JPH0233390A - Production of cast coated paper - Google Patents

Abstract

PURPOSE:To efficiently obtain cast coated paper having high live gloss in spite of low gloss of white paper of coated layer of the back by passing cast coated paper through a heating metallic roll and an elastic roll having specific surface roughness. CONSTITUTION:Pigment coating agent is applied to the surface and the back of base paper, respectively, the surface side of the paper is brought into contact with a heating drum having specular surface to give cast coated paper under pressure. Further the cast finished face at the surface side is brought into contact with a heating metallic roll and the back with an elastic roll satisfying the formula [Rmax is surface roughness (mum) prescribed by JIS BO651; D is Shore D hardness ( deg.); T is surface temperature ( deg.C) of metallic roll in operation] and smoothed so as to give <=40% measured value of gloss of white paper of the coated layer face of the back in the method described in JIS P8142 and <15cmHg smoothness by a smooth star evenness meter. Consequently, cast coated paper having matte back coated layer of so-called matte-gloss type is obtained.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a method for producing cast coated paper, and in particular to a so-called Mazda gloss-type glossy paper that has a low white paper gloss in the back coating layer but high ink gloss. The present invention relates to a method for efficiently producing cast coated paper having an eraser back coating layer.

``Conventional technology'' Cast coated paper has particularly excellent gloss and smoothness among coated papers for printing, and is used for various magazines, catalogs, pamphlets,
It is widely used as the cover of annual reports, etc.

Conventionally, methods for producing cast coated paper include wet casting (USP 1719166), rewetting casting (USP 2759847), and gelling casting (USP 2759847).
USP 2919205) are known, but in all of these, the coating layer, which is mainly composed of mineral pigments and adhesives, is pressed onto a heated finished surface while it is in a plastic state due to water content and then dried. The method is basically the same in that it can be used. Most of the cast-coated papers produced according to these manufacturing methods are so-called single-sided cast-coated papers, which have a highly glossy cast finish on one side and a high-quality paper-like surface on the other side.

On the other hand, matte coated paper gives an elegant and calm image compared to high-gloss coated paper, so in recent years it has become an important printing paper for everything from single-color prints such as text paper to various multi-color prints. It is commonly used as one of the grades.

For example, when cast-coated paper is used as the cover of a magazine, catalog, annual report, etc., when the cover is opened, the back side of the cast-coated paper and the text paper made of matte-coated paper may be different. It is necessary to show the same blank paper quality and printing quality without any blemishes, and for this purpose, it is strongly desired that the back side of the cast coated paper be a matte coated paper that corresponds to the text paper.

The method for obtaining cast-coated paper as described above does not change the basic method of cast finishing as described above, but the method is to coat the back side with a pigment that has good ink receptivity, retention, and plate reproducibility. A coating layer is provided, and if necessary, this is calendered to smooth the base paper, and the pigment coating layer provided on the surface of this base paper is pressure-bonded to the heated finished surface while it is in a plastic state due to water content. A method of drying and finishing has been proposed. However, although this method improves the printing quality on the back side, it is considerably inferior in terms of smoothness and ink gloss because it is not super calendered compared to general coated printing paper.

It has also been proposed to perform a super calender treatment after finishing the cast, but this results in the occurrence of bumps on the surface of the cast coated paper, making the appearance of the cast surface thicker (damaging), and causing the gloss of the white paper on the back side to become matte and coated. The problem is that it is too expensive for paper.

In addition, as another method for making the back coating layer highly smooth and exhibiting high ink gloss, there is, for example, a method of laminating single-sided cast coated paper and matte coated paper using a thermoplastic polymer bonding agent. Although this method has been proposed, it has not been implemented in practice due to problems such as unevenness on the cast surface depending on the type of bonding agent and difficulty in controlling curl after bonding.

``Problems to be Solved by the Invention'' In view of the current situation, the present inventors have conducted intensive research on a method for improving the above-mentioned drawbacks that accompany heating calendering after finishing casting, and have found that It has been found that the surface roughness and hardness of the elastic rolls constituting the render are extremely important factors for the unevenness of the cast coated paper surface and the smoothness of the back coating layer.

That is, in order to smooth the back surface of the cast coated paper, heating calendering is performed so that the front surface of the cast coated paper is in contact with a heated metal roll and the back surface is in contact with an elastic roll. In this case, the cast surface has an extremely smooth and glossy surface that has been transferred from the mirror surface of the heating drum, but if the surface of the elastic roll of the heating calender becomes deformed or roughened due to temperature and pressure, the effects of this will be affected. It became clear that the high gloss and smoothness of the cast coating layer and, as a result, the cast surface were impaired.

Therefore, by regulating the surface roughness of the elastic roll according to the hardness of the roll and the surface temperature of the metal roll, high smoothness can be imparted to the back surface of the resulting cast-coated paper. It has been found that cast coated paper can be produced with high efficiency without any scratches or poor gloss on the surface, and the present invention has finally been completed.

"Means for Solving the Problems" The present invention forms a pigment coating layer containing pigments and adhesives as main components on the back side of base paper, and then coats the surface of the base paper with pigments and adhesives as main components. Form a pigment coating layer and coat the surface! While the layer is in a plastic state, it is pressed onto the surface of a heated drum with a mirror surface and dried to obtain a cast coated paper, and then the finished cast surface is placed on the heated metal roll surface, and the back pigment coated layer surface is placed on the elastic roll surface. In the method for manufacturing cast coated paper, which is applied to a heated calender to give a high gloss finish in contact with the elastic roll, the surface roughness Rmax (JIS B0
651) satisfies the following formula, and the back coating layer is smoothed so that the measured value of white paper gloss according to JIS P8142 method is 40% or less and the smoothness by Smoostar smoothness meter is 15 cmHg or less. This is a method for producing cast coated paper whose back surface is a matte coated layer surface, which is characterized by subjecting it to a chemical treatment.

(Note) Rmax≦-0,1D -0,01T +35 [Note] Rmax iSurface roughness of elastic roll (μm) D; Shore D hardness of elastic roll) T; Surface temperature of metal roll during operation (°C ) "Function" In the method of the present invention, the pigment coating composition for forming the back surface contains a pigment and an adhesive as main components, similar to conventional coating compositions for printing.

Examples of pigments include one or two of the usual pigments for coated paper, such as clay, kaolin, aluminum hydroxide, calcium carbonate, titanium dioxide, barium sulfate, zinc oxide, satin white, calcium sulfate, talc, plastic pigments, etc. The above are selected and used as appropriate.

In particular, the purpose of the present invention is to obtain a cast-coated paper that has a high smoothness and high ink gloss on the back side but low white paper gloss, so-called matte coated paper on the back side. 40% or less when measured in accordance with JIS P8142, and the smoothness measured by a Smoothstar smoothness meter is 15 cm.
+ Hg or less, and for this purpose, the pigment used in the back coating layer preferably contains 50% by weight or more of calcium carbonate in the total pigment, and more preferably cast. It is desirable to use calcium carbonate having an average particle diameter of 0.3 to 2 μm, which can easily provide a smoothing effect by heating and calendering after finishing.

Examples of adhesives include casein, soy protein, conjugated diene polymer latex such as styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer, and polymers or copolymers of acrylic esters and/or methacrylic esters. Acrylic polymer latex such as ethylene-vinyl acetate copolymer, vinyl polymer latex such as ethylene-vinyl acetate copolymer, or alkaline-soluble or alkaline polymers obtained by functionally modifying these various polymers with a monomer containing a functional group such as a carboxyl group. Insoluble polymer latex, polyvinyl alcohol, acetoacetylated polyvinyl alcohol,
Synthetic resin adhesives such as carboxy-modified polyvinyl alcohol, sulfonic acid-modified polyvinyl alcohol, silicon-containing modified polyvinyl alcohol, olefin-maleic anhydride resin, melamine resin, starches such as positive starch and oxidized starch, carboxymethyl cellulose, hydroxyethyl cellulose, etc. General adhesives for coated paper such as cellulose derivatives can be used alone or in combination. These adhesives are used in an amount of 5 to 50 parts by weight, more preferably 10 to 30 parts by weight, per 100 parts by weight of the pigment. or,
Examples of auxiliary agents include antifoaming agents, colorants, mold release agents, flow modifiers, etc., as needed.As auxiliary agents that promote solidification of the coated layer, for example, amines, amides, polyamides, etc. Acrylamine, etc., zinc, aluminum, magnesium,
A polyvalent metal salt such as calcium or barium may be added in an amount of 0.1 to 10 parts by weight per 100 parts by weight of the pigment.

The coating composition thus prepared is used in the production of coated papers, such as blade coaters, air knife coaters, roll coaters, reverse roll coaters, brush coaters, curtain coaters, champlex coaters, and bar coaters. The base paper is coated in one layer or in multiple layers using an on-machine or off-machine coater equipped with a coating device such as a gravure coater or a size press coater. The solid content concentration of the coating composition at that time is generally 40 to 75% by weight, but considering operability, the solid content concentration is 40 to 75% by weight.
A range of 5 to 70% by weight is preferred. Note that as the base paper, paper-based or board-based base paper with a weight of 30 to 400 g/rrr, which is used for general printing coated paper and cast coated paper, is used, but there are no particular limitations on the method of making the base paper. However, either acidic or alkaline paper may be used, and of course, medium base paper containing high-yield pulp may also be used. Additionally, base paper pre-coated with a size press, bill blade, etc. can also be used.

The coating amount of the coating composition on the base paper is generally about 10 to 50 g/rd per side in terms of dry weight, but considering the blank paper quality, printability, etc. of the resulting Cath 11-covered paper, it is about 15 g/rd.
It is desirable to adjust it within a range of about 30 g/rd. In addition, as a method for drying a wet coating layer, there are various conventionally known methods 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. Can be adopted as appropriate.

The opposite side (front side) of the base paper coated on the back side as described above contains various inorganic pigments and plastic pigments such as clay, kaolin, calcium carbonate, aluminum hydroxide, and titanium oxide, as well as casein, starch, synthetic resin latex, etc. A coating composition mainly composed of natural and synthetic adhesives is applied, and while the coating layer contains water and is in a plastic state, it is pressed against a heated finished surface and dried, so that the moisture in the coating layer is removed. After substantial evaporation, the finished surface is released from the mold to yield a cast coated paper. The casting finishing method itself is not particularly limited, and may include the conventional wet casting method, gel casting method, rewetting casting method, etc. In short, it is a method in which the cast material is pressure-bonded to the heated finished surface while it is in a plastic state containing water.・
A so-called cast finishing method that involves drying can be applied to the present invention.

In the manufacturing method of the present invention, the surface of the thus obtained cast sheet is passed through a heated calender. Examples of the calender include a super calender, a gloss calender ( Japanese Patent Application Publication No. 1973-13
No. 2305, Publication Patent Publication No. 63-500188), Soft Compact Calender (Gi Pulp Technology Times,
August 1962 issue, pp. 31-36, PPI, 1987
November issue, pp. 45-47; WFP, 1985.
22, pp. 873-877) are used in on-machine and off-machine formats. Note that the surface of the metal roll may be mirror-finished by hard chrome plating or the like.

In the method of the present invention, an elastic roll having a surface roughness that satisfies the following formula is selectively used as the elastic roll of the various calenders as described above.

Rn+ax≦-0, LD -0, OIT +35 [Notes] Rh+ax; Surface roughness of elastic roll (μg+) D;
(Shore D hardness of the elastic roll) T: Surface temperature of the metal roll during operation (°C) As is clear from the above relational expression, the elastic roll used in the method of the present invention has a hard Shore D hardness of the elastic roll. Obviously, it is necessary to reduce the surface roughness Rmax.

Conventionally, no particular attention has been paid to the surface roughness of the elastic roll constituting the calender, and as in the present invention, the surface roughness of the elastic roll is determined based on the relationship between the Shore D hardness of the elastic roll and the surface temperature of the metal roll. There is no known technical idea for improving the fraying of the obtained cast coated paper by specifying the thickness.

According to experiments conducted by the present inventors, surface roughness Rm
Even with an elastic roll with ax of 5 μm or less, the speed is 200 m/
At a high speed of over min, the surface temperature of the metal roll was increased to 60°C.
When cast coated paper is processed at temperatures above ℃ and linear pressure of 100 kg/cm or more, the surface roughness rapidly decreases due to unevenness caused by uneven formation and coating of the coated paper. It became clear that

In particular, thick paper has uneven texture and poor smoothness, so the surface roughness decreases significantly, and this tendency becomes even more pronounced when using elastic rolls with low hardness or elastic rolls made of materials with low resilience. It was also revealed that this was significant.

Therefore, in the method of the present invention, it is necessary to specify the surface roughness of the elastic roll in the state in which it is actually used, and if the surface roughness of the elastic roll deviates from the specifications of the present invention during operation, the It is necessary to stop the render and replace it with a role that satisfies the conditions.

As for the material of the elastic roll, it is also possible to use the materials conventionally used in calenders for coated paper, such as cotton wool, filmd cotton, white cotton paper, woolen paper, and asbestos, but these natural fibers are the main materials. The elastic roll used as the material has poor high-temperature durability and tends to lose surface roughness quickly, so it is best to use one or more layers of resin such as urethane, polyamide, epoxy, isocyanate, silicone, vinylidene fluoride, and phenol. (Japanese Unexamined Patent Publication No. 62-282093) made of synthetic fibers such as nylon, tetron, aramid, etc.
% or more (hereinafter collectively referred to as resin rolls) are preferable, and resin rolls made of aramid, epoxy, polyamide, etc., which have strong heat resistance, are particularly preferably used.

Regarding the hardness of the elastic roll, it is desirable to use a roll with Shore D hardness of 75° or more, considering durability under high temperature and high pressure and resistance to roughening during paper passing.Also, the higher the surface temperature of the elastic roll, the more Since roughening of the roll surface progresses quickly, it is preferable to cool the elastic roll from inside or outside the roll with a cooling liquid or cooling air.

In addition, in the method of the present invention, the surface roughness R of the elastic roll
max is measured based on the method defined in JIS B0651, but since the width of a normal calender roll of cast coated paper is about 1500 to 3800 mm, the measured value varies considerably in the width direction of the roll. Therefore, for example, as a measuring device, 5urf test t20 manufactured by Sanrai Seisakusho is used.
1, and the maximum measurement length (L) is 8 mm,
It is necessary to define the surface roughness Rmax by measuring at least 10 times over the entire elastic roll (or more times if the roll width is wide), and using the average value of the obtained measurement values.

Various processing conditions when surface treating coated paper with a heated calender are appropriate depending on the type of coated paper intended, base paper conditions, properties of the coated layer, coating amount, paper moisture, finishing speed, etc. adjusted.

Calender roll pressure conditions are 100 to 500 linear pressure.
kg/cm, and the number of pressurizing nips per calender is usually 2 to 6 per drum or 10 mm in the case of a soft compact calender.
It's Nitsubu. Incidentally, in the case of a super calender, about 3 to 13 nips are common.

Therefore, in terms of surface finish, cast coated paper is 2 to 12
The degree of decrease in surface roughness of the zero elastic roll that comes into pressure contact with an elastic roll of approximately 100 lbs.
It varies depending on many conditions such as hardness, roll temperature, pressure, speed, etc., so it is a hassle to constantly measure and manage it.
In the method of the present invention, it is necessary to operate using a roll having a surface roughness Rmax that satisfies the relationship of the above general formula for at least one of the latter elastic rolls that have a large effect on bumps. Of course, it is most preferable that all elastic rolls satisfy the above general formula.

The moisture content of cast coated paper before entering the calender nip is preferably about 3 to 10%, and the finishing speed of the calender varies greatly depending on the paper weight, paper type, etc., but is 100 to 400 m/min. A range of degrees is preferred.

In addition, in order to control and humidify the coated paper after surface treatment, we have installed water coating equipment using rolls, electrostatic humidification equipment, steam humidification equipment, etc., which are conventionally known in the field of coated paper manufacturing. It is of course possible to use various techniques in combination as appropriate.

"Example" The present invention will be described in more detail with reference to Examples below, but it is of course not limited to these.

Further, unless otherwise specified, parts and % in the examples indicate parts by weight and % by weight, respectively.

Examples 1 to 3 5 parts of Satin White (trade name: Sachin White, manufactured by Shiraishi Kogyo Co., Ltd.), 30 parts of kaolin (trade name: UW-90, manufactured by EMC Corporation), heavy calcium carbonate with an average particle size of 1.73 μm (Product name: Softon 1800, manufactured by Bihoku Funka Kogyo ■)
65 parts were dispersed in a Coles disperser using 0.2 parts of sodium polyacrylate as a dispersant to prepare a pigment slurry with a solid content concentration of 65%. To this pigment slurry, 3 parts of phosphoric acid-modified starch (solid content) and 12 parts of styrene-butadiene copolymer latex (trade name, JSRO696, manufactured by Japan Synthetic Rubber Co., Ltd.) (solid content) were added, and water was added to adjust the solid content. A coating liquid with a concentration of 60% was prepared. This coating solution was coated on the back side of a 75 g/day base paper using a blade coater so that the dry coating amount was 20 g/rd, and dried with a dryer at 120° C. to obtain a single-sided coated paper with a moisture content of 6%.

Separately, an aqueous coating liquid for casting with a solid content concentration of 53% was obtained, consisting of 80 parts of kaolin, 20 parts of light calcium carbonate, 10 parts of casein (solid content), and 8 parts of styrene-butadiene latex (solid content). This coating liquid was applied to the surface of the base paper to be coated on the back side, and finished by casting according to the wet-on-wet method as disclosed in Japanese Patent Publication No. 38-25160. That is, the surface of the base paper to be coated is coated with a casting coating liquid using a first coating device so that the dry weight is 11 g/%, and then, while this coating layer is in a wet state, a second coating liquid is immediately applied. In the coating device, the same casting coating liquid as in the case of the first coating device was applied so that the dry weight was 9 g/rd, and immediately it was pressed against a chrome-plated casting drum with a surface temperature of 90°C and dried. After that, the mold was released to obtain a cast coated paper.

This cast coated paper was heated to a metal roll with a surface temperature of 60°C and a surface roughness Rmax of 5 μl11 (Example 1) and 16 μm.
(Example 2), cast coating was performed using a 4-nip super calender consisting of a polyurethane resin elastic roll (trade name: ERAGLAS, manufactured by Kinyosha) with a diameter of 20 μm and a Shore D hardness of 86°. With the surface of the paper in contact with the metal roll, the speed was 200 m/w.
The surface of the paper was pressure-finished at a linear pressure of 150 kg/cm to obtain a cast coated paper.

The obtained cast coated paper was evaluated according to the evaluation items, and the results are shown in Table 1.

Comparative Examples 1 to 4 Comparative Example 1 is Example 1 in which the calendering treatment is not performed after casting, and Comparative Examples 2 to 4 are the case in which the resin elastic roll Rmax used in Example 1 is 37 μm (Comparative Example 2), 42μlI+ (Comparative Example 3), 50μm
(Comparative Example 4) Cast coated paper was produced in the same manner as in Example 1, and the evaluation results are shown in Table 1.

Example 4 Cast coated paper was produced in the same manner as in Example 1 except that the Shore D hardness of the resin elastic roll used in Example 1 was 78°, and the evaluation results are shown in Table 1.

Example 5 Example 1 except that 65 parts of light calcium carbonate (trade name: Tama Pearl 121, manufactured by Okutama Kogyo ■) with an average particle size of 1.10 μm was used as the calcium carbonate of the back coating layer pigment used in Example 1. Cast coated paper was produced in the same manner as above, and the evaluation results are shown in Table 1.

Comparative Example 5 In place of the light calcium carbonate with an average particle diameter of 1.10 μm used in Example 5, heavy calcium carbonate with an average particle diameter of 8.60 μm (trade name, BF-100, manufactured by IF Kitafunka Kogyo ■) was used. Cast coated paper was produced in the same manner as in Examples 1 and 5, except that 70 parts were used, and the evaluation results are shown in Table 1.

Examples 6-7 20 parts of kaolin, heavy calcium carbonate with an average particle size of 1.73 μm (trade name: Softon 1800, Bihoku Funka Kogyo ■
50 parts of light calcium carbonate with an average particle size of 1.10 μm (trade name: Tamavar 121, manufactured by Okutama Kogyo ■) 3
A coating liquid with a solid content concentration of 45% was prepared, consisting of 0 parts of oxidized starch (solid content), 3 parts of oxidized starch (solid content), and 13 parts of styrene-butadiene latex (trade name, JSR0696 manufactured by Japan Synthetic Rubber Co., Ltd.). This coating liquid was coated on the back side of high-quality base paper with a dry weight of 80 g/n (20 g/n) using an air knife coater.
RF coating and drying to prepare a back-coated base paper for casting.

Separately, 60 parts of kaolin, 40 parts of light calcium carbonate, and 0.5 parts of sodium polyacrylate were dispersed in water using a Coles disperser to prepare a pigment slurry with a solid content concentration of 60%. This is supplemented with 0 tributyl phosphate as an antifoaming agent.
．． 5 parts, ammonium stearate 1.0 as mold release agent
10 parts of a 15% casein aqueous solution (solid content) dissolved using ammonia as an adhesive and acrylic acid/butadiene/methyl methacrylate (ratio; 2/33/6
5) Add 16 parts of copolymer latex (solid content) and further add 3 parts of ZnSOs and water until the solid content concentration is 45.
% coating solution was prepared. The obtained coating liquid was used in JP-A-59-
Cast finishing was carried out according to the rewet casting method disclosed in Japanese Patent No. 216996.

This cast coated paper was coated with a metal roll having a surface temperature of 105'C and a surface roughness Rmax of 7 μm (Example 6) and 19 μm.
(Example 7), a 4-nip soft compact calender made of elastic rolls made of epoxy resin with a Shore D hardness of 90' was used.
The cast-coated paper was passed under the conditions of m/DIin and linear pressure of 200 kg/ca+ so that the surface of the cast-coated paper was in contact with a metal roll, and the surface was finished under pressure to obtain a cast-coated paper. Table 1 shows the evaluation results for each coated paper.

Comparative Example 6 R1llax of the elastic roll used in Example 6 was 42μ
Cast coated paper was produced in the same manner as in Example 5, except that m (Comparative Example 6) was used, and the evaluation results are shown in Table 1.

``Effect J'' As is clear from the results in Table 1, the cast-coated papers obtained in the Examples of the present invention all had significantly improved surface roughness, and the back surface smoothness and ink gloss were also extremely high. It was an excellent cast coated paper.When these were used as a cover, there was almost no difference in quality from the main text paper.Especially when the coating layer was the same as the back pigment coating layer shown in the example of the present invention. By using finished double-sided matte coated paper as the text paper, there is no sense of incongruity between the back of the cast cover and the text paper, resulting in an extremely high-class magazine.

(Note) Each evaluation method in Table 1 is as follows: [Surface unevenness] (Visual judgment of cast surface) ◎; Very good O; Good Δ; Poor ×; Extremely poor [Gloss] (The higher the value, the higher the Good) Murakami Color Research Institute (GM-30) showed a gloss value (measured value) of 75 degrees from C.

[Back surface smoothness] (The smaller the value, the better the smoothness) Measured using a Smoothstar measuring device (manufactured by Toei Denshi Co., Ltd.) DSM-01.

[Backside ink gloss]

8000 by Mitsubishi Heavy Industries diamond offset printing machine
Four-color printing was performed at a printing speed of sheets/hour, and the ink gloss of the four-color overlapping area was visually evaluated.

◎; Very good O; Good Δ; Poor ×; Very poor (Note) Surface roughness Rmax Measurement length (L
) was measured assuming that it was 8 mm.

Claims (3)

[Claims] (1) After forming a pigment coating layer containing pigment and adhesive as main components on the back side of the base paper, a pigment coating layer containing pigment and adhesive as main components is formed on the surface of the base paper, and then While the coating layer is in a plastic state, it is pressed onto the surface of a heated drum with a mirror surface and dried to obtain cast coated paper, and then the cast finished surface is placed on the heated metal roll surface and the back pigment coating layer surface is made elastic. In a method for manufacturing cast coated paper in which a heated calender is applied in contact with the roll surface to give a strong gloss finish, the surface roughness of the elastic roll R_m_a_x (JISB0651
) satisfies the following formula, and the measured value of white paper gloss according to JISP8142 method of the back coating layer is 40
% or less and smoothness by Smoostar smoothness meter is 15c
A method for producing cast coated paper whose back surface is a matte coated layer surface, which comprises performing a smoothing treatment so that the surface temperature is below mHg. (Note) R_m_a_x≦-0.1D-0.01T+35 [Notes] R_m_a_x; Surface roughness of elastic roll (μm) D; Shore D hardness of elastic roll (°) T; Surface temperature of metal roll during operation (℃) ) (2) The method for producing cast coated paper according to claim (1), wherein the back coating layer contains 50% by weight or more of calcium carbonate as a pigment. (3) Average particle size of calcium carbonate is 0.3 to 2.0μ
The method for producing cast coated paper according to claim (2), wherein m.