JPS62206098A - Method for modifying 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 "Industrial Application Field" The present invention relates to a method for modifying printing paper using radiation curing technology, and particularly to a method for improving the stiffness of printing paper.

``Prior art'' Printing paper, including uncoated paper and coated paper, is most widely used in magazines, but in recent years there has been a change in the style of magazines. There is an increasing trend towards migration, visualization and colorization. For this reason, it is necessary to upgrade the quality while keeping costs down, and there is a noticeable trend toward thinner printing paper. However, as printing paper becomes thinner, the stiffness of the printing paper inevitably becomes weaker, leading to problems with the feeder on the printing machine and trouble on the folding machine during the bookbinding process.

In particular, for gravure printing paper, in order to improve the adhesion of halftone dots to the leather, in addition to the smoothness of the paper surface, the flexibility of the paper,
Cushioning properties are required, and as a result, the paper has the drawback of becoming particularly stiff.

On the other hand, in order to obtain printing paper with stiffness, printing paper is manufactured by, for example, size-pressing a material with a hard film such as starch or casein on the base paper, or mixing these with a pigment coating solution and coating it. There is a way. However, the printing paper obtained by this method is given paper stiffness during the drying process, which reduces the smoothing effect of calendering, super calendering, gloss calendering, etc. following the drying process, and resulting This results in printing paper with insufficient quality such as smoothness and gloss. Furthermore, when paper using gravure stamps is produced using these methods, although the effect of improving paper stiffness can be obtained, cushioning properties are reduced, resulting in unsatisfactory printed matter.

``Problems to be Solved by the Invention'' The purpose of the present invention is to produce printing paper that maintains the required quality such as printing effect and production efficiency, eliminates feeder troubles on the printing press, and improves folding machine suitability. The object of the present invention is to provide a method for modifying printing paper into a so-called stiff printing paper that has good page turning properties after binding.

"Means for Solving the Problems" The present invention involves supplying a coating liquid containing a radiation-curable monomer and/or oligomer to a base paper, drying it, and then performing any of the post-processes from the smoothing process to the bookbinding process. This method of modifying printing paper is characterized in that it is irradiated with radiation after the process has been completed.

"Function" In the present invention, the radiation-curing type upper layer and oligomer to be contained in the coating liquid may be those that can be polymerized and cured by radiation irradiation, for example, vinyl-based unsaturated double bonds in the molecule. Examples include compounds having one or more. Specific examples of such radiation-curable upper knobs include the following.

■ Ethylenically unsaturated mono- or polycarboxylic acids such as (meth)acrylic acid, itaconic acid, maleic acid, and their metal salts, ammonium salts, and amine salts.

■ (meth)acrylamide, N-methylol (meth)
Amide group-containing monomers such as acrylamide.

■ Methyl (meth)acrylate, hydroxyethyl (
Esters of ethylenically unsaturated carboxylic acids such as meth)acrylate and dimethylaminoethyl(meth)acrylate.

■ Esters of ethylenically unsaturated alcohols such as vinyl acetate.

■ Diesters of polyols such as ethylene glycol di(meth)acrylate and propylene glycol di(meth)acrylate and ethylenically unsaturated carboxylic acids.

■ Bisacrylamides such as N,N-methylenebisac-lylamide.

■Divinyl compounds such as divinylbenzene.

■ Triesters such as trimethylolpropane tri(meth)acrylate.

Further, specific examples of radiation-curable oligomers include the following.

■ Polyether (meth)acrylates such as polyethylene glycol di(meth)acrylate.

(2) Polyurethane di(meth)acrylates obtained by reacting hydroxyl group-containing (meth)acrylates such as 2-hydroxyethyl(meth)acrylate with diisocyanates such as tolylene diisocyanate, xylene diisocyanate, and hexamethylene diisocyanate.

■ Mono-, di-, and triester polyesters obtained from polybasic acids such as succinic acid, adipic acid, phthalic acid, maleic acid, and trimellidic acid and polyhydric alcohols such as ethylene glycol, propylene glycol, polyethylene glycol, glycerin, and pentaerythritol. Or polyester (meth)acrylates, which are poly(meth)acrylates.

(2) Epoxy di(meth)acrylates obtained by reacting an epoxy compound such as a bisphenol A-epichlorohydrin type epoxy compound with (meth)acrylic acid.

Among these radiation-curable monomers and oligomers, water-soluble compounds can be added to the coating solution as they are, and hydrophobic compounds can be used as an emulsion by emulsifying and dispersing them with a surfactant.

In addition, these radiation-curable monomers and oligomers may include carbonyl compounds such as benzophenone and acetophenone, azo compounds such as azobisisobutyronitrile, sulfur compounds such as benzothiazolyl sulfide, carbon tetrabromide, etc. It can also be used in combination with a polymerization initiator such as a halide or peroxide such as penzoyl peroxide.

In the present invention, radiation-curable monomers and oligomers can constitute a coating liquid alone, but generally they are mixed together with a water-based adhesive and further a pigment to form a size press coating liquid or a pigment coating liquid. prepared.

The amount of the radiation-curable monomer and/or oligomer to be added to the coating liquid may be determined as appropriate depending on the type of radiation-curable monomer and oligomer used, the type of intended printing paper, the amount of coating liquid applied, etc. Although it should be adjusted, if the coating amount of the radiation-curable monomer or oligomer is less than 0.5 g/d, no improvement in paper stiffness will be obtained, and if it is more than 10 g/rd, printability will decrease.
Generally, it is desirable to add the radiation-curable monomer and/or oligomer to the coating solution in an amount of 0.5 g/m=10 g/rd.

Examples of the water-based adhesives constituting the coating liquid include styrene/butadiene, styrene/acrylic, vinyl acetate/acrylic, ethylene/vinyl acetate, butadiene/methyl methacrylate, vinyl acetate/butyl acrylate, etc. Alkali-sensitive or alkali-insensitive adhesives such as copolymers and polyvinyl acetate, even polyvinyl alcohol, maleic anhydride/styrene copolymers, isobutyne/maleic anhydride copolymers, acrylic acid/methyl methacrylate copolymers, etc. Synthetic adhesives such as polymers, oxidized starch, etherified starch,
Various known adhesives include esterified starch, enzyme-modified starch, cold water-soluble starch obtained by flash drying them, and natural adhesives such as casein and soybean protein.

In addition, pigments include kaolin, clay, barium sulfate,
Examples include various pigments for coated paper such as light calcium carbonate, heavy calcium carbonate, ultra-fine grained heavy calcium carbonate, aluminum hydroxide, satin white, titanium dioxide, calcium sulfite, zinc sulfate, and plastic pigments.
These are appropriately blended depending on the properties of each pigment.

Furthermore, such a coating liquid may contain a dispersant, a thickener, a water retention agent, an antifoaming agent, a water resistance agent, a lubricant, a dye, a PHfi
Various auxiliaries such as J1 moderation agent and other various auxiliaries can also be used.

Further, in preparing the coating liquid, various mixing and stirring machines such as mixers, kneaders, ball mills, sand mills, etc. are appropriately selected and used depending on the type of the coating liquid.

In the present invention, the coating liquid containing radiation-curable monomers and/or oligomers is supplied to the base paper by impregnation or coating, for example, as a size press coating liquid or a pigment coating liquid, and is dried to form a high-quality paper. Or coated paper type printing paper is produced. Of course, when producing coated paper type printing paper, such radiation-curable monomers and/or oligomers may be contained in the size press coating liquid or both the size press coating liquid and the pigment coating liquid. You can also do it. In addition, when coating a pigment coating liquid, both sides or one side of the base paper are coated in a single layer or in multiple layers, but in this case, the formulation of the coating liquid composition on both sides may be changed as appropriate according to a conventional method. I can do it.

In addition, the amount of the coating liquid supplied to the base paper is generally 0.5 to 10 g/rrr for size press coating liquids, and 5 to 30 g/rrr per side for dye coating liquids (approximately 5 to 30 g/rrr per side). It is desirable to adjust.

In addition, there are no particular limitations on the method of supplying the coating liquid, such as size press coater, gate roll coater, etc.
, air knife coater, roll coater-1, paddle and inverter type blade coaters with beveled and bent blades, as well as various types of blade coaters such as bill blades, twin blades, chambrex, and short dwell coaters. A coating device is used.

The present invention involves applying radiation to the printing paper produced by supplying the above-mentioned coating liquid to the base paper and drying it after completing any of the post-processes from the smoothing process to the bookbinding process. It has important characteristics.

Here, examples of post-processes include various processes such as smoothing processes such as calendering, super calendering, and gloss calendering, embossing processes, various printing processes, folding processes, and bookbinding processes.

The radiation irradiation treatment of the present invention can be appropriately selected depending on the intended use of the printing paper, etc., including the case where there are multiple post-processes, after which the radiation irradiation treatment is completed. be.

However, if radiation treatment is applied after the gravure printing process, it is possible to obtain excellent gravure printing paper that has good ink adhesion at halftone dots, has very few misdots, and has strong paper stiffness, something that could not be achieved using conventional techniques. Particularly preferred.

Radiation used in the present invention refers to electromagnetic waves with a wavelength shorter than 400 nm, and specific examples include ultraviolet rays, electron beams, gamma rays, alpha rays, and X-rays. It is common to use When using ultraviolet light, irradiation with a mercury lamp, a xenon lamp, etc. can be employed.

In addition, when using an electron beam, for example, a scanning method, a curtain beam method, a broad beam method, etc. are used at an accelerating voltage of about 100 to 300 kV, and an acceleration voltage of 0.1 to 1
It is appropriate to perform treatment so that the dose is approximately 0 Mrad.

"Example" The present invention will be described in more detail with reference to Examples below, but it is of course not limited to these.

Note that parts and % in the examples represent parts by weight and % by weight, respectively, unless otherwise specified.

Examples 1 to 4 70 parts of kaolin (HT clay, manufactured by EMC), 30 parts of heavy calcium carbonate (Softon 1800, manufactured by Bihoku Funka Co., Ltd.) were mixed with 0.2 parts of sodium polyacrylate as a dispersant. A pigment slurry having a solid concentration of 70% was prepared by dispersing with a dispersing machine. After adding 7 parts of alkali-sensitive latex as an adhesive to this pigment slurry in terms of solid content, the following various electron beam curable tops or oligomers were added to the first layer.
After adding the coating amount as shown in the table (coating amount on both sides) and further adding 0.5 part of calcium stearate,
The pH was adjusted to 9.5 with NaOH, and water was added to obtain a pigment coating liquid with a solid content concentration of 60%.

The obtained coating solution was applied to the base paper for coating using a blade coater so that the dry coating amount was 26 g/rd on both sides, and after drying, smoothing treatment was performed using a super calender. Then, the irradiation dose was 4 at the location listed in Table 1.
Electron beam irradiation treatment was performed to obtain Mrad.

The glossiness (
The results are shown in Table 1.

Examples 1 and 2: Emulsion of polyester acrylate (Aroex M-8060, manufactured by Toagosei Co., Ltd.) Example 3: N,N-methylenebisacrylamide Example 4: Polyethylene glycol diacrylate (N
K-ester A-400, manufactured by Shin-Nakamura Chemical Co., Ltd.) Example 5 Polyester acrylate (Aloex M-806)
0, manufactured by Toagosei Co., Ltd.) was applied to a coating base paper using a size press so that the solid content was 2 g/cd. Next, gravure printing paper was prepared in the same manner as in Example 1, except that a coating liquid obtained by removing the polyester acrylate emulsion from the pigment coating liquid used in Example 1 was applied to this base paper for coating. , similarly evaluated. The result is the first
It is listed in the table.

Comparative Example 1 Gravure printing paper was produced in the same manner as in Example 1, except that a coating liquid obtained by removing the polyester acrylate emulsion from the pigment coating liquid was used, and the electron beam irradiation treatment was not performed. prepared and evaluated.

The results are listed in Table 1.

Comparative Example 2.3 Two types of gravure were prepared in the same manner as in Example 1, except that in the pigment coating liquid of Example 1, an emulsion of polyester acrylate was used in the coating amount as shown in Table 1. Printing paper was prepared and evaluated in the same manner. The results are listed in Table 1.

Comparative Examples 4 and 5 Two types of gravure printing papers were obtained in the same manner as in Example 1, except that the electron beam irradiation was performed at the locations listed in Table 1.

The quality of the obtained gravure printing paper was evaluated, and the results are listed in Table 1.

"Effects" As is clear from the results in Table 1, the gravure printing paper obtained in each example of the present invention has strong paper stiffness and fewer miss dots in gravure printing, making it an extremely excellent printing paper. there were.

Claims (2)

[Claims] (1) A coating liquid containing a radiation-curable monomer and/or oligomer is supplied to the base paper, and after drying, radiation is irradiated after any of the post-processes from the smoothing process to the bookbinding process are completed. A method for modifying printing paper. (2) Claim No. 1 (2) in which the post-process is a gravure printing process
Modification method described in section 1).