JPH07119086A - Production of matte coated paper - Google Patents

Abstract

PURPOSE:To provide a matte coated paper having high ink build-up property and printing gloss in spite of low white paper glossiness, exhibiting high contrast, giving excellent white-paper and printed paper characteristics with extremely low gloss unevenness and ink build-up unevenness and having small difference of quality between the top and reverse faces. CONSTITUTION:A stock paper is coated with an undercoating liquid containing 10-90 pts.wt. of ground limestone having an average particle diameter of 0.5-1.0mum and 90-10 pts.wt. of kaolin and then with a top-coating liquid containing 55-95 pts.wt. of ground limestone having an average particle diameter of 0.5-1.5mum and 5-45 pts.wt. of kaolin. The coated paper is dried and finished with a supercalender having >=6 stages and integrated with two metal rolls having surface roughness of the rolls of 8-14mum and 3-7mum (Rz: 10 points average roughness measured in conformity to JIS B-0601). A surface of the coated paper is brought into contact with the metal roll of 8-14mum roughness and then the reverse surface of the paper is brought into the metal roll of 3-7mum roughness. A matte coated paper having high quality can be produced by this process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an excellent white paper and printed surface which have a low glossiness of white paper, a high ink receptivity, a high gloss after printing, a high contrast, and an extremely low unevenness of gloss and unevenness of ink replenishment. The present invention relates to a method for producing a matte coated paper having a shape and having a small difference between front and back sides.

[0002]

2. Description of the Related Art In recent years, there has been a growing need for matte coated paper that is not glossy but has a smooth surface and is excellent in ink acceptance, and is mainly used for high-quality art printing, catalogs, pamphlets, calendars and commercial publications. It is used as a text sheet.

Among matte coated papers, the printed matter called matte has a low gloss on the white paper surface, single color printing surface and multicolor printing surface, and the entire surface is flat and gives a moist visual and tactile sensation. On the other hand, there is a case where the blank surface is not desired to have gloss, but only the print surface is desired to have some gloss. In other words, we want to make the text part or non-printed area a low white paper glossiness so that it is easy to read or easy on the eyes, and the imaged area is highlighted by the gloss to make it a printed product with high contrast and high quality. Is a need. The one that matches this is called the dull tone.
The dull tone is between the matte tone and the gloss tone. Generally, the white paper glossiness and the gloss after printing are slightly higher than the matte tone, and the gloss after printing is slightly lower than the gloss tone.

Matte coated matte coated papers are usually compared with gloss coated papers in order to keep white paper gloss low.
A coating composition containing a large amount of calcium carbonate, which is a coarser pigment, is coated with various coaters and commercialized as it is, or commercialized only by mild calendering.
These matte matte coated papers are usually inferior in smoothness and ink receptivity, and are inferior to dull or glossy coated papers in terms of gloss after printing, and do not give printed matter with high contrast. .

[0005] Further, dull coated paper generally has a small amount of calcium carbonate in order to enhance gloss after printing as compared with matte, and it is commercialized by applying milder supercalendering to coated paper containing more kaolin. ing. Accordingly, the glossiness of the white paper becomes high, and not only a printed matter having a high contrast is not provided, but also uneven orientation of the plate-like kaolin occurs, resulting in uneven gloss and uneven inking of ink, which impairs a sense of quality.

In order to solve such a problem, a method of treating coated paper with a metal roll having a specific surface roughness has already been proposed (Japanese Patent Laid-Open No. 4-119192), which is used. It is stipulated that the surface roughness of each metal roll is 8 to 25 μm in Rmax (maximum height), and the coating liquid and coating method are not stipulated.

[0007]

DISCLOSURE OF THE INVENTION The inventors of the present invention have made diligent studies to solve the above-mentioned problems of the matte coated paper, and as a result, the coating containing a specific heavy calcium carbonate in a specific amount. It is an object of the present invention to coat the liquid in two steps, topcoating and undercoating, and to dry it, and then calendering it in a super calender of 6 stages or more incorporating two metal rolls by a specific paper feeding method. Despite the low glossiness of white paper, it has high ink receptivity, high gloss after printing and high contrast, and has excellent white paper and printing surface state with extremely little unevenness of gloss and unevenness of ink replenishment, and little difference between front and back sides. A matte coated paper is obtained.

[0008]

According to the present invention, the average particle size is
Heavy calcium carbonate having an average particle size of 0.5 to 1.5 μm, which is obtained by coating a base paper with an undercoat coating liquid containing 10 to 90 parts by weight of 0.5 to 1.0 μm of heavy calcium carbonate and 90 to 10 parts by weight of kaolin. Of 55 to 95 parts by weight and 5 to 45 parts by weight of kaolin are applied and dried, and then the surface roughness (Rz: ten-point average roughness JIS B0601) is 8 to 14 μm and 3 to
With a super calender of 6 steps or more incorporating two 7 μm metal rolls, pass one side of the coated paper to the metal roll of 8 to 14 μm first, and the other side to the metal roll of 3 to 7 μm later. And a method for producing a matte coated paper.

The present invention will be described in detail below. The inventors of the present invention firstly prepared a coated paper obtained by applying a coating solution containing 50 to 95 parts by weight of ground calcium carbonate having an average particle diameter of 0.5 to 1.5 μm in a single layer or in a multilayer structure. Rmax is 2
It was confirmed that a printed matter with high contrast was obtained by treating with a metal roll of 8 μm (Japanese Patent Application No. 4-191354). However, as a result of further studies, when passing through a super calender with 6 or more vertical sheets, the matte coated paper obtained with the same surface roughness of the metal roll as in this method may have a difference in front and back. Admitted.

Further, Rmax (JISB0601: maximum height) has been conventionally used as a numerical value for defining the surface roughness of rolls.
However, the numerical value of Rmax is not reproducible due to the manufacturing method of roll surface processing, and it varies depending on the measuring position.
We acknowledged that this number cannot control the quality correctly. Therefore, as a result of re-examination by the present inventors, R
It was confirmed that the quality can be controlled with good reproducibility by using z (JIS B0601: 10-point average roughness). By the way,
Although the conventional value of Rmax tends to be larger than that of Rz, the value of Rmax is not reproducible as described above, so that a certain correlation is not recognized between the two values.

Further, as a result of extensive studies on the compositions of the undercoat coating liquid and the overcoat coating liquid used in the present invention, when the average particle diameter of the heavy calcium carbonate in the undercoat coating liquid exceeds 1.0 μm. Or, if the blending amount exceeds 90 parts by weight, the smoothness after the top coating liquid coating is poor,
It was acknowledged that the final improvement in gloss after printing was insufficient. If the amount of the heavy calcium carbonate is less than 10 parts by weight or the average particle diameter is less than 0.5 μm, the glossiness of the white paper after the top coating liquid coating becomes too high,
It was confirmed that a printed surface with high contrast could not be obtained. On the other hand, when the average particle diameter of the heavy calcium carbonate in the overcoat coating liquid exceeds 1.5 μm, or when the blending amount exceeds 95 parts by weight, improvement in gloss after printing becomes insufficient. If the amount of the heavy calcium carbonate is less than 55 parts by weight or the average particle diameter is less than 0.5 μm, the glossiness of the white paper becomes too high and a printed surface with high contrast cannot be obtained.

Further, in the case of processing with a super calender of 6 stages or more, when one side of the coated paper is first applied to a metal roll having a surface roughness of less than 8 μm, the other side of It was confirmed that there was a problem that the final white paper gloss became too high. Further, when the roll having a diameter of more than 14 μm is first applied, the final improvement in gloss after printing is insufficient.

Similarly, when the opposite surface to be subsequently hit is applied to a roll having a surface roughness smaller than 3 μm, the glossiness of the white paper becomes too high, and when applied to a roll larger than 7 μm,
After printing, the gloss is insufficiently improved.

Therefore, in the case of processing with a super calender, one side of the coated paper first hits a metal roll of 8 to 14 μm, and the other side does not hit a metal roll of 3 to 7 μm later. There is a problem that the difference in gloss between front and back occurs after printing.

As described above, the inventors of the present invention applied the specific coating liquid twice as described above, and then finished the paper passing under the above-mentioned calender conditions to obtain the glossiness (JIS P-8142 75 degree white paper glossiness). ) Is adjusted to 40% or less of coated paper.

As the adhesive used in the present invention, various copolymers of styrene / butadiene type, styrene / acrylic type, ethylene / vinyl acetate type, butadiene / methyl methacrylate type, vinyl acetate / butyl acrylate type and polyvinyl alcohol, Maleic anhydride copolymer,
Synthetic adhesives such as acrylic acid / methyl methacrylate copolymers, oxidized starch, esterified starch, enzyme-modified starch and natural adhesives such as cold-water soluble starch obtained by flash-drying them, casein, soybean protein, etc. Commonly known adhesives are available. These adhesives are used in amounts of 5 to 50 parts by weight per 100 parts by weight of pigment. In the coating liquid of the present invention, various auxiliaries such as a dispersant, a thickener, a water retention agent, a defoaming agent, and a water resistance agent, which are mixed with a usual pigment for coated paper, are used.

The coating composition thus prepared comprises a base coater and a blade coater, a base coater and a top coater, respectively.
An air knife coater and a blade coater, a blade coater and an air knife coater, a gate roll coater and a blade coater, and a combination of a gate roll coater and an air knife coater are applied on a base paper by on-machine or off-machine.

As the base paper, a paper base or board base base paper having a basis weight of 30 to 400 g / m ² which is used for general coated paper for printing is used. The coating amount of the coating composition on such base paper is 15 to 50 in terms of dry weight in terms of quality.
It is adjusted in the range of g / m ² .

As described above, the present inventors have found that the average particle size is 0.5 to 1.
An undercoat coating liquid containing 10 to 90 parts by weight of 0 μm heavy calcium carbonate and 90 to 10 parts by weight of kaolin is applied to the base paper, and a heavy calcium carbonate having a particle diameter of 0.5 to 1.5 μm is applied.
After coating the top coating liquid containing 55 to 95 parts by weight and 5 to 45 parts by weight of kaolin and drying, the surface roughness (Rz: ten-point average roughness JIS B0601) is 8 to 14 μm and 3 to 7 μm. With a super calender of 6 or more stages that incorporates two metal rolls,
One side of the coated paper first hits a metal roll of 8-14 μm,
By finishing so that the opposite side will hit a metal roll of 3 to 7 μm later, ink receptivity, high gloss after printing, high contrast, uneven gloss, and ink replenishment even if the white paper glossiness is 40% or less It was confirmed that it is possible to obtain a matte coated paper which has an excellent white paper and printing surface condition with extremely little unevenness and has a small difference in front and back.

[0020]

【Example】

(Examples 1 to 3 and Comparative Examples 1 to 9) The present invention will be specifically described below with reference to Examples, but the present invention is not limited thereto.

As shown in Table 1, kaolin [manufactured by Engelhard Co., Ltd., trade name: Ultra White 90] and heavy calcium carbonate [manufactured by Sankyo Seiko Co., Ltd., trade name: Escalon # 1500 (average particle size) 1.7 μm), trade name: Escalon # 2000 (average particle size 1.2 μm), trade name: Escalon # 2200 (average particle size 0.9 μm) or Yotai Co., Ltd., trade name: Tancal NCC-α-90 (average particle size) Diameter 0.5 μm)] to 100 parts by weight of a mixed pigment, 0.3 parts by weight of a dispersant (Toagosei Co., Ltd., trade name: Aron T-40) was added, and the mixture was dispersed in water using a Cowles disperser. 5 parts by weight of oxidized starch (Oji Corn Starch Co., Ltd., trade name: Oji Ace B) and 10 parts by weight of a synthetic adhesive (Asahi Kasei Co., Ltd., trade name: L-1762) as an adhesive are used as the top coat and undercoat. Coating composition A solid concentration of 63%)
Got

This was coated on a base paper having a basis weight of 90 g / m ^{2 by} a blade coder so that the dry weight (one side) of the undercoat coating composition shown in Table 1 was 8 g / m ² . On top of this, a top coat composition shown in Table 1 was coated with a blade coater so that the dry weight (one side) was 7 g / m ² .
Dried.

As shown in FIG. 1, the obtained coated paper had the surface roughness (Rz: ten-point average roughness JIS B0601) shown in Table 1.
The first roughening roll (3-2) with a 12-stage super calendar (made by Minami Senju Seisakusho) consisting of a metal roll (3) incorporating two metal rolls of 5 μm, 11 μm or 18 μm and a cotton roll (1) The surface corresponding to the F surface (4-
Processed as in 1). Linear pressure during calendar processing
100kg / cm, metal roll temperature 70 ℃, processing speed 600m / m
in constant.

In Comparative Examples 8, Comparative Example 8 is not calendered, and Comparative Example 9 is a coating composition in which the dry weight (one side) of the coating composition is 15 g / m ^2. It is a coated paper obtained by coating a single layer on.

<Quality evaluation method> -Average particle size: A 50% point of the cumulative weight distribution was measured as an average particle size using a light transmission type particle size distribution measuring device SHC5000 manufactured by Seishin Enterprise.

White paper glossiness: Measured at an angle of 75 ° according to JIS P-8142.

Smoothness: Measured with JAPAN Tappi No5 Oken type smoothness tester.

-Gloss after printing: Using a RI-II type printing tester, ink for Sakata ink offset printing (trade name:
0.35 cc of Diatone GSL red) was used for printing, and after leaving it all day and night, the glossiness at 75 degrees was measured.

Contrast property: Using a two-color offset sheet-fed printing machine (manufactured by Ryobi: 3302M), printing was performed using first-color indigo ink and second-color red ink, and the contrast property between the white paper and the printed surface was visually evaluated. The visual evaluation criteria were the following three grades. ⊚: Very high contrast △: Normal contrast ×: Insufficient contrast

.Surface condition (uneven gloss, uneven ink deposition): 2
Using a color offset sheet-fed printing machine (manufactured by Ryobi: 3302M), printing was performed using the first-color indigo ink and the second-color red ink, and the uneven glossiness on the white paper surface and the uneven ink buildup on the printed surface were visually evaluated. The visual evaluation criteria were the following three grades. ◎: Very excellent surface condition ○: Relatively good surface condition △: Normal surface condition

Difference between front and back: Two-color offset sheet-fed printing machine (manufactured by Ryobi: 3302M) was used to print using first-color indigo ink and second-color red ink, and the front-back difference between the blank surface and the printed surface was visually evaluated. . The visual evaluation criteria were the following two grades. ◎: Almost no difference between front and back ×: Those with front and back difference

[0032]

[Table 1]

[0033]

As is clear from Table 1, Example 1,
2 and 3 have high smoothness even though the glossiness of white paper is low,
After high printing, the finished product has a glossy finish with very high contrast, and the unevenness of gloss and ink buildup on white paper is extremely small, and there is almost no difference between the front and back sides.

On the other hand, in Comparative Example 1, since the amount of kaolin contained in the undercoating liquid is high, the glossiness of the white paper becomes too high and the contrast is poor. In Comparative Example 2, since the particle size of the ground calcium carbonate blended in the undercoat coating liquid is large, the smoothness is low and the gloss after printing is low. In Comparative Example 3, since the amount of kaolin contained in the top coating liquid is high, the glossiness of the white paper becomes too high and the contrast is poor. Comparative Example 4
Has a large particle size of heavy calcium carbonate compounded in the top coating liquid, so that the smoothness is low and the gloss after printing is low. In Comparative Example 5, since the surface roughness of the roll on which the coated paper first hits is smaller than the surface roughness of the roll on which the coated paper hits later, the smoothness, the white paper glossiness, and the post-printing gloss of the surface that hits later than the surface that hits first. Is low and the difference between front and back becomes too large. In Comparative Example 6, since the surface roughness of the roll that first hits is too large, the smoothness, the glossiness of white paper, and the gloss after printing of the first contacted surface are low and the difference between the front and back surfaces becomes too large, compared to the surface that is subsequently contacted. In Comparative Example 7, the rolls that hit first and the rolls that hit later are too large in surface roughness, so that the smoothness is low and the gloss after printing is low. Since Comparative Example 8 was not subjected to calendar treatment, the smoothness was low and the gloss after printing was low. Since Comparative Example 9 has only one coating layer, the smoothness is low and the gloss after printing is low.

As can be seen from the above, the matte-coated paper produced by the method for producing matte-coated paper of the present invention has an unprecedentedly excellent quality, and its product value is extremely large. is there.

[Brief description of drawings]

FIG. 1 is a super calender device which is composed of 12 rolls for obtaining a matte coated paper used in an example of the present invention, and which is fed so that a surface corresponding to a roughening roll is an F surface first. FIG.

[Explanation of symbols]

 1-1-6 Cotton Roll 2-1-2 Chilled Roll 3-1-2 Roughened Metal Roll 4 Coated Paper 4-1 F Side 4-2 W Side

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] November 17, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Change

[Correction content]

As described above, according to the present invention , the glossiness (JIS P-8142) is obtained by applying the specific coating liquid twice as described above and then finishing the paper passage under the above-mentioned calendar conditions.
It is adjusted so that the coated paper has a white paper gloss of 75 degrees) of 40% or less .

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0033

[Correction method] Change

[Correction content]

[0033]

As is clear from Table 1, Example 1
2 and 3 have high smoothness even though the glossiness of white paper is low,
After high printing, the finished product has a glossy finish with very high contrast, and the unevenness of gloss and ink buildup on white paper is extremely small, and there is almost no difference between the front and back sides.

Claims (1)

[Claims] 1. In the production of a matte coated paper in which a coating liquid is applied twice to a base paper, 10 to 90 parts by weight of ground calcium carbonate having an average particle size of 0.5 to 1.0 μm and 90 to 10 parts of kaolin are used. By coating the base paper with the undercoat coating liquid contained by weight, and
55-95 parts by weight of 0.5-1.5 μm heavy calcium carbonate,
Applying a topcoat coating liquid containing 5-45 parts by weight of kaolin,
After drying, the surface roughness of the roll (Rz: ten-point average roughness J
IS B0601) uses 8-14 μm and 3-7 μm metal rolls.
With this built-in super calender of 6 steps or more, one side of the coated paper first hits a metal roll of 8 to 14 μm, the other side hits a metal roll of 3 to 7 μm later, and the glossiness (JIS
P-8142 A method for producing a matte-coated paper, which comprises calendering so that the 75-degree white paper glossiness) is 40% or less.