JPH11279476A - Aqueous ball-point pen ink composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous ball-point pen ink capable of giving a uniform dispersion system of a pigment and a thickener and keeping viscosity stable with passing of time in an aqueous ball-point pen ink for using to a ball-point pen of a type directly supplying an ink from an ink reserving tube to a pen point tip. SOLUTION: This aqueous ball-point pen ink composition contains polyethylene glycol monostearate or polyethylene glycol distearate having 15-9.5 HLB (hydrophile-lipophile balance) in an amount of 1-10 wt.% based on a whole amount of the ink and adjusting the viscosity to 50-2,000 cps (20 deg.C) in an aqueous ball-point pen ink composition containing a pigment, water and a polar solvent. Especially, storage stability of the ink under a high temperature condition can be improved by further including a nonionic surfactant other than polyethylene glycol monostearate and polyethylene glycol distearate and having 15=19.5 HLB as a viscosity stabilizer in an amount of 0.2-5 wt.% to a whole 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 an aqueous ballpoint pen ink composition, and more particularly, to a type in which ink is supplied directly from an ink storage tube to a pen point tip without the need for batting ink or an ink guide core. The present invention relates to an aqueous ballpoint pen ink composition for use in an aqueous ballpoint pen.

[0002]

2. Description of the Related Art A conventional ballpoint pen using water-based ink absorbs 2 to 10 cps of ink into a batting ink, supplies the ink to a pen tip through an ink guide core, and transfers the ink to the paper surface by rotating the ball. Was adopted. After that, water-based ink was thickened, and ink was stored directly in the ink storage tube in the same manner as oil-based ballpoint pens, and ink was supplied directly from the ink storage tube to the pen tip. .

[0003] Examples of additives for adjusting the viscosity of water-based inks include JP-B-7-17873 and JP-B 64-64.
As described in JP 8673, polysaccharides such as xanthan gum, guar gum, locust bean gum, and cellulose derivatives have been proposed. Further, for example, JP-A-8-209055 describes that the viscosity is adjusted by a crosslinked acrylic acid polymer.

[0004]

However, in inks provided with viscosity using a polysaccharide such as xanthan gum or a synthetic polymer such as polyacrylic acid, those thickeners have an affinity for the pigment. Inferior, a uniform dispersion system cannot be obtained, lacks stability over time, and when stored for a long period of time, sedimentation of the pigment and separation and floatation of the thickener occur, clogging of the pen tip due to sedimentation of the pigment, thickener Since the amount of ink transferred to the paper surface varies due to the separation and floating of the ink, the ink composition was not always satisfactory.

Accordingly, the present invention overcomes the above-mentioned drawbacks of the water-based ballpoint pen ink, provides a uniform dispersion of the pigment and the thickener, and maintains a stable viscosity over time. The object of the present invention is to provide a ballpoint pen ink.

[0006]

That is, an aqueous ballpoint pen composition of the present invention is an aqueous ballpoint pen ink composition containing a pigment, water and a polar solvent, which is a polyethylene glycol monostearate having an HLB of 15 to 19.5. Alternatively, it is characterized in that polyethylene glycol distearate is contained in an amount of 1 to 10% by weight based on the total amount of the ink, and the viscosity is adjusted to 50 to 2000 cps (20 ° C.).

The above aqueous ballpoint pen composition has an HLB of 15 other than polyethylene glycol monostearate and polyethylene glycol distearate.
A nonionic surfactant having a viscosity of from 19.5 to 19.5 as a viscosity stabilizer in the range of 0.2 to 5% by weight based on the total weight of the ink, thereby improving the storage stability especially under high temperature conditions. Can be.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Polyethylene glycol monostearate or polyethylene glycol distearate used as a thickening agent in the present invention is:
The one having an HLB of 15 to 19.5 is used. HL
If B is less than 15, the thickening effect is lacking, and the desired viscosity cannot be imparted. As a result, when the pen is turned downward, there is a danger that the ink will blow out from the pen tip. On the other hand, if the HLB exceeds 19.5, there is a risk of breaking the uniform dispersion system, which is not preferable. The HLB of polyethylene glycol monostearate or polyethylene glycol distearate is 18 to 19.5.
Is more preferable.

The content of polyethylene glycol monostearate or polyethylene glycol distearate is in the range of 1 to 10% by weight based on the total amount of the ink. If the amount is less than 1% by weight, a uniform dispersion can be obtained but the sufficient thickening effect cannot be obtained. If the content exceeds 10% by weight, the uniform dispersion can be obtained but the viscosity becomes too high. In addition, the ability of the ink to follow the rotation of the ball of the pen tip chip becomes poor, and the ball may run idle.

[0010] Pigments as colorants for the ink include inorganic and organic pigments such as carbon black, phthalocyanine pigments and azo pigments conventionally used in aqueous ballpoint pen inks, and resin emulsions such as styrene-acrylonitrile copolymer. A dye which is dyed with a basic dye, an oil-soluble dye, a fluorescent basic dye, a fluorescent whitening agent or the like can also be used in the present invention.

As the polar solvent, ethylene glycol which has been generally used in aqueous ballpoint pen inks,
Polyhydric alcohol solvents such as diethylene glycol and glycerin, and glycol ether solvents such as ethylene glycol / mono / butyl ether can also be used in the present invention.

Further, as other components of the ink composition, surfactants, rust preventives, preservatives, pH adjusters and the like generally used conventionally in aqueous ballpoint pen inks are also used in the present invention, if necessary. Can be selected and used.

[0013] As described above, the ink composition of the present invention uses polyethylene glycol monostearate or polyethylene glycol distearate as a thickening agent to provide a uniform and stable dispersion for a long period of time. Although an ink can be obtained, the viscosity of the ink tends to decrease with time when the ink is stored under high temperature conditions. When the ink viscosity decreases, there is a problem that ink is blown out from the pen tip when the pen is turned downward. In order to suppress such a problem, a nonionic surfactant other than polyethylene glycol monostearate and polyretylene glycol distearate is further added to the ink composition of the present invention as a viscosity stabilizer. It is desirable to do. By the addition of such a viscosity stabilizer, it is possible to prevent a decrease in ink viscosity particularly in a high-temperature environment. In addition, as a nonionic surfactant which can be used as a viscosity stabilizer, a polyoxyethylene / alkyl ether type or a polyoxyethylene / sorbitan fatty acid ester type can be exemplified, but it is not particularly limited thereto.

The HLB of the nonionic surfactant as a viscosity stabilizer is preferably from 15 to 19.5,
If B is less than 15, no effect as a viscosity stabilizer can be expected, and if HLB exceeds 19.5, there is a risk of breaking a uniform dispersion system, which is not preferred. The content thereof is preferably in the range of 0.2 to 5% by weight based on the total amount of the ink. If the content is less than 0.2% by weight, a sufficient viscosity stabilizing effect cannot be obtained. The addition is not preferable because there is a risk of breaking the uniform dispersion system.

[0015]

The present invention will be described below in detail with reference to examples and comparative examples.

Example 1 The following components were sequentially mixed with stirring and then dispersed by stirring with a homomixer to prepare an ink composition of the present invention having a viscosity of 205 cps (20 ° C., the same applies hereinafter). Carbon black dispersion 45.0% by weight ("WA Color Black" manufactured by Dainichi Seika Kogyo Co., Ltd.) Glycerin 20.0% by weight Polyethylene glycol monostearate 20% aqueous solution ("Emanon 3199" manufactured by Kao Corporation) , HLB 19.1) 12.5% by weight Potassium oleate 0.2% by weight Preservative ("Proxel XL-2" manufactured by Zeneca) 0.1% by weight Benzotriazole (rust inhibitor) 0.4% by weight Water balance

Example 2 The following components were sequentially mixed with stirring, and then stirred and dispersed by a homomixer to prepare an ink composition of the present invention having a viscosity of 510 cps.
Fluorescent yellow resin emulsion coloring pigment 40.0% by weight ("Lumicol NKW-2105" manufactured by Nippon Fluorescent Chemical Co., Ltd.) Glycerin 15.0% by weight Diethylene glycol 5.0% by weight 20% aqueous solution of polyethylene glycol distearate ("" Emanone 3299, Kao Corporation, HLB 18.3) 15.0% by weight Sodium dioctyl sulfosuccinate 0.2% by weight Preservative ("Proxel XL-2") 0.1% by weight Benzotriazole (rust inhibitor) 0 .2 wt% water balance

[Example 3] Polyoxyethylene nonylphenyl ether ("Emulgen 935" manufactured by Kao Corporation, HLB17.
5) was added in an amount of 2.0% by weight, and an ink composition of the present invention having a viscosity of 315 cps was prepared in the same manner as in Example 1.

[Example 4] In addition to the components of Example 2, polyoxyethylene sorbitan mono-oleate ("Reodol TW-0120" Kao Corporation) was used as a viscosity stabilizer.
(HLB 15.0) was added in an amount of 2.5% by weight, and an ink composition of the present invention having a viscosity of 560 cps was prepared in the same manner as in Example 2.

Comparative Example 1 Instead of the polyethylene glycol monostearate 20% aqueous solution of Example 1,
12.5% by weight of a 2% aqueous solution of xanthan gum is added,
An ink composition having a viscosity of 250 cps was prepared in the same manner as in Example 1.

Comparative Example 2 An ink having a viscosity of 490 cps was prepared in the same manner as in Example 2 except that 15% by weight of a 2% aqueous solution of xanthan gum was added instead of the 20% aqueous solution of polyethylene glycol distearate of Example 2. A composition was prepared.

Comparative Example 3 Instead of the aqueous solution of 20% polyethylene glycol monostearate of Example 1,
An ink composition having a viscosity of 250 cps was prepared in the same manner as in Example 1 by adding 12.5% by weight of a 2% aqueous solution of sodium polyacrylate (crosslinked and branched type).

Each of the aqueous ballpoint pen ink compositions obtained in the above Examples and Comparative Examples was examined for dispersibility, viscosity stability and stability over time by the following methods. Table 1 summarizes the obtained results.

A. Dispersibility After preparing the ink, the dispersion state of the pigment and the thickener is observed under a microscope of 200 to 400 times. Evaluation: Both the pigment and the thickener are uniformly dispersed. Δ: Dispersion of the pigment and the thickener is uneven. ×: The pigment is aggregated or the thickener is not dispersed at all.

B. Viscosity stability When the ink was put in a 100 ml glass bottle and stored at 50 ° C. for 2 weeks and 4 weeks, the viscosity of the upper part and the lower part of the ink was measured using an ELD viscometer at 20 ° C. at a shear rate of 10 S ^−1. Measure with

C. Stability over time An ink was filled into a ballpoint pen having a 3.5 mm inner diameter polypropylene ink storage tube and a 0.5 mm diameter ball, in which neither the ink storage body nor the ink guide core was provided. This ballpoint pen is placed at 50 ° C and 30% humidity for 3 minutes.
After storage for months and indoors (room temperature, natural humidity) for one year, observe the written condition. Evaluation: No change. Δ: The amount of ink supplied during writing is reduced or increased. ×: Writing is impossible.

[0027]

From the results in Table 1, it can be seen that the inks of Examples 1 to 4 of the present invention in which the viscosity was adjusted with polyethylene glycol monostearate or polyethylene glycol distearate provided a uniform dispersion system, Sinking,
It can be seen that there is no floating of the thickener and no viscosity change in the ink, and a stable ink can be obtained over time.

The ink of Example 1 and a nonionic surfactant polyoxyethylene.
Comparing with the ink of Example 3 to which nonylphenyl ether was added, it was found that the addition of the viscosity stabilizer suppressed the decrease in viscosity during high-temperature storage. Similarly, when comparing the ink of Example 2 with the ink of Example 4 to which polyoxyethylene sorbitan mono-oleate which is a nonionic surfactant was added as a viscosity stabilizer, the addition of the viscosity stabilizer It can be seen that the decrease in viscosity during high-temperature storage is suppressed.

[0030]

As can be seen from the above description, the aqueous ballpoint pen ink composition of the present invention using polyethylene glycol monostearate or polyethylene glycol distearate as a thickening agent has a uniform dispersion. No sedimentation of the pigment and no separation and floating of the thickening agent occur, and the composition is excellent over time.

Further, by further adding a predetermined amount of a nonionic surfactant to the ink composition of the present invention, a decrease in ink viscosity due to high-temperature storage can be effectively suppressed.

Claims (2)

[Claims] 1. An aqueous ball-point pen ink composition containing a pigment, water and a polar solvent, wherein the HLB is 15 to 19.
The polyethylene glycol monostearate or polyethylene glycol distearate is contained in an amount of 1 to 10% by weight based on the total weight of the ink, and the viscosity is 50.
An aqueous ballpoint pen ink composition characterized by being adjusted to 2000 cps (20 ° C.). 2. A nonionic surfactant having an HLB of 15 to 19.5 other than polyethylene glycol monostearate and polyethylene glycol distearate as a viscosity stabilizer, based on the total amount of the ink.
The aqueous ball-point pen ink composition according to claim 1, further comprising 0.2 to 5% by weight.