JP2005206977A - Method for producing coated paper for printing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a coated paper sheet for printing by which the coating in a high concentration can be carried out without accompanying rapid increase in the viscosity of a coating liquid at the coating, and the gloss of the print can be improved by 2-4%. <P>SOLUTION: This method for producing the coated paper sheet for the printing comprises formulating ≥30 mass% ground calcium carbonate obtained by wet-grinding solid components formulated with 0.55-0.65 mass%, based on the solid components, of a dispersant, based on a whole pigment, and coating the coating liquid having ≥65 mass% coating concentration on a base paper by using a blade-type coating device. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention is an A2 coated paper having a coating amount per side of 10 to 25 g / m ² coated by a blade type coating apparatus, and is high without causing a rapid increase in the viscosity of the coating solution during coating. The present invention relates to a method for producing a coated paper for printing which can be applied at a concentration and has an increased printing gloss.

  As a technique for improving printing gloss, it is generally known to increase the blending ratio of primary kaolin, to increase the latex ratio in the binder component, or to increase the amount of latex, but this may increase the cost. . In addition, increasing the latex ratio or increasing the amount of latex leads to a decrease in quality such as ink fillability and blister deterioration.

  It is possible to increase the printing gloss by increasing the coating concentration, but at the same time, the viscosity of the coating solution also increases, resulting in operational inconveniences such as streak and bleeding.

  Although it is possible to increase the print gloss by applying the coating on the same surface twice or more (see, for example, Patent Document 1), it is designed only to coat one layer or one front and back layer. To apply two or more layers in a coating apparatus, after coating once, the original material is coated again using the same coating apparatus or another coating apparatus, or the coater head Additional methods are required and both methods result in increased product costs.

Mixing organic pigments instead of inorganic pigments in the coating liquid is one of the means to increase printing gloss, but the concentration and viscosity of the coating liquid decrease, and the coating amount is comparable to A2 gloss. In order to apply a single layer using a coating system of the system, it is necessary to change the operating conditions such as reducing the pressure of the blade and increasing the coating speed, and the stability of the coating surface deteriorates and the drying load increases. It becomes a negative factor in operation.
JP 09-324395 A

The object of the present invention is to produce A2 type printing coated paper with a coating amount of 10 to 25 g / m ² coated on one side by means of a blade-type coating apparatus, and the viscosity of the coating liquid at the time of coating. The present invention provides a method for producing a coated paper for printing, which can be applied at a high concentration without causing a rapid increase in the printing speed and can improve printing gloss.

  As a result of intensive studies to solve the above problems, the present inventors have invented the method for producing a coated paper for printing of the present invention.

  That is, in the method for producing a coated paper for printing according to the present invention, 30 mass% of the heavy calcium carbonate obtained by wet-grinding 0.55 to 0.65 mass% of the dispersant with respect to the solid content in the total pigment. % Or more, and a coating liquid having a coating concentration of 65% by mass or more is applied to the base paper using a blade-type coating apparatus.

In the present invention, the viscosity of the coating liquid at the time of coating is abrupt in the manufacture of A2 type printing paper coated with 10 to 25 g / m ^{2 of} coating amount per side by a blade type coating apparatus. It is possible to perform coating at a high concentration without causing a significant increase, and it is possible to increase the printing gloss of the coated paper for printing by 2 to 4%.

  The manufacturing method of the coated paper for printing of this invention is demonstrated in detail below.

The printing coated paper of the present invention contains 30% by weight or more of heavy calcium carbonate in the total pigment, which is obtained by blending 0.55 to 0.65% by weight of a dispersant with respect to the solid content and wet-grinding. A coated paper for printing with a coating gloss of 2 to 4% by applying a coating amount of 10 to 25 g / m ^{2 on} one side with a blade-type coating device at a coating concentration of 65% by mass or more. is there.

  In the present invention, the dispersant used when wet pulverizing heavy calcium carbonate is not particularly limited, and a known dispersant can be used. For example, polycarboxylic acid, sodium polycarboxylate, ammonium polycarboxylate, synthetic polycarboxylate, isobutylene-maleic anhydride copolymer resin, sodium polyacrylate, sulfonated styrene resin, sulfonated styrene copolymer resin, polyvinyl alcohol , Modified polyvinyl alcohol, condensed phosphate and the like can be used alone or in admixture of two or more.

  Here, when the blending ratio of the dispersant is less than 0.55% by mass, the pulverization and dispersion efficiency of heavy calcium carbonate is lowered, and the coating liquid is adjusted to a high concentration of 65% by mass or more. The viscosity of the working liquid becomes high, streaks and bleeding are likely to occur when coating is performed with a blade-type coating apparatus, resulting in inconveniences in terms of operation and quality.

  On the other hand, even if the blending ratio of the dispersant exceeds 0.65% by mass, significant improvement in operation and quality can be expected due to heavy calcium carbonate pulverization, dispersion efficiency, and decrease in viscosity of the coating liquid. On the other hand, it is not preferable in actual production because the factor of cost increase becomes larger.

  When blending heavy calcium carbonate mixed with 0.55 to 0.65% by mass of dispersant with respect to the solid content at less than 30% by mass with respect to the total pigment, coating after adjustment The liquid viscosity is increased, streaks and bleeding are likely to occur during coating, resulting in inconveniences in terms of operation and quality. In addition, when trying to suppress streak and bleeding with less than 30% by weight, there is a method of coating by lowering the concentration of the coating solution. This is undesirable because it causes a reduction in printing gloss.

  When the concentration at the time of coating is less than 65% by mass, the phenomenon of sinking of adhesives and pigments occurs as in the case where the blending amount of heavy calcium carbonate is 30% by mass or less, and the printing gloss is lowered. It becomes a factor.

  The upper limit of the concentration of the coating solution that can be prepared is about 68% by mass based on the dispersion concentration of pigments known as raw materials for coated paper for printing, the concentration of adhesives such as latex and starch, and the concentration of other auxiliaries. .

  As pigments other than those prescribed in the present invention, kaolin is preferable, but light calcium carbonate, talc, calcined kaolin, aluminum hydroxide, satin white, titanium oxide, silica, zinc oxide, activated clay, silicon earth, lake, plastic You may mix and use a pigment etc.

  Moreover, the adhesive agent used for the coating liquid of this invention is not restrict | limited in particular, A well-known adhesive agent can be used. For example, various latexes such as styrene / butadiene, styrene / acrylic, vinyl acetate / acrylic, butadiene / methyl methacrylic latex, polyvinyl alcohol, oxidized starch, esterified starch, thermochemically modified starch, enzyme-modified starch, They can be selected from cold water soluble starch obtained by flash drying, casein, dextrin and the like, or can be used alone or in admixture of two or more.

  Copolymer latex includes aromatic vinyl monomers such as styrene and α-methylstyrene, aliphatic conjugated diene monomers such as 1,3 butadiene and 2-methyl-1,3 butadiene, acrylic acid, methacrylic acid, and the like. Copolymerizable monomers such as ethylenically unsaturated acid monomers, acrylonitrile monomers and ethylenically unsaturated carbobonic acid alkyl esters, ethylenically unsaturated carboxylic acid amides, other organic carboxylic acids and their derivatives A copolymer obtained by a known method, preferably a styrene / butadiene / methyl methacrylate / acrylonitrile copolymer.

  In addition, auxiliary agents such as a printability improver, a lubricant, a dye, and a water retention agent may be used in combination as appropriate.

  The base paper used in the present invention includes pulps such as chemical pulps such as LBKP and NBKP, mechanical pulps such as GP, PGW, RMP, TMP, CTMP, CMP, and CGP, and pulps such as waste paper pulp such as DIP. Contains various additives such as heavy calcium carbonate, talc, clay, kaolin, sizing agent, fixing agent, retention agent, cationizing agent, paper strength enhancer, etc. The

  The method of applying the coating composition according to the present invention to the base paper is limited to the blade method, but the type of the blade coater is not particularly limited, such as a short dwell coater, a roll applicator type, a nozzle applicator type, etc. Various blade coaters can be used, and it can be applied by the bevel method or the vent method. The coated paper thus coated and dried is subjected to super calendar, gloss calendar, soft calendar processing, and the like.

  Hereinafter, the effects of the present invention will be described in more detail by way of examples, but the present invention is not limited thereto. In addition, the part and% in an Example show a mass part and the mass%, respectively. The various measured values in the examples were obtained by the following method.

<Print gloss>
Using an RI printing aptitude tester, indigo, red, and yellow ink (soybean oil ink and mineral oil ink manufactured by DIC, 0.3CC) is printed in solid color, left standing for a day and night, and then Murakami-style digital in accordance with JIS Z8741. The glossiness of the coated paper was measured at an angle of 60 degrees using a gloss meter (model GM-3D).

<High shear viscosity of coating liquid>
The high shear viscosity at 28 ° C. of the coating solution was measured at 1000 rpm with a rheometer IGK-120 manufactured by Nippon Rheology Equipment Co., Ltd.

<Coating suitability>
Is it possible to apply without any operational problems without increasing the viscosity of the coating liquid when each coating liquid prepared with the above-mentioned formulation is applied at a coating speed of 1000 m / min with a blade coater? , “O” to “X” were observed.

<Base paper formulation>
LBKP 40 parts NBKP 40 parts GP 20 parts

<Inner medicine>
Calcium carbonate 6 parts Commercially available cationic starch 2 parts Commercially available cationic polyacrylamide yield improver 0.02 parts Pulp and filling chemicals are prepared as described above, and a base paper for coating having a basis weight of 54 g / m ² is obtained using this. It was.

<Dispersion of self-made heavy calcium carbonate>
Dispersant (sodium polyacrylate + synthetic polyacrylate) 0.58 parts heavy calcium carbonate (Vietnamese raw stone) 100 parts were pulverized to a mean particle size of 1.2 μm using a wet pulverizer, and a slurry with a concentration of 75% Got.

<Coating solution adjustment method>
Commercially available primary kaolin (UW90) 55 parts Self-made heavy calcium carbonate 45 parts Commercially available polyacrylic dispersant 0.1 parts Commercially available phosphate esterified starch 2.5 parts Commercially available styrene / butadiene latex 10.0 parts Commercially available calcium stearate 1 part Adjust to pH 9.7 with sodium hydroxide

The coating liquid having the above composition was adjusted to a concentration of 65%, and using a blade coater in which a ceramic blade was mounted on the above-described base paper for coating, 12 g / m ^{2 was} applied per side at a coating speed of 1000 m / min. Dried. Subsequently, a super calendar process was performed under the conditions of a linear pressure of 290 kg / cm and a speed of 700 m / min to obtain a coated paper for printing of Example 1.

  A coated paper for printing was obtained in the same manner as in Example 1 except that the blending amount of the self-made heavy calcium carbonate dispersant was changed to 0.55 part.

  A coated paper for printing was obtained in the same manner as in Example 1 except that the blending amount of the self-made heavy calcium carbonate dispersant was 0.65 part.

  A coated paper for printing was obtained in the same manner as in Example 1 except that the blending amount of the self-made heavy calcium carbonate in the coating liquid blend was 30 parts.

  A coated paper for printing was obtained in the same manner as in Example 1 except that the blending amount of the self-made heavy calcium carbonate in the coating liquid blending was 60 parts.

  A coated paper for printing was obtained in the same manner as in Example 1 except that sodium polycarboxylate was used as the dispersant for the self-made heavy calcium carbonate.

(Comparative Example 1)
A coated paper for printing was obtained in the same manner as in Example 1 except that the blending amount of the self-made heavy calcium carbonate dispersant was 0.50 part.

(Comparative Example 2)
A coated paper for printing was obtained in the same manner as in Example 1 except that the blending amount of the self-made heavy calcium carbonate in the coating liquid blend was 25 parts.

(Comparative Example 3)
A coated paper for printing was obtained in the same manner as in Example 1 except that the coating liquid was coated at a concentration of 64%.

  About the coating paper for printing obtained by the said Example and comparative example, the kind and compounding quantity of a dispersing agent, the compounding quantity of the self-made heavy calcium carbonate (heavy calcium) contained in a coating liquid, coating liquid density | concentration The evaluation results are shown in Table 1 below.

Rating:
From the results of Table 1 above, in Examples 1 to 6, the amount of the dispersant for the self-made heavy calcium carbonate, the blending amount of the self-made heavy calcium carbonate in the coating solution, and the coating concentration of the coating solution are set according to the present invention. Good results were obtained with respect to the high shear viscosity and printing gloss of the coating solution using the one in the range.

In the present invention, the viscosity of the coating liquid at the time of coating is abrupt in the manufacture of A2 type printing paper coated with 10 to 25 g / m ^{2 of} coating amount per side by a blade type coating apparatus. The present invention can be applied to a method for producing a coated paper for printing that can be applied at a high concentration without causing a significant increase.

Claims (1)

Heavy calcium carbonate blended with 0.55 to 0.65% by weight of dispersant with respect to the solid content and blended in an amount of 30% by weight or more of the total pigment to give a coating concentration of 65% by weight or more A method for producing a coated paper for printing, characterized in that the working liquid is coated on a base paper using a blade type coating device.