JP2000103998A - Water-based ink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ink excellent in both drying resistance of an ink discharging part such as a pen point in writing utensils, recorders, or the like, and drying properties of a handwriting. SOLUTION: This water-based ink contains at least 2-20 wt.% of a colorant such as a dye or a pigment, 30-80 wt.% of water and a crosslinked gelatin at a concentration so as to provide 0.01-10 wt.% ratio of the added gelatin based on the total amount of the ink.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based ink used for a writing instrument, a recorder and the like, and more particularly to a water-based ink having excellent drying resistance of an ink discharge portion such as a pen tip.

[0002]

2. Description of the Related Art Conventionally, aqueous inks used for writing instruments, recorders, and the like contain at least a coloring material and water. Further, in order to improve the drying resistance of an ink discharge portion such as a pen tip, It has been proposed to use a hygroscopic water-soluble organic solvent such as a glycol solvent, a glycol ether solvent, a glycol ether ester solvent, or an amine solvent.

[0003]

However, when the hygroscopic water-soluble organic solvent is added to improve the drying resistance of the nib of the water-based ink, there arises a problem that the drying property of the handwriting is deteriorated. It was difficult to improve both the drying resistance of the pen tip and the drying property of the handwriting.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a water-based ink having excellent drying resistance at an ink discharge portion such as a pen tip without deteriorating the drying property of a handwriting. A water-based ink characterized by including at least a material, water and cross-linked gelatin.

Hereinafter, the present invention will be described in detail. As the coloring material, a water-soluble dye and a pigment can be used. Water-soluble dyes
Any of direct dyes, acid dyes, food dyes, and basic dyes can be used.

An example of a direct dye is described below. C.
I. Direct Black 17, 19, 22, and 3
2, 38, 51, 71, C.I. I. Direct Yellow 4, 26, 44, 50, C.I. I. Direct Red 1, 4, 4, 23, 31, 37, 39, 7
5, 80, 81, 83, 225, 226, 227, C.I. I. Direct Blue 1, 15, 15
1, 86, 106, and 199.

One example of an acid dye is described below. C.
I. Acid Black 1, 2, 24, 26, 3
1, 52, 107, 109, 110, 11
9, 154, C.I. I. Acid Yellow 7: 1, 1
7, 19, 23, 25, 29, 38, 4
2, 49, 61, 72, 78, 110, 1
41, 127, 135, 142, C.I. I. Acid Red 8, 9, 14, 18, 18, 26, 27,
35, 37, 51, 52, 57, 82, 87, 92, 94, 111, 129, 13
1, 138, 186, 249, 254, 26
5, 276, C.I. I. Acid Violet 15, 17 and C.I. I. Acid Blue 1, 7, 9, 9
5, 22, 23, 25, 40, 41, 4
3, 62, 78, 83, 90, 93, 10
3, 112, 113, 158, C.I. I. Acid Green 3, 9, 16, 25, 27, and the like.

[0008] Food dyes are mostly contained in direct dyes or acid dyes.
C. I. Food Yellow 3.

An example of the basic dye is described below. C.
I. Basic Yellow 1, 2 and 21, C.I. I. Basic Orange 2, 14, 32 and C.I. I. Basic Red 1, 2, 9, 14, C.I. I. Basic Violet 1, 3 and 7, C.I. I. Basic Blue 3, 26, C.I. I. Basic Green 4, C.I.
I. Basic Brown 12, C.I. I. Basic Black 2, 8 and the like.

[0010] These dyes can be used alone or in combination. The amount used is 2 to the total amount of the aqueous ink.
It is preferable to add 20% by weight.

As pigments, ocher, barium yellow, navy blue,
Inorganic pigments such as cadmium red, titanium oxide, red iron oxide, iron black, and carbon black; organic pigments such as azo pigments, phthalocyanine pigments, nitroso pigments, nitro pigments, basic dye lake pigments, and acid dye lake pigments; Pigments such as a colored resin pigment obtained by coloring fine particles of a high molecular compound with a dye or a pigment are exemplified.

These pigments can be used alone or in combination of two or more. The amount used is 2% based on the total amount of aqueous ink.
It is preferable to add 〜20% by weight.

When a pigment is used as a colorant, it is necessary to use a dispersant in view of the dispersibility of the pigment, the stability of the ink over time, and the workability during the production of the ink. As the dispersant, a resin dispersant, a nonionic surfactant, and an anionic surfactant can be used.

An example of the resin-based dispersant is described below. Styrene-acrylic acid copolymer salt, styrene-acrylic acid alkyl ester-based copolymer salt, styrene-maleic acid copolymer salt, styrene-maleic acid alkyl ester-based copolymer And coalesced salts.

An example of the nonionic surfactant is described below. Glycerin fatty acid ester, polyglycerin fatty acid ester, propylene glycol fatty acid ester, pentaerythritol fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbite fatty acid ester, polyoxyethylene glycerin fatty acid ester, polyethylene glycol fatty acid ester, polyoxyethylene methyl ether , Polyoxyethylene phytosterol, polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene castor oil, polyoxyethylene hydrogenated castor oil, polyoxyethylene lanolin, polyoxyethylene lanolin alcohol, polyoxyethylene alkyl Amine, polyoxyethylene fatty acid amide, polio Such as shea alkylphenyl formaldehyde condensates and the like.

One example of the anionic surfactant is described below. Alkyl sulfate, polyoxyethylene alkyl ether sulfate, N-acyl amino acid salt, N-acylalkyl taurine salt, polyoxyethylene alkyl ether acetate, alkyl phosphate, polyoxyethylene alkyl ether phosphate, and the like.

These dispersants can be used alone or as a mixture of two or more. It is preferable to add 0.01 to 6.0% by weight based on the total amount of the aqueous ink.

Water is used as a main solvent, and its amount is preferably 30 to 80% by weight based on the total amount of the aqueous ink.

The crosslinked gelatin which is the essence of the present invention is obtained by mixing gelatin, which is a kind of derived protein obtained by partially hydrolyzing collagen, with a crosslinking agent in the presence of water to chemically crosslink. And is used to improve the drying resistance of an ink discharge portion such as a pen tip. The amount of gelatin used in the crosslinked gel was 0.1% based on the total amount of the aqueous ink.
It is preferably from 0.01 to 10% by weight. This is because it is preferable to use 0.01% by weight or more in order to impart sufficient drying resistance to the ink discharge section, and it is preferable to use 10% by weight or less in order to sufficiently discharge the ink from the ink discharge section. is there. Examples of the crosslinking agent include a polymer compound having a carboxyl group such as poly-L-glutamic acid.

In addition to the components described above, a water-soluble organic solvent may be used, if necessary, for moisturizing and / or preventing freezing. Examples thereof include alcohols such as methanol, ethanol, propanol, isopropanol, butanol, and isobutanol; glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3 butylene glycol, and thiodiglycol; and ethylene glycol. Monoalkyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, N-methyl-2-
Examples include pyrrolidone, sorbit, sorbitan, acetin, glycerin and the like. These water-soluble organic solvents can be used alone or as a mixture of two or more. The amount used is preferably 1 to 50% by weight based on the total amount of the aqueous ink.

Further, preservatives, fungicides, moisturizing assistants such as urea, thiourea, ethylene urea and derivatives thereof, water-soluble natural polymers for adjusting the viscosity of ink, and water-soluble synthetic polymers Various additives such as molecules, rust inhibitors for preventing corrosion of metal parts, surfactants, defoamers, and alkali agents can be appropriately selected and used.

The aqueous ink can be prepared by mixing and stirring using a conventionally known stirrer when a dye is used as a coloring material, and by using a conventionally known dispersing machine or a necessity when using a pigment. Accordingly, it can be obtained by dispersing and mixing using a combination of stirrers.

[0023]

The cross-linked gelatin used in the aqueous ink of the present invention has a structural feature that chemical cross-linking due to a covalent bond is present, and has a property of forming a gel film when its concentration is increased. When the solvent (especially water) in the ink evaporates at the ink discharge section such as the pen tip and the concentration of the cross-linked gelatin increases, the cross-linked gelatin forms a gel film on the pen tip surface, so that the solvent is no more. It is considered that evaporation is suppressed and the ink nib drying resistance is improved. It should be noted that ordinary gelatin also produces a gel under appropriate concentration and temperature conditions, but it is difficult to form a film because the force for holding the gel is hydrogen bonding. Further, since the gel formed by hydrogen bonding has a variable structure, the evaporation of the solvent by the film is not completely suppressed, and the ability to prevent drying of the pen tip is insufficient. Further, the gel coating formed by the crosslinked gelatin on the pen tip surface is a brittle coating that is strong enough to suppress the evaporation of the solvent. Therefore, the film is easily broken by normal writing pressure, and normal writing can be performed after the film is formed. Further, unlike the conventionally used hygroscopic water-soluble organic solvent, the crosslinked gelatin does not have hygroscopicity, and its use amount may be small, so that it is presumed that the dryness of the handwriting is also good. .

[0024]

The present invention will be described in more detail with reference to the following examples.

Example 1 CI Basic Red 14 3.0 parts by weight Ethylene glycol 20.0 parts by weight Crosslinked gelatin (gelatin content: 5% by weight) 50.0 parts by weight Benzotriazole (rust inhibitor) 0.1 parts by weight water 26.9 parts by weight Each of the above components was heated to 40 to 50 ° C and stirred for 2 hours to obtain an aqueous red ink.

Example 2 CI Direct Blue 199 5.0 parts by weight Propylene glycol 7.0 parts by weight Thiodiglycol 5.0 parts by weight Crosslinked gelatin (gelatin content: 4% by weight) 25.0 parts by weight Collagen 3.0 parts by weight Proxel GXL (antifungal agent: manufactured by Zeneca Corporation) 0.1 part by weight EFTOP EF122C (fluorinated surfactant: manufactured by Shin-Akita Chemical Co., Ltd.) 0.01 part by weight water 54.89 Parts by weight Each of the above components was made in the same manner as in Example 1 to obtain an aqueous blue ink.

Example 3 8.0 parts by weight of carbon black 5.0 parts by weight of glycerin 61.5 parts by weight of crosslinked gelatin (gelatin content: 13% by weight) Ammonium salt of styrene-acrylic acid copolymer (dispersant) 2 2.0 parts by weight 25% aqueous sodium hydroxide solution 0.1 parts by weight Proxel GXL (described above) 0.2 parts by weight Water 23.2 parts by weight After stirring the above components for 2 hours with a stirrer, dispersing them for 2 hours with a bead mill. Thus, an aqueous black ink was obtained.

Example 4 CI Acid Black 2 8.0 parts by weight Propylene glycol 20.0 parts by weight Crosslinked gelatin (gelatin content: 2% by weight) 2.5 parts by weight Proxel GXL (described above) 0.2 parts by weight 69.9 parts by weight of water The above components were made in the same manner as in Example 1 to obtain an aqueous black ink.

Example 5 NKW-3602 (colored resin pigment, solid content: 36% by weight: manufactured by Nippon Fluorescent Chemical Co., Ltd.) 38.0 parts by weight Glycerin 5.0 parts by weight Crosslinked gelatin (gelatin content: 1%) 30 0.0 parts by weight Proxel GXL (described above) 0.4 part by weight Water 26.6 parts by weight The above components were made in the same manner as in Example 1 to obtain an aqueous yellow-green ink.

Comparative Example 1 CI Basic Red 14 3.0 parts by weight Ethylene glycol 20.0 parts by weight Benzotriazole (described above) 0.1 part by weight Water 76.9 parts by weight A water-based red ink was obtained in the same manner as described above.

Comparative Example 2 CI Direct Blue 199 5.0 parts by weight Propylene glycol 12.0 parts by weight Thiodiglycol 5.0 parts by weight Proxel GXL (described above) 0.1 part by weight Ftop EF122C (fluorine-based interface) (Activator: Shin-Akita Chemical Co., Ltd.) 0.01 parts by weight Water 77.89 parts by weight The above components were made in the same manner as in Example 1 to obtain an aqueous blue ink.

Comparative Example 3 8.0 parts by weight of carbon black 6.9 parts by weight of glycerin Ammonium salt of styrene-acrylic acid copolymer (described above) 2.0 parts by weight 0.1 part by weight of 25% aqueous sodium hydroxide solution Proxel GXL (Described above) 0.2 parts by weight Water 76.7 parts by weight Each of the above components was made in the same manner as in Example 1 to obtain an aqueous black ink.

Comparative Example 4 CI Acid Blue 9 5.0 parts by weight Ethylene glycol 25.0 parts by weight Glycerin 20.0 parts by weight Proxel GXL (described above) 0.2 parts by weight Water 49.8 parts by weight Each of the above components In the same manner as in Example 1 to obtain an aqueous blue ink.

2.0 g of the water-based inks obtained in Examples 1 to 5 and Comparative Examples 1 to 4 were filled in a commercially available sign pen (S520, manufactured by Pentel Co., Ltd.), and the nib drying resistance and handwriting drying property Was tested. Table 1 shows the results.

Pen tip drying resistance test: After leaving the writing implement with the pen tip exposed under the conditions of a temperature of 25 ± 5 ° C. and a humidity of 65 ± 20%, handwriting on fine paper (every 5 minutes) The time it takes for writing to occur and the handwriting to be blurred (unit:
Min) was measured.

Handwriting dryness test: Handwriting is performed on high quality paper, and a high quality paper with a load of 500 g is applied on the handwriting.
Time until ink transfer stops (unit: seconds)
Was measured.

[0037]

[Table 1]

[0038]

As described above, the water-based ink of the present invention is excellent in both the drying resistance of the ink discharge part such as the pen tip and the drying property of the handwriting, and is similar to the conventional water-based ink. It has excellent properties that are unlikely to cause blurring due to pre-drying.

Claims (1)

[Claims] 1. An aqueous ink comprising at least a colorant, water and crosslinked gelatin.