JPH073200A - Water-based pigment ink composition for writing utensil - Google Patents

Abstract

PURPOSE:To provide the compsn. which provides written lines excellent in hiding power, hardly exhibits difference in whiteness between just after writing and after drying, and can flow out the ink even when used in a writing utensil of a central lead type. CONSTITUTION:The compsn. contains, as a white hiding agent, a styrene-based doughnut-shaped flat particle emulsion. The doughnut-shaped flat particle has a circular shape or the like with a central through-hole or with a concave part at the center of at least one side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based pigment ink composition for a writing instrument, and more particularly to a water-based pigment ink composition for a writing instrument suitable for a core type writing instrument.

[0002]

BACKGROUND OF THE INVENTION Conventionally, a water-based pigment ink composition for a writing instrument is a white pigment having a large particle size and a large specific gravity as a hiding agent in order to give hiding or opacity to a handwriting.
Typically, it contains titanium oxide particles. Such an ink composition has a poor dispersibility in the white pigment,
For example, it cannot be used as an ink composition for a so-called core type marking pen in which ink is written to the pen tip by capillarity from the ink occlusion body for writing. When a white pigment having a smaller particle size is used, the dispersibility in the ink composition is excellent, but the target hiding property is inferior, and the opacity of handwriting cannot be secured.

Therefore, for example, Japanese Patent Laid-Open No. 63-14538.
No. 0 and Japanese Patent Laid-Open No. 63-145382 propose an aqueous white pigment ink composition prepared by mixing hollow resin particles (spherical particles) called plastic pigments together with titanium oxide and a chromatic color pigment. Further, JP-A-63-145381 proposes an aqueous black pigment ink composition prepared by blending hollow resin particles together with carbon black.

Although the hollow resin particles have excellent dispersibility, they are not sufficiently concealable as compared with, for example, titanium oxide. On the other hand, when the hollow resin particles are used in combination with titanium oxide,
If an attempt is made to improve the concealing property, titanium oxide will settle down and a density difference will occur in the handwriting, so it cannot be used, for example, in a center-type writing instrument. Therefore, in order to solve the above-mentioned problems, JP-A-63-243179 discloses that water is included inside,
An aqueous pigment ink composition for a writing instrument has been proposed which contains at least hollow resin particles (spherical) formed of a shell of an acrylic-styrene copolymer. The hollow resin particles in the aqueous pigment ink composition for a writing instrument are those containing water inside and formed by the shell of an acrylic-styrene copolymer, and are in the form of a water-based emulsion. Although the particles also contain water inside, the water evaporates during drying and is replaced with air to become hollow resin particles containing air inside. Moreover, since the hollow resin particles after drying each independently retain the shape of the hollow resin particles, light scattering occurs between the acrylic-styrene copolymer layer that is the shell and the air inside, and the hollow resin particles were used alone. When it is used in combination with other colorants, the hiding power is improved. Further, since the hollow particles have a smaller specific gravity than titanium oxide, less sedimentation occurs,
It has excellent storage stability.

[0005]

However, since the hollow resin particles develop a white color due to evaporation of water in the hollow portion, the hiding property is inferior immediately after writing, that is, in a state containing water immediately after writing. There is a difference in whiteness between the color and the color after drying. Here, there are two types of writing instruments, an ink-free type valve type and a core type that fills the filling (or core) with ink and causes the ink to flow out from the tip. In the case of the former valve type, , Since it is used after shaking inside, dispersibility does not matter so much.

However, the latter core type, for example, the one in which the ink is made to flow out from the chips by the capillary phenomenon from the batting (or the core), has been previously proposed by the applicant of the present invention, Japanese Patent Laid-Open No. 2-13.
In the writing instrument described in No. 3479, it can be evaluated that the above problems have been improved to some extent by using a hollow resin emulsion and a specific water-solubilizing resin as a dispersant, but the ink itself has hiding properties and good dispersibility. Even if it is a white ink, when the ink flows out from the batting or core, it is filtered by the batting and chips, and the substantial concentration of titanium oxide and hollow resin particles becomes low, and the ink with poor hiding property There was a problem that it was leaked from.

The object of the present invention is to provide a handwriting which is particularly excellent in hiding property, and there is almost no difference in whiteness between immediately after writing and after drying, and particularly when used for a core type writing instrument, the hiding property is excellent. An object of the present invention is to provide a water-based pigment ink composition for a writing instrument that can flow out ink.

[0008]

The aqueous pigment ink composition for a writing instrument of the present invention is characterized by containing a styrene-type donut-shaped flat particle emulsion as a white-type masking agent. The styrene-based donut-shaped flat particles (hereinafter referred to as "doughnut-shaped flat particles") is a kind of plastic pigment and is used as a hiding agent capable of exhibiting a white color like hollow resin granules. Since the specific gravity of the doughnut-shaped flat particles is smaller than the specific gravity of titanium oxide, it is possible to improve the hiding power and reduce the weight of the ink by using the white hiding agent instead of titanium oxide or together with titanium oxide. it can.

The composition of the donut-shaped flat particles is not particularly limited as long as it is a composition capable of maintaining the donut-shaped flat particles in an aqueous medium. The manufacturing method is not particularly limited as long as it is a method capable of forming a donut shape. For example, commercially available products such as Muticle D type manufactured by Mitsui Toatsu Chemicals, Inc. can be preferably used. Generally, any styrene type may be used.

As the size of the donut-shaped flat particles, particles having an outer diameter (major axis) of about 0.1 to 1.0 μm can be used, but an outer diameter of about 0.3 to 0.7 μm is preferable. If the outer diameter is less than 0.1 μm, the hiding property is not very good,
If it exceeds 1.0 μm, it will be difficult for the tip to be the tip to flow out. Further, the thickness of the donut-shaped flat particles is preferably about 1/3 to 2/3 of the outer diameter. In addition, the donut shape referred to in the present invention is a solid flat body having a disk-like shape such as an elliptical shape and a circular shape, and is not limited to one having a through hole formed in the central portion, and one surface or both surfaces It also includes the one with the central part depressed. At this time, the size of the through hole or the recess is not particularly limited.

Such donut-shaped flat particles are contained in the aqueous pigment ink composition in an amount of usually 0.5 to 40% by weight, preferably 1 to 20% by weight, as a solid content. If the content exceeds 40% by weight, the viscosity rises too much, especially when used in a core type writing instrument, the tip of the pen tip is clogged, which easily causes outflow failure and is relatively Since the content of the water-soluble resin (described later) as a tackifier decreases, the adhesion to the writing surface also decreases. On the other hand, if it is less than 0.5% by weight, a sufficient hiding effect cannot be obtained, so it is necessary to increase the content of the white inorganic pigment such as titanium oxide.
The dispersibility cannot be improved.

The doughnut-shaped flat particles can be added alone in the preparation of the aqueous pigment ink composition, but they are generally used in the form of an emulsion based on water. The donut-shaped flat particle emulsion has a solid content of donut-shaped flat particles of 40 to 4
About 5% by weight, viscosity is 15 to 25 cps, pH 7.8
A weak alkaline emulsion of about 8.3 is preferably used.

In the aqueous pigment ink composition for a writing instrument of the present invention, the above donut-shaped flat particles are used as a masking agent.
It is preferable to use together with a white inorganic pigment such as titanium oxide or zinc oxide. By containing these white inorganic pigments, especially titanium oxide, high hiding power can be exhibited. The content of titanium oxide in the aqueous pigment ink composition is in the range of 1 to 40% by weight, preferably 5 to 30% by weight, depending on the use of the ink, the hiding property, etc., and depends on the content of the donut-shaped flat particles. Is appropriately selected. Generally, when the content of donut-shaped flat particles is high, the content of titanium oxide can be reduced.

The aqueous pigment ink composition of the present invention is generally a natural water-soluble polymer or water-soluble polymer as a tackifier for increasing the dispersibility of the above-mentioned hiding agent in the ink and the adhesion to the writing surface. Resin (hereinafter, collectively referred to as "water-soluble resin") may be contained. Examples of the water-soluble resin include poly (meth) acrylic acid, styrene-acrylic acid copolymer, styrene-maleic acid copolymer, polymaleic acid, rosin-modified maleic acid resin, shellac and the like. These water-soluble resins may be used as alkali metal salts, ammonium salts, amine salts, or as an aqueous resin emulsion or an aqueous resin hydrosol.

Such a water-soluble resin may be contained in the aqueous pigment ink composition in an amount of 0.1 to 30% by weight, preferably 1 to 10% by weight. When the content is less than 0.1% by weight, the dispersibility of the above-mentioned masking agent becomes insufficient and the adhesion to the writing surface also becomes insufficient. On the other hand, if the content exceeds 30% by weight, the viscosity rises too much, which causes poor outflow especially when used in a core type writing instrument.

The aqueous pigment ink composition for a writing instrument of the present invention may further contain a preservative, a fungicide, a surfactant and the like, if necessary. In the case of an achromatic or chromatic aqueous pigment ink composition other than white, an achromatic or chromatic inorganic pigment or organic pigment is contained as a colorant. The pigment is not particularly limited, for example, carbon black, azo type, phthalocyanine type, quinacridone type,
Any pigments such as anthraquinone-based, dioxane-based, indigo-based, thioindigo-based, perinone-based, perylene-based, isoindrene-based, azomethineazo-based pigments can be blended. When such a colorant is contained, the content thereof in the aqueous pigment ink composition is 0.1 to 30% by weight, preferably 1 to 15% by weight.

As the solvent for the aqueous pigment ink composition, water or an aqueous medium prepared by blending water with various water-soluble organic solvents as a wetting agent and / or a drying accelerator is used. Examples of the water-soluble organic solvent include lower alcohols such as ethanol, isopropanol, butanol; polyhydric alcohols such as ethylene glycol, propylene glycol, glycerin; diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, polypropylene. Polyalkylene glycol such as glycol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether,
Alkyl ethers of alkylene glycols such as ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether and propylene glycol monobutyl ether are used. These water-soluble organic solvents are used in water-based inks
It may be contained in an amount of not more than 10% by weight, preferably not more than 10% by weight.

The water-based pigment ink of the present invention is prepared by blending the above-mentioned components in a predetermined amount and mixing and stirring the mixture uniformly with a conventionally known disperser such as a ball mill, homomixer, bead mill and roll mill. The composition can be prepared. When an inorganic pigment is used in combination, a composition in which the pigment is dispersed may be prepared in advance, and this may be mixed with the solid donut-shaped flat particle emulsion in an appropriate ratio.

Unlike conventional hollow resin granules, the donut-shaped flat particles do not contain water inside the particles, so that they can develop white color immediately after being written on the paper. Further, compared to an aqueous pigment ink composition containing hollow resin granules at the same concentration, the aqueous pigment ink composition of the present invention containing donut-shaped flat particles generally has excellent dispersibility and low viscosity, Excellent outflow. This means that when a core-type writing instrument is filled with ink having the same degree of concealment,
The aqueous pigment ink composition of the present invention is batting, meaning that the rate at which the concentration of the actual hiding agent is reduced by filtering with chips is small, and the hiding property that is satisfactory even when written on the paper, Can also exhibit smoothness and gloss.

[0020]

EXAMPLES Specific examples of the aqueous pigment ink composition for a writing instrument of the present invention will be described below. <Example 1> As the donut-shaped flat particles, Muticle PP240D (trade name), which is a styrene-based donut-shaped flat particle having recesses, manufactured by Mitsui Toatsu Chemicals, Inc. was used. 240D is a milky white emulsion having a pH of 8 and containing 44 wt% of doughnut-shaped flat particles having a particle diameter of 0.5 μm as a solid content (150 ° C., 20 minutes) and having a viscosity (20 ° C., 6 minutes).
0 rpm) is 20 cps.

As the water-soluble resin, John Cryl 679 (trade name), which is a styrene-acrylic acid copolymer manufactured by Johnson Co., Ltd. (abbreviated as "resin A" in Table 1).
Was used. This was used as an ammoniacal aqueous solution containing 34% by weight of this John Cryl 679 and 10% by weight of isopropanol. As the white pigment, Kronos KR-3 which is titanium oxide manufactured by Titanium Industry Co., Ltd.
80D (trade name) was used.

240D, titanium oxide, John Kryl 67
9, a surfactant, propylene glycol, and water were mixed in the amounts (parts by weight) shown in Table 1 and uniformly mixed by a bead mill to prepare an aqueous pigment ink composition.
The viscosity (25 ° C.) of this aqueous pigment ink composition was measured,
Further, using a core-type writing instrument in which the core portion was filled with this aqueous pigment ink composition, the writability, hiding power, and storability were evaluated based on the following evaluation methods.

<Examples 2 to 6> Examples except that the type and content of the water-soluble resin and the respective contents of 240D, titanium oxide, surfactant, propylene glycol and water were changed as shown in Table 1. In the same manner as in Example 1, the aqueous pigment ink compositions of Examples 2 to 6 were prepared. However, the black pigment (CI.PIG.BLAC) was added to the water-based ink composition of Example 4.
K7), a red pigment (CI.
PIG. RED57), the water-based ink composition of Example 6 is a chromatic ink containing a blue pigment (CI.PIG.BLUE15) in an amount shown in Table 1. The water-soluble resins B to F used in Examples 2 to 6 are as follows.

Example 2 (Resin B) B-36 manufactured by Johnson Co., Ltd. Example 3 (Resin C) Hyros X-220 manufactured by Hoshi Kogaku Co., Ltd. Example 4 (Resin D) John Krill 555 manufactured by Johnson Co., Ltd. Example 5 (Resin E) H-21 manufactured by Seikou Kagaku Co., Ltd.
90 Example 6 (Resin F) John Kryl 67 manufactured by Johnson Co., Ltd. Among the above water-soluble resins, Resin C is a styrene-maleic acid copolymer, Resin E is polyacrylic acid, and others (Resin B, D, F) is a styrene-acrylic acid copolymer. All of these were used as an ammoniacal aqueous solution containing 34% by weight of resin and 10% by weight of isopropanol.

The viscosities (25 ° C.) of the prepared aqueous pigment ink compositions of Examples 2 to 6 were measured, and the writability and the like were evaluated in the same manner as in Example 1.

[0026]

[Table 1]

Next, a comparative example with the present invention will be given. <Comparative Examples 1 to 6> Instead of the styrenic donut-shaped flat particle emulsion, as a hollow resin granule sphere emulsion, Grand Nippon PP-1 manufactured by Dainippon Ink and Chemicals, Inc.
100 (trade name) was used. This Grandeur PP-1
100 is an emulsion containing 36% by weight of hollow resin granules as a solid content.

Comparative Examples 1 to 6 were all aqueous pigment ink compositions of Examples 1 to 6 except that hollow resin particles were contained in an amount shown in Table 2 instead of the donut-shaped flat particles. Was prepared so as to have the same composition. The viscosities (25 ° C.) of these aqueous pigment ink compositions were measured, and the writability and the like were evaluated in the same manner as in Example 1.

[0029]

[Table 2]

[Evaluation Method] The writability is the ink outflow property when handwritten on the paper surface: ◎ (very good ink outflow property), ○ (ink good outflow property), △ (blurring) It was evaluated on a three-point scale. The hiding property is written on the black line printed on the art paper, and visually observing the remaining condition of the black line after the ink is dried. ◎ (black line is not visible at all), ○ (black line is hardly visible) ) And Δ (black line is visible).

The storability is 50 in an upright state or an inverted state.
The writability and hiding property after storage at ℃ for 1 month were evaluated by comparing with the writability and hiding property before storage.
Regarding the writability, ◎ (same as before storage), ○ about the change of ink outflow before and after storage, and about the hiding property about the change of writing density before and after storage, respectively.
(Evaluation was almost the same as before storage) and Δ (flowability or hiding property was lower than before storage) was evaluated.

The aqueous ink compositions of Examples 1 to 6 and Comparative Examples 1 to 6 were evaluated according to the above evaluation method. Table 3 shows the evaluation results and the measurement results of the viscosity of each water-based ink composition. In terms of storability, no difference was observed between the upright and inverted states.

[0033]

[Table 3]

[Evaluation Results] As can be seen from Table 3, the ink compositions of Examples 1 to 6 and Comparative Examples 1 to 6 containing doughnut-shaped flat particle emulsions or hollow resin particle spherical emulsions at almost the same concentration as a masking agent. It can be seen that the viscosity of the example product is lower than that of the example product.

Further, with respect to the writability, the hiding power, and the preservability, the example product exhibited the same or higher characteristics than the corresponding comparative example product. That is, in the product of this example, the initial hiding property and writability are superior to those of the comparative example product, and
It was excellent in storability, and the writability and the concealing property were maintained in the initial state even after being stored for 1 month. The change in the hiding property of Comparative Examples 2 to 4 is evaluated as “◯” as in Examples 2 to 4, but the hiding property before storage is better for the Example product. Regarding the hiding property after storage, the example product was also superior.

[0036]

EFFECTS OF THE INVENTION The aqueous pigment ink composition for a writing instrument of the present invention contains styrenic donut-shaped flat particles as a masking agent, and therefore has good dispersibility and good outflow. Therefore, not only a valve type writing instrument but also a core type writing instrument can be used to exert a satisfactory hiding power.

The styrenic donut-shaped flat particles are
Unlike hollow resin granules, since the granules are not written on the paper surface containing water, there is almost no difference in whiteness immediately after writing and after drying. Moreover, due to the peculiar shape of the flat particles, that is, in order to make the hiding property more effective by aligning or laminating microscopically almost flat on the handwriting, smoothness and glossiness are better than those of conventional solid spherical ones. Is also excellent.

Claims (11)

[Claims] 1. An aqueous pigment ink composition for a writing instrument, which comprises a styrene-based donut-shaped flat particle emulsion as a white-based hiding agent. 2. The aqueous pigment ink composition for a writing instrument according to claim 1, wherein the styrenic donut-shaped flat particles have a circular shape. 3. The aqueous pigment ink composition for a writing instrument according to claim 1, wherein the styrenic donut-shaped flat particles have a through hole formed in the central portion. 4. The aqueous pigment ink composition for a writing instrument according to claim 1, wherein the central portion of at least one surface of the styrenic donut-shaped flat particles is a depression. 5. The writing instrument according to claim 1, wherein the styrenic donut-shaped flat particles have an outer diameter of 0.1 to 1.0 μm and a thickness of 1/3 to 2/3 of the outer diameter. Water-based pigment ink composition for use. 6. The aqueous pigment ink composition for a writing instrument according to claim 1, wherein the styrene-based doughnut-shaped flat particles are contained in the aqueous pigment ink composition for a writing instrument in a solid content of 0.5 to 40% by weight. object. 7. The concentration of styrenic donut-shaped flat particles is 40 to 45% by weight, the viscosity is 15 to 25 cps, and the pH is
6. An aqueous emulsion of 7.8 to 8.3.
The aqueous pigment ink composition for a writing instrument as described in 1. 8. The aqueous pigment ink composition for a writing instrument according to claim 1, which contains a white inorganic pigment in an amount of 1 to 40% by weight. 9. The aqueous pigment ink composition for a writing instrument according to claim 1, which contains a water-soluble resin in an amount of 0.1 to 30% by weight. 10. The water-soluble resin is polyacrylic acid,
Polymethacrylic acid, styrene-acrylic acid copolymer,
The aqueous pigment ink composition for a writing instrument according to claim 9, which is one or more selected from the group of styrene-maleic acid copolymer, polymaleic acid, rosin-modified maleic acid resin, and shellac. 11. At least one selected from the group consisting of lower alcohols, polyhydric alcohols, polyalkylene glycols and alkylene glycol ethers is used as a solvent.
An aqueous medium containing less than or equal to wt% is used.
0. The aqueous pigment ink composition for a writing instrument according to any one of 0.