JP3064563B2 - Method for producing double-sided matte coated paper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for producing a double-sided matte coated paper. More specifically, the present invention relates to a method for producing a double-side matt coated paper having excellent surface properties on both sides of white paper and after printing.

[0002]

2. Description of the Related Art Matte coated papers are used widely in the fields of monochromatic printing to high-grade multicolor printing, since they provide an elegant and calm printing effect in printing, and the demand is growing further.

Conventional matte coated paper, paint coated on the base paper, which had been manufactured and finished by performing lightly treatment with metal rolls to suppress low sheet gloss after drying, according to this method There is a disadvantage that the surface properties of the coated paper are inferior.

[0004] On the other hand, a method of treating a coated paper containing satin white with a hard roughening roll having a specific surface roughness to obtain low blank gloss and high print gloss (Japanese Patent Publication No. 59-1984).
No. 53956) has been proposed. Furthermore, the surface of the coated paper is smoothed and densified in advance with a calender consisting of a metal roll and an elastic roll, and then treated with a roughening roll having a specific roughness to obtain a low white paper gloss and ink smoothness. Good
For obtaining a matte coated paper (Japanese Patent Application Laid-Open No. 1-260094)
Gazette) has also been proposed. Or even a blank paper like this
In order to improve the matte tone of
Was applied and dried, and the coated paper obtained was passed through a calender having a combination of a roughening roll and an elastic roll to treat the coated surface (Japanese Patent Application No. 2-226711).
These methods combine the roughness of the roughening roll with the number of contacts of the coated paper to the roughening and elastic rolls to improve the smoothness of the matte coated paper, thereby improving the white paper surface properties and after printing. It is intended to improve the surface properties of the steel, and a certain effect has been obtained.

However, according to these methods, the degree of Shore D hardness of the elastic roll is inferior in the smoothness of the surface which is finally in contact with the roughening roll, and the smoothness of both surfaces cannot be simultaneously and uniformly improved. was there.

On the other hand, as a method for improving the surface properties of a double-sided matte coated paper, both sides of the coated paper are separately treated with a roughening roll and then passed between elastic plastic rolls to improve the uniformity of both sides. An improved matte calendar has been proposed (Japanese Patent Publication No. 47-85). In this apparatus, when a matte coated paper is passed between two elastic rolls, the matte imparted by the roughening roll is partially pressed again, and the unevenness of the roll surface is reduced. The purpose of this device is to improve the appearance of irregular gloss (marble or mottled gloss). According to this apparatus, the matte applied to the coated paper has two smooth surfaces. It is not erased again by the elastic roll and is somewhat weakened, but the stabilization has a certain effect.

However, in this apparatus, the coated paper is pressed against the roughening roll only once, so
The surface to be pressed against has the disadvantage that the matte of the coated paper is much weaker than the surface to be pressed only once. For this reason, the surface of the roll which is twice pressed against the elastic roll is roughened slightly to cope with the problem. However, uniformity of the surface smoothness is still insufficient.

[0008]

In view of the above situation, the present inventors have conducted intensive studies on the processing conditions using a combination of a roughened roll and an elastic roll. In the number of times of contact with the roughening roll and in combination with the elastic roll, the matte of the coated paper is sufficiently applied, and at the end of the treatment, the matted coated paper is placed between the elastic rolls having a specific hardness. It has been found that by passing through, the disappearance of matting due to the elastic roll treatment after the matting treatment is reduced, and furthermore, it has been found that the surface is made uniform with a high level of smoothness on both sides, and the present invention has been completed.

Accordingly, an object of the present invention is to solve the drawbacks of the prior art, and in particular, to improve the smoothness of both sides of a double-sided mat coated paper, and to provide a double-sided gloss having excellent white paper surface properties and surface properties after printing. An object of the present invention is to provide a method for producing an erased coated paper.

[0010]

SUMMARY OF THE INVENTION The present invention relates to a method for producing a matte coated paper by applying a coating to a base paper and drying the coated paper obtained by pressing the coated paper against a roughening roll.
Surface roughness Rmax defined by 0601 is 8 to 25 μm
After at least two presses against the hardened surface roughening roll to perform a matting treatment, the mat is passed through a nip between elastic rolls having a Shore D hardness of 80 to 90 according to ASTM standard D-2240. Treat both sides of erased coated paper,
Two-dimensional surface roughness R of paper defined by IS B 0601
a is in the range of 0.02 to 0.15 μm.

The coating liquid pigments used in the present invention include kaolin, calcium carbonate, titanium oxide, aluminum hydroxide, satin white, zinc oxide, barium sulfate, calcium sulfate, calcium sulfite, talc, silica, activated clay, and diatomaceous earth. And pigments generally used in coatings for coated papers such as plastic pigments. Particularly preferred are pigments containing heavy calcium carbonate as a main component and appropriately selecting and combining these pigments.

Examples of the coating liquid adhesive used in the present invention include casein, soybean protein, yeast protein, starch, oxidized starch, esterified starch, etherified starch, cationized starch, modified starch such as enzyme-modified starch, and cellulose. Natural adhesives such as derivatives and styrene-butadiene copolymers,
Conjugated diene copolymer latex such as methyl methacrylate-butadiene copolymer, acrylic copolymer latex such as acrylate, methacrylate polymer or copolymer, ethylene-vinyl acetate copolymer Examples thereof include a vinyl acetate polymer latex and a synthetic adhesive such as polyvinyl alcohol. One or more of these adhesives are used, and 5 to 30 parts by weight per 100 parts by weight of the pigment is used.

In preparing the coating liquid used in the present invention, various auxiliaries, such as a dispersant, a flow modifier, an antifoaming agent, and a colorant, to be added to the coating liquid for ordinary coated paper are required. They are appropriately selected and blended according to the requirements.

The coating liquid prepared as described above is composed of wood pulp, and is coated on both sides of a base paper made by a known paper machine in a range of 10 to 35 g / m ² per one side, if desired. However, the coating method is not particularly limited, and is appropriately selected from blade coaters, air knife coaters, bar coaters, roll coaters, champlex coaters, and the like used in the production of general coated paper. It is coated in a single layer or multiple layers, dried to a water content of 3 to 8%, and wound up.

[0015] The coated paper thus obtained is JIS
The surface roughness Rmax defined by B0601 is 8 to 2
It is passed between a roughening roll and an elastic roll in the range of 5 μm by pressing and matting. The material of the hard surface roughening roll is not particularly limited, and a steel or alloy roll having a desired surface roughness imparted to the roll surface by a sandblasting method, a corrosion method, or the like and a chrome-plated roll thereof may be used. It is preferably used for the present invention. As the elastic roll used in combination with the roughening roll, a known elastic roll made of cotton, asbestos, wool, plastic, or the like is used.

In the present invention, the matte treatment of the coated paper by the roughening roll is performed at least twice on the front and back surfaces of the coated paper, and finally the coated paper has a Shore D hardness of 80 to 90 according to ASTM D-2240. It is passed between the nips of two elastic rolls in the area and pressed into contact. Surprisingly, when matting is performed at least twice with a roughening roll and finally with an elastic roll having the above-mentioned Shore hardness, the surface of the coated paper when matting is performed with the roughening roll is poor. It was found that the influence was mitigated by the elastic roll which comes in contact later, the smoothness of both surfaces was improved, and a uniform matte surface was obtained.

However, the surface roughness R of the roughening roll
If the max is less than 8 μm, a satisfactory matting effect cannot be obtained, and if the surface roughness Rmax exceeds 25 μm, the surface of the mat coated paper becomes noticeably rough, which is inconvenient in the present invention.

As the elastic roll to be passed at the end of finishing, a roll having a Shore D hardness of 80 to 90 according to ASTM standard D-2240 made of cotton, asbestos, plastic or the like is preferably used. If the Shore D hardness of the elastic roll is less than 80, it is too soft to improve the smoothness of the matte surface, and if it exceeds 90, the desired nip width cannot be obtained. It is not suitable for the present invention because smoothness cannot be imparted, the matte portion is partially erased, and mottle occurs in a part and lacks uniformity.

The Shore D hardness of the elastic roll used in combination with the roughening roll is not particularly limited, but it is convenient to use the same hardness as that of the elastic roll for passing as the end of finishing.

In the present invention, two or more roughening rolls are incorporated in a super calender having six or more stages, and the front and back surfaces of the coated paper are each at least twice, usually two to three times. Shore D hardness 8 after passing by pressure
It is necessary to be treated with an elastic roll having a hardness selected from the range of 0 to 90. If the treatment with the roughening roll is performed less than twice, the matting effect is significantly impaired due to the subsequent contact with the elastic roll.

The surface of the matte coated paper thus obtained has a roughness Ra defined by JIS B 0601 of 0.
If it is less than 0.02 μm, the matting effect will be lost, and if it exceeds 0.15 μm, the roughness will be noticeable and the smoothness will be insufficient, so that it is not suitable for the present invention.

In order to obtain the desired effect of the present invention, the coated paper must have a surface temperature of the hard roughening roll and the chilled roll of 5 or less.
The pressure welding treatment is performed at 5 ° C. or less, preferably 45 ° C. or less. Therefore, a roll cooling device using air cooling, water cooling or the like is installed as necessary.

The nip pressure conditions when the coated paper is pressed and passed are determined by a combination of the coating composition of the coated paper, the surface roughness of the roughening roll, the temperature of the roll, and the like. However, a pressure in the range of 100 to 300 kg / cm is appropriately selected and used.

According to the present invention, it is possible to provide a double-sided mat coated paper having extremely high smoothness of white paper, excellent surface properties of white paper by sensory evaluation and excellent surface properties after printing, and a method for producing the same.

[0025]

EXAMPLES The present invention will be described more specifically with reference to the following examples, but it should be understood that the present invention is not limited by these examples. In the following, parts and% all mean parts by weight and% by weight.

Example 1 40 parts of kaolin (manufactured by Engel Hard Minerals and Chemicals (EMC), trade name, Ultra White 90) as a pigment and 40 parts of heavy calcium carbonate (manufactured by the company, ground calcium carbonate) 60 having an average particle size of 4 μm Of the oxidized starch (manufactured by Oji Constarch Co., Ltd., trade name: Oji Ace A) and 12 parts of latex (manufactured by Asahi Kasei Corporation, trade name: L-1537), and further as a dispersant per pigment. 0.3% sodium polyacrylate,
As a lubricant, calcium stearate 0.5% and a fluorescent dye 0.2% are sequentially added and thoroughly mixed and dispersed.
The coating solution was prepared by adjusting the pH to alkaline using an aqueous ammonia solution.

This coating liquid is applied to both sides of a base paper having a basis weight of 80 g / m ^{2 made} of a hardwood bleached kraft pulp by a known paper machine using a 20 g / m ² blade coater (Mitsubishi Heavy Industries, Ltd.) per side. Then, it was dried by a known dryer to produce a coated paper having a paper moisture of 6%.

The coated paper is subjected to JIS as shown in FIG.
The surface roughness Rmax defined by B0601 is 15 μm
Temperature of 4 with a super calender equipped with two hard surface roughening rolls and five elastic rolls having a Shore D hardness of 88 °.
While pressing at 0 ° C. and a nip pressure of 200 kg / cm, the paper was passed through at a speed of 700 m / min with the back side of the paper (the wire side of the paper machine) facing up to produce a matte coated paper.

FIGS. 1 and 2 show a super calender in which one side of a coated paper is pressed against a roughening roll at least twice, and then both sides of the coated paper are pressed against an elastic roll. FIGS. 3 and 4 show a side view of a super calender showing a state in which paper is passed through. One side of a coated paper is pressed against a roughening roll at least twice, and then only one side of the coated paper is an elastic roll. FIG. 3 is a side view of the super calender showing a state in which coated paper is passed through a super calender pressed into contact with the surface of the super calender, wherein 1 is an elastic roll, 2 is a chilled roll, and 3 is a roughened roll. Reference numeral 4 denotes a paper roll, and reference numeral 5 denotes a coated paper.

The quality of the matte coated paper was evaluated by the following method. Quality evaluation method (1) Blank glossiness Measured at an angle of 75 degrees according to JIS P8142. (2) Two-dimensional surface roughness of blank paper The surface roughness was measured using a surface roughness measuring instrument (SE-3AK, manufactured by Kosaka Laboratories) and represented by center line average roughness. (3) White paper surface characteristics The matte coated paper was visually evaluated, and indicated by ○, □, △, ▲ in order from the best one. ○ □, □ △ and △ ▲ show the middle of each. (4) Surface properties after printing The matte coated paper was printed by Mitsubishi Diamond Printing Machine (manufactured by Mitsubishi Heavy Industries, Ltd.) and visually indicated by ○, □, △, ▲ in order from the best one. ○ □, □ △ and △ ▲ indicate the middle of each. (5) Smoothness of blank paper It was measured using an Oken type smoothness meter (manufactured by Asahi Seiko Co., Ltd.).

Example 2 A super calender shown in FIG. 2 in which the surface roughness of a roughening roll was 10 μm (all elastic rolls have Shore D hardness)
The matte coated paper was manufactured in the same manner as in Example 1 except that the paper was passed as shown in FIG. 2 and the quality was evaluated.

Example 3 40 parts of kaolin (Ultra White 90) as a pigment,
Heavy calcium carbonate with an average particle size of 2 μm (manufactured by our company) 50
Parts, using 10 parts of Satin White having an average particle size of 2 μm,
A matte coated paper was manufactured in the same manner as in Example 1 except that the Shore D hardness of the elastic roll of the super calender shown in FIG. 1 was changed to 84 °, and the quality was evaluated.

Example 4 A matte coated paper was produced in the same manner as in Example 3 except that the Shore D hardness of the elastic roll of the super calender shown in FIG. 1 was changed to 86 °, and the quality was evaluated.

Example 5 A matte coated paper was manufactured in the same manner as in Example 4 except that the surface roughness of the roughening roll of the super calender shown in FIG. 1 was changed to 23 μm, and the quality was evaluated. .

Comparative Example 1 A matte coated paper was manufactured in the same manner as in Example 1 except that the elastic roll had a Shore D hardness of 86 ° and the super calender shown in FIG. 4 was used to pass the paper as shown in FIG. And evaluated its quality.

Comparative Example 2 A matte coated paper was produced in the same manner as in Example 3 except that the paper was passed as shown in FIG. 3 using a super calender having a Shore D hardness of 86 ° of the elastic roll, and its quality was measured. Was evaluated.

Comparative Example 3 A matte coated paper was produced in the same manner as in Example 1 except that the Shore D hardness of the elastic roll of the super calender shown in FIG. 2 was changed to 78 °, and the quality was evaluated.

Comparative Example 4 A matte coated paper was manufactured in the same manner as in Example 2 except that the surface roughness of the roughening roll of the super calender shown in FIG. 2 was changed to 28 μm, and the quality was evaluated. .

Comparative Example 5 A matte coated paper was manufactured in the same manner as in Example 3 except that the Shore D hardness of the elastic roll of the super calender shown in FIG. 1 was changed to 92 °, and the quality was evaluated.

Comparative Example 6 A matte coated paper was manufactured in the same manner as in Example 5 except that the surface roughness of the roughening roll of the super calender shown in FIG. 1 was changed to 6 μm, and the quality was evaluated. .

Table 1 shows the results obtained in Examples 1 to 5, Table 2 shows the results obtained in Comparative Examples 1 and 2, and Table 3 shows the results obtained in Comparative Examples 3 to 6.

[0042]

[Table 1]

[0043]

[Table 2]

[0044]

[Table 3]

The matte coated paper according to the method of the present invention has different glossiness and smoothness of the matte coated paper before printing depending on the difference in the particle size of heavy calcium carbonate contained in the paint or the presence or absence of satin white. (Examples 1-2 and Examples 3-5 are compared), but the matte coated paper according to the present invention has uniformity and surface roughness on both sides, uniformity on both sides after printing, and printing. Table 1 shows that the surface finish is excellent.

On the other hand, when the matte coated paper leaves the super calender, only one side is pressed against the elastic roll, and the other side is pressed against the roughening roll (Comparative Examples 1 and 2). The surface roughness of the surface that does not contact the surface is high, the value of the smoothness is low, and the finished surface after printing can only be extremely poor.

Even if the matte coated paper is passed between the elastic rolls as the final finish, the shore D of the elastic rolls
If the hardness is low (Comparative Example 3), the effect of flattening the surface cannot be obtained, and the surface roughness of both surfaces of the coated paper is high and the smoothness is low.
In this case, if the Shore D hardness of the elastic roll is high (Comparative Example 5), the flattening effect is not obtained, the surface is roughened, and uneven gloss is generated, and as a result, the surface properties after printing are not excellent.

Furthermore, even if the hardness of the elastic roll of the super calender is appropriate, if the surface roughness of the roughened roll is small, the smoothness and glossiness become extremely high, and the matte feature is lost. If the surface roughness is too large, smoothness will be lost, and the surface of the matte coated paper obtained will be rough, and the surface properties after printing will be extremely poor.

[0049]

According to the method of the present invention, when a coated paper is pressed against a roughening roll to produce a double-sided matte coated paper, at least 2
By passing between elastic rolls having a specified hardness as a final treatment after treatment with a roughening roll, it is possible to provide a method for producing a double-side coated paper having excellent uniformity in both white paper surface properties and surface properties after printing. This has the effect.

[Brief description of the drawings]

FIG. 1 shows a state in which one side of a coated paper is pressed at least twice against a roughening roll, and then the coated paper is passed through a super calender in which both sides of the coated paper are pressed against an elastic roll. Side view of the super calender shown

FIG. 2 shows a state in which one side of a coated paper is pressed against a roughening roll at least twice, and then the coated paper is passed through a super calender in which both sides of the coated paper are pressed against an elastic roll. Side view of a super calender different from that shown in Fig. 1

FIG. 3 shows a state in which one side of a coated paper is pressed against a roughening roll at least twice, and then the coated paper is passed through a super calender in which only one side of the coated paper is pressed against an elastic roll. Side view of a super calender showing

FIG. 4 shows a state in which one side of a coated paper is pressed against a roughening roll at least twice, and then the coated paper is passed through a super calender in which only one side of the coated paper is pressed against an elastic roll. Side view of a super calender different from FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Elastic roll 2 ... Chilled roll 3 ... Roughening roll 4 ... Paper roll 5 ... Coated paper

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor, Kimifumi Kusumi 373 Yoshioka, Yonago, Tottori Pref. Oji Paper Co., Ltd. Yonago Mill (58) Field surveyed (Int. Cl. ⁷ , DB name) D21H 19/00 -27/42

Claims (1)

(57) [Claims] 1. A method for producing a matte coated paper by applying a coated paper obtained by applying a coating material on a base paper and drying the coated paper to a roughening roll, wherein a surface roughness Rmax defined by JIS B 0601 is provided. After applying a matting treatment by pressing both sides of the coated paper at least twice each on a hard roughened roll having a hardness of 8 to 25 μm, the elasticity in the range of Shore D hardness of 80 to 90 according to ASTM standard D-2240. Pass between the rolls to treat both sides of the matte coated paper, JIS B 0601
Is defined as 0.02 to 0.
A method for producing a double-sided mat coated paper, characterized in that the thickness is in the range of 15 µm.