JPH0665898A - White paperboard for offset printing and gravure printing - Google Patents

Abstract

PURPOSE:To provide a white paperboard for offset printing and gravure printing and provide a process for the production of the paperboard. CONSTITUTION:This coated white paperboard for offset printing and gravure printing has an undercoating layer directly applied to the surface of a base paper and a top coating layer formed on the undercoating layer. The undercoating layer contains a pigment containing heavy calcium carbonate and precipitated calcium carbonate and a binder resin for the pigment and the top coating layer contains a pigment containing calcined kaolin and a binder resin containing an organic binder pigment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to white paperboard commonly used for offset gravure printing, and more particularly to confectionery,
The present invention relates to coated white paperboard commonly used for offset / gravure printing, which is used as packaging paper for favorite products such as cigarettes.

[0002]

2. Description of the Related Art Conventionally, offset printing has been used for printing white paperboard, but in recent years, a gravure printing method has been adopted in order to improve operability of printing work. However, conventional white paperboard is mainly designed for offset printing, and if gravure printing is performed on that paper,
There is a defect that halftone dots are missing and the finish of the printed surface is deteriorated.

On the other hand, in the case of coated white paperboard, it is necessary to make offset and gravure printing papers in the same lot in consideration of the efficiency of manufacturing work. Therefore, the offset suitability of the conventional coated white paper is maintained. However, it is becoming an important factor to improve the gravure printability as well.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an offset / gravure common white paperboard having excellent printability for both offset printing and gravure printing.

[0005]

A so-called coated white paperboard having a coating layer containing a pigment generally has printability for both offset printing and gravure printing.
It is not always good due to reasons such as poor smoothness resulting from poor formation of coated white paperboard due to sheeting, and poor balance of coating layer adhesion (cushioning property) and ink absorption during gravure printing. It was not suitable for gravure. On the other hand, the inventors of the present invention, in order to solve the above problems, as a result of studying the configuration of both layers of the overcoat coating layer and the undercoat coating layer of coated white paperboard, a pigment that constitutes these layers, a binder It was found that by combining resins and the like in a specific type and range, a white paperboard for offset / gravure printing having sufficient gravure printing characteristics can be obtained.

That is, the present invention provides a coating for both offset and gravure printing, which has an undercoating layer formed directly on the surface of a base paper and an overcoating layer formed on the undercoating layer. An engineered white paperboard, wherein the undercoat layer comprises a pigment containing 30 to 70% by weight of heavy calcium carbonate and 20 to 50% by weight of light calcium carbonate, and 10 to 30 parts by weight of the binder resin with respect to 100 parts by weight of the pigment. 10 parts by weight of the binder resin and 5 to 20 parts by weight of a binder resin with respect to 100 parts by weight of an inorganic pigment containing 10 parts by weight of calcined kaolin and containing 100 parts by weight of an overcoating layer. The present invention provides a coated white paperboard for offset / gravure printing, which is characterized by containing parts. Hereinafter, the present invention will be described in detail.

As the base paper of the present invention, general base paper used in the production of conventional coated white paperboard can be used without particular limitation, and for example, 150 m2 to 600 g / m ^{2 of} tsubo.
It is preferred to use a degree of multilayer paperboard. The present invention comprises an undercoating coating layer and an overcoating coating layer, but the undercoating coating layer of the present invention mainly covers poor formation of the base paper, improves smoothness, and at the same time provides cushioning properties. In addition, the top coat layer of the present invention has the function of improving all of smoothness, cushioning property, and ink absorbency.

The undercoat layer of the present invention is a layer containing a pigment containing heavy calcium carbonate and light calcium carbonate, and a binder resin. The pigment constituting the undercoating layer of the present invention is composed of 30 to 70% by weight of heavy calcium carbonate, preferably 50 to 70% by weight, and light calcium carbonate 2
It is a pigment containing 0 to 50% by weight, preferably 30 to 50% by weight. As the pigment other than calcium carbonate, any pigment that has been conventionally used for coated white paperboard can be used without particular limitation. The average particle size of the pigment is preferably set to about 0.6 to 1.0 μm.

The heavy calcium carbonate to be added to this pigment has an average particle size of 0.5 to 3 μm, especially 1.0 to 1.5 μm.
m is preferred, and light calcium carbonate has an average particle size of
The thickness is preferably 0.3 to 1 μm, and more preferably 0.5 to 0.7 μm. The reason for combining heavy calcium carbonate and light calcium carbonate in this way is that heavy calcium carbonate with a large average particle size mainly fills large irregularities due to poor formation of the base paper, and light calcium with a relatively small average particle size. Calcium carbonate
This is because it fills the remaining small irregularities of the base paper and also provides cushioning properties.

Here, if the blending ratio of the heavy calcium carbonate having a large average particle diameter, that is, a small (specific) surface area, is increased, the amount of the required binder is reduced and the surface strength at the time of offset printing is improved. Therefore, by blending heavy calcium carbonate and light calcium carbonate having these average particle diameters in combination, the smoothness and cushioning property in the coating layer are improved, and it has excellent suitability for both offset and gravure printing. It becomes coated white paperboard.

Examples of the binder resin used in the undercoating layer of the present invention include water-soluble resins such as starch, starch derivatives, polyvinyl alcohol, modified polyvinyl alcohol, and casein, and styrene-butadiene copolymer latex. , Water-dispersible resins such as styrene / acrylic copolymer latex, butadiene / acrylic copolymer latex, and vinyl acetate / acrylic copolymer latex.

The binder resin (solid content) is 10 to 30 parts by weight, especially 15 to 10 parts by weight, based on 100 parts by weight of the pigment.
It is preferable to use 25 parts by weight. By reducing the binder resin, particularly the natural binder that forms a hard coating layer, it is possible to improve the cushioning property of the coating layer and improve the halftone dot reproducibility. The undercoat coating layer of the present invention is 5 to 20 g / m ² in terms of pigment weight, especially 8
It is preferably formed so as to have a thickness of -15 g / m ² .

The top coat layer of the present invention contains 5 to 20 parts by weight of a binder pigment and 10 to 30 parts by weight of a binder resin, based on 100 parts by weight of a pigment containing calcined kaolin. The pigment used in the overcoat layer of the present invention contains 10 to 30% by weight of calcined kaolin, preferably 1%.
It is an inorganic pigment containing 0 to 20% by weight. The calcined kaolin to be mixed with this pigment preferably has a relatively large average particle size of about 0.4 to 1.0 μm. The pigment other than calcined kaolin can be used without any particular limitation as long as it has been conventionally used for coated white paperboard, and among them, calcium carbonate, titanium kaolin, and satin white are preferable, and The average particle size of the pigment is preferably 0.4 to 1.2 μm. The calcined kaolin and other pigments are preferably combined in a relatively large size and uniform size in order to improve smoothness and cushioning properties on coated paper.

The binder pigment used in the overcoat layer of the present invention is a plastic pigment having a binder function. Generally, it has a core / shell structure produced by two-stage feed polymerization and having different polymer compositions in the core and the shell. The core part has a function as a plastic pigment, and the shell part has a function as a binder.

The binder pigment used in the present invention is
Consisting essentially of a double structure of a film-forming "hard" core and a film-forming "soft" surface,
Examples of particles constituting the core include styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2,4-diisopropylmethylstyrene, 2,4-dimethylstyrene, 4-t-. Aromatic vinyl compounds such as butylstyrene, 5-t-butyl-2-methylstyrene, monochlorostyrene, dichlorostyrene, monofluorostyrene, hydroxymethylstyrene; vinyl chloride; and acrylic acid, methacrylic acid,
There are unsaturated carboxylic acids such as crotonic acid, cinnamic acid, itaconic acid, fumaric acid, maleic acid, butenetricarboxylic acid, itaconic acid monobutyl ester and salts thereof, and two or more kinds of these monomers may be used. Further, the polymer forming the surface layer of the binder pigment is a butadiene-based copolymer containing a butadiene aromatic vinyl compound, a methacrylic acid ester, an unsaturated carboxylic acid and an unsaturated acid amide, butadiene and styrene, α-methyl Aromatic vinyl compounds such as styrene, 4-methylstyrene, monochlorostyrene and hydroxymethylstyrene, methacrylic acid esters such as methyl methacrylate and ethyl methacrylate, acrylic acid, methacrylic acid, itaconic acid, fumaric acid, itaconic acid monobutyl ester And an unsaturated carboxylic acid or a salt thereof and an unsaturated acid amide such as acrylamide, methacrylamide, N-methylolacrylamide, N-butoxymethylacrylamide or a derivative thereof. If necessary, ethylene-based nitrile compounds such as acrylonitrile and methacrylonitrile; 2-methyl-1,3-butadiene, 2-chloro-
Fatty acid diolefin compounds such as 1,3-butadiene;
Ethyl acrylate, butyl acrylate, β-acrylic acid
At least one of acrylic acid esters such as hydroxyethyl, glycidyl acrylate, amide amidoethyl and the like can be further copolymerized.

The binder pigment is preferably used in an amount of 5 to 20% by weight, particularly 5 to 12% by weight. Since this binder pigment is a pigment with a uniform particle size, it is effective in improving printability, and the use of binder pigment improves smoothness of ink settability,
Further, the surface strength is also improved. Further, since the blank paper and the printing glossiness are improved, the quality of offset printing can also be improved. The cushioning property can also be improved by limiting the addition amount of natural binders such as casein and starch which are factors that form a hard coating layer like the undercoat layer.

The binder resin used in the overcoat coating layer of the present invention is the same as that used in the undercoat coating layer. The ratio of each component in the overcoat layer is preferably 10 to 30 parts by weight, and more preferably 15 to 25 parts by weight with respect to 100 parts by weight of the pigment. By limiting the amount of the binder resin that forms a hard coating, the cushioning property to the coating layer is improved and the gravure printing suitability is improved.

The undercoat coating layer of the present invention is preferably formed so as to have a weight of 5 to 20 g / m ² , particularly 8 to 15 g / m ² in terms of pigment weight. When an air knife coater is used, the coating liquid used to form the topcoat coating layer of the present invention is prepared to have a solid content concentration of 35 to 40% by weight to form an undercoat coating layer. The coating liquid is prepared so that the solid content is 50 to 60% by weight, but the concentration is appropriately adjusted depending on the type of coating machine.

The coating method of the undercoat coating layer and the overcoat coating layer is not particularly limited. Generally, a rod coater, a roll coater or the like is used to form the undercoat coating layer.
Further, a blade coater, a rod coater, an air knife coater or the like can be used for forming the overcoat coating layer.

[0020]

The cushioning property and the ink absorbing property are improved by the above-mentioned overcoating layer, and the paper having a good print finish is obtained together with the effect of improving the formation failure by the undercoating layer. Therefore, according to the present invention, it is possible to obtain an offset / gravure printing common white paperboard having excellent printability for both offset printing and gravure printing.

[0021]

EXAMPLES The coated white paper for offset / gravure printing of the present invention will be described in detail below based on examples. [Examples 1-2 and Comparative Examples 1-9] Rice basis weight 250 g / m ²
100 parts by weight of the pigments listed in the predetermined column in Table 1, 17 parts by weight of styrene-butadiene latex (solid content), and 2 parts by weight of starch (solid content) with respect to the base paper consisting of recycled multilayer paperboard. Test coating (gate roll coater)
Then, a solid content of 10 g / m ² is applied, followed by drying to form an undercoat coating layer directly on the base paper, and subsequently, a solid content concentration of the following composition as a solid content on the undercoat coating layer. A 35 wt% coating solution for topcoating was applied with the same test coater (air knife coater) to a solid content of 9 g / m ² and dried to form a topcoating layer.
In order to compare the performance with the coated white paperboard for both offset and gravure printing of the present invention produced in Examples, coated white paperboards other than the present invention were produced in Comparative Examples.

The pigments used for forming the undercoat layer are light calcium carbonate having an average particle size of 0.6 μm and heavy calcium carbonate having an average particle size of 1.5 μm. Solid content in top coating liquid (1) Pigment: 100 parts by weight Calcined kaolin (average particle size: 0.7 μm): 20 parts by weight First grade kaolin (average particle size: 0.9 μm): 50 parts by weight Parts Light calcium carbonate (average particle size 0.6 μm) ・ ・ ・ 30 parts by weight (2) Resin for binder ・ ・ ・ 27 parts by weight (31 parts by weight) Styrene / butadiene latex ・ ・ ・ 18 parts by weight Casein ・ ・ ・ 4 Parts by weight Binder pigment: 5 parts by weight (Asahi Kasei Corp. L-8804) [Evaluation experiment] Smoothness, cushioning property, white paper gloss, and printing gloss of each coated white paperboard obtained in Examples and Comparative Examples. The degree, surface strength, ink setting property and halftone dot reproducibility were evaluated.

The evaluation criteria are the 5-point method and ◎ to ×. Display by and. As is clear from Table 2, by using the whiteboard for both offset and gravure of the present invention, good printed matter can be obtained in both the commonly used offset printing and the gravure printing method which has been growing in recent years. I was able to.

[0024]

[Table 1] Table 1 ─────────────────────────────────── Examples Comparative Examples 1 2 1 2 3 4 5 6 7 8 9 Undercoat layer [Pigment composition (% by weight)] Light calcium carbonate 40 40 20 40 20 40 40 10 10 40 Light calcium carbonate 60 60 50 60 50 60 50 60 90 60 Kaolin 30 30 60 50 30 ─────────────────────────────────── Overcoat layer [Pigment composition (% by weight)] Kaolin 0.4 μm 65 65 Kaolin 0.9 μm 50 50 60 50 50 50 50 50 50 Light calcium carbonate 30 30 20 20 35 30 30 30 30 30 10 TiO ₂ 15 15 Calcined kaolin 20 20 5 20 20 20 20 20 40 (Binder 5 10 5 5 5 5 5 Pigment] ───────────────────────────────────

[0025]

[Table 2] Table 2 ─────────────────────────────────── Example Comparative Example 1 2 1 2 3 4 5 6 7 8 9 Smoothness 3.8 3.8 3.5 3.6 3.7 3.6 3.6 3.5 3.7 3.5 3.8 (5-point method) Cushion △ to ○ △ to ○ △ '△ △ △ △ △ △ △' △ to ○ White gloss 47.0 50.8 53.4 53.0 47.0 41.5 48.6 45.7 46.0 44.0 43.0 degree (%) Printing gloss 88.5 89.8 87.8 88.0 88.0 86.0 89.5 87.0 88.0 86.0 85.5 degree (%) Surface strength 3.5 3.7 3.0 3.3 3.5 3.4 2.8 3.9 3.6 3.9 3.0 (5-point method) Ink △ to ○ △ to ○ △ △ △ △ ○ '× to △ △ × to △ △ to ○ Setability Halftone dot ○ to ◎ ◎ × to △ △ △ ○ ○' △ △ △ '○ to ◎ Reproducibility ─── ──────────────────────────────── (Note) i) The 5-point method should have a higher score. (Good) 5 to 1
(Poor) ii) Δ'means slightly worse than Δ. iii) ○ 'means slightly worse than ○.

Claims (2)

[Claims] 1. A coated white paperboard for both offset and gravure printing, comprising an undercoat coating layer formed directly on the surface of a base paper and an overcoat coating layer formed on the undercoat coating layer. There, the undercoat layer is ground calcium carbonate 3
A pigment containing 0 to 70% by weight and 20 to 50% by weight of light calcium carbonate, and 10 to 30 parts by weight of a resin for a binder based on 100 parts by weight of the pigment, and the top coat layer contains calcined kaolin. An inorganic pigment containing 10 to 30% by weight, and 5 to 20 parts by weight of a binder pigment, and 10 to 30 parts by weight of a binder resin, based on 100 parts by weight of the pigment. Coated white paperboard. 2. An undercoat coating layer 5 in terms of pigment weight.
In 20 g / m ^2, coated white paperboard offset gravure printing sharing according to claim 1, wherein the topcoat coating layer is formed so as to be 5 to 20 g / m ^2.