JPH08143809A - Aqueous ink composition - Google Patents

Abstract

(57) [Summary] [Object] To provide a water-based ink composition excellent in preventing hard cake of a pearl pigment after a long period of time. A water-based ink composition comprising a pearl pigment, a resin, an organic or inorganic pigment as a colorant, and water, wherein the resin has a glass transition temperature of 80 ° C. or higher.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pearly water-based ink composition used for marking pens.

[0002]

2. Description of the Related Art Conventionally, as a pearly water-based ink composition, for example, (1) a daylight fluorescent pigment,
(2) A marking pen containing a hiding property-imparting pigment selected from a pearl pigment consisting of titanium oxide and a mica piece coated with titanium oxide, (3) an alkali-soluble water-soluble resin, and (4) a rosin ester emulsion Aqueous fluorescent pigment ink (Japanese Patent Laid-Open No. 5-45633) is known. Further, a pearl pigment having an average particle diameter of 5 to 100 μm is used in an amount of 5 to 50% by weight based on the total amount of the ink, a dispersant / fixing agent of 5 to 30% by weight based on the total amount of the ink, and a colorant based on the total amount of the ink. A metallic or pearly water-based ink composition characterized by containing 0 to 20% by weight of a dye or a pigment (Japanese Patent Laid-Open No. 5-117569) is also known.

The pearl pigment composed of mica pieces coated with titanium oxide disclosed in the above-mentioned JP-A-5-45633 is a commercially available pigment having a specific gravity of about 3.0 and an average particle diameter of 5 to 100 μm. In low viscosity ink, sedimentation easily occurs in the ink, and when the ink is left for a long time, the precipitated pearl pigment forms a hard cake and the stirrer moves in the pen. There was a problem to limit. In addition, there is a problem in that the ink that has flown out without sufficient ink agitation does not contain a pearl pigment, or has a very small content, and an ink that does not have a pearly feel will flow out.

In order to prevent these problems, various additives are added to disperse the pearl pigment to form a system which is difficult to settle, or a composition which is easily redispersed even when settling. Although a pearlescent water-based ink composition having the composition of (for example, JP-A-5-117569) has been proposed, these are effective for the initial dispersion, but are hard-cake after a long period of time. Is insufficient to prevent,
At present, there is a problem that the desired effect has not been achieved.

[0005]

Means for Solving the Problems In view of the above-mentioned conventional problems, the present inventor has conducted diligent research, and as a result, by mixing a water-soluble resin having a specific glass transition temperature, a pearl pigment after a long time has passed. It was found that the present invention is extremely effective in preventing the hard cake, and completed the present invention. That is, the water-soluble ink composition of the present invention is a water-soluble ink composition comprising a pearl pigment, a resin, an organic pigment or an inorganic pigment and water, wherein the glass transition temperature of the resin is 80 ° C. or higher. . The resin is preferably an emulsion and / or an alkali neutralized salt. The resin component is styrene, acrylonitrile, a homopolymer of acrylic acid ester, or
These co-polymers are preferred.

[0006]

In the aqueous ink composition comprising the pearl pigment of the present invention, the resin, the organic pigment or the inorganic pigment as the colorant, and water, the reason why the resin having a glass transition temperature of 80 ° C. or higher has a good hard cake preventing property is It is guessed as follows. That is, in an aqueous ink composition consisting of a pearl pigment, a resin, an organic pigment or an inorganic pigment as a colorant, and water, the pearl pigments settle down due to gravity, and when further compressed, a low glass adsorbed on the pearl pigment surface. In a resin having a transition temperature, since the molecular chains can actively move, the molecular chains are entangled with each other and behave like an adhesive, whereas in the present invention, the molecular chains have a high glass transition point. Since it is in a frozen state, it is considered that there is no entanglement of the molecular chains, but rather it acts as a spacer between the pearl pigments and exhibits an effect of preventing hard cake (this point will be described in more detail).

The contents of the present invention will be described below. Examples of the resin used in the present invention include styrene, acrylonitrile, homopolymers of acrylic acid esters, or copolymers thereof, that is, styrene-acrylonitrile copolymer, styrene-acrylonitrile-
Examples thereof include acrylic acid ester copolymers, acrylonitrile-acrylic acid ester copolymers, and styrene-acrylic acid ester copolymers. These resins are preferably emulsions and / or alkali (ammonia, sodium hydroxide) neutralized salts from the viewpoint of dispersibility and addition to water-based inks.

Further, these resins are selected from those having a glass transition temperature of 80 ° C. or higher and used alone or in combination of two or more kinds. When a material having a glass transition temperature of less than 80 ° C. is used, even if it has an effect on the initial dispersion, it becomes insufficient for the prevention of hard cake after a long period of time, so that it may be present in the pen body. Since the stirrer is buried and a hard sediment is formed, the stirrer does not move, which is not preferable.

The higher the compounding ratio of the resin in the composition, the higher the effect. However, it is desirable to add the resin so that the necessary physical properties such as the viscosity of the ink and the characteristics as a pen can be obtained. 40% by weight, preferably 15-25
% By weight.

The pearl pigment used in the present invention comprises a mica piece coated with a metal oxide having a high refractive index such as titanium oxide or iron oxide, and has a layer of a metal oxide having a high refractive index and a low refractive index. The light reflected at the boundary with the layer of mica,
A pearl luster is provided, and an average particle size of 15 μm or less is preferable. The mixing ratio of the pearl pigment in the composition can be arbitrarily used, but preferably,
It is used in the range of 10 to 20% by weight. If it is less than this amount, the pearly feeling is insufficient and it is not practical, and if it is too much, the viscosity of the liquid becomes too high and the ink outflow from the capillary of the pen tip is alienated.

As the organic pigment and the inorganic pigment used as a colorant in the present invention, general pigments which are generally used in writing instrument inks are used. Examples of the inorganic pigments include Pigment Black 6, 7, 9, 10, 1
1, Pigment Red 101, 105, 106, 10
7, 108, Pigment Blue 27, 28, 29, 3
5, Pigment Green 17, 18, 19, 21 and the like. Examples of organic pigments include Pigment Black 1, Pigment Red 1, 2, 3, 4, 5,
7, 9, 12, 22, Pigment Blue 1, 2, 15,
16, 17, and Pigment Greens 2, 7, 8, 10 and the like. Further, what is called a plastic pigment in which a resin is dyed is also usable.

The blending ratio of the pigment in the composition is 0.
It is used in the range of 5 to 5% by weight, preferably 1 to 3% by weight. If the amount is less than this amount, the density of the handwriting is insufficient and it is not practical, and if the amount is too large, the pearl pigment itself is colored and the pearl feeling is reduced. The pigments for coloring are
The powder may be mixed as it is, or may be mixed as already dispersed. In any case, it is desirable that the composition is such that the mechanism of the pen to be used and the desired line density are taken into consideration.

In the water-based ink composition of the present invention, a surfactant, a water-soluble resin as a fixing agent, a resin emulsion, a pH adjusting agent, a quick-drying agent for controlling a drying rate, or A slow-drying organic solvent, a preservative, etc. are added.

[0014]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In addition, Tg shows a glass transition point.

Example 1 Pearl pigment (Iriogen 111, manufactured by Merck-Jaun Co., Ltd., particle size: 15 μ or less) 13% by weight Styrene-acrylic acid ester copolymer resin aqueous solution 60% by weight (Cybinol EK-1000, manufactured by Cyten Chemical Co., Ltd., Tg) 86 ° C, solid content 36%) Phthalocyanine green (CI high green 7) 3% by weight Ethylene glycol 10% by weight Water 14% by weight Total 100% by weight

Example 2 Pearl pigment (Iriogen 111, manufactured by Merck Jahn KK, particle size: 15 μ or less) 13% by weight Styrene-acrylonitrile copolymer resin emulsion 50% by weight (Mobinyl 970 Hoechst Synthetic Co., Ltd., Tg 102 ° C., solid) Min 40%) Phthalocyanine green (CI high green 7) 3% by weight Ethylene glycol 10% by weight Water 14% by weight Total 100% by weight

Example 3 Pearl pigment (Iriogen 111, manufactured by Merck Jahn Co., Ltd., particle size: 15 μ or less) 13% by weight Styrene resin emulsion 40% by weight (C-10, Showa High Polymer Chemical Co., Ltd., Tg 100 ° C., solid content 50) %) Phthalocyanine Green (CI High Green 7) 3% by weight Ethylene glycol 10% by weight Water 34% by weight Total 100% by weight

Comparative Example 1 Pearl pigment (manufactured by Iriogen 111, Merck & Co., Inc., particle size: 15μ or less) 13% by weight Styrene-acrylic acid ester copolymer resin aqueous solution 60% by weight (JONCRYL J-61J Jonson & Jonson Co., Ltd.) Manufactured by Tg 70 ° C, solid content 30%) Phthalocyanine green (CI high green 7) 3% by weight Ethylene glycol 10% by weight Water 14% by weight Total 100% by weight

Comparative Example 2 Pearl pigment (manufactured by Iriogen 111, Merck Jahn Co., Ltd., particle size: 15 μm or less) 13% by weight Styrene-acrylic ester copolymer resin Emuljun 60% by weight (AE-137, Tg manufactured by Japan Synthetic Rubber Co., Ltd.) 48 ° C, solid content 35%) Phthalocyanine green (CI high green 7) 3% by weight Ethylene glycol 10% by weight Water 14% by weight Total 100% by weight

Comparative Example 3 Pearl pigment (Iriogen 111, manufactured by Merck Jahn Co., Ltd., particle size: 15μ or less) 13% by weight Styrene-acrylic ester copolymer resin emulsion 40% by weight (Tg manufactured by AE-333 Nippon Synthetic Rubber Co., Ltd.) Phthalocyanine green (CI high green) 7% 3% by weight Ethylene glycol 10% by weight Water 34% by weight Total 100% by weight

The compositions of the above Examples and Comparative Examples were mixed and dispersed with a stirrer for 3 hours to obtain a pearl ink. Put the adjusted ink into a glass bottle with a bottom diameter of 30 mm and a height of 70 mm so that the liquid surface height is 50 mm.
After centrifuging 3000G for 30 minutes to force the pearlescent pigment to settle, a stainless steel ball (weight: 1.1 g) with a diameter of 6.45 mm was dropped onto the sediment from the liquid surface to reduce the hardness of the sediment. It was judged.

Further, each ink is equipped with a valve mechanism, and a stainless ball having a diameter of 6.45 mm (weight 1.1
g) 10 pens each with a built-in pen, and assemble
After leaving the pen tip side up for 1 month at room temperature, each sample pen was shaken up and down, the number of times until the ball moved was measured, and the average of 10 balls was calculated. The results are shown in Table 1 below.

[0023]

[Table 1]

(Discussion of Table 1) Examples 1 to 3 are cases in which resins having a glass transition temperature of 80 ° C. or more, which is within the scope of the present invention, are used, Example 1 is Tg 86 ° C., and Example 2 is Tg. 102
C., Example 3 has Tg of 100.degree. On the other hand, in Comparative Examples 1 to 3, the glass transition temperature outside the scope of the present invention is 80 ° C.
Comparative Example 1 is a case of using a resin of less than Tg 70
C., Comparative Example 2 has a Tg of 48.degree. C., and Comparative Example 3 has a Tg of 0.degree. As is clear from the drop test of the stainless steel ball and the number of times the ball moves as shown in Table 1, Examples 1 to 3
It can be seen that forms a softer precipitate than Comparative Examples 1 to 3.

[0025]

According to the present invention, in order to prevent the hard cake of the pearl pigment after a long period of time, the stirrer present in the pen can easily stir the ink and cause the ink to flow out. As the ink, a water-based ink composition that provides an excellent pearlescent line is provided. Further, since a commercially available stirrer can be used, and the weight and the number of the stirrers can be reduced, the efficiency of manufacturing the product is improved, and the raw material cost and labor cost of the product can be suppressed to a low cost.

Claims (4)

[Claims] 1. A water-based ink composition comprising a pearl pigment, a resin, an organic pigment or an inorganic pigment as a colorant, and water, wherein the resin has a glass transition temperature of 80 ° C. or higher. 2. The resin is an emulsion.
The water-based ink composition described. 3. The water-based ink composition according to claim 1, wherein the resin is an alkali-neutralized salt. 4. The water-based ink composition according to claim 1, wherein the resin component is styrene, acrylonitrile, a homopolymer of acrylic acid ester, or a co-polymer thereof.