JP2838007B2 - How to make matte 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 a method for producing a matte coated paper, and more particularly to a matte coated paper which has a low glossiness of a white paper and does not cause a problem of transfer of a printing ink to a white paper part which occurs in a bookbinding process or the like. The present invention relates to a paper manufacturing method.

[0002]

2. Description of the Related Art In recent years,
The need for matte and dull matte coated papers that give a moist but calm image instead of glossy coated papers with high blank paper gloss, which has been conventionally used, is increasing. It is widely used mainly in high-end art printing, catalogs, brochures, calendars, and commercial paper.

[0003] Matte coated papers use a coating liquid containing a large amount of coarser pigments as compared with pigments used for ordinary printing coated papers in order to keep the glossiness of a blank paper surface low. The product may be commercialized as it is, or it may be commercialized by performing a slight calendering treatment within a range where the gloss of blank paper does not excessively increase.

[0004] The paper printed in the printing process is bound into a book through a bookbinding process, and the matte coated paper is printed by a folding machine or a collating machine in the bookbinding process. This causes the printing ink to transfer to the blank paper, or the contact between the front and back covers during stacking after bookbinding, causing the printing ink to transfer to the blank paper surface, greatly deteriorating the quality of the printed matter. That is the current situation.

[0005] The main causes of the transfer of the printing ink to the blank portion are as follows. Matte coated paper contains a lot of irregular and relatively coarse pigments in order to suppress the gloss of white paper, so the pigment orientation on the surface of the coated paper is inferior. It is conceivable that the pigment projecting on the surface of the coating layer scrapes the printing ink. In recent years, since high-speed printing has been attempted, high ink receptivity is required for printing paper, and the coated paper is designed to easily absorb the ink vehicle. For this reason, it is conceivable that the coating strength of the printed ink becomes weak, and the ink easily falls off when the printed portion comes in contact with the blank portion.

[0006] Since matte coated paper is widely used especially for high-quality printed matter, there is a problem that the printed ink is transferred to a blank paper surface, which is peculiar to the matte coated paper. At present, it no longer functions as a high-quality printing paper.

As a means for solving the above problems, the present inventors have applied a coating composition containing 20 to 80% by weight of a delaminated clay to a printing paper to form a white sheet of printing ink. That the metastasis can be suppressed.
3-180527). Also, 50-80% by weight of calcium carbonate,
It has been found that the same effect can be obtained by applying a coating liquid containing 20 to 50% by weight of clay, followed by drying and then performing soft calendering at a high temperature of 100 ° C. or higher (Japanese Patent Application No. Hei.
279908). Further, the present inventors have proposed a method for producing a coated paper in which a base paper is coated twice with a coating liquid, wherein calcium carbonate having an average particle size of 3 μm or less is added to 100% by weight of the total pigment in the undercoating coating layer. It has been found that matte coated paper containing at least 40% by weight of clay with respect to 100% by weight of the total pigment in the overcoating layer has the same effect as above (Japanese Patent Application No.
3-352066). However, in the above prior art for sheet gloss increases, had to use a low latex of T _g in order to alleviate this a little.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the difficulties of the matte coated paper, and as a result, the pigment component has an average particle diameter of 0.6 to 1.6 μm.
70-85% by weight of heavy calcium carbonate and kaolin 15-
30% by weight and glass transition temperature ( _Tg ) as an adhesive component
The base paper is coated with a coating composition containing 3 to 25% by weight of a polymer latex having a temperature of 10 ° C. or higher based on 100% by weight of a pigment, and the white paper gloss is particularly low. It was later found that a very ideal matte-coated paper free from the problem of transfer of the printing ink to the blank portion was obtained, and the present invention was completed.

That is, according to the present invention, the average particle diameter is 0.6 to 1.6 μm.
70-85% by weight of heavy calcium carbonate and kaolin 15-
A polymer latex having 30% by weight and a glass transition temperature (T _g ) in the range of 10 ° C. or more is used in an amount of 3 to 100% by weight of the pigment.
A process for producing a matte coated paper, which comprises coating a base paper with a coating composition containing 25% by weight.

Hereinafter, the present invention will be described in detail. The problem of the transfer of printing ink to the white paper during the bookbinding process is that the white paper, which occurs when the printing part comes into contact with the white paper, improves the property of scraping the printing ink and suppresses the absorption of the ink vehicle during printing. Then, it can be considered that such a problem can be solved by preventing a decrease in the coating strength of the printing ink.

[0011] Generally, matte coated paper is coated with a coating composition containing a higher amount of a coarser pigment than normal glossy coated paper in order to suppress the glossiness of white paper. Since it is commercialized or commercialized by performing a light calendering process, there is a problem that the pigment orientation on the surface of the coated paper is inferior and that white paper easily takes ink.

The present inventors have conducted intensive studies in order to solve such a problem. As a result, 70-85% by weight of heavy calcium carbonate having an average particle diameter of 0.6-1.6 μm and 15-30% by weight of kaolin
And a polymer latex having a glass transition temperature (T _g ) of 10 ° C. or more in an amount of 3 to 25% by weight based on 100% by weight of the pigment.
By coating and drying the contained coating composition on the base paper, it was found that a very ideal matte coated paper having particularly low blank gloss and no problem of transfer of the printing ink to the blank portion was obtained. Things.

The reason why the problem of the transfer of the printing ink to the white paper portion has been solved is that a polymer latex having a Tg in the range of 10 ° C. or more is used. Generally, in the production of matte coated paper, a polymer latex having a Tg lower than 10 ° C. is used. When a polymer latex having a Tg lower than 10 ° C. is used, the latex itself has large deformability, and the latex film shrinks during drying.
Accompanying this, the orientation of the pigment during the drying step is disturbed, so that the gloss of the white paper is suppressed to a low level. However, for this reason, it is considered that the blank paper easily scrapes the ink on the printing surface. On the other hand, when a polymer latex having a Tg of 10 ° C. or higher was used, since the deformability was small, the shrinkage of the latex film during drying was small, and as a result, the orientation of the pigment was maintained to some extent. Since the coating layer is formed as it is, it is considered that the scraping of the ink on the printing surface by the white paper was reduced.

When such a latex having low deformability is used, there is a concern that the glossiness of white paper becomes too high due to the excellent orientation of the pigment. It was found that a high calcium content could solve the problem. If the amount is less than 70% by weight, the glossiness of the white paper is significantly increased. Moreover, even with a latex high T _g exceeds 85 wt%, the orientation of the ground calcium carbonate itself is poor, it is impossible to solve the problem of printing ink is transferred to the white paper.

The average particle size of the heavy calcium carbonate used in the present invention must be in the range of 0.6 to 1.6 μm. If the average particle size is less than 0.6 μm, the gloss of white paper significantly increases, which is not preferable. Further, it was recognized that when the average particle diameter exceeded 1.6 μm, the smoothness was remarkably reduced, and the print gloss was lowered due to the reduced ink acceptability.

The adhesive used in the present invention includes various copolymers such as styrene / butadiene, styrene / acrylic, ethylene / vinyl acetate, butadiene / methyl methacrylate, and vinyl acetate / butyl acrylate, and polyvinyl alcohol. , Maleic anhydride copolymers, synthetic adhesives such as acrylic acid / methyl methacrylate copolymers, oxidized starch, esterified starch, enzyme-modified starch and cold-water-soluble starch obtained by flash-drying them, casein, soybean Commonly known adhesives such as natural adhesives such as proteins can be used. In the present invention, one or more of these adhesives generally comprises a pigment 1
It is blended at a ratio of 3 to 50% by weight to 00% by weight,
According to the study by the present inventors, in particular, clear that the effect of the present invention can be obtained remarkably when used in a specific ratio mentioned polymer latex T _g is in the range of more than 10 ° C. below became. The proportion of such T _g is 10 ° C. or more polymer latex is less than 3% by weight with respect to 100 wt% pigment, less improvement to the problem of printing ink is transferred to the white paper, also 25 wt% ultra formulation As a result, problems such as too slow drying of the ink occur. Therefore, the polymer latex used in the present invention is 3% based on 100% by weight of the pigment.
It is desirably used in a range of 2525% by weight, more preferably 5-20% by weight.

[0017] Examples a T _g of more than 10 ° C. polymer latex used in the present invention, as a component, butadiene,
10 to 30% by weight of a conjugated diene such as isoprene and chloroprene; 2 to 20% by weight of an ethylenically unsaturated carboxylic acid such as methacrylic acid, acrylic acid, maleic acid, fumaric acid, crotonic acid and itaconic acid; Aromatic vinyl compounds such as styrene, α-methylstyrene, divinylbenzene, etc. copolymerizable with the unsaturated unsaturated carboxylic acid, and ethylenically unsaturated carboxylic acid ester acrylamide such as methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate And the like.

In preparing the coating composition used in the present invention, a dispersant, a thickener,
Various auxiliaries, such as a water retention agent, an antifoaming agent, a waterproofing agent, and a coloring agent, which are blended in a general composition for coated paper, are appropriately used.

The coating composition thus prepared can be used in the production of general coated paper such as blade coater, air knife coater, roll coater, curtain coater, champlex coater, bar coater, gravure coater, size press coater and the like. One side or both sides are coated on base paper by an on-machine or off-machine coater provided with a coating device. The solid content concentration of the coating composition at that time is generally 40
Although it is about 70% by weight, the range of 45 to 65% by weight is preferable in consideration of operability. As the base paper, a paper-based or board-based base paper having a basis weight of 30 to 400 g / m ² used for general printing coated paper is used. The coating amount of the coating composition on the base paper is 1 on a dry weight basis on both sides.
Although 0~50g / ^{m 2} about the coating is to be, and most preferably is adjusted from the face of the blank quality coated paper obtained in the range of 15 to 35 g / ^{m 2.}

As described above, the present inventors have found that the average particle diameter is 0.6 to
70 to 85% by weight of heavy calcium carbonate of 1.6 μm, 15 to 30% by weight of kaolin, and a polymer latex having a glass transition temperature (T _g ) of 10 ° C. or more in a range of 3 to 25% with respect to 100% by weight of pigment. By coating and drying the coating composition containing wt% on the base paper, it was recognized that a matte coated paper having particularly low glossiness of the white paper and causing no problem of transfer of the printing ink to the white paper portion was obtained.

[0021]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited by these examples. In the examples, parts and% indicate parts by weight and% by weight, respectively.

(Examples 1 to 4) (Comparative Examples 1 to 5) Kaolin [manufactured by Engelhard Co., Ltd., trade name: Ultra White 90] and heavy calcium carbonate [manufactured by Sankyo Flour Milling Co., Ltd. Product name: Escalon # 1500 (average particle size 1.7 μm), Product name: Escalon # 2200
(Average particle diameter: 0.9 μm) or a product name: TANKAL NCC-α-90 (manufactured by YOTAI Corporation) (average particle diameter: 0.5 μm)
m)], 0.2 parts of sodium polyacrylate was added as a dispersant to 100 parts of the mixed pigment, and the mixture was dispersed in water using a Cowles disperser to prepare a pigment dispersion having a solid content of 65%. 5 parts of esterified starch as an adhesive and the polymer latex shown in the table [L-1538 (Tg: 20 ° C.) manufactured by Asahi Kasei Kogyo Co., Ltd.) or L
−1503 (Tg: 0 ° C.)] and a solid concentration of 60
% Of the coating composition was obtained. This was coated with a blade coater so that the coating amount was 30 g / m ² on both sides, and dried to obtain a coated paper. The evaluation results of each coated paper were as shown in the table.

<Quality Evaluation Method> The glossiness of white paper, gloss after printing, surface smoothness, and abrasion resistance in Examples and Comparative Examples are values determined as follows.

White paper gloss: According to JIS-P8142 method
The gloss was measured at 75 ° using a gloss meter manufactured by Murakami Color Research Laboratory.

Gloss after printing: Using a RI-II type printing tester, printing was performed using 0.35 cc of Sakata Inks offset printing ink (trade name: Diatone GSL Red) (TV = 12). The 75 ° gloss was measured using a gloss meter manufactured by Technical Research Institute.

Smoothness: Measured with an Oken type smoothness meter.

Abrasion resistance: Printing was performed using 0.35 cc of Toyo Ink Offset Printing Ink (trade name: TK Mark Five New Ink M Type) using an RI-II type printing tester, and left overnight for a day, followed by Toyo Seiki Seisakusho Contact the printed test paper with a blank paper using a Southerland Lab Tester made of
Then, reciprocating friction was performed 20 times at a speed of 43 times / minute, and the density of the ink transferred from the printed paper to the white paper was visually evaluated in four steps. ：: Almost no transfer of ink ○: Slight transfer of ink △: Transfer of ink a lot ×: Transfer of ink very much

[0028]

[Table 1]

[0029]

As is clear from the table, all of Examples 1 to 4 have low white paper gloss and excellent rub resistance. On the other hand, Comparative Examples 1, 3, and 4 are inferior in friction resistance, and Comparative Examples 3, 4 are inferior in surface smoothness. In Comparative Examples 2 and 5, the glossiness of blank paper was increased. As described above, according to the method of the present invention, it has become possible to produce an excellent coated paper free from the problem that the ink printed in the bookbinding step or the like is transferred to the white paper portion while maintaining low white paper gloss.

────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Sachi Sakamoto 2-8-1 Iida-cho, Iwakuni-shi, Yamaguchi Prefecture Sanyo Kokusaku Pulp Co., Ltd. Production Research Laboratory (58) Field surveyed (Int. Cl. ⁶ , DB name) ) D21H 19/38-19/44

Claims (1)

(57) [Claims] 1. The pigment component has an average particle size of 0.6 to 1.
70-85% by weight of 6 μm heavy calcium carbonate and kaolin
15-30% by weight and a glass transition temperature (T
_g ) a polymer latex having a temperature of at least 10 ° C.
A process for producing a matte coated paper, characterized by coating a base paper with a coating composition containing 3 to 25% by weight based on 00% by weight.