JP2007084981A - Coated paper for printing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coated paper for printing, having a low density, high gloss and excellent quality of a printed surface, hardly having coating unevenness such as pinholes and produced in high productivity. <P>SOLUTION: The coated paper for the printing has one or more of coated layers formed at least on one surface of a base paper. At least one layer of the coated layers is formed by a curtain coating method, and the coated layer formed by the curtain coating method is formed by bringing the coated layer into contact with the surface smoothened by a long-nip calender treating apparatus comprising a hot metal roll and a shoe roll. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a coated paper for printing. More specifically, the present invention relates to a coated paper for printing that has low density, high gloss, excellent printing surface quality, and can be produced with high productivity without uneven coating of pinholes.

  For coated paper for printing, high glossiness of the coated surface, excellent print surface quality, and the like have been required due to the visualization, colorization, and high-quality of printed matter. The excellent print surface quality here means that the unevenness on the surface of the base paper is completely covered with the coating layer, the printed surface has no blur derived from the base paper, and the coating layer structure is uniform, This indicates a state where there is no opacity unevenness or ink receiving unevenness. On the other hand, in recent years, a reduction in density has been demanded for coated paper for printing due to an increase in environmental awareness and a demand for cost reduction. Of course, at this time, high glossiness of the coated surface, excellent printing surface quality, etc. must be maintained.

  Low-density coated paper for printing is light in weight even with the same thickness, and can reduce the weight of catalogs and magazines. Therefore, transportation costs can be reduced and resources can be saved. In addition, even if the number of pages is small, the book becomes thick, which has the effect of increasing the reader's satisfaction. In recent years, there has been a tendency to demand coated paper for printing with a lower density.

  In order to reduce the density of the coated paper for printing, it is important that the coating liquid does not fall into the base paper and that the coating layer itself is less compressed. Even if the density of the base paper itself is reduced, if the coating liquid drops into the base paper at the time of coating, and if the coating layer itself is highly compressed, the printing paper as a whole will have a high density. . Therefore, the selection of the coating method is important for reducing the density of the coated paper for printing. Post-weighing types such as blade coating have a process of scraping off the excessively supplied coating liquid on the base paper. At this time, a considerable pressure is applied to the coated surface, so coating inside the base paper The drop of the liquid is remarkable, and the coating layer itself is also compressed, which is disadvantageous for reducing the density. On the other hand, in the curtain coating method, since the pre-weighed coating liquid is supplied onto the base paper without receiving pressure, the coating liquid hardly falls into the base paper, and the compression of the coating layer itself is also small. It is an advantageous coating method for obtaining a low-density printing coated paper.

  As described above, the curtain coating method is a coating method capable of obtaining a low-density printing coated paper, but has other advantages. In the case of the blade coating method, which is the mainstream in the production of coated paper for printing, the resulting coated surface is flat, but if the surface to be coated is uneven, the coating layer itself has uneven thickness, which is Ink acceptance unevenness is likely to occur. The curtain coating method forms a so-called contour coating layer in which the coating liquid is extremely uniform along the surface shape of the surface to be coated. Therefore, the thickness of the coating layer is uniform, and unevenness in ink reception is unlikely to occur. However, when the surface shape of the surface to be coated has irregularities, the surface of the resulting coated paper for printing also has irregularities, making it difficult to exhibit high gloss and excellent printing surface quality. On the contrary, when the surface to be coated is not uneven and has high smoothness, the surface of the resulting coated paper for printing is flat and the coating layer itself has no unevenness in thickness, resulting in the highest glossiness and Excellent print quality can be developed.

  The curtain coating method is free of streaks and scratches, has a low possibility of paper breakage, and is excellent in suitability for high-speed coating. However, it has a higher coating speed for the purpose of improving productivity. When the increase is attempted, a so-called air entrainment phenomenon occurs in which air is entrained in the coating surface and the coating liquid. That is, the air flow carried by the traveling web collides with the contact line between the curtain film and the surface to be coated, and the curtain film and the contact line are shaken, and the coated surface and the coating liquid When this air entrainment occurs, a pinhole-shaped uncoated portion appears on the coated surface, and this pinhole-shaped uncoated portion is coated. Even after printing, printing unevenness remains as printing unevenness. It is well known that such air entrainment appears as a remarkable phenomenon as the coating speed increases and the smoothness of the surface to be coated decreases. If the coating speed is not increased, this air entrainment phenomenon is unlikely to occur, but this manufacturing method is extremely disadvantageous. A method of controlling the air entrainment by controlling the viscosity and surface tension of the coating liquid has been proposed (see, for example, Patent Document 1), but this method has limitations in designing the coating liquid. It is difficult to express satisfactory print quality. Therefore, it is important to improve the smoothness of the surface to be coated.

  That is, in order to obtain a low-density printing coated paper, it is effective to provide a coating layer by a curtain coating method, but in order to achieve higher productivity without air entrainment, high glossiness, In order to develop an excellent printing surface quality, the smoothness of the surface to be coated must be improved.

  In order to develop high glossiness and excellent printing surface quality, a technique for providing a coating layer after applying a smoothing process to a base paper in advance (see, for example, Patent Document 2) has been proposed. This technology is generally processed with a soft calender device. According to this technology, not only a coated paper for printing with high glossiness and excellent printing surface quality is obtained, but also the effect of eliminating air entrainment. Although it can be expected, in order to obtain a preferable smoothness, the base paper density becomes too high, and a low-density printing coated paper cannot be obtained. In addition, paper stiffness is lowered and opacity unevenness is likely to occur. Furthermore, since the coating layer provided by the curtain coating method is mainly composed of aragonite-type light calcium carbonate, it is possible to obtain a low-density coating paper for smear printing and to exhibit high gloss (for example, Patent Document 3). Have been proposed). However, light calcium carbonate often does not provide satisfactory gloss when compared with plate-like pigments such as kaolin.

Therefore, the present situation is that a coated paper for printing that has low density, high gloss, excellent printing surface quality, and can be produced with high productivity without uneven coating of pinholes has not been obtained.
JP 2001-262494 A JP-A-6-25992 JP-A-7-166493

  An object of the present invention is to provide a coated paper for printing which has a low density, high gloss, excellent printing surface quality, and can be produced with high productivity without uneven coating of pinholes.

  As a result of diligent research in view of the above, the present inventor has found that at least one of the coating layers is curtain coated in a printing coated paper having at least one coating layer on at least one side of the base paper. The coating layer provided by the curtain coating method is provided in contact with the surface smoothed by a long nip calender processing device comprising a heated metal roll and a shoe roll. It came to invent the coated paper for printing characterized by being a thing.

More preferably, in a printing coated paper in which one or more coating layers are provided on at least one side of the base paper, at least one of the coating layers is provided by a curtain coating method, And the coating layer provided by the curtain coating method is provided in contact with the surface smoothed by a long nip calender processing device comprising a heated metal roll and a shoe roll. In the coated paper for printing, it came to invent the coated paper for printing characterized by the density of the coated paper for printing being 0.67 to 1.20 g / cm ³ .

  ADVANTAGE OF THE INVENTION According to this invention, the coating paper for printing which can be manufactured with low productivity, high glossiness, excellent printing surface quality, and high productivity without pinhole coating unevenness is provided.

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

  The printing coated paper in the present invention is a printing coated paper in which at least one coating layer is provided on at least one side of a base paper, and at least one of the coating layers is provided by a curtain coating method. It is characterized by being. The base paper may be one in which a single-layer coating layer is provided by a curtain coating method, or two or more layers may be provided, one of which is provided by a curtain coating method. Of the two or more layers, a plurality of coating layers may be provided by a curtain coating method. However, the coating layer provided by the curtain coating method must be in direct contact with the surface smoothed by a long nip calendering device composed of a heated metal roll and shoe roll. When the coating layer is provided directly on the base paper by the curtain coating method, the surface of the base paper must be smoothed by a long nip calendering device composed of a heated metal roll and shoe roll. When a coating layer is further provided by the curtain coating method on the state where the coating layer is already provided, a long nip calender comprising a metal roll and a shoe roll whose surface is already provided is heated. It must be smoothed by the processor.

  As a result of earnest investigation, the present inventor has obtained low-density, high-gloss, excellent printing surface quality, and can be produced with high productivity without pinhole coating unevenness. I found out that the proposed technology has limitations. That is, if the surface on which the coating layer is provided by the curtain coating method is not smoothed, a low-density printing coated paper can be obtained, but the curtain coating layer is the coating layer or base paper directly below it. A printing paper having high gloss and excellent printing surface quality cannot be obtained, and pinhole-shaped coating unevenness occurs when high-speed coating is applied. In addition, when a coating layer by a curtain coating method is provided on a surface that has been smoothed by a soft calender processing device comprising a conventional metal roll and an elastic roll, the nip width of the soft calender processing device is the roll to be used. Due to restrictions on diameter, hardness and coating thickness of elastic roll coating material, mechanical strength, etc., it is practically at most about 10 mm. If you try to obtain satisfactory smoothness with this method, the density will inevitably decrease. This must be sacrificed.

  Therefore, instead of the conventional elastic roll, using a shoe roll capable of realizing a long nip width, calendar treatment was performed on the surface on which the coating layer by the curtain coating method was provided. High smoothness and low density that could not be achieved at the same time. As a result, it is a low-density, high-gloss, excellent printing surface quality, and can be produced with high productivity without pinhole coating unevenness. The inventors found that a craft paper was obtained and reached the present invention.

  The long nip calendering process comprising the heated metal roll and shoe roll used in the present invention will be described with reference to FIG. 1. For example, when the base paper is directly subjected to the long nip calendering process, the base paper 5 is heated. The shoe roll 4 is calendered by passing between the pressurized states of the metal roll 1 and the shoe roll 4, and the shoe roll 4 has a resin belt 2 that runs along with the running base paper 5 on the roll outer surface. A shoe 3 is provided inside the resin belt 2, and the shoe 3 is pressurized by a pressure cylinder 7 fixed to the central axis of the main body. Further, the lubricating oil 6 is press-fitted from the central portion of the shoe 3, and a lubricating film is formed between the shoe 3 and the resin belt 2 to reduce mechanical friction. When the shoe 3 pushes up the resin belt 2, a long nip portion and a nip pressure gradient according to the shape of the shoe 3 are formed between the opposing metal rolls, and the base paper 5 is calendered.

  The following is conceivable as the reason why the calendering method using the long nip calender device composed of a heated metal roll and a shoe roll according to the present invention is particularly effective.

  According to the above method of the present invention, for example, a case where the base paper is directly subjected to the long nip calendering process will be described. The nip width is remarkably increased as compared with a normal hard nip calender apparatus and the soft calender apparatus shown in FIG. Since it can be widened, the nip residence time is significantly extended. As a result, the amount of heat received by the base paper in contact with the heated metal roll is significantly increased, and the base paper is more susceptible to plastic deformation than when a normal calender device having a heating roll is used. It is done. In addition, due to the wide nip width, calendering with a low nip surface pressure is possible, so it is possible to avoid an unavoidable increase in the density of the base paper, especially near the surface of the base paper, which is particularly susceptible to heat and pressure Is preferentially smoothed, so that both satisfactory paper smoothness and smoothness can be achieved.

  The shoe roll is not particularly limited as long as it is a shoe roll having a wide nip width in a long nip calender process including a heated metal roll and a shoe roll. For example, “Opti Duel Shoe Calender” (manufactured by Metso SHI) is The nip width is preferably used because the nip width can be expanded to a maximum of 270 mm.

  The material of the metal roll used in the present invention is not particularly limited as long as it can be heated, but a general-purpose metal roll obtained by applying chrome plating to iron may be used.

  The nip width in the long nip calender device composed of a metal roll and a shoe roll used in the present invention can be increased up to 270 mm although it depends on the structure of the shoe roll. The nip width in the present invention is preferably 40 to 90 mm. If it is less than 40 mm, paper stiffness, opacity unevenness, and ink receiving unevenness are likely to occur, and if it is 90 mm or more, the smoothness of the base paper may not be sufficiently obtained. In this case, in the present invention, it is an essential condition that the metal roll is heated, and the heating temperature is not generally determined, but is usually 120 to 230 ° C., preferably 150 to 200 ° C.

The pressurization conditions for the long nip calender treatment comprising a heated metal roll and shoe roll are not particularly limited, but the final density of the resulting coated paper for printing is 0.67 to 1.20 g. / Cm ³ is preferable. When the density is 0.67 g / cm ³ or more, more satisfactory gloss and printing surface quality can be obtained when the coated paper for printing is manufactured, and the density is 1.20 g / cm ³ or less. A more satisfactory low-density coated paper for printing can be obtained.

  In the smoothing process according to the present invention, when the long nip calender process is directly performed on the base paper, the position may be either before or after the size press of the paper machine, or both. Further, the smoothing processing method in the present invention may be a multi-stage processing if necessary. If necessary, a combination of a heated elastic roll and a shoe roll may be used instead of the heated metal roll as long as the characteristics of the present invention are not impaired. However, in the present invention, a long nip calender treatment must be applied to the surface of the base paper or the coating layer on which the coating layer is applied by the curtain coating method. The coated paper for printing often has various smoothing treatments applied to the top surface of the coating layer or the surface of the undercoat layer in the case of multilayer coating. Even if the long nip calendering process is performed on the uppermost surface of the coating layer or the surface of the other coating layer without performing the calendering process, the above coated paper for printing cannot be obtained. In addition, when a long nip calender treatment is performed on the surface on which the coating layer is provided by the curtain coating method, performing a smoothing treatment on the uppermost surface of the coating layer or the other coating layer surface, if necessary, There are no restrictions. The type of calendar device or other smoothing device at this time is not limited at all.

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

  Examples of the base paper used in the present invention include a no-size press base paper, or a base paper size-pressed with starch, polyvinyl alcohol, or the like. In addition, as the paper machine in the base paper making method of the present invention, a paper machine known in the paper industry such as a long paper machine, a twin wire paper machine, a combination paper machine, a round paper machine, and a Yankee paper machine can be used as appropriate.

  The present invention relates to a coated paper for printing. In general, all of those used for producing a coated paper for printing may be blended. The pigment blended in the coating liquid used in the present invention is not particularly limited, and examples thereof include kaolin, clay, heavy calcium carbonate, light calcium carbonate, titanium dioxide, satin white, talc, aluminum hydroxide, and plastic pigment. Etc. These may be used alone, and the use of a plurality of these in combination is not limited.

  The adhesive compounded in the coating liquid used in the present invention is not particularly limited. For example, ordinary starch, oxidized starch, phosphate esterified starch, enzyme-modified starch, and cold water obtained by freshly drying them. Starches such as soluble starch, various copolymer latexes such as styrene-butadiene, acrylic and vinyl acetate, polyvinyl alcohol, sodium polyacrylate, polyethylene oxide, polyacrylamide, urea or melamine / formalin resin, polyethyleneimine, polyamide Examples thereof include water-soluble synthetic compounds such as polyamine / epichlorohydrin, natural products such as wax, casein and soybean protein, and those obtained by cationizing these. These may be used alone, and the use of a plurality of these in combination is not limited.

  In the coating liquid used in the present invention, all those generally used for producing coated paper may be blended. For example, as a thickener, water-soluble polymers such as carboxymethylcellulose, sodium alginate, methylcellulose, hydroxyethylcellulose, casein, sodium polyacrylate, synthetic polymers such as polyacrylate, styrene maleic anhydride copolymer, Examples include silicates. In addition, dispersants, pH adjusters, lubricants, antifoaming agents, water resistance agents, surfactants, foam suppressors, mold release agents, foaming agents, penetrating agents, coloring dyes, fluorescent whitening agents as necessary Various auxiliary agents such as ultraviolet absorbers, antioxidants, antiseptics, antibacterial agents, and those obtained by cationizing these auxiliary agents are preferably used. You may mix | blend another component as needed.

  The printing coated paper in the present invention is a printing coated paper in which at least one coating layer is provided on at least one side of a base paper, and at least one of the coating layers is provided by a curtain coating method. It is characterized by being. When at least one or more layers are not provided by the curtain coating method, the above-described printing coated paper cannot be obtained. In addition to this, when a coating layer is provided, the coating method is not particularly limited, and various blades, or various metade film transfers such as size press, gate roll, shim sizer, air knife, rod, etc. . In addition, the coating layer of the coating paper for printing in the present invention is not particularly limited, even if it is a single layer or a multilayer, and when performing multilayer coating, a coating layer is provided by appropriately combining the above coating methods. There is no limit to this. Of course, it is not limited at all to provide two or more layers by the curtain coating method.

In the coated paper for printing of the present invention, the total mass after drying of the coating layer provided on the base paper is not particularly limited, but the total number of coating layers provided on one side is usually 2 to 2. a 25 g / m ^2, preferably 4~18g / m ^2.

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

The physical properties of the coated paper for printing in each example and comparative example were evaluated by the following methods.
<Evaluation method>
1) Gloss of white paper The gloss of the coated paper for printing was evaluated according to JIS P8142 at an angle of 75 ° -75 ° reflectivity. However, in the present invention, four or more points are the objects of the invention.
5 points: Blank paper gloss of 72% or more 4 points: Blank paper gloss of 68% or more and less than 72% 3 points: Blank paper gloss of 64% or more but less than 68% 2 points: Blank paper gloss of 60% or more but less than 64% 1 point: Blank paper gloss Less than 60%

2) Printed surface feeling Using an RI printing aptitude tester, after performing indigo, red and yellow heavy solid printing, leave it at room temperature all day and night, visually determine the printed surface, and print surface feeling 1-5 Evaluation was made within a range of points. 5 points are the printing surface is flat, there is no unevenness, and there is no opacity unevenness and ink acceptance unevenness, 1 point is the unevenness of the unevenness of the base paper on the printing surface, and there is much opacity unevenness and ink receiving unevenness Indicates that However, in the present invention, four or more points are the objects of the invention.

3) Pinhole-like coating unevenness The pinhole-like coating unevenness accompanying air entrainment is generated by analyzing the image of the surface of the coating layer of the resulting coated paper for printing. The degree of unevenness was visually evaluated. However, in the present invention, four or more points are the objects of the invention.
5 points: No pinhole-like coating unevenness 4 points: No pinhole-like coating unevenness 3 points: Little pinhole-like coating unevenness 2 points: Many pinhole-like coating unevenness 1 Point: Very large pinhole coating unevenness

4) Density of coated paper for final printing The obtained coated paper for printing was subjected to density measurement in the final form after finishing treatment. The density was calculated from the basis weight and thickness of the coated paper for printing according to JIS P8118. In the present invention, a density of 1.25 g / cm ³ or less was the subject of the invention. The density is more preferably 0.67 to 1.20 g / cm ³ .

The base paper was prepared with the following composition, and a base paper for coating having a basis weight of 89 g / m ² was made. A mass part here is the solid content mass ratio of each material with respect to 100 mass parts of total pulp solid content. A commercially available oxidized starch of 0.30 g / m ² per side was adhered to this with a size press to form a base paper. The density of the obtained base paper was 0.60 g / cm ³ .
<Base paper formulation>
LBKP (freeness 440 mlcsf) 70 parts by mass NBKP (freeness 490 mlcsf) 30 parts by mass <Internally added chemicals>
Light calcium carbonate (expressed as ash content in base paper) 6.0 parts by mass Commercial cationized starch 1.0 part by mass Commercially available cationic polyacrylamide yield improver 0.030 parts by mass

  The coating solution was prepared as follows. A mass part here is a solid content mass ratio of each material with respect to 100 mass parts of total pigment solid content in a coating liquid. To 50 parts by mass of commercially available wet heavy calcium carbonate (Carbital 90) and 50 parts by mass of commercially available primary kaolin (Ultra White 90), 0.10 parts by mass of a commercially available polyacrylic dispersant (Aron T-40) was added, 10 parts by mass of commercially available styrene-butadiene copolymer latex and 4.0 parts by mass of commercially available phosphorylated starch are added as adhesives to those dispersed at a solid content concentration of 72% by mass with a disperser, and further commercially available calcium stearate is added. 0.50 part by mass was added and the pH was adjusted to 9.6 with sodium hydroxide to obtain a coating solution. The obtained coating liquid was adjusted to a solid concentration of 60% by mass with adjusted water.

  The coating liquid prepared as described above was applied to the base paper produced as described above, as in Examples and Comparative Examples, and dried. The coated paper thus obtained was subjected to a soft calendering process (using a soft calender consisting of a metal roll heated to 60 ° C. with a hardness of Hs of 84 degrees and a surface roughness of 0.3 S and an elastic roll made of Elaglass with a hardness of 90 ShD. Was applied to the heated metal roll surface at a rate of 80 kN / m once each on the front and back surfaces to produce a coated paper for printing.

A long nip calender (“Optical Dwell Shoe” comprising a metal roll heated to 180 ° C. having a hardness of Hs of 84 degrees and a surface roughness of 0.3 S and a shoe roll having a resin belt having a hardness of 91 ShA as an outer layer and a shoe width of 70 mm inside. Using a calendar (made by Metso SHI), the base paper was calendered under calendering conditions of 150 kN / m as shown in Table 1. The calendar pressurization conditions listed in Table 1 are described in units of kN / m as weights (kN) applied per unit width (1 m) of the base paper to be calendar processed. The long nip calendering process was performed so as to contact the heated metal roll surface of the long nip calender once on each side. The coating liquid obtained as described above was applied to the base paper that had been subjected to the long nip calender treatment in this manner at a coating speed of 700 m / min using a curtain coater. One side was coated on both sides, and the coating amount per side at this time was 12.0 g / m ² . The obtained coated paper was subjected to the above finishing treatment to produce a coated paper for printing. Table 2 shows the evaluation results of the coated paper for printing.

A base paper subjected to long nip calendering under the same conditions as in Example 1 was obtained. The coating liquid obtained as described above was applied to the base paper that had been subjected to the long nip calender treatment in this manner at a coating speed of 700 m / min using a curtain coater. One side was coated on both sides, and the coating amount per side at this time was 6.0 g / m ² . Further, on this coated surface, the coating liquid obtained as described above was applied by a blade coater at a coating speed of 700 m / min, a coating amount per side of 6.0 g / m ² , under the conditions of simultaneous coating on both sides. Coated. The obtained coated paper was subjected to the above finishing treatment to produce a coated paper for printing. Table 2 shows the evaluation results of the coated paper for printing.

  In Example 2, the same procedure as in Example 2 was performed except that the apparatus for further coating the coating liquid on the coating surface provided by the curtain coater was changed from a blade coater to a shim sizer which is a kind of film transfer coater. went. Table 2 shows the evaluation results of the coated paper for printing.

Without applying calendar treatment to the base paper, the coating solution obtained as described above was applied at a coating speed of 700 m / min with a shim sizer which is a kind of film transfer coater. Both sides were coated simultaneously, and the coating amount per side at this time was 6.0 g / m ² . Further, this is a long nip calender comprising a metal roll heated to 180 ° C. having a hardness of Hs of 84 degrees and a surface roughness of 0.3 S, and a shoe roll having a resin belt having a hardness of 91 ShA and a shoe having a width of 70 mm inside. Using an “Optical Duel Shoe Calendar” (Metso SHI), calendar treatment was performed under calendar pressure conditions of 150 kN / m as shown in Table 1. The long nip calendering process was performed so as to contact the heated metal roll surface of the long nip calender once on each side. Furthermore, on the coated surface subjected to the long nip calendering, the coating liquid obtained as described above was applied with a curtain coater at a coating speed of 700 m / min and a coating amount per side of 6.0 g / m ² . And coated on both sides. The obtained coated paper was subjected to the above finishing treatment to produce a coated paper for printing. Table 2 shows the evaluation results of the coated paper for printing.

  In Example 4, everything was performed in the same manner as in Example 4 except that the apparatus for applying the coating liquid on the base paper subjected to the long nip calendering process was changed from a shim sizer to a blade coater. Table 2 shows the evaluation results of the coated paper for printing.

  In Example 1, all was performed in the same manner as in Example 1 except that the coating speed at the time of coating by the curtain coater was changed to 600 m / min. Table 2 shows the evaluation results of the coated paper for printing.

  In Example 1, all was performed in the same manner as in Example 1 except that the coating speed at the time of coating by the curtain coater was changed to 800 m / min. Table 2 shows the evaluation results of the coated paper for printing.

  In Example 1, all was performed in the same manner as in Example 1 except that the coating speed at the time of coating by the curtain coater was changed to 1000 m / min. Table 2 shows the evaluation results of the coated paper for printing.

  The same procedure as in Example 1 was performed except that the shoe roll used in the long nip calendering process in Example 1 was changed to a shoe roll having a 50 mm wide shoe inside. Table 2 shows the evaluation results of the coated paper for printing.

  In Example 1, everything was carried out in the same manner as in Example 1 except that the calendar pressurizing condition during the long nip calendering process was changed to 100 kN / m. Table 2 shows the evaluation results of the coated paper for printing.

  In Example 1, everything was carried out in the same manner as in Example 1 except that the calendar pressure condition during the long nip calendering process was changed to 200 kN / m. Table 2 shows the evaluation results of the coated paper for printing.

(Comparative Example 1)
The coating liquid obtained as described above was applied to the base paper by a curtain coater at a coating speed of 700 m / min without calendering. One side was coated on both sides, and the coating amount per side at this time was 12.0 g / m ² . The obtained coated paper was subjected to the above finishing treatment to produce a coated paper for printing. Table 2 shows the evaluation results of the coated paper for printing.

(Comparative Example 2)
Without applying calendar treatment to the base paper, the coating solution obtained as described above was applied at a coating speed of 700 m / min with a shim sizer which is a kind of film transfer coater. Both sides were coated simultaneously, and the coating amount per side at this time was 6.0 g / m ² . Further, without applying a calender treatment, the coating solution obtained as described above was coated on both sides of each side with a curtain coater at a coating speed of 700 m / min and a coating amount of 6.0 g / m ² per side. Coated. The obtained coated paper was subjected to the above finishing treatment to produce a coated paper for printing. Table 2 shows the evaluation results of the coated paper for printing.

(Comparative Example 3)
The coating liquid obtained as described above was applied to the base paper by a curtain coater at a coating speed of 700 m / min without calendering. Each side was coated on both sides, and the coating amount per side at this time was 6.0 g / m ² . Further, without applying a calender treatment, the coating solution obtained as described above was coated simultaneously on both sides with a blade coater at a coating speed of 700 m / min and a coating amount of 6.0 g / m ² per side. did. The obtained coated paper was subjected to the above finishing treatment to produce a coated paper for printing. Table 2 shows the evaluation results of the coated paper for printing.

(Comparative Example 4)
In Example 1, instead of the long nip calender, a base paper using a soft calender made of a metal roll heated to 180 ° C. having a hardness of Hs of 84 degrees and a surface roughness of 0.3 S and an elastic roll having a hardness of 90 ShD (manufactured by Elegless). All of the procedures were performed in the same manner as in Example 1 except that the sample was smoothed. The pressurizing condition was 150 kN / m, and the calendering was performed so as to hit the pressed metal roll surface once each on the front and back sides. Table 2 shows the evaluation results of the coated paper for printing.

(Comparative Example 5)
In Comparative Example 4, everything was carried out in the same manner as in Comparative Example 4 except that the pressure condition of the soft calendar was set to 100 kN / m. Table 2 shows the evaluation results of the coated paper for printing.

(Comparative Example 6)
In Example 4, instead of the long nip calender, a soft calender composed of a metal roll heated to 180 ° C. having a hardness of Hs of 84 degrees and a surface roughness of 0.3 S and an elastic roll having a hardness of 90 ShD (manufactured by Elegres) was used. All of the procedures were performed in the same manner as in Example 1 except that the sample was smoothed. The pressurizing condition was 150 kN / m, and the calendering was performed so as to hit the pressed metal roll surface once each on the front and back sides. Table 2 shows the evaluation results of the coated paper for printing.

(Comparative Example 7)
In Comparative Example 6, everything was carried out in the same manner as Comparative Example 6 except that the pressure condition of the soft calendar was set to 100 kN / m. Table 2 shows the evaluation results of the coated paper for printing.

(Comparative Example 8)
In Example 1, the apparatus for coating the coating liquid on the base paper subjected to the long nip calendering process was changed from a curtain coater to a blade coater. Both surfaces were simultaneously coated under the conditions of a coating speed of 700 m / min and a coating amount of 12.0 g / m ² per side. The obtained coated paper was subjected to the above finishing treatment to produce a coated paper for printing. Long nip calendering was performed in the same manner as in Example 1. Table 2 shows the evaluation results of the coated paper for printing.

(Comparative Example 9)
A base paper subjected to long nip calendering under the same conditions as in Example 1 was obtained. The thus obtained long nip calendered base paper was coated with the coating liquid obtained as described above at a coating speed of 700 m / min using a shim sizer which is a kind of film transfer coater. . Both sides were coated simultaneously, and the coating amount per side at this time was 6.0 g / m ² . Further, on this coated surface, the coating liquid obtained as described above was applied by a blade coater at a coating speed of 700 m / min, a coating amount per side of 6.0 g / m ² , under the conditions of simultaneous coating on both sides. Coated. The obtained coated paper was subjected to the above finishing treatment to produce a coated paper for printing. Table 2 shows the evaluation results of the coated paper for printing.

(Comparative Example 10)
Without calendering the base paper, the coating solution obtained as described above was applied at a coating speed of 700 m / min with a blade coater. Both sides were coated simultaneously, and the coating amount per side at this time was 12.0 g / m ² . The obtained coated paper was subjected to the above finishing treatment to produce a coated paper for printing. Table 2 shows the evaluation results of the coated paper for printing.

(Comparative Example 11)
Without applying calendar treatment to the base paper, the coating solution obtained as described above was applied at a coating speed of 700 m / min with a shim sizer which is a kind of film transfer coater. Both sides were coated simultaneously, and the coating amount per side at this time was 6.0 g / m ² . Further, without applying a calender treatment, the coating solution obtained as described above was coated simultaneously on both sides with a blade coater at a coating speed of 700 m / min and a coating amount of 6.0 g / m ² per side. did. The obtained coated paper was subjected to the above finishing treatment to produce a coated paper for printing. Table 2 shows the evaluation results of the coated paper for printing.

(Comparative Example 12)
Without calendering the base paper, the coating solution obtained as described above was applied at a coating speed of 700 m / min with a blade coater. Both sides were coated simultaneously, and the coating amount per side at this time was 6.0 g / m ² . Further, without applying a calender treatment, the coating solution obtained as described above was coated simultaneously on both sides with a blade coater at a coating speed of 700 m / min and a coating amount of 6.0 g / m ² per side. did. The obtained coated paper was subjected to the above finishing treatment to produce a coated paper for printing. Table 2 shows the evaluation results of the coated paper for printing.

(Comparative Example 13)
In Comparative Example 1, everything was carried out in the same manner as Comparative Example 1 except that the coating speed at the time of coating with the curtain coater was changed to 600 m / min. Table 2 shows the evaluation results of the coated paper for printing.

  Table 1 shows the conditions of Examples 1 to 11 and Comparative Examples 1 to 13.

  Table 2 shows the evaluation results of Examples 1 to 11 and Comparative Examples 1 to 13.

  As is apparent from the results in Table 2, in the coated paper for printing in which one or more coating layers are provided on at least one side of the base paper, at least one of the coating layers is provided by the curtain coating method. The coating layer provided by the curtain coating method is provided in contact with the surface smoothed by a long nip calender processing device comprising a heated metal roll and a shoe roll. With this feature, it is possible to provide a coated paper for printing that has low density, high gloss, excellent printing surface quality, and can be produced with high productivity without pinhole coating unevenness.

Schematic of long nip calender device Schematic diagram of soft calendar device

Explanation of symbols

1 and 8 Heated metal roll 2 Resin belt 3 Shoe 4 Shoe roll 5 Base paper 6 Oil for lubrication 7 Pressure cylinder 9 Soft calender roll 10 Roll cover resin

Claims (2)

,
A printing coated paper having at least one coating layer provided on at least one side of a base paper, wherein at least one of the coating layers is provided by a curtain coating method, and curtain coating A coating paper for printing, characterized in that the coating layer provided by the method is provided in contact with the surface smoothed by a long nip calender processing device comprising a heated metal roll and a shoe roll . The coated paper for printing according to claim 1, wherein the density is 0.67 to 1.20 g / cm ³ .

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