JPH0770495A - Liquid ink - Google Patents

Abstract

(57) [Summary] [Object] To provide a liquid ink in which color separation due to floating or sedimentation is difficult to occur by microencapsulating two or more kinds of pigments having different colors and specific gravities contained in the liquid ink. [Structure] The microcapsules 1 obtained by microencapsulating the pigments 3 and 4 and the solution in which the microcapsules are dispersed have the same specific gravity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a writing instrument and a liquid ink used for print recording.

[0002]

2. Description of the Related Art Heretofore, liquid inks used for writing instruments and print recording have been used by dissolving a dye in a solution which is a main component of the liquid ink as a coloring means. However, liquid inks containing dyes have poor light resistance, and therefore have undergone discoloration and fading during long-term storage. Therefore, a liquid ink using a pigment has been devised in order to prevent the discoloration and fading.
This liquid ink includes one in which a pigment is dispersed in a solution that is the main component of the liquid ink by using a dispersant, and one in which the pigment itself is surface-treated and dispersed in the solution.

When particles such as a pigment are dispersed in a solution, the sedimentation rate of the particles can be expressed by the following equation.

V = de ² (P−P ₀ ) g / 18η where de: particle size P, P ₀ : specific gravity of particles and solution g: gravitational acceleration η: viscosity of solution If the specific gravity and the specific gravity of the solution in which it is dispersed are equal, the sedimentation velocity is 0
Therefore, sedimentation or floating of the pigment does not occur.

[0005]

However, in the liquid ink using a pigment as the coloring means, the specific gravity of the pigment itself used is not necessarily the same as the specific gravity of the solution which is the main component of the liquid ink. Therefore, if left unused for a long period of time, there is a problem with stability over time, such as sedimentation or floating of the pigment, and printing defects such as ink clogging and insufficient density occur. Further, when the pigment is finely dispersed up to the primary particles in order to prevent the pigment from settling or floating, there is a problem that the hiding power of the ink itself becomes weaker this time. Furthermore, if you want to set the color of the ink arbitrarily, you will use multiple types of pigments with different colors,
This caused more serious problems such as aggregation of pigments and color separation due to the difference in specific gravity.

The present invention has been made to solve the above-mentioned problems, and provides a liquid ink in which the pigment dispersed in the liquid ink is unlikely to cause sedimentation, floating, aggregation, color separation, and the like. Is intended.

[0007]

To achieve this object, the liquid ink of the present invention contains a plurality of types of pigments having different specific gravities in microcapsules, and the specific gravity of the pigment-containing microcapsules is defined as the specific gravity of the solution. It is characterized by eliminating the difference in specific gravity from the solution by preparing the same.

[0008]

According to the liquid ink of the present invention having the above-mentioned constitution, the microcapsules obtained by containing two or more kinds of pigments having different specific gravities so as to be equal to the specific gravity of the solution are put in the solution. By dispersing, the pigment does not settle or float even if it is left for a long time, and a stable pigment dispersion state can be maintained for a long time.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

The liquid ink of this embodiment is obtained by dispersing microcapsules containing two or more kinds of pigments in the solution containing the main component in the solution containing the main component of the liquid ink. As shown in FIG. 1, this microcapsule 1 comprises a microcapsule wall 2 and a solvent 5 in which pigments 3 and 4 are dispersed.

The pigment used in this embodiment can be selected from inorganic pigments and organic pigments. Inorganic pigments include, for example, zinc white, titanium oxide, red iron oxide, chromium oxide, iron black, complex oxide, titanium yellow, cobalt blue, cerulean blue, cobalt green, alumina white,
Yellow iron oxide, viridian, cadmium yellow, cadmium red, vermilion, lithopone, yellow lead, molybdate orange, zinc chromate, gypsum, barium sulfate, calcium carbonate, lead white, ultramarine, manganese violet, cobalt violet, emerald green, navy blue, Examples include carbon black, aluminum powder, bronze powder, zinc dust and the like.

The organic pigments include, for example, monoazo lake, monoazo, disazo, condensed azo, metal complex salt azo, phthalocyanine, acid dye lake, basic dye lake, anthraquinone, thioindigo, perinone, perylene, quinacridone, dioxazine, isoindolinone, Examples include nitroso, alizarin lake, metal complex salt azomethine, aniline black, and alkali blue.

Microcapsules containing pigments selected from these are obtained by dispersing two or more kinds of pigments in a pigment dispersion medium and microencapsulating them. Examples of the pigment dispersion medium include water, organic solvents, fats and oils. A surfactant or the like can be added to these pigment dispersion media for dispersing the pigment.

The ratio of the pigment in the pigment dispersion medium used here is determined by adjusting the specific gravity of the encapsulated pigment dispersion medium to be equal to the specific gravity of the liquid ink. As a method for encapsulating the pigment dispersion medium, there are known chemical manufacturing methods, physical manufacturing methods, physicochemical manufacturing methods, mechanical manufacturing methods, etc., but mainly interfacial polymerization method, in-situ polymerization method, coacervation method, liquid method. It is produced by a medium drying method, a melt dispersion cooling method, a liquid hardening coating method, or the like.

The material of the microcapsule wall used at this time is polyamide, polyurethane, polyester, polyurea, epoxy resin, polycarbonate, urea resin, melamine resin, phenol resin, gelatin, gum arabic, dextran, casein, protein, cellulose. , Carboxypolymethylene, styrene maleic acid reaction product, polyvinyl alcohol, polysaccharides, polyvinyl acetate, polyvinyl chloride, polyvinylidene chloride, ethyl cellulose, methyl cellulose, polyethylene, polystyrene, natural rubber, nitrocellulose, polymethyl methacrylate, cellulose acetate , Polyacrylic acid ester, polyvinyl formal, polyvinyl pyrrolidone, silicone resin, starch, sodium polyacrylate, hydroxyethyl cellulose Scan, paraffin, beeswax, water wax, hardened beef tallow, carnauba wax, fatty acid, sodium alginate, glycerin, albumin and the like are used.

The microcapsules 1 obtained as described above are dispersed in the solution 6 which is the main component of the liquid ink as shown in FIG. The solution 5 which is the main component of the liquid ink includes, for example, solvents such as aliphatic hydrocarbons, aromatic hydrocarbons, alcohols, ketones, esters, ethers and glycols, vegetable oils, mineral oils and water. To disperse the microcapsules in the liquid ink, use of a dispersant such as a polymer surfactant, an anionic surfactant, a cationic surfactant, a nonionic surfactant, an amphoteric surfactant and a metal soap, Alternatively, it is carried out by a method such as surface modification of microcapsules. In addition, various auxiliary agents such as a plasticizer, a resin, and a wax can be added to the ink.

The present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the invention. For example, the inclusion of microcapsules may be gel-like or solid. For example, by a method such as a spray coagulation method, the pigment can be dispersed in a solid substance such as gelatin / acacia, methylcellulose, carboxymethylcellulose, sodium alginate, polyvinylpyrrolidone, and tragacanth, and then encapsulated.

[0018]

As is clear from the above description, the liquid ink of the present invention can be regarded as one pigment by encapsulating two or more pigments having different colors and specific gravities. In addition, when encapsulating, the specific gravity of the solution, which is the main component of the liquid ink, can be made the same, so even when the pigment is left unused for a long period of time, the pigment settles, floats, aggregates the pigments, and Problems such as separation do not occur.

[Brief description of drawings]

FIG. 1 is a configuration diagram of microcapsules dispersed in a liquid ink of the present invention.

FIG. 2 is a configuration diagram of the liquid ink of the present invention.

[Explanation of symbols]

 1 microcapsule 3, 4 pigment

Claims (1)

[Claims] 1. A liquid ink in which at least two or more kinds of pigments having different specific gravities are used as a coloring means, and microcapsules containing the two or more kinds of pigments are dispersed in a solution which is a main component of the ink. A liquid ink, wherein the specific gravity of the capsule is the same as that of the solution.