Oil-based ink composition

Abstract

To provide an oil-based ink composition that can be used for clear marking without being dried and solidified during work hours, even without an airtight mechanism in a marking device, can be dried and fixed on non-absorbent surfaces of resin, glass, metal, and the like, by the next day after marking, and will not peel off even when exposed to flowing water, such as rain, immediately after marking.SOLUTION: An oil-based ink composition is made by mixing at least a hydrophobic organic solvent with a boiling point of 200°C to 300°C, a resin soluble in the hydrophobic organic solvent, and a colorant, wherein the content of the hydrophobic organic solvent is at least 70 wt.% relative to the total solvent mass. It is preferred that the resin and colorant have weather resistance.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an oil-based ink composition that has excellent fixability, water resistance, and weather resistance even on non-absorbent surfaces such as resins, glass, and metals, and also has an appropriate drying property. [Background technology]

[0002] In steel frame construction, after components are fully tightened with bolts, nuts, washers, etc., a series of linear marks are applied to the bolts, nuts, washers, and components, etc., and after a certain period of time has passed since tightening, the positional deviation angle of these marks is used to check whether the fastening components have loosened.

[0003] Inks that must maintain marks outdoors for long periods of time must have good fixability, weather resistance, and water resistance so that they do not peel off due to running water from rain, etc. Fast-drying inks are preferably used for non-absorbent surfaces such as bolts, and when using fast-drying inks, it is common to use equipment with an airtight mechanism to prevent the printed surface of the marking device from drying out and hardening.

[0004] However, marking devices with airtight mechanisms have many structural limitations, and in some cases, airtightness has had to be sacrificed in order to improve convenience. Furthermore, when a cap is used to make a stamp or marker pen airtight, the cap must be attached and detached during work, which creates problems in terms of work efficiency. In particular, since marking to check loosening of fastening members is expected to be performed at high altitudes, a marking device that does not require the attachment and detachment of a cap or the replacement of a cartridge during work is desired. Summary of the Invention [Problem to be solved by the invention]

[0005] The object of the present invention is to solve the above problems and to provide an ink which can produce clear markings without drying and solidifying during working hours even if the marking device does not have an airtight mechanism, which dries and fixes by the next day after marking even on non-absorbent surfaces such as resin, glass and metal, and which does not peel off even if exposed to running water such as rain immediately after marking. [Means for solving the problem]

[0006] The present invention, which was completed to achieve the above-mentioned object, is an oil-based ink composition comprising at least a hydrophobic organic solvent having a boiling point of 200°C to 300°C, a resin soluble in said solvent, and a colorant, wherein the proportion of said solvent is at least 70% by weight or more relative to the total mass of the solvent.

[0007] In the present invention, weather-resistant resins and colorants can be selectively used.

[0008] The oil-based ink composition of the present invention can be used for conventionally known writing implements, ink-penetrating stamps, vermilion ink pads, stamp pads, etc., but is particularly suitable for stamping or marking, and further for checking the loosening of fastening members such as bolts. [Effects of the Invention]

[0009] By blending at least a hydrophobic organic solvent having a boiling point of 200°C to 300°C, a resin soluble in the hydrophobic organic solvent, and a colorant, and by making the ratio of the hydrophobic organic solvent at least 70% by weight or more relative to the total mass of the solvent, it is possible to provide an ink that can produce clear markings without drying and solidifying during operation, even if the marking device does not have an airtight mechanism, and that dries and fixes by the next day after marking even on non-absorbent surfaces such as resin, glass, and metal, and that will not peel off even if exposed to running water such as rain immediately after marking.

[0010] By using weather-resistant resins and colorants, the weather resistance of the ink is further improved, making it possible to apply markings that do not discolor or fade due to ultraviolet rays, etc.

[0011] The oil-based ink composition of the present invention can be used in conventionally known writing instruments, ink-penetrating stamps, vermilion ink pads, stamp pads, etc., but since the ink dries after a certain period of time, it is particularly preferred to use it in stamps that can be used continuously by replacing the cartridge, or in marking pens that are inexpensive and easy to replace.

[0012] Furthermore, the oil-based ink composition of the present invention can be used outdoors on non-absorbent surfaces such as metal, and since the marking device does not require airtightness, there is no need to attach or detach a cap or cartridge during work, making it suitable for checking for looseness of fastening members such as bolts. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described in detail. The oil-based ink composition of the present invention comprises at least a hydrophobic organic solvent having a boiling point of 200°C to 300°C, a resin soluble in said solvent, and a colorant, and an essential constituent requirement is that the proportion of said solvent is at least 70% by weight based on the total mass of the solvent.

[0014] The organic solvent used in the present invention preferably has a boiling point of 200°C to 300°C, is hydrophobic, and has a solubility in water of 10% or less at 20°C. If the boiling point is less than 200°C or more than 300°C, adequate drying properties cannot be obtained. Furthermore, if the solubility in water at 20°C exceeds 10%, the ink tends to peel off when exposed to running water, which is undesirable as it causes problems with water resistance.

[0015] The organic solvent used in the present invention is not particularly limited as long as it has a boiling point of 200°C to 300°C and is hydrophobic. Examples of suitable organic solvents include benzyl alcohol (205°C, 4.0%), dipropylene glycol-n-butyl ether (230°C, 5.0%), tripropylene glycol monobutyl ether (274°C, 3.0%), ethylene glycol monohexyl ether (208°C, 0.9%), ethylene glycol mono-2-ethylhexyl ether (229°C, 0.2%), diethylene glycol mono-2-ethylhexyl ether (272°C, 0.8%), and ethylene glycol mono-2-ethylhexyl ether (272°C, 0.8%). Examples include ethylene glycol phenyl ether (245°C, 2.7%), diethylene glycol phenyl ether (298°C, 3.5%), diethylene glycol di-n-butyl ether (255°C, 0.3%), diethylene glycol monobutyl ether acetate (247°C, 6.5%), dihydroterpineol (210°C, 0.5%), tetralin (207°C, 0.5%), isophorone (215°C, 1.2%), benzyl cinnamate (205°C, 0.0%), and ethyl benzoate (212°C, 0.1%). The values listed at the end of each organic solvent are the boiling point and solubility in water at 20°C. These solvents may be used alone or in combination.

[0016] In the present invention, solvents typically used in inks other than the above organic solvents can be blended in. Examples include alcohols such as methanol, ethanol, propanol, butanol, pentanol, and hexanol, aliphatic hydrocarbons such as n-hexane and n-octane, alicyclic hydrocarbons such as methylcyclohexane and dimethylcyclohexane, aromatic hydrocarbons such as benzene, toluene, and xylene, ketones such as methyl ethyl ketone, dimethyl ketone, diethyl ketone, and 4-methoxy-4-methylpentanone, esters such as ethyl acetate, butyl acetate, ethyl lactate, butyl lactate, butyl benzoate, and benzyl benzoate, glycols such as ethylene glycol, propylene glycol, and butylene glycol, glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, and 3-methoxy-3-methylbutanol, and glycol ether acetates such as ethylene glycol monomethyl ether acetate and ethylene glycol monoethyl ether acetate. However, when mixing these organic solvents, the hydrophobic organic solvent with a boiling point of 200°C to 300°C must be blended in at a ratio of at least 70% by weight based on the total solvent mass to ensure adequate drying properties of the ink.

[0017] The resin used in the present invention is not particularly limited as long as it is soluble in the solvent, and examples thereof include phenolic resins, terpene phenolic resins, rosin resins, rosin-modified maleic acid resins, ketone resins, silicone resins, vinyl chloride resins, and fluororesins. Of these, weather-resistant resins are particularly preferred, such as hydrogenated rosin esters and polycondensates of acetophenone and glycerin. These resins may be used alone or in combination.

[0018] The colorant used in the present invention is not particularly limited as long as it is soluble or dispersible in the organic solvent, but weather resistance is preferred. Examples of organic pigments include azo pigments, phthalocyanine pigments, anthraquinone pigments, oxazine pigments, diketopyrrolopyrrole pigments, quinacridone pigments, threne pigments, isoindoline pigments, perylene pigments, condensed pigments, and condensed polycyclic pigments. Examples of inorganic pigments include metal oxides such as titanium oxide, iron oxide, and aluminum oxide, carbon black, mica, red iron oxide, ultramarine blue, verdigris, barium sulfate, zinc oxide, and aluminum powder. Examples of dyes include nigrosine pigments, azine pigments, monoazo pigments, disazo pigments, metal complex monoazo pigments, phthalocyanine pigments, anthraquinone pigments, and triarylmethane pigments. These colorants may be used alone or in combination.

[0019] In the present invention, silica, alumina, clay, talc, aluminum silicate, calcium carbonate, magnesium carbonate, etc. may be used as a dispersant as needed. These dispersants may be used alone or in combination of two or more kinds, as long as they do not affect the stability of the ink.

[0020] In addition, antioxidants such as dimethylhydroxybenzene, surfactants such as polyglycerol fatty acid esters, thickeners such as ethyl cellulose, etc. may be used as needed within the range in which they are compatible with the ink without adversely affecting it.

[0021] The oil-based ink composition of the present invention can be used in conventional writing implements, ink-penetrating stamps, vermilion ink pads, and ink pads, but is particularly suitable for stamps or marking pens. The stamp structure is not particularly limited, but due to the ink's tendency to dry after a certain period of time, a cartridge-type stamp is preferred, which allows for easy ink replacement. The material of the printing element to be set in the cartridge can be selected from conventional materials that can be impregnated with ink, including, but not limited to, rubbers such as natural rubber, acrylonitrile-butadiene rubber, styrene-butadiene rubber, and silicone rubber, and resins such as polyolefins, plastic elastomers, and vinyl chloride. In addition to the above, non-elastic materials such as metals, plastics, and glass can also be used.

[0022] The oil-based ink composition of the present invention is suitable for checking the loosening of fastening members such as bolts, etc. The marking device used here can be a conventionally known one. FIG. 1 shows an example of a marking device for fasteners such as bolts that uses the oil-based ink composition of the present invention; (a) is a perspective view, and (b) is a cross-sectional view taken along the line XX. This marking device includes a generally cylindrical housing 10 and a marking member 20 that is connected to the housing 10 and can swing inward and outward relative to the housing 10. A printing element 22 impregnated with the oil-based ink composition of the present invention is attached to the marking member 20. A holder 30 that is movable toward the bottom opening 11 of the housing 10 is attached to the housing 10 via an elastic member 31. The holder 30 includes a pressing portion 32 that can press the push-in lever 21 of the marking member 20. This configuration allows an operator to align the bottom opening 11 with a fastener such as a bolt and press the holder 30, thereby pressing the marking member 20 and performing marking.

[0023] A marking device using the oil-based ink composition of the present invention does not require an airtight mechanism, allowing for a high degree of freedom in design and allowing for a structure such as that shown in Figure 1. Note that the structure of a marking device that can use the oil-based ink composition of the present invention is not limited to that exemplified in Figure 1.

[0024] The oil-based ink composition of the present invention can be produced by blending the above-mentioned components and then mixing and stirring them with a stirrer. [Example]

[0025] Next, the present invention will be described in more detail with reference to examples and comparative examples.

[0026] The formulations of the examples and comparative examples are shown in Table 1. [Table 1] The phenolic resin in the table is YS Polystar TH130 (manufactured by Yasuhara Chemical Co., Ltd.), the rosin-modified maleic acid resin is Marquid No. 32 (manufactured by Arakawa Chemical Industries, Ltd.), the hydrogenated acid-modified rosin resin is KE-604 (manufactured by Arakawa Chemical Industries, Ltd.), and the polyvinyl butyral resin is S-Lec B BL-1 (manufactured by Sekisui Chemical Co., Ltd.).

[0027] After the inks of the Examples and Comparative Examples were impregnated into rubber stamps, the stamps were set in stamp cartridges and subjected to the following tests. (1) Imprint durability test: Two cartridges using the same ink were prepared. One was attached to a stamp as is and stamped on a metal plate to obtain imprint A. The other was stored face down in a room maintained at a temperature of 20°C and humidity of 65% for 6 hours, and then attached to a stamp and stamped on a metal plate to obtain imprint B. ◎: There was no difference between imprint A and imprint B 〇: The density of imprint B was lighter than imprint A, but imprint B could be visually confirmed. ×: Impression B could not be visually confirmed or was extremely faint (2) Imprint drying test: The cartridge was attached to a stamp, and the impression imprinted on a metal plate was stored for 24 hours in a room maintained at a temperature of 20°C and a humidity of 65%, after which the impression was rubbed 10 times with a cotton swab and the impression was confirmed. ◎: No misalignment or peeling was observed in the print ○: There was a small amount of misalignment or peeling in the print. ×: Significant misalignment or peeling occurred in the print (3) Water resistance test: The cartridge was attached to the stamp, and immediately after imprinting on a metal plate, the imprint was exposed to running water for 30 minutes to check for bleeding. ◎: No bleeding at all, no decrease in density of print 〇: A little bleeding was observed, but the density of the print was not significantly reduced. ×: Severe bleeding occurred and the density of the printed image was significantly reduced.

[0028] As is clear from the results in Table 1 above, the ink compositions of Examples 1 to 5, which fall within the scope of the present invention, were found to be significantly superior in terms of print durability, print drying properties, and water resistance compared to the ink compositions of Comparative Examples 1 to 6, which fall outside the scope of the present invention.

[0029] Looking at each example individually, it was found that Examples 1 to 5, which use 70% by weight or more of solvents with a boiling point in the range of 200°C to 300°C regardless of the resin, are excellent in both print durability and print drying properties, whereas Comparative Examples 1 and 2, which use a proportion of less than 70% by weight, and Comparative Examples 3 and 4, which use only solvents with a boiling point below 200°C, are inferior in print durability, and Comparative Example 5, which uses only solvents with a boiling point above 300°C, is inferior in print drying properties.

[0030] Furthermore, it was found that Examples 1 to 5, which used hydrophobic solvents, had very good water resistance, whereas Comparative Example 6, which used only a solvent miscible with water, had poor water resistance.

[0031] The present invention has been described above in relation to the embodiment that is considered to be the most practical and preferable at present. However, the present invention is not limited to the embodiment disclosed in this specification, and can be modified as appropriate within the scope of the claims and the gist or idea of the invention that can be read from the specification as a whole, and ink compositions with such modifications should also be understood to be included within the technical scope. [Explanation of symbols]

[0032] 10. Cabinet 20 Marking material 21 Push-in lever 22 Printing 30 Holder 31 Elastic Body 32 Pressing section TIFF2025117749000002.tif102169

Claims

1. An oil-based ink composition comprising at least a hydrophobic organic solvent having a boiling point of 200°C to 300°C, a resin soluble in said hydrophobic organic solvent, and a colorant, wherein the proportion of said hydrophobic organic solvent is at least 70% by weight based on the total mass of the solvent.

2. 2. The oil-based ink composition according to claim 1, wherein the resin and the colorant are weather resistant.

3. 3. The oil-based ink composition according to claim 1, wherein the oil-based ink is for use in a stamp or a marking pen.

4. 3. The oil-based ink composition according to claim 1, wherein the oil-based ink is used to check for loosening of fastening members.

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