JP7082864B2 - Offset printing ink composition, its manufacturing method, and offset printing ink composition preparation varnish - Google Patents

Description

The present invention relates to an ink composition for offset printing, a method for producing the same, and a varnish for preparing an ink composition for offset printing.

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 offset 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 repels and does not adhere to the non-image portion where 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 printing paper to perform printing.

Further, offset printing has a characteristic that it is suitable for a field where a printed matter having high cosmeticity can be obtained or a large amount of printed matter can be obtained in a short time while the production of a printed 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 paper, 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. The printing speed may reach as high as 100,000 copies or more per hour. Under these circumstances, many products with high-speed printability have been proposed for ink compositions (see, for example, Patent Document 1).

By the way, the ink composition used for offset printing includes a pigment component for imparting coloring power to the ink composition, a resin component for dispersing the pigment component and fixing the pigment component on the surface of paper after printing, and Generally, it contains an oil component for dissolving the resin component and imparting fluidity to the ink composition. As is the case with the ink composition described in Patent Document 1, it is common to use a rosin-modified phenol resin or a rosin-modified maleic acid resin as the above-mentioned resin component. In particular, the rosin-modified phenolic resin has a high affinity for pigments and is excellent in the property of dispersing the rosin-modified phenol resin, and also has excellent properties such as imparting a good emulsification balance at the time of printing to the ink composition. It is frequently used as the main ingredient of.

Japanese Unexamined Patent Publication No. 2000-281954

As described above, rosin-modified phenolic resin and rosin-modified maleic acid resin are components that are used in large quantities in the preparation of ink compositions, but since rosin, which is a natural product, is used as a raw material, it may be received depending on the weather and other conditions. It includes the possibility of tightness. The present invention has been made in view of the above circumstances, and provides an offset printing ink composition capable of maintaining good performance while reducing the use of rosin-modified phenol and rosin-modified maleic acid resin. The purpose is.

As a result of diligent studies to solve the above problems, the present inventors have improved the performance of the ink composition by replacing a part or all of the rosin-modified phenol formaldehyde and the rosin-modified maleic acid resin with petroleum asphalt. It has been found that the amount of rosin-modified phenolic resin and rosin-modified maleic acid resin used can be reduced without damage. The present invention has been completed based on the above findings, and provides the following.

The present invention includes carbon black as a coloring pigment, heavy mineral oil and / or soybean oil as an oil component, and further contains petroleum asphalt in an amount of 2.5% by mass or more based on the entire composition. Characteristically, the petroleum asphalt is an ink composition for offset printing, which is a blown asphalt having an average molecular weight of 5000 to 10000 for all the components thereof.

In the present invention, the content of the rosin-modified phenolic resin and the rosin-modified maleic acid resin in the composition is preferably less than 3% by mass.

It is preferable that the petroleum asphalt is contained in an amount of 5% by mass or more based on the entire composition.

Further, the present invention is characterized in that petroleum asphalt is dissolved or dispersed in an oil component to form a varnish, which is used as a varnish for preparing an ink composition, and the petroleum asphalt has an average molecular weight of 5000 or more for all the components. It is also a method for producing an offset printing ink composition which is 10000 blown asphalt and whose oil component is heavy mineral oil and / or soybean oil.

Further, the present invention comprises dissolving or dispersing petroleum asphalt in an oil component, and the petroleum asphalt is a blown asphalt having an average molecular weight of all the components of 5000 to 10000, and the oil component is a heavy mineral oil and / or a large amount. It is also a varnish for preparing an ink composition for offset printing, which is bean oil.

INDUSTRIAL APPLICABILITY According to the present invention, there is provided an ink composition for offset printing capable of maintaining good performance while reducing the use of rosin-modified phenol and rosin-modified maleic acid resin.

Hereinafter, an embodiment of the offset printing ink composition of the present invention, an embodiment of a method for producing an offset printing ink composition, and an embodiment of a varnish for preparing an offset printing ink composition will be described. The present invention is not limited to the following embodiments and embodiments.

<Ink composition for offset printing>
First, an embodiment of the offset printing ink composition of the present invention will be described. The offset printing ink composition of the present invention is characterized by containing a coloring pigment and an oil component, and further containing petroleum asphalt in an amount of 2.5% by mass or more based on the entire composition. The offset printing ink composition of the present invention is for offset lithographic printing in which printing is performed using a lithographic printing plate having no unevenness, and can be particularly preferably used in offset lithographic printing of a penetration drying method. Further, the offset printing ink composition of the present invention can be used not only for a printing method with water using dampening water but also for printing without water using dampening water.

[Coloring pigment]
The coloring pigment is a component for imparting coloring power to the ink composition. Examples of the coloring pigment include organic and / or inorganic pigments conventionally used in ink compositions. However, the asphalt added to the ink composition of the present invention has a high affinity for carbon black, that is, has a high wettability, and is colored black by itself. Therefore, carbon black is used as the coloring pigment in the present invention. Preferred. In this case, the ink composition is black ink colored black. When pigments of other colors are used as coloring pigments, purified asphalt obtained by extracting an asphalt component or a resin component from petroleum asphalt can be used.

Color pigments other than carbon black include yellow pigments such as disazo yellow (pigment yellow 12, pigment yellow 13, pigment yellow 17, pigment yellow 1) and Hansa yellow, and magenta such as brilliant carmine 6B, lake red C, and watching red. Examples thereof include pigments, cyanidic pigments such as phthalocyanine blue, phthalocyanine green, and alkaline blue.

The amount of the coloring pigment added is exemplified, but is not particularly limited to about 8 to 30% by mass with respect to the entire ink composition, and the degree of coloring power required for the ink composition is taken into consideration. It may be adjusted as appropriate. 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.

[Oil component]
The oil component is used to dissolve or disperse petroleum asphalt, which will be described later, 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 that have been used for preparing ink compositions can be used without particular limitation.

In the present invention, the vegetable oil may contain a fatty acid ester compound derived from the vegetable oil in addition to the vegetable oil. Examples of vegetable oils include drying oils such as soybean oil, cottonseed oil, flaxseed oil, safflower oil, tung oil, tall oil, dehydrated castor oil, and canola oil, and semi-drying oils. Moreover, as a fatty acid ester compound derived from a vegetable oil, a monoalkyl ester compound of the fatty acid derived from the said vegetable oil and the like are exemplified. Saturated or unsaturated fatty acids having 16 to 20 carbon atoms are preferably exemplified as the fatty acids constituting the fatty acid monoalkyl ester compound, and examples of such saturated or unsaturated fatty acids include stearic acid, isostearic acid, and hydroxystearic acid. Oleinic acid, linoleic acid, linolenic acid, eleostearic acid and the like are preferably exemplified. As the alkyl group constituting the fatty acid monoalkyl ester compound, an alkyl group having 1 to 10 carbon atoms is preferably exemplified, and more specifically, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, and the like. A tert-butyl group, a 2-ethylhexyl group and the like are preferably exemplified.

These vegetable oils can be used alone or in combination of two or more. As the vegetable oil, soybean oil, soybean oil fatty acid ester and the like are preferably exemplified. As the content of vegetable oil in the ink composition, about 20 to 60% by mass can be exemplified with respect to the entire ink composition.

In the present invention, examples of the mineral oil include light mineral oil, which is also called a solvent, and heavy mineral oil, which is a lubricating oil.

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 No. 0 solvent, AF solvent No. 5, AF solvent No. 6, and AF solvent No. 7 manufactured by JX Nippon Oil Energy Co., Ltd.

Examples of 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 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 such mineral oils include ink oil H8 and ink oil H35 (all trade names) manufactured by JX Nikko Nisseki Energy Co., Ltd., SNH8, SNH46, SNH220, and SNH540 manufactured by Sankyo Yuka Kogyo Co., Ltd. (Both are product names) and the like are exemplified.

These mineral oils can be used alone or in combination of two or more. As the content of mineral oil in the ink composition, about 0 to 50% by mass can be exemplified with respect to the entire ink composition.

[Petroleum asphalt]
The ink composition of the present invention contains 2.5% by mass or more of petroleum asphalt with respect to the entire composition. Petroleum asphalt is obtained as a residue after rectifying crude oil in the petroleum chemical industry to obtain various petroleum products, and petroleum asphalt is a straight residue obtained by rectifying crude oil. It is classified into asphalt and blown asphalt obtained by air-oxidizing straight asphalt. As the petroleum asphalt in the present invention, either the straight asphalt or the blown asphalt described above can be used, and both can be mixed and used. Petroleum asphalt contains a hydrocarbon having a relatively large molecular weight called bitumen and its compound, and mainly contains an asphalt component that is insoluble in hexane and heptane, a resin component that is soluble in hexane and heptane, and an asphalt oil component. .. As described above, since ordinary petroleum asphalt is colored black, when the present invention is applied to an ink composition other than black, it is desirable to use purified asphalt obtained by extracting an asphalt component or a resin component. Such refined asphalt can also be used as the petroleum asphalt in the present invention.

As described above, petroleum asphalt contains a bitumen component having a relatively large molecular weight such as an asphalt component and a resin component, and according to the studies by the present inventors, the bitumen component contained in petroleum asphalt is particularly used in the preparation of an ink composition. It has been found that it is useful as a resin component and can replace resins such as rosin-modified phenolic resin and rosin-modified maleic acid resin that have been conventionally used. That is, even if a resin such as a rosin-modified phenol resin or a rosin-modified maleic acid resin is replaced with petroleum asphalt, that is, bitumen, all the performances required for an ink composition such as dispersibility of a coloring pigment and suitability for emulsification are satisfied. Can be done. Considering that there is no chemical similarity between bitumen and a resin such as a rosin-modified phenolic resin or a rosin-modified maleic acid resin, such a result can be said to be surprising. The present invention has been completed based on these findings.

Petroleum asphalt may be used as it is for preparing an ink composition, or may be used for preparing an ink composition in a state of being dissolved or dispersed in the above oil component to form a varnish. Among the above, heavy mineral oil and vegetable oil are preferably mentioned as the oil component used for dissolving or dispersing petroleum asphalt, and soybean oil is particularly preferable as the vegetable oil. When using a varnish prepared using mineral oil, the increase in tack when the ink composition becomes a thin film tends to be slightly large, while the varnish prepared using soybean oil is used. If so, the tack when the ink composition becomes a thin film tends to be the same as that of the conventional ink composition, which is preferable. The characteristics of the ink composition may be adjusted by combining these heavy mineral oils and soybean oil.

The content of petroleum asphalt with respect to the entire ink composition needs to be 2.5% by mass or more, preferably 5% by mass or more, and more preferably 10% by mass or more. When the content of petroleum asphalt in the entire ink composition is 2.5% by mass or more, the dispersibility of the coloring pigment and the printability are improved, which is preferable. There is no particular upper limit to the content of petroleum asphalt in the entire ink composition, and it may be appropriately determined in consideration of the required viscosity of the ink composition and the like, but the upper limit is generally about 50% by mass.

As described above, in the present invention, petroleum asphalt is used in place of the rosin-modified phenol resin and the rosin-modified maleic acid resin, which are resin components, and therefore the rosin-modified phenol resin and the rosin-modified maleic acid resin are contained in the ink composition. The amount can be significantly reduced. Therefore, the content of the rosin-modified phenolic resin and the rosin-modified maleic acid resin in the composition of the ink composition of the present invention can be less than 3% by mass. More preferably, the content of the rosin-modified phenolic resin and the rosin-modified maleic acid resin in the ink composition can be 0% by mass.

Petroleum asphalt, both blown asphalt and straight asphalt, contains a resin component, an asphalt component, and an asphalt oil component with almost no volatility. The average molecular weight of petroleum asphalt containing each of these components varies depending on the production process of petroleum asphalt, the production area of crude oil as a raw material, etc., but in the present invention, it is contained in this average molecular weight, that is, petroleum asphalt. It is preferable to use one having an average molecular weight of all components in a specific range. Specifically, when the petroleum asphalt is blown asphalt, the average molecular weight of all the components is preferably about 3000 to 10000, and more preferably about 5000 to 9000. When the petroleum asphalt is straight asphalt, the average molecular weight of all the components is preferably about 500 to 1000. The average molecular weight of all the components referred to here is literally the average molecular weight of all the components contained in the petroleum asphalt, and is the average molecular weight calculated when the petroleum asphalt itself is analyzed by an apparatus such as GPC. When the average molecular weight of all the components contained in petroleum asphalt is in the above range, it is preferable because it exhibits good solubility in oil components and can impart appropriate viscoelasticity to the ink composition.

When a rosin-modified phenol resin or a rosin-modified maleic acid resin is used for the purpose of imparting viscous elasticity or aptitude, these resins are dissolved or dispersed by being heated together with the above oil components to form a varnish. Used in the state. When preparing the varnish, a metal alkoxy compound having a valence of 2 or more may be added as a gelling agent into the dissolved varnish obtained by dissolving the resin to obtain a gelled varnish. By preparing the gelled varnish in this way and using it in the preparation of the ink composition, it is possible to impart appropriate viscoelasticity to the ink composition, which is preferable.

[Other ingredients]
From the viewpoint of improving printing performance and the like, various components can be added to the ink composition of the present invention in addition to the above-mentioned components, if necessary. Such various components include resins such as alkyd resin and petroleum resin excluding rosin-modified phenol resin and rosin-modified maleic acid resin, salts such as gilsonite, colorless pigment, and phosphate, polyethylene wax and olefin wax. -Waxes such as Fisher Tropsch wax, alcohols, antioxidants, etc. are exemplified.

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

The ink composition of the present invention is adjusted by a Raleigh viscometer so that the viscosity at 25 ° C. (hereinafter, simply referred to as “viscosity”) is 5 to 30 Pa · s. In order to adjust the viscosity of the ink composition, the above oil components may be appropriately added and mixed.

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

The method for producing an ink composition for offset printing of the present invention is characterized in that petroleum asphalt is dissolved or dispersed in an oil component to form a varnish, which is used as a varnish for preparing an ink composition. That is, as described above with respect to the invention of the ink composition for offset printing, in one embodiment of the present invention, an ink composition prepared by dissolving or dispersing petroleum asphalt in an oil component is used as a varnish. The manufacturing method of is specified to include such a step. In the following description, the description of the content overlapping with the ink composition already described will be omitted as appropriate.

In the production method of the present invention, petroleum asphalt may be used as it is for preparing an ink composition, or may be used for preparing an ink composition in a state of being dissolved or dispersed in the above oil component to form a varnish. May be good. As the oil component at this time, it can be appropriately selected and used from those already described, and among these, heavy mineral oil and vegetable oil are preferably mentioned, and soybean oil is particularly preferable as the vegetable oil. When using a varnish prepared using mineral oil, the increase in tack when the ink composition becomes a thin film tends to be slightly large, while the varnish prepared using soybean oil is used. If so, the tack when the ink composition becomes a thin film tends to be the same as that of the conventional ink composition, which is preferable. The characteristics of the ink composition may be adjusted by combining these heavy mineral oils and soybean oil.

When dissolving or dispersing petroleum asphalt in the oil component, the petroleum asphalt and the oil component may be put into a melting pot equipped with a heating device and a stirring device and heated while stirring. The ratio of the petroleum asphalt to the oil component at this time may be appropriately determined in consideration of the handling property as a varnish, the viscous elasticity required for the ink composition, etc., but the petroleum asphalt: mass ratio of the oil component is 2. : 8 to 8: 2 is exemplified, 3: 7 to 7: 3 is more preferably exemplified, and 3: 7 to 5: 5 is further preferred. Further, the heating temperature at this time can be exemplified by about 100 to 200 ° C. A varnish is prepared by continuing stirring and heating in the mixture until the solids disappear, and then cooling. If insoluble matter such as residue is present, it is preferable to remove it with an appropriate filtration device.

The varnish thus prepared is used for the preparation of the ink composition. When preparing the ink composition, the coloring pigment, the above varnish and the oil component may be mixed and then kneaded using a kneading device such as a three-roll mill or a bead mill. When petroleum asphalt is used as it is for preparing an ink composition without using varnish, the coloring pigment, petroleum asphalt and oil components may be mixed and then kneaded using a kneading device such as a three-roll mill or a bead mill. good. Then, the above oil component and various components are added and mixed to adjust the viscosity, whereby an ink composition can be obtained. As described above, an example of the viscosity of the ink composition is 5 to 30 Pa · s.

<Varnish for preparing ink composition for offset printing>
The above varnish obtained by dissolving or dispersing petroleum asphalt in an oil component, that is, a varnish for preparing an ink composition for offset printing is also one of the present inventions. One embodiment of the present invention has already been described, and the description thereof will be omitted here. As described above, the oil component for preparing this varnish is selected from the above oil components, and among these, heavy mineral oil and vegetable oil are preferably mentioned, and soybean oil is particularly preferable as the vegetable oil. Can be mentioned. The characteristics of the ink composition may be adjusted by combining these heavy mineral oils and soybean oil.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the following description, unless otherwise specified, "%" means "% by mass" and "part" means parts by mass.

[Preparation of varnish 1 for ink composition preparation]
Bloan asphalt A (average molecular weight of asphalt component and resin component 8350, oil component 37.2%, resin component 15.1%, asphalt component) in a four-necked flask equipped with a cooling tube, thermometer, agitator and heating device. 47.7%) After charging 50 parts and 50 parts of soybean oil, the temperature was raised to 140 ° C., and the same temperature was maintained for 1 hour with stirring to dissolve the blown asphalt A, and the varnish for preparing an ink composition 1 (Hereinafter referred to as varnish 1) was obtained.

[Preparation of varnish 2 for ink composition preparation]
30 parts of blown asphalt A and 70 parts of heavy mineral oil (SNH540 manufactured by Sankyo Yuka Kogyo Co., Ltd.) were placed in a four-necked flask equipped with a cooling tube, a thermometer, a stirrer and a heating device, and then heated to 140 ° C. The blown asphalt A was dissolved by raising the temperature and maintaining the same temperature for 1 hour with stirring to obtain a varnish 2 for preparing an ink composition (hereinafter referred to as varnish 2).

[Preparation of varnish 3 for ink composition preparation]
40 parts of blown asphalt A, 20 parts of soybean oil, and 40 parts of heavy mineral oil (SNH540 manufactured by Sankyo Yuka Kogyo Co., Ltd.) are charged in a four-necked flask equipped with a cooling tube, a thermometer, a stirrer and a heating device. After that, the temperature was raised to 140 ° C., and the same temperature was maintained for 1 hour with stirring to dissolve the blown asphalt A, thereby obtaining a varnish 3 for preparing an ink composition (hereinafter referred to as varnish 3).

[Preparation of varnish 4 for ink composition preparation]
The above varnish 2 except that blown asphalt B (average molecular weight of asphalt component and resin component 16524, oil component 41.2%, resin component 15.6%, asphalt component 43.2%) was used instead of blown asphalt A. In the same procedure as above, a varnish 4 for preparing an ink composition (hereinafter referred to as varnish 4) was obtained. The varnish 4 tended to have a higher elasticity than the varnishes 1 to 3 using the blown asphalt A.

[Preparation of varnish 5 for ink composition preparation]
28.6 parts of varnish-modified phenolic resin (manufactured by Arakawa Chemical Industry Co., Ltd.) with a mass average molecular weight of 100,000 and 28.4 parts of soybean oil in a four-necked flask equipped with a cooling tube, thermometer, agitator and heating device. After charging, the temperature was raised to 200 ° C., and the resin was dissolved by maintaining the same temperature for 30 minutes with stirring, and then 43 parts of soybean oil and ethylacetate acetate aluminum diisopropyrate (manufactured by Kawaken Fine Chemical Co., Ltd.). , ALCH) was charged in 0.8 parts, and then the mixture was stirred while heating at 175 ° C. for 50 minutes to obtain a varnish 5 for preparing an ink composition (hereinafter referred to as varnish 5).

[Preparation of varnish 6 for ink composition preparation]
After charging 22 parts of varnish-modified phenolic resin (manufactured by Arakawa Chemical Industry Co., Ltd.) and 22 parts of soybean oil with a mass average molecular weight of 100,000 into a four-necked flask equipped with a cooling tube, a thermometer, a stirrer and a heating device. After the resin was dissolved by raising the temperature to 200 ° C. and maintaining the same temperature for 30 minutes with stirring, 56 parts of soybean oil and ethylacetacetate aluminum diisopropyrate (manufactured by Kawaken Fine Chemical Co., Ltd., ALCH) were added. 0.8 parts were charged, and then the mixture was stirred while heating at 175 ° C. for 50 minutes to obtain a varnish 6 for preparing an ink composition (hereinafter referred to as varnish 6).

[Preparation of Ink Composition 1]
The ink compositions of Examples 1 to 8 and Reference Example 1 were prepared by mixing various materials according to the formulations shown in Table 1 and kneading the meat with three rolls. Reference Example 1 is an ink composition containing a rosin-modified phenol resin as in the conventional ink composition. The blending amount shown in Table 1 is by mass. In Table 1, "carbon black" is carbon black # 32 manufactured by Mitsubishi Chemical Corporation, "kaolinite" is a commercially available powdered kaolinite, and "guilsonite varnish" is guilsonite (American Gilsonite Company). 20 parts of AF Solvent No. 6 (manufactured by JX Nikko Nisseki Energy Co., Ltd.) melted in 80 parts of product name: Gilsonite S325L. Yes, "heavy mineral oil" is SNH540 manufactured by Sankyo Yuka Kogyo Co., Ltd. Further, in each of the examples and reference examples in Table 1, the total number of copies blended is different because there is a difference in the amount of oil component added in order to make the viscosities of the ink compositions uniform, and this difference is about the same. Does not affect the evaluation.

[Preparation of ink composition 2]
The ink compositions of Examples 6 to 8 and Reference Example 2 were prepared by mixing various materials according to the formulations shown in Table 2 and kneading the meat with a bead mill. Reference Example 2 is an ink composition containing a rosin-modified phenol resin as in the conventional ink composition. The blending amount shown in Table 2 is a part by mass. In Table 2, "carbon black" is carbon black # 32 manufactured by Mitsubishi Chemical Corporation, "kaolinite" is a commercially available powdered kaolinite, and "guilsonite varnish" is guilsonite (American Gilsonite Company). 20 parts of AF Solvent No. 6 (manufactured by JX Nikko Nisseki Energy Co., Ltd.) melted in 80 parts of product name: Gilsonite S325L, and "varnish 5-6" is the above varnish 5-6. Yes, "heavy mineral oil" is SNH540 manufactured by Sankyo Yuka Kogyo Co., Ltd. The average molecular weight of straight asphalt A as a whole is 644, the oil component is 48.1%, the resin component is 49.9%, and the asphalt component is 2.0%. Further, in each of the examples and reference examples in Table 2, the total number of parts blended is different because there is a difference in the amount of oil component added in order to make the viscosities of the ink compositions uniform, and this difference is about the same. Does not affect the evaluation.

[Liquidity evaluation]
Fluidity, which is one of the physical characteristics of the ink composition, is one of the indexes showing the degree of pigment dispersion and viscoelasticity. If it is too large, it leads to factors that increase flying and misching, and if it is too small, it leads to an increase. This leads to factors that cause problems such as supply failure and pot rising in the pipe pumping of the ink composition. Therefore, the fluidity of each of the ink compositions of the examples and the reference examples was evaluated. For the evaluation of the fluidity of the ink compositions of each example and the reference example, the distance (mm) in which 0.5 cc of the printing ink composition flowed in 10 minutes by gravity at 25 ° C. using a vertical glass plate flow meter. Was performed by measuring. The results are shown in the "Liquidity" column of Tables 3 and 4.

As shown in Tables 3 and 4, it can be seen that the ink compositions of Examples 1 to 8 and Reference Examples 1 and 2 have practical fluidity. In particular, the ink compositions of Examples 1, 3 and 5 using blown asphalt having an average molecular weight of 10,000 or less of all components showed substantially the same fluidity as the conventional ink composition of Reference Example 1. It can be seen that the ink composition of Example 2 exhibits fluidity without any problem in practical use. Further, the ink compositions of Examples 6 to 8 using straight asphalt showed practical fluidity, although they were slightly inferior to the conventional ink compositions of Reference Example 2. From the above, it can be understood that the ink composition of the present invention has performance comparable to that of the conventional type in terms of ink properties.

[Emulsification evaluation]
For each of the printing ink compositions of Examples 1 to 8 and Reference Examples 1 and 2, using a tabletop emulsifier (manufactured by MHI Solution Technology Co., Ltd., product name STIEU-02), dampening water (Sakata Inks Co., Ltd.) Ink composition (1 g) is kneaded with a rotating roller in the presence of (0.7% aqueous solution of etchant N-4), and the emulsification rate (%) of the ink composition is measured after 0.5 minutes. did. The results are shown in the emulsification rate columns of Tables 3 and 4.

As shown in Table 3, it can be seen that the ink compositions of Examples 1 to 5 show almost the same emulsifying property as the conventional ink composition of Reference Example 1. Further, as shown in Table 4, it can be seen that the ink compositions of Examples 6 to 8 also show almost the same emulsifying property as the conventional ink composition of Reference Example 2. From this, it can be understood that the ink composition of the present invention has the same performance as the conventional type in terms of emulsification suitability.

[Print evaluation]
N-750 type printing experimental machine (manufactured by Higashihama Seiki Co., Ltd.) for each of the ink compositions of Examples 1 to 8 and the ink compositions of Reference Examples 1 and 2 which are conventional ink compositions according to the present invention. Was used as a printing sheet for newspapers at a printing speed of 120,000 copies / hour, and a printing test was performed at a solid paper surface density of 1.05 ± 0.02. The solid paper surface density is a numerical value obtained by measuring the density of the solid portion in the printed matter with a Spectroeye densitometer (manufactured by Gretagmacbeth). In the printing evaluation, 17,000 copies of each ink composition were printed, and the allowable width for fluctuations in the amount of water during printing, that is, the water width was examined. Specifically, in order to investigate the state of being fanned when the amount of water increases, that is, the amount of decrease in the paper surface concentration due to the decrease in the amount of ink transfer when the amount of dampening water is increased, first, the normal amount of dampening water is supplied. After printing with the above to determine the density of the paper surface, the density of the paper surface when the amount of dampening water was intentionally increased was determined. The results are shown in the water width test columns of Tables 3 and 4. In addition, the accumulation state of paper dust on the printing plate after the completion of each printing and the inking property in the printed matter were also evaluated. The results are shown in the pilling columns of Tables 3 and 4. As the dampening water in the printing test, 0.7% of SAH-7 (made by Sakata Inx Corporation, alkaline H solution) was added to tap water, and the spray dampener SSD-12 (spray dampener SSD-12) was used to supply the dampening water. Using Sakata Inx Corporation), the dial of SSD-12 was raised by 60 points under the condition of increasing dampening water.

In addition, in the evaluation result in the pyring column of Tables 3 and 4, the state of the accumulation and the inking property of the paper dust in the conventional ink composition (Reference Examples 1 and 2) was set as "standard", and the embodiment according to the present invention was used. The superiority or inferiority of those states in the ink compositions 1 to 8 with respect to the "standard" was shown.

As shown in Table 3, it can be seen that the ink compositions of Examples 1 to 5 have a smaller density decrease under water-filled printing conditions and a larger water width than the conventional ink compositions of Reference Example 1. As shown in Table 4, similar results were obtained in the comparison between the ink compositions of Examples 6 to 8 and the conventional ink composition of Reference Example 2. Further, it can be seen that the ink compositions of Examples 1 to 5 retain the same performance as the ink composition of Reference Example 1 which is a conventional type for piring. Similar results were obtained in the comparison between the ink compositions of Examples 6 to 8 and the conventional ink composition of Reference Example 2. Further, when the situation of stains on the guide rollers was compared between Reference Example 2 which is a conventional ink composition and the ink compositions of Examples 6 to 8, the ink compositions of Examples 6 and 7 were found to be. The ink composition of Example 8 was almost the same as that of Reference Example 2 which was the conventional type, with less stain and better than that of Reference Example 2 which was the conventional type. From these facts, it is understood that the ink composition according to the present invention retains printability equal to or higher than that of the conventional type.

Claims (5)

It contains carbon black as a coloring pigment and heavy mineral oil and / or soybean oil as an oil component.
Further, the petroleum asphalt is characterized by containing 2.5% by mass or more with respect to the entire composition, and the petroleum asphalt is an ink composition for offset printing, which is a blown asphalt having an average molecular weight of 5000 to 10000 for all the components thereof. The offset printing ink composition according to claim 1, wherein the content of the rosin-modified phenol resin and the rosin-modified maleic acid resin in the composition is less than 3% by mass. The offset printing ink composition according to claim 1 or 2, which contains 5% by mass or more of the petroleum asphalt with respect to the entire composition. It is characterized in that petroleum asphalt is dissolved or dispersed in an oil component to form a varnish , which is used as a varnish for preparing an ink composition. A method for producing an offset printing ink composition, wherein the oil component is heavy mineral oil and / or soybean oil. Offset printing in which petroleum asphalt is dissolved or dispersed in an oil component, the petroleum asphalt is a blown asphalt having an average molecular weight of 5000 to 10000 of all the components, and the oil component is a heavy mineral oil and / or soybean oil. Varnish for preparing ink composition.