JPH01174696A - Production of lusterless coated paper - Google Patents

Abstract

PURPOSE:To obtain a lusterless coated paper having excellent printing ink acceptability and printing smoothness and having elegant and calm tone, by passing a cast paper having a specific water content through a specific roughened rolls in order to subject the cast paper to roughening treatment. CONSTITUTION:A cast coated paper having 2-8%, preferably 4-6% water content and obtained by bringing a wet coated layer containing a pigment and adhesive as a main component into contact with a heated drum having mirror gloss under pressure is passed through a roughened roll having 1-30mu, preferably 2-20mu surface roughness in JIS B0601 to provide the matte coated paper prefer ably having <=80mmHg smoothness by Smoothter smoothness measuring instru ment.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a method for producing matte coated paper, in particular a matte coated paper that has low white paper gloss but has extremely good printing ink receptivity and printing smoothness. This invention relates to a method for producing coated paper.

``Conventional technology'' Compared to high-gloss coated paper, matte coated paper has a more sophisticated and subdued tone, giving it a strong impression of luxury.
For example, it is used for a wide range of purposes, from covers, high-end posters, catalogs, calendars, etc. to single-color printed matter such as body paper, and is one of the coated papers with high general-purpose value.

There are two types of conventional matte coated paper: one is a base paper coated with a coating liquid containing a large amount of a relatively coarse pigment among the pigments used in ordinary coated printing paper, and is coated with a matte finish. The other two types are so-called low white paper gloss-high printing gloss matte coated paper with Matsudo gloss finish, which is finished using a roughening roll as described in Japanese Patent Publication No. 59-53956. In particular, the latter has a high gloss contrast between the blank paper surface and the printed surface, giving it a more luxurious image. However, all of these conventional matte coated papers are designed to reduce the gloss of the white paper, so they are usually inferior in smoothness, and furthermore, they are inferior to general gloss in terms of printing smoothness and printing ink receptivity. Currently, it is considerably inferior to coated paper for printing.

"Problems to be Solved by the Invention" The inventors of the present invention have attempted to solve the above-mentioned difficulties of conventional matte coated paper. If treated with a roughened roll, the white paper gloss will be reduced, but the printing smoothness and ink receptivity will not be degraded, making it an extremely ideal matte coating with low white paper gloss and excellent print finish quality. They discovered that a covering paper could be obtained and finally completed the present invention.

Conventionally, in order to improve the smoothness (print finish quality) of matte coated paper, coated paper has been manufactured by providing a base paper with a coating composition using fine pigments such as Sachin White and Kaolin.
Although improvements have been made by treating the coated paper with a roughening roll or by variously examining the selection of the material of the roughening roll, temperature and pressure conditions, etc., the quality is still satisfactory. In particular, when the temperature and pressure conditions are increased, the paper thickness becomes smaller and the stiffness decreases.

That is, the feature of the present invention is that cast coated paper, which has a high stiffness among printing coated papers, is used in order to obtain a matte coated paper that provides high smoothness and excellent printing finish quality and has stiffness (firmness). This process roughens the coating layer.

"Means for Solving the Problems" The present invention provides cast coated paper with a moisture content of 2 to 8%, which is obtained by press-contacting a wet coating layer mainly composed of pigments and adhesives to a heated drum having a specular gloss. JIS B0601 within the range of
This method of producing matte coated paper is characterized by passing the paper through a roughening roll having a surface roughness (Rmax) defined by 1 to 30μ.

"Operation" As mentioned above, the feature of the present invention is that the cast-coated paper having the highest level of gloss is purposely subjected to surface roughening treatment, and during this treatment, the cast-coated paper is passed through a roughening roll. It is necessary to specify the moisture content of 2-8%. moisture is 8
If it exceeds 2%, the desired smoothness can be obtained, but the paper thickness and stiffness decrease, while if it is less than 2%, problems such as poor paper curling may occur after the paper is passed through the roughened roll, making it unsuitable. A more preferable range is 4 to 6%.

In addition, the roughness of the roughening roll is 1 to 30μ, but 1μ
If it is less than 60%, the white paper gloss will be 60% or more, and the characteristics of a matte coated paper will be lost. Moreover, if it exceeds 30μ, the desired smoothness cannot be obtained, so it is more preferable to use 2μ.
A roll having a roughness of about 20 μm is used.

The surface of the coating layer of the matte coated paper obtained by the method of the present invention was measured with a smoothness needle of 89 mml (g
(The larger the value, the poorer the smoothness.) If the coating layer is treated to the following values, the gloss of the coated layer surface will decrease, but the printing smoothness and ink receptivity of the surface will remain the same as before treatment, resulting in excellent results. It has also become clear that print finishing quality is imparted.

Therefore, there are no particular restrictions on the number of times or pressure conditions for passing the paper through the roughening roll, but by appropriately adjusting it to achieve the smoothness described above, it is possible to achieve a uniform matte finish on the surface of the coated layer. By providing excellent printing smoothness and creating an elegant and calm astringency, matte coated paper of extremely excellent quality can be obtained.

Cast coated paper is particularly excellent among coated papers for printing in terms of gloss, smoothness, and printing smoothness, and is also characterized by high rigidity. By applying the above-mentioned specific surface roughening treatment to cast coated paper, which has such excellent characteristics, it is possible to efficiently reduce the gloss of the coated layer surface and improve ink receptivity and improve ink receptivity without compromising other qualities. The object of the present invention is to provide matte coated paper that suppresses deterioration in printing smoothness and has extremely excellent printing finish quality.

The highly glossy coated paper for printing called cast coated paper used in the present invention can be produced using the wet casting method, in which a wet coating layer is pressed against the surface of a heating drum to achieve a glossy finish, or the coating method in a wet state. Gelling casting method, in which the layer is in a gel state and pressed against the heated drum surface for a glossy finish; rewet casting, in which the wet coating layer is once dried or semi-dried, then plasticized by rewetting, and then pressed against the heated drum surface. There are single-sided cast paper and double-sided cast paper that are finished using methods such as methods.

The coating composition that forms the coating layer of the cast paper contains pigments and adhesives as main components.
For example, one or more types of general pigments for coated paper such as clay, kaolin, aluminum hydroxide, calcium carbonate, titanium oxide, barium sulfate, zinc oxide, satin white, and plastic pigments are appropriately selected and used.

Examples of adhesives include casein, soybean protein, styrene-butadiene copolymer, and methyl methacrylate.
Conjugated diene polymer latex such as butadiene copolymer, acrylic polymer latex such as polymer or copolymer of acrylic acid ester and/or methacrylic acid ester, vinyl polymer such as ethylene-vinyl acetate copolymer latex, or alkali-soluble or alkali-insoluble polymer latex modified with a functional group-containing monomer such as a carboxyl group, polyvinyl alcohol, acetoacetylated polyvinyl alcohol, carboxy-modified polyvinyl alcohol , sulfonic acid-modified polyvinyl alcohol, silicon-containing modified polyvinyl alcohol, synthetic resin adhesives such as olefin-maleic anhydride resins and melamine resins, starches such as positive starch and oxidized starch, and cellulose-based adhesives such as carboxymethyl cellulose and hydroxyethyl cellulose. General adhesives for coated paper, such as adhesives, can be used alone or in combination. These adhesives are used in an amount of about 5 to 50 parts by weight, more preferably about 10 to 30 parts by weight, per 100 parts by weight of the pigment. In addition, as the auxiliary agent, for example, an antifoaming agent, a coloring agent, a mold release agent, a fluidity modifier, etc. are used as appropriate.

The coating composition prepared in this manner can be applied to blade coaters, air knife coaters, roll coaters, brush coaters, curtain coaters, champlex coaters, bar coaters, gravure coaters, It is coated on one side or both sides of the base paper in one layer or in multiple layers using an on-machine or off-machine coater equipped with a coating device such as a size press coater.The solid content concentration of the coating composition is generally 40. ~70% by weight, but a range of 45 to 65% by weight is preferable in consideration of operability.The base paper is 30 to 400 g/r, which is used for general printing coated paper and cast coated paper.
RL paper-based or board-based base paper is used. The coating amount of the coating composition on such base paper is about 10 to 50 g/rd in terms of dry weight, but from the viewpoint of the white paper quality of the resulting cast coated paper and the speed increasing effect on casting operation, it is about 15 to 50 g/rd in terms of dry weight. Most preferably adjusted in the range of 35 g/cd.

In the method of the present invention, there are no particular limitations on the method of finishing the cast (conventional wet casting, gel casting, rewetting casting, etc. can be appropriately selected and used).

When passing cast coated paper through the roughening roll, which is a feature of the present invention, temperature control of the cast drum, pre-drying device, or humidity controller is used to adjust the moisture content of the coated paper to 2 to 8%. etc. are used as appropriate. The cast coated paper finished in this way is then passed through a roughening roll. This is done by passing the paper through a nip formed by a curing roll and an elastic roll made of paper, cotton, asbestos, plastic, etc.

In the case of double-sided cast coated paper, two hard rough surfaces having the above-mentioned specific surface roughness are placed on both sides of two elastic rolls such as plastic or cotton rolls as described in Japanese Patent Publication No. 47-85. A calender equipped with curing rolls is applied as a preferred embodiment.

In order to obtain the desired effect of the present invention, the roll temperature of the hard roughening roll when treating the coated paper is also an important factor. Usually, for coated paper for printing, 60
Generally, calendering is carried out at a roll temperature of ℃ or higher, but in the case of the matte coated paper of the present invention, it is desirable to pass the paper at a roll temperature of 55℃ or lower, more preferably 45℃ or lower. .

Therefore, adjustments are made as necessary, such as by installing a roll cooling device. In addition, the pressurizing conditions are adjusted as appropriate depending on the coating liquid composition of the coated paper, the surface roughness of the roughening roll, the roll temperature, and the desired quality design of the matte coated paper, but in general, roughening Coated paper density after treatment is 0.8-1.25g/
It is desirable to adjust it so that it becomes "cw+".

The material of the hard roughened roll used in the present invention is not particularly limited as long as it has the above-mentioned specific surface roughness, but generally metal rolls such as chilled alloy rolls and steel rolls are processed by sandblasting or corrosion. A roll whose surface has been roughened by a method or the like is preferably used, and if necessary, a roll which has been chromium plated can also be used.

Thus, the matte coated paper obtained by the method of the present invention does not lose the excellent quality characteristics and stiffness of the cast coated paper (but is extremely tasteful, has excellent print smoothness and print gloss) It is coated paper.

"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 1-4. Comparative Examples 1 to 3 A cast with a concentration of 58% consisting of 50 parts of kaolin, 50 parts of calcium carbonate, 12 parts of casein aqueous solution (solid content), and 12 parts of acrylic acid-butadiene-methyl methacrylate (2/33/65) copolymer latex. A coating liquid was prepared.

This coating liquid was coated on the surface of base paper with a weight of 135 g/%,
Cast finishing was performed using the wet casting method using the apparatus shown in FIG.

That is, the coating liquid for casting is coated on the surface of the base paper (1) by the first coating device (2) so that the dry weight is 20 g/rd, and then this coating layer is maintained in a moist state. While this is being done, immediately apply the same coating liquid as above using the second coating device (3) so that the dry weight is 14 g/I, and use the press roll (4) to give it a specular gloss. It was pressed against a cast drum (5) having a surface temperature of 90° C., and after drying, it was peeled off to obtain a cast coated paper (6). The obtained cast coated paper (6) was roughened using a 5-stage calender (Fig. 2) equipped with three hard roughening rolls having the surface roughness shown in Table 1. The temperature of the roll was adjusted to 30° C., and the number of nips was changed as shown in Table 1 to obtain matte coated paper. The quality evaluation and paper passing conditions of the obtained matte coated paper are also listed in Table 1. In addition, quality evaluation was performed according to the following method.

[Quality evaluation method]

White paper gloss: Angle 7 according to JIS P-8142
Measured at 5 degrees.

Blank paper smoothness - Measured using a smoothness meter (Smoostar) manufactured by Toi Denshi ■.

The unit is mmHg, the smaller the value Good smoothness.

Print smoothness and ink receptivity (print gloss): The smoothness and ink receptivity of printed matter printed by a Roland offset printing machine at a speed of 5000 sheets/hour were visually evaluated.

The evaluation criteria were the following three levels.

◎: Very good.

O: Excellent.

×: Inferior.

Example 5 Cast coating was applied to both sides of the base paper in the same manner using the same coating liquid as in Example 1 (after creating the single-sided cast coated paper, cast coating was applied to the back side in the same manner).Double-sided cast paper In a calender as shown in Fig. 3, which is manufactured by manufacturing and equipped with two roughening rolls, Rmax of the upper roughening roll is 10μ, and Rm of the lower roughening roll.
The paper was passed through a roughening roll having ax: 5μ to obtain a matte coated paper. Example 1 The matte coated paper thus obtained was
A quality test was conducted in the same manner as above, and the results are shown in Table 1.

Comparative Examples 4-5 48 parts of kaolin, 50 parts of calcium carbonate, 2 parts of Satin White, 7 parts of 25% starch aqueous solution (solid content), styrene-
A 55% art paper coating liquid consisting of 10 parts (solid content) of butadiene copolymer latex was prepared. The resulting coating liquid was applied to base paper with a dry weight of 22 g and a weight of 135 g/rrr.
Coater speed 450 m/rd so that
It was coated with a blade coater for 30 minutes and dried to obtain a coated base paper with a moisture content of 6% for art paper specifications.

The obtained coated base paper was passed through a calender equipped with a roughening roll in the same manner as in Example 1 to obtain a matte coated paper. The quality measurement results of the obtained matte coated paper are shown in Table 1.

“Effect” As is clear from the above results, the matte coated paper obtained by the method of the present invention has excellent printing smoothness and ink receptivity, and has an elegant and calm tone (Z knee 1”) - 2nd hook) (←77゛Nao'8 entry) Ramkitsune:
5P April 6, 1986

Claims (2)

[Claims] (1) Cast coated paper obtained by press-contacting a wet coating layer mainly composed of pigments and adhesives against a heated drum with specular gloss has a surface roughness specified by JISB0601 with a moisture content in the range of 2 to 8%. A method for producing matte coated paper, which comprises passing the paper through a roughening roll having (Rmax) of 1 to 30μ. (2) The matte coated paper according to claim 1, wherein the paper is passed through a roughening roll so that the surface smoothness of the resulting cast coated paper is 80 mmHg or less as measured by a smoother smoothness meter. manufacturing method.