JP3230229B2 - Coated paper manufacturing method and coated paper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the production of a coated paper having excellent high-speed operability and excellent surface condition and printing surface strength after top coating when a base paper is coated with a base coating liquid. Method and its coated paper.

[0002]

2. Description of the Related Art In recent years, demand for printing paper has tended to gradually increase. In particular, there is a growing demand in the commercial printing field for advertisements and advertisements such as flyers, catalogs, brochures, and direct mails. Although these commercial prints have low commercial value themselves, it is important that the purpose be achieved as an advertising medium, so low-cost, good-quality prints are required, and paper users are becoming more cost-conscious. And the use of paper is also getting lower and lighter.

In order to respond to such a vigorous demand, paper manufacturers have been promoting wider and faster coating equipment in order to achieve more efficient production and cost reduction of products, while maintaining high quality. Increasing productivity is an important technical issue.

[0004] Coating paper production methods include an off-machine coating method in which papermaking and coating are performed in separate steps, and an on-machine coating method in which papermaking and coating are performed simultaneously by a single machine. The on-machine coating method has a feature that the production cost of the product can be reduced and the product having a price competitiveness can be manufactured as compared with the off-machine coating method.

[0005] In particular, in the case of a multi-layer coated paper, a base paper is coated with an undercoating coating liquid containing an inexpensive pigment on-machine and then coated with a top coating liquid, so that it is less expensive than a single-layer coated paper. Products can be manufactured, and in terms of quality, coating of base paper is improved by applying a base coat, and surface quality and printing quality are improved. In recent years, not only conventional high-grade paper (art paper), Even in the production of coated paper with a smaller coating amount, products using multi-layer coating are increasing. For this reason, there is a demand for an even higher speed of a film transfer coating apparatus which is an on-machine coating method.

However, when an ordinary pigment coating liquid is used for undercoating base paper using a gate roll coater, a blade or a rod metaling size press coater used in an on-machine coating method, it has been an operation to date. The maximum speed is about 1100 m / min. One of the reasons that hinders the speeding up is a phenomenon called mist, in which in the case of a blade or rod metering size press coater, the coating liquid becomes mist and scatters at the exit of the applicator roll nip. Mist is 11 depending on operating conditions.
It starts to occur even at a speed lower than 00 m / min. However, the degree increases significantly at higher speeds, which worsens the working environment. At the same time, when the peripheral rolls are soiled and further dried and solidified, they fall onto the paper surface, resulting in product defects. Becomes Also, in the case of a gate roll coater, a similar problem of mist generation occurs, and when the mechanical stability of the coating liquid is inferior, between the inner roll and the outer roll or between the inner roll and the applicator roll. Due to the shearing force applied between the rolls having different roll diameters and peripheral speeds, a phenomenon called gum-up in which the coating liquid solidifies and adheres to the roll surface occurs, thereby reducing operability. Also, there is a problem that the paper separation from the roll at the exit of the applicator roll nip is not stable, and a line-shaped unevenness called a peeling pattern or a ring pattern occurs.

[0007] Among the problems that occur when performing high-speed coating by the film transfer method, it is known to use a low-concentration coating liquid as a means for improving mist and a peeling pattern. However, the use of a low-concentration coating liquid increases the drying load, increases the penetration of the coating liquid into the base paper, lowers the base paper coatability, and increases the gloss unevenness after the top coating is applied. This causes new problems such as a decrease in printability. Further, in the case of a multi-layer coated paper in which the coating liquid is undercoated on-machine, there is a problem that the printing surface strength is inferior to that of a single-layer coated paper in which starch is individually size-pressed. On the other hand, JP-A No. 7-189188 discloses a method for increasing the coating solution concentration, not causing mist and gum-up during high-speed operation, and preventing surface unevenness. At a coating solution concentration of 58% or more using the starch derivative of
It has been proposed to use a coating liquid having a mold viscosity of 1500 cps or less. However, in the examples in this publication, mist, gum-up, and surface unevenness tended to occur under high-speed operation of 1100 m / min or more as intended by the present invention, and the operation was not stable.
Furthermore, this publication does not consider the production of a multilayer coated paper, and if an overcoat layer is provided on the coating layer formed with the coating liquid of this publication, the printing strength and the like of the finished coated paper Was not enough.

[0008]

In view of the above situation, an object of the present invention is to use the film transfer method as described above, and to apply the undercoat coating liquid under high-speed conditions, especially at a high speed of 1100 m / min or more. It is an object of the present invention to provide a method for producing coated paper having excellent operability, which is a problem in the production process of undercoating base paper, and excellent quality after overcoating, and a coated paper.

[0009]

Means for Solving the Problems As a result of intensive studies on the above problems, the present inventors have found that a base paper is coated with a coating liquid containing a pigment and an adhesive undercoating and overcoating. In the production method, dispersing with a dispersant excluding the cationic dispersant
An undercoating coating liquid containing 15 to 30 parts by weight of a starch derivative as an adhesive and having a dynamic water retention of 100 to 150 g / m @ 2, based on 100 parts by weight of the dispersed pigment, was coated by a film transfer method. The present invention has been accomplished by applying an undercoat to a base paper using an apparatus and then applying an overcoat. The present invention is intended to limit the amount of a starch derivative used as an adhesive in an undercoating coating liquid for coating base paper with a film transfer type coating apparatus, and to further control the dynamic water retention of the undercoating coating liquid. There is a feature. As a result, problems such as mist generation and operability, which are problems in the production process of undercoating the base paper, such as gum up, are improved, and at the same time, coated paper excellent in surface condition and print quality after overcoating is obtained. Can be done.

The starch derivative used as the adhesive of the present invention must be incorporated in an amount of 15 to 30 parts by weight, more preferably 18 to 28 parts by weight. If the amount of the starch derivative is less than 15 parts by weight, gum up occurs frequently and the printing surface strength is reduced due to the insufficient amount of adhesion in terms of quality. If the amount is more than 30 parts by weight, the viscosity of the coating liquid becomes too high, and mist and peeling patterns frequently occur.

The dynamic water retention of the coating liquid of the present invention is 100 to 100.
It is necessary to adjust to 150 g / m ² . If the dynamic water retention of the coating liquid exceeds 150 g / m ² , gum up occurs frequently due to the shearing force applied between the rolls. Also 100
If it is less than g / m ^2, the paper separation from the roll at the exit of the applicator roll will not be stable, and mist and peeling patterns will occur frequently.

[0012] The starch derivative used in the present invention is preferably a phosphorylated esterified starch. Thereby, it is easy to adjust a coating liquid having good balance such as dynamic water retention, color stability, color foaming property and printing surface strength. Further, the present inventors have found that it is possible to solve the problems of mist generation, peeling pattern, and gum-up that appear more remarkably particularly at high-speed operation conditions of 1100 m / min or more.

In the present invention, the film transfer type coating apparatus preferably uses a gate roll coater or a rod metering size press coater having a rod having a diameter of 30 to 50 mm and having a smooth surface. When both are coated with the pigment coating liquid at high speed, they are excellent in balance between operability and quality. However, when a rod metering size press is used, if the diameter of the rod is smaller than 30 mm, the film forming ability of the pigment coating liquid is reduced, and a uniform film cannot be transferred to the paper surface. It tends to be inferior. On the other hand, rods larger than 50 mm do not need to be particularly large because the effect does not change. If the surface is not a smooth rod,
That is, in the case of a rod having a groove, a problem of streak generation is likely to newly occur.

[0014]

Pigment used in DETAILED DESCRIPTION OF THE INVENTION The present invention is primed
The pigment in the coating liquid is dispersed with a dispersant except the cationic dispersant.
If not specified, heavy calcium carbonate, light calcium carbonate, kaolin, clay, talc, satin white, plastic pigment, titanium dioxide, silica and the like are used, although not particularly specified. In addition , it is preferable to use heavy calcium carbonate as a main component of the undercoating pigment.

As the adhesive of the present invention, phosphoric esterified starch is preferred as the starch derivative, but etherified starch, oxidized starch, esterified starch,
Enzyme-modified starch and cold-water-soluble starch obtained by flash-drying them may be used. Particularly, these starch paste solutions have a solid content of 30% and a viscosity at 30 ° C. of 40%.
More preferably, it is 0 to 1800 mPa · s. Further, as an adhesive other than the starch derivative, a copolymer latex, casein, polyvinyl alcohol, etc., which are generally used, can be used in combination. Incidentally, the copolymer latex is a styrene-butadiene-based, styrene-
Examples include various copolymer latexes such as acrylic, vinyl acetate / acrylic, butadiene / methyl methacrylic, and modified products of these various copolymer latexes by a chemical reaction.

In the coating liquid of the present invention, various auxiliaries such as a dispersant, a thickener, a water retention agent, an antifoaming agent, and a waterproofing agent may be used.
Further, as the base paper for coating, base paper having a basis weight of 30 to 100 g / m ² used for general printing coated paper such as high-quality paper and medium-quality paper is preferable, and regarding the freeness of pulp, It is preferable that the Canadian standard freeness is 250 to 400 ml.

The amount of undercoat is 2 per side of the base paper.
It is preferable to apply the coating at 8 g / m ² . When the amount of coating is less than 2 g / m ^{2, the} concentration of the coating liquid must be greatly reduced due to the limitations of the apparatus, and as a result, the base paper coatability is inferior, and the surface state after overcoating tends to decrease. is there. On the other hand, when the amount of coating is more than 8 g / m ^2, it is necessary to increase the concentration of the coating liquid. Surface roughness easily occurs on the paper surface.

As the calendering apparatus after the undercoating and drying, a usual calendering apparatus is used, but a steel calender composed of a metal chill roll or a soft calender composed of a metal chill roll and an elastic roll is used. Is more preferable.

In the present invention, the pigment, adhesive composition, blending amount, coating amount and the like of the topcoat liquid are not particularly limited, but include pigments and adhesives generally used as described above. The concentration of the coating liquid is preferably from 60 to 68%, and the amount of the top coating is usually from 6 to 14 g / m2 per one side.
² is preferred.

It is preferable that the coated paper which has been overcoated and dried as described above is glossed by a finishing process such as a super calender or a soft calender as usual.

[0021]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited by these examples. In addition, the number of parts and% in an example show a solid content weight part and weight%, respectively. The quality evaluation method is as follows.

<Quality Evaluation Method> (1) Dynamic Water Retention The coating solution concentration was adjusted to 37%, and Kaltec Scie was used.
The amount of dehydration of the coating liquid was measured under the conditions of a temperature of 25 ° C., a pressure of 150 kPa and a time of 200 seconds using a dynamic water retention tester manufactured by ntific.

(2) Blank glossiness Measured at an angle of 75 degrees according to JIS P-8142.

(3) Gloss after printing Using an RI-II type printing machine (manufactured by Meiji Seisakusho), Sakata Inks offset printing ink (trade name: Diatone)
GSL red) was printed using 0.35 cc, and after standing overnight, the glossiness was measured at 75 degrees.

(4) Smoothness In accordance with JAPAN Tappi No. 5, the smoothness was measured with an Oken type smoothness tester. (5) Printing surface strength Using an RI-II type printing machine (manufactured by Akira Seisakusho), using Toyo Ink TV-24, printing at a constant rotation speed of 40 rpm and an ink amount of 0.35 cc, the degree of picking of the printing surface. Was visually evaluated relative to each other.

＝= No occurrence, ＝= Nearly occurrence Δ = Yes, X = Severe occurrence (6) Blank white paper The unevenness of white paper gloss was evaluated by visual observation.

＝= No unevenness, 全 く = Almost no unevenness △ = Some unevenness, X = Severe unevenness (7) Evaluation of gum-up occurrence The appearance of gum-up when coated for 24 hours is visually judged. did.

＝= Not generated at all, ＝= Not generated at all △ = Produced, X = Remarkable generation (8) Evaluation of mist generation At the time of coating, the state of mist generation was visually judged.

＝= Not generated at all, ほ と ん ど = Not generated at all △ = Produced, X = Remarkable occurrence (9) Evaluation of release pattern The state of generation of the release pattern at the time of coating was visually judged.

◎ = Not generated at all, ○ = Almost not generated △ = Generated, X = Remarkable generation [Example 1] Heavy calcium carbonate having an average particle diameter of 0.6 μm (Shiroishi Calcium Co., Ltd., Hydrocarbo) 90) 1
To 00 parts, sodium polyacrylate dispersant 0.3
Was added and dispersed in water using a Cowles disperser, and 20 parts of a phosphorylated ester starch (Japan Food Processing Co., Ltd., MS-4600) and 5 parts of a styrene-butadiene latex were compounded as an adhesive, An undercoat pigment coating liquid having a concentration of 48% and a dynamic water retention of 125 g / m ² was prepared.

Further, 50 parts of kaolin (ECC Co., Ltd., β-coat) having an average particle size of 0.55 μm and heavy calcium carbonate (Shiroishi Calcium Co., Ltd., Hydrocarbo 90) having an average particle size of 0.60 μm are used. Containing 1 part
To 00 parts, a dispersant (Toa Gosei Co., Ltd., Aron T-
40) Add 0.3 part, disperse in water using Cowles disperser, 5 parts of phosphorylated starch as adhesive,
Mixing 10 parts of styrene / butadiene latex,
A topcoat pigment coating liquid having a concentration of 63% was prepared.

These coating liquids were prepared at a basis weight of 54 g / m ² ,
Using a gate roll coater as a coating device for coating undercoat pigment on a base paper blended with bleached kraft pulp of 300 ml of hardwood bleached with a Canadian standard freeness, a coating speed of 1200 m
/ G, 5 g / m ² per side, coated on both sides, dried, then soft calendered (conditions: 50 ° C., 100 kg
/ Cm). Further, a high-speed blade coater was used as a coating device for coating the topcoat pigment, and a coating speed of 1200 m
/ Min, 8 g / m ² per side was coated on both sides. Further, after overcoating and drying, gloss finishing was performed using a 12-stage super calendar (manufactured by Minami-Senju Seisakusho).

Example 2 In preparing an undercoat pigment coating liquid, etherified starch (Penford Gum Co., Ltd.
G-295), and coated paper was produced in the same manner as in Example 1 except that 20 parts of styrene-butadiene latex was blended.

At this time, the dynamic water retention of the undercoat pigment coating liquid was 110 g / m ² .

[Example 3] A rod metering size press coater having a rod having a diameter of 40 mm and a smooth surface was used as a coating device for applying an undercoat pigment.
A coated paper was produced in the same manner as in Example 1. At this time, the dynamic water retention of the undercoat pigment coating liquid was 125 g / m ² .

Example 4 When preparing an undercoat pigment coating liquid, a phosphorylated ester (Nippon Food Processing Co., Ltd.
MS-4400), and a coated paper was produced in the same manner as in Example 1 except that 26 parts of styrene-butadiene latex was blended.

At this time, the dynamic water retention of the undercoat pigment coating liquid was 118 g / m ² .

Example 5 When preparing an undercoat pigment coating liquid, a phosphate esterified starch (Nippon Food Processing Co., Ltd.
MS-4600), and coated paper was produced in the same manner as in Example 1 except that 17 parts of styrene / butadiene latex was blended.

At this time, the dynamic water retention of the undercoat pigment coating liquid was 144 g / m ² .

[Comparative Example 1] When preparing an undercoat pigment coating solution, a phosphate esterified starch (Shikishima Starch Co., Ltd.,
MC-2000), and coated paper was produced in the same manner as in Example 1 except that 20 parts of styrene-butadiene-based latex was blended. At this time, the dynamic water retention of the undercoat pigment coating liquid was 505 g / m ² .

[Comparative Example 2] A phosphate esterified starch (Nippon Food Processing Co., Ltd.
MS-4400), and coated paper was produced in the same manner as in Example 1, except that 20 parts of styrene-butadiene latex was blended. At this time, the dynamic water retention of the undercoat pigment coating liquid was 172 g / m ² .

[Comparative Example 3] When preparing an undercoat pigment coating solution, oxidized starch (M-210, Shikishima Starch Co., Ltd.)
A coated paper was produced in the same manner as in Example 1 except that 20 parts and 5 parts of a styrene / butadiene latex were blended. At this time, the dynamic water retention of the undercoat pigment coating liquid was 81 g / m ² .

[Comparative Example 4] When preparing an undercoat pigment coating solution, a phosphate esterified starch (Nippon Food Processing Co., Ltd.
MS-4600), and coated paper was produced in the same manner as in Example 1 except that 32 parts of styrene-butadiene latex was blended. At this time, the dynamic water retention of the undercoat pigment coating liquid was 85 g / m ² .

Comparative Example 5 When preparing an undercoat pigment coating liquid, a phosphate esterified starch (Nippon Food Processing Co., Ltd.
MS-4600), and coated paper was produced in the same manner as in Example 1 except that 13 parts of styrene-butadiene-based latex was blended. At this time, the dynamic water retention of the undercoat pigment coating liquid was 169 g / m ² .

Comparative Example 6 When preparing an undercoat pigment coating liquid, a phosphate esterified starch (Sanwa Starch Co., Ltd., PN
-300) A coated paper was manufactured in the same manner as in Example 1 except that 33 parts of styrene-butadiene-based latex was blended. At this time, the dynamic water retention of the undercoat pigment coating liquid is 120.
g / m ² .

[Comparative Example 7] When preparing an undercoat pigment coating liquid, oxidized starch (M-210, Shikishima Starch Co., Ltd.)
A coated paper was manufactured in the same manner as in Example 1 except that 13 parts and 5 parts of a styrene / butadiene latex were blended. At this time, the dynamic water retention of the undercoat pigment coating liquid was 133 g / m ² .

The above results are shown in Tables 1 and 2.

[0048]

[Table 1]

[Table 2] As is clear from Tables 1 and 2, Examples 1 to 5 have high smoothness, high gloss after printing, excellent surface strength, and excellent surface condition of blank paper, and mist, gum up, and peeling pattern at the time of undercoating coating are completely or almost nonexistent. Does not occur. In contrast, Comparative Example 1,
In No. 2, the occurrence of gum up is remarkable. In Comparative Examples 3, 4, and 6, mist and peeling patterns are remarkably generated. In Comparative Examples 5 and 7, the printing surface strength was inferior and the occurrence of gum up was remarkable.

Accordingly, the coated paper produced according to the present invention provides unprecedented excellent high-speed operability and coated paper quality,
The effect is extremely large.

[0050]

According to the present invention, a film transfer method is used,
Under high-speed conditions, especially at a high speed of 1100 m / min or more, the operability which is a problem in the production process of undercoating is improved, and the surface condition (surface coverage and gloss unevenness) after overcoating and excellent printing surface strength are excellent. A coated paper can be obtained.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-241199 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) D21H 11/00-27/42

Claims (5)

(57) [Claims] 1. A method for producing a coated paper in which a base paper is coated with a coating liquid containing a pigment and an adhesive by undercoating and overcoating.
The undercoat is dispersed with a dispersant except the cationic dispersant.
A starch derivative is contained as an adhesive in an amount of 15 to 30 parts by weight with respect to 100 parts by weight of
A method for producing coated paper, characterized in that the undercoating coating liquid of 100 to 150 g / m @ 2 is applied by a film transfer type coating apparatus. 2. The method for producing coated paper according to claim 1, wherein the starch derivative is a phosphate esterified starch. 3. The method for producing coated paper according to claim 1, wherein the coating speed of the undercoat is 1100 m / min or more. 4. The coating apparatus according to claim 1, wherein the film transfer type coating apparatus is a gate roll coater or a rod metaling size press coater having a rod having a diameter of 30 to 50 mm and having a smooth surface. Manufacturing method of paper. 5. A coated paper manufactured by the manufacturing method according to claim 1.