JPH064804B2 - Water based ink - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-viscosity water-based ink applied to a writing instrument in which ink is led out to a pen tip through a capillary-sized ink conduction path. In particular, the present invention relates to a water-based ink which gives water-resistant writing or recording even on the surface of an ink-impermeable plastic.

2. Description of the Related Art A large number of water-based inks for writing instruments or recording pens that give water-resistant handwriting or recording on a paper surface, or water-based inks for writing instruments or recording pens on ink-impermeable plastics have been proposed. These are various resin emulsions, water-soluble resins, specific water-soluble organic solvents, surfactants, or a combination thereof for the purpose of imparting water resistance to handwriting and enabling writing on hydrophobic surfaces such as plastics. It teaches water-based inks with added. However, water-based inks that give this kind of water-resistant handwriting, when the pen tip of a writing instrument or recording pen is in an open state, an insoluble product is deposited on the surface of the pen tip due to evaporation of water, and the pen is There was a tendency for the ink to flow out from the inside of the body to the surface of the pen tip and to appear as a blur phenomenon.

In addition, almost no water-based inks that give water-resistant handwriting to both paper and plastics surfaces have been disclosed, and there are inks in which pigments are dispersed in a slightly high-viscosity aqueous vehicle. The high-viscosity ink has a very thick porous pen body and is practically used only for a marking pen (so-called paint marker) of a type in which ink in a container is sent to the pen body through a valve mechanism. . Since such a coloring liquid for a paint marker contains particles and has a high viscosity, it is difficult to apply it to a fountain pen for fine characters, a sense pen and a recorder pen for a recorder.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention is applied to a writing instrument such as a fountain pen, a felt-tip pen, and a ballpoint pen having a thin pen tip through which ink is led to a pen tip through a capillary-sized ink conduction path, and not to mention the paper surface. In particular, it is an object of the present invention to provide a low-viscosity water-based ink for a writing instrument, which brings water-resistant handwriting even on an ink-impermeable plastic surface, but does not cause ink clogging of the pen tip even in an open pen tip.

The aqueous ink of the present invention is obtained by reacting an acid dye, a direct dye and a water-soluble dye having active hydrogen with a compound having an epoxy group in an aqueous vehicle containing a partially sulfonated polyester resin. It is a composition obtained by dissolving one or more dyes selected from the group consisting of products (hereinafter abbreviated as epoxy addition dyes).

The acidic dye is selected from the dyes classified as acidic dyes of Color Index, and belongs to azo type and their metal complex salts, anthraquinone type, triphenylmethane type and xanthene type in terms of chemical structure.

The direct dye is selected from dyes classified as direct dyes of Color Index, and in terms of chemical structure, azo-based and metal complex salts thereof, stilbene-based, thiazole-based, dioxazine-based,
It belongs to the phthalocyanine series.

The epoxy addition dye is obtained by reacting a water-soluble dye having active hydrogen with a compound having an epoxy group and is represented by the following formula.

(D) _m — (CH ₂ —CH (OH) —R) _n where D is a dye residue, R is a C _{1 to} C ₄ alkyl group, or —CH ₂ OR ¹ (R ₁ is H, branched Optionally represents a C _{1 to} C ₅ alkyl group, a C _{1 to} C ₅ alkenyl group, a (meth) acrylic acid group, propyltrimethoxysilane or a polyhydric alcohol residue having a molecular weight of 300 or less), m is 1 or 2, n represents the number of 1-4.

This type of epoxy addition dye is described in detail in JP-A-61-14270, and the compounds described in that publication are preferably used.

These dyes are used in the ink composition in an amount of 4 to 10% by weight based on the total amount.

The partially sulfonated polyester resin is a linear polyester having a skeleton of a dicarboxylic acid and a diol, and a part of either of the two components has an aromatic ring to which a sulfonic acid group is bonded. The part is polyethylene glycol having 2 to 10 repeating units. As the dicarboxylic acid component, malonic acid, succinic acid,
Adipic acid, sebacic acid, maleic acid, fumaric acid, cyclohexanedicarboxylic acid, phthalic acid, naphthalenedicarboxylic acid, and derivatives thereof are listed, and as the diol component, ethylene glycol, propylene glycol, 1,3-propanediol, diethylene glycol, Examples thereof include triethylene glycol, polyethylene glycol, cyclohexanediol, dihydroxybenzene, methylenediphenol, thiodiphenol, biphenol and derivatives thereof, and examples of the component having an aromatic ring to which the sulfonic acid is bound include sulfoisophthalic acid and sulfo. Terephthalic acid, sulfophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid, sulfodimethylisophthalic acid, 4'-sulfophenyl-3,5-dicarbomethoxybenzenesulfonate, 6 '-Sulfo-2'-naphthyl-
3,5-dicarboxybenzene sulfonate, 5- [4'-
(Sulfo) -phenoxy] isophthalic acid, 5- [4'-
(Sulfo) -phenoxy] terephthalic acid, 2-sulfo-
Examples are 1,4-dihydroxybenzene and alkali metal salts thereof.

The resin is used in an amount of 5 to 10% by weight based on the total amount in the ink composition, and is used in an amount of 1 to 2 times the weight of the dye. The use of larger amounts leads to highly viscous inks, making them unsuitable as inks for writing instruments with capillary-sized ink conduits. Inks suitable for said applications are those which exhibit a low viscosity of less than 10 cPs at about 20 ° C.

The vehicle of the aqueous ink of the present invention comprises the partially sulfonated polyester resin dispersed or dissolved in water,
If necessary, glycols such as ethylene glycol, propylene glycol, diethylene glycol, polyethylene glycol, etc., glycol ethers such as ethylene glycol monomethyl ether, propylene glycol monomethyl ether, etc., glycerin, 2-pyrrolidone, N-sotylpyrrolidone, dimethylimidazolinone, etc. Moisturizers selected from among the above, plasticizers of the above resins such as phthalates, volatile organic solvents such as ethanol and propanol for speeding up the drying of handwriting, wettability to the hydrophobic surface of the ink, and permeability to the capillary channels. A modifying surfactant, a pH adjusting agent, a rust preventive, a preservative and the like may be added.

Action As described above, the partially sulfonated polyester resin has various hydrophilic parts and hydrophobic parts in the structure, so that the water-based ink containing the same is compatible with various surfaces, and the dye in the ink associates with the resin at a part that is compatible with each other. It is considered that the handwriting obtained in this state is water resistant.

Examples Example inks were prepared as follows.

(1) Preparation of Partial Sulfonated Polyester Resin Aqueous Dispersion While stirring in hot water of about 90 ° C., add a predetermined amount of resin and
Stir for 40 minutes to dissolve and disperse the resin, and allow to cool.

An aqueous resin dispersion having the following composition was obtained.

Resin A aqueous dispersion Partially sulfonated polyester resin A 28 parts by weight Dimethyl phthalate (plasticizer) 3 parts by weight Water 69 parts by weight Resin B aqueous dispersion Partially sulfonated polyester resin B 25 parts by weight Water 75 parts by weight Resin C aqueous dispersion Liquid Partially sulfonated polyester resin C 30 parts by weight Water 70 parts by weight The properties of the partially sulfonated polyester resin used are as follows.

(2) Preparation of ink A predetermined amount of dye, the partially sulfonated polyester resin aqueous dispersion, other additives and the remaining water are mixed to obtain about 90
The mixture was stirred for 2 hours while heating at 0 ° C., cooled, and then filtered and filtered to finish.

Next, the comparative ink was prepared as follows.

A predetermined amount of dye, additives and water were mixed, stirred for 2 hours while heating at 40 to 50 ° C., cooled, and filtered with filter paper to finish the ink.

The contents of the raw materials (note numbers) in Table 1 are as follows.

(1) 15% aqueous solution of direct dye (CIDirect Black 154) (2) Direct dye (CIDirect Black 19) (3) 15% aqueous solution of 1 mol of butyl glycidyl ether addition to 1 mol of direct dye (CIDirect Black 154) (4 ) 15% aqueous solution of 2 mol of acid dye (CIAcid Red 92) and 1 mol of ethylene glycol diglycidyl ether (5) Acid dye (CIAcid Blue 83) (6) Basic dye (CIBasic Violet 1) (7) ~ ( 9) Partial sulfonated polyester resin aqueous dispersion described on pages 8 and 9 (10) Polyacrylic ester emulsion, solid content 44
% (11) Polyvinyl alcohol, average degree of polymerization about 500, degree of saponification
97% (12) 75% solution of sodium salt of sulfosuccinic acid dialkyl ester (13) Polyoxyethylene sorbitan monolaurate (14) 30% aqueous solution of sodium salt of sulfosuccinic acid dialkyl ester Tests (1) to (4) were performed.

A predetermined amount of each ink was filled in a marking pen equipped with a pen tip made of a synthetic resin molding having a capillary ink passage in the axial direction, and the test was performed as a sample pen.

(1) Water resistance of handwriting on paper A sample piece (writing about 10 minutes after writing) on the writing paper A (JIS P3201) with each sample pen was immersed in running water for 1 hour and then dried. The change in handwriting was examined visually and in gray scale.

(2) Handwriting on polyester film A predetermined character group was written on the polyester film with each sample pen, and the state of handwriting was observed.

(3) Water resistance of handwriting on polyester film (2) After writing the film (about 30 minutes after writing) in running water,
After immersing for a period of time, it was dried and examined for changes in handwriting visually and in gray scale.

(4) Writing performance after the sample pen was left open The sample pen was opened, left for 2 hours, and then written on the writing paper A to check the writing property.

The test results are shown in Table 2.

EFFECTS OF THE INVENTION As shown in the results shown in Table 2, the water-based ink of the present invention gives water-resistant handwriting not only to the paper surface but also to the ink-impermeable plastic surface, and nevertheless, the pen tip in an open state. At the same time, no precipitate that prevents the ink from forming is formed.

Claims (1)

[Claims] 1. An ink composition containing 4 to 10% by weight of a total amount of an acid dye, a water-soluble dye selected from a direct dye and an epoxy addition dye, and 5 to 10% by weight of a partially sulfonated polyester resin and water as essential components. The skeleton of the partially sulfonated polyester resin is a linear polyester of a dicarboxylic acid and a diol, and a part of either of the components has an aromatic ring to which a sulfonic acid group is bonded. A structure in which at least a part of the diol component is polyethylene glycol having a repeating unit number of 2 to 10 and a molecular weight of 10,000 to 20,000, and the weight ratio of the dye to the resin is in the range of 1 to 2 resin to 1 dye. And an ink viscosity at about 20 ° C. of less than 10 cPs.