JPH04300391A - Production of coated paper - Google Patents

Abstract

PURPOSE:To provide a process for producing a multi-coated paper having high quality and excellent workability by using especially a specific undercoated base paper. CONSTITUTION:The undercoated base paper to be used in the present process has a specular reflection smoothness of 10-60% and a water-absorption of <=60% after 5see and 5-95% after 60sec and satisfies the formula S.m5/100<=15, wherein S is specular reflection smoothness (%) of the base paper and m5 is water- absorption of the undercoated base paper after 5sec.

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 multilayer coated paper, and more particularly to a method for producing coated paper of high quality and excellent operability by specifying base paper for undercoat.

0002

BACKGROUND OF THE INVENTION In recent years, with the trend toward visualization, colorization, and high-quality printed matter, there has been an increasing demand for improvements in the gloss, shine, and smoothness of the coated surface of coated paper for printing. For this reason, various proposals have been made regarding the manufacturing process of coated paper for printing. For example, for the coating method, a multilayer coating method using a blade coater is used, and for the finishing process, a finishing method using a high-temperature calender at 100°C or higher (JP-A-54-125712, Japanese Patent Publication No. 49-21252
(issues, etc.) have been proposed.

Furthermore, regarding the coating composition, use of fine pigments such as sachin white, ultrafine kaolin, ultrafine calcium carbonate, or organic pigments, and coating liquid concentration of 65
Many coating methods using coating liquids with a high concentration of % by weight or more have been proposed. However, many issues remain to be considered in order to obtain high-quality coated paper that is operationally superior.

[0004] Generally, coated paper obtained by multilayer coating is
It is known that it has superior quality compared to coated paper with a single layer coating, that is, high smoothness, gloss, shine, etc. In addition, if the undercoat base paper is smoothed by calendering, or by using fine pigments to make up the coating layer of the undercoat base paper, a higher quality coating can be achieved in the end. It is also generally known that paper can be obtained (WOCHENBLATT FUR PAPIER).
FABRIKATION 10, 1974, P353
~362).

However, especially when performing multi-layer coating using a blade, as the smoothness of the undercoat base paper improves, operational troubles such as streaks and scratches occur more frequently when coating the topcoat layer, which disturbs stable operation. This will lead to a decrease in product yield.

The reason why streaks and scratches occur will be explained below. Normally, the coating liquid is passed through a screen to remove residue and foreign matter from the coating liquid, but it is not completely removed, and foreign matter brought in by the base paper itself, pulp fibers, etc. If foreign matter stays under the blade, troubles such as streaks and scratches occur where the coating liquid is not coated only in that area.

[0007] If the base paper to be coated has relatively low smoothness, foreign matter may get into its unevenness and pass under the blade, or even if it stays there, it may not be removed immediately. The frequency of streaks and scratches is small. However, if the base paper to be coated has good smoothness, such as undercoated paper that has been coated with coating liquid in advance, foreign matter in the coating liquid will easily stay under the blade, and once it stays there will be a short period of time. Streak scratches occur frequently and last for a long time.

[0008]

OBJECTS OF THE INVENTION The present invention provides a method for producing coated paper that has high quality smoothness, gloss, and shine, and is also excellent in operability.

[0009]

[Means for Solving the Problems] The present invention provides a coating composition containing a pigment and an adhesive as main components, which is coated on a base paper, and a coating composition containing a pigment and an adhesive as a main component on a dried undercoating base paper. In the method for manufacturing multilayer coated paper, which coats and dries and then finishes with a calender, the specular reflection smoothness of the undercoat base paper is 10 to 6.
0%, and the water absorption of the base paper after 5 seconds is 60%.
The following is a method for producing a multilayer coated paper characterized in that the water absorption after 60 seconds is 5 to 95% and satisfies the following formula. S・m5 /100≦15 However, S: Specular reflection smoothness (%) of undercoat base paper m5
: Water absorption of base paper after 5 seconds (%)

0010

[Operation] The present inventors have conducted research on the occurrence of streaks and scratches when coating liquid on undercoat base paper. We found that the water absorption of the base paper measured by the method of The present inventors have discovered that high quality coated paper that fully exhibits the coating effect can be obtained, and have completed the present invention.

As mentioned above, the smoothness of the base paper is related to the occurrence of streaks and scratches, but the water absorption of the base paper also has a great influence. When coating base paper with a coating liquid, an excessive amount of the coating liquid is applied and then metalling is performed with a blade, etc., but from this application stage to the metaling stage, the amount of water absorbed by the base paper is large. As a result, the concentration of the coating liquid increases, and the fluidity deteriorates accordingly.If a large shear rate occurs under the blade, the fluidity of the coating liquid is impaired, and if there is a foreign object in the coating liquid, the fluidity will deteriorate. It cannot pass under the blade and tends to cause streaks and scratches.

[0012] The method for measuring water absorption in the present invention is to express the amount of water permeating into the undercoat layer over a certain period of time. ) is the value measured using Pure water kept at 20℃ using a microsyringe on the undercoat coated paper 5
The water absorption amount is measured over time by gently depositing μl onto the coated surface and setting this point at 0 seconds.The water droplets are photographed from the horizontal direction with a CCD camera, and the projected image is processed using an image processing measurement system (product Name: Dot Analyzer DA-3000
, manufactured by KS Systems Inc.), and subjected to binarized image processing to distinguish water droplets from the background, and the obtained data was analyzed using a host computer (PC-9801, manufactured by NEC Corporation). The projected area of water droplets on a substrate that does not absorb any water is taken as 100%, and the projected area for each time period is expressed as a percentage as a measure of the amount of water absorbed.

[0013] As a result of further research on this amount of water absorption, the amount of water absorbed over time measured using this measurement method is as follows:
It has been found that the amount of water absorbed 5 seconds after the water droplets are attached has a significant effect on the occurrence of streaks and scratches when coating the base paper with the coating liquid. In the present invention, it is necessary that the water absorption amount m5 (%) of the base paper after 5 seconds is 60% or less, preferably 50% or less.

[0014] Furthermore, the smoothness value S (%) of the undercoat base paper in the present invention under a specular reflection smoothness meter (manufactured by Toyo Seiki Seisakusho) at a pressure of 20 kg/cm2 is 10 to 60%, preferably 15 to 50%. is necessary. The smaller this value is, the rougher the surface of the coating layer of the base paper is, and the larger this value is, the smoother it is.

A major feature of the present invention is that in coated paper, which is finished by coating an undercoat base paper with a topcoat coating liquid,
In order to obtain coated paper of high quality and suppressing the occurrence of streaks and scratches, a correlation was found between the water absorption amount m5 (%) and the smoothness S (%) described above. That is, S・m5 /100≦15, preferably S・m5
When the relationship of /100≦10 is satisfied, the quality effect of multi-layer coating is exhibited, and coated paper that is also operationally friendly can be obtained.

Note that the value of smoothness S used in the above equation is 1
If it is less than 0%, no quality improvement effect will be observed even with multilayer coating, and if it exceeds 60%, streaks and scratches will not be suppressed no matter how small the water absorption m5 of the base paper is, which is preferable. do not have.

[0017] Furthermore, the water absorption m5 of the base paper for undercoat is 60%.
If it exceeds this value, the fluidity of the coating liquid under the blade tends to change significantly, streaks and scratches are likely to occur, and it becomes difficult to control the coating amount, which is undesirable.

Furthermore, in the present invention, it is necessary that the water absorption m60 after 60 seconds in the above-mentioned water absorption measurement method be 5 to 95%, preferably 5 to 90%. If the water absorption m60 after 60 seconds is less than 5%, the topcoat coating liquid will not be compatible with the base paper layer, and the surface strength of the final coated paper will likely decrease. Furthermore, if m60 exceeds 95%, the adhesive component in the coating liquid will rapidly penetrate into the base paper coating layer together with water during the coating process until it is solidified in the drying process. This is undesirable because the adhesive component in the top coat layer decreases, resulting in insufficient surface strength during printing on coated paper and a decrease in ink gloss due to extreme ink absorption.

The smoothness and water absorption amount of the base paper of the present invention can be adjusted by adjusting the type and particle size of the pigment constituting the coated layer of the base paper, the type and blending ratio of the adhesive, the amount of coating, Drying conditions for the coating layer, calendering after drying the undercoat layer, pulp composition of the base paper on which the undercoat layer is applied, beating conditions, type and amount of filler, internal sizing agent, surface sizing agent, surface There are various methods such as processing agents, smoother pressure, press pressure, drying conditions, etc., and the optimum conditions are appropriately selected and determined depending on each paper machine and coating machine.

Pigments constituting the coating layer of the base paper of the present invention include, for example, clay, kaolin, aluminum hydroxide, calcium carbonate, titanium dioxide, barium sulfate,
Zinc oxide, calcium sulfate, talc, sachin white,
One or more kinds of ordinary pigments for coated paper such as organic pigments are appropriately selected and used. It is not limited by its production method, form, or particle size; for example, heavy calcium carbonate can be used by dry classification, dry pulverization, wet pulverization, etc., and light calcium carbonate can be used as a plate. Light calcium carbonate can be used in shapes such as shaped, spindle-shaped, columnar, cubic, and needle-shaped.

[0021] Conventionally, when a large amount of kaolin was blended to improve the smoothness of the base paper, streaks and scratches frequently occurred, so the number of kaolin blended was limited, but according to the method of the present invention, the amount of kaolin blended was limited. It is possible to incorporate a high proportion of kaolin, and when it is contained in 40 to 100 parts by weight, preferably 60 to 100 parts by weight, in 100 parts by weight of the pigment in the undercoat layer coating liquid, coated paper of extremely high quality can be obtained. This is a possible and preferred method.

Examples of adhesives include proteins such as casein, soybean protein, and synthetic proteins; conjugated diene polymer latex such as styrene-butadiene copolymer; polymers or copolymers of acrylic esters and/or methacrylic esters. Acrylic polymer latex such as polymers; vinyl polymer latex such as ethylene/vinyl acetate copolymer; or alkali-soluble or Alkali-insoluble polymer latex; synthetic resin adhesives such as polyvinyl alcohol, olefin/maleic anhydride resin, and melamine resin; starches such as positive starch and oxidized starch;
One or more types of common adhesives for coated paper, such as cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose, are appropriately selected and used.

[0023] Generally, the amount of the adhesive is adjusted within the range of 5 to 50 parts by weight, more preferably 10 to 30 parts by weight, based on 100 parts by weight of the pigment.

[0024] In addition, various auxiliary agents such as antifoaming agents, colorants, mold release agents, flow modifiers, etc. are appropriately blended into the coating composition as necessary, but they do not promote solidification of the coating layer. As an auxiliary agent, for example, amine, amide, polyacrylamine, etc., or a salt of a polyvalent metal such as zinc, aluminum, magnesium, calcium, barium, etc., is added in an amount of 0.1 to 10% per 100 parts by weight of the pigment.
It may be added in an amount of about parts by weight.

[0025] The coating composition obtained under the above conditions is as follows:
Coating equipment used in general coated paper manufacturing, such as blade coaters, air knife coaters, roll coaters, reverse roll coaters, bar coaters, curtain coaters, die slot coaters, gravure coaters, champlex coaters, and size press coaters. The base paper is coated in one layer or in two or more layers using a provided on-machine or off-machine coater.

The solid content concentration of the coating composition at this time is generally about 40 to 75% by weight, but in consideration of operability and the like, it is preferably in the range of 45 to 70% by weight.

[0027] As the base paper, paper-based or board-based base paper with a weight of about 30 to 400 g/m2, which is used for general coated printing paper, is used, but there are no particular limitations on the paper making method. , acidic or alkaline paper may be used, and of course, medium base paper containing high-yield pulp can also be used. Additionally, base paper pre-coated with a size press, bill blade, etc. can also be used.

The amount of coating on the base paper is desirably adjusted within the range of about 3 to 25 g/m 2 , taking into consideration the smoothness of the resulting undercoat base paper and the occurrence of streaks during coating of the top coat.

[0029] Various methods are used to dry the wet coating layer, such as steam heating, hot air heating, gas heater heating, electric heater heating, infrared heater heating, high frequency heating, laser heating, and electron beam heating. Although not particularly limited, the degree of migration of the adhesive in the coated layer varies greatly depending on the drying conditions, and the water absorption in the present invention varies even if the type and blending ratio of the composition are the same. It is necessary to adjust the drying conditions accordingly.

[0030] The base paper can be calendered on-machine or off-machine.
For example, machine calenders, super calenders, soft compact calenders, gross calenders, etc. can be used.

The pigments constituting the coating solution for the topcoat layer applied to the base paper thus obtained are not particularly limited, as are the pigments constituting the undercoat coating layer, and examples include satin white, organic pigments, etc. , clay, kaolin, aluminum hydroxide, calcium carbonate, titanium dioxide, barium sulfate, zinc oxide, calcium sulfate, talc, etc., one or more pigments for coating paper may be appropriately selected and used. When a coating liquid containing satin white or an organic pigment is coated on the undercoat base paper of the present invention, particularly excellent smoothness, gloss, and shine are exhibited, and this is a preferred method for high-grade printing coated paper.

Examples of adhesives include proteins such as casein, soy protein, and synthetic proteins; conjugated diene polymer latex such as styrene-butadiene copolymer; polymers or copolymers of acrylic esters and/or methacrylic esters. Acrylic polymer latex such as polymers; vinyl polymer latex such as ethylene/vinyl acetate copolymer; or alkali-soluble or Alkali-insoluble polymer latex; synthetic resin adhesives such as polyvinyl alcohol, olefin/maleic anhydride resin, and melamine resin; starches such as positive starch and oxidized starch;
One or more types of common adhesives for coated paper, such as cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose, are appropriately selected and used.

[0033] Generally, the amount of the adhesive is adjusted within the range of 5 to 50 parts by weight, more preferably 10 to 30 parts by weight, based on 100 parts by weight of the pigment.

[0034] In addition, various auxiliary agents such as antifoaming agents, colorants, mold release agents, flow modifiers, etc. are appropriately blended into the coating composition as necessary, but they do not promote solidification of the coating layer. As an auxiliary agent, for example, amine, amide, polyacrylamine, etc., or a salt of a polyvalent metal such as zinc, aluminum, magnesium, calcium, barium, etc., is added in an amount of 0.1 to 10% per 100 parts by weight of the pigment.
It may be added in an amount of about parts by weight.

The coating composition for the top coat layer obtained under the above conditions is prepared by applying an excessive amount of the coating liquid to the base paper using a blade coater, rod blade coater, Champlex coater, etc. Coating is done by an on-machine or off-machine coater using a coating device that measures and smoothes the surface while in contact with the surface. When coating is done with an off-machine coater, the undercoat layer is coated continuously after drying. Alternatively, the undercoat layer may be dried and then rolled up, and then the top coat layer may be applied.

[0036] The solid content concentration of the coating composition is generally about 40 to 75% by weight, but in consideration of operability and the like, it is preferably in the range of 45 to 70% by weight. In addition, the amount of topcoat applied to the base paper is generally 3 per side by dry weight.
-50 g/m2, but in consideration of the blank quality, printability, etc. of the resulting coated paper, it is desirable to adjust it within the range of about 8-25 g/m2.

[0037] There are various methods for drying the top coat wet coating layer, such as steam heating, hot air heating, gas heater heating, electric heater heating, infrared heater heating, high frequency heating, laser heating, and electron beam heating. It is adopted and is not particularly limited.

Examples of calender finishing methods include super calender, gross calender, soft calender, and soft compact calender (Paper and Pulp Technology Times/August 1985 issue, pp. 31-36; same/October 1999) Monthly issue, pp. 42-47; PPI/1987 1
January issue, pp. 45-47; WFP/1985, 22, 8
73-877) etc. can be applied on-machine or off-machine.

[0039] The surface temperature of the metal roll is about 20-35
Used at 0°C. If the temperature is lower than 20℃, the smoothing effect will be insufficient, and if the temperature exceeds 350℃, the micro pores in the coated layer will be crushed, resulting in poor ink absorption when printing on coated paper, resulting in offset. This is not preferable because stable printing operations become difficult.

[0040] The elastic rolls to be used include, for example, rolls made of natural fibers such as normal cotton, white cotton, fill matte cotton, woolen paper, and paper, rolls containing aramid fibers in these natural fibers, and rolls made of epoxy-based Resin, polyimide resin, polyamide resin, polyurethane resin, isocyanate resin, silicone resin, polyarylate resin, vinylidene fluoride resin, unsaturated polyester resin, polyacetal resin, phenolic resin, polyphenylene sulfide resin An elastic roll made of a single layer or multiple layers of synthetic resin such as resin can be used.

As the heating method for the metal roll, conventionally used methods such as steam, hot water, electricity, etc. can be used as appropriate.
In high-temperature conditions of 0°C or higher, for example, an induction heating type jacket roller (electrothermal/No. 41, pp. 2-8, 1)
988, Paper and Pulp Technology Times/December 1962 issue, 4
1 to 47) is preferably used because temperature uniformity is maintained.

[0042] Pressure conditions for the calender roll are preferably in the range of about 10 to 500 kg/cm in linear pressure, and the number of pressure nips per calender is usually within the range of a soft calender or a gross calender. The number of nips per drum or metal roll is 1 to 6, and if necessary, both sides may be finished using two calenders. Also,
In the case of a super calender, about 3 to 13 nips are applied.

[0043]

[Examples] The present invention will be explained in more detail with reference to Examples below, but it is of course not limited to the scope thereof. Note that "parts" and "%" in the examples indicate "parts by weight" and "% by weight", respectively, unless otherwise specified.

Example 1 <Preparation of undercoat layer coating liquid> Pigment 100 for undercoat layer coating liquid
%, heavy calcium carbonate (trade name: Softon 1
800/manufactured by Bihoku Funkasha) 80 parts, kaolin (product name: H
0.3 parts of sodium polyacrylate as a dispersant was added to 20 parts of pigment (manufactured by T/EMC) and dispersed using a Coles disperser to prepare a pigment slurry with a solid content concentration of 68%. Add 5% oxidized starch (solid content) to this pigment slurry.
parts, styrene-butadiene copolymer latex (trade name: JSR0696/manufactured by Japan Synthetic Rubber Co., Ltd.) (solid content) 12
A coating liquid having a solid content concentration of 60% was obtained by adding 50% of the total solid content and further adding water.

<Preparation of topcoat layer coating liquid> Kaolin (trade name: UW-9) was added to 100 parts of pigment in the topcoat layer coating liquid.
0/manufactured by EMC Co., Ltd.) and 20 parts of light calcium carbonate (trade name: Tama Pearl TP-123/manufactured by Okutama Kogyo Co., Ltd.), and 0.0 parts of sodium polyacrylate as a dispersant.
2 parts were added and dispersed using a Coles disperser to prepare a pigment slurry with a solid content concentration of 68%. To this pigment slurry, 3 parts of oxidized starch (solid content) and 10 parts of styrene-butadiene copolymer latex (trade name: JSR0696/manufactured by Japan Synthetic Rubber Co., Ltd.) (solid content) were added, and water was further added to increase the solid content concentration. A coating liquid with a coating liquid of 60% was obtained.

<Base paper for undercoat> Apply this undercoat layer coating solution to a base paper of 70 g/m2 in dry weight at 10 g/side per side.
Both sides were coated with a blade coater to a coating thickness of m2 and dried to obtain an undercoat base paper. At this time, the specular reflection smoothness of the base paper for undercoat was 12%, and the water absorption after 5 seconds was 25%.
The water absorption after 0 seconds was 60%.

<Top coated paper> The above-mentioned top coat layer coating liquid was applied to this base paper at a dry weight of 15 g/m2 per side.
2. Coat both sides with a blade coater so that
The paper was dried to a moisture content of 6.0%. Then, 60℃, 1 1
Super calendering was performed under the conditions of nip and linear pressure of 200 kg/cm. The operating conditions during the application of the topcoat layer and the quality of the obtained coated paper were measured, and the results are shown in Table 1.

The frequency of occurrence of streaks and scratches was determined by visual observation during coating and measurement using a streak detector. That is, the frequency of occurrence of streaks and scratches was determined from the ratio of the streak occurrence length to the total coating length of the top coat coating solution. The frequency of streak occurrence in normal single-layer coating without undercoating was in the range of 0.01 to 0.2%.

The white paper smoothness of the top-coated paper was measured using a Smoostar smoothness meter (manufactured by Toei Denshi Kogyo Co., Ltd.). The white paper glossiness was measured by a method according to JIS-P-8142, and the white paper gloss was visually determined. In addition, printing smoothness, ink gloss, and surface strength were determined using an RI printing machine (manufactured by Mei Seisakusho).
Printing was carried out using the following and visual judgment was made.

[0050] Evaluation criteria ◎...Very good○...Good △…Slightly inferior ×…Defect

Example 2 Light calcium carbonate (trade name: Tama Pearl TPK/manufactured by Okutama Kogyo Co., Ltd.) was added to 100 parts of pigment in the undercoat layer coating liquid.
50 parts, heavy calcium carbonate (trade name: Carbital-9
0/manufactured by Fuji Kaolin Co., Ltd.), the specular reflection smoothness of the undercoat base paper was 29%, and the water absorption after 5 seconds was 30%.
A coated paper was obtained in the same manner as in Example 1, except that the water absorption after 0 seconds was 73%. Table 1 shows the operating conditions during the application of the topcoat layer and the quality of the coated paper obtained.

Example 3 To 100 parts of the pigment of the undercoat layer coating liquid, 45 parts of kaolin (trade name: UW-90/manufactured by EMC Co., Ltd.) and heavy calcium carbonate (trade name: Carbital-90/manufactured by Fuji Kaolin Co., Ltd.) were added. 55 parts (manufactured by), and the specular reflection smoothness of the base paper was reduced to 32%.
, water absorption after 5 seconds is 13%, water absorption after 60 seconds is 21%.
A coated paper was obtained in the same manner as in Example 1, except that the following was used. Table 1 shows the operating conditions during the application of the topcoat layer and the quality of the coated paper obtained.

Example 4 To 100 parts by weight of the pigment in the undercoat layer coating liquid, 70 parts of kaolin (trade name: UW-90/manufactured by EMC), heavy calcium carbonate (trade name: Carbital-90/Fuji Kaolin) were added. using 30 parts of oxidized starch (solid content), the regular reflection smoothness of the undercoat base paper was 41%, the water absorption after 5 seconds was 6%, and the water absorption after 60 seconds was 12%. A coated paper was obtained in the same manner as in Example 1, except that the following values were used. Table 1 shows the operating conditions during the application of the topcoat layer and the quality of the coated paper obtained.

Example 5 The undercoat base paper was calendered using a soft compact calender, and the specular reflection smoothness of the undercoat base paper was 55.
%, water absorption after 5 seconds is 15%, water absorption after 60 seconds is 47
A coated paper was obtained in the same manner as in Example 1 except that the amount was expressed as %. Table 1 shows the operating conditions during the application of the topcoat layer and the quality of the coated paper obtained.

Example 6 In Example 3, 10 parts of Sachin White (trade name: SW-BL/manufactured by Shiroishi Calcium Co., Ltd.) and an organic pigment (trade name: L- 8801
/ manufactured by Asahi Kasei Co., Ltd.) 10 parts, kaolin (product name: UW-90)
/manufactured by EMC) 70 parts, heavy calcium carbonate (trade name;
0.2 parts of sodium polyacrylate was added as a dispersant to a pigment consisting of 10 parts of Carvital-90 (manufactured by Fuji Kaolin Co., Ltd.), and the mixture was dispersed using a Coles disperser to achieve a solid content concentration of 60.
% pigment slurry was prepared. This pigment slurry contains 2 parts of oxidized starch (solid content), styrene-butadiene copolymer (
Product name: 0696/manufactured by Japan Synthetic Rubber Co., Ltd.) (solid content) 12
A coated paper was obtained in the same manner as in Example 3, except that a coating solution having a solid content of 55% was obtained by adding 55% solids. Table 1 shows the operating conditions during the application of the topcoat layer and the quality of the coated paper.

Example 7 In the coating solution for undercoat layer, 100 parts of light calcium carbonate (trade name: Tama Pearl TP-123/manufactured by Okutama Kogyo Co., Ltd.) was used for 100 parts of pigment, and 3 parts of oxidized starch (solid content) was used.
5 parts of styrene-butadiene copolymer latex (trade name: 0696/manufactured by Japan Synthetic Rubber Co., Ltd.) to make the solid content concentration of the undercoat layer coating liquid 52%, and the specular reflection smoothness of the undercoat base paper was 35%. Coated paper was obtained in the same manner as in Example 6, except that the water absorption after 5 seconds was 33% and the water absorption after 60 seconds was 92%. Table 1 shows the operating conditions during application of the top coat layer and the quality of the coated paper obtained.

Comparative Example 1 In the undercoat layer coating solution, a pigment consisting of 100 parts of heavy calcium carbonate (trade name: Softon 1500/manufactured by Bihoku Funka Co., Ltd.) was used to increase the specular reflection smoothness of the undercoat base paper to 6%, Coated paper was obtained in the same manner as in Example 1, except that the water absorption after 5 seconds was 28% and the water absorption after 60 seconds was 39%. Table 1 shows the operating conditions during the application of the topcoat layer and the quality of the coated paper obtained.

Comparative Example 2 The dry weight of the undercoat layer coating liquid was 20 g/m2 per side.
Coat both sides so that A coated paper was obtained in the same manner as in Example 2 except that the strength was 52%, but streaks and scratches occurred frequently when the topcoat layer was applied. Table 1 shows the operating conditions during the application of the topcoat layer and the quality of the coated paper obtained.

Comparative Example 3 In the undercoat layer coating liquid, 2 parts of oxidized starch (solid content),
Coat 4 parts of styrene-butadiene copolymer (trade name: 0696/manufactured by Japan Synthetic Rubber Co., Ltd.) on both sides of base paper with a dry weight of 4 g/m2 per side using a blade coater. After calendering the undercoat base paper with a soft calender, the specular reflection smoothness of the undercoat base paper was 45%, the water absorption after 5 seconds was 38%, 6
A coated paper was obtained in the same manner as in Example 1 except that the water absorption after 0 seconds was 75%, but streaks and scratches occurred frequently when the top coat layer was applied. Table 1 shows the operating conditions during application of the top coat layer and the quality of the coated paper obtained.

Comparative Example 4 In the undercoat coating liquid, 70 parts of calcined kaolin (trade name: Ansilex/manufactured by EMC) and amorphous silica (trade name: Mizukasil/manufactured by Mizusawa Chemical Co., Ltd.) were used for 100 parts of pigment.
Using 30 parts, 2 parts of oxidized starch (solid content) and 5 parts of styrene-butadiene copolymer (trade name: 0696/manufactured by Japan Synthetic Rubber Co., Ltd.) were added, and the solid content concentration of the coating liquid was set at 40%.
5g dry weight per side on base paper of 60g/m2
/m2, both sides were coated with a gate roll coater, and dried to obtain a paper coated with an undercoat. At this time, the regular reflection smoothness of the paper coated with the undercoat layer was 16%, and the water absorption after 5 seconds was 2
A coated paper was obtained in the same manner as in Example 1, except that the water absorption rate after 60 seconds was 98%. Table 1 shows the operating conditions during the application of the topcoat layer and the quality of the coated paper obtained.

Comparative Example 5 Light calcium carbonate (
Using 100 parts of Tama Pearl TP-121 (trade name; manufactured by Okutama Kogyo Co., Ltd.), 2 parts of oxidized starch, and 5 parts of styrene-butadiene copolymer (trade name; 0696 / manufactured by Nihon Gosei Rubber Co., Ltd.) were used to form an undercoat base paper. The topcoat layer was applied in the same manner as in Example 1, except that the specular reflection smoothness was 16%, the water absorption amount after 5 seconds was 66%, and the water absorption amount after 30 seconds was 82%. However, it was not possible to control the amount of coating to a predetermined level, and it was not possible to obtain a uniform coated surface.

Comparative Example 6 15 parts of oxidized starch (solid content) and 20 parts of styrene-butadiene copolymer (trade name: 0696/manufactured by Nihon Gosei Rubber Co., Ltd.) were added to the undercoat layer coating liquid. Example 4 except that the solid content concentration was 52%, the specular reflection smoothness of the obtained undercoat base paper was 30%, the water absorption after 5 seconds was 1%, and the water absorption after 60 seconds was 3%. A coated paper was obtained in the same manner. Table 1 shows the operating conditions during the application of the topcoat layer and the quality of the coated paper obtained.

Comparative Example 7 No undercoat was applied, and the coating liquid for the topcoat layer in Example 1 was applied to a base paper of 70 g/m2 in dry weight per side.
A coated paper was obtained in the same manner as in Example 1, except that both sides were coated using a blade coater to give a coating weight of 5 g/m2. Table 1 shows the operating conditions during coating and the quality of the coated paper obtained.

[0064]

[Table 1]

[0065]

[Effects of the Invention] The multilayer coated paper obtained by the method of the present invention was excellent in quality, and the frequency of occurrence of streaks and scratches was low.

Claims (6)

[Claims] Claim 1: A coating composition containing pigments and an adhesive as main components is coated on a base paper. After drying, a coating composition containing a pigment and an adhesive as main components is coated on an undercoated base paper and dried, followed by a calendering process. In the method for producing a multilayer coated paper finished with, the specular reflection smoothness of the undercoat base paper is 10 to 60%, and the water absorption after 5 seconds of the undercoat base paper is 60% or less, and the water absorption after 60 seconds is 5 to 95% and satisfies the following formula. S・m5 /100≦15 However, S: Specular reflection smoothness (%) of undercoat base paper m5
: Water absorption of base paper after 5 seconds (%) 2. The method for producing multilayer coated paper according to claim 1, wherein the base paper satisfies the following formula. S・m5/100≦10 Claim 3: Specular reflection smoothness of base paper for undercoat is 15% to 50.
%. The method for producing a multilayer coated paper according to claim 1. 4. The method for producing a multilayer coated paper according to claim 1, wherein the water absorption of the base paper after 5 seconds is 50% or less, and the water absorption after 60 seconds is 5 to 90%. . 5. The method for producing a multilayer coated paper according to claim 1 or 4, wherein 40 to 100 parts by weight of kaolin is contained in 100 parts by weight of the pigment constituting the undercoat coating liquid. 6. The method for producing multilayer coated paper according to claim 1 or claim 4, wherein 60 to 100 parts by weight of kaolin is contained in 100 parts by weight of the pigment constituting the undercoat coating liquid.