc, hydrated Known fillers such as silicic acid, white carbon, titanium oxide, and synthetic resin fillers can be used. The filler is preferably used in an amount of 6% by weight, more preferably 10% by weight or more, based on the weight of the pulp. If necessary, a sulfuric acid band, a sizing agent, a paper strength enhancer, a softening agent, a retention improver, a colorant, a dye, an antifoaming agent, and the like may be contained.

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, Young's modulus and 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-strengthening agent 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 treating 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.

(4) 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, zinc oxide conventionally used for coated paper as a pigment used in the coating layer And inorganic pigments such as silicic acid, silicates, colloidal silica, and satin white; and organic pigments such as plastic pigments. One or more of these pigments can be appropriately selected and used as necessary.

The adhesive used in the present invention is a styrene / butadiene type, a styrene / acrylic type, an ethylene / vinyl acetate type, a butadiene / methyl methacrylate type, a vinyl acetate / butyl acrylate type, etc. which are conventionally used for coated paper. Various types of copolymers and synthetic adhesives such as polyvinyl alcohol, maleic anhydride copolymers, acrylic acid / methyl methacrylate copolymers; proteins such as casein, soybean protein, and synthetic proteins; oxidized starch, positive starch, and urea One or more types of ordinary adhesives for coated paper such as phosphated starch, etherified starch such as hydroxyethyl etherified starch, starches such as dextrin, and cellulose derivatives such as carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxymethyl cellulose are appropriately selected. Used as It is necessary to use these adhesives in an amount of 5 to 50 parts by weight, preferably 5 to 25 parts by weight, based on 100 parts by weight of the pigment. If necessary, various auxiliaries to be added to ordinary coated paper pigments, such as a dispersant, a thickener, a water retention agent, a defoaming agent, a waterproofing agent, and a colorant, 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, the Young's modulus, and the breaking length. The coating amount of the coating layer is more preferably 10 to ²⁰ g / m ² per side.

As a method for coating the coating composition on the base paper, 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 rod metaling size press coater, a simsizer, etc. In addition to coaters, flooded nip / blade coaters, jet fountain / blade coaters, short dwell time applicator coaters, rod metering coaters using grooved rods, plain rods, etc. instead of blades, curtain coaters, die coaters It can be coated with a known coater such as a tar coater.

Further, in order to improve the smoothness of the paper and the print quality, the coated paper obtained by the above method can be subjected to a surface treatment within a range that does not affect the density. As the 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 in some cases, so that a coated paper having lower density and higher smoothness can be obtained, which is preferable. The coated paper for printing 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.

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: ease of page turning) When 100 sheets of blank paper are cut to A5 size, a booklet model is created by clipping, and the page is turned. Ease of turning was evaluated by a monitor of 10 persons on a four-point scale of ◎ very excellent, ○ excellent, △ slightly problematic, and × bad.
(Workability in the printing press) The sample winding is printed on the offset rotary printing press at a printing speed of 250 m / min for a length of 6,000 m, and the tension fluctuation of the in-feed portion and the cooling roll portion during printing. Was evaluated in three stages: ○ small, Δ slightly large, × large, or paper breakage.
[Example 1]
Basis weight containing 100 parts of chemical pulp as paper pulp, 12 parts of light calcium carbonate as filler, and 0.3 part of ester compound of polyhydric alcohol and fatty acid (KB-110, manufactured by Kao Corporation) as softener 80 g of heavy calcium carbonate as a pigment, 10 parts of secondary kaolin, 10 parts of fine kaolin, 0.05 parts of sodium polyacrylate as a dispersing agent, and carboxy-modified styrene butadiene as a binder were added to a base paper of 64 g / m ^2. 11 parts of latex and 4 parts of phosphorylated esterified starch were added, and water was further added to adjust the solid content concentration to 65%. The coating solution was coated so that the coating amount was 14 g / m ² per side. Coating was performed on both sides with a blade coater at a speed of 800 m / min to obtain a coated paper for printing.
[Example 2]
A coated paper for printing was obtained in the same manner as in Example 1, except that the pigment contained in the coating liquid was changed to 80 parts of heavy calcium carbonate and 20 parts of fine kaolin.
[Example 3]
Basis weight containing 100 parts of chemical pulp as paper pulp, 12 parts of light calcium carbonate as filler, and 0.5 parts of ester compound of polyhydric alcohol and fatty acid (KB-110, manufactured by Kao Corporation) as softener. ^On a base paper of 76 g / m ² , 65 parts of heavy calcium carbonate as a pigment, 7 parts of secondary kaolin, 28 parts of fine kaolin, 0.05 parts of sodium polyacrylate as a dispersant, and carboxy-modified styrene butadiene as a binder 9 parts of latex and 2.5 parts of phosphorylated ester were added, and water was further added to adjust the solid concentration to 64%. The coating liquid was adjusted so that the coating amount was 13 g / m ² per side. 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.
[Example 4]
Basis weight containing 100 parts of chemical pulp as paper pulp, 12 parts of light calcium carbonate as filler, and 0.3 part of ester compound of polyhydric alcohol and fatty acid (KB-115, manufactured by Kao Corporation) as softener 80 g of heavy calcium carbonate as a pigment, 10 parts of secondary kaolin, 10 parts of fine kaolin, 0.05 parts of sodium polyacrylate as a dispersing agent, and carboxy-modified styrene butadiene as a binder were added to a base paper of 64 g / m ^2. 11 parts of latex and 4 parts of phosphorylated esterified starch were added, and water was further added to adjust the solid content concentration to 65%. The coating solution was coated so that the coating amount was 14 g / m ² per side. Coating was performed on both sides with a blade coater at a speed of 800 m / min to obtain a coated paper for printing.
[Example 5]
Basis weight containing 100 parts of chemical pulp as paper pulp, 12 parts of light calcium carbonate as filler, and 0.6 parts of ester compound of polyhydric alcohol and fatty acid (KB-110, manufactured by Kao Corporation) as softener. 80 parts 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 a phosphate ester on a base paper of 64 g / m ^2. 4 parts of the modified starch was added, and water was further added to adjust the solid content concentration to 65%. A blade coater was applied at a coating speed of 800 m / min so that the coating amount was 12 g / m ² per one side. To obtain a coated paper for printing.
[Comparative Example 1]
Base paper having a basis weight of 76 g / m ² containing 100 parts of chemical pulp as paper pulp and 12 parts of light calcium carbonate as a filler, 80 parts of heavy calcium carbonate as a pigment, 10 parts of secondary kaolin, and fine kaolin as pigment 10 parts, 0.05 parts of sodium polyacrylate as a dispersant, 11 parts of carboxy-modified styrene-butadiene latex as a binder, and 4 parts of phosphorylated starch were added, and further, water was added to adjust the solid content to 65%. The coating solution was coated on both sides with a blade coater at a coating speed of 800 m / min so that the coating amount was 14 g / m ² per side, to obtain a coated paper for printing.
[Comparative Example 2]
100 parts of chemical pulp as paper pulp, 12 parts of light calcium carbonate as filler, base paper having a basis weight of 103 g / m ² , 65 parts of heavy calcium carbonate as pigment, 7 parts of secondary kaolin, and fine kaolin 28 parts, 0.05 parts of sodium polyacrylate as a dispersant, 9 parts of a carboxy-modified styrene-butadiene latex as a binder, and 2.5 parts of a phosphorylated starch, and further, water was added, and the solid content concentration was 64%. The coating liquid was adjusted on both sides with a blade coater at a coating speed of 500 m / min so that the coating amount was 13 g / m ² per side, 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 a papermaking pulp and 12% of light calcium carbonate as a filler, 95 parts of heavy calcium carbonate as a pigment, 5 parts by weight of secondary kaolin, A coating liquid prepared by adding 0.05 parts of sodium polyacrylate as a dispersant, 4 parts of carboxy-modified styrene butadiene latex as a binder, and 20 parts of phosphorylated esterified starch, and further adding water to adjust the concentration to 40%, Coating is performed on both sides with a film transfer roll coater at a coating speed of 1000 m / min so that the coating amount is 3 g / m ² per side, and 80 parts of heavy calcium carbonate and 20 parts of fine kaolin are used as pigments. 0.05 parts of sodium polyacrylate as a dispersant and carboxy-modified styrene-butadiene latex as a binder 11 parts and 4 parts of phosphorylated esterified starch were added, and water was further added to adjust the solid content concentration to 64%. The coating liquid was coated at a coating rate of 11 g / m ^{2 on} one side. Coating was performed on both sides with a blade coater at 900 m / min to obtain a coated paper for printing.
[Comparative Example 4]
A coated paper for printing was obtained in the same manner as in Comparative Example 3 except that the basis weight of the base paper was changed to 82 g / m ² .
[Comparative Example 5]
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.

に お い て In the coated printing paper manufactured under the above conditions, the basis weight, density, Young's modulus in the papermaking direction, and tear length in the papermaking direction were measured, and the product of the four was calculated. Further, the evaluation of the ease of page turning and the operability in a printing machine when the same paper was bound into a booklet were evaluated. The results are shown in Table 1.

　表１から明らかなように、坪量、密度、抄紙方向のヤング率、および抄紙方向の裂断長の４者の積の値が１．０×１０²¹ｇ²・Ｎ／ｍ^６以上４．０×１０²¹ｇ²・Ｎ／ｍ^６以下の範囲にあれば、原紙、顔料塗被層の組成の違いの有無にかかわらず、柔軟性に優れるためページがめくりやすく、かつ嵩高で、印刷機での作業性も優れる印刷用塗被紙であることが明らかである。

As is clear 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. If it is within the range of 0 × 10 ²¹ g ² · N / m ⁶ or less, the printing machine is excellent in flexibility and easy to turn over and bulky, regardless of the composition of the base paper and the pigment coating layer. It is clear that this is a coated paper for printing which also has excellent workability in the above.

Claims (3)

In a printing coated paper having a coating 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 the breaking length in the papermaking direction is 1.0 × A printing method characterized by being 10 ²¹ g ² · N / m ⁶ or more and 4.0 × 10 ²¹ g ² · N / m ⁶ or less, and containing 5 to 50 parts by weight of an adhesive based on 100 parts by weight of a pigment. For coated paper. The product of the basis weight, density, Young's modulus in the papermaking direction and the breaking length in the papermaking direction is 2.0 × 10 ²¹ g ² · N / m ⁶ or more and 3.5 × 10 ²¹ g ² · N / m ^6. The coated paper for printing according to claim 1, wherein: Coated paper for printing according to claim 1 or 2, characterized in that the 9~25g / m ² coating at least one surface per the coated amount of coating layer.