JPH10168789A - Cast-coated paper and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a cast-coated paper excellent in mold release properties from a casting drum, facilitating a continuous operation for a long time and good in qualities such as drying properties of an ink and glossiness after printing. SOLUTION: This cast-coated paper is produced by using a styrene-butadiene latex having 50-65% butadiene content in a coating liquid for coating a base paper in a method for producing the cast coated paper by including a polyoxyethylene alkyl ether in a rewetting liquid in a rewetting method or in a coagulating liquid in a coagulating method, and rewetting or coagulating the coated layer, and pressing the rewetted or coagulated coated layer to be brought into contact with a mirror plane drum having a saturated fatty acid and/or a salt thereof coated on the surface to perform a mirror plane processing.

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 capable of producing a high quality product extremely efficiently.

[0002]

2. Description of the Related Art Conventionally, cast coated papers having high glossiness have been used for publishing, commercial printing, adhesive label paper, packaging and packaging. In publishing applications, it is used for covers such as magazines, weekly magazines, comic magazines, and the like. In recent years, comic magazine applications have been increasing. In the commercial printing field, it is used for posters, catalogs, calendars, pamphlets, etc., and recently the demand has been increasing especially for the cover of mail-order catalogs. Demand for adhesive label paper, packaging, and packaging is stable for food, light electrical goods, and luxury goods packaging.

In the production of cast coated paper, a base paper surface is coated with an aqueous coating liquid containing a pigment and an adhesive as a main component to form a cast coated layer. It is manufactured by pressing and drying on a mirror-surfaced drum made of aluminum.

[0004] Typical methods for producing this cast coated paper include a re-wetting method in which a wet coating layer is once dried, then plasticized by re-wetting and pressed against the surface of a heating drum, or a wet coating. There are known a coagulation method in which a layer is brought into a gel state and pressure contact with a heating drum, and a direct method in which a wet coating layer is brought into pressure contact with a heating drum as it is. In all of these methods, the coating layer in a plasticized state is peeled off from the drum surface while being pressed and dried on the drum surface.However, it is necessary to obtain a stable release property under a long continuous operation. Is an important issue in improving

[0005] Conventionally, as a method for improving the releasability,
(1) a method of applying a release agent to a drum surface, (2) a method of adding a release agent to a coating liquid, and (3) a method of adding a release agent to a rewet liquid or a coagulation liquid, etc. Have been.

Examples of the release agent used in the above method (1) include synthetic resins such as polyethylene, metal salts of fatty acids or higher fatty acids, fatty acid amides, higher alcohols, tributyl phosphoric acid and puffing wax. As the release agent used in the method (2) or (3), polyethylene emulsion,
Examples include an alkyl ketene dimer and a nonionic surfactant.

[0007] However, even when these release agents are used, peeling failure occurs after about 5 hours of operation, and a part of the coating layer starts to adhere to the drum surface (hereinafter referred to as a drum pick). In this case, the entire paper sticks to the drum surface and does not peel off.

The cause of such a problem is as follows.
It is considered that the release agent interposed between the heating drum and the coating layer is successively carried away by the coating layer during operation, and the amount of the release agent is insufficient, so that the drum pick is likely to be generated.
It is conceivable to increase the amount of the release agent used to improve the releasability, but in such a case, new problems such as poor fixing of the printing ink and poor drying properties occur. Therefore, it is necessary to stop the operation several times a day and supply the release agent to the drum surface. Each time, the operation must be stopped for about one hour, resulting in a significant decrease in production efficiency. The current situation is to do it. Therefore, in the re-wetting method and the coagulation method, it is a major problem to improve the release agent so that continuous operation can be performed particularly stably for a long time.

In order to solve such a problem, the present inventors have made the rewetting liquid or the coagulating liquid contain a polyoxyethylene alkyl ether and have the mirror surface drum surface contain saturated fatty acids having 11 to 17 carbon atoms and / or saturated fatty acids. Alternatively, it has been found that a cast-coated paper can be stably manufactured for a long time by applying the metal salt thereof (Japanese Patent Application Laid-Open No. H3-113090). However, from the viewpoint of productivity, further improvement in continuous operability has been demanded. In addition, in terms of quality, especially when used for adhesive label paper in recent years, if the ink drying property is slow, the problem that the ink on the printing surface adheres to the release paper in a wound state after printing increases, Conventionally, there is a tendency that a cast coated paper having a high ink drying property is demanded from the market.

[0010]

SUMMARY OF THE INVENTION In view of the above situation, an object of the present invention is to provide a method for producing a cast coated paper using a rewetting liquid or a coagulating liquid, such as ink drying property and gloss after printing. An object of the present invention is to provide a method for producing cast coated paper with good quality and stably for a long time.

[0011]

Means for Solving the Problems As a result of intensive studies on the above-mentioned problems, the present inventors have found that polyoxyethylene alkyl ether is contained in the rewet liquid in the rewet method or the coagulation liquid in the coagulation method, and A mirror surface drum is coated with a saturated fatty acid having 11 to 17 carbon atoms and / or a metal salt thereof, and the coating layer re-wetted or solidified by each of the above methods is pressed against the coated mirror drum to finish the mirror surface. In a method for producing a cast coated paper, the present invention has been accomplished by including a styrene / butadiene copolymer having a butadiene content of 50 to 65% in a coating liquid applied to a base paper.

The prior art of the present invention (Japanese Patent Laid-Open No. Hei 3-111309)
No. 0), a polyoxyethylene alkyl ether is contained in a rewet or coagulation liquid, and a saturated fatty acid having 11 to 17 carbon atoms and / or a metal salt thereof is applied to the surface of a mirror drum for a long time. Although it was recognized that stable operation was possible, further detailed examinations revealed that continuous operability greatly varies depending on the pigment, adhesive type, composition, and formulation applied to the base paper. Further, since these changes in the manufacturing method have a large effect on the quality such as ink drying property, it is necessary to balance the operability and the quality.

In the present invention, by limiting the butadiene content of the styrene / butadiene latex used in the coating liquid to the range of 50 to 65%, the time which is more than 30% longer than that of the prior art can be obtained. Stable operation was possible, which led to a 30% or more increase in production, and productivity was greatly improved. At the same time, the ink drying property was good.

When a butadiene content of less than 50% is used, the continuous operation time is generally about 10 to 12 hours, depending on conditions such as the composition of the coating liquid and the coating speed. Was enough.

On the other hand, it has been found that when the butadiene content exceeds 50%, the continuous operation time increases with the butadiene content. However, even in that case, when the butadiene content is more than 65%, the deformability is large, and the coating layer becomes porous, so that the ink drying property becomes too fast, and the glossiness after printing of the cast coated paper decreases. occured. The reason why the continuous operability is improved as the butadiene content of the latex becomes 50% or more is not clear, but the saturated fatty acids having 11 to 17 carbon atoms and / or used as a release agent to be coated on the mirror drum surface are used. The decrease in affinity and wettability between the metal salt and the latex suppresses the transfer of the release agent to the coating layer, and enables the release agent thin film on the cast drum surface to be kept uniformly for a long time. Conceivable.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The pigment used in the present invention includes:
One or more types of kaolin, clay, light calcium carbonate, light calcium carbonate, zinc oxide, synthetic silica, satin white, plastic pigment, and the like generally used for papermaking are used.

The composition of the styrene / butadiene copolymer latex used in the present invention may be a commonly used styrene / butadiene copolymer, styrene / butadiene / acrylic copolymer or a modified product thereof. As monomers, other vinyl compounds such as styrene, butadiene, methyl methacrylate, other vinyl-based unsaturated carboxylic acid ester compounds and acrylonitrile,
Alternatively, a vinyl unsaturated carboxylic acid such as acrylic acid or fumaric acid is used. In consideration of strength characteristics and water resistance, the gel content of the latex is preferably 45 to 85%, and the amount of the latex is preferably 10 to 25 parts by weight based on 100 parts of the pigment.

Other commonly used adhesives include casein, soybean protein, synthetic proteins, polyvinyl alcohol and oxidized starch, esterified or esterified starch, enzyme-modified starch and flash-dried thereof. Starches such as cold water-soluble starch or cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose are used. The proportion of these adhesives used is 10 parts by weight per 100 parts by weight of pigment.
-30 parts by weight are preferred.

In the coating liquid of the present invention, various auxiliaries, such as a dispersant, a thickener, a water retention agent, a defoaming agent, and a water-proofing agent, which are blended in a general pigment for coated paper may be used. The base paper used in the present invention is a base paper having a basis weight of 50 to 400 g / m ² used for general printing coated paper or cast coated paper. To use. In addition, a base paper may be used in which the surface of the cast coated paper is coated with the undercoat or the coated paper whose back surface is coated.

The coating amount of the cast coated paper on the base paper is preferably in the range of 15 to 35 g / m ^{2 in} solid content per one side of the base paper.

The coating layer thus formed on the base paper is re-wetted or coagulated by a re-wetting liquid or a coagulating liquid, and is pressed against a heated mirror drum to be manufactured.

[0022]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited by these examples. In the examples, parts and% indicate parts by weight and% by weight, respectively. The quality evaluation method is described below.

<Quality evaluation method> (1) Ink drying property Toyo Ink T was manufactured using an RI-II printing machine (manufactured by Meiji Seisakusho).
Using K mark V617 Sumi, printing is performed with a constant ink amount of 0.5 ml. Immediately after printing, transfer paper (high quality coated paper) is covered on the printed material sample, and after 45 seconds, transfer is performed at the same rotation speed. From the change in the whiteness of the transfer paper, the ink drying property is calculated by the following equation.

Ink drying property = whiteness of white paper of transfer paper−whiteness of transfer paper after transfer (%) Therefore, the smaller the value, the faster the ink drying property.

(2) Glossiness after printing Using an RI-II type printing machine (manufactured by Meiji Seisakusho), using a printing ink (Diatone GSL red) manufactured by Sakata Inks, printing with a constant ink amount of 0.35 ml, and leaving it overnight. After 20 degrees, the gloss was measured.

(3) Continuous operability The following relative evaluation was performed.

：: Continuous operation is possible for 20 hours or more. ：: Continuous operation is possible for 16 hours to less than 20 hours. Δ: Continuous operation is possible for 12 hours to less than 16 hours. It is impossible to operate continuously for 12 hours or more. [Example 1] To 100 parts of kaolin, 0.2 parts of a sodium polyacrylate-based dispersant was added, and dispersed in water using a Cowles disperser. A pigment slurry having a solid content of 60% was prepared. 0.2 parts of tributyl phosphate as an antifoaming agent, 7 parts of a casein aqueous solution (solid content concentration: 18%) dissolved using ammonia as an adhesive, and a styrene / butadiene copolymer having a butadiene content of 55% 17 parts of latex was added, and 2 parts of calcium stearate and 0.6 part of a nonionic emulsifier were added as a release agent. Finally, water and ammonia were added to obtain a solid content of 48 parts.
% And pH were adjusted to 10.0.

A 10% calcium formate solution was prepared as a coagulating liquid, and 0.3 parts of a polyethylene wax emulsion and 0.3 parts of polyoxyethylene alkyl ether (carbon number: 16) were added as a releasing agent.

Further, stearic acid (carbon number: 17) was applied to the mirror-surface drum and buffed.

Using the coating liquid prepared by the above method,
A coating liquid is applied on one side of base paper containing only bleached kraft pulp having a basis weight of 110 g / m ² to make a dry coating amount of 21 g / m ^2, and then a release agent is added. The coating layer was coagulated by contact with the coagulating liquid thus obtained. Thereafter, a press roll of 750 mm in diameter and a cast drum of 3000 mm in diameter with a surface temperature of 105 ° C. and a press pressure of 130 kg /
cm, and after drying, peeled off from the cast drum with a take-off roll to produce a cast coated paper. The processing speed was 40 m / min.

Example 2 A coated paper was produced in the same manner as in Example 1 except that a latex having a butadiene content of 62% was used.

Example 3 For 100 parts of kaolin,
0.3 parts of a sodium polyacrylate dispersant was added, and the mixture was dispersed in water using a Cowles disperser to prepare a pigment slurry having a solid content of 60%. 0.5 parts of the defoamer was added to this,
10 parts of a casein aqueous solution and 15 parts of a styrene-butadiene copolymer latex having a butadiene content of 55% were added as an adhesive, and 5 parts of calcium stearate was added as a release agent, and a coating solution having a solid content of 50% was added. Prepared.

This coating liquid was coated on a base paper having a basis weight of 70 g / m ^{2 by} a blade coater so that the dry coating amount was 25 g / m ^2, and then dried with an air dryer until the paper moisture became 7%. Was. Then, in a nip formed by a forming roll having a diameter of 750 mm and a cast drum having a diameter of 3000 mm, a polyethylene wax emulsion and a polyoxyethylene alkyl ether (having a carbon number of 1) were formed.
After the surface of the coating layer is rewet with a rewet liquid (1% concentration) composed of 6), it is pressed on a cast drum having a surface temperature of 110 ° C. at a press pressure of 100 kg / cm, dried, and then stearic acid (C17). Was peeled from the cast drum which had been coated and buffed to produce a cast coated paper.

Comparative Example 1 A coated paper was manufactured in the same manner as in Example 1 except that a latex having a butadiene content of 31% (trade name: SN307, manufactured by Sumitomo Nogatack Co., Ltd.) was used.

Comparative Example 2 A coated paper was produced in the same manner as in Example 1 except that a latex having a butadiene content of 40% was used.

Comparative Example 3 A coated paper was produced in the same manner as in Example 1 except that a latex having a butadiene content of 70% was used.

[Comparative Example 4] A latex having a butadiene content of 55% was used, and a mirror drum (with 11 to 11 carbon atoms) was used.
Coated paper was manufactured in the same manner as in Example 1 except that the saturated fatty acid and / or its metal salt of No. 17 were applied.

Comparative Example 5 A coated paper was produced in the same manner as in Example 3 except that a latex having a butadiene content of 35% was used.

Table 1 shows the above results.

[0040]

[Table 1] As is clear from Table 1, Examples 1 to 3 were excellent in continuous operation, ink drying property and glossiness after printing. In contrast, in Comparative Examples 1 and 2, the glossiness after printing was good, but the continuous operability was poor. In Comparative Example 3, although the operability was good, the glossiness after printing was considerably low, and there was a problem in quality. Comparative Example 4 had good glossiness after printing, but was inferior in operability. In Comparative Example 5, the continuous operability was poor, and the ink drying property was slow.

In the present invention, continuous operability could be improved by 30% or more as compared with Comparative Example 1 using the latex of the above-mentioned prior art document having a lower butadiene content as claimed in the claims. This led to an increase of more than 30% in the production volume, and the productivity was greatly improved. Also, compared to when using a latex higher than the butadiene content of the present invention,
Good quality was obtained without any decrease in gloss after printing. Therefore, according to the present invention, a good cast coated paper having both operability and quality can be obtained.

[0042]

The cast coated paper produced by using the latex produced according to the present invention has good release properties, enables stable continuous operation for a long time, ink drying property, glossiness after printing, etc. Of cast coated paper with good quality.

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[Procedure amendment]

[Submission date] December 26, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction contents]

[0004] Typical methods for producing this cast coated paper include a re-wetting method in which a wet coating layer is once dried, then plasticized by re-wetting and pressed against the surface of a heating drum, or a wet coating. There are known a coagulation method in which a layer is brought into a gel state and pressure contact with a heating drum, and a direct method in which a wet coating layer is brought into pressure contact with a heating drum as it is. In all of these methods, the coating layer in a plasticized state is peeled off from the drum surface while being pressed and dried on the drum surface.However, it is necessary to obtain a stable release property under a long continuous operation. Is an important issue in improving

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction contents]

The prior art of the present invention (Japanese Patent Laid-Open No. Hei 3-111309)
No. 0), a polyoxyethylene alkyl ether is contained in a rewet or coagulation liquid, and a saturated fatty acid having 11 to 17 carbon atoms and / or a metal salt thereof is applied to the surface of a mirror drum for a long time. Although it was recognized that it could be operated stably, as a result of further detailed examination, it was recognized that continuous operability greatly differs depending on the type and composition of the pigment and adhesive applied to the base paper. Further, since these changes in the manufacturing method have a large effect on the quality such as ink drying property, it is necessary to balance the operability and the quality.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0023

[Correction method] Change

[Correction contents]

<Quality evaluation method> (1) Ink drying property Using a printing ink (TK mark V617 black) manufactured by Toyo Ink using a RI-II type printing machine (manufactured by Meiji Seisakusho), the ink amount was kept constant at 0.5 ml. Printing is performed, and immediately after printing, a transfer paper (high quality coated paper) is covered on the printed material sample, and after 45 seconds, it is transferred at the same rotation speed. From the change in the whiteness of the transfer paper, the ink drying property is calculated by the following equation.

Claims (2)

[Claims] 1. A rewetting liquid in a rewet method or a coagulation liquid in a coagulation method containing a polyoxyethylene alkyl ether, and a coating layer rewet or coagulated by each of the above methods is coated on the surface with 11 carbon atoms. Of a cast coated paper which is mirror-finished by pressing against a mirror drum coated with a saturated fatty acid and / or a metal salt thereof, wherein the butadiene content is 50 to 65% in the coating liquid applied to the base paper A method for producing a cast coated paper, characterized by containing a styrene / butadiene copolymer latex in the range of (1). 2. A cast coated paper manufactured by the method according to claim 1.