JPH0565446A - Ink for offset or letterpress printing - Google Patents

Abstract

PURPOSE:To provide the subject ink containing a microcapsule having a specific median value and a volume particle size distribution, composed of a core substance and a wall membrane made of a melamine resin, resistant to the collapse of the microcapsule in printing and giving a printed matter exhibiting functionality. CONSTITUTION:The objective ink contains a microcapsule composed of a core substance (preferably containing perfume or thermochromic compound) and a wall membrane made of a melamine resin. The median value of the microcapsule diameter is 1.0-6.0mum and the ratio of particles of >=8mum in diameter is <=10% in the volume particle size distribution.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel lithographic or letterpress printing ink containing microcapsules, and more specifically, a microcapsule containing a perfume or a microcapsule containing a thermochromic compound, which is a functional printed matter. The present invention relates to a lithographic or letterpress printing ink which gives

[0002]

2. Description of the Related Art Microcapsules are microscopic bodies having a structure in which a core material is covered with a wall film, and are used as coating agents for pressure-sensitive copying paper, pharmaceuticals, agricultural chemicals, fragrances, adhesives, enzymes, pigments, Widely used as an encapsulant for dyes and solvents.

In the printing field as well, attempts have been made to produce functional printed matter by using the microcapsules. For example, a gravure printed matter which has been printed using an ink containing microcapsules containing a fragrance and emits a scent by rubbing with a finger has already been put into practical use.

Although such microcapsules are suitable materials for providing various functional prints, they are generally weak against pressure, and thus the microcapsules are contained in an ink and printed on a substrate such as paper. In this case, the printing method is such that the printing pressure is weak or the pressure is not applied to the microcapsules, for example, screen printing, letterpress printing (gravure),
Only flexographic printing or the like is used, and in lithographic or letterpress printing, which is the mainstream of printing, high printing pressure is directly applied to the microcapsules, and the microcapsules are destroyed. The fact is that inks containing microcapsules are not used.

[0005]

SUMMARY OF THE INVENTION The present invention provides a microcapsule-containing printing ink for providing a functional printed matter by a planographic or letterpress printing method which is the mainstream of printing under such circumstances. It was done for the purpose.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to develop a microcapsule-containing lithographic or letterpress printing ink for providing a functional printed matter, and as a result, the microcapsules have a specific volume particle size. By using a core material having a diameter distribution and containing a fragrance or a thermochromic compound and a wall film made of a melamine resin, the microcapsules are not destroyed during printing, and the above-mentioned object is achieved. The inventors have found what can be achieved and have completed the present invention based on this finding.

That is, the present invention comprises a core substance and a wall film made of a melamine resin, has a median value of 1.0 to 6.0 μm, and a ratio of particles of 8 μm or more to 10.
An ink for lithographic printing or letterpress printing, which comprises microcapsules having a volume particle size distribution of not more than%.

The microcapsules used in the ink of the present invention are composed of a core substance containing an effective substance such as a fragrance or a thermochromic compound, and a wall film made of a melamine resin.

Regarding the fragrance used for the core substance,
There is no particular limitation as long as it can serve as the core substance of the microcapsules, and any of natural flavors, synthetic flavors and prepared flavors can be used, but particularly hydrophobic plant essential oils and essential oil components are preferably used. ..

Examples of the plant essential oil include citronella oil, lemongrass oil, needle oil, rose oil, jasmine oil, lavender oil, cabbage oil, orange oil, lemon oil,
Mint oil, ylang-ylang oil, clove oil, geranium oil, patchouli oil, cassia leaf oil, hawthorn flower oil, tuberose oil, nut meg oil, clove oil, bay oil, spearmint oil, cumin seed oil, cinnamon oil, petitgrain oil, kei Leaf oil, eucalyptus oil, linaloe oil, neroli oil and the like can be mentioned.

Examples of essential oil components include anethole, isoeugenol, eugenol, L-carvone,
Cuminaldehyde, cinnamic alcohol, cinnamic aldehyde, geraniol, citral, citronellal, citronellol, vanillin, borneol, L-menthol, eucalyptol, linalool, D-limonene, 3
-Phenylpropionaldehyde and the like.

The thermochromic compound used as the core substance is preferably a reversible thermochromic compound whose color tone reversibly changes with a change in temperature. Examples of such compounds include fused aromatic ring-substituted ethylene derivatives, There are liquid crystal and metamocolor. Examples of the condensed aromatic ring-substituted ethylene derivative include spiropyrans such as di-α, β-naphthoisospiropyran, benzo-β-naphthoisospiropyran, 3-alkyl-di-β-naphthospiropyran, bianthrone, dixanthylene, xanthyline. Examples include anthurones such as denanthrone, and of these, spiropyrans are preferable. These spiropyrans have a certain temperature as a boundary, below which they are colorless,
Above that, it becomes colored and reversibly changes color. This fading color is due to the reversible structural deformation between the ring-closing type (colorless) of the spiropyrans and the planar ring-opening type (colored) formed by cleavage.

On the other hand, liquid crystals are roughly classified into three types, nematic, smectic and cholesteric, and cholesteric liquid crystals are mainly used as thermochromic materials. Many of the cholesteric liquid crystals are derivatives of cholesterin and form an extremely thin spiral structure. In such a molecular arrangement, the torsional deformation energy is extremely small. , Easily changed by external force such as stress and chemical environment. Such a pitch change can be regarded as an optical color change. The discoloration temperature can be selected quite freely depending on the type of liquid crystal and the mixing ratio.

Further, metamocolor is composed of an electron-donating color-forming organic compound, an electron-accepting compound and a polar organic compound.
Composed of ingredients. The electron-donating color-forming organic compound has a role of determining color, and examples of such a compound include 3,6-dimethoxyfluorane (yellow), 3
-Cyclohexylamino-6-chlorofluorane (orange), 3-diethylamino-6-methyl-7-chlorofluorane (red), 3-diethylaminobenzfluorane (peach), rhodamine B lactam (red), crystal violet lactone (Blue) 3-diethylamino-7-
Dibenzylaminofluorane (green), 3-diethylamino-6-methyl-7-anilinofluorane (black) and the like can be mentioned. Further, the electron-accepting compound has a role of determining the color density, and as such a compound, gallic acid propyl ester or the like is usually used. further,
The polar organic compound has a role of determining the discoloration temperature, and examples thereof include higher alcohols such as n-octyl alcohol, n-decylalco-lauryl alcohol, myristyl alcohol, cetyl alcohol and stearyl alcohol. Be done. The color change temperature can be arbitrarily selected within the range of about -40 to 50 ° C by appropriately mixing and using these alcohols.

The microcapsules used in the ink of the present invention have a wall film made of a melamine resin, have a median value in the range of 1.0 to 6.0 μm, and the proportion of particles of 8 μm or more is 10% or less by volume. It is necessary to have a diameter distribution. Microcapsules which do not satisfy these conditions, when used as an ink for lithographic or letterpress printing, are easily broken during printing, and the object of the present invention cannot be sufficiently achieved.

The method for producing the microcapsules is not particularly limited, and the methods conventionally used in the production of microcapsules, such as interfacial polymerization method, in situ method, coacervation method, submerged curing coating method (orifice method), are used. In-liquid method, spraying / granulating method and the like can be used, and in-situ method is particularly preferable.

Next, one example of a suitable method for producing the microcapsules will be described. A core substance containing a fragrance or a thermochromic compound is added to an acidic aqueous solution of a styrene-maleic anhydride copolymer, and high-speed stirring is performed. , Emulsify or disperse by applying ultrasonic waves. On the other hand, add alkali to the mixed solution of formalin and melamine to adjust the pH to 8-1.
After adjusting to 0, it is heated to a temperature of about 50 to 100 ° C. to prepare an aqueous solution of a melamine-formaldehyde initial condensate composed of methylolated melamine.

Then, the aqueous solution of the melamine-formaldehyde precondensate is added to the emulsion or dispersion containing the styrene-maleic anhydride copolymer and the core substance, and the mixture is added at a temperature of about 40 to 90 ° C. for 30 minutes. The reaction is carried out with stirring for 4 minutes to 4 minutes to form a wall film made of a melamine resin around the core substance. The wall film formed of the melamine resin thus formed is excellent in heat resistance, water resistance, solvent resistance, and high in tightness, and is suitable for printing ink.

Next, the thus obtained microcapsule dispersion is dried by a known drying method such as a spray drying method to obtain a microcapsule powder having fluidity.

The printing ink of the present invention contains microcapsules containing the above-mentioned perfume or thermochromic compound, and the microcapsules are destroyed during printing even when used in a lithographic or letterpress printing system. It is possible to provide a functional printed matter. For example, a printed matter obtained by using an ink containing microcapsules containing a fragrance does not smell as it is, but rubs a scent by rubbing with a finger. Further, the color tone of the printed matter obtained by using the ink containing the microcapsules containing the thermochromic compound changes according to the change in temperature.

[0021]

The lithographic or letterpress printing ink of the present invention comprises:
A lithographic printing method comprising microcapsules having a specific volume particle size distribution and comprising a core substance containing a fragrance or a thermochromic compound and a wall film made of a melamine resin coating the core substance. Also when used in a relief printing method, the microcapsules are not destroyed during printing, and a functional printed matter can be provided.

[0022]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 (1) Preparation of offset printing ink containing microcapsules containing lemon fragrance Styrene-maleic anhydride copolymer (manufactured by Monsanto Co., Ltd.,
5% by weight of pH 4.5 prepared by dissolving the trade name "Scriptset-520") with a small amount of sodium hydroxide.
To 300 parts by weight of the aqueous solution, 200 parts by weight of lemon fragrance (trade name "PH-6968" manufactured by Takasago International Corporation) was added,
The emulsion was emulsified using an ultra homogenizer manufactured by Nippon Seiki.

On the other hand, melamine 20 parts by weight and 37% by weight
Add 45 parts by weight of formalin to 35 parts by weight of water and add 2 more
The pH was adjusted to 9.5 with a 0 wt% sodium hydroxide aqueous solution and heated at 85 ° C. for 15 minutes to prepare an aqueous solution of a melamine-formaldehyde precondensate.

Next, an aqueous solution of the melamine-formaldehyde precondensate was added to the above emulsion, and the mixture was added at 75 ° C. for 2 hours.
After stirring for a period of time, a microcapsule dispersion having a melamine resin wall film containing a lemon flavor was obtained. When the particle size of the microcapsules was measured using an Elzone Particle Counter (manufactured by US Particle Data Co., Ltd.), the median value of the volume particle size distribution was 4.5 μm,
The ratio of particles having a size of 8 μm or more was 4%.

The thus obtained microcapsule dispersion having a melamine resin wall film enclosing the lemon fragrance was spray-dried (Yamato Scientific DL41 type).
At inlet temperature of 250 ° C, nozzle pressure of 1.5 kg / c
Spray drying was performed under the conditions of m ² and a sample feed rate of 15 g / min to obtain a fluid lemon microcapsule-encapsulating microcapsule powder. Next, 15 parts by weight of this microcapsule powder was added to 85 parts by weight of OP varnish (manufactured by Toyo Ink Mfg. Co., Ltd.) and kneaded with a three-roll to give an ink for rotary offset printing.

(2) Preparation of Fragrance Printed Product A lemon pattern was offset-printed at a speed of 500 FPM onto a 55 kg continuous paper of the ink containing microcapsules containing the above-mentioned fragrance using a business form printing machine. When the obtained printed matter was observed with an electron microscope, the perfume microcapsules were not destroyed,
When I rubbed the lemon pattern with my finger, it smelled like lemon.

Comparative Example 1 A microcapsule dispersion having a melamine resin wall film containing a perfume in the same manner as in Example 1 except that 220 parts by weight of the lavender perfume was used instead of 200 parts by weight of the lemon perfume in Example 1. Got When the particle size of this microcapsule was measured using an Elzone particle counter (described above), the median value in the volume particle size distribution was 6.7 μm, and the ratio of particles of 8 μm or more was 35%.

The microcapsule dispersion liquid having the melamine resin wall film containing the lavender flavor thus obtained was sprayed with a spray dryer (described above) at an inlet temperature of 250.
° C, nozzle pressure 1.0 kg / cm ² , sample feed amount 12 g
Spray drying was performed under the condition of / min to obtain a lavender perfume-containing microcapsule powder having fluidity.

Then, this microcapsule powder was used as an ink for offset rotary printing in the same manner as in Example 1, and a flower pattern was printed. As a result, a strong scent was generated during printing. When the obtained printed matter was observed with an electron microscope, most of the microcapsules were broken.

Example 2 (1) Preparation of letterpress printing ink containing microcapsules containing a thermochromic compound In Example 1, instead of 200 parts by weight of lemon flavor,
Thermochromic compound 1 that fades in red color at 30 ° C
A microcapsule dispersion having a melamine resin wall film containing a thermochromic compound was obtained in the same manner as in Example 1 except that 80 parts by weight was used. The particle size of this microcapsule is determined by the LZONE particle counter (see above).
When measured using, the median value in the volume particle size distribution is 4.0 μm, and the ratio of particles of 8 μm or more is 3%.
Met.

The microcapsule dispersion liquid having the melamine resin wall film encapsulating the thermochromic compound thus obtained was spray dried (described above) at an inlet temperature of 220 ° C., a nozzle pressure of 2.0 kg / cm ² , and a sample. Spray-drying was performed under the condition of a feed amount of 12 g / min to obtain a microcapsule powder containing a thermochromic compound having fluidity. Then, 20 parts by weight of this microcapsule powder is added to TK Mark V New Medium M (manufactured by Toyo Ink Manufacturing Co., Ltd.).
In addition to 20 parts by weight, it was kneaded with a three-roll mill to give an ink for letterpress printing.

(2) Preparation of Thermochromic Printed Material Using a business foam printing machine, ink containing microcapsules containing the above-mentioned thermochromic compound was printed on a fine paper of 75 kg continuous amount by resin letterpress at a speed of 300 FPM. .. When the obtained printed matter was observed with an electron microscope, the microcapsules were not broken, and when exposed to an atmosphere of 40 ° C, the color changed from red to colorless.

Comparative Example 2 Except that 180 parts by weight of the red-colored thermochromic compound in Example 2 was replaced by 230 parts by weight of a blue-colored thermochromic compound that was decolorized at 30 ° C.
A microcapsule dispersion having a melamine resin wall film containing a thermochromic compound was obtained in the same manner as in Example 2. The particle size of the microcapsules was measured using an Elzone particle counter (described above), and the median value in the volume particle size distribution was 5.5 μm.
The ratio of particles of m or more was 15%.

The thus obtained microcapsule dispersion having a melamine resin wall film encapsulating a thermochromic compound was spray dried (previously described) at an inlet temperature of 250 ° C., a nozzle pressure of 2.0 kg / cm ² , and a sample. Spray drying was carried out under the condition of a feed rate of 18 g / min to obtain a microcapsule powder containing a fluid thermochromic compound.

Then, this microcapsule powder was used as an ink for letterpress printing in the same manner as in Example 2 to perform printing. When the obtained printed matter was observed with an electron microscope, the microcapsules were broken, and even when exposed to an atmosphere of 40 ° C., the color was not completely erased, and numerous blue spots remained.

Claims (3)

[Claims] 1. A core material and a wall film made of a melamine resin, and a median value of 1.0 to 6.0 μm.
The ink for lithographic or letterpress printing, wherein the ink contains microcapsules having a volume particle size distribution in which the proportion of particles of 8 μm or more is 10% or less. 2. The ink for lithographic or letterpress printing according to claim 1, wherein the core substance contains a fragrance. 3. The lithographic or relief printing ink according to claim 1, wherein the core substance contains a thermochromic compound.