JPS5953956B2 - Manufacturing method of matte coated paper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing matte coated paper, and in particular to a method for producing matte coated paper which has low white paper gloss but high ink gloss after printing and has good ink receptivity. It is something.

Matte coated paper gives an elegant and calm image compared to highly glossy coated paper, so it is one of the important grades of coated paper for everything from monochrome prints such as text paper to various multicolor prints. It is commonly used as.

However, in order to reduce the gloss of the white paper, such matte coated paper is coated with a coating liquid containing a relatively coarser amount of pigment than that used in ordinary coated printing paper, and moreover, Calender treatment for smoothing is either very light or not performed at all, resulting in poor ink receptivity and poor ink smoothness, resulting in low ink gloss after printing. In order to improve these drawbacks, for example, Japanese Patent Publication No. 47-85 proposes a method of treating coated paper with a calender consisting of a hard roughening roll and an elastic roll made of plastic.

However, even if such a calender is used, if the surface roughness of the roughening roll is made finer to improve smoothness, the white paper gloss will increase significantly, and conversely, if the surface roughness of the roughening roll is made rougher, At present, sufficient smoothness cannot be obtained, resulting in poor ink receptivity and ink smoothness, and only matte coated paper with low ink gloss after printing can be obtained. In view of the current situation, the present inventors conducted intensive research on the composition of the coating liquid for matte coated paper and the roughening treatment conditions. The present invention was achieved by focusing on the effective use of the excellent properties of Sachin White, a pigment that is not used in paper coverings, through a specific surface roughening treatment.

The purpose of the present invention is to improve the drawbacks of the prior art and to comply with JISP-8 standards.
The object of the present invention is to provide a method for producing a matte coated paper which has a low white paper gloss of 10 to 40% as measured based on 142, but has a high ink gloss after printing and has excellent ink receptivity.

The object of the present invention is to coat a base paper with a coating liquid containing (a) a pigment for coated paper containing 3 to 25% by weight of Sachitsubo Wide and (b) an adhesive and drying it. cover paper, J
Surface roughness (Rmax) defined by ISBO65l is 1
．． This is achieved by processing with a hard roughening roll having a roughness of 2 to 20 microns.

Sachin white used in the present invention is generally known as calcium sulfoaluminate, and is an acicular or plate-like synthetic pigment obtained by reacting milk of lime with sulfuric acid, potassium alum, etc.
It also includes those containing one or more compounds such as calcium chloride, silicon, and zinc.

Coated paper containing Sachin White in its coating layer can easily be given a high white gloss by applying a calender, so Sachin White is usually not used as a pigment for coated papers with a high white gloss. used, but not for matte coated paper. In the present invention, such Sachin White is used in combination with other ordinary pigments for coated paper in a specific ratio, and the coated paper obtained is subjected to surface roughening treatment under specific conditions. It improves whiteness, smoothness, ink gloss after printing, and ink receptivity without imparting a high degree of white gloss to paper.

However, when the proportion of Sachin White is less than 3% by weight of the total pigment, it is insufficient in improving the ink gloss and ink receptivity of coated paper;
If it exceeds 3 to 25% by weight, preferably 5 to 25% by weight of the total pigment, the white paper gloss of the coated paper obtained even with the special surface roughening treatment method of the present invention will be 40% or more. 15
It accounts for % by weight. It is mixed in the same ratio. Pigments for coated paper used in combination with Sachin White in the present invention include, for example, kaolin, clay, calcium carbonate, titanium oxide, aluminum hydroxide, zinc oxide, barium sulfate, calcium sulfate, calcium sulfite, talc, silica,
Examples include activated clay, acid clay, silicon clay, lake, and plastic pigment.

The adhesive used in the present invention includes casein,
Modified starches such as soybean protein, yeast protein, starch, oxidized starch, t-ester starch, ether starch, cationic starch, enzyme-modified starch, natural adhesives such as cellulose derivatives, styrene-butadiene copolymers, methyl methacrylate, etc.
Conjugated diene polymer latex such as butadiene copolymer, acrylic polymer latex such as acrylic acid ester, methacrylic acid ester polymer or copolymer, vinyl acetate polymer latex such as ethylene/vinyl acetate copolymer and synthetic adhesives such as polyvinyl alcohol.

In the present invention, one or more of these adhesives is generally blended at a ratio of 3 to 30 parts by weight per 100 parts by weight of the pigment, but according to studies by the present inventors, the minimum film forming temperature is particularly high. It has become clear that the effects of the present invention can be significantly obtained when a polymer latex having a temperature of 20° C. or higher is used in a specific ratio. That is, coated paper using polymer latex as an adhesive generally gives prints with high ink gloss when printed, but on the other hand, the gloss of the white paper can easily increase with one coat of calender, so it is difficult to coat with a matte coating. Even with the special roughening treatment method of the present invention described below, paper still requires careful temperature control of the roughening roll and the incorporation of relatively coarse pigments into the paint. Naturally, 2
It is clear that when a specific ratio of polymer latex having a minimum film-forming temperature of 0°C or higher is used, the ink gloss and ink receptivity after printing can be efficiently improved without increasing the white paper gloss. Summer. If the proportion of the polymer latex having a minimum film-forming temperature of 20° C. or higher is less than 3 parts by weight based on 100 parts by weight of pigment, the effect of improving ink gloss and ink receptivity after printing will be small; 3 to 25, as white paper tends to become glossy if it exceeds 3 to 25%.
It is desirable to use it in parts by weight, more preferably in the range of 5 to 15 parts by weight. A polymer latex having a minimum film forming temperature of 20° C. or higher includes 5 to 30% by weight of conjugated diene I, and 2 to 15% by weight of ethylene containing methacrylic acid that may constitute at least 2% by weight of the total monomers. An example is a copolymer latex consisting of an ethylenically unsaturated monomer copolymerizable with the ethylenically unsaturated carboxylic acid and i and Ii forming the remainder Iiii.

The above-mentioned conjugated dienes as one component include butadiene, isoprene, chloroprene, etc., and the ethylenically unsaturated carboxylic acids other than methacrylic acid as component Ii include monomers such as acrylic acid, crotonic acid, itaconic acid, fumaric acid, and maleic acid. Alternatively, the dicarboxylic acid is further used as the ethylenically unsaturated monomer of component III, such as aromatic vinyl compounds such as styrene, α-methylstyrene, and divinylbenzene, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, and ethyl methacrylate. Examples include ethylenically unsaturated carboxylic acid esters such as acrylamide and vinyl cyanide monomers.

In addition, when preparing the coating liquid used in the present invention, various auxiliary agents such as dispersants, flow modifiers, antifoaming agents, colorants, etc., which are usually added to pigments for coated paper, may be appropriately added as necessary. Of course. In the present invention, as described above, (
A coating liquid containing a) a pigment for coated paper containing 3 to 25% by weight of satin white and (b) an adhesive is applied to one or both sides of the base paper and dried. There are no particular limitations on the amount, coating method, and drying method, and approximately 6 to 40 g per side can be applied according to the general coated paper manufacturing method.
4 is coated in a single layer or in multiple layers using a coating machine such as a blade coater, an air knife coater, a bar coater, a chain coater, a roll coater, or a size press coater to obtain a coating amount of M2. 3
Dry to ~9% paper moisture and roll.

Among the above-mentioned various coating machines, the blade coater is more preferably used because it provides matte coated paper that produces particularly elegant printed matter. In the present invention, the coated paper thus obtained is treated with a hard roughening roll having a specific surface roughness, and the surface roughness of the roughening roll is Rmax defined by JISBO65l. If it is finer than 1.2μ, the white paper gloss of the coated paper after treatment will easily exceed 40%, while if it is coarser than 20μ, the smoothness of the paper surface will decrease and the ink gloss after printing will decrease. 1.2-2
It is necessary to process with a roughening roll having a surface roughness in the range of 0μ, more preferably between 4 and 12μ.

Generally, the treatment of coated paper with such hard roughening rolls is as follows:
This is done by passing the coated paper through a nip formed by a hard roughened roll and an elastic roll made of paper, cotton, asbestos, wool, plastic, etc.
In the present invention, the surface roughening treatment is also carried out by passing the above-mentioned coated paper through a nip formed by a hard roughening roll and an elastic roll having the above-mentioned specific surface roughness.

In this case, a preferred embodiment is a calender as described in Japanese Patent Publication No. 47-85, in which two hard surface roughening rolls having the above-mentioned specific surface roughness are arranged on both sides of two elastic rolls made of plastic. It is applied to the present invention as follows. In order to obtain the desired effects of the present invention, the mouth temperature of the roughening roll when treating coated paper with the hard roughening roll is also an important factor.

Generally, coated paper for printing is subjected to calendering treatment at a roll temperature of 60°C or higher, but the matte coated paper of the present invention is subjected to a calendering process at a roll temperature of 55°C or lower, more preferably 4°C.
It is desirable to process at a roll temperature of 5°C or less. For this reason, adjustments such as installing a roll cooling device are made as necessary. In addition, the pressurizing conditions are adjusted as appropriate depending on the coating liquid formulation of the coated paper, the surface roughness of the roughening roll, the roll temperature, and the desired quality setting of the matte coated paper, but in general, roughening The density of coated paper after treatment is 0.8-1.25g/C
It is desirable to adjust it so that it becomes nl3.

The material of the hard roughened roll used in the present invention is not particularly limited as long as it has a specific surface roughness as described above, but generally metal rolls such as alloy tilt rolls and steel rolls are processed by sandblasting or corrosion. A roll whose surface has been roughened by a method such as a method is preferably used, and a roll which has been subjected to a chrome plating treatment can also be used if necessary.
The thus obtained matte coated paper of the present invention effectively utilizes the excellent properties of Sachin White through a specific surface roughening treatment, so while the white paper gloss is sufficiently low, the ink gloss after printing is low. It is expensive and has excellent ink receptivity, and can provide printed matter that is elegant and has a good appearance.

Examples will be described below to further specifically explain the present invention, but the present invention is of course not limited to these.

Note that unless otherwise specified, "parts" and "%" indicate "parts by weight" and "% by weight," respectively. Examples 1 to 5,
Comparative Examples 1 and 2 A coating liquid containing pigments for coated paper and adhesive as main components in the proportions shown in Table 1 was applied to both sides of a 64 g/M2 base paper.
The paper was coated with a blade coater at a coater speed of 300 m/min so that the coating amount per side was 20 g/M2 in terms of dry weight, and the paper was dried and wound up so that the paper moisture content was 7%.

The obtained coated paper was transferred to a 4-stage super calender equipped with two hard roughening rolls with a surface roughness (Rmax) of 8μ at a temperature of 30°C of the hard roughening rolls. A matte coated paper was obtained by passing the paper so that the density was 1.18.

The quality of the obtained matte coated paper was evaluated by the following method, and the results are also listed in Table 1.

(1) White paper gloss: Measured at an angle of 75° according to JISP-8142.

(2) Blank paper smoothness: Measured using a smoothness meter (Smoothta-1) manufactured by Toei Denshi Co., Ltd.

The unit is (2), and the smaller the value, the better the smoothness. (3) Ink gloss and ink receptivity: The ink gloss of printed matter printed at a speed of 5000 sheets/minute with a Roland offset printing machine was visually judged.

The evaluation criteria were the following six levels. ◎・・・◎″・・・O
・・・○″・・・△・・・× (Excellent) (
As is clear from the results in Table 1, the matte coated papers obtained in each example of the present invention all had white paper gloss in the range of 10 to 40%, and white paper smoothness was also good. At 2,
The ink gloss after printing was high and the ink receptivity was good, resulting in an elegant and attractive printed matter.

Examples 6 and 7, Comparative Examples 3 and 4 Matt coated paper was prepared in the same manner as in Example 2, except that a hard roughening roll having a surface roughness (Rmax) of 2 as shown in Table 1 was used. was manufactured and subjected to quality evaluation tests, and the results are also listed in Table 1.

As is clear from the results in Table 1, in Comparative Example 3, the white paper gloss was extremely high and fell outside the range of matte coated paper. Furthermore, in Comparative Example 4, although the white paper gloss was low, the white paper smoothness was extremely poor, and the ink gloss and ink receptivity after printing were also poor. Example 8 A matte coated paper was produced in the same manner as in Example 2 except that an air knife coater was used instead of the blade coater, and a quality evaluation test was conducted. The results are shown in Table 1.

Comparative Example 5 A coated paper was obtained in the same manner as in Example 2, except that a coating liquid formulated in the proportions shown in Table 1 was coated using an air knife coater.

The obtained coated paper was passed through a four-stage super calender equipped with two tilt rolls each having a plain surface at a temperature of 60° C. so that the density of the paper after treatment was 1.18. A matte coated paper was obtained. When the quality of the obtained matte coated paper was evaluated in the same manner, only printed matter was obtained which had extremely poor white paper smoothness and extremely poor ink gloss and ink receptivity after printing.

Claims (1)

[Scope of Claims] 1. Obtained by coating a base paper with a coating liquid containing (a) a pigment for coated paper containing 3 to 25% by weight of satin white and (b) an adhesive and drying it. Coated paper, JISB_0_6_5
Surface roughness (Rmax) defined by _1 is 1.2 to 20
1. A method for producing matte coated paper, characterized in that the process is carried out using a hard surface roughening roll. 2. The matte according to claim 1, which contains 3 to 25 parts by weight of a polymer latex having a minimum film-forming temperature of 20° C. or more as an adhesive based on 100 parts by weight of a pigment for coated paper. Method of manufacturing coated paper.