JPH08226095A - Production of cast coated paper - Google Patents

Abstract

PURPOSE: To provide a method for producing cast-coated paper especially having high luster, free from irregular luster and pine holes, and excellent in printing suitability at a high speed. CONSTITUTION: This method for producing a cast-coated paper comprises coating an aqueous coating material containing a pigment and an adhesive as main components on base paper, drying the coating layer, treating the coating layer with a rewetting solution to plasticize the coating layer, and subsequently bringing the coating layer into contact with the surface of a heated drum to finish the surface of the coated paper into a strongly lustrous surface. In the method, the aqueous coating material is especially compounded with structured kaolin as a pigment and with at least one of the salts of metals consisting of zinc, aluminum, magnesium and calcium as an auxiliary agent.

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 a cast coated paper, and more particularly to a method for producing a cast coated paper which has high gloss, has no gloss unevenness and pinholes, and has excellent printability at high speed. It is a thing.

[0002]

2. Description of the Related Art Cast coated papers are widely used as high-grade printing papers because they have very high surface gloss, excellent smoothness, and excellent printability. As a method for producing a cast coated paper, a wet coating layer is applied by a wet casting method in which a heated drum surface having a mirror surface is pressed to give a glossy finish, and the wet coating layer is once dried and then rewetted. Rewet casting method that wets with a liquid and plasticizes it, then press-contacts the surface of the heating drum to give a gloss finish,
Further, a gelling casting method is generally known in which a wet coating layer is put into a gel state and then pressed against a heating drum surface to give a gloss finish. These cast finishing methods are
All of them have a common point in that the surface of the coating layer in a wet plastic state is pressed against the surface of the heating drum, dried, and released to take a mirror surface.

In such a method for producing cast coated paper, since the coated layer is dried by contacting the surface of the heating drum, all the water in the coated layer or the water in the rewetting liquid is in the paper layer. After passing through, it will escape to the non-cast surface side and evaporate. If the evaporation rate becomes high enough to exceed a certain limit,
A part of the water in the coating layer and the rewetting liquid tends to evaporate toward the mirror drum surface. As a result, pinholes and gloss unevenness occur on the surface of the obtained cast coated paper, and the quality tends to be remarkably deteriorated, and in order to suppress it, the drum temperature and the production speed are naturally limited. It will be. Therefore,
In the production of cast coated paper, it is the current situation that it is forced to operate at an extremely low speed as compared with general art paper and coated paper that are dried from both sides of the paper.

Among the above-mentioned cast finishing methods, the gelling casting method and the rewet casting method are both gelled or dried before the cast coating layer is pressed against the mirror-finished drum surface. Can be pressed against a mirror-drum surface having a relatively high temperature of 90 ° C. or higher for cast finishing. Therefore, compared to the wet casting method, the two can strengthen the drying, so that the casting finish can be performed at a higher speed, which is excellent in productivity.

By the way, in the gelling casting method, the wet paint provided on the cast base paper is gelated by the coagulating liquid treatment, and then it is brought into pressure contact with the heating mirror surface drum surface to finish the casting. Since the drying process is not performed before, the additional energy required for drying on the heating drum surface is relatively high, and since the coagulation treatment is performed immediately before the casting finish, a sufficient coagulation action cannot be obtained, and the surface by the coagulant is not obtained. There is concern about a decrease in strength and a decrease in gloss.

On the other hand, in the rewet casting method, compared with other casting methods, the plasticizing of the coating layer before pressure contact with the heated mirror surface drum surface is low, so that it is difficult to uniformly adhere to the mirror surface drum surface. Therefore, although cast coated paper with relatively uniform gloss and printability can be obtained under low speed operation, the gloss decreases as high speed operation occurs, causing pinhole-like spots and uneven gloss. It will be easier. Conventionally, hexagonal plate-shaped hydrous kaolin has been used as one of the pigments constituting the cast coating layer. This hydrous kaolin has a strong tendency to be aligned side by side inside and on the surface of the coating layer, so it is excellent in smoothness improvement, white paper gloss, and expression of ink gloss, but on the other hand, since the coating layer becomes dense, moisture Air permeability deteriorates, pinholes and gloss unevenness are more likely to occur, and this is one of the causes of productivity drop.

Therefore, as a method for improving the production rate of cast coated paper, aluminum hydroxide, titanium dioxide, barium sulfate, calcium sulfite, which have good moisture permeability,
It is known to use zinc oxide, light calcium carbonate, heavy calcium carbonate, etc. in the form of rice grains, spindles, spheres, and amorphous particles in combination with hydrous kaolin, or alone. However, although the use of such a pigment is effective in improving the air permeability of water, on the other hand, the glossiness of the white paper surface, which is a characteristic of cast coated paper, is significantly reduced, and the ink gloss is also reduced in terms of printability. There is a drawback. Therefore, various proposals have been made in order to eliminate the drawbacks of the rewet casting method.

For example, in Japanese Examined Patent Publication No. 1-28155, cubic calcium carbonate having an average particle diameter of 0.1 to 1.0 μm is added.
In particular, there has been proposed a method for obtaining a continuous productivity by using the rewet casting method or the gelling casting method to reduce the decrease in gloss. However, with this method, the productivity, uneven gloss, pinholes, etc. are improved with an increase in the blending ratio of the cubic calcium carbonate, but the gloss and ink gloss of the paper surface are reduced accordingly. Therefore, when using conventional hydrous kaolin and cubic calcium carbonate together, increase the ratio of hydrous kaolin when emphasizing the gloss and ink gloss of the paper, and cubic carbonic acid when emphasizing productivity and whiteness. There is no choice but to take measures to increase the ratio of calcium.

Further, JP-A-1-118691 discloses that by using hydrous kaolin having an average particle size of 0.5 μm or less and columnar or acicular calcium carbonate having an average particle size of 1 to 3 μm, a rewet casting method or a gelling casting method is particularly used. A method of increasing the gloss and obtaining high productivity has been proposed. However, even though this method is excellent in terms of gloss unevenness, pinholes, and productivity, it is still inadequate in terms of gloss and ink gloss, as compared with a 100% kaolin product.

Further, Japanese Patent Application Laid-Open No. 4-174796 discloses that
Although it has been proposed to use fibrous calcium carbonate having a long diameter of 4 to 100 μm and a short diameter of 0.1 to 3.0 μm,
Even in this case, the white paper gloss and the ink gloss are inferior to those of the product containing only the hydrous kaolin.

In the process for producing a cast coated paper having high gloss and no pinholes or uneven gloss, it is necessary to solve the above-mentioned quality problems and achieve stable operation at high speed. The reality is that is difficult.

[0012]

DISCLOSURE OF THE INVENTION The present invention provides a method for producing cast coated paper, in particular, by efficiently eliminating pinholes and uneven gloss, which have been difficult to cope with in the prior art, and has improved paper gloss and smoothness. It is intended to provide a method for producing a cast coated paper capable of stably producing an excellent high quality cast coated paper at a high speed.

[0013]

Based on the above situation, the inventors of the present invention aim to obtain a cast coated paper, particularly a rewet cast system, which is excellent not only in operability but also in quality. We have earnestly studied. As a result, the present invention applies a water-based paint containing a pigment and an adhesive as a main component onto a base paper, and after providing a coating layer by drying, the coating layer is treated with a rewetting liquid to wet it, After plasticizing, in a method for producing a cast coated paper which is pressed against a heated drum surface to give a strong gloss finish, structured kaolin is compounded as a pigment in the water-based paint, and zinc, aluminum, magnesium, or At least one metal salt of calcium is added to the method for producing cast coated paper.

[0014]

According to the present invention, the base paper is preliminarily coated with a water-based paint containing a pigment and an adhesive as main components and dried to form a cast coating layer, and then the cast coating layer is treated with a rewetting liquid. In a method for producing a cast coated paper in which a highly glossy finish is obtained by press-contacting a heated mirror surface drum and releasing after moistening and plasticizing, structured kaolin is used as a pigment in the aqueous paint,
The method for producing cast coated paper is characterized by containing at least one selected from salts of zinc, aluminum, magnesium or calcium as an auxiliary agent.

A major feature of the present invention is the use of structured kaolin as the pigment used in the cast coating layer. Here, the structured kaolin is a bulky aggregate obtained by increasing the porosity and chemically aggregating the fine grain clay from the hexagonal plate-like dense state of the hydrous kaolin before the structuring. As kaolin which is a bulky aggregate, there is another calcined kaolin. This calcined kaolin is obtained by calcining hydrous kaolin at a high temperature of 900 ° C. or higher to melt and fuse the surface of each particle into an aggregate having a void structure. However, this calcined kaolin has a problem in dispersibility, and when it is used as a pigment in a water-based paint for cast coated paper, it is difficult to obtain a uniform coated layer, and the obtained cast coated paper is obtained. Has a significantly low gloss on white paper,
Further, it has a drawback that the printing strength is also lowered.

On the other hand, structured kaolin is a structure having a void structure by chemically aggregating fine clay, and is stabilized by, for example, a urea / formalin polymer described in JP-B-59-15944. Structured agglomerates, kaolin agglomerated by zirconium treatment described in JP-A-62-1757, JP-A-62-267
Hydrated kaolin aggregated with the cationic polyelectrolyte aggregating agent described in No. 371, aggregates obtained by precipitating hydrous metal silicate particles described in Japanese Patent Publication No. 63-500723 on clay, and the like. . Specific structured kaolins include, for example, EXIRON90 (manufactured by EMC, USA), ASTRA PLUS (manufactured by ECC, USA), and LI.
Examples include THO PRINT (manufactured by HUBER, USA) and the like.

The structured kaolin produced by the method as described above is effective for producing a bulky coating layer because it has a void structure. Further, since the structured kaolin is generally bound by a polymer, it can be used in the calender. The treatment deforms the structure, improves the surface smoothness while maintaining the bulkiness of the coating layer, and imparts excellent gloss. For this reason, when structured kaolin is used in a water-based paint that forms a coating layer, an opacity improving effect as a titanium dioxide substitute and a blister resistance improving effect can be expected, and ink gloss is excellent because of excellent smoothness. It is also possible to improve. Furthermore, due to being structured, the required amount of adhesive can be reduced, and the viscosity of the paint can be reduced.
When applied to a water-based paint forming a coating layer for general art and coated paper, the quality and productivity can be effectively improved.

The cast coated paper is very excellent in surface smoothness, gloss, ink gloss and the like as compared with general art paper, coated paper and the like, but it is water-based which constitutes the coating layer of the cast coated paper. Simply using structured kaolin in the paint,
The effect of improving the quality characteristics as described above cannot be expected.
That is, the cast-coated paper exhibits gloss and smoothness by film-forming substances such as adhesives copying the mirror surface of the cast drum. For this reason, cast coated paper has more adhesive added to the water-based paint compared to general art paper and coated paper, and when structured kaolin is used in the water-based paint for casting, the coating of the water-based paint, In the process of forming the coating layer during drying, there is a strong tendency that the void structure is filled with an adhesive such as latex. Therefore, the porosity of the coating layer is lowered, and like the hydrous kaolin, it is easily oriented not only in the surface layer but also in the coating layer. Therefore, the characteristic of structured kaolin, which has good air permeability, cannot be utilized, and the cast-finished coated paper is
Compared with the one using hydrous kaolin, the improvement effect for eliminating pinholes and uneven gloss can hardly be expected.

Therefore, the present inventors have conducted extensive studies on a method of maintaining and utilizing the characteristics of structured kaolin, that is, a method of making the coating layer bulky and maintaining good air permeability. As a result, by using a specific metal salt together with the structured kaolin in the water-based coating, it was found that the excellent effect desired by the present invention can be obtained without losing the characteristics of the structured kaolin, The present invention has been completed.

Although the action of the metal salt is not clear, it is presumed as follows. That is, in the process of coating the base paper with the water-based paint and drying it to form a coating layer, the metal salt penetrates into the void structure of the structured kaolin in order to accelerate immobilization of the coating layer. Is suppressed and the orientation tendency of the structured kaolin in the coating layer is suppressed, so that the entire coating layer is kept porous. as a result,
It is presumed that vapor is likely to dissipate in the process of drying the paint on the heated drum surface, and pinholes and uneven glossiness can be effectively eliminated.On the other hand, the degree of orientation inside the coating layer is low. Since the surface of the coating layer is strongly pressed against the surface of the heating drum by a press roll, its structure changes and it is easy to orient, and it is presumed that a cast coated paper with excellent white paper gloss and ink gloss can be obtained. It

Further, it has been found that the cast coated paper obtained by the present invention has excellent paper surface gloss and ink gloss, and also has a fast ink setting (fast ink drying). By the way, when the structured kaolin is used in the water-based paint without using the metal salt together, the structured kaolin is oriented in the surface layer of the coating layer and is excellent in gloss and ink gloss, but also in the inside of the coating layer. The tendency to orient is strong and the ink set is inferior (ink drying is slow). On the other hand, in the case of using only metal salt without using structured kaolin, the coating layer becomes bulky and the air permeability is excellent, so the ink setting becomes faster, which is a desirable tendency, but the surface gloss and ink gloss decrease. To do. However, the cast coated paper obtained by the present invention has excellent white paper gloss and ink gloss due to the orientation of the structured kaolin on the coating layer surface, and the action of the metal salt inside the coating layer. Because of this, the degree of orientation is suppressed low and the porous state is maintained. Therefore, it has the feature that the ink setting is quick.

That is, according to the present invention, by using a specific metal salt as an auxiliary agent and structured kaolin as a pigment,
For the first time, the present invention provides a method capable of efficiently eliminating pinholes and gloss unevenness, and producing cast coated paper excellent in white paper gloss, ink gloss, and ink setting property (fast setting) with high efficiency.

Here, as the specific metal salt, at least one metal salt selected from zinc, aluminum, magnesium, or calcium is used. And
The specific metal salt is in the form of any of sulfate, nitrate, acetate, or formate, and zinc sulfate, calcium sulfate, magnesium sulfate, calcium formate, calcium acetate, etc. are preferably used. It

The addition amount of the metal salt is adjusted in the range of about 0.5 to 10 parts by weight with respect to 100 parts by weight of the pigment. By the way, if it is less than 0.5 parts by weight, sufficient ink drying property cannot be obtained, while if it exceeds 10 parts by weight, the viscosity of the water-based paint may increase and the printing strength of the product may decrease. .

The amount of structured kaolin used is as follows.
It is desirable to add 20% by weight or more, preferably 30% by weight or more, based on the solid content to all pigments. By the way, 20
If it is less than 10% by weight, the characteristics of the structured kaolin, such as bulkiness and air permeability, which are characteristics of the structured kaolin, cannot be fully exhibited, and pinholes and uneven gloss may occur in the obtained product during high-speed operation.

In the present invention, the structured kaolin is used as the pigment used in the aqueous paint for forming the coating layer of the cast coated paper as described above.
For example, ordinary kaolin, clay, calcined clay, amorphous silica, zinc oxide, used in the general coated paper manufacturing field,
Aluminum oxide, aluminum hydroxide, barium sulfate, light calcium carbonate, heavy calcium carbonate, talc, satin white, titanium dioxide, aluminum silicate, magnesium silicate, magnesium carbonate, diatomaceous earth, styrene plastic pigment, urea resin plastic pigment, benzoguanamine Various publicly known and used pigments such as plastic pigments can be appropriately used in combination.

Next, as an adhesive used for the water-based paint, proteins such as casein, soybean protein, conjugated diene polymer latex of styrene-butadiene copolymer, acrylic polymer latex, ethylene-vinyl acetate are used. Vinyl-based polymer latex such as vinyl-based polymer such as copolymer,
Alternatively, these various polymers are modified with functional group-containing monomers such as carboxyl groups to functionally modified alkali-soluble or alkali-insoluble polymer latex, polyvinyl alcohol, olefin-maleic anhydride resin, melamine resin, etc. Synthetic resin-based adhesives, as well as starches such as cationized starch, oxidized starch and esterified starch, cellulose derivatives such as carboxymethyl cellulose and hydroxymethyl cellulose, and other publicly known adhesives for general coated paper, alone or in combination. Can be used. The amount of the adhesive used is 5 to 100 parts by weight of the pigment based on the solid content.
The amount is adjusted to 50 parts by weight, generally 10 to 30 parts by weight.

Furthermore, in addition to the above-mentioned specific metal salt, an antifoaming agent, a coloring agent, a release agent, a flow modifier, a water-proofing agent, a preservative, etc. are appropriately added to the water-based paint as an auxiliary agent. It

Aqueous paints for cast coating layers composed of the above-mentioned materials generally have a solid content of 20 to 7
It is prepared to about 0% by weight, and the weight of rice is about 20 to 400 g / m 2.
^A blade coater, an air knife coater, a roll coater, a brush coater, a chanplex coater, a bar coater, or a dry coater having a dry weight of about 10 to 50 g / m ² , preferably about 20 to 30 g / m ^{2 on} about ² base papers, or The base paper is coated using various publicly known coating devices such as a gravure coater and then dried.

According to the above, after the aqueous coating material for cast coating layer is coated on the base paper and dried, the rewet casting method, that is, the dry coating layer is rewetted by the wetting liquid and plasticized and then heated to the mirror surface drum The surface is pressed to give a glossy finish.
Of course, it is also effective to perform smoothing treatment such as super calendering or brushing before rewetting the dry coating layer.

The rewetting liquid is not particularly limited, but generally, as a releasing agent, for example, polyethylene emulsion, metal salt of fatty acid or its derivative, microcrystalline wax, funnel oil, etc. are dissolved or dispersed in water. The liquid (concentration 0.5 to 3% by weight) is used as appropriate. Further, a phosphate such as sodium hexametaphosphate, an organic acid, a salt of an organic acid or the like may be used in combination for promoting wetting and plasticization of the dry coating layer.

In the method of the present invention, as described above, the coating layer can be made porous by using the structured kaolin and the metal salt together in the water-based coating. An index showing the porosity of this coating layer. For example, the air permeability of the coated paper can be raised. In the present invention, the air permeability of the dry coated paper before rewetting is JI.
It is particularly desirable that the finish is 700 seconds or less (the lower the value, the better the air permeability and the porosity) by the method according to SP-8117. When the above air permeability is satisfied, the properties of the structured kaolin are fully exhibited. By the way, as a method of setting the air permeability to 700 seconds or less, the required air permeability can be obtained by appropriately combining the base paper preparation method, the pigment composition to be added to the water-based paint, and the type and amount of the adhesive. You can

In the present invention, the base paper used is not particularly limited, and acidic paper or neutral paper used for general coated paper is appropriately used. If necessary, one or both sides of the base paper may be pre-coated with a general pigment coating composition, and if necessary, this pre-coated base paper may be pre-coated in advance with a supercapacitor. Smoothing processing such as rendering, brushing, and cast finishing can also be performed.

[0034]

The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. Unless otherwise specified, “parts” and “%” in the examples and comparative examples represent “parts by weight” and “% by weight”, respectively.

Example 1 70 parts of structured kaolin (trade name: EXIRON 90 / manufactured by EMC, USA) and light calcium carbonate (trade name: Brilliant S-15 / manufactured by Shiraishi Kogyo Co., Ltd.) 30 as an aqueous paint to be coated on a base paper. Parts, 8 parts of a 15% casein aqueous solution dissolved in ammonia (solid content), 16 parts of SBR latex (solid content), and 2 parts of zinc sulfate to prepare a cast coating liquid having a concentration of 48%. The coating liquid was coated on a base paper having a basis weight of 64 g / m ^{2 with} a dry weight of 20 g / m ² by using an air knife coater and then dried by an air floating dryer.

Next, this coated paper is passed through a press nip formed by a press roll and a heating cast drum, and a rewetting liquid (1.0% concentration) composed of a polyethylene emulsion supplied from a nozzle to this nip portion. )) To re-wet the surface of the coated paper and plasticize it, then press-contact with a heated cast drum surface (surface temperature 105 ° C) at a running speed of 70 m / min at a press pressure of 200 kg / cm, dry, and then peel from the drum. By doing so, a cast coated paper was obtained.

Example 2 In Example 1, the structured kaolin was treated with ASTRA PL
A cast coated paper was obtained in the same manner as in Example 1 except that US (trade name / manufactured by ECC, USA) was used.

Example 3 In Example 1, the structured kaolin was mixed with LITHO PR.
A cast coated paper was obtained in the same manner as in Example 1 except that INT (trade name / manufactured by HUBER, USA) was used.

Example 4 In Example 1, the structured kaolin (EXIRON9
A cast coated paper was obtained in the same manner as in Example 1 except that the compounding number of 0) was changed to 100 parts and light calcium carbonate was not added.

Example 5 A cast coated paper was obtained in the same manner as in Example 1, except that the addition number of zinc sulfate was changed to 0.5 part.

Example 6 A cast coated paper was obtained in the same manner as in Example 1 except that the addition number of zinc sulfate was changed to 5.

Example 7 A cast coated paper was obtained in the same manner as in Example 1 except that zinc sulfate was changed to magnesium sulfate.

Example 8 A cast coated paper was obtained in the same manner as in Example 1 except that the zinc sulfate was changed to calcium formate.

Example 9 A cast coated paper was obtained in the same manner as in Example 1 except that zinc sulfate was changed to aluminum nitrate.

Comparative Example 1 In Example 1, hydrous kaolin containing structured kaolin (trade name: ULTRA WHITE 90 / manufactured by EMC, USA).
A cast coated paper was obtained in the same manner as in Example 1 except that the content was changed to.

Comparative Example 2 A cast coated paper was obtained in the same manner as in Example 1 except that the structured kaolin was changed to hydrous kaolin (trade name: ULTRA COAT / manufactured by EMC, USA).

Comparative Example 3 A cast coated paper was obtained in the same manner as in Example 1 except that calcined kaolin (trade name: ANSILEX / manufactured by EMC, USA) was used instead of structured kaolin.

Comparative Example 4 In Example 1, hydrous kaolin containing structured kaolin (trade name: ULTRA WHITE 90 / manufactured by EMC, USA).
Was changed to 100 parts and the light calcium carbonate was not added to obtain a cast coated paper in the same manner as in Example 1.

Comparative Example 5 A cast coated paper was obtained in the same manner as in Example 1 except that the number of metal salt (zinc sulfate) parts in the water-based paint was not added.

The pinholes, gloss unevenness, white paper gloss, ink gloss, ink setting and maximum operable speed of the obtained cast coated paper were evaluated by the following methods. In addition, the air permeability of the coated paper before rewetting in each of Examples and Comparative Examples is J
Measurements were made according to IS-P-8117 and are summarized in Table 1.

(Pinhole) The surface of the cast coated paper was observed with a stereoscopic microscope and judged according to the following criteria. ⊚: There are less than 10 pinholes in 1 cm ² . ◯: About 10 to 20 pinholes exist in 1 cm ² . B: About 20 to 50 pinholes exist in 1 cm ² , which is practically impossible. X: 50 or more pinholes exist in 1 cm ² .

(Gloss unevenness) The gloss unevenness of the surface of the cast coated paper was judged according to the following criteria. ⊚: The surface is uniform without gloss unevenness. ◯: Gloss unevenness is slightly observed, but there is no problem in practical use. Δ: Uneven gloss is observed, which is practically impossible. X: The gloss unevenness is remarkable.

(Glossy of white paper) It was measured according to JIS P8142.

(Ink gloss) A sheet offset ink (G
Raf-G (black ink, made by Dainippon Ink) 0.2cc was used to print on the surface of the cast coated paper, and after being left for 24 hours, a gloss checker (IG-310, manufactured by Horiba Ltd.) was applied to give a gloss of 60 °. It was measured.

(Ink set) A sheet offset ink (F
-Gloss (manufactured by Dainippon Ink and Chemicals) 0.6 cc was used to print on the surface of the cast coated paper, and immediately after printing, 2 minutes after printing, and 5 minutes after printing, fine quality was obtained on the surface of the cast coated paper. The papers were overlapped and pressed with a constant pressure, and the density of the ink transferred to the high-quality paper was judged according to the following criteria. A: Ink hardly transferred after 2 minutes. ◯: The ink hardly transferred after 5 minutes. Δ: The transfer density after 5 minutes is about half of the ink transfer density immediately after printing, which is a problem in practical use. X: The transfer density after 5 minutes is slightly thin with respect to the ink transfer density immediately after printing, which is a problem in practical use.

(Operating Speed) When the cast coated paper is produced by the above method, the cast coated paper does not stick to the cast drum or a drum pick does not occur, and the maximum speed at which stable operation is possible ( m / min).

[0057]

[Table 1]

[0058]

As is apparent from Table 1, the cast coated paper obtained by the method of the present invention has high gloss, is free from uneven gloss and pinholes, and has excellent printability. And was able to be produced at high speed.

Claims (3)

[Claims] 1. A base paper is coated with an aqueous paint containing pigments and adhesives as main components, dried to form a coat layer, and the coat layer is treated with a rewetting liquid to wet and plasticize. Then, in a method for producing a cast coated paper which is pressed against a heating drum surface to give a strong gloss finish, structured kaolin is blended as a pigment in the aqueous paint, and zinc, aluminum, magnesium or calcium is used as an auxiliary agent. A method for producing cast coated paper, characterized in that at least one of the following metal salts is added. 2. The method for producing cast coated paper according to claim 1, wherein the metal salt comprises zinc sulfate, calcium sulfate, magnesium sulfate, calcium formate, and calcium acetate. 3. The air permeability of a coated paper provided with a dry coating layer before being treated with a rewetting liquid is 700 seconds or less by a method according to JIS-P-8117. The method for producing a cast coated paper according to claim 1.