JPH09111694A - Production of cast-coated paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for producing a cast-coated paper easily releasable from the surface of a casting drum leaving little stain on the drum surface and having high glossiness without using casein. SOLUTION: This process for the production of a cast-coated paper is a rewet cast coating method comprising the coating of the surface of a base paper with a coating composition composed of a pigment, an aqueous adhesive and an assistant, the drying of the coating layer, the rewetting of the surface of the dried coating layer with a rewetting liquid and the pressing of the coating layer to a casting drum having specular gloss to effect the drying of the layer. The coating composition contains a pigment at least containing 30-98wt.% (based on the total pigment) of kaolinite clay and 2-30wt.% of satin white and further contains 0.2-6wt.% (based on the total pigment) of a cationic resin as an assistant. The cationic resin is one or more substances selected from urea resin, polyamide urea resin, melamine resin and their derivatives. The thermal coagulation temperature of the coating liquid is 40-80 deg.C.

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 cast coated paper which is excellent in releasability from a drum and glossiness of a cast surface without using casein as an adhesive.

[0002]

2. Description of the Related Art JIS P 81 called cast paper
As a method for producing a high-gloss coated paper having a glossiness of 85 to 95 according to No. 42 (75 degree method), a coating composition whose main components are a pigment, a water-based adhesive and an auxiliary agent is coated on the surface of the base paper After drying, the dried coating layer is rewetted by a wetting agent solution to be plasticized, and a method for producing a cast coated paper by a rewetting method in which the dried coating layer is dried while being pressed against the heated mirror-finished drum surface (for example, Japanese Patent Publication No. 32-7604)
In order to improve the releasability of the coated paper from the surface of the cast drum after drying, casein is used which has a salting property and is easily changed into a gel by heat.

However, casein is not only unstable in terms of supply and price, but also has a characteristic odor because it is an animal protein. In particular, the odor caused by the decay of casein during the production of a coating liquid and the odor generated during the heat treatment for drying the ink in the case of high-speed printing of coated paper are pollution problems. Therefore, in the printing plant, in order to eliminate the odor caused by casein generated by the heat treatment after printing, the odorous gas is burned using a platinum catalyst in the deodorizing device, but the phosphorus component contained in the casein is used. As a result, the life of the expensive platinum catalyst is shortened to about 1/5 as compared with the odorous gas in the case of coated paper that does not use casein.

JP-A-3-252473 discloses an aqueous urethane resin which can stably exist in water in the form of emulsion, colloidal dispersion, aqueous solution or the like instead of a water-soluble polymer compound such as casein. The coating composition used and the high gloss paper obtained by applying this composition are disclosed. This strong glossy paper has a glossiness as high as that which cannot be obtained unless casein, oxidized starch, carboxymethylcellulose or the like is used as a pigment adhesive, for example, a blank paper glossiness of 98 to 100.

In JP-A-5-44193, instead of casein, a modified aqueous urethane resin obtained by neutralizing an epoxy resin-modified aqueous urethane resin or an acrylic resin-modified aqueous urethane resin with an alkali metal hydroxide is used. Without causing defects such as blisters and drum picks,
Disclosed are a composition for cast coated paper, which enables a cast surface having high gloss and excellent surface strength and uniformity, and a method for producing cast coated paper using the same. In this method, since casein is not used, the problem of catalyst deterioration due to the phosphorus component contained in casein when burning the waste solvent can be solved.

Japanese Patent Laid-Open No. 6-2299 discloses a modified water-based urethane resin, an aliphatic conjugated diolefin-based monomer, which is obtained by copolymerizing one or more olefin-based monomers as an adhesive for a pigment, and an olefin-based monomer. Are used alone or in combination of two or more kinds, and the particle size obtained by emulsion polymerization is 150 to 300 nm, and the gel content is used in combination with a latex having a content of 70% by weight or more to obtain gloss, dry and wet surface strength and resistance. Disclosed is a coating composition for cast coated paper suitable for offset rotary printing that enables a cast surface having excellent blister properties, and a method for producing cast coated paper using the same.

Further, when the above-mentioned aqueous urethane resin or modified aqueous urethane resin is used, clay, light calcium carbonate, heavy calcium carbonate, titanium oxide, aluminum hydroxide, satin white, barium sulfate, magnesium oxide, talc are used as pigments. Inorganic pigments such as colloidal silica, and organic pigments such as plastic pigments and white urea resin pigments can all be used, but the above-mentioned aqueous urethane resin has a fatal drawback that it is extremely expensive. . So, of course, casein is excellent in mold releasability from the cast drum surface without using expensive materials such as water-based urethane resin as an adhesive for pigments, does not stain the drum surface, and has a high gloss cast coating. It is strongly desired to realize a method for producing cast coated paper by a rewetting method having a work surface.

[0008]

In view of the above situation, the inventors of the present invention have made earnest studies on a combination of a pigment and an auxiliary agent in order to obtain a cast coated paper having an excellent cast surface by the rewetting method. Clay and satin white as pigments are included in the coating layer, and a specific cationic resin is used as an auxiliary agent in the coating layer. The coating liquid of the composition loses fluidity by heating and shows the temperature at which gelation occurs. Thermal coagulation temperature is 40 ~
The one set in the range of 80 ° C. has excellent releasability from the surface of the cast drum without using casein as an adhesive,
The inventors have found that a cast coated paper having excellent characteristics can be obtained by imparting excellent gloss to a paper base material with little stain on the drum surface, and completed the present invention. The object of the present invention is to use castin-free paper by rewetting method, which does not use casein and water-based urethane resin as an adhesive, has excellent releasability from the surface of the cast drum, has little stain on the surface of the drum, and has excellent gloss. It is to provide a manufacturing method of.

[0009]

The first aspect of the present invention is to provide a pigment,
A coating liquid of a coating composition consisting of an aqueous adhesive and an auxiliary agent is applied to the surface of the base paper, dried, and then dried by a re-wetting liquid to re-wet the coating surface and press-contact with a cast drum having a mirror gloss, and then dried. In the method for producing a cast coated paper by the rewetting method, the coating composition contains at least kaolinite clay as a pigment in an amount of 30 to 98% by weight and satin white in an amount of 2 to 30% by weight. Further, the present invention is a method for producing cast coated paper, characterized in that a cationic resin is contained as an auxiliary agent in an amount of 0.2 to 6% by weight based on the total weight of the pigment, and casein is not used as an adhesive. The second aspect of the present invention is a cast resin according to the first aspect of the present invention, wherein the cationic resin is at least one selected from urea-based resins, polyamideurea-based resins, melamine-based resins and their derivatives. It is a method of manufacturing coated paper. A third aspect of the present invention is that the coating liquid of the coating composition loses fluidity by heating and has a thermal solidification temperature in the range of 40 to 80 ° C. at the time of gelation. Alternatively, it is the method for producing the cast coated paper according to the second aspect.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the above coating composition is used as a base paper, or a base paper having an undercoat layer made of a coating composition containing a pigment and an adhesive as a main component on the base paper. (In the present specification, these base papers and base papers are generically referred to as "paper base materials"), and after forming a cast coating layer, a known casting finish method by a rewetting method is applied. To be done. The clay used in the present invention is a known kaolinite clay (also known as kaolin), which is a general term for kaolin minerals including kaolinite and halloysite, but in the present invention, it is widely used for coating. Kaolinite is used. Kaolinite is chemically Al ₂ O ₃ ·.
2Si0 ₂ · 2H ₂ 0 is the main component, usually hexagonal plate crystals, and various grades of clay are commercially available for coated paper depending on the whiteness and the content of particles of 2 μm or less. Can also be used for the present invention. Furthermore, so-called calcined clay obtained by heat-treating the clay can also be used.

In the present invention, the content of clay is 30 to 98% by weight, preferably 40 to 90% by weight, based on the weight of the total dry pigment in the coating composition. If the clay content is out of the above range and is less than 30% by weight or more than 98% by weight, the gloss of the coated surface of the cast coated paper does not become high and the releasability from the surface of the cast drum is deteriorated. The effect of reducing dirt on the surface becomes insufficient.

The satin white used in the present invention has a chemical name of calcium sulfoaluminate and a chemical formula of 3CaO.Al ₂ O ₃ .3CaSO ₄ .31-32H ₂ 0, which is a columnar or needle-like shape. It is a white pigment having a crystal system of. The manufacturing method is disclosed in JP-A-54-34.
As disclosed in Japanese Patent No. 407, an aqueous suspension of quick lime or slaked lime is treated with aluminum sulfate, Al ₂ (SO ₄ )
₃ · 18H ₂ 0: obtained as a reaction product is reacted with a (common name sulfate) 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 content of satin white is 2 to 30% by weight, preferably 5 to 5% by weight of the total dry pigment in the coating composition.
25% by weight. Sachin white content is 2% by weight
When it is less than, as in the case of clay, the gloss of the coated surface of the cast coated paper does not become high, the releasability from the surface of the cast drum deteriorates, and the effect of further reducing the stain on the drum surface is sufficient. Disappear. On the other hand, when the content exceeds 30% by weight, the fluidity of the coating liquid becomes poor and uneven coating is likely to occur, which is not suitable.

As the cationic resin in the present invention, known ones can be used, for example, cationized starch and its derivative (JP-A-51-123304), cationized polyvinyl alcohol, cationized guar gum and the like (JP-A-6-63).
No. 1-138798), quaternary ammonium-based compounds, tertiary amine-based compounds, secondary amine-based compounds (Japanese Patent Publication No. 62-2).
4560) and the like. Particularly, as an example of a tertiary amine system, dialkylaminoalkyl (meth)
Copolymers of acrylate, vinylpyrimidine, etc. and acrylamide, water-soluble copolymers of these copolymers with further polymerizable vinyl monomers, homopolymers of acrylamide and methacrylamide, and vinyl monomers copolymerizable therewith. Mannich compounds and the like, which are water-soluble copolymers of Further, polyamide polyamine resin, polyethylene imine, polyethylene imine-epichlorohydrin adduct, copolymer of acrylamide and dimethylaminoethyl methacrylate, cationic acrylamide resin and the like can be used.

In particular, at least one kind of cationic resin selected from urea resins, polyamide urea resins, melamine resins and their derivatives (Shinkan Paper Processing Handbook, Tech Times, 1988, 586-587). Page) can be preferably used for the present invention. Of these, various types are known for polyamide urea resins,
For example, "Paper Paper Cooperative Paper (Vol. 45, No. 6,656
P., 1991) ". In addition, amide polyurea obtained by subjecting urea and polyalkylene polyamine to a deammoniation reaction, then dehydration condensation with a dibasic carboxylic acid, and further deammonia reaction with urea, or dehydration condensation of a polyalkylene polyamine and a basic carboxylic acid. Polyamide polyurea obtained by deammonia reaction with urea (Japanese Patent Publication No. 3-16438) or a product obtained by reacting this polyamide polyurea with formaldehyde in an aqueous solution and then reacting with epihalohydrin. (Japanese Patent Publication No. 23679/1990) and the like.

The content of the cationic resin in the present invention is 0.2 to 6% by weight based on the weight of the pigment solid content in the coating liquid,
Preferably it is 1 to 4% by weight. When the content of the cationic resin is less than 0.2% by weight, the gloss of the cast coated paper does not become high and the releasability from the drum surface is improved,
The effect of reducing dirt on the drum surface is not sufficient, and conversely,
When the content exceeds 6% by weight, the fluidity of the coating composition deteriorates and coating unevenness is likely to occur, which is not suitable. In the present invention, any of the various cationic resins described above can be used, in particular, a urea resin, a polyamide urea resin,
At least one cationic resin selected from melamine resins and their derivatives can be preferably used. The mechanism of action by which these cationic resins exert an effect in the present invention is not yet clear in detail, but the cationic resin adsorbs to the anionic pigment particles in the coating liquid to prevent adhesion between the pigments, It is considered that the whole film is made uniform and easily gels easily.

The coating composition according to the present invention contains pigments, adhesives and auxiliaries as main components, as in the known cast coating compositions. As the pigments, clay and satin white which are the above-mentioned essential components are used. In addition, one or more known coating pigments such as aluminum hydroxide, light calcium carbonate, heavy calcium carbonate, titanium dioxide, barium sulfate, zinc oxide and plastic pigment may be appropriately selected and used. Examples of the adhesive include starches such as oxidized starch and enzyme-modified starch, polyvinyl alcohol, synthetic resin adhesives such as olefin maleic anhydride resin and melamine resin,
Cellulose derivatives such as carboxymethyl cellulose, hydroxyethyl cellulose, styrene-butadiene copolymer, conjugated diene polymer latex such as methyl methacrylate-butadiene copolymer, acrylic acid ester and / or acrylic acid ester polymer or copolymer, etc. Of acrylic polymer latex, vinyl polymer latex such as ethylene-vinyl acetate copolymer, or various polymer latexes modified with a monomer having a functional group such as a carboxyl group, or alkali solubility or Examples thereof include alkali-insoluble polymers, which are appropriately selected and used. In the present invention, casein and water-based urethane resin are not used as an adhesive at all. The use ratio of the pigment and the adhesive is 95: pigment: adhesive in an absolute dry weight ratio:
The range is 5 to 70:30, preferably 90:10 to 75:25.

In addition to the above-mentioned pigments, adhesives and cationic resins, various auxiliary agents such as defoaming agents, colorants, release agents and flow modifiers may be added to the coating composition of the present invention as required. Can be appropriately mixed and used. In the present invention, as described in detail above, it is possible to obtain excellent cast coating characteristics and cast paper surface without using casein and an aqueous urethane resin as an adhesive, but such excellent processability The obtained coating liquid of the coating composition capable of imparting excellent properties to the paper substrate is the coating liquid at room temperature (20 to 25 ° C.).
The temperature at which the coating liquid loses fluidity and gels is visually confirmed, and the temperature at that time, that is, the thermal solidification temperature is 4
It is in the range of 0 to 80 ° C, preferably 45 to 70 ° C. If the thermal solidification temperature is less than 40 ° C, the fluidity of the coating liquid may deteriorate during operation, and the coating liquid has a high solidification temperature of more than 80 ° C, or one that does not solidify when heat is applied. Cannot obtain a good cast coated surface.

In the present invention, a known coater, such as a blade coater, an air knife coater, a roll coater, a reverse roll coater or a bar, is used for coating the coating liquid of the above-mentioned coating composition on a paper substrate. A coater selected from a coater, a curtain coater, a die slot coater, a gravure coater, a chanplex coater, etc. is used to coat the coating in one or more layers. The solid content concentration of the coating liquid at that time is 40 to 70% by weight,
It is appropriately adjusted depending on the type of coater and the coating speed. As the paper substrate, unbleached or bleached chemical pulp obtained by digesting hardwood or softwood, mechanical pulp such as GP, RGP, thermomechanical pulp, and pulp selected from deinked waste paper pulp may be used alone or in combination. , A known wet paper machine has a basis weight of 30 to 40 in a single-layer or multi-layer papermaking.
0 g / m ² of paper or paperboard is used. The papermaking method is
It is not particularly limited, and may be acid paper, neutral paper or alkaline paper. In addition, a size selected from known starch, polyvinyl alcohol, external sizing agents, synthetic resins, etc., is applied on a paper base material made of the above paper or paperboard by a size press or a roll coater, and further Those coated with a pigment coating composition as an undercoat layer, coated paper coated with the pigment coating composition on the back surface of the cast coating layer, cast coated paper with the back surface gloss-finished by a casting method, etc. It can be used as a paper substrate for the present invention.

In order to obtain the cast paper of the present invention, the coating composition is coated on the paper substrate in the range of 10 to 50 g / m ² , preferably 15 to 35 g / m ² . If the coating amount is out of this range, a suitable cast paper cannot be obtained. As a method of casting finish, a known direct method,
Either the rewetting method or the coagulation method may be used. In the rewetting method, the coating layer coated on the paper substrate is once dried and then re-wet, but at this time, hot air dryer, air foil dryer, air cap dryer, cylinder dryer, infrared ray are used. Dryers for coated paper such as dryers and electron beam dryers are used. The degree of drying of the coated paper is such that the water content is 4 to 8% by weight based on the total weight of the coated paper. The coated paper after drying is smoothed by machine calender, super calender, etc., if necessary, but it is necessary to avoid excessive treatment that significantly impairs the bulkiness and rigidity, which are the features of cast paper. is there.

In the case of the rewetting method, the coating layer after drying is rewetted as described above, and pressed to a heated mirror surface (cast) drum to give a strong gloss finish. The rewetting liquid in this case is not particularly limited, and examples thereof include clear water, warm water, hot water, or an aqueous solution containing a mold release agent, sodium citrate, zinc sulfate, dicyandiamide, urea or the like. To be

In the present invention, clay, satin white and a cationic resin are combined without using casein or an aqueous urethane resin, and the thermal solidification temperature of the coating liquid is 40 to 40.
By setting the temperature in the range of 80 ° C., cast paper having excellent mold releasability from the cast drum, reducing the dirt on the drum surface, and excellent glossiness on the cast surface can be obtained, but its mechanism of action has been sufficiently clarified. However, while clay is a plate-like crystal, satin white is a needle-like crystal, and by admixing them, the clay particles are prevented from adhering to each other, and a cationic resin is added thereto. Then, as described above, the cationic resin is adsorbed on the anionic pigment particles to prevent the pigments from adhering to each other, and the entire coating film becomes uniform. Due to their synergistic effect, gelation easily occurs within a specific temperature range. It is thought to be from.

[0023]

The present invention will be described in more detail with reference to the following Examples, but it should be understood that the present invention is not limited to these Examples. Unless otherwise specified,% in the examples and comparative examples indicates% by weight, and the coating amounts are all dry weight.

Example 1 Paper having a basis weight of 95 g / m ² was made by a known Fourdrinier paper machine using a mixed pulp composed of 90% hardwood bleached kraft pulp and 10% softwood bleached kraft pulp. On both sides of this base paper, an aqueous undercoating coating composition having the following composition was applied at 8 g / m on each side.
Apply ² by ² with a blade coater to form an undercoat layer, then dry and super calender (water content 5.5%,
A paper base material was manufactured under a nip pressure of 180 kg / cm). Aqueous coating liquid for undercoating Kaolin (UW-90, manufactured by EMC, USA) 30% Heavy calcium carbonate (particle size 1 to 4 μm, manufactured by our company) 70% Oxidized starch per pigment weight (Oji Ace A, manufactured by Oji Konstarch) 2% Latex (L-1537, manufactured by Asahi Kasei Co., Ltd.) 14% Dispersant (sodium polyacrylate) 0.3% Lubricant (calcium stearate) 0.5% Fluorescent dye 0.2% Solid pigment and dispersant At a concentration of 70%, the mixture was dispersed with a deleter (manufactured by Serie Co.), and then an adhesive and other auxiliary agents were added to the mixture while stirring to thoroughly mix and disperse the mixture, and then the solid content concentration was adjusted to 60%, and a 25% aqueous ammonia solution was used. The pH of the coating solution was adjusted to be alkaline.

Next, an aqueous coating solution for cast coating having the following composition was applied to one side of the paper base material using an air knife coater 20.
After coating with g / m ² , the paper was dried with a hot air dryer until the water content became 6%. Aqueous coating liquid for cast coating Kaolin (UW-90) 65% Light calcium carbonate (Tamapearl 123-SF, 20% Okutama Kogyo Co., Ltd.) Sachin White (In-house) 15% Dispersant per pigment weight (sodium polyacrylate) , Toagosei Co., Ltd.) 0.4% Oxidized starch (Oji Ace A) 3% Latex (L-1537) 15% Cationic resin (polyamide urea resin, PA-620, manufactured by Nippon PMC) 3% Release agent (Wax emulsion, manufactured by San Nopco) 1% Fluorescent dye 0.2% Non-phosphorus antifoaming agent 0.1% Pigment and dispersant are dispersed at a solid concentration of 65% by a deritter (manufactured by Serie Co.), and then stirred. While the adhesive and other auxiliary agents were sequentially added and sufficiently mixed and dispersed, the solid content concentration was adjusted to 40%, and a 25% aqueous ammonia solution was used.
The pH of the coating liquid was adjusted to be alkaline to obtain an aqueous coating liquid for cast coating.

Thereafter, the cast coated surface of the obtained coated paper was coated with a 0.5% aqueous sodium citrate solution so that the coating amount was 10 g / m ^2, and this surface was immediately treated with 11
After being pressed against a cast drum having a surface temperature of 0 ° C. with a press roll and dried, it was peeled from the cast drum with a take-off roll, and a cast paper was obtained by the “rewetting method”.
The winding speed at this time was 100 m / min. The following test methods and evaluation methods were used to evaluate the quality of the obtained cast paper and the operability in producing the cast paper. Test method and evaluation method (1) Glossiness of cast surface Measured according to JIS P 8142 (75 degree method). (2) Releasability The state when the cast surface is separated from the cast drum was visually observed and the evaluation was performed as follows. ◯: The cast surface is separated from the drum without any resistance. Δ: The cast surface was slightly attached to the drum, and it was slightly difficult to separate. □: The cast surface adheres to the drum and is difficult to separate.

(3) Dirt on the surface of the drum: The surface of the cast drum after the continuous pressure contact treatment of 5000 m was visually observed, and the evaluation was performed as follows. ○: Clean, and continuous operation is possible. Δ: Some white and light dirt is attached, but a little more continuous operation is possible. □: There is a lot of dirt and it is necessary to stop the operation and wipe the drum surface again. (4) Fluidity of coating liquid The coating surface immediately after the coating liquid was coated on a paper substrate with an air knife was visually observed, and the evaluation was performed as follows. ◯: The coated surface is uniform and good with no coating unevenness. Δ: Coating unevenness sometimes appears on the coated surface. □: There are many coating irregularities on the coated surface. (5) Thermal Coagulation Temperature of Coating Liquid 20 g of the aqueous coating liquid for cast coating was placed in a 100 ml Erlenmeyer flask, and the contents were stirred on a warm bath for 5 ± 5%.
The temperature was raised at a rate of 1 ° C./min, the coating liquid thickened, and the temperature at which the coating liquid solidified (the coating liquid lost fluidity and gelled) was defined as the thermocoagulation temperature.

Example 2 A cast paper was produced in the same manner as in Example 1 except that the composition of the pigment slurry for the aqueous coating liquid for cast coating was changed as follows. Pigment slurry Kaolin (UW-90) 97% Satin white (manufactured in-house) 3% Polyacrylic acid soda 0.4% per pigment weight 0.4% The quality of the cast paper obtained and the operability in manufacturing the cast paper were evaluated. .

Example 3 A cast paper was produced in the same manner as in Example 1 except that the composition of the pigment slurry for the aqueous coating liquid for cast coating was changed as follows. Pigment Slurry Kaolin (UW-90) 32% Light Calcium Carbonate (Tamapearl 123-SF) 53% Satin White (Made In-house) 15% Sodium Polyacrylate 0.4% Per Pigment Weight Sodium Polyacrylate Quality Evaluation and Casting The operability in producing paper was evaluated.

Example 4 A cast paper was produced in the same manner as in Example 1 except that the composition of the pigment slurry for the aqueous coating liquid for cast coating was changed as follows. Pigment Slurry Kaolin (UW-90) 40% Light Calcium Carbonate (Tamapearl 123-SF) 32% Sachin White (Made In-house) 28% Sodium Polyacrylate 0.4% Per Pigment Weight Sodium Polyacrylate 0.4% The operability in producing paper was evaluated.

Example 5 Polyamide urea resin (PA-620, Japan PM) was used as the cationic resin in the composition of the aqueous coating liquid for cast coating liquid.
A cast coated paper was produced in the same manner as in Example 1 except that the amount of C) was 0.3% based on the weight of the pigment. The quality evaluation of the obtained cast coated paper and the operability in manufacturing the cast paper were evaluated.

Example 6 Same as Example 1 except that the amount of the cationic resin (PA-620, manufactured by CMC Japan) in the composition of the aqueous coating solution for cast coating solution was 5% based on the weight of the pigment. Then, a cast coated paper was manufactured. The quality evaluation of the obtained cast coated paper and the operability in manufacturing the cast paper were evaluated.

Example 7 A cast paper was produced in the same manner as in Example 1 except that the composition of the pigment slurry for the aqueous coating liquid for cast coating was changed as follows. Pigment slurry Kaolin (Alphacoat, manufactured by Anglo America) 65% Light calcium carbonate (Tamapearl 123-SF) 20% Sachin white (manufactured by us) 15% Sodium polyacrylate 0.4% by weight of pigment Obtained cast paper Was evaluated and the operability when manufacturing cast paper was evaluated.

Example 8 A cast paper was produced in the same manner as in Example 1 except that the composition of the pigment slurry for the aqueous coating liquid for cast coating was changed as follows. Pigment slurry calcined clay (Ansilex 93, manufactured by US EMC) 65% Light calcium carbonate (Tamapearl 123-SF) 20% Sachin white (manufactured by us) 15% Sodium polyacrylate 0.4% per pigment weight Obtained cast The quality of the paper and the operability when manufacturing cast paper were evaluated.

Example 9 In the composition of the aqueous coating liquid for cast coating liquid, the cationic resin was replaced with another polyamide urea resin (Sumiraz resin 63).
9, manufactured by Sumitomo Chemical Co., Ltd.), and cast coated paper was manufactured in the same manner as in Example 1. The quality evaluation of the obtained cast coated paper and the operability in manufacturing the cast paper were evaluated.

Example 10 In the composition of the aqueous coating liquid for cast coating liquid, the cationic resin was replaced with another polyamide urea resin (Sumiraz resin 70).
3, manufactured by Sumitomo Chemical Co., Ltd.), and cast coated paper was manufactured in the same manner as in Example 1. The quality evaluation of the obtained cast coated paper and the operability in manufacturing the cast paper were evaluated.

Comparative Example 1 A cast paper was produced in the same manner as in Example 1 except that the composition of the pigment slurry for the aqueous coating liquid for cast coating was changed as follows. Pigment slurry Kaolin (UW-90) 99% Satin white (manufactured in-house) 1% Polyacrylic acid soda 0.4% per pigment weight 0.4% We evaluated the quality of the cast paper obtained and the operability when manufacturing the cast paper. .

Comparative Example 2 A cast paper was manufactured in the same manner as in Example 1 except that the composition of the pigment slurry for the aqueous coating liquid for cast coating was changed as follows. Pigment Slurry Kaolin (UW-90) 27% Light Calcium Carbonate (Tamapearl 123-SF) 58% Satin White (Made In-house) 15% Sodium Polyacrylate 0.4% Per Pigment Weight Sodium Polyacrylate Quality Evaluation and Casting The operability in producing paper was evaluated.

Comparative Example 3 A cast paper was produced in the same manner as in Example 1 except that the composition of the pigment slurry for the aqueous coating liquid for cast coating was changed as follows. Pigment Slurry Kaolin (UW-90) 40% Light Calcium Carbonate (Tamapearl 123-SF) 27% Satin White (Made In-house) 33% Sodium Polyacrylate 0.4% Per Pigment Weight Sodium Polyacrylate 0.4% The operability in producing paper was evaluated.

Comparative Example 4 Casting was carried out in the same manner as in Example 1 except that the amount of the cationic resin (PA-620) in the composition of the aqueous coating liquid for cast coating liquid was 0.1% based on the weight of the pigment. A coated paper was manufactured.
The quality evaluation of the obtained cast coated paper and the operability in manufacturing the cast paper were evaluated.

Comparative Example 5 In the composition of the aqueous coating liquid for cast coating liquid, the amount of the cationic resin (PA-620) was 7% based on the weight of the pigment,
A cast coated paper was produced in the same manner as in Example 1. The quality evaluation of the obtained cast coated paper and the operability in manufacturing the cast paper were evaluated.

The results obtained in Examples 1-10 and Comparative Examples 1-5 are shown in Table 1.

[0043]

[Table 1]

As can be seen from Table 1, the coating liquid according to the method of the present invention has excellent fluidity, the thermal solidification temperature is in the range of 46 to 63 ° C., and the gloss of cast paper is excellent at 88% or more. Further, when producing cast paper, the cast paper has excellent releasability from the cast drum, and the drum surface does not become dirty. On the other hand, when the content of satin white or clay in the composition of the aqueous coating liquid for cast coated paper is small, the releasability of the cast paper from the drum becomes poor, and the dirt on the drum surface becomes large, The gloss of cast paper is also low and not suitable for practical use (Comparative Examples 1 and 2). Similarly, when the content of satin white in the composition is large, the thermal coagulation temperature becomes low, the fluidity of the coating liquid deteriorates, and a problem occurs in operation (Comparative Example 3). On the other hand, when the amount of the cationic resin in the composition is small, the releasability of the cast surface from the drum is deteriorated, the drum surface is also heavily soiled, and the gloss of the cast paper is remarkably inferior. On the other hand, if the content of the cationic resin is high, the fluidity of the coating liquid is deteriorated and the operability is deteriorated, which is not suitable.

[0045]

INDUSTRIAL APPLICABILITY According to the present invention, the flowability of the coating liquid is good, the glossiness of the obtained cast paper is excellent, and the cast surface of the cast paper under production is not required to be used without using casein as an adhesive. An effect of providing a method for producing cast paper which is excellent in mold releasability and has less dirt on the drum surface is obtained.

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Claims (3)

[Claims] 1. A coating solution of a coating composition comprising a pigment, a water-based adhesive and an auxiliary agent is applied to the surface of a base paper, dried and then re-wetting the dried coating surface to give a specular gloss. In a method for producing a cast coated paper by a rewetting method, which comprises contacting with a cast drum and drying, the coating composition comprises at least kaolinite clay as a pigment in an amount of 30 to 98% by weight and satin white based on the total weight of the pigment. 2-30% by weight
A method for producing cast coated paper, characterized in that it contains 0.2 to 6% by weight of a cationic resin as an auxiliary agent based on the total weight of the pigment, and does not use casein as an adhesive agent. 2. The cast coated paper according to claim 1, wherein the cationic resin is at least one selected from urea resins, polyamideurea resins, melamine resins and derivatives thereof. Production method. 3. The thermal coagulation temperature when the coating liquid of the coating composition loses fluidity by heating and gels is 40 to 80 ° C.
The method for producing cast coated paper according to claim 1 or 2, characterized in that