JP7309347B2 - Ink composition for offset printing, method for producing the same, and method for producing printed matter using the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to an ink composition for offset printing, a method for producing the same, and a method for producing a printed matter using the same.

Offset printing is a printing method that utilizes the water-repellent property of an oil-based ink composition for offset printing (hereinafter abbreviated as "ink composition" or "ink" as appropriate). Unlike the letterpress printing method that uses a plate, it is characterized by using a printing plate without unevenness. This printing plate has oleophilic image areas and hydrophilic non-image areas instead of unevenness. During printing, first, the non-image area of the printing plate is moistened with dampening water to form a water film on the surface, 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 areas where the water film is formed, but adheres only to the lipophilic image areas. Thus, printing is effected by forming an image with the ink composition on the surface of the printing plate, which is then sequentially transferred to the blanket and paper.

In addition to offset printing using dampening water as described above, a waterless offset printing method using a printing plate having a non-image portion formed with a silicone resin has also been put to practical use. In this printing method, dampening water does not repel the ink composition to form non-image areas, but the silicone resin repels the ink composition to form non-image areas. Except for these points, waterless offset printing is also a printing method common to offset printing using dampening water. Therefore, in this specification, the term "offset printing" is used as a concept including not only the printing method using dampening water but also the waterless printing method. In waterless offset printing, emulsification of the printing ink composition by dampening water does not occur, so high-quality printing with small dot gain can be performed.

Offset printing has the characteristics that it is suitable for fields in which printing plates can be produced relatively easily, and printed matter with high cosmetic quality is obtained, and in which a large amount of printed matter is obtained in a short period of time. Therefore, offset printing is widely used in fields such as pamphlets, posters, calendars, etc., which require high cosmetic quality, to fields, such as newspapers, magazines, telephone directories, etc., which require high-speed and large-volume printing. .

By the way, printed matter obtained by offset printing is in a state in which the ink composition adhering to the surface is sufficiently dried (a state in which the ink composition does not feel sticky to the touch), and this state is called tack-free. ), set-off occurs when printed matter is stacked, and ink adheres when the printed matter is touched with a finger, so it cannot be sent to the post-process or distributed as a product. . Drying of the ink composition is mainly carried out by an oxidative polymerization method in which the components contained in the ink composition undergo oxidative polymerization to increase the molecular weight and become tack-free. Evaporation drying method, penetrating drying method in which the liquid component contained in the ink composition permeates the printing paper and becomes tack-free, and UV irradiation causes the component contained in the ink composition to polymerize to increase the molecular weight and make it tack-free. can be classified into UV drying methods.

A sheet-fed printing method is often selected for printing that requires high-quality printed matter, such as posters and product packages. In this printing method, a high-quality printing paper such as art paper or coated paper or a non-permeable printing paper made of synthetic resin is used in combination with an oxidative polymerization ink composition. A drier made of a transition metal soap is generally added to the ink composition used here in order to promote oxidative polymerization after printing and realize tack-free at an early stage. As the dryer used in this case, those containing cobalt as a transition metal are said to be particularly effective in promoting oxidative polymerization. There are also moves to avoid using it. As an example of this, for example, Patent Document 1 proposes a printing ink composition that avoids the use of cobalt.

Moreover, from the viewpoint of reducing the burden on the environment, in recent years, ink compositions that positively use naturally derived raw materials have also been proposed. As such an example, for example, Patent Document 2 proposes an ink composition containing vegetable oils and beeswax, aiming at reducing the environmental load from the viewpoint of CO ₂ emissions.

JP 2004-256623 A JP 2016-166266 A

Attempts to reduce the environmental load by using naturally-derived oil components such as vegetable oils in ink compositions have been widely carried out, as shown in Patent Document 2 and the like. However, the situation in which rosin-modified phenolic resins are mainly used as binder resins in ink compositions for offset printing has not changed either in the past or at present. Rosin-modified phenolic resin is made by reacting resole, which is a polycondensation product of alkylphenol, with rosin, etc., as raw materials. Not a natural product. In addition, concerns have been pointed out that alkylphenol, which is a raw material of resol, increases the environmental load. Nevertheless, rosin-modified phenol resins are excellent as binder resins for ink compositions in terms of printability and the like, and are currently widely used as raw materials for ink compositions.

In addition, as shown in Patent Document 1, although there is a movement to refrain from using dryers containing cobalt from the viewpoint of environmental load, instead of this, for example, when using a dryer containing manganese, which has a lower environmental load, The fact is that the drying performance is inferior to the case of using a dryer containing cobalt.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an ink composition that provides sufficient printability while using materials that have a low environmental impact.

The present inventors have made intensive studies to solve the above problems, and found that even a resin that is not a resol derivative such as a rosin-modified phenolic resin has n-hexane tolerance when dissolved under predetermined conditions. shows a specific value, it can be sufficiently used as a binder resin for an ink composition by using it in combination with a vegetable oil fatty acid alkyl ester, and it can also be used as a binder resin. As a result, the setting property is improved, and even if a dryer having performance inferior to that of a cobalt-containing dryer is used, a drying property that can withstand practical use can be obtained, and the present invention has been completed. The present invention has been completed based on the above findings, and specifically provides the following.

The present invention provides an ink composition for offset printing comprising a pigment, a binder resin, and vegetable oils, wherein the binder resin is a rosin ester, and the rosin ester is obtained by heating 80 g of the rosin ester to 200°C. 120 g of soybean oil with stirring for 30 minutes to give a dissolved varnish having an n-hexane tolerance of 2 to 3 g/5 g measured by the following procedure. As at least a part of the class, the ink composition for offset printing is characterized by containing 10 to 30% by mass of a butyl ester of soybean oil fatty acid with respect to the entire composition.
Procedure: After allowing the dissolved varnish to cool to room temperature, 5 g was collected in a beaker, and while the liquid temperature in the beaker was maintained at 25°C, n-hexane was added to the dissolved varnish in the beaker little by little while stirring. In addition, determine the mass (g) of n-hexane required until the liquid in the beaker starts to become cloudy. The mass (g) of n-hexane thus obtained is defined as n-hexane tolerance (g/5g).

The ink composition for offset printing of the present invention preferably contains 2 to 10% by mass of an alkyd resin having an oil length of 50 to 90% with respect to the entire composition.

The ink composition for offset printing of the present invention preferably does not contain cobalt metal soap.

The present invention comprises a varnish preparation step of preparing a varnish, comprising a step of dissolving a rosin ester in an oil component containing vegetable oils, and adding a coloring pigment to the varnish to form a mixture, and and a kneading step in which the pigment is finely divided by a dispersing means, and the rosin ester is dissolved by stirring 80 g of the rosin ester in 120 g of soybean oil heated to 200 ° C. for 30 minutes. Offset printing, which satisfies the condition of giving a dissolved varnish having an n-hexane tolerance of 2 to 3 g/5 g, as measured by the procedure, and contains butyl ester of soybean oil fatty acid as at least a part of the vegetable oils. It is also a method for producing an ink composition.
Procedure: After allowing the dissolved varnish to cool to room temperature, 5 g was collected in a beaker, and while the liquid temperature in the beaker was maintained at 25°C, n-hexane was added to the dissolved varnish in the beaker little by little while stirring. In addition, determine the mass (g) of n-hexane required until the liquid in the beaker starts to become cloudy. The mass (g) of n-hexane thus obtained is defined as n-hexane tolerance (g/5g).

It is preferable to add an alkyd resin having an oil length of 50 to 90% when preparing the varnish in the varnish preparing step.

The present invention also provides a method for producing a printed matter, comprising the step of printing using the ink composition for offset printing.

The printed matter is preferably used for packaging.

ADVANTAGE OF THE INVENTION According to this invention, the ink composition from which sufficient printability is obtained is provided, using the material with a small environmental load.

Hereinafter, one embodiment of the ink composition for offset printing of the present invention, one embodiment of the method for producing the ink composition for offset printing of the present invention, and one embodiment of the method for producing printed matter of the present invention will be described. It should be noted that the present invention is not limited to the following embodiments and modes, and can be implemented with appropriate modifications within the scope of the present invention.

<Ink composition for offset printing>
First, an embodiment of the ink composition for offset printing of the present invention (hereinafter abbreviated as "the ink composition of the present invention", etc.) will be described. The ink composition of the present invention is used for offset printing, and belongs to the oxidative polymerization drying type that is suitably used in sheet-fed printing. The ink composition of the present invention does not contain a resol derivative, that is, a rosin-modified phenolic resin, and in this respect contributes to the realization of offset printing with reduced environmental load. In addition, the ink composition of the present invention does not contain a resol derivative and employs a binder resin that exhibits a specific value of n-hexane tolerance when dissolved under predetermined conditions. Thus, even if a drier containing a transition metal such as manganese, which is not cobalt, is used, it is possible to obtain drying properties that can withstand practical use. In this respect as well, the ink composition of the present invention contributes to the realization of offset printing with reduced environmental load.

The ink composition of the present invention contains a pigment, a binder resin, and vegetable oils, and the binder resin is not a resol derivative. By dissolving, a dissolved varnish having an n-hexane tolerance of 2 to 7 g/5 g is provided, and as at least a part of the vegetable oils, 10 to 30 masses of fatty acid alkyl esters of vegetable oils are added to the entire composition. %. Moreover, the composition of the present invention may optionally contain other components such as an alkyd resin and a drier, in addition to the components described above. Each component will be described below.

[Pigment]
Pigments include coloring pigments for imparting coloring power to the ink composition and colorless pigments for imparting properties such as viscoelasticity to the ink composition. First, these pigments will be explained.

A color pigment is a component for imparting coloring power to the ink composition. As the coloring pigment, organic and/or inorganic pigments conventionally used in printing ink compositions can be used without particular limitation.

Examples of such color pigments include disazo yellow (Pigment Yellow 12, Pigment Yellow 13, Pigment Yellow 17, Pigment Yellow 1), yellow pigments such as Hansa Yellow, and magenta pigments such as Brilliant Carmine 6B, Lake Red C, and Watching Red. , phthalocyanine blue, phthalocyanine green, cyan pigments such as alkali blue, black pigments such as carbon black, and fluorescent pigments. In the present invention, metallic powder pigments for imparting metallic colors such as gold and silver to ink compositions are also treated as coloring pigments. Examples of such metal powder pigments include gold powder, bronze powder, aluminum paste obtained by processing aluminum powder into a paste, and mica powder.

The amount of the coloring pigment to be added is exemplified at about 8 to 30% by mass with respect to the entire ink composition, but is not particularly limited. A yellow ink composition is prepared using a yellow pigment, a magenta ink composition is prepared using a magenta pigment, a cyan ink composition is prepared using a cyan pigment, and a black ink composition is prepared using a black pigment. When preparing, it is also possible to use pigments of other colors together or to add ink compositions of other colors as complementary colors.

Colorless pigments are also called extender pigments and are preferably used to adjust properties such as viscoelasticity in ink compositions. Examples of colorless pigments include clay, talc, kaolinite (kaolin), barium sulfate, calcium carbonate, silicon oxide, bentonite, and titanium oxide. The amount of the colorless pigment to be added is exemplified to be about 0 to 33% by mass with respect to the entire ink composition, but is not particularly limited.

[Binder resin]
The binder resin is a component that functions as a binder to fix the pigment on the surface of the printing paper, and is also a component that is used to disperse the pigment in the ink composition. The resin used as the binder resin in the present invention is not a resol derivative, but 80 g thereof is dissolved in 120 g of soybean oil heated to 200° C. by stirring for 30 minutes to obtain an n-hexane tolerance of 2 to 7 g/ It gives 5 g of melted varnish. Each item will be described below.

The binder resin used in the present invention is not a resol derivative. This means that it is not a rosin-modified phenolic resin. As already mentioned, the rosin-modified phenolic resin is obtained by reacting resol, which is a polycondensation product of alkylphenol, with rosin or the like as raw materials. Alkylphenol, which is a raw material of resol, is feared to function as a so-called endocrine disruptor, and is recognized as a substance that increases environmental load. Alkylphenols incorporated into resins as resole or rosin-modified phenolic resins no longer function as endocrine disruptors, but there are concerns that unreacted alkylphenols remain. There is also a demand for refraining from using ink compositions using phenolic resins for printing packaging materials. However, rosin-modified phenolic resins have extremely excellent properties as binder resins for ink compositions, and the actual situation is that there are almost no resins that can replace them.

Under these circumstances, the inventors found that a resin with a specific solubility, that is, 80 g of it was stirred in 120 g of soybean oil heated to 200° C. for 30 minutes to dissolve n- It was found that a resin that gives a dissolved varnish with a hexane tolerance of 2 to 7 g/5 g can be suitably used as a binder resin for an ink composition by using it in combination with a fatty acid alkyl ester of vegetable oil, which will be described later. The resin that dissolves under the above conditions and gives a dissolved varnish having an n-hexane tolerance of 2 to 7 g/5 g has considerably lower solubility than rosin-modified phenolic resins generally used for ink compositions. . In the present invention, it is used by dissolving it in a fatty acid alkyl ester of vegetable oil, which has a high dissolving power. At this time, even better results can be obtained by dissolving in combination with an alkyd resin having an oil length of 50 to 90%, which will be described later.

Furthermore, the present inventors have found that the setting property of the ink composition is improved by using a low-soluble resin as the binder resin as described above. The settability of the ink composition is a measure of how long it takes for the printed matter to become tack-free after printing on paper. The reason for such a result is not necessarily clear. However, it is believed that binder resins with low solubility tend to precipitate and solidify when the oil component that dissolves them is lost from the ink due to oxidative polymerization or permeation into the paper surface. It is speculated that such solidification occurred when even a small amount of oil component was lost from the ink composition because the solubility of the binder resin used was very low. Since the ink composition of the present invention exhibits such a high setting property, it is possible to obtain a practically dry state even when using a dryer containing a transition metal such as manganese instead of cobalt. This reduces the use of cobalt contained in the dryer and contributes to the realization of printing with a smaller environmental impact.

As the binder resin, not a resol derivative, but a dissolved varnish having an n-hexane tolerance of 2 to 7 g/5 g by dissolving 80 g of it in 120 g of soybean oil heated to 200° C. for 30 minutes with stirring. Anything that gives Examples of such resins include rosin esters and rosin-modified maleic acid resins, among which rosin esters are preferred.

A rosin ester is a resin obtained by dehydration condensation of a rosin and a polyhydric alcohol. Rosin contains compounds with carboxyl groups such as abietic acid, and by dehydration condensation of such compounds with carboxyl groups and polyhydric alcohols with multiple hydroxyl groups, the molecular weight is increased to form rosin esters. Become. In addition, among the compounds contained in the raw material rosin, there are those having a cis-diene structure, such as levopimaric acid. Therefore, prior to the above dehydration condensation reaction, maleic acid modification is performed between rosin and maleic acid by Diels-Alder addition reaction, so that rosin contains compounds rich in carboxyl groups. A rosin ester having a higher molecular weight can be obtained by performing a dehydration condensation reaction with a polyhydric alcohol using such a modified rosin. Furthermore, by coexisting a fatty acid when performing the dehydration condensation reaction, it is possible to variously change the properties of the obtained rosin ester. These rosin esters are preferable because they have a high proportion of natural components (biomass) such as rosin in the resin, and also lead to an ink composition that can realize printing with low environmental load.

As the polyhydric alcohol used for preparing the rosin ester, glycerin, pentaerythritol and the like are preferably exemplified, but other polyhydric alcohols may be used.

Since various rosin esters obtained by the chemical reaction as described above are commercially available, such commercial products may be purchased and used for the preparation of the ink composition. Such commercial products are available from Harima Kasei Co., Ltd., Arakawa Chemical Industries, Ltd., LAWTER, and the like.

Next, the method for measuring the n-hexane tolerance of the resin in the present invention will be explained. First, 80 g of a resin to be measured is prepared and dissolved in 120 g of soybean oil heated to 200° C. by stirring for 30 minutes to prepare a dissolved varnish. After allowing the obtained dissolved varnish to cool to room temperature, 5 g was collected in a beaker, and while the liquid temperature in the beaker was maintained at 25° C., n-hexane was gradually stirred into the dissolved varnish in the beaker. The mass (g) of n-hexane required until the liquid in the beaker starts to become cloudy is determined. The obtained mass (g) of n-hexane is the n-hexane tolerance (g/5g). As already mentioned, a resin having an n-hexane tolerance of 2 to 7 g/5 g determined by the above procedure is used as the binder resin in the present invention. This n-hexane tolerance is more preferably 2 to 5 g/5 g, even more preferably 2 to 3 g/5 g.

The binder resin is dissolved or dispersed by being heated together with a vegetable oil or the like, which will be described later, and used in the form of a varnish. When preparing the varnish, a gelling agent such as a metal chelate compound or metal soap may be added to the dissolved varnish obtained by dissolving the resin to obtain a gelled varnish. By preparing such a gelling varnish and using it in preparation of an ink composition, it is possible to impart appropriate viscoelasticity to the ink composition, which is preferable.

[Vegetable oils]
Vegetable oils include vegetable oils themselves and fatty acid alkyl esters of vegetable oils. The ink composition of the present invention contains vegetable oils, and as at least part of the vegetable oils, fatty acid alkyl esters of vegetable oils are contained in an amount of 10 to 30% by mass based on the total ink composition.

Examples of vegetable oils include drying and semi-drying oils such as soybean oil, cottonseed oil, linseed oil, safflower oil, tung oil, tall oil, dehydrated castor oil, and canola oil. Examples of fatty acid alkyl esters of vegetable oils include monoalkyl esters of fatty acids derived from the above vegetable oils. Preferred examples of the fatty acid constituting the fatty acid monoalkyl ester include unsaturated fatty acids having 16 to 20 carbon atoms, and examples of such unsaturated fatty acids include oleic acid, linoleic acid, linolenic acid, and eleostearic acid. It is preferably exemplified. As the alkyl group constituting the fatty acid monoalkyl ester compound, alkyl groups having 1 to 10 carbon atoms are preferably exemplified, more specifically, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, Preferred examples include tert-butyl group, 2-ethylhexyl group and the like. The unsaturated bond portion contained in the vegetable oils is oxidatively polymerized in the ink composition after printing, thereby drying the ink composition.

As the fatty acid alkyl ester of the vegetable oil, soybean oil fatty acid butyl ester, linseed oil fatty acid butyl ester, and the like are preferably mentioned. As described above, the content of the fatty acid alkyl ester of vegetable oil in the ink composition is 10 to 30% by mass. This content is more preferably 10 to 20% by mass, more preferably 15 to 20% by mass.

Moreover, the vegetable oil is preferably contained in the ink composition from the viewpoint of improving the drying properties of the ink composition. Preferable examples of the vegetable oil in this case include soybean oil, linseed oil, and tung oil. The content of the vegetable oil in the ink composition is preferably about 15 to 40% by mass, more preferably about 20 to 40% by mass, and even more preferably about 20 to 35% by mass.

[Alkyd resin]
The ink composition of the present invention preferably contains an alkyd resin. Alkyd resins are resins prepared by dehydration condensation of fatty acids and polyhydric alcohols, and if necessary, are prepared by adding polybasic acids such as phthalic anhydride and maleic anhydride in addition to fatty acids. Alkyd resins are often prepared by heating a vegetable oil and a polyhydric alcohol in the presence of a catalyst to simultaneously effect transesterification and dehydration condensation. In the alkyd resin, the ratio (%) of the mass of the fatty acid moiety to the mass of the whole alkyd resin is called oil length. In the present invention, an alkyd resin with an oil length of 50-90% is preferably used, and an alkyd resin with an oil length of 60-80% is more preferably used. Moreover, in the present invention, an alkyd resin containing a vegetable oil-derived fatty acid, that is, a vegetable oil-modified alkyd resin is preferably used. Such alkyd resins are commercially available.

The content of the alkyd resin in the ink composition of the present invention is preferably about 2 to 10% by mass with respect to the entire ink composition.

Alkyd resins are preferably used together with binder resins and vegetable oils when preparing varnishes. As a result, the dissolution of the binder resin having low solubility can be further promoted. In addition, the alkyd resin improves pigment dispersibility, and is therefore preferably used in this respect as well.

[Hairdryer]
The ink composition of the present invention preferably contains a drier. As already mentioned, the drier has the function of assisting the oxidative polymerization of the components in the ink composition after printing and accelerating the drying of the ink composition. In general, a drier made of transition metal metal soap and containing cobalt as a transition metal is said to have the highest drying effect. On the other hand, as already explained, concerns about cobalt's toxicity and increased environmental load remain.

In this respect, as already described, the ink composition of the present invention has improved setting property by using the above binder resin, and can realize sufficient drying property without using a dryer containing cobalt. Therefore, the ink composition of the present invention preferably does not contain cobalt metal soap.

As the drier in the ink composition of the present invention, a manganese metal soap is preferably used. The content of the drier in the ink composition is preferably about 1 to 5% by mass, more preferably about 1 to 3% by mass.

[mineral oil]
Mineral oil may be added to the ink composition of the present invention in addition to the above vegetable oils. Mineral oils include light mineral oils, which are also called solvents, and heavy mineral oils, which are in the form of lubricating oils.

Examples of light mineral oils include non-aromatic petroleum solvents having a boiling point of 160° C. or higher, preferably 200° C. or higher. Examples of such non-aromatic petroleum solvents include Solvent No. 0, AF Solvent No. 5, AF Solvent No. 6 and AF Solvent No. 7 manufactured by JX Nippon Oil & Energy Corporation.

Heavy mineral oils include various lubricating oils that have been classified as spindle oils, machine oils, dynamo oils, cylinder oils, and the like. Among these, from the viewpoint of adapting to OSHA standards in the United States and EU standards, it is preferable that the content of the condensed polycyclic aromatic component is suppressed. Such mineral oils include Ink Oil H8 and Ink Oil H35 (both trade names) manufactured by JX Nippon Oil & Energy Corporation, and SNH8, SNH46, SNH220 and SNH540 manufactured by Sankyo Yuka Kogyo Co., Ltd. (both are trade names) and the like are exemplified.

These mineral oils can be used individually or in combination of 2 or more types. The content of mineral oil in the ink composition can be exemplified from about 0 to 50% by mass with respect to the entire ink composition.

[Other ingredients]
Various components other than the components described above can be added to the ink composition of the present invention as necessary from the viewpoint of improving storage stability and printing performance. Examples of such various components include antioxidants, salts such as phosphate, waxes such as polyethylene wax, olefin wax, and Fischer-Tropsch wax, and alcohols.

Preferable examples of the antioxidant include phenol compounds such as butylhydroxytoluene, tocopherol acetate, and the like, and among them, butylhydroxytoluene is more preferable. By adding such an antioxidant to the ink composition, the oxidation of the components contained in the ink composition is suppressed, and the storage stability is improved. The content of the antioxidant in the ink composition can be exemplified from about 0.1 to 2% by mass.

<Method for producing ink composition for offset printing>
Next, one embodiment of the method for producing the ink composition for offset printing will be described. A method for producing an ink composition for offset printing, which will be described below, is also one aspect of the present invention.

In the method for producing the ink composition for offset printing of the present invention, 80 g of the oil component containing vegetable oils, not the resole derivative, is dissolved in 120 g of soybean oil heated to 200 ° C. by stirring for 30 minutes. By doing so, it comprises a step of dissolving a binder resin that gives a dissolved varnish having an n-hexane tolerance of 2 to 7 g / 5 g, a varnish preparation step of preparing a varnish, a pigment is added to the varnish and mixed, and this and a kneading step in which the pigment contained in the mixture is made into fine particles by dispersing means, and a fatty acid alkyl ester of vegetable oil is included as at least a part of the vegetable oil. That is, in the description of the above ink composition, it was described that the varnish is prepared by heating and dissolving a binder resin exhibiting a predetermined solubility and vegetable oils, particularly fatty acid alkyl esters of vegetable oils. The manufacturing method of the invention is specified to include such steps. In addition, in the following description, the description of the content overlapping with the ink composition already described will be omitted as appropriate.

The production method of the present invention comprises a varnish preparation step comprising a step of dissolving the already explained binder resin in the already explained oil component containing the vegetable oils. At this time, it is necessary to contain a fatty acid alkyl ester of vegetable oil as the vegetable oil.

Vegetable oil components contained in the oil component include vegetable oils and fatty acid alkyl esters of vegetable oils. Vegetable oils and fatty acid alkyl esters of vegetable oils are as described above. Moreover, at this time, it is preferable to add the already explained alkyd resin. In this case, in the varnish preparation process, about 15 to 40 parts by mass of vegetable oil, about 15 to 30 parts by mass of fatty acid alkyl ester of vegetable oil, and about 3 to 5% by mass of alkyd resin are added to 40 parts by mass of binder resin. The binder resin is dissolved while stirring at 100 to 150° C. for 30 to 90 minutes to prepare a dissolved varnish.

The obtained dissolved varnish may be used as it is for the preparation of an ink composition, or a gelling varnish may be obtained by adding a gelling agent such as a metal chelate compound or a metal soap and reacting it under heating. In the case of gelling varnish, aluminum ethyl acetoacetate diisopropylate (ALCH) is preferably used as a gelling agent, and the amount added is about 0.3 to 1% by mass with respect to 100 parts by mass of the dissolved varnish. preferably. A gelling varnish is prepared by adding the gelling agent to the melted varnish and reacting at 100-150° C. for 30-90 minutes. The varnish prepared in the varnish preparing process is subjected to a kneading process.

In the kneading step, a pigment is added to and mixed with the varnish, and the pigment contained in this mixture is made into fine particles by a dispersing means. That is, the already explained pigment is added to the varnish, and the pigment is dispersed by kneading with a bead mill, a three-roll mill, or the like. Thereafter, a drier and various components (antioxidants, alcohols, waxes, etc.) are added as necessary, and an oil component such as vegetable oil is added to adjust the viscosity to prepare an ink composition. The viscosity of the ink composition is exemplified by a value of 10 to 50 Pa·s at 25° C. measured by a Laret viscometer, but is not particularly limited.

<Manufacturing method of printed matter>
Next, an embodiment of the method for manufacturing printed matter will be described. A method for producing a printed matter to be described below is also one aspect of the present invention.

The method for producing a printed matter of the present invention is characterized by including the step of printing using the ink composition for offset printing of the present invention. As already mentioned, the ink composition of the present invention has a high proportion of naturally derived components and does not contain a rosin-modified phenolic resin made from alkylphenol, which has a large environmental load, or a cobalt dryer, which also has a large environmental load. It is characterized by having a smaller environmental impact than conventional products. By using such an ink composition, it is possible to realize printing with less environmental load, and the printed matter thus obtained also has less environmental load.

In addition, printed materials printed with ink compositions that do not contain rosin-modified phenolic resins made from alkylphenols or cobalt dryers, which are of concern for toxicity, are in strong demand, especially in the packaging field where safety is a priority. be. Therefore, printed matter produced using the ink composition of the present invention is extremely useful for packaging.

EXAMPLES Hereinafter, the present invention will be described more specifically by showing examples, but the present invention is not limited to the following examples. In addition, in the following description, "part" shall mean a mass part and "%" shall mean mass %.

[Preparation of varnish 1]
In a four-necked flask equipped with a condenser, a thermometer and a stirrer, 41.4 parts of rosin ester (Harrier 619CI, manufactured by Harima Kasei Co., Ltd.), vegetable oil-modified alkyd resin (manufactured by Toshin Yushi Co., Ltd., TOKYD-81S -NV) 4.4 parts, 18.2 parts of butyl ester of soybean oil fatty acid, and 35.4 parts of soybean oil were charged, then the temperature was raised to 130°C, and the temperature was maintained for 50 minutes to dissolve the resin. After that, 0.6 part of aluminum ethyl acetoacetate diisopropylate (manufactured by Kawaken Fine Chemicals Co., Ltd., ALCH) was added, and then heated at 130° C. for 60 minutes to obtain varnish 1. The n-hexane tolerance value of the rosin ester used in the preparation of Varnish 1 was 2.49 (g/5g).

[Preparation of varnish 2]
41.8 parts of the same rosin ester used in the preparation of Varnish 1, the same vegetable oil-modified alkyd resin used in the preparation of Varnish 1 were added to a four-necked flask equipped with a condenser, thermometer and stirrer. 4 parts, 21.1 parts of butyl ester of soybean oil fatty acid, and 32.0 parts of soybean oil were charged, the temperature was raised to 130° C., and the temperature was maintained for 50 minutes to dissolve the resin. 0.6 parts of acetate diisopropylate (manufactured by Kawaken Fine Chemicals Co., Ltd., ALCH) was charged, and then heated at 130° C. for 60 minutes to obtain varnish 2 .

[Preparation of varnish 3]
42.3 parts of the same rosin ester used in the preparation of Varnish 1, the same vegetable oil-modified alkyd resin used in the preparation of Varnish 7. 7 parts of soybean oil fatty acid butyl ester, 19.9 parts of soybean oil fatty acid and 29.4 parts of soybean oil were charged, the temperature was raised to 130° C., and the temperature was maintained for 50 minutes to dissolve the resin. 0.7 part of acetate diisopropylate (manufactured by Kawaken Fine Chemicals Co., Ltd., ALCH) was charged, and then heated at 130° C. for 60 minutes to obtain Varnish 3.

[Preparation of varnish 4]
A four-necked flask equipped with a condenser, a thermometer and a stirrer was charged with 41.4 parts of the same rosin ester and 58.0 parts of soybean oil used in the preparation of varnish 1, and then heated to 130°C. After dissolving the resin by maintaining the same temperature for 50 minutes, 0.6 part of aluminum ethyl acetoacetate diisopropylate (manufactured by Kawaken Fine Chemicals Co., Ltd., ALCH) was charged, and then heated at 130 ° C. for 60 minutes. and varnish 4 was obtained.

[Preparation of varnish 5]
41.4 parts of the same rosin ester and 58.0 parts of soybean oil fatty acid butyl ester used in the preparation of varnish 1 were charged into a four-necked flask equipped with a condenser, thermometer and stirrer, and then heated to 130°C. and maintained at the same temperature for 50 minutes to dissolve the resin, then 0.6 part of aluminum ethyl acetoacetate diisopropylate (manufactured by Kawaken Fine Chemicals Co., Ltd., ALCH) was charged, and then heated to 130°C to 60°C. A varnish 5 was obtained by heating and holding for a minute.

[Preparation of varnish 6]
35.8 parts of rosin ester (LAWTER, ECO-REZ-9715A), vegetable oil-modified alkyd resin (manufactured by Toshin Yushi Co., Ltd., TOKYD-81S- NV) 3.8 parts, 15.8 parts of butyl ester of soybean oil fatty acid and 44.1 parts of soybean oil were charged, then the temperature was raised to 130°C and the temperature was maintained for 50 minutes to dissolve the resin. , aluminum ethyl acetoacetate diisopropylate (manufactured by Kawaken Fine Chemicals Co., Ltd., ALCH) was charged, and then heated at 130° C. for 60 minutes to obtain varnish 6 . The n-hexane tolerance value of the rosin ester used in the preparation of Varnish 6 was 0.0 (g/5g). That is, 80 g of this rosin ester did not dissolve in 120 g of soybean oil at 200°C.

[Preparation of varnish 7]
A four-necked flask equipped with a condenser, a thermometer and a stirrer was charged with 53.0 parts of rosin ester (LAWTER, ECO-REZ-350C), vegetable oil-modified alkyd resin (manufactured by Toshin Yushi Co., Ltd., TOKYD-81S- NV) 4.3 parts, 16.2 parts of butyl ester of soybean oil fatty acid and 25.9 parts of soybean oil were charged, then the temperature was raised to 130°C and the temperature was maintained for 50 minutes to dissolve the resin. After that, 0.6 part of aluminum ethyl acetoacetate diisopropylate (manufactured by Kawaken Fine Chemicals Co., Ltd., ALCH) was charged, and then heated at 130° C. for 60 minutes to obtain varnish 7 . The n-hexane tolerance value of the rosin ester used in the preparation of Varnish 7 was 11.5 (g/5g).

[Preparation of varnish 8]
38.0 parts of the same rosin ester used in the preparation of Varnish 1, the same vegetable oil-modified alkyd resin used in the preparation of Varnish 1 were added to a four-necked flask equipped with a condenser, thermometer and stirrer. After charging 0 part, 10.9 parts of butyl ester of soybean oil fatty acid and 46.5 parts of soybean oil, the temperature was raised to 130° C., and the temperature was maintained for 50 minutes to dissolve the resin. 0.6 part of acetate diisopropylate (manufactured by Kawaken Fine Chemicals Co., Ltd., ALCH) was charged and then heated at 130° C. for 60 minutes to obtain varnish 8 .

[Preparation of varnish 9]
In a four-necked flask equipped with a condenser, a thermometer and a stirrer, 38.5 parts of rosin-modified phenol resin (manufactured by Arakawa Chemical Co., Ltd., Tamanol 414), vegetable oil-modified alkyd resin (manufactured by Toshin Oil Co., Ltd., TOKYD- 81S-NV), 17.0 parts of butyl ester of soybean oil fatty acid, and 39.9 parts of soybean oil were charged, the temperature was raised to 130°C, and the temperature was maintained for 50 minutes to dissolve the resin. After that, 0.6 part of aluminum ethyl acetoacetate diisopropylate (manufactured by Kawaken Fine Chemicals Co., Ltd., ALCH) was charged, and then heated at 130° C. for 60 minutes to obtain varnish 9. The n-hexane tolerance value of the rosin-modified phenolic resin used in the preparation of Varnish 9 was 3.1 (g/5g).

[Preparation of ink composition]
Ink compositions of Examples 1 to 5, Comparative Examples 1 to 4, and Reference Examples 1 to 2 were prepared by mixing various materials according to the formulations shown in Table 1 and kneading them using a triple roll. bottom. The blending amount of each component shown in Table 1 is parts by mass. In addition, in the columns below the "Total" column, the content of the vegetable oil fatty acid alkyl ester in the ink composition (%; expressed as "ester (%)"), and the content of the vegetable oil-modified alkyd resin in the ink composition The content (%; expressed as "alkyd (%)") is described. In Table 1, "indigo pigment" is a phthalocyanine pigment PB15:3, "yellow pigment" is a disazo yellow pigment PY12, and "alkyd resin" is a vegetable oil-modified alkyd resin (manufactured by Toshin Yushi Co., Ltd., TOKYD-81S-NV ) 4.1 parts, 17.0 parts of butyl ester of soybean oil fatty acid and 39.9 parts of soybean oil), "wax" is polyethylene wax, and "Co dryer" is a cobalt-based metal dryer. "Mn dryer" is a manganese-based metal dryer, and "fatty acid ester" is soybean oil fatty acid butyl ester.

[Evaluation of liquidity]
The fluidity of the ink compositions of Examples, Comparative Examples, and Reference Examples was evaluated using a vertical glass plate flowmeter at 25°C. was measured. The larger the distance, the better the fluidity and the better the dispersibility of the pigment. The evaluation criteria are as follows, and the results are shown in the fluidity column of Table 2. Reference Example 1 was used as a standard for indigo ink, and Reference Example 2 was used as a standard for yellow ink (the same applies hereinafter).
○: equivalent to the standard reference example (reference example 1 or 2) △: inferior to the standard reference example (reference example 1 or 2), but within the practical range ×: standard reference example (reference example Significantly inferior to 1 or 2) and out of the practical range

[Evaluation of dryness on paper]
For each of the ink compositions of Examples, Comparative Examples, and Reference Examples, 0.1 cc of the ink composition was applied to coated paper (Nippon Paper Industries Co., Ltd. manufactured by Aurora Coat). After that, under an environment of room temperature of 25°C and humidity of 50%, the specimen covered with a backing paper is set in a paper surface drying tester (manufactured by Toyo Seiki Co., Ltd.) to judge the drying state of the coating film by oxidative polymerization. The state of ink adhesion to the cover paper was visually confirmed. The time required for the ink to stop adhering to the cover sheet was taken as the paper surface drying time. The evaluation criteria are as follows, and the results are shown in the paper surface drying property column of Table 2.
○: equivalent to the standard reference example (reference example 1 or 2) △: inferior to the standard reference example (reference example 1 or 2), but within the practical range ×: standard reference example (reference example Significantly inferior to 1 or 2) and out of the practical range

[Evaluation of set time]
For each of the ink compositions of Examples, Comparative Examples, and Reference Examples, 0.1 cc of the ink composition was applied to coated paper (Nippon Paper Industries Co., Ltd.) using an RI color development machine (four-split roll, manufactured by Akira Seisakusho Co., Ltd.). The color was exhibited on the company's Aurora Coat). After that, under an environment of room temperature 25° C. and humidity 50%, the color development surface of each color exhibit immediately after color development is covered with a piece of paper and set in a setting tester (AUTO INKSETTING TESTER, manufactured by Toyo Seiki Co., Ltd.), A set test was performed at intervals of 3 minutes, and the state of ink adhesion to the cover paper was visually confirmed. The time required for the ink to stop adhering to the cover sheet was defined as the set time. The evaluation criteria are as follows, and the results are shown in Table 2.
○: equivalent to the standard reference example (reference example 1 or 2) △: inferior to the standard reference example (reference example 1 or 2), but within the practical range ×: standard reference example (reference example Significantly inferior to 1 or 2) and out of the practical range

[Evaluation of Gloss]
For each of the ink compositions of Examples, Comparative Examples, and Reference Examples, 0.1 cc of the ink composition was applied to coated paper (Nippon Paper Industries Co., Ltd. manufactured by Aurora Coat). Then, it was stored under an environment of room temperature of 25° C. and humidity of 50%, and after 24 hours, the 60° reflection gloss value of the developed surface was determined using a gloss meter (manufactured by Nippon Denshoku Industries Co., Ltd.). The evaluation criteria are as follows, and the results are shown in the gloss column of Table 2.
○: equivalent to the standard reference example (reference example 1 or 2) △: inferior to the standard reference example (reference example 1 or 2), but within the practical range ×: standard reference example (reference example Significantly inferior to 1 or 2) and out of the practical range

According to Table 2, although the ink composition of the present invention does not contain a rosin-modified phenolic resin (resole derivative), it is equivalent to a conventional ink composition containing a rosin-modified phenolic resin (Reference Example 1). It can be seen that printability is achieved. From this, it can be understood that the ink composition of the present invention provides sufficient printability while using materials with low environmental load.

Claims (7)

An offset printing ink composition comprising a pigment, a binder resin, and vegetable oils,
The binder resin is a rosin ester, and the rosin ester is dissolved by stirring 80 g of the rosin ester in 120 g of soybean oil heated to 200° C. for 30 minutes. It satisfies the condition of giving a dissolved varnish with a hexane tolerance of 2 to 3 g/5 g,
An ink composition for offset printing, comprising 10 to 30% by mass of soybean oil fatty acid butyl ester as at least part of the vegetable oils.
Procedure: After allowing the dissolved varnish to cool to room temperature, 5 g was collected in a beaker, and while the liquid temperature in the beaker was maintained at 25°C, n-hexane was added to the dissolved varnish in the beaker little by little while stirring. In addition, determine the mass (g) of n-hexane required until the liquid in the beaker starts to become cloudy. The mass (g) of n-hexane thus obtained is defined as n-hexane tolerance (g/5g). 2. The ink composition for offset printing according to claim 1, further comprising 2 to 10% by mass of an alkyd resin having an oil length of 50 to 90%. 3. The ink composition for offset printing according to claim 1, which does not contain a cobalt metal soap. A varnish preparation step of preparing a varnish, comprising a step of dissolving a rosin ester in an oil component containing vegetable oils;
a kneading step in which a pigment is added to the varnish to form a mixture , and the pigment contained in the mixture is finely divided by a dispersing means;
The rosin ester is dissolved by stirring 80 g of the rosin ester in 120 g of soybean oil heated to 200° C. for 30 minutes, and the n-hexane tolerance measured by the following procedure is 2 to 3 g/5 g. It satisfies the conditions of giving a dissolving varnish,
A method for producing a printing ink composition for offset printing, comprising a butyl ester of soybean oil fatty acid as at least part of the vegetable oils.
Procedure: After allowing the dissolved varnish to cool to room temperature, 5 g was collected in a beaker, and while the liquid temperature in the beaker was maintained at 25°C, n-hexane was added to the dissolved varnish in the beaker little by little while stirring. In addition, determine the mass (g) of n-hexane required until the liquid in the beaker starts to become cloudy. The mass (g) of n-hexane thus obtained is defined as n-hexane tolerance (g/5g). 5. The method for producing a printing ink composition for offset printing according to claim 4, wherein an alkyd resin having an oil length of 50 to 90% is added when preparing the varnish in the varnish preparing step. A method for producing printed matter, comprising a step of printing using the ink composition for offset printing according to any one of claims 1 to 3. 7. The method of manufacturing printed matter according to claim 6, wherein said printed matter is for packaging.