JP3151175B2 - Metallic luster water-based ink for ballpoint pens - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous ink composition for a ballpoint pen having a metallic metallic luster.

[0002]

2. Description of the Related Art An ink composition obtained by adding a viscosity modifier to an aqueous ink is called an aqueous gel ink.
Widely used for aqueous ballpoint pens. As an example of this type of conventional water-based ink for ballpoint pens, Japanese Patent Publication No. 64-86
As disclosed in Japanese Patent Publication No. 73, there is known a method in which the viscosity is adjusted by adding a specific amount of xanthan gum.

As this kind of water-based ballpoint pen ink, a metal-gloss water-based ink for a water-based ballpoint pen having a metal-gloss color such as gold or silver using an aluminum powder as a coloring material and xanthan gum as a viscosity modifier is known. is there.

[0004]

However, in the above-mentioned conventional metallic glossy aqueous ink, the specific gravity of the aluminum powder is larger than that of a dye or the like used as a usual coloring material, and the aluminum powder tends to settle in the ink container. The addition amount of a thickening gelling agent such as xanthan gum is increasing. However, when the amount of xanthan gum added in the ink composition increases, there is a problem in that the overall viscosity increases and the writing quality decreases. For the above reasons, the amount of the aluminum powder to be added cannot be increased so much that an ink having a strong metallic luster could not be obtained.

[0005] Further, when a coloring agent other than aluminum powder is added to a conventional metallic gloss ink using xanthan gum to produce a colored metallic gloss ink,
It is difficult to add a coloring material other than aluminum powder because the viscosity of the ink is further increased and the writing quality is reduced, so that a colored metallic color ink other than gold or silver has not been conventionally possible.

An ink using xanthan gum as a thickening gelling agent has a drawback that, due to the influence of xanthan gum, the color becomes dull when written, so that a clear metallic color cannot be obtained.

[0007] In addition, inks using xanthan gum are susceptible to temperature. When the temperature exceeds 50 ° C, there is a problem that the thickening effect is reduced and the thixotropic property is reduced. The temperature may increase during transportation or storage as an aqueous ballpoint pen, so that stability to temperature is required.

An object of the present invention is to solve the drawbacks of the above-mentioned conventional metallic glossy ink using xanthan gum as a thickening gelling agent, which has good thixotropy and provides a clear and strong metallic gloss. An object of the present invention is to provide a metallic glossy water-based ink for ballpoint pens that is obtained, has good writing characteristics, has good stability against temperature, and has excellent storage stability.

[0009]

According to the present invention, there is provided (1) an aqueous ink for a ballpoint pen containing aluminum powder and having a metallic luster, comprising xanthan gum and a hectorite-based inorganic thickener as a thickening gelling agent. The metallic glossy water-based ink for a ball-point pen according to the above (1), wherein the addition amount of the (2) hextry-based inorganic thickening gelling agent is 0.1 to 0.5% by weight.
(3) The metallic luster aqueous ink for ballpoint pens according to the above (1) or (2), containing a coloring agent other than aluminum powder.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The composition of the present invention uses xanthan gum and a hectorite-based inorganic thickener as a thickening gelling agent. The hectorite-based inorganic thickening gelling agent is a kind of montmorillonite group mineral, and may be either a natural product or a synthetic product, but a synthetic product is preferably used. The synthetic product has particularly low coloration and excellent transparency, does not contain crystalline impurities that do not swell, and has strong gel strength because the primary particles are small and uniform.

The synthetic hectorite-based inorganic thickener is Lap
orte Industries Ltd. A product commercially available under the registered trademark “LAPONITE” manufactured by Nippon Silica Kogyo Co., Ltd. under the trade name “Laponite” can be used. The synthetic hectorite-based inorganic thickener is an agglomerate composed of fine disk-shaped primary particles having a diameter of 20 to 40 μm and a thickness of about 1 nm, and has a chemical composition represented by the following formulas (1) and (2). Have.

[0012]

## STR1 ## [Si ₈ (Mg _5.34 Li _0.66 ) O ₂₀ (O
H) ₄ ] M + _0.66

## STR2 ## [Si ₈ (Mg _5.34 Li _0.66 ) O ₂₀ (OH.
F) ₄ ] M + _0.66

These synthetic hectorites have a three-layer structure as shown in FIG. 1, and extend two-dimensionally to form platelet particles. Some of the magnesium atoms in the platelet particles are isomorphously substituted with lower-valent lithium (monovalent cation), and the platelet particles are negatively charged due to charge deficiency. The primary particles of the synthetic hectorite in a dry state are secondarily aggregated into a large flat plate bundle.

Although the synthetic hectorite-based inorganic thickener has an ionic bond as shown in FIG. 1, it is easily broken when a shear stress is applied thereto, and the bond is easily regenerated when left standing. Therefore, it shows high thixotropy. This property is due to a different mechanism from that of increasing the viscosity by entanglement of fibers of a long chain polymer of a high molecular weight such as xanthan gum.

As described above, the hectorite-based inorganic thickener has a large thickening effect and a high thixotropy. Therefore, when used alone, the effect of preventing precipitation of aluminum is improved, but the viscosity is too high after storage. Fluidity is extremely reduced, and there is instability such as a decrease in writing taste. In the ink composition of the present invention, by using xanthan gum in combination with the hectorite-based inorganic thickener, the instability of this hectorite-based inorganic thickener is improved, and the gel state is appropriately adjusted to ensure fluidity. And a stable thixotropic ink is obtained.

The amount of the hectorite-based inorganic thickener in the aqueous ink composition of the present invention is preferably in the range of 0.1 to 1% by weight. 1% by weight of hectorite-based inorganic thickener
If it exceeds 3, the gel structure may become too strong after storage such as storage, and the writing taste may be impaired. If it is less than 0.1% by weight, sufficient thixotropy may not be obtained, There is a possibility that the stability of the viscosity with respect to is reduced.

The amount of xanthan gum added is preferably in the range of 0.1 to 1% by weight. The amount of xanthan gum added is 0.
If the amount is less than 1% by weight, sufficient stability of the ink may not be obtained. If the amount exceeds 1% by weight, the viscosity of the ink as a whole may be too high and the thixotropic property may be reduced. Note that xanthan gum alone cannot greatly increase the thixotropy, and has problems such as a low aluminum sedimentation prevention effect and a decrease in viscosity due to aging after storage. Further, when the amount of added xanthan gum is increased, the overall viscosity increases, the thixotropy is not significantly improved, and the writing taste is reduced.

As xanthan gum, for example, a commercial product, "Kelzan" (trade name) of Sansei Co., Ltd. can be used.

An aluminum powder is added to the ink composition of the present invention to give a metallic luster. As the aluminum powder, a commercially available aluminum paste can be used. The aluminum paste is obtained by mixing and kneading an aluminum metal powder with a high-boiling solvent such as mineral spirit and an antiwear agent such as stearic acid to form a paste. The amount of the aluminum powder to be added is not particularly limited, but is usually about 1 to 20% by weight. The average particle size of the aluminum powder is about 5 to 30 μm.

In the present invention, various color metallic luster inks can be obtained by adding a usual coloring agent other than aluminum powder. Examples of such colorants include titanium oxide, carbon black, carmine 6B, CI
Pigment Red, CIigmentGreen7, CIigmentBlue, etc., CIAcidRed87, CIAcidRed92, CIAcidYe
llow28, CIAcidBlue9, CIAcidViolet, CIAcidBl
ue7, CIAcidOrange56, CIAcidBlack2, CIAcidRe
Acid dyes such as d18, CIDirectBlack19, CIDirectBla
ck38, CIDirectBlack154, CIDirectOrange6, C.
I.DirectYellow44, CIDirectYellow87, CIDirectBl
direct dyes such as ue71.

The ink composition of the present invention contains water, an aqueous medium, a preservative, a rust preventive, a sequestering agent, a surfactant, a dispersant, as components other than the above-mentioned thickening gelling agent and coloring agent.
Known components conventionally used, such as pH adjusters, can be added to this type of aqueous gel ink for ballpoint pens.

As the aqueous medium, an organic compound miscible with water is used, and alcohols, glycol ethers, polar organic solvents, and the like are used. Specifically, examples of alcohols include monohydric alcohols such as ethanol and isopropyl alcohol, ethylene glycol, diethylene glycol, triethylene glycol, 1,3 propanediol, propylene glycol, 1,3 butylene glycol, 1,4 butanediol, Dihydric alcohols such as 2,3 butylene glycol, neopentyl glycol, hexylene glycol, thiodiglycol, glycerin, trimethylolethane, trimethylolpropane,
Polyhydric alcohols such as 3-methylpentane-1,3,5-triol, diglycerin, and sorbite;
Examples of glycol ethers include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, and the like. 2-pyrrolidone, dimethylformamide and the like.

Examples of the pH adjuster include sodium hydroxide, sodium carbonate, triethanolamine and the like; surfactants such as anionic and nonionic surfactants; rust preventives such as benzotriazole; preservatives; As sequestering agents such as methyl-P-hydroxybenzoate, potassium sorbate, sodium pentachlorophenol, and sodium dehydroacetate;
DTA and the like. These additives are added in appropriate amounts as needed.

[0024]

EXAMPLES Specific examples of the present invention will be described below. Examples 1 to 4 The components shown in Table 1 below were mixed to obtain metallic color inks shown in the same table.

[0025]

[Table 1] In the above table, all units are parts by weight. * 1: About 20% by weight of blue pigment component * 2: About 20% by weight of green pigment component * 3: About 20% by weight of red pigment component * 4: Sequestering agent (manufactured by Meisei Chemical Industry Co., Ltd.) * 5: Synthetic hectorite thickening gelling agent [manufactured by Nippon Silica Industry Co., Ltd.]

FIG. 2 shows the results of measuring the viscosity of the metallic red ink of Example 4. The viscosity was measured at a temperature of 25 ° C. using a R115 type viscometer manufactured by Toki Sangyo Co., Ltd. and a RC-105A type computer manufactured by Toki Sangyo Co., Ltd. As a reference example, the results of measuring the viscosity of a commercially available metallic color gel ink are shown in the same table.

Comparative Example 1 The same composition as in Example 1 was used except that xanthan gum was omitted. Comparative Example 2 The composition was the same as in Example 1 except that Laponite S was omitted. The inks of Example 1 and Comparative Examples 1 and 2 were filled in ink storage tubes, and the results of sedimentation, separation, and writing quality were tested immediately after production and after storage, and Table 2 shows the results. still,
After storage, the state after storage at 50 ° C. for 7 days is shown.

[0028]

[Table 2]

In the test of sedimentation separation, when the ink filled in the ink storage tube was visually observed, there was no sedimentation, and there was no color unevenness when actually written, and the case where there was sedimentation or color unevenness was evaluated. X. In addition, in the test of writing taste, when writing was actually performed, the case where smooth writing was performed was evaluated as ○, and when the case where smooth writing was not performed was evaluated as X.

[0030]

As described above, the ink of the present invention has excellent thixotropic properties by using xanthan gum and a hectorite-based inorganic thickener as a thickening gelling agent. As compared with an ink using as a thickening gelling agent, the amount of aluminum powder added can be increased, and an excellent ink having good writing characteristics and strong metallic luster can be obtained.

Further, a coloring agent other than aluminum powder can be added to the ink without lowering the writing characteristics, and a colorful metallic color ink colored in various colors can be obtained.

Further, compared with the conventional ink using only xanthan gum as a thickening gelling agent, the amount of added xanthan gum can be reduced, so that coloring and dulling of xanthan gum are prevented, and a clear metallic Color is obtained.

Further, in the ink of the present invention, since the hectorite-based inorganic thickener is hardly affected by the temperature, the thixotropic property does not decrease even at a temperature of 50 ° C. or more. Even when the temperature reaches 50 ° C. or more during storage, the gel structure is not broken, the writing taste after storage is not reduced, and the storage stability is excellent.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing the structure of a synthetic hectorite.

FIG. 2 is a graph showing viscosity characteristics of the ink of the present invention.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C09D 11/18

Claims (3)

(57) [Claims] An aqueous ink for a ballpoint pen, comprising aluminum powder and having a metallic luster, comprising xanthan gum and a hectorite-based inorganic thickener as a thickening gelling agent. 2. The amount of addition of a hectry inorganic thickener of 0.
The metallic glossy water-based ink for a ball-point pen according to claim 1, wherein the content is 1 to 0.5% by weight. 3. The water-based metallic luster ink for ball-point pens according to claim 1, further comprising a colorant other than aluminum powder.