JP3108541B2 - Aqueous ink composition for writing utensils - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous ink composition for a writing instrument. More specifically, the present invention relates to a water-based ink composition for a writing implement that can be suitably used for, for example, a marking pen, a mechanical writing implement, a ballpoint pen, and the like.

[0002]

2. Description of the Related Art Conventionally, marking pens, ball pens, and the like used for recording and writing on documents and the like are generally added with, for example, polyhydric alcohol, formamide, glycerin, urea, etc. in order to prevent the nib from drying. An ink containing an agent is used.

However, when such an additive is used, it is possible to prevent the pen tip from drying, but depending on the paper quality of the document, ink bleeding or penetration may occur, or the paper quality of the paper may be reduced. This causes a difference in the density of the coloration, resulting in not only a non-sharp drawing line having an uneven density with uneven drawing lines, but also a problem that drying of the formed writing lines is significantly slowed down.

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the inventors of the present invention have made it possible to prevent the pen tip from drying and eliminate the occurrence of a color density difference due to a difference in paper quality. As a result of extensive studies to obtain a water-based ink composition capable of forming sharp lines without blurring of drawn lines, surprisingly, when a specific resin emulsion and a specific sugar are used in combination, The present inventors have found that an aqueous ink composition having the above physical properties can be obtained, and have completed the present invention.

[0005]

That is, the present invention relates to an aqueous ink composition containing a pigment, a resin, sugar and water, wherein the resin is an acrylic resin having a minimum film-forming temperature of 40 ° C. or higher. A writing implement, wherein the saccharide is a sucrose and / or maltitol-based saccharide, and a water-soluble resin is blended as a binder. The present invention relates to an aqueous ink composition for use.

[0006]

Action and Examples As described above, the aqueous ink composition for a writing instrument of the present invention contains a pigment, a resin, sugar and water, and the resin has a minimum film-forming temperature of 40 ° C. or higher. An oil-in-water emulsion of an acrylic resin or a styrene-acrylic resin, wherein the sugar is sucrose and / or
Alternatively, it is a sugar containing maltitol as a main component, and is characterized in that a water-soluble resin is blended as a binder.

Examples of the pigment include various organic pigments and inorganic pigments, and the kind of the pigment is not particularly limited.

The organic pigments include, for example, monoazo pigments derived from allylic acetoacetate derivatives and β-naphthol derivatives, lake pigments obtained by laking monoazo dyes such as β-oxynaphthoic acid dyes, disazo pigments, condensed disazo pigments, and the like. Lake pigments such as isoindoline derivatives, derivatives of naphthalene or perylene tetracarboxylic acid, anthraquinone pigments, thioindigo derivatives, azomethine derivatives, quinacridone, dioxazine, pyrazoloquinazolone, phthalocyanine pigments, lake pigments obtained by lacquering basic dyes such as triarylmethane dyes, etc. Specific examples of such organic pigments include, for example, Pigment Yellow 1 (CI 11680), Pigment Yellow 3 (CI 11710), and Pigment Yellow 42 (CI 7
7492), Pigment Yellow 74 (CI 11741), Pigment Yellow 83 (CI 21108), Pigment Yellow 106, Pigment Yellow 108 (CI 68240),
Pigment Yellow 117, Pigment Yellow 126
, Pigment Yellow 139, Pigment Yellow 1
85, Pigment Orange 5 (CI 12075), Pigment Orange 67, Pigment Red 3 (CI 1212
0), Pigment Red 48: 1 (CI 15865: 1),
Pigment Red 48: 4 (CI 15865: 4), Pigment Red 101 (CI 77491), Pigment Red
112 (CI 12370), Pigment Red 123 (CI 7
1145), Pigment Red 169 (CI 45160: 2),
Pigment Violet 23 (CI 51319), Pigment Violet 27 (CI 42555: 3), Pigment Violet
Blue 1 (CI 42595: 2), Pigment Blue 15:
1 (CI 74160), Pigment Blue 15: 3 (CI 7
4160), Pigment Blue 61 (CI 42765: 1), Pigment Green 7 (CI 74260), and Pigment Green 36 (CI 74265). Among these organic pigments, Pigment Red 112, Pigment Violet 23, Pigment Blue 15: 1, Pigment Blue 15: 3, and Pigment Green 7 are preferred.

Representative examples of the inorganic pigment include iron oxide, iron ferricyanide, sodium aluminum silicate containing sulfur, titanium dioxide, and carbon black. Specific examples of such inorganic pigments include, for example, Pigment Yellow 42 (CI77492), Pigment White 6 (CI 77891), Pigment Blue 27 (CI
77510), Pigment Blue 29 (CI 77007), and Pigment Black 7 (CI 77266).

The average particle size of the pigment is usually 0.01 to several tens.
μm, preferably 0.05-1 μm, more preferably 0.05
When the average particle diameter is in this range, the particles can be uniformly dispersed in the ink composition without aggregation. In addition, as a method of adjusting the average particle diameter of the pigment to the above range, for example, after finely pulverizing the pigment using a known mixing mill such as a bead mill, roll mill, agitator mill, centrifugal separation or filter filtration. There is a method of removing coarse particles by a method. In the present invention, a pigment dispersion having an average particle diameter already adjusted to the above range may be used.

The pigments are usually used alone or as a mixture of two or more kinds. The amount of such pigments is 1 to 15% by weight, preferably 3 to 10% by weight, in the aqueous ink composition.
It is preferable to be adjusted so as to be contained. When the amount of such a pigment is less than the above range, the coloring property becomes poor, and when the amount exceeds the above range,
The viscosity tends to increase and the stability of the resulting aqueous ink composition tends to decrease.

The present invention has one significant feature in that an acrylic resin or a styrene-acrylic resin oil-in-water emulsion having a minimum film forming temperature of 40 ° C. or higher is used as the resin.

When the minimum film forming temperature of the resin is lower than 40 ° C., the drawing lines formed by the obtained water-based ink composition are blurred or a density difference occurs depending on the type of paper. When the pen tip is dry,
Rewriting is not possible. The minimum film forming temperature of the resin is preferably 50 ° C. or higher.

The oil-in-water emulsion is prepared by, for example, mixing (meth) acrylic acid ester or a mixture of styrene and (meth) acrylic acid ester, and, if necessary, (meth) acrylic acid, a surfactant and water. Formed by Here, the oil-in-water emulsion means that the dispersed phase is oil (a mixture of (meth) acrylic acid ester or styrene and (meth) acrylic acid ester, if necessary, (meth) acrylic acid, and a surfactant), When the phase is water. In the process of forming an oil-in-water emulsion, the mixing ratio of (meth) acrylic acid ester or a mixture of styrene and (meth) acrylic acid ester, and if necessary, (meth) acrylic acid and surfactant is usually 10% by weight. : 0.1 to 5: 1. When the amount of the surfactant used is less than the above range, it is difficult to obtain an emulsion, and when the amount exceeds the above range, the water resistance of the obtained aqueous ink composition is reduced, There is a tendency for sex to become worse.

The mixing ratio of the component for the disperse phase and water should be determined carefully because it has a significant effect on the formation of an oil-in-water emulsion. Parts to 60 parts by weight of water
It is preferable to adjust the amount to 400 parts, especially 100 to 200 parts. When the proportion of water exceeds the above range, the solid content concentration of the obtained oil-in-water emulsion tends to decrease and the practicality tends to decrease. An oil-in-water emulsion having suitable properties, such as being too large, tends to be difficult to obtain.

The type of the surfactant is not particularly limited. Specific examples of such surfactants include anionic surfactants such as sodium dodecylbenzenesulfonate, sodium lauryl sulfate, and ammonium salts of polyoxyethylene alkyl ether sulfate; polyoxyethylene alkyl ethers, polyoxyethylene alkyl esters; Nonionic surfactants such as polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylphenyl ether, polyoxyethylene alkylamine, polyoxyethylene alkylamide, and acetylated products thereof, and the like, alone or in combination of two or more Are used as a mixture.

The oil-in-water emulsion can be produced by a known method such as an emulsion polymerization method using a general stirrer such as a low-shearing stirrer or a pipeline mixer.

In the present invention, an oil-in-water emulsion of an acrylic resin or a styrene-acrylic resin having a minimum film-forming temperature of 40 ° C. or higher is used as the resin. Preferably, the composition is adjusted so that the resin solids content is 0.5 to 25% by weight, preferably 1 to 5% by weight. When the amount of the resin solids exceeds the above range, the storage stability of the obtained aqueous ink composition is reduced, and when the amount is less than the above range, the bleeding is improved or the color difference due to paper is reduced. Tends to be insufficient in eliminating the effect.

In the present invention, since an acrylic resin or a styrene-acrylic resin oil-in-water emulsion having a minimum film-forming temperature of 40 ° C. or higher is used as the resin as described above, the occurrence or generation of bleeding due to a difference in paper quality is achieved. Color differences can be eliminated.

Further, since the oil-in-water emulsion is used in combination with a sugar containing sucrose and / or maltitol as a main component, the difference in color density based on the difference in paper quality due to the oil-in-water emulsion ( While the effect of reducing the color difference is exhibited, drying of the pen tip and the like is prevented.

In the present invention, a sucrose and / or maltitol-based saccharide is used as the saccharide. When the sucrose and / or maltitol content of the saccharide is too small, Since the drying resistance of the obtained water-based ink composition tends to be insufficient, it is preferably at least 50% by weight, particularly preferably at least 60% by weight.

As the saccharide, for example, maltose, sorbit, maltotriitol, oligosaccharide and the like can be used in addition to sucrose and maltitol.

The amount of the sugar is preferably adjusted so that the aqueous ink composition contains 3 to 30% by weight, preferably 5 to 20% by weight. When the amount of the sugar is less than the above range, the drying resistance with a pen tip or the like is reduced, and when the amount exceeds the above range, the viscosity of the obtained aqueous ink composition is reduced. They tend to be too high and unsuitable for writing instruments.

In the present invention, a water-soluble resin is used as a binder.

When the water-soluble resin is used together with the sugar, the water-soluble resin is re-dissolved by the aqueous ink composition that follows even under conditions in which the pen tip and the like are dry, and the formation of a film or the like is prevented at room temperature. Has the property of blocking.

As the water-soluble resin, those soluble in an aqueous solution in which an amine or other base is dissolved are preferable from the viewpoint of the water resistance and friction resistance of the formed writing line.

Representative examples of the water-soluble resin include, for example, acrylic resins. Specific examples of such acrylic resins include, for example, styrene-acrylic acid copolymers and acrylic acid-acrylic acid alkyl ester copolymers. Copolymer, styrene-acrylic acid-alkyl acrylate copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-alkyl acrylate copolymer, styrene-α-methylstyrene-acrylic acid copolymer, styrene -Α-methylstyrene-acrylic acid-alkyl acrylate copolymers and salts thereof.

If the weight-average molecular weight of the water-soluble resin is too large, the viscosity of the resulting aqueous ink composition tends to be high, making it unsuitable for writing. If it is too small, Since a film tends to be hardly formed when drawing a line, it is preferably 3,000 to 30,000, particularly preferably 5,000 to 15,000.

The amount of the water-soluble resin is set at room temperature or lower, preferably at room temperature or lower, in order to form a film in the atmosphere in which the aqueous ink composition is usually used. The temperature is adjusted to 30 ° C. or lower, more preferably 25 ° C. or lower, particularly preferably 0 ° C. or lower. As described above, the amount of the water-soluble resin capable of imparting a film-forming temperature of preferably 30 ° C. or lower, more preferably 25 ° C. or lower, and particularly preferably 0 ° C. or lower to the obtained aqueous ink composition, Since it depends on the type of resin, it cannot be unconditionally determined. However, it is preferably 0.5 parts or more, more preferably 3 parts or more, based on 100 parts of the total amount of the resin and the solid content of the resin usually contained in the oil-in-water emulsion. It is particularly preferably about 10 parts or more. When the amount of the water-soluble resin is too large, the effect of lowering the film-forming temperature of the obtained aqueous ink composition is not so much improved, and the viscosity of the obtained aqueous ink composition is extremely low. It is desirable that the amount be 200 parts or less, especially 100 parts or less, because the amount will be improved.

The water-soluble resin may be used after being dissolved in water in advance, or may be used by being blended with a pigment, an oil-in-water emulsion, sugar and water.

When dissolving the water-soluble resin in water, for example, 2-aminoisobutanol, triethanolamine, morpholine, aqueous ammonia, propylene glycol, isopropanol, or the like may be used as an auxiliary.

In the present invention, a water-soluble resin is used as a binder, and when such a water-soluble resin serves as a dispersant, it is not necessary to add another resin.

The balance of the aqueous ink composition of the present invention is mainly water, and the amount of water may be adjusted so that the pigment, resin and sugar are contained at predetermined concentrations.

The aqueous ink composition of the present invention can be obtained by mixing the pigment, oil-in-water emulsion, sugar, water-soluble resin and water, and the aqueous ink composition contains, for example, aggregates. In some cases, clogging may occur at the pen tip or the like. Therefore, it is desirable to remove the particles by filtration using, for example, a centrifuge or a filter.

In the present invention, a moisturizing / slow-drying component such as urea, various glycols, glycerin and alkanolamines may be added to the aqueous ink composition as long as the object of the present invention is not impaired. it can.

Next, the aqueous ink composition for a writing instrument of the present invention will be described in more detail with reference to Examples, but the present invention is not limited to only these Examples.

Example 1 and Comparative Examples 1-2 Carbon black dispersion as pigment (Mikuni Color Co., Ltd.)
HI-Micron K Black # 7360, carbon black content: about 15% by weight, styrene-acrylic acid copolymer (weight average molecular weight: about 10,000) as a water-soluble resin, about 3% by weight, carbon black Average particle size: 0.1 μ
m), maltitol as sugar, oil-in-water emulsion of styrene-acrylic resin as oil-in-water emulsion (manufactured by Zeon Corporation, SAE1014, resin solid content: 40% by weight, minimum film-forming temperature: 80 ° C) and water Was mixed in the mixing ratio shown in Table 1 and dispersed using an agitator mill to obtain an aqueous ink composition.

The film forming temperature of the obtained aqueous ink composition was examined according to the following method. Table 1 shows the results.

(Film forming temperature of water-based ink composition) About 23 g / m ^{2 of the} obtained water-based ink composition was placed on a glass plate.
The temperature at which the film forms when dried is determined.

Next, the obtained aqueous ink composition was filled into a plastic felt-tip pen (tip diameter: 0.3 mm),
(A) OD (optical density) value of written lines, (b) blur of written lines, (c) drying resistance and (d) abrasion resistance, and (e) storage stability using aqueous ink composition. The properties were examined according to the following methods. The results are also shown in Table 1.

(A) OD value of handwritten line The handwritten line is drawn on PPC paper, postcard, stationery and report paper using a plastic felt-tip pen, and the OD value is obtained using a Macbeth densitometer RD-918 (manufactured by Sakata Inx Corporation). Ask.

(B) Bleeding of written lines The degree of bleeding of the drawn lines drawn in (a) is visually observed and evaluated according to the following evaluation criteria.

(Evaluation Criteria) A: No bleeding is observed on any of PPC paper, postcard, stationery and report paper.

B: Bleeding is observed on any of PPC paper, postcard, stationery and report paper.

C: Bleeding is observed on any of PPC paper, postcard, stationery and report paper.

(C) Drying resistance The cap of the plastic felt-tip pen is removed, and the time until writing becomes impossible is measured.

(D) Abrasion resistance A drawing line is formed on art paper (coating paper) and report paper using a plastic felt-tip pen, left at room temperature, completely dried, and rubbed on the drawing line with dry paper. ,
The peeling of the drawn line is examined and evaluated according to the following evaluation criteria.

(Evaluation Criteria) A: There is no change in either art paper or report paper.

B: Slight peeling was observed on art paper, and there was almost no change on report paper.

C: Slight peeling is observed on art paper, but dirt spreads around on report paper.

D: Peeling is completely recognized on art paper, and dirt spreads around on report paper.

(E) Storage stability The aqueous ink composition was placed in a glass test tube, sealed, and then left in a constant temperature and humidity room at a temperature of 50 ° C. and a relative temperature of 65% for 3 months. The composition is checked for changes in viscosity and pH, and evaluated according to the following evaluation criteria.

(Evaluation Criteria) A: No change is observed in any of the viscosity and the pH of the aqueous ink composition.

B: A change is observed in either the viscosity or the pH of the aqueous ink composition.

C: Changes are observed in both the viscosity and the pH of the aqueous ink composition.

[0056]

[Table 1]

From the results shown in Table 1, when the oil-in-water emulsion of styrene-acrylic resin and maltitol were used in combination like the aqueous ink composition obtained in Example 1, the paper It can be seen that not only is there no difference in color development based on the difference, but also an aqueous ink composition is obtained which has almost no bleeding, and at the same time has excellent drying resistance and storage stability with a pen tip or the like.

On the other hand, when an oil-in-water emulsion of a styrene-acrylic resin was not blended (Comparative Example 1), a difference in color development based on a difference in paper was observed.
When the level of color development is low and bleeding occurs, and when sugar (maltitol) is not used (Comparative Example 2),
It can be seen that the drought resistance is extremely poor.

Example 2 and Comparative Example 3 Dispersion of phthalocyanine blue as a pigment (HI. Micron K Blue # 6227, manufactured by Mikuni Dye Co., Ltd., content of phthalocyanine blue: about 20% by weight, styrene-acryl as a water-soluble resin Acid copolymer (weight average molecular weight: about 10,000)
About 4% by weight, average particle diameter: 0.15 μm), sucrose as sugar, oil-in-water emulsion of acrylic resin as oil-in-water emulsion (manufactured by Seiden Chemical Co., Ltd., Sibinol SK-200, resin solid content: 49.5) Wt%, minimum film forming temperature:
(80 ° C. or higher) (Example 2) or an oil-in-water emulsion of an acrylic resin (manufactured by Hoechst Gosei KK, Movinyl DM-7)
58, a resin solid content: about 60% by weight, a minimum film-forming temperature: 0 ° C. or lower) (Comparative Example 3) and water in a mixing ratio shown in Table 2, and dispersed using an agitator mill to disperse the aqueous ink composition I got

The physical properties of the obtained aqueous ink composition were examined in the same manner as in Example 1. The results are also shown in Table 2.

[0061]

[Table 2]

As is clear from comparison of the results of Example 2 and Comparative Example 3 shown in Table 2, as the resin component used in the oil-in-water emulsion, those having a minimum film-forming temperature lower than 40 ° C. It can be seen that when used, bleeding occurs and the drying resistance is poor.

Example 3 and Comparative Example 4 Anthraquinone Red 18 parts as a pigment and Ribonox NC-200 (trade name, manufactured by Lion Corporation) 6 as a surfactant
Part, 0.5 part of Bestside 200K (trade name, manufactured by Dainippon Ink and Chemicals, Inc.) as a preservative, 2-part as a pH adjuster
0.5 parts of aminoisobutanol and 70 parts of water were dispersed with a Dynomill, and coarse particles were removed with a centrifuge to obtain a pigment dispersion having a pigment content of 14.0% by weight.

Next, an aqueous acrylic resin (Dainippon Ink Chemical Industry Co., Ltd.) was used as the water-soluble resin in the obtained pigment dispersion liquid.
Water Sol S-745, resin solid content: 40.0% by weight), oil-in-water emulsion of acrylic resin as oil-in-water emulsion (manufactured by Seiden Chemical Co., Ltd., Sivinol SK-200, resin solids: 49.5% by weight, Minimum film formation temperature: 80
Sucrose and water as sugars in the mixing ratio shown in Table 3, dispersed using an agitator mill to obtain an aqueous ink composition, and then filtered using a membrane filter (pore size: 1.0 μm). Then, coarse particles in the liquid were removed to obtain an aqueous ink composition for a writing implement.

The obtained aqueous ink composition was examined in the same manner as in Example 1. The results are also shown in Table 3.

[0066]

[Table 3]

From the results shown in Table 3, the water-based ink composition obtained in Example 3 was firmly adhered to the drawn lines after writing, and did not peel off even when rubbed or stained around. The water-based ink composition obtained in Comparative Example 4, in which no water-soluble resin was used, showed no sticking of drawn lines after writing, peeled off on art paper leaving traces, and on report paper, It can be seen that the rubbed dirt spreads and is not suitable for a writing instrument.

[0068]

The aqueous ink composition for a writing instrument of the present invention has little change in the degree of coloration depending on the type of paper, has excellent storage stability, and has excellent drying resistance such as a pen tip. Things.

Accordingly, the aqueous ink composition for a writing instrument of the present invention can be used for a recording instrument such as a marking pen using various fiber bundles, a thin rod type or ball point type marking pen, a mechanical writing instrument, and the like. , For printing,
It can be suitably used as an aqueous ink composition for stamps and the like.

Continuation of the front page (56) References JP-A-2-214785 (JP, A) JP-A-4-76074 (JP, A) JP-A-6-212106 (JP, A) JP-B-37-18021 (JP, A) , B1) (58) Field surveyed (Int. Cl. ⁷ , DB name) C09D 11/16-11/20

Claims (3)

(57) [Claims] 1. An aqueous ink composition comprising a pigment, a resin, sugar and water, wherein said resin is an oil-in-water acrylic resin or a styrene-acrylic resin having a minimum film-forming temperature of 40 ° C. or higher. A water-based ink composition for a writing implement, wherein the saccharide is a sucrose and / or maltitol- based saccharide, and an acrylic water-soluble resin is blended as a binder. 2. The minimum film forming temperature is 30 ° C. or lower.
The aqueous ink composition for a writing instrument according to the above. 3. The water-soluble resin has a weight average molecular weight of 3,000 to 30.
The aqueous ink composition for a writing implement according to claim 1 or 2, which is an acrylic resin of 000.