JPS6018557B2 - How to cover printed matter - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for coating printed matter.

Printing is performed using printing ink on base materials such as paper, plastic, and film, and the printed matter is coated with a transparent coating and is used in fields such as packaging, advertising, books, and building materials. ing.

In the case of such coating, the typical conventional method is to apply a solvent solution of a transparent copolymer, such as a pinyl chloride vinyl acetate copolymer, to the surface of the printed matter and then evaporate the solvent. This is a method of coating a solvent solution of a polymer such as a method. However, when such a method is carried out, an environmental problem arises due to contamination of the workplace and factory surroundings due to solvent volatilization, and a solution to this problem is strongly desired.

One possible solution to this problem is to apply and dry a water-dispersed polymer made by polymerizing an ethylenically unsaturated compound in water, such as an acrylic water-dispersed polymer. When such a method is used, it is impractical in that the coating film of the polymer is generally insufficient to form a film in which the particles are tightly formed with each other, making it difficult to obtain a coating with good surface smoothness. In order to improve this problem, coatings can be obtained by coating printed matter with a water-dispersed polymer mixed with a solvent or plasticizer, or a water-dispersed polymer whose softening temperature is below room temperature. Although the surface smoothness of the object has been improved to some extent, it is still insufficient, and when the obtained coatings are piled up, there is a problem that the coatings adhere to each other, that is, blocking occurs, which is not practical. Not. Another possible countermeasure is to apply a photopolymerizable paint to the printed material and cure it by irradiating it with light to form a coating. This tends to cause disadvantages such as partial oozing, the printing ink being easily peeled off from the substrate etc. together with the cured paint, and a peculiar odor remaining in the coating for a long period of time.

The cause of the above-mentioned phenomenon of easy peeling and peculiar odor remaining on the coating for a long period of time is not clear, but it is probably due to the photopolymerizable paint penetrating inside or behind the printing ink, and then Even when light is irradiated, the printing ink blocks the light from passing through, so the photopolymerizable paint in the permeated area does not harden or remains uncured, resulting in the above-mentioned peeling phenomenon. This is thought to be due to the fact that this is more likely to occur, and that the remaining uncured parts generate an odor over a long period of time.

The inventors of the present invention have conducted various studies using water-dispersed polymers as described above in order to solve the above-mentioned problems that occur when coating printed matter. achieved.

That is, the method of the present invention comprises: (1) a water-dispersed polymer prepared by polymerizing an ethylenically unsaturated compound in water; 'B' a polymerizable ethylenically unsaturated group soluble in the water-dispersed polymer;
A water compound prepared by mixing a compound containing 1 or more and a photosensitizer and adjusting the particle size to particles with a particle size of 0.6 microns or less is applied to a printed matter and cured by irradiation with light. This is a method of coating printed matter characterized by the following.

The water-dispersed polymer used in the present invention, that is, the water-dispersed polymer prepared by polymerizing an ethylenically unsaturated compound in water, will be explained below.

That is, the polymers of the ethylenically unsaturated compounds used here include polymers of '11 acrylic compounds and vinyl aromatic compounds, ie, acrylic compounds such as methyl acrylate, ethyl acrylate, butyl acrylate, 2- Compounds such as ethylhexyl acrylate, hydroxypropyl acrylate, methyl methacrylate, butoxyethyl methacrylate, glycidyl methacrylate, diethylaminoethyl methacrylate, diethylene glycol dimethacrylate, methacrylonitrile, butylated acrylamide, etc., and vinyl aromatic compounds such as styrene. , vinyltoluene, alpha-methylstyrene, etc.; '21-Dene polymers, i.e., polymers containing at least a majority of diene compounds such as ptagene, isoprene, chloroprene, etc.; [31] Vinyl polymers, i.e. vinyl compounds such as pinyl chloride,
Typical examples include polymers containing at least a majority of compounds in which oxygen, nitrogen, or halogen atoms are directly bonded to polymerizable ethylene groups, such as vinyl acetate, vinyl propionate, pinylidene chloride, and ethyl vinyl ether. ,
In addition, ethylene polymers, that is, polymers containing at least a majority of ethylene, and polymers of unsaturated dibasic acid ester compounds such as ester itaconate, ester maleate, and ester fumarate can also be used. A typical method for polymerizing these ethylenically unsaturated compounds in water is emulsion polymerization. Incidentally, the particle size of the dispersed particles of the water-dispersed polymer of W used in the present invention described above is usually 0.5 microns or less, particularly 0.3 to 0.05 microns.
Micron ones are preferred. The above {B used in the present invention
-, i.e., a polymerizable compound soluble in the above-mentioned water-restricted polymer. Compounds containing two or more ethylenically unsaturated groups are typically compounds containing two or more acrylate groups and methacrylate groups in total. Compounds with derived chemical structures, such as ethylene glycol diacrylate, neobenkel glycol dimethacrylate, trimethylolpropane triacrylate, bentaerythritol triacrylate, sorbitol hexaacrylate, triethylene glycol diacrylate, polyethylene glycol dimethacrylate Polypropylene glycol diacrylate, diventaerythritol bentamethacrylate, a compound with a chemical structure derived from '21 polyester polyol, such as a polyester diol obtained by reacting 2 moles of ethylene glycol with 1 mole of adipic acid and 2 moles of methyl acrylate. Polyester diol dimethacrylate, trimethylol, obtained by reacting diacrylate, 3 moles of diethylene glycol, 2 moles of isophthalic acid, and 2 moles of methacrylic acid.

Polyester tetraacrylate obtained by reacting 2 moles of bread with 1 mole of phthalic acid and 4 moles of acrylic acid, polyester diacrylate obtained by reacting 1 mole of chlorendic acid, 2 moles of ethylene glycol, and 2 moles of acrylic acid, and trimellitic acid. Polyester triacrylate obtained by reacting 1 mole of anhydride, 3 moles of diethylene glycol, and 3 moles of acrylic acid, [3' epoxy resin,
Compounds with chemical structures derived from urethane resins, amino resins, acrylic resins, etc. For example, epoxy diacrylate and trimethylolpropane triglycidisoether obtained by addition reaction of 1 mole of bisphenol A dicrycidyl ether and 2 moles of acrylic acid. Epoxy acrylate methacrylate obtained by addition-reacting 1 mole of methacrylic acid and 1 mole of acrylic acid, 3 moles of toluene diisocyanate, 1 mole of trimethylolpropane, and 3 moles of hydroxyethyl methacrylate. The obtained polyurethane trimethacrylate, triacrylate of melamine resin obtained by reacting 1 mole of hexamethylated methylol melamine with 3 moles of hydroxypropyl acrylate, addition of methyl methacrylate to styrene glycidyl methacrylate copolymer and acrylic acid. Typical examples are acrylic resins in which two or more acrylate groups are introduced into one molecule obtained by reaction, and compounds such as polyesters using itaconic acid and dipinylbenzene can also be used, and in either case, water-soluble Compounds with poor properties are particularly preferred. Any of the known photosensitizers used in the present invention (CI photosensitizers include penzoin ethyl ether, benzoin butyl ether, penzoin acrylate, benzophenone, alpha methylanthraquinone, benzyl, etc.) One species or two or more species can be used.

A water-dispersed polymer prepared by polymerizing the ethylenically unsaturated compound (W) in water, a compound containing two or more polymerizable ethylenically unsaturated groups (B-), and a photosensitizer (C) The usage ratio (weight basis) is usually 10 to 80%, especially 20 to 6.
0%, and the ratio of the above-mentioned [C'] to the sum of the above-mentioned aberrations and 'B-' is usually 0.3 to 15%, particularly 0.5 to 10%.

In addition, the proportion of water to the total of the above-mentioned (1), legs, and water is usually 25 to 95%, particularly 35 to 90%, and the water in this case includes the water used in producing the water-dispersed polymer; This is the total amount of water used, such as water added later. In addition, in the present invention, the above-mentioned ``8'' and [
When preparing an aqueous dispersion by mixing C', simply mixing C' and CI generally results in poor surface smoothness. It is necessary to use a mixing method that allows the particle size of the dispersed particles to be 0.6 microns or less.

In this case, the mixing method includes, for example, the above-mentioned legs and
After namiai, mix it with water in which a surfactant or dispersant has been dissolved, mix it thoroughly with Takaazusa, mix it with the above, and use a powerful Takaframe machine to rope it for a long enough time or use the wind rope. There are methods such as mixing with a rope pestle while gradually dropping the mixture of 'B' and {C} into the tube, but there are no special restrictions, and in any case, the particle size of the dispersed particles is substantially An aqueous dispersion may be prepared so that the particle size is 0.6 microns or less. In the present invention, the aqueous dispersion may be applied to the printed material by any known coating method such as a roll method, a spray method, or a curtain method.

In the present invention, the light to be irradiated is usually preferably ultraviolet light, but visible light can also be used. Examples of ultraviolet generators that use ultraviolet light include mercury lamps, metal halide lamps, and carbon arc lamps. In addition, regarding the atmosphere when irradiating light in the present invention,
The atmosphere may be air or an active gas such as nitrogen gas or carbon dioxide, and there are no particular restrictions. When light is irradiated onto a printed matter coated with an aqueous dispersion, the printed matter is usually irradiated from the side of the coated water dispersion. However, for example, if the irradiated light is ultraviolet rays, When transmitting ultraviolet rays, the irradiation may be performed in the opposite direction to the above-mentioned irradiation direction, that is, the irradiated ultraviolet rays may be irradiated so as to pass through the substrate and transfer to the applied dispersion.

The printing ink used to obtain the printed matter used in the present invention is
There are no particular restrictions on the type, and examples include oil-based ink, synthetic resin ink, and photocurable ink.

In the printed matter of the present invention, the substrate on which the printing ink is printed may be any solid material such as paper, cellophane, plastic synthetic leather, wood, leather, cloth, metal, etc. It can be anything.

The printed material used in the present invention is obtained by printing printing ink on the above-mentioned base material.

When carrying out the present invention, various changes are possible, such as those described below.

The above-mentioned water-reduced polymers used in the present invention include polymers obtained directly by polymerization, as well as polymers modified by chemical reactions such as polymers obtained by hydrolyzing this polymer in water, and other polymers dispersed in water. You can also use things.

When carrying out the present invention, when preparing the aqueous dispersion in the present invention, when mixing the substances used in the above-mentioned Compounds having one unsaturated group can also be used together, and typical examples of such compounds include compounds containing an acrylate group or a methacrylate group.
Examples include ptoxyethyl acrylate, 2-ethylhexyl acrylate, tetrahydrofurfuryl acrylate, diethylaminoethyl methacrylate, morpholinoethyl methacrylate, glycidyl methacrylate, and other compounds such as styrene, pinyltoluene, dibutyl itaconate, etc. can.

The above-mentioned compound having one polymerizable ethylenically unsaturated group is used in combination to adjust the viscosity related to the curing speed of the aqueous dispersion when applied to printed matter. The effect will not be affected.

When carrying out the present invention, other additives such as photosensitizers such as phosphines and amines, colorants, polymerization inhibitors, surfactants, solvents, plasticizers, various resins, and other additives may be used. May be used together.

The method of the present invention does not emit the odor peculiar to solvents as in the previously mentioned known methods, so it is possible to solve environmental problems caused by contamination around workplaces and factories due to solvent volatilization.
A close film is formed between the particles of the cured coating film formed on the printed matter, and a coating with excellent surface smoothness is obtained, and the obtained coating does not have the defect of causing blocking. Since it has many practical advantages such as being difficult to peel off, the present invention is an extremely useful and valuable method for coating printed matter compared to the known methods described above.

Examples will be shown below, and all parts and percentages shown in the examples are expressed on a weight basis. Example 1 100 parts of a water-dispersed polymer having a particle size of 0.12 microns, a concentration of 35%, and a composition of 30% methyl methacrylate, 40% ethyl acrylate, and 30% styrene were mixed with 20% ethylene glycol diacrylate. Using a mixed solution of 80% methylolpropane triacrylate [B} and benzene butyl ether [C}, first add 0% polyvinyl alcohol as dispersion water to the mixed solution of the above '8' and 2}.
．． A 1% concentration aqueous solution (■) was mixed with a rope and pressed to form a dispersion liquid, which was then dropped into the above wind with a diluted water droplet under the flies for 30 minutes. After that, continuous pitching was continued for an additional 100 minutes to examine the dispersed particles using an electron microscope. After checking the particle size, apply the resulting aqueous dispersion onto plywood with printing paper for decorative laminates using a bar coater so that the coating film has a thickness of 0.15 microns. Evaporate the moisture and place under a mercury lamp.
Irradiated with ultraviolet light.

For each obtained scarlet coating, the surface of the cured coating was rubbed with a pencil with a flat tip having a hardness of 2 days to test the adhesion of the coating cured by the irradiation, and the peelability from the printed part of the printing paper was evaluated. Also, as a blocking test, cut the above-mentioned coating so that its surface area is a square of 5 squares on a side to make two coatings, and connect these two coatings in series. That is, the coating was stacked with the base materials on the bottom side, a 5K9 weight was placed on top of it, and the blocking property was checked immediately after leaving it for 2 days, and the coating was also subjected to a sensory test one day after its manufacture. The residual odor was tested respectively. The test conditions and test results described above are collectively shown in Table 1.

Table 1 [Note] [1' In the case of experiment number 4, the above [B'
Mix the mixed solution of and 'C}, the above ■ and the legs all at once, and make 2.
Aqueous dispersion was obtained by heating for 0 minutes, and a coating was obtained from this in the same manner as in the above experimental example.

(2) In all of Experiment Nos. 1 to 3, there was no peeling or blocking property from the printed area of the printing paper, and virtually no residual odor was observed.

Regarding Experiment No. 4, there was no blocking property at all, but the test results for peelability from the printed area of the printing paper and residual odor were poor. Example 2 As shown in Table 2, various water-dispersed polymers, ethylenically unsaturated compounds (BN), and photosensitizers were prepared according to each experiment number.
C', using an aqueous solution of polypynyl alcohol with a concentration of 0.1% and a diluted water base, first, the mixed solution of (BN) and } above and the above rib were mixed and concentrated to form a dispersion. This was added dropwise to the above solution together with the legs under a hawk azure for 30 minutes, and then the aqueous dispersion was continued for 10 more pieces to confirm the particle size of the dispersed particles using an electron microscope, and the resulting aqueous dispersion was coated with a bar coater. The coating was applied to printing paper to a thickness of 0.10 microns, left to evaporate water, and irradiated with UV rays under a double mercury lamp.

Each of the obtained coatings was tested in the same manner as in Example 1 for adhesion, peelability, blocking properties, and residual odor of the cured suppuration caused by the irradiation. Table 2 shows the test conditions and test results described above. 2 [Kono] In the above table, AI is a copolymer of 80% styrene and 20% ptadine, A2 is a copolymer of 75% butadiene and 25% styrene, and A3 is 85% vinyl acetate and 15% ethylene.
A4 is a copolymer of 90% vinyl acetate and 10% vinyl alcohol, A5 is a copolymer of 100% ethyl acrylate, BI is triethylene glycol diacrylate, B2 is pentaerythritol triacrylate, and B3 is trimellit. Triacrylate of polyester obtained by reacting 1 mole of acid anhydride, 3 moles of diethylene glycol, and 3 moles of acrylic vinegar, B4 is dimethylaminoethyl methacrylate, and B5 is 1 mole of dicrycidyl ether of bisphenol A and 2 acrylic acids. B6 is polyurethane trimethacrylate obtained by reacting 3 moles of toluene diisocyanate, 1 mole of trimethylolpupan, and 3 moles of hydroxyethyl methacrylate; B7 is tetrahydrofurfuryl Acrylate CI represents penzoin ethyl ether, C2 represents penzophenone, and C3 represents penzyl.

Claims (1)

[Scope of Claims] 1 (A) a water-dispersed polymer prepared by polymerizing an ethylenically unsaturated compound in water; (B) a polymer having an ethylenically unsaturated group soluble in the water-dispersed polymer; An aqueous dispersion prepared by mixing a compound containing two or more compounds and (C) a photosensitizer so that the particles have a particle size of 0.6 microns or less is applied to a printed matter, and by irradiation with light. A method for coating printed matter, characterized by curing.