JP2001192595A - Oil-based black pigment dispersion for writing implement ink, and oil-based black pigment writing implement ink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare an oil-based black pigment writing implement ink excellent in writability without thinning or blurring of handwriting and excellent in stability over time without thickening of ink or aggregation of pigment. To provide an oily black pigment dispersion for writing implement ink. An alcohol-based high-boiling organic solvent having a boiling point of 150 ° C. or higher at normal pressure, a pigment-dispersed resin dissolved in the high-boiling organic solvent, and carbon black dispersed in the high-boiling organic solvent Wherein the compounding ratio of the carbon black and the pigment-dispersed resin (carbon black / resin) is in the range of 0.5 to 5, and the average particle diameter of the carbon black is 130 to 180 nm. Black pigment dispersion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oily black pigment dispersion for writing inks and an oily black pigment writing ink, and more particularly to an oily black pigment dispersion for ballpoint pen inks.
And an oil-based black pigment ballpoint pen ink.

[0002]

2. Description of the Related Art Ballpoint pens have been widely used as writing instruments because of their extremely smooth writing. The pen tip (tip) of the ball-point pen is composed of a ball, a seat for supporting the ball, an ink guide hole for guiding ink from the ink storage tube to the ball, and the like. When writing with a ballpoint pen, first, ink adheres to the ball in the chip, and the ink is transferred to the paper as needed by rotating the ball.

[0003] Due to the writing mechanism peculiar to such a ball-point pen, in a ball-point pen tip, it is necessary for the ink to smoothly move to the space between the ball and the receiving seat. If the smooth movement of the ink in the space is hindered, the adhesion of the ink to the ball becomes uneven or intermittent, so that the smooth writing quality of the ballpoint pen is impaired and writing defects such as blurring may occur.

[0004] Oil-based ballpoint pen inks are generally viscous compositions containing an organic solvent, a colorant, a lubricant, a viscosity modifier, a fixability-imparting agent, etc., and many types are known. As a colorant for ballpoint pen ink,
Colorants that dissolve in organic solvents, that is, dyes, have been mainly used in the past.

[0005] This is because the use of a colorant that does not dissolve in an organic solvent, such as a pigment, changes the viscosity of the ink when the pigment is coagulated and settles, so that the ink in the space between the ball and the receiver is smoothly dispersed. This is because there is a high possibility that flow is inhibited. Further, when the pigment particles become coarse, the writing quality becomes poor or writing becomes impossible due to the phenomenon of ball abrasion due to collision with the ball.

That is, in the pigment ink, since the colorant is not dissolved in the solvent but is dispersed, there is an essential problem that the colorant is easily coagulated and settled as compared with the dye ink in which the colorant is dissolved in the solvent. Have. As a result, pigment inks have lower storage stability than dye inks, and tend to aggregate and settle or thicken pigments over time. Has been considered inappropriate.

However, in recent years, pigments have begun to attract attention in place of dyes in order to impart light resistance and water resistance to handwriting.
For oil-based ballpoint pens, pigment inks using a pigment as a colorant have been desired. For example, Japanese Patent Application Laid-Open Nos. 1-135881, 2-233785 and 7-268.
No. 268 describes a ballpoint pen ink containing carbon black as a coloring agent.

However, in these ballpoint pen inks, the carbon black particles dispersed therein tend to aggregate, coarsen, and settle, and as a result, the ink itself tends to thicken. Insufficient stability.

When a pigment is used as a colorant for an ink,
It is necessary to previously disperse and stabilize in an organic solvent using a disperser in the presence of various resins, polymer dispersants or surfactants. However, these are accompanied by problems such as sedimentation and aggregation of the pigment over time, or increase in the viscosity of the pigment ink, and imparting excellent dispersion stability is an important point in the formulation design. ing.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems. It is an object of the present invention to provide a carbon black having a good dispersion stability in an alcohol-based high-boiling organic solvent as a black pigment. An object of the present invention is to provide a black pigment dispersion in which black particles are selected and the pigment particles are not aggregated or settled with the lapse of time by using black. Also, by using the pigment dispersion, the handwriting is thin,
An object of the present invention is to provide an oil-based black pigment writing implement ink which has good writing properties without being blurred, and has excellent temporal dispersion stability without thickening of the ink or aggregation of the pigment.

[0011]

SUMMARY OF THE INVENTION The present invention relates to a method for producing a semiconductor device at 150
Containing an alcohol-based high-boiling organic solvent having a boiling point of at least 0 ° C., a pigment-dispersed resin dissolved in the high-boiling organic solvent, and carbon black dispersed in the high-boiling organic solvent,
The compounding ratio of the carbon black to the pigment dispersion resin (carbon black / resin) is in the range of 0.5 to 5, and the average particle diameter of the carbon black is 130 to 180 n.
m, wherein the oil-based black pigment dispersion for writing implement inks is provided, whereby the object is achieved.

The oil-based black pigment dispersion for a writing instrument ink of the present invention that achieves the above object is a pigment dispersion comprising an organic solvent, carbon black, and a pigment dispersion resin dissolved in the organic solvent, wherein the organic solvent is Contains one or more high-boiling organic solvents having a boiling point of 150 ° C. or higher at normal pressure,
The compounding ratio of carbon black and resin (carbon black / resin) is in the range of 0.5 to 5, and the initial average particle diameter immediately after dispersion of carbon black is 130 nm to 18
0 nm, and the pigment dispersion resin has a softening point of 100 to 135 ° C.
And the K content (potassium content) in the pigment dispersion is preferably 200 ppm or less.

That is, the present inventors have found that in a pigment dispersion comprising an organic solvent, carbon black, and a pigment dispersion resin soluble in the organic solvent, the organic solvent has a boiling point of 150 ° C. or more at normal pressure. One or two high boiling organic solvents
At least one kind of carbon black having a specific average particle diameter and a specific type of pigment-dispersed resin, and specifying the mixing ratio of the carbon black and the resin, more preferably the amount of K (the amount of potassium) contained in the dispersion. ) Is 200 ppm or less, the pigment particles aggregate over time,
It has been found that a black pigment dispersion having good dispersion stability can be obtained without sedimentation.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A first aspect of the present invention is an oily black pigment dispersion for a writing implement ink containing an organic solvent, a pigment dispersion resin dissolved in the organic solvent, and a black pigment dispersed in the organic solvent. It is.

The oil-based black pigment dispersion for writing implement inks is
Basically, it is a high-concentration composition of a pigment component of an oil-based black pigment writing implement ink. In general, an oily black pigment writing tool ink is prepared by a known method by adding an appropriate diluting solvent or additive to the oily black pigment dispersion for writing tool ink. In other words, when the oil-based black pigment writing implement ink is used as the final product, the oil-based black pigment dispersion for the writing implement ink is an intermediate composition used for preparing the oil-based black pigment writing implement ink.

Generally, the oil-based black pigment dispersion for writing instrument ink has a solid content of about 15 to 50% by weight,
The oily black pigment writing implement ink is provided by adjusting the amount to 0 to 50% by weight.

As the organic solvent, a general organic solvent used in a writing instrument ink can be used. Preferred organic solvents are alcoholic organic solvents commonly used in ballpoint pen inks. High-boiling organic solvents having a boiling point of 150 ° C. or more at normal pressure are particularly preferred.

Examples include alcohols such as benzyl alcohol, 1-octanol, 2-octanol, α-methylbenzyl alcohol, and the like. Further, ethylene glycol, diethylene glycol, propylene glycol, hexylene glycol, benzyl glycol, ethylene glycol monophenyl Ether (phenyl glycol), dipropylene glycol monomethyl ether,
Dipropylene glycol monoethyl ether, dipropylene glycol monophenyl ether, diethylene glycol monophenyl ether, propylene glycol monophenyl ether, diethylene glycol monobutyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, propylene glycol Glycols such as methyl ether acetate and propylene glycol diacetate and derivatives thereof are exemplified. The above organic solvents may be used alone or in combination of two or more. The use amount thereof is preferably from 50 to 85% by weight based on the total amount of the black pigment dispersion.

It is preferable to use carbon black as the black pigment. The type of carbon black used as a raw material is not particularly limited as long as it is a known commercially available one. Although any of acidic carbon black, neutral carbon black, and alkaline carbon black can be used, those having a pH of 8 to 9.5 are preferred. Further, carbon black as a raw material can be used as it is, but can be desalted and purified. As a desalting and purification method, for example, dispersion in distilled water, filtration and purification, ultrafiltration, and electrodialysis can be used.

The carbon black used as a raw material has a K content (potassium content) of 1000 ppm or less, preferably 500 ppm or less. In general, in the production process of carbon black, an alkali metal salt, particularly a KOH solution, is introduced into a raw material in the production process, and its potassium ion is contained in the final product. Therefore, if the K amount exceeds 1000 ppm, it becomes a nucleus during dispersion to prevent the particles from being disintegrated, and also after dispersion, the particles are agglomerated, and the dispersion system is stabilized. It can not be planned.

This carbon black has a primary particle diameter of 20.
Preferably it is あ る 40 nm. Then, the ratio between the DBP oil absorption of the carbon black and the primary particle diameter (DB
P oil absorption / primary particle diameter ^{(cm 3 / 100g · nm,} 10
m ² / g)) is preferably from 1.0 to 3.5.
When the value of DBP oil absorption / primary particle diameter is less than 1.0,
If the color density of the ink becomes light and exceeds 3.5, coarse particles increase in the ink, causing ball friction and poor writing performance.

[0022] Here, the DBP oil absorption amount, a predetermined amount of carbon black is in a predetermined condition, refers to an amount of absorbing dibutyl phthalate (cm ³ / 100g). In the present invention, the method for measuring the DBP oil absorption is JIS-K62.
The 21A method is used.

Next, the compounding ratio of carbon black and resin (carbon black / resin) is 0.5-5, preferably 1-3. If the compounding ratio of the carbon black and the resin is less than 0.5, there is excess resin other than at least covering the surface of the pigment, and the portion becomes a nucleus and binds with the resin coated with the pigment to increase the viscosity. I will. On the other hand, if it exceeds 5, the resin that only covers the pigment surface is insufficient, and the portion that is not coated with the resin approaches by the van der Waals force and eventually aggregates. Therefore, in order to achieve the stability over time of this pigment dispersion, the mixing ratio of carbon black and resin is 0.5
It is desirably in the range of ~ 5.

As the pigment-dispersed resin, a resin commonly used in ordinary oil-based writing instrument inks can be used. For example, polyvinyl butyral resin, rosin-modified maleic resin, rosin-modified fumaric resin, ketone resin, maleic resin, styrene-maleic resin, terpene-maleic resin, acrylic resin, styrene-acrylic resin, ester gum, xylene resin, Alkyd resin, phenol resin, terpene phenol resin, polyvinylpyrrolidone and the like are used. Preferably, polyvinyl butyral resin, rosin-modified maleic resin, ketone resin, phenol-modified xylene resin, terpene phenol resin are used. These resins may be used alone or in combination of two or more. A particularly preferred pigment dispersion resin is a polyvinyl butyral resin.

In consideration of the long-term storage stability of the pigment dispersion, the softening point of the pigment dispersion resin is preferably from 100 to 135 ° C., more preferably from 105 to 130 ° C., and even more preferably from 105 to 120 ° C. The amount of the pigment-dispersed resin is 5 to 30% by weight, preferably 10 to 20% by weight, based on the total amount of the dispersion.
By using it in the range, improvement in pigment dispersibility and favorable viscosity are adjusted. The most preferred pigment dispersion resin is a polyvinyl butyral resin having a softening point of 100 to 135 ° C.

Specific examples of the polyvinyl butyral resin include BL-1, BL-2, trade names manufactured by Sekisui Chemical Co., Ltd.
BL-S, BX-10, BX-L, BM-1, BM-
2, BM-S, BX-1, BH-3, etc .; or trade names # 2000-L, # 3000-1, manufactured by Denki Kagaku Kogyo Co., Ltd.
# 3000-2, # 3000-4, # 4000-1, #
4000-2 and the like.

Specific examples of the phenol-modified xylene resin include HP-70 and HP-70 manufactured by Mitsubishi Gas Chemical Company.
100, HP-120, HP-150, HP-210,
GHP-160 and the like.

Specific examples of the ketone resin include Hilac 111 and Hilac 22 (trade names, manufactured by Hitachi Chemical Co., Ltd.).
2. Arakawa Chemical Co., Ltd. product name K-90.

Specific examples of the terpene phenol resin include YS POLYSTAR T8 (trade name, manufactured by Yashara Chemical Co., Ltd.).
0, YS polystar T100, YS polystar T11
5, YS polystar T130, YS polystar T14
5, YS Polystar S145, Mighty Ace G12
5, Mighty Ace G150 and the like.

Specific examples of the rosin-modified maleic resin include Tespol 110 (trade name, manufactured by Hitachi Chemical Co., Ltd.).
1, Tes Paul 1103, Tes Paul 1104, Tes Paul 1105, Tes Paul 1150, Tes Paul 115
1, Testpole 1152, Testpole 1155, Testpole 1158, Testpole 1161, and the like.

The oily black pigment dispersion for a writing instrument ink of the present invention can be produced by a known method. A general production method is a method including a step of providing a mixture containing an alcohol-based organic solvent, a pigment dispersion resin, and carbon black; and a step of dispersing the mixture.

A preferred production method is a method of producing by performing a two-stage dispersion process in which coarse dispersion is first performed and then fine dispersion is performed. Because carbon black is quite hard,
As the dispersion order, it is preferable to first disperse the pigment roughly under the condition that requires a large amount of energy, and then to perform the dispersion under the condition that the pigment is finely dispersed.

Examples of the dispersing machine used in the present invention include a ball mill, an attritor, a jet jet mixer, an impeller mill, a colloidal mill, and a sand mill [for example, a bead mill, a sand glider, a super mill, an agitator mill, and a Dyno mill (trade name)]. Mixing, dispersion and pulverization can be performed using a machine. At this time, a mill medium can be used. The material of the mill medium is not particularly limited, and for example, beads made of glass, stainless steel, zircon, or zirconia can be used. The mill medium is 60-95% by volume, especially 75-85% by volume, based on the volume of the mill.
Is preferable.

As a more preferable dispersion method, first, a pigment dispersion including a step of coarsely dispersing the pigment to an average particle diameter of 200 nm or less and a step of finely dispersing the pigment to an average particle diameter of 150 nm or less is obtained. . The coarse dispersion step and the fine dispersion step are performed by changing dispersion conditions. For example, a coarse dispersion uses a disperser or mill medium for coarse dispersion, and a fine dispersion uses a disperser or mill medium for fine dispersion.

A preferred disperser for performing the coarse dispersion step is
There are a bead mill and various sand mills, and the mill medium is preferably zirconia beads having a diameter of 2 mm. Another preferable condition for performing the coarse dispersion step is to set the filling ratio of the mill medium to 75 to 80%.

A preferred disperser for performing the fine dispersion step is
There are bead mills and various sand mills, and the mill medium is preferably zirconia beads having a diameter of 1.5 mm. Another preferable condition for performing the fine dispersion step is to set the filling ratio of the mill medium to 80 to 85%.

In the above-mentioned two-stage dispersion process, for example, in the first stage of coarse dispersion, dispersion is performed with the bead diameter being, for example, 2 mm, and thereafter, the dispersion is performed by replacing the beads with 1.5 mm beads as the second stage dispersion. Do. If it is not easy to replace the beads, pulverization under different conditions, such as putting 2 mm beads in the first stage pulverizer and 1.5 mm beads in the second stage pulverizer The dispersion may be performed by connecting the devices. If the second-stage dispersion is not performed, coarse particles may remain in the dispersion, causing ball abrasion during writing with a ballpoint pen, which may impair smooth writing performance.

The average particle size of the carbon black contained in the dispersion obtained by the above method is 130 to 180 n.
m is preferable. More preferably, the average particle size over time after storage at 50 ° C. for one month is 130 to 180 nm, and the rate of change from the average particle size immediately after dispersion is 15% or less, more preferably 10% or less.

Originally, carbon black did not exist as primary particles but existed as aggregates. Therefore, if the average particle diameter exceeds 180 nm, the diameter of the aggregate becomes large, and when the ink passes through the gap between the tip and the ball at the tip of the ballpoint pen, the pigment particles, that is, the aggregate cause ball abrasion. Conversely, when the average particle diameter is less than 130 nm, the specific surface area increases, the cohesive force between the particles increases, and the viscosity increases.

Even if the average particle size immediately after dispersion and after storage at 50 ° C. for one month is 130 to 180 nm, if the rate of change exceeds 15% with respect to the average particle size immediately after dispersion, the dispersion system Is unstable and the rate of change is still increasing, or the possibility of thickening is very high, which affects writing performance when filled in a ballpoint pen.

The particle size distribution of the dispersion obtained by the above method is desirably that particles having a size of 1 μm or more are 10% by weight or less. Due to the design of the ballpoint pen, the gap where the ballpoint pen ink is ejected from the tip is only a few μm. If more than 10% by weight of coarse particles of 1 μm or more exist, the coarse particles overlap and pass between the ball and the chip. In this case, ball wear occurs. Therefore, by performing dispersion by the above-described dispersion method, coarse particles
It is important to keep the content at most 5% by weight, preferably at most 5% by weight.

The oil-based black pigment dispersion for a writing implement ink of the present invention provides a writing implement ink (for example, a ball-point pen ink) which is hardly thickened or coagulated and sedimented, and is required to have a property that the ink flows smoothly for a long period of time. Shows sufficient stability over time to perform For example, the oily black pigment dispersion for writing instruments of the present invention hardly increases in viscosity even when stored at normal pressure of 50 ° C. for one month. Specifically, the thickening rate in that case is almost 10
% Or less, and the thickening rate does not exceed 20%.

One or more dispersants and rheology control agents (including thickeners) may be used in combination with one another in order to further increase the dispersion stability of the black pigment dispersion under various conditions. The amount of these additives is not limited as long as it does not reduce the physical properties of the pigment dispersion, but is preferably from 0 to 20% by weight, and more preferably from 0 to 10% by weight, as a whole of the pigment dispersion.

Specific examples of the dispersant include Solsperse 12000 and Solsperse 2000 manufactured by Avicia.
0, Solsperse 24000, Solsperse 2700
0, Solsperse 28000, etc .; trade name Dispavic 160 series, Dispavic 1 manufactured by Big Chemie
No. 80 series, Dispavic 2000, Dispavic 2001, etc .; trade name Floren G manufactured by Kyoeisha Chemical Co.
-700, Floren DOPA-17, Floren DO
PA-17HF, Floren DOPA-33 and the like.

Also, anionic surfactants such as fatty acid salts, aromatic sulfonates, higher alcohol sulfates, fatty acid sulfates, alkylallyl sulfonates, etc .; decaglycerin fatty acid esters, hexaglycerin fatty acid esters, polyoxygen Non-ionic surfactants such as ethylene alkyl ethers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene glycerin fatty acid esters, polyoxyethylene polyalkyl ethers, and polyoxyethylene alkylphenyl ethers. May be used.

The rheology control agent may be in any of a scaly shape, a rod (needle) shape, a lump (spherical) shape and a liquid shape, and can be used irrespective of inorganic or organic. In particular,
Examples include inorganic bentonite, smectite, silica, calcium carbonate, and organic urea compounds, amide compounds, urethane compounds, vegetable oils, polyethylene, and acrylic compounds. Although it depends on the amount of addition, inorganic compounds may adversely affect abrasion of balls and seats and writing performance. Therefore, organic compounds are preferable if possible.

A second embodiment of the present invention is an oil-based black pigment writing implement ink containing an organic solvent, a pigment-dispersed resin dissolved in the organic solvent, and a black pigment dispersed in the organic solvent.
This oily black pigment writing implement ink can be prepared by a known method by adding an appropriate organic solvent, resin, additive and the like to the oily black pigment dispersion for writing implement ink of the present invention as described above.

The amount of the black pigment in the oil-based black pigment writing implement ink of the present invention may be an amount suitable for a desired hue or concentration. Problems such as so-called inability to write, etc., occur, in which drawing and ink do not come out and drawing lines cannot be drawn. Conversely, when the amount is small, problems such as poor coloring of handwriting occur. The preferred amount of the pigment is 5 to 5% based on the total pigment ink composition.
It is 30% by weight, preferably 7 to 15% by weight. Also,
Known dyes, inorganic pigments, or organic pigments can be added as long as the intended purpose and effect can be achieved.

The preferred composition of the oil-based black pigment writing implement ink of the present invention comprises: an alcohol-based high-boiling organic solvent having a boiling point of at least 150 ° C. at normal pressure; a pigment-dispersed resin dissolved in the high-boiling organic solvent; A carbon black dispersed in the high-boiling organic solvent, wherein the compounding ratio of the carbon black to the pigment-dispersed resin (carbon black / resin) is in the range of 0.5 to 5; The average particle size is 130 to 180 nm.

In order to further improve the pigment dispersion stability,
The potassium content in the ink is 200 ppm or less, preferably 50 ppm or less. As the pigment-dispersed resin, it is preferable to use one or more resins selected from polyvinyl butyral resin, phenol-modified xylene resin, ketone resin, and terpene phenol resin.
It is particularly preferable to use a pigment dispersion resin having a softening point of 100 to 135 ° C, preferably 105 to 130 ° C, and 105 to 120 ° C.

The organic solvent added for dilution or viscosity adjustment is preferably the organic solvent added to the above-mentioned pigment dispersion, and the total organic solvent is preferably 40 to 90% by weight, and more preferably 50 to 80% by weight based on the total pigment ink. % By weight is more preferred.

A resin can be added for the purpose of improving the fixability of handwriting, adjusting the viscosity, and stabilizing the dispersion of the pigment. For example, ketone resin, xylene resin, polyethylene oxide, rosin derivative, terpene resin, cumarone-indene resin, polyvinyl butyral resin, terpene phenol resin, phenol-modified xylene resin, polyvinyl pyrrolidone, acrylic resin, styrene-acryl resin, Typical pigment-dispersing resins and oligomers such as a styrene-maleic acid resin, a rosin-modified maleic resin, a rosin-modified fumaric resin, and a terpene-maleic acid resin can be given.

For the preparation of the oil-based black pigment writing implement ink of the present invention, various conventionally known methods for producing a writing implement ink can be applied. That is, a writing implement ink composition can be obtained by dispersing the pigment dispersion together with other components using a dispersion mixer.

The dispersion and mixing can be performed by using a dispersing machine such as a sand mill, a ball mill, a homomixer, a bead mill, and a high-speed disper.

The oil-based black pigment writing implement ink of the present invention may further comprise an antioxidant, an ultraviolet absorber,
Various additives such as a lubricant, a preservative, a fungicide, a rust inhibitor, a dispersant, and a rheology control agent may be appropriately selected and used as needed.

Dispersants used for improving writability and stabilizing the dispersion of pigments include Solsperse 12000, Solsperse 20000, Solsperse 27000, Solsperse 24000, Solsperse 28000 (trade name, manufactured by Avicia); Big 160 Series, Dispavic 180 Series, Dispavic 2000, Dispavic 2001
Etc .; brand names manufactured by Kyoeisha Chemical Co., Ltd. Floren G-700, Floren DOPA-17, Floren DOPA-17H
F, Floren DOPA-33 and the like.

Further, anionic surfactants such as fatty acid salts, aromatic sulfonates, higher alcohol sulfates, fatty acid sulfates, alkylallyl sulfonates, etc .; decaglycerin fatty acid esters, hexaglycerin fatty acid esters, polyoxycarboxylic acids, etc. Non-ionic surfactants such as ethylene alkyl ethers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene glycerin fatty acid esters, polyoxyethylene polyalkyl ethers, polyoxyethylene alkyl phenyl ethers, etc. Can be used.

Examples of the above lubricant include castor oil, polyoxyethylene adduct of castor oil, polyoxyethylene alkylamine, molybdenum disulfide and the like.

Examples of the above thickeners include Benton SD-2 and Benton 27 manufactured by NL Chemicals, and TIXOGEL VZ and TIX manufactured by Nissan Gardler Catalysts.
OGELEZ, trade name EX-0101 manufactured by SUD Chemical Co., Ltd.
Silica-based thickeners such as Aerosil 380 and Aerosil COK84 manufactured by Nippon Aerosil Co., Ltd. and Mizukasil P-801 manufactured by Mizusawa Chemical Co .; and Tarlen VA manufactured by Kyoeisha Chemical Co., Ltd. -100,
Tarlen VA-500, Tarlen VA-800, trade names ASA T-1, ASA T-51, AS manufactured by Ito Oil Co., Ltd.
AT-350F and other fatty acid polyamides.

[0060]

According to the black pigment dispersion of the present invention, the mixing ratio of carbon black and resin is adjusted, the initial average particle diameter immediately after the carbon black is dispersed is 130 to 180 nm, and the K content (potassium content) in the dispersion is adjusted. By limiting, carbon black can be uniformly and stably dispersed, has an optimum color tone and fluidity for a ballpoint pen application, and is excellent in various fastnesses such as weather resistance and solvent resistance. In addition, since interaction with the resin used in the present invention works and the dispersion stability with time is excellent, the pigment particles are not aggregated with time and coarse particles are formed, and are not settled in the pigment dispersion. .

The oil-based ink for a ball-point pen using the black pigment dispersion of the present invention has excellent durability and writing feeling, and also has good pigment dispersibility and excellent stability over time. If the writing tip is left upward,
There is no writing failure such as scratches or poor writing due to ball wear.

[0062]

Next, the present invention will be described in detail with reference to examples, but it is needless to say that the present invention is not limited to these examples. In the following description, “parts by weight” is replaced by “parts”.
Abbreviated.

In Examples 1 to 6 and Comparative Examples 1 to 6, production examples of the black pigment dispersion of the present invention will be described.

Example 1 900 g of phenyl glycol and benzyl alcohol 32
In a mixed solvent with 4 g, a polyvinyl butyral resin (trade name: Eslec BL-3, softening point manufactured by Sekisui Chemical Co., Ltd.):
(100 to 110 ° C.), and 216 g was added thereto and dissolved with stirring for about 2 hours. Thereafter, 360 g of carbon black (potassium content: 300 ppm) was added and stirred for about 2 hours. Thereafter, dispersion was carried out for about 1 hour with a horizontal disperser filled with 2 mm beads to prepare an oil-based black pigment dispersion for ballpoint pen ink. The resulting dispersion had good color tone and fluidity.

Measurement of Average Particle Size, Particle Size Distribution and Change Rate of Average Particle Size The particle size of the pigment particles in the dispersion obtained in Example 1 was measured using a laser light scattering type particle size distribution analyzer (trade name: LPA3).
000/3100 (manufactured by Otsuka Electronics Co., Ltd.) (this is set as an initial value), and this dispersion is placed in an oven kept at 50 ° C. for one month, and then similarly. The measurement was performed, and the state of the change over time was determined as a change rate of the average particle diameter as follows. The results are shown in Table 1.

[0066]

## EQU1 ## Average particle diameter change rate = (value after one month−initial value)
÷ (initial value)

Measurement of Change Rate of Viscosity The viscosity of the dispersion obtained in Example 1 was measured using a rotary viscometer (E
HD type) at 25 ° C. (this is used as an initial value). Further, the dispersion was placed in an oven kept at 50 ° C. for one month, and then the measurement was performed in the same manner.
The state of the change over time is determined as the rate of change of the viscosity as follows,
The results are shown in Table 1.

[0068]

## EQU2 ## Viscosity change rate = (value after one month−initial value) ÷ (initial value)

Confirmation of Dispersibility The dispersion obtained in Example 1 was used. After diluting 2-fold with a mixed solvent of phenyl glycol and benzyl alcohol, a small amount was spotted on a preparation. After covering this with a cover glass and allowing it to stand at room temperature for one day, pigment aggregates were confirmed with an optical microscope.

Example 2 900 g of phenyl glycol and benzyl alcohol 32
Polyvinyl butyral resin (trade name: Eslec BL-1, manufactured by Sekisui Chemical Co., Ltd.) in a mixed solvent with 4 g of softening point:
(100 to 110 ° C.), and 216 g was added thereto and dissolved with stirring for about 2 hours. Thereafter, 360 g of carbon black (potassium content: 300 ppm) was added and stirred for about 2 hours. The subsequent dispersion method was the same as in Example 1. The resulting dispersion had good color tone and fluidity.

Table 1 shows the measurement results of the average particle diameter, the particle ratio of 1 μm or more, and the change rate of the viscosity of the oil-based black pigment dispersion for ballpoint pen ink.

Example 3 950 g of phenyl glycol and benzyl alcohol 31
In a mixed solvent with 0 g, polyvinyl butyral resin (trade name: Eslec BL-2, softening point manufactured by Sekisui Chemical Co., Ltd.):
(105-115 ° C.) and dissolved while stirring for about 2 hours. Thereafter, 360 g of carbon black (potassium content: 300 ppm) was added and stirred for about 2 hours. The subsequent dispersion method was the same as in Example 1. The resulting dispersion had good color tone and fluidity.

Table 1 shows the measurement results of the average particle diameter, the particle ratio of 1 μm or more, and the change rate of the viscosity of the oil-based black pigment dispersion for ballpoint pen ink.

Example 4 970 g of phenyl glycol and benzyl alcohol 32
In a mixed solvent with 6 g, a polyvinyl butyral resin (trade name: Eslec BM-1, softening point manufactured by Sekisui Chemical Co., Ltd.):
(110-120 ° C.) and dissolved with stirring for about 2 hours. Thereafter, 360 g of carbon black (potassium content: 300 ppm) was added and stirred for about 2 hours. The subsequent dispersion method was the same as in Example 1. The resulting dispersion had good color tone and fluidity.

Table 1 shows the measurement results of the average particle diameter, the particle rate of 1 μm or more, and the change rate of the viscosity of the oil-based black pigment dispersion for ballpoint pen ink.

Example 5 970 g of phenyl glycol and benzyl alcohol 32
In a mixed solvent with 6 g, a polyvinyl butyral resin (trade name: Eslec BL-2, softening point manufactured by Sekisui Chemical Co., Ltd.):
(105-115 [deg.] C.) and dissolved with stirring for about 2 hours. Thereafter, 360 g of carbon black (potassium content: 900 ppm) was added and stirred for about 2 hours. The subsequent dispersion method was the same as in Example 1. The resulting dispersion had good color tone and fluidity as in the examples.

Table 1 shows the measurement results of the average particle diameter, the particle ratio of 1 μm or more, and the change rate of the viscosity of the oil-based black pigment dispersion for ballpoint pen ink.

Example 6 900 g of phenyl glycol and benzyl alcohol 32
In a mixed solvent with 4 g, a polyvinyl butyral resin (trade name: Eslec BL-3, softening point manufactured by Sekisui Chemical Co., Ltd.):
(100 to 110 ° C.), and 216 g was added thereto and dissolved with stirring for about 2 hours. Thereafter, 360 g of carbon black (potassium content: 300 ppm) was added and stirred for about 2 hours. Thereafter, dispersion was carried out for about 1 hour by a horizontal dispersing machine filled with 2 mm beads, and then further replaced with 1.5 mm beads for about 30 minutes. The obtained dispersion had good color tone and fluidity similarly to Example 1.

Table 1 shows the measurement results of the average particle diameter, the particle ratio of 1 μm or more, and the change rate of the viscosity of the oil-based black pigment dispersion for ballpoint pen ink.

Comparative Example 1 900 g of phenyl glycol and benzyl alcohol 32
In a mixed solvent with 4 g, a polyvinyl butyral resin (trade name: Eslec BL-3, softening point manufactured by Sekisui Chemical Co., Ltd.):
(100 to 110 ° C.), and 216 g was added thereto and dissolved with stirring for about 2 hours. Thereafter, 360 g of carbon black (potassium content: 1200 ppm) was added and stirred for about 2 hours. The subsequent dispersion method was the same as in Example 1. The resulting dispersion had good color tone and fluidity as in the examples.

Table 1 shows the measurement results of the average particle diameter, the particle ratio of 1 μm or more, and the change rate of the viscosity of the oil-based black pigment dispersion for ballpoint pen ink.

Comparative Example 2 470 g of phenyl glycol and benzyl alcohol 16
In a mixed solvent with 0 g, a polyvinyl butyral resin (trade name: Eslec BL-1, softening point manufactured by Sekisui Chemical Co., Ltd.):
(100 to 110 ° C.), and 810 g was added and dissolved with stirring for about 2 hours. Thereafter, 360 g of carbon black (potassium content: 300 ppm) was added and stirred for about 2 hours. The subsequent dispersion method was the same as in Example 1. The resulting dispersion had no problem with the color tone, but did not have good fluidity.

Table 1 shows the measurement results of the average particle diameter, the particle ratio of 1 μm or more, and the change rate of the viscosity of the oil-based black pigment dispersion for ballpoint pen ink.

Comparative Example 3 1000 g of phenyl glycol and benzyl alcohol 3
In a mixed solvent with 86 g, 54 g of polyvinyl butyral resin (trade name: Eslec BL-1, softening point: 100 to 110 ° C., manufactured by Sekisui Chemical Co., Ltd.) was added and dissolved with stirring for about 2 hours. Thereafter, 360 g of carbon black (potassium content: 300 ppm) was added and stirred for about 2 hours. The subsequent dispersion method was the same as in Example 1. The resulting dispersion had no problem with color tone, but had poor fluidity immediately after dispersion, and eventually thickened.

Table 1 shows the measurement results of the average particle diameter, the particle ratio of 1 μm or more, and the change rate of the viscosity of the oil-based black pigment dispersion for ballpoint pen ink.

Comparative Example 4 800 g of phenyl glycol and benzyl alcohol 28
Phenol-modified xylene resin (trade name: HP-120, manufactured by Mitsubishi Gas Chemical Co., Ltd.) in a mixed solvent with 0 g.
(125-135 ° C) 360 g was added and dissolved with stirring for about 2 hours. Thereafter, 360 g of carbon black (potassium content: 300 ppm) was added and stirred for about 2 hours. The subsequent dispersion method was the same as in Example 1. The resulting dispersion had no problem with the color tone, but had almost no fluidity.

Table 1 shows the measurement results of the average particle diameter, the particle ratio of 1 μm or more, and the change rate of the viscosity of the oil-based black pigment dispersion for ballpoint pen ink.

Comparative Example 5 860 g of phenyl glycol and 29 of benzyl alcohol
Terpene phenolic resin (trade name: YS Polystar N125, manufactured by Yashara Chemical Co., Ltd.)
(Softening point: 120-130 ° C.) and 288 g thereof were added and dissolved with stirring for about 2 hours. Thereafter, 360 g of carbon black (potassium content: 300 ppm) was added and stirred for about 2 hours. The subsequent dispersion method was the same as in Example 1. The resulting dispersion had no problem with the color tone, but had almost no fluidity.

Table 1 shows the measurement results of the average particle diameter, the particle ratio of 1 μm or more, and the change rate of the viscosity of the oil-based black pigment dispersion for ballpoint pen ink.

Comparative Example 6 780 g of phenyl glycol and benzyl alcohol 26
0 g of a ketone resin (trade name: Hilac 222, manufactured by Hitachi Chemical Co., Ltd., softening point: 100 to 120)
400 ° C.) and dissolved with stirring for about 2 hours. Then, carbon black (potassium amount 300pp
m) 360 g was added and stirred for about 2 hours. The subsequent dispersion method was the same as in Example 1. The resulting dispersion had no problem with the color tone, but had almost no fluidity.

Table 1 shows the measurement results of the average particle diameter, the particle ratio of 1 μm or more, and the change rate of the viscosity of the oil-based black pigment dispersion for ballpoint pen ink.

[0092]

[Table 1]

In Examples 7 to 12 and Comparative Examples 7 to 12, oily black pigment ballpoint pen inks using the oily black pigment dispersion liquid for ballpoint pen inks of the present invention will be described.

Example 7 50 parts of the black pigment dispersion obtained in Example 1, 25 parts of phenyl glycol, 10 parts of benzyl alcohol, 5 parts of a rosin-modified phenol resin (softening point: 110 to 115 ° C.),
An oily black pigment ballpoint pen ink was prepared by dispersing and mixing 5 parts of a ketone resin (softening point: 100 to 120 ° C.), 1 part of polyvinylpyrrolidone, and 4 parts of oleic acid.

The ink obtained above was filled in a ball-point pen comprising a cemented carbide ball having a diameter of 0.7 mm, a stainless steel tip and a storage tube to obtain an oil-based ball-point pen. When writing with the ballpoint pen, it showed smooth and good writability. Then, after leaving it for 1 month in a 50 ° C. constant temperature bath with the writing tip facing upward, it was left at room temperature for 1 day to obtain a writing angle of 70 °.
°, a straight handwriting was performed with a load of 100 g, and the fray length at that time was measured. The results are shown in Table 2.

The oil-based ballpoint pen obtained above was written on a writing tester under the conditions of a load of 100 g, a writing angle of 70 ° and a writing speed of 4 m / min in accordance with JIS S6039.
The amount of wear of the ball after 500 m of writing was measured using an optical microscope, and a handwriting test was performed by handwriting. The results are shown in Table 2.

Examples 8 to 12 In Examples 8 to 12, oil-based black pigment ballpoint pen inks were prepared in the same manner as in Example 7 using the black pigment dispersions obtained in Examples 2 to 6, respectively. Each of the obtained inks showed a good color tone, the viscosity of the ink was stable without aggregation and sedimentation of the pigment, and good writing properties were obtained at the initial stage and over time.

Comparative Examples 7 and 8 In Comparative Examples 7 and 8, oil-based black pigment ballpoint pen inks were prepared in the same manner as in Example 7 using the black pigment dispersions obtained in Comparative Examples 1 and 2, respectively. The resulting inks each had a good color tone, but a satisfactory writing feeling could not be obtained due to abrasion of the ball in a writing test.

Comparative Examples 9 to 12 In Comparative Examples 9 to 12, since the black pigment dispersions obtained in Comparative Examples 3 to 6 each had a significant increase in viscosity, the ink formulation of Example 7 and the mixing ratio thereof were changed. However, the obtained black pigment ink was slightly thick, and could not be filled in a ballpoint pen.

Examples 13 and 14 illustrate the oil-based black pigment ballpoint pen ink of the present invention.

Example 13 600 g of phenyl glycol and benzyl alcohol 42
In a mixed solvent with 0 g, a polyvinyl butyral resin (trade name: Eslec BL-1, softening point manufactured by Sekisui Chemical Co., Ltd.):
180 g, rosin-modified phenol resin (softening point: 110-115 ° C.) 150 g, ketone resin (softening point: 100-120 ° C.) 150 g, oleic acid 1
20 g and polyvinylpyrrolidone 30 g were added and dissolved under stirring for about 2 hours. Thereafter, 300 g of carbon black (potassium content: 300 ppm) was added and stirred for about 2 hours. Thereafter, dispersion was performed for about 30 minutes using a horizontal dispersing machine filled with 2 mm beads, and then dilution was performed with 750 g of phenyl glycol and 300 g of benzyl alcohol to prepare an oil-based black pigment ballpoint pen ink. The obtained ink had good color tone and fluidity.

Example 14 630 g of phenyl glycol and benzyl alcohol 42
In a mixed solvent with 0 g, a polyvinyl butyral resin (trade name: Eslec BL-1, softening point manufactured by Sekisui Chemical Co., Ltd.):
100-110 ° C) 150 g, rosin-modified phenol resin (softening point: 110-115 ° C) 150 g, ketone resin (softening point: 100-120 ° C) 150 g, oleic acid 1
20 g and polyvinylpyrrolidone 30 g were added and dissolved under stirring for about 2 hours. Thereafter, 300 g of carbon black (potassium content: 300 ppm) was added and stirred for about 2 hours. Thereafter, dispersion was performed for about 30 minutes using a horizontal dispersing machine filled with 2 mm beads, and then dilution was performed with 750 g of phenyl glycol and 300 g of benzyl alcohol to prepare an oil-based black pigment ballpoint pen ink. The obtained ink had good color tone and fluidity.

The ink obtained above was filled into a ballpoint pen comprising a cemented carbide ball having a diameter of 0.7 mm, a stainless steel tip and a storage tube to obtain an oil-based ballpoint pen. When writing with the ballpoint pen, it showed smooth and good writability. Then, after leaving it for 1 month in a 50 ° C. constant temperature bath with the writing tip facing upward, it was left at room temperature for 1 day to obtain a writing angle of 70 °.
°, a straight line was written with a load of 100 g, and the fray length at that time was measured. The results are shown in Table 2.

The oil-based ballpoint pen obtained above was written with a writing tester in accordance with JIS S6039 under the conditions of a load of 100 g, a writing angle of 70 °, and a writing speed of 4 m / min.
The amount of ball abrasion after 00m writing was measured using an optical microscope, a handwriting test was performed by handwriting, and the results are shown in Table 2.
It was shown to.

[0105]

[Table 2]

Claims (13)

[Claims] An alcohol-based high-boiling organic solvent having a boiling point of 150 ° C. or more at normal pressure, a pigment-dispersed resin dissolved in the high-boiling organic solvent, and carbon black dispersed in the high-boiling organic solvent And a blending ratio of the carbon black and the pigment-dispersed resin (carbon black / resin) is in the range of 0.5 to 5, and the carbon black has an average particle size of 130 to 180 nm. Oily black pigment dispersion. 2. The pigment-dispersed resin has a softening point of 100 to 1
The oily black pigment dispersion according to claim 1, which is at 35 ° C. 3. The oily black pigment dispersion according to claim 1, wherein the pigment dispersion resin is a polyvinyl butyral resin. 4. The oily black pigment dispersion according to claim 1, wherein the amount of potassium contained in the carbon black is 1,000 ppm or less. 5. The carbon black having a primary particle size of 2
The oily black pigment dispersion according to claim 1, wherein the dispersion is from 0 to 40 nm, and the ratio of the DBP oil absorption to the primary particle diameter (DBP oil absorption / primary particle diameter) is 1.0 to 3.5. 6. The pH of the carbon black is from 8 to 9.
5. The oily black pigment dispersion according to claim 1, which is 5. 7. The oily black pigment dispersion according to claim 1, wherein the potassium content is 200 ppm or less. 8. The average particle size of carbon black after storage at normal pressure of 50 ° C. for one month is 130 to 180 nm, and the average particle size after storage at normal pressure of 50 ° C. for one month relative to the average particle size immediately after dispersion. The oily black pigment dispersion according to any one of claims 1 to 7, wherein a change rate of the oily black pigment is 15% or less. 9. The content of the carbon black having a particle size of 1 μm or more is 10% by weight or less.
The oily black pigment dispersion according to any one of the above. 10. The oily black pigment dispersion according to claim 1, which has a viscosity increase of 20% or less after storage at normal pressure of 50 ° C. for one month. 11. A step of providing a mixture containing an alcohol-based high-boiling organic solvent having a boiling point of 150 ° C. or more at normal pressure, a pigment-dispersed resin, and carbon black; A process for dispersing the mixture using a milling medium for fine dispersion; and a method for producing an oil-based black pigment dispersion for a writing instrument ink. 12. An oily black pigment writing implement ink comprising at least the oily black pigment dispersion for a writing implement ink according to claim 1 and an alcoholic high boiling organic solvent having a boiling point of 150 ° C. or higher at normal pressure. 13. An alcohol-based high-boiling organic solvent having a boiling point of 150 ° C. or more at normal pressure, a pigment-dispersed resin dissolved in the high-boiling organic solvent, and carbon black dispersed in the high-boiling organic solvent And a blending ratio of the carbon black and the pigment-dispersed resin (carbon black / resin) is in the range of 0.5 to 5, and the carbon black has an average particle size of 130 to 180 nm. Oily black pigment dispersion.