JP2002227091A - Cast coated paper and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce in high speed a good-quality cast coated paper having high gloss and free from surface defects such as pinholes under conditions within a relatively reasonable range by the use of a cast coating incorporated with two kinds of air permeability improving agents. SOLUTION: This cast coated paper is produced by the following process: a base paper 1 is coated with a cast coating simultaneously incorporated with, as air permeability improving agents, either calcium formate or calcium acetate and either one of zinc compounds including zinc oxide, zinc chloride and zinc sulfate, the resultant base paper 1 is then dried to a specified moisture content using a dryer 3, wetting again the thus dried base paper 1 by coating a rewetting liquid issued from a nozzle 4 to plasticize the coating material, subsequently the resultant coated base paper is butted on the surface of a specular drum 7 heated to high temperatures, put to pressure contact with a press roll 5 to effect gloss finish; wherein, particularly, the amount of either the calcium formate or calcium acetate is preferably 0.2-1.8 pt.wt., and that of either one of the zinc compounds including zinc oxide, zinc chloride and zinc sulfate preferably 0.1-3.0 pt.wt., each based on 100 pts.wt. of the pigment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cast coated paper and a method for producing the same, and more particularly, to a cast coated paper which retains the high gloss characteristic of cast coated paper and has good printability without surface defects such as pinholes. An object of the present invention is to provide a coated paper and a method for producing the cast coated paper at a high speed.

[0002]

2. Description of the Related Art As a method for producing a glossy paper for printing called a cast coated paper, a cast paint containing a pigment and an adhesive as a main component is applied, and then a mirror finish is performed while the coated layer is in a wet state. Wet casting method in which the surface of a heated drum is pressed and dried to give a gloss finish, or gel casting method in which a wet coating layer is made into a gel state and pressed into a heated drum surface having a mirror surface and dried to give a gloss finish Further, there is known a re-wet casting method in which a wet coating layer is once dried, wetted and plasticized with a rewet liquid, and then pressed against a heating drum surface having a mirror surface.

[0003] In these methods for producing a cast coated paper, the coating layer surface, which is in a plastic state, is pressed against a heated drum surface having a mirror surface, dried, and separated from the heated drum surface to copy the mirror surface. Are common. But,
In such a manufacturing method, since the surface of the coating layer is dried in contact with the surface of the heating drum, all of the moisture in the coating layer or the moisture of the rewetting liquid passes through the paper layer to the opposite side and evaporates. Will do. As a result, pinholes and uneven gloss are likely to occur on the surface of the coating layer of the obtained cast coated paper, and it is necessary to devise operating conditions to eliminate these troubles.

On the other hand, cast coated paper is currently required to operate at an extremely low speed as compared with general art paper and coated paper which are dried from both sides and further from the coated layer surface. That is, in the wet casting method, since the paint is pressed against the heating drum surface immediately after application of the paint, the paint is pressed in the plastic state of the paint, so that the mirror gloss is easily obtained, but the paint contains a large amount of water. When drying rapidly, moisture transfer does not accompany it and surface defects such as blisters occur. Therefore, the drum temperature is set to 90 ° C.
Even if the drying load is reduced by adopting the double coating process as described below, the production speed cannot be increased to 80 m / min or more.

In the gel casting method, since the smeared paint is solidified with an aqueous solution of a specific acid or salt and then pressed against the surface of a heating drum, the drying load is reduced compared to the wet casting method, and the air permeability is improved. Operation at a drum temperature of 100 ° C. or higher is possible, but surface defects such as pinholes are likely to occur, and the production speed is limited to 90 m / min.

[0006] In this respect, the re-wet casting method is different from other wet casting methods and gelling casting methods in that the coating layer once dried is wetted and plasticized with a rewet liquid,
Since it is in pressure contact with the heating drum surface having a mirror surface, the amount of water to be dried is relatively small, and only the coating layer surface is in pressure contact with the heating drum surface in a wet state.
Larger than the law. However, the production speed was limited to around 60 m / min because the coating layer lacked plasticity when pressed against the heating drum.

In addition, this re-wet casting method is sufficient to re-wet the dried coating layer and to copy the mirror surface during the momentary pressing time between the cast drum surface (the above-mentioned heating drum) and the press roll. It is necessary to impart the plasticity of the coating layer, and at the same time, it is necessary to smoothly evaporate the water, mainly the rewet liquid, through the base paper layer. In comparison, the manufacturing conditions had to be complicated.

Hitherto, as a method of solving these problems, various studies have been made from the viewpoints of base paper, paint blending, blending and concentration of rewetting liquid, drying temperature, pressing pressure, drum temperature and the like. For example, in the formulation of paints, calcium carbonate having high air permeability is frequently used as a white pigment and a synthetic rubber latex which is a main component of an adhesive is used. For example, Japanese Patent Publication No. 1-28155 and Japanese Patent Publication No. 8-26274 Each is disclosed in the gazette. As the rewet liquid, one using a dispersant, a release agent, a pH adjuster or the like alone or in combination is disclosed, for example, in Japanese Patent Publication No. 4-15315. As for the drum temperature and pressure, there is a method in which the cast drum is heated to 100 ° C. or more, and the pressure between the cast drum and the press roll is operated at a high pressure of 180 kg / cm ² or more. As a result, even in the re-wet casting method, the production speed in the factory was about 90 m / min, and some high-speed operation was possible. However, even in these production methods, there remain problems such as stability of long-term operation, finishing quality, shortening of life of used parts and limitation of production speed, and many improvements have been required.

[0009]

The present invention has been completed as a result of studying these problems from a completely new viewpoint. That is, at the time of instantaneous pressing between the cast drum and the press roll, the plasticity of the coating layer by the re-wetting liquid is maintained to the maximum, and at the same time, the air permeability of the dry coating layer is maximized in order to efficiently remove moisture. Focusing on both of these facts, we conducted intensive studies. As a result, by adding an appropriate amount of a mixture of calcium oxide, calcium acetate, zinc oxide, zinc chloride, zinc sulfate, and the like to the cast paint at the same time, there are no surface defects such as pinholes, and a high gloss and printability. And a production method capable of producing this paper efficiently, stably and at high speed.

[0010]

According to a first aspect of the present invention, there is provided a cast paper having a pigment and an adhesive as a main component, and a dried coating layer provided on a base paper. After applying and moistening and plasticizing, the cast coated paper made by pressing against the heated mirror surface drum surface and performing a gloss finish, in the coating layer, either calcium formate or calcium acetate, further zinc oxide, It is characterized by containing any of zinc compounds such as zinc chloride and zinc sulfate. In particular, in addition to the calcium formate, by simultaneously adding an appropriate amount of a zinc compound, particularly zinc oxide, to the cast paint, the air permeability of the coating layer is dramatically improved, and at the same time, the heat transfer to the heating drum surface is improved. The plasticization of the dry coating layer by the rewetting liquid at the time of instantaneous pressure welding is also smooth, and it is possible to obtain a cast coated paper which maintains strong gloss and has no surface defects such as pinholes.

According to a second aspect of the present invention, in the cast coated paper according to the first aspect, the coating layer contains 0.1% of either calcium formate or calcium acetate per 100 parts by weight of the pigment.
2 to 1.8 parts by weight, and further contains 0.1 to 3.0 parts by weight of any of zinc compounds such as zinc oxide, zinc chloride, and zinc sulfate.

According to a third aspect of the present invention, a cast paint containing a pigment and an adhesive as main components contains either calcium formate or calcium acetate and further contains any one of zinc compounds such as zinc oxide, zinc chloride and zinc sulfate. And applying it on the base paper, drying the base paper to a predetermined moisture content, applying a rewetting liquid to the dried base paper and wetting it, and after plasticizing the coating material with the rewetting liquid, The present invention is characterized by a method for producing a cast coated paper having a process of pressing a mirror-surface drum surface heated to a temperature and applying a glossy finish. In addition to this calcium formate, by adding an appropriate amount of a zinc compound, especially zinc oxide, to the cast paint, the air permeability of the coating layer is dramatically improved, and at the same time, the instantaneous pressure contact with the heating drum surface is achieved. The plasticization of the dry coating layer by the rewetting liquid at the time becomes smooth, and high-speed production operation of cast coated paper that maintains strong gloss and has no surface defects such as pinholes becomes possible.

According to a fourth aspect of the present invention, in the method for producing a cast coated paper according to the third aspect, the immersion portion of the rewetting liquid is a nip portion formed by a drum and a pressure roll. Thereby, it is possible to prevent the rewetting liquid from excessively penetrating into the paper layer.

According to a fifth aspect of the present invention, in the method for producing a cast coated paper according to the third or fourth aspect, the cast paint is
Per 100 parts by weight of the pigment, 0.2 to 1.8 parts by weight of either calcium formate or calcium acetate, and 0.1 part by weight of a zinc compound such as zinc oxide, zinc chloride or zinc sulfate.
It is characterized by containing 1 to 3.0 parts by weight.

According to a sixth aspect of the present invention, in the method for producing a cast coated paper according to any one of the third to fifth aspects, the moisture contained in the coated layer is dried to 2 to 10%.

Hereinafter, the contents will be described in detail. The coating layer of the re-wet casting method is used to determine how to efficiently evaporate and dry moisture through the coating paper layer when pressing the casting drum through the press roll for a moment, and to smooth the coating layer by pressing the coating layer. It is important how to maintain the plasticity of the coating layer for achieving mirror surface. These two actions are often contradictory as countermeasures, and how to achieve these two actions at the same time has been the greatest problem of the present invention.

First, in order to improve the efficiency of moisture removal, the coating layer is plasticized by the rewetting liquid in the rewetting casting method. Therefore, a sufficient amount of the rewetting liquid is required for plasticizing. You. On the other hand, how to reduce the required amount depends on the fact that the rewetting liquid has a large wet plasticizing ability of the dry paint layer, and that the rewetting liquid stays only on the surface of the coating layer required for plasticization and has an effect. And must not unnecessarily cause excessive penetration of the paper layer. It is also necessary that the vapor permeability (hereinafter referred to as air permeability) of the coating layer itself be large, which is an essential quality of the coating composition. Without sacrificing the properties required for product manufacturing and use, such as operability in the manufacturing process and printability of the finished product,
It is important to keep the quality within a range that enables high-quality, high-speed production.

As a specific method, as described above, while optimizing the pigment composition of the paint, the type of the adhesive, and the blending amount,
Furthermore, as a method for positively improving the air permeability of the coating layer itself, the present inventor has conceived to add calcium formate, which has been conventionally used as a coagulant in a coagulating solution of a gelling method, to the coating material itself.

An example in which a so-called coagulant is added to a cast paint is described in Japanese Patent Publication No. 38-15575, for example, in a thermogelling method. In addition, those obtained by adding a large amount of satin white to those aiming at the same effect are disclosed in
No. 40410, and those added in small amounts are disclosed in Japanese Patent No. 2987.
No. 528. However, they are not suitable for high-speed operation because they are pressed against a heated drum, that is, a cast drum in a semi-dry state, or pressed against a cast drum without being dried in advance.

On the other hand, in the present invention, after the water content of the coating layer is dried to a predetermined amount, the coating layer is wetted with a rewetting liquid to finish the work, thereby enabling high-speed operation. At this time, the calcium formate gels the coating layer, and at the same time, the network structure of the coating layer improves the air permeability. On the other hand, if it is added directly to the paint, the viscosity of the paint will naturally increase, and furthermore, the paint will destabilize due to condensation, etc. At the same time, excessive use of the finished product quality will have an adverse effect such as surface strength deterioration. Is expected.

As a result of comprehensively examining these points, it was found that the water content of the coating layer was within the range of 2 to 10%, preferably 3 to 8%.
% After drying, the amount of calcium formate added was
It has been discovered that air permeability can be improved without sacrificing operability and finish quality by using 0.2 to 1.8 parts by weight with respect to 0 parts by weight. This amount of addition generally corresponds to 3.0 to 30 parts by weight based on 100 parts by weight of the protein adhesive.

On the other hand, zinc compounds such as zinc chloride, zinc sulfate and zinc oxide which are usually used as a water-proofing agent are also used.
As a result of examination, it was found that such an effect of improving the air permeability was great. That is, the immobilization point of the coating material is lowered by a reaction or a cohesive action in a drying step after application, and this has the effect of improving the microporous property of the coating layer. Furthermore, in the rewet casting method, various uses of the zinc compound were examined. As a result, when an appropriate amount of zinc compound is added to the paint, it produces high-gloss cast coated paper that has a strong glossy surface without surface defects such as pinholes, although the increase in paint viscosity is small and it has a water-resistant effect. I did not get the expected effect of doing so. On the other hand, although the air permeability is improved by adding a large amount of a zinc compound, a high-speed operation of 80 m / min or more in a test using a cast paper production machine causes surface defects such as pinholes.
In this case, although the air permeability is certainly improved, the water resistance is also increased, and the plasticizing action of the re-wetting liquid of the dry paint layer in the instantaneous pressure welding between the cast drum and the press roll, which is another necessary condition, is increased. Probably damaged.

Thus, by adding an appropriate amount of the above-mentioned calcium formate to the cast paint, high-speed production to some extent was made possible. However, as a result of various studies aimed at further improvement, it was found that, in addition to this calcium formate, Furthermore, by adding an appropriate amount of zinc oxide, particularly a zinc oxide, to the cast paint, the air permeability of the coating layer is dramatically improved, and at the same time, the dry coating layer is instantaneously pressed against the heating drum surface. Plasticization by re-wetting liquid is smooth, strong coated gloss is maintained, and there is no surface defect such as pinhole.
High-speed production operation at 20 m / min or more became possible.

The amount of the calcium formate added to the cast paint is 0.2 to 1.8 parts by weight, preferably 0.5 to 1.2 parts by weight, based on 100 parts by weight of the pigment. This amount of addition generally corresponds to 3.0 to 30 parts by weight based on 100 parts by weight of the protein adhesive. If the amount exceeds this amount, the viscosity of the coating material increases, eventually gelling and the operation becomes impossible. If the amount is less than this, the expected effect cannot be obtained. In the case of zinc oxide, the amount is 0.1 to 3.0 parts by weight, preferably 0.3 to 2.0 parts by weight, based on 100 parts by weight of the pigment. This addition amount corresponds to approximately 1.5 to 40 parts by weight based on 100 parts by weight of the protein adhesive. If the amount is more than this amount, the effect becomes saturated and, at the same time, a problem such as a decrease in gloss of white paper occurs. If the amount is less than this amount, the expected effect cannot be obtained.

Although the synergistic effect of the mixed use of calcium formate and zinc oxide is not always clearly understood, the network structure of zinc oxide is not sufficient to increase the air permeability due to the network structure of the coating layer developed by the use of calcium formate. It is presumed that, in addition to the effect of increasing the thickness, the immobilization effect is synergistically exhibited, and at the same time, the plasticity of the coating layer required in the press nip is sufficiently maintained.

The composition of the rewetting liquid is not particularly limited. For example, a polyethylene emulsion, a fatty acid soap, calcium stearate, a microcrystalline wax, a surfactant, a mold release agent such as a funnel oil may be used in an amount of 0.1%.
It is contained in an amount of about 0.01 to 3.0% by weight. In addition, inorganic salts such as zinc sulfate, calcium phosphate, sodium polyphosphate, sodium hexametaphosphate, sodium formate, ammonium formate, sodium soap potassium, sodium citrate, potassium citrate, sodium dioctylsulfosuccinate and the like may be used in an amount of 0.01 to 3. 0% is contained. Of these, the use of multiple phosphates such as sodium hexametaphosphate, sodium pyrophosphate, sodium tripolyphosphate, and sodium citrate, which have particularly excellent dispersing action, is suitable.

[0027]

The present invention will be described below more specifically with reference to examples. However, it goes without saying that the present invention is not limited to these.

The base paper used is clay, talc, etc. as filler, rosin sizing agent and sulfate band as fixing agent.
Either so-called acidic papermaking or so-called neutral or alkaline papermaking using clay, talc, calcium carbonate or the like as a filler, a sizing agent such as AKD or ASA, and cationic starch or the like as a fixing agent may be used. Paint is clay as white pigment,
Kaolin, light or heavy calcium carbonate, barium sulfate, plastic pigment, etc., which are white pigments usually used for coated paper, are determined in consideration of finishing quality and suitability for casting. In particular, satin white is not used because it reacts with calcium formate to increase the viscosity.

As the adhesive, a protein-based adhesive such as casein or soybean protein (protein), or a synthetic rubber latex containing butadiene / styrene, methyl methacrylate, acrylic acid or the like as a main component is usually mixed and used. In each case, the pigments are determined in consideration of the finishing quality and the suitability for casting work, as in the case of pigments. Mixing protein-based and synthetic rubber-based latex
In particular, the selection of synthetic rubber latex is important because it has a large effect on high-speed operation suitability such as air permeability and finish quality. Further, as a dispersant for the pigment, generally a multiple phosphate or sodium polyacrylate is added. Further, in order to improve the removability of the cast coating layer from the cast drum, an appropriate amount of a lubricant such as a metal salt of a fatty acid or a polyethylene compound is added. In addition, an antifoaming agent and a waterproofing agent are added as required.

The present invention is intended to obtain an appropriate amount of calcium formate or calcium acetate, zinc oxide, zinc chloride, and sulfuric acid in order to obtain high-speed workability by the re-wet casting method and excellent finish quality without surface defects such as pinholes. An appropriate amount of a zinc compound such as zinc is added. The effect of this addition is to improve the air permeability of the coating layer, as described above, and to maintain the plasticity of the coating layer sufficient to obtain smooth and high gloss at the time of instantaneous pressing between the cast drum and the press roll. That is.

The addition method and the addition order must be carefully performed since calcium formate or calcium acetate causes an effect of solidifying the paint when added to the paint. For example, the paint PH is adjusted and the amount of calcium formate or calcium acetate is divided and added. These materials are dispersed by a high-speed stirrer such as a cowles dissolver or a serie mixer to produce a paint, which is then filtered through a screen to provide the paint. 38-65% as paint solids, 50-150 as paint solids
0 cps is an appropriate range. Coating method using an air coater, a blade coater, roll coater, a rod coater, a coverage on the surface of base paper having a basis weight 40~350g / ^{m 2} is applied so that the 10 to 30 g / ^{m 2} Form a coating layer.

Next, the coating layer is a gas suitable for high-speed operation,
Drying is performed at a temperature of 100 to 200 ° C. using an air dryer or an infrared dryer using steam as a heat source. The coating layer provided on the base paper in this manner is re-wet with a re-wetting liquid to be in a plastic state, and 90 to 150
A linear pressure of 100 to 250 kg /
By pressing and drying at a pressure of cm ² , a cast coated paper having high gloss and no surface defects such as pinholes and uneven adhesion and excellent in surface strength can be produced at high speed. The smoothing work using a gloss calender, a soft calender, a super calender, etc. after coating and drying, which was conventionally required in the re-wet casting method, is necessary in the present invention because the plasticization of the coating layer at the time of pressing is sufficiently performed. And not. Conversely, the air permeability of the coating layer is undesirably hindered.

Hereinafter, more specific examples 1 to 8 and comparative examples corresponding thereto will be sequentially described. Further, the numerical values of materials and% in Tables 1 and 2 indicate parts by weight and% by weight, respectively. Example 1 Kaolin for coating (ECW UW)
90) 75 parts and 25 parts of calcium carbonate for coating (Brilliant N15 manufactured by Shiroishi Kogyo Co., Ltd.) are added to 0.8 parts of sodium polyacrylate as a dispersant to a white pigment composed of 25 parts and dispersed with a Coreless disperser. Casein (16% concentration in which 3 parts of caustic soda and 10 parts of 28% ammonia solution were added and dissolved in casein) dissolved in alkali in this pigment dispersion (concentration of 60%), and 7 parts of modified styrene butadiene were synthesized. Rubber latex (L made by Asahi Kasei Corporation)
X1385) 19 parts are added. Next, 1.0 part (10% aqueous solution) of calcium formate in solid content is added as the air permeability improving agent A to the mixed solution. Add carefully as viscosity rises sharply. Further, 0.5 part of zinc oxide is added as a permeability improving agent B. In addition, 1 part of a lubricating release agent (PEM17 manufactured by Nopco Chemical Co., Ltd.), 0.05 part of tributyl phosphate as an antifoaming agent, and an appropriate amount of a complementary color dye are added and screened to complete the paint. The finished paint had a concentration of 45%, a viscosity of 300 CP, a pH of 9.5, and a temperature of 25 ° C.

[0034] The paint base paper having a basis weight of 60 g / ^{m 2,} one side 20 g / cm ² is coating amount in an air coating machine 2 shown in FIG. 1
Then, the hot air dryer 3 using gas or steam as a heat source is dried so that the water content becomes about 6%.
The coated paper is dipped in a press-contact portion of the cast drum 7 and the press roll 5 with the nozzle 4 by a rewetting liquid containing 0.5% of sodium hexametaphosphate, and then coated with the chrome-plated cast drum 7 and urethane rubber. Between the high-pressure and high-pressure nips 6 formed between the press rolls 5, instantaneous pressurization and smoothing were performed, followed by drying with a cast drum 7 and peeling to obtain cast coated paper. Here, the immersion part of the rewetting liquid is set to the nip portion 6 formed by the cast drum 7 and the press roll 5, so that only the surface of the coating layer can be plasticized, and the excessive rewetting liquid is poured into the paper layer. No penetration. In addition, in FIG. 1, 1 is a base paper and 8 is a cast coated paper. The temperature of the cast drum 7 was set to 120 ° C., the nip pressure was set to 200 kg / cm ² , and the production speed was able to achieve 120 m / min. The production speed is 120
m / min or more was possible. As shown in Table 1, the quality of the resulting cast coated paper was as shown in Table 1. The cast coated paper had excellent gloss without surface defects such as pinholes and excellent printability such as surface strength.

Example 2 A cast coated paper was produced in the same manner as in Example 1 with the composition shown in Table 1. The quality of the obtained cast coated paper is shown in Table 1.
As shown in Table 2, a cast coated paper having excellent gloss without surface defects such as pinholes and excellent printability was obtained.

Example 3 A cast coated paper was produced in the same manner as in Example 1 with the composition shown in Table 1. The modified protein of the adhesive (manufactured by Protein Chemical Co., Ltd.) was used as a 30% aqueous solution. As shown in Table 1, the quality of the obtained cast coated paper was as shown in Table 1. The cast coated paper had excellent gloss without surface defects such as pinholes and excellent printability such as surface strength.

Examples 4 to 8 Cast coated papers were produced in the same manner as in Example 1 in the same manner as in Example 1 except that the proportions shown in Table 1, especially the ratios of the air permeability improvers A and B were changed. As shown in Table 1, the quality of the resulting cast coated paper was excellent, with no surface defects such as pinholes, excellent gloss, and excellent printability.

[0038]

[Table 1]

The measuring method is as follows. Gloss JIS P8142 75 degree method ···% Printing gloss test method Use RI printing tester. Ink used: Toyo Ink Co., Ltd. Hi-Echo Blue 0.4cc Air permeability ISO5636 (Air Permeance) ml / min Surface strength RI printing machine (Ishikawajima Sangyo Kikai Co., Ltd.) uses Toyo Ink Stick NO18 ink (ink quantity 0.6cc) ) Was used to evaluate the degree of picking of the coating layer. Pinhole The surface of the coated paper was checked with a 10-fold loupe. 4.5: Almost non-existent ... 4.0: Occasionally found △ ○ to ○ 3.5: Many 多 い ・ ・ ・ 3.0: Very Many ×

Comprehensive judgment ：: extremely good ：: good ：: problematic ×: not possible

Comparative Examples 1 to 8 Comparative Examples 1 to 8 correspond to Examples 1 to 8, respectively, and were the same as Example 1 except that the ratio of the air permeability improving agents A and B was changed. The method produced cast coated paper. The quality of the obtained cast coated paper was as shown in Table 2.

In Comparative Examples 1 to 3, the air permeability improving agent was added alone, and in Comparative Examples 4 and 6, the air improving agent was excessively added.
Comparative Examples 5 and 7 are examples in which the amount was too small. Comparative Example 8 is an example in which the same modifier was not added.

[0043]

[Table 2]

[0044]

According to the present invention, the present inventors have made intensive studies on improving air permeability and improving plasticity of a coating layer at the time of pressing, and as a result, by adding two kinds of air permeability improving agents to a cast paint, As is clear from the results in Table 1, good quality cast coated paper that retains high gloss and has no surface defects such as pinholes is produced under a relatively reasonable range of production conditions that can be easily produced. Production at a high speed of min or more has become possible.

[0045]

[Brief description of the drawings]

FIG. 1 is a schematic view of an example of a cast coating apparatus to which a method for producing a cast coated paper of the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base paper 2 Coating machine 3 Hot air dryer 4 Rewetting liquid supply nozzle 5 Press roll 6 Press nip 7 Cast drum (mirror surface drum) 8 Cast coated paper

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[Procedure amendment]

[Submission date] April 26, 2001 (2001.4.2
6)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 3

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction contents]

Hitherto, as a method of solving these problems, various studies have been made from the viewpoints of base paper, paint blending, blending and concentration of rewetting liquid, drying temperature, pressing pressure, drum temperature and the like. For example, in the formulation of paints, calcium carbonate having high air permeability is frequently used as a white pigment and a synthetic rubber latex which is a main component of an adhesive is used. For example, Japanese Patent Publication No. 1-28155 and Japanese Patent Publication No. 8-26274 Each is disclosed in the gazette. As the rewet liquid, one using a dispersant, a release agent, a pH adjuster or the like alone or in combination is disclosed, for example, in Japanese Patent Publication No. 4-15315. As for the drum temperature and pressure, there is a method in which the cast drum is heated to 100 ° C. or more and the pressure between the cast drum and the press roll is operated at a high pressure of 180 kg / cm or more. As a result, even in the re-wet casting method, the production speed in the factory was about 90 m / min, and some high-speed operation was possible. However, even in these production methods, long-term operation stability, finish quality,
Problems such as shortening of life of used parts and limitation of manufacturing speed still remain, and many improvements were needed.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction contents]

On the other hand, in the present invention, after the water content of the coating layer is dried to a predetermined amount, the coating layer is wetted with a rewetting liquid to finish the work, thereby enabling high-speed operation. At this time, the calcium formate causes the coating layer to gel, but at the same time, the network structure of the coating layer improves air permeability. On the other hand, if it is added directly to the paint, the viscosity of the paint will naturally increase, and furthermore, the paint will destabilize due to condensation, etc. At the same time, excessive use of the finished product quality will have an adverse effect such as surface strength deterioration. Is expected.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0032

[Correction method] Change

[Correction contents]

Next, the coating layer is a gas suitable for high-speed operation,
Drying is performed at a temperature of 100 to 200 ° C. using an air dryer or an infrared dryer using steam as a heat source. The coating layer provided on the base paper in this manner is re-wet with a re-wetting liquid to be in a plastic state, and 90 to 150
A linear pressure of 100 to 250 kg /
By pressing and drying at a pressure of 1 cm, a cast coated paper having high gloss and having no surface defects such as pinholes and uneven adhesion and having excellent surface strength can be produced at high speed. In addition, the smoothing work using a gloss calender, a soft calender, a super calender, or the like after coating and drying, which was conventionally required by the re-wet casting method, is necessary in the present invention because the plasticization of the coating layer at the time of pressing is sufficiently performed. And not. Conversely, the air permeability of the coating layer is undesirably hindered.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0033

[Correction method] Change

[Correction contents]

Hereinafter, more specific examples 1 to 8 and comparative examples corresponding thereto will be sequentially described. Further, the numerical values of materials and% in Tables 1 and 2 indicate parts by weight and% by weight, respectively. Example 1 Kaolin for coating (EC
0.8 parts of sodium polyacrylate as a dispersant is added to a white pigment composed of 75 parts of UW90 (manufactured by Company C) and 25 parts of calcium carbonate for coating (Brilliant N15 manufactured by Shiraishi Industry Co., Ltd.), and the mixture is dispersed with a Coreless disperser. Casein (16% concentration in which 3 parts of caustic soda and 10 parts of 28% ammonia solution were added and dissolved in casein) was dissolved in alkali in this pigment dispersion (concentration: 60%), and 7 parts in solid content of modified styrene butadiene were synthesized. 19 parts of rubber latex (LX1385 manufactured by Asahi Kasei Corporation) is added. Then
First, 1.0 part (a 10% aqueous solution) of calcium formate as a permeability improving agent A in solid content is added to this mixed solution. Add carefully as viscosity rises sharply. Further, 0.5 part of zinc oxide is added as a permeability improving agent B. In addition, 1 part of a lubricating release agent (PEM17 manufactured by Nopco Chemical Co., Ltd.), 0.05 part of tributyl phosphate as an antifoaming agent, and an appropriate amount of a complementary color dye are added and screened to complete the paint. The concentration of the finished paint is 45%, the viscosity is 300CP, PH
9.5, temperature 25 ° C.

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0034

[Correction method] Change

[Correction contents]

[0034] The paint base paper having a basis weight of 60 g / ^{m 2,} one side 20 g / cm ² is coating amount in an air coating machine 2 shown in FIG. 1
Then, the hot air dryer 3 using gas or steam as a heat source is dried so that the water content becomes about 6%. A rewetting liquid comprising 0.5% of sodium hexametaphosphate was applied to a cast drum 7 and a press roll
After being immersed in the pressure contact portion of the above, it is instantaneously pressurized and smoothed between the chromium-plated cast drum 7 and the high-temperature and high-pressure nip 6 formed between the press rolls 5 coated with urethane rubber or the like. After drying and peeling, a cast coated paper was obtained. Here, the immersion site of the rewetting liquid is defined by a nip portion 6 formed by a cast drum 7 and a press roll 5.
By doing so, only the surface of the coating layer can be plasticized, and the excessive rewetting liquid does not penetrate into the paper layer. In addition, in FIG. 1, 1 is a base paper and 8 is a cast coated paper. The temperature of the casting drum 7 was set to 120 ° C., the nip pressure was set to 200 kg / cm, and the production speed was 12
0 m / min could be achieved. The production speed is 120m / min
The above was also possible. As shown in Table 1, the quality of the resulting cast coated paper was as shown in Table 1. The cast coated paper had excellent gloss without surface defects such as pinholes and excellent printability such as surface strength. ────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] June 13, 2001 (2001.6.1
3)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0034

[Correction method] Change

[Correction contents]

This paint was applied to a base paper having a basis weight of 60 g / m ² by an air coater ² shown in FIG. 1 so that the amount of coating was 20 g / m ² on one side, and then heated with hot air using gas or steam as a heat source. Drying is performed by the dryer 3 so that the water content becomes about 6%. The coated paper is immersed in a press-contact portion of the cast drum 7 and the press roll 5 by the nozzle 4 with a rewetting liquid composed of 0.5% sodium hexametaphosphate and then coated with the chrome-plated cast drum 7 and urethane rubber. Between the high-pressure and high-pressure nips 6 formed between the press rolls 5, they were instantaneously pressurized, smoothed, dried on a cast drum 7, and peeled to obtain cast coated paper. Here, the immersion site of the rewetting liquid is defined by a nip portion 6 formed by a cast drum 7 and a press roll 5.
By doing so, only the surface of the coating layer can be plasticized, and the excessive rewetting liquid does not penetrate into the paper layer. In addition, in FIG. 1, 1 is a base paper and 8 is a cast coated paper. The temperature of the casting drum 7 was set to 120 ° C., the nip pressure was set to 200 kg / cm, and the production speed was 12
0 m / min could be achieved. The production speed is 120m / min
The above was also possible. As shown in Table 1, the quality of the resulting cast coated paper was as shown in Table 1. The cast coated paper had excellent gloss without surface defects such as pinholes and excellent printability such as surface strength.

Continued on the front page (72) Inventor Ali Alimsha Indonesia, Jakarta Utara Pluit Punjaligan Pluit Ti Muru Jayel Bjerkeel / 4 (72) Inventor Sangjen Sunkart Indonesia, Joglo-Jakarta Barat Taman Alpha Indah Jayer B19 / 18 (72) Inventor Munemi Horiuchi 5-5-11-304, Matsuba-cho, Kashiwa-shi, Chiba (72) Inventor Haruo Okada 1464-4, Ashzaki, Hitachinaka-shi, Ibaraki F-term (reference) 4L055 AG04 AG07 AG08 AG11 AG12 AG20 AG27 AG54 AG63 AG76 AG89 AH50 AJ04 BE08 EA13 EA32 FA11 FA12 FA15 GA20

Claims (6)

[Claims] 1. A base material is coated with a cast coating mainly composed of a pigment and an adhesive, and a dried coating layer is provided. The coating layer is coated with a rewetting liquid to wet and plasticize, and then heated. In the cast coated paper created by pressing against the mirror surface drum surface that has been gloss-finished, the coated layer is made of either calcium formate or calcium acetate, and further zinc oxide, zinc chloride, zinc compound such as zinc sulfate. A cast coated paper characterized by containing any one of the above. 2. The coating layer contains 0.1% of either calcium formate or calcium acetate per 100 parts by weight of pigment.
2. The cast coating according to claim 1, further comprising 0.1 to 3.0 parts by weight of any one of zinc compounds such as zinc oxide, zinc chloride, and zinc sulfate. paper. 3. A method for producing a cast-coated paper, comprising the following steps: (a) a cast paint containing a pigment and an adhesive as a main component;
A step of containing either calcium formate or calcium acetate, and further containing any one of zinc compounds such as zinc oxide, zinc chloride, and zinc sulfate, and applying the mixture on base paper. (B) a step of drying the coated paper until it reaches a predetermined moisture content. (C) a step of applying a rewetting liquid to the dried base paper to wet it. (D) a step of plasticizing the coating material with a rewetting liquid and then pressing the coating material against a mirror-surface drum surface heated to a predetermined temperature to perform a gloss finish. 4. The method for producing a cast coated paper according to claim 3, wherein the immersion site of the rewetting liquid is a nip formed by a drum and a pressure roll. 5. The cast paint contains 0.1% of either calcium formate or calcium acetate per 100 parts by weight of the pigment.
The cast according to claim 3 or 4, further comprising 2 to 1.8 parts by weight, and 0.1 to 3.0 parts by weight of any one of zinc compounds such as zinc oxide, zinc chloride and zinc sulfate. Manufacturing method of coated paper. 6. The method for producing a cast coated paper according to claim 3, wherein the moisture contained in the coated layer is dried to 2 to 10%.