JP2006335927A - Ink composition for oil-based marking pen - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink composition for an oil-based marking pen having suppressed unevenness of the ink concentration at the pen tip of the oil-based marking pen after leaving at rest for a long period and improving the writing performance by minimizing the precipitation of pigment and free from the leakage of a medium-viscosity oil-based ink from the pen tip. <P>SOLUTION: The ink composition for an oil-based marking pen contains ≥30 mass% organic solvent as the solvent and has a viscosity of 2-20 mPa s. The composition contains 5-50 mass% inorganic pigment having an average particle diameter of 0.008-0.05μm and 1-20 mass% pigment having an average particle diameter of 0.05-0.3μm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ink composition for oil-based marking pens. More specifically, the present invention includes a pigment, and prevents ink settling and deviation in the pen to prevent variation in ink density at the pen tip. The present invention relates to an ink composition for an oil-based marking pen that is suppressed.

Conventionally, as a marking pen ink that can be written on paper, glass, plastic, etc., an ink composition in which a dye and a resin are dissolved in an organic solvent, a marker ink for whiteboard in which a pigment is dispersed in an organic solvent, etc. There is.
In dye inks, there is little variation in the pen tip density regardless of the pen leaving direction, but the light resistance of the drawn lines for the dye is insufficient. In addition, organic solvent pigment inks typified by whiteboard marker inks cause sedimentation of the pigment, so that when the pen tip is left facing upward or downward, the ink density at the pen tip varies significantly.

  In order to solve such problems, various proposals have been made for pigment ink compositions. For example, there has been proposed an ink composition containing a thixotropic agent that imparts a viscosity that prevents precipitation of the pigment during storage at rest and reduces the viscosity by stirring or shaking (for example, Patent Document 1). See). As the thixotropic agent, smectite, tetratetrafluoromica, bentonite, silica, montmorillonite, sodium polyacrylate and the like are used.

  Further, it contains 5 to 25% by weight of a spherical resin having a particle diameter of 0.5 to 20 μm formed by dyeing a spherical resin with a dye or pigment, and 0.1 to 5.0% by weight of fine particulate anhydrous silica. A whiteboard marking pen ink composition has been proposed (see, for example, Patent Document 2). If writing is performed by shaking a pen using such an ink composition, the redispersibility of the ink in the ink containing cylinder is good, and the colorant particles settled in the ink are easily redispersed. Also, the stirrer housed in the ink container starts to move by shaking once or twice, and all the liquid returns to the original state by shaking 4 to 5 times, and the ink in the pen core is the same. It is said that you can return to the original state and write smoothly.

  Although it is different from the ink for oil-based marking pens, it is suitable for use as a ballpoint pen with a direct connection between the ink tank and the pen body, or as a direct liquid writing instrument or applicator with a valve mechanism between the ink tank and the pen body. As an oil-based ink composition that can be used, a composition containing an aluminum salt of a saturated fatty acid has been proposed (see, for example, Patent Document 3). Such an oil-based ink composition is supposed to prevent darkening and lightening of the ink due to sedimentation of the pigment. In addition, in ink using a pigment having a remarkably large specific gravity, such as titanium oxide, it contributes to a decrease in ink function due to hard cake formation in which precipitation further proceeds, prevention of ink leakage of a medium viscosity oil-based ballpoint pen, and improvement in writing performance.

JP-A-8-325491 JP-A-10-36744 JP 2001-329204 A

  However, both ink compositions imparted with thixotropy and pigment spheroidizing ink compositions require re-stirring. Even if the thixotropy is exhibited, an oil-based marking pen made of a fiber bundle core is irrelevant to the variation in the concentration of the pen tip whether or not the thixotropy is expressed.

  Therefore, in order to solve such problems, the present invention suppresses the ink sedimentation of the oil-based marking pen after standing for a long period of time by suppressing the sedimentation of the pigment as much as possible, thereby improving the writing property. An object of the present invention is to provide an oil-based marking pen ink composition for low- and medium-viscosity oil-based inks that does not leak from the tip.

The present inventor is an oil-based marking pen that uses an organic solvent whose viscosity characteristics are extremely limited as a solvent, and is a pigment fine particle that does not easily settle in an organic solvent, that is, a pigment having an average particle size in the range of 0.008 to 0.05 μm. Is added to the solvent to increase the apparent specific gravity of the solvent solution itself, and the specific gravity and apparent specific gravity of the carbon black or organic pigment having an average particle size of 0.05 to 0.3 μm as the main pigment It has been found that by reducing the difference between the two, the sedimentation of the main pigment is prevented and the change in ink density at the nib is suppressed, and the present invention has been achieved.
That is, the ink composition for an oil-based marking pen according to the present invention comprises the following constitution or means, and solves the above problems.

(1). Inorganic pigment 5 containing 30% by mass or more of the organic solvent and having a viscosity in the range of 2 to 20 mPa · s and an average particle diameter in the range of 0.008 to 0.05 μm. An ink composition for an oil-based marking pen containing ˜50 mass% and 1 to 20 mass% of a pigment having an average particle diameter in the range of 0.05 to 0.3 μm.
(2). The ink composition for oil-based marking pens according to the above (1), wherein the inorganic pigment comprises at least one pigment of silica, titanium oxide, and zinc oxide.
(3). The ink composition for oil-based marking pens according to the above (1), which contains a dispersant for the pigment, the dispersant is a highly functional resin, and the resin is a polyvinyl butyral or a basic functional group-containing dispersant.
(4). The ink composition for an oil-based marking pen according to (1), wherein 2 to 12% by mass of a fatty acid monoester and 0.5 to 4% by mass of a phosphoric acid ester are added.
(5). The ink composition for oil-based marking pens according to (1) above, wherein 1 to 20% by mass of a dye is added.

  According to the ink composition for an oil-based marking pen according to the present invention, an oil-based marking ink having excellent light resistance is obtained by mainly using a pigment instead of a dye as a coloring material. In this case, an inorganic pigment having a small particle diameter is used. It acts to increase the apparent specific gravity of the solvent, suppresses the precipitation of the pigment having an average particle size in the range of 0.05 to 0.3 μm as the main pigment, and does not cause poor writing even when left for a long period of time. Further, there is no leakage from the pen tip in the medium viscosity oil-based ink.

Hereinafter, preferred embodiments of the oil-based marking pen ink composition according to the present invention will be described in detail. The ink composition for an oil-based marking pen according to the present invention is not limited to the following embodiments and examples.
The ink composition for oil-based marking pens according to the present invention is an ink composition for oil-based marking pens having an organic solvent as a solvent and a viscosity of 2 to 20 mPa · s containing 30% by mass or more of the organic solvent. . The viscosity is an E-type viscometer measured at a rotor speed of 20 to 50 rpm. The ink composition for oil-based marking pens is intended for low-viscosity and medium-viscosity ink compositions having a viscosity in the range of 2 to 20 mPa · s. In particular, the viscosity is preferably in the range of 3 to 15 mPa · s.

The ink composition for an oil-based marking pen preferably contains an organic solvent in an amount of at least 30% by mass, particularly 40 to 90% by mass. When the organic solvent in the ink composition is less than 30% by mass, the inorganic pigment and the main pigment are not sufficiently dispersed, and the viscosity is increased.
Specific organic solvents include general ester solvents such as butyl acetate and isoamyl acetate, ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, aliphatic solvents such as hexane and isooctane, and aromatic solvents such as toluene and xylene. Group solvents and the like. In addition, as solvents having low toxicity, alkyl alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, n-butyl alcohol, sec-butyl alcohol and t-butyl alcohol, ethylene glycol, propylene glycol, butylene glycol , Triethylene glycol, 1,2,6-hexanetriol, alkylene alcohols such as thiodiglycol, hexylene glycol and diethylene glycol, ethers with these alkylene alcohols, polyhydric alcohols such as glycerin, ethylene glycol and diethylene glycol , Polyhydric alcohols such as diethylene glycol dimethyl (or ethyl) ether, carbitol and triethylene glycol monomethyl ether Ethers, and carbitol acetate and the like. In addition, amides such as dimethylformamide and dimethylacetamide, ketones or ketone alcohols such as acetone and diacetone alcohol, ethers such as tetrahydrofuran and dioxane, polyalkylene glycols such as polyethylene glycol and polypropylene glycol, methyl cellosolve and ethyl cellosolve And the like.
In the oil-based marking pen ink composition, the solvent is substantially an organic solvent, but it may contain a trace amount of moisture of 5% by mass or less derived from the raw material.

The ink composition for an oil-based marking pen comprises a fine particle-containing solvent solution containing at least an inorganic pigment having an average particle diameter in the range of 0.008 to 0.05 μm in a range of 5 to 50% by mass. And the apparent specific gravity of the inorganic pigment-containing solvent solution increases. A more preferable blending amount of the inorganic pigment with respect to the ink composition is in the range of 10 to 40% by mass.
The inorganic pigment is not particularly limited as long as it can be used in the ink composition, and specific examples include silica, titanium oxide, aluminum oxide, gold, silver, iron oxide, zinc oxide, calcium sulfate and the like. . Preferably, silica, titanium oxide, zinc oxide and the like are desirable because of their good stability when dispersed in a solvent.

  The average particle diameter of the inorganic pigment is in the range of 0.008 to 0.05 μm. A more preferable average particle diameter is in the range of 0.01 to 0.04 μm. When the average particle diameter of the inorganic fine particles is less than 0.008 μm, the dispersion stability in the solution is poor, and when the average particle diameter exceeds 0.05 μm, the inorganic fine particles themselves are liable to precipitate. Specific inorganic pigments having such a particle size include those manufactured by Nippon Aerosil Co., Ltd. such as Aerosil 200 (average particle size 0.012 μm) and Aerosil R972 (average particle size 0.016 μm), which are silica, Snowtex 50 (Average particle size 0.025 μm), silica sol IPA-SP (average particle size 0.015 μm), silica sol PGM-ST (average particle size 0.015 μm), etc., manufactured by Nissan Chemical Industries, Ltd., or TTO which is titanium oxide -51A (average particle size 0.02 μm), TTO-51C (average particle size 0.02 μm) manufactured by Ishihara Sangyo Co., Ltd. and MT-100s (average particle size 0.015 μm) manufactured by Teika Co. Examples include zinc FTO-50 (average particle size 0.02 μm) manufactured by Ishihara Sangyo Co., Ltd. and MZ-707S (average particle size 0.015 μm) manufactured by Teika. Door can be.

The ink composition for oil-based marking pens contains, as a main pigment, a pigment having an average particle size in the range of 0.05 to 0.3 μm in a range of 1 to 20% by mass. When the average particle diameter of the pigment exceeds 0.3 μm, the precipitation of the pigment in the ink composition cannot be sufficiently prevented. Further, when the average particle size of the pigment is less than 0.05 μm, the effect as the main pigment in the ink composition is lowered.
When the pigment in the ink composition is less than 1% by mass, the effect as a pigment is not sufficiently exhibited. On the other hand, if the pigment content exceeds 20% by mass, unevenness in ink density during writing tends to occur, making it difficult to prevent the pigment from settling.
Pigments used in the ink composition for oil-based marking pens are inorganic pigments such as carbon black and ultramarine blue, azo, phthalocyanine, indigo, shioindigo, selenium, quinacridone, anthraquinone, throne, diketopyrrolopyrrole -Based, dioxane-based, perylene-based, perinone-based, isoindolinone-based organic pigments, metallic luster pigments such as aluminum powder and brass powder, and fluorescent pigments in the form of synthetic resin fine particles in which a fluorescent dye is solid-solved in a resin matrix, Examples include pearl pigments and phosphorescent pigments. One or two or more kinds having an average particle diameter selected from the above pigments in the above range can be mixed and used at an arbitrary ratio.

  In order to improve the dispersibility of the pigment, it is preferable to add a high-functional resin to the oil-based marking pen ink composition. The addition amount of the high-functional resin is preferably in the range of 0.1 to 50% by mass and particularly preferably in the range of 1 to 40% by mass with respect to the total amount of the ink composition. Examples of highly functional resins include butyral resins, phenol resins, basic functional group-containing copolymers, ketone resins, rosins and / or modified rosins, rosin esters and other rosin resins, butyral resins, polyamide resins, cellulose resins, Examples thereof include amino resins, acrylic resins, vinyl resins, maleic acid resins, epoxy resins, alkyd resins, and urethane resins.

  As the highly functional resin of the oil-based marking pen ink composition, a butyral resin, a phenol resin, and a basic functional group-containing copolymer are particularly preferable. If a specific example is given, as phenol resin, Tamanol 100S, 510 (above, Arakawa Chemical Co., Ltd. product), Hitanol 1501, 2501 (above, Hitachi Chemical Co., Ltd. product) etc. are mentioned. Examples of the butyral resin include Denkabutyral # 2000-L, # 3000-1, # 3000-2, # 3000-4, # 3000-K (above, manufactured by Denki Kagaku Kogyo Co., Ltd.). . Examples of the basic functional group-containing copolymer include Solsperse S3000, S9000, S13000, S17000 (diethanolamine-based), S20000 (ethyleneimine-based), S24000GR (azolidine and 1,2-hydroxystearic acid-based polyester), and the like. , Manufactured by Abyssia), BYK (Bisperbyk) series 101, 108, 161, 162, 163, 164, 165, 166, 170 (above, manufactured by BYK Chemie), Ajisper series PB-711, PB-821 , PB-822 (manufactured by Ajinomoto Finetech Co., Ltd.) and the like. These can be used alone or in combination.

In order to improve the erasability of the ink, it is also possible to add an erasing agent such as a fatty acid monoester or a phosphate ester. Examples of fatty acid monoesters include isocetyl myristate (trade name: NIKKOL ICM-R, manufactured by Nikko Chemicals), butyl myristate, butyl stearate, cetyl isooctanoate, diethyl sebacate, and diisopropyl adipate. Examples of phosphoric acid esters include alkyl polyoxyethylene addition type phosphoric acid esters. The fatty acid monoester is preferably added in the range of 2 to 12% by mass with respect to the ink composition. The phosphoric acid ester is preferably added in the range of 0.5 to 4% by mass with respect to the ink composition.

  In the present invention, a dye can be added to the ink composition as necessary. As the dye, C.I. I. Solvent Black 7, 123, C.I. I. Solvent Red 8, 49, C.I. I. Solvent Blue 2, 25, 55, 70, C.I. I. Solvent Green 3, C.I. I. Solvent Yellow 21, 61, C.I. I. Solvent Orange 37, C.I. I. Solvent Violet 8, 21 and Varifast Red 3311 are included. The amount of dye used is preferably 2 to 20% by weight based on the total amount of the ink composition.

  In the present invention, the ink composition for an oil-based marking pen has an evaporation inhibitor, an antiseptic, an antifungal agent, a wetting agent, a viscosity modifier, in addition to the above-described components, as long as the above effects are not lost. Various additives such as a freeze stabilizer and an antifoaming agent can be appropriately selected and used.

Next, the present invention will be described in more detail with reference to examples and comparative examples. Examples and comparative examples were evaluated by the following methods.
Example 1
Propylene glycol monomethyl ether (PGM) 35% by mass, average particle size 0.2 μm red pigment (trade name: Chromophthalol DPP Red 2030, manufactured by Ciba Specialty Chemicals) 5% by mass, average particle size 0.015 μm 30% by mass of propylene glycol monomethyl ether dispersion (water content 2% or less) solution (trade name: silica sol PGM-ST, manufactured by Nissan Chemical Industries, Ltd.) 50% by mass, polyvinyl butyral (trade name: BL -1, Sekisui Chemical Co., Ltd.) 5% by mass and red dye (trade name: Balifast Red 1355, manufactured by Orient Chemical Co., Ltd.) 5% by mass, for a marking pen with a viscosity of 7.0 mPa · s The ink composition is referred to as Example 1.

(Example 2)
Propylene glycol monomethyl ether (PGM) 34% by mass, blue pigment (trade name: Chromophthalol Blue A3R, manufactured by Ciba Specialty Chemicals) having an average particle size of 0.2 μm 5% by mass, average particle size 0.015 μm 30 50% by mass of isopropanol-dispersed silica sol (water content 2% or less) solution (trade name: Silica sol IPA-ST, manufactured by Nissan Chemical Industries, Ltd.) as a highly functional resin, a pigment containing ethyleneimine basic functional group (trademark) Name: Solsperse 20000, manufactured by Avicia) 3% by mass, polyvinyl butyral (trade name: Hitanol 1501, Hitachi Chemical Co., Ltd.) 5% by mass as a highly functional resin, and blue dye (trade name: Bali Fast Blue) 2620, manufactured by Orient Chemical Industry Co., Ltd.), a 3% by mass viscosity of 7.0 mPa · s The ink composition for a king pen is referred to as Example 2.

(Example 3)
Isopropanol dispersed silica sol containing 32% by mass of isooctane and 5% by mass of red pigment (trade name: Chromophthalanol DPP Red, manufactured by Ciba Specialty Chemicals) and 30% by mass of average particle size of 0.015 μm. 50% by mass of a solution (trade name: silica sol IPA-ST, manufactured by Nissan Chemical Industries, Ltd.) and a polyvinyl butyral (trade name: BL-1, manufactured by Sekisui Chemical Co., Ltd.) as a highly functional resin 5% by weight, 5% by weight of polyvinyl butyral (trade name: Hitanol 1501, manufactured by Hitachi Chemical Co., Ltd.) as a highly functional resin, and 3% by weight of red dye (trade name: SOTRED3, manufactured by Hodogaya Chemical Co., Ltd.) An ink composition for a marking pen having a viscosity of 7.0 mPa · s is referred to as Example 3.

Example 4
50% by mass of an alcohol-dispersed black pigment (trade name: AMBK-7, manufactured by Orient Chemical Industries) containing 22% by mass of ethanol and 10% by mass of an average particle size of 0.15 μm (titanium oxide having an average particle size of 0.2 μm) Trade name: TTO-51A, manufactured by Ishihara Sangyo Co., Ltd. 15% by mass, aliphatic monoester (trade name: ICM-R, manufactured by Nikko Chemicals) 10% by mass, phosphate ester (trade name: RS-410, Toho) A marking pen ink composition having a viscosity of 8.0 mPa · s comprising 2% by mass of Chemical Industries, Ltd. and 1% by mass of triglyceryl monostearate (Taiyo Kagaku Co., Ltd.) is referred to as Example 4.

(Example 5)
Propylene glycol monomethyl ether (PGM) 33% by mass, carbon black (trade name: # 1000, manufactured by Mitsubishi Chemical Corporation) having an average particle size of 0.09 μm 15% by mass, propylene glycol containing 30% by mass with an average particle size of 0.015 μm 40% by mass of a glycol monomethyl ether dispersion (water content 2% or less) solution (trade name: silica sol PGM-ST, manufactured by Nissan Chemical Industries, Ltd.), a basic functional group-containing polymer as a high-functional resin (trade name: Ajisper) An ink composition for a marking pen having a viscosity of 7.0 mPa · s, comprising 6% by mass of PB821, manufactured by Ajinomoto Finetech Co., Ltd. and 6% by mass of polyvinyl butyral (trade name: Hitanol 1501, manufactured by Hitachi Chemical Co., Ltd.). This is Example 5.

(Comparative Example 1)
Comparative Example 1 is obtained by adding ethanol in place of the red pigment of Example 1, chromophanol DPP red.
(Comparative Example 2)
What added ethanol instead of the titanium oxide of Example 4 was made into the comparative example 2.
(Comparative Example 3)
Comparative Example 3 was prepared by adding propylene glycol monomethyl ether (PGM) instead of silica sol PGM-ST of Example 1.

7 g of the above-described ink composition is filled into a batting type sign pen PWB-7M shaft manufactured by Mitsubishi Pencil Co., Ltd., and the following test evaluation is performed.
<Writing test 1>
After leaving the pen tip upward at a temperature of 25 ° C. for 3 months, write on paper, compare the concentration of the first brush with that before standing, and determine visually. ○ shows almost no change in density. Δ shows a slight decrease in density. X shows a significant decrease in density.

<Writing test 2>
After leaving the pen tip downward at a temperature of 25 ° C. for 3 months, write on paper, compare the concentration of the first brush with that before standing, and judge visually. ○ shows almost no change in density. Δ is slightly blurred and density is increased. X indicates that clogging of the pigment at the nib is observed and writing is impossible.

<Light resistance test>
A drawn line was drawn on paper with the above-described PMB-7M pen body containing each sample, and left for 6 months indoors in direct sunlight, and the color fading was judged visually. ○ shows almost no fading. △ is slightly faded. X is markedly fading.
The following results are shown in Table 1.

  From the results in Table 1, it can be seen that Examples 1 to 5 showed excellent results in the writing tests 1 and 2, but Comparative Examples 2 to 3 were not sufficient in writing properties. In Comparative Example 1, it is also found that the light resistance is inferior because the dye is mainly used.

  The ink composition for oil-based marking pens of the present invention is excellent in light resistance due to being mainly composed of pigments, and has high industrial applicability without causing poor writing even when left for a long period of time as in the prior art.

Claims (5)

An ink composition for an oil-based marking pen containing 30% by mass or more of an organic solvent and having a viscosity in the range of 2 to 20 mPa · s, and having an average particle diameter in the range of 0.008 to 0.05 μm An ink composition for an oil-based marking pen comprising 50% by mass and 1 to 20% by mass of a pigment having an average particle diameter in the range of 0.05 to 0.3 μm. The ink composition for an oil-based marking pen according to claim 1, wherein the inorganic pigment comprises at least one pigment of silica, titanium oxide, and zinc oxide. The ink composition for oil-based marking pens according to claim 1, comprising a dispersant for the pigment, wherein the dispersant is a highly functional resin, and the resin is polyvinyl butyral or a basic functional group-containing dispersant. The ink composition for an oil-based marking pen according to claim 1, wherein 2 to 12% by mass of a fatty acid monoester and 0.5 to 4% by mass of a phosphoric acid ester are added. The ink composition for oil-based marking pens according to claim 1, wherein 1 to 20% by mass of a dye is added.