JPS60479B2 - Paper coating agent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coating agent for paper, and more particularly to a coating agent for paper suitable for producing coated paper for printing.

Coated paper for printing is widely used as art paper, machine coated paper, etc., and is generally made of clay as a main ingredient, with a coating agent containing a synthetic resin emulsion such as SBR latex and a thickening agent such as casein. By painting the surface of paper, ``it gives the paper a sense of beauty and improves its printability, but on the other hand, problems with blocking and texture have been pointed out.

Also, when cardboard is used as paper, the back side is made of waste paper, so the fluff comes off when it is rolled up and sticks to the surface, so to prevent this, for example, paraffin emulsion is added. However, this causes problems such as poor printing effects and excessive slippage. In order to overcome the drawbacks of the prior art as described above, the present inventors have made extensive studies and developed a coating agent that further contains tung sugar higher fatty acid ester in a paper coating agent containing synthetic resin emulsion and lake material. By using a 7-ing agent,
The inventors have discovered that it is possible to produce coated paper for printing with excellent anti-blocking properties, surface gloss, printing properties, etc., and have arrived at the present invention.

That is, the present invention resides in a coating agent for base paper of coated paper for printing, characterized in that it contains a synthetic resin emulsion, a paste, and a bear sugar higher fatty acid ester.

The present invention will be explained in detail below.

Examples of the synthetic resin emulsion in the present invention include styrene/butadiene latex, butadiene/methyl methacrylate latex, acrylic resin emulsion, etc., but styrene/butadiene latex is preferred from the viewpoint of cost and binder effect. .

Further, examples of the thickening agent used in the present invention include protein-based pastes such as casein, soybean protein, and animal glue, carbohydrate-based pastes such as starch and methylcellulose, and poval.

The sucrose higher fatty acid ester further added to the above synthetic resin emulsion and paste has an HLB value of 9 or less, more preferably 1 to 7, particularly preferably 4 to 6, and usually has 6 to 6 carbon atoms. It is an ester of 22, more preferably 10 to 2 hard higher fatty acids and sucrose. Specific examples of higher fatty acids include capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, and linoleic acid. H.L.B.
If the value exceeds 9, water may be absorbed and the surface of the paper may become cloudy, which is not preferable. The blending ratio of the sucrose higher fatty acid ester in the present invention is usually 0.1 to 1% by weight, preferably 0.5 to 3% by weight based on the solid content of the resin and the paste.
Weight%. Further, the blending ratio of the synthetic resin emulsion and the paste is appropriately selected according to conventional methods. That is, the ratio is usually 5:1 to 2:1. And these combinations are
For example, it is done as follows. Add sugar high fatty acid ester, dissolve it at about 6000 ml, add a small amount of alkali to partially saponify it, and then add hot water or water to 1 ml.
The emulsion has a solids content of 0 to 3% by weight.

Meanwhile, the synthetic resin emulsion and the paste are mixed, a certain amount of preservative such as sodium benzoate is added, and the mixture is thoroughly mixed.

Next, the emulsion of the olefin sugar higher fatty acid ester is added at the above ratio and mixed well. The paper coating agent thus obtained is usually applied to paper materials such as high-quality paper, medium-quality paper, and cardboard in the following manner.

Roll coaters, gravure roll coaters, knife coaters, bonding methods, etc. are used as coating methods.
A roll coater is most often used.

In other words, when using a roll coater, paper runs between a metal roll and a rubber roll to continuously apply the coating agent attached to the rubber roll, and the solid content is approximately 7 to 30 ta per coated area. You can change it freely.

In addition, the coating agent of the present invention can be appropriately used in combination with pigments or other additives such as viscosity reducing agents, antifoaming agents, etc. by a conventional method.

The coating agent of the present invention has the following effects.

The surface of paper using the coating agent of the present invention has unique surface characteristics and does not cause flocking, and for example, papers do not stick to each other even when cut with a cutter. In addition, since it has a suitable amount of slippage, it is extremely easy to separate sheets of paper one by one. Furthermore, the printability is extremely good, and no gluing defects occur when gluing.

EXAMPLES Hereinafter, the present invention will be further explained in detail with reference to Examples.
In addition, "parts" in the examples refer to "parts by weight."
shows.

Example 1 Styrene-butadiene latex (5% by weight) 6 parts, casein (2% by weight) 3 parts, Fuji sugar higher fatty acid ester (S-570 manufactured by Hishito) emulsion (15% by weight)
) 3 parts, sodium benzoate 0.01 part and water 6.9 dollars
A coating agent for paper was obtained by mixing the two parts.

This was coated on machine-coated manila paper to a thickness of 20 microns using a test roll coater and dried with warm air at 60 pm. The coating thickness after drying was 9 microns. The performance of the obtained coated paper was tested and
The results shown in the table were obtained.

Comparative Example For comparison with Example 1, in Example 1, instead of the sucrose higher fatty acid ester emulsion, polyoxyethylene nonylphenol ether with an HLB value of 14.1 (Nonion NS-212 manufactured by NOF ■) was used. A coating agent was obtained in the same manner as in Example 1, except that 3 parts of a 15% aqueous solution of .

The results are shown in Table 1 below in comparison with the results of Example 1. Table 1: Rice surface gloss (measured at JIS Z8741 angle of incidence of 45o) The rice surface size effect is related to the water resistance of the surface, and is determined as follows.

A small piece of sample coated paper in a 5% aqueous solution of ferric chloride. Float it face up and place it on top of it. Add 1 drop of 5% potassium cyanate aqueous solution Measure the number of seconds until a color change occurs.

The lower the water resistance, the faster it turns red.

Example 2 Methyl methacrylate-ethyl acrylate copolymer emulsion (5% by weight) 4 parts, polyvinyl alcohol aqueous solution (3% by weight) 5 parts, sodium benzoate 0.01 part, low sugar higher fatty acid Estel (made by Hishito S)
-370) 6 parts of emulsion (20% by weight) and 3 parts of water
．． A coating agent for paper was obtained by mixing 9 $9.

Claims (1)

[Claims] 1. A coating agent for base paper of coated paper for printing, characterized in that it contains a synthetic resin emulsion, a paste, and a sucrose higher fatty acid ester.