JPH0551898A - Production of multi-coated paper - Google Patents

Abstract

PURPOSE:To efficiently obtain a multi-coated paper useful as an information- recording paper, etc., without linear trace troubles such as streak by adjusting the surface roughness of the coated layer to a prescribed toughness and subsequently forming one or more upper coating layers by blade coating. CONSTITUTION:In production of a multi-coated paper in which one or mere upper coating layers are formed on an undercoating layer-containing substrate, the objective multi-coated paper is obtained by forming one or more layers of the above-mentioned upper coating layers by blade coating and adjusting the surface roughness of the coating layer surface before application of blade coating to 8-30mum in terms of surface roughness (Rmax) defined by JIS B0651 by surface treatment of the surface to be coated using a rigid surface-roughing roll. In addition, the applied coating weight in blade coating is preferably >=15g/m<2> per one side.

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 multi-layer coated paper, and more particularly to a method for producing a multi-layer coated paper which does not cause streak and scratches due to blade coating.

[0002]

2. Description of the Related Art In recent years, with the diversification of printed materials and the convenience of information recording papers (pressure-sensitive copying papers, thermal recording papers, electrostatic recording papers, etc.), printing coated papers and information recording papers have been printed or recorded. As a medium, higher quality and higher quality are required. On the other hand, manufacturers that manufacture these papers must select products that have excellent quality efficiently and in consideration of profitability, while considering operability and economic efficiency according to their applications and purposes. Has become essential.

Generally, in a method for producing a coated paper in which a coating liquid containing a pigment and an adhesive as a main component is applied to a base paper and dried to finish, a size press coater, a bar coater, an air knife is used as a coating device. Coater, roll coater,
Rod blade coaters, doctor blade coaters, etc. are used.These coating devices can be used individually or in line with multiple coaters of the same type depending on the quality design of the final product and the purpose and application of the product. The above coaters are appropriately combined and used for one-time coating or multi-layer coating.

By the way, in the case of producing coated paper for printing, a blade using a coating liquid having a high solid content concentration of 50 to 70% by weight among these coating apparatuses (hereinafter referred to as coaters). Since the coating method dries the coating liquid layer quickly,
Not only the equipment and energy cost required for drying can be saved and high-speed coating is possible, but since the coating liquid layer solidifies before moving along the uneven surface of the base paper (undercoat coating layer),
It can form a coated layer surface having high smoothness, and is a major coater particularly when producing coated paper for printing.

On the other hand, as described above, the blade coating provides a high-speed and high-smooth coating layer surface, but on the other hand, it is caused by minute foreign matters mixed in the coating liquid and lumps of the coating liquid. It is easy to induce streak and scratches called scratches on the surface of the coating layer, which is a problem of blade coating. These streaks and scratches have a great adverse effect on the operation or on the quality of the product, especially in the production of coated paper for high-grade printing, which often causes streak trouble during coating of a multi-layer blade, which is improved. Has become an urgent and important issue.

[0006] Conventionally, several proposals have been made as a method for improving the streak trouble associated with blade coating. For example, in Japanese Patent Laid-Open No. 3-59195, attention is paid to the water retention property of the coating liquid, and after the coating liquid is transferred to the web, the coating liquid is scraped by a blade and leveled (leveled). Moisture in the paper is absorbed by the paper, it has been proposed to suppress the occurrence of streaks and scratches by preventing the increase in viscosity due to the increase in the solid content concentration of the coating layer liquid, a minute metal, The effect of preventing streak trouble cannot be expected for coating liquids containing foreign substances such as minerals or plastics.

Further, in JP-A-2-234998, in order to obtain good smoothness and gloss of coated paper, after providing an undercoating coating layer of 1 to 8 g / m ^{2 on} one side of the base paper, smoothness is obtained. The smoothness of the undercoat layer is treated to be 100 to 500 mmHg and the overcoat layer is formed on the undercoat layer with a flooded nip blade coater. Is disclosed.

Rather than blade coating directly on a base paper with a large unevenness and low smoothness made by a paper machine, the base paper is once smoothed by a machine calender, or pre-coated on the base paper in advance and calendered. It is well known that, when treated, the top coating layer is finished as a coating layer having higher smoothness only because the lower layer is smooth, which is a widely practiced method. The mechanism of streaking occurs when fine foreign substances mixed in the coating liquid bite into the wedge-shaped nip formed by the blade and the web.

In Japanese Patent Laid-Open No. 2-234998, after the undercoat layer has a smoother smoothness value of 100 mmHg or less,
It is described that it is not preferable to apply a blade coating thereon because streaks are generated. Smoother smoothness measuring device has a width of approximately 53 mm on the bottom of a cylinder with a base diameter of 53 mm.
It is a measuring method that has multiple ring-shaped contact surfaces of 500 μm, presses an attachment (measurement head) sucking at a vacuum degree of 760 mmHg from between the rings against the surface of the object to be measured, and determines the smoothness by the degree of decrease in the vacuum degree. .. Therefore, the smoothness value may change subtly depending on the size and condition of the unevenness of the paper surface to be measured, and the smoothness may not always be faithful. Even if the smoother smoothness value is 100 mmHg or less, streaks occur. It is possible that you will not. In other words, defining the presence or absence of streak with the smoother smoothness value has some difficulty in terms of reproducibility.

By the way, in the case of the coated paper for printing, the coating amount tends to increase as the coated paper for high-grade printing becomes higher, and the blade coating is the mainstream in the coating method. The specifications are such that high-speed coating can be performed using a coating liquid having a concentration, and the surface of the coating layer is very smooth and easy to finish. Therefore, for example, in the case of a multi-layer coating using only a blade coater, it is easy to obtain a flattened coating layer surface without subjecting the undercoat layer formed by the blade coater to a marked smoothing treatment (calendering, etc.). Moreover, streaks are likely to occur frequently, and the actual situation is that no satisfactory streak solution has been found yet.

[0011]

From the actual situation as described above,
The present inventors, in the method of manufacturing a multilayer coated paper containing at least a blade coating layer, as a result of earnestly researching a coating method that does not cause streak and other streak troubles,
After roughening the undercoat coating layer surface before blade coating within the specified range, blade coating can efficiently obtain high quality multilayer coated paper without inducing streak trouble. I found a way.

[0012]

The present invention provides a method for producing a multi-layer coated paper comprising at least one overcoating layer provided on a support provided with an undercoating layer. One or more layers are formed by blade coating, and the surface of the coating layer before carrying out blade coating is subjected to surface treatment with a hard roughening roll to provide a coating layer surface of JIS B0651.
The method for producing a multi-layer coated paper is characterized in that the surface roughness (Rmax) defined in 8) is set to 8 to 30 μm.

[0013]

INDUSTRIAL APPLICABILITY The present invention is applied to all coated papers adopting the blade coating method, and particularly coated papers for high-grade printing (from heavy coating amount to at least one blade coating layer). The effect desired by the present invention is extremely remarkably exerted in the production of (a). Therefore, the case of application to high-quality printing coated paper will be described in detail below.

Generally, the grade ranking of coated paper for printing is mainly determined by the values of glossiness and smoothness of the paper surface. Increasing these values is conventionally achieved by increasing the coating weight. For example, so-called lightly coated paper, which is often used for leaflets and the like where gloss and smoothness after printing are not strongly required, has a dry coating weight of about 5 g / m ^{2 on} one side and is ranked as medium. Coated paper (A ₂ grade)
In 10 to 20 g / m ^2, art paper used in the exclusive art prints and catalogs such (A ₁ grade) in 25~40g / m ²
Is divided into 1 to 2 to 4 layers by using various coaters.

In order to obtain a coated surface that is as smooth as possible, it is desirable to coat the high-concentration coating with a blade coater several times to coat multiple layers. However, when applying a multi-layer coating with a blade coater, the coating layer surface previously coated with the blade coater is finished to be smooth and finished, so when coating with the blade coater subsequently thereon, the coating liquid The fine foreign matter inside is transferred to the web and bites into the nip formed by the blade coating tip and the smooth coating surface already provided by blade coating, causing streaks on the newly formed coating layer surface. Let The occurrence of this streak is very easily influenced by the unevenness of the paper surface coated with the blade.

Incidentally, when blade coating is applied directly to a base paper with a coating for coating which has been appropriately screened, streaking is extremely small. When a blade coating is applied a second time to the base paper and a blade coating is applied a second time, streaks occur, and when a blade coating is performed a third time on the surface, streaks are likely to occur.

On the other hand, even if blade coating is applied to the coated layer surface coated on the base paper with an air knife, the streak generated is slight, but the coated surface coated with this air knife is a normal surface. Surface roughness (Rmax) after surface treatment with a soft calender composed of flat metal roll and elastic roll
When the blade coating is applied to the coating layer surface smoothed to 3 to 4 μm, streaks are likely to occur frequently.

According to the present invention, the surface of the coating layer smoothed by blade coating is treated with a hard surface roughening roll, and the surface roughness Rmax of the surface of the coating layer is roughened to 8 to 30 μm. By doing so, a streak, scratch, or other streak trouble does not occur even if blade coating is performed on the coated paper. In this case, there is a close relationship between the size of foreign matter mixed in the coating liquid, the roughness of the coating layer surface, and the thickness of the coating liquid layer during coating.

That is, the size of the foreign matter in the coating liquid is 250 μm.
(Equivalent to the mesh size of the screen of 60 mesh) If it is above, there may be serious defects such as paper breaks during operation. Among the sieve screens that are commercially available, the mesh size is the smallest 325-
Screening with 400 mesh (opening 44-37 μm) reduces streaks that occur, but the filtration performance of the coating liquid is extremely reduced, and a large amount of equipment is required to avoid this difficulty, making it practical. is not. Therefore, a screen with a sieve mesh of about 200 mesh (opening 74 μm) is widely used in consideration of economy from the viewpoint of equipment and operation.

From the above, when a normal blade coater is operated using a coating liquid that has been subjected to a 200-mesh screen treatment (screening), it is necessary to consider the inclusion of foreign matter having a maximum size of 74 μm or less. At the time of coating, regarding the thickness of the coating liquid layer, streak does not theoretically occur if the thickness of the coating liquid layer is larger than the size of the foreign matter, and conversely the thickness of the coating liquid layer is smaller than the foreign matter. And streak will occur. For example, when a coating liquid having a concentration of 58% by weight and a specific gravity of 1.5 is applied with a blade coater so that the coating amount after drying is 22 g / m ² , the coating liquid layer has a thickness of about 25 μm, and 15g /
In the case of m ² , it is about 17 μm, and if foreign matter larger than the respective thickness is mixed in the coating liquid, streaks will occur.

However, an uncoated paper surface, that is, a base paper (surface roughness Rmax = 25 to 35 μm) or a base coating layer surface (surface roughness Rma) coated once on the base paper with an air knife coater
x = about 15μm) 200 mesh screen (opening 74μ)
m) Streak trouble hardly occurs when blade coating is performed using the treated coating liquid. This means that even if the size of the foreign matter is larger than the thickness of the coating liquid layer + the coated paper surface Rmax, streak will occur if a certain degree of surface roughness is given to the paper surface before blade coating. It tells that it will be suppressed.

From the above, the inventors of the present invention pay attention to the roughness of the surface of the coating layer, for example, coating twice by only blade coating, and the surface roughness Rmax of the coating surface of the first layer is 5 If a blade coating is further applied to a flat coating layer surface of ~ 7 μm, streaks frequently occur, and it is difficult to commercialize it. However, the flat coating surface is previously treated with a hard roughening roll, The inventors have found that streak formation is significantly suppressed by roughening the surface so that the surface roughness Rmax is 8 μm or more and then applying blade coating thereon, and finally completed the present invention.

That is, it is desirable to increase the degree of roughening of the coating layer surface in order to prevent the occurrence of streaks. However, if the degree of roughening is too large, the finished surface after blade coating will eventually become Even if a smoothing process such as super calender is performed on the surface, it becomes difficult to obtain a coated surface with high smoothness due to the influence of the large irregularities that have been roughened until then, and as a result, offset printing It has been found that in so-called gravure printing, only products with poor ink transfer and poor dot reproducibility, so-called poor printability, can be obtained.

The inventors of the present invention have further earnestly studied and studied the degree of roughening of the coated layer surface, and as a result, particularly the surface roughness Rma of the coated layer surface before the final blade coating.
When x is finished to have a surface roughness specified to 8 to 30 μm, preferably 12 to 25 μm, and a final coating layer is provided on it by a final blade coating, streaks and scratches are scarcely generated, and a blank sheet is obtained. Even the appearance does not recognize the unevenness of the surface,
It has been found that a coated paper having an extremely white paper appearance and a good print finish can be obtained.

As described above, the coating liquid layer thickness and the coated paper surface Rma
The reason why streak trouble does not occur when blade coating a coating liquid containing a foreign substance larger than the value obtained by adding x is
It is not always clear, but it is easy for foreign matter to bite into the concave portion of the coating layer surface formed by the roughening roll, and the whole or several 10% of the size is buried in the depression,
As a result, the foreign matter is smaller than the thickness of the coating layer, and it is presumed that the occurrence of continuous long streaks and scratches is suppressed because it passes through the wedge-shaped nip together with the web during coating. ..

The coating can be applied not only on one side but also on both sides, and it is naturally possible to apply two layers per one side, as well as three layers and more than two layers. The coater used for coating and the place where the coater is installed are not particularly limited, and for example, a combination blade coater, a flooded nip coater, a trailing blade coater, a bill blade coater, or the like can be appropriately used. In this case, coaters of the same kind or coaters of different kinds may be appropriately combined and used. Further, the coater may be either a so-called on-machine coater system provided on the paper machine or an off-machine coater system different from the paper machine, and of course, a combination of both types is also possible. Regarding the composition of the coating liquid to be used, the same paint or different paints can be appropriately used according to the purpose.

The solid content concentration, viscosity, etc. of the coating liquid at the time of coating are not specified, but the opening 74 μm (screen mesh
It is desirable to use a screened coating solution of about 200 mesh). In the present invention, it is desirable that the amount of coating applied per blade coating be as large as possible. By the way, if it is a small amount, for example, 74
When a coating liquid that has passed through a screen with a mesh opening of μm is used, it is impossible to prevent the inclusion of finer metallic foreign substances and the like below that. For this reason, when a small amount of coating is applied by blade coating, streak, scratches and other streak troubles are likely to occur. Therefore, in the present invention, if possible, the minimum amount of blade coating should be 15 g dry weight.
/ M ² is preferable.

In the method of the present invention, the material of the hard surface-roughening roll used and the surface-roughening method are not particularly limited, and generally, metals, ceramics, plastics, and rubbers widely used in the art are used. The surface of a hard roll made of such a material as described above may be processed by a sandblasting method, a corrosion method, a plasma method, or the like, and an uneven pattern may be appropriately used. The surface roughness of the hard roll is not particularly limited as long as the surface of the coated layer can be roughened to an Rmax value of about 8 to 30 μm, but is usually about 8 to 60 μm. Rolls are used.

The material and hardness of the elastic roll used as the facing roll of the roughening roll are not particularly limited, but for example, natural rubber, synthetic rubber, various plastic resins, cotton, paper, wool, tetron. Examples of the elastic body are made of nylon, nylon, or a mixture thereof, and have a Shore D hardness of 80 to 95 °. The roughening roll may be used in any of a super calender, a soft compact calender, an embossing machine and the like. Further, the installation location may be on the paper machine, on the coating machine, or separately from them, and the pressure nip conditions, linear pressure, etc. may be adjusted appropriately according to the coating amount, the water content of the coating layer, etc. To be done.

Next, the coating liquid used in the present invention may be any coating liquid which is usually used for coated paper, and the pigments, adhesives and other auxiliaries which are the constituents are not particularly limited. Not something. By the way, as the pigment constituting the coating liquid, for example, clay, kaolin, calcium carbonate, aluminum hydroxide, talc, zinc oxide, titanium dioxide, satin white, plastic pigment, binder pigment, etc. One type or two or more types are appropriately selected and used.

Further, examples of the adhesive include proteins such as casein, soybean protein and synthetic protein, conjugated diene copolymer latex such as styrene-butadiene copolymer,
Acrylic polymer latex such as polymer or copolymer of acrylic acid ester and / or methacrylic acid ester,
For ordinary coated paper such as vinyl-based polymer latex such as ethylene-vinyl acetate polymer, oxidized starch, positive starch, esterified starch, starch such as etherified starch, cellulose derivative such as carboxymethyl cellulose and hydroxyethyl cellulose One kind or two or more kinds of adhesives are appropriately selected and used.

It should be noted that the adhesive is 4 parts by weight per 100 parts by weight of the pigment.
It is adjusted in the range of about 50 parts by weight, preferably about 10 to 30 parts by weight. Further, various auxiliary agents such as an antifoaming agent, a colorant, a release agent, a flow modifier and an antiseptic agent are appropriately blended in the coating liquid.

The base paper used in the method of the present invention includes:
Generally, bleached or unbleached kraft pulp or unbleached high-yield pulp, mechanical pulp, and high-quality coating base paper or medium-quality coated paper made from recycled paper of these using acidic or neutral papermaking. Although base paper is used, it is not limited to these, and synthetic paper, plastic film,
It is also possible to use a non-woven fabric instead of the base paper.

[0034]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.
In addition, unless otherwise indicated, the part and% in an example show a weight part and weight%, respectively.

Examples 1 to 3

[Preparation of base paper] 20 parts of NBKP and LBKP
80 parts of beaten pulp dispersion with rosin size
Add 0.3 parts and 15 parts of papermaking talc as a filler, adjust the pH to 4.5 with a sulfuric acid band to prepare a stock, make a base paper using a Fourdrinier paper machine, and machine on both sides of this base paper. Drying weight of oxidized starch solution by size press machine is 1.5g / m
Apply size press coating to ² and dry.
A base paper for coated paper of g / m ² was obtained.

[Preparation of coating liquids A and B] 65 parts of kaolin as a pigment, 25 parts of calcium carbonate having an average particle size of 1.8 μm and 10 parts of satin white, and further 7 parts of a 25% starch aqueous solution (solid content) as an adhesive. ) And a styrene-butadiene copolymer latex 10 parts (solid content), using a Choles disperser, stirring and mixing to prepare a coating liquid having a solid content concentration of 57%, and then a part thereof Opening 0.074 mm (20
A foreign matter was passed through a vibrating sieve (0 mesh sieve) to screen foreign matter to obtain a coating liquid A. Also, open the remaining coating liquid to 0.
A coarse foreign substance was screened through a vibrating screen of 25 mm (60 mesh screen) to obtain a coating liquid B.

[Preparation of coating liquids C and D] 50 parts of kaolin as a pigment and 50 parts of calcium carbonate having an average particle size of 2.5 μm,
Furthermore, a coating composition consisting of 6 parts (solid content) of 25% starch aqueous solution and 7 parts (solid content) of styrene-butadiene copolymer latex as an adhesive was stirred and mixed using a Choles disperser to obtain a solid content concentration of After preparing a coating liquid of 60%, a part of the coating liquid was passed through a vibrating sieve having an aperture of 0.074 mm (200 mesh sieve) to screen foreign substances to obtain a coating liquid C.
Also, open the remaining coating liquid by 0.25 mm (60 mesh screen)
Coarse foreign matter was passed through a vibrating screen of No. 1 to perform a scrolling treatment to obtain coating liquid D.

[Coater] As a coater, four single-sided blade coater heads are equipped, and first and third blade heads (from the front of the coater, for each coater head unit, the first, second, third and third coater heads, respectively). In front of the 4-blade head, the surface roughening device (surface roughening Rmax 8 by the roughening roll / sandblast method shown in FIG. 1 is used.
~ 60μm metal roll, opposing elastic roll / cotton,
Tetoron mixed fiber, pressed winding = Shore D hardness 80
Off machine coater equipped with

[Coating Method] The above-mentioned base paper for coating (64 g / m ² ) was placed on the unwinder of the above-mentioned off-machine coater (not shown), and the coater was run at a working speed of 1200 m / min. The coating was performed by the method. That is, the coating liquid C was dried at a weight of 15 g / m using the first blade head.
After being coated so that it has a thickness of ² , it is dried with hot air, and then the second blade head is used to apply a dry weight of 15 to the opposite surface (non-coated surface).
After coating so as to be g / m ² , it was dried with hot air to obtain a coated paper having one coated surface each on the front and back sides.

Next, a second roughening device (roughening roll = a metal roll having a surface roughness Rmax 47 μm by a sandblast method of the first cylinder, Rmax 38 μm, which is arranged in front of the third blade head, is used. Metallic rolls were respectively arranged as the second cylinder), and each surface of the coated layer was changed with the linear pressure.
The coating layer surface was roughened (Rmax) as shown in (Example 1 to Example 3). Further, successively, the coating liquid C is applied to each surface by a third and a fourth blade head so that the dry weight per surface is 18 g / m ^2, and dried to form a double-sided coating consisting of two layers on each side. The paper was once wound up.

The above-mentioned double-coated double-sided coated paper was attached again to the unwinder of the same coater, and blade coating was continuously carried out by the following method to obtain a double-sided coated paper consisting of four layers per one side in total. .. That is, the above-mentioned double-sided coated paper coated on one side twice is reattached to the unwinder of the off-machine coater, and is run in front of the first blade head while running at an operating speed of 1000 m / min. Roughening device (roughening roll = metal roll with surface roughness Rmax 29 μm by sandblast method, first cylinder, Rmax 22 μm
m metal rolls are arranged as the second cylinder, respectively)
Then, as shown in Table 1, the linear pressure is changed to roughen each surface of the coating layer of the second coating, and subsequently, the coating liquid A is applied to the front and back sides by the first blade head and the second blade head, respectively. The coated layer surface was coated with a blade so that the dry weight was 20 g / m ^2, and dried with hot air.

Further, a second roughening device (roughening roll = a metal roll having a surface roughness Rmax of 22 μm by a sandblast method) arranged in front of the third blade head is used as a first roll.
Cylinder, Rmax 18μm metal roll as the second cylinder)
Then, as shown in Table 1, the linear pressure was changed to roughen the surface of the coating layer of the third layer, and subsequently, the coating liquid A was applied to the surface using the third blade head and the fourth blade head, respectively. The back surface was coated with a blade so that the dry weight was 20 g / m ^2, and dried with hot air. Thus, a coated paper for double-sided printing having four layers on each side was obtained. The multilayer coated paper thus obtained was passed through an ordinary super calender to carry out smoothing treatment to obtain a coated paper for printing.

Example 4 In the same manner as in Example 1 except that the second layer was coated by using a multi-layer blade without using a roughening device, four layers were coated on each side. A coated paper for double-sided printing was obtained.

Example 5 In Example 1, in applying the second layer and the third layer, a roughening device was not used, but a roughening device was used before coating the fourth layer. A coated paper for double-sided printing having four layers per one surface was obtained in the same manner as in Example 1 except for the above.

Example 6 Using the same base paper and coater as in Example 1, a coating speed of 1,
While running at 000 m / min, the coating liquid A is applied to the dry weight using the first and second blade heads at a dry weight of 25 g / m ^{2 on} each side, dried to apply both sides, and then the second rough surface. Pass through a roughening device (using a metal roughening roll having surface roughnesses of 22 μm and 18 μm as the first cylinder and the second cylinder) to roughen the coating layer surface, and further to the third and fourth surfaces. The coating liquid A was applied to each surface of the first coating layer at 25 g / m ² using a blade head and dried to obtain a double-sided coated paper having two layers on each side. The coated paper thus obtained was passed through a super calender for smoothing treatment in the same manner as in Example 1 to obtain a coated paper for double-sided printing.

[0047] In Example 7 Example 1, the coated amount of the first layer 8 g / m ^2, the second layer 8 g / m ^2, the third layer 16g / m ^2, and the fourth layer 16
A coated paper for double-sided printing having 4 layers per one side was obtained in the same manner as in Example 1 except that the coating was performed so as to be g / m ² .

Example 8 In Example 1, each coating amount was changed to the first layer 16 g / m ² , the second layer 16 g / m ² , the third layer 8 g / m ² and the fourth layer 8.
A coated paper for double-sided printing having 4 layers per one side was obtained in the same manner as in Example 1 except that the coating was performed so as to be g / m ² .

Example 9 The procedure of Example 1 was repeated except that the coating liquid D was used for the first blade head and the second blade head and the coating liquid B was used for the third blade head and the fourth blade head. In the same manner as in Example 1, a coated paper for double-sided printing having 4 layers on each side was obtained.

Example 10 A coated paper for double-sided printing having 4 layers per side was obtained in the same manner as in Example 6 except that the coating liquid A was changed to the coating liquid B.

COMPARATIVE EXAMPLE 1 The procedure of Example 1 was repeated except that the roughening device was not used before coating the second layer, the third layer, and the fourth layer, and four layers were coated on each side. A double-sided coated paper consisting of 4 layers per side was obtained in the same manner as in Example 1.

Comparative Example 2 In Example 6, both sides were coated in the same manner as in Example 6 except that the second layer was coated without using the second roughening device and two layers were coated per side. A coated paper for printing was obtained.

Table 1 shows the surface roughness, streak evaluation, and quality results of the coated papers obtained in each stage of the thus obtained multilayer coated papers. The quality evaluation was performed according to the following method.

[Surface Roughness Rmax] The surface roughness was measured using a universal surface shape measuring instrument (measuring instrument: model / SE-3C; manufactured by Kosaka Laboratory Ltd.).

[Streak] Sample width 160 cm, length 1000
The generated streak was visually observed and evaluated over m. A: Almost no streak can be found. ◯: Length 1 cm
Below 10 streaks. Δ: Length 1 cm to 100
No more than 10 streaks up to cm. ×: 100 cm in length
More than 10 streaks.

[Print Smoothness and Ink Acceptability] Using a Roland offset printing machine, the print smoothness and the ink acceptability of the printed matter printed at a printing speed of 5000 sheets / hour were visually evaluated. A: Excellent. Good: Excellent. Δ: A little inferior, but practically no problem. X: extremely inferior (especially,
Conspicuous areas of defective ink transfer)

[0057]

[Table 1]

[0058]

As is apparent from the results of Table 1, the blade multilayer coated paper obtained by the method of the present invention has almost no streak and other streak troubles, and the printability of the obtained multilayer coated paper. (Printing effect) was also excellent.

[Brief description of drawings]

FIG. 1 is a schematic (line) diagram of a roughening device used in the method of the present invention.

[Description of Reference Signs] 1 ... Metal first roughening roll 2 ... Metal second roughening roll 3 ... Elastic roll facing the first roughening roll 4 ... Second Elastic roll facing the roughening roll 5 ... Guide roll 6 ... Guide roll 7 ... Guide roll 8 ... Paper strip (coated paper)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location D21H 19/80 23/34

Claims (4)

[Claims] 1. A method for producing a multi-layer coated paper comprising at least one or more overcoat layers provided on a support provided with an undercoat layer, wherein one or more of the overcoat layers are blade coated. And the surface of the coating layer before the blade coating is subjected to a surface roughening treatment with a hard surface roughening roll to give the surface roughness (Rma defined by JIS B0651).
The method for producing a multi-layer coated paper, wherein x) is 8 to 30 μm. 2. The method for producing a multilayer coated paper according to claim 1, wherein the undercoat coating layer is formed by blade coating. 3. Coating amount per one side in blade coating
At least 15 g / m ²The multi-layer according to claim 1 set forth above
Manufacturing method of coated paper. 4. The multilayer coated paper according to claim 1, wherein the coating liquid used for blade coating is a coating liquid which has been subjected to a foreign matter removal treatment with a screen having a mesh of mesh of 0.074 mm or less. Production method.