JPH0673699A - Production of coated paper - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a method for producing coated paper which does not generate odor during printing heating so that the coated paper can be used as a coated transfer paper. [Constitution] 12% talc mainly made from bleached hardwood kraft pulp, 2% starch, 1.5% rosin size and 1 sulfuric acid band
% Of the base paper with a basis weight of 70 g / m ² produced with a Fourdrinier paper machine was heated and agitated for 30 minutes at a temperature of 60 ° C. and 85% of light calcium carbonate to obtain a residual monomer concentration of 17 ppm. A coating consisting of 13% of SBR latex and 2% of oxidized starch was coated with a blade coater so as to be 6 g / m ² on one side, dried, and then smoothed with a super calendar to obtain coated paper. [Effect] Since this coated paper does not generate odor after heating and printing, it is possible to provide a coated transfer paper.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing coated paper. More specifically, the present invention relates to a method for producing coated paper which does not generate odor after printing and printing.

[0002]

2. Description of the Related Art In general commercial printing and high-grade printing,
Offset printing is the mainstream, and coated paper obtained by coating a base paper containing cellulose pulp as a main component with a paint containing pigments and adhesives such as art paper and coated paper is used.

The reason for this is that the surface of the obtained coated paper is smooth, so that when it comes into contact with the blanket roll during printing,
This is because the ink transfer from the roll to the surface of the coated paper is good, the gloss of the image is high, and the color reproducibility is good.

The electrophotographic suitability of such coated paper was examined by Tsukaya et al. (Tsukaya, Ota: Non-impact Printer Paper, Paper and Pulp Technology Times, 27, No. 4 (1984) 31-36) and applied. Since engineering paper is physically smooth and evenly adheres to the photoconductor, a theoretically clean transfer image should be obtained, but when applied to an actual device, a rough image Is obtained.

In fact, in electrophotography, coated paper for printing has hardly been used because it has no advantage in image quality. However, recently, efforts have been made to use a coated paper as an electrophotographic transfer paper as described in JP-A-62-198876 and JP-A-62-198877. In addition, applications have also been developed in which the level of printing that requires coated paper is performed in advance, and then printing is performed with an electrophotographic printer.

[0006] Thus, when the coated paper produced by the conventionally proposed method is used as a transfer paper, an odor which is not present before use is remarkably generated after obtaining an electrophotographic image,
It is a big problem in practical use.

[0007]

DISCLOSURE OF THE INVENTION The inventors of the present invention have made earnest studies in view of the above situation, and as a result, investigated the cause of the odor generated after printing with an electrophotographic printer and applied the toner during heating when fixing the toner. The cause of odor is that the adhesive in the coating layer of the paper, especially the monomers remaining in the latex, vaporizes and scatters into the atmosphere.The concentration of the residual monomers in the latex used is at a certain level. It was found that the odor generated after printing is not a practical problem if it is suppressed below, and the present invention has been completed.

Accordingly, an object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide a method for producing a coated paper which does not generate an odor during printing heating so that the coated paper can be used as a coated transfer paper. To provide.

[0010]

DISCLOSURE OF THE INVENTION The present invention is a coated paper comprising applying a coating material containing a pigment and an adhesive as main components to the surface of a base paper containing cellulose pulp as a main component and performing a smoothing treatment. In the method for producing coated paper, the latex having a monomer concentration of 20 ppm or less remaining in the latex constituting a part of the adhesive is used.

In the present invention, the coated paper is such as hardwood bleached kraft pulp (LBKP), softwood bleached kraft pulp (NBKP), newspaper wastepaper, fine wastepaper, and / or deinked wastepaper from OA wastepaper (DIP). Cellulose pulp as the main component, filler,
A paint containing a pigment and an adhesive as a main component is applied to one or both sides of a base paper obtained by making a paper with a known wet paper machine by adding a paper-making chemical such as a sizing agent and a paper-strengthening agent, and then dried. After that, the coated surface is obtained by further smoothing with a gloss calender, a super calender, etc., but in order to impart suitability to running property and curl, known methods can be applied as they are to the raw material blending and papermaking methods. Kosho 55-47385
And Japanese Patent Laid-Open No. 57-81270).

Pigments for the present invention include calcium carbonate, aluminum hydroxide, zinc oxide, titanium dioxide,
Barium sulfate, calcined clay, silica, kaolin clay and the like are appropriately selected and used.

As the adhesive, one having a residual monomer concentration of 20 ppm or less in a latex such as styrene-butadiene latex or acrylonitrile-butadiene latex and other water-soluble adhesives such as polyvinyl alcohol, starch, methyl cellulose and carboxy are used. Methyl cellulose, hydroxyethyl cellulose and the like are appropriately selected and mixed and used.

In addition to the above, a dye or a colored pigment may be added to the paint to adjust the color tone, or a fluorescent dye may be used to improve the whiteness of the visual appearance. A dispersant or an antifoaming agent may be added for the purpose of adjusting.

To reduce the monomer concentration in the latex to 20 ppm or less, heat is applied to the latex while stirring at atmospheric pressure and the temperature is maintained at 50 to 95 ° C. for 60 to 180 minutes, during which the residual concentration of the monomer is determined by gas chromatography. It is advisable to set the necessary conditions while measuring. The most preferable method is to reduce the temperature to 40 at a reduced pressure of 300 to 500 mmHg.
When heated at ~ 80 ° C for 20-90 minutes, the monomer concentration in the latex can be easily brought to a level of 20 ppm or less.

The ratio of the pigment to the adhesive used in the coating composition of the present invention is in the range of 95: 5 to 60:40, preferably 90:10 to 70:30, in terms of dry weight of pigment: adhesive. If the usage ratio of the pigment exceeds 95%, the coating film strength will be weakened and not only the image glossiness will decrease, but also troubles may occur in the manufacturing process. If the proportion of the pigment used is less than 60%, sufficient smoothness cannot be obtained even with smoothing finishing, which is not suitable.

The coating amount is 5 to 30 g / m ² per side.
When the coating amount is less than 5 g / m ² , sufficient surface smoothness cannot be obtained, and when the coating amount exceeds 30 g / m ² , blistering may occur, which is not suitable.

As a coating method, a known method, for example, a method using a blade coater, an air knife coater, a roll coater or a bar coater is used.

For smoothing the coated paper, a known method, for example, a method of passing the coated paper between a chilled roll such as a super calender and a gloss calender and an elastic roll is used.

[0020]

The present invention will be described in more detail with reference to the following examples, but of course the present invention is not limited thereto. In the following,% means% by weight.

Example 1 Free weight of 460 ml of bleached hardwood kraft pulp with 12% talc, 2% starch, 1.5% rosin size and 1% sulfuric acid band was added to a known wet Fourdrinier paper machine to obtain a basis weight of 70 g / m ²
A fine paper was produced. Next, light calcium carbonate (Brilliance 15, average particle size 0.15μm, Shiraishi Kogyo) 85
%, A commercially available SBR latex (L-1537, manufactured by Asahi Kasei, residual monomer concentration 70 ppm) was kept at a temperature of 60 ° C. for 30 minutes while stirring, and the residual monomer concentration was reduced to 17 ppm. A known blade that uses a coating consisting of 2% of oxidized starch (Ace A, made by Oji Konstarch) as a base paper for the above high-quality paper so that the coating amount on one side is 6 g / m ² per weight of the absolutely dry base paper. It was coated with a coater, dried, and smoothed with a super calendar to obtain coated paper.

Example 2 Same as Example 1 except that the latex used in Example 1 was kept at 60 ° C. with stirring for another 30 minutes to reduce the residual monomer concentration in the latex to 7 ppm. To produce coated paper.

Comparative Example 1 A coated paper was produced in the same manner as in Example 1 except that a commercially available SBR latex (L-1537, manufactured by Asahi Kasei) was used without any treatment. The residual monomer concentration in the latex used was
It was 70 ppm.

The transfer papers obtained in Examples 1 and 2 and Comparative Example 1 were foamed into a size of 15 inches × 11 inches, and then 1,000 sets were continuously printed by a printer (Hitachi 6275, manufactured by Hitachi Ltd.) before printing. The odor of the transfer paper after printing was organoleptically evaluated, and when the odor that is not a problem in practical use is felt, the case where a odor that is a problem in practice is felt is indicated by x.

Table 1 shows the evaluation results of Example 1 to Comparative Example 1.

[0026]

[Table 1]

As can be seen from Table 1, the coated paper according to the method of the present invention does not feel a practically problematic odor both before and after printing, whereas the coated paper according to the conventional method has an extremely high odor after printing. I felt an unpleasant odor, which was a practical problem.

[0028]

The present invention has the effect of making it possible to provide coated paper that does not generate odor after printing.

Claims (1)

[Claims] 1. A method for producing a coated paper, which comprises applying a paint containing a pigment and an adhesive as a main component to the surface of a base paper containing a cellulose pulp as a main component and performing a smoothing treatment, wherein the adhesive is used. A method for producing a coated paper, characterized in that a latex having a residual monomer concentration of 20 ppm or less is used in the latex constituting a part of the above.