JPH05125695A - Coated paper for gravure printing - Google Patents

Abstract

PURPOSE:To obtain the subject coated paper having light weight, decreased mis-dot and excellent dot reproduction and gravure printability by incorporating a specific amount of a filler to a paper layer contacting with the coating layer of a specific coating base paper and incorporating a specific amount of hollow polymer particles in the coating layer. CONSTITUTION:The objective coated paper has a coating layer composed mainly of a filler such as clay and an adhesive such as a styrene-butadiene polymer and applied to a coating base paper having an areal weight of 20-50g/m<2>, preferably 23-40g/m<2>. The paper layer contacting with the coating layer contains 10-50wt.% of a filler such as calcium carbonate and the coating layer contains 5-40wt.% of hollow polymer particles (e.g. polystyrene particles) having an average particle diameter of preferably 0.8-2mum. The smoothness of the coating base paper is preferably 60-2,000sec.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated paper for gravure printing, and more particularly to a lightweight coated paper for gravure printing which has few misdots and is excellent in dot reproducibility.

[0002]

2. Description of the Related Art In recent years, the demand for high-quality printed materials such as photographs and paintings has been rapidly increasing. Therefore, it is possible to print beautiful photographs with good gradation reproducibility from highlights to midtones and shadows. However, the reproducibility of photographs and paintings is good, and gravure printing, which forms a beautiful printed surface, has been widely used. At the same time, the weight of gravure printed matter is reduced and the transportation cost is reduced for convenient handling. In order to reduce the demand, there is an increasing demand for weight reduction of coated paper for gravure printing.

On the other hand, in gravure printing, if the smoothness of the surface of the printed paper is low, misdots and halftone dots will be reproduced poorly, and the printing effect will be significantly reduced. In order to improve the smoothness of, the coated paper coated with high specific gravity inorganic pigments such as calcium carbonate and kaolin clay is subjected to a strong supercalender treatment, the coating amount is increased, and fine particle coating pigments are used. I have dealt with. However, in order to meet the demand for weight reduction of coated paper for gravure printing, the conventional method is used, so even if the basis weight of the coated base paper is reduced and the coating amount is reduced, it is sufficiently dealt with. However, there is a problem in that the smoothness of the coated paper is impaired, the number of misdots increases, the halftone dot reproducibility is poor, and the gravure printing characteristics deteriorate.

On the other hand, Japanese Unexamined Patent Publication No. 1-249861,
JP-A-2-140271, JP-A-2-140272, and JP-A-3-33296 disclose a coated base paper for the purpose of reducing the weight of the coated paper for gravure printing while maintaining the gravure printing characteristics. , A coated paper for gravure printing, which is provided with a coating layer containing hollow polymer particles as a coating pigment, maintains the smoothness of the coated paper, has few misdots, and has good dot reproducibility. It was not possible to sufficiently meet the demand for weight reduction while maintaining high gravure printing characteristics such as.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a coating paper for gravure printing having high gravure printing characteristics such as few misdots and good halftone dot reproducibility, and in particular, light weight and gravure printing coating material having high gravure printing characteristics. The purpose is to obtain craft paper.

[0006]

[Means for Solving the Problems] In order to solve the above problems,
The inventors have conducted a study focusing on the interrelationship between the characteristics of the coating material containing hollow polymer particles and the characteristics of the coated base paper. As a result, by combining a coating base paper containing a filler in a predetermined ratio and a coating layer containing hollow polymer particles, a lightweight gravure printing coated paper having high gravure printing characteristics can be obtained. The smoothness of the previous coated base paper is 60 to 200
It was found that the property of the coated paper for gravure printing was further improved by setting the time to 0 seconds.

Therefore, the present invention is a gravure printing coated paper in which a coating layer containing a pigment and an adhesive as a main component is provided on the coated base paper, and the paper layer is in contact with the coating layer of the coated base paper. Contains 10 to 50% by weight of filler, and the coated base paper has a basis weight of 2
There is provided a coated paper having a content of 0 to 50 g / m ² and a coating layer containing 5 to 40% by weight of hollow polymer particles. Further, according to the present invention, the smoothness of the coated base paper is 60 to 200.
The coated paper for gravure printing, which is 0 second, is provided.

The term "misdot" used in the present specification is a phenomenon in which intaglio ink is not sufficiently transferred to the paper surface to cause defects, and "defective dot reproduction" is gravure ink. Is transferred to the paper and spreads on the paper surface at the same time,
This is a phenomenon that causes poor reproduction of printed matter and also "smoothness".
In gravure printing, since printing is performed under a printing pressure higher than that of other printing methods, it means smoothness in a state compressed under this printing pressure.

The hollow polymer particles used in the present invention are
Average particle size 0.8 to 6 μm, preferably 0.8 to 2 μm
And an inner diameter of 0.5 to 0.9 times, preferably 0.6 to 0.9 times the outer diameter. The manufacturing method and components are not particularly limited as long as it is a hollow polymer having the above average particle diameter and the ratio of the inner diameter to the outer diameter, but the general manufacturing method and components are as follows. For example, the hollow polymer particles are (1) a two-step crosslinking method in which the crosslinked polymer particles are used as seeds, and polymers having different compatibility are polymerized and crosslinked on the seeds, or (2)
It can be manufactured by a method such as a method of manufacturing by polymer polymerization shrinkage. In this case, the polymerizable monomer is not particularly limited as long as it has radical polymerizability, and examples thereof include aromatic vinyl monomers such as styrene, α-methylstyrene, p-methylstyrene and halogenated styrene, Vinyl esters such as vinyl propionate, ethyl methacrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, lauryl acrylate, lauryl methacrylate and other ethylenically unsaturated carboxylic acid alkyl esters, butadiene, isoprene and other conjugated aliphatic dienes And the like, and styrene is particularly preferable. As the obtained hollow polymer, styrene and a styrene-acrylic copolymer are particularly preferable.

The coated paper pigment used in combination with the hollow polymer particles is not particularly limited as long as it is a conventionally used coated paper pigment. Specific examples include clay, kaolin, talc, aluminum hydroxide, light calcium carbonate, titanium dioxide, magnesium carbonate, alumina, activated clay, acid clay, diatomaceous earth, synthetic silica, zinc oxide, barium sulfate, calcium sulfate, Satin white, rake, plastic pigment, binder pigment,
Rice starch etc.

The coating pigment used in the coating layer of the present invention is prepared by mixing the hollow polymer particles and, if necessary, one or more kinds of the pigments. At this time, the ratio of the hollow polymer particles is 5% by weight or more, preferably 1% of the total coating pigment.
0-40% by weight, with the balance being the pigment. The reason for defining the proportion of the hollow polymer particles in this way is that if the hollow polymer particles are less than 5% by weight, it is impossible to improve the gravure printing suitability of the coated paper. This is because if it exceeds 40% by weight, the effect of the hollow polymer particles is saturated and at the same time calendar fouling occurs and the performance of the coated paper for gravure printing deteriorates.

The adhesive used in the coating layer of the present invention is not particularly limited, and known adhesives can be used. For example, styrene / butadiene type, styrene / acrylic type, vinyl acetate / acrylic type. , Ethylene / vinyl acetate based, butadiene / methyl methacrylic based, vinyl acetate /
Various copolymers such as butyl acrylate-based and alkali-sensitive or alkali-insensitive adhesives such as polyvinyl acetate, further, polyvinyl alcohol, maleic anhydride / styrene copolymer, isobutene / maleic anhydride copolymer, Synthetic adhesives such as acrylic acid / methacrylate copolymers, as well as oxidized starch, etherified starch,
Esterified starch, enzyme-modified starch and cold water-soluble starch obtained by flash-drying them, casein, soybean protein and the like can be selected and used alone or in combination of two or more.

The ratio of the adhesive used is 3 to 50 parts by weight, preferably 5 to 20 parts by weight, based on 100 parts by weight of the coating pigment. Further, if necessary, various auxiliary agents such as a dispersant, a viscosity modifier, a water retention agent, a water resistant agent, a lubricant, a dye, and a pH adjuster can be added to the coating composition for coating as needed. For the preparation of the coating composition for coating, various mixers, kneaders, mixing and stirring machines such as ball mills are appropriately selected and used according to the type of coating composition.

The coating material for forming the coating layer is prepared by sequentially adding the coating pigment, the adhesive and, if necessary, additives such as a dispersant while mixing with the mixing stirrer. By doing. The solid content concentration of the coating material for coating is generally adjusted to 30 to 80% according to the purpose.
The coating layer of the present invention is coated on both sides or one side of the coated base paper. In this case, the coating method is not particularly limited and has been conventionally used, such as an air knife coater, a roll coater, a bar coater, a rod coater, a bevel or a vent type blade coater, and further, a bill blade coater, a twin blade. Various known coating devices such as various blade coaters and short dwell coaters can be used. After coating, it is generally processed with a finishing device such as a super calendar or a gloss calendar.

The coating material for coating is applied so that the dry coating amount on one side is 4 to 20 g / m ² , preferably 4 to 12 g / m ² . The amount of coating is specified in this way is 4 g / m
^If it is less than ² , the effect of coating is not sufficiently obtained, while 20 g
This is because the effect of coating is saturated at / m ² . The coated base paper used in the present invention includes various wood pulps, DIPs, and synthetic pulps singly, or a pulp composition prepared by mixing a pulp and a filler, which is acidic or neutral papermaking by an ordinary paper machine. .. The filler internally added to the coated base paper is 10 to 50% by weight, preferably 10 to 30% by weight in the base paper. The predetermined amount of the filler and the hollow polymer particles constituting the coating layer have a synergistic effect, and the gravure printing suitability of the coated paper is improved. The content of the filler in the base paper should be 10
50% by weight means that if the filler is less than 10% by weight, it is not effective in improving the gravure printing suitability.
This is because if the content is more than 5% by weight, the amount of the filler will be too much and papermaking will be difficult.

According to the present invention, in addition to a usual single-layer coated base paper, a paperboard produced by performing papermaking,
Paperboard containing 10 to 50% by weight of a filler in the paper layer in contact with the coating layer can also be used as the coating base paper. Examples of the filler to be internally added to the coated base paper in the present invention include inorganic fillers such as calcium carbonate, talc, kaolin, acid clay, silica and titanium oxide, and organic fillers such as urea resin and non-gelatinized starch. it can. In addition to the above pulp and filler, various auxiliaries such as a sizing agent, a retention agent, a paper strength enhancer, a dye, a band, a pitch control agent, and an antifoaming agent are added to the coated base paper, if necessary. Further, if necessary, starch, polyvinyl alcohol, surface sizing agent and the like may be applied by a size press, a gate roll coater, a blade coater or the like in the paper making process.

The coated base paper has a basis weight of 20 to 50 g / m 2.
² , preferably 23 to 50 g / m ² , particularly preferably 2
It is 3 to 40 g / m ² . In this way, the lower limit of the coated stencil sheet should be determined if the sheet slab is less than 20 g / m ² .
This is because the paper strength is low and the papermaking is difficult due to the large amount of internal filler. In the case where the base paper thus produced has a smoothness of 60 seconds or more, the gravure is produced by the synergistic effect of the internal filler and the hollow polymer particles constituting the coating layer, even if the calender treatment is not intentionally performed. Printability is improved.
When the smoothness of the base paper produced as described above is less than 60 seconds, it is calendered with a machine calendar, a super calendar, a gloss calendar, or the like, and then a coating composition containing the hollow polymer particles is applied. The gravure printability of the coated paper obtained by coating is further improved. The calendered coated base paper has a smoothness of generally 60 to 2000 seconds, and preferably 100 to 10 seconds.
00 seconds. If the base paper smoothness is less than 60 seconds, the synergistic effect of the coating material containing the hollow polymer particles and the filler in the coated base paper will not be exhibited. The base paper smoothness is 100
If it is 0 seconds or more, it becomes difficult to apply the paint, or the paper strength of the base paper is excessively lowered to cause frequent paper breakage, which lowers the workability.

[0018]

Industrial Applicability According to the present invention, it is possible to obtain a coated paper having less misdots, excellent halftone dot reproducibility, and improved gravure printing suitability, and particularly a lightweight coated paper for gravure printing. ..

[0019]

EXAMPLES The present invention will be described in detail based on examples, but the present invention is not limited to the scope of these examples. In addition, "part" and "%" in the examples mean "part by weight" and "% by weight", respectively, unless otherwise specified. [Example 1] Papermaking of raw paper Pulp mixed with 65 parts of NBKP and 35 parts of LBKP was beaten to a Canadian freeness of 120 cc, and then light calcium carbonate PCX-850 (Shiraishi Industry Co., Ltd.) was used as a filler.
Was added in an amount of 340 kg per ton of pulp, and a base paper was made by a Fourdrinier paper machine according to a conventional method. At this time, using a size press in the middle of the paper machine, surface sizing was carried out with a 5% solution of oxidized starch Oji Ace A (Oji corn starch).
A coated base paper of g / m ² was obtained. The filler in the coated base paper at this time was 25.3% by weight. Furthermore, this coated base paper has 150
Super calendering was performed under the conditions of linear pressure of kg / cm and 7 nip. The smoothness of the wire surface of the obtained base paper was 220 seconds.

[0020] Paint preparation and coating color hollow polymer particles Ropeiku HP-91 (Rohm and Haas) <outer diameter 1.0 .mu.m, inner diameter 0.8 [mu] m; styrene - acrylic> 15 parts primary kaolin ULTRAWHITE -90 85 parts of dispersing agent SDA-40P (Somal) 0.4 parts PH adjuster Caustic soda 0.1 parts Defoamer Nopco 8034-L (San Nopco) 0.4 parts Modified starch Neil gum A85 (Abebe) 2 parts SBR latex T-2102P (Nippon Synthetic Rubber) ) 9 parts A coating solution was prepared based on the above composition so that the coating solid content concentration was 40 to 60%. After coating this coating solution on the wire side of the coated base paper using a Mayer bar so that the coating amount on one side after drying becomes 5 g / m ² and 7 g / m ² , Dried. Further, a test super calendar treatment was performed to obtain a coated paper of the present invention.

[Example 2] Urea resin Eupearl (Mitsui Toatsu Kagaku) was added as an internal filler for the coated base paper in an amount of 165 kg per ton of pulp, and the filler in the coated base paper was 12.2% by weight.
Was adjusted so that A coated paper was obtained in the same manner as in Example 1 except that the internal filler was changed.

[Embodiment 3] The eupearl filler paper produced in Embodiment 2 was subjected to a weak super calender treatment to obtain a smoothness of 6
A coated base paper of 0 seconds was obtained. The same coating material as that used in Example 1 was applied to the wire side of this coated base paper so that one side was 7 g / m ^2, and a coated paper was obtained in the same manner as in Example 1.

[Examples 4, 5 and 6] The pearlescent filler paper obtained in Example 2 was subjected to a strong super calender treatment to obtain a smoothness of 2.
65 seconds, HP-91 on the wire side 5,
A coated paper was obtained in the same manner as in Example 1 except that 10 and 20 parts of the coating composition was applied so that the amount of coating on one side was 7 g / m ² .

[Comparative Example 1] The eupearl filler paper obtained in Example 2 was subjected to a strong supercalendering treatment to a smoothness of 265 seconds, and the wire surface was coated with HP-91 at 7 g / m ² on one side. A coated paper was obtained in the same manner as in Example 1 except that the coating was performed as described above.

[Comparative Example 2] The calcium carbonate-filled paper produced in Example 1 was subjected to a strong super calendar treatment to obtain a smoothness of 2.
It was set to 65 seconds, and the wire surface was coated with a paint not containing HP-91 so that one surface was 7 g / m ^2, and Example 1 was repeated.
A coated paper was obtained in the same manner as in.

[Comparative Example 3] The amount of calcium carbonate added was 5.
A coated base paper was obtained in the same manner as in Example 1 except that the amount was reduced to 7%. This coated base paper was subjected to a weak super calender treatment to a smoothness of 61 seconds, and the wire surface of this coated base paper was HP-
A coated paper was obtained in the same manner as in Example 1 except that the coating composition containing 20 parts of 91 was coated on one side at 7 g / m ² .

As is clear from the results shown in Tables 1 to 3, the coating composition containing 5% by weight or more of the hollow polymer particles having a predetermined average particle diameter contains 10 to 50% by weight of the internally added filler. The coated paper coated on the coated base paper has remarkably improved reproducibility of misdots and halftone dots in gravure printing. Furthermore, when the smoothness of the base paper before coating is 60 seconds or more, the gravure printing suitability is improved. did. Moreover, the weight of the coated paper for gravure printing can be reduced by the present invention.

[Evaluation Method] Measurement and evaluation were performed under the following conditions. . (1) White paper glossiness: angle 7 according to JIS-P8142
It was measured at 5 degrees. (2) Smoothness: J. According to TAPPI. No. 5, it was measured using an Oken smoothness meter. (3) Miss dot: After printing black with a gravure printing tester, Ministry of Finance, Printing Bureau, the number of defective ink transfer per 6.5 cm ² at 20% gradation part was measured. The ink (OG-91 ink manufactured by Toyo Ink Co., Ltd.) was adjusted to a viscosity of 15 seconds with a # 3 Zahn cup. (4) Halftone dot reproducibility: The halftone dot shape of the sample printed by the above method was visually evaluated.

◎ Excellent ○ Good △ Slightly inferior × Inferior [Quality of coated paper] [Table-1] Example 1 2 Coating amount (one side g / m ² ) 7.0 5.0 7.3 4.7 Smoothness (s) 5500 4000 3200 2300 White paper gloss (%) 78.9 72.9 73.3 64.5 Missing halftone dots (pieces) 1 2 11 21 dots Reproducibility ◎ ○ ◎ ○ [Table-2] Implementation Example 3 4 5 6 Smoothness (s) 3000 2500 2700 3600 White paper gloss (%) 72.9 62.2 67.8 77.2 Missing halftone dots (pieces) 16 19 10 1 dot reproducibility ○ ○ ○ ◎ [ Table-3] Comparative Example 1 2 3 Smoothness (s) 2100 2200 2480 White paper glossiness (%) 55.0 60.1 76.2 Missing halftone dots (pieces) 47 35 49 Dot reproducibility × Δ △

Claims (2)

[Claims] 1. A coated paper for gravure printing, wherein a coated layer containing a pigment and an adhesive as a main component is provided on the coated base paper, and the paper layer in contact with the coated layer of the coated base paper contains a filler. ˜50% by weight, and the coated base paper has a basis weight of 20 to 50 g / m ² ,
A coated paper, characterized in that the coating layer comprises 5-40% by weight of hollow polymer particles. 2. The coated paper for gravure printing according to claim 1, wherein the coated base paper has a smoothness of 60 to 2000 seconds.