JP2001172541A - Writing ink composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide writing ink compositions possessing high safety and, simultaneously, excellent writing properties and stability with time. SOLUTION: The writing ink compositions comprise at least a colorant and a 2-hydroxyisobutyric acid derivative.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a writing ink composition. More specifically, the present invention relates to an ink composition for writing implements that has high safety to the human body and excellent writing characteristics and stability over time.

[0002]

2. Description of the Related Art Conventionally, oil-based inks using an organic solvent have been widely used as inks for writing instruments. However, since oil-based inks are required to be quick-drying, aromatic solvents such as toluene and xylene have been used. There is known an oil-based ink in which a volatile organic solvent such as cellosolve is used as a main solvent, and a coloring agent such as a dye or a pigment is dissolved or dispersed in the solvent. However, in recent years, the effects of these organic solvents on the human body and the environment have begun to be concerned, and relatively low-toxic alcohols, propylene glycol alkyl ethers, and the like have come to be used as solvents for writing implement inks.

However, when a dye is used as a coloring agent,
Since there are few dyes that are sufficiently soluble in these solvents, there are restrictions on the hue as an ink, and when a relatively high-concentration dye is blended to ensure a sufficient concentration as a writing implement ink, There were problems such as precipitation of dye. In addition, when a pigment is used as a colorant, there is a problem in the temporal stability of the ink, such as sedimentation of the pigment over time and an increase in viscosity.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the ink for writing implements, and provides an ink composition for writing implements having high safety, excellent writing characteristics and stability over time. Things.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have solved the above problems by using a 2-hydroxyisobutyric acid derivative, and have high safety. The present inventors have found that an ink composition for a writing instrument having excellent writing characteristics and stability can be obtained, and have completed the present invention. That is, the ink composition for a writing implement of the present invention comprises: (1) an ink composition for a writing implement comprising at least a colorant and a 2-hydroxyisobutyric acid derivative. (2) An ink composition for a writing implement according to claim (1), further comprising a resin.

[0006]

Embodiments of the present invention will be described below in detail. The colorant used in the present invention is not particularly limited as long as it is a colorant usually used in a writing instrument ink composition, and examples thereof include oil-soluble dyes and pigments. Examples of oil-soluble dyes include, for example, azo dyes, salt-forming dyes, metal-containing dyes, anthraquinone dyes, condensation dyes,
And phthalocyanine sulfamide dyes. Specific examples include CISolvent Yellow 2,
6, 14, 14, 15, 16, 19, 21, 2
3, 56, 61, 80, CISolvent Orange
1, 2, 5, 6, 14, 37, 40, 4
4, same 45,

CISolvent Red 1, 3, 8, 8
3, 24, 25, 27, 30, 30, 49, 8
1, 82, 83, 84, 100, 109, 121, CI Disperse Red 9, CISolvent Violet
8, 13, 13, 14, 21, 21, 27, CIDi
sperse Violet 1, CISolvent Blue 2, 11, 11, 25, 35, 36, 55, 73, CI
Solvent Green 3, CISolvent Brown 3, 5, 5
0 and 37.

[0008] Examples of the pigment include organic pigments and inorganic pigments. The pigment may be used as it is, or may be, for example, a treated pigment surface-treated in a pigment production stage, a processed pigment kneaded with a resin or a surfactant, a dispersed toner subjected to a dispersion treatment, or the like. Various pigment dispersants, pigment derivatives, surfactants, and the like may be blended to improve the dispersion stability of the pigment.

Specific examples of pigments include azo lake pigments, insoluble monoazo pigments, insoluble disazo pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, anthraquinone pigments, perylene pigments, perinone pigments, thioindigo pigments, and quinacridone. Pigments, dioxazine pigments, isoindolinone pigments, quinophthalone pigments, dyed lake pigments, carbon black, titanium oxide, red iron oxide, iron black and the like.

These colorants may be used alone or in combination of two or more. The amount of these colorants is not particularly limited as long as a sufficient concentration can be obtained as a writing implement ink composition, but 0.1 to 50 parts by weight, preferably 0.1 to 50 parts by weight, per 100 parts by weight of the writing implement ink composition. It is selected from the range of 5 to 35 parts by weight. If the amount is less than 0.1 part by weight, it is not preferable because a sufficient density cannot be obtained as a writing implement ink, and if it is more than 50 parts by weight, the viscosity of the ink increases and the writing performance is deteriorated.

The 2-hydroxyisobutyric acid derivative used in the present invention is a 2-hydroxyisobutyric acid ester compound represented by the general formula (1). (CH ₃ ) ₂ C (OH) COOR (1) Specifically, 2-hydroxyisobutyric acid methyl ester,
2-hydroxyisobutyric acid ethyl ester, 2-hydroxyisobutyric acid propyl ester, 2-hydroxyisobutyric acid isopropyl ester, 2-hydroxyisobutyric acid n-butyl ester, 2-hydroxyisobutyric acid isobutyl ester, 2-hydroxyisobutyric acid isopentyl ester ,
Ester compounds of 2-hydroxyisobutyric acid and monohydric alcohol such as 2-hydroxyisobutyric acid 2-ethylhexyl ester, and 2-hydroxyisobutyric acid such as ethylene glycol ester and 2-hydroxyisobutyric acid propylene glycol ester. Esters of butyric acid and polyhydric alcohol can be mentioned.

The above-mentioned 2-hydroxyisobutyric acid derivatives may be used alone or in an appropriate combination of two or more. The compounding amount of these 2-hydroxyisobutyric acid derivatives is 100% by weight of the ink composition for writing implements. Parts by weight is selected from the range of 0.1 to 99 parts by weight. Preferably it is selected from the range of 1 to 90 parts by weight. At 0.1 parts by weight or less, it is difficult to obtain the effect of the blending, and at 99 parts by weight or more, the blending amount of other components blended in the ink composition for a writing implement such as a colorant is relatively reduced, and as a writing implement ink. It is not preferable because it becomes difficult to secure the concentration and the fastness of the polymer. The 2-hydroxyisobutyric acid derivative is used as a solvent for the ink composition for a writing instrument of the present invention, but may be used in combination with another organic solvent shown below as needed.

The other solvent which may be used in the present invention is not particularly limited as long as it is an organic solvent usually used for a writing instrument. However, in consideration of the volatility at the time of writing, a solvent having a vapor pressure at 20 ° C. of 1 mmHg or more. Is preferably used. Specific examples include alcohols, glycols, glycol ethers, fatty acid esters, ketones, ethers, aliphatic hydrocarbons, aromatic hydrocarbons and derivatives thereof, preferably alcohols,
Glycol ethers and their derivatives can be mentioned.

Examples of alcohols include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutyl alcohol and t-butyl alcohol. Examples of glycol ethers include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, and propylene glycol monopropyl ether. .

Examples of the derivative include fatty acid ester derivatives of alcohols such as ethyl acetate and butyl acetate, and fatty acid ester derivatives of glycol ethers such as propylene glycol monomethyl ether acetate. These organic solvents may be used alone or in an appropriate combination of two or more kinds. Further, when a 2-hydroxyisobutyric acid derivative is used as a solvent, it may not be blended.

In the present invention, a colorant and a 2-hydroxyisobutyric acid derivative are essential components, but other components which are used in ordinary ink compositions for writing implements can be arbitrarily used. For example, to adjust the viscosity of the ink composition for writing implements, to improve the fixability and water resistance of the colorant to the writing medium, a resin that is usually used may be used, as specific examples, Natural and synthetic resins such as ketone resins, sulfoamide resins, maleic acid resins, ester gums, xylene resins, alkyd resins, phenolic resins, rosins, polyvinylpyrrolidone, polyvinylbutyral, polyvinyl alcohol, acrylic resins, melamine resins, and cellulose resins One or two of these can be used.

In the present invention, components such as a preservative, a fungicide, a rust inhibitor, a lubricant, a pH adjuster, a viscosity adjuster, an anti-settling agent, a dissolution aid, and a surfactant can also be used. . The ink composition for a writing implement of the present invention can be prepared from a predetermined component by various known methods for producing an ink composition for a writing implement. For example, it can be manufactured by a method of uniformly mixing each component with a mixing stirrer, or a method of dispersing and mixing each component using a disperser such as a ball mill, a bead mill, a roll mill, a disper, an ultrasonic classifier, and a high-pressure homogenizer. it can. At this time, all the components may be stirred and mixed or dispersedly mixed at the same time, or each component may be sequentially stirred and mixed or dispersedly mixed.

The viscosity of the ink composition for a writing instrument of the present invention obtained at 25 ° C. is preferably in the range of 1 to 20,000 mPa · s. When the viscosity is less than 1 mPa · s, the penetrating speed on the surface to be written is so high that the ink tends to bleed, which is not preferable. When the viscosity exceeds 20,000 mPa · s, the fluidity of the ink in the writing instrument container deteriorates, and writing characteristics such as fading easily deteriorate. Is not preferred. The ink composition for writing implements of the present invention can be suitably used for ballpoint pens, fountain pens, sign pens, marking pens and the like.

[0019]

EXAMPLES The present invention will be described in more detail with reference to Examples, Comparative Examples and Test Examples of the present invention, but the present invention is not limited by the Examples. However, the parts by weight are parts by weight.

Example 1 The following components were uniformly mixed at 40 ° C. to obtain an ink composition for a writing implement.・ Coloring agent: 6 parts of Varifast Red # 1308 (manufactured by Orient Chemical Industries) ・ Resin: 8 parts of Hilac 110H (manufactured by Hitachi Chemical) ・ Solvent: 86 parts of methyl 2-hydroxyisobutyrate

Example 2 The following components were uniformly mixed at 40 ° C. to obtain an ink composition for a writing implement. Colorant: Varifast Black # 3810 (manufactured by Orient Chemical Industries) 10 parts Resin: Hilac 110H (manufactured by Hitachi Chemical) 10 parts Solvent: methyl 2-hydroxyisobutyrate 60 parts Solvent: ethanol 20 parts

Example 3 The following components were dispersed in a bead mill to obtain an ink composition for writing implements.・ Coloring agent: MA-100 (manufactured by Mitsubishi Chemical) 4 parts ・ Resin: Eslek B BL-1 4 parts ・ Solvent: methyl 2-hydroxyisobutyrate 92 parts

Comparative Example 1 An ink composition for a writing implement was obtained by uniformly mixing similarly in Example 1 except that the solvent (methyl 2-hydroxyisobutyrate) was changed to ethanol.

Comparative Example 2 An ink composition for a writing implement was obtained in the same manner as in Example 2 except that the solvent (methyl 2-hydroxyisobutyrate) was changed to ethanol, followed by uniform mixing.

Comparative Example 3 An ink composition for a writing implement was obtained in the same manner as in Example 3, except that the solvent (methyl 2-hydroxyisobutyrate) was changed to propylene glycol monomethyl ether.

The ink compositions for writing instruments prepared in Examples 1 to 3 and Comparative Examples 1 to 3 described above were filled in a commercially available writing instrument (A-50E manufactured by Mitsubishi Pencil) and written. Also, after leaving the writing implements at room temperature for one day with the cap off,
I wrote it as well. Table 1 shows the evaluation results of the writability.

[0027]

[Table 1]

[0028]

As described above, the ink composition for a writing instrument of the present invention uses a highly safe 2-hydroxyisobutyric acid derivative, and therefore has a very small effect on the human body and the environment, and has a low dye content. Since the ink is excellent in solubility and dispersibility of the pigment, it is possible to provide a writing instrument that is safe and has excellent writing characteristics and stability over time by using this ink composition.

Claims (2)

[Claims] 1. An ink composition for a writing implement comprising at least a colorant and a 2-hydroxyisobutyric acid derivative. 2. The ink composition for a writing implement according to claim 1, further comprising a resin.