JPH0813949B2 - Oil-based pigment ink composition for core type marking pen - Google Patents

Description

TECHNICAL FIELD The present invention relates to an oil-based pigment ink composition for so-called core-type marking pens, which uses carbon black as a coloring agent, and more specifically, it has excellent fine dispersion stability of carbon black. ,
Therefore, the present invention relates to an oil-based pigment ink composition which is useful as an ink composition for a core-type marking pen in which an ink is occluded in an occlusion body made of felt or a fiber bundle and the ink is led out to a pen tip.

Furthermore, the present invention relates to such oily pigment ink compositions which can be of little toxicity.

2. Description of the Related Art Conventionally, most of marking pens widely used as writing instruments hold an ink composition, and as an occlusion body or a pen tip for controlling the outflow from the pen tip,
A resin-processed felt or other fiber, or a rod made of a synthetic resin having an ink distribution gap in the axial direction is used. Therefore, a black oil-based ink composition for such a marking pen is used. As a conventional method, most of them have been prepared by dissolving a black dye in a solvent. When a pigment is used as the colorant instead of the dye, the pigment particles aggregate with time to form coarse particles, which are allowed to settle in the ink composition, or a nib made of felt or the like is used. It is difficult to pass, especially because the handwriting at the beginning of writing is extremely thin or even writing is impossible.

Furthermore, the marking pen ink composition using a black dye as a colorant has a low handwriting fastness to sunlight, and in particular, easily fades when exposed to the outdoors.

Therefore, conventionally, in order to solve the above problems, for example, Japanese Patent Publication No. 52-1332 discloses an oil-based ink composition for a marking pen, which is obtained by dispersing a resin-processed black pigment in an organic solvent. However, since the resin-processed pigment is expensive, its manufacturing cost is inevitably high.

Further, JP-A-62-207377 describes an ink composition for oil-based marking pens that can use carbon black as a colorant, but it is possible to improve the fine dispersion stability of the ink composition of carbon black. However, the above-mentioned problems have not been solved yet.

In particular, in conventional ink compositions for oil-based marking pens in which conventional carbon black can be used as a colorant, the carbon black in the ink composition is generally used only as relatively large particles having an average particle size of 0.16 to 0.30 μm. Since it is dispersed, when the marking pen is left stationary with its pen tip facing up and then used for writing, the carbon black is settled in the ink chamber, and the handwriting density is extremely low. When the amount of carbon black is increased in order to increase the handwriting density, the viscosity of the ink composition becomes excessively high, which makes it difficult to pass through the felt or closes the felt.

On the other hand, JP-A-61-200183 discloses an aqueous ink composition for a ballpoint pen, in which a carbon black is dispersed in an aqueous solvent using a phthalocyanine compound and a protective colloid. The fine dispersion stability of the carbon black is still insufficient.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention has been made in order to solve the above-mentioned various problems in the ink composition for a core type marking pen using carbon black as a coloring agent, and Excellent in fine dispersion stability.For example, not only can you obtain sufficient handwriting density immediately after writing with the pen tip facing up for a long period of time, but also the adhesion to the writing surface and light resistance. It is an object of the present invention to provide an oil-based pigment ink composition for a core type marking pen, which has excellent properties and can be hardly poisoned.

MEANS FOR SOLVING THE PROBLEMS The present invention is an oil-based pigment ink composition for a core-type marking pen in which the ink composition is occluded in an ink occluding body made of a felt or a fiber bundle, and the ink composition is led out to a pen tip. In the compound, an organic solvent, a carbon black, and a resin (excluding polyvinyl butyral resin) are contained, and further, an aliphatic lower alcohol having 4 or less carbon atoms, ethylene glycol monoalkyl ether and propylene glycol monoalkyl ether (however, alkyl The number of carbon atoms in the group is 1 to 4
Is. The carbon black having a volatile content of 5% or more and a primary particle size of 30 mμ or less is dispersed as fine particles having an average particle size of 0.10 μm or less in a solvent selected from at least one of the above).

The carbon black used in the ink composition according to the present invention has a volatile content of 5% or more and a primary particle size of 30 μm or less, and has an average particle size of 0.10 in the ink composition.
It is stably dispersed as fine particles of μm or less. When the volatile content is less than 5%, the average particle size in the solvent is 0.10μ
It is difficult to disperse it as fine particles of m or less, and as a result, the carbon black settles in the ink composition over time, for example, the felt is clogged, or the ink composition becomes non-uniform, making writing difficult. Or, reduce the initial density of writing. Particularly, in the present invention, a channel black is preferably used as a carbon black.

In the present invention, the volatile content of carbon black is DIN5
According to 1720, it means the value measured by heating a sample at 950 ° C. for 7 minutes in the absence of oxygen.

In the present invention, such a carbon black is contained in an amount of 3 to 15% by weight, preferably 5 to 10% by weight, based on the ink composition.
It is compounded in the range of weight%. When the blending amount of the carbon black is more than 15% by weight in the ink composition, the fluidity of the ink composition may be poor, or the carbon black may aggregate. On the other hand, when the blending amount of carbon black is less than 3% by weight in the ink composition, the handwriting density when writing is not sufficient.

In the ink composition according to the present invention, the solvent is an aliphatic lower alcohol having 4 or less carbon atoms, ethylene glycol monoalkyl ether and propylene glycol monoalkyl ether (provided that the alkyl group has 1 to 4 carbon atoms). It is selected from at least one kind. Examples of the aliphatic lower alcohol having 4 or less carbon atoms include methanol, ethanol, isopropanol and the like. Examples of the ethylene glycol monoalkyl ether and propylene glycol monoalkyl ether include ethylene glycol methyl ether, ethyl ether and butyl ether, propylene glycol methyl ether, ethyl ether and butyl ether.

In the present invention, the use of such a solvent is essential in order to use the carbon black having a volatile content of 5% or more and to secure the fine dispersion stability of the carbon black as described above. Further, among the above-mentioned solvents, particularly when ethanol, propylene glycol monomethyl ether or a mixture thereof is used, an ink composition having extremely low toxicity can be obtained. The volatile content of the carbon black is related to the amount of functional groups such as carboxyl group, hydroxyl group, and carbonyl group that the carbon black has on its surface, and the high volatile content means that the amount of such functional group is large. Therefore, the present invention, although not limited by theory, has a high volatile content, and therefore, a highly polar carbon black is dispersed in a polar organic solvent having a hydroxyl group as described above. It seems that the carbon black can be finely and stably dispersed in the ink composition.

In the present invention, the organic solvent is added in the ink composition in an amount of 50 to 95% by weight, preferably 60 to 85% by weight. When the content of the solvent is more than 95% by weight in the ink composition, the handwriting concentration of the ink composition is usually insufficient, while when it is less than 50% by weight, the ink composition has poor fluidity. , Writability deteriorates.

However, in the ink composition according to the present invention, in addition to the above, as a solvent, acetate of the above ethylene glycol monoalkyl ether, acetate of the above propylene glycol monoalkyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol It is acceptable to use a small amount of propylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate or the like.

Furthermore, conventionally, diethylene glycol monomethyl ether, which has been used as a solvent in oil-based ink compositions,
It is acceptable to use a small amount of diethylene glycol monoethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether or the like.

In the present invention, a resin is dissolved and blended in the ink composition in order to enhance the dispersibility of the carbon black and enhance the adhesion of the handwriting to the writing surface. The resin is not particularly limited as long as it dissolves in the solvent used, but for example, polymethacrylic acid ester resin, polyacrylic acid ester resin, acrylic acid ester-acrylic acid copolymer resin, polyvinylpyrrolidone, etc. Vinyl resins (excluding polyvinyl butyral resin),
Hydrocarbon resin, phenol resin, xylene resin, ketone resin, alkyd resin, polyamide resin, polyester resin, maleic acid resin, cellulose resin, rosin resin, etc., gelatin, casein, cerac, etc., one of natural and synthetic resins Alternatively, two or more kinds are used. The content of these resins in the ink composition is usually 0.5 to 30% by weight, preferably 1 to 20% by weight. This is because when the content of the resin in the ink composition is less than 0.5% by weight, the dispersion stability of carbon black in the ink composition is inferior and the handwriting when writing is inferior.

Further, the ink composition may contain various dispersants in order to enhance the stability of fine dispersion of carbon black. Examples of such dispersants include nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyalkyl phenyl ether, polyoxyethylene fatty acid ester, polyoxyethylene polyoxypropylene block copolymer, and higher alcohol sulfuric acid. Examples thereof include anionic surfactants such as sulfonated ester salts, sulfated ester salts of polyoxyethylene adducts, alkyl sulfated salts of fatty acid alkylamides, and cationic surfactants such as higher alkylammonium halides.

In the present invention, these surfactants are generally blended in the ink composition in an amount of 20% by weight or less, preferably 15% by weight or less.

Further, in the present invention, a phthalocyanine compound can be used as a dispersant and / or as a color adjusting agent for the ink composition. Such a phthalocyanine compound is already known, and in the present invention, for example, it is described in JP-B-51-29899, U.S. Pat.No. 4,313,766, JP-A-58-167654, etc. What is present can be used appropriately. Such a phthalocyanine compound is used in the ink composition according to the present invention in an amount of 15% by weight or less, preferably 10% by weight or less, if necessary.

The method for producing the ink composition according to the present invention may be the same as the method for producing a conventional marking pen ink composition.
For example, carbon black, a resin, a solvent and a dispersant are mixed and stirred using a stirrer, and then kneaded by a ball mill, a roll mill or the like, and further, if necessary, a resin, a solvent,
It is produced by re-adding a dispersant and the like and mixing and stirring. Coarse particles may be removed by filtration at any step of the above steps or as a final step.

Effects of the Invention As described above, the oil-based pigment ink composition for writing according to the present invention uses a carbon black having a predetermined primary particle size and a volatile content as a black colorant, and has a hydroxyl group as its dispersion medium. In the ink composition, a predetermined polar organic solvent is used, and the carbon black is stably dispersed as fine particles having an average particle diameter of 0.10 μm or less.

Therefore, the oil-based pigment ink composition for a core type marking pen according to the present invention has a fine and stable carbon black in the ink composition even after writing, for example, after leaving the pen tip up for a long time. Since it is dispersed in, it is possible to obtain a sufficient handwriting density immediately. For example, even if the pen is left for a long period of time and then written, a sufficient black density can be obtained immediately because the carbon black is finely and stably dispersed in the ink composition.

Further, in the present invention, as the solvent, for example, ethanol, propylene glycol monoethyl ether, etc.,
An ink composition with high safety can be obtained by selecting and using one having almost no toxicity.

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

 The following were used as carbon black.

Carbon black A (Channel black) Primary particle size 13mμ Volatile content 21.0% Carbon black B (Channel black) Primary particle size 20μm Volatile content 15.0% Carbon black C (Furness black) Primary particle size 18mμ Volatile content 3.0% Carbon black D (Channel black) Primary particle size 35mμ Volatile content 6.0% Carbon black E (Channel black) Primary particle size 40mμ Volatile content 0.7% Ink composition with the composition shown in Table 1 using each of these carbon blacks Was prepared and its characteristics are shown in Table 1.

In Table 1, the average particle size of the carbon black in the ink composition was measured by a light transmission type centrifugal sedimentation method,
The viscosity was measured at 20 ° C. with a B type viscometer. Further, the upright test is to fill the ink chamber of the core type marking pen with the ink composition, and leave it with the pen tip upward at room temperature for a predetermined period, and then write a writing line on Kent paper, which is This is a test to measure the concentration with a densitometer or (photograph) densitometer.

All of the ink compositions shown in Table 1 have excellent adhesion to the writing surface, but as is clear from the results shown in Table 1, the ink compositions according to Comparative Examples 1 to 3 have volatile components. Is less than 5.0% and / or the primary particle meter has a carbon black of more than 30 mμ, and therefore the handwriting is significantly reduced with time in the upright test. On the other hand, in the ink composition according to the present invention, the handwriting density is hardly reduced even after the erecting test for a long period of time.

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Claims (1)

[Claims] 1. An oil-based pigment ink composition for a core-type marking pen in which an ink composition is occluded in an ink occluding body composed of a felt or a fiber bundle, and the ink composition is led out to a pen tip. It contains a black and a resin (excluding polyvinyl butyral resin), and further contains an aliphatic lower alcohol having 4 or less carbon atoms, ethylene glycol monoalkyl ether and propylene glycol monoalkyl ether (provided that the alkyl group has 1 to 10 carbon atoms). Four
Is. ) In a solvent selected from at least one kind, a carbon black having a volatile content of 5% or more and a primary particle size of 30 mμ or less is dispersed as fine particles having an average particle size of 0.10 μm or less. Oil-based pigment ink composition for use.