JP4745639B2 - Method for producing coated paper for printing - Google Patents

Description

  The present invention relates to a method for producing a coated paper for printing, in which a coating liquid is applied onto a paper substrate using a blade coater.

In recent years, printing paper for printing has been required to improve productivity as the demand for it increases. For this reason, for coating machines, the coating speed is increased and the paper width is increased. It is desired to cope with the increase in the solid concentration of the coating liquid. Therefore, a blade coater that has high-speed coating suitability for high viscosity and high concentration coating liquids and that can obtain high paper quality, especially the coating liquid solid content per side is 5 to 20 g / m. A chip (bevel) type blade coater having excellent coating suitability for about ^two general printing coated papers is widely used.

  In the bevel type blade coater, as is well known, after the coating liquid is applied to the paper substrate that continuously runs on the roll by the rotation of the backing roll, the paper base is applied by the tip of the doctor blade. The excess coating liquid is scraped off from the coated surface of the material, and at the same time, the coated surface is made smooth. By the way, in such a doctor blade, its tip is continuously rubbed against the paper base material and the coating liquid, and because it is necessary to scrape off the excess with a very large shearing force, etc. Rapid wear may occur at the tip, and the coating quality may be significantly reduced. In particular, when a high coating speed of 1200 m / min or more is used, uneven wear tends to occur along the paper width direction of the tip, and the coating liquid is uniformly applied due to the uneven wear. Coating defects such as bleeding that leaks onto the coating surface on the opposite side of the blade (running side of the paper base), centering on the recessed part, are not possible. Sometimes appeared. Therefore, in the conventional manufacturing method, for example, as described in Patent Documents 1 and 2 below, instead of a doctor blade made of a single material such as a high carbon steel plate, a surface hardened portion made of a ceramic material is provided at the tip. It has been proposed to use a doctor blade that is provided at the tip and has improved wear resistance at the tip.

Japanese Patent No. 3453716 Japanese Patent Laid-Open No. 2002-254014

  However, in the conventional method as described above, the wear resistance of the doctor blade is improved by the surface-hardened portion, but there is a problem that a conforming defect tends to occur in the doctor blade. That is, in order to improve the productivity of coated paper by increasing the coating speed or the like, the conventional method deteriorated the familiarity of the doctor blade with the backing roll as the surface-cured portion was hardened. For this reason, after the replacement with a new doctor blade, until the blade adapts, the coating amount in the paper width direction and the paper substrate running direction is not uniform, and the coated surface becomes rough and the desired coating is performed. In some cases, the coating liquid could not be coated on the paper substrate due to the work amount distribution (coating profile).

  In view of the conventional problems as described above, it is an object of the present invention to provide a method for producing a coated paper for printing excellent in productivity that can stabilize a coating profile at an early stage.

The present invention uses a blade coater provided with a doctor blade provided at a tip portion where a surface-hardened portion is in contact with a paper base material, and the amount of solid content of a coating liquid containing a pigment and an adhesive is the paper base. A method for producing a coated paper for printing, wherein the coating liquid is applied at a coating speed of 1200 m / min or more so as to be 5 to ²⁰ g / m ² per side of the material,
The surface hardened portion is made of a material mainly composed of tungsten,
The Vickers hardness with a 1000~1 5 00Hv in the surface hardening portion, the R processing portion subjected to R processing to the cutting edge portion of the surface hardening portion is provided, and the R in the R processing unit 0. It is characterized by being 1 ± 0.02 mm.

In the manufacturing method of the coated paper for printing comprised as mentioned above, invention of this application is provided by providing R process part which has R of 0.1 +/- 0.02mm in the most advanced location of the surface hardening part of a doctor blade. Have found that the familiarity of the doctor blade can be improved. Further, by making the Vickers hardness of the above hard facing with 1000~1 5 00Hv, even such as when the speed of coating speed, while applying a suitable abrasion resistance to the hard facing, R processing The effect of improving the familiarity by the part can be surely exhibited, and the coating profile can be stabilized at an early stage.

In addition, when R of said R process part is made smaller than 0.98 mm, the conformity improvement effect of the doctor blade by the said R process part becomes small, and it depends on coating speed, coating amount (solid content adhesion amount), etc. May not be able to stabilize the coating profile early. On the other hand, when an R-processed portion of R larger than 1.02 mm is provided, wear starting from the R-processed portion is likely to occur in the surface-hardened portion, and the life of the doctor blade may be reduced.
Further, when the Vickers hardness at the surface hardened portion is less than 1000 Hv, depending on the coating speed or the like, wear tends to occur in the surface hardened portion, and the life of the doctor blade may be reduced. On the other hand, if it is greater than 1 5 00Hv Vickers hardness it may not be able to quickly stabilize the the coating profile conformability improvement in not sufficiently obtained by the R processing portion.

In the method of making a coated printing paper, the surface hardening portion, by forming a material composed mainly of tungsten, while sufficiently ensuring the wear resistance of the hard facing, increase its toughness Therefore, the effect of improving the familiarity by the R processed part can be easily improved. That is, tungsten is a material excellent in wear resistance, and it is possible to easily extend the life of the surface hardened portion, and thus the doctor blade. Further, since the particles of tungsten are fine, it is possible to easily obtain a good coated surface feeling, and it is possible to suppress the deterioration of the coated surface feeling as much as possible even when the surface hardened portion is worn.

In the method for producing a coated paper for printing, the coating liquid has a solid concentration of 50 to 72% by weight and a capillary viscosity at a shear rate of 10 ⁵ sec ⁻¹ of 70 mPa · s. It may be the following.
In this case, even when the coating speed is increased, the concentration and viscosity of the coating liquid are set appropriately, and the improvement in productivity of the coated paper by increasing the coating speed is not hindered. In addition, when the solid content concentration of the coating liquid is lower than 50% by weight, the coating efficiency may be lowered. On the other hand, when the solid content concentration is higher than 72% by weight, even when the surface-cured portion is relatively hard, wear in the cured portion is likely to proceed and it may be difficult to increase the coating speed and the like. is there. In addition, even when the capillary viscosity at the shear rate is greater than 70 mPa · s, even when the hardened surface portion is relatively hard, wear at the hardened portion is likely to proceed and the coating speed is increased. It may be difficult.

Moreover, in the said manufacturing method of the coated paper for printing, the said surface hardening part may have a Vickers hardness of 1200-1500Hv.
In this case, even when the coating speed is increased, it is possible to ensure appropriate wear resistance at the surface hardened portion, and the familiarity with the R processed portion regardless of the material constituting the surface hardened portion. The improvement effect can be sufficiently obtained, and the early stabilization of the coating profile can be more reliably performed. In addition, when the Vickers hardness in the surface hardened portion is larger than 1500 Hv, depending on the material of the surface hardened portion, the effect of improving the conformity by the R processed portion cannot be obtained sufficiently, and the coating layer The thickness may be uneven. Further, when the Vickers hardness is less than 1200 Hv, the life of the doctor blade is likely to be reduced due to wear of the surface hardened portion when the coating speed is increased.

In the method for producing a coated paper for printing, the pigment contains 20 parts by weight or more of heavy calcium carbonate with respect to 100 parts by weight of the total pigment, and the heavy calcium carbonate has an average particle size thereof. Wet heavy calcium carbonate having a diameter of 0.3 to 2.0 μm and a weight ratio of particles having a particle diameter exceeding 2.0 μm may be 10% or less.
In this case, since 20 parts by weight or more of heavy calcium carbonate is contained with respect to 100 parts by weight of the total pigment, it is possible to improve quality such as whiteness in the coated paper. In addition, even when the coating speed is increased, the average particle diameter and the weight ratio of the heavy calcium carbonate are set appropriately, and the improvement in the productivity of the coated paper by increasing the coating speed is hindered. There is nothing. If the amount of heavy calcium carbonate is less than 20 parts by weight, the whiteness may be insufficient. Moreover, when the average particle diameter of heavy calcium carbonate is made smaller than 0.3 μm, the particles are likely to re-aggregate, and the effect of improving coating quality such as whiteness due to the calcium carbonate may be reduced. is there. On the other hand, when the average particle size is larger than 2.0 μm, the effect of improving the coating quality is reduced, or even when the surface hardened portion is relatively hardened, wear at the hardened portion is likely to proceed. It may be difficult to increase the coating speed. In addition, when the weight ratio of particles having a particle size larger than 2.0 μm is larger than 10%, even when the surface-cured portion is relatively hard, wear at the cured portion is likely to proceed. It may be difficult to increase the work speed.

In the method for producing a coated paper for printing, the coating speed may be 1500 m / min or more.
In this case, since the time required for the coating process of the coated paper for printing can be shortened, the productivity of the coated paper can be improved more reliably.

  According to the present invention, even when the coating speed is increased, it is possible to reliably exhibit the effect of improving the conformity of the doctor blade while imparting appropriate wear resistance to the surface-hardened portion of the doctor blade. In addition, it is possible to provide a method for producing a coated paper for printing excellent in productivity that can stabilize the coating profile at an early stage.

Hereinafter, a preferred embodiment showing a method for producing a coated paper for printing of the present invention will be described with reference to the drawings.
FIG. 1 is a side view showing a main configuration of a doctor blade in a method for producing a coated paper for printing according to an embodiment of the present invention. In FIG. 1, the doctor blade 1 of the present embodiment includes a base material 2 indicated by a hatched portion in the drawing and a surface hardened portion 3 provided on the base material 2. The doctor blade 1 is extended in the direction perpendicular to the paper surface in the shape shown in the drawing, and the right end portion of the drawing is shown in a state where the left end portion (free end portion) of the drawing is allowed to deform. It is fixed with the clamp of the omitted blade coater. The doctor blade 1 is arranged to face a paper substrate (base paper) that runs in the direction of the two-dot chain line in the figure by rotating the roll on the backing roll (not shown). And in the doctor blade 1, when the surface hardening part 3 contacts the said paper base material with which the coating liquid was coated, the adhesion amount of the solid content of a coating liquid will be 5-20 g / m < ² > per side. The amount of coating on the paper substrate is adjusted so that a coated coated paper for printing on which a smooth coated surface is formed is produced. The doctor blade 1 is attached to the blade coater so as to be able to control the contact pressure (blade linear pressure) of the surface hardened portion 3 with the paper substrate, and the coating amount can be adjusted by adjusting the blade linear pressure. It can be changed easily. The paper base material is not particularly limited, and various paper base materials containing chemical pulp such as KP, mechanical pulp such as PGW, non-wood pulp such as waste paper pulp or kenaf, or a mixture of two or more kinds thereof. On the other hand, in the manufacturing method of the present invention, an optimum coating process can be performed.

  The base material 2 is made of a material having an appropriate hardness (for example, Rockwell C, 22 or more) and a certain degree of elasticity so that the coating amount can be easily controlled, for example, a carbon tool steel (SK material). Has been. The base material 2 includes a flat lower surface 2a, a land surface 2b orthogonal to the lower surface 2a, an inclined surface 2c inclined to the land surface 2b, and a flat upper surface formed in parallel to the lower surface 2a. 2d, and a lower surface 2a and an upper surface 2d configured in parallel with each other are connected to the clamp.

  The surface hardened portion 3 is made of, for example, a material containing tungsten as a main component, and is formed on the upper surface 3a formed in parallel to the upper surface 2d of the base material 2 and the tip end side of the upper surface 3a. A bevel surface 4 is provided that contacts the paper substrate over the entire surface. More specifically, the surface hardened portion 3 is formed such that, for example, a material obtained by adding aluminum oxide to tungsten as a main component is coated on the inclined surface 2c and the upper surface 2d of the base material 2 by plasma spraying. 2 is formed by surface processing. In addition, the specific dimensions of the base material 2 and the surface hardened portion 3 on the blade land side indicated by S1 and S2 in the drawing are 0.1 to 0.15 mm and 0.3 to 0.35 mm, respectively. Further, specific dimensions of the base material 2 and the surface hardened portion 3 on the fixed end side indicated by S3 and S4 in the same figure are 0.635 mm and 0.3 mm, respectively. Moreover, the specific dimension of the surface hardening part 3 in the left-right direction in the drawing is about 8 mm from the most distal portion at the left end of the drawing, and only the base material upper surface 2d is connected to the clamp. A small amount of chromium, titanium, or the like may be included in tungsten.

Moreover, in the surface hardening part 3, the hardness is set to Vickers hardness, 1000-1700Hv, More preferably, it is set to 1200-1500Hv, Even when the high-speed coating whose coating speed is 1200 m / min or more is implemented, The surface hardened portion 3 has appropriate wear resistance.
The bevel surface 4 is provided with an R processed portion 4a and bent portions 4b and 4c sequentially from the free end side of the doctor blade 1 toward the fixed end side. That is, an R processed portion 4 a having an R (curvature radius) defined by the following range is formed at the most distal portion of the bevel surface 4. Further, the inclined surface 4d between the R processed portion 4a and the bent portion 4b is formed to have a predetermined angle (for example, 32 °) with respect to the upper surface 3a, and between the bent portion 4b and the bent portion 4c. The inclined surface 4e is formed to have a predetermined angle (for example, 20 °) with respect to the upper surface 3a. The R processed portion 4a and the inclined surfaces 4d and 4e are first provided with inclined surfaces 4d and 4e by grinding the surface hardened portion 3, and further chamfering is performed at the most distal portion of the inclined surface 4d. By applying, the R processing part 4a is provided. Further, as described above, the bevel surface 4 is configured in two stages including the two inclined surfaces 4d and 4e, so that an appropriate coating liquid can be applied between the inclined surfaces 4d and 4e and the paper base material. The liquid surface can be formed to improve the coating surface feeling. In addition, the specific dimension of the inclined surfaces 4d and 4e shown by S5 and S6 in the figure is 0.5 mm.

Moreover, in the said R process part 4a, the R is set to 0.1 mm +/- 0.02 mm, and even if high speed coating with a coating speed of 1200 m / min or more is performed, the backing roll of the doctor blade 1 This makes it possible to stabilize the coating profile at an early stage. That is, in the above conventional method, when a new doctor blade having a bevel surface hardened to a Vickers hardness of 1000 Hv or more is used in order to cope with the above-described high-speed coating, the new doctor blade is not compatible. In addition, the coating quality has deteriorated by several tens of minutes, and it has not been possible to prevent a large amount of defective coating paper from being produced. For this reason, the productivity of the coated paper cannot be improved reliably, but conversely, the productivity may be reduced.
On the other hand, in the present invention, the familiarity of the doctor blade 1 is improved by the R processing portion 4a. Therefore, immediately after the doctor blade 1 is replaced with a new one, the coating liquid is immediately applied to the paper base with a desired coating profile. Can be applied to the material. As a result, coated paper of desired quality can be produced immediately after blade replacement, and the productivity of coated paper can be reliably improved by increasing the coating speed. Moreover, since the Vickers hardness of the surface hardened portion 3 is set to 1000 to 1700 Hv and appropriate wear resistance is given to the surface hardened portion 3, unlike the conventional method, it is possible to suppress uneven wear generation, Occurrence of an excessive scraping defect of the coating liquid can be suppressed as much as possible.

  In addition, when the R processing part 4a of R smaller than 0.98 mm is provided, the effect of improving the conformity of the doctor blade 1 by the R processing part 4a is reduced, and the coating speed, coating amount (solid content adhesion amount) ) Or the coating profile may not be stabilized early depending on the viscosity or concentration of the coating solution. On the other hand, when the R-processed portion 4a having the R larger than 1.02 mm is provided, wear starting from the R-processed portion 4a is likely to occur in the surface-hardened portion, and the life of the doctor blade 1 is reduced. Sometimes.

In addition, when the Vickers hardness at the surface hardening portion 3 is smaller than 1000 Hv, the surface hardening may occur depending on the coating speed, the coating amount (solid content adhesion amount), or the viscosity or concentration of the coating liquid. This is likely to occur in the portion 3 and the life of the doctor blade 1 may be reduced. Further, when the surface hardened portion 3 having a Vickers hardness smaller than 1200 Hv is formed, the life of the doctor blade 1 due to insufficient strength of the surface hardened portion 3 when coating is performed at a high speed of 1500 m / min or more. May decrease.
On the other hand, when the Vickers hardness is set higher than 1700 Hv, there is a case where the coating profile cannot be stabilized at an early stage because the effect of improving the conformity by the R processed portion 4a cannot be sufficiently obtained. In addition, when it is larger than 1500 Hv, depending on the material of the surface hardened portion 3, the effect of improving the conformity by the R processed portion 4 a is not sufficiently obtained, and the thickness of the coating layer on the paper base material is A coating profile defect may occur without being uniform. Further, time and labor may be required for chamfering and grinding for forming the R processed portion 4a and the bent portion 4b.

  In addition to the above-mentioned tungsten-based material, it contains one or more metal oxides, metal carbides, metal nitrides, ceramic materials such as cermets in combination thereof, tungsten carbide and chromium carbide. The surface hardened portion 3 may be constituted by a cemented metal such as cemented carbide or chrome plating. Moreover, the surface hardening part 3 can also be formed on the base material 2 using the thermal spraying methods other than plasma, vapor deposition methods, such as PVD and CVD. However, when using the above-described material mainly composed of tungsten, the toughness can be enhanced while sufficiently securing the wear resistance of the surface hardened portion 3, and other materials were used. Compared to the case, it is preferable in that the conforming improvement effect by the R processed portion 4a can be easily improved and the conforming time of the doctor blade 1 can be shortened. In addition, since the particles of tungsten are fine, it is possible to easily obtain a good coating surface feeling and to suppress the deterioration of the coating surface feeling as much as possible even when the surface hardened portion 3 is worn. It becomes.

  Further, when the surface hardened portion 3 having a hardness greater than 1500 Hv is formed using a metal nitride ceramic material or a material with relatively low toughness such as chrome plating, the surface hardened portion 3 becomes brittle. The life of the doctor blade 1 may be shortened. Therefore, the hardness of the surface hardened portion 3 is set to 1200 Hv or more that can sufficiently suppress the life reduction of the doctor blade 1 even when high-speed coating of 1500 m / min or more is performed, and the R processed portion 4a and the like. It is relatively easy to form, and regardless of the material of the surface hardened portion 3, the effect of improving the conformity by the R processed portion 4 a can be sufficiently obtained, and early stabilization of the coating profile can be more reliably performed with 1500 Hv or less. More preferably.

Further, the coating liquid contains a pigment and an adhesive, and the coating quality and the coating property of the coated paper such as whiteness are improved. Furthermore, auxiliary agents, such as a dispersing agent, a thickener, a water retention agent, a defoaming agent, a water-resistant agent, and a coloring agent, can also be added to the coating liquid as necessary.
Specifically, the pigment contains 20 parts by weight or more of heavy calcium carbonate with respect to 100 parts by weight of the total pigment, and the whiteness, glossiness, opacity, ink acceptability, etc. on the coated paper Improvement of quality is planned. If the amount of calcium carbonate is less than 20 parts by weight with respect to 100 parts by weight of the total pigment, the whiteness may be insufficient. The pigment may be all heavy calcium carbonate, other pigments such as clay, kaolin, talc, silica, zinc oxide, barium sulfate, titanium dioxide, aluminum hydroxide, and other organic pigments such as plastic pigments. A pigment and calcium carbonate may be mixed.

  Moreover, the said adhesive agent is not specifically limited, Latex, starch, modified starch, PVA, carboxymethylcellulose (CMC), casein, soybean protein, etc. can be illustrated. Among these, as latexes, copolymers such as styrene / butadiene copolymers, conjugated diene copolymer latexes such as methacrylate / butadiene copolymers, vinyl copolymer latexes including acrylates and methacrylates, etc. Latex can be exemplified, and modified starch can be exemplified by oxidized starch, phosphate esterified starch, hydroxyethyl etherified starch, enzyme-modified starch and the like.

In the coating liquid, the solid content is preferably 50 to 72% by weight and the capillary viscosity at a shear rate of 10 ⁵ sec ⁻¹ is adjusted to 70 mPa · s or less. That is, when the coating liquid having the concentration and viscosity prepared as described above is used, when the blade linear pressure is relatively high, that is, when high-speed coating of 1200 m / min or more is performed, or the coating amount is Even in the case of 12 g / m ² or less, the concentration and viscosity of the coating liquid can be made appropriate for the coating speed and coating amount, and the coated paper can be improved by increasing the coating speed. Productivity can be improved and fine coated paper can be produced without hindrance.
In addition, when the solid content concentration of the coating liquid is lower than 50% by weight, the coating efficiency may be lowered. On the other hand, when the solid content concentration is higher than 72% by weight, even when the surface-cured portion 3 is relatively hard, wear at the surface-cured portion 3 is likely to proceed and it is difficult to increase the coating speed. Or it may be difficult to reduce the coating amount.
In addition, even when the capillary viscosity at the shear rate is greater than 70 mPa · s, even when the surface-cured portion 3 is relatively hard, wear at the surface-cured portion 3 is likely to proceed and the coating speed is increased. It may be difficult to increase the speed and fine coating.

The heavy calcium carbonate is a wet heavy calcium carbonate having an average particle diameter of 0.3 to 2.0 μm and a weight ratio of particles having a particle diameter exceeding 2.0 μm of 10% or less. It is preferable to do. When such wet heavy calcium carbonate is used, even when high-speed coating of 1200 m / min or more is performed or when the coating amount is 12 g / m ² or less, the coating speed and coating amount are not affected. Thus, the average particle diameter and the weight ratio can be made appropriate, and the productivity of coated paper can be improved by increasing the coating speed and the production of fine coated paper can be performed without any trouble.
In addition, when the average particle diameter of heavy calcium carbonate is made smaller than 0.3 μm, the particles are likely to re-aggregate, and the effect of improving coating quality such as whiteness due to the calcium carbonate may be reduced. is there. On the other hand, when the average particle diameter is larger than 2.0 μm, even when the effect of improving the coating quality is reduced or the surface hardened portion 3 is made relatively hard, wear at the surface hardened portion 3 proceeds. This may make it difficult to increase the coating speed or to reduce the coating amount.
Further, when the weight ratio of the particles having a particle diameter larger than 2.0 μm is larger than 10%, even when the surface hardened portion 3 is made relatively hard, wear at the surface hardened portion 3 is likely to proceed. Thus, it may be difficult to increase the coating speed or to make fine coating. In addition, the said average particle diameter and weight ratio can be measured, for example using Cedygraph 5100 V3.07.

[Example]
Hereinafter, the test result example of the verification test performed by the inventor of the present invention will be specifically described.
In this verification test, Examples 1 to 8 equivalent to the products of the present invention shown in Table 1 and Comparative Examples 1 to 8 equivalent to the conventional products shown in Table 2 were prepared. In each example, the elapsed time from when the doctor blade was replaced with a new doctor blade until the coating liquid was stably coated on the paper substrate with the desired coating profile was determined as the familiar time. Furthermore, the elapsed time until the time when it was determined that the doctor blade had to be replaced anew due to the deterioration of the coating quality due to the wear generated on the new doctor blade was defined as the lifetime of the doctor blade.

In all examples, a doctor blade was used in which a surface hardened portion mainly composed of tungsten was formed on a base material made of SK material. Further, the pulp composition of the paper base material is common, and specifically, LBKP (85%) and NBKP (15%). In all examples, wet heavy calcium carbonate is added as a pigment in an amount of 30 parts by weight with respect to 100 parts by weight of the total pigment, and latex is mixed in an amount of 8.5 parts by weight with respect to 100 parts by weight of the total pigment. did. The solid content concentration of the coating liquid was 67% by weight, and the capillary viscosity at a shear rate of 10 ⁵ sec ⁻¹ was 30 mPa · s. The heavy calcium carbonate having an average particle diameter of 2.2 μm and a weight ratio of particles exceeding 2.0 μm was 10%.

  As is clear from Tables 1 and 2, it was confirmed that in each of the examples corresponding to the product of the present invention, the familiarization time can be significantly reduced to 5 to 10 minutes as compared with the comparative examples corresponding to the conventional product. In addition, in each example, it was proved that at least the shortening time of the familiar time can be increased as the actual working time of the doctor blade as compared with each comparative example, and the occurrence of defects in the coating profile is suppressed more efficiently. Proven to produce coated paper for printing.

  In the above description, the case of using a doctor blade provided with an R-processed portion at the most advanced portion of the surface-hardened portion has been described. There is no limitation as long as at least one R processed portion is provided and the Vickers hardness at the surface hardened portion is 1000 to 1700 Hv. For example, at least one of the two bent portions has the R range. R processing may be performed.

It is a side view which shows the principal part structure of the doctor blade in the manufacturing method of the coated paper for printing which concerns on one Embodiment of this invention.

Explanation of symbols

1 Doctor blade 3 Surface hardened part 4a R processed part

Claims (5)

Using a blade coater having a doctor blade provided at the tip where the surface hardened portion comes into contact with the paper substrate, the amount of solid content of the coating liquid containing the pigment and adhesive per one side of the paper substrate A method for producing a coated paper for printing, in which the coating liquid is applied at a coating speed of 1200 m / min or more so as to be 5 to ²⁰ g / m ² ,
The surface hardened portion is made of a material mainly composed of tungsten,
The Vickers hardness with a 1000~1 5 00Hv in the surface hardening portion, the R processing portion subjected to R processing to the cutting edge portion of the surface hardening portion is provided, and the R in the R processing unit 0. 1 +/- 0.02 mm, The manufacturing method of the coated paper for printing characterized by the above-mentioned. The coating solution according to claim 1, characterized in that the concentration of solids is 50-72 wt%, and the capillary viscosity at the shear rate 10 ⁵ sec ^-1 or less 70 mPa · s Method for producing coated paper for printing. The said surface hardening part has the Vickers hardness of 1200-1500Hv, The manufacturing method of the coated paper for printing in any one of Claim 1 or 2 characterized by the above-mentioned. The pigment contains 20 parts by weight or more of heavy calcium carbonate with respect to 100 parts by weight of the total pigment, the heavy calcium carbonate has an average particle diameter of 0.3 to 2.0 μm, and The method for producing a coated paper for printing according to any one of claims 1 to 3 , wherein the weight ratio of particles having a particle diameter exceeding 2.0 µm is wet heavy calcium carbonate having a particle size of 10% or less. The said coating speed is 1500 m / min or more, The manufacturing method of the coated paper for printing in any one of Claims 1-4 characterized by the above-mentioned.

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