Ink composition for oil-based marking pens

Abstract

To provide an ink composition for an oily marking pen excellent in writing property on an oil film, and excellent in removable property by an alkali.SOLUTION: The ink composition for an oily marking pen includes: a solvent constituent; a resin constituent; and a dye constituent. The solvent constituent at least includes 2-4 C alcohol. The resin constituent includes an alkali-soluble resin. The dye constituent is composed of only a basic dye.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an ink composition for an oil-based marking pen.

Background Art

[0002] For metal processing materials (such as metal formed products) to be painted, oil is applied to the surface for the purpose of preventing rust. In the areas where an oil film is formed, it is difficult for a coating film to adhere. Therefore, prior to painting, the oil film formed on the surface of the metal processing material is removed by degreasing treatment with an alkali.

[0003] In addition, information such as lot numbers may be marked on metal processing materials to be painted. For marking, an opaque oil-based or water-based marking pen or the like is used from the viewpoint of obtaining high visibility.

[0004] Generally, compared with paper or the like, the writing property and fixing property of a marking pen on an adherend surface of metal or plastic are low. Therefore, there is a demand for an ink composition for a marking pen that can provide high writing property or fixing property even for such adherend surfaces. For example, Patent Document 1 proposes an oil-based ink for a marking pen containing at least a pigment, an organic solvent, a terpene phenol resin, and fine powder silicon dioxide.

[0005] On the other hand, technologies focusing on suppressing discoloration of ink are also known. For example, Patent Document 2 proposes an alcohol-based ink containing a dye represented by C.I. 42660 and / or C.I. 42655, at least one solvent selected from ethers composed of alcohols having 2 to 4 carbon atoms, glycols having 2 to 3 carbon atoms, and alcohols having 1 to 3 carbon atoms, and a resin soluble in the solvent.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] Since the oil film formed on the surface of the uncoated metal working material is extremely thin, it is impossible to immediately determine whether the metal working material is before or after degreasing treatment.

[0008] On the other hand, from the viewpoint of ensuring high adhesiveness to the adherend surface, the ink composition for an oil-based marking pen contains an oil-soluble resin, and the ink composition for an aqueous marking pen contains a resin emulsion. When the adhesiveness of the marking ink composition is increased, the writing property or fixing property to the adherend surface can be enhanced. However, resin components such as oil-soluble resins or resin emulsions are difficult to remove by alkaline degreasing treatment. Therefore, separately from the degreasing treatment, the film formed by marking is removed by wiping with a solvent.

[0009] If the film formed by marking can be removed by alkaline degreasing treatment, the oil film and the film formed by marking can be removed in one step, which is simple and cost-effective. When marking on an oil film, since high adhesiveness is required due to the resin component, it becomes even more difficult to remove the film formed by marking by alkaline degreasing treatment.

Means for Solving the Problems

[0010] One aspect of the present invention relates to an ink composition for an oil-based marking pen, which contains a solvent component, a resin component, and a dye component, the solvent component contains at least an alcohol having 2 to 4 carbon atoms, the resin component contains an alkali-soluble resin, and the dye component consists only of a basic dye.

Effects of the Invention

[0011] An ink composition for an oil-based marking pen can be provided that has excellent writing properties on an oil film and excellent removability with an alkali.

Embodiments for Carrying Out the Invention

[0012] [Ink Composition for Oil-Based Marking Pen] The ink composition for an oil-based marking pen according to one aspect of the present invention includes a solvent component, a resin component, and a dye component. The solvent component includes at least an alcohol having 2 to 4 carbon atoms. The resin component includes an alkali-soluble resin. The dye component consists only of a basic dye.

[0013] By using an alkali-soluble resin, high adhesiveness of the ink composition for an oil-based marking pen to the adherend surface can be ensured, so excellent writing properties can be ensured. Thereby, writing can be performed with high writing properties even on the adherend surface of a metal or an oil film. Also, high fixability of the ink composition for an oil-based marking pen can be ensured. The amount of the dye component contained in the ink composition for an oil-based marking pen is usually less than that of the resin component. However, even when only an alkali-soluble resin is used as the resin component, it is difficult to ensure high alkali washability when the dye component contains a dye other than a basic dye. In the present invention, by using an alkali-soluble resin and using only a basic dye as the dye component, the film formed by the marking of the ink composition for an oil-based marking pen can be easily removed with an alkali, and high alkali washability can be ensured. Therefore, even when marking a metal processing material subjected to a degreasing treatment with an alkali, it can be easily removed by the degreasing treatment with an alkali. The film can be easily removed even by using an aqueous alkali solution having a relatively low concentration such as 10% by mass or less or 5% by mass or less.

[0014] As described above, since the ink composition for an oil-based marking pen of the present invention is excellent in removability with an alkali, it is suitable for use in applications where marking is performed on a metal processing material subjected to a degreasing treatment with an alkali.

[0015] If the adhesiveness of the resin component is high, even if the coating formed by marking can be removed by alkali degreasing treatment, the components of the coating may reattach to the adherend surface and cause unintended coloring. From the perspective of preventing such a situation, the dye component may be composed only of methine-based basic dyes. Generally, dyes function as colorants due to the presence of a conjugated system contained in the molecule. Methine-based basic dyes have a structure in which methine groups are linked as a conjugated system. Unlike dyes having only an aromatic ring as a conjugated system, when methine-based basic dyes come into contact with alkali, the conjugated bonds contained in the molecule are cleaved and they become colorless. Therefore, by using a dye component consisting only of methine-based basic dyes, an ink composition for an oil-based marking pen with excellent decolorability by alkali can be obtained. As a result, when a coating is formed by marking on a metal processing material to be subjected to a coating process, when the coating is removed by alkali degreasing treatment, even if the constituent components of the coating reattach to the metal processing material, they are in a decolorized state. Therefore, it is possible to easily determine that the alkali degreasing treatment of the metal processing material has been completed. Also, even when the dye component reattaches to the metal processing material, it is in a state of being decomposed by alkali. Therefore, even if the dye component bleeds to the surface of the coating film when the metal processing material is subjected to coating, it is colorless and does not affect the coating film. Also, it can be easily decolorized even when using an alkaline aqueous solution with a relatively low concentration such as 10% by mass or less or 5% by mass or less. When the dye component contains dyes other than methine-based basic dyes, it does not decolorize by alkali, so it is necessary to remove the dye component remaining on the surface of the metal processing material by wiping or the like after the degreasing treatment. If the metal processing material is subjected to a coating process without removing the dye component remaining on the surface of the metal processing material (that is, a dye component that does not decolorize by alkali), it bleeds to the surface of the coating film. Therefore, it is necessary to remove all of the coating film and repaint. Therefore, in order to ensure the alkali decolorability of the ink composition for an oil-based marking pen, it is preferable to use a dye component consisting only of methine-based basic dyes. By using a dye component consisting only of methine-based basic dyes, it becomes easier to visually determine that the alkali degreasing treatment of the metal processing material has been completed.

[0016] In addition, in the ink composition for an oil-based marking pen, since a volatile organic solvent is usually used, when the cap of the oil-based marking pen is removed and the pen tip is exposed, the drying of the pen tip tends to progress. Therefore, with an oil-based marking pen, when writing is done after leaving the pen tip exposed for a long time, streaks are likely to occur in the handwriting. That is, it is difficult to ensure high cap-off performance. In a working environment where marking is done on an unpainted metal workpiece, the operation of opening and closing the cap of the oil-based marking pen each time writing is done is cumbersome. Therefore, even when the cap is removed and left for a while, high cap-off performance is required such that the pen tip does not dry and writing can be done. On the other hand, for the ink composition for an oil-based marking pen, high fixability to the adherend surface is required. However, there is a trade-off relationship between the cap-off performance and the fixability of the ink composition for an oil-based marking pen, and it is difficult to achieve both high fixability and excellent cap-off performance.

[0017] When the ink composition for an oil-based marking pen of the present invention further contains a sucrose fatty acid ester component (preferably further a fatty acid glyceride component), excellent cap-off performance can be ensured while ensuring high fixability.

[0018] In this specification, the case where streaks are suppressed when writing is done after leaving the pen tip of the oil-based marking pen exposed to the atmosphere is sometimes expressed as excellent cap-off performance or high cap-off performance. Low cap-off performance or deteriorated cap-off performance means that streaks are relatively likely to occur when writing is done after leaving the pen tip exposed to the atmosphere. The cap-off performance in this specification is the cap-off performance under a general atmospheric environment (for example, an environment of 20 to 25°C and a relative humidity of 50 to 65%).

[0019] Hereinafter, the ink composition for an oil-based marking pen of the present invention will be described in more detail.

[0020] (Solvent component) The solvent component contains at least an alcohol having 2 to 4 carbon atoms (hereinafter sometimes referred to as the first solvent). By the solvent component containing the first solvent, excellent color developability can be ensured, and even when using the resin with high adhesiveness, it can be easily dissolved, and an ink composition for a low-viscosity oil-based marking pen can be obtained. The solvent component may contain a second solvent other than the first solvent.

[0021] (The first solvent) Specifically, the first solvent is an aliphatic alcohol. The aliphatic alcohol may be a linear alcohol or a branched-chain alcohol. As the first solvent, a monohydric alcohol having one hydroxy group is preferable.

[0022] Examples of the monohydric alcohol include ethanol, n-propyl alcohol, iso-propyl alcohol, n-butyl alcohol, iso-butyl alcohol, sec-butyl alcohol, and t-butyl alcohol.

[0023] The number of carbon atoms of the first solvent is 2 to 4, and preferably 2 or 3.

[0024] The solvent component may contain one kind of the first solvent or two or more kinds of the first solvent. The solvent component preferably contains at least a first solvent having 2 or 3 carbon atoms.

[0025] The ratio of the first solvent in the solvent component is, for example, 40% by mass or more. From the viewpoint of ensuring higher color development property and suppressing the viscosity of the ink composition for oil-based marking pens to a lower level, the ratio of the first solvent is preferably 50% by mass or more or 55% by mass or more, more preferably 70% by mass or more or 75% by mass or more, and may be 80% by mass or more. When the ratio of the first solvent is within such a range, higher color development property can be ensured, higher writing property can be ensured, and bleeding of the handwriting can also be suppressed. The ratio of the first solvent in the solvent component may be 100% by mass or less, may be 95% by mass or less or 90% by mass or less. These lower limit values and upper limit values can be arbitrarily combined. The ratio of the first solvent having 2 to 3 carbon atoms may be adjusted to such a range.

[0026] (Second solvent) Examples of the second solvent include alcohols (including phenolic compounds) excluding the first solvent, glycol ethers, etc. As the alcohol, a monohydric alcohol is preferable. The solvent may contain one kind of the second solvent or may contain two or more kinds of the second solvents. From the viewpoint of ensuring high compatibility with the first solvent and easily adjusting the drying rate, it is preferable to use at least glycol ether as the second solvent.

[0027] Examples of the glycol ether include monoethers or diethers of glycol compounds, and monoether monoesters of glycol compounds. Examples of the ether include alkyl ethers, aryl ethers, aralkyl ethers, etc.

[0028] Examples of the glycol compound include polyhydroxyalkanes and polyalkylene glycols. Examples of the polyhydroxyalkane include alkylene glycols (ethylene glycol, propylene glycol, propane diol, butane diol, hexane diol, octane diol, etc.), trimethylolpropane, pentaerythritol, etc. The number of carbon atoms of the polyhydroxyalkane is, for example, 1 to 10, and may be 2 to 6 or 2 to 4.

[0029] Examples of the polyalkylene glycol include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, etc. The number of carbon atoms of the oxyalkylene unit contained in the polyalkylene glycol is, for example, 2 to 4, and may be 2 or 3. In the polyalkylene glycol, the number of repetitions of the oxyalkylene unit is, for example, 2 to 10, and may be 2 to 6 or 2 to 4.

[0030] Among the glycol ethers, from the viewpoint of being easily soluble in other components and easily stabilizing the physical properties of the ink composition for the oil-based marking pen, monoethers are preferred. Further, from the viewpoints of having less odor, etc. and having high compatibility with the first solvent, alkyl ethers and monoalkyl ether monoesters are preferred.

[0031] Examples of the alkyl constituting the alkyl ether include methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, t-butyl, n-pentyl, n-hexyl, etc. The number of carbon atoms of the alkyl is, for example, 1 to 10, and may be 1 to 6 or 1 to 4.

[0032] Examples of the acyl group constituting the ester moiety of the monoalkyl ether monoester include aliphatic acyl groups (such as acetyl and propionyl groups), benzoyl group, etc. Among them, aliphatic acyl groups having 2 to 4 carbon atoms (particularly, acetyl group) are preferred.

[0033] Specific examples of the alkyl ether include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol mononormal butyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol mononormal butyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, and the like. Specific examples of the monoalkyl ether monoester include, for example, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monopropyl ether acetate, diethylene glycol monobutyl ether, and the like. Among them, at least one selected from the group consisting of ethylene glycol mononormal butyl ether, propylene glycol monomethyl ether, propylene glycol mononormal butyl ether, and diethylene glycol monomethyl ether is preferable. It is also preferable to use at least propylene glycol monomethyl ether as the second solvent.

[0034] Only glycol ether may be used as the second solvent, or glycol ether may be used in combination with other second solvents. The ratio of glycol ether in the solvent component is preferably 5% by mass or more or 10% by mass or more. Also, the ratio of glycol ether is preferably 30% by mass or less, and may be 25% by mass or less or 20% by mass or less. When the ratio of glycol ether is within such a range, it is easy to lower the viscosity of the ink composition for an oil-based marking pen, and it is easy to achieve a balance between appropriate quick-drying property and suppression of drying at the pen tip. These lower limit values and upper limit values can be arbitrarily combined.

[0035] (Resin component) The resin component contains an alkali-soluble resin. The resin component may further contain a polyvinylamide-based resin. From the viewpoint of ensuring high removability by an alkali, it is desirable that the resin component consists of only the alkali-soluble resin or only the alkali-soluble resin and the polyvinylamide-based resin. Since the resin component contains at least the alkali-soluble resin, high water resistance of the coating by marking can be ensured.

[0036] In this specification, the alkali-soluble resin means a resin containing an anionic monomer unit and having an acid value of 30 KOH·mg / g or more.

[0037] The alkali-soluble resin may be a homopolymer of a monomer unit having an anionic group (the first monomer unit), or may be a copolymer containing the first monomer unit and another monomer unit (the second monomer unit). The resin component may contain one kind of alkali-soluble resin or may contain two or more kinds in combination. The anionic group of the alkali-soluble resin may be contained in the form of an anion in the oil-based marking pen ink composition, or may be contained in a form interacting with a methine-based basic dye.

[0038] Examples of the anionic group include a carboxy group, an acid anhydride group, a sulfonic acid group, a phosphonic acid group, and a phosphinic acid group. The alkali-soluble resin may have one kind of anionic group or may have two or more kinds of anionic groups. Among the anionic groups, a carboxy group, an acid anhydride group, and a sulfonic acid group are preferable.

[0039] Among monomers (the first monomer) having an anionic group corresponding to the first monomer unit, examples of the monomer having a carboxy group include acrylic acid, methacrylic acid, maleic acid, fumaric acid, and the like. Examples of the monomer having an acid anhydride group include maleic anhydride. Examples of the monomer having a sulfonic acid group include vinyl sulfonic acid, styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, and the like. These are merely specific examples, and the first monomer is not limited to these specific examples. The alkali-soluble resin may contain one kind of the first monomer unit or may contain a combination of two or more kinds.

[0040] As the monomer (the second monomer) corresponding to the second monomer unit, it may be any monomer that can polymerize with the first monomer. Examples of the second monomer include acrylic monomers, vinyl monomers, olefins, vinyl cyanide (such as acrylonitrile, methacrylonitrile), and the like. The alkali-soluble resin may contain one kind of the second monomer unit or may contain two or more kinds.

[0041] Examples of acrylic monomers include acrylic esters, methacrylic esters, acrylamides, methacrylamides, etc. The acrylic monomer may have one (meth)acryloyl group in one molecule, or may have two or more (meth)acryloyl groups. Examples of acrylic esters and methacrylic esters include alkyl (meth)acrylates, hydroxyalkyl (meth)acrylates, cycloalkyl (meth)acrylates, cycloalkenyl (meth)acrylates, aryl (meth)acrylates, aralkyl (meth)acrylates, etc. The number of carbon atoms of the alkyl constituting these esters is, for example, 1 or more and 20 or less, and may be 1 or more and 10 or less, or 1 or more and 6 or less. The number of carbon atoms of cycloalkyl or cycloalkenyl is, for example, 4 or more and 8 or less, and may be 5 or more and 8 or less. The number of carbon atoms of aryl is, for example, 6 or more and 20 or less, and may be 6 or more and 14 or less, or 6 or more and 10 or less. The number of carbon atoms of aralkyl is, for example, 7 or more and 22 or less, and may be 7 or more and 16 or less, or 7 or more and 12 or less. Here, the acryloyl group and the methacryloyl group are collectively referred to as the (meth)acryloyl group. Also, acrylic esters and methacrylic esters are collectively referred to as (meth)acrylates. The alkali-soluble resin may contain one kind of acrylic monomer unit, or may contain two or more kinds of acrylic monomer units.

[0042] Specific examples of (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, cyclohexyl (meth)acrylate, cyclohexenyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, phenethyl (meth)acrylate, etc. These are merely examples, and (meth)acrylate is not limited to these specific examples.

[0043] Examples of vinyl monomers include aromatic vinyls (such as styrene, vinyltoluene, divinylbenzene, etc.), vinyl halides (such as vinyl chloride, etc.), vinyl esters (such as vinyl acetate, etc.), vinyl ethers (such as alkyl vinyl ethers (propyl vinyl ether, butyl vinyl ether, etc.), etc.), vinyl ketones, etc. The vinyl monomer may have one vinyl group or may have two or more vinyl groups. The vinyl monomer includes those having a substituent. Examples of the substituent include a hydroxy group, an alkoxy group, a halogen atom, etc. Examples of the substituent on the aromatic ring also include an alkyl group, a hydroxyalkyl group, etc. However, the substituent is not limited to these. The alkali-soluble resin may contain one kind of vinyl monomer unit or may contain two or more kinds of vinyl monomer units.

[0044] Examples of olefins include, for example, α-olefins. The olefin may be either linear or cyclic. Specific examples of linear olefins include ethylene, propylene, 1-butene, 4-methyl-1-pentene. The number of carbon atoms of the linear olefin is, for example, 2 or more and 16 or less, and may be 2 or more and 12 or less, or 2 or more and 10 or less. Specific examples of cyclic olefins include norbornene, dicyclopentadiene. However, these are merely examples, and the olefin is not limited to these specific examples. Note that the olefin includes those having a substituent (such as a hydroxy group, an alkoxy group, an acyl group, a halogen atom, etc.). The substituent of the cyclic olefin further includes an alkyl group, a hydroxyalkyl group, etc. However, the substituent is not limited to these. The alkali-soluble resin may contain one kind of olefin unit or may contain two or more kinds of olefin units.

[0045] The alkali-soluble resin preferably contains at least an aromatic vinyl unit (especially, a styrene unit, etc.) as the second monomer unit, and may contain an aromatic vinyl unit and a (meth)acrylate unit.

[0046] The acid value of the alkali-soluble resin may be 30 KOH·mg / g or more, preferably 40 KOH·mg / g or more, and more preferably 50 KOH·mg / g or more or 60 KOH·mg / g or more. When the alkali-soluble resin has such an acid value, the film formed by the ink composition for an oil-based marking pen can be more easily removed by an alkali. The acid value of the alkali-soluble resin may be 300 KOH·mg / g or less.

[0047] Incidentally, the acid value of the resin can be measured in accordance with "JIS K 2501-2003 Petroleum products and lubricating oils - Test method for neutralization value". More specifically, the acid value of the resin can be determined by the following procedure. First, a predetermined amount of the resin is dissolved in a solvent obtained by mixing xylene and dimethylformamide at a volume ratio of 1:1 to prepare a titration sample. For the titration sample, potentiometric titration is performed using an ethanol solution containing potassium hydroxide at a concentration of 0.1 mol / L to obtain a titration curve. Using the inflection point on the titration curve as the end point, the acid value is calculated from the concentration of the resin in the titration sample, the titration volume of the ethanol solution up to the end point, and the concentration of potassium hydroxide.

[0048] The weight average molecular weight (Mw) of the alkali-soluble resin is, for example, 1,000 or more and 30,000 or less. When Mw is in such a range, while ensuring high removability of the film by an alkali, higher writing properties and fixability on the oil film can be ensured, and high water resistance of the film can be ensured. From the viewpoint of further enhancing the removability of the film by an alkali, Mw is preferably 1,000 or more and 20,000 or less.

[0049] In this specification, the weight average molecular weight (Mw) is measured by gel permeation chromatography (GPC) using standard polystyrene. As the standard polystyrene, for example, those with Mw = 1.01×10 3 , 3.12×10 3 , 5.43×10 3 , 9.49×10 3 , or 1.37×10 4 are used.

[0050] Examples of the alkali-soluble resin include the Joncryl series manufactured by BASF, the Hiros series manufactured by Starlight PMC, and the ARUFON series manufactured by Toagosei Co., Ltd. Specific examples of the alkali-soluble resin include Joncryl 67, 678, 680, 682, 683, 690, 52, 57, 60, 61, 62, 63, 70, HPD-962, 501, 354, 6610, Hiros X-1, X-310, RS-1191, VS-1047, YS-1274, X-1, ARUFON UC-3080, UC-3910, UC-3920, UF-5022, but are not limited thereto.

[0051] The content of the alkali-soluble resin in the ink composition for an oil-based marking pen is preferably 30% by mass or less, more preferably 25% by mass or less. When the content of the alkali-soluble resin is in such a range, the film formed by marking can be removed more easily with alkali. The content of the alkali-soluble resin is, for example, 1% by mass or more. From the viewpoint of ensuring high writing performance on the oil film, the content of the alkali-soluble resin is preferably 3% by mass or more, more preferably 5% by mass or more. These upper and lower limit values can be arbitrarily combined.

[0052] Examples of the polyvinylamide-based resin include polymers obtained by polymerizing a monomer having a vinyl group and an amide bond and, if necessary, other copolymerizable monomers. The polyvinylamide-based resin preferably contains vinylpyrrolidone as a monomer unit. The polyvinylamide-based resin preferably contains at least polyvinylpyrrolidone. When the resin component contains a polyvinylamide-based resin, excellent color development can be obtained. In addition, high sensitivity of decolorization can be ensured, and high color development can be maintained for a long time.

[0053] The Mw of the polyvinylamide-based resin is, for example, 3000 or more and 100000 or less, may be 5000 or more and 70000 or less, may be 8000 or more and 50000 or less, or may be 10000 or more and 40000 or less. When the Mw is in such a range, while ensuring high color development properties and high removability of the coating by alkali due to marking, the fixing property and water resistance can be further enhanced.

[0054] The content of the polyvinylamide-based resin in the ink composition for an oil-based marking pen is, for example, 0.01% by mass or more. From the viewpoint of ensuring higher color development properties and higher sensitivity of decolorization, and being likely to maintain high color development properties for a long time, the content of the polyvinylamide-based resin is preferably 0.05% by mass or more, more preferably 0.1% by mass or more or 1% by mass or more. The content of the polyvinylamide-based resin is, for example, 10% by mass or less. From the viewpoint of ensuring higher water resistance, the content of the polyvinylamide-based resin is preferably 5% by mass or less, more preferably 3% by mass or less or 2% by mass or less. These lower limit values and upper limit values can be arbitrarily combined.

[0055] From the viewpoint of easily ensuring high water resistance, high color development properties, and high sensitivity of decolorization, it is preferable that the resin component contains both an alkali-soluble resin and a polyvinylamide-based resin. In this case, by setting the content of the polyvinylamide-based resin in the ink composition for an oil-based marking pen within the above range, the effect of using the alkali-soluble resin and the polyvinylamide-based resin in combination can be further enhanced.

[0056] (Dye component) In this specification, that the dye component consists only of a basic dye means that the ink composition substantially does not contain dyes other than the basic dye. Also, in this specification, that the ink composition substantially does not contain dyes other than the basic dye means the case where the amount of dyes other than the basic dye is 5 parts by mass or less (preferably 1 part by mass or less) with respect to 100 parts by mass of the resin component. The dyes other than the basic dye in the ink composition or its coating film may be below the detection limit.

[0057] Examples of basic dyes include, for example, methine-based basic dyes, diarylmethane-based basic dyes, triarylmethane-based basic dyes, azo-based basic dyes, anthraquinone-based basic dyes, and nitrogen-containing heterocyclic compounds. The dye component may contain one kind of basic dye or may contain a combination of two or more kinds.

[0058] When the dye component contains only a methine-based basic dye, excellent decolorability of the ink composition for an oil-based marking pen can be ensured by cleavage of the conjugated bond in the molecule upon contact with an alkali.

[0059] A methine-based basic dye is a basic dye that contains a structure in which methine groups are linked as a conjugated system and the conjugated bond is cleaved upon contact with an alkali.

[0060] Specific examples of methine-based basic dyes include, but are not limited to, Basic Red 12 to 15, 27, 35, 37, 45, 48, 49, 52, 53, 66, 68, Basic Yellow 11 to 14, 21 to 24, 28, 29, 33, 35, 40, 43 to 45, 48, 49, 51 to 53, Basic Violet 7, 15, 16, 20, 21, 27, 39, 40, Basic Blue 62, 63, Basic Orange 27, 42, 44, 46 in the Color Index. From the viewpoint of high decoloring sensitivity, Basic Red 12 to 15, 37, Basic Yellow 11, 13, and Basic Violet 15 are preferred.

[0061] The dye component may contain one kind of methine-based basic dye or may contain two or more kinds of methine-based basic dyes.

[0062] Regarding basic dyes other than methine-based basic dyes, specific examples of triarylmethane-based basic dyes include Basic Blue 5, 7, 26 and Basic Green 1 of the Color Index. Specific examples of azo-based basic dyes include Basic Red 18, Basic Yellow 36, and Basic Blue 54, 65, 66, 67 of the Color Index.

[0063] The content of the basic dye in the ink composition for an oil-based marking pen is, for example, 0.1% by mass or more, preferably 0.2% by mass or more, and may be 0.5% by mass or more or 1% by mass or more. When the content of the basic dye is in such a range, in addition to obtaining higher color development and higher sensitivity of color development, high color development can be maintained for a long time. The content of the methine-based dye may also be in such a range. The content of the basic dye is, for example, 10% by mass or less, preferably 8% by mass or less, and may be 7% by mass or less or 6% by mass or less. When the content of the basic dye is in such a range, the adhesion of the film formed by marking is enhanced and the water resistance can be improved. When the content of the methine-based basic dye is in such a range, it can be decolorized more uniformly. These lower limit values and upper limit values can be arbitrarily combined.

[0064] (Pigment component) The ink composition for an oil-based marking pen may contain a pigment component as needed. Among pigments, there are pigments colored with dyes, but as the pigment component, those other than such pigments are used. Examples of the pigment component include coloring pigments, extender pigments, and functional pigments. Examples of the pigment include inorganic pigments, organic pigments, and metal powder pigments. Also, pearl pigments, white resin particles, etc. may be used as the pigment. Further, a powder containing these pigments and resin may be used as the pigment component. As the pigment component, one of these pigments may be used, or two or more kinds may be used in combination.

[0065] From the viewpoint of ensuring a higher hiding effect for the base, the pigment component preferably contains at least a white pigment (the first pigment). In addition to the first pigment, the pigment may further contain a pigment other than the white pigment (the second pigment).

[0066] Examples of the first pigment include titanium oxide (such as Pigment White 6), zinc oxide, barium sulfate, calcium carbonate, aluminum hydroxide, talc, and white resin particles. The first pigment may be used alone or in combination of two or more. From the viewpoint of easily ensuring a higher hiding property for the base, it is preferable to use at least titanium oxide, and titanium oxide may be used in combination with other white pigments. In addition, the particles of the first pigment may be coated with at least one of an inorganic component (for example, metal oxides such as alumina, zirconia, and / or titania) and an organic component.

[0067] Specific examples of the white resin particles include Muticle PP240D (styrene resin), Muticle PP110C, PP2000TX (styrene-acrylic copolymer) manufactured by Mitsui Chemicals, Inc., Rohm and Haas's Rohapek Ultra E, SE, Rohapek HP-1055, SN-1055, HP-91, OP-84J, etc. However, these are merely examples, and the white resin particles are not limited to these specific examples.

[0068] Examples of the second pigment include colored pigments, black pigments, colored resin particles, etc. Each of the colored pigment and the black pigment may be an inorganic pigment (for example, carbon black) or an organic pigment. Examples of the organic pigment include phthalocyanine-based pigments, threne-based pigments, azo-based pigments, quinacridone-based pigments, anthraquinone-based pigments, dioxazine-based pigments, indigo-based pigments, thioindigo-based pigments, perinone-based pigments, perylene-based pigments, indolenone-based pigments, azomethine-based pigments, etc. These pigments may be used as a dispersion containing these pigments (pigment dispersion). Also, a commercially available pigment dispersion may be used as the second pigment.

[0069] The ratio of the first pigment in the pigment component is, for example, 30% by mass or more, and may be 50% by mass or more, or 60% by mass or more. When the ratio of the white pigment is within such a range, higher hiding power can be ensured. The upper limit of the ratio of the white pigment can be determined according to the desired color of the ink composition, and is, for example, 100% by mass or less. The ratio of titanium oxide contained in the entire content included in the ink composition may satisfy such a range.

[0070] A white inorganic pigment (such as titanium oxide) and resin particles (such as white resin particles) may be combined. By using a white inorganic pigment, higher hiding power of the substrate can be ensured. In addition to the white inorganic pigment and resin particles, pigments other than these may be used in combination.

[0071] When the white inorganic pigment and resin particles are used in combination, the amount of the resin particles (dry solid content) is, for example, 1 part by mass or more and 50 parts by mass or less, and may be 5 parts by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the white inorganic pigment (dry solid content).

[0072] The content of the pigment component in the ink composition for an oil-based marking pen is, for example, 0.1% by mass or more, and may be 1% by mass or more, or 5% by mass or more. The content of the pigment component is, for example, 15% by mass or less, and may be 10% by mass or less. These lower limit values and upper limit values can be arbitrarily combined.

[0073] (Sucrose fatty acid ester component) When the ink composition for an oil-based marking pen contains a sucrose fatty acid ester component, even if the oil-based marking pen is left with the cap removed, a film is formed on the surface of the pen tip. Therefore, the volatilization of the solvent can be reduced, and when starting writing, this film peels off and the ink composition for the oil-based marking pen oozes out onto the adherend surface, effectively reducing the occurrence of streaks in the handwriting. Thus, the cap-off property can be enhanced.

[0074] Examples of the sucrose fatty acid ester component include sucrose fatty acid esters. The sucrose fatty acid ester may be either a monoester or a polyester. The polyesters include diesters, triesters, tetraesters, pentaesters, hexaesters, heptaesters, and octaesters. The polyester may be an ester of sucrose and one kind of fatty acid, or an ester of sucrose and two or more kinds of fatty acids.

[0075] The sucrose fatty acid ester component may contain one kind of sucrose fatty acid ester, or may contain two or more kinds of sucrose fatty acid esters.

[0076] The sucrose fatty acid ester component may contain, for example, a monoester and a polyester. From the viewpoint of ensuring higher dispersion stability in the ink composition for an oil-based marking pen, it is preferable that the sucrose fatty acid ester component contains at least a polyester (particularly, a diester and / or a triester).

[0077] Examples of the fatty acid constituting the sucrose fatty acid ester include saturated fatty acids and unsaturated fatty acids. Examples of the fatty acid include monovalent aliphatic carboxylic acids having 2 or more carbon atoms. The number of carbon atoms of the aliphatic carboxylic acid is, for example, 2 to 30, may be 2 to 26 or 2 to 22, and may also be 5 to 22 or 12 to 20. The number of carbon-carbon unsaturated bonds contained in the unsaturated fatty acid is, for example, 1 to 3, and may be 1 or 2. The fatty acids also include those having one or more substituents. Examples of the substituent include a hydroxy group, an alkoxy group, a halogen atom, and the like.

[0078] Specific examples of the fatty acid include butanoic acid, pentanoic acid, hexanoic acid, octanoic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, behenic acid, and montanic acid.

[0079] From the perspective of ensuring higher dispersion stability in the ink composition for an oil-based marking pen, the HLB (Hydrophilic-Lipophilic Balance) of the sucrose fatty acid ester is preferably 8 or less, and may be 1 to 8. The sucrose fatty acid ester having such an HLB contains a large amount of polyester.

[0080] The content of the sucrose fatty acid ester in the ink composition for an oil-based marking pen may be 0.05% by mass or more, and may also be 0.1% by mass or more. Even if the content of the sucrose fatty acid ester is very small, by combining it with the fatty acid glyceride component, high cap-off performance can be ensured. From the perspective of ensuring higher dispersion stability in the ink composition for an oil-based marking pen, the content of the sucrose fatty acid ester component is preferably 1% by mass or less, and may be 0.5% by mass or less.

[0081] (Fatty acid glyceride component) When the ink composition for an oil-based marking pen contains a fatty acid glyceride component in addition to the sucrose fatty acid ester component, when the oil-based marking pen is left with the cap removed, a suitable composite film is formed on the surface of the pen tip. Therefore, the volatilization of the solvent can be reduced, and since this film peels off easily when starting to write, the cap-off performance can be further enhanced.

[0082] Examples of the fatty acid glyceride component include fatty acid glycerides. Examples of the fatty acid glyceride include at least one selected from the group consisting of fatty acid monoglycerides, fatty acid diglycerides, and fatty acid triglycerides. Among the three hydroxy groups of glycerin, the monoester in which one hydroxy group is esterified with a fatty acid is a fatty acid monoglyceride, and the diester in which each of the two hydroxy groups is esterified with a fatty acid is a fatty acid diglyceride. Fatty acid triglyceride is a triester in which the three hydroxy groups of glycerin are each esterified with a fatty acid.

[0083] As the fatty acid constituting each ester, an aliphatic carboxylic acid having 4 to 30 carbon atoms is preferable. The number of carbon atoms of the aliphatic carboxylic acid may be 10 to 30, may be 10 to 22, or may be 12 to 18. The fatty acid may be a polyvalent fatty acid, but a monovalent fatty acid is preferable. The fatty acid may be either a saturated fatty acid or an unsaturated fatty acid. Regarding the fatty acid, the description and examples of the sucrose fatty acid ester component can be referred to.

[0084] Each of the fatty acid diglyceride and the fatty acid triglyceride may be an ester of glycerin and one kind of fatty acid, or may be an ester of glycerin and two or more kinds of fatty acids.

[0085] The fatty acid glyceride component may contain one kind of fatty acid glyceride, or may contain two or more kinds of fatty acid glycerides.

[0086] From the viewpoint of ensuring higher dispersion stability in the ink composition for an oil-based marking pen, the fatty acid glyceride component preferably contains at least one selected from the group consisting of fatty acid diglyceride and fatty acid triglyceride, and more preferably contains at least fatty acid triglyceride. From the same viewpoint, in each of the fatty acid diglyceride and the fatty acid triglyceride, it is preferable to use a fatty acid glyceride component containing at least a fatty acid glyceride in which at least one of the three hydroxy groups of glycerin is esterified with a fatty acid having 10 to 30 carbon atoms (preferably 10 to 22 or 12 to 18). Examples of the fatty acid glyceride include CA340.2 and CA210.2 manufactured by MULTICHEM.

[0087] The content of the fatty acid glyceride component in the ink composition for an oil-based marking pen is, for example, 0.3% by mass or more, preferably 0.5% by mass or more. When the content of the fatty acid glyceride component is within such a range, higher cap-off property can be ensured. From the viewpoint of suppressing the precipitation of the fatty acid glyceride component in the ink composition for an oil-based marking pen and making it easier to fill the ink container or the refill with the ink for an oil-based marking pen, the content of the fatty acid glyceride component is preferably 2.5% by mass or less, more preferably 2% by mass or less.

[0088] (Silicone oil) The ink composition for an oil-based marking pen may contain silicone oil. In this case, while the solvent volatilizes from the coating film of the ink composition for an oil-based marking pen formed by writing on the adherend surface and the viscosity of the coating film increases, the silicone oil migrates to the surface of the coating film. As a result, the surface of the dried coating film is in a state where the silicone oil has bled and acts as a slipping agent (lubricant). Therefore, even if the dried coating film (handwriting) of the ink composition for an oil-based marking pen is rubbed, it is slippery and the coating film is less likely to peel off. Thus, higher fixability of the ink composition for an oil-based marking pen to the adherend surface can be obtained.

[0089] As the silicone oil, those having fluidity at least at room temperature (20 to 30 °C) are used. From the viewpoint of easily ensuring the dispersion stability in the ink composition for an oil-based marking pen, it is preferable to use a modified silicone oil as the silicone oil. Examples of the modified silicone oil include polyether-modified silicone oil, amino-modified silicone oil, mercapto-modified silicone oil, carboxy-modified silicone oil, and the like. The ink composition for an oil-based marking pen may contain one kind of silicone oil or two or more kinds of silicone oils. Among these silicone oils, polyether-modified silicone oil is preferable from the viewpoint of easily ensuring high dispersion stability and high erasability resistance of the handwriting.

[0090] Examples of polyether-modified silicone oils include polysiloxanes having a polyether structure. The polyether-modified silicone oil may have a polyether structure at the terminal of the molecular chain, may have it in the side chain, or may have it at both the terminal and the side chain.

[0091] The HLB (hydrophile-lipophile balance) of the polyether-modified silicone oil is, for example, 7 or less, and may be 5 or less. The lower limit of the HLB is not particularly limited, but is usually 3 or more.

[0092] From the viewpoint of easily achieving a balance between hydrophilicity and hydrophobicity, the polyether structure is preferably a polyoxyalkylene structure (a repeating structure of oxyalkylene units).

[0093] In the polyoxyalkylene structure, the number of repetitions of the oxyalkylene group (oxyalkylene unit) is, for example, 2 to 20, may be 2 to 16, or may be 2 to 10 or 2 to 6. The number of repetitions of the oxyalkylene group is appropriately selected, for example, so that the HLB of the modified silicone oil falls within the above range.

[0094] In the polyoxyalkylene structure, the number of carbon atoms of the alkylene is, for example, 1 to 6, and may be 2 to 6 or 2 to 4. The polyether-modified silicone oil preferably contains at least a polyoxyalkylene structure in which the number of carbon atoms of the alkylene is 2 to 4 (particularly 2 or 3) as the polyether structure.

[0095] When the ink composition for an oil-based marking pen contains an alkali-soluble resin and a sucrose fatty acid ester component (and, if necessary, a fatty acid glyceride component), in the coating film formed when writing with the oil-based marking pen, as the solvent gradually volatilizes, these components precipitate on the surface to form a film, and the volatilization of the solvent may become difficult to proceed. This is because the sucrose fatty acid ester component and the fatty acid glyceride component have low solubility in alcohols having 2 to 4 carbon atoms (preferably 2 or 3), and it can be said that this is the opposite of high cap-off property. The film formed on the surface of the coating film is sticky and may peel off when subjected to a strong impact. For example, when touching the coating film, the film may peel off and the ink composition for an oil-based marking pen in the coating film may adhere. Therefore, in the ink composition for an oil-based marking pen of the present invention, the erasability of the coating film tends to be low.

[0096] When the ink composition for an oil-based marking pen contains a polyether-modified silicone oil containing oxyethylene units, as the solvent volatilizes, the viscosity of the coating film increases, and while the solid content concentration increases from the surface side of the coating film, the polyether-modified silicone oil migrates rapidly to the surface of the coating film. As a result, the polyether-modified silicone oil bleeds at a relatively early stage on the surface of the coating film and acts as a slipping agent. Therefore, the coating film (writing) is slippery even when rubbed, and peeling and adhesion of the coating film are suppressed when touched, and the drying speed (apparent drying speed) can be shortened. In addition, the fixing property of the coating film (writing) to the adherend surface can be further enhanced. The reason why the above polyether-modified silicone oil migrates rapidly to the surface of the coating film is considered to be that the polyether-modified silicone oil contains oxyethylene units, which increases its hydrophilicity and makes it easier to separate from other lipophilic components (such as alkali-soluble resins, sucrose fatty acid esters, fatty acid glyceride components, etc.) in a state of increased concentration. From the viewpoint of easy and rapid migration of the polyether-modified silicone oil, it is particularly preferable that the polyether-modified silicone oil contains a repeating structure of oxyethylene units. When a polyether-modified silicone oil containing a repeating structure of oxyethylene units is used, it is easier to ensure higher fixing property to the adherend surface. From the viewpoint of easily introducing a larger number of repeating structures of oxyethylene units into the molecule to enhance hydrophilicity, it is preferable to use a polyether-modified silicone oil having a polyether structure (particularly, a repeating structure of oxyethylene units) at least in the side chain. Note that a polyether-modified silicone oil containing oxyethylene units (particularly, a repeating structure of oxyethylene units) has higher hydrophilicity than other polyether-modified silicone oils, but since the ink composition for an oil-based marking pen contains other lipophilic components in a well-balanced manner, high water resistance of the coating film (writing) can be ensured.

[0097] The polyether-modified silicone oil containing oxyethylene units may contain oxyalkylene units other than oxyethylene units. The number of carbon atoms of the alkylene in such oxyalkylene units is, for example, 3 to 6, and 3 or 4 is preferable. The polyether-modified silicone oil containing oxyethylene units and oxypropylene units is easily available.

[0098] The ratio (EO ratio) of the total number of oxyethylene units to the total number of oxyalkylene units in the polyether-modified silicone oil is, for example, 40% or more. From the viewpoint of obtaining a higher drying rate, the EO ratio is preferably 50% or more. The EO ratio is 100% or less. The total number of oxyalkylene units is the total number of oxyalkylene units contained in one molecule of the polyether-modified silicone oil. The total number of oxyethylene units is the total number of oxyethylene units contained in one molecule of the polyether-modified silicone oil. A polyether-modified silicone oil containing only oxyethylene units as oxyalkylene units (EO ratio = 100%) may be used.

[0099] Examples of the polyether-modified silicone oil having the above EO ratio include TSF4440, 4441, 4445, 4446 (EO ratio: 100%), and TSF4452 (total number of oxyethylene units / total number of oxypropylene units (= EO / PO) = 50 / 50 (EO ratio 50%)) manufactured by MOMENTIVE Performance Materials. All of these polyether-modified silicone oils are of the side-chain type. From the viewpoint of obtaining a higher slipping effect, it is preferable to use a side-chain type polyether-modified silicone oil.

[0100] The main chain of the polyether-modified silicone oil contains a polysiloxane structure. The polysiloxane structure of the silicone oil usually has organic groups in the side chains in addition to the side chains having a polyether structure. Examples of the organic group include an alkyl group (such as a methyl group) and an aryl group (such as a phenyl group). The polysiloxane structure may be a polyalkylsiloxane structure having an alkyl group in the side chain, or a polyarylsiloxane structure having an aryl group in the side chain. Further, the polysiloxane structure may be a polyalkylarylsiloxane structure having an alkyl group and an aryl group in the side chain. These polysiloxane structures include those in which some of the side chains are hydrogen atoms. From the viewpoint of easily controlling the viscosity of the ink composition for an oil-based marking pen and easily ensuring higher writing properties, the polyether-modified silicone oil preferably has a polyalkylsiloxane structure.

[0101] The content of the silicone oil (or polyether-modified silicone oil) in the ink composition for an oil-based marking pen is, for example, 0.01% by mass or more and 2% by mass or less, and may be 0.05% by mass or more and 2% by mass or less, may be 0.05% by mass or more and 1% by mass or less, or may be 0.1% by mass or more and 1% by mass or less. When the content of the silicone oil (such as polyether-modified silicone oil) is in such a range, higher cap-off properties can be ensured, and the drying speed can be increased. In addition to easily ensuring higher fixing properties of the ink composition for an oil-based marking pen to the adherend surface, it is easy to ensure high writing properties. The content of the polyether-modified silicone oil containing oxyethylene units in the ink composition for an oil-based marking pen may also be in the above range.

[0102] Even when the ink composition for an oil-based marking pen contains a sucrose fatty acid ester component and a polyether-modified silicone oil (and a fatty acid glyceride component if necessary), when the content of the alkali-soluble resin increases, the cap-off property tends to decrease. Therefore, from the viewpoint of ensuring a higher cap-off property, the content of the alkali-soluble resin in the ink composition for an oil-based marking pen is preferably 20% by mass or less, and may be 15% by mass or less or 11% by mass or less. As described above, the lower limit of the content of the alkali-soluble resin in the ink composition for an oil-based marking pen is preferably 3% by mass or more or 5% by mass or more. Further, when the content of the alkali-soluble resin is relatively low in this way, the content of the sucrose fatty acid ester component and the fatty acid glyceride component becomes relatively high, so the film becomes sticky and the drying rate tends to be slow. Therefore, it is advantageous to further use a polyether-modified silicone oil to improve the drying rate.

[0103] (Additive) The ink composition for an oil-based marking pen can contain additives as necessary. The additives are not particularly limited, and examples include known additives added to the ink composition for an oil-based marking pen. Examples of the additives include, but are not limited to, viscosity modifiers, structure viscosity imparting agents, dye solubilizers, drying property imparting agents, and the like.

[0104] (Others) When the ink composition for an oil-based marking pen has a low viscosity, the outflow amount of the ink composition for an oil-based marking pen increases, and a high cap-off property is easily obtained. In the present invention, since the ink composition for an oil-based marking pen contains the above components, high fixing property can be ensured even when the amount of the resin component is relatively small, so it is easy to reduce the viscosity.

[0105] The viscosity of the ink composition for an oil-based marking pen at 20°C is, for example, 10 mPa·s or less, and may be 6 mPa·s or less. The viscosity of the ink composition for an oil-based marking pen at 20°C is, for example, 1 mPa·s or more, and may be 2 mPa·s or more. Note that the viscosity of the ink composition for an oil-based marking pen is measured, for example, using a commercially available E-type rotational viscometer at 20°C under the condition of a rotational speed of 50 rpm.

[0106] The ink composition for an oil-based marking pen can be prepared by mixing the constituent components. During the preparation process, the mixture may be heated as necessary. The constituent components may be mixed all at once, or after mixing some of the constituent components, the remaining constituent components may be added. The order of addition of the constituent components is not particularly limited.

[0107] [Examples] Hereinafter, the present invention will be specifically described based on examples and comparative examples, but the present invention is not limited to the following examples.

[0108] 《Examples 1 to 9, Reference Example 1 and Comparative Example 1》 (1) Preparation of the ink composition for an oil-based marking pen Prepare the ink composition for an oil-based marking pen with the components and amounts shown in Table 1. More specifically, the resin component and the dye component were added to the solvent component under stirring and dissolved to prepare the ink composition for an oil-based marking pen.

[0109] The following were used as the solvent component, resin component, and dye component.

[0110] (I) Solvent component (i) First solvent (ia) Ethanol (ib) Isopropanol (ii) Second solvent (iia) Propylene glycol monomethyl ether (iib) Ethylene glycol mononormal butyl ether

[0111] (II) Resin components (i) Resin 1 (alkali-soluble resin): Styrene-acrylic resin (manufactured by BASF, Joncryl 682, acid value 238, Mw 1700) (ii) Resin 2 (alkali-soluble resin): Styrene-acrylic resin (manufactured by BASF, Joncryl 690, acid value 240, Mw 16500) (iii) Resin 3 (alkali-soluble resin): Styrene-acrylic resin (manufactured by BASF, Joncryl 683, acid value 160, Mw 8000) (iv) Resin 4 (alkali-soluble resin): Styrene-acrylic resin (manufactured by Starlight PMC, Hiros X-1, acid value 110, Mw 18000) (v) Resin 5 (alkali-soluble resin): Acrylic resin (manufactured by Starlight PMC, Hiros X-310, acid value 60, Mw 14000) (vi) Resin 6 (alkali-insoluble resin): Acrylic resin (manufactured by Mitsubishi Chemical Holdings, Dianal BR-100, acid value 0) (vii) Resin 7 (polyvinylamide-based resin): Polyvinylpyrrolidone (manufactured by Tokyo Chemical Industry, K15, Mw about 10000) (viii) Resin 8 (polyvinylamide-based resin): Polyvinylpyrrolidone (manufactured by Tokyo Chemical Industry, K30, Mw about 40000)

[0112] (III) Dye components (i) Dye 1: Methine-based basic dye, C.I. Basic Red 14 (ii) Dye 2: Methine-based basic dye, C.I. Basic Red 37 (iii) Dye 3: Methine-based basic dye, C.I. Basic Violet 27 (iv) Dye 4: Azo-based basic dye, C.I. Basic Red 18 (v) Dye 5: Azo-based basic dye, C.I. Basic Yellow 36

[0113] (2) Preparation of an oil-based marking pen The ink composition for an oil-based marking pen obtained in the above (1) was filled into a refill for an oil-based marking pen and set in a container of the oil-based marking pen, whereby an oil-based marking pen was produced.

[0114] (3) Evaluation The following evaluations were carried out using the oil-based marking pen produced in the above (2) or the ink composition for an oil-based marking pen prepared in (1).

[0115] (a) Viscosity The viscosity of the ink composition for an oil-based marking pen was measured using an E-type rotational viscometer (manufactured by Toki Sangyo Co., Ltd., TVE-type viscometer, cone and rotor = 1°34′×R24) under the condition of a rotational speed of 50 rpm.

[0116] (b) Writing property on an oil film An anti-rust oil was coated on the surface of a steel plate to form an oil film. Writing was done on the surface of the oil film with an oil-based marking pen, and the repellency of the ink composition for an oil-based marking pen at this time was evaluated according to the following criteria. A: No repellency of the ink composition for an oil-based marking pen is observed at all. B: Slight repellency of the ink composition for an oil-based marking pen is observed. C: The repellency of the ink composition for an oil-based marking pen is remarkable.

[0117] (c) Alkaline decolorization property Writing was done on a steel plate with an oil-based marking pen and dried. An aqueous solution containing sodium hydroxide at a concentration of 5% by mass was sprayed on the handwriting and left for 1 minute. The color development state of the handwriting at this time was evaluated according to the following criteria. A: No color development of the handwriting is observed at all (transparent). B: Slight color development of the handwriting is observed. C: The color development of the handwriting remains as vivid as before spraying.

[0118] (d) Alkaline detergency (removability of the coating by alkali) In (c) above, a spray was applied and after leaving it for 1 minute, the sprayed area was gently wiped with a cloth, and the state of the handwriting was observed. A: The handwriting has completely disappeared. B: The handwriting remains, but the original shape cannot be distinguished. C: The handwriting can be clearly distinguished.

[0119] (e) Water resistance 1 The steel plate was written with an oil-based marking pen and dried. The steel plate was immersed in a water bath for 10 minutes. The steel plate was taken out of the water bath, and the state of the handwriting was evaluated according to the following criteria. A: No change is seen in the handwriting before and after immersion in the water bath. B: Slight change is seen in the handwriting. C: The change in the handwriting is significant. Or the handwriting does not remain.

[0120] (f) Color development property The Kent paper was written with an oil-based marking pen and dried. The color development of the handwriting was evaluated according to the following criteria based on the L*a*b* color system. A: |a*| + |b*| ≧ 31 B: |a*| + |b*| < 31

[0121] (g) Quick-drying property The steel plate was written with an oil-based marking pen and dried under the conditions of 20°C and 65% RH. The quick-drying property was evaluated according to the following criteria based on the time until drying was completed after writing. A: The time until drying is completed is within 10 seconds. B: The time until drying is completed exceeds 10 seconds and is within 30 seconds. C: The time until drying is completed exceeds 30 seconds.

[0122] The results are shown in Table 1. In the table, E1 to E9 are Examples 1 to 9, C1 is Comparative Example 1, and R1 is Reference Example 1.

[0123]

Table 1

[0124] As shown in Table 1, in E1 to E9, although a dilute alkaline aqueous solution with a concentration of 5% by mass is used, the film formed by marking can be easily removed. In E8 and E9 using dyes other than methine-based basic dyes, the color does not fade even when contacted with the alkaline aqueous solution. On the contrary, in E1 to E7 using methine-based basic dyes, the color can fade by contacting with the alkaline aqueous solution. Also, in E1 to E9, high writing performance on the oil film can be ensured.

[0125] On the contrary, in C1 using a resin insoluble in alkali, although a basic dye is used, the film formed by marking could not be removed even when washed with the alkaline aqueous solution.

[0126] 《Examples 10 to 25 and Comparative Examples 2 to 6》 An ink composition for an oil-based marking pen is prepared with the components and amounts shown in Tables 2 to 4. More specifically, first, the sucrose fatty acid ester component and the fatty acid glyceride component are dissolved in the solvent component as necessary. The obtained solution is heated to a temperature of 45°C ± 5°C, the resin component is added and stirred to be dissolved. The obtained solution is maintained at 45°C ± 5°C, and the dye component and, if necessary, the polyether-modified silicone oil are added to the solution and stirred to be dissolved. In this way, an ink composition for an oil-based marking pen is prepared.

[0127] Among the components in Tables 2 to 4, the components not described in Table 1 are as follows. (I) Solvent component (i) First solvent (ic) n-Propyl alcohol (ii) Second solvent (iic) Dipropylene glycol monomethyl ether

[0128] (II) Resin component (ix) Resin 9 (oil-soluble resin): Alkylphenol resin (manufactured by Arakawa Chemical Industries, Ltd., Tamanol 510) (x) Resin 10 (oil-soluble resin): water-added ketone resin (manufactured by EVONIK, TEGO VARIPLUS SK) (xi) Resin 11 (oil-soluble resin): rosin ester resin (manufactured by Arakawa Chemical Industries, Markid 33) (xii) Resin 12 (oil-soluble resin): rosin resin (manufactured by Arakawa Chemical Industries, Rosin WW)

[0129] (III) Dye component (vi) Dye 6: triarylmethane-based basic dye, C.I. Basic Blue 7 (vii) Dye 7: triarylmethane-based basic dye, C.I. Basic Green 1 (viii) Dye 8: azo-based basic dye, C.I. Basic Blue 66 (ix) Dye 9: oil-soluble dye, Spiron Red CGH (manufactured by Hodogaya Chemical Co., Ltd.)

[0130] (IV) Others (i) Sucrose fatty acid ester component (sucrose fatty acid ester, manufactured by Dai-Ichi Kogyo Seiyaku Co., Ltd., DK Ester F-50, HLB 6) (ii) Fatty acid glyceride component (fatty acid triglyceride, manufactured by MULTICHEM, CA340.2) (iii) Polyether-modified silicone oil 1 (manufactured by Momentive Performance Materials, TSF4446, EO / PO = 100 / 0) (iv) Polyether-modified silicone oil 2 (manufactured by Momentive Performance Materials, TSF4452, EO / PO = 50 / 50)

[0131] Using the prepared oil-based marking pen or the ink composition for the prepared oil-based marking pen, the evaluations of (a) viscosity, (d) alkali washability, and (g) quick-drying property were carried out in the same manner as in Examples 1 to 9, and the following evaluations were also carried out. Note that the actual drying rates of the quick-drying property are shown in Tables 2 and 3.

[0132] (h) Water resistance 2 The water resistance of the handwriting was evaluated according to the same procedure and criteria as those for water resistance 1, except that the immersion time of the steel plate in the water bath was changed to 1 hour.

[0133] (i) Cap-off property in a general atmospheric environment (humid environment) In a constant temperature chamber at 20 °C and a relative humidity of 65%, the cap of the oil-based marking pen was removed and left in a horizontal position. After leaving it, the cap-off property was evaluated when writing was done 1 day, 7 days, 14 days, and 28 days later. However, the cap-off property was evaluated according to the following criteria for writing on the steel plate. 5: No bleeding is observed in all 10 circles, or bleeding does not occur during the writing of the first circle. 4: Bleeding does not occur during the writing of the second circle. 3: Bleeding does not occur during the writing of the third or fourth circle. 2: Bleeding does not occur during the writing of the fifth to ninth circles. 1: Bleeding is observed in all 10 circles.

[0134] The results of Examples 10 to 25 and Comparative Examples 2 to 6 are shown in Tables 2 to 4. Note that Examples 10 to 25 are E10 to E25 respectively, and Comparative Examples 2 to 6 are C2 to C6 respectively.

[0135]

Table 2

[0136] As shown in Table 2, when an oil-soluble resin is used instead of an alkali-soluble resin and an oil-soluble dye is used instead of a basic dye, high writability (or fixability) with respect to the adherend surface can be ensured. However, in these cases, the handwriting cannot be removed with an aqueous solution containing alkali (C2 to C6).

[0137]

Table 3

[0138]

Table 4

[0139] As shown in Table 4, when the ink composition for an oil-based marking pen does not contain a sucrose fatty acid ester component, the cap-off property deteriorates (E19 to E21 and E23). On the other hand, when the ink composition for an oil-based marking pen contains a sucrose fatty acid ester component (furthermore, a fatty acid glyceride component), a high cap-off property can be obtained (E10 to E18, E22, E24, and E25). From the viewpoint of ensuring a higher cap-off property, the content of the alkali-soluble resin is preferably 20% by mass or less (comparison between E24 and E25 and E10 and E18). Further, by including a polyether-modified silicone oil in the ink composition for an oil-based marking pen, the drying rate can be increased (comparison between E19 and E20 and E10 and E18). Also in the examples of Table 3 and Table 4, as in the case of Examples 1 to 9, high alkali detergency and high fixability (or writing property) can be obtained.

Industrial Applicability

[0140] The ink composition for an oil-based marking pen of the present invention is excellent in writing property on an oil film and excellent in removability with an alkali. Therefore, the ink composition for an oil-based marking pen is particularly suitable for marking on a metal processing material that is subjected to a degreasing treatment with an alkali. However, the use of the ink composition for an oil-based marking pen is not limited to such uses.

Claims

1. Comprising a solvent component, a resin component, and a dye component, The solvent component contains at least an alcohol having 2 to 4 carbon atoms, The resin component consists of only an alkali-soluble resin or only an alkali-soluble resin and a polyvinylamide-based resin, The alkali-soluble resin contains an anionic monomer unit and has an acid value of 30 KOH·mg / g or more, The content of the alkali-soluble resin is 3% by mass or more and 30% by mass or less, The content of the polyvinylamide-based resin is 10% by mass or less, which is less than the content of the alkali-soluble resin, The dye component consists of only a basic dye, an ink composition for an oil-based marking pen.

2. The alkali-soluble resin has an acid value of 40 KOH·mg / g or more, the ink composition for an oil-based marking pen according to Claim 1.

3. The weight average molecular weight of the alkali-soluble resin is 1000 or more and 20000 or less, the ink composition for an oil-based marking pen according to Claim 1 or 2.

4. The ratio of the alcohol in the solvent component is 50% by mass or more, the ink composition for an oil-based marking pen according to any one of Claims 1 to 3.

5. The dye component consists of only a methine-based basic dye, the ink composition for an oil-based marking pen according to any one of Claims 1 to 4.

6. The content of the methine-based basic dye is 0.1% by mass or more and 10% by mass or less, the ink composition for an oil-based marking pen according to Claim 5.

7. Further comprising a sucrose fatty acid ester component, the ink composition for an oil-based marking pen according to any one of Claims 1 to 6.

8. The content of the sucrose fatty acid ester component is 0.1% by mass or more and 1% by mass or less, the ink composition for an oil-based marking pen according to Claim 7.

9. Further comprising a fatty acid glyceride component, the ink composition for an oil-based marking pen according to Claim 7 or 8.

10. The content of the fatty acid glyceride component is 0.3% by mass or more and 2.5% by mass or less, the ink composition for an oil-based marking pen according to Claim 9.

11. The content of the alkali-soluble resin is 3% by mass or more and 20% by mass or less, the ink composition for an oil-based marking pen according to any one of Claims 7 to 10.

12. The ink composition for an oil-based marking pen according to any one of claims 1 to 11, further comprising a polyether-modified silicone oil.

13. The polyether-modified silicone oil includes a repeating structure of oxyalkylene units, and includes at least oxyethylene units as the oxyalkylene units. The ink composition for an oil-based marking pen according to claim 12, wherein the ratio of the total number of oxyethylene units to the total number of oxyalkylene units is 50% or more.

14. The ink composition for an oil-based marking pen according to claim 12 or 13, wherein the content of the polyether-modified silicone oil is 0.01% by mass or more and 2% by mass or less.

15. The ink composition for an oil-based marking pen according to any one of claims 1 to 14, which is used for marking a metal processing material subjected to degreasing treatment with an alkali.

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