JP5010264B2 - Heatset offset ink composition - Google Patents

Description

The present invention relates to an ink composition for heat-set type offset printing, and more particularly to a heat-set type ink composition for offset printing excellent in low-temperature drying properties and oil-proofing performance on the surface of printing paper.

Conventionally, heat set drying and oxidation polymerization drying are known as drying methods in offset printing. Heat-set drying is a method in which after printing an offset printing ink containing a low-boiling petroleum solvent, the printing paper surface is heated to evaporate the solvent. This drying method is also called rotary printing (hereinafter referred to as “heat set type off-wheel printing (method)” which is a combination of this drying method and the printing method, which is required to be dried quickly after being printed and wound up. Used).

Usually, a drying system in heat-set type off-wheel printing has a paper surface temperature of 100 ° C. by a drying device adjacent to the printing machine (there are methods such as a hot air blowing type, a direct fire burner type, and combinations thereof). Heat until it reaches above, forcibly evaporate the low boiling point petroleum solvent. Accordingly, since the binder resin, the colorant, and the like can be fixed to the print medium (mostly paper) in a short time, the printing system is extremely productive.

However, when the paper surface temperature is set to 100 ° C. or higher as described above, there are problems such as generation of wrinkles on the paper and high energy costs. To prevent this, the paper surface temperature during drying is as low as possible. There is a request to print. In recent years, printing speed has been increased in order to improve printing efficiency, and the time required for the printed matter to pass through the dryer has also been shortened. Therefore, in order to obtain a good printed material under such printing conditions, there is a demand for a heat-set offset printing ink composition that dries with the addition of less heat energy.

Conventionally, as a method for improving the drying property of an ink composition for heat-set offset printing, an increase in the amount of a solvent having a low boiling point has been attempted. However, when the content of the solvent having a low boiling point increases, the amount of volatilization of the solvent on the printing press increases, which causes problems such as a decrease in the stability of the ink on the printing press. For this reason, there is a limit to improving the drying property by increasing the content of the solvent having a low boiling point.

In addition, if a hand is in contact with the printed material created by the heat-set type off-wheel printing method for a long time, the ink adheres to the hand and gets dirty, or a part of the printed photograph disappears. It may be pointed out. This is due to the fact that the ink binder resin once fixed to the printing paper is dissolved and eluted again by the sebum of the finger due to the evaporation of the solvent. The heat setting that fixes the binder resin just by evaporating the solvent. It can be said that the fate of the method. In other words, the binder resin fixed only by evaporation of the solvent has no change in properties as a resin even after printing, and its solubility in oil hardly changes, so it can be easily re-dissolved by oil such as sebum. Then, it will fall out of the page. In recent years, there has been a problem that, when the demand for higher quality of printed materials is increasing, when such printed portions disappear in printed materials such as photographs, the commercial value is remarkably lowered.

On the other hand, the oxidation polymerization type drying method is a method in which a drying oil contained in the ink or a binder resin component having an unsaturated bond is oxidized and polymerized using oxygen in the air to form a high molecular weight film and dried. It is. In this drying method, since it is not necessary to evaporate the solvent, drying at room temperature is possible. In addition, the molecular weight effect by oxidative polymerization (in the polymer obtained by polymerizing the same monomer etc., the higher the molecular weight, the solvent As a result, the binder resin is less likely to be redissolved. Therefore, the oil does not disappear due to the oil component of the sebum level.

So, by adding an oxidation polymerization type drying method to the heat set type drying method as an auxiliary, so-called hybrid type heat set type offset printing ink that has the good parts of both printing methods can be obtained. Be expected. That is, although it is a heat-set type offset printing ink, it is expected to dry at a lower temperature (100 ° C. or lower) than a normal one and to have a high oil removal resistance.

By the way, in order to dry a printed matter by an oxidative polymerization reaction, a metal soap type dryer is generally added as a catalyst for promoting the oxidative polymerization reaction. However, when such a catalyst is added, the oxidative polymerization reaction is promoted even when the ink is stored, and the polymer component has a high molecular weight at the surface portion of the ink in contact with the air to form a film. This is called “ink skinning”, and the skinned ink cannot be used for printing. Therefore, in order to prevent such skinning during storage, a method of increasing storage stability by adding a phenol-based antioxidant or the like (for example, see Non-Patent Document 1) is also known. However, while the antioxidant improves the storage stability, it also has a side effect of inhibiting the oxidative polymerization reaction after printing and delaying drying. Since drying and storage stability are incompatible with each other in this way, a method that improves both the storage stability and drying of ink as much as possible by balancing the addition amount of the dryer and antioxidant. Has been studied. As a result, in the sheet-fed printing method employing oxidative polymerization type drying, the printed matter is left to dry for several hours, and the amount of antioxidant added is kept within the range that can be dried within this time. To use.

On the other hand, the heat-set type off-wheel printing method has the advantage of high productivity brought about by the evaporation drying method, so that once the solvent evaporates, it can enter a post-processing step such as cutting immediately after printing. Yes, the situation is different from the sheet-fed printing method that takes time to dry. For this reason, in the heat set type off-wheel printing method, the conventional oxidation polymerization method as described above, which requires a long time for drying, cannot be employed as it is. However, adding a large amount of metal soap type dryer to obtain a drying speed that does not impair off-wheel printing productivity will cause a problem of skinning, and a practical ink composition will be generated. Can't get. Therefore, if a large amount of an antioxidant is added in order to improve the storage stability, the drying speed is slowed down and the productivity of off-wheel printing is impaired. After all, even if the conventional oxidation polymerization type drying method is added to the heat-set type offset printing ink composition as it is, it is not possible to obtain only the advantages of both drying methods, and the purpose is high productivity. In the heat set type off-wheel printing method, it is necessary to rely only on the evaporation drying method.

As described above, while maintaining the high productivity and good storage stability of heatset-type off-wheel printing, it was not possible to give it low-temperature drying performance or oil-proofing performance of printed matter. is there.
First edition of Color Material Engineering Handbook p. 1005 (published by the Color Material Association, 1989)

In view of such a background, the present invention maintains a high productivity, has a good drying property even at a lower temperature, and has an oil-proofing performance comparable to that of a sheet-fed printing method, and is also good. It is a technical problem to provide a heat-set type ink composition for offset printing having storage stability.

As a result of intensive studies to solve the above problems, the present inventors have found that ascorbic acid is used as an antioxidant even when a metal soap type dryer is used in an ink composition for heat-set offset printing. It has been found that the above-mentioned problems can be solved by using a specific compound called an acid ester compound.

That is, the present invention provides a heat-set offset printing ink composition containing (A) a pigment, (B) a binder resin, (C) a petroleum solvent, and (D) a vegetable oil component. Is at least one selected from the group consisting of drying oils, semi-drying oils, fatty acid esters thereof and polymerized oils, and the ink composition further includes (E) a metal soap type dryer. A heat-set type ink composition for offset printing, comprising 0.01 to 0.05% by mass based on the mass of the metal, and (F) 3 to 7% by mass of an acid ester compound of ascorbic acid. It is about.
The heat-set offset printing ink composition preferably has a phenolic antioxidant content of less than 0.08% by mass.

As described above, in the oxidative polymerization type drying method, a material that promotes oxidative polymerization is required to improve drying properties, while a material that suppresses oxidative polymerization is required to improve storage stability. . In general, when using a metal soap dryer as a material for promoting oxidative polymerization in an ink composition for offset printing, an antioxidant is used to ensure storage stability, but oxidative polymerization is promoted. If the inhibitory action is superior to the action, the storage stability will be improved instead of drying, and if the inhibitory action is inferior, the dryability will be improved instead of reducing the storage stability. That is, the antioxidant inhibits the oxidative polymerization reaction in the drying process, and thus it can be said that increasing the storage stability with the antioxidant sacrifices the drying speed. It is extremely difficult to simultaneously improve such contradictory performances in a normal oxidation polymerization type drying method mainly for drying at room temperature.

In contrast, the present invention is an attempt to add an oxidation polymerization type drying method to a heat set type drying method. As a result of investigations focusing on the fact that an acid ester compound of ascorbic acid, which is a kind of antioxidant, deactivates the antioxidant action by heat, the present inventors have effectively improved the antioxidant action during storage. The present inventors have found that although skinning is suppressed, the oxidative polymerization reaction by a dryer is not inhibited in the drying process. That is, the hot air applied in the drying process of heat-set type off-wheel printing is originally for evaporating the solvent, but the heat at this time inactivates the acid ester compound of ascorbic acid and oxidative polymerization The reaction can be prevented. As a result, a large amount of metal soap dryer and ascorbic acid ester compound are added to the ink, and the stability is increased by the action of the acid ester compound of ascorbic acid during storage, and metal soap is used in the drying process during actual printing. It becomes possible to dry quickly by the action of the mold dryer. In other words, even if a sufficient amount of metal soap type dryer that does not impair the productivity of off-wheel printing is used as an oxidation polymerization catalyst, an appropriate amount of an ascorbic acid ester compound is added as an antioxidant. The inventors have found that the storage stability can be ensured without sacrificing the drying speed, and have completed the present invention. Therefore, the heat-set type offset printing ink composition of the present invention has high productivity and excellent storage stability even under low temperature drying conditions.

That is, the heat-set offset printing ink composition of the present invention contains a specific amount of a metal soap dryer and an acid ester of ascorbic acid, respectively, and is a drying oil, a semi-drying oil, a fatty acid ester thereof, and a polymerization Since it contains at least one vegetable oil component selected from the group consisting of oils, it can be dried at a lower temperature compared to conventional types of inks that rely solely on evaporation drying of solvent components, In addition, it has high oil resistance.

Ascorbic acid also has the same antioxidant action as the acid ester compound of ascorbic acid. However, since ascorbic acid that has not been esterified is water-soluble, if ascorbic acid elutes in the dampening water during printing, the dampening water may be altered to reduce printability. Furthermore, since ascorbic acid is oxidized and colored, the solid portion of the printed material to which the fountain solution containing it is transferred is soiled. In particular, in the type in which dampening water is circulated and supplied, the concentration of ascorbic acid in the dampening water tends to be high. For the above reasons, it is not appropriate to use ascorbic acid that is not esterified in the present invention.
Hereinafter, the present invention will be described in detail.

The heat-set type offset printing ink composition of the present invention is used in a printing method having a dry form in which a solvent is evaporated by heating after printing, and contains a specific amount of a metal soap type dryer and an acid ester of ascorbic acid, respectively. And at least one vegetable oil component selected from the group consisting of a drying oil, a semi-drying oil, a fatty acid ester thereof, and a polymerized oil.

Hereinafter, the heat-set offset printing ink composition of the present invention (hereinafter, “heat-set offset printing ink composition” may be simply referred to as “offset printing ink composition”). The material will be described.

As the pigment [component (A)] used for obtaining the ink composition for offset printing of the present invention, colorless or colored inorganic or organic pigments generally used for offset printing inks can be used. Inorganic pigments such as titanium dioxide, barium sulfate, calcium carbonate, organic bentonite, silicon dioxide, iron oxide, carbon black; organic pigments such as azo pigments, lake pigments, phthalocyanine pigments, isoindoline pigments, anthraquinone pigments, quinacridone pigments, etc. Can be illustrated. These pigments can be used alone or in admixture of two or more. The content of the pigment in the offset printing ink composition is appropriately 5 to 50% by mass.

As the binder resin [component (B)] constituting the ink composition for offset printing of the present invention, a binder resin generally used for offset printing ink can be used. Specifically, rosin-modified phenol resin, petroleum resin Examples thereof include various phenol resins such as modified phenol resins, petroleum resins, various alkyd resins, rosin ester resins, rosin modified maleic acid resins, polyester resins, these drying oil-modified resins, and gilsonite resins. These compounds can be used alone or in admixture of two or more.

Among the binder resins, rosin-modified phenol resins and rosin-modified maleic resins are preferable, and rosin-modified phenol resins are particularly preferable. Thereby, the effect of this invention can be acquired favorably.

Examples of the rosin-modified phenol resin include those obtained by reaction of rosins or derivatives thereof, phenol aldehyde addition condensates (so-called resole), and, if necessary, polyhydric alcohols. Here, the rosins or their derivatives are preferably rosins or their carboxyl group-containing derivatives. Examples of the rosins include gum rosin, wood rosin, tall oil rosin, disproportionated rosin, hydrogenated rosin or polymers thereof, and derivatives thereof include unsaturated carboxylic acids such as maleic acid, itaconic acid, and crotonic acid. Examples thereof include carboxyl group-containing derivatives such as rosin derivatives to which an acid has been added. Moreover, as said rosin modified maleic acid resin, what is normally used for offset printing inks can be used.
The content of the binder resin in the offset printing ink composition is suitably 10 to 40% by mass.

If necessary, the binder resin can be used to crosslink the resin by using an appropriate amount of a gelling agent (about 15% by mass or less based on the binder resin). Examples of the gelling agent used in such a case include aluminum alcoholates and aluminum chelate compounds. Preferred specific examples include aluminum triisopropoxide, mono-sec-butoxyaluminum diisopropoxide, and aluminum trioxide. Examples include -sec-butoxide, ethyl acetate aluminum diisopropoxide, and aluminum trisethyl acetoacetate.

The petroleum solvent [component (C)] constituting the offset printing ink composition of the present invention has a boiling point of 160 ° C. or higher, preferably 200 ° C. or higher, which is incompatible with water used as the offset printing solvent. Can be suitably used. Specifically, petroleum solvents such as n-paraffin solvents, isoparaffin solvents, naphthene solvents, aromatic solvents, α-olefin solvents; light oil, spindle oil, machine oil, cylinder oil, turpentine oil, mineral spirit These solvents can be used alone or in combination of two or more, but it is preferable to use a non-aromatic solvent in view of environmental problems in recent years.
The content of the petroleum solvent in the offset printing ink composition is 20% by mass or more, and preferably 40 to 53% by mass.

As the vegetable oil component [component (D)] constituting the offset printing ink composition of the present invention, among vegetable oils generally used in offset printing ink, drying oil, semi-drying oil, fatty acid esters thereof, and At least one selected from the group consisting of polymerized oils can be used. Specifically, dry oil or semi-dry oil such as soybean oil, cottonseed oil, linseed oil, safflower oil, tung oil, tall oil, dehydrated castor oil, canola oil, polymerized vegetable oils such as these fatty acid esters, polymerized linseed oil, etc. Can be mentioned. These vegetable oil components may be used alone or in combination of two or more.

Examples of the fatty acid ester include fatty acid monoalkyl ester compounds. The fatty acid constituting the fatty acid monoester compound is preferably a saturated or unsaturated fatty acid having 16 to 20 carbon atoms, such as stearic acid, isostearic acid, hydroxystearic acid, oleic acid, linoleic acid, linolenic acid, eleostearic acid, and the like. Can be illustrated. As the alkyl group derived from alcohol constituting the fatty acid monoester compound, those having 1 to 10 carbon atoms are preferable, and alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, 2-ethylhexyl and the like are preferable. It can be illustrated. Among the vegetable oil components, soybean oil, linseed oil, and fatty acid esters thereof are preferable. Soybean oil is particularly preferable in terms of availability at low cost, and linseed oil is particularly preferable in terms of improving drying properties. Thereby, the effect of this invention can be acquired favorably.

Content of the vegetable oil component in the said ink composition for offset printing becomes like this. Preferably it is 0.1-15 mass%, More preferably, it is 7-10 mass%.
In addition, it is preferable to use it so that the total usage-amount of the said petroleum-based solvent and a vegetable oil component may be 30-60 mass% in the said ink composition for offset printing.

As the metal soap dryer (component (E)) constituting the ink composition for offset printing of the present invention, octylic acid, naphthenic acid, resin acid, tall oil fatty acid, soybean oil fatty acid, hydroxy higher fatty acid and the like, cobalt, Conventionally used offset printing inks such as metal salts with manganese, lead, zinc, copper, iron, calcium, zirconium, aluminum, or rare earth metal salts with cerium or the like can be used. Specifically, manganese octylate, cobalt octylate, zirconium octylate, calcium octylate, iron octylate, copper octylate, manganese naphthenate, cobalt naphthenate, zirconium naphthenate, calcium naphthenate, iron naphthenate, naphthenate An example is acid copper. Of these, metal octylate and metal naphthenate are preferable, and manganese octylate and cobalt naphthenate are particularly preferable. Thereby, the effect of this invention can be acquired favorably. These compounds can be used alone or in admixture of two or more.

The content of the metal soap type dryer in the ink composition for offset printing is 0.01 to 0.05 mass%, preferably 0.02 to 0.03 mass, based on the mass of the metal contained in the dryer. %.

Usually, the dryer is often added in the form of a metal soap solution, and “based on the mass of the metal contained in the dryer” means the mass converted to only the metal component in the dryer, that is, the metal soap type dryer. It is based on the mass calculated by multiplying the mass of the solid content by the mass proportion of the metal in the dryer molecule. For example, when 100 g of ink contains 2 g of a 10% solution of manganese octylate [Mn (C ₇ H ₁₅ COOMn) ₂ , molecular weight 341, Mn = 55] as a metal soap-type dryer, The content of the dryer based on the mass of "
(2 × 0.1 × 55/341) /100×100≈0.032 [mass%]
It becomes.
If the content is less than 0.01% by mass, a sufficient drying rate cannot be obtained, and if it exceeds 0.05% by mass, there is a problem in terms of storage stability.

Examples of the acid ester of ascorbic acid constituting the ink composition for offset printing of the present invention include [Component (F)] ascorbic acid carboxylic acid ester, ascorbic acid sulfuric acid ester and the like, and ascorbic acid carboxylic acid ester is preferable. .

As the ascorbic acid carboxylic acid ester, ascorbic acid monocarboxylic acid ester, ascorbic acid dicarboxylic acid ester or the like is preferably used. Specific examples include, for example, ascorbic acid lower fatty acid esters (1 to 9 carbon atoms) such as ascorbic acid acetate; ascorbic acid aromatic carboxylic acid esters such as ascorbic acid benzoic acid ester; ascorbic acid monopalmitic acid ester and ascorbic acid Examples include ascorbic acid higher fatty acid esters (having 10 or more carbon atoms) such as dipalmitic acid ester, ascorbic acid monostearic acid ester, and ascorbic acid distearic acid ester. Further, as the higher fatty acid constituting the higher fatty acid ester of ascorbic acid, unsaturated fatty acids such as oleic acid, linoleic acid, and linolenic acid can also be used, but saturated fatty acids from the point that the effect of the present invention can be obtained well. Is preferred.

The acid ester of ascorbic acid is preferably an ascorbic acid higher fatty acid ester having 10 or more carbon atoms, more preferably having 14 to 22 carbon atoms, still more preferably having 15 to 17 carbon atoms, and palmitic acid for ascorbic acid. Acid esters and stearic acid esters of ascorbic acid are particularly preferred, and palmitic acid esters of ascorbic acid are most preferred. Palmitic acid esters of ascorbic acid are desirable because they are easily available industrially. These acid esters of ascorbic acid can be used alone or in admixture of two or more.

The content of the acid ester of ascorbic acid in the ink composition for offset printing is 3 to 7% by mass. If the content is less than 3% by mass, the ink composition for offset printing is covered during storage, and if it exceeds 7% by mass, drying under the condition where the paper surface temperature is lower than 90 ° C. is insufficient. . Preferably, it is 3 to 6% by mass for monoacid esters of ascorbic acid, and 5 to 6% by mass for diacid esters of ascorbic acid.

In addition to the above-described constituent materials, the offset printing ink composition of the present invention includes, as necessary, a pigment dispersant, a leveling aid, a friction resistance improver, an anti-set-off agent, a nonionic surfactant, and the like. These additives can be used as appropriate.

The offset printing ink composition of the present invention preferably has a phenolic antioxidant content of less than 0.08% by mass. As more phenolic antioxidant is added, the oxidative polymerization reaction tends to be inhibited and the drying rate tends to decrease. Therefore, the content of the phenolic antioxidant is more preferably 0.05% by mass or less, and still more preferably not contained at all.

Next, the manufacturing method of the ink composition for offset printing containing the said structural material is demonstrated.
In order to produce the ink composition for offset printing of the present invention, conventionally known production methods (dry grinding method, flushing method, etc.) can be used.
For example, (1) a varnish for oil-based printing ink is prepared in advance by heating a binder resin, a vegetable oil component and / or a petroleum solvent, and a gelling agent as necessary. Next, a base for oil-based printing ink is obtained by adding dried pigment, vegetable oil component, petroleum-based solvent, and pigment dispersant as necessary to varnish for oil-based printing ink, and kneading and dispersing with bead mill, three-roll mill, etc. . Furthermore, a method for adjusting a predetermined viscosity by adding a metal soap dryer, an acid ester compound of ascorbic acid to an oil-based printing ink base, and adding an oil-based printing ink varnish, a vegetable oil component, a petroleum solvent, and additives as necessary. (2) A varnish for an oil-based printing ink is prepared in advance by heating a binder resin, a vegetable oil component and / or a petroleum solvent, and a gelling agent as necessary. Stirring device that has a mechanism to add water varnish for oil-based printing ink to water suspension of pigment (water-containing cake or dry pigment to make water suspension) and remove solvent. And then dewatering until the water content in the flushed composition is preferably 2% by mass or less. Next, an oil-based printing ink base is obtained by adding a varnish for oil-based printing ink and the like to the dehydrated composition, if necessary, and kneading and dispersing with a bead mill or a three-roll mill. Furthermore, add a metal soap-type dryer and an acid ester compound of ascorbic acid to the base for oil-based printing inks, and adjust the viscosity to the desired level by adding varnish for oil-based printing inks, vegetable oil components, petroleum-based solvents, and additives as necessary. The method of doing is mentioned.

Since the ink composition for offset printing of the present invention is excellent in drying property at a low temperature, it can be suitably used at a drying temperature of 100 ° C. or less, more preferably 60 to 100 ° C., still more preferably. Can be used at a drying temperature of 70 to 100 ° C.

The ink composition for offset printing of the present invention obtained from such a constituent material and production method has high productivity, can prevent skinning during storage, and has good on-press stability. When printing is performed using a heat-set type off-wheel printing press, drying is possible even under conditions where the paper surface temperature is lower than 90 ° C., and printed matter is required from the viewpoint of preventing rubbing such as sebum. The oil drop-off performance is good.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples. Unless otherwise specified, “%” means “mass%” and “part” means “part by mass”.

Production Example 1
<Manufacture of varnish for ink for heat set-off wheel printing>
A four-necked flask equipped with a condenser, thermometer and stirrer is charged with rosin-modified phenolic resin, soybean oil, and petroleum solvent (Aroma Free Solvent No. 7 manufactured by Nippon Oil Corporation) to the following composition and heated to 200 ° C. After warming, the mixture was heated and stirred at the same temperature for 1 hour to obtain an ink varnish for heat-set-off wheel printing.
(Mixing ratio)
Rosin-modified phenolic resin (KG-1804: manufactured by Arakawa Chemical Industries): 50 parts, soybean oil: 10 parts, petroleum solvent: 40 parts, 100 parts in total

Production Example 2
<Manufacture of base ink composition for heat set-off wheel printing>
Carmine 6B (Sumika Color Pigment) and the varnish for heat-set-off wheel ink obtained in Production Example 1 were mixed in the following composition, and kneaded sequentially with a bead mill and three rolls. Next, soybean oil and a petroleum solvent were charged so as to have the following composition and stirred to obtain a base ink composition for heat set-off wheel printing.
(Mixing ratio)
Heat set-off wheel printing ink varnish: 54.6 parts, Pigment: 16 parts, Soybean oil: 1.5 parts, Petroleum solvent: 27.9 parts Total: 100 parts

Examples 1-5, Comparative Examples 1-5
<Manufacture of ink composition for heat set-off wheel printing>
Into the base ink composition for heat-set-off wheel printing, various metal soap-type dryers and various acid esters of ascorbic acid are mixed in the resulting heat-set-off wheel printing ink composition in the amount of% shown in Table 1. Preparation and stirring were carried out to obtain ink compositions for heat set-off wheel printing of Examples 1 to 5 and Comparative Examples 1 to 5.

[Skin test]
10 g of the heat-set-off wheel printing ink composition of Examples 1 to 5 and Comparative Examples 1 to 5 was put into a mentum can (diameter: about 3 cm, depth: about 1 cm), covered, and stored at 100 ° C. When the ink was applied to the finger and the ink composition for heat-set-off wheel printing no longer adhered to the finger, it was determined that the skin was applied. Table 1 shows the number of days until skinning. For reference, with respect to the skinning time in Table 1, the skinning time of Comparative Example 1 is taken as a standard, and a thing equivalent to or longer than the standard is indicated by ○, and an object shorter than the standard is indicated by ×. Yes.

[Drying temperature]
After 0.1 cc of the heat-set-off wheel printing ink composition of Examples 1 to 5 and Comparative Examples 1 to 5 was coated on coated paper with an RI color developing machine (Made Seisakusho, machine number RI-2), Pass through the conveyor type dryer (Asahi Scientific Instruments) twice. After that, place a white paper on the color development surface of the coated paper, sandwich it between the rubber roller and metal roller of the RI color machine, and apply a certain pressure for 2 minutes. The paper surface temperature was determined as the drying temperature. The results are shown in Table 1. For reference, with respect to the drying temperature in Table 1, the drying temperature of Comparative Example 1 is used as a standard, and the one that is dried at a temperature lower than the standard is ○, and the one that is dried at a temperature equal to or higher than the standard. Each is indicated by ×.

[Oil drop test]
After 0.1 cc of the heat-set-off wheel printing ink composition of Examples 1 to 5 and Comparative Examples 1 to 5 was coated on coated paper with an RI color developing machine (Made Seisakusho, machine number RI-2), A drop of squalene (the main component of sebum) is dropped on the color surface and left for 1 minute. Thereafter, the dropped squalene was rubbed with Kimwipe (registered trademark) and evaluated by the number of rubs required until the coating film was peeled off. The results are shown in Table 1. In addition, with respect to the oil resistance test in Table 1, Comparative Example 1 was used as a standard, and those that were peeled off at the same number of times as the standard were indicated by x, and those that the ink coating was more difficult to peel than the standard were indicated by ○.

As shown in Table 1, it was confirmed that all of Examples 1 to 5 were superior to the comparative example in terms of skinning time, drying temperature, and oil removal performance. From these facts, the effectiveness of the present invention could be confirmed.

The ink composition for heat-set off-wheel printing of the present invention obtained from such a constituent material and production method can prevent skinning during storage and is printed using a heat-set off-wheel printing machine. In addition to being able to dry even under conditions of low paper surface temperature, the printed matter can achieve good resistance to rubbing by sebum.

Claims (2)

In the heat-set offset printing ink composition containing (A) a pigment, (B) a binder resin, (C) a petroleum-based solvent, and (D) a vegetable oil component,
The vegetable oil component is at least one selected from the group consisting of drying oils, semi-drying oils, fatty acid esters and polymerized oils thereof,
The ink composition further comprises (E) a metal soap type dryer, 0.01 to 0.05% by mass based on the mass of the metal contained in the dryer, and (F) an acid ester compound of ascorbic acid 3 An ink composition for heat-set offset printing, which contains ˜7% by mass. The ink composition for heat-set offset printing according to claim 1, wherein the content of the phenolic antioxidant is less than 0.08% by mass.