JP2021127394A - Ink composition for offset printing, printed matter, and method for producing printed matter - Google Patents

Abstract

To provide an ink composition for offset printing that prevents the area of printed dots from decreasing with the lapse of time.SOLUTION: An ink composition for offset printing comprises a color pigment, a loading pigment, a binder resin, and an oil component and further includes an aminocarboxylic-acid-based chelating agent, wherein the loading pigment is an inorganic calcium salt and the mass ratio of the inorganic calcium salt to the aminocarboxylic-acid-based chelating agent, [(inorganic calcium salt)/(aminocarboxylic-acid-based chelating agent)], is 1-50 inclusive.SELECTED DRAWING: None

Description

The present invention relates to an ink composition for offset printing, a printed matter, and a method for producing a printed matter.

Offset printing is a printing method that utilizes the property that an oil-based offset printing ink composition (hereinafter, abbreviated as "ink composition" or "ink" as appropriate) repels water, and prints with irregularities. Unlike the letterpress printing method using a plate, it is characterized by using a printing plate having no unevenness. This printing plate includes a lipophilic image portion and a hydrophilic non-image portion instead of the unevenness. At the time of printing, first, the non-image portion of the printing plate is wetted with dampening water to form a water film on the surface thereof, and then the ink composition is supplied to the printing plate. At this time, the supplied ink composition does not repel and adhere to the non-image portion on which the water film is formed, but adheres only to the lipophilic image portion. In this way, an image of the ink composition is formed on the surface of the printing plate, and then the image is sequentially transferred to the blanket and the paper to perform printing.

Further, offset printing has a characteristic that it is suitable for a field in which a printed matter having high cosmeticity is obtained or a large amount of printed matter is obtained in a short time while the production of a printing plate is relatively easy. Therefore, offset printing is widely used from fields such as pamphlets, posters, and calendars that require high cosmeticity to fields such as newspapers, magazines, and telephone directories that require high-speed and mass printing. ..

Of these fields, offset rotary presses are generally used in fields that require high-speed and large-volume printing. In an offset rotary press, printing paper is mounted on a paper supply unit in a wound state, and by unwinding the winding, printing paper is supplied to the printing unit for printing. The printed printing paper is cut by the cutting section and then subjected to necessary processing such as folding to become a product. According to such a printing method, it is possible to print tens of thousands to hundreds of thousands of copies at a time, which is efficient, and the printing speed can reach as high as 100,000 or more per hour. be.

By the way, the ink composition used for offset printing is at least a coloring pigment for imparting coloring power to the ink composition, and a binder resin for dispersing the coloring pigment and fixing the coloring pigment on the surface of paper after printing. , An oil component for dissolving the binder resin to impart fluidity to the ink composition, and an extender pigment for adjusting characteristics such as viscosity in the ink composition are generally included (for example, Patent Document 1-). 5).

Japanese Unexamined Patent Publication No. 2018-59066 Japanese Unexamined Patent Publication No. 2017-88714 Japanese Unexamined Patent Publication No. 2017-31357 Japanese Unexamined Patent Publication No. 2016-222785 Japanese Unexamined Patent Publication No. 2016-11407

By the way, as the extender pigment, an inorganic calcium salt is widely used from the viewpoint of the cost of the offset printing ink composition. However, the ink composition containing the inorganic calcium salt has room for improvement with respect to the time-dependent decrease in the halftone dot printing area during offset printing.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an ink composition for offset printing which is excellent in suppressing a decrease in the halftone dot printing area with time.

Another object of the present invention is to provide a printed matter provided with a printed layer formed from the above ink composition, and a method for producing the printed matter.

That is, the present invention is an ink composition for offset printing containing a coloring pigment, an extender pigment, a binder resin, and an oil component, further comprising an aminocarboxylic acid-based chelating agent, and the extender pigment is an inorganic calcium salt. The present invention relates to an ink composition for offset printing in which the mass ratio of the inorganic calcium salt to the aminocarboxylic acid-based chelating agent (inorganic calcium salt / aminocarboxylic acid-based chelating agent) is 1 or more and 50 or less.

The present invention also relates to a printed matter provided with a printing layer formed from the offset printing ink composition.

The present invention also relates to a method for producing a printed matter, which comprises a step of printing using the offset printing ink composition.

The details of the action mechanism of the effect in the offset printing ink composition of the present invention are unknown, but it is presumed as follows. However, the present invention does not have to be construed as being limited to this mechanism of action.

The offset printing ink composition of the present invention is an offset printing ink composition containing a coloring pigment, an extender pigment, a binder resin, and an oil component, and further contains an aminocarboxylic acid-based chelating agent. , The mass ratio of the inorganic calcium salt to the aminocarboxylic acid-based chelating agent (inorganic calcium salt / aminocarboxylic acid-based chelating agent) is 1 or more and 50 or less. As a result of studies by the present inventors, it has been found that the decrease in the halftone dot printing area at the time of printing in the ink composition containing the inorganic calcium salt is due to the fact that the inorganic calcium salt inhibits the ink adhesion to the plate. rice field. In the offset printing ink composition of the present invention, by using a specific amount of an aminocarboxylic acid-based chelating agent as a component capable of capturing an inorganic calcium salt (calcium ion), the halftone dot printing area during offset printing is reduced with time. Can be suppressed.

The offset printing ink composition of the present invention contains a coloring pigment, an extender pigment, a binder resin, and an oil component, and further contains an aminocarboxylic acid-based chelating agent, and the extender pigment is an inorganic calcium salt.

<Color pigment>
The coloring pigment of the present invention is a component for imparting coloring power to an ink composition. Examples of the coloring pigment include organic and / or inorganic pigments conventionally used in ink compositions, and examples thereof include disazo yellow (pigment yellow 12, pigment yellow 13, pigment yellow 17, pigment yellow 18), and Hansa. Examples thereof include yellow pigments such as yellow, magenta pigments such as Brilliant Carmine 6B, Lake Red C and Watching Red, cyan pigments such as phthalocyanine blue, phthalocyanine green and alkali blue, and black pigments such as carbon black.

The proportion of the coloring pigment in the ink composition is not particularly limited and may be appropriately adjusted in consideration of the degree of required coloring power, and examples thereof include about 8 to 30% by mass. The yellow pigment is used for the yellow ink composition, the magenta pigment is used for the magenta ink composition, the cyan pigment is used for the cyan ink composition, and the black pigment is used for the black ink composition. In the case of preparation, it is also possible to use a pigment of another color in combination as a complementary color, or to add an ink composition of another color.

<Constitution pigment>
The extender pigment of the present invention is an inorganic calcium salt. As the inorganic calcium salt, known ones can be used without limitation, and for example, calcium carbonate, calcium chloride, calcium nitrate, calcium sulfate, calcium phosphate, calcium oxide, calcium hydroxide, calcium fluoride, calcium bromide, calcium iodide, etc. Calcium carbide, calcium phosphate, calcium hydrogencarbonate, calcium sulfite, calcium silicate, calcium pyrophosphate, calcium hypochlorate, hydroxyapatite and the like can be mentioned. The extender pigment is also called a colorless pigment and is preferably used for adjusting characteristics such as fluidity in the ink composition. Therefore, clay, talc, kaolinite (kaolin), barium sulfate, etc. It is also possible to add extender pigments conventionally used in ink compositions such as silicon oxide, bentonite, and titanium oxide to the ink composition.

The proportion of the inorganic calcium salt in the ink composition is preferably 0.5% by mass or more, more preferably 1% by mass or more, from the viewpoint of the viscosity and coloring power of the ink composition. It is more preferably 5% by mass or more, preferably 10% by mass or less, more preferably 8% by mass or less, and further preferably 6% by mass or less.

<Binder resin>
The binder resin of the present invention is a component that functions as a binder for fixing the pigment on the surface of printing paper, and is also a component used for dispersing the pigment in an ink composition. Examples of the binder resin include those usually used in the field of ink compositions, and examples thereof include rosin-modified phenolic resin, rosin-modified maleic acid resin, rosin-modified alkyd resin, rosin-modified petroleum resin, and rosin. Examples thereof include ester resins, petroleum resin-modified phenolic resins, acrylic-modified phenolic resins, alkyd resins, vegetable oil-modified alkyd resins, and petroleum resins. The binder resin usually has a weight average molecular weight of about 1,000 to 300,000. The binder resin can be used alone or in combination of two or more.

Among these, from the viewpoint of good pigment dispersibility, print quality, and stable printability over a long period of time, the binder resin is selected from the group consisting of a rosin-modified phenol resin, a rosin-modified maleic acid resin, and an alkyd resin. It preferably contains at least one, and more preferably contains a rosin-modified phenolic resin.

The binder resin may be used in a state of being varnished by being dissolved or dispersed by being heated together with an oil component described later. Further, when preparing the varnish, a metal alkoxy compound having a divalent value or higher may be added as a gelling agent into the dissolved varnish obtained by dissolving the binder resin to obtain a gelled varnish. It is preferable to prepare a gelled varnish from a binder resin and use it for preparing an ink composition because an appropriate viscoelasticity can be imparted to the ink composition.

The proportion of the binder resin in the ink composition is preferably about 10 to 45% by mass, more preferably about 10 to 30% by mass.

<Oil component>
The oil component of the present invention is used to dissolve a binder resin to form a varnish or to adjust the viscosity of an ink composition. Examples of the oil component include vegetable oil and / or mineral oil, and those used in the preparation of conventional ink compositions can be used without particular limitation. The oil component can be used alone or in combination of two or more.

Examples of the vegetable oil include drying oils such as soybean oil, cotton seed oil, flaxseed oil, safflower oil, tung oil, tall oil, dehydrated castor oil, and canola oil, and semi-drying oils. In addition, the vegetable oil may contain a fatty acid ester compound derived from the vegetable oil. Examples of the fatty acid ester compound derived from the vegetable oil include the fatty acid monoalkyl ester compound derived from the vegetable oil. Examples of the fatty acid constituting the fatty acid monoalkyl ester compound include stearic acid, isostearic acid, hydroxystearic acid, oleic acid, linolenic acid, linolenic acid, eleostearic acid and the like, which are saturated or unsaturated with 16 to 20 carbon atoms. Fatty acids are preferred. Examples of the alkyl group constituting the fatty acid monoalkyl ester compound include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, 2-ethylhexyl group and the like having 1 to 10 carbon atoms. Alkyl group of is preferably mentioned.

Examples of the mineral oil include a light mineral oil also called a solvent and a heavy mineral oil which is a lubricating oil.

Examples of the light mineral oil include non-aromatic petroleum solvents having a boiling point of 160 ° C. or higher, preferably a boiling point of 200 ° C. or higher. Examples of the non-aromatic petroleum solvent include "No. 0 solvent", "AF solvent No. 5," "AF solvent No. 6," "AF solvent No. 7" manufactured by JX Nikko Nisseki Energy Co., Ltd. Be done.

Examples of the heavy mineral oil include various lubricating oils that have been classified as spindle oil, machine oil, dynamo oil, cylinder oil and the like. Among these, from the viewpoint of adapting to the OSHA standard and the EU standard in the United States, it is preferable that the content of the condensed polycyclic aromatic component is suppressed. Examples of the heavy mineral oil include "ink oil H8" and "ink oil H35" manufactured by JX Nikko Nisseki Energy Co., Ltd., "SNH8", "SNH46" and "SNH220" manufactured by Sankyo Yuka Kogyo Co., Ltd. Examples include "SNH540".

The proportion of the oil component in the ink composition is preferably about 30 to 70% by mass, more preferably about 40 to 70% by mass.

<Amino carboxylic acid chelating agent>
The aminocarboxylic acid-based chelating agent of the present invention is a component capable of capturing an inorganic calcium salt (calcium ion) contained in an ink composition. In the aminocarboxylic acid-based chelating agent, the amino groups (-NR ¹ R ² , -NHR ¹ , -NH ₃ , in the formula, R ¹ and R ² are independently monovalent or divalent organic, respectively, in the molecule. It may be a group and may be bonded to each other to form a ring), and may have a carboxyl group, and may be either a low molecular weight chelating agent or a high molecular weight chelating agent (chelating resin). However, a low molecular weight chelating agent (for example, having a molecular weight of about 500 or less) is preferable. The aminocarboxylic acid-based chelating agent can be used alone or in combination of two or more.

Examples of the low molecular weight aminocarboxylic acid-based chelating agent include ethylenebisnitrylotetraacetic acid (EDTA), nitrilotriacetic acid (NTA), diethylenetriaminepentaacetic acid (DTPA), and N- (2-hydroxyethyl) ethylenediaminetriacetic acid (. HEDTA), triethylenetetraaminehexacetic acid (TTHA), trimethylenedinitridilotetraacetic acid (PDTA), 2-hydroxypropane-1,3-diaminetetraacetic acid (DPTA-OH), 2-hydroxyethyliminodiacetic acid (HEIDA). ), N, N-bis (2-hydroxyethyl) glycine (DHEG), ethylenebis (oxyethylenediaminetrilo) tetraacetic acid (GEDTA), N, N-bis (carboxymethyl), N, N'-ethylenediaminediaminedic acid (EDDS) and the like; these salts and the like can be mentioned.

The proportion of the aminocarboxylic acid-based chelating agent in the ink composition is preferably 0.1% by mass or more, preferably 0.2% by mass or more, from the viewpoint of suppressing a decrease in the halftone dot printing area with time. Is more preferably 0.4% by mass or more, and from the viewpoint of suppressing a decrease in the halftone dot printing area with time and preventing the generation of roller strips, it is preferably 3% by mass or less. It is more preferably 2% by mass or less, and further preferably 1.5% by mass or less.

Further, in the offset printing ink composition of the present invention, the mass ratio of the inorganic calcium salt to the aminocarboxylic acid-based chelating agent (inorganic calcium salt / aminocarboxylic acid-based chelating agent) is 1 or more and 50 or less. The mass ratio of the inorganic calcium salt to the aminocarboxylic acid-based chelating agent (inorganic calcium salt / aminocarboxylic acid-based chelating agent) is from the viewpoint of suppressing the decrease in halftone dot printing area with time and preventing the generation of roller strips. It is preferably 2 or more, more preferably 5 or more, and from the viewpoint of suppressing a decrease in the halftone dot printing area with time, it is preferably 30 or less, and more preferably 10 or less.

In the offset printing ink composition of the present invention, various components can be added in addition to the above-mentioned components as necessary from the viewpoint of improving printing performance and the like. Examples of such various components include waxes such as polyethylene wax, olefin wax, and Fisher Tropsch wax, salts such as phosphate, alcohols, antioxidants, and the like.

The total ratio of the coloring pigment, the extender pigment, the binder resin, the oil component, and the aminocarboxylic acid-based chelating agent in the ink composition is preferably 70% by mass or more, preferably 80% by mass or more. Is more preferable, and 90% by mass or more is further preferable.

Conventionally known methods can be applied to prepare the offset printing ink composition of the present invention. After mixing each of the above components, the coloring pigment is dispersed by kneading with a bead mill or a three-roll mill, and if necessary, oil components and additives (antioxidants, alcohols, waxes, etc.). Etc. may be added and stirred well to further adjust the viscosity. Further, the binder resin may be dissolved in an oil component such as vegetable oil or mineral oil to form a varnish or gel varnish. The viscosity of the ink composition can be exemplified by a value of 5 to 30 Pa · s at 25 ° C. by a Raleigh viscometer, but is not particularly limited.

<Printed matter and its manufacturing method>
The printed matter of the present invention is provided with a printed layer formed from the offset printing ink composition. In addition, the method for producing a printed matter of the present invention includes a step of printing using the offset printing ink composition. Printing is carried out using ordinary offset lithographic printing technology, and offset lithographic printing may be a printing method using dampening water with water, or by using a dedicated lithographic printing plate, dampening water is used. A waterless printing method may be used in which printing is performed without using.

Hereinafter, the present invention will be described with reference to Examples and the like, but the present invention is not limited to these.

<Example 1>
<Preparation of gel varnish>
A four-necked flask equipped with a condenser, a thermometer and a stirrer, 35 parts by mass of rosin-modified phenol resin (trade name "Hariphenol T-3120", manufactured by Harima Kasei Co., Ltd.) as a binder resin, and soybean oil as an oil component. After charging 20 parts by mass and 44.5 parts by mass of mineral oil (trade name "AF Solvent No. 7", manufactured by JX Nippon Oil Energy Co., Ltd.), the temperature is raised to 200 ° C. and the same temperature is maintained for 1 hour. After dissolving the resin, 0.5 parts by mass of ethylacetacetate aluminum diisopropylate (trade name "ALCH", manufactured by Kawaken Fine Chemicals Co., Ltd.) was charged as a gelling agent, and then heated and held at 170 ° C. for 60 minutes. , Gel varnish was prepared.

<Preparation of ink composition for offset printing>
55 parts by mass of gel varnish obtained above, 15 parts by mass of coloring pigment (trade name "Carmine 6B", manufactured by Sumika Color Co., Ltd.), calcium carbonate (trade name "Shiro Gloss Flower T-DD", Shiraishi Calcium Co., Ltd.) as an inorganic calcium salt (Manufactured) 4 parts by mass, as an aminocarboxylic acid-based chelating agent, EDTA triammonium salt (trade name "Kirest 3N-50", solid content 50% by mass, manufactured by Kirest Co., Ltd.) 0.4 parts by mass, and as an oil component, Mineral oil (trade name "AF Solvent No. 7", manufactured by JX Nikko Nisseki Energy Co., Ltd.) was added by 25.6 parts by mass and kneaded with a three-roll mill to obtain the offset printing ink composition of Example 1. rice field.

<Example 2-8, Comparative Example 1-3>
In each Example and each Comparative Example, the same operation as in Example 1 was performed except that each component used was changed to the raw materials and blending amounts shown in Table 1, and each Example and each Comparative Example were offset. A printing ink composition was prepared.

Each item of the offset printing ink composition obtained above was evaluated according to the following evaluation method. The results are shown in Table 1.

[Evaluation of the decrease in halftone dot printing area over time]
To evaluate the decrease in halftone dot printing area over time, printing was performed with an offset sheet-fed printing press LITHRONE L426 (Komori Corporation) at a speed of 10,000 sheets / hour, and using a SpectroEye manufactured by GretagMacbeth, printing was started and 5 The density at 25% halftone dots of the printed matter at the end of printing 000 sheets was measured and evaluated by the following halftone dot area retention rate.
Halftone dot area retention rate (%) = (halftone dot area at the end of printing 5,000 sheets) ÷ (halftone dot area at the start of printing) x 100

[Evaluation of roller strip]
The evaluation of the roller strip was made by visually confirming the presence or absence of the roller strip (a phenomenon in which ink does not adhere to the rollers) under the above printing conditions, and evaluating by the number of copies printed when the phenomenon occurred. The results are shown in Table 1. In Table 1, "not generated" means that the roller strip did not occur even after printing 10,000 copies.

In Table 1, Chelest 3N-50 is an EDTA triammonium salt (trade name “Chelest 3N-50”, solid content 50% by mass, manufactured by Chelest);
Chelest C is an EDTA trisodium salt (trade name "Chelest C", solid content 100% by mass (including composition water), manufactured by Chelest);
Chelest 110 is EDTA (trade name "Chelest 110", solid content 100% by mass, manufactured by Chelest);
Chelest 70 is NTA trisodium salt (trade name "Chelest 70", solid content 70% by mass, manufactured by Chelest);
Kirest PC-45 represents DPTA trisodium salt (trade name "Kirest PC-45", solid content 45% by mass, manufactured by Kirest Co., Ltd.).

Claims (4)

An offset printing ink composition containing a coloring pigment, an extender pigment, a binder resin, and an oil component.
In addition, it contains an aminocarboxylic acid-based chelating agent.
The extender pigment is an inorganic calcium salt and is
An offset printing ink composition, wherein the mass ratio of the inorganic calcium salt to the aminocarboxylic acid-based chelating agent (inorganic calcium salt / aminocarboxylic acid-based chelating agent) is 1 or more and 50 or less. The offset printing ink composition according to claim 1, wherein the proportion of the aminocarboxylic acid-based chelating agent is 0.1% by mass or more and 3% by mass or less in the printing ink composition. A printed matter characterized in that a printed matter formed from the offset printing ink composition according to claim 1 or 2 is provided. A method for producing a printed matter, which comprises a step of printing using the offset printing ink composition according to claim 1 or 2.