JP2009035825A - Coated paper for printing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide coated paper for printing, which has high surface strength, inner bond strength and opacity in spite of having a low density, and is excellent in printing suitability. <P>SOLUTION: The coated paper for printing, prepared by disposing one or more layers consists mainly of a pigment and an adhesive on at least one side of base paper, wherein the base paper contains amorphous silica particles or amorphous silicate particles having a fine pore surface area of 15 to 200 m<SP>2</SP>/g and an average fine pore diameter of 0.10 to 0.80 μm in an amount of 1 to 30 mass% as the amount of filler in the paper, and the outermost layer of the coating layers is a layer containing kaolin having an average particle diameter of 1.0 μm or less measured by a precipitation method. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a coated paper for printing, and particularly to a coated paper for low density printing having excellent surface strength, internal bond strength, printability and opacity.

  In general, coated paper for printing is manufactured by applying and drying a coating liquid mainly composed of pigment and adhesive on a base paper, and depending on the coating amount of the coating liquid and the finishing method of the coated paper, It is classified into paper, art paper, coated paper, finely coated paper and the like. These coated papers are subjected to multicolor printing or single color printing, and are widely used as commercial printed materials such as flyers, brochures and posters, or as publications such as books and magazines.

In recent years, the visualization and colorization of printed materials has progressed, and the demand for higher quality of coated paper for printing has increased. In the printing finish such as white paper quality such as white paper glossiness, smoothness, whiteness, and printing gloss. Quality such as appearance is regarded as important.
On the other hand, weight reduction of the coated paper for printing is required from the viewpoint of resource saving, transportation cost, etc. In order to reduce the weight, it is necessary to lower the base weight of the base paper and the coating weight of the coating layer. .

  Currently, as a method for reducing the weight of coated paper, a method is known in which the press pressure and machine calender pressure during base paper making are lowered to lower the density of the base paper. However, when the density of the base paper is lowered to a desired level only by this method, there is a problem that the smoothness of the base paper is remarkably lowered, and as a result, the smoothness of the coated paper is also lowered.

  Moreover, as a method of improving surface strength and printability and reducing the weight, a method of blending amorphous silica or amorphous silicate into paper (see Patent Document 1), a mechanical pulp is blended with the pulp used, and a filler Methods for blending amorphous silica (Patent Documents 2, 3, and 4), methods for blending amorphous silica or amorphous silicate with a bulking agent (see Patent Document 5), and the like have been proposed.

  However, in the combination of normal amorphous silica or amorphous silicate, or in combination with a bulking agent, amorphous silica particles, amorphous silicate particles, and bulking agent are mixed with pulp and conveyed in each step. Not only can the bulk density effect be crushed due to the market share, the press pressure and machine calender pressure during base paper making, and the target low density cannot be achieved, but also the surface strength of the coated paper and the interior of the base paper There was a problem of reducing the bond strength. In addition, when the regular amorphous silica or amorphous silicate is blended, the water resistance of the paper surface is remarkably lowered, so a surface treating agent blended with a water resistant agent is used. The coated paper has a problem that the disintegration property is deteriorated and the recyclability is inferior.

  In order to reduce the density of the coating layer and contribute to the reduction in the density of the entire coated paper, a method of treating the coated paper with a soft nip calender at 150 ° C. or higher has also been proposed. In the treatment, smoothness only on the surface is expressed, but there is a problem that the target smoothness cannot be expressed in a state where pressure is applied at the time of printing and printability is inferior. In addition, mechanical pulp that is easy to express bulkiness is also added, but mechanical pulp is highly rigid, so in addition to reducing the smoothness of the coated paper, the whiteness of the base paper is inferior There's a problem.

Further, as a method for improving opacity and printability, weight reduction, opacity improvement, strength and stiffness reduction, as well as a method of blending amorphous silica and / or amorphous silicate with paper, calcium carbonate A method of blending a composite filler composed of inorganic particles such as titanium dioxide, magnesium carbonate, barium sulfate and silicic acid and / or silicate into paper has been proposed (Patent Documents 6, 7, 8, 9, 10, 11). , 12, 15, 16, 17, 18, 19).
However, even in the case of composite fillers composed of inorganic particles and silicic acid and / or silicate, the target density reduction and surface strength are destroyed by various shares during base paper making, press pressure and machine calendar pressure, etc. In addition, it was impossible to achieve both the internal bond strength and the coated paper with good printability.

  In addition, as a method of reducing the weight by using a plate-like pigment and improving the coverage of the base paper with a low coating amount, 100 parts by mass of a delaminated clay having a volume distribution average particle size of 3.5 to 20 μm is used. As a method of applying a coating layer containing 30 to 90 parts by mass (see Patent Document 13), reducing the weight of the coating layer, and reducing the weight by suppressing crushing of the base paper due to calendar processing, A method of using synthetic resin particles having a low specific gravity and a high gloss (see Patent Document 14) has also been proposed, but to achieve both satisfactory printability and target weight reduction sufficiently Not reached.

Japanese Patent Laid-Open No. 10-226982 Japanese Patent Laid-Open No. 11-279988 JP 2000-345493 A JP 2001-214395 A JP 2000-282392 A JP-A-60-72963 JP-A-11-107189 JP 2001-247310 A JP 2003-020592 A JP 2006-070413 A JP 2006-97138 A JP 2006-97162 A JP 2002-194698 A JP 7-238493 A JP-A-5-178606 JP 60-065713 A JP 61-141767 A Japanese Patent Publication No.49-36877 Japanese Patent Publication No. 52-28754

As described above, the conventional methods as described in Patent Documents 1 to 19 have high surface strength, internal bond strength and opacity, and excellent printability, despite the low density. It was difficult to obtain paper.
The present invention has been made in view of the above circumstances, and provides a coated paper for printing that has high surface strength, high internal bond strength, and high opacity, and excellent printability despite its low density. With the goal.

  The present invention is selected from the invention specified by the following technical matters.

(1) A coated paper for printing in which at least one surface of a base paper is provided with one or more coating layers mainly composed of a pigment and an adhesive, and the base paper has a pore surface area of 15 to 200 m ² / g. In addition, amorphous silica particles or amorphous silicate particles having an average pore diameter of 0.10 to 0.80 μm are contained in an amount of 1 to 30% by mass as a filler content in the paper, and the outermost layer of the coating layer is precipitated. A coated paper for printing, which is a layer containing kaolin having an average particle diameter measured by a method of 1.0 μm or less.

(2) The base paper has a pore surface area of 15 to 150 m ² / g, preferably 15 to 100 m ² / g, and an average pore diameter of 0.15 to 0.80 μm, preferably 0.20 to 0. Amorphous silica particles or amorphous silicate particles of 80 μm are contained as a filler content in the paper in the range of 1 to 30% by mass, preferably 2.0 to 15% by mass, and the outermost layer of the coating layer is measured by a sedimentation method. The coated paper for printing according to (1), which is a layer containing kaolin having an average particle size of 1.0 μm or less, preferably 0.8 μm or less, more preferably 0.5 μm or less.

(3) Item (1) or (2), wherein the amorphous silica particles or amorphous silicate particles are particles having a pore volume of less than 4.0 ml / g, preferably less than 3.0 ml / g. The coated paper for printing as described in the item).

(4) Items (1) to (3), wherein the average particle size of the amorphous silica particles or the amorphous silicate particles is 40 μm or less, preferably 3 to 30 μm or less, more preferably 5 to 25 μm or less. The coated paper for printing according to any one of the above.

(5) The outermost layer of the coating layer has an average particle size measured by a precipitation method of 1.0 μm or less, preferably 0.8 μm or less, more preferably 0.5 μm or less, and further preferably 0.35 μm or less. The printing coating according to any one of (1) to (4), wherein kaolin is a layer containing 10% by mass or more and less than 50% by mass in the total inorganic pigment in the outermost layer. Paper.

(6) The outermost layer of the coating layer includes, in addition to the kaolin, heavy calcium carbonate, light calcium carbonate, satin white, calcium sulfite, gypsum, barium sulfate, talc, clay, white carbon, diatomaceous earth, magnesium carbonate, It is a layer containing one or more inorganic pigments selected from titanium dioxide, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, zinc oxide, magnesium oxide, bendnite, sericite and the like. The coated paper for printing according to any one of items (1) to (5), wherein:

(7) The coated paper for printing according to any one of items (1) to (6), wherein the outermost layer of the coating layer is a layer containing a resin pigment.

(8) The printing coating according to any one of (1) to (7), wherein the base paper is a base paper having a basis weight of 30 to 300 g / m ² , preferably 30 to 130 g / m ^2. paper.

(9) The adhesive in the coating layer is one or more selected from a water-dispersible adhesive and a water-soluble adhesive, and any one of (1) to (8) Coated paper for printing according to item.

(10) The coated paper for printing according to any one of items (1) to (9), wherein the coating layer is a layer having a thickness of 5 to 50 μm, preferably 8 to 30 μm.

(11) The base paper is preliminarily coated with two roll size press coaters, gate roll coaters, premetering size press coaters, etc. on the surface on which the coating layer mainly composed of the pigment and the adhesive is formed. Any one of (1) to (10), characterized in that the coating liquid containing at least one selected from starch and polyvinyl alcohol is pre-coated by an apparatus. Coated paper for printing.

(12) The printing coating material according to any one of items (1) to (11), wherein the coated paper for printing is subjected to pressure finishing with a machine calendar and / or a super calender. Paper.

  The coated paper of the present invention has high surface strength, internal bond strength and opacity despite its low density, and is excellent in printability. It is suitable for use as a commercial printed matter such as a pamphlet or a poster, or as a publication such as a book or a magazine.

(Coated paper)
The coated paper of the present invention has at least one coated layer mainly composed of a pigment and an adhesive on at least one side of a base paper.

  As pulp components constituting the base paper of the coated paper, chemical pulp such as softwood bleached kraft pulp (NBKP), hardwood bleached kraft pulp (LBKP), sulfite pulp (SP), groundwood pulp (GP), stone ground pulp ( SG), Pressurized Stone Grand Pulp (PGP), Thermo Mechanical Pulp (TMP), Chemi Thermo Mechanical Pulp (CTMP), Refiner Grand Pulp (RGP), Refiner Mechanical Pulp (RMP), Semi Chemical Pulp (SCP), etc. Used paper pulp, and used paper pulp (DIP) made from various used paper as raw materials. The freeness of the pulp component is preferably 200 to 580 CSF from the viewpoint of the balance between strength and stiffness in the base paper.

The amorphous silica particles or amorphous silicate particles contained in the base paper of the coated paper have a pore surface area of 15 to 200 m ² / g and a pore diameter of 0.10 to 0.8 μm.
The pore surface area is preferably 15 to 150 m ² / g and the pore diameter is preferably 0.15 to 0.8 μm, the pore surface area is 15 to 100 m ² / g and the pore diameter is 0.20 to 0. More preferably, the pore surface area is 15 to 75 m ² / g, and the pore diameter is further preferably 0.25 to 0.8 μm.
Here, amorphous silica or amorphous silicate is a compound represented by the general formula xM ₂ O · ySiO ₂ , xMO · ySiO ₂ , xM ₂ O ₃ · ySiO ₂ , where M is Al, Fe, Ca. , Mg, Na, K, Ti, Zn (x and y are arbitrary positive numerical values).

When the pore surface area is less than 15 m ² / g, the particle size distribution becomes poor, the fine particles and coarse particles increase, and the surface strength and internal bond strength of the base paper decrease. In addition, the surface of the base paper is roughened by coarse particles, and a strong smoothing treatment is required to develop the desired surface smoothness, resulting in insufficient bulkiness. Further, the smoothness in a state where pressure is applied during printing is also deteriorated, and the printability is also lowered.
If it exceeds 200 m ² / g, the cohesive strength of the aggregated structure will be weak, it will be easily crushed by the shearing force, press pressure, and calendering pressure during pulp slurry preparation, and the bulkiness of the base paper will be insufficient, and the surface strength will also be high descend. Furthermore, the opacity of the base paper is also reduced.

If the pore diameter is less than 0.08 μm, the cohesive strength of the aggregated structure will be weak, it will be easily crushed by the shearing force, press pressure, and calendar treatment pressure during pulp slurry preparation, and the bulkiness of the base paper will be insufficient. In addition, the surface strength also decreases. Further, the opacity when blended with the base paper is lowered.
When it exceeds 0.8 μm, the particle size distribution is deteriorated, and fine particles and coarse particles are increased, and the internal strength and the surface strength are lowered. Further, the surface of the base paper is roughened by coarse particles, and a strong smoothing treatment is required to develop the desired surface smoothness, resulting in insufficient bulkiness. Further, the smoothness in a state where pressure is applied during printing is also deteriorated, and the printability is also lowered.

The amorphous silica or amorphous silicate contained in the base paper of the coated paper preferably has a pore volume of less than 4.0 ml / g, more preferably less than 3.0 ml / g. When the pore volume is less than 4.0 ml / g, the cohesive strength of the aggregates can be increased, and crushing at various shares can be prevented, and the bulk effect is enhanced.
Here, the specific surface area is the surface area of all the pores assuming that the pore shape is a geometric cylinder using a pore sizer 9320 (manufactured by Shimadzu Corporation), and is pressed into the pressure within the measurement range. It is the value obtained from the relationship of the amount of mercury.
The pore diameter is a median pore diameter obtained from an integral specific surface area curve using a pore sizer 9320 (manufactured by Shimadzu Corporation). The pore volume is also a value when measured by a mercury intrusion method using a pore sizer 9320 (manufactured by Shimadzu Corporation) and integrated with a pore diameter of 0.01 to 10 μm.

  The amorphous silica or amorphous silicate has a specific surface area and pore diameter within a specific range, so that when added to paper, the decrease in internal bond strength and surface strength is small. Even if the surface treatment is performed, the base paper layer is not easily crushed, the bulkiness is maintained, and a base paper having good smoothness can be formed. In addition, because it has a good particle size distribution and few amorphous silicas or amorphous silicates with different particle sizes, it has good smoothness with no unevenness even under pressure applied during printing, so it has excellent printability. Is.

  Amorphous silica or amorphous silicate needs to contain 1 to 30% by mass as a filler content in the paper, and preferably 2.0 to 15% by mass. If the amount is less than 1% by mass, the above-described effects cannot be exhibited, and the desired low density and surface smoothness are not sufficiently exhibited. On the other hand, when it exceeds 30% by mass, the surface strength and the internal bond strength are insufficient.

The internal bond strength of the base paper formed by containing particles of amorphous silica or amorphous silicate is preferably 500 J / m ² or more, and more preferably 600 J / m ² or more. More preferably, it is 700 J / m ² or more.

The amorphous silica or amorphous silicate particles preferably have an average particle size of 40 μm or less, more preferably 3 to 30 μm, and even more preferably 5 to 25 μm. When the average particle diameter of the amorphous silica particles or amorphous silicate particles exceeds 40 μm, the surface strength is lowered and the surface smoothness is also lowered. Processing is required, resulting in reduced bulkiness. Also, printability and blank paper opacity are reduced.
In addition, the average particle diameter in the present invention is a value that is measured by a laser diffraction method using SALD2000J (manufactured by Shimadzu Corporation) and is 50% in volume integration. As the particle size distribution of amorphous silica or amorphous silicate, the standard deviation (σ) is preferably 0.450 or less, more preferably 0.400 or less. With such a particle size distribution, both the coarse particles and the fine particles are reduced, and more excellent internal bond strength and surface strength can be obtained, and good surface smoothness can be obtained. In addition, it has excellent smoothness with no unevenness particularly in a state where pressure is applied during printing, and therefore has excellent printability.

  The amorphous silica or amorphous silicate particles are produced by adding a mineral acid solution and / or a metal salt solution of a mineral acid to an aqueous alkali silicate solution, and neutralizing the alkaline silicate aqueous solution to contain silicon. There is a method of depositing particles in the presence of a certain electrolyte.

Here, the alkali silicate aqueous solution is not particularly limited, but a sodium silicate aqueous solution or a potassium silicate aqueous solution is preferable. The concentration of the alkali silicate aqueous solution is preferably 3 to 15% because amorphous silica or amorphous silicate can be efficiently produced. When the alkali silicate aqueous solution is a sodium silicate aqueous solution, SiO ₂ / it is preferable Na ₂ O molar ratio of 2.0 to 3.4.

  In the mineral acid solution and / or metal salt solution of mineral acid used for the production of amorphous silica or amorphous silicate particles, examples of the mineral acid used include hydrochloric acid, sulfuric acid, nitric acid, and the like. Examples of the metal salt include sodium salts, potassium salts, calcium salts, and aluminum salts of the mineral acids. Among these, sulfuric acid and aluminum sulfate are preferable from the viewpoint of cost and handling, and an aqueous solution is preferable.

The base paper constituting the coated paper of the present invention is, for example, the above-mentioned amorphous silica particles or amorphous silicate particles, and, if necessary, a paper strength enhancer, a sizing agent, and a fixing agent in a pulp slurry containing a beaten pulp component. It is obtained by preparing a paper stock by adding an agent, an antifoaming agent, a colorant and the like, and making the paper stock.
As the papermaking method, for example, a long wire machine, a round wire machine, a twin wire machine including a gap former and a hybrid former, a machine using these together, a Yankee dryer machine, etc., acid papermaking, neutral papermaking, or Examples include alkaline paper making.

Further, when obtaining the base paper, it is preferable to appropriately adjust the press pressure in the dehydration step and the machine calendar pressure in the smoothing step so as to obtain the desired smoothness and bulkiness of the coated paper.
For the base paper, in order to adjust the papermaking suitability and strength characteristics of the base paper, other fillers other than the above-mentioned amorphous silica or amorphous silicate particles, for example, talc, kaolin, heavy calcium carbonate, light calcium carbonate, titanium oxide Etc. may be included.

The basis weight of the base paper constituting the coated paper of the present invention is preferably 30~300g / ^{m 2,} and more preferably 30~130g / ^{m 2.}

The coating layer constituting the coated paper of the present invention contains a pigment and an adhesive, and the outermost layer contains kaolin having an average particle diameter measured by a precipitation method of 1.0 μm or less.
The average particle size of kaolin is preferably 0.8 μm or less, and more preferably 0.5 μm or less. If it is 0.35 micrometer or less, it is still more preferable. By containing kaolin having an average particle size of 1.0 μm or less in the outermost layer, it is excellent in the pressure dispersion effect on the particles of the specific amorphous silica or amorphous silicate that is internally added to the base paper during the smoothing treatment, The amorphous silica or amorphous silicate particles can be prevented from being crushed, and the bulkiness effect and smoothness development effect are excellent, and the opacity and printability are also improved.

  If the average particle diameter of kaolin exceeds 1.0 μm, the effect of pressure dispersion on the particles of the specific amorphous silica or amorphous silicate that is internally added to the base paper during the smoothing treatment is reduced, and the desired smoothing is achieved. Therefore, it is necessary to strengthen the smoothing treatment for expressing the properties, and as a result, the bulkiness of the base paper becomes insufficient, and the internal bond strength and the surface strength are also lowered. Also, the coated paper in a state where the specific amorphous silica or amorphous silicate particles contained in the base paper are crushed due to the strong smoothing treatment and the generated fine particles are applied with pressure during printing. The smoothness of the ink is inferior and the printability is lowered.

  The content of kaolin having an average particle diameter of 1.0 μm or less in the outermost layer is preferably 10% by mass or more and less than 50% by mass in all inorganic pigments in order to develop blank paper opacity and bulk effect. In addition, when a coating layer is one layer, the coating layer becomes the outermost layer.

Examples of other inorganic pigments when the outermost layer contains an inorganic pigment other than the kaolin component include, for example, heavy calcium carbonate, light calcium carbonate, satin white, calcium sulfite, gypsum, barium sulfate, talc, clay, Examples thereof include white carbon, diatomaceous earth, magnesium carbonate, titanium dioxide, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, zinc oxide, magnesium oxide, bendnite, and sericite. These other inorganic pigments may be used alone or in combination of two or more.
The other inorganic pigments preferably have an average particle size of 0.2 to 1.5 μm, more preferably 0.2 to 1.0 μm, measured by a sedimentation method. If the average particle size of other inorganic pigments is 0.2 μm or more, the smoothness of the coating layer can be further increased, and if the average particle size is 1.5 μm or less, an excessive decrease in white paper glossiness can be prevented. .

  The coating layer constituting the coated paper of the present invention may contain a resin pigment. The resin pigment may be hollow or solid particles, may be a particle having a through hole, or may be a bowl-shaped particle.

  Examples of the resin constituting the resin pigment include styrene polymers obtained by polymerizing styrene monomers such as styrene and α-methylstyrene, methyl (meth) acrylate, ethyl (meth) acrylate, and (meth) acrylic. (Meth) acrylic acid alkyl ester polymer obtained by polymerizing (meth) acrylic acid alkyl ester monomers such as butyl acid and (meth) acrylonitrile, (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, etc. Examples thereof include unsaturated carboxylic acid polymers obtained by polymerizing saturated carboxylic acid monomers, and unsaturated amide polymers obtained by polymerizing unsaturated amide monomers such as (meth) acrylamide. In addition, a copolymer obtained by copolymerizing at least one selected from the group consisting of the above aromatic vinyl monomers, acrylic acid alkyl ester monomers, unsaturated carboxylic acid monomers, and unsaturated amide monomers ( For example, a styrene- (meth) acrylic acid ester copolymer) may be used. When such a resin pigment is contained, the density of the coating layer becomes lower, which is preferable.

The average particle size of the resin pigment is preferably 0.5 to 1.5 μm. If the average particle diameter of the resin pigment is 0.5 μm or more, the opacity can be further improved, and if it is 1.5 μm or less, the surface smoothness can be further improved.
Further, the resin pigment is preferably hollow particles having an average particle diameter in the above range and a porosity of 30 to 60%.

When there are two or more coating layers, the above-described kaolin component may also be included in the coating layer (undercoat coating layer) between the coating layer serving as the outermost layer and the base paper.
Further, the outermost coating layer and the undercoat coating layer may be formed of a coating liquid having the same composition, or may be formed of coating liquids having different compositions. When two or more coating layers are provided, the smoothness of the coated paper tends to be higher.

As an adhesive contained in the coating layer, for example, a water-dispersible adhesive or a water-soluble adhesive can be used.
Examples of water-dispersible adhesives include styrene / butadiene copolymers, styrene / acrylic copolymers, ethylene / vinyl acetate copolymers, butadiene / methyl methacrylate copolymers, and vinyl acetate / butyl acrylate copolymers. A copolymer etc. are mentioned.
Examples of water-soluble adhesives include, for example, synthetic adhesives such as polyvinyl alcohol, maleic anhydride copolymer, acrylic acid / methyl methacrylate copolymer; proteins such as casein, soy protein, synthetic protein; oxidized starch, positive Examples include starch, etherified starch such as urea phosphate esterified starch and hydroxyethyl etherified starch, and starches such as dextrin; cellulose derivatives such as carboxymethyl cellulose, hydroxymethyl cellulose, and hydroxyethyl cellulose. These adhesives may be used alone or in combination of two or more.

  The adhesive content in the coating layer is preferably 5 to 50 parts by mass, more preferably 7 to 30 parts by mass with respect to 100 parts by mass of the pigment.

  The total thickness of the coating layer is preferably 5 to 50 μm, and more preferably 8 to 30 μm. If the total thickness of the coating layer is 5 μm or more, ink receptivity can be sufficiently exhibited. Moreover, if the total thickness of the coating layer is 50 μm or less, flexibility can be maintained, the texture as paper can be prevented from being impaired, and the surface state of the base paper can be easily applied to the surface of the coating layer. Will be reflected.

The coating liquid applied to the base paper contains the above-described pigment and adhesive. The pigment and the adhesive are prepared, for example, by dispersing and mixing in an aqueous medium. In the coating solution, various auxiliary agents such as a dispersant, a thickener, a water retention agent, an antifoaming agent, a water resistance agent, and a coloring agent may be added as necessary.
The coating amount of the coating liquid is selected according to the target quality of the coated paper. Taking the case where the basis weight of the base paper is 40 g / m ² as an example, if the dry coating amount per side is about 5 to 20 g / m ² , sufficient coverage, desired smoothness and printability are obtained. be able to.

Examples of the coating apparatus for coating the base paper with the coating liquid include various size press machines and roll coaters such as gate rolls, shim sizers and size press coaters, blade coaters, bar coaters, rod coaters, air knife coaters, curtain coaters. And reverse roll coater.
Examples of the drying device for drying the coating liquid include various types of dryers such as a heating cylinder, a heated hot air air dryer, a gas heater dryer, an electric heater dryer, an infrared heater dryer, and the like, and these may be used alone or in combination. Can do.

  The base paper may be preliminarily coated with starch, polyvinyl alcohol, or the like before applying the coating solution. Examples of the preliminary coating apparatus include a two-roll size press coater, a gate roll coater, and a pre-metering size press coater.

  Examples of the pressure finishing process include a machine calendar process such as a chilled calendar and a soft nip calendar, a super calendar process, and the like.

  In the method for producing a coated paper of the present invention, as a base paper, a coating liquid is applied to at least one surface of a base paper containing the above-mentioned specific amorphous silica particles or amorphous silicate particles in a specific range amount, This is a method for obtaining a coated paper containing the above-mentioned specific inorganic pigment in the outermost layer. As described above, the specific amorphous silica particles or amorphous silicate particles contained in the base paper are not easily crushed even when pressure is applied, and exhibit uniform and good smoothness in a state where pressure is applied during printing. In addition, the pressure during the smoothing process can be uniformly transmitted from the coating layer to the base paper, and a uniform smoothing process without unevenness is possible.

Furthermore, by adding the above-mentioned specific pigment, it is possible to impart bulkiness to the coating layer, and it is possible to uniformly convey the pressure during the smoothing process or printing in both the base paper and the coating layer. As a result, it is possible to prevent the breakage of specific amorphous silica or amorphous silicate particles internally added to the base paper, and it is possible to produce a coated paper having an excellent bulk effect and excellent surface strength and internal bond strength.
According to the above production method, it is possible to provide a coated paper having high printability and excellent surface strength and internal bond strength despite its low density.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the following examples, “parts” and “%” mean “parts by mass” and “mass%”, respectively, unless otherwise specified.
Moreover, in the amorphous silica or amorphous silicate used in the following examples, the specific surface area, pore diameter, pore volume, and average particle diameter were measured as follows.

(Specific surface area)
The specific surface area is the surface area of all pores when the pore shape is assumed to be a geometric cylinder using a pore sizer Pore Sizer 9320 (manufactured by Shimadzu Corporation), and the pressure within the measurement range. And the value obtained from the relationship between the amount of injected mercury.
(Pore diameter)
The pore diameter is a median pore diameter measured using a pore sizer 9320 (manufactured by Shimadzu Corporation).

(Pore volume)
The pore volume is a value when measured by a mercury intrusion method using a pore sizer 9320 (manufactured by Shimadzu Corporation) and integrated with a pore diameter of 0.01 to 10 μm.
(Average particle size)
The average particle diameter is a particle diameter of 50% volume integrated value measured using a laser diffraction particle size distribution analyzer “SALD2000J” (manufactured by Shimadzu Corporation). The standard deviation of the particle diameter is a value calculated from the particle diameter obtained by a laser diffraction particle size distribution meter.

Moreover, the average particle diameter of the pigment which comprises a coating layer was measured as follows.
(Measurement of average particle size of pigment by sedimentation method)
The average particle diameter of the pigment by the precipitation method was measured as an average particle diameter of 50 cumulative mass% using Sedygraph 5100 (manufactured by Micrometrics) using a pigment dispersion containing the pigment as a measurement sample.
The pigment dispersion used for the measurement was a pigment slurry obtained by adding 0.05% of a dispersant (sodium polyacrylate) to 100% of the pigment, and 0% of the phosphate dispersant (nancarin). It was prepared by diluting with a 1% aqueous solution so that the pigment solid content concentration was about 1%.

Example 1
(Preparation of coated paper for printing)
In a pulp slurry prepared by mixing 70 parts of hardwood kraft pulp beaten with DDR (Double Disk Refiner) and adjusted to 380 ml of CSF and 30 parts of softwood kraft pulp beaten with DDR and adjusted to 400 ml of CSF, 1.0 part starch (trade name) : Ace K, manufactured by Oji Constarch Co., Ltd.), 0.5 part of sulfuric acid band, 0.03 part of alkyl ketene dimer (trade name: SKS296, manufactured by Arakawa Chemical Industries), 0.1% polyacrylamide (trade name: PS1250 Manufactured by Arakawa Chemical Industries, Ltd.), 6.0 parts of the following synthetic amorphous silica A, 3.0 parts of light calcium carbonate (average particle size 6.1 μm), 0.03 part of yield improver (trade name: DR-1500, Made by Hymo Co., Ltd., made with a hybrid former, and starch is applied on both sides with a size press coater. It applied so that the coating amount is 1.5 g / m ^2, dried and further, so that the dry mass per one surface below coated layer for coated liquid A onto the coated layer is 8 g / m ² The outermost coating layer was provided by coating both sides using a blade coater and drying. Next, the paper was smoothed with a smoothing machine (soft nip calender) installed in the paper machine so that the glossiness of the blank paper was 62%, and a coated paper for printing having a paper thickness of 50 μm was produced. The basis weight was 49.0 g / m ² .

(Production of amorphous silica A)
460 parts by weight of water, aqueous sodium 524 parts of sulfuric acid of a concentration of 6%, were successively added with stirring Si0 ₂ concentration 28.8wt / wt% / Na ₂ O concentration 9.5 wt / wt% of sodium silicate 417 parts, temperature Was adjusted to 55 ° C. Next, 94 parts of 20% sulfuric acid was added while stirring at a temperature of 55 ° C. to neutralize the first stage, and then the temperature was raised to 85 ° C. Was added with stirring until pH 5.7, and the second stage neutralization was performed. Next, the slurry prepared as described above was separated and filtered with a 200 mesh sieve to obtain an amorphous silica slurry.
Table 1 shows the average particle diameter and standard deviation of the amorphous silica of the amorphous silica slurry. Further, a part of the cake after filtration and washing was dried at 105 ° C. and subjected to a specific surface area, a pore diameter and a pore volume. Table 1 shows the specific surface area, pore diameter, and pore volume of amorphous silica.

(Preparation of coating solution A for coating layer)
As a pigment, kaolin (trade name: Milagros J, manufactured by BASF Corp.) 45% having an average particle size of 0.25 μm, heavy calcium carbonate having an average particle size of 0.8 μm (trade name: Hydrocurve 90, manufactured by Bihoku Flour Industries Co., Ltd.) ) Oxidized starch (trade name: Oji) with respect to 100 parts of pigment in a slurry of a pigment mixture comprising 15% and 40% light calcium carbonate (trade name: TP123CS, manufactured by Okutama Kogyo Co., Ltd.) having an average particle size of 0.45 μm Ace B, supra) 3.0 parts, styrene-butadiene copolymer latex (trade name: Smartex PA2323, particle size: 89 nm, manufactured by Nippon A & L Co., Ltd.) (all in terms of solid content), resin pigment (product) Name: Lopaque HP91, average particle size: 1 μm, porosity: 55%, manufactured by Rohm and Haas) 2.5 parts and auxiliary agents such as antifoaming agent and dye And finally solid concentration was prepared 59% of the coated liquid.

Example 2
A coated paper for printing was prepared in the same manner as in Example 1 except that the following amorphous silica B was used, smoothed so that the glossiness of the blank paper was 62%, adjusted to a paper thickness of 50 μm, and paper was made. Manufactured. The basis weight was 50.5 g / m ² .

(Production of amorphous silica B)
546 parts by weight of water, a concentration of 6% 741% sulfuric acid aqueous sodium successively added with stirring Si0 ₂ concentration 28.8wt / wt% / Na ₂ O concentration 9.5 wt / wt% of sodium silicate 417 parts, temperature Was adjusted to 55 ° C. Next, 94 parts of 20% sulfuric acid was added while stirring at a temperature of 55 ° C. to neutralize the first stage, and then the temperature was raised to 85 ° C. Was added with stirring until pH 5.7, and the second stage neutralization was performed. Next, the slurry obtained above was separated and filtered with a 200 mesh sieve to obtain an amorphous silica slurry.
Table 1 shows the average particle diameter and standard deviation of the amorphous silica of the amorphous silica slurry. Further, a part of the cake after filtration and washing was dried at 105 ° C. and subjected to a specific surface area, a pore diameter and a pore volume. Table 1 shows the specific surface area, pore diameter, and pore volume of amorphous silica.

Example 3
A coated paper for printing was prepared in the same manner as in Example 1 except that the following amorphous silica C was used, smoothed so that the glossiness of blank paper was 62%, adjusted to a paper thickness of 50 μm, and paper was made. Manufactured. The basis weight was 52.0 g / m ² .

(Production of amorphous silica C)
597 parts of water, 870 parts of aqueous solution of sodium sulfate concentration of 6%, were successively added with stirring Si0 ₂ concentration 28.8wt / wt% / Na ₂ O concentration 9.5 wt / wt% of sodium silicate 417 parts, the temperature Adjusted to 55 ° C. Next, 94 parts of 20% sulfuric acid was added while stirring at a temperature of 55 ° C. to neutralize the first stage, and then the temperature was raised to 85 ° C. Was added with stirring until pH 5.7, and the second stage neutralization was performed. Next, the slurry obtained above was separated and filtered with a 200 mesh sieve to obtain an amorphous silica slurry.
Table 1 shows the average particle diameter and standard deviation of the amorphous silica of the amorphous silica slurry. Further, a part of the cake after filtration and washing was dried at 105 ° C. and subjected to a specific surface area, a pore diameter and a pore volume. Table 1 shows the specific surface area, pore diameter, and pore volume of amorphous silica.

Example 4
A coated paper for printing was prepared in the same manner as in Example 1 except that the following amorphous silica D was used, smoothed so that the glossiness of the blank paper was 62%, adjusted to a paper thickness of 50 μm, and paper was made. Manufactured. The basis weight was 53.0 g / m ² .

(Production of amorphous silica D)
697 parts of water, aqueous sodium 374 parts of sulfuric acid of a concentration of 6%, were successively added with stirring Si0 ₂ concentration 28.8wt / wt% / Na ₂ O concentration 9.5 wt / wt% of sodium silicate 417 parts, the temperature Adjusted to 55 ° C. Next, 109.5 parts of 20% sulfuric acid was added while stirring at a temperature of 55 ° C. to neutralize the first stage, then the temperature was raised to 85 ° C., and the 20% concentration was maintained at this temperature. Of sulfuric acid was added with stirring until pH 5.7, and the second neutralization was performed. Next, the slurry obtained above was separated and filtered with a 200 mesh sieve to obtain an amorphous silica slurry.
Table 1 shows the average particle diameter and standard deviation of the amorphous silica of the amorphous silica slurry. Further, a part of the cake after filtration and washing was dried at 105 ° C. and subjected to a specific surface area, a pore diameter and a pore volume. Table 1 shows the specific surface area, pore diameter, and pore volume of amorphous silica.

Example 5
A coated paper for printing was prepared in the same manner as in Example 1 except that the following amorphous silica E was used, smoothed so that the glossiness of the blank paper was 62%, adjusted so that the paper thickness was 50 μm, and made paper. Manufactured. The basis weight was 54.0 g / m ² .

(Production of amorphous silica E)
617 parts of water, aqueous sodium 315 parts of sulfuric acid of a concentration of 6%, were successively added with stirring Si0 ₂ concentration 28.8wt / wt% / Na ₂ O concentration 9.5 wt / wt% of sodium silicate 417 parts, the temperature Adjusted to 55 ° C. Next, 119 parts of 20% strength sulfuric acid was added while stirring at a temperature of 55 ° C. to neutralize the first stage, then the temperature was raised to 85 ° C., and at this temperature, 20% strength sulfuric acid was added. Was added with stirring until pH 5.7, and the second stage neutralization was performed. Next, the slurry obtained above was separated and filtered with a 200 mesh sieve to obtain an amorphous silica slurry.
Table 1 shows the average particle diameter and standard deviation of the amorphous silica of the amorphous silica slurry. Further, a part of the cake after filtration and washing was dried at 105 ° C. and subjected to a specific surface area, a pore diameter and a pore volume. Table 1 shows the specific surface area, pore diameter, and pore volume of amorphous silica.

Example 6
A coated paper for printing was prepared in the same manner as in Example 1 except that the following amorphous silica F was used, smoothed so that the glossiness of the blank paper was 62%, adjusted to a paper thickness of 50 μm, and paper was made. Manufactured. The basis weight was 51.0 g / m ² .

(Manufacture of amorphous silica F)
423 parts of water, aqueous sodium 676 parts of sulfuric acid of a concentration of 6%, were successively added with stirring Si0 ₂ concentration 28.8wt / wt% / Na ₂ O concentration 9.5 wt / wt% of sodium silicate 417 parts, the temperature Adjusted to 55 ° C. Next, 119 parts of 20% strength sulfuric acid was added while stirring at a temperature of 55 ° C. to neutralize the first stage, then the temperature was raised to 85 ° C., and at this temperature, 20% strength sulfuric acid was added. Was added with stirring until pH 5.7, and the second stage neutralization was performed. Next, the slurry obtained above was separated and filtered with a 200 mesh sieve to obtain an amorphous silica slurry.
Table 1 shows the average particle diameter and standard deviation of the amorphous silica of the amorphous silica slurry. Further, a part of the cake after filtration and washing was dried at 105 ° C. and subjected to a specific surface area, a pore diameter and a pore volume. Table 1 shows the specific surface area, pore diameter, and pore volume of amorphous silica.

Example 7
For printing as described in Example 1, except that the following coating layer coating solution B was used, smoothing was performed so that the glossiness of the blank paper was 62%, the paper thickness was adjusted to 50 μm, and the paper was made. Coated paper was produced. The basis weight was 49.5 g / m ² .

(Preparation of coating solution B for coating layer)
As a pigment, kaolin (trade name: Milagros J, manufactured by BASF) 90% with an average particle size of 0.25 μm, heavy calcium carbonate with an average particle size of 0.8 μm (trade name: Hydrocurve 90, manufactured by Bihoku Flour Industries Co., Ltd.) ) Oxidized starch (trade name: Oji) with respect to 100 parts of pigment in a slurry of a pigment mixture composed of 5% and 5% light calcium carbonate (trade name: TP123CS, manufactured by Okutama Kogyo Co., Ltd.) having an average particle size of 0.45 μm Ace B, supra) 3.0 parts, styrene-butadiene copolymer latex (trade name: Smartex PA2323, particle size: 89 nm, manufactured by Nippon A & L Co., Ltd.) (all in terms of solid content), resin pigment (product) Name: Ropaque HP91, average particle size: 1 μm, porosity: 55%, manufactured by Rohm and Haas) 2.5 parts and auxiliary agents such as antifoaming agent and dye, The end the solid content to prepare a 59% coated liquid.

Example 8
For printing as in Example 1, except that the following coating layer coating solution C was used, smoothing was performed so that the glossiness of the blank paper was 62%, the paper thickness was adjusted to 50 μm, and papermaking was performed. Coated paper was produced. The basis weight was 50.5 g / m ² .

(Preparation of coating solution C for coating layer)
As a pigment, kaolin (trade name: HT-GAS, manufactured by BASF Corp.) 45% having an average particle size of 0.39 μm, heavy calcium carbonate having an average particle size of 0.8 μm (trade name: Hydrocurve 90, Bihoku Flour Industry Co., Ltd.) Manufactured product) 15% and a light mixture of 40% light calcium carbonate having an average particle size of 0.45 μm (trade name: TP123CS, manufactured by Okutama Kogyo Co., Ltd.), 100 parts of pigment, and oxidized starch (trade name: Oji Ace B, supra) 3.0 parts, styrene-butadiene copolymer latex (trade name: SMARTEX PA2323, particle size: 89 nm, manufactured by Nippon A & L Co., Ltd.) (all in terms of solid content), resin pigment ( (Product name: Ropaque HP91, average particle diameter: 1 μm, porosity: 55%, manufactured by Rohm and Haas) 2.5 parts and auxiliary agents such as antifoaming agent and dye are added. And finally solid concentration was prepared 59% of the coated liquid.

Example 9
For printing in the same manner as in Example 1 except that the following coating layer coating solution D was used, smoothing was performed so that the glossiness of the blank paper was 62%, the paper thickness was adjusted to 50 μm, and papermaking was performed. Coated paper was produced. The basis weight was 52.0 g / m ² .

(Preparation of coating solution D for coating layer)
As a pigment, kaolin (trade name: Astraplus, manufactured by Imeris Co., Ltd.) 45% having an average particle size of 0.60 μm, heavy calcium carbonate having an average particle size of 0.8 μm (trade name: Hydrocurve 90, manufactured by Bihoku Powdered Industries Co. ) Oxidized starch (trade name: Oji) with respect to 100 parts of pigment in a slurry of a pigment mixture comprising 15% and 40% light calcium carbonate (trade name: TP123CS, manufactured by Okutama Kogyo Co., Ltd.) having an average particle size of 0.45 μm Ace B, supra) 3.0 parts, styrene-butadiene copolymer latex (trade name: Smartex PA2323, particle size: 89 nm, manufactured by Nippon A & L Co., Ltd.) (all in terms of solid content), resin pigment (product) Name: Ropaque HP91, average particle size: 1 μm, porosity: 55%, manufactured by Rohm and Haas) 2.5 parts and auxiliary agents such as antifoaming agent and dye added Te, and finally solid concentration was prepared 59% of the coated liquid.

Example 10
For printing as described in Example 1, except that the following coating layer coating solution E was used, smoothing was performed so that the glossiness of the blank paper was 62%, the paper thickness was adjusted to 50 μm, and papermaking was performed. Coated paper was produced. The basis weight was 54.5 g / m ² .

(Preparation of coating solution E for coating layer)
As a pigment, kaolin with an average particle size of 0.85 μm (trade name: Capim NP, manufactured by Imeris) 45%, heavy calcium carbonate with an average particle size of 0.8 μm (trade name: Hydrocurve 90, manufactured by Bihoku Flour Industries Co., Ltd.) ) Oxidized starch (trade name: Oji) with respect to 100 parts of pigment in a slurry of a pigment mixture comprising 15% and 40% light calcium carbonate (trade name: TP123CS, manufactured by Okutama Kogyo Co., Ltd.) having an average particle size of 0.45 μm Ace B, supra) 3.0 parts, styrene-butadiene copolymer latex (trade name: Smartex PA2323, particle size: 89 nm, manufactured by Nippon A & L Co., Ltd.) (all in terms of solid content), resin pigment (product) Name: Ropaque HP91, average particle size: 1 μm, porosity: 55%, manufactured by Rohm and Haas) 2.5 parts and auxiliary agents such as antifoaming agent and dye Eventually solid concentration was prepared 59% of the coated liquid

Example 11
With a size press coater, oxidized starch (trade name: Oji Ace B, supra) against 100 parts of heavy calcium carbonate (trade name: Hydrocurve 90, manufactured by Bihoku Flour Industry Co., Ltd.) with an average particle size of 0.8 μm 20 parts, 10 parts of styrene-butadiene copolymer latex (trade name: SMARTEX PA2323, particle size: 89 nm, manufactured by Nippon A & L Co., Ltd.), and additives such as antifoaming agents and dyes are added. Finally, a coating solution having a solid content concentration of 50% is applied and dried so that the coating amount on both sides is 4.0 g / m ^2, and further, the above coating layer is applied onto the coating layer. The coating solution A for coating was coated on both sides using a blade coater and dried so that the dry mass per side was 8 g / m ² , thereby providing the outermost coating layer. Next, a smoothing processing machine (soft nip calender) installed in the paper machine was smoothed so that the glossiness of the blank paper was 62%, adjusted to a paper thickness of 50 μm, and papermaking was performed in the same manner as in Example 1. A coated paper for printing was produced. The basis weight was 51.0 g / m ² .

Example 12
A coated paper for printing was prepared in the same manner as in Example 1 except that the following amorphous silicate K was used, smoothing was performed so that the glossiness of the blank paper was 62%, the paper thickness was adjusted to 50 μm, and the paper was made. Manufactured. The basis weight was 49.5 g / m ² .

(Manufacture of amorphous silicate K)
460 parts of water, aqueous sodium 524 parts of sulfuric acid concentration of 6%, were successively added with stirring Si0 ₂ concentration 28.8wt / wt% / Na ₂ O concentration 9.5 wt / wt% of sodium silicate 417 parts, the temperature Adjusted to 55 ° C. Next, 94 parts of 20% strength sulfuric acid was added while stirring at a temperature of 55 ° C. to neutralize the first stage, and then the temperature was raised to 85 ° C. Was added with stirring until pH 6.0, and the second stage neutralization was performed. Next, 10% by mass of a 20% aqueous aluminum sulfate solution was added with stirring. The slurry obtained above was separated and filtered with a 200 mesh sieve to obtain an amorphous silicate slurry.
Table 1 shows the average particle size and standard deviation of the amorphous silicate in the amorphous silicate slurry. Further, a part of the cake after filtration and washing was dried at 105 ° C. and subjected to a specific surface area, a pore diameter and a pore volume. Table 1 shows the specific surface area, pore diameter, and pore volume of the amorphous silicate.

Comparative Example 1
A coated paper for printing was prepared in the same manner as in Example 1 except that the following amorphous silica G was used, smoothed so that the glossiness of blank paper was 62%, adjusted to a paper thickness of 50 μm, and paper was made. Manufactured. The basis weight was 56.5 g / m ² .

(Manufacture of amorphous silica G)
303 parts of water, aqueous sodium 554 parts of sulfuric acid of a concentration of 6%, were successively added with stirring Si0 ₂ concentration 28.8wt / wt% / Na ₂ O concentration 9.5 wt / wt% of sodium silicate 417 parts, the temperature Adjusted to 55 ° C. Next, 125 parts of 20% sulfuric acid was added while stirring at a temperature of 55 ° C. to neutralize the first stage, and then the temperature was raised to 90 ° C. Was added with stirring until pH 5.7, and the second stage neutralization was performed. Next, the slurry obtained above was separated and filtered with a 200 mesh sieve to obtain an amorphous silica slurry.
Table 2 shows the average particle diameter and standard deviation of the amorphous silica of the amorphous silica slurry. Further, a part of the cake after filtration and washing was dried at 105 ° C. and subjected to a specific surface area, a pore diameter and a pore volume. Table 2 shows the specific surface area, pore diameter, and pore volume of amorphous silica.

Comparative Example 2
A coated paper for printing was prepared in the same manner as in Example 1 except that the following amorphous silica H was used, smoothed so that the glossiness of the blank paper was 62%, adjusted to a paper thickness of 50 μm, and paper was made. Manufactured. The basis weight was 57.5 g / m ² .

(Production of amorphous silica H)
642 parts of water, aqueous sodium 285 parts of sulfuric acid of a concentration of 6%, were successively added with stirring Si0 ₂ concentration 28.8wt / wt% / Na ₂ O concentration 9.5 wt / wt% of sodium silicate 417 parts, the temperature Adjusted to 55 ° C. Next, 125 parts of 20% sulfuric acid was added while stirring at a temperature of 55 ° C. to neutralize the first stage, and then the temperature was raised to 90 ° C. Was added with stirring until pH 5.7, and the second stage neutralization was performed. Next, the slurry obtained above was separated and filtered with a 200 mesh sieve to obtain an amorphous silica slurry.
Table 2 shows the average particle diameter and standard deviation of the amorphous silica of the amorphous silica slurry. Further, a part of the cake after filtration and washing was dried at 105 ° C. and subjected to a specific surface area, a pore diameter and a pore volume. Table 2 shows the specific surface area, pore diameter, and pore volume of amorphous silica.

Comparative Example 3
A coated paper for printing was prepared in the same manner as in Example 1 except that the following amorphous silica I was used, smoothed to give a blank paper gloss of 62%, adjusted to a paper thickness of 50 μm, and made paper. Manufactured. The basis weight was 57.0 g / m ² .

(Production of amorphous silica I)
643 parts of water, aqueous sodium 367 parts of sulfuric acid of a concentration of 6%, were successively added with stirring Si0 ₂ concentration 28.8wt / wt% / Na ₂ O concentration 9.5 wt / wt% of sodium silicate 417 parts, the temperature Adjusted to 55 ° C. Next, 119 parts of 20% strength sulfuric acid was added while stirring at a temperature of 55 ° C. to neutralize the first stage, then the temperature was raised to 90 ° C., and at this temperature, 20% strength sulfuric acid was added. Was added with stirring until pH 5.7, and the second stage neutralization was performed. Next, the slurry obtained above was separated and filtered with a 200 mesh sieve to obtain an amorphous silica slurry.
Table 2 shows the average particle diameter and standard deviation of the amorphous silica of the amorphous silica slurry. Further, a part of the cake after filtration and washing was dried at 105 ° C. and subjected to a specific surface area, a pore diameter and a pore volume. Table 2 shows the specific surface area, pore diameter, and pore volume of amorphous silica.

Comparative Example 4
A coated paper for printing was prepared in the same manner as in Example 1 except that the following amorphous silica J was used, smoothed so that the glossiness of the blank paper was 62%, adjusted to a paper thickness of 50 μm, and paper was made. Manufactured. The basis weight was 56.5 g / m ² .

(Manufacture of amorphous silica J)
90 parts of water, aqueous sodium 846 parts of sulfuric acid of a concentration of 6%, were successively added with stirring Si0 ₂ concentration 28.8wt / wt% / Na ₂ O concentration 9.5 wt / wt% of sodium silicate 417 parts, the temperature Adjusted to 55 ° C. Next, 81 parts of 20% sulfuric acid was added while stirring at a temperature of 55 ° C. to neutralize the first stage, then the temperature was raised to 90 ° C., and at this temperature, 20% sulfuric acid was added. Was added with stirring until pH 5.7, and the second stage neutralization was performed. Next, the slurry obtained above was separated and filtered with a 200 mesh sieve to obtain an amorphous silica slurry.
Table 2 shows the average particle diameter and standard deviation of the amorphous silica of the amorphous silica slurry. Further, a part of the cake after filtration and washing was dried at 105 ° C. and subjected to a specific surface area, a pore diameter and a pore volume. Table 2 shows the specific surface area, pore diameter, and pore volume of amorphous silica.

Comparative Example 5
70 parts of hardwood kraft pulp beaten with DDR and adjusted to 380 ml of CSF and 1.0 part of starch in pulp slurry prepared by mixing 30 parts of softwood kraft pulp beaten with DDR and adjusted to 400 ml of CSF ), 0.5 part of a sulfuric acid band, 0.03 part of alkyl ketene dimer (trade name: SKS296, manufactured by Arakawa Chemical Industries), 0.1 part of polyacrylamide (trade name: PS1250, manufactured by Arakawa Chemical Industries), 0.8 parts of the above synthetic amorphous silica A, 9.2 parts of light calcium carbonate (average particle size 6.1 μm), 0.03 part of yield improver (trade name: DR-1500, manufactured by Hymo Co., Ltd.) It added, and papermaking hybrid former, coated with starch in a size press coater so applied amount of double-sided is 1.5 g / m ^2, dried Further, both surfaces coated using a blade coater so that the dry mass per one surface of the coated layer for coated liquid A onto the coated layer is 8 g / m ^2, by performing drying, the outermost layer The coating layer of was provided. Next, the paper was smoothed with a smoothing machine (soft nip calender) installed in the paper machine so that the glossiness of the blank paper was 62%, and a coated paper for printing having a paper thickness of 50 μm was produced. The basis weight was 60.0 g / m ² .

Comparative Example 6
70 parts of hardwood kraft pulp beaten with DDR and adjusted to 380 ml of CSF and 1.0 part of starch in pulp slurry prepared by mixing 30 parts of softwood kraft pulp beaten with DDR and adjusted to 400 ml of CSF ), 0.5 part of a sulfuric acid band, 0.03 part of alkyl ketene dimer (trade name: SKS296, manufactured by Arakawa Chemical Industries), 0.1 part of polyacrylamide (trade name: PS1250, manufactured by Arakawa Chemical Industries), Add 35 parts of the above synthetic amorphous silica A and 0.03 part of yield improver (trade name: DR-1500, manufactured by Hymo Co., Ltd.), make paper with a hybrid former, and apply starch on both sides with a size press coater. The coating amount is 1.5 g / m ² and dried, and the coating layer coating liquid A is applied on one side of the coating layer. Double-side coating and drying were performed using a blade coater so that the dry mass of each was 8 g / m ² , thereby providing the outermost coating layer. Next, the paper was smoothed with a smoothing machine (soft nip calender) installed in the paper machine so that the glossiness of the blank paper was 62%, and a coated paper for printing having a paper thickness of 50 μm was produced. The basis weight was 43.5 g / m ² .

Comparative Example 7
For printing as in Example 1 except that the following coating layer coating solution F was used, smoothing was performed so that the glossiness of the blank paper was 62%, the paper thickness was adjusted to 50 μm, and the paper was made. Coated paper was produced. The basis weight was 56.0 g / m ² .

(Preparation of coating solution F for coating layer)
As a pigment, kaolin with an average particle size of 1.09 μm (trade name: Ultimate, manufactured by BASF) 45%, heavy calcium carbonate with an average particle size of 0.8 μm (trade name: Hydrocurve 90, manufactured by Bihoku Powdered Industries Co., Ltd.) ) Oxidized starch (trade name: Oji) with respect to 100 parts of pigment in a slurry of a pigment mixture comprising 15% and 40% light calcium carbonate (trade name: TP123CS, manufactured by Okutama Kogyo Co., Ltd.) having an average particle size of 0.45 μm Ace B, supra) 3.0 parts, styrene-butadiene copolymer latex (trade name: Smartex PA2323, particle size: 89 nm, manufactured by Nippon A & L Co., Ltd.) (all in terms of solid content), resin pigment (product) Name: Ropaque HP91, average particle size: 1 μm, porosity: 55%, manufactured by Rohm and Haas) 2.5 parts and auxiliary agents such as antifoaming agent and dye added Te, and finally solid concentration was prepared 59% of the coated liquid.

  The printing paper obtained in each Example and Comparative Example was evaluated for the following density, blank paper gloss, printability, internal bond strength, surface strength, and blank paper opacity. The results are shown in Tables 1 and 2. In addition, about the measurement and evaluation of the coated paper for printing in this invention, unless otherwise indicated, it performed in the environment of 23 degreeC and 50 degreeCRH%.

(density)
Measured according to JIS P 8118-1998.
(Internal amount of amorphous silica or amorphous silicate added to paper)
In accordance with JIS P 8128, measure the ash content of each printing coated paper obtained in Examples and Comparative Examples (A), and do not add amorphous silica or amorphous silicate to each printing coated paper. The amount of ash content of the coated paper thus prepared was measured (B), and B was subtracted from A to calculate the amount of amorphous silica or amorphous silicate added internally to the paper.

(Blank gloss)
Both sides were measured according to JIS P 8142, and the average was determined.

(Printability): Ink fillability and printing smoothness Ink which was printed and printed using 0.15cc of printing ink (Values-G type, manufactured by Dainippon Ink & Chemicals, Inc.) on an RI printer. Concentration (ink fillability) and ink transfer uniformity (printing smoothness) were comprehensively observed and evaluated.
<Evaluation criteria>
5 (excellent) -1 (inferior)
Those with an evaluation of less than 3 have practical problems.

(Internal bond strength)
J. et al. Measurement was carried out according to the internal bond test method of Tappi pulp test method 18-2.

(Surface strength)
Using an RI printing tester, printing was performed using 0.6 cm ^{3 of} printing ink (SD50 for paper test, manufactured by Toyo Ink Co., Ltd.), and the degree of picking on the printed surface was visually evaluated.
A: Picking did not occur at all, and the surface strength was extremely good.
A: Picking occurred slightly, but it was a good level as coated paper.
Δ: Picking occurred and the surface strength was low.
X: A lot of picking occurred and the surface strength was extremely low.

(Blank paper opacity)
The measurement was conducted according to JIS P 8149, and the evaluation was performed based on the following criteria.
<Evaluation criteria>
5 (excellent) -1 (inferior)
Those with an evaluation of less than 3 have practical problems.

As shown in Tables 1 and 2, the coated paper of the present invention has high surface strength, internal bond strength, and opacity, despite its low density, and is excellent in printability.
From this result, the coated paper of the present invention is suitable for use as a paper for commercial printed matter such as flyers, brochures and posters, or for publications such as books and magazines by performing multicolor printing or single color printing. It is.

Claims (5)

A coated paper for printing comprising at least one coated layer mainly composed of a pigment and an adhesive on at least one side of a base paper, wherein the base paper has a pore surface area of 15 to 200 m ² / g, and Amorphous silica particles or amorphous silicate particles having an average pore diameter of 0.10 to 0.80 μm are contained in an amount of 1 to 30% by mass as a filler content in the paper, and the outermost layer of the coating layer is measured by a sedimentation method. A coated paper for printing, which is a layer containing kaolin having an average particle diameter of 1.0 μm or less. The base paper has an amorphous silica particle or an amorphous silicate particle having a pore surface area of 15 to 150 m ² / g and an average pore diameter of 0.15 to 0.80 μm as a filler ratio in the paper of 1 to 1. The printing coating according to claim 1, wherein the coating layer is contained in an amount of 30% by mass, and the outermost layer of the coating layer is a layer containing kaolin having an average particle diameter measured by a precipitation method of 1.0 µm or less. paper.   The coated paper for printing according to claim 1 or 2, wherein the amorphous silica particles or the amorphous silicate particles are particles having a pore volume of less than 4.0 ml / g.   The coated paper for printing according to any one of claims 1 to 3, wherein an average particle diameter of the amorphous silica particles or the amorphous silicate particles is 40 µm or less.   The outermost layer of the coating layer is a layer containing 10% by mass or more and less than 50% by mass of kaolin having an average particle diameter of 1.0 μm or less measured by a precipitation method in the total inorganic pigment in the outermost layer. The coated paper for printing of any one of Claims 1-4 characterized by these.