JP2002173616A - Water-based ink composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-based ink composition highly resistant to drying and excellent in suppressing a relatively large-sized crystal deposition at a penpoint. SOLUTION: This water-based ink composition is characterized by comprising a colorant, water and 1,6-hexanediol.

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 having excellent drying resistance and low crystallization of ink components, which can be used for writing implements, stamps, recorders, printers, printing and the like. Be quiet.

[0002]

2. Description of the Related Art Conventional writing instruments using water-based ink have a drawer in which the cap is removed from the writing instrument body and the pen tip is exposed to the atmosphere for a long period of time. In some cases, it became impossible. In order to obtain a water-based ink having excellent drying resistance, there has been known an ink obtained by adding a water-soluble organic solvent such as ethylene glycol or urea as an evaporation inhibitor. However, when such additives are used, satisfactory performance improvement is not recognized unless a large amount is added to the ink. In such a case, problems such as difficulty in flowing out due to an increase in the viscosity of the ink, fading of the drawing line, and a marked decrease in the sticking of the drawing line on the non-absorbing surface after writing due to the difficulty in drying the ink become remarkable. is there.

[0003] When a water-soluble organic solvent such as ethylene glycol is added, the surface tension of the ink is reduced, and the tangent lines are easily blurred. Furthermore, when urea is added, urea is decomposed when the ink is stored at a high temperature, and there is a problem in its stability. When such additives are added to the ink composition in order to improve the drying resistance as described above, the ink may have a behavior of deteriorating the writing performance, and such improvement measures have conventionally been desired. .

As a means for suppressing such a decrease or change in ink performance and obtaining an ink having excellent drying resistance, para-xylylene glycol or the like is added as disclosed in JP-A-09-012957, and immediately upon cap-off, Attempts have also been made to precipitate crystals to ensure the fluidity of the ink in the pen core. In this case, a very excellent effect on the drying resistance is recognized, but conversely, large crystals are easily deposited on the pen tip and the appearance is bad, and the deposited crystals block the ink flow path and the like, and writing is impossible. Easy to be.

[0005]

Under such circumstances, the present invention suppresses a decrease or change in the writing performance of ink such as blurring and blurring of drawing lines, and at the same time, has excellent drying resistance and a large crystal at the pen tip. It is an object of the present invention to provide an aqueous ink composition which is excellent in suppressing precipitation of water.

[0006]

The present inventors have conducted various studies to solve the above-mentioned problems, and as a result, 1,6-hexanediol has a good writing performance and an excellent effect as a desiccant. Thus, the present invention has been completed.
That is, the present invention is an aqueous ink composition comprising a colorant, water and 1,6-hexanediol.

[0007]

Embodiments of the present invention will be described below in detail. 1,6-hexanediol, which is a gist of the present invention, is used as a desiccant-resistant agent, and does not cause a decrease in the writing performance of the ink even when incorporated in an aqueous ink composition. The amount used is from 0.01% by mass to 15.0% by mass, more preferably from 5.0% by mass to 10.0% by mass, based on the total amount of the aqueous ink composition. If the amount is less than 0.01% by mass, the desired good drying resistance cannot be obtained, and if it exceeds 15.0% by mass, the temporal stability of the ink will be affected, and the sedimentation and clogging of the pigment will occur. And the like, the stability of the ink is deteriorated, which is not preferable. The content of water as a solvent used in the present invention is from 30 to 90% by mass, more preferably from 45 to 8% by mass, based on the total amount of the aqueous ink composition.
5% by mass.

As the colorant used in the present invention, any dyes and pigments conventionally used in aqueous inks can be used without any limitation. Examples of the dye include direct dyes such as Aizen Burimura Red 4BH and Aizen Burimura Yellow GCLH (all manufactured by Aizen Co., Ltd.), Aizen Bonsaw RH, Aizen Opal Pink B
H, acid dyes such as Eizen Opal Black WH Extra Conc (manufactured by Eizen Co., Ltd.), Orient Soluble Blue OBX, and Orient Solble Blue OBB (manufactured by Orient Chemical Co., Ltd.), tartrazine, acid red, and phloxine Food dyes (eg, manufactured by Eizen Co., Ltd.). These dyes can be used alone or in combination with other two or more kinds, and the content thereof is 0.01 to 0.01 in the total amount of the aqueous ink composition.
It is 40.0% by mass, more preferably 0.10 to 5.00% by mass.

As the pigment, inorganic pigments such as carbon black, titanium oxide and iron oxide, phthalocyanine pigments,
Examples thereof include organic pigments such as azo pigments, inorganic fluorescent pigments such as calcium sulfide, and other organic fluorescent pigments.
When a pigment is used as a colorant, it is desirable to use a dispersant at the same time. These pigments can be used alone or in combination with other two or more kinds, and the content thereof is 5.0 to 30.0% by mass, more preferably 5.0 to 20.0% by mass in the total amount of the aqueous ink composition. %.

When the above pigment is used as a colorant, it is desirable to use a dispersant at the same time. Examples of the dispersant include, for example, Joncryl J-62, Joncryl J-450 (manufactured by Johnson), Jolimar AT-210, Jolimar SE, which are generally used for aqueous inks.
Water-soluble resins such as K-101 (manufactured by Nippon Pure Chemical Industries, Ltd.), anionic activators, nonionic activators, and the like can be used without limitation. The content of these dispersants is 0.5 to 30.0% by mass, more preferably 1.0 to 15.0% by mass, based on the total amount of the aqueous ink composition.

In addition to the above main components, sodium benzoate (manufactured by Wako Pure Chemical Industries, Ltd.), Bioden-18, Amorden-HS, Amorden-HS, Amorden BT-
50, Amorden FS-14D (manufactured by Daiwa Chemical Industry Co., Ltd.), Proxel BDN, Proxel GXL, Proxel TN (manufactured by Zeneca Corporation), and a small amount of a bactericidal agent can be added. Aminomethylpropanol and triethanolamine (above,
Wako Pure Chemical Industries, Ltd.) can be added. Further, for the tip at the tip of the ballpoint pen, an anticorrosive, a lubricant or the like can be used as needed.

The aqueous ink composition of the present invention can be produced by the following method. In the case of an ink using a dye as a coloring material, the ink can be easily obtained by mixing and dissolving the above components. In the case of an ink in which a pigment alone or a pigment and a dye are used in combination as a coloring material, the above components are stirred and mixed by a known dispersing machine such as a ball mill, a roll mill, a sand mill, a flow mill, a Dyno mill, an attritor, and the like, and pulverized. The desired aqueous ink composition can be easily obtained by removing coarse particles and dust from the intermediate obtained by stirring, mixing, or mixing and pulverization by a method such as filtration or centrifugal sedimentation, if necessary.

[0013]

The reason why the aqueous ink composition of the present invention is excellent in drying resistance is presumed as follows. 1,6-hexanediol dissolved in the aqueous ink composition easily precipitates as a crystal at the pen tip. It is thought that this crystal plays a role of a lid in the pen tip opening and suppresses evaporation and drying of water from the ink at the pen tip. When para-xylylene glycol is used instead of 1,6-hexanediol, the evaporation and drying of water are similarly suppressed, but at the same time, the precipitation of crystals is too intense and a huge precipitate is formed on the pen tip. There was a defect that appeared,
No such precipitate is seen when 1,6-hexanediol is used. It is assumed that 1,6-hexanediol has a large power of dissolving in water, and therefore, there is no precipitation of a huge crystal at the pen tip.

[0014]

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

Example 1 69.70 parts by mass of water Carbon black MA-100 (manufactured by Mitsubishi Chemical Corporation) 15.00 parts by mass Joncryl 62 10.00 parts by mass Aminomethylpropanol 0.10 parts by mass Bioden-18 20 parts by mass 1,6-hexanediol 5.00 parts by mass The above components were mixed and pulverized, and then filtered to obtain a black ink.

Example 2 65.51 parts by weight of water Emacol. Blue. FB (manufactured by Sanyo Pigment Co., Ltd.) 18.00 parts by mass Joncryl J450 11.13 parts by mass 0.13 parts by mass of triethanolamine 0.23 parts by mass of Proxel BDN 5.00 parts by mass of 1,6-hexanediol The components were mixed and pulverized, and then filtered to obtain a blue ink.

Example 3 54.67 parts by mass of water Fuji. SP. Red. 5111 (manufactured by Fuji Dye Co., Ltd.) 18.00 parts by mass Jolimer AT210 12.00 parts by mass Propylene glycol 10.00 parts by mass Aminomethylpropanol 0.13 parts by mass Amorden-HS 0.20 parts by mass 1,6-hexanediol 5.00 parts by mass The above components were mixed and pulverized, and then filtered to obtain a red ink.

Example 4 Water 57.77 parts by mass Eisen Burimura Red 4BH 3.77 parts by mass Eisen Mura Ero GCLH 0.23 parts by mass Propylene glycol 30.00 parts by mass Triethanolamine 0.01 parts by mass Sodium benzoate 1.22 parts by mass 1,6-hexanediol 7.00 parts by mass The above components were mixed and pulverized, and then filtered to obtain a red ink.

Comparative Examples 1 to 8 Instead of hexanediol of Examples 1 to 4, two components of paraxylylene glycol and water (3.00 parts by weight of the former and the rest of the latter) were used (Comparative Examples 1 to 4). Examples 1 to 4 except that water was used or only water was used (Comparative Examples 5 to 8).
Ink was obtained in the same manner as described above.

Test Examples Each of the ink compositions obtained in Examples 1 to 4 and Comparative Examples 1 to 8 was applied to a commercially available aqueous pen for fine writing (Mitsubishi PIN-10).
3: Made by Mitsubishi Pencil Co., Ltd.), left the cap in the air after removing the cap, and wrote it by hand at regular intervals, and measured the elapsed time until it was blurred and could not be drawn. Table 1 shows the rewriting performance results (elapsed time) after each cap-off.
Shown in Further, after the above test is completed, the samples of Examples 1 to 4 and Comparative Examples 1 to 4 were aged at 0 ° C. for one month or more, and the states of the respective nibs were observed. Table 2 shows the results of crystal precipitation (level of crystal precipitation).

[0021]

[Table 1]

[0022]

[Table 2]

From the results shown in Table 1, in Comparative Examples 5 to 8, the writable standing time was 5 minutes or less, which was poor in drying resistance. In Examples 1 to 4, the writable standing time was extended to 60 minutes or more, and it was recognized that the drying resistance was excellent. On the other hand, from the results of Table 2, the results of observing the state of the deposition of the pen tip by aging at 0 ° C. for 1 month or more show that in Comparative Examples 1 to 4 using paraxylylene glycol, the generation of the precipitate was In comparison with the remarkable examples, in Examples 1 to 4 using 1,6-hexanediol, almost no generation of precipitate was observed.

[0024]

According to the present invention, 1,6-hexanediol dissolved in the aqueous ink composition of the present invention easily precipitates as a crystal at the pen tip, and the crystal is deposited on the lid at the opening of the pen tip. It seems to play a role and suppress evaporation and drying of water from the ink at the pen tip. In addition, 1,6-hexanediol has a higher dissolving power in water than known para-xylylene glycol, and does not cause precipitation of a huge crystal on a pen tip. As described above, the water-based ink of the present invention is excellent in drying resistance at the pen tip of a writing implement, has a small amount of deposits at the pen tip, and has an effect of exhibiting good writing performance.

Continuation of the front page (72) Inventor Hide Nagami 1091 Tateishi, Fujioka-shi, Gunma F-term in Gunma R & D Center, Mitsubishi Pencil Co., Ltd. (Reference) 4J039 BA04 BA13 BA18 BA30 BA35 BA37 BC09 BC39 BC60 BE01 BE02 BE03 BE04 BE22 CA03 CA06 EA11 EA28 EA41 EA47 GA07

Claims (1)

[Claims] 1. An aqueous ink composition comprising a colorant, water and 1,6-hexanediol.