JP2899558B2 - Cast coated paper and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cast-coated paper having good quality, and more particularly, to a cast-coated paper suitable for use as an ink-jet recording paper for obtaining a high-quality image using an aqueous ink, and a continuous operation during production. To cast-coated paper with excellent properties.

[0002]

2. Description of the Related Art In general, cast-coated paper is prepared by applying a coating solution containing a pigment and an aqueous binder to at least one surface of a base paper, and forming the coating layer while the coating layer is in a wet state. It is pressed onto a heated mirror-finished metal surface, and the mirror-finished metal surface is copied and dried at the same time. The cast coated paper thus obtained is characterized in that it has high gloss and high smoothness as compared with a super calendered normal coated paper. Therefore, when used for printing, an extremely excellent printing effect can be obtained, and a high-grade feeling can be given as a packaging material.

Further, in the field of full-color information paper, the market of which has been expanding in recent years, high gloss recording paper can be obtained by using a film as a base material or applying a wet type laminating technology or a multilayer coating technology. Although the cast coating method is superior to these methods in terms of cost or simplicity of the process, it is compared with the case where general coated paper is obtained. Therefore, there is a disadvantage that productivity is poor.

That is, in the cast coating method, it is necessary to dry the wet coating layer while pressing the wet coating layer on a mirror-finished metal surface, so that moisture in the coating layer passes through the base paper layer and escapes to the opposite side. Must evaporate. Accordingly, the drying efficiency is extremely poor as compared with the case of general coated paper production in which water evaporates from the upper surface or both surfaces of the coating layer, so that the production must be performed at a low speed, resulting in poor productivity.

[0005] In view of this, there have been proposals for improving the drying efficiency by improving the air permeability of the base paper so as to increase the drying efficiency (for example, Japanese Patent Application Laid-Open Nos. 56-26094 and 3-103). 193995 is a publication)
However, in these cast coated papers, the coating amount is as large as 10 to 30 g / m ^2, and therefore, the amount of water to be evaporated is large, so that the productivity cannot be sufficiently improved.

[0006] Further, the low continuous operability also causes a decrease in the productivity of the cast coating method. That is,
In the production of cast coated paper, the peelability of the paper web from the mirror-finished metal surface is gradually impaired over time,
A so-called drum pick occurs in which a part of the coating layer is formed on a mirror-finished metal surface.

[0007] When a drum pick occurs, a sheet break occurs within a short time. In addition, when the paper breaks, the mirror surface is almost always stained, so that the operation must be suspended for a long time for the cleaning operation. Therefore, conventionally, in order to maintain good peelability between the mirror-finished metal surface and the paper web,
On the mirror-finished metal surface, for example, a coating treatment for applying a release agent such as vegetable hardened oil, vegetable oxidized oil, tributyl phosphate, xylene, terpene, monochlorobenzene, etc., and derivatives thereof is performed. Have been done.

Further, in order to obtain good releasability between a mirror-finished metal surface and a paper web, a coating liquid, a coagulating liquid or a rewet liquid may be used, for example, stearic acid, polyethylene, polypropylene, paraffin, silicone oil, Alternatively, a release agent such as a derivative thereof is also added.

However, even when such a peeling acceleration treatment is performed, the peelability between the mirror-finished metal surface and the paper web gradually deteriorates over time. As the cause, the release agent coated on the mirror-finished metal surface is gradually taken to the coating layer, the effect is lost, when the paper strips from the mirror-finished metal surface,
As a result of a small portion of the coating layer remaining on the metal surface, the mirror surface cannot be copied, and at the same time, good peelability between the two is lost.

[0010] On the other hand, the ink jet recording method is to form an image on recording paper by ejecting small ink droplets in various modes, and is less noisy than a dot impact type, and it is easy to make full color printing. Along with
It has the feature that high-speed recording is also possible. Normal,
Almost all of the inks used in the ink jet recording system are water-based inks, and thus have a drawback that the ink has poor drying properties.

[0011] Such ink jet recording paper includes:
Characteristics such as a high ink drying speed, no ink bleeding or overflow, high recording density, and no ripple due to ink absorption are required. It has already been proposed to obtain an ink jet recording paper having these properties by a cast coating method (Japanese Patent Application Laid-Open No. 62-95258,
JP-A-62-264391, JP-A-2-274587
JP-A-5-59694, each gazette, etc.). However, in cast coated paper for ink jet recording, since the main component of the pigment is porous synthetic silica having a large specific surface area, the release accelerating substance is remarkably absorbed as compared with the cast paper using other pigment components, and the breakage of the paper is increased. As the frequency increases, productivity further decreases.

[0012]

Accordingly, the first aspect of the present invention is as follows.
An object of the present invention is to provide a cast coated paper having high productivity and good quality. A second object of the present invention is to provide a method for producing a cast-coated paper having excellent continuous operability and high productivity.

[0013]

SUMMARY OF THE INVENTION The above objects of the present invention are attained by providing a coating liquid containing a pigment and an aqueous binder on at least one surface of a base paper and then dissolving a coagulating agent. The coated surface is subjected to coagulation treatment using, and while the coating layer is in a wet state, the coated layer is pressed against a heated mirror-finished metal surface, and is a cast-coated paper. And a method for producing the same.

The production method of the present invention belongs to the solidification method in the cast coating method. This coagulation method is to apply a coating liquid to the base paper, solidify the coating layer into a gel with no fluidity, and then press the coating layer onto a heated mirror-finished metal surface to form a coating. This refers to a method of copying the mirror surface of the metal surface onto the layer surface. In this case, the coating layer solidifies as a result of the aqueous binder such as casein contained therein being salted out by a salt solution (coagulant).

Conventionally, when a cast-coated paper is produced by a coagulation method, the coagulant is mainly a metal salt of formic acid such as calcium formate or zinc formate because of its high solubility in water and salting out effect. Is commonly used, and ammonium salts have not been used due to low coagulation ability.

However, according to the study of the present inventors, when a metal salt usually used as a coagulant is used, the used metal salt is accumulated on the mirror-finished metal surface, and as a result, the mirror-finished metal is used. While good releasability between the surface and the paper web is impaired and the frequency of paper breakage increases, when an ammonium salt is used as a coagulant, the ammonium salt is thermally decomposed and the base moiety is converted to ammonia in the air. When released as a result of the release of the mirror-finished metal surface and the web, it is not present in a salt form.

Therefore, when an ammonium salt is used as a coagulant, no salt accumulates on the mirror-finished metal surface, so that good releasability between the mirror-finished metal surface and the paper web is maintained, and breakage is achieved. The frequency of paper generation is reduced. Examples of the ammonium salt that can be used as a coagulant in the present invention include ammonium salts such as formic acid, acetic acid, sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid. In the present invention, at least one of these ammonium salts can be selected and used.

When an ammonium salt is used as a coagulant, the ability to coagulate the coating layer is smaller than that of a conventionally used metal salt of formic acid. If the gel state is different from the conventional one, the product quality may be impaired, but if the gel state is made equal to the conventional state by increasing the coagulant concentration, the conventionally used coagulant is used. Good surface gloss and surface strength are obtained as in the case.

The concentration of the ammonium salt as a coagulant is
It is necessary to change according to the use of the cast-coated paper, the formulation of the coating solution and the solid content, the amount of coating, etc., but in the present invention, the quality of the product, the storability, and the continuous operability during production The concentration of the ammonium salt in the coagulating liquid is set to 2 to 40% by weight, preferably 5 to 30% by weight, as long as it has no adverse effect.

In other words, when an ammonium salt is used as a coagulant in such a range, the surface of the coating layer and the structure and properties of the inside of the paper are the same as those obtained by using a conventionally used metal salt such as formic acid. Quality such as glossiness and surface strength is good.
If the concentration of the ammonium salt used is less than 2% by weight, the solidification of the coating liquid is insufficient, and when the metal coating is pressed against a mirror-finished metal surface, part or all of the wet coating liquid is squeezed out. A high gloss coating layer surface, which is a major feature of coated paper, cannot be obtained.

Conversely, when the concentration of the ammonium salt as a coagulant exceeds 40% by weight, thermal decomposition of the ammonium salt during drying does not sufficiently occur and remains on the surface of the dried coating layer, as described above. Not only hurt productivity,
Since ammonia is gradually released from the product, the quality of the product is significantly impaired. In addition, the pH of the paper decreases due to an increase in the amount of the coagulant attached, which may deteriorate the storage stability.

In the present invention, conventionally used coagulants can be used in combination with ammonium salts. Examples of coagulants that can be used in combination with ammonium salts include, for example, acids such as formic acid, acetic acid, citric acid, lactic acid, hydrochloric acid, sulfuric acid, carbonic acid, and boric acid, and calcium, zinc, barium, lead, potassium, sodium, cadmium, and aluminum. And borax. However, when these coagulants are used in combination with ammonium salts, continuous operability may be slightly impaired as compared with the case where ammonium salts are used alone.

Examples of the aqueous binder used in the present invention include starches such as oxidized starch and esterified starch, cellulose derivatives such as carboxymethylcellulose and hydroxyethylcellulose, starch, polyvinyl alcohol resin, polyvinylpyrrolidone, casein and gelatin. Styrene-acrylic resin, styrene-butadiene latex, acrylic resin, vinyl acetate resin, vinyl chloride resin, urea resin, alkyd resin, urethane resin, polyethylene, and derivatives thereof. In the present invention, these water-soluble binders can be appropriately selected and used, and two or more kinds may be used in combination.

The pigment contained in the coating layer of the present invention includes, for example, kaolin, talc, calcium carbonate, calcium acetate, titanium dioxide, clay, zinc oxide, alumina, aluminum hydroxide, amorphous silica, and silica. Synthetic silica such as fixed silica and finely divided silica can be used. In the present invention, at least one of these pigments can be appropriately selected and used. When the cast coated paper of the present invention is used particularly for inkjet recording,
Preferably, 40 to 100% by weight of the pigment used is synthetic silica having a BET specific surface area of 200 to 600 m ² / g, and particularly preferably 250 to 450 m ² / g.

In the present invention, the coating liquid containing at least the pigment and the aqueous binder is usually prepared as an aqueous coating liquid. The mixing ratio of the two at that time varies depending on the composition of the aqueous binder, the composition of the pigment, the coating conditions, etc., provided that the quality satisfies the quality required according to the use of the cast coated paper to be obtained. However, there is no particular limitation. Further, the coating liquid in the present invention, if necessary,
Dispersants, water retention agents, thickeners, defoamers, preservatives, coloring agents, waterproofing agents, wetting agents, drying agents, inducers, plasticizers, fluorescent dyes,
An ultraviolet absorber, a release agent, a lubricant, a cationic polymer electrolyte, and the like may be appropriately added.

As the coating method, blade coater, air knife coater, roll coater, comma coater,
The method can be appropriately selected from methods using a known coating machine such as a brush coater, a kiss coater, a squeeze coater, a curtain coater, a bar coater, and a gravure coater.

In the present invention, when the coating amount of the coating layer is small, a good cast surface may not be obtained,
If the amount is large, poor cast surface due to poor solidification of the wet coating layer may occur, or the amount of water to be evaporated may increase, so that the coating speed must be reduced. Therefore,
It is desirable that the range of the coating amount is 10 to 30 g / m ² , but the size, air permeability, smoothness and basis weight of the base paper, the composition of the coating liquid, the viscosity, the solid content concentration, and other conditions. Can be manufactured outside the above range.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention provides a coating liquid containing a pigment and an aqueous binder, which is applied to at least one surface of a base paper, and then a coagulating liquid in which an ammonium salt is dissolved as a coagulant. The coating surface is coagulated by using, and then, while the coating layer is in a wet state, the coating layer is heated to about 100 ° C. and a mirror-finished metal surface is pressed against a drum having a cylindrical outer surface. Can be implemented.
Incidentally, it is a matter of course that a coating layer may be provided on both sides of the base paper to form a double-sided recording paper.

[0029]

The cast coated paper of the present invention not only has good quality, but also has a remarkable improvement in continuous operability during production, and therefore has excellent productivity. In particular, when 40% by weight or more of the pigment used in the coating layer is made of synthetic silica, it is suitable as an ink jet recording paper.

[0030]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.
In addition, “%” and “part” mean “% by weight” and “part by weight”, respectively, unless otherwise specified.

Preparation of Coating Solution: Coating Solution A 100 parts kaolin as pigment, 10 parts casein (New Zealand), styrene-butadiene latex (manufactured by Nippon Synthetic Rubber Co., Ltd., trade name: JSR-) 0
617) 15 parts, calcium stearate (manufactured by San Nopco Co., Ltd., trade name: Nopcoat SYC) 5 as a release agent
And an aqueous coating solution having a solids concentration of 45%, comprising 0.5 part of an antifoaming agent and 0.5 part of an antifoaming agent.

Coating liquid B 100 parts of kaolin as a pigment, 10 parts of casein (from New Zealand), and styrene-butadiene latex (manufactured by Nippon Synthetic Rubber Co., Ltd., trade name: JSR-0) as a binder
617) 30 parts, calcium stearate (manufactured by San Nopco Co., Ltd., trade name: Nopcoat SYC) 5 as a release agent
And an aqueous coating solution having a solids concentration of 45%, comprising 0.5 part of an antifoaming agent and 0.5 part of an antifoaming agent.

Coating liquid C 80 parts of kaolin, 20 parts of calcium carbonate, 10 parts of casein (from New Zealand) as a pigment, and styrene-butadiene latex (Nippon Synthetic Rubber Co., Ltd.) as a binder
(Trade name: JSR-0617), 5 parts of calcium stearate (manufactured by San Nopco Co., Ltd., trade name: Nopcoat SYC) as a release agent, and 0.5 part of an antifoaming agent. A 45% aqueous coating solution was prepared.

Coating liquid D Synthetic silica as a pigment (Mizukasil P-87, manufactured by Mizusawa Chemical Co., Ltd., BET specific surface area: 320 m ² / g)
100 parts by weight, styrene-butadiene latex (manufactured by Nippon Synthetic Rubber Co., Ltd., trade name: JSR-06) as a binder
17) 10 parts by weight, casein (from New Zealand) 3
0 parts by weight and calcium stearate (manufactured by San Nopco Co., Ltd., trade name: Nopcoat SYC) 5 as a release agent
An aqueous coating solution having a concentration of 30% and containing parts by weight was prepared.

Coating liquid E Synthetic silica as a pigment (Mizukasil P-87, manufactured by Mizusawa Chemical Co., Ltd., BET specific surface area: 320 m ² / g)
40 parts by weight, and 60 parts by weight of columnar calcium carbonate (trade name: Tamapearl # 123, manufactured by Okutama Industry Co., Ltd.)
10 parts by weight of styrene-butadiene latex (manufactured by Nippon Synthetic Rubber Co., Ltd., trade name: JSR-0617), 30 parts by weight of casein (New Zealand), and calcium stearate (manufactured by San Nopco Co., Ltd.) as a release agent (Trade name: Nopcoat SYC) An aqueous coating solution having a concentration of 30% and containing 5 parts by weight was prepared.

Coating liquid F Synthetic silica as a pigment (manufactured by Fuji Devison Chemical Co., Ltd.)
Product name: Syloid 800, BET specific surface area 600m
² / g) 100 parts by weight, styrene-butadiene latex (manufactured by Nippon Synthetic Rubber Co., Ltd., trade name: JS) as a binder
R-0617) 10 parts by weight, casein (from New Zealand) 30 parts by weight, and calcium stearate (manufactured by San Nopco Co., Ltd., trade name: Nopcoat SY) as a release agent
C) A 30% concentration aqueous coating solution containing 5 parts by weight was prepared.

Coating liquid G Synthetic silica (Mizukasil P-802, manufactured by Mizusawa Chemical Co., Ltd., BET specific surface area 180 m ² /
g) 100 parts by weight, styrene-butadiene latex (manufactured by Nippon Synthetic Rubber Co., Ltd., trade name: JSR-
0617) 10 parts by weight, casein (from New Zealand) 30 parts by weight, and calcium stearate (manufactured by San Nopco Co., Ltd., trade name: Nopcoat SY) as a release agent
C) A 30% concentration aqueous coating solution containing 5 parts by weight was prepared.

Preparation of coagulating solution: coagulating solution 10% ammonium sulfate and a release agent (Nopcoat S
A coagulation solution consisting of 0.5% of YC) was prepared.・ Coagulating liquid Ammonium formate 10% and release agent (Nopcoat S
A coagulation solution consisting of 0.5% of YC) was prepared.・ Coagulation liquid Ammonium sulfate 20% and release agent (Nopcoat S
A coagulation solution consisting of 0.5% of YC) was prepared.

Coagulation liquid 10% calcium formate and a release agent (Nopcoat SY
C) A coagulation solution consisting of 0.5% was prepared.・ Coagulation liquid 10% zinc sulfate and release agent (Nopcoat SYC)
A coagulation solution consisting of 0.5% was prepared.

Embodiment 1 The coating liquid A was applied to one side of the base paper using a comma coater so that the coating amount was 18 g / m ^2, and then coagulated with a coagulating liquid. The coating was pressed on a mirror surface heated to ° C. and dried to produce a cast-coated paper.

Embodiment 2 FIG. The coating liquid B was applied to one side of the base paper using a comma coater so that the coating amount was 18 g / m ^2, and then coagulated with a coagulating liquid. The coating was pressed on a mirror surface heated to ° C. and dried to produce a cast-coated paper.

Embodiment 3 FIG. The coating liquid C was applied to one side of the base paper using a comma coater so that the coating amount was 18 g / m ^2, and then coagulated with a coagulating liquid to obtain 100 g while the coating layer was in a wet state. The coating was pressed on a mirror surface heated to ° C. and dried to produce a cast-coated paper.

Embodiment 4 FIG. The coating liquid A was applied to one side of the base paper using a comma coater so that the coating amount was 18 g / m ^2, and then coagulated with a coagulating liquid to obtain 100 g while the coating layer was in a wet state. The coating was pressed on a mirror surface heated to ° C. and dried to produce a cast-coated paper.

Embodiment 5 FIG. The coating liquid A was applied to one side of the base paper using a comma coater so that the coating amount was 18 g / m ^2, and then coagulated with a coagulating liquid to obtain 100 g while the coating layer was in a wet state. The coating was pressed on a mirror surface heated to ° C. and dried to produce a cast-coated paper.

Comparative Example 1 The coating liquid A was applied to one side of the base paper using a comma coater so that the coating amount was 18 g / m ^2, and then coagulated with a coagulating liquid to obtain 100 g while the coating layer was in a wet state. The coating was pressed on a mirror surface heated to ° C. and dried to produce a cast-coated paper.

Comparative Example 2 The coating liquid C was applied to one side of the base paper using a comma coater so that the coating amount was 18 g / m ^2, and then coagulated with a coagulating liquid to obtain 100 g while the coating layer was in a wet state. The coating was pressed on a mirror surface heated to ° C. and dried to produce a cast-coated paper.

Comparative Example 3 The coating liquid A was applied to one side of the base paper using a comma coater so that the coating amount was 18 g / m ^2, and then coagulated with a coagulating liquid to obtain 100 g while the coating layer was in a wet state. The coating was pressed on a mirror surface heated to ° C. and dried to produce a cast-coated paper.

Comparative Example 4 The coating liquid C was applied to one side of the base paper using a comma coater so that the coating amount was 18 g / m ^2, and then coagulated with a coagulating liquid to obtain 100 g while the coating layer was in a wet state. The coating was pressed on a mirror surface heated to ° C. and dried to produce a cast-coated paper.

Continuous operability, evaluation strength of coating layer, and pH of coating layer surface in Examples 1 to 5 and Comparative Examples 1 to 4
Are evaluated according to the following evaluation criteria, and the results are as shown in Table 1.

[Table 1] The above results prove the effectiveness of the present invention.

I) Continuous operability: Continuous coating time (coating length)
Were compared with each other based on Comparative Example 1. The larger the value is, the more excellent the continuous operability is. When the value is 1.4 or more, the effect of improving the continuous operability is remarkable. ii) Surface glossiness of coating layer: The surface glossiness of the coating layer, which is the greatest feature of cast coated paper, is determined according to JIS P-81.
The 75 ° gloss was measured and evaluated according to 42. iii) pH on the surface of the coating layer: As described above, an acid that adversely affects the storage stability of the cast-coated paper may remain on the coating layer or in the coating layer due to excessive adhesion of the coagulant. TAPPI UM-47
Measured and evaluated according to 1. PH of coating layer surface is 6 ~
Within the range of 8, there is no problem in the storage stability of the cast coated paper.

Embodiment 6 FIG. The coating liquid D was applied to one side of the base paper using a comma coater so as to have a target coating amount of 18 g / m ^2, and then 10% by weight of ammonium sulfate as a coagulant and cationic polymer electrolyte ( Daiwa Chemical Co., Ltd., trade name: Difix YK-50) Coated with a coagulating liquid containing 1% by weight, and a mirror-finished metal surface heated to 100 ° C. while the coating layer is in a wet state. And dried to produce a cast-coated paper for inkjet recording.

Embodiment 7 FIG. A cast coated paper for inkjet recording was produced in exactly the same manner as in Example 6, except that the amount of ammonium sulfate used as a coagulant was changed to 20% by weight.

Embodiment 8 FIG. A cast coated paper for inkjet recording was produced in exactly the same manner as in Example 6, except that the amount of the coating liquid D and ammonium sulfate used as a coagulant was changed to 30% by weight.

Embodiment 9 FIG. Except that the amount of ammonium sulfate used as a coagulant was changed to 40% by weight, a cast-coated paper for inkjet recording was produced in exactly the same manner as in Example 6.

Embodiment 10 FIG. Except that the amount of ammonium sulfate used as a coagulant was 5% by weight, a cast-coated paper for inkjet recording was produced in exactly the same manner as in Example 6.

Embodiment 11 FIG. Except for using ammonium formate as a coagulant instead of ammonium sulfate, a cast-coated paper for inkjet recording was produced in exactly the same manner as in Example 6.

Embodiment 12 FIG. Coating liquid E instead of coating liquid D
A cast-coated paper for ink jet recording was manufactured in exactly the same manner as in Example 6 except that was used.

Embodiment 13 FIG. Coating liquid F instead of coating liquid D
A cast-coated paper for ink jet recording was manufactured in exactly the same manner as in Example 6 except that was used.

Comparative Example 5 Except that calcium formate was used in place of ammonium sulfate, a cast coated paper for inkjet recording was produced in exactly the same manner as in Example 6.

Comparative Example 6 Except that zinc formate was used in place of ammonium sulfate, a cast coated paper for inkjet recording was produced in exactly the same manner as in Example 6.

Comparative Example 7 Reduce the amount of ammonium sulfate used by 1
A cast-coated paper for ink-jet recording was manufactured in exactly the same manner as in Example 6, except that the amount was changed to wt%.

Comparative Example 8 Reduce the amount of ammonium sulfate used to 5
Except that the amount was 0% by weight, a cast-coated paper for inkjet recording was manufactured in exactly the same manner as in Example 6.

Comparative Example 9 A cast-coated paper for inkjet recording was manufactured in exactly the same manner as in Example 1 except that the coating liquid G was used instead of the coating liquid D.

In the above Examples 6 to 13 and Comparative Examples 5 to 9, the suitability for ink-jet recording, the continuous operability during production (based on Comparative Example 5), and the glossiness of the coating layer surface were evaluated as described above. Table 2 shows the results of evaluation by standard and odor from the product by the following evaluation standard.

[Table 2] The above results demonstrate the effectiveness of the present invention.

I) Recording suitability: Focusing on the recording suitability for the ink jet recording method, particularly focusing on the ink absorbency of the cast-coated paper for ink jet recording, a black solid is recorded by the full color ink jet recording method, and the ink absorbency is determined as follows. It was visually evaluated according to the standard. No defects are observed after recording. ... ○ After recording, some defects were observed, but the lower limit of recording quality was maintained.・ ・ ・ 欠 点 After recording, defects are clearly recognized. ... ×

Ii) Odor of the product: Sensory evaluation was performed according to the following criteria. No odor is felt from the product.・ ・ ・ ○ Slight odor is felt from the product, but the quality of the product can be maintained.・ △ Odor is felt from the product, and it is impossible to maintain product quality. ... ×

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yoshihiro Kuroyama 1-30-6 Kamiochiai, Shinjuku-ku, Tokyo Nippon Paper Industries Co., Ltd. (56) References JP-A-4-126889 (JP, A) (58) Survey Field (Int.Cl. ⁶ , DB name) D21H 1/22

Claims (5)

(57) [Claims] 1. A coating solution containing a pigment and an aqueous binder is applied to at least one surface of a base paper, and then the coated surface is solidified using a coagulating solution in which a coagulant is dissolved. Cast coated paper obtained by pressing the coated layer to a heated mirror-finished metal surface while in a wet state, wherein an ammonium salt is used as a coagulant. . 2. 40 to 100% by weight of the pigment in the coating liquid
Is a cast silica coated paper according to claim 1, which is a synthetic silica having a BET specific surface area of 200 to 600 m ² / g. 3. The cast-coated paper according to claim 1, wherein the coagulant is ammonium formate and / or ammonium sulfate. 4. A coating solution containing a pigment and an aqueous binder is applied to at least one surface of a base paper, and then coagulated using 2 to 40% by weight of an ammonium salt. A method for producing cast coated paper, characterized in that the coated layer is pressed against a heated mirror-finished metal surface while in a wet state. 5. The method for producing a cast-coated paper according to claim 4, wherein a synthetic silica having a BET specific surface area of 200 to 600 m ² / g is used as 40 to 100% by weight of the pigment in the coating liquid. .