JPH06306796A - Mat coated paper - Google Patents

Abstract

PURPOSE:To obtain mat coated paper, high in having both whiteness and glossiness of a printed surface and excellent in surface properties. CONSTITUTION:The mat coated paper is obtained by coating base paper with a coating consisting essentially of a pigment and an adhesive, drying the coated paper and then treating the surface with roughened rolls 3 and elastic rolls 1. The composition of the coating for the coated paper contains 20-60wt.% precipitated calcium carbonate having 0.1-0.8mum average particle diameter and 10-37wt.% kaolin based on the weight of the whole pigments so as to provide 80-90% whiteness of the coated paper defined by JISP8123 and 25-50% 75 deg. specular glossiness thereof defined by JISP8142.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a matte coated paper which has a high whiteness and a high glossiness on the printed surface and is excellent in surface properties.

[0002]

2. Description of the Related Art Matte coated papers are preferred for their calm feel, and are widely used in the fields of single-color printing to multi-color printing, and their demand is increasing. In order to give the product a high degree of surface property, the manufacturing method is generally a method of coating the base paper with a coating material, drying it, and then subjecting the coated surface to a roughening roll and an elastic roll for surface treatment. It has become established as a high-quality printing paper (Japanese Patent Publication No. 59-53956, Japanese Patent Application Laid-Open No. 1-260094, Japanese Patent Application Laid-Open No. 4-11).
9192, JP-A-4-153396, etc.).

However, recently, users have come to demand a matte coated paper having a significantly high whiteness and an outstanding finish on the printed surface.
Ingenuity is also required in the manufacturing method. That is, in order to maintain the whiteness of the coated paper at the maximum level, a heavy calcium carbonate is usually added to the paint at a high rate. Since the glossiness of is also reduced, the print finish becomes rather dull.

Therefore, a coating composition having a new composition for coated paper which does not depend on the conventional method is used to solve the conventional drawbacks, have excellent white paper and printing surface gloss, and have high whiteness. There is an urgent need for paper development.

[0005]

In order to obtain a coated paper having a high whiteness, it is necessary to select a pigment having the highest whiteness and a high glossiness as a pigment for coating the base paper. Although heavy calcium carbonate gives high whiteness, it has low glossiness, and kaolin, which is easy to produce gloss, has low whiteness. Therefore, both cannot be blended at a high rate.

However, since kaolin has the effect of maintaining the water-retaining property of the paint and preventing scratches on the coated paper from being scratched by a blade, that is, so-called streak, it is essential for the formulation. I can't.

Pigments capable of imparting both high whiteness and high gloss include precipitated calcium carbonate having fine particles and synthetic polymer pigments, which may be blended at a high rate.
Due to the above-mentioned drawback that streaks are likely to occur, the mixing ratio is also limited. In addition, precipitated calcium carbonate is
If the average particle size is not 0.8 μm or less, glossiness is poor. Therefore, it is desired to use the precipitated calcium carbonate which is as fine as possible, but there is a drawback in that it is not possible to manufacture a product having an average particle size of less than 0.1 μm.

The synthetic polymer pigment is composed of a polymer of styrene, a copolymer of styrene and butadiene, etc., has a high degree of whiteness and is excellent in imparting gloss, and depending on the type, Some have adhesive strength.

As described above, each pigment has various advantages and disadvantages, and it is attempted to obtain a coated paper having a high whiteness and a high printing surface gloss by blending these pigments in a well-balanced manner. No attempt has been made so far.

Furthermore, in order to obtain a coated paper having a high printing surface glossiness, it is necessary to impart a certain degree of glossiness to the white paper before printing. If the white paper glossiness is too low, the printing surface glossiness is unsatisfactory, and if it is too high, it cannot be said to be a matte paper. Normally, the coated paper has a white gloss of 50.
If it exceeds 50%, it can be visually observed that the surface of the white paper is glossy, and if it is not more than 50%, it cannot be said to be matte coated paper anymore.

Therefore, the level of the blank glossiness of the coated paper for obtaining a satisfactory glossiness of the printing surface is in a range of 25 to 50%, which is so-called dull. In a practical operation, it is effective to bring the coated paper into contact with a roughening roll having an appropriate surface roughness in order to give the paper a fine texture, so However, in order to have a glossiness of 50% or more, it is necessary to reduce the surface roughness of the roughening roll or to treat with a flat metal roll (chilled roll). In that case, Non-uniform gloss, so-called gloss mottle, is likely to appear on the surface of the coated paper after the treatment, and the whiteness as the object of the present invention is extremely high, and the finest matte coated paper excellent in surface property and printing surface glossiness. Cannot be.

In view of the above situation, the present inventors have conducted various studies on coating materials for coating base paper made of cellulose pulp, and as a result, have found that the composition of the coating materials includes precipitated calcium carbonate and kaolin having a specific average particle size range. The inventors have found that a matte coated paper having a high whiteness and a high printing surface glossiness and an excellent surface property can be obtained by using a specific amount, and thus the present invention has been completed.

[0013]

DISCLOSURE OF THE INVENTION The present invention provides a matte coating obtained by coating a base paper with a coating material containing a pigment and an adhesive as a main component, drying and then surface-treating it with a roughening roll and an elastic roll. In the coated paper, the coating composition of the coated paper contains 20 to 60% by weight of precipitated calcium carbonate having an average particle diameter of 0.1 to 0.8 μm and 10 to 37% by weight of kaolin based on the total weight of pigment. A matte coated paper characterized in that the coated paper has a whiteness of 80 to 90% defined by JIS P 8123 and a 75 degree specular gloss of 25 to 50% defined by JIS P 8142. is there.

The whiteness of the coated paper of the present invention is 80 to 90%.
However, the whiteness exceeding 90% was devised and tried to make it as high as possible, but 90% was the limit and could not exceed this. However, it can be said that this level is the coated paper with the highest whiteness when observed with the naked eye, and there is no practical problem, and the lower limit of 80%, which the user actually satisfies as a high-whiteness product, is significantly increased. It is superior to.

The coating composition of the coated paper of the present invention comprises 20 to 60% by weight, preferably 22 to 58% by weight, of precipitated calcium carbonate having an average particle size of 0.1 to 0.8 μm and preferably 10 to 10 kaolin, based on the total weight of pigment. -37% by weight, preferably 12-36% by weight.

The content of the precipitated calcium carbonate is 20
If it is less than 10% by weight, the whiteness of the coated paper does not reach a desired level even if other pigments are used together, and if it exceeds 60% by weight, streaks are likely to occur during coating, which is not suitable. On the other hand, if the content of kaolin is less than 10% by weight, the content of other pigments relatively increases, and streaks are likely to occur. If it exceeds 37% by weight, whiteness is insufficient, which is not suitable.

Other pigments for paints include heavy calcium carbonate, titanium oxide, aluminum hydroxide, satin white, zinc oxide, barium sulfate, calcium sulfate, calcium sulfite, talc, silica, activated clay, diatomaceous earth,
Examples thereof include synthetic polymer pigments, and these pigments may be appropriately selected and used in combination. In particular, using a small amount of a synthetic polymer pigment such as a styrene polymer or a styrene-butadiene copolymer is effective in improving both whiteness and glossiness, but it causes streaks, so a large amount should be added. Can not.

Further, as an adhesive for paint, casein,
Soybean protein, yeast protein, starch, oxidized starch, esterified starch, etherified starch, cationized starch, modified starch such as enzyme modified starch, natural adhesive such as cellulose derivative and styrene-butadiene copolymer, methyl methacrylate -Conjugated diene-based copolymer latex such as butadiene-based copolymer, acrylic-based polymer latex such as acrylic ester, methacrylic acid ester polymer or copolymer, vinyl acetate-based such as ethylene / vinyl acetate copolymer Polymer latex, synthetic adhesives such as polyvinyl alcohol, and the like are used, and one or more kinds of these adhesives are used, and 5 to 30 parts by weight are blended per 100 parts by weight of the pigment. Further, in the case of offset rotary printing, it is preferable to use latex having a small average particle size and a large gel content in order to prevent blisters during printing.

In addition to these, various auxiliaries used for ordinary coating liquids such as dispersants, flow modifiers, defoamers, and fluorescent dyes are appropriately selected and used as necessary. However, the fluorescent dye can give a whitening effect to the paper, but since it accelerates the fading of the paper, the addition rate should be as small as possible.

The base paper for coating the coating material obtained as described above has a whiteness of pulp of 80 to 90%, preferably 84 to 90%, such as hardwood bleached pulp and softwood bleached pulp. It is composed of a pulp containing as a main component, and besides, coated paper with a whiteness of 77 to 87%, deinked waste paper pulp, etc. are appropriately selected and mixed while maintaining the whiteness of the paper at a desired level. You may use it. The base paper may be acid paper, neutral paper or alkaline paper having a whiteness of 79 to 90%, preferably 81 to 88%, which is obtained by making a paper with a known wet paper machine. When the whiteness of the wood pulp is less than 80%, the whiteness of the desired paper cannot be ensured because the whiteness of the paper cannot be ensured because the loss of the whiteness becomes large due to the drying heat, water and the like during papermaking. In order to increase the content of the bleaching agent to more than 100%, it is necessary to increase the number of bleaching chemicals and / or to significantly increase the number of bleaching stages. If the whiteness of the base paper is less than 79%, the whiteness of the desired matte-coated paper cannot be obtained due to the loss of the whiteness during coating with a paint, drying and treatment with a roughening roll. On the contrary, the whiteness of the base paper exceeding 90% is not practical because it is very difficult to obtain the paper even by adjusting the raw materials and the papermaking conditions. In order to maintain the whiteness of the coated paper high, other means such as heavy calcium carbonate having excellent whiteness, precipitated calcium carbonate having excellent whiteness, and filtered fresh water as a filler may be used in addition to the pulp as required in the papermaking process. It is preferable to take these measures.

If desired, the base paper produced as described above is coated with a coating material in the range of 10 to 35 g / m ² per side. The coating method is not particularly limited, and it is used by appropriately selecting from a blade coater, an air knife coater, a bar coater, a roll coater, a chanplex coater, etc. used in the production of general coated paper, and one side of the base paper or Is applied on both sides in a single layer or multiple layers, and finally 3-8%
It is dried to a water content of and rolled up as coated paper.

The coated paper obtained in this manner is passed between the roughening roll and the elastic roll under pressure, and the nip linear pressure, temperature, and coating amount of the coating are adjusted to adjust the coating. A product having a white paper gloss of 25 to 50% and a whiteness of 80 to 90% is obtained.

The surface-roughening roll for use in the present invention is not particularly limited, and known ones may be used in appropriate combination with the elastic roll. That is, such a roughening roll is, for example, a steel or alloy roll having a desired roughness on the surface of the roll by a sand blast method, a corrosion method or the like, or a surface of which is subjected to a chrome plating treatment. Any known roll may be used, but a roll having a two-dimensional surface roughness Rmax defined by JIS B 0601 in the range of 5 to 35 μm is particularly effective.

On the other hand, for the elastic roll, cotton,
Known materials made of asbestos, wool, plastic and the like may be used, but those having a Shore D hardness of 80 ° or more according to ASTM standard D-2240 are preferably used.

When the coated paper is treated with the roughening roll and the elastic roll, the surface temperature of the roll is preferably 30 to 70 ° C. for effectively improving the surface property of the paper. The nip linear pressure of the roll is determined by a combination of the surface roughness of the roughened roll, the surface temperature of the roll, etc., but may be appropriately selected from the range of 100 to 300 Kg / cm.

The coated paper obtained as described above has a whiteness of 80 to 90% and a white paper gloss of 25 to 50%, and has high gloss after printing and excellent surface properties. It can be used as a high-grade printing paper.

[0027]

The present invention will be described in more detail with reference to the following examples, but of course the present invention is not limited thereto. In the following, parts and% mean parts by weight and% by weight.

Example 1 Hardwood bleached kraft pulp (LBK) with a whiteness of 86% and a freeness of 450 ml CSF (Canadian standard freeness)
P) 72% whiteness 86% freeness 400ml
Cationic starch (trade name: Kate F, manufactured by Oji National Co., Ltd.) is added per dry dry weight of a mixed pulp raw material of 8% of CSF softwood bleached kraft pulp (NBKP) and 20% of coated paper with whiteness of 80%. ) 0.5%, sulfuric acid band (18 crystal water salt of aluminum sulfate) 0.3%, alkenyl succinic acid-based sizing agent (manufactured by Mitsubishi Petroleum, trade name: Fibran 8)
1) 0.06%, heavy calcium carbonate (in-house wet crushed product) 6%, precipitating calcium carbonate (Toyo Denka Kogyo, trade name: TNC C-10) 6%, talc (Nippon Talc, trade name) : Talc-NT) 2%, polyacrylamide type retention aid (manufactured by Himo, trade name: DR-3500)
0.03% is added in this order to make paper by a known Fourdrinier paper machine,
Furthermore, a surface sizing agent having the following formulation was applied on both sides of the paper by a size press in a total amount of 2.0 g / m ² on both sides, and a press contacting treatment was performed with a machine calendar at a linear pressure of 20 kg / cm to obtain a whiteness of 82.5. %, The basis weight of the rice was 82.0 g / m ² , and the smoothness (Oken type) was 28 seconds to produce a base paper for coating.

Size press prescription Enzyme-modified starch (manufactured in-house) 80% Polyvinyl alcohol (Nippon Gosei Kagaku, trade name: T-330H) 17% Styrene acrylic acid-based sizing agent (Arakawa Chemical Co., 3% Polymalon 1308S)

Next, kaolin (manufactured by Engelhard, trade name: Ultra White 90) as a pigment is 36%, heavy calcium carbonate having an average particle diameter of 1 μm is 30%, and an average particle diameter is 0.12 μm. 24% of precipitated calcium carbonate (produced in-house) and 10% of satin white (produced in-house) having an average particle size of 1 μm are put into a mixer and stirred into the mixture, and oxidized starch (Oji corn starch is added per 100 parts of pigment). Made, product name: Oji Ace 4 parts and latex (made by Japan Synthetic Rubber, product name: J
SR-0632) 10 parts, sodium polyacrylate 0.3 parts as a dispersant, calcium stearate 0.4 parts as a lubricant, polyvinyl alcohol (manufactured by Kuraray, trade name:
0.1 part of PVA105 and 0.5 part of fluorescent dye (manufactured by Nippon Kayaku Co., Ltd., trade name: Kayahor PAS) are sequentially added, and after sufficiently mixing and dispersing, p is added using a 5% sodium hydroxide aqueous solution.
A coating liquid was prepared by adjusting H to be alkaline.

Both sides of the above-mentioned base paper were coated with the above coating liquid at a rate of 18 g / m ² per side by a blade coater and dried by a known drier to prepare a coated paper having a water content of 6%. This coated paper, as shown in FIG. 1, has two hard surface roughening rolls having a surface roughness Rmax defined by JIS B 0601 of 15 μm and Shore D according to ASTM standard D-2240.
In a super calender composed of 5 polyether elastic rolls (made by Yamauchi, trade name: YCR-5200) with hardness of 87 ° and 3 chilled rolls, while contacting at a temperature of 45 ° C. and a nip pressure of 170 kg / cm. ,
A matte coated paper was produced by passing the paper at a speed of 700 m / min so that the front surface and the back surface of the coated paper contacted the roughening roll twice, respectively.

A method for measuring the particle size of various pigments mixed in the paint,
The method for evaluating the occurrence of streaks in a coater and the method for evaluating the quality of the produced matte coated paper are shown below.

(1) Method of Particle Size Measurement Light transmission type particle size distribution analyzer (SACP-3 manufactured by Shimadzu Corporation)
The particle size of the pigment was measured by the centrifugal sedimentation method using L), and the particle size at which the weight accumulated from the smaller particles to the larger particle reached 50% was determined and expressed as the so-called average particle size. (2) Evaluation method of streak generation in coater During coating of the base paper with the blade coater, the coated surface immediately after coating and immediately before drying is visually evaluated, and the best state without streak is indicated as ◯, Below, they are displayed in the order of □, Δ, and ×.

(3) Method of quality evaluation 1) Surface property of white paper The matte coated paper was visually evaluated, and the one in the best state was marked as ◯, and the average of the front and back sides was shown in the following order of □, △, ×. . 2) Glossiness of white paper The 75-degree specular glossiness defined by JIS P 8142 was measured and shown as the average value of the front and back sides.

3) Whiteness of white paper The whiteness was measured according to the method for measuring paper according to JIS P 8123, and the average value of the front and back sides was shown. 4) Glossiness of printed surface After printing with a Mitsubishi diamond four-color printing machine, the four-color solid heavy-color portion was measured and displayed in the same manner as in 2). 5) Pulp whiteness It was measured according to the measurement method of pulp of JIS P8123.

Example 2 Kaolin 12% and ground calcium carbonate 3 as in Example 1
3%, Satin White 10% and average particle size 0.77μ
m mixed pigment consisting of 45% of precipitated calcium carbonate (manufactured by in-house) and used for offset rotary printing as latex (manufactured by Zeon Corporation, trade name: LX407GT129)
4) was used in an amount of 10 parts per 100 parts of the pigment, and the fluorescent dye and polyvinyl alcohol were not added to produce a coating material under the same conditions as in Example 1, and the same base paper as in Example 1 was used. Similarly, matte coated paper was manufactured and its quality was evaluated.

Example 3 Kaolin 21% and ground calcium carbonate 1 as in Example 1
8%, Satin White 20%, average particle size 0.40 μm
24% of precipitated calcium carbonate (made in-house) and 17% of synthetic polymer pigment (Made by Asahi Kasei, brand name: L8808)
A latex for offset rotary printing using a mixed pigment consisting of (Nippon Zeon, trade name: LX407
Example 1 except that 10 parts of GT1294) were used per 100 parts of pigment and no fluorescent dye and polyvinyl alcohol were added.
A paint was produced under the same conditions as in Example 1, and the same base paper as in Example 1 was used to produce a matte coated paper in the same manner as in Example 1.
The quality was evaluated.

Example 4 The same kaolin as in Example 12 12%, ground calcium carbonate 2
0%, Satin White 15%, average particle size 0.77 μm
A mixed pigment consisting of 50% of precipitated calcium carbonate (manufactured by in-house) and 3% of synthetic polymer pigment (manufactured by Asahi Kasei Co., Ltd., product name: L899) is used as a latex, product name: JSR-
A coating material was produced under the same conditions as in Example 1 except that 0632 was used in 10 parts per 100 parts of the pigment and the fluorescent dye and polyvinyl alcohol were not added, and the same base paper as in Example 1 was used. Then, matte coated paper was manufactured and its quality was evaluated.

Example 5 Kaolin 36% and ground calcium carbonate 2 as in Example 1
8%, Satin White 10%, average particle size 0.12 μm
22% of precipitable calcium carbonate (produced in-house) and 4% of synthetic polymer pigment (L8808) are used as a latex, and trade name: JSR-0632 is used as pigment 100.
A paint was prepared under the same conditions as in Example 1 except that 10 parts were used per part, and no fluorescent dye and polyvinyl alcohol were added.
Using the same base paper as in Example 1, a matte coated paper was produced in the same manner as in Example 1, and its quality was evaluated.

Example 6 Kaolin 12% and ground calcium carbonate 2 as in Example 1
Latex using a mixed pigment consisting of 5%, 5% satin white, 40% of precipitating calcium carbonate having an average particle size of 0.45 μm (manufactured by in-house), and 18% of synthetic polymer pigment (manufactured by Asahi Kasei Kogyo, trade name: L8808). Product name: JSR
A coating material was produced under the same conditions as in Example 1 except that the fluorescent dye and polyvinyl alcohol were not added in an amount of 10 parts per 100 parts of pigment, and the same base paper as in Example 1 was used. Similarly, matte coated paper was manufactured and its quality was evaluated.

Example 7 Kaolin 11% and ground calcium carbonate 1 as in Example 1
9%, Satin White 10% and average particle size 0.40μ
m mixed pigment consisting of 58% of precipitated calcium carbonate (manufactured by in-house) for offset rotary printing as latex (manufactured by Zeon Corporation, trade name: LX407GT129
4) was used in an amount of 10 parts per 100 parts of pigment, and a fluorescent dye and polyvinyl alcohol were not added, and a paint was produced under the same conditions as in Example 1. The base paper was made into an absolutely dry solid in the size press formulation of Example 1. A matte coated paper was produced in the same manner as in Example 1 except that 7 parts of the fluorescent dye was added per 100 parts by weight, and the quality of the matte coated paper was evaluated.

Comparative Example 1 Kaolin 40%, ground calcium carbonate 2 as in Example 1
8%, Satin White 10% and average particle size 0.12μ
m of the precipitated calcium carbonate (manufactured by Mitsui Chemicals Co., Ltd.) was used, and a paint for offset rotary printing (LX407GT1294) was used as a latex in an amount of 10 parts per 100 parts of the pigment. Manufactured,
Using the same base paper as in Example 1, a matte coated paper was produced in the same manner as in Example 1, and its quality was evaluated.

Comparative Example 2 The same kaolin as in Example 1 7%, ground calcium carbonate 36
%, Satin White 10% and average particle size 0.77 μm
The same conditions as in Example 1 except that a mixed pigment consisting of 47% of precipitated calcium carbonate (manufactured by in-house) was used, 10 parts of JSR-0632 was used as a latex per 100 parts of the pigment, and no fluorescent dye and polyvinyl alcohol were added. A coating material was manufactured in the same manner as in Example 1, and the same base paper as in Example 1 was used. A matte coated paper was manufactured in the same manner as in Example 1, and its quality was evaluated.

Comparative Example 3 The same kaolin as in Example 1 42%, heavy calcium carbonate 2
7%, Satin White 15% and average particle size 0.45μ
The same as in Example 1 except that a mixed pigment consisting of 16% of m-precipitating calcium carbonate (manufactured by in-house) was used, 10 parts of JSR-0632 was used as latex per 100 parts of pigment, and no fluorescent dye and polyvinyl alcohol were added. A paint was produced under the conditions, and the same base paper as in Example 1 was used. A matte coated paper was produced in the same manner as in Example 1, and its quality was evaluated.

Comparative Example 4 Kaolin 42% same as in Example 1, heavy calcium carbonate 3
0%, Satin White 10%, average particle size 0.12 μm
Using a mixed pigment consisting of 16% of precipitating calcium carbonate (produced in-house) and 2% of a synthetic polymer pigment (L8808), and a latex for offset rotary printing (manufactured by Zeon Corporation, trade name: LX407GT1294) as a pigment 100
A paint was prepared under the same conditions as in Example 1 except that 10 parts were used per part, and no fluorescent dye and polyvinyl alcohol were added.
Using the same base paper as in Example 1, a matte coated paper was produced in the same manner as in Example 1, and its quality was evaluated.

Comparative Example 5 Kaolin 21% and ground calcium carbonate 2 as in Example 1
6%, Satin White 10%, average particle size 0.45 μm
Using a mixed pigment consisting of 18% of precipitating calcium carbonate (made in-house) and 25% of synthetic polymer pigment (L8808),
A paint was produced under the same conditions as in Example 1 except that JSR-0632 was used as a latex in an amount of 10 parts per 100 parts of the pigment, and no fluorescent dye and polyvinyl alcohol were added. A matte coated paper was produced in the same manner as in Example 1 and its quality was evaluated.

Comparative Example 6 Kaolin 21% and heavy calcium carbonate 4 as in Example 1
%, Satin white 10%, precipitated calcium carbonate having an average particle size of 0.45 μm (produced in-house) 62%, and synthetic polymer pigment (L899) 3% as a latex for offset rotary printing ( A paint was manufactured under the same conditions as in Example 1 except that 10 parts by weight of 100 parts of pigment (trade name: LX407GT1294, manufactured by Nippon Zeon Co., Ltd.) was used, and no fluorescent dye and polyvinyl alcohol were added. The base paper was also the same as in Example 1. Was used to produce a matte coated paper in the same manner as in Example 1, and the quality was evaluated.

Comparative Example 7 Kaolin 21% and ground calcium carbonate 1 as in Example 1
8%, Satin White 20%, average particle size 0.85 μm
Using a mixed pigment consisting of 24% of precipitated calcium carbonate (produced in-house) and 17% of synthetic polymer pigment (L8808),
A paint was produced under the same conditions as in Example 1 except that JSR-0632 was used as a latex in an amount of 10 parts per 100 parts of the pigment, and no fluorescent dye and polyvinyl alcohol were added. A matte coated paper was produced in the same manner as in Example 1 and its quality was evaluated.

Results obtained in Examples 1 to 7 and Comparative Example 1
The results obtained for ~ 7 are shown in Table 1.

[0050]

[Table 1]

The matte-coated paper of the present invention has no streak on the surface and has a very high whiteness in the range of 80 to 90%, and a white paper glossiness in the range of 25 to 50%. The glossiness is extremely high in the range of 65 to 90% (Examples 1 to 7). On the other hand, when the pigment composition is not within the proper range, only coated paper having inferior whiteness and printed surface glossiness can be obtained. That is, if the content ratio of kaolin is too large, the whiteness is insufficient (Comparative Example 1), and if it is too small, the water retention property of the paint cannot be maintained, and thus a streak occurs in the coater (Comparative Example 2). If the blending ratio is too small, the glossiness may be maintained due to the effect of kaolin, but the whiteness may not be satisfactory (Comparative Example 3). Conversely, if it is too large, streaks may occur (Comparative Example 6). . Further, the effect of the particle size of the precipitated calcium carbonate on the expression of gloss on the printing surface is extremely large, and if the particle size is large, the glossiness is significantly impaired (Comparative Example 7). When the blending ratio of the precipitated calcium carbonate is less than 20%, the whiteness is insufficient. Therefore, even if an attempt is made to supplement the whiteness by using the synthetic polymer pigment, the effect is not obtained if the blending amount of the synthetic polymer pigment is too small. If no synthetic polymer pigment is produced (Comparative Example 4) and conversely there is too much synthetic polymer pigment, streaks are caused, which is inconvenient (Comparative Example 5).

[0052]

INDUSTRIAL APPLICABILITY The present invention has an effect that not only the surface property is excellent, but also the whiteness and the glossiness of the printing surface are at the highest level, and a matte coated paper suitable for the highest grade application can be provided.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a super calender device used in Examples and Comparative Examples of the present invention, which is composed of 10-stage rolls including a roughening roll for obtaining a matte coated paper.

[Explanation of Codes] 1 ... Elastic roll 2 ... Chilled roll 3 ... Roughening roll 4 ... Paper roll 5 ... Coated paper

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kusumi Kusumi 373 Yoshioka, Yonago City, Tottori Prefecture Oji Paper Co., Ltd. Yonago Mill

Claims (1)

[Claims] 1. A matte coated paper obtained by coating a base paper with a coating material containing a pigment and an adhesive as a main component, drying it, and then surface-treating it with a roughening roll and an elastic roll. The coating composition has an average particle size of 0.1 to 0.8 based on the weight of all pigments.
The coated paper contains 20 to 60% by weight of precipitated calcium carbonate and 10 to 37% by weight of kaolin, and the coated paper has a whiteness of 80 to 90 defined by JIS P8123.
% And a 75-degree specular gloss defined by JIS P 8142 of 25 to 50%, a matte coated paper.