JPH01171892A - Production of high-gloss printed matter - Google Patents

Abstract

PURPOSE:To obtain a high-gloss printed matter having excellent collapse properties, by applying a specified coating agent for press working to a printing paper immediately after printing in a water-based ink, and continuously subjecting the printing paper to hot press working in the condition where water content is left in the paper. CONSTITUTION:A dispersed material of a water-soluble resin having a glass transition temperature of 60-130 deg.C is used as a coating agent for press working. For example, styrene is subjected to emulsion polymerization by using an ammoniacal aqueous solution of a methacrylic resin as a dispersant, and the resultant product is used as the coating agent. By using a two-color flexographic rotary press, a UF Manila paper is continuously printed in a water-based flexographic ink (used as the first color) and coated with the coating agent (used as the second color). Then, the paper is pressed by a hot roller at a temperature of 110 deg.C on a luster press. If the printed paper is subjected to drying before the press working, ununiform luster is generated.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for producing ultra-glossy printed matter, in particular immediately after printing with a water-based printing ink, applying a water-based press coating and subsequently The present invention aims to provide a method for producing ultra-glossy printed matter, which is characterized by hot-pressing.

<Conventional technology> Conventionally, in the field of high-quality printed materials that use various types of paper as printing materials, offset printing using oil-based inks or gravure printing using solvent-based gravure inks has been mainstream, and water-based inks have been used almost exclusively for printing on cardboard and paper bags. It was used in the field of paper carton printing, such as

However, in recent years, improvements have been made in printing machines and printing plate materials, as well as improvements in water-based inks, and process printing using water-based inks has come to be performed.Even in the field of paperboard printing such as cardboard and cartons, advanced printed matter using multicolor overprinting is now being produced using water-based inks. Increasingly, this is done using ink.

However, because it does not satisfy the advanced market demands for cosmetics and luxury, the use of printed materials using water-based inks is severely limited, and in reality, offset printing using oil-based inks, which has been conventionally used, etc. was the dominant one.

In the case of offset printing, it is superior to water-based inks in terms of gloss, but because it uses oil-based inks, there is an operational problem in that it takes a long time for the ink to dry. Moreover, when offset ink is used to print on paperboard or the like with poor smoothness, the super gloss required for high-quality printed matter cannot be achieved. Therefore, after offset printing, an overcoating varnish was applied, vinyl coating, or press processing was performed. However, in order to obtain super gloss, simply applying an overcoating face or applying vinyl is not sufficient, and it is necessary to perform a -less process.

Conventionally, in press processing, a resin solution consisting of solvent-based vinyl chloride/vinyl acetate resin is applied to the printed surface, and after drying, a mirror plate made of stainless steel or the like is layered, and a flat press or endless press is used to create a glossy finish. The grant was being made.

<Problems to be solved by the invention> However, in the case of offset printed matter, it takes a long time to dry after printing, and since it is sheet-fed printing, press processing cannot be performed continuously, resulting in poor work efficiency. Moreover, since a solvent-based coating agent is used as a coating agent for press working, there is a problem of fire hazard in terms of the working environment. On the other hand, in recent years, water-based coating materials have been used as coating materials for press processing, and although the above problems have been solved, there are still problems with the efficiency of printing operations, and furthermore, oil-based inks and water-based Problems have arisen in compatibility with coating materials for press processing, such as uniformity, swimming, repellency, adhesion, abrasion resistance, and transparency of the coating. The present invention aims to provide a method for producing printed matter that is superior in workability and has ultra-glossy properties that solves these problems.

Means for Solving the Pressure Pressure〉 That is, the present invention continuously applies a water-based press coating material to printed matter immediately after printing with a water-based printing ink, and then hot-presses the printed matter. It is an object of the present invention to provide a method for producing ultra-glossy printed matter, which is characterized by performing the following steps.

Hereinafter, the method for producing a super glossy printed matter according to the present invention will be explained in more detail.

First, the printing material used in carrying out the method of the present invention is preferably paperboard such as coated cardboard, K liner, jute liner, etc. used for printing on folding containers such as corrugated boards and cartons, art paper, coated paper, or other paperboards. Thin paper can be used by taking into account the drying properties of the water-based ink and the expansion and contraction of the paper due to the water-based ink.

In the case of the present invention, it is preferable to use paper that does not cause misregistration even when the paper swells.

In addition, as the water-based ink to be printed on the above-mentioned printing material, aqueous alkaline solutions such as conventionally used acrylic resin, styrene/Fray acid resin, styrene/maleic acid resin, etc., and/or acrylic, styrene/acrylic, styrene / An emulsion such as shellac can be used as a binder.

When printing with water-based ink on these printing materials, printing can be performed using a flexo or gravure printing machine.

In addition, the water-based press processing coating material applied to the above-mentioned printed matter has a glass transition temperature (Tg) of 60 to 130.
Preferred are coating compositions containing as an essential component an aqueous resin dispersion in the range of .degree. In press processing,
Since the process is usually carried out in a temperature range of 90 to 120°C, if the Tg of the aqueous dispersion is less than 60°, the heat resistance will not be sufficient during press working, and if the Tg is 130°C or higher, the coating film will not be formed during press working. In this case, the desired amount of ultra-glossy printed material cannot be obtained due to insufficient crushing.

Although it is possible to increase the temperature during press processing to improve the crushing, this may cause shrinkage of the paper, misregistration during cutting, and may even cause deterioration of paper strength. This can cause problems, so it is desirable to keep the temperature of press working as low as possible.

First, when obtaining an aqueous resin dispersion having a specific glass transition temperature, which is the main component of the coating composition used in carrying out the method of the present invention, consider the glass transition temperature of the vinyl monomer homopolymer exemplified below. However, it is possible to obtain an aqueous resin dispersion having a desired glass transition temperature by setting the polymerization ratio of the nil monomer when used, respectively, based on conventionally known approximate formulas. −
On the other hand, an aqueous resin dispersion with a desired Tg can also be produced by a so-called polymer blend, which is a mixture of an aqueous resin dispersion made of a polymer with a relatively high Tg and an aqueous resin dispersion made with a polymer with a relatively low Tg. can be obtained. Examples of vinyl monomers for obtaining such an aqueous resin dispersion include the following. Nyl monomers that can be used to obtain homopolymers with a relatively high Tg include acrylic and nyl monomers such as acrylic acid, methacrylic acid, methyl methacrylate, and ethyl methacrylate, and styrene and nil monomers such as styrene and α-methylstyrene. As vinyl monomers with relatively low Tg, alkyl esters of acrylic acid or methacrylic acid other than the above-mentioned methyl methacrylate and ethyl methacrylate, such as methyl, ethyl, propyl, isopropyl, n-butyl, S-butyl, t-butyl, hexyl , 2-ethylhexyl, decyl, lauryl, and the like can be exemplified by esters having a linear or side-chain alkyl group. In addition, it is also possible to copolymerize other vinyl monomers in addition to the above-mentioned monomers, such as unsaturated monotarponic acids such as crotonic acid, and those containing at least one N-substituted methylol group such as itacon N-p)-xymethylacrylamide. Acrylic acid amide derivatives, glycol-necked acrylic acid or methacrylic acid mono- or diesters such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, or monomers such as glycidyl ether of acrylic acid or methacrylic acid, or acrylonitrile, chloride Examples include vinyl, vinyl acetate, vinyl propionate, and vinylidene chloride. Among these exemplified vinyl monomers, those whose main components are acrylic acid, methacrylic acid, or their alkyl esters, and styrene vinyl monomers are preferred. To obtain an aqueous resin dispersion from these monomers, the monomers mentioned above are emulsion-polymerized using a hydrophilic catalyst such as ammonium persulfate, potassium persulfate, hydrogen peroxide, or a redox catalyst by the most known method to stabilize the dispersion. It is sufficient to disperse it, and an emulsifier can be added if necessary.

As an emulsifier, a mixture of vinyl monomers can be copolymerized in an emulsified state in the presence of an anionic or nonionic surfactant, but numerically speaking, the use of a low-molecular-weight surfactant may affect the water resistance of the resulting film, etc. If water resistance is particularly required, polymeric anionic activators are suitable as emulsifiers because they may have a negative effect.

The aqueous resin dispersion used in the present invention also has excellent performance by using such an emulsifier. Examples of such polymeric emulsifiers include conventional aqueous solutions of alkali-soluble resins such as shellac and (meth)acrylic or maleic acid copolymers having carboxyl groups.

Regarding the coating composition for press processing used in the present invention, it is necessary to use an aqueous resin dispersion having a relatively high glass transition temperature (60 to 130°C). As a dispersant used during polymerization,
When a homopolymer with a high glass transition temperature such as acrylic acid, methacrylic acid, or styrene is formed, other monomers are emulsion-polymerized using a relatively large amount of an aqueous solution of an alkali-soluble resin composed of a nyl monomer using a conventional method. Preferably.

As the alkali used for water-solubilizing the alkali-soluble resin, known alkalis can be used, such as ammonia, organic amines such as trieta-nolamine, monoethanolamine, etc.; Highly alkaline is best.

In addition, the following additives can be added to the composition as needed, and these additives include water-soluble adhesives to assist in adhesion to the printed surface, and acrylic resins. , a rosin-modified maleic acid resin, a styrene-maleic acid resin, an aqueous solution of an alkali-soluble resin such as shellac can be added. In addition, polyethylene-based wax sheets to improve abrasion resistance, higher fatty acids such as stearic acid, higher alcohols such as cetyl alcohol, and surfactants such as phosphoric acid esters are used to improve peelability during press processing. Agents etc. can be used.

In addition, as inorganic fillers, silica powder, silica gel, quartz powder, alumina, glass powder, talc, clay,
Calcium carbonate, magnesium carbonate, zinc white, barium sulfate, etc. can be added, but the amount in the coating composition of the present invention is 5.0% by weight or less, more preferably 0.5 to 0.5% by weight.
It is necessary to contain it in a range of 3.0% by weight.

If the content of the inorganic filler exceeds 5.0% by weight, a problem arises in that high gloss cannot be obtained.

When manufacturing such a coating composition for press processing, the above additives are simply mixed into the aqueous resin dispersion, or when an inorganic filler is added, a conventional dispersion machine is used. It can be obtained by finely dispersing it using.

Further, as other additives, coloring agents such as dyes and pigments can be added, and it is also possible to obtain a colored glossy film.

The coating agent for press processing consisting of the above-mentioned components can be applied to printed matter immediately after printing using water-based flexo ink or water-based gravure ink, etc. by means such as roll coating, curtain coating, spray coating, or gravure or flexographic printing machines. It can be applied to the entire surface or the necessary parts using the following.

Since the water-based ink used in the method of the present invention has relatively excellent drying properties, it may be carried out in-line with the water-based ink printing process, or the last printing unit of a flexo or gravure printing machine may be used for press processing. It can also be used for coating coatings.

The printed matter coated with the coating composition for pressing is subsequently glossed with a hot roller used in pressing.

The temperature of the hot roller is preferably 90 to 120°C and the pressure is 150 to 350 Kg/cm.The press processing apparatus is conventionally used as an endless press machine. Any conventional press can be used, but when carrying out the method of the present invention on a web-shaped printing paper, a press for imparting gloss of 2 to 3 II! or more is preferable to a single press machine. A type with continuous rolls is effective.For press processing, immediately after applying the coating for printing and press processing, the moisture content in the printing paper promotes crushing and gloss. It is important to increase the

Therefore, it is preferable to perform coating and press processing continuously, but if the paper to be printed is dry and contains some moisture, it is not possible to perform only the press process independently. It is possible.

Effect> When using the water-based ink and water-based coating material for press processing shown in the present invention, since the drying speed of the water-based ink is fast, printing, coating, and press processing can be performed continuously. It has excellent work efficiency.

Furthermore, since it is a water-based coating, there are no problems such as swimming or repelling, and since it can be applied uniformly, uneven gloss does not occur. It also has the effect of excellent adhesion between the ink and the coating material, and excellent resistance such as abrasion resistance.

Furthermore, immediately after applying the water-based ink and water-based press coating, the printing material is in a swollen state with water, and by pressing with a hot roller in this state, the printing material itself is smoothed and dried. This is more accelerated than when a printing medium is used, and printed matter with a high degree of gloss can be obtained at a lower temperature.

This will be explained in detail below with reference to Examples.

<Example> Dispersion Production Example 1 An ammonia aqueous solution of an alkali-soluble resin consisting of 53% by weight of methacrylic acid, 23% by weight of methyl methacrylate, and 24% by weight of styrene was used as a dispersant, and for 66 parts by weight of the resin content of the dispersant, 34 parts by weight of styrene is added and emulsion polymerization is carried out by a conventional method to obtain aqueous resin dispersion A. The resulting dispersion A has a glass transition temperature of about 125° C. for a 37% solids dispersion by weight.

Dispersion Production Example 2 Same as Production Example 1, 28% by weight of methacrylic acid, 4% by weight of acrylic acid, 7% by weight of methacrylate, ethyl acrylate.
) An ammonia aqueous solution of an alkali-soluble resin containing 61% by weight is used as a dispersant, and 88 parts by weight of styrene is emulsion polymerized with respect to 12 parts by weight of the resin content of the dispersant to obtain an aqueous resin dispersion B. The resulting dispersion B has a solids content of 55% by weight and a glass transition temperature of about 89°C.

Dispersion Production Example 3 Using acrylic resin (Joncryl 67) as the alkali-soluble resin and using its alkaline aqueous solution as the dispersant, 54 parts by weight of inbutyl methacrylate was added to 10 parts by weight of the resin content of the dispersant. , 36 parts by weight of styrene was emulsion polymerized by a conventional method to obtain an aqueous resin dispersion C.
The solid content of dispersion C is 441%, and the glass transition temperature is about 67.
It is ℃.

Production Examples 1 to 6 of Coating Agents for Press Processing Using 80 parts by weight of each of the dispersions A to C obtained in Dispersion Production Examples 1 to 3, ethanol, 10 parts by weight, petitcarbitol, 5 parts by weight, polyethylene wax. , 1 part by weight,
1 part by weight of a phosphate ester mold release agent and 3 parts by weight of water are mixed to prepare coating materials for press working (1 to 3).

Examples 1 to 3 Using a two-color flexo rotary printing press, water-based flexo ink was applied as the first color and each coating agent (1 to 3) was applied as the second color on Honshu Paper's UF Manila paper (230 g/m''). Printing and coating are performed continuously.

Subsequently, using a raster press machine, the temperature was 110°C.
Pressing was performed with a hot roller at a pressure of 300 kg/- and a speed of 3011/min to impart gloss. The gloss after pressing is measured using a gloss meter (incidence angle 60°)
The measured values are shown in Table 1.

Comparative Examples 1 to 6 In the same manner as in Example 1, water-based flexo ink and coating materials 1 to 3 were printed and coated on UF Manila paper, and the ink and coating materials were completely dried using a dryer attached to the printing machine. . After drying, press processing was performed under the same conditions as in Example 1,
The gloss was measured in the same manner, and the results are shown in Table 1 (referred to as Comparative Examples 1 to 3). On the other hand, using the same dried printed matter, press processing was performed with the hot roller temperature set at 130°C and other conditions the same, and the gloss was measured in the same way.
The results are added to Table-1.

Comparative Examples 7 to 9 The same UF Manila paper as in Example 1 was printed with lithographic sheet-fed ink, left for one day to completely dry, then coatings 1 to 3 were applied, and after drying, the same roller as in Example 1 was applied. Pressing was performed at different temperatures, pressures, and speeds, and the gloss was measured in the same manner as shown in Table 1.
It is written in

Other Evaluation Tests The printed matter after press processing obtained in Examples 1 to 3 and Comparative Examples 1 to 9 was tested for the degree of uneven gloss and cellophane adhesiveness, and the results are shown in Table 1.

The evaluation will be performed in the following manner.

Gloss unevenness: Visually judge the degree of gloss unevenness of press-processed prints. Those with uneven gloss are evaluated as ×, those with slight uneven gloss are rated as Δ, and those with no uneven gloss at all are evaluated as O. do.

Adhesion: Adhesive sellotape between the printed and non-print areas of press-processed printed matter, and examine the peeling state of the coating when the sellotape is peeled off to determine the tendency for the coating to peel off. Those showing a tendency are evaluated as ×, those with no tendency at all are evaluated as ○, and those in between are evaluated as Δ.

Table-1 Example 4 Using a flexographic rotary printing machine, NK Hi-Coat Gi (1
Water-based flexo ink and coating material 3 were coated on a sheet of paper (manufactured by Nippon Kako Paper Industries, Ltd.) (manufactured by Nippon Kako Paper Industries Co., Ltd.).Subsequently, pressing was performed under the same conditions as in Example 1 (roller temperature 110°C).Press When comparing the paper length (longer in the paper making direction) with that before pressing, an elongation of 0.044% was observed.

Comparative Example 10 Water-based flexographic ink and coating material 3 were applied to NK high coat paper in the same manner as in Example 4, and after sufficiently drying, press processing was performed under the same conditions as in Comparative Example 4 (lawn temperature 130°C). .

The paper length (paper making direction) after pressing is 0.0 compared to before pressing.
We saw an increase of 0.89%.

Effects> As shown in the examples above, by following the method of the present invention, it is possible to efficiently produce printed matter with a high degree of gloss. In particular, by applying a specific press coating material immediately after printing with water-based ink, and then performing press processing continuously or with water remaining in the printing paper, it has excellent crushability. , it is possible to obtain a printed matter having the desired ultra-gloss.

In addition, by performing press processing under these conditions, the temperature of the hot roller can be significantly lowered, which prevents problems such as paper expansion and contraction and poor strength, and is also superior in terms of energy consumption. It is. Furthermore, unlike conventional oil-based inks, it has excellent adhesion, so there are no problems with swimming, repellency, or evenness of the coating film, so that ultra-glossy printed matter with excellent transparency can be obtained.

Claims (2)

[Claims] (1) A method for producing ultra-glossy printed matter, which comprises continuously applying a water-based press processing coating onto the printed matter immediately after printing with water-based printing ink, and then hot-pressing. (2) The water-based press processing coating material has a glass transition temperature (
2. The method for producing an ultra-glossy printed matter according to claim 1, wherein the main component is an aqueous resin dispersion having a Tg) in the range of 60 to 130°C.