JPH0643675B2 - Method for producing matte coated paper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a method for producing a matte coated paper, and in particular, a matte having a low white paper gloss but a high ink gloss after printing and good printability. The present invention relates to a method for manufacturing coated paper.

(B) Prior Art and Problems Conventionally, matte coated paper is used in a wide area because it gives a feeling of refinement compared to coated paper having low gloss and high gloss of white paper. However, in order to reduce the white paper gloss, a coating solution containing a large amount of a pigment that is coarser than the pigments used for ordinary coated paper is applied to the base paper. However, it may not be processed at all. Therefore, the coated paper is inferior in ink acceptability and ink gloss after printing.

Calcium carbonate, which has been widely used for matte coated paper, has less white paper gloss than kaolin.
It also has the property that printing gloss is less likely to appear.

On the other hand, since the mica has a scale-like shape, the viscosity of the dispersion is high, and it is difficult to make it into a high concentration and high content.

However, due to its flat shape, it is excellent in smoothness, ink gloss after printing, and hiding power.

(C) Object of the invention In view of the present situation, the present inventors obtain a matte coated paper having high ink gloss after printing even if white paper gloss is suppressed by compensating for the defects of calcium carbonate and mica. In order to obtain a matte coated paper with high ink gloss, which complements each other's defects by combining calcium carbonate and mica with specific particle sizes, and which does not easily produce white paper gloss. The present invention has been found to be possible.

(D) Means for Solving the Problems That is, the present invention relates to a method for producing a matte coated paper, which comprises coating a base paper with a coating solution containing at least calcium carbonate and mica. Average particle size 0.4μ ~ 2μ
Mica is in the range of 0.5 μm to 2 μm, and the coating composition containing 20% by weight or more of the total amount of the calcium carbonate and the mica as a pigment component in the pigment composition is applied to the base paper.・ Dry, white paper gloss (JISP8142 method) is 25%
A method for producing a matte-coated paper, characterized by performing a smoothing treatment as described below.

In the present invention, a mixture of calcium carbonate having an average particle diameter of 0.4 μ to 2 μ and mica having an average particle diameter of 0.5 μ to 2 μ in a specific range is used as described above, but the average particle diameter of calcium carbonate is 2 μ. If it exceeds, it is difficult to obtain sufficient ink gloss, hiding power, and smoothness after printing. Not preferable. When the average particle size of mica exceeds 2 μ, smoothness is poor and ink gloss is also low. If it is less than 0.5 μ, the coating layer strength is lowered and the gloss of the heavy color ink is lowered.

If the mixing ratio of calcium carbonate and mica having such a specific average particle diameter to the total pigment is less than 20% by weight, the effect of mixing mica and calcium carbonate is insufficient.
The coated paper has a high white paper gloss, and the ink gloss after printing is not improved, so that it is insufficient as a matte coated paper. Therefore, the ratio of the above calcium carbonate and mica to the total pigment is 20% by weight or more, preferably 30% by weight.
The composition will occupy the above.

Further, from the viewpoint of the effect of mixing mica and calcium carbonate, the content of mica needs to be 5% by weight with respect to calcium carbonate, and the upper limit value is 90% by weight in consideration of the liquidity of the final coating liquid. Below, preferably 70% by weight or less is practical.

Further, as a method of obtaining calcium carbonate and mica having such a specific average particle diameter, mica and calcium carbonate are mixed and a high-concentration mixed slurry can be obtained by a sand gliding treatment, and further, trapped in mica. It is possible to completely remove the air present and prevent the occurrence of uncoated spots on the coating machine.

Therefore, the most preferable operation is possible when using calcium carbonate and mica which are most preferably sand-milled.

As the mica component, it is preferable to use sericite, and it is actually effective to use sericite-containing kaolin, Sieglite, for increasing the concentration and decreasing the viscosity of the coating liquid.

Pigments for coated paper other than calcium carbonate and mica used in the present invention include kaolin, clay, satin white, titanium oxide, aluminum hydroxide, zinc oxide, barium sulfate, calcium sulfate, silica, activated clay, talc, and silicon earth. , Rakes, plastic pigments and the like.

As the adhesive used in the present invention, various copolymers such as styrene / butadiene type, styrene / acrylic type, vinyl acetate / acrylic type, ethylene / vinyl acetate type, butadiene / methyl methacrylic type, vinyl acetate / butyl acrylate type, etc. And polyvinyl alcohol, maleic anhydride / styrene copolymer,
Synthetic adhesives such as isobutene / maleic anhydride copolymer, acrylic acid / methylmethacrylate copolymer, oxidized starch, etherified starch, esterified starch, enzyme-modified starch and cold water soluble obtained by flash-drying them Commonly known adhesives such as starch, casein, soybean protein and other natural adhesives can be used. If necessary, various auxiliaries such as dispersants, thickeners, water retention agents, defoaming agents, water resistant agents, and coloring agents that are added to ordinary coating liquids for coated paper can be appropriately used.

The method of applying the coating composition according to the present invention to the base paper is not particularly limited, and various ordinary coating devices such as an air knife coater, a roll coater, various blade coaters and a short dwell coater can be used.

Thus, the coated paper which has been coated with the coating composition and dried is finished through a finishing device such as a super calender and a gloss calender.
Method) to be 25% or less.

The matte coated paper of the present invention thus obtained can provide a printed matter having good smoothness, low white paper gloss, an elegant appearance, and excellent ink gloss.

(E) Action The fine calcium carbonate used in the present invention alone is conventionally
Compared with calcium carbonate used for matte coated paper, white paper gloss is more likely to occur and heavy color ink gloss is reduced, but smoothness is more likely to occur. Further, the fine mica used in the present invention alone has low white paper gloss, smoothness is easily obtained, and ink gloss is good, but the viscosity of the dispersion becomes very high, and it is recommended to make a high concentration and a high content. It has the drawback of being very difficult.

For the above reasons, fine calcium carbonate and mica as in the present invention have not been used in matte coated paper.

However, by using a mixture of finely divided calcium carbonate and mica of the present invention, the disadvantages of the calcium carbonate for matte coated papers are that the glossiness of white paper and the glossiness of heavy color ink are difficult to appear. Are canceled by fine mica,
In addition, it is possible to obtain a good matte coated paper by solving the difficulty of increasing the concentration of the coating solution and the difficulty of using a high content of fine mica, which are defects of fine mica, by the shape of calcium carbonate. .

(F) Examples The effects of the present invention will be described below with reference to Examples, but the present invention is not limited thereto.

In the examples, "parts" and "%" indicate "parts by weight" and "% by weight", respectively.

Table 1 summarizes the average particle size and composition of the pigment slurries used in Examples and Comparative Examples and symbols.

The average particle size referred to in this patent is the result of measurement using a light transmission type particle size distribution measuring device (SHC5000 manufactured by Seishin Enterprise Co., Ltd.). Regarding the particle size of the mixed slurry, the particle size distribution before and after dissolving calcium carbonate with an acid was measured to obtain the average particle size of various pigments.

Examples 1-10, Comparative Examples 1-6 25 parts of sericite having an average particle diameter of 2.6μ, average particle diameter of 15μ
75 parts by weight of heavy calcium carbonate, 0.6 parts by weight of sodium polyacrylate, and a slurry having a solid content of 66% were prepared and treated with a sand glider to obtain a pigment slurry A.
Also, 40 parts of sericite having an average particle diameter of 2.6μ, an average particle diameter of 1
A slurry having 60 parts of 5 μ of heavy calcium carbonate, 0.6 part of sodium polyacrylate and a solid content of 64% was prepared and passed through a sand glider to obtain a pigment slurry B.

Next, 25 parts of Sieglite having an average particle size of 2.6μ, 75 parts of ground calcium carbonate having an average particle size of 15μ, 0.6 part of sodium polyacrylate, and a slurry having a solid content concentration of 68% were prepared, and a sand glider was used. Pass through to obtain Pigment Slurry C.

Subsequently, 40 parts of Sieglite having an average particle size of 2.6μ, 60 parts of calcium carbonate having an average particle size of 15μ, 0.6 part of sodium polyacrylate, and a slurry having a solid content concentration of 66% were prepared, and a sand glider was used. It was passed through to obtain a pigment slurry D.

Other pigment slurries to be used were pigments having an average particle size as shown in Table 1, which were dispersed and adjusted with sodium polyacrylate.

The above pigments were mixed in such a proportion that the solid content was as shown in Table 2.

Further, the styrene-butadiene latex and the phosphoric acid esterified starch were mixed by stirring in the proportions shown in Table 2 to obtain a coating liquid of 61%.

Both sides of this coating solution composition were coated on 60 g / m ² coated base paper so that the coating amount was 13 g / m ² on one side in terms of solid content,
After drying and humidity control, super calendar processing was performed. The quality of each coated paper was compared, and the results are shown in Table 2. The measurement conditions are as follows.

(1) Smoothness: Smoother smoothness tester (Toei Denshi K
The value according to K). (MmHg) (2) Glossiness of blank paper: Angle of 75 according to JIS P8142
It was measured at °. (%) (3) Print glossiness: printed with a Roland offset printing machine and printed in magenta single color and magenta, shea, yellow,
The print gloss of the three-color overlapping portion was measured at an angle of 60 degrees. (%) (4) Coating layer strength: The surface strength of the coated paper was determined using an RI printing suitability tester (Ming Seisakusho).

A value of 5 is a good state, and a value of 3 or less causes a problem.

As shown in Table 2, in the examples of the present invention, even if the surface treatment is performed under the condition that the glossiness of the blank sheet is 25% or less, the smoothness of the blank sheet is good, the ink gloss after printing is high, and the elegant printing is good. I got a print.

(G) Effect of the Invention The present invention provides a white paper with less glossiness and smoothness by applying a coating solution containing 20% or more of mica having a specific average particle size and calcium carbonate as a pigment component of coated paper. Good of
It is possible to obtain a matt coated paper that easily gives an ink gloss.

Claims (4)

[Claims] 1. A base composition comprising a coating composition containing 20% by weight or more of the total amount of calcium carbonate and mica satisfying the following conditions [I] and [II] as a pigment component in the pigment composition. Coated and dried, white paper gloss (JISP8142 method) is 25
%, A smoothing treatment is carried out so as to be not more than%. Calcium carbonate: 0.4 μ ≦ average particle size ≦ 2 μ [I] Mica: 0.5 μ ≦ average particle size ≦ 2 μ [II] 2. The method for producing matte coated paper according to claim 1, wherein the mixing ratio of the calcium carbonate and mica is 5 to 90% by weight of mica with respect to calcium carbonate. 3. The method for producing a matte coated paper according to claim 1 or 2, wherein the mica is sericite or sieglite. 4. The method for producing a matt coated paper according to claim 1, 2 or 3, wherein the calcium carbonate and mica are obtained as a mixed slurry by a sand mill treatment.