Oxidation polymerization type ink composition and method for producing oxidation polymerization type ink composition

Abstract

To provide an oxidative polymerization type ink composition capable of suppressing an excessive increase in fluidity at high temperature and improving print image quality by lowering the heating temperature necessary for obtaining the non-offset property and by reducing an energy consumption, an environmental load, a mechanical load, an amount of a wax and a heating temperature, and to provide a method of preparing the oxidative polymerization type ink composition.SOLUTION: There is provided an oxidative polymerization type ink composition comprising: (a) a vegetable oil and / or a modified vegetable oil; (b) a wax; (c) a pigment; and (d) a drying agent, wherein (b) the wax comprises at least (b1) mineral-based wax and at least one of (b2) petroleum-based wax or (b3) plant-based wax, and the content of (b) the wax is 2 mass % or more and 35 mass% or less based on 100 mass% of the total of (a), (b), (c) and (d).SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an oxidation polymerization type ink composition and a method for producing the same. In particular, it contains (a) vegetable oil and / or modified vegetable oil, (b) wax, (c) pigment, and (d) drier, and (b) the wax contains at least (b1) mineral wax and at least one of (b2) petroleum wax or (b3) plant wax, and relates to an oxidation polymerization type ink composition in which the content of (b) wax is in a specific range and a method for producing the same.

Background Art

[0002] The oxidation polymerization type ink composition utilizes the fact that the oxidation polymerizable substance contained in the ink composition reacts with oxygen in the air and hardens, and is fixed on the printing surface. As printing methods, intaglio printing, offset printing, etc. are used.

[0003] Among these, intaglio printed matter has a large finger sensitivity because it forms a printed line with a raised feeling compared to other printing methods, and is widely used in printed matter such as securities such as banknotes, stamps, and postage stamps, various certificates, and important documents that require security. On the other hand, due to the raised feeling of this printed line, there is a tendency for "back transfer", which is a phenomenon in which the ink transfers between the laminated papers after printing, to easily occur, and eliminating this is a major issue.

[0004] In order to prevent "back transfer", it is necessary to impart non-offset property (preventing the ink from detaching from the printed matter) after printing. A method of blending wax is known to impart non-offset property to the oxidation polymerization type ink composition.

[0005] Such oxidative polymerization type ink compositions need to be heated near or above the melting point of the wax during printing. On the other hand, waxes that provide high non-offset properties at room temperature after heating often have a high melting point of 70°C or higher. As a result, the heating temperature during printing increases, leading to an increase in energy consumption, environmental load, and mechanical load. So far, no oxidative polymerization type ink composition that exhibits good non-offset properties at a relatively low heating temperature has been known.

[0006] Patent Document 1 describes a gravure printing ink composition containing at least one oxidative curable main substance selected from the group consisting of alkyd resins and modified alkyd resins, at least one UV curable acrylate, at least one soluble wax having a melting point or melting range between 50 and 120°C, at least one oxidative polymerization type drier, and at least one photoinitiator.

[0007] Patent Document 2 describes an oxidative polymerization type gravure ink composition containing at least one oxidative curable varnish selected from the group consisting of vegetable oils and modified vegetable oils, at least one low melting point wax having a melting temperature range between 50°C and 85°C, at least one pigment, and at least one drier. When the oxidative polymerization type gravure ink composition is heated to a temperature at which the low melting point wax melts and then set to 30°C, the storage modulus at 30°C after heating relative to the storage modulus at the temperature at which the low melting point wax melts is 110 or more.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0009] The gravure printing ink composition described in Patent Document 1 contains acrylate and can be rapidly surface-dried. Therefore, it has effects such as elimination of drying waiting time, high productivity, and less back transfer due to instantaneous drying. However, it requires an ultraviolet irradiation process and, since it is a petroleum-derived material, it has a greater environmental impact than alkyd-based inks and is also very expensive.

[0010] Also, the oxidation polymerization type gravure ink composition described in Patent Document 2 utilizes the fact that the storage elastic modulus G’ increases dramatically due to the synergistic effect of vegetable oil and wax when passing through a temperature cycle of room temperature (25°C) - 70°C - 30°C, and has obtained high back transfer resistance while being an ink with only an oxidation-curing component for the varnish. However, the wax used in Patent Document 2 requires heating at 70°C or higher to exhibit good non-offset properties and does not exhibit good non-offset properties at relatively low heating temperatures.

[0011] The problems to be solved by the present invention are: (i) By reducing the heating temperature required to obtain non-offset properties, it is possible to reduce energy consumption, reduce environmental impact, and reduce mechanical load; (ii) By reducing the amount of wax to be blended, the cost can be reduced; (iii) By reducing the amount of wax and the heating temperature, it is possible to suppress excessive increase in fluidity under heating and improve the quality of printed image lines; (iv) It does not require special processes and devices such as a UV irradiation process and equipment. To provide an oxidation polymerization type ink composition mainly composed of plant-derived materials and a method for producing the oxidation polymerization type ink composition.

Means for Solving the Problems

[0012] As a result of intensive studies to solve the above problems, the inventors have found that the above problems can be solved by an oxidation polymerization type ink composition having a specific composition, and have completed the present invention. That is, the present invention provides the following oxidation polymerization type ink composition and a method for producing the oxidation polymerization type ink composition.

[0013] The present invention relates to an oxidative polymerization type ink composition comprising (a) vegetable oil and / or modified vegetable oil, (b) wax, (c) pigment, and (d) drier, wherein (b) the wax contains at least (b1) mineral wax and at least one of (b2) petroleum wax or (b3) plant wax, and the content of (b) the wax is 2% by mass or more and 35% by mass or less based on 100% by mass of the total of (a), (b), (c), and (d).

[0014] The present invention relates to the storage elastic modulus G ’ (30 °C) of the oxidative polymerization type ink composition is 3,500 kPa or more.

[0015] The present invention relates to the blending ratio (b1) / (b2) on a mass basis of (b1) mineral wax and (b2) petroleum wax or (b3) plant wax in (b) the wax, or the blending ratio (b1) / (b3) or the blending ratio (b1) / (b2 + b3) is 10 / 90 to 90 / 10, and it is an oxidative polymerization type ink composition.

[0016] The present invention relates to a method for producing an oxidative polymerization type ink composition, which comprises adding and mixing a material containing at least (b1) mineral wax and (d) drier to a kneaded product obtained by kneading after mixing at least (a) vegetable oil and / or modified vegetable oil and at least one of (b2) petroleum wax or (b3) plant wax.

Effects of the Invention

[0017] According to the present invention, (i) by reducing the heating temperature required to obtain non-offset property, it is possible to reduce energy consumption, reduce environmental load, and reduce mechanical load; (ii) by reducing the amount of wax to be blended, the cost can be reduced; (iii) by reducing the amount of wax and the heating temperature, it is possible to suppress an excessive increase in fluidity under heating and improve the quality of printed lines; (iv) provided is an oxidation polymerization type ink composition mainly composed of plant-derived materials and a method for producing the oxidation polymerization type ink composition, which do not require special processes or apparatuses such as a UV irradiation process or apparatus.

Brief Description of the Drawings

[0018]

Figure 1

Embodiments for Carrying Out the Invention

[0019] Hereinafter, embodiments for carrying out the present invention will be described in detail. Note that the present invention is not limited only to the following embodiments for carrying out the invention, and various modifications within the scope not changing the gist of the present invention are also included.

[0020] [Oxidation Polymerization Type Ink Composition] The oxidation polymerization type ink composition of the present invention contains (a) vegetable oil and / or modified vegetable oil, (b) wax, (c) pigment, and (d) drier, (b) wax contains at least one of at least (b1) mineral wax and (b2) petroleum wax or (b3) plant wax, and the content of (b) wax is 2% by mass or more and 35% by mass or less based on the total of (a), (b), (c), and (d) being 100% by mass.

[0021] [Vegetable Oil and / or Modified Vegetable Oil] (a) Vegetable oil and / or modified vegetable oil, which are components of the oxidative polymerization type ink composition of the present invention, are not particularly limited as long as they have oxidative polymerizability to polymerize in the presence of oxygen. It is used as an oxidative curing component constituting the oxidative polymerization type ink composition. (a) Vegetable oil and / or modified vegetable oil may be mixed with a solvent to form an oxidative polymerization type varnish and then used as a component of the oxidative polymerization type ink composition.

[0022] Examples of vegetable oils include soybean oil, linseed oil, rice bran oil, China wood oil, Japan wood oil, castor oil, dehydrated castor oil, corn oil, safflower oil, peanut oil, olive oil, cottonseed oil, sesame oil, perilla oil, sunflower oil, safflower oil, rapeseed oil, canola oil, egoma oil, camellia oil, grape seed oil, palm oil, palm kernel oil, hemp seed oil, wheat germ oil, mustard oil, kukui oil, avocado oil, oiticica oil, cocoa butter, kapok oil, kaya oil, kyo nin oil, coconut oil, walnut oil, poppy seed oil, their heat-polymerized oils, oxygen-blowing polymerized oils, recycled oils (vegetable oils used in cooking that are recovered and subjected to regeneration treatments such as removal of precipitates by filtration, standing, etc., and decolorization with activated clay, etc.). These vegetable oils may be used alone or in combination of two or more.

[0023] Examples of modified vegetable oils include vegetable oil-modified resins, vegetable oil esters (vegetable oil fatty acid esters), etc.

[0024] Vegetable oil-modified resins are obtained by subjecting one or more of resins such as alkyd resins, petroleum resins, rosin-modified phenol resins, rosin-modified alkyd resins, petroleum resin-modified alkyd resins, rosin-modified maleic resins, terpene resins, rosin ester resins, etc., and one or more of vegetable oils to a heat reaction (such as transesterification reaction and / or alkoxylation reaction, etc.).

[0025] Examples of vegetable oil-modified resins include linseed oil-modified alkyd resin, soybean oil-modified alkyd resin, tung oil-modified alkyd resin, castor oil-modified alkyd resin, tall oil-modified alkyd resin, linseed oil-modified petroleum resin, soybean oil-modified petroleum resin, tung oil-modified petroleum resin, castor oil-modified petroleum resin, tall oil-modified petroleum resin, linseed oil-modified rosin ester resin, soybean oil-modified rosin ester resin, tung oil-modified rosin ester resin, castor oil-modified rosin ester resin, tall oil-modified rosin ester resin, and the like. Among these, linseed oil-modified alkyd resin, soybean oil-modified alkyd resin, castor oil-modified alkyd resin, and tall oil-modified alkyd resin are preferably used. The modified vegetable oil may be used alone or in combination of two or more.

[0026] Vegetable oil esters (vegetable oil fatty acid esters) are obtained by subjecting one or more types of vegetable oils and one or more types of alcohol compounds to a transesterification reaction. They can also be obtained by subjecting the fatty acids of vegetable oils and alcohol compounds to an esterification reaction. Examples of alcohol compounds include saturated alcohols such as methanol, ethanol, n-propanol, i-propanol, n-butanol, t-butanol, heptynol, 2-ethylhexanol, hexanol, octanol, decanol, dodecanol; and unsaturated aliphatic alcohols such as oleyl alcohol, dodecenol, icosenol, undecenol, eicosenol, octadecenol, octenol, decenol, tetradecenol, dodecenol, tridecenol, nonadecenol, nonenol, butenol, propenol, hexenol, heptenol, pentadecenol, pentenol.

[0027] Examples of the vegetable oil ester (vegetable oil fatty acid ester) include methyl linseed oil fatty acid, ethyl linseed oil fatty acid, butyl linseed oil fatty acid, methyl soybean oil fatty acid, ethyl soybean oil fatty acid, butyl soybean oil fatty acid, methyl palm oil fatty acid ester, ethyl palm oil fatty acid ester, propyl palm oil fatty acid ester, butyl palm oil fatty acid ester, methyl castor oil fatty acid ester, ethyl castor oil fatty acid ester, propyl castor oil fatty acid ester, butyl castor oil fatty acid ester, and esters of Aleurites moluccana oil. The vegetable oil ester (vegetable oil fatty acid ester) may be used alone or in combination of two or more thereof.

[0028] The content of (a) vegetable oil and / or modified vegetable oil in the oxidative polymerization type ink composition is not particularly limited. Taking the total of (a), (b), (c), and (d) constituting the oxidative polymerization type ink composition as 100% by mass, for example, it is 10% by mass or more, preferably 15% by mass or more, more preferably 25% by mass or more, and for example, 75% by mass or less, preferably 70% by mass or less, more preferably 55% by mass or less. When the content of (a) vegetable oil and / or modified vegetable oil in the oxidative polymerization type ink composition is less than 15% by mass, the fastness of the cured film of the oxidative polymerization type ink composition may decrease.

[0029] <(b) Wax> (b) Wax, which is a constituent of the oxidative polymerization type ink composition of the present invention, contains at least one of (b1) mineral wax and (b2) petroleum wax or (b3) plant wax. Wax can improve the anti-back transfer property, abrasion resistance, blocking prevention property, slipperiness, anti-slipping property, etc. of the oxidative polymerization type ink composition coating film.

[0030] (b1) The mineral wax is not particularly limited. For example, montan wax (purified montan wax, montanic acid, montan amide, montan ester, modified or saponified montan wax, etc.), ozokerite, ceresin wax, derivatives obtained by subjecting these to modifications such as purification, oxidation, esterification, saponification, etc. are used. (b1) The mineral wax may be used alone or in combination of two or more thereof. The melting point (temperature at which melting occurs) of the (b1) mineral wax is not particularly limited. The melting point is, for example, 50 °C or higher, preferably 55 °C or higher, and, for example, 85 °C or lower, preferably 70 °C or lower. When the melting point exceeds 85 °C, when printing the oxidation polymerization type ink composition, the heating temperature of the printing plate surface has to be increased, requiring a lot of energy, and the load on the printing machine, etc. also increases. When the melting point is less than 50 °C, the oxidation polymerization type ink composition may solidify during storage.

[0031] (b2) The petroleum wax is not particularly limited. For example, paraffin wax, microcrystalline wax, petrolactam, derivatives obtained by subjecting these to modifications such as purification, oxidation, esterification, saponification, etc. are used. (b2) The petroleum wax may be used alone or in combination of two or more thereof. The melting point (temperature at which melting occurs) of the (b2) petroleum wax is not particularly limited. The melting point is, for example, 50 °C or higher, preferably 55 °C or higher, and, for example, 85 °C or lower, preferably 65 °C or lower. When the melting point exceeds 85 °C, when printing the oxidation polymerization type ink composition, the heating temperature of the printing plate surface has to be increased, requiring a lot of energy, and the load on the printing machine, etc. also increases. When the melting point is less than 50 °C, the oxidation polymerization type ink composition may solidify during storage.

[0032] (b3) The plant wax is not particularly limited. For example, candelilla wax, carnauba wax, rice wax, wood wax, jojoba oil, oryctes wax, derivatives obtained by subjecting these to modifications such as purification, oxidation, esterification, saponification, etc. are used. Further, (b3) the plant wax may be used alone or in combination of two or more. The melting point (temperature at which melting occurs) of (b3) the plant wax is not particularly limited. The melting point is, for example, 50°C or higher, preferably 55°C or higher, and, for example, 85°C or lower, preferably 70°C or lower. When the melting point exceeds 85°C, the heating temperature of the printing plate surface must be increased during printing of the oxidation polymerization type ink composition, which requires a large amount of energy and also increases the load on the printing machine, etc. When the melting point is less than 50°C, the oxidation polymerization type ink composition may solidify during storage.

[0033] The content of (b) wax in the oxidation polymerization type ink composition is 2% by mass or more, preferably 3% by mass or more, more preferably 4% by mass or more, and 35% by mass or less, preferably 33% by mass or less, more preferably 30% by mass or less, with the total of (a), (b), (c), and (d) constituting the oxidation polymerization type ink composition being 100% by mass. When the content of (b) wax is less than 2% by mass, the resistance to reverse transfer may decrease. When it exceeds 35% by weight, it may be difficult to prepare the oxidation polymerization type ink composition. Further, the blending ratio of (b1) mineral wax and (b2) petroleum wax based on mass is not particularly limited.

[0034] The oxidative polymerization type ink composition of the present invention contains at least (b1) a mineral wax and at least one of (b2) a petroleum wax or (b3) a plant wax. The inventors have found that thereby, when the heating temperature during printing is at a temperature not higher than the melting point of the wax having the higher melting point among at least (b1) and (b2), and in some cases even not higher than the melting points of (b1) and (b2), the degree of solidification when the oxidative polymerization type ink composition is brought to room temperature increases significantly compared to the case where one type of wax is used. For example, the oxidative polymerization type ink composition of the examples contains a montanic acid wax having a melting point of 66°C and a paraffin wax having a melting point of 61°C, and strongly solidifies when heated to 60°C and then allowed to cool to room temperature (25°C). Thereby, even if the heating temperature when printing the oxidative polymerization type ink composition is, for example, 60°C which is not higher than the melting point of the wax, when it returns to room temperature after printing, since the degree of solidification of the ink composition has increased significantly, even when overlaid after printing, it exhibits sufficient anti-blocking property with almost no blocking.

[0035] As the (b) wax which is a constituent component of the oxidative polymerization type ink composition of the present invention, in addition to (b1) a mineral wax and (b2) a petroleum wax or (b3) a plant wax, one or more of an animal wax and a synthetic wax may be used in an amount of 30 parts by mass or less based on 100 parts by mass of the total (b) wax. As the plant wax, candelilla wax, carnauba wax, rice wax, wood wax, jojoba oil, ouricury wax, derivatives obtained by subjecting these to modifications such as purification, oxidation, esterification, saponification, etc. are used.

[0036] As the animal wax, beeswax, shellac wax, wool wax (lanolin), whale oil, derivatives obtained by subjecting these to modifications such as purification, oxidation, esterification, saponification, etc. are used.

[0037] Examples of synthetic waxes include synthetic hydrocarbon waxes (Fisher-Tropsch waxes (Sasol waxes), polyethylene waxes, low molecular weight polymers with a viscosity average molecular weight of 500 to 20,000 (e.g., polypropylene, ethylene-acrylic acid copolymers, polytetrafluoroethylene, polyamides, polyethylene glycols, polypropylene glycols, etc.), hydrogenated waxes (hydrogenated castor oil and hydrogenated castor oil derivatives), fatty acid waxes, acid amide waxes, amine waxes, imide waxes, ester waxes, ketone waxes, and derivatives obtained by subjecting these to modifications such as purification, oxidation, esterification, saponification, etc. are used.

[0038] Note that waxes other than (b1) mineral waxes, (b2) petroleum waxes, and (b3) plant waxes may be used alone or in combination of two or more.

[0039] <(c) Pigment> The (c) pigment, which is a constituent of the oxidation polymerization type ink composition of the present invention, is not particularly limited as long as it does not inhibit oxidation polymerization. The definition of "pigment" in the present invention includes dyes. Appropriate ones are used from inorganic pigments, organic pigments, and dyes in order to obtain a desired color and ink flow characteristics.

[0040] Examples of inorganic pigments include carbon black, titanium oxide, zinc oxide, red iron oxide, calcium carbonate, barium sulfate, silica, clay, talc, alumina, zinc yellow, ultramarine blue, lapis lazuli, graphite, aluminum powder, etc.

[0041] Examples of organic pigments include azo-based, diazo-based, condensed azo-based, azomethine-based, indanthrone-based, carbonyl-based, anthraquinone-based, nitro-based, phthalocyanine-based, indigo-based, thioindigo-based, benzodifuranone-based, benzimidazolone-based, methine-based, polyene-based, polymethine-based, dioxazine-based, quinacridone-based, isoindoline-based, quinophthalone-based, perylene-based, perinone-based, triallylmethane-based, diketopyrrolopyrrole-based, and carotene-based, etc.

[0042] As the dye, for example, one or more of reactive dyes, direct dyes, anionic dyes, cationic dyes, acid dyes, basic dyes, food colorants, metal complex dyes, and solvent dyes can be used. As the dye, for example, dyes such as coumarin-based, cyanine-based, oxazine-based, phthalocyanine-based, indolinocyanine, triphenylmethane-based, naphthalocyanine-based, anthraquinone-based, azo-based, rhodamine-based, and squarylium-based dyes can be used.

[0043] Note that the pigments may be used singly or in combination of two or more.

[0044] The content of (c) the pigment in the oxidation polymerization type ink composition is not particularly limited. Assuming that the total of (a), (b), (c), and (d) constituting the oxidation polymerization type ink composition is 100% by mass, for example, it is 10% by mass or more, preferably 15% by mass or more, more preferably 20% by mass or more, and for example, 75% by mass or less, preferably 70% by mass or less, more preferably 65% by mass or less.

[0045] <(d) Drying agent> The (d) drying agent, which is a constituent of the oxidation polymerization type ink composition of the present invention, is a compound that acts as a catalyst in the drying and curing by oxidation polymerization of the oxidation polymerization type ink composition. It may also be referred to as an (oxidation polymerization type) drier, an oxidation polymerization catalyst, an oxidation drying agent, or a drying substance.

[0046] As the drying agent, for example, it contains one or more salts composed of any one or more cations of metals such as cobalt, calcium, copper, zinc, iron, zirconium, manganese, cerium, zirconium, barium, zinc, strontium, lithium, vanadium, and potassium, and any one or more anions such as halogen, boric acid, nitric acid, sulfuric acid, carboxylic acid (for example, acetic acid, ethylhexanoic acid, octylic acid, naphthenic acid, acetoacetonate, resin acid, tall oil fatty acid, etc.), but is not limited thereto.

[0047] The desiccant may be used alone or in combination of two or more thereof.

[0048] The content of the desiccant (d) in the oxidation polymerization type ink composition is not particularly limited. Taking the total of (a), (b), (c) and (d) constituting the oxidation polymerization type ink composition as 100% by mass, for example, it is 0.005% by mass or more, preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and 5.0% by mass or less, preferably 3.0% by mass or less, more preferably 2.0% by mass or less.

[0049] <Other components> Furthermore, in the gravure ink composition, if necessary, an oxidation polymerizable substance other than "(a) vegetable oil and / or modified vegetable oil" (hereinafter sometimes referred to as "other oxidation polymerizable substance"), a gelling agent, a solvent, a filler (extender), a surfactant, an antioxidant, an anti-settling agent, an antifoaming agent, an anti-blocking agent, a magnetic material, a luminescent material, a conductive material, an infrared absorbing material, etc. may be added and used. In the present invention, only one of these other components may be used alone, or two or more thereof may be used in combination.

[0050] (Other oxidation polymerizable substances) The oxidation polymerization type ink composition of the present invention may contain other oxidation polymerizable substances in addition to (a) vegetable oil and / or modified vegetable oil. The other oxidation polymerizable substances may be used as the oxidation curing component of the oxidation curing type varnish.

[0051] Examples of the other oxidation polymerizable substances include alkyd resins, phenol-modified alkyd resins, epoxy-modified alkyd resins, urethane-modified alkyd resins, silicone-modified alkyd resins, acrylic-modified alkyd resins, vinyl-modified alkyd resins, neutralized acid alkyd resins, rosin-modified maleic acid resins, unsaturated polyester resins, petroleum resins (aromatic type, aliphatic type, aromatic-aliphatic copolymer type), rosin esters, phenol-modified rosins, phenol resins, rosin-modified phenol resins, resole type or novolak type resins such as octylphenol and nonylphenol.

[0052] In addition, as for other oxidation polymerizable substances, one of these may be used alone, or two or more of them may be used in combination.

[0053] <Gelling agent> The oxidation polymerization type ink composition of the present invention may contain a gelling agent for the purpose of adjusting viscoelasticity and the like. As the gelling agent, for example, an organic aluminum compound, an organic titanate compound, an organic zinc compound, an organic zirconium compound, etc. can be used. Among them, an organic aluminum compound (for example, aluminum alcoholate, aluminum chelate compound (aluminum diisopropoxide monoethyl acetoacetate, aluminum di-n-butoxide monomethyl acetoacetate, aluminum di-n-butoxide monoethyl acetoacetate, aluminum di-i-butoxide monomethyl acetoacetate, aluminum di-sec-butoxide monoethyl acetoacetate, aluminum tris(acetylacetonate), aluminum tris(ethylacetoacetonate), aluminum mono-acetylacetonate-bis(ethylacetoacetonate), etc.)) is preferable. In the present invention, only one of these gelling agents may be used alone, or two or more of them may be used in combination. The gelling agent can be used, for example, in an amount of 5 parts by mass or less based on 100 parts by mass of the entire oxidation polymerization type ink composition.

[0054] <Solvent> The oxidation polymerization type ink composition of the present invention may contain a solvent for the purpose of adjusting viscosity and the like. As the solvent, for example, mineral oil, alcohol-based solvent, ether-based solvent, ester-based solvent, hydrocarbon-based solvent, etc. can be used.

[0055] <Physical properties, etc. of the oxidation polymerization type ink composition> (Viscosity and yield value) The viscosity, which is an index of the fluidity characteristics of the oxidation polymerization type ink composition, is not particularly limited. When used for gravure printing, from the viewpoints of line reproduction and handling workability, for example, the viscosity at 30 °C is 25 Pa·s or more, preferably 30 Pa·s or more and 700 Pa·s or less, preferably 500 Pa·s or less, and the viscosity at 60 °C is 5 Pa·s or more, preferably 10 Pa·s or more and 25 Pa·s or less, preferably 22 Pa·s or less, and is adjusted accordingly.

[0056] The yield value, which is an index of the fluidity characteristics of the oxidation polymerization type ink composition, is not particularly limited. When used for gravure printing, from the viewpoints of line reproduction and handling workability, for example, the yield value at 30 °C is 400 Pa or more, preferably 450 Pa or more and 3,000 Pa or less, preferably 2,700 Pa or less, and the yield value at 60 °C is 200 Pa or more, preferably 250 Pa or more and 1,000 Pa or less, preferably 900 Pa or less, and is adjusted accordingly.

[0057] The oxidation polymerization type ink composition of the present invention has a low viscosity and yield value at room temperature (30 °C) before being supplied to the printing machine and exhibits high fluidity. Therefore, it is possible to automatically supply the oxidation polymerization type ink composition to the printing machine. As a result, the production efficiency and work efficiency of printed matter are good. The viscosity and yield value of the oxidation polymerization type ink composition can be measured, for example, by the method described in the examples.

[0058] (Storage elastic modulus) The storage elastic modulus (G ’ (at 30 °C)) when the oxidation polymerization type ink composition is heated to a constant temperature T °C and then set to 30 °C is not particularly limited. When used for gravure printing, in order to improve the anti-back transfer property, when T is 60 °C, G ’ (at 30 °C) and when T is 70 °C, G ’ (at 30 °C) are both preferably adjusted to be 2,000 kPa or more, preferably 4,000 kPa or more. In particular, the storage elastic modulus G ’When (30°C) is 2,000 kPa or more, the oxidative polymerization type ink composition can be hardened after heating and cooling, and the anti-back transfer property can be improved.

[0059] The heating temperature T is 50°C or more, preferably 55°C or more, and 80°C or less, preferably 65°C or less. The higher the heating temperature T, the more the melting of the wax is promoted, so the storage modulus at T°C becomes smaller, and the storage modulus G ’ (30°C) becomes larger. However, the larger the value of T, the greater the temperature load, environmental load, and energy consumption on the printing machine.

[0060] In the present invention, due to the synergistic effect of (a) vegetable oil and / or modified vegetable oil and (b) wax, G ’ (30°C) and G ’ (30°C) can both be 5,000 kPa or more when T is 70°C. Thereby, when a cooling line is formed after heating during printing to form a printed line, the anti-back transfer property of the printed matter can be improved, and further, the temperature load, environmental load, and energy consumption on the printing machine can be suppressed. The storage modulus of the oxidative polymerization type ink composition can be measured, for example, by the method described in the examples.

[0061] [Method for producing oxidative polymerization type ink composition] The method for producing the oxidative polymerization type ink composition is not particularly limited as long as an oxidative polymerization type ink composition in which at least the components (a), (b), (c), and (d) are uniformly mixed can be formed. For example, method A: a method of kneading after mixing at least (a) vegetable oil and / or modified vegetable oil, (b) wax, (c) pigment, and (d) drier; method B: a method of kneading after mixing at least (a), (b), and (c), and then mixing at least (d) into the kneaded product; method C: a method of kneading after mixing at least (a) and (c), and then mixing at least (b) and (d) into the kneaded product; method D: a method of kneading after mixing at least (a), (b2) petroleum wax or (b3) plant wax, and (c), and then mixing at least (b1) mineral wax and (d) into the kneaded product; method E: a method of preparing an oxidative polymerization type varnish containing at least (a), adding at least (b), (c), and (d) to the oxidative polymerization type varnish, and kneading; method F: a method of preparing an oxidative polymerization type varnish containing at least (a), mixing at least (b) and (c) into the oxidative polymerization type varnish and kneading, and then mixing at least (d) into the kneaded product; method G: a method of preparing an oxidative polymerization type varnish containing at least (a), mixing at least (c) into the oxidative polymerization type varnish and kneading, and then mixing at least (b) and (d) into the kneaded product; method H: a method of preparing an oxidative polymerization type varnish containing at least (a), mixing (b2) or (b3) and (c) into the oxidative polymerization type varnish and kneading, and then mixing (b1) and (d) into the kneaded product; method I: a method of preparing an oxidative polymerization type varnish containing at least (a), mixing (b2) or (b3) and (c) into the oxidative polymerization type varnish and kneading, and then mixing ground (b1) and (d) into the kneaded product, etc. are used.

[0062] In the kneading in the method for producing an oxidative polymerization type ink composition, for example, a kneading machine such as a three-roll mill, bead mill, ball mill, etc. is used. Also, in the mixing of each component in the method for producing an oxidative polymerization type ink composition, for example, a mixer such as a planetary mixer, tumbler, stirrer, agitator, mechanical homogenizer, ultrasonic homogenizer, paint shaker, V-type blender, Nauta mixer, etc. is used.

[0063] Among these methods, by adopting the production methods of the aforementioned C, D, G, H, or I, a part of the mineral wax with a low melting point is caused by the heat generated during kneading ruIt is possible to prevent melting and prevent the increase in viscosity and yield value. As a result, an oxidation polymerization type ink composition having high fluidity, being relatively soft, and having excellent handling workability such as filling into a container and automatic supply to a printing machine can be produced. In the present invention, it is particularly preferable to adopt the above-described method for producing ku or ke.

[0064] [Printing of Oxidation Polymerization Type Ink Composition] The oxidation polymerization type ink composition of the present invention can be printed on a substrate by printing methods such as intaglio printing, relief printing, offset printing, screen printing, inkjet printing, etc. The substrate is not particularly limited. For example, it is paper, plastic film, glass, metal, wood, composites thereof, etc.

[0065] The oxidation polymerization type ink composition of the present invention is used for printing various printed matters. Preferably, it is used for security printed matters and printed matters requiring design properties, such as banknotes (paper money), stamps, postage stamps, securities, identity certificates, passports, security labels, etc.

Examples

[0066] Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. Unless otherwise specified, "parts" in each example are parts by mass, and "%" is "% by mass".

[0067] [Ink Raw Materials] The ink raw materials used in the Examples and Comparative Examples are as follows. Vegetable oil and / or modified vegetable oil: Linseed oil-modified alkyd resin Mineral wax 1: Montanic acid wax ("Licowax WE40" manufactured by Clariant) Petroleum wax 1: Paraffin wax ("Paraffin Wax-140" manufactured by Nippon Seiro Co., Ltd.) Petroleum wax 2: Paraffin wax ("HNP-5" manufactured by Nippon Seiro Co., Ltd.) Petroleum wax 3: Paraffin wax ("SP-0145" manufactured by Nippon Seiro Co., Ltd.) Plant wax 1: Candelilla wax (MD-21 manufactured by Yokose Oil & Fat Industry Co., Ltd.) Pigments: Red pigment, black pigment, blue pigment, brown pigment Desiccant: Mixture of cobalt 2-ethylhexanoate and 2-ethylhexanoic acid (manufactured by Nippon Chemical Industry Co., Ltd.)

[0068] [Evaluation of ink] <Viscosity and yield value> The viscosity and yield value were determined using a rheometer (Modular Compact Rheometer MCR 302 manufactured by Anton Paar) and a CP25 type cone plate. At 30 °C, 60 °C or 70 °C, the shear rate was changed from 0 s ‐1 to 10 s ‐1 and then after 10 s ‐1 from 10 s ‐1 to 0 s ‐1 The shear stress (flow curve) was measured, and the flow curve in the region from 10 s ‐1 to 2.5 s

[0069] <Storage modulus> The ink compositions of Examples 1 to 15 and Comparative Examples 1 and 2 were heated from room temperature (25 °C), held at 60 °C or 70 °C for 1 minute, and then the storage modulus was measured every 1 °C until it reached 30 °C at a cooling rate of 5 °C / min. The storage modulus G ’ (30 °C) was determined. The storage modulus was measured using a rheometer (Modular Compact Rheometer MCR 302 manufactured by Anton Paar). The measurement conditions were: oscillation angle 0.1%, frequency 1.0 Hz, strain 0.1%, using a 25 mm parallel plate, and gap 0.25 mm.

[0070] <Blocking resistance> In Examples 1 to 15 and Comparative Examples 1 and 2, each ink composition, which was heated to 60°C or 70°C and held for 1 minute and then cooled to measure the storage elastic modulus, was used to perform printing on high-quality paper with a gravure printing machine. The maximum depth of the gravure plate surface was about 80 μm, and the plate surface temperature was 60°C. 5,000 printed sheets were stacked in a pile, and after standing for 1 week, the printed sheets were visually evaluated according to the following criteria. 〇: No reverse transfer occurred (qualified) ×: Reverse transfer occurred (unqualified)

[0071] [Example 1] <Manufacture of oxidative polymerization type ink composition> 42 parts of modified vegetable oil (linseed oil-modified alkyd resin), 8 parts of mineral wax 1 (montanic acid wax), 2 parts of petroleum wax 1 (paraffin wax), and 47 parts of pigment were mixed and kneaded with a three-roll mill to obtain a kneaded product. The obtained kneaded product and 1 part of a drier were mixed with a planetary mixer to prepare an oxidative polymerization type ink composition according to Example 1. The composition, viscosity (at 30°C, 60°C, and 70°C), yield value (at 30°C, 60°C, and 70°C), storage elastic modulus (at 30°C after heating at 60°C or 70°C), and reverse transfer resistance evaluation of the obtained oxidative polymerization type ink composition are shown in Table 1.

[0072] [Examples 2 to 11, Comparative Examples 1 to 4] Oxidative polymerization type ink compositions were prepared in the same manner as in Example 1, except that the constituent components of the oxidative polymerization type ink compositions were the components described in Tables 1 and 2, respectively. The composition, viscosity (at 30°C, 60°C, and 70°C), yield value (at 30°C, 60°C, and 70°C), storage elastic modulus (at 30°C after heating at 60°C or 70°C), and reverse transfer resistance evaluation of each of the obtained oxidative polymerization type ink compositions are shown in Tables 1 and 2.

[0073] [Example 12] <Manufacture of oxidative polymerization type ink composition> 21 parts of modified vegetable oil (linseed oil-modified alkyd resin), 5 parts of mineral wax 1 (montanic acid wax), and 23 parts of pigment were mixed and kneaded with a three-roll mill to obtain a kneaded product. Also, 21 parts of modified vegetable oil (linseed oil-modified alkyd resin), 5 parts of plant wax 1 (candelilla wax), and 24 parts of pigment were mixed and kneaded with a three-roll mill to obtain a kneaded product. Two of the obtained kneaded products and 1 part of a drying agent were mixed with a planetary mixer to prepare the oxidative polymerization type ink composition according to Example 12.

[0074] [Example 13] An oxidative polymerization type ink composition was prepared in the same manner as in Example 12, except that the constituent components of the oxidative polymerization type ink composition were the components described in Tables 1 and 2, respectively. The composition, viscosity (at 30°C, 60°C, and 70°C), yield value (at 30°C, 60°C, and 70°C), storage elastic modulus (at 30°C after heating at 60°C or 70°C), and reverse transfer resistance evaluation of each of the obtained oxidative polymerization type ink compositions are shown in Tables 1 and 2.

[0075] [Example 14] [Manufacture of Oxidative Polymerization Type Ink Composition] 42 parts of modified vegetable oil (linseed oil-modified alkyd resin), 5 parts of petroleum wax 1 (paraffin wax), and 47 parts of pigment were mixed and kneaded with a three-roll mill to obtain a kneaded product. 5 parts of mineral wax 1 (montanic acid wax) were micronized with a jet mill to obtain micronized wax 1. The obtained kneaded product, micronized wax 1, and 1 part of a drying agent were mixed with a planetary mixer to prepare the oxidative polymerization type ink composition according to Example 14.

[0076] [Example 15] An oxidative polymerization type ink composition was prepared in the same manner as in Example 14, except that the constituent components of the oxidative polymerization type ink composition were the components described in Table 2. The composition, viscosity (at 30°C, 60°C, and 70°C), yield value (at 30°C, 60°C, and 70°C), storage elastic modulus G ’ (at 30°C) (at 30°C after heating at 60°C or 70°C) and reverse transfer resistance evaluation are shown in Table 2.

[0077] [Example 16] An oxidation polymerization type ink composition was prepared in the same manner as in Example 12, except that the components of the oxidation polymerization type ink composition were the components described in Tables 1 and 2, respectively. The composition, viscosity (at 30 °C, 60 °C, and 70 °C), yield value (at 30 °C, 60 °C, and 70 °C), storage modulus (at 30 °C after heating at 60 °C or 70 °C), and reverse transfer resistance evaluation of each of the obtained oxidation polymerization type ink compositions are shown in Tables 1 and 2.

[0078]

Table 1

[0079]

Table 2

[0080] From Tables 1 and 2, it can be seen that the oxidation polymerization type ink compositions mainly composed of plant-derived materials according to Examples 1 to 15 have a high storage modulus (an index of the degree of solidification of the oxidation polymerization type ink composition) of 4,000 kPa or more after heating at 60 °C.

[0081] As a result, even if the heating during printing (plate surface heating temperature) is lowered, non-offset properties can be exhibited, and a printed matter with good reverse transfer resistance can be obtained. Furthermore, reduction of energy consumption, reduction of environmental load, and reduction of mechanical load can be achieved.

[0082] Although the present invention has been described in detail above, various changes can be made without departing from the scope of the present invention in the above configuration. Therefore, all matters included in the above description or shown in the attached drawings should be construed as illustrative.

Explanation of Signs

[0083] (a-1) to (a-3): Scanning electron microscope (SEM) photographs of a kneaded product containing linseed oil-modified alkyd resin and paraffin wax ("Paraffin Wax-140" manufactured by Nippon Seiro Co., Ltd.) after heating at 60 °C (a-1), 70 °C (a-2) or 80 °C (a-3) for 30 minutes, cooling, immersing in ethanol for 2 weeks to remove and dry the linseed oil-modified alkyd resin. (b-1) to (b-3): Scanning electron microscope (SEM) photographs of a kneaded product containing linseed oil-modified alkyd resin and mineral wax ("Licowax WE40" (Li40) manufactured by Clariant) after heating at 60 °C (b-1), 70 °C (b-2) or 80 °C (b-3), cooling, and performing the above treatment. (c-1) to (c-3): Scanning electron microscope (SEM) photographs of a kneaded product containing linseed oil-modified alkyd resin (MO15), mineral wax ("Licowax WE40" (Li40) manufactured by Clariant), and paraffin wax ("Paraffin Wax-140" manufactured by Nippon Seiro Co., Ltd.) after heating at 60 °C (b-1), 70 °C (b-2) or 80 °C (b-3), cooling, and performing the above treatment.

Claims

1. An oxidation polymerization type ink composition comprising: (a) vegetable oil and / or modified vegetable oil, (b) wax, (c) pigment, and (d) drier, wherein the (b) wax contains at least one of (b1) mineral wax, (b2) petroleum wax, or (b3) plant wax, the content of the (b) wax is 4% by mass or more and 35% by mass or less based on 100% by mass of the total of (a), (b), (c), and (d), an oxidation polymerization type ink composition having a storage elastic modulus G' of 3,500 kPa or more when the oxidation polymerization type ink composition is heated to 60°C for 1 minute and then cooled to 30°C.

2. An oxidation polymerization type ink composition comprising: (a) vegetable oil and / or modified vegetable oil, (b) wax, (c) pigment, and (d) drier, wherein the (b) wax contains at least one of (b1) mineral wax, (b2) petroleum wax, or (b3) plant wax, the content of the (b) wax is 4% by mass or more and 35% by mass or less based on 100% by mass of the total of (a), (b), (c), and (d), and the mixing ratio (b1):(b2) or (b1):(b3) or (b1):(b2 + b3) by mass of the (b1) mineral wax and the (b2) petroleum wax or the (b3) plant wax in the (b) wax is 10:90 to 90:

10.

3. A method for producing the oxidation polymerization type ink composition according to any one of Claims 1 or 2, wherein a material containing at least the (b1) mineral wax and the (d) drier is added to and mixed with a kneaded product obtained by kneading after mixing at least one of the (a) vegetable oil and / or the modified vegetable oil, the (c) pigment, and the (b2) petroleum wax or the (b3) plant wax.

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