JPH0559692A - Multi-layer coated paper - Google Patents

Abstract

PURPOSE:To obtain the title coated paper with excellent white glass and printed gloss, suitable for, in particular, both gravure printing and roto-offset printing by providing each specific undercoating layer and face coating layer on the surface(s) of a base paper. CONSTITUTION:The objective coated paper can be obtained by providing one or both of the surfaces of a base paper with (A) a undercoating layer (pref. at 7-20g/m<2> on a dry basis) predominant in (1) a pigment (e.g. clay, aluminum hydroxide) containing 10 (pref. 60-100)wt.% of starch particles (pref. rice starch which are 2.0-20mum in volume distribution mean size and >=0.6 in its coefficient of variation and (2) an adhesive and (B) a face coating layer (pref. at 7-12g/m<2> on a dry basis) predominant in pigment and adhesive.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer coated paper for printing, and more particularly to a multilayer coated paper suitable for both gravure printing and roller offset printing.

[0002]

2. Description of the Related Art In recent years, the demand for high-quality printed materials, multicolor printed magazines and pamphlets has been rapidly increasing. For printing high-quality printed matter, gravure printing, which has good reproducibility for photographs and paintings and forms a beautiful printed surface, is suitable for printing multicolor printed matter such as magazines, and offset printing. Is suitable.

However, in gravure printing, if the smoothness of the printed paper surface is low, misdots and halftone dots will be reproduced poorly, and the printing effect will be significantly reduced, and even in offset printing, the surface of the printing paper will also be affected. If the smoothness is low, the acceptability of the ink becomes poor, and the gloss of the ink becomes uneven in the solid printing portion of multicolor printing, resulting in extremely poor quality printing. In order to improve such a defect of the printing paper, it is effective to increase the coating amount of the printing coated paper, and JP-A-61-698 discloses
Produces coated paper with multiple coating layers using the double coat method that improves the coatability of the base paper, and printability such as white paper gloss, printing gloss, ink receptivity and printing surface smoothness Discloses a good multi-layer coated paper.

Further, among the offset printing, the roller offset printing has a problem of blister resistance. Blister property means the property of causing blisters on both sides of coated paper when the ink on the printing paper surface printed by a roller offset printing machine is forced to dry at high temperature. It significantly reduces the product value. The double-coated paper has insufficient blister resistance and is likely to cause blistering. Therefore, it cannot be used for roller offset printing as it is, and it is attempted to forcibly improve the blister resistance. Then, the glossiness of white paper, the surface strength, and the like are lowered, and the printability is significantly deteriorated. JP 63-1
No. 96793 discloses a coated paper which has improved blister resistance and can be used in both sheet offset printing and roller offset printing, but its blister resistance is still insufficient, and its printability in gravure printing is further improved. Improvement has not been achieved.

Therefore, it has been difficult to produce a coated paper having blister resistance and excellent printability suitable for gravure printing and offset printing, and it is difficult to obtain such a coated paper. However, it has been a big problem for those who manufacture coated paper.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems and has printability such as white paper gloss, printing gloss, ink receptivity, and printing surface smoothness superior to conventional ones, and at the same time, blistering resistance. An object of the present invention is to obtain a multi-layer coated paper which has properties and can be widely used in gravure printing, offset printing, roller offset printing and the like.

[0007]

As a result of research for solving the above-mentioned problems, the inventors have found that the use of starch as a part of the pigment in the undercoat layer of multilayer coated paper results in excellent printing characteristics. The present invention has been completed by finding that a coated paper for printing having a blister resistance and a blister resistance can be obtained. The present invention is
At least one surface on the base paper, a multi-layer coated paper provided with an undercoat layer containing a pigment and an adhesive as main components, and at least one overcoat layer containing a pigment and an adhesive as a main component,
Provided is a multi-layer coated paper characterized in that the pigment of the subbing layer contains at least 10% by weight of starch particles.

The reason why the coated paper for printing having excellent printing characteristics and blister resistance is obtained by the present invention is as follows. By using starch as a pigment in the undercoat layer, the air permeability of the coated paper is improved, the blister resistance required for rotary offset printing is considerably improved, and the cushioning property is further improved, so it is required for gravure printing. The dot reproducibility of coated paper is significantly improved. Therefore,
By using starch as a pigment in the undercoat layer, whiteness, without considering blister resistance and halftone dot reproducibility,
This is because the overcoat layer can be formed by focusing on physical properties such as opacity and glossiness.

The term "volume distribution average particle size of starch" in the present specification refers to a value obtained by dividing the total volume of individual starch particles by the total number of particles. In the present specification, a particle size distribution measuring device (micrometer) is used. A volume distribution average particle size (MV) obtained by measurement using a track particle size analyzer: Nikkiso Co., Ltd. is used. The volume distribution average particle size of this starch can be calculated based on the following formula: Volume distribution average particle size (MV) = Σ (Vi × di) / ΣVi where Vi = volume ratio in each particle size segment di = representative diameter of the particle diameter in each particle size classification The term "coefficient of variation" in the present specification means the standard deviation (SD) of the volume particle diameter distribution in the volume distribution average particle diameter (MV).
Is the coefficient divided by and can be calculated based on the following formula: Coefficient of variation = SD / MV.

This coefficient of variation is a coefficient by which the influence of the average particle size of the volume distribution can be removed and the variation in particle size can be compared. The smaller the value, the more uniform the particle size and the more uneven the particle size. Indicates that there are few. The starch used in the present invention is a starch having a volume distribution average particle size of 2.0 to 20 microns and a variation coefficient of the volume distribution average particle size of 0.6 or less, and can be used in a non-gelatinized state. I can list things. For example, rice starch, wheat flour starch, takapio starch, corn starch, sweet potato starch and the like can be mentioned. Particularly, since they have a property of absorbing basic dyes well and sticking well to unevenness of paper, rice starch Is excellent. If necessary, modified starch obtained by using the above-mentioned starch as a raw material can be used. Particularly, when the starch is a slurry having a pH of 2 to 11, a pH of 5 to 10.5 and a temperature of 5 to 5 are used.
Modified starch that is not gelatinized when dispersed in a 0 ° C. paint is preferred. Furthermore, if desired, starch crosslinked with a crosslinking agent such as formaldehyde, epichlorohydrin, succinic acid may be used.

The pigment for coated paper used in combination with the above-mentioned starch is not particularly limited as long as it is a pigment for coated paper which has been conventionally used, but generally the volume distribution average particle diameter is 0.5 to 0.5. 1
0 micron, coefficient of variation of volume distribution average particle size is 0.3 to 1.5
It is better to use the one. Specific examples include clay, kaolin, talc, aluminum hydroxide, light calcium carbonate, heavy calcium carbonate, titanium oxide, magnesium carbonate, alumina, activated clay, acid clay, diatomaceous earth, synthetic silica, zinc oxide, sulfuric acid. Barium, calcium sulfate, satin white, lake, plastic pigment, binder pigment, etc.

The pigment used in the undercoat layer of the present invention is prepared by mixing the starch and, if necessary, one or more kinds of the pigments. At this time, the ratio of the starch is 10% by weight.
The above content is preferably 20% by weight or more, particularly preferably 60 to 100% by weight, and the balance is the pigment. It should be noted that the ratio of starch is specified in this way when starch is 10
This is because if it is less than wt%, the blister resistance and printing characteristics of the coated paper cannot be improved.

The pigment used in the overcoat layer is not particularly limited as long as it is a conventionally used pigment for coated paper, and the same pigment as that used in the undercoat layer except starch is used alone. Alternatively, they can be mixed and used. Further, the coating amount of the pigment in the undercoat coating layer is 5 to 30 g / m ² , preferably 7 to 20 in terms of weight after drying per one surface.
g / m ² . This is because when the coating amount is less than 5 g / m ² , the coating effect is not sufficiently obtained, while when it is 30 g / m ² , the coating effect is saturated. Further, the coating amount of the pigment in the top coating layer is 5 to 20 g / dry weight per one side.
m ² , preferably 7 to 12 g / m ² .

By forming multiple coating layers using pigments having such a composition, the coated paper has excellent printing characteristics and blister resistance, and this coated paper is subjected to gravure printing. When it is used, dot dropout is extremely small and halftone dot reproducibility is excellent, and when it is used for offset printing, it is particularly excellent in ink receptivity and blister resistance. It is considered that such an effect is obtained because the use of a pigment containing a predetermined amount of starch in the undercoat layer allows the pigment particles to be easily arranged in the coating layer and a bulky coating layer with large voids to be obtained. Be done.

As the adhesive constituting the coating layer of the present invention, there is no particular difference between the undercoat layer and the overcoat layer, and known adhesives can be used. For example, styrene / butadiene type, styrene / acrylic type, acetic acid Various copolymers such as vinyl / acrylic, ethylene / vinyl acetate, butadiene / methylmethacrylate, vinyl acetate / butyl acrylate, etc., and alkali-sensitive or alkali-insensitive adhesives such as polyvinyl acetate, and polyvinyl. alcohol,
Synthetic adhesives such as maleic anhydride / styrene copolymers, isobutene / maleic anhydride copolymers, acrylic acid / methacrylate copolymers, as well as oxidized starch, etherified starch, esterified starch, enzyme-modified starch and It can be used by appropriately selecting from cold water-soluble starch, casein, soybean protein and the like obtained by flash-drying them. The adhesive is used in an amount of 3 to 50 parts by weight, preferably 5 to 20 parts by weight, based on 100 parts by weight of the pigment.
Parts by weight.

Further, if necessary, a dispersant, a viscosity modifier, a water retention agent, an antifoaming agent, a water resistance agent, a lubricant, a dye, and a pH.
Various auxiliaries such as regulators can also be appropriately blended. In preparing the coating material for coating, various mixers, kneaders, mixing and stirring machines such as ball mills can be appropriately selected and used according to the type of coating composition. The coating material for forming the coating layer is prepared by mixing 100 parts by weight of the pigment and 3 to 30 parts of the adhesive while mixing with a mixing stirrer.
It is carried out by sequentially adding parts by weight and, if necessary, additives such as a dispersant. Generally, the solid content of paint is 30
It is selected according to the purpose between -80%.

A coating layer comprising an overcoat layer and an undercoat layer, which constitutes the coated paper of the present invention, is coated on both sides or one side of a base coating paper. In this case, the composition of the coating composition applied on both sides can be appropriately changed according to a general method. The coating method is also not particularly limited, for example, air knife coater, roll coater, bar coater, rod coater, bevel or vent type blade coater, further, bill blade, twin blades, various blades such as. Various known coating devices such as coaters and short dwell coaters can be used as appropriate. After coating, it is generally finished with a finishing device such as a super calendar or a gloss calendar.

The coating amount of the undercoat layer is 5 to 30 g / m ² , preferably 7 to 20 g / m ² in terms of dry weight.
^{2. The} dry weight of the overcoat layer is 5 to 20 g / m ² , preferably 7 to 12 g / m ² . Further, the base paper used in the present invention is not particularly limited, and as the base paper, various wood pulps and synthetic pulps may be used alone or mixed to make papers. The basis weight is 20 to 200 g / m ² , and preferably 24 to 160.
g / m ² .

[0019]

EFFECTS OF THE INVENTION According to the present invention, while having printability such as white paper gloss, printing gloss, ink receptivity, and print surface smoothness superior to conventional ones, and having blister resistance, gravure printing, offset printing and It was possible to obtain a multi-layer coated paper that can be widely used for roller offset printing and the like.

[0020]

EXAMPLES The contents and effects of the present invention will be described below with reference to Examples.
However, the present invention is not limited to these examples.
It is not limited to the scope of the examples. In the examples
Unless otherwise specified, "part" and "%" in
"Parts by weight" and "% by weight" are shown. [Example 1]Undercoat paint Micropearl as a starch pigment (volume distribution average particle size 4.7μ
m, coefficient of variation 0.58, Shimada Chemical Co., Ltd.) 100 parts
Add 0.4 parts sodium polyacrylate and 0.1 parts NaOH.
Then, a pigment slurry was prepared. Further gelatinized phosphoric acid
Stellized starch (Neil gum A85, Abbe Co., Ltd.) 4
Part, SBR latex (JSR T-2102P Tg =
-20 ° C., Japan Synthetic Rubber Co., Ltd.) 7 parts added, solid content
A paint having a concentration of 37% was prepared. Meyer the resulting paint
Coating amount using a bar 10g / m on one side ²To be medium quality
Coated base paper 41g / m²And then dried.Top coating Commercial delaminated clay (Nukray (volume distribution average grain
Diameter 5.9 μm, coefficient of variation 0.73), Engelhard Co., Ltd.)
60 parts, first-grade clay (Rustler 40, Engelhard) 40
Partial mixed pigment 0.4 parts sodium polyallyl acid, Na
Add 0.1 parts of OH to prepare a pigment slurry and further gelatinize.
2 parts of phosphoesterified starch (neal gum A85)
9 parts of SBR latex (T-2102P) was added and solid
A paint having a concentration of 44% was prepared. The paint obtained below
7g / m on one side of paper coated with paint²So that
After coating using an ear bar, it was dried.

This coated paper is used under normal conditions for one day (20 ° C, 65%
RH) after humidity control, by super calendar 100kg /
The treatment was carried out 3 times under a pressure of cm. Table 1 shows the quality of the coated paper thus obtained. Examples 1 to 4 and Comparative Examples 1 and 2 differ from Example 1 only in the pigment used, and the other conditions are the same. The measurement and evaluation conditions are described last. [Example 2] 100 parts of cross-linked starch SELEX (volume distribution average particle size 16.7 μm, coefficient of variation 0.41; Nitto Kagaku Co., Ltd.) was used as the pigment of the undercoat layer, and the coating amount was 20 g on one side.
A coated paper was obtained under the same conditions as in Example 1 except that / m ² was used. [Example 3] A coated paper was obtained under the same conditions as in Example 1 except that the pigment of the undercoat layer was mixed with Micropearl and Nuclay at 60 parts and 40 parts, respectively. [Example 4] As the pigment for the undercoat layer, 20 parts, 40 parts and 40 parts of micropearl, nuclay and calcium carbonate (Ace 25 (volume distribution average particle size 2.5 μm, coefficient of variation 0.70), Dowa Calfine Co., Ltd.) were respectively prepared. A coated paper was obtained under the same conditions as in Example 1 except that the mixture was mixed so as to form a part. [Comparative Example 1] Neuclai and Ace 2 were used as the pigment for the undercoat layer.
Example 1 except that 5 and 60 parts and 40 parts respectively
A coated paper was obtained under the same conditions as above. [Comparative Example 2] A coated paper was obtained under the same conditions as in Example 1 except that 100 parts of Neuclay was used as the pigment for the undercoat layer.

The results of Examples 1 to 4 are shown in Table 1, and the results of Comparative Examples 1 and 2 are shown in Table 2. As is clear from Table 1 and Table 2, the starch particles were used as a pigment for the undercoat layer in an amount of 10% by weight.
The coated paper containing the above is a gravure printing coated paper having high smoothness, few missing dots, and excellent halftone dot reproducibility. [Table 1] Example 1 Example 2 Example 3 Example 4 Pigment formulation of undercoat layer Starch pigment Micropar 100 parts Celex 100 parts Micropal 60 parts Micropal 60 parts (rice starch) (crosslinked starch) Concomitant pigment Kao Li down ─ ─ Nukurei 40 parts Nukurei 20 parts of calcium carbonate ─ ─ ─ ace 25 40 parts subbing coating weight g / m ² single-sided 10 sided 20 sided 10 sided 10 sheet gloss (%) 68.3 69.3 69.0 70.2 Oken smoothness (s) 3230 3100 2870 2680 Oken air permeability (s) 1250 850 1910 2260 Number of missing dots 5 8 10 12 Halftone dot reproducibility ◎ ◎ 〇 〇 〇

[0023]

[Example 5] Undercoat paint Micropearl as a starch pigment (Shimada Chemical Industry Co., Ltd.)
Sodium polyacrylate 0.4 parts and NaOH 0.1 part were added to 100 parts to prepare a pigment slurry, which was then gelatinized to form a phosphoric esterified starch (Neil gum A85, Abbe Co., Ltd.).
5 parts and 10 parts of SBR latex (JSR T-2113 gel content = 40%, Japan Synthetic Rubber Co., Ltd.) were added to prepare a coating material having a solid content concentration of 38%. The obtained coating material was applied to a medium-quality base paper 48 g / m ² using a Meyer bar so that the coating amount was 10 g / m ^{2 on} one side, and then dried. Top coat commercially available first-class kaolin (Rustler 90 (volume distribution average particle size
3.3 μm, coefficient of variation 0.66), 80 parts of Engelhard), 20 parts of light calcium carbonate (Brilliant-15 (volume distribution average particle size 1.9, coefficient of variation 0.73), Shiraishi Kogyo) 20 parts A pigment slurry was prepared by adding 0.4 parts of sodium polyacrylate and 0.1 part of NaOH, and further 3 parts of gelatinized phosphate esterified starch (neal gum A85) and 12 parts of SBR latex (JSR0617 gel content 52%). In addition, a paint having a solid content concentration of 44% was prepared. The resulting top-coat paint was applied to the above-mentioned undercoat paper with a Meyer bar so that one side was 7 g / m ^2, and then dried. This coated paper was conditioned at room temperature (20 ° C., 65% RH) for one day and then treated twice with a super calendar under a pressure of 100 kg / cm. Table 3 shows the quality of the coated paper thus obtained.

Examples 6 to 8 and Comparative Examples 3 and 4 were different from Example 5 only in the pigment used, and the other conditions were the same. [Example 6] As a pigment for the undercoat layer, crosslinked starch (SELEX,
Nitto Kagaku Co., Ltd.) 100 parts, coating amount 2 on one side
A coated paper was obtained under the same conditions as in Example 1 except that the amount was 0 g / m ² . [Example 7] As a pigment for the undercoat layer, micropearl and ace 2 were used.
A coated paper was obtained under the same conditions as in Example 5, except that 60 parts and 40 parts of 5 and 5 were used, respectively. [Example 8] As a pigment for the undercoat layer, micropearl and ace 2 were used.
A coated paper was obtained under the same conditions as in Example 5, except that 20 parts and 80 parts of 5 and 5 were used, respectively. [Comparative Example 3] A coated paper was obtained under the same conditions as in Example 5, except that 60 parts and 40 parts of Ace 25 and Rustler 90 were respectively used as the pigment of the undercoat layer. [Comparative Example 4] A coated paper was obtained under the same conditions as in Example 5, except that 100 parts of Ace 25 was used as the pigment of the undercoat layer.

The results of Examples 5 to 8 are shown in Table 3, and the results of Comparative Examples 3 and 4 are shown in Table 4. As is clear from the results, the coated paper containing 10% by weight or more of starch particles as a pigment in the undercoat layer has a high smoothness, is excellent in the inking during printing, and is at the same time excellent in the anti-ribster property. It is craft paper.

[Table 3] Example 5 Example 6 Example 7 Example 8 Pigment formulation of undercoat layer Starch pigment Micropale 100 parts Celex 100 parts Micropale 60 parts Micropale 20 parts (rice starch) (crosslinked starch) combined use Pigment Calcium carbonate ─ ─ Ace 25 40 parts Ace 25 80 parts Kaolin Undercoating amount g / m ² Single side 10 Single side 20 Single side 10 Single side 10 (Double side 20) (Double side 40) (Double side 20) (Double side 20) Blank paper Gloss (%) 56.7 53.1 56.7 55.5 Oken smoothness (s) 1290 1160 1160 1100 Oken air permeability (s) 1880 1290 2240 2520 Printing gloss (%) 61.4 5.9 .2 61.8 60.8 Ink receptivity 〇 〇 〇 〇 Blister generation temperature (° C) 260 280 260 240

[0028]

[Evaluation Method] The measurement and evaluation conditions were as follows. (1) White paper glossiness: angle 7 according to JIS-P8142
It was measured at 5 degrees. (2) Smoothness: J. TAPPI No5 Measured according to Oken type smoothness. The larger the value, the higher the surface smoothness and the smoother. (3) Air permeability: J. TAPPI No5 was measured according to Oken type air permeability, and was used as an index of voids in the coating layer. The smaller the value, the higher the air permeability and the more voids. (4) Miss dot: The number of defective ink transfer per 6.5 cm ^{2 in} 20% gradation part was measured after black printing with a gravure printing tester of Ministry of Finance Printing Bureau. The ink (OG-91 ink from Toyo Ink Mfg. Co., Ltd.) was adjusted to a viscosity of 15 seconds with a # 3 Zahn cup. (5) Halftone dot reproducibility: The halftone dot shape of the sample printed by the above method was visually evaluated.

◎ Excellent ○ Good △ Slightly inferior × Inferior (6) Printing Glossiness In accordance with JIS K5701, printing with an RI printing machine (Asahi Seisakusho) with an ink supply amount of 0.5 cc (Toyo Ink TK Mark V New Red M). Day and night (2
It was left at 0 ° C. and 65% RH). The printing glossiness of the sample left to stand was measured again at 75 degrees. (7) Blister generation temperature Similar to the printing glossiness, printing is performed on both sides with an RI printing machine and left in a normal state for one day (20 ° C. 65% RH). The left sample was immersed in a silicone oil bath and the temperature at which blisters were generated was measured. (8) Inking of ink: A sample whose printing glossiness was measured was visually evaluated.

Claims (1)

[Claims] 1. A multi-layer coated paper comprising an undercoat layer containing a pigment and an adhesive as main components and at least one overcoat layer containing the pigment and an adhesive as main components on at least one surface of a base paper. There is at least 10% by weight of pigment in the undercoat layer
A multilayer coated paper containing the starch particles of