JPH06158589A - Production of cast coated paper - Google Patents

Abstract

PURPOSE:To provide the method for producing cast coated paper good in releasability from a cast drum even when casin is not used, not accompanied by the generation of stains on the cast drum, and good in the glossiness of the cast surface. CONSTITUTION:The method for producing the cast coated paper comprises coating a coating solution on a paper substrate, drying the formed coating layer with an air drier at a hot air temperature of 55-140 deg.C and under an air pressure of 10-140mmAq, rewetting the coating layer, and subsequently bringing the rewetted coating layer into press-contact with a heated finishing surface having a mirror luster to obtain a strongly lustrous finished paper.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing cast coated paper. More specifically, the present invention makes it possible to obtain cast paper having good mold releasability from the cast drum and having good gloss on the cast surface, even without containing casein which has been conventionally used as an essential component. The present invention relates to a possible manufacturing method.

[0002]

2. Description of the Related Art As a method for producing high-gloss coated paper called cast paper, a coating solution containing a pigment, an aqueous adhesive and an auxiliary agent as a main component is applied to the surface of the base paper and immediately heated to a mirror-finished surface. Direct method of drying while contacting with (see, for example, Japanese Examined Patent Publication No. 38-25160), the main component is a coating liquid consisting of a pigment, a water-based adhesive and an auxiliary agent, and after drying,
A rewetting method in which the coating layer is re-wetted with a wetting agent solution to be plasticized and dried while being brought into contact with a heated mirror-finished surface (see, for example, JP-B-32-7604), a main component is a pigment,
After applying a coating liquid consisting of an aqueous adhesive and an auxiliary agent on the surface of the raw paper, after contacting with a coagulating liquid solution to gelate the coating layer,
A solidification method of drying while contacting a heated mirror-finished surface (see, for example, Japanese Patent Publication No. 38-15751, Japanese Patent Publication No. 40-7207, and Japanese Patent Publication No. 47-7555) is known.

All of these cast finishing methods
It is common in that the coating layer in the plastic state is pressed against the heated mirror surface drum, dried, and released from the mold, but the rewetting method is particularly preferred because of the high processing speed and therefore high production efficiency. It has been implemented.

The adhesive in the coating liquid for cast paper was a natural adhesive such as various starches, casein and other proteins almost without exception at the early stage of the development of cast coating. Only some form of casein was used for. When styrene-butadiene latex has been industrialized in recent years, casein and latex have come to be used in combination in any of the above three casting finishing methods. Casein, which is commonly used in any of the casting finishing methods, belongs to phosphoprotein among proteins, and it easily becomes a variable gel due to chlorination or heat. This is to improve the releasability when releasing from the mold. For these reasons, it is considered that casein has been used as an essential component of coating solutions for cast paper to date.

On the other hand, polyvinyl alcohol (hereinafter referred to as PVA) has been widely known as a material for paper coating since ancient times, and is currently used as a papermaking-related material in Japan for 2 times a year.
It is said that there is a demand of less than 10,000 tons (The World of PVA, published by The Society of Polymer Publishing, p. 128, 1992). PVA is a water-soluble polymer produced by polymerizing and saponifying vinyl acetate monomer in methanol. Many varieties of brands have been developed by changing the degree of polymerization and the degree of saponification, but in order to further functionalize, (1) copolymerization method, (2) end group modification method, (3) modified P by graft reaction method, etc.
VAs are also manufactured (published by Tech Times, "Pharmaceutical Encyclopedia of Paper and Processing," pages 229, 257, 1991).

[0006] A method of blending PVA or a derivative thereof into a coating liquid composition is also disclosed in Japanese Patent Publication No. 2-23639, but in this case, it is used in combination with a water-soluble optical brightener and By drying at the evaporation rate, PVA fixes the whitening agent and migrates to the surface of the coating layer, so that the whitening effect is enhanced. However, the above-mentioned publication merely discloses a technique that is completely different from the mold release property and the improvement of glossiness of cast coated paper, especially cast paper that does not use casein, and makes any suggestions regarding the cast coated paper. It is not something that exists.

Further, in JP-B-2-23639, PVA or a derivative thereof is not only PVA but also modified by esterification, etherification, urethanization, acetalization, cross-linking, copolymerization or the like. It is disclosed to also include derivatives of modified PVA. Further, JP-A-4-209889 discloses a carboxyl group-modified PVA as a surface sizing agent.

The use of an aqueous urethane resin in a coating liquid for cast paper is disclosed in JP-A-3-167386.
However, in this publication, an aqueous urethane resin and casein are used together as shown in the examples. Further, in JP-A-3-252473, an aqueous urethane resin is used together with a polymer latex and / or an emulsion, and a coating composition which does not use a water-soluble polymer such as casein and oxidized starch, and the composition are coated. Although a high-gloss paper obtained by working is disclosed, this publication merely specifies the use ratio of the latex and / or emulsion and the aqueous urethane resin. There is no description or suggestion of a coating liquid composition when the usage ratio exceeds 30% by weight. Further, there is no description suggesting the drying conditions, and it is unknown.

Casein, which is currently used as a component of a coating liquid for cast paper, is not only unstable in terms of supply and price because it is a natural adhesive, but it also has a peculiar malodor because it is an animal protein. Occur. In particular, the odor caused by rotting during the production of coating liquid, and the odor when heat-treated by passing through a dryer at 200 to 300 ° C to dry the ink in the case of high-speed printing such as offset rotary printing poses a problem. Has become. Therefore, in the case of offset rotary printing, the exhaust gas in the dryer is burned by an afterburner to perform deodorizing treatment. However, the platinum catalyst required for deodorizing treatment by combustion is expensive at around 1500 yen per gram, and it is easily deteriorated by the phosphorus component contained in casein, so the life of the catalyst is extremely shortened and it becomes a heavy economical burden. ing.

For this reason, the development of a coating solution for cast paper that does not use casein is a major issue that must be urgently solved. However, no matter how the adhesives other than casein are combined, It has not been possible to obtain a cast surface with a gloss level comparable to that of the above.

[0011]

SUMMARY OF THE INVENTION In view of the above situation, the present inventors have been keenly aware of a combination of adhesives for a coating liquid for cast paper, coating the coating liquid, and drying conditions in an air dryer. As a result of research, they have found that a cast paper having good mold releasability from a cast drum and excellent gloss can be obtained without using casein, and completed the present invention.

Therefore, the object of the present invention is to eliminate the drawbacks of the prior art as described above, to eliminate the generation of harmful components such as odor due to casein, and to remove from the cast drum even without using casein. An object of the present invention is to provide a production method capable of obtaining a cast coated paper having good properties and excellent gloss.

[0013]

The present invention provides a coating layer formed by applying a casein-free coating liquid composition containing a pigment and an adhesive as main components onto a paper substrate to form a coating layer. In the method for producing a cast coated paper, which is re-wetted after drying and pressed against a heat-finished surface having a mirror gloss to give a strong gloss finish, (1) in the adhesive, an aqueous urethane resin is added to a coating liquid having a solid content of 2.5.
% To 30% by weight and polyvinyl alcohol or a derivative thereof in an amount of 0.1 to 3% by weight, and (2) the hot air temperature of an air dryer for drying the coating layer before rewetting is 55 to 14%.
A method for producing cast coated paper, which is characterized by maintaining 0 ° C and a wind pressure at 10 to 140 mmAq.

In order to produce cast coated paper using the coating liquid composition in the present invention, a base paper (or a base paper having an undercoat layer containing a pigment or an adhesive as a main component) is provided on the base paper. In the specification, these base papers and base papers are collectively referred to as a paper base material, which means that a cast coating layer is further provided on the base paper). After forming the cast coating layer, the hot air temperature and the air pressure of the air dryer are set to the conditions of the present invention and dried, and cast by the rewetting method among the well-known direct method, rewetting method and coagulation method. Just finish it.

In the present invention, an aqueous urethane resin is used among the urethane resins. Urethane resin is a polymer having a urethane bond (-OOCHN-) in the molecule,
Generally, saturated polyols with two or more OH groups (HO-PE-O
H) and polycyanate (OCN-Ar-NCO). In particular, as the polyol used for the aqueous urethane resin, diol or triol is generally used.

Examples of the diol include, in addition to usual glycols such as neopentyl glycol, 1,4-butanediol, and 1,6-hexadiol, polyether glycol represented by polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. Further, polyester polyol, acrylic polyol, epoxy polyol, polycarbonate polyol and the like can be mentioned. or,
Examples also include diols having a tertiary amine such as N-methyldiethanolamine and diols having a carboxyl group such as dimethylolpropionic acid.

On the other hand, the isocyanate used for the aqueous urethane resin is toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, 4,4'-cyclohexyl isocyanate, methylcyclohexane-2,4. (2,6) diisocyanate, 1,3
-Cyclohexane, isophorone diisocyanate, trimethylhexamethylene diisocyanate, dimer acid diisocyanate and the like can be mentioned.

Further, as disclosed in JP-A-3-167386, a polymer is polymerized with amines such as triethylamine and dimethylethanolamine, or a water-soluble amino resin such as methylated melamine resin, It is also possible to use a known aqueous polyurethane resin obtained by crosslinking using aziridine, an epoxy resin, a zinc complex or the like. The aqueous urethane resin thus obtained is used in the present invention in a water-soluble state or an emulsion or colloidal dispersion state.

The content of the aqueous urethane resin in the coating liquid composition of the present invention is 2.5 to 30% by weight, preferably 3 to 20% by weight, based on the solid content of the coating liquid. When the content of the water-based urethane resin is less than 2.5%, the glossiness of the cast surface of the obtained cast coated paper cannot be obtained, and conversely 30%
When it exceeds, the glossiness of the cast surface is not improved to a certain extent or more, and only the cost is increased, which is not preferable.

In the present invention, the above-mentioned known
You can use any of the PVA,
For the purpose of the present invention, industrially easily, inexpensively supplied, and commonly used PVA having a polymerization degree of 300 to 2000 and a saponification degree of 85 mol% or more sufficiently exerts its effect. Therefore, it is preferably used.

The amount of PVA blended in the present invention is in the range of 0.1 to 3% by weight, preferably 0.5 to 2% by weight, based on the solid content of the coating liquid. When the content of PVA is less than 0.1%, the gloss of the cast surface of the obtained cast coated paper is poor and the releasability from the cast drum is poor. On the other hand, when the amount of PVA exceeds 3%, the viscosity of the coating liquid becomes high, defects such as coating unevenness are likely to occur, and it is difficult to coat with an air knife coater, so it is not suitable. Is.

Next, the coating liquid of the present invention is applied by a coating apparatus used for producing general coated paper such as an air knife coater, a blade coater, a roll coater and a bar coater.
Coated on a paper substrate. The coating layer coated on the paper substrate, hot air temperature 55 ~ 140 ℃ in an air dryer,
Preferably 80-110 ℃ and wind pressure 10-140 mmAq, preferably
The water content of the coated paper is adjusted to the range of 2 to 9%, preferably 4 to 8% by appropriately selecting it in the range of 30 to 110 mmAq.

The hot air temperature of the air dryer is 55 ° C.
When the temperature is lower than 140 ° C. or higher than 140 ° C., and when the wind pressure is lower than 10 mmAq or higher than 140 mmAq, the mold release property of the cast coated paper from the cast drum and the gloss of the cast surface are inferior. So unsuitable. If the hot air temperature is less than 55 ° C and the air pressure is less than 10 mmAq, there is a risk that the drying will be insufficient.

The mechanism of how the effects obtained in the present invention are expressed is not clear so far, but the conventionally known method uses hydrophilic casein and therefore is suitable in the coating layer. The viscosity and water retention are secured, a uniform coating film is easily obtained on drying, the distribution of each component on the cast surface is very uniform, and the mold releasability from the cast drum and the glossiness of the cast coated surface are good. It is considered to be a thing. On the other hand, when an aqueous urethane resin is used without using casein, it is difficult to obtain appropriate viscosity and water retention in the coating layer, and it is difficult to obtain water and each component in the coating layer during drying. Excessive flow and rapid evaporation of water are likely to occur. This leads to poor smoothness on the surface of the cast coating and uneven distribution of each component, which may result in poor releasability from the cast drum and poor gloss.

Further, not only the cast surface but also the coating layer as a whole, the distribution of each component, especially the adhesive becomes non-uniform due to migration, so that the adhesive strength in a local and microscopic region is A weak portion is created, and when the coated surface is re-wetted and pressed against the cast drum and released from the mold, fine coating film pieces peel off and adhere to the surface of the cast drum. It is considered that the deterioration becomes even worse and the glossiness is remarkably reduced.

In the production of cast coated paper by the rewetting method,
The coating, drying, rewetting and casting are usually carried out continuously in one pass, in which case the production speed is usually 50 to 150 m / min. This is significantly slower than the production speed of coated paper such as general art paper and coated paper.In other words, it takes a long time for the coating film to dry after coating, and The adhesive component easily penetrates into the paper base material, and the adhesive strength of the coating film tends to decrease accordingly, and this tendency is even stronger in casein-free coating liquids for casting. It is considered that the PVA in the present invention imparts appropriate viscosity and water retention in the cast coating layer and contributes to the improvement of the adhesive strength inside the cast coating layer.

The coating liquid composition of the present invention contains pigments, adhesives and auxiliaries as main components as in the conventional cast coating liquid compositions. Examples of pigments include clay, kaolin and
Aluminum hydroxide, calcium carbonate, titanium dioxide,
One or more known pigments for coated paper such as barium sulfate, zinc oxide, satin white, and plastic pigments are appropriately selected and used.

In the coating liquid composition of the present invention, it is essential that an aqueous urethane resin and PVA are contained as adhesive components. As the adhesive other than the aqueous urethane resin and PVA, for example, a styrene-butadiene copolymer, a conjugated diene polymer latex such as a methyl methacrylate-butadiene copolymer, a polymer or copolymer of an acrylic acid ester and / or a methacrylic acid ester. Acrylic polymer latex such as polymer (of these, those not containing diene monomer are particularly referred to as acrylic emulsion),
Vinyl-based polymer latexes such as ethylene-vinyl acetate copolymers, or alkali-soluble or alkali-insoluble polymer latexes obtained by modifying these various polymer latexes with monomers containing functional groups such as carboxyl groups. Examples of known adhesives for coated paper include maleic anhydride resins, synthetic resin adhesives such as melamine resins, starches such as oxidized starch and enzyme-modified starch, and cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose. it can.

The weight ratio of the pigment to the adhesive in the coating liquid composition of the present invention is 92: 8 to 60:40, preferably 88:12 to 65: 3 in terms of solid content.
5, the weight ratio of the latex and the aqueous urethane resin is 70:30 to 20:80, preferably 65:35 to 25:75 in solid content, and the weight ratio of the aqueous urethane resin and PVA is in solid content. 99: 1
~ 45: 55, preferably 95: 5 to 55:45.

In addition to the above-mentioned adhesive and pigment components, in the coating liquid composition of the present invention, if necessary, a defoaming agent, a coloring agent, a water-proofing agent, a release agent, a flow modifier, a coagulant. Various auxiliaries such as can be appropriately mixed. For example, as a coagulant, any coagulant such as an organic acid such as formic acid, crotonic acid, itaconic acid or an electrolyte such as calcium formate, calcium chloride or the like that coagulates the adhesive component of the coating film can be used.

When the coating liquid composition is coated on a paper substrate, a coater used for producing a known coated paper, such as a blade coater, an air knife coater, a roll coater or a reverse roll, is used. A coater provided with a coating device such as a coater, a bar coater, a curtain coater, a die slot coater, a gravure coater, and a chanplex coater is used, and the coating is performed in one layer or in multiple layers. At that time, the solid content concentration of the coating liquid is 35 to 70.
It is appropriately selected and used within the range of wt% depending on the type of coater and the coating speed.

As the paper base material for the present invention, a basis weight of 30 to 400 g used for general printing coated paper and cast coated paper is used.
Paper and paperboard made of wood pulp within the range of / m ² are used, but the papermaking method is not particularly limited, and may be acidic papermaking, alkaline papermaking, single-layer papermaking, or multilayer papermaking, It is also possible to use a medium-quality base paper containing 10% by weight or more of high yield pulp. In addition, the undercoat coating, coated paper with a known pigment coating on the opposite side of the cast coating layer, or cast coated paper with one side (back side) finished with a gloss by a casting method, etc. It can be used as a material.

The coating amount of the coating liquid composition on the paper substrate is 10 to 50 g / m ² in terms of dry weight, but the effect of improving the white paper quality and the cast coating speed of the cast coated paper obtained is obtained. 15-35 in points
It is desirable to adjust in the range of g / m ² .

The coated paper after drying may be subjected to a smoothing treatment by a machine calender, a super calender, etc., if necessary, but an excessive amount such that the bulkiness and the rigidity characteristic of the cast coated paper are remarkably impaired. Of course processing should be avoided. In the rewetting method as in the present invention, after smoothing the coated layer of the smoothed coated paper or the untreated coated paper as described above, it is pressed against a heated mirror surface drum to obtain a strong gloss. To be finished. At that time, the rewetting liquid is not particularly limited, and includes, for example, fresh water, warm water, hot water, an aqueous solution containing a release agent, sodium citrate, zinc sulfate or dicyandiamide, and amines such as urea. A known rewetting liquid such as an aqueous solution is used.

In the present invention, the coating liquid contains an aqueous urethane resin and PV.
By blending A, it gives the coating layer viscosity and water retention instead of casein, and at the same time contributes to the improvement of adhesive strength, and each component is uniformly distributed for the first time by applying proper drying. A coating film is obtained,
As described in JP-B-2-23639, a whitening agent-immobilized P
Basically, unlike the case where VA is migrated to the coating film surface to obtain a whitening effect, the present invention makes it possible to easily obtain excellent quality even with cast paper that does not use casein.

[0036]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the examples and comparative examples, parts and% are parts by weight and% by weight, respectively, unless otherwise specified. In addition, all coating amounts are indicated by absolute dry weight.

Example 1 80 parts of kaolin (UW-90, manufactured by EMC, USA), 20 parts of light calcium carbonate (Tamapearl 123-SF, manufactured by Okutama Industry Co., Ltd.), 0.4 part of sodium polyacrylate were used using a deritter (manufactured by Serie). It was dispersed in water to prepare a pigment slurry having a solid content concentration of 65%. Then, using this pigment slurry, a coating liquid was prepared with the following formulation.

80% water-based urethane resin (Olestar UD100N, manufactured by Mitsui Toatsu) 10% latex (L-1537, manufactured by Asahi Kasei) 8% PVA (NH-17Q, manufactured by Nippon Synthetic Chemical Industry, degree of polymerization 1700, saponification) 99% by mol) 1% Release agent (wax emulsion, made by San Nopco) 1% Calcium formate 0.5 parts, fluorescent dye 0.2 parts, non-phosphorus antifoaming agent 0.1 part, water in order per 100 parts by weight of this coating solution. After adding and stirring well, the pH was made alkaline with 25% aqueous ammonia to obtain an aqueous coating solution with a solid content concentration of 40%.

[0039] This coating solution was applied to hardwood bleached kraft pulp 90
%, Softwood bleached kraft pulp mixed with 10%, and coated with the cast coater shown in FIG. 1 on one side of a paper base material having a basis weight of 90 g / m ^{2 which} is produced by a normal paper machine. Was manufactured. That is, a paper substrate 1 was coated with an air knife coater 2 so that the dry weight was 23 g / m ² , and a drier 3
(Mitsubishi Heavy Industries, air dryer, drying zone length 25
m) and dried under the conditions of hot air temperature of 80 ° C and air pressure of 90 mmAq. After that, 0.3% zinc sulfate aqueous solution was sprayed onto the coating layer with the zinc sulfate aqueous solution sprayer 4, immediately pressed against the cast drum 6 having a surface temperature of 110 ° C. with the press roll 5, and after drying, peeled from the cast drum with the take-off roll 7. Then, cast paper 8 was obtained. The winding speed at this time is 100 m / min, and this method is generally called "rewetting method". The quality of the obtained cast paper was evaluated as follows.

(1) Releasability The state when the cast surface was separated from the cast drum was visually observed and evaluated as follows. ◯: The cast surface is separated from the drum without any resistance. Δ: The cast surface is slightly attached to the drum and is slightly difficult to separate. □: The cast surface adheres to the drum and is difficult to separate. ○ △ and △ □ indicate the middle level between them. (2) Dirt on the surface of the cast drum The cast drum after the continuous pressure contact treatment of 5000 m was visually observed and evaluated 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. ○ △ and △ □ indicate the middle level between them. (3) Glossiness of cast surface The cast surface of the obtained cast paper was measured by JIS P 8142 (75 degree method).

Example 2 70% of the pigment, an aqueous urethane resin (Olestar UD100N,
Cast paper was manufactured in the same manner as in Example 1 except that it was 20%, and the quality was evaluated.

Example 3 Barrier Star XUD219 was prepared by adding 63% of the pigment and an aqueous urethane resin.
3 (Mitsui Toatsu) 27%, hot air temperature of air dryer 6
Cast paper was manufactured in the same manner as in Example 1 except that the temperature was 0 ° C., and quality evaluation was performed.

Example 4 88% of the above pigment, 2.8% of aqueous urethane resin KA8066 (Sumitomo Bayer Urethane), 6% of latex L-1537, PVA (NH
-17Q) was 2.2%, and cast paper was manufactured in the same manner as in Example 1 and quality evaluation was performed.

Example 5 A cast paper was produced in the same manner as in Example 1 except that the pigment was 79% and the PVA was PVA205 (Kuraray Co., Ltd., polymerization degree 500, saponification degree 88 mol%) 2%. went.

Example 6 78.3% of the above pigment and PVA of PVA 205 (polymerization degree 500, saponification degree 88
(Mole%) 2.7% and cast paper was manufactured in the same manner as in Example 1 and quality evaluation was performed.

Example 7 Example 1 except that the pigment was 80.8% and PVA was 0.2% Gosefimer Z-200 (acetoacetylated PVA, manufactured by Nippon Gosei Co., Ltd.)
The cast paper was manufactured in the same manner as above, and the quality was evaluated.

Example 8 Acrylic emulsion (Primal WL-81, manufactured by Rohm and Haas Japan) 12%, aqueous urethane resin (Orestar UD100N) 6%, hot air temperature of the air dryer was 130 ° C., and air pressure was 15 mmAq. Cast paper was manufactured in the same manner as in Example 1, and quality evaluation was performed.

Example 9 A cast paper was produced in the same manner as in Example 1 except that the hot air temperature of the air dryer was 130 ° C. and the air pressure was 130 mmAq, and the quality was evaluated.

Example 10 The following aqueous coating solution was applied to both sides of the paper base material (base paper) of Example 1 by 8 g / m ² per side with a blade coater and then a nip linear pressure of 200 kg / in a super calender. A paper base material was produced by performing a smoothing treatment in cm. Kaolin (UW-90), an aqueous coating solution for paper substrates 26% Heavy calcium carbonate (made in-house, particle size 0.5-4 μm) 60% Oxidized starch (Oji Ace, Oji corn starch) 2% Latex (L-1537 ) 12% 0.3 parts of polyacrylic acid soda as a dispersant and 0.5 parts of calcium stearate as a lubricant per 100 parts of pigment in the above ingredients
Parts and 0.2 parts of fluorescent dye were sequentially added and thoroughly mixed and dispersed, and the pH was adjusted to be alkaline with a 25% ammonium aqueous solution. The solid content concentration was 60%.

On one side of this paper base material, a coating liquid was applied in the same manner as in Example 1 to produce cast paper, and the quality was evaluated.

Example 11 Bleached kraft pulp (mixing ratio of hardwood and softwood is 8: 2)
With a known three-layer papermaking machine using a middle layer basis weight of 30 g / m ² ,
Basis weights of 110 g / m ² were laminated on both sides of this middle layer to produce a paper base material with a total basis weight of 250 g / m ² , and cast paper was produced in the same manner as in Example 1 using this paper base material. Then, the quality was evaluated.

Comparative Example 1 88% of the above pigment, water-based urethane resin (Olestar UD100N)
Cast paper was manufactured in the same manner as in Example 1 except that the content was changed to 2%, and the quality was evaluated.

Comparative Example 2 A cast paper was produced in the same manner as in Example 1 except that latex (L-1537) was 9% and PVA was 0%, and the quality was evaluated.

Comparative Example 3 A coating solution was prepared in the same manner as in Example 1 except that the pigment was 77.5% and the PVA (NH-17Q) was 3.5%, but the viscosity was too high to allow coating.

Comparative Example 4 A cast paper was produced in the same manner as in Example 1 except that the hot air temperature of the air dryer was 50 ° C. and the air pressure was 150 mmAq, and the quality was evaluated.

Comparative Example 5 A cast paper was produced in the same manner as in Example 1 except that the hot air temperature of the air dryer was 150 ° C. and the air pressure was 5 mmAq.

Comparative Example 6 A cast paper was produced in the same manner as in Example 1 except that 1% of oxidized starch (Ace A, made by Oji Corn Starch) was used instead of PVA (NH-17Q), and quality evaluation was performed. .

The results obtained in Examples 1 to 11 are shown in Table 1, and the results obtained in Comparative Examples 1 to 6 are shown in Table 2.

[0059]

[Table 1]

[0060]

[Table 2]

As is clear from Table 1, according to the method of the present invention, it is possible to obtain a cast paper which has a good releasability from the cast drum, does not cause stains on the surface of the cast drum, and has an excellent glossiness. In Examples 1 to 11), when the amount of the aqueous urethane resin used was small (Comparative Example 1), the glossiness did not increase, and when polyvinyl alcohol was not used (Comparative Example 2), the cast drum surface was stained and the glossiness was increased. Get lower. Even when oxidized starch was used instead of polyvinyl alcohol (Comparative Example 6), it was almost at the same level as when polyvinyl alcohol was not used. However, when a large amount of polyvinyl alcohol was used (Comparative Example 3), the viscosity of the coating liquid was remarkably increased and the coating became impossible. On the other hand, even when the hot air temperature when drying the coating layer before re-wetting is low (Comparative Example 4) or the wind pressure is low (Comparative Example 5), the mold releasability from the cast drum and the stain on the drum are slightly. It becomes worse and the glossiness is lower.

[0062]

As described in detail above, according to the present invention, an aqueous urethane resin and polyvinyl alcohol are used in combination and the hot air temperature and the air pressure of an air dryer for drying the coating layer before rewetting are combined to obtain a specific value. By using within the range, it is possible to obtain a cast coated paper with excellent mold releasability from the cast drum without using casein, and without causing stain on the cast drum surface and with excellent gloss on the cast surface. There is an effect of providing.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of a cast coater used when producing cast paper by the method of the present invention.

[Explanation of symbols]

 1 ・ ・ ・ Paper substrate 2 ・ ・ ・ Air knife coater 3 ・ ・ ・ Dryer (air dryer) 4 ・ ・ ・ Rewetting liquid sprayer 5 ・ ・ ・ Press roll 6 ・ ・ ・ Cast drum 7 ・ ・ ・ Take off roll 8: Cast paper.

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Hidetoshi Hatta 373 Yoshioka, Yonago, Tottori Prefecture Yonago Mill, Oji Paper Co., Ltd. 72) Inventor Kosumi Kusumi 373 Yoshioka, Yonago, Tottori Prefecture Yonago Mill, Oji Paper Co., Ltd.

Claims (1)

[Claims] 1. A coating liquid composition containing a pigment and an adhesive as a main component and containing no casein is applied onto a paper base material, and the formed coating layer is dried and rewet to give a specular gloss. In the method for producing a cast coated paper, which has a high gloss finish by pressing against a heat-finished surface, (1) in the adhesive, an aqueous urethane resin is used in an amount of 2.5 to 30% by weight and polyvinyl alcohol, based on the solid content of the coating liquid, Or containing 0.1 to 3 wt% of its derivative, and (2) the hot air temperature of the air dryer for drying the coating layer before rewetting is 55 ~ 140 ° C. and the air pressure is 10 ~ 140 mmA.
A method for producing cast coated paper, characterized by maintaining at q.