JPH05117566A - Printing ink composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition having reduced change of viscosity of ink with time, excellent fast drying properties and viscosity stability by adding a specific amount of hydroxypropyl cellulose to a glycol solvent type printing ink for letterpress printing. CONSTITUTION:(B) 0.05-3.0wt.% hydroxypropyl cellulose is added to (A) 100wt.% glycol solvent type printing ink for letterpress printing to give the objective composition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a glycol solvent type printing ink for a letterpress printing machine, which is used for printing on paper containers such as cardboard and paper bags.

[0002]

2. Description of the Related Art Generally, there are a flexo method using a water-based ink and a Prislo method using a glycol solvent type ink in this type of printing, but in the latter method, a roller of a printing machine is used as needed. Printing can be done by giving only a minute amount of ink, and the amount of ink used and washing are small, so
A printing machine of a prism type is often used for corrugated board printing and the like.

In recent years, in order to improve productivity by adapting to the shortage of skilled workers and the production of various types in small quantities, it is urgently necessary to improve the printing machine. As an ink supply system, ink is set for each container and air pressure or It has also become possible to find a configuration with an automatic supply device for spraying the ink onto a printing roller under computer control by an electrically operated spray.

The conventional glycol solvent type ink is prepared by adding an alkali to a solid resin such as a rosin-modified maleic acid resin, a styrene-modified maleic acid resin, an acrylic resin, etc., dissolving it in a glycol solvent and adding a little alkaline aqueous solution to the vehicle. Is used as.

The ink used in the Prislo printing machine equipped with the above-mentioned ink supply device is generally as follows.
Depending on the season, the viscosity and tack of the vehicle are changed, and the addition amount of organic solvent and alcohol is changed in consideration of the drying property of the ink, the on-machine stability, the resistance of printed matter, etc.
It is manufactured and supplied by being classified as summer type.

[0006]

As described above, as a vehicle for the conventional glycol solvent type printing ink, a solid resin dissolved in a glycol solvent is used.
This resin is the only one that retains viscosity, and it has the property that the resin becomes soft when the temperature is high and hard when the temperature is low. For example, the viscosity changes greatly depending on the temperature and humidity, and the drying is slow. Therefore, the summer ink manufactured in the summer has a high viscosity in the winter and becomes hard to use, and the winter ink has a low viscosity in the summer and is too soft to be used. In addition, it was necessary to manufacture and supply ink according to each season. Especially in Japan, the temperature difference between winter and summer was so severe that it was difficult to use the same ink throughout the year.

[0007] For example, in a Prislo printing machine equipped with an automatic feeder, when summer type ink is used in winter, the ink is too hard to jet onto the roll, or even if jetted, the ink is not evenly fed. There was a problem such as becoming.
Further, when winter type ink is used in summer, the amount of jetting becomes excessive and it becomes impossible to print beautifully.

Therefore, even in a Prislo printing machine equipped with this kind of automatic supply device, it is necessary to supply ink according to the season, but troubles caused by accidentally using out-of-season ink by workers occur throughout the year. The current situation is that many are occurring, and it is inevitable that the inventory management of ink is extremely wasteful and complicated.

The present invention has been made in view of the above problems of conventional inks, and the purpose thereof is to use the same ink throughout the year even in a climatic condition in which the temperature difference between winter and summer is drastic as in Japan. Another object of the present invention is to provide a glycol solvent-type ink composition that can be printed by using the ink composition and has excellent quick-drying properties.

[0010]

To achieve the above object, in the present invention, in a glycol solvent type printing ink composition for a relief printing press, hydroxypropyl cellulose is added in an amount of 0.05 to 3 in 100% by weight of the ink. The present invention proposes a printing ink composition containing 0.0% by weight.

The present invention has achieved the above-mentioned object of the present invention by paying attention to the characteristics of hydroxypropyl cellulose (hereinafter abbreviated as HPC) and using it.

[0012]

[Function] Generally, there are many swelling agents (gelling agents) in celluloses, most of which swell in organic solvents and alcohols but not in water, and other swelling agents in water. Swells, but not organic solvents. But in this H
Only PC swells in both and presents a clear and colorless gel. Then, it was found that by adding this to a glycol solvent type ink, the solvent and the resin are connected to each other to act on both of them, and play a role of maintaining resistance to heat. As a result, it has become possible to provide a low-viscosity glycol solvent type ink capable of maintaining a constant viscosity (hardness) independent of temperature and humidity.

[0013]

EXAMPLES Examples of the present invention will be described below. First, for the printing ink according to the present invention (Example 1), the conventional summer product to be compared with this (Comparative Example 1) and the winter product (Comparative Example 2), Indicates. All mixing ratios are weight ratios.

Varnish Production Example John Cryl 67 (1) 50 parts Diethylene glycol 10 parts Ethylene glycol 33 parts Monoethanolamine 7 parts (Note) (1): Johnson Wax acrylic resin Dissolved at 180 ° C. under the reaction conditions under the above conditions. , Varnish (A) was obtained.

Comparative Example 1 Lionol Red F2B (2) 14 parts Precipitating sulfuric acid value (3) 15 parts Varnish (A) 55 parts Wax 3620 (4) 5 parts Ethylene glycol 11 parts

Comparative Example 2 Lyonol Red F2B (2) 14 parts Precipitating Sulfuric Acid Value (3) 15 parts Varnish (A) 45 parts Wax 3620 (4) 5 parts Ethylene glycol 21 parts

Example 1 Lionol Red F2B (2) 14 parts Precipitating sulphate value (3) 15 parts Varnish (A) 45 parts Wax 3620 5 parts Ethylene glycol 19.5 parts Hydroxypropyl cellulose (HPC) (5) 1 .5 copies

(Note) (2): Toyo Ink Co., Ltd. red pigment (3): Barite Kogyo Co., Ltd. extender pigment (4): Hoechst Japan Co., Ltd. polyethylene wax (5): Shin-Etsu Chemical Co., Ltd. gelling agent Example 1 The ink composition is the same in both summer and winter. Comparative Examples 1 and 2 and Example 1 are all kneaded with three rolls. The boiled meat temperature is constant (35 ° C).

1 and 2 show the results of measuring the change in viscosity throughout the year at room temperature for the four seasons of Comparative Examples 1 and 2 and Example 1 having the above formulations. The tester is a BH type rotational viscometer. FIG. 1 shows Comparative Example 1 and Example 1 which are manufactured in summer by a broken line and a solid line, respectively. In the winter season, the ink of Comparative Example 1 rapidly increases in viscosity and becomes too hard to be used. In comparison with 1.
It has been shown that the ink of Example 1 added with 5% by weight exhibits a stable state without significant change even in winter.

Next, FIG. 2 shows a comparative example 2 which is a product manufactured in winter.
And the ink of Example 1 are represented by a broken line and a solid line, respectively. In the summer, the ink of Comparative Example 2 suddenly dropped in viscosity and became too soft and unusable, whereas the ink of Example 1 showed a stable state with no significant change in the summer. Has been done.

Therefore, for Comparative Examples 1 and 2 and Example 1 in which there is no significant difference in ink composition except for the presence or absence of addition of HPC, as in Example 1, addition of HPC causes little change in viscosity throughout the year and the same ink. It turned out that printing is possible with.

Next, regarding the conventional ink having the following compositional composition (Comparative Example 3) and the ink according to the present invention (Example 2) to which HPC was added, the comparison of properties such as drying time and the change with time in stickiness were conducted. I considered.

Comparative Example 3 Lionol Red F-2B 14 parts Precipitating Sulfuric Acid Valuem 15 parts Varnish (A) 40 parts Polyethylene wax 5 parts Ethylene glycol 6 parts Ethanol 20 parts

Example 2 Lionol Red F-2B 14 parts Precipitating Sulfuric Acid Value 15 parts Varnish (A) 35 parts Polyethylene wax 5 parts Ethylene glycol 6 parts Water 24 parts Hydroxypropyl cellulose (HPC) 1 part

With respect to Comparative Example 3 and Example 2 having the above-mentioned configurations,
Property data such as drying time are shown in Table 1 below.

[Table 1] (Test conditions) Temperature: 20 ° C Humidity: 60% Viscosity (poise): BH type rotational viscometer (constant at 20 ° C) Drying time: Set time (minutes) until the print surface is pressed with a finger and the ink does not stick to the finger Tack: Toyo Seiki Incometer (32 ℃
Liner used: Tokai Jate Liner

The change in tenacity with time is shown in FIG. 3, Comparative Example 3 is shown by a broken line, and Example 2 is shown by a solid line.

As can be seen from Table 1 and FIG. 3 above, the ink of Example 2 according to the present invention has little change with time and high viscosity stability, so that the fluidity of the ink is improved and the ink is automatically When used in a printing machine equipped with a supply device, when the ink is supplied onto the roll from the jet nozzle, it is possible to completely prevent dripping of ink, ink scattering, and so-called misting. As a result, ink consumption loss can be significantly reduced. In addition, improved fluidity enables printing with low viscosity, and even if the ink buildup on the printing machine is made thinner, good printing can be performed without causing ink spills (curing of the vehicle) or blurring phenomenon. The suitability can be maintained. Furthermore, it has been found that the printed matter has a thinner and more uniform coating, so that the drying time is significantly reduced compared to conventional inks. In addition, since a good printing effect can be obtained even with such a thin ink pile, the number of printed sheets (the number of consecutive sheets) with the same amount of ink can be increased by 1.5 times and the printing speed is also increased by 1.5 times. Became possible. The vertical axis of the graph in FIG. 3 represents stickiness (tack), and TV is an abbreviation for tack value.

Next, the amount of HPC added was changed with respect to the glycol solvent type ink composition formulation in Example 2, and the change in viscosity thereof is shown in Table 2 and FIG. 4 below.

[Table 2]

From the results shown in Table 2 and the graph of FIG. 4, H
The amount of PC added is 100% in the ink composition.
It is desirable that the content of 0.05 to 3.0% by weight is contained in the weight%. If it is less than 0.05% by weight, no change in viscosity can be obtained and resistance to a target temperature cannot be obtained. On the other hand, if it exceeds 3% by weight, the viscosity rises sharply and the ink becomes rubbery, making it impossible to perform proper printing. Therefore, in the present invention, H within the above range
The addition of PC has proved desirable.

Next, regarding the safety of the printing ink containing HPC according to the present invention, the flash point test (JIS K2
As a result of the (265 Cleveland open type), the flash point has an average value of 115 ° C. and the amount of combustible liquid is 28%, and it has been determined that the substance does not correspond to Class 4 hazardous materials. In addition, it meets the voluntary regulations (so-called NL regulations) for printing inks for food packaging materials, and there is no problem in safety.

The present invention has been described above with reference to the examples. In the present invention, hydroxypropyl cellulose (H
PC) was used, but if it is a cellulose having a hydroxypropyl group that achieves the same action and effect, this is synonymous with HPC in the present invention. Besides, the present invention is not limited to the embodiments.

[0032]

As described above, according to the present invention, hydroxypropyl cellulose (HPC) is added to the composition of a glycol solvent type printing ink in an amount of 0.
By including it in the range of 05 to 3.0% by weight, there is little change in the viscosity of the ink over time, and the stability of the viscosity is improved, so it is possible to print with the same ink throughout the four seasons. It is no longer necessary to select and store appropriate inks, inventory management becomes easier, and uniform printed matter can be obtained on the printing machine even in high temperature and high humidity environments during the rainy season. Also, even if printing for a long time, there is little change in increase in ink viscosity, so uniform printing can be continued from beginning to end, long run can be supported, and the drying amount is also in seconds because the amount of ink is uniform and thin. The number of printed sheets to be printed is increased, and the printing itself has various effects such as solid printing similar to flexographic printing, fine print, and dot printing.

[Brief description of drawings]

FIG. 1 is a graph showing a change in viscosity of an ink of Example 1 according to the present invention and Comparative Example 1 of a conventional ink throughout a year.

FIG. 2 is a graph showing changes in viscosity of the ink of Example 1 according to the present invention and Comparative Example 2 of a conventional ink over a year.

FIG. 3 is a graph showing changes over time in the stickiness (tack, TV) of the ink of Example 2 according to the present invention and Comparative Example 3 of the conventional ink.

FIG. 4 is a graph showing changes in HPC addition amount and viscosity in the ink of Example 2 according to the present invention.

Claims (1)

[Claims] 1. A printing ink composition comprising a glycol solvent type printing ink composition for a relief printing press, wherein hydroxypropyl cellulose is contained in an amount of 0.05 to 3.0% by weight based on 100% by weight of the ink. ..