JPS61252393A - Coating composition for flexographic printing paper - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a coating composition used for producing coated paper suitable for flexographic printing, particularly flexographic printing using aqueous in-#. It is also ■.

[Conventional technology]

7 Rekin printing has the advantages that there is little decrease in the strength of the corrugated sheet due to printing, the flexo ink dries quickly, and it is possible to perform the next process and O-I/L-I. Printing method O is the mainstream in the process.

However, in recent years, the cosmetic and printing effects of dangale have been improved.
:' In addition to the conventionally used general liners, white liners, coated liners, and coated white goals have come to be used.

Among these, printing on the coated liner and coated white gale gives a beautiful appearance and an extremely excellent printing effect, but the surface of the coated layer has poor absorption and drying properties. In particular, belt stains occur in the folder gluer, and this causes stains on the printing surface, which is harmful when trying to speed up the production of multi-column mail. le
(Published by Shigyo Times, 10/7/30).

Therefore, in order to speed up the production of the corrugated gale, it is desired to improve the yield and drying properties of the ink on the surface of the coated layer.

Conventionally, in order to improve the drying properties of flexible ink O, porosity has been imparted to the coated layer. For example, by reducing the amount of binder Q blended or by adding a cationic substance to the coating composition. However, according to these O methods, although the drying properties are improved, the coating strength is reduced, and the printed surface is damaged due to scratches during transportation, and the printed surface is damaged, making it difficult to use as a decorative cardboard. The disadvantage is that the value is reduced to 0.

On the other hand, as a method to improve the drying properties of flexible ink O, it is effective to reduce the coating amount of coating composition Q, but with this Ll, the performance approaches that of uncoated paper, and the coated paper's unique printing , the cosmetic effect is not exhibited.

[Problem that the invention seeks to solve]

Therefore, an object of the present invention is to provide a transverse wave composition for flexographic printing, which is used for rolling up coated paper that has excellent absorbency and drying properties for 71/Kin ink and has high coating strength.

[Means for solving problems]

The present invention differs from the pigments conventionally blended in coating compositions for flexible printing paper, in that it has a nine-particle size distribution, particularly when expressed as a volume-based equivalent spherical particle diameter (hereinafter abbreviated as volume average particle diameter). The use of a pigment with a narrow particle size distribution and a specific particle size distribution can effectively solve the above problems, and at the same time, the printing gloss and printing ink density are high, and the printing effect can be greatly improved. It was made by

That is, in the present invention, the pigment has a volume-based Q equivalent spherical average particle diameter (volume average particle diameter) of 72 m or less, and a particle size of 5 μm.
It is characterized by containing a pigment whose total volume of particles having an equivalent spherical particle diameter exceeding 2 μm is not more than 30 cm, and the total volume of particles having an equivalent spherical particle diameter exceeding 2 μm is not more than 30 cm. 7 Requino coating composition for printing paper is provided.

The pigment of the present invention has the above-mentioned particle size distribution (1), but more preferably has a volume average particle size of O8j to 1, O
pm, and the total amount of particles having an equivalent spherical particle diameter of more than 2 μm is 020% by volume or less, and the total amount of particles having an equivalent spherical particle diameter of 72 m or less is less than 0% by volume. As the pigment having the particle size distribution of the present invention, a pigment conventionally used in coating compositions for paperboard may be re-pulverized so as to have the particle size distribution defined by the present invention.

Specifically, the pigments used in the present invention include inorganic pigments such as clay, kaolin, aluminum hydroxide, calcium carbonate, titanium dioxide, satin white, barium sulfate, zinc white plastic pigment, organic pigments, and natural pigments. (minerals) and synthetic pigments are exemplified, and any type of these pigments can be used as long as they are pigments with a volume-based particle size distribution O defined in the present invention.

These are contained as main pigments in an arbitrary Q amount among all the pigments in the coating composition, but usually ≠θ~1
00 volume tank, preferably jo to 100 volume tank is contained.

Therefore, the remaining pigment of OO body qII (preferably YOOO volume qII) is outside the range defined by the present invention, and can be used in combination with conventional coating pigments as auxiliary pigments.

The coating composition of the present invention usually contains a binder and may also contain various additives.

○ Binder: Any O binder such as styrene-butanoene emulsion (SBR), vinyl acetate yarn emulsion, acrylic emulsion, methyl methacrylate-butanoene yarn latex (MBR), acrylonitrile-butanoene yarn latex (NBR) can be blended with any Qil. I can do that. It is usually added in an amount of 70 to 2 parts by weight, preferably 20 to 20 parts by weight, per 100 parts by weight of the pigment.

○ Sonoike Q additive Calcium ether cellulose, Alki 759 f thorium, Sodium polyacrylate, Polyvinyl alcohol, 7
Water retention agents, dispersants, pH adjusters, lubricants, antifoaming agents, coloring pigments, fluorescent dyes, preservatives, etc. can be added.

The coating composition for paperboard of the present invention can be easily produced by weighing and mixing the above-mentioned components and stirring and mixing them using, for example, a mixer such as a Coles splitting machine or a Keday mill. and,
The resulting coating composition can be coated using a blade coater, rod coater, Cha/Bio/coater, air knife coater, etc.C>
1jXMKλ~lj&/nt After coating on one side and drying,
A coated paper is obtained by applying Q finishing such as curling/calendaring, straight curling/daring, and gloss curling/daring.

〔Effect of the invention〕

When a coated paper is manufactured using the coating composition of the present invention, excellent intensities are obtained during flexographic printing. It is possible to obtain a frame print that exhibits absorbency and drying properties, and has excellent abrasion resistance.

Next, the present invention will be explained with reference to Examples, but the present invention is not limited thereto. In the examples, 0 parts means parts by weight.

〔Example〕

Example / A coating composition for Shigin printing paper (solid content: 1 degree IAz) was prepared using various O pigments shown in Table 1 as pigments.

The composition was added to a liner with an absolute dry solid content of 2-209 m²/trl O. A coated paperboard was obtained by coating one side so that the coating was 9/rd. Coated paper whiteness, 7
The ink drying properties, print gloss, 7 print density, and abrasion resistance were investigated. The results are summarized in Table-2. In addition, Kronos KA-10 is Titano Dioxide 1 manufactured by Titano Industries, and SIRL-/11t10 is manufactured by Asahi Kasei Industries ID5.
BR emulsion (glass transition point Hiro ℃), Aron A70
jO is a Q/lyacrylic acid emulsion manufactured by Toagosei Chemical Industry Co., Ltd., and the cationic agent ED is a condensate of shrimp chlorhydride/, trimethylamine, and O.

Measurement method - White a: Measured using Ellefo (LK manufactured by Carl Zeiss).

0 Flexin ink drying property: Evaluated by undried ink transfer method using a RI-11 type printing machine (two-color machine manufactured by Mei Seisakusho). In other words, 7 Rekin ink (Toyo Ink 0FOtA red) was supplied / cc to the -color roll, the ink was kneaded, and immediately printed at 30 rprn, and at the same time, the undried ink was transferred to the transfer paper attached to the second color roll. .

77- of coated paperboard? The better the ink O absorption and drying properties, the lower the transferred ink O concentration, so visually evaluate the ink O concentration in descending order of transfer surface ink concentration as Excellent ◎, Good 01 Acceptable Δ, and Unsatisfactory × 7. It was made into a sex.

○Flexi printing gloss: R1 printing tester (manufactured by Mei Seisakusho)
Using flexo ink (Toyo Ink DFO Hiroaka) e/cc supply,
Perform printing. After this θ, the printed surface 0 glossiness t was measured at a measurement angle of 7l-7j-'.

(Gloss meter Gv-J o, new product of Murakami Color Research) 07
Printing density: Using an RI printing machine (manufactured by Mei Seisakusho), flexographic ink (Toyo (Nki DFO'A Red) / cc was supplied, and printing was performed after mixing the ink. After this, printing was performed using a Macbeth a meter. The red color density was measured and was determined to be 7rekin printing density.

○Abrasion resistance: Coated paperboard O# abrasion resistance was evaluated using a chemical photographic dyeing sturdiness tester. Sun the coated paperboard in the flow direction! The coated surfaces were rubbed against each other 300 times, and the appearance of removal of the #L composition on the surface was visually observed and evaluated based on the following criteria.

No removal θ◎ ○ Δ Significant removal × Pigment Q substance 1 base O particle size distribution is Coulter force
del TA n (Coalter Electro
It was measured using a T-T (manufactured by NICS 1NC-). The diameter of the nine apertures used is -2()prn s fdA fixed range is 0.4l-1prn, and the measurement solvent is /% NaCL.
An aqueous solution was used. When measuring the particle size, t-/l of sodium polyacrylate was added to each pigment, and the solid content concentration, 2
After adjusting to 0 cs, it was dispersed for 3 minutes using a household mixer (MX-760S, Matsushita Electric Industrial).

Figures 1 to 7 show the OIK volume distribution and volume distribution by particle size for the pigments in Tables 10A to 10G.

Incidentally, Pigment C is Q obtained by wet-pulverizing Pigment O, and is within the scope of the present invention. Wet grinding O conditions vary depending on the particle size before grinding, but for example, for heating powder 0, add sodium polyacrylate and adjust the solid content concentration. rOt
After IbVc141F, //rG patch 1I16 cylinder type/
Using Dograi/Goo (Igarashi Kikai Seizo Co., Ltd.), disc rotation speed 200 Orpm (bead diameter/~tmm)
It was obtained by wet grinding for one hour.

As is clear from Table λ, the coating compositions (l to 3) for flexible printing paper of the present invention exhibit excellent performance, but the compositions using conventional pigments (comparative examples/~j ), then
It can be seen that it is not possible to improve both the ink drying properties and the abrasion resistance in the air.

Furthermore, the print gloss and print density are also inferior to the products of the present invention. Furthermore, when a cationic agent is added (Comparative Example B), the flexible ink drying properties are improved, but the abrasion resistance is significantly reduced.

Example - Various coating compositions (solid content concentration 4t6%) were prepared using Kazei/ as a water retention agent, and this composition was
' / m'' s whiteness 67 arrogance 0 Coated on base paper for white gale with absolute dry solid content 6.01/lr? Suit 4-calender finish (1 pass at ls pressure 100 kg/cm). The raw materials used and the performance measurement method for the first generation were the same as in Example 1. The results are shown in Table 3.

Example 3 Coating composition in which the blending amount of pigment A was drastically changed (solid content concentration 4
L ochi) was prepared, and this composition was prepared with a total weight of 100 square meters/♂0,! i'
/rrl nonite liner with bone dry solid content of 7, j
f/ / one side] 1 & he obtained coated paper. The performance of this coated paper was evaluated in the same manner as in Example.

The results are summarized in Table 1.

From Table ≠, it can be seen that O is preferable so that the pigment contains jOφ or more of the pigment having the particle size distribution tU defined in the present invention.

[Brief explanation of drawings]

Figure 1 shows pigment A12) Cumulative volume distribution and particle size fj
The iS distribution is shown. Figure 1 shows pigment B, Figure 3 shows pigment C.
, Fig. 5 shows pigment 0, Fig. 5 shows pigment Eo1, Fig. 6 shows pigment FO1, and Fig. 7 shows pigment G, respectively. show.

Claims (1)

[Claims] 1. In a coating composition containing a pigment and a binder as main components, the pigment has a volume-based equivalent spherical average particle diameter of 1 μm.
m or less, particles with an equivalent spherical particle diameter exceeding 5 μm account for 5% by volume or less of the total, and particles with an equivalent spherical particle diameter exceeding 2 μm account for 30% by volume or less of the total. A coating composition for flexographic printing paper, characterized by: