JP2699179B2 - Water-based ink composition for writing - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous ink composition capable of forming a writing portion having excellent washing resistance.

2. Related Art and Problems There have been proposed various water-based ink compositions having excellent water resistance. For example, JP-B-62-256882 discloses an aqueous ink in which an epoxy addition dye obtained by dyeing and reacting with a compound having an epoxy group is dissolved in an aqueous vehicle containing a partially sulfonated polyester resin. However, when a dye is used as a pigment component, even when a resin exhibiting excellent water resistance after curing is used in combination, the dye itself is re-dissolved in water from a dry writing portion, and color bleeding occurs. Is inevitable.

Further, an aqueous ink composition using a pigment as a coloring matter component is also known (JP-A-58-80368). However, in the writing portion obtained with this ink composition, the acrylate-based resin, maleate-based resin, and the like compounded as a dispersibility stabilizer are easily reconstituted in water in the presence of an alkaline detergent. As it dissolves, the water resistance is still insufficient.

Means for Solving the Problems The present inventor has repeated studies in view of the current state of the art as described above, and when using a specific resin and pigment in combination, water resistance after writing and drying. And an aqueous ink composition having excellent washing resistance was obtained.

That is, the present invention provides the following aqueous ink composition: (a) a resin component comprising a polyurethane having a molecular weight of 100,000 or more or a mixture of a polyurethane having a molecular weight of 100,000 or more and a polyester having a molecular weight of 5,000 to 30,000; (B) 2 to 30% by weight of a solvent-insoluble pigment component, (c) 50 to 95% by weight of a solvent component comprising water or a mixture of water and a water-soluble organic solvent, and (d) a dispersion aid. An aqueous ink composition for writing, characterized by comprising 0.01 to 30% by weight of an agent.

In the following, “%” means “% by weight” in all cases. In this specification, "writing" means to apply the ink composition to the surface of any object or material.

The resin component in the present invention is water-soluble or water-dispersible, forms a coating film exhibiting a high degree of water resistance under alkaline and acidic conditions after writing and drying of the ink, and is subjected to severe water and washing. It is necessary to be able to prevent the color bleeding of the writing portion even under an unusual contact condition. In the present invention, polyurethane or a mixed resin of polyurethane and polyester is used as such a resin component. The polyurethane is not particularly limited, but contains an aliphatic polyester or an aromatic polyester in the molecule and has a molecular weight of 10
Those having an acid value of not less than 10,000 and an acid value of not more than 40 are preferred. Polyester is also not particularly limited, but has sodium sulfonate, hydroxyl group, and the like in the main chain, and has a molecular weight of 5,000 to 30.
Those having an acid value of about 000 and an acid value of about 10 or less are preferred. When using a mixed resin of polyurethane and polyester,
The latter ratio is up to about 80%, more preferably up to about 50% of the weight of the mixed resin. If the percentage of polyester is more than 80%, the reason is unknown, but when stored in a writing instrument, the preservability deteriorates, and over time, clogging, blemishes, and other phenomena tend to occur. There is. The proportion of the resin component in the ink composition depends on the type of pigment,
Depends on the type of solvent, type of dispersion aid, etc.
It is about 0.1 to 50%, more preferably about 1 to 20%. When the amount of the resin component is excessive, the viscosity of the composition is excessively increased and the writability is reduced, whereas when the amount is too small,
Adhesion to the writing surface is reduced, and high water resistance or washing resistance is insufficient.

As the dye component in the present invention, a dye component that is stable, has excellent coloring properties, and is insoluble in a solvent component is used. Examples of such a dye component include the following.

Inorganic pigments: carbon block, titanium oxide, etc. Organic pigments: azo, phthalocyanine, quinacridone, anthraquinone, dioxane, indigo, thioindigo, perylene, perinone, isoindolenone, azomethine, etc. Synthetic resin pigments: addition polymers of monomers such as styrene, melamine, acrylic, benzoguanamine, epoxy, and vinyl chloride.

The proportion of the pigment component in the ink composition varies depending on the type of the pigment itself, the type of the resin, the type of the solvent, the type of the dispersing agent, and the like, but is usually about 2 to 30%, and more preferably about 4 to 20%. . If the amount of the dye component is too large, the viscosity becomes high and the writability decreases, whereas if the amount is too small, the coloring becomes insufficient.

As the solvent component in the present invention, one that dissolves or disperses other components favorably to form a composition having excellent fluidity and that easily volatilizes after writing is used.
Examples of such a solvent component include water or a mixture of water and a water-soluble or water-miscible organic solvent. The following are examples of the water-soluble or water-miscible organic solvent.

Alcohols: Methanol, ethanol, isopropanol (IPA), butanol, etc. Ethylene glycol monoethers: Ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol isopropyl ether, ethylene glycol butyl ether, ethylene glycol isobutyl ether, propylene glycol monoether Classes: alkyl (methyl, ethyl, isopropyl, butyl, isobutyl, etc.) substituted ethers such as propylene glycol, diethylene glycol, dipropylene glycol, etc.

When a mixture of water and an organic solvent is used as the solvent component, the ratio of the latter is up to about 60%, more preferably up to about 30% of the weight of the mixture. 60% of organic solvent
When the ratio exceeds the above range, precipitation and reduction in dispersibility of the water-soluble resin which may be used as a pigment dispersant or a binder component may be caused.

The solvent component in the ink composition mainly defines the drying rate of the ink composition, and its ratio varies depending on the type of resin, the type of pigment, the type of solvent itself, the type of dispersion aid, and the like. , Usually 50-95%, more preferably 75-90
%. If the amount of the solvent component is too large, the viscosity will be too low and the color will be insufficient,
If the amount is too small, the viscosity increases and the writability decreases.

As the dispersing aid in the present invention, an acrylic resin conventionally used as a dispersant in an aqueous dispersion,
Maleic acid resin, styrene-acrylic resin, styrene-
Synthetic and natural water-soluble resins such as maleic acid resin, polyvinyl alcohol and cellulose: anionic, cationic, nonionic and amphoteric surfactants and the like. The solvent component in the ink composition is used mainly for improving the dispersibility of the pigment, and the ratio is appropriately determined depending on the type and amount of the pigment, but is usually 0.01%.
It is about 30%, more preferably about 0.1 to 15%. If the amount of the dispersing aid is too large, the water resistance and washing resistance are significantly reduced, and the adhesion to the writing surface is also insufficient. Causes clogging. When a water-soluble resin is used as the dispersing aid, the water resistance may decrease due to the relative quantitative relationship with the resin component of the present invention. Therefore, the amount of the dispersing aid is desirably within a range not exceeding about 70% of the amount of the resin component.

Known additives can be appropriately added to the ink composition of the present invention, if necessary. Examples of such additives include:-pH adjusters such as ammonia, triethylamine, methyldiethanolamine, and triethanolamine:-Leveling and slip property improvers such as silicones and fatty acid derivatives:-Ethylene glycol and its dimer to trimer And propylene glycol and dimer or trimer thereof such as fatty acid esters and succinate derivatives, and wetting agents and coating improvers such as fatty acid esters and succinate derivatives.

The ink composition of the present invention can be manufactured by any method, and does not need to be manufactured by a specific manufacturing method. An example is as follows. First, a resin component is dissolved or dispersed in a solvent component with stirring while heating, and then a dispersant and other additives as necessary are added, followed by further stirring. Next, a pigment previously dispersed uniformly is added,
After further stirring and mixing, if necessary, the mixture is filtered,
Obtain the desired ink composition.

The ink composition of the present invention is housed in a writing instrument having a known structure, and can be used as a writing material for fibers, paper, glass, metal, plastic, wood, and the like.

Effect of the Invention The ink composition according to the present invention is quick-drying, has good pigment dispersibility (storage stability), has good adhesion to a writing surface after drying, and has excellent water resistance, washing resistance, color development, and the like. Are better.

EXAMPLES Examples are shown below to further clarify features of the present invention.

Examples 1 to 6 and Comparative Examples 1 to 3 The components were uniformly mixed at the ratios (as solid contents) shown in Table 1 to obtain ink compositions.

 In addition, each symbol in Table 1 shows the following materials.

Pigment I: CI Pigment Black 7 Pigment II: CI Pigment Red 57 Pigment III: CI Pigment Blue 15 Resin I: Water-soluble polyurethane dispersion, trademark "NEOREZ R-"
960 ", Resin II: Water-soluble polyester dispersion, manufactured by ICI of the United Kingdom, trademark" WNT "Resin III: Styrene-maleic acid copolymer, manufactured by Eastman Kodak Company, USA; Trademark:" HIROS X-205 ", Seiko Chemical Co., Ltd. Aqueous solution with a solid content of 30% with 28% aqueous ammonia 1.3 times the equivalent (acid value 205) Resin IV: Acrylic resin dispersion, trademark “Watersol”
S-744 ", manufactured by Dainippon Ink and Chemicals, Inc. Resin V: acrylic resin emulsion, trademark" JONCRYL J
-450 ", manufactured by Johnson, USA Additive: Propylene glycol: sodium salt of polyoxyethylene (3) dodecyl ether acetate = 2:
1 (weight ratio) mixture water ... ion exchange water Next, the obtained ink composition was filled into a marking pen (a member for white plate marker “WBK-M” manufactured by Sakura Crepas Co., Ltd., ink filling amount: 7 g), and stored for 1 month in an upright and inverted state. After that, writing was performed on blank paper, and the difference in shading between writing with an upright pen and writing with an inverted pen was visually observed to determine storage stability.

In addition, using the ink composition obtained, after writing the alphabet (A) on the fiber, various detergent solutions (concentration 0.2%)
Using a washing machine for 15 minutes of washing 5 times,
After drying, the handwriting density before and after washing was compared to determine the washing resistance. However, in the case of the solid soap for washing, the soap was sufficiently applied and rubbed and washed 20 times.

 Table 2 shows the results.

In addition, each symbol in Table 2 shows the following materials and matters.

Detergent I ... Sodium linear alkyl bezensulfonate-based neutral detergent Detergent II ... Sodium fatty acid-based laundry powder soap Detergent III ... Laundry solid soap Storage stability A: No difference in shading.

…: Little or no difference in shading.

Washing resistance A: No difference at all.

 …: There is almost no difference.

 ×: Discolored and unreadable.

In addition, using a marking pen manufactured in the same manner as above, writability, which is an important property as a writing instrument, adhesion to fibers and cap-off property were examined, and it was found that all of them were satisfactory for practical use. found.

Claims (1)

(57) [Claims] 1. A resin component comprising: (a) a polyurethane component having a molecular weight of 100,000 or more or a mixture of a polyurethane having a molecular weight of 100,000 or more and a polyester having a molecular weight of 5,000 to 30,000; and (b) a solvent-insoluble pigment component. 2 to 30% by weight, (c) 50 to 95% by weight of a solvent component comprising water or a mixture of water and a water-soluble organic solvent, and (d) 0.01 to 30% by weight of a dispersing aid. Water-based ink composition.