JP3049186B2 - Aqueous pigment ink composition for core type writing implements - Google Patents

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]

2. Description of the Related Art Conventionally, an aqueous pigment ink composition for a writing instrument has been used as a concealing agent as a white pigment having a large particle diameter and a large specific gravity as a concealing agent in order to impart opacity or opacity to handwriting.
Typically, it contains titanium oxide particles. Such an ink composition, because the white pigment is inferior in dispersibility,
For example, the ink composition cannot be used as an ink composition for a so-called center-core type marking pen in which ink is caused to flow out of an ink occluding body to a pen tip by capillary action and writing is performed. When a white pigment having a smaller particle size is used, although its dispersibility in the ink composition is excellent, the intended concealing property becomes poor, and opacity of the handwriting cannot be secured.

Therefore, for example, Japanese Patent Application Laid-Open No. 63-14538
No. 0 and JP-A-63-145382 propose an aqueous white pigment ink composition comprising titanium oxide and a chromatic color pigment, together with hollow resin particles (spherical) called plastic pigments. Japanese Patent Application Laid-Open No. 63-145381 proposes an aqueous black pigment ink composition comprising hollow resin particles mixed with carbon black. Although the hollow resin particles are excellent in dispersibility, for example, the concealing property is not sufficient as compared with titanium oxide, and on the other hand, if titanium oxide is used together with the hollow resin particles to increase the concealing property, Since titanium oxide precipitates and a concentration difference occurs in handwriting, it cannot be used for, for example, a core-type writing instrument.

In order to solve the above-mentioned problem, Japanese Patent Application Laid-Open No. 63-243179 describes a writing instrument containing water therein and containing at least hollow resin particles (spherical) formed of an acrylic-styrene copolymer shell. Aqueous pigmented ink compositions have been proposed. The hollow resin particles in the aqueous pigment ink composition for writing implements are formed of a shell of an acrylic-styrene copolymer containing water therein, and are in the form of a water-based emulsion. Although particles contain water inside, the water evaporates during drying and is replaced by air to become hollow resin particles containing air therein. In addition, since the hollow resin particles after drying each independently maintain the shape of the hollow resin particles, light scattering occurs between the acrylic styrene copolymer layer as the shell and the air inside, and the hollow resin particles were used alone. In this case, it looks white, but when used in combination with other coloring agents, the hiding power is improved. Further, the hollow particles have a lower specific gravity than titanium oxide, so that sedimentation is small,
Excellent storage stability.

[0005]

However, since the hollow resin particles develop a white color due to the evaporation of moisture in the hollow portion, the opacity is poor immediately after writing, that is, the hollow resin particles contain 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 implements: an ink-free type valve type, and a core type that fills the batting (or core) with ink and allows ink to flow out of the tip. Since it is used after shaking the inside, dispersibility does not matter much.

However, the latter medium-core type, for example, Japanese Patent Application Laid-Open No. 2-13, proposed by the present applicant, which allows ink to flow out of a chip from a batting (or a core) by capillary action.
The writing implement described in No. 3479 can be evaluated as having improved the above-mentioned problems to some extent by using a hollow resin emulsion and a specific water-solubilizing resin as a dispersant, but the ink itself has a concealing property and a good dispersibility. Even white ink, when the ink flows out of the batting or the core, is filtered through the batting and chips, causing the substantial concentration of titanium oxide and hollow resin particles to decrease, and the ink having poor hiding power There was a problem that was leaked from.

An object of the present invention is to provide a handwriting having particularly excellent concealing properties, and there is almost no difference in whiteness between immediately after writing and after drying. An object of the present invention is to provide a water-based pigment ink composition for a writing instrument from which ink can flow out.

[0008]

The aqueous pigment ink composition for a writing instrument of the present invention is obtained by filling a batting or a core with the ink.
Medium-core brush that causes ink to flow out of the chip by capillary action
The ink composition for a writing instrument is characterized by containing a styrene-based central depressed flat particle emulsion as a white hiding agent. The styrene-based central depressed flat particles and
Is a kind of plastic pigment, and is used as a concealing agent capable of expressing white color, like hollow resin particle spheres. Center
Since the specific gravity of the depressed flat particles is smaller than the specific gravity of titanium oxide, it can be used as a white hiding agent instead of or together with titanium oxide to improve the hiding power and reduce the weight of the ink. it can.

The composition of the central depression flat particles is not particularly limited as long as the composition can maintain the central depression flat in an aqueous medium. The manufacturing method is not particularly limited as long as it can form a central depression . For example, a commercially available product such as a Muticle D type manufactured by Mitsui Toatsu Chemicals, Inc. can be suitably used. Generally, anything of styrene type may be used. As the size of the central depressed flat particles, particles having an outer diameter (major diameter) of about 0.1 to 1.0 μm can be used, and an outer diameter of about 0.3 to 0.7 μm is preferable. Outer diameter 0.
When the thickness is less than 1 μm, the concealing property is not very good.
If it exceeds 0 μm, it will be difficult to flow out of the pen tip. The thickness of the central depressed flat particles is 1 / the outer diameter.
It is preferably about 3 to 2/3 . In the present invention,
A central depression is defined as a disk-like shape such as an ellipse or a circle.
It is a real flat body, and the center of one or both sides is depressed
Means what you do. At this time, the size of the recess is particularly limited.
Absent.

[0010] Such a central depressed flat particle is generally contained in a medium-core type aqueous pigment ink composition in a solid content of 0.5 to 4%.
0% by weight, preferably about 1 to 20% by weight. When the content exceeds 40 wt%, the viscosity is too elevated, medium
When used in a core-type writing instrument, the tip of the pen tip becomes clogged and easily leaks, and the content of the water-soluble resin (described later) as a tackifier is relatively low. Adhesion to the surface decreases. On the other hand, 0.5
If the content is less than 10% by weight, a sufficient hiding effect cannot be obtained. Therefore, it is necessary to increase the content of a white inorganic pigment such as titanium oxide, and the dispersibility cannot be improved.

The central depressed flat particles may be used alone in the preparation of the aqueous pigment ink composition, but are generally used in the form of a water-based emulsion. As the central depressed flat particle emulsion, the concentration of the solid depressed flat particles is 40 to 4%.
About 5% by weight, viscosity is 15-25 cps, pH 7.8
A weak alkaline emulsion of about ８8.3 is preferably used. In the aqueous pigment ink composition for a core type writing instrument of the present invention, it is preferable to use the flat particles and a white inorganic pigment such as titanium oxide and zinc oxide in combination as a concealing agent. By containing these white inorganic pigments, particularly titanium oxide, high hiding power can be exhibited. The content of titanium oxide in the aqueous pigment ink composition is 1 to 40% by weight depending on the use of the ink, hiding power, and the like.
Preferably, it is appropriately selected within the range of 5 to 30% by weight according to the content of the flat particles having a central depression . In general, central depression
When the content of the immersed flat particles is high, the content of titanium oxide can be reduced.

The core type aqueous pigment ink composition of the present invention comprises:
As a tackifier for enhancing the dispersibility of the above-mentioned concealing agent in the ink and enhancing the adhesiveness to the writing surface, a natural water-soluble polymer or a water-soluble synthetic resin (hereinafter, collectively referred to as “water-soluble Resin "). Examples of the water-soluble resin include poly (meth) acrylic acid, styrene-acrylic acid copolymer, styrene-maleic acid copolymer, polymaleic acid, rosin-modified maleic 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.

[0013] 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 concealing 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 is excessively increased, and particularly when used for a medium-core type writing instrument, it causes poor outflow. The aqueous pigment ink composition for a core-type writing instrument of the present invention (hereinafter, the aqueous pigment ink composition)
) Further includes, if necessary, preservatives, fungicides,
Surfactants and the like may be appropriately contained.

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, and includes, for example, pigments such as carbon black, azo-based, phthalocyanine-based, quinacridone-based, anthraquinone-based, dioxane-based, indigo-based, thioindigo-based, perinone-based, perylene-based, isoindrene-based, and azomethineazo-based pigments. Any one can be blended. When such a coloring agent is contained, it is blended so that the content in the aqueous pigment ink composition is 0.1 to 30% by weight, preferably about 1 to 15% by weight.

As the solvent for the aqueous pigment ink composition, water or an aqueous medium prepared by mixing various water-soluble organic solvents as a wetting agent and / or a drying accelerator with water is used. Examples of the water-soluble organic solvent include lower alcohols such as ethanol, isopropanol and butanol; polyhydric alcohols such as ethylene glycol, propylene glycol and glycerin; diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol and polypropylene. Polyalkylene glycols such as glycol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether,
Alkylene ethers of alkylene glycol 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 aqueous inks for 20
%, Preferably up to 10% by weight.

The aqueous pigment ink of the present invention is prepared by mixing a predetermined amount of the above-mentioned components and uniformly mixing and stirring the mixture with a conventionally known dispersing machine such as a ball mill, a homomixer, a bead mill, and a roll mill. A composition can be prepared. Further, when used in combination inorganic pigments, previously, to prepare a composition in which a pigment is dispersed, and this central Recessed
The submerged flat particle emulsion may be mixed at an appropriate ratio. Unlike the conventional hollow resin particle spheres, the central depressed flat particles do not contain moisture inside the particles, and thus can exhibit white color immediately after writing on the paper.

In addition, the aqueous pigment ink composition of the present invention containing the flat particles having a central depression is generally superior in dispersibility to the aqueous pigment ink composition containing the same concentration of hollow resin particle spheres. Low viscosity and excellent outflow. This means that, when an ink having the same degree of hiding power is filled into a core writing instrument, the aqueous pigment ink composition of the present invention has
This means that the rate of substantial reduction in the concentration of the concealing agent after being filtered with a batting or chip is small, and satisfactory concealing properties, even smoothness and gloss can be exhibited even when written on paper.

[0018]

EXAMPLES Hereinafter, specific examples of the water-based pigment ink composition for a core writing instrument of the present invention will be described. <Example 1> central internal concave flattened particles were used MUTICLE PP240D (trade name) is a styrene-based central internal concave flattened particles having a recessed hole made by Mitsui Toatsu Chemicals Corporation. 240
D is pH 8 containing 44% by weight of flat particles having a central depression shape having a particle diameter of 0.5 μm as solids (150 ° C., 20 minutes).
Milky white emulsion, viscosity (20 ° C, 60rpm)
Is 20 cps.

As a water-soluble resin, a styrene-acrylic acid copolymer, John Krill 679 (trade name) manufactured by Johnson Co., Ltd. (abbreviated as "resin A" in Table 1)
Was used. It was used as an aqueous ammoniacal solution containing 34% by weight of this Johncryl 679 and 10% by weight of isopropanol. As the white pigment, Kronos KR-3 which is a titanium oxide manufactured by Titanium Industry Co., Ltd.
80D (trade name) was used. 240D, titanium oxide, Joncryl 679, a surfactant, propylene glycol, and water were each blended 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 the water-based pigment ink composition was measured, and the writability and concealing property were evaluated based on the following evaluation methods using a core-type writing instrument in which the water-based pigment ink composition was filled in the center. And storage stability were evaluated.

<Examples 2 to 6> Examples 2 to 6 were repeated except that the kind and content of the water-soluble resin and the 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, a black pigment (CI.PIG.BLACK7) was used for the aqueous ink composition of Example 4, a red pigment (CI.PIG.RED57) was used for the ink composition of Example 5, and an aqueous ink composition of Example 6 was used. Is a blue pigment (CI. PIG.
BLUE15) in the amount shown in Table 1. The water-soluble resin B used in Examples 2 to 6
-F are as follows.

Example 2 (Resin B) B-3 manufactured by Johnson Co., Ltd.
6 Example 3 (Resin C) HYROS X-220 manufactured by Hoshi Kogaku Co., Ltd. Example 4 (Resin D) Joncryl 555 manufactured by Johnson Co., Ltd. Example 5 (Resin E) H-21 manufactured by Hoshi Photo Chemical Co., Ltd.
90 Example 6 (Resin F) Joncryl 67 manufactured by Johnson Co. Among the above water-soluble resins, resin C is a styrene-maleic acid copolymer, resin E is polyacrylic acid, and others (resins B, D, F) is a styrene-acrylic acid copolymer. Each of these was 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.

[0023]

[Table 1]

Next, a comparative example with the present invention will be described. <Comparative Examples 1 to 6> Instead of the styrene-based central depressed flat particle emulsion,
As a hollow resin particle sphere emulsion, Grandl PP-1100 (trade name) manufactured by Dainippon Ink and Chemicals, Inc.
Was used. This groundul PP-1100 is an emulsion containing hollow resin particle spheres at a solid content of 36% by weight. In Comparative Examples 1 to 6, the compositions of the aqueous pigment ink compositions of Examples 1 to 6 were the same as those in Examples 1 to 6, except that hollow resin particles were contained in the amounts shown in Table 2 in place of the flattened particles in the center. Was prepared to be equal to

The viscosity of these aqueous pigment ink compositions (2
5 ° C.), and the writability and the like were evaluated in the same manner as in Example 1.

[0026]

[Table 2]

[Evaluation Method] Writability was evaluated by ink outflow when writing by hand on paper, as follows: （(very good ink outflow), イ ン キ (good ink outflow), Δ (blurring) Evaluation) on a three-point scale. The concealability was written on a black line printed on art paper, and the degree of black line remaining after ink drying was visually observed. ◎ (no black line was seen at all), ○ (black line was barely seen) ) And △ (black line is visible).

The storage stability is 50 in the upright or inverted state.
The writing and concealing properties after storage for 1 month at ℃ were evaluated by comparing the writing and concealing properties before storage.
Regarding the writability, the change in the outflow of the ink before and after storage, and the concealing property, regarding the change in the writing density before and after the storage, ◎ (exactly the same as before storage) and ○, respectively.
(Same as before storage) and △ (the outflow or concealment is lower than before storage).
According to the above evaluation methods, Examples 1 to 6 and Comparative Examples 1 to
6 aqueous ink compositions were evaluated. Table 3 shows the evaluation results and the measurement results of the viscosity of each aqueous ink composition. It should be noted that there was no difference in storage stability between the upright state and the inverted state.

[0029]

[Table 3]

[0030] [Evaluation Results] As can be seen from Table 3, the ink composition of Comparative Examples 1 to 6 substantially as in Examples 1-6 containing the same concentration a central recess shaped flat particles emulsion or hollow resin particle spheres emulsion as a masking agent Comparing with each of the examples, it can be seen that the viscosity of the example product is lower in each case. Further, in all of the writing property, the concealing property, and the preservation property, the example product exhibited characteristics equal to or higher than the corresponding comparative product. That is, the product of this example has excellent initial concealability and writability as compared with the comparative example product, and also has excellent preservability, and the writability and concealability even after storage for one month are almost in the initial state. Was holding.

The change in the concealing property of Comparative Examples 2 to 4 was evaluated as “○” as in Examples 2 to 4, but the concealing property before storage was superior to that of the example product. Therefore, the example product was also superior in concealability after storage.

[0032]

As described above, the aqueous pigment ink composition for a core type writing instrument of the present invention contains styrene-based central depressed flat particles as a hiding agent, so that it has good dispersibility and good outflow. Therefore, a satisfactory concealing power can be exhibited not only in the valve-type writing instrument but also particularly in the core-type writing instrument. In addition, styrene-based central depressed flat particles are not written on paper with water contained in the spherical spheres like hollow resin particle spheres. There is no difference. Moreover, due to the unique shape of the flat particles,
In other words, microscopically arranged or laminated microscopically on the handwriting to make the concealing effect more effective, it is superior in smoothness and glossiness as compared with a conventional solid spherical one.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-129276 (JP, A) JP-A-63-218778 (JP, A) JP-A-2-14222 (JP, A) JP-A 61-218 66710 (JP, A) JP-A-1-185311 (JP, A) JP-A-5-171093 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09D 11/00-11 / 20

Claims (9)

(57) [Claims] 1. Filling a batting or core with ink
Core-type writing implement that causes ink to flow out of the chip by tube phenomenon
A water-based pigment ink composition for a core-type writing implement , comprising a styrene-based central depressed flat particle emulsion as a white hiding agent. 2. The particle according to claim 1, wherein said particle has a circular shape.
The aqueous pigment ink composition for a core writing instrument according to the above. 3. The particle has an outer diameter of 0.1 to 1.0 μm,
The aqueous pigment ink composition for a core-type writing implement according to claim 1 or 2, wherein the thickness is 1/3 to 2/3 of the outer diameter. 4. A wick type writing instrument aqueous pigment in according to one of claims 1 to 3 containing 0.5 to 40% by weight solids in the central core type writing instrument aqueous pigment ink composition wherein the particles Ink composition. 5. The method according to claim 1, wherein said particles have a concentration of 40 to 45% by weight.
The aqueous pigment ink composition for a core-type writing implement according to any one of claims 1 to 4, which is an aqueous emulsion having a viscosity of 15 to 25 cps and a pH of 7.8 to 8.3. 6. The aqueous pigment ink composition for a core-type writing implement according to claim 1, wherein the aqueous pigment ink contains 1 to 40% by weight of a white inorganic pigment. 7. The aqueous pigment ink composition for a core-type writing implement according to claim 1, wherein the aqueous pigment ink composition contains 0.1 to 30% by weight of a water-soluble resin. 8. The water-soluble resin is selected from the group consisting of polyacrylic acid, polymethacrylic acid, styrene-acrylic acid copolymer, styrene-maleic acid copolymer, polymaleic acid, rosin-modified maleic resin, and shellac.
The aqueous pigment ink composition for a core-type writing instrument according to claim 7, wherein the composition is a kind or two or more kinds. 9. An aqueous medium containing at least 20% by weight of at least one selected from the group consisting of lower alcohols, polyhydric alcohols, polyalkylene glycols and alkylene glycol ethers as a solvent. The aqueous pigment ink composition for a core-type writing instrument according to one of the above.