JPH06108396A - Production of coated paper for printing - Google Patents

Abstract

PURPOSE:To provide the method for producing the printing coated paper excellent in whiteness and luster without generating a flow band defect and a mottling by using a coating solution compounded with satin white. CONSTITUTION:The method for producing the coated paper for printing is characterized by coating raw paper or base paper with an aqueous coating solution containing as main components an adhesive agent and a pigment comprising 100 pts.wt. of a pigment and 1-30 pts.wt. of satin white produced from 0.1-100mum diameter calcined lime particles as a raw material, preliminarily drying the coated paper with IR light, and subsequently drying the dried coated paper with a hot air drier.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing coated paper for printing. More specifically, the present invention is a means for producing satin white having good fluidity and filterability, and a method in which the satin white is blended with a coating liquid to prevent occurrence of flow stripe defects and mottling, and whiteness. , A method for producing a coated paper for printing having excellent glossiness.

[0002]

2. Description of the Related Art In recent years, in the field of coated paper for printing, quality requirements from the market have become more and more stringent, and excellent whiteness, glossiness and printability have been demanded.
Therefore, satin white, which can easily impart whiteness, smoothness, opacity, glossiness, etc. to coated paper, is preferably used together as a pigment used in preparing a coating liquid.

Sachin White has a chemical name of calcium sulfoaluminate and a chemical formula of 3CaO.Al ₂ O ₃ .3.
It is a common name for CaSO ₄ .31 to 32H ₂ O, and is a white pigment having a columnar or needle-like crystal form. The production method, as shown in JP-A-54-34407, generally lime or aluminum sulfate to an aqueous suspension of slaked _{lime, Al 2 (SO 4) 3} · 1
It is obtained as a reaction product by reacting with 8H ₂ O (common name: sulfuric acid band) or alum. Particularly important conditions during the reaction include the concentration of the liquid during the reaction, the stirring power, the addition rate of the sulfuric acid band, the reaction temperature and the like.

The method for producing satin white using quicklime as a raw material will be described in more detail. Quick lime (calcium oxide, CaO) crushes rough stones (mainly calcium carbonate, CaCO ₃ ) mined from limestone veins existing in the ground into lumps, such as horizontal kilns (rotary kilns) or vertical kilns (calciners). 1000 ~ 15 in the firing furnace
It is produced by firing at a temperature in the range of 00 ° C. for a certain period of time. At this time, the shape of the rough stone is a lump that usually has a diameter of about 3 to 10 cm in consideration of workability, easiness of handling, and the like. It becomes quicklime.

The massive quick lime is poured into a tank containing a predetermined amount of water with stirring, and is gradually dissolved to react with the quick lime and water to produce slaked lime (Ca (OH) ₂ ).
A suspension of is obtained. Although a suspension of slaked lime can be obtained by adding dry powdered slaked lime to water to disperse it, it is usually very expensive to produce dry powdered slaked lime. A simple and low-cost method has been carried out in which water is poured into water to obtain a slaked lime suspension as it is.

Next, an aqueous solution of a sulfuric acid band is vigorously stirred into this suspension of slaked lime until a predetermined pH is reached.
Alternatively, a suspension of satin white can be obtained by adding so as to have a predetermined molar ratio calculated in advance. The end point of this reaction is not a neutralization point but a point containing some free alkali.

Then, this suspension is dehydrated or squeezed by using a press, a centrifuge or the like to obtain a solid content of about 40.
% Of cake-like satin white can be obtained, and dispersant such as sodium polycarboxylate is appropriately added to this to disperse it with a disperser such as ball mill, sand mill, kedi mill, cowless dissolver, attritor, and satin white. A dispersion of is obtained.

For example, JP-A-50-128725 describes a method of treating a pigment dispersion containing satin white with a sand mill. Satin white, when dried and powdered, will have different water of crystallization and different crystal forms.Usually, after the dispersion treatment as described above, the dispersion is used as it is in the coating liquid. Used.

As described above, since the lump-like quick lime is used in the usual method for producing satin white, when the quick lime is thrown into water and stirred, the lump gradually dissolves, so that the lime is dissolved to a certain extent. It takes time, and even if it is dissolved over time, undissolved residue tends to remain. Therefore, it is usually necessary to add the sulfuric acid band after filtering the suspension of slaked lime once.

Satin white is a columnar or acicular crystal, and the major and minor axes of each particle are not constant, and those of various sizes coexist. Usually, the major axis is significantly larger than the minor axis. large. When Satin White having such a special form is blended in the coating liquid, an aggregated structure is formed between the pigments, and the viscosity of the coating liquid increases. Especially, if the particle size of Sachin White is not uniform, the viscosity of the coating solution tends to increase.

In Japanese Patent Publication No. 2-60797, when satin white having an extremely small average major axis of 0.5 to 1 μm is used in combination with coarse-grained calcium carbonate, the aggregating effect between the pigments is impaired and the viscosity of the coating is lowered, resulting in a blade tip. It has been disclosed that the liquidity at the point of time is improved. However, the combined use of coarse-grained calcium carbonate tends to reduce the glossiness and the uniformity of the printing finish, so that it is not suitable as a coated paper for high-grade printing.

[0012] Sachin white is a pigment that is indispensable for high-quality coated paper for printing, and therefore it is desired to increase the compounding ratio as much as possible. Since the viscosity of the liquid increases and the fluidity deteriorates, flow stripe defects (uneven thickness of the coating film) easily occur on the coated surface. This defect is different from streak defects (so-called streaks) in which fine foreign matter adheres to the tip of the blade during blade coating and causes sharp streaky defects in the blade coating area. This is a serious defect because it causes nonuniformity (disorder) of thin film thickness and appears as striped unevenness in density during printing.

During coating, the coating liquid is generally applied to the paper surface by an applicator roll and then scraped off. However, if the coating liquid has a high viscosity and poor fluidity, the coating liquid adheres to the applicator. The thickness is uneven and becomes striped,
It is easy to lead to flow stripe coating defects. In addition, a coating liquid having poor fluidity is difficult to level (so-called leveling) even after being coated on paper, which leads to a poor coating surface.

JP-A-3-113095 discloses that the long side of a single particle diameter has a length of 0.3 to 3 μm and the short side has a length of 0.
When coated with a coating composition containing satin white of 0.5 to 0.3 μm on a base paper having specific physical property values, the coated paper is excellent in gloss of the coated surface, smoothness and ink gloss after printing. Is disclosed. However, no specific method for producing satin white having such a specific particle size is described, and no effect on the filterability of the satin white slurry or the fluidity of the coating solution is described. It is unknown.

Here, the drying of the coating film applied to the paper will be described. Conventionally, hot air drying, blast drying, steam heating, infrared burner heating, infrared heater heating, gas heater heating, electric heater heating, laser heating, high frequency. heating,
Various methods such as electron beam heating are known, but the hot air drying method is generally used in consideration of ease of operation and economy.

On the other hand, drying by infrared rays has been known for a long time not only in paper coating but also industrially. "Industrial materials" No. 25
Vol. 4, No. 4, p132-138 (1977), paints, printing inks, plastics, wood and other organic substances, water, etc. are all 3 μm to 50 μm.
It has the property of absorbing long-wavelength infrared rays over μm. Infrared drying utilizes this property. Further, Japanese Patent Application Laid-Open No. 3-199492 discloses an example of drying with a near infrared ray having a wavelength of 0.75 to 2.5 μm in the production of coated paper.

The Paper and Paper Cooperative Magazine Vol. 45, No. 9, p.
23-29 (1991) describes the coating process of double coated medium quality paper, and the effect on the mottling is obtained by using the drying condition in which the electrically heated infrared ray and the air foil (hot air dryer) are combined as a variable. Although shown, the paint at this time does not contain satin white, and much less is known about the effect on the coating liquid containing specific satin white as in the present invention.

[0018]

DISCLOSURE OF THE INVENTION The inventors of the present invention have conducted extensive studies to solve the above-mentioned drawbacks of the prior art, and as a result, in the method for producing satin white, in which quicklime is dissolved in water and then reacted with a sulfuric acid band, When lime is crushed and used while maintaining the particle size within a specific range, there are few residues generated in the production process of satin white, the filterability is extremely good, the operation is easy, and the coarse particle fraction is found in the particle size distribution. It is possible to obtain a homogeneous satin white with a small particle size and uniform, and because the paint containing this satin white does not increase in viscosity and has good fluidity, a coated surface free of flow stripe defects during coating can be obtained. And that when this is dried by hot air on the coated surface by predrying with infrared rays, no mottling occurs,
Further, they have found that the whiteness and glossiness are further improved by evenly distributing the blended satin white in the coating film, thus completing the present invention.

Therefore, an object of the present invention is to provide a means for producing satin white having good fluidity and good filterability, and to mix the satin white with a coating liquid without causing flow stripe defects or mottling. Another object of the present invention is to provide a method for producing a coated paper for printing which has excellent whiteness and gloss.

[0020]

The present invention provides a method for producing a coated paper for printing, which comprises coating a base paper or a base paper with an aqueous coating solution containing a pigment and an adhesive as main components. 1) The pigment 100 In the weight part, the particle size is 0.1-100μ
1 of satin white produced from m quicklime
30 parts by weight are compounded, and 2) the coating liquid is applied, pre-dried with infrared rays, and then dried with a hot air dryer, which is a method for producing a coated paper for printing.

Particle size used for the present invention 0.1-1
The quicklime in the range of 00 μm, preferably 2 to 70 μm,
It is obtained by crushing massive quicklime having a diameter of 3 to 10 cm produced in the above-mentioned firing furnace and further classifying it.

Various types of crushers have been devised and put into practical use, and there are many names. For example, a compression crushing method such as a rotary type, an impact compression crusher such as a hammer type (hammer mill), a friction crushing method such as a rotary type (roll crusher), and the like can be used, either alone or in combination. Can be used for the present invention.

Classification is carried out by sieving with a sieve or screen having an appropriate pore size, or by gravitational force of powder in an air stream,
Although a method such as an airflow classification method utilizing inertial force, centrifugal force, etc. is commonly used, the airflow classification method is suitable for the classification of particularly fine powder as in the present invention.

A screen is provided for dissolving undissolved residue after dissolving the quicklime in water and before adding the sulfuric acid band. The pores of the screen must be as small as possible to completely remove the residue, but if the pores are small, they tend to become clogged and impair the operability, so a relatively coarse ASTM standard 50 mesh (pore diameter 0.297
mm) The front and back screens are inevitable. In addition, after the reaction produced satin white is dispersed with a sand mill, ball mill, etc., it is further screened. Even at this time, it is preferable that the pores are small, but due to clogging up to about 150 mesh (pore diameter 0.099 mm) at most. Since it is made small, it is a limit in terms of operability.

According to the present invention, however, the screen before adding the sulfuric acid band has a mesh size of 150 mesh (pore diameter 0.099 m).
m), and the screen after dispersing Satin White is 200
It was found that the operation can be performed even if the mesh size (pore diameter 0.074 mm) is reduced. Therefore, the satin white obtained according to the present invention does not contain a residue or foreign matter larger than 0.074 mm (74 μm), so that it also has an effect of significantly reducing the occurrence of streak defects during coating.

The particle size of quicklime is 100 μm (0.10 m
m), when using a 150 mesh (pore size 0.099 mm) screen before adding the sulfuric acid band, clogging may easily impair operability, and a coating liquid containing the produced satin white. It is not suitable because the fluidity of is likely to deteriorate. On the other hand, even if the particle size of quick lime is smaller than 0.1 μm, no special effect is observed,
This is not preferable because it only increases the energy cost required for crushing. However, in the case of producing quick lime having a particle size of 0.1 to 100 μm industrially, it is inevitable that about 10% or less of particles having a particle size slightly out of this range are mixed in the crushing and classification steps. If it is a mixing ratio, there is no problem in the effect of the present invention. The particle size of these quicklimes can be measured by observing the shape directly with an electron microscope, or can be ultrasonically dispersed in a dehydrated and purified solvent such as methanol or ethanol, and can be measured by a centrifugal sedimentation measuring machine. It does not matter which is.

The satin white obtained by the method of the present invention has a very small amount of residues and foreign matters, has no coarse particles, has a small particle size and is very evenly distributed. Since the increase in viscosity when mixed is small, the flowability is good even if a large amount is mixed, and flow stripe defects are unlikely to occur.
Also, since the particle size is small and it is very evenly distributed, it is distributed very uniformly in the coating liquid, so when blended in a certain amount in the coating liquid, whiteness compared to conventional Satin White,
The expression of glossiness becomes more remarkable.

The amount of satin white to be added to the coating solution according to the method of the present invention is 1 to 30 parts by weight, preferably 3 to 20 parts by weight, per 100 parts by weight of the pigment. When the content of Sachin White is less than 1 part by weight, the effect on the whiteness and glossiness of the coated paper is almost eliminated, and when it exceeds 30 parts by weight, the fluidity of the coating tends to be poor, and the coated paper tends to be poor. The whiteness and glossiness of the above are difficult to improve beyond a certain level, which is not preferable.

Next, with respect to infrared drying, it is said that hot air drying which is generally widely used is accompanied by a rapid evaporation of water from the surface of the coating film and migration is likely to occur, whereas drying by infrared rays is performed inside the coating film. It is well known that since it is uniformly heated from above, migration is unlikely to occur, and that infrared drying is particularly effective when it is performed at an early stage in the entire drying process. The use of infrared drying to control binder migration has been a standard method in Europe since the mid-1960s. 1
Until the early 980s it was common to use heaters with temperatures between 1100 ° K and 1400 ° K operating at wavelengths of 2.5 to 2.8 μm. 2400 ° at a wavelength of 1 μm
Current dryers at temperatures of K have increased drying capacity by a factor of 15 over previous cold equipment. (Helmut Graab, 19
91 TAPPI Coating Conf. Proc.)

The inventors of the present invention tend to cause migration when applying and drying the coating solution containing the specific sachin white if only a hot air dryer is used, and the distribution of the satin white in the coating film is likely to occur. It has been found that the results tend to be non-uniform and that the effect of improving whiteness and glossiness is not sufficiently exhibited. This has become remarkable as the drying conditions have been strengthened with the recent increase in coating speed.

On the other hand, as in the present invention, by pre-drying with infrared rays and then drying with hot air, the specific satin white is distributed very uniformly in the coating film, and the conventional satin white was used. It will lead to the improvement of whiteness and gloss that cannot be achieved by just doing it. In addition, by irradiating the coating film immediately after being coated on paper with infrared rays, the coating film is uniformly heated from the inside, the temperature of the entire coating film rises uniformly, the fluidity is improved, and the leveling is improved. Also contributes to the elimination of flow stripe defects.

Infrared rays are near infrared rays, mid infrared rays,
Although it is classified as far-infrared, it is necessary to indicate it accurately by wavelength because the classification is different depending on the book and is not exact. In the present invention, any of these wavelengths can be used, but it is particularly preferable that the wavelength range from 2.5 to 2.5 that is well absorbed by water.
A wavelength of 6 μm is more preferred.

Further, as a device for generating infrared rays, as described in Nikkan Kogyo Shimbun (November 18, 1991, Yasunobu Nakamura), a 1938 American automobile company Ford, Inc. painted red on automobiles. It is said that the outer lamp was put into practical use for the first time in industrial use, and then in Japan as well, the nichrome wire was covered with metal oxide (insulating), and the heating element housed in a metal pipe or the heating element covered with a quartz tube. Was developed and 70
In the year, radiators that directly wrap Nichrome wire in ceramics or coat the metal surface with ceramics appeared,
The heat source is diversified into electricity, gas, steam, and the shape is rod, pipe, cup, ribbon, and flat, and the range of use as an infrared radiator is gradually expanding. In the present invention, any of these may be used, but the most suitable one may be selected in terms of economical efficiency, operability, and the like.

In the case where the drying by infrared rays is carried out by a gas combustion burner system, for example, the amount of gas supplied to select the type of gas is adjusted because the calorie of combustion varies depending on the type of gas. Various methods such as adjusting the length of the drying zone by increasing or decreasing the number of burner units to be installed to adjust the temperature of the heat generating part can be arbitrarily used.

As the pigment used in the coating liquid in the present invention, in addition to satin white according to the present invention, kaolin, clay, calcium carbonate, titanium oxide, aluminum hydroxide, zinc oxide, barium sulfate, calcium sulfate,
It is appropriately selected and selected from talc, silica, plastic pigments and the like.

As the adhesive, casein, soybean protein,
Modified starch such as yeast protein, starch, oxidized starch and esterified starch, etherified starch, cationized starch, enzyme modified starch, natural adhesive such as cellulose derivative and styrene
-Butadiene-based copolymer, methylmethacrylate-Conjugated diene-based polymer latex such as butadiene-based copolymer,
Acrylic polymer latex such as acrylic acid or methacrylic acid ester polymer or copolymer, acetic acid type polymer latex such as ethylene-vinyl acetate copolymer, synthetic adhesive such as polyvinyl alcohol are appropriately selected. One or more types are used for the present invention.
The amount of the adhesive used is 8 to 30 parts by weight, preferably 10 to 20 parts by weight, based on 100 parts by weight of the pigment. If the amount of the adhesive used is 8 parts by weight or less, the strength of the coated surface will be weak, and if it is 30 parts by weight or more, the cost will be high, which is not suitable for the present invention.

In preparing the coating liquid, various auxiliaries such as a dispersant, a flow modifier, a defoaming agent, and a colorant, which are added to the ordinary coating liquid for coated paper, are used to obtain desired properties. Are appropriately selected and used as necessary. The solid content concentration of the coating liquid is generally adjusted to about 45 to 75% by weight, but in consideration of the drying load and the workability affected by the viscosity of the coating liquid, it is preferably about 55 to 70% by weight. Be engineered. The aqueous coating solution prepared in this manner is an acidic base paper or medium produced by a normal paper machine using a pulp selected from softwood bleached kraft pulp, hardwood bleached kraft pulp, recycled paper recycled pulp, mechanical pulp, etc. 10 or more on one or both sides of the base paper
30 g / m ^2, still more preferably 15-25 g / m ² coating.

The base paper used in the present invention has a basis weight of 50 to 400.
It is possible to use g / m ² and it is possible to use a single-layer papermaking or a multi-layer papermaking, but it is properly used depending on the application. In other words, 80-150 g / m ² is used in the form of sheets such as catalogs and pamphlets, and 200-is used for box making, picture postcards, cards, etc.
A base paper having a basis weight of about 300 g / m ² is said to be preferable.

The aqueous coating liquid may be directly coated on the base paper,
Alternatively, it may be coated on a base paper having an undercoat of about 3 to 15 g / m ² per side (this is referred to as “base paper” in the present invention). Recently, clear printing is more and more demanded, and so-called two-layer coating (or two-step coating) for coating on a base paper is more preferred.

In the present invention, the coating and drying methods are not particularly limited, and a blade coater, an air knife coater, a bar coater, a roll coater, a chanplex coater, and a size press used in the production of general coated papers. A single layer or multiple layers is coated on one side or both sides of the paper by a coater, a gravure coater, etc., and is first pre-dried by infrared rays, and then usually dried in a hot air dryer zone of 3 to 6 sections. In the case of double-sided coating or multi-layer coating, the entire coating may be continuously coated with one coater having two or more coating equipments, or a part of the entire coating may be coated. Once wound,
Then, the remaining coating may be performed by the same coater or another coater. The final coated paper product is about 3 ~
It is dried to a paper moisture in the range of 8% by weight and wound on a reel.

The coated paper thus obtained is subjected to surface finishing, if necessary, by using a super calender, a mat calender or the like in an on-machine state or an off-machine state to obtain a product. In the present invention, by using a coating solution containing a specific satin white, and by predrying the coating solution with infrared rays in accordance with this, there is no occurrence of flow stripe defects or mottling, In addition, a coated paper for printing having excellent whiteness and glossiness can be manufactured.

[0042]

The present invention will be described in more detail with reference to the following examples, but of course the present invention is not limited thereto. In the following, "parts" and "%" are all absolute dry weight parts and%.

Example 1 2.7 m ³ of water was put into a reaction tank having a volume of 7 m ³ , and while stirring, water was crushed into particles having a particle size in the range of 0.1 to 100 μm, and classified into quicklime (CaO, Adachi). Lime Industry Co., Ltd.) 3
00 kg was added. After stirring, the solution was dissolved, the temperature of the solution was raised, and the temperature was maintained in the range of 85 to 95 ° C for 1 hour.
Cooled to 30 ° C. This solution was passed through a screen of 150 mesh (pore size 0.099 mm), but there was almost no residue. Next, an aqueous solution of a sulfuric acid band (Al ₂ (SO ₄ ) ₃ · 18H ₂ per 1 m ^{3 of} water was added with vigorous stirring.
O dissolved at a rate of 500 kg) 1,750 kg
Was gradually added to obtain a suspension of satin white.

This suspension is squeezed with a filter press,
A cake-like satin white having a solid content concentration of 35% was obtained, and then sodium polycarboxylate (trade name: Aron T-4, manufactured by Toagosei Co., Ltd.) was used per 100 parts of the solid content of the satin white.
0) After adding 3.0 parts and water to a solid content concentration of 20%, the mixture was passed through a sand grinder (32G, manufactured by Igarashi Kikai Co., Ltd.) at a rate of 1 m ³ per hour to obtain a satin white dispersion liquid. This dispersion is 200 mesh (pore size 0.0
(74 mm) vibrating screen to obtain a satin white finishing liquid.

Next, 5 parts of satin white and kaolin (Engelhard Minerals) obtained by the above-mentioned method were used.
And Chemicals (EMC), trade name: Ultra White 90 (50 parts) and heavy calcium carbonate with a particle size of 1 to 3 μm (45 parts, in-house, ground calcium carbonate) are put in a mixer and mixed with it. Oxidized starch (Oji Konstarch Co., Ltd., trade name: Oji Ace A) 3 parts and latex (Asahi Kasei Co., trade name: L-1537) 12 parts, and sodium polyacrylate 0.3% as a dispersant per pigment. Calcium stearate 0.5 as a lubricant
% And 0.2% of fluorescent dye are added in sequence and mixed well,
The pH was adjusted to alkaline with a 25% aqueous ammonia solution to prepare an aqueous coating solution having a solid content of 60%.

This coating solution was applied to hardwood bleached kraft pulp 9
A blade coater (manufactured by Mitsubishi Heavy Industries, Ltd.) on one side of a base paper having a basis weight of 80 g / m ² obtained by making a paper by a known wet paper machine using a mixed pulp of 0 part and 10 parts of softwood bleached kraft pulp. 20 g / m ^{2 was} applied. The coating speed was 1,000 m / min. Immediately after coating, place an infrared dryer (LTH Malmo, gas combustion infrared burner, main wavelength of infrared radiation 2 to 5 μm, surface temperature of burner 800 ° C., drying zone length 2 m) toward the coated surface. Install and pre-dry the coated surface, and then use a hot air dryer consisting of 4 sections (Ishikawajima Harima Heavy Industries Ltd., arched hot air dryer, drying length of 6 m each) to measure the hot air temperature,
The amount of air was adjusted and drying was performed to obtain coated paper having a water content of 6.4%.
The coated paper obtained was supercalendered at a nip pressure of 230 kg / cm.

Various quality evaluations were performed as follows. (1) 150-mesh residue ratio (after dissolution of quicklime) The residue on a screen having a 150-mesh pore size was scraped, dried, weighed, and expressed as a weight% relative to the amount of quicklime raw material charged. (2) Average particle size and particle size distribution of satin white The satin white slurry after being dispersed by a sand grinder was diluted with water and ultrasonically dispersed to remove secondary aggregation, and used as a measurement sample. About this sample, a commercially available measuring device (centrifugal sedimentation type particle size distribution measuring device, manufactured by Shimadzu Corporation, model: SA-CP3
L) was used to measure the average particle size (50% cumulative) and the particle size distribution. Further, the above sample was dried and observed with a scanning electron microscope (manufactured by Hitachi, Ltd.), and the uniformity of particle size distribution (a state in which the particle size was uniform or uneven) was evaluated as follows. ○ The size and shape of the particles are relatively well aligned △ 〃 〃 Somewhat irregular □ 〃 〃 Some irregularity, and coarse particles are also mixed.

(3) Viscosity of coating liquid The coating liquid temperature was set to 20 ° C., and the viscosity was measured with a Hercules high shear air viscometer (8800 rpm). (4) Whiteness after coating It was measured by the method described in JIS P8123. (5) Glossiness of coated paper It was measured by the method described in JIS P 8142. (6) Flow-Striped Defects When the coated paper roll after the super calendar was applied to a cutter (cutting machine), the backside of the paper was illuminated with an illumination lamp to observe the presence or absence of flow-striped defects. The judgment results are shown in five stages as follows. ○ ○ ～ △ △ △ ～ □ □ No defects at all Some defects There are many defects (7) Mottling Visually evaluate the halftone dot portion of the printed matter when printed at a speed of 8000 sheets / hour with a Mitsubishi diamond printing machine. , As follows: ○ ○ ～ △ △ △ ～ □ □ Very good Usually poor

Example 2 The pigment blending ratio in the coating liquid of Example 1 was changed to the following: satin white 15 parts obtained by the method as described above kaolin (ultra white 90) 45 parts heavy calcium carbonate (1 to 3 μm, in-house) The quality was evaluated in exactly the same manner as in Example 1 except that the amount was changed to 40 parts.

Example 3 The pigment blending ratio in the coating liquid of Example 1 was set such that satin white 25 parts kaolin (ultra white 90) 40 parts obtained by the above method 40 parts heavy calcium carbonate (1 to 3 μm, in-house) The quality was evaluated in exactly the same manner as in Example 1 except that the amount was changed to 35 parts.

Example 4 The coated paper prepared in the same manner as in Example 2 and wound up once (before the super calender treatment) was put on the same coater again, and the original paper surface opposite to the coated surface was used. The same coating and drying as in 2 were performed to obtain a double-sided coated paper. 230 kg /
Super calendering was performed at a nip pressure of cm, and the same quality evaluation was performed.

Example 5 A base paper was manufactured by applying 10 g / m ² of an undercoat coating solution having the following composition on one side of a base paper of the same type as used in Example 2. Undercoat coating liquid Kaolin (Ultra White 90) 30 parts Heavy calcium carbonate (self-made, particle size 1 to 3 μm) 70 parts Oxidized starch (Oji Ace A) 2 parts Latex (L-1537) 14 parts Pigment in addition to the above components Sodium polyacrylate (0.3%) as a dispersant and calcium stearate (0.5%) as a lubricant are sequentially added, and mixed and dispersed sufficiently.
The pH was adjusted to be alkaline with an aqueous ammonia solution having a concentration of 60% to obtain a solid concentration of 60%. Then, the same coating solution as in Example 2 was applied on the undercoated surface of the base paper at 15 g / m ² and dried in the same manner as in Example 2 to evaluate the quality.

Example 6 Example 5 was applied to both sides of the same type of base paper as used in Example 5.
In the same manner as above, 10 g of the undercoat coating liquid per side
/ M ^{2 was} coated to produce a base paper. Then, the same coating liquid as in Example 2 was applied onto the undercoated surface of this base paper in Example 2
In the same manner as above, each side was coated with 15 g / m ² and dried to produce a double-side coated paper, and the quality was evaluated.

Example 7 Using a bleached kraft pulp (a ratio of hardwood to softwood of 8: 2), a known three-layer papermaking machine was used.
^{2. The} basis weights of 110 g / m ² were made on both sides of the middle layer to produce a base paper having a total basis weight of 250 g / m ² . On this base paper, an undercoat and an overcoat were applied in the same manner as in Example 6 to produce a double-sided coating, and the quality was evaluated.

Example 8 As a infrared dryer, a gas combustion type infrared dryer (manufactured by Solaronics, main wavelength of infrared rays is 1.5 to 4 μm,
(Surface temperature of burner is 980 ℃, length of drying zone is 1m)
In the same manner as in Example 1 except that was used, one-side coated paper was manufactured and quality evaluation was performed.

Comparative Example 1 Sachin white was produced in the same manner as in Example 6 except that a lump-shaped quicklime raw material having a diameter of 3 to 7 cm mixed therein was used, and this satin white was used. Double-sided coated paper was manufactured and quality was evaluated.

Comparative Example 2 Sachin white was produced in the same manner as in Example 6 except that a granular quicklime raw material having a diameter of 0.2 to 3 mm mixed therein was used. The double-sided coated paper used was manufactured and the quality was evaluated.

Comparative Example 3 A coated paper was produced in the same manner as in Example 1 except that an infrared dryer was not used and only a hot air dryer was used, and the quality was evaluated.

Comparative Example 4 The pigment blending ratio in the coating liquid of Example 1 was set such that the sachin white obtained by the method as described above was 0 parts Kaolin (Ultra White 90) 55 parts Heavy calcium carbonate (1 to 3 μm, in-house) The quality was evaluated in the same manner as in Example 1 except that the amount was changed to 45 parts.

Comparative Example 5 The pigment blending ratio in the coating liquid of Example 1 was set such that the sachin white obtained by the method as described above 35 parts kaolin (ultra white 90) 35 parts heavy calcium carbonate (1 to 3 μm, in-house) A coating solution was prepared in exactly the same manner as in Example 1 except that the amount was changed to 30 parts, but the fluidity of the coating solution was poor and the coating could not be performed. Table 1 shows the quality evaluation results obtained in Example 1 to Comparative Example 5.
The results are shown in Table 2.

[0061]

[Table 1]

[0062]

[Table 2]

From Tables 1 and 2, the satin white of Examples 1 to 8 produced by using quicklime whose particle size is adjusted to a specific range has a small particle size distribution with no coarse particle fraction. It is a uniform and satin white,
It can be seen that the coating liquid containing this satin white contributes to improving the whiteness and glossiness of the coated surface, as well as providing a coated surface with no flow stripe defects and having good fluidity with little increase in viscosity. . Further, in addition to the use of the coating liquid containing the above Satin White, when drying the coating surface of the coating liquid with hot air, predrying with infrared rays not only prevents the occurrence of mottling. It is clear that it also contributes to further improving whiteness and glossiness.

On the other hand, Comparative Example 1 in which satin white produced by using lumped quick lime without crushing was used and the crushing treatment was performed, but large-sized particles were mixed. Comparative Example 2 using Satin White produced using quick lime shows that the viscosity of the coating liquid is high and causes flow stripe defects, and it is also pre-dried by an infrared dryer. In Comparative Example 3 in which Mottling is not performed, the occurrence of Mottling is unavoidable, and
It also shows that the effect of improving whiteness and gloss is inferior. Further, even though the same satin white as in Examples 1 to 8 was used, Comparative Example 5 in which the amount used exceeded 30 parts by weight had poor fluidity of the coating liquid and was applied by the time it was impossible to apply. It shows that the viscosity of the working fluid increases, and Comparative Example 4 in which Sachin White is not used shows that the whiteness and glossiness are significantly inferior to those in the case where Sachin White is used.

[0065]

As described above, according to the present invention, satin white produced by using quicklime whose particle size is adjusted in the range of 0.1 to 100 μm is used in an amount of 1 to 30 parts by weight based on 100 parts by weight of all pigments. Part of an aqueous coating solution is used, and after the coating solution is applied, preliminary drying with infrared rays is performed prior to the hot air drying treatment, so that flow stripe defects and mottling are not generated, and whiteness It is possible to produce the effect that a coated paper for printing having excellent glossiness can be manufactured.

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Claims (1)

[Claims] 1. A method for producing a coated paper for printing, which comprises applying a water-based coating solution containing a pigment and an adhesive as a main component to a base paper or a base paper and drying the mixture. 1) In 100 parts by weight of the pigment, Particle size is 0.1-100μ
1 of satin white produced from m quicklime
30 parts by weight, and 2) a method for producing a coated paper for printing, which comprises: applying the coating solution, predrying it with infrared rays, and then drying it with a hot air dryer.