JP2001040266A - Water-base pigment ink composition for ball point pen - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pigment ink for ball-point that has excellent long-term stability, causes no ink leakage from the ball point, even when it is allowed to stand for many hours, as the pen point is kept downward. SOLUTION: In a water-base pigment ink composition for ball point pen that mainly comprises a pigment, a pigment dispersant, water, a water-soluble solvent, and a water-soluble polymer resin as essential components, microfine, porous or nonporous and hydrophilic particles of anhydrous silica with a specific surface area of >=250 m2/g according to the BET method are used in an amount of 0.03-0.3 wt.%. In a preferred embodiment, both of a straight-chain polymer having the filament-drawing properties and of a crosslinkable and three- dimensional structure-forming polymer can be used as the water-soluble polymer resin. In addition, the amount of the straight chain polymer that can form filaments is preferably made more than that of the hydrophilic, porous or nonporous, microfine, anhydrous silica.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous ballpoint pen ink using a pigment as a colorant, and more particularly to a pigment, a pigment dispersant, water, a water-soluble solvent and a water-soluble polymer resin. And a pigment ink composition for an aqueous ballpoint pen.

[0002]

2. Description of the Related Art An aqueous pigment ink composition is prepared by dispersing a pigment used as a colorant into fine particles and stably dispersing the pigment.
It is important to make the material excellent in long-term stability. In order to solve this problem, a water-soluble polymer resin is used as an ink viscosity modifier. For example, methyl cellulose,
Ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, straight polymers of water-soluble polymer resins such as polyvinylpyrrolidone, tragacanth gum, guar gum, alginic acid, carrageenan, xanthan gum, dextrin, sodium polyacrylate, carboxyvinyl polymer, polyethylene oxide, poly-N-vinyl Polymers capable of forming a crosslinked three-dimensional structure such as acetamide are exemplified. These ink viscosity modifiers can be used as a mixture of two or more kinds.

However, even when the above-mentioned water-soluble polymer resin is used, depending on the properties of the resin used, if the pen tip is turned down and left for a long time, the ink composition is not retained and the ink leaks from the pen tip. Prevents "leakage," when using an electrolyte polymer, changes the behavior depending on the additives used, such as water-soluble solvents and surfactants, and lowers the ink viscosity, causing bleeding during writing and poor long-term stability There are problems such as.

[0004] In order to solve the above-mentioned problems, for example, a cation-exchangeable synthetic silicate having a smectite structure is added (see JP-A-4-292672), and a fine powder of silicon dioxide and alumina are mixed and added ( JP-A-7-
No. 76665) and those to which magnesium silicate is added (see JP-A-9-328647).
-40 nm and specific surface area (BET method) 50-380 m
² / g of fine particle silica, having a viscosity of 1000 to 50
Oil-based ink for ballpoint pens having a pressure of 00 mpa · s (JP-A-10-204368), and an ink using inorganic fine particles having an average particle diameter of 2 μm or less as a shear thinning agent (JP-A-6-206)
-256699) and the like. However, in the case of the inorganic fine particles used in the ink composition for an aqueous ballpoint pen described in JP-A-6-256699, the stability of the ink is obtained because the surface is lipophilic or the specific surface area is small. It is difficult to make the quality uniform. In addition, the inks disclosed in these publications cause the inorganic substance to be added to cause clogging in a tip which is a pen tip, and as the writing progresses, the concentration of the writing line becomes thinner or writing becomes impossible, and the capillary action occurs. Insufficient problems, such as the inability to use a resin or polymer compound to supply ink using the ink, the ink viscosity is too high, and the ink from the tip of the chip is not easy to use, and it cannot be used for water-based ballpoint pen ink. Does not solve the problem.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and the "tip leakage" does not occur even when the ball-point pen is pointed downward and left for a long time.
An object of the present invention is to provide a water-based pigment ink composition for ball-point pens, which does not generate dents during writing and has stable writing performance without change over time.

[0006]

Means for Solving the Problems As a result of intensive studies on the above problems, the present inventor has found that a composition in which a shear-thinning agent having specific physical properties and a polymer resin are blended at a predetermined ratio is used.
They have found that the above object can be achieved, and have completed the present invention based on this finding. That is, the pigment ink composition for an aqueous ballpoint pen of the present invention comprises the following (1) to
(3). (1) In a pigment ink composition for an aqueous ballpoint pen containing a pigment, a pigment dispersant, water, a water-soluble solvent, and a water-soluble polymer resin as main components, the specific surface area by the BET method is 250 m ^2.
An aqueous pigment ink composition for ballpoint pens, characterized in that the pigment ink composition contains 0.03 to 0.3% by weight of hydrophilic, porous or non-porous fine particles of anhydrous silica having a particle size of at least / g. (2) The ballpoint pen pigment ink composition according to (1), wherein the water-soluble polymer resin contains both a straight polymer having spinnability and a polymer capable of forming a crosslinked three-dimensional structure. (3) The compounding weight of the straight polymer having spinnability is
The pigment ink composition for an aqueous ball-point pen according to the above (1) or (2), wherein the amount is larger than the compounding weight of the hydrophilic, porous or nonporous fine particle anhydrous silica.

[0007]

Embodiments of the present invention will be described below in detail.

[0008] Porous or non-porous fine particles used in the present invention
The surface of the anhydrous silica is hydrophilic, and a ratio table based on the BET method
The area is 250m^Two/ G or more is preferred.
Hydrophobizing the surface of porous or non-porous fine anhydrous silica
With a specific surface area of 250m ^Two/ G of fine particles anhydrous
In Rica, secondary coagulation is likely to occur,
It is not preferable because clogging occurs. The amount is
0.03-0.3% by weight based on the total weight of the ink composition, preferably
Or 0.04 to 0.2% by weight. This hydrophilicity
There is no effect if the content of the fine particle anhydrous silica is too small,
If it exceeds 0.3% by weight, the viscosity becomes too high,
As a result, the flow of ink inside a certain chip is obstructed.
The feeling of writing and writing lines are extremely poor.

The water-soluble polymer resin used in the present invention adjusts the viscosity of the ink composition. A straight polymer having spinnability is used for ink flow along with the rotation of the ball as a pen tip during writing. It has the effect of smoothing out. The polymer capable of forming a crosslinked three-dimensional structure is added in order to more effectively keep the pigment serving as a colorant and the hydrophilic fine particle anhydrous silica in a stable dispersion state for a long period of time. The blending amount is 0.05% by weight of the straight polymer having spinnability, which is required to be greater than that of the hydrophilic fine particle anhydrous silica, based on the total amount of the ink composition.
The above is preferable, and it is preferable to vary the amount of the hydrophilic fine particle anhydrous silica in accordance with the specific surface area. That is, it is necessary to increase the amount of the straight polymer having spinnability as the specific surface area increases.

The amount of the polymer capable of forming a crosslinked three-dimensional structure varies depending on the molecular weight of the polymer used, but is preferably from 0.1% by weight to less than 0.5% by weight.
When the content is 5% by weight or more, the thickening effect of the hydrophilic fine particles of anhydrous silica is added to increase the viscosity, thereby inhibiting the flow of ink.

There is no particular limitation on the pigment used in the present invention, and any pigment can be used from the inorganic and organic pigments used in ordinary pigment inks for aqueous ballpoint pens. Alternatively, a pseudo pigment obtained by emulsion polymerization may be used. The pseudo pigment may be obtained by dyeing an acrylic resin latex with a fluorescent dye, and the type of the pseudo pigment is not particularly limited as long as it can be dispersed well in water. For example, carbon black such as fanest black, contact black, acetylene black, and thermal black; inorganic pigments such as black iron oxide, yellow iron oxide, red iron oxide, ultramarine, navy blue, cobalt blue, and titanium yellow; Black 7, CI Pigment Blue 15, 16, 17, 17, and 22, CI Pigment Red 5, 22, 38, 41, 49, 88,
112, 122, 146, 170, 190,
206, 245, 258, CI Pigment Orange 5, 10, 13, 13, 40, 43,
CI Pigment Violet 19, 23, 31;
36, 50, CI Pigment Brown 25, 2
6, CI Pigment Yellow 3, 12, 12, 13, 24, 81, 95, 97, 108, 110
Organic pigments such as 120, 139, 166, CI Pigment Green 7, 10 and 36, NKW series fluorescent dispersion (manufactured by Nippon Fluorescent Chemical Co., Ltd.), Shinroyhi color paste series fluorescent dispersion (Shinroihi Co., Ltd.
), Nile Color Series Dispersion (Mikuni Color Co., Ltd.)
Pseudo-pigment). The amount of the pigment used in the present invention is 3 to 30% by weight based on the total amount of the ink composition.
Preferably it is 5 to 20% by weight.

As the pigment dispersant used in the present invention, a styrene / acrylic acid copolymer, a maleic acid / styrene copolymer, a neutralized salt thereof and the like can be used.

The water-soluble solvent used in the present invention includes propylene glycol, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, 1,3-butylene glycol, thiodiethylene glycol, glycerin, ethylene glycol monomethyl ether and diethylene glycol monomethyl ether. One or two or more of them can be used in combination, and used in a range of 10 to 40% by weight based on the total amount of the ink composition.

In the pigment ink composition for an aqueous ball-point pen according to the present invention, in addition to the above-mentioned main components, a commonly used p-type ink is used.
It may contain an H adjuster, a rust inhibitor, a lubricant, a surfactant, a preservative, a wetting agent, and the like. Examples of the pH adjuster include triethanolamine, diisopropanolamine, monoethanolamine, triethylamine and the like. Examples of the rust preventive include benzotriazole, tolyltriazole, dicyclohexylammonium nitrate and the like. As the lubricant, an anionic surfactant, an amphoteric surfactant, a nonionic surfactant, or a fluorine-based surfactant can be selected according to the effect. Examples of the preservative include sodium benzoate, potassium sorbate, sodium pentachlorophenol, sodium dehydroacetate, 1,2-benzoisothiazolin-3-one and the like. Examples of the wetting agent include urea, urea derivatives, organic acids such as malonic acid and derivatives thereof, and hygroscopic substances such as polyethylene glycol.

The viscosity of the pigment ink composition for aqueous ball-point pens of the present invention is not particularly limited.
It is desirable that the viscosity under the condition of 5 ° C. be 100 to 800 mpa · s. By setting the viscosity in this range, the smoothness of writing and the density of the writing line of the aqueous ballpoint pen pigment ink can be obtained.

According to the present invention, the specific surface area is 250 m ² / g.
Having the above, and containing a porous or non-porous particulate anhydrous silica that is hydrophilic in the ink, to prevent tip leakage from the pen tip, and with good writing performance without dents, A pigment ink for an aqueous ballpoint pen that does not cause clogging of the pen tip is obtained. Although the function of preventing such leakage is not clear, the silanol groups (Si-OH) on the surface of the fine anhydrous silica particles are connected to each other by hydrogen bonding to form a network structure when left in a stationary state, so that a network structure is formed. It is thought that it prevents the leak of the front.

[0017]

Examples and Comparative Examples Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to these Examples. Examples and comparative examples of the pigment ink for aqueous ballpoint pens of the present invention are shown in Table 1 below. The numerical values in the table indicate% by weight.

[0018]

[Table 1]

Examples 1 to 5 and Comparative Examples 1 to 5 described in Table 1
The method for preparing the pigment ink composition for aqueous ballpoint pen No. 3 will be described below. Examples 1 to 3 described in Table 1 include ethylene glycol, diethylene glycol, a water-soluble solvent of glycerin, polyethylene glycol, and Aerosil # 300 (an aerosol of non-porous fine particles of water) manufactured by Nippon Aerosil Co., Ltd. In addition, a dissolver stirrer (V
DISPERM made by MA-GETZMANN GmbH
ATFE) and the number of rotations is from 10,000 to 12000 rpm.
Disperse with m. Next, a pigment and a styrene-acrylic acid copolymer as a pigment dispersant were added, and the number of rotations was 10,000 to 1
Disperse uniformly at 2000 rpm. Thereafter, the number of revolutions was set to 800 to 1500 rpm, and a cross-linked acrylic acid resin was used.
Add polyvinylpyrrolidone. Further, a surfactant and urea are added, and finally, triethanolamine is added to add p
The H value was adjusted to 7.5 to 9.0, and this was used as an aqueous pigment ink composition for a ballpoint pen.

In Examples 4 and 5, fine particles of anhydrous silica such as Aerosil # 300 (manufactured by Nippon Aerosil Co., Ltd.) were mixed with a water-soluble solvent of glycerin and triethylene glycol and polyethylene glycol, using a dissolver stirrer (VMA-GE).
Using TZMANN GmbH (DISPERMATE), the dispersion is performed at a rotation speed of 10,000 to 12000 rpm. Next, the number of revolutions was set to 800 to 1500 rpm, and a pigment dispersion and a crosslinked N-vinylacetamide and a straight type N-vinylacetamide were added and uniformly dispersed to obtain a pigment ink composition for an aqueous ballpoint pen. Comparative Example 1
-3 were prepared in the same manner as in Examples 1-5.

In Comparative Example 1, Aerosil # 300 (manufactured by Nippon Aerosil Co., Ltd.) was added to Aerosil # 2 from the composition of Example 1.
This is an ink composition prepared by replacing with 00 (manufactured by Nippon Aerosil Co., Ltd.).

In Comparative Example 2, 0.35% by weight of Aerosil # 380 (manufactured by Nippon Aerosil Co., Ltd.) having the composition of Example 2 was used.
The ink composition was prepared by increasing the amount of the ink composition.

Comparative Example 3 is an ink composition prepared by removing the straight polymer from the composition of Example 4.

The physical properties of Examples 1 to 5 and Comparative Examples 1 to 3 are shown in Table 2 below.

[0025]

[Table 2]

The pigment ink compositions for water-based ballpoint pens prepared as Examples 1 to 5 and Comparative Examples 1 to 3 were applied to an inner diameter of 3.5 m.
m about 10cm in height to a polypropylene pipe,
Fill about 0.8 g by weight. Attached with a stainless steel tip for water-based ballpoint pen, filling the back of the ink with grease to prevent drying and outflow of the ink, and then using centrifugal force to remove air remaining between the tip and the ink. Of the test.

Pre-leakage: The pen tip of the test core was fixed vertically downward, and it was observed whether or not the ink naturally leaked from the pen tip. The evaluation is expressed in the following three stages. ：: No change was observed at the tip of the pen. Δ: Leakage of rice-sized ink was observed at the tip of the pen. ×: Ink leakage was observed such that ink fell from the tip of the pen.

Long-term stability: Examples 1 to 5 and Comparative Example
The water-based pigment ink compositions for ball-point pens of 1 to 3 were placed in a glass container, stored in a thermostatic chamber set at a temperature of 50 ° C. and a relative humidity of 60% for 6 months, and returned to room temperature. And the pH value were measured. The evaluation is expressed in the following three stages. ：: A change in viscosity within ± 20% and no change in pH value, or a very small change in pH value. Δ: Change in viscosity is ± 20 to 50%, and change in pH value is
What was less than 1. X: The change in viscosity was ± 50% or more, or the ink was separated, or the change in pH value was 1 or more.

Writing performance: The test core was written at a temperature of 25 ° C., and burrs, dents and cracks were observed. The evaluation is expressed in the following three stages. ：: Good writing lines were obtained with almost no blurring, dents and cracks. Δ: Scratches, dents, and cracks were found throughout the writing line. ×: Unable to use as a writing instrument due to continuous blurring, dents, and broken characters.

Table 3 shows the results of the above three tests.

[0031]

[Table 3]

Claims (3)

[Claims] An aqueous ball-point pen pigment ink composition containing a pigment, a pigment dispersant, water, a water-soluble solvent and a water-soluble polymer resin as main components has a specific surface area of 25 based on the BET method.
A pigment ink composition for an aqueous ballpoint pen, which has a hydrophilic, porous or non-porous fine particle anhydrous silica of 0.03 to 0.3% by weight having a surface area of 0 m ² / g or more. 2. The pigment ink composition for an aqueous ball-point pen according to claim 1, wherein the water-soluble polymer resin contains both a straight polymer having spinnability and a polymer capable of forming a crosslinked three-dimensional structure. 3. The pigment ink composition for an aqueous ball-point pen according to claim 1, wherein the compounding weight of the straight polymer having spinnability is larger than the compounding weight of the hydrophilic, porous or nonporous fine particle anhydrous silica. .