JP2009001953A - Coated paper for printing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide coated paper low in density, but having a high surface strength and internal bond strength and excellent in printing suitability. <P>SOLUTION: The coated paper for printing includes base paper and at least one coated layer which is composed mainly of a pigment and an adhesive and is formed on at least one surface of the base paper, the base paper contains a porous filler of 1-30 mass% as the filler content in paper, the porous filler contains silicon-containing particles formed of silicon dioxide and/or a silicate and alkaliproof microparticles and has a specific surface area of 10-250 m<SP>2</SP>/g and a pore diameter of 0.08-0.80 μm, and the coated paper has a Parker Print Surf roughness of 0.50-0.99 μm. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

  In recent years, matte-coated paper with low gloss and printing gloss, which is difficult to obtain with glossy coated paper with high gloss on both white and printed gloss, has a low-grade gloss, and low on printing gloss. There is an increasing demand for dull matte coated paper with low gloss but high print gloss. In particular, dull matte coated paper has a good balance of high appeal, which is a characteristic of matte, and high print gloss, which is a characteristic of glossy. Widely applied to prints with improved

In printed materials, weight reduction is required from the viewpoint of resource saving, transportation and mail cost reduction, and accordingly, the density of coated paper is required to be reduced.
As a method of reducing the density of the coated paper, a method of reducing the density of the base paper by reducing the press pressure and machine calendar pressure at the time of base paper making is known. 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 for 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 pulp to be used, and a filler Methods of blending amorphous silica (Patent Documents 2, 3, and 4) and methods of blending amorphous silica or amorphous silicate and a bulking agent have been proposed (see Patent Document 5).
However, when blended with regular amorphous silica or amorphous silicate, or in combination with a bulking agent, amorphous silica, amorphous silicate, bulking agent is mixed with pulp, share when transported to each process, or base paper In addition to being crushed by the press pressure and machine calender pressure at the time, the target density reduction cannot be achieved, and the surface strength of the coated paper and the internal bond strength of the base paper are reduced. Further, since mechanical pulp has high rigidity, there is a problem that the smoothness of the coated paper is lowered and the whiteness is inferior.
In addition, inorganic particles such as calcium carbonate, titanium dioxide, magnesium carbonate, and barium sulfate can be used to improve oil absorption, improve opacity and printability, reduce weight, improve opacity, and improve strength and stiffness. There has been proposed a method of blending a composite filler composed of silica and silicic acid and / or silicate into paper (see Patent Documents 6, 7, 8, 9, 10, 11, 12).
However, these composite fillers composed of inorganic particles and silicic acid and / or silicate are also destroyed by various shares at the time of base paper making, press pressure and machine calendering pressure. It was not possible to achieve both surface and internal bond strength.
In addition, as a method of using a plate-like pigment to improve the covering property of the base paper with a low coating amount and to reduce the weight, a delaminated clay having a volume distribution average particle size of 3.5 to 20 μm is added to 100 parts by mass of the pigment. On the other hand, as a method for applying a coating layer containing 30 to 90 parts by mass (see Patent Document 13), a method for reducing the weight of the coating layer and further reducing the weight by suppressing the crushing due to the calender treatment, the glossiness is low. A method (see Patent Document 14) using easy-to-use synthetic resin particles has been proposed.
However, only these coating layers and calendering methods could not achieve both good printability and target weight reduction.
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

As described above, in the methods described in Patent Documents 1 to 14, it was difficult to obtain a coated paper having high surface strength and high internal bond strength and excellent printability even though the density was low. .
The present invention has been made in view of the above circumstances, and provides a dull matte coated paper having high surface strength and high internal bond strength and excellent printability despite its low density. With the goal.

The present invention includes the following inventions.
[1] A coated paper for printing in which at least one surface of a base paper is provided with at least one coating layer mainly composed of a pigment and an adhesive, and the base paper is formed of silicon dioxide and / or silicate. The porous filler containing the silicon-containing particles and alkali-resistant fine particles, having a specific surface area of 10 to 250 m ² / g and a pore diameter of 0.08 to 0.8 μm is used as a filler ratio in paper of 1 to 30 A coated paper for printing having a mass% content and a Parker print surf roughness of 0.50 to 0.99 μm.
[2] The coated paper for printing according to [1], wherein the porous filler contains 0.1 to 40 parts by mass of alkali-resistant fine particles with respect to 100 parts by mass of the silicon-containing particles.
[3] The coated paper for printing according to [1] or [2], wherein the porous filler has an average particle size of 40 μm or less.

  The coated paper of the present invention has high surface strength and internal bond strength despite its low density, and is excellent in printability. Such a coated paper can be reduced in weight, and can be dull and matte with a high-class feeling, and the design of printed matter can be improved.

(Coated paper)
An embodiment of the coated paper of the present invention will be described.
The coated paper of this embodiment is provided with 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 coated paper of the present invention, chemical pulp such as softwood bleached kraft pulp (NBKP), hardwood bleached kraft pulp (LBKP), sulfite pulp (SP), ground wood 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) And other types of mechanical pulp, and used paper pulp (DIP) made from various types of used paper. The freeness of the pulp component is preferably 250 to 580 CSF from the viewpoint of the balance between strength and stiffness in the base paper.

The porous filler contained in the base paper of the coated paper of the present invention has a specific surface area of 10 to 250 m ² / g and a pore diameter of 0.08 to 0.8 μm, and is formed from silicon dioxide and / or silicate. The obtained silicon-containing particles and alkali-resistant fine particles are contained.
Moreover, it is preferable that a specific surface area is 10-150 m < ² > / g and a pore diameter is 0.12-0.8 micrometer. Furthermore, the specific surface area is preferably 10 to 100 m ² / g and the pore diameter is preferably 0.15 to 0.8 μm.
Here, the silicate forming the silicon-containing particles is a compound represented by the general formula xM ₂ O · ySiO ₂ , xMO · ySiO ₂ , xM ₂ O ₃ · ySiO ₂ , wherein M is Al, Fe , Ca, Mg, Na, K, Ti, Zn (x and y are arbitrary positive numerical values).

Examples of the alkali-resistant fine particles include kaolin, calcined kaolin, calcium carbonate, barium sulfate, titanium dioxide, talc, alumina, magnesium carbonate, magnesium oxide, and magnesium hydroxide. Among these, calcium carbonate, kaolin, and talc are preferable because of cost advantage.

When the specific surface area is less than 10 m ² / g, the particle size distribution is deteriorated, fine particles and coarse particles are increased, and the surface strength and the internal bond strength are lowered. 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.
If it exceeds 250 m ² / g, the cohesive strength of the aggregated structure will be weak, and it will be easily crushed by the shearing force, press pressure, and calendar treatment pressure during pulp slurry preparation, and the bulkiness will be insufficient. Furthermore, the opacity when blended into paper is reduced.

On the other hand, if the pore diameter is less than 0.08 μm, the cohesive strength of the aggregated structure is weakened, and it tends to be crushed by the shearing force, press pressure, and calendar treatment pressure during pulp slurry preparation, resulting in insufficient bulkiness. Furthermore, the opacity when blended into paper is reduced.
When it exceeds 0.8 μm, the particle size distribution is deteriorated, fine particles and coarse particles are increased, and the internal strength and the surface strength are lowered. In addition, the coarse particles roughen the surface of the base paper, and a strong smoothing treatment is required to develop the desired surface smoothness, resulting in insufficient bulkiness.
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 pressure within the measurement range. It is the value obtained from the relationship of the amount of mercury. The pore diameter is also the median pore diameter obtained from the integral specific surface area curve using a pore sizer 9320 (manufactured by Shimadzu Corporation).

The content of the alkali-resistant fine particles is preferably 0.1 to 40 parts by mass, more preferably 0.3 to 24 parts by mass with respect to 100 parts by mass of the silicon-containing particles. Due to the content of the alkali-resistant fine particles being in the above range, it is suitable for the bulkiness of paper and the prevention of crushing due to the fan pump from the preparation of pulp slurry to the sheet, the shearing force by stirring, the pressure by pressing, calendering, etc. A porous filler is obtained.
If the content of the alkali-resistant fine particles is less than 0.1 parts by mass, the particle size distribution becomes broad and the internal bond strength and surface strength of the paper are lowered, and the surface smoothness is also lowered by the generated coarse particles. In order to express the smoothness, a strong smoothing process is required and the bulkiness is lowered. Moreover, since different particle diameters are internally added, printability is also reduced. Moreover, when it exceeds 40 mass parts, it will be crushed easily and the bulking effect will fall.
The content of the alkali-resistant fine particles can be determined by making a powder sample of the porous filler into a tablet and then measuring it using a fluorescent X-ray analyzer.

The porous filler has a specific surface area and pore size in a specific range and a good particle size distribution, so that the internal bond strength and surface strength are reduced by adding to paper, and further, the calender In addition to maintaining the bulkiness of the base paper layer during the surface treatment, the surface of the base paper due to coarse particles is small and has good smoothness. In addition, since it has good particle size distribution and few porous fillers with different particle sizes, it has excellent smoothness without unevenness in a state where pressure is applied at the time of printing or the like, and is therefore excellent in printability. The porous filler is required to contain 1 to 30% by mass as a filler content in paper, and is preferably contained in the range of 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 become insufficient.

Internal bond strength is preferably at 300 J / ^{m 2} or more, more preferably has a 400 J / ^{m 2} or more. More preferably, it is 500 J / m ² or more.

The porous filler preferably has an average particle size of 40 μm or less, more preferably 3 to 30 μm, and further preferably 5 to 25 μm. When the average particle diameter of the porous filler exceeds 40 μm, the surface strength is lowered and the surface smoothness is also lowered. Therefore, a strong smoothing treatment is required to express the desired smoothness, and the bulkiness is increased. Decreases. 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 the porous filler, the standard deviation (σ) is preferably 0.350 or less, and more preferably 0.300 or less. With such a particle size distribution, both coarse particles and fine particles are reduced, and not only better internal bond strength and surface strength can be obtained, but also 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 porous filler is produced by adding alkali-resistant microparticles in an aqueous alkali silicate solution, adding a mineral acid solution and / or a metal salt solution of a mineral acid in the presence of the alkali-resistant microparticles, In this method, the aqueous alkali solution is neutralized to deposit silicon-containing particles in the presence of a certain electrolyte. In addition, since it has good smoothness particularly in a state where pressure is applied during printing, it has excellent printability.

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 the porous filler can be produced efficiently. When the alkali silicate aqueous solution is a sodium silicate aqueous solution, the SiO ₂ / Na ₂ O mole The ratio is preferably 2.0 to 3.4.
The addition amount of the alkali-resistant fine particles is 0.1 to 40 parts by mass, preferably 0.3 to 30 parts by mass with respect to 100 parts by mass of the silicon-containing particles to be produced.

In addition, the alkali-resistant microparticles are preferably added to the aqueous alkali silicate solution while the alkali-silicate aqueous solution is stirred while the alkali-resistant microparticles are added to the aqueous slurry of the alkali-resistant microparticles. Even if an acid-alkaline aqueous solution is added, there is no problem.
In addition, the alkali-resistant fine particles may be added all at once to the alkali silicate aqueous solution before the addition of the mineral acid solution and / or the metal salt solution of the mineral acid, or may be added in multiple portions. Good.

  In the mineral acid solution and / or the metal salt solution of the mineral acid used in the present invention, examples of the mineral acid include hydrochloric acid, sulfuric acid, nitric acid and the like, and the metal salt of the mineral acid includes a sodium salt of the mineral acid, A potassium salt, a calcium salt, an aluminum salt, etc. are mentioned. 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, a pulp slurry containing a beaten pulp component, the porous filler, if necessary, a paper strength enhancer, a sizing agent, a fixing agent, an antifoaming agent, a coloring It can be obtained by preparing a stock by adding an agent and making paper.
As a papermaking method, for example, a method of performing acidic papermaking, neutral papermaking, or alkaline papermaking using a long net machine including a top wire, a round net machine, a twin wire machine, a machine using them together, a Yankee dryer machine, etc. Etc.

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, for the purpose of adjusting papermaking suitability and strength characteristics of the base paper, other fillers than the above porous fillers, for example, amorphous silica, amorphous silicate, talc, kaolin, heavy calcium carbonate, light calcium carbonate, Titanium oxide or the like may be included.

Preferably the basis weight of the base paper is 30~300g / ^{m 2,} in terms of opacity and bulkiness of the base paper, and more preferably 40~130g / ^{m 2.}

The coating layer constituting the coated paper of the present invention contains a pigment and an adhesive, and examples of the pigment contained in the coating layer include inorganic pigments and resin pigments.
Examples of inorganic pigments include heavy calcium carbonate, light calcium carbonate, satin white, calcium sulfite, gypsum, barium sulfate, talc, kaolin, clay, calcined kaolin, white carbon, delaminated kaolin, engineered kaolin, diatomaceous earth, Examples thereof include magnesium carbonate, titanium dioxide, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, zinc oxide, magnesium oxide, bendnite, and sericite.

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 resin pigment may be hollow or solid particles, may be a particle having a through hole, or may be a bowl-shaped particle.

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%.

Among the one or more coating layers, the outermost coating layer includes both the inorganic pigment and the resin pigment, and the content of the resin pigment in the coating layer is 2 to 20% by mass. preferable. If the content of the resin pigment is 2% by mass or more, the smoothness after the calendering process becomes higher, and if it is 20% by mass or less, the glossiness of the blank paper can be easily reduced and the printing strength can be reduced. Decline can be prevented more.
In addition, when a coating layer is one layer, the coating layer becomes the outermost layer.

The inorganic pigment contained in the outermost coating layer contains 50 to 100% by mass of a kaolin component composed of engineered kaolin and / or delaminated kaolin, and the average particle size measured by the sedimentation method in the kaolin component is 0. The thing of 2-1.0 micrometer is preferable. If the content of the kaolin component is 50% by mass or more, the blank paper glossiness and smoothness will be higher.
In addition, if the average particle diameter measured by the sedimentation method of the kaolin component is 0.2 μm or more, the amount of the kaolin component penetrating into the base paper can be reduced when the coating layer is formed. Can be higher. Further, the glossiness of the white paper can be easily lowered, and matte coated paper can be more easily produced. Moreover, if the average particle diameter is 1.0 μm or less, an excessive decrease in the glossiness of the white paper can be prevented.
In the present invention, the average particle diameter measured by the sedimentation method is an average particle diameter (d ₅₀ ) of 50 cumulative mass%.

When the kaolin component in the inorganic pigment is less than 100% by mass, other inorganic pigments are included. Examples of other inorganic pigments include calcium carbonate, calcium sulfate, satin white, titanium oxide, zinc oxide, aluminum hydroxide, magnesium hydroxide, barium sulfate, silica, and silica-alumina. 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. .

  Inorganic pigments, in terms of securing the fluidity of the coating liquid used when forming the coating layer and improving the surface quality of the resulting coated paper, 50 to 85% by mass of the inorganic pigment is the kaolin. More preferably, it is a component and the rest is another inorganic pigment.

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 outermost coating layer and the base paper.
Further, the outermost coating layer and the undercoat coating layer may be composed of the same component or different components.
When two or more coating layers are provided, the smoothness of the coated paper becomes 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 individually by 1 type, and may use 2 or more types together.

  The adhesive content in the coating layer is preferably 5 to 50 parts by mass, more preferably 10 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 dull matte coated paper of the present invention is required to have a Parker print surf roughness of 0.50 to 0.99 μm.
That is, the smoothness (Parker print surf roughness) of the coated paper is in the range of 0.50 to 0.99 μm, which is a characteristic of matte matte coated paper and features of high appeal and gloss. This is a necessary element for having a high printing gloss with a good balance. When the Parker print surf roughness is less than 0.50 μm, that is, when the smoothness is excessively high, the glossiness of the blank paper becomes too high, and the desired dull tone is obtained. The matte property is reduced. Conversely, if the Parker print surf roughness exceeds 0.99 μm, the desired print gloss cannot be obtained.
The blank paper glossiness is a value measured with an incident angle of light for measurement being 75 °.

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 70 g / m ² as an example, if the dry coating amount per side is about 5 to 30 g / m ² , sufficient coverage, desired smoothness and printing glossiness can be obtained. Obtainable.

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 machine calendar processes such as a chilled calendar and a soft nip calendar, a super calendar process, a mat calendar process, and a roughened calendar process.
As the pressure finishing process of the coated paper, a calendar process is applied in which the Parker print surf roughness is in the range of 0.50 to 0.99 μm.

The calendering process in which the Parker print surf roughness is in the range of 0.50 to 0.99 μm is a calendering process under the condition that the surface is not excessively smoothed. For example, the calendering process with a low linear pressure (nip pressure), Examples of the method include calendering with a reduced number of paper passes (number of nips) between rolls and calendering with a roll having a rough surface. In the present invention, since it contains a specific porous filler that is difficult to be crushed even under pressure during pressure treatment, and can obtain uniform and good smoothness even when the smoothing treatment conditions are weak, low A dull matte coated paper that achieves both density and high printability can be obtained.

The method for producing a coated paper according to this embodiment applies a coating liquid to at least one side of a base paper containing a specific range of the specific porous filler described above as a base paper, provides a coating layer, and has a Parker print surf roughness. In this method, the coated paper is obtained by adjusting the thickness to 0.50 to 0.99 μm. As described above, the specific porous filler contained in the base paper is not easily crushed even when pressure is applied, and exhibits uniform and good smoothness in a state where pressure is applied during printing. According to the above production method using a base paper containing such a specific porous filler, a coated paper having high printability and excellent surface strength and internal bond strength despite its low density. Can be manufactured.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to the following examples. In the following examples, “part” and “%” mean “part by mass” and “% by mass”, respectively, unless otherwise specified.
Moreover, in the porous filler used in the following examples, the alkali-resistant fine particle content, specific surface area, pore diameter, and average particle diameter were measured as follows.
(Alkali-resistant fine particle content)
The alkali-resistant fine particle content is a value measured using a fluorescent X-ray analyzer (Spectris PW2404).

(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 9320 (manufactured by Shimadzu Corporation), which is a 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).
(Average particle size)
The average particle diameter is a 50% volume integrated particle diameter 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 sedimentation method is measured as an average particle diameter (d ₅₀ ) of 50 cumulative mass% using a pigment dispersion containing the pigment as a measurement sample and using Cedigraph 5100 (manufactured by Micrometrics). did.
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
(Manufacture of porous filler A)
263 parts by weight of water, 754 parts by weight of sodium sulfate aqueous solution of 5% strength, were sequentially added with stirring Si0 ₂ concentration 28.8wt / wt% / Na ₂ O concentration 9.5 wt / wt% of sodium silicate 330 parts by weight . Next, 100 parts by mass of a 9.5% concentration calcium carbonate dispersion A (calcium carbonate is needle-shaped) adjusted to have an average particle size of 0.6 μm with a sand grinder as alkali-resistant microparticles. It was added with stirring at a temperature of 55 ° C. Next, 74 parts by mass 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. Sulfuric acid was added with stirring until the pH reached 6.8 to neutralize the second stage. Next, the slurry obtained above was separated and filtered with a 200-mesh sieve to obtain a porous filler slurry.
Table 1 shows the average particle size and standard deviation of the porous filler in the porous filler slurry.
A part of the cake after filtration and washing was dried at 105 ° C., and the specific surface area and pore diameter were measured, and the alkali-resistant fine particle content was measured with a fluorescent X-ray analyzer. Table 1 shows the specific surface area, pore diameter, and content of alkali-resistant fine particles of the porous filler.

(Preparation of coating solution A for undercoat layer in contact with base paper)
As a pigment, 95% heavy calcium carbonate having an average particle size of 0.8 μm (trade name: Hydrocurve 90, manufactured by Bihoku Flour Chemical Co., Ltd.), Sachin White having an average particle size of 1.0 μm (trade name: Sachin White B, Shiroishi) 5 parts of oxidized starch (trade name: Oji Ace B, manufactured by Oji Cornstarch Co., Ltd.), styrene-butadiene copolymer latex (trade name: Smartex) 9 parts of PA2182-2 (manufactured by Nippon A & L Co., Ltd.) and auxiliary agents such as an antifoaming agent and a dye were added to finally prepare a coating solution having a solid content concentration of 59%.

(Preparation of coating solution B for outermost coating layer)
As a pigment, 30% light calcium carbonate having an average particle size of 0.55 μm (trade name: TP-123-CS, manufactured by Okutama Kogyo Co., Ltd.), fine kaolin having an average particle size of 0.4 μm (trade name: Kao gloss, manufactured by Huber): USA) 5%, engineered kaolin (trade name: Miracrips PG, Engelhard) 51% with an average particle size of 0.5 μm, delaminated kaolin (Contour 1500 / Imeris) 10% with an average particle size of 0.46 μm In the pigment slurry consisting of 4.0% resin pigment, hollow plastic pigment (trade name: Ropeke HP91, average particle size: 1 μm, porosity: 55%, manufactured by Rohm and Haas Co.) Oxidized starch (trade name: Oji Ace B, manufactured by Oji Cornstarch) 3 parts, styrene-butadiene copolymer latex (trade) Name: smart tex PA2182-2, manufactured by Nippon A & L Inc.) 10 parts, and a defoaming agent were added auxiliaries such as dyes, finally a solid concentration of 59% coated liquid was prepared.

(Preparation of coated paper for printing)
70 parts by mass of hardwood kraft pulp beaten with DDR and adjusted to 390 ml of CSF, and 30 parts by weight of softwood kraft pulp beaten with DDR and adjusted to 410 ml of CSF and mixed with pulp slurry, 1.0 part of starch (100 parts of pulp) Product 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, Ltd.), 0.5 part of polyacrylamide (trade name) : PS1250, manufactured by Arakawa Chemical Industries, Ltd.), 7.0 parts of the above synthetic porous filler A, 5.0 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.), paper is made with a hybrid former, and starch is applied on both sides with a size press coater of 1.5. / M ² and so as coated, dried, smoothed by the installed smoothing device (soft nip calender) in a paper machine, to produce a base paper.
On the base paper, the coating solution A for the undercoat coating layer is coated on both sides using a blade coater and dried so that the dry mass per side is 8 g / m ^2. Was established. Next, the outermost coating layer coating liquid B is coated on both sides using a blade coater and dried so that the dry mass per side is 9 g / m ² , thereby providing the outermost coating layer. It was. The coated paper thus obtained is adjusted for the conditions of a super calender consisting of a metal roll and an elastic roll, and the paper is coated so that the paper thickness is 77 μm and the Parker print surf roughness is 0.83 μm. A paper was obtained (basis weight 71.6 g / m ² ).

Example 2
Using the following porous filler B, comprising a smoothing processor (soft nip calender) installed in a paper machine and a metal roll and an elastic roll so that the paper thickness is 77 μm and the Parker print surf roughness is 0.86 μm. A coated paper for printing was obtained (basis weight 72.5 g / m ² ) in the same manner as in Example 1 except that adjustment and smoothing were performed using a super calender.
(Manufacture of porous filler B)
831 parts by mass of water, 161 parts by mass of a 5% aqueous sodium sulfate solution, and 330 parts by mass of sodium silicate having a SiO ₂ concentration of 28.8 wt / wt% / Na ₂ O concentration of 9.5 wt / wt% were added with stirring. Next, 100 parts by mass of calcium carbonate dispersion A was added as alkali-resistant fine particles at a temperature of 50 ° C. with stirring. Next, 74 parts by mass of 20% sulfuric acid was added while stirring at a temperature of 50 ° C. to neutralize the first stage, and then the temperature was raised to 90 ° C. Sulfuric acid was added with stirring until the pH reached 6.9 to carry out the second neutralization. Next, the slurry obtained above was separated and filtered with a 200 mesh sieve to obtain a porous filler slurry.
Table 1 shows the average particle size and standard deviation of the porous filler in the porous filler slurry.
Further, a part of the cake after filtration and washing was dried at 105 ° C., the specific surface area and the pore diameter were measured, and the alkali-resistant fine particle content was measured with a fluorescent X-ray analyzer. Table 1 shows the specific surface area, pore diameter, and content of alkali-resistant fine particles of the porous filler.

Example 3
Using the following porous filler C, comprising a smoothing processor (soft nip calender) installed in a paper machine and a metal roll and an elastic roll so that the paper thickness is 77 μm and the Parker print surf roughness is 0.90 μm. A coated paper for printing was obtained (basis weight 73.2 g / m ² ) in the same manner as in Example 1 except that adjustment and smoothing were performed using a super calender.
(Synthesis of porous filler C)
286 parts by mass of water, 725 parts by mass of a 5% sodium sulfate aqueous solution, and 330 parts by mass of sodium silicate having a SiO ₂ concentration of 28.8 wt / wt% / Na ₂ O concentration of 9.5 wt / wt% were added with stirring. Next, 100 parts by mass of calcium carbonate dispersion A was added as alkali-resistant fine particles at a temperature of 50 ° C. with stirring.
Next, 79.2 parts by mass of 20% sulfuric acid was added while stirring at a temperature of 50 ° C. to neutralize the first stage, then the temperature was raised to 90 ° C., and at this temperature, 20% The sulfuric acid having a concentration was added with stirring until the pH reached 6.8 to carry out the second neutralization. Next, the slurry obtained above was separated and filtered with a 200 mesh sieve to obtain a porous filler slurry.
Table 1 shows the average particle size and standard deviation of the porous filler in the porous filler slurry.
Further, a part of the cake after filtration and washing was dried at 105 ° C., the specific surface area and the pore diameter were measured, and the alkali-resistant fine particle content was measured with a fluorescent X-ray analyzer. Table 1 shows the specific surface area, pore diameter, and content of alkali-resistant fine particles of the porous filler.

Example 4
70 parts by mass of hardwood kraft pulp beaten with DDR and adjusted to 390 ml of CSF, and 30 parts by weight of softwood kraft pulp beaten with DDR and adjusted to 410 ml of CSF and mixed with pulp slurry, 1.0 part of starch (100 parts of pulp) Product 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, Ltd.), 0.5 part of polyacrylamide (trade name) : PS1250, manufactured by Arakawa Chemical Industries, Ltd.), 1.8 parts of porous filler A, 10.2 parts of light calcium carbonate (average particle size 6.1 μm), 0.03 part of yield improver (trade name: DR-1500, HYMO Co., Ltd.) and so as added, and papermaking hybrid former, the coating amount of the both sides of the starch in the size press coater 1.5 g / m Become so coated, dried, smoothed by the installed smoothing device (soft nip calender) in a paper machine, to produce a base paper.
On the base paper, the coating solution A for the undercoat coating layer is coated on both sides using a blade coater and dried so that the dry mass per side is 8 g / m ^2. Was established. Next, the outermost coating layer coating solution B is coated on both sides using a blade coater and dried so that the dry mass per side becomes 9 g / m ² to provide the outermost coating layer. It was. The coated paper thus obtained is adjusted for the conditions of a super calender consisting of a metal roll and an elastic roll, and the paper is coated so that the paper thickness is 77 μm and the Parker print surf roughness is 0.97 μm. A paper was obtained (basis weight 76.7 g / m ² ).

Example 5
In a pulp slurry prepared by mixing 58% by mass of hardwood kraft pulp beaten with DDR and adjusted to 390 ml of CSF and 42% by weight of softwood kraft pulp beaten with DDR and adjusted to 410 ml of CSF, 1.0 part of starch (100 parts of pulp) Product 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), 1.0 part of polyacrylamide (trade name) : PS1280, manufactured by Arakawa Chemical Industry Co., Ltd.), porous filler A 20 parts, yield improver 0.03 part (trade name: DR-1500, manufactured by Hymo Co., Ltd.), paper-made with a hybrid former, A smoothing process installed in a paper machine by applying and drying starch with a size press coater so that the coating amount on both sides is 1.5 g / m ^2. A base paper was produced by smoothing with a machine (soft nip calender).
On the base paper, the coating solution A for the undercoat coating layer is coated on both sides using a blade coater and dried so that the dry mass per side is 8 g / m ^2. Was established. Next, the outermost coating layer coating solution B is coated on both sides using a blade coater and dried so that the dry mass per side becomes 9 g / m ² to provide the outermost coating layer. It was. The coated paper thus obtained is adjusted for the conditions of a super calender consisting of a metal roll and an elastic roll, and the paper is coated so that the paper thickness is 77 μm and the Parker print surf roughness is 0.64 μm. A paper was obtained (basis weight 65.7 g / m ² ).

Example 6
Using the following coating solution C for the outermost coating layer, a smoothing processing machine (soft nip calender) and metal installed in the paper machine so that the paper thickness is 77 μm and the Parker print surf roughness is 0.87 μm A coated paper for printing was obtained (basis weight 76.1 g / m ² ) in the same manner as in Example 1 except that adjustment and smoothing treatment were performed using a super calender composed of a roll and an elastic roll.
(Preparation of coating solution C for outermost coating layer)
As a pigment, 78% of light calcium carbonate having an average particle size of 0.55 μm (trade name: TP-123-CS, manufactured by Okutama Kogyo Co., Ltd.) and fine kaolin having an average particle size of 0.4 μm (trade name: Kao gloss, manufactured by Huber): USA: Engineered kaolin (trade name: Miracrips PG, Engelhard) 5%, hollow plastic pigment (trade name: Ropaque HP91, average particle size: 1 μm, porosity) with 13%, average particle size 0.5 μm : 55%, manufactured by Rohm and Haas Co.) 4.0 parts of pigment slurry, 3 parts of oxidized starch (trade name: Oji Ace B, manufactured by Oji Cornstarch Co., Ltd.) and 100 parts of pigment, styrene-butadiene copolymer 10 parts of combined latex (trade name: Smartex PA2182-2, manufactured by Nippon A & L Co., Ltd.), antifoaming agent, dye, etc. Was added, and finally a coating solution having a solid content of 59% was prepared.

Example 7
The following porous filler D is used, and it consists of a smoothing processor (soft nip calender) installed in a paper machine and a metal roll and an elastic roll so that the paper thickness is 77 μm and the Parker print surf roughness is 0.62 μm. A coated paper for printing was obtained (basis weight 75.5 g / m ² ) in the same manner as in Example 1 except that adjustment and smoothing were performed using a super calender.
(Synthesis of porous filler D)
162 parts by mass of water, 851 parts by mass of a 5% aqueous sodium sulfate solution, and 104 parts by mass of sodium silicate having a SiO ₂ concentration of 28.8 wt / wt% / Na ₂ O concentration of 9.5 wt / wt% were added with stirring. Next, 46.8 parts by mass of 50.0% concentration calcium carbonate dispersion B (calcium carbonate shape is needle-shaped) adjusted to have an average particle size of 0.6 μm with a sand grinder as alkali-resistant fine particles. Was added with stirring at a temperature of 50 ° C. Next, 18 parts by mass of 20% sulfuric acid was added while stirring at a temperature of 50 ° C. to neutralize the first stage, and then the temperature was raised to 90 ° C. Sulfuric acid was added with stirring until the pH reached 9.0 to neutralize the second stage. Next, the slurry obtained above was separated and filtered with a 200 mesh sieve to obtain a porous filler slurry.
Table 1 shows the average particle size and standard deviation of the porous filler in the porous filler slurry.
Further, a part of the cake after filtration and washing was dried at 105 ° C., the specific surface area and the pore diameter were measured, and subjected to measurement of the alkali-resistant fine particle content by a fluorescent X-ray analyzer. Table 1 shows the specific surface area, pore diameter, and content of alkali-resistant fine particles of the porous filler.

Example 8
Using the following coating solution D for the outermost coating layer, a smoothing processor (soft nip calender) and metal installed in the paper machine so that the paper thickness is 77 μm and the Parker print surf roughness is 0.87 μm A coated paper for printing was obtained (basis weight 74.1 g / m ² ) in the same manner as in Example 1 except that adjustment and smoothing treatment were performed using a super calender composed of a roll and an elastic roll.
(Preparation of coating solution D for outermost coating layer)
As a pigment, light calcium carbonate having an average particle size of 0.55 μm (trade name: TP-123-CS, manufactured by Okutama Kogyo Co., Ltd.) 32%, fine kaolin having an average particle size of 0.4 μm (trade name: Kao gloss, manufactured by Huber): USA) Engineered kaolin with 6.5% average particle size of 0.5 μm (trade name: Miracrips PG, Engelhard) 51% delaminated kaolin with average particle size of 0.46 μm (Contour 1500 / Imeris) Hollow pigment pigment (trade name: Ropeke HP91, average particle size: 1 μm, porosity: 55%, manufactured by Rohm and Haas Co.) 0.5% with respect to 100 parts of pigment 3 parts of oxidized starch (trade name: Oji Ace B, manufactured by Oji Cornstarch), styrene-butadiene copolymer latex Product Name: smart Tex PA2182-2, Nippon A & L Inc.) 10 parts, and a defoaming agent were added auxiliaries such as dyes, finally a solid concentration of 59% coated liquid was prepared.

Example 9
The following porous filler F is used, and it consists of a smoothing processor (soft nip calender) installed in a paper machine and a metal roll and an elastic roll so that the paper thickness is 77 μm and the Parker print surf roughness is 0.90 μm. A coated paper for printing was obtained in the same manner as in Example 1 except that it was adjusted and smoothed with a super calender (basis weight 73.1 g / m ² ).
(Synthesis of porous filler F)
138 parts by mass of water, 904 parts by mass of a 5% strength aqueous sodium sulfate solution, and 330 parts by mass of sodium silicate having a SiO ₂ concentration of 28.8 wt / wt% / Na ₂ O concentration of 9.5 wt / wt% were added with stirring. Next, 76 parts by mass of calcium carbonate dispersion B was added as alkali-resistant fine particles at 50 ° C. with stirring. Next, 76.8 parts by mass of 20% strength sulfuric acid was added while stirring at a temperature of 50 ° C. to perform the first stage neutralization, and then the temperature was raised to 90 ° C. The sulfuric acid of the density | concentration was added, stirring until pH was set to 6.9, and the 2nd step | paragraph neutralization was performed. Next, the slurry obtained above was separated and filtered with a 200 mesh sieve to obtain a porous filler slurry.
Table 1 shows the average particle size and standard deviation of the porous filler in the porous filler slurry.
Further, a part of the cake after filtration and washing was dried at 105 ° C., the specific surface area and the pore diameter were measured, and the alkali-resistant fine particle content was measured with a fluorescent X-ray analyzer. Table 1 shows the specific surface area, pore diameter, and content of alkali-resistant fine particles of the porous filler.

Example 10
Using the following porous filler G, comprising a smoothing processor (soft nip calender) installed in a paper machine and a metal roll and an elastic roll so that the paper thickness is 77 μm and the Parker print surf roughness is 0.92 μm. A coated paper for printing was obtained (basis weight 75.1 g / m ² ) in the same manner as in Example 1 except that adjustment and smoothing were performed using a super calender.
(Synthesis of porous filler G)
310 parts by mass of water, 696 parts by mass of 5% sodium sulfate, and 330 parts by mass of sodium silicate having a SiO ₂ concentration of 28.8 wt / wt% / Na ₂ O concentration of 9.5 wt / wt% were added with stirring. Next, 100 parts by mass of calcium carbonate dispersion A was added as alkali-resistant fine particles at a temperature of 50 ° C. with stirring. Next, 84.2 parts by mass of 20% sulfuric acid was added while stirring at a temperature of 50 ° C. to neutralize the first stage, and then the temperature was raised to 90 ° C. The sulfuric acid having a concentration was added with stirring until the pH reached 6.8 to carry out the second neutralization. Next, the slurry obtained above was separated and filtered with a 200 mesh sieve to obtain a porous filler slurry.
Table 1 shows the average particle size and standard deviation of the porous filler in the porous filler slurry.
Further, a part of the cake after filtration and washing was dried at 105 ° C., the specific surface area and the pore diameter were measured, and the alkali-resistant fine particle content was measured with a fluorescent X-ray analyzer. Table 1 shows the specific surface area, pore diameter, and content of alkali-resistant fine particles of the porous filler.

Example 11
30% by weight of hardwood kraft pulp beaten with DDR and prepared to 370 ml of CSF, 30% by weight of softwood kraft pulp beaten with DDR and prepared to 390 ml of CSF, 20% by weight of BCTMP beaten with DDR and prepared to 200 ml of CSF, and DIP prepared to 270 ml of CSF (upper white Waste paper) 20% by mass of pulp slurry, and 1.0 part of starch (trade name: Ace K, manufactured by Oji Constarch), 0.5 part of sulfuric acid band, alkyl ketene dimer 0.03 part (trade name: SKS296, manufactured by Arakawa Chemical Industries), 0.8 part of polyacrylamide (trade name: PS1280, manufactured by Arakawa Chemical Industries), 7.0 parts of the above synthetic porous filler A, light calcium carbonate (Average particle diameter 6.1 μm) 5.0 parts, yield improver 0.03 parts (trade name: DR-15 0, added to a manufactured Hymo Co., Ltd.), and paper in hybrid formers, applying a starch size press coater so applied amount of double-sided is 2.0 g / m ^2, and dried, the paper machine Was smoothed by a smoothing machine (soft nip calender) installed in No. 1 to produce a base paper.
On the base paper, the coating solution A for the undercoat coating layer is coated on both sides using a blade coater and dried so that the dry mass per side is 8 g / m ^2. Was established. Next, the outermost coating layer coating solution B is coated on both sides using a blade coater and dried so that the dry mass per side becomes 9 g / m ² to provide the outermost coating layer. It was. The coated paper thus obtained is adjusted for the conditions of a super calender consisting of a metal roll and an elastic roll, and is passed through to give a printing coating with a paper thickness of 77 μm and a Parker print surf roughness of 0.92 μm. A paper was obtained (basis weight 69.5 g / m ² ).

Example 12
The following porous filler H is used, and it consists of a smoothing processor (soft nip calender) installed in the paper machine and a metal roll and an elastic roll so that the paper thickness is 77 μm and the Parker print surf roughness is 0.82 μm. A coated paper for printing was obtained (basis weight 71.6 g / m ² ) in the same manner as in Example 1 except that adjustment and smoothing were performed using a super calender.
(Manufacture of porous filler H)
263 parts by weight of water, 754 parts by weight of sodium sulfate aqueous solution of 5% strength, were sequentially added with stirring Si0 ₂ concentration 28.8wt / wt% / Na ₂ O concentration 9.5 wt / wt% of sodium silicate 330 parts by weight . Next, 100 parts by mass of a 9.5% concentration fine kaolin (MGJ, Engelhard) dispersion C having an average particle size of 0.8 μm as alkali-resistant fine particles was added at a temperature of 55 ° C. with stirring. Next, 74 parts by mass 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. Sulfuric acid was added with stirring until the pH reached 6.8 to neutralize the second stage. Next, the slurry obtained above was separated with a sieve of 200 mesh and filtered to obtain a porous filler slurry.
Table 1 shows the average particle size and standard deviation of the porous filler in the porous filler slurry.
A part of the cake after filtration and washing was dried at 105 ° C., and the specific surface area and pore diameter were measured, and the alkali-resistant fine particle content was measured with a fluorescent X-ray analyzer. Table 1 shows the specific surface area, pore diameter, and content of alkali-resistant fine particles of the porous filler.

Example 13
Using the following porous filler I, a smoothing machine (soft nip calender) and a metal roll and an elastic roll installed in a paper machine so that the paper thickness is 77 μm and the Parker print surf roughness is 0.0.81 μm A coated paper for printing was obtained in the same manner as in Example 1 except that it was adjusted and smoothed with a super calender made of (basis weight 71.6 g / m ² ).
(Manufacture of porous filler I)
263 parts by weight of water, 754 parts by weight of sodium sulfate aqueous solution of 5% strength, were sequentially added with stirring Si0 ₂ concentration 28.8wt / wt% / Na ₂ O concentration 9.5 wt / wt% of sodium silicate 330 parts by weight . Next, as alkali-resistant microparticles, 100 parts by mass of a 9.5% -concentration heavy calcium carbonate (FMT-90, manufactured by Phimatech) dispersion D having an average particle diameter of 1.2 μm was stirred at a temperature of 55 ° C. Added. Next, 74 parts by mass 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. Sulfuric acid was added with stirring until the pH reached 6.8 to neutralize the second stage. Next, the slurry obtained above was separated and filtered with a 200-mesh sieve to obtain a porous filler slurry.
Table 1 shows the average particle size and standard deviation of the porous filler in the porous filler slurry.
A part of the cake after filtration and washing was dried at 105 ° C., and the specific surface area and pore diameter were measured, and the alkali-resistant fine particle content was measured with a fluorescent X-ray analyzer. Table 1 shows the specific surface area, pore diameter, and content of alkali-resistant fine particles of the porous filler.

Example 14
Using the following porous filler J, comprising a smoothing processing machine (soft nip calender) installed in a paper machine and a metal roll and an elastic roll so that the paper thickness is 77 μm and the Parker print surf roughness is 0.82 μm. A coated paper for printing was obtained (basis weight 71.6 g / m ² ) in the same manner as in Example 1 except that adjustment and smoothing were performed using a super calender.
(Manufacture of porous filler J)
263 parts by weight of water, 754 parts by weight of sodium sulfate aqueous solution of 5% strength, were sequentially added with stirring Si0 ₂ concentration 28.8wt / wt% / Na ₂ O concentration 9.5 wt / wt% of sodium silicate 330 parts by weight . Next, 100 parts by mass of a 9.5% concentration talc (talc B, manufactured by Nippon Talc) dispersion E having an average particle diameter of 1.2 μm as alkali-resistant microparticles was added at a temperature of 55 ° C. with stirring. Next, 74 parts by mass 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. Sulfuric acid was added with stirring until the pH reached 6.8 to neutralize the second stage. Next, the slurry obtained above was separated and filtered with a 200-mesh sieve to obtain a porous filler slurry.
Table 1 shows the average particle size and standard deviation of the porous filler in the porous filler slurry.
A part of the cake after filtration and washing was dried at 105 ° C., and the specific surface area and pore diameter were measured, and the alkali-resistant fine particle content was measured with a fluorescent X-ray analyzer. Table 1 shows the specific surface area, pore diameter, and content of alkali-resistant fine particles of the porous filler.

Example 15
The following porous filler K is used, and it consists of a smoothing machine (soft nip calender) installed in the paper machine and a metal roll and an elastic roll so that the paper thickness is 77 μm and the Parker print surf roughness is 0.94 μm. A coated paper for printing was obtained (basis weight 76.0 g / m ² ) in the same manner as in Example 1 except that adjustment and smoothing were performed using a super calender.
(Manufacture of porous filler K)
470 parts by weight of water, 455 parts by weight of sodium sulfate aqueous solution of 5% strength, were sequentially added with stirring Si0 ₂ concentration 28.8wt / wt% / Na ₂ O concentration 9.5 wt / wt% of sodium silicate 330 parts by weight . Next, 100 parts by weight of calcium carbonate dispersion A was added as alkali-resistant microparticles at 50 ° C. with stirring. Next, 99 parts by mass of 20% sulfuric acid was added while stirring at a temperature of 50 ° C. to neutralize the first stage, and then the temperature was raised to 90 ° C. Sulfuric acid was added with stirring until the pH reached 6.8 to neutralize the second stage. Next, the slurry obtained above was separated with a sieve of 200 mesh and filtered to obtain a porous filler slurry.
Table 1 shows the average particle size and standard deviation of the porous filler in the porous filler slurry.
A part of the cake after filtration and washing was dried at 105 ° C., and the specific surface area and pore diameter were measured, and the alkali-resistant fine particle content was measured with a fluorescent X-ray analyzer. Table 1 shows the specific surface area, pore diameter, and content of alkali-resistant fine particles of the porous filler.

Example 16
Using the following porous filler P, comprising a smoothing processor (soft nip calender) installed in a paper machine and a metal roll and an elastic roll so that the paper thickness is 77 μm and the Parker print surf roughness is 0.86 μm. A coated paper for printing was obtained in the same manner as in Example 1 except that it was adjusted and smoothed with a super calendar (basis weight 72.3 g / m ² ).
(Manufacture of porous filler P)
115 parts by weight of water, 836 parts by weight of a 5% strength sodium sulfate aqueous solution, and 330 parts by weight of sodium silicate having a SiO ₂ concentration of 28.8 wt / wt% / Na ₂ O concentration of 9.5 wt / wt% were sequentially added with stirring. . Next, 250 parts by weight of calcium carbonate dispersion A was added as alkali-resistant fine particles at 50 ° C. with stirring. Next, 69.3 parts by mass of 20% sulfuric acid was added while stirring at a temperature of 50 ° C. to neutralize the first stage, then the temperature was raised to 90 ° C., and at this temperature, 20% The sulfuric acid of the density | concentration was added, stirring until it became pH 6.9, and the 2nd step | paragraph neutralization was performed. Next, the slurry obtained above was separated and filtered with a 200-mesh sieve to obtain a porous filler slurry.
Table 1 shows the average particle size and standard deviation of the porous filler in the porous filler slurry.
A part of the cake after filtration and washing was dried at 105 ° C., and the specific surface area and pore diameter were measured, and the alkali-resistant fine particle content was measured with a fluorescent X-ray analyzer. Table 1 shows the specific surface area, pore diameter, and content of alkali-resistant fine particles of the porous filler.

Example 17
Using the following porous filler Q, it consists of a smoothing processor (soft nip calender) installed in the paper machine and a metal roll and an elastic roll so that the paper thickness is 77 μm and the Parker print surf roughness is 0.97 μm. A coated paper for printing was obtained (basis weight 75.0 g / m ² ) in the same manner as in Example 1 except that adjustment and smoothing treatment were performed using a super calendar.
(Manufacture of porous filler Q)
557 parts by weight of water, 479 parts by weight of sodium sulfate aqueous solution of 5% strength, were sequentially added with stirring Si0 ₂ concentration 28.8wt / wt% / Na ₂ O concentration 9.5 wt / wt% of sodium silicate 330 parts by weight . Next, 0.8 parts by mass of calcium carbonate dispersion A was added as alkali-resistant fine particles at 50 ° C. with stirring. Next, 76.8 parts by mass of 20% sulfuric acid was added while stirring at a temperature of 50 ° C. to perform the first neutralization, and then the temperature was raised to 90 ° C. The sulfuric acid of the density | concentration was added, stirring until it became pH 6.8, and the 2nd step | paragraph neutralization was performed. Next, the slurry obtained above was separated and filtered with a 200-mesh sieve to obtain a porous filler slurry.
Table 1 shows the average particle size and standard deviation of the porous filler in the porous filler slurry.
A part of the cake after filtration and washing was dried at 105 ° C., and the specific surface area and pore diameter were measured, and the alkali-resistant fine particle content was measured with a fluorescent X-ray analyzer. Table 1 shows the specific surface area, pore diameter, and content of alkali-resistant fine particles of the porous filler.

Comparative Example 1
The following porous filler L is used, and it consists of a smoothing processor (soft nip calender) installed in a paper machine and a metal roll and an elastic roll so that the paper thickness is 77 μm and the Parker print surf roughness is 0.90 μm. A coated paper for printing was obtained (basis weight 79.3 g / m ² ) in the same manner as in Example 1 except that adjustment and smoothing were performed using a super calendar.
(Synthesis of porous filler L)
346 parts by mass of water, 483 parts by mass of a 10% aqueous sodium sulfate solution, and 174 parts by mass of sodium silicate having a SiO ₂ concentration of 28.8 wt / wt% / Na ₂ O concentration of 9.5 wt / wt% were added with stirring. Next, 55 parts by mass of calcium carbonate dispersion B was added as alkali-resistant fine particles at 50 ° C. with stirring. Next, 19.5 parts by mass of 20% sulfuric acid was added while stirring at a temperature of 50 ° C. to carry out the first stage of neutralization, and then the temperature was raised to 90 ° C. A second stage of neutralization was performed by adding sulfuric acid having a concentration until stirring at pH 9.0. Next, the slurry obtained above was separated and filtered with a 200 mesh sieve to obtain a porous filler slurry.
Table 2 shows the average particle size and standard deviation of the porous filler in the porous filler slurry.
Further, a part of the cake after filtration and washing was dried at 105 ° C., the specific surface area and the pore diameter were measured, and the alkali-resistant fine particle content was measured with a fluorescent X-ray analyzer. Table 2 shows the specific surface area, pore diameter, and content of alkali-resistant fine particles of the porous filler.

Comparative Example 2
The following porous filler M is used, and it comprises a smoothing machine (soft nip calender) installed in a paper machine and a metal roll and an elastic roll so that the paper thickness is 77 μm and the Parker print surf roughness is 0.96 μm. A coated paper for printing was obtained (basis weight 80.1 g / m ² ) in the same manner as in Example 1 except that adjustment and smoothing were performed using a super calender.
(Synthesis of porous filler M)
103 parts by weight of water, 388 parts by weight of 5% sodium sulfate, and 243 parts by weight of sodium silicate having a SiO ₂ concentration of 28.8 wt / wt% / Na ₂ O concentration of 9.5 wt / wt% were added with stirring. Next, 295 parts by mass of calcium carbonate dispersion A was added as alkali-resistant fine particles at a temperature of 50 ° C. with stirring. Next, 64 parts by mass of 20% sulfuric acid was added while stirring at a temperature of 50 ° C. to neutralize the first stage, and then the temperature was raised to 90 ° C. Sulfuric acid was added with stirring until the pH reached 8.0 to neutralize the second stage. Next, the slurry obtained above was separated and filtered with a 200 mesh sieve to obtain a porous filler slurry.
Table 2 shows the average particle size and standard deviation of the porous filler in the porous filler slurry.
Further, a part of the cake after filtration and washing was dried at 105 ° C., the specific surface area and the pore diameter were measured, and the alkali-resistant fine particle content was measured with a fluorescent X-ray analyzer. Table 2 shows the specific surface area, pore diameter, and content of alkali-resistant fine particles of the porous filler.

Comparative Example 3
The following porous filler N is used, and it comprises a smoothing processing machine (soft nip calender) installed in a paper machine and a metal roll and an elastic roll so that the paper thickness is 77 μm and the Parker print surf roughness is 0.88 μm. A coated paper for printing was obtained in the same manner as in Example 1 except that it was adjusted and smoothed with a super calendar (basis weight 82.4 g / m ² ).
(Synthesis of porous filler N)
417 parts by weight of water, 393 parts by weight of sodium sulfate having a 5% concentration, and 330 parts by weight of sodium silicate having a SiO ₂ concentration of 28.8 wt / wt% / Na ₂ O concentration of 9.5 wt / wt% were added with stirring. Next, 100 parts by mass of calcium carbonate dispersion A was added as alkali-resistant fine particles at a temperature of 40 ° C. with stirring. Next, 94 parts by mass of 20% sulfuric acid was added while stirring at a temperature of 40 ° C. to neutralize the first stage, and then the temperature was raised to 90 ° C. Sulfuric acid was added with stirring until the pH reached 6.9 to carry out the second neutralization. Next, the slurry obtained above was separated and filtered with a 200 mesh sieve to obtain a porous filler slurry.
Table 2 shows the average particle size and standard deviation of the porous filler in the porous filler slurry.
Further, a part of the cake after filtration and washing was dried at 105 ° C., the specific surface area and the pore diameter were measured, and the alkali-resistant fine particle content was measured with a fluorescent X-ray analyzer. Table 2 shows the specific surface area, pore diameter, and content of alkali-resistant fine particles of the porous filler.

Comparative Example 4
The following porous filler O is used, and it consists of a smoothing processing machine (soft nip calender) installed in a paper machine and a metal roll and an elastic roll so that the paper thickness is 77 μm and the Parker print surf roughness is 0.93 μm. A coated paper for printing was obtained in the same manner as in Example 1 except that it was adjusted and smoothed with a super calendar (basis weight 82.4 g / m ² ).
(Synthesis of porous filler O)
564 parts by mass of 5% sodium sulfate and 330 parts by mass of sodium silicate having a SiO ₂ concentration of 28.8 wt / wt% / Na ₂ O concentration of 9.5 wt / wt% were added with stirring. Next, 110 parts by mass of calcium carbonate dispersion A110 was added as alkali-resistant fine particles at a temperature of 70 ° C. with stirring. Next, 62 parts by mass of 20% sulfuric acid was added while stirring at a temperature of 70 ° C. to neutralize the first stage, and then the temperature was raised to 90 ° C. Sulfuric acid was added with stirring until the pH reached 6.9 to carry out the second neutralization. Next, the slurry obtained above was separated and filtered with a 200 mesh sieve to obtain a porous filler slurry.
Table 2 shows the average particle size and standard deviation of the porous filler in the porous filler slurry.
Further, a part of the cake after filtration and washing was dried at 105 ° C., the specific surface area and the pore diameter were measured, and the alkali-resistant fine particle content was measured with a fluorescent X-ray analyzer. Table 2 shows the specific surface area, pore diameter, and content of alkali-resistant fine particles of the porous filler.

Comparative Example 5
70 parts by mass of hardwood kraft pulp beaten with DDR and adjusted to 390 ml of CSF, and 30 parts by weight of softwood kraft pulp beaten with DDR and adjusted to 410 ml of CSF and mixed with pulp slurry, 1.0 part of starch (100 parts of pulp) Product 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, Ltd.), 0.5 part of polyacrylamide (trade name) : PS1250, manufactured by Arakawa Chemical Industries, Ltd.), 0.8 part of the porous filler A, 11.2 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.), paper is made with a hybrid former, and the amount of starch applied on both sides is 1.5 with a size press coater. / M ² and so as coated, dried, smoothed by the installed smoothing device (soft nip calender) in a paper machine, to produce a base paper.
On the base paper, the coating solution A for the undercoat coating layer is coated on both sides using a blade coater and dried so that the dry mass per side is 8 g / m ^2. Was established. Next, the outermost coating layer coating liquid B is coated on both sides using a blade coater and dried so that the dry mass per side is 9 g / m ² , thereby providing the outermost coating layer. It was. The coated paper thus obtained is adjusted for the conditions of a super calender consisting of a metal roll and an elastic roll, and is passed through to give a printing coating with a paper thickness of 77 μm and a Parker print surf roughness of 0.92 μm. A paper was obtained (basis weight 86.2 g / m ² ).

Comparative Example 6
70 parts by mass of hardwood kraft pulp beaten with DDR and adjusted to 390 ml of CSF, and 30 parts by weight of softwood kraft pulp beaten with DDR and adjusted to 410 ml of CSF and mixed with pulp slurry, 1.0 part of starch (100 parts of pulp) Product name: Ace K, manufactured by Oji Constarch Co., Ltd.), sulfuric acid band 0.5 part, alkyl ketene dimer 0.03 part (trade name: SKS296, manufactured by Arakawa Chemical Industries), polyacrylamide 0.5 part (trade name: PS1250, manufactured by Arakawa Chemical Industry Co., Ltd.), 35 parts of the above porous filler A, 0.03 part of yield improver (trade name: DR-1500, manufactured by Hymo Co., Ltd.), and paper making with a hybrid former. Applying and drying starch with a size press coater so that the coating amount on both sides is 1.5 g / m ² , smoothing installed in the paper machine The paper was smoothed by a processing machine (soft nip calender) to produce a base paper.
On the base paper, the coating solution A for the undercoat coating layer is coated on both sides using a blade coater and dried so that the dry mass per side is 8 g / m ^2. Was established. Next, the outermost coating layer coating solution B is coated on both sides using a blade coater and dried so that the dry mass per side becomes 9 g / m ² to provide the outermost coating layer. It was. The coated paper thus obtained is adjusted for the conditions of a super calender consisting of a metal roll and an elastic roll, and the paper is coated so that the paper thickness is 77 μm and the Parker print surf roughness is 0.62 μm. A paper was obtained (basis weight 61.6 g / m ² ).

The matte coated paper obtained in each Example and Comparative Example was evaluated for the following density, blank paper gloss, printability, smoothness, 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.
(Blank gloss)
Both sides were measured according to JIS P 8142, and the average was determined.
(Smoothness)
Smoothness (μm) using Parker Print Surf Surface Smoothness Tester (Mezmer) according to ISO 8791-4 (1992), rubber (soft type) for backing, and clamping pressure of 1 MPa Was measured. The smoothness was measured 5 times, and the average value was obtained. The smaller the measured value, the higher the smoothness.

(Printability): Ink fillability and printing smoothness Ink which was printed by using 0.15 cc of printing ink (Values-G type, manufactured by Dainippon Ink & Chemicals, Inc.) with an RI printer. The density (ink fillability) and the 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.
□: 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.

Claims (3)

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 is silicon formed from silicon dioxide and / or silicate 1 to 30% by mass of a porous filler containing contained particles and alkali-resistant fine particles, having a specific surface area of 10 to 250 m ² / g and a pore diameter of 0.08 to 0.80 μm, as a filler content in paper. A coated paper for printing, containing a Parker print surf roughness of 0.50 to 0.99 μm. The coated paper for printing according to claim 1, wherein the porous filler contains 0.1 to 40 parts by mass of alkali-resistant microparticles with respect to 100 parts by mass of the silicon-containing particles. The coated paper for printing according to claim 1 or 2, wherein the porous filler has an average particle size of 40 µm or less.