JPH10315681A - Ink follow-up member for aqueous ink ballpoint pen - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain suitable follow-up to ink by charging gellike material using base oil having satisfactory followability to ink side and low viscosity, and charging the material using high base oil advantageous for impact resistance to an ink containing tube tail end side, thereby improving resistance to strong dropping impact. SOLUTION: A predetermined ink 8 and ink follow-up member 9 are charged in an ink containing tube 7. Gel-like materials are charged in both ink side and tail end side of the member, the member is charged. A ballpoint pen tip having an ink occlusion material is mounted at an end of the pan. The member for an aqueous ink ballpoint pen has base oil having a viscosity at 25 of 2 Pa.sec or less by organic solvent charged at the ink side, gel-like material given by pseudoplastic viscosity by thickener, and gel-like material given by pseudoplastic viscosity by thickener to the base oil having viscosity at 25 deg.C of 2Pa.sec by organic solvent charged at ink containing tube tail end side. Thus, it can endure against strong dropping impact while having followability to the ink.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink follower for an aqueous ball-point pen used at the tail end of an ink for an aqueous ball-point pen directly housed in an ink storage tube.

[0002]

2. Description of the Related Art The viscosity of an ink for a water-based ball-point pen is 3 Pa · sec to 20 P for an oil-based ball-point pen having a similar form.
Since it is a · sec, it is as low as 50 mPa · sec to 3 Pa · sec, so that the ink leaks when the pen is left upward or sideways. In addition, since ink may be scattered even by a slight impact to stain hands and clothes, an ink follower is provided to prevent this. This ink follower is called a “backflow prevention body”.

JP-A-57-153070, JP-A-57-15370
200472, JP-A-61-57673, JP-A-61-57673
145269, JP-A-61-151289, JP-A-61-61289
-200187, JP-A-61-268786, JP-A-Showa 6
2-50379, JP-A-62-148581, etc.
It is disclosed that a water-based ball-point pen for directly storing ink in an ink storage tube is provided with a gel-like backflow preventer.

[0004] When these backflow preventers are left upright or sideways, they exhibit sufficient performance against the prevention of ink spillage and light drop impact. However, the conventional gel-like ink follower, especially a gel-like ink follower using a low-viscosity base oil with good followability to ink, has a sharp viscosity when subjected to a strong drop impact. Degrade and lose its function.

The prior art ink follower is obtained by imparting pseudoplasticity to a water-insoluble base oil with fine-particle silica or the like, and the viscous behavior changes drastically as the pseudoplasticity becomes stronger and the impact becomes stronger. . That is, the viscosity sharply decreases, the fluidity increases, and the ink follower (backflow prevention body) itself scatters. In the ink follower, this property appears when a strong drop impact is applied.

As an example of the strongest “light drop impact” in the text, a pen is placed on a desk (about 70 cm).
m) to the floor. In this case, the ink follower of the related art may have some variation in the ink follower, but hardly causes any inconvenience.

[0007] However, in the process of pen distribution, it is considered normal to drop from a shelf (about 150 cm) approximately at eye level. In this case, 2
Since the impact is more than doubled, the ink follower may flow in the ink storage tube, and the ink may leak out. Furthermore, when the contents of the ink storage tube flow dramatically like this, excessive pressure is also applied to the vicinity of the pen tip,
Frequent accidents where the ball jumps out of the chip holder.

Although there is no problem with such a light impact,
The tendency of the ink follower to lose its function due to a strong drop impact is more remarkable in an ink follower having a lower base oil viscosity. However, the lower the viscosity of the base oil of the ink follower, the better the ability to follow the ink, and conversely, the higher the viscosity of the base oil, the worse the ability to follow the ink.

For example, US Pat. No. 4,671,691 discloses 49% polybutene, 49% mineral oil, and dimethyldioctadecyl ammonium bentonite 2 as a thickener.
% Of a viscoelastic ink follower is disclosed. Briefly describing this ink follower from the viewpoint of the present invention, it is a product obtained by imparting a weak pseudoplasticity to a highly viscous base oil using a clay-based thickener. Sex is not good.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems with respect to a strong drop impact which is a drawback of the conventional water-based ballpoint pen. That is, an object of the present invention is to provide an ink follower for a water-based ballpoint pen, which has improved resistance to a strong drop impact and has appropriate followability to ink.

As a matter of course, shutting off the ink and the outside air to prevent the ink from volatilizing (volatilization preventing property);
It is an object of the present invention to provide an ink follower for a water-based ball-point pen, which also has a function of preventing leakage of ink from the rear end of an ink storage tube after upward writing (leakage prevention).

[0012]

Means for Solving the Problems The present inventors have conducted intensive studies on the above-mentioned problems, and as a result, filled the ink side with a gel-like substance using a low-viscosity base oil having good follow-up properties, and prepared an ink containing pipe tail. By filling the end side with a gel-like material using a base oil having a high impact resistance, it was found that both disadvantages were complemented, and the present invention was completed.

The ink follower for aqueous ballpoint pens of the present invention has a temperature of 25 ° C. selected from non-volatile or non-volatile (hereinafter simply referred to as non-volatile) non-water-soluble organic solvents to be filled in the ink side. Base oil having a viscosity of 2 Pa · sec or less, a gel-like substance provided with pseudoplastic viscosity by a hydrophobic thickener, and filling the ink storage tube at the tail end (hereinafter simply referred to as the tail end) It is composed of a base oil having a viscosity of 2 Pa · sec or more at 25 ° C. selected from the hardly volatile organic solvents to be used and a gel-like substance provided with pseudoplastic viscosity by a thickener.

As the gel material on the ink side, Japanese Patent Application Laid-Open No.
153070, JP-A-57-100472, JP-A-61-61
-57673, JP-A-61-145269, JP-A-61-61269
JP-A-151289, JP-A-61-200187, JP-A-Showa 6
1-268786, JP-A-62-250379, JP-A-6-50379
A conventional ink follower such as that described in 2-148581 can be used as it is. However, since the tail end side is filled with a gel-like substance that is advantageous for impact resistance, a base oil having good follow-up properties has a low viscosity. Gels can be used.

The viscosity of the base oil of the gel material on the ink side used in the present invention is 2 Pa · sec or less at 25 ° C., preferably 1 Pa · sec or less. If the viscosity of the base oil exceeds 2 Pa · sec, the ability to follow the ink will deteriorate, and the amount adhered to the inner wall of the ink storage tube will be large. As a result, the function as an ink follower is lost.

In the present invention, the base oil has a viscosity of 2 Pa ·
Although a gel-like substance exceeding sec is used, the gel-like substance on the tail end side will be consumed by the end of the stroke because a large amount of the gel-like substance adheres to the inner wall of the ink storage tube.

However, since the ink is also consumed by writing, even if all of the gel at the tail end is lost,
Since the weight of the ink is reduced, the burden on the ink follower is reduced, and even if the base oil has a low viscosity, it can withstand a strong drop impact, so that there is no problem.

Examples of the solvent used as the base oil for the gel material on the ink side and the tail end side include polybutene having a molecular weight of 500 to 3,000, mineral oils such as liquid paraffin and spindle oil, and silicone oil. Further, the gel-like substance on the tail end side may be a water-soluble, non-volatile solvent such as glycerin. These may be used alone or in combination.

The thickener used for the gel material on the ink side used in the present invention is selected from hydrophobic or water-insoluble ones. The hydrophilic thickener migrates into the ink from the interface with the ink, causing the pseudoplasticity of the ink follower to be lost, causing the ink to flow backward when left standing upward, or the base oil to float in the ink, making writing impossible. Inconveniences such as occur.

The tail end thickener may be hydrophilic.

Accordingly, as a thickener for a gel-like substance used on the ink side, Nippon Aerosil Aerosil R-972,
Fine particle silica such as R-974D and R-976D, whose surface is methylated, clay thickener whose surface is hydrophobized by onium treatment such as dimethyldioctadecyl ammonium bentonite, or lithium stearate, aluminum stearate, stearin It is desirable to use a water-insoluble metal soap such as sodium acid. These may be used alone or in combination, but their total amount is 1 to 10% by weight based on the total amount of the ink follower.

Since the thickener used for the gel material on the tail end side may be hydrophilic, in addition to the thickener used for the gel material on the ink side, the surface is covered with a hydrophilic group. Fine particle silica or a general viscosity thickener that has not been subjected to hydrophobic treatment can also be used.

It is also an effective means to use a surfactant in order to improve the follow-up properties of the ink-side and tail-end gel materials used in the present invention with the ink. The type of the surfactant is not limited, but it is not preferable that the gel on the ink side elutes into the ink during storage over time, and a nonionic surfactant having an HLB (hydrophilic / hydrophobic balance) value of 4 or less is preferable. . Furthermore, what is generally called a fluorine-based surfactant or a silicon-based surfactant is most preferable because it significantly lowers the surface tension of the base oil.

The amount of the surfactant added is from 0.01%, which is the minimum amount at which the effect is exhibited, to 5% by weight at the maximum.
It is about. When used in an amount exceeding 5% by weight, there is no problem in performance, but the effect of addition is completely meaningless.

The method of producing the gel material used in the present invention may be the same as that of the prior art ink follower on both the ink side and the tail end side.
For example, when using a hydrophobic silica or clay-based thickener, all gel-like components such as a base oil and a surfactant are pre-kneaded at room temperature, and then dispersed with a disperser such as a three-roll mill or a kneader. A very simple method of kneading may be used. When metal soap is used as the thickener, it must be kneaded by heating to a high temperature of 200 ° C. or higher, and the surfactant must be added after cooling according to its heat resistance.

An example of a method for filling the gel material on the tail end side used in the ink follower of the present invention is as follows. An ink is filled in an ink storage tube, a pen point is attached, and the gel material on the ink side is removed from the ink. After filling the rear end, a solid is introduced from the tail end of the ink storage tube. Thereafter, when a strong centrifugal force is applied from the tail end to the pen tip by a centrifugal separator, the ink, the ink-side gel-like substance, and the tail-end-side gel-like substance are filled with good appearance without air or the like between them. You.

[0027]

The present invention will be further described with reference to Examples and Comparative Examples.

The measurement of the viscosity of the base oil and the ink in Examples and Comparative Examples was performed using an EMD viscometer manufactured by Toki Sangyo.

The filling of the ink follower is performed by a domestic centrifuge H
Using a -103N centrifuge, centrifugal force was applied at 2800 revolutions per minute for 10 minutes so that centrifugal force was applied from the tail end of the pen toward the pen tip.

Water-based ballpoint pen: The one having the structure shown in FIG. 2 was used. A translucent polypropylene tube having an inner diameter of 4.0 mm was used as an ink storage tube 7 and filled with a predetermined ink 8 and an ink follower 9 of each of Examples and Comparative Examples. In the embodiment, the ink follower is filled with about 0.8 g of the gel-like material on both the ink side and the tail end side, and the ink follower is about 0.16 g in the comparative example.
g. The same ball-point pen tip as a water-based ball-point pen having an ordinary fiber bundle ink absorbing member was attached to the pen tip. The material of the ballpoint pen tip holder 3 was a free-cutting stainless steel, and the ball 4 was a tungsten carbide having a diameter of 0.5 mm.

Thirty aqueous ballpoint pens were prepared for each of the examples and comparative examples, and ten pens were spirally written at a speed of 4.5 m / min until the ink ran out, and the followability to the ink was examined. The ink criterion was evaluated as follows: if there is some adhesion to the inner wall, the function of the ink follower is not lost until the end. Those that have been completely consumed in are marked as x.

Further take 10 caps, drop them on concrete from the height of 1.5m and land on the tail end side of the pen, and count the number of inks leaked and the number of balls jumped out. Was.

Write the remaining 10 pens with the pen tip facing upward until the drawing line cannot be drawn, and then stand the test tube stand with the pen tip facing upward to reverse the ink flow. The number of leaks was counted.

Table 1 shows the test results.

Inks: Aqueous ballpoint pen inks used in Examples and Comparative Examples were prepared as follows. PRINTEX 25 (carbon black; trade name of Degussa) 7 parts by weight PVP K-30 (polyvinylpyrrolidone; manufactured by GAF) 3.5 {glycerin 10} potassium ricinoleate 0.5 {triethanolamine 1} 1,2- After kneading benzisothiazolin 3-one 0.2 {benzotriazole 0.2} water 27.2} or more with a bead mill, coarse particles of carbon black are removed and propylene glycol 20 parts by weight Carbopol 940 (crosslinked polyacrylic acid; BF Goodrich Co., Ltd.) 0.4 {water 30} was added to obtain an ink for a water-based ball-point pen having a viscosity at 40 sec ^-1 of 500 mPa · sec.

Example 1 Gel on the ink side: Polybutene 35R (Idemitsu Kosan, trade name; MW = 720) 47.4 parts by weight Diana Process Oil MC-S32 (mineral oil; Idemitsu Kosan, trade name) 47.5 〃 Aerosil R-976D (hydrophobic silica; Nippon Aerosil trade name; BET surface area 300 / g) 5 {F-top EF-801 (fluorinated surfactant; Mitsubishi Materials trade name) 0.1} To obtain an ink-side gel. Tail-end gel: Polybutene 35R 97.9 parts by weight Aerosil R-976D 2 {F-Top EF-801 0.1} The above compound was kneaded with a three-roll mill to obtain a tail-end gel. . The ink-side gel and the tail-end gel were used in combination to form an ink follower.

(Example 2) Gel on the ink side: Nissan polybutene 015N (Nippon Oil & Fats, trade name; MW = 580) 95 parts by weight Aerosil R-974D (Nippon Aerosil trade name; BET surface area 200 / g) 4 @ SILWET FZ 2110 (Silicone-based surfactant; Nippon Unicar product name) 1 The above-mentioned compound was kneaded with a three-roll mill to obtain an ink-side gel. Tail end gel: Nissan polybutene 200SH (Nippon Oil & Fat Co., Ltd .; MW = 2650) 48.4 parts by weight Diana Process Oil MC-W90 (mineral oil; Idemitsu Kosan Co., Ltd.) 48.5 エ ロ Aerosil R-972 (hydrophobicity) Silica; Nippon Aerosil trade name; BET surface area 110 / g) 3 {F-Top EF-801 (Fluorine-based surfactant; Mitsubishi Materials trade name) 0.1} A side gel was obtained. The ink-side gel and the tail-end gel were used in combination to form an ink follower.

Example 3 Ink-side gel-like substance: Diana Process Oil MC-W90 (mineral oil; trade name of Idemitsu Kosan Co., Ltd.) 96 parts by weight Aerosil R-974D 3 ３ SILWET FZ-2171 (silicone surfactant; Nippon Unicar 1) The above formulation was obtained in the same manner as in Example 1 to obtain an ink-side gel. Tail end side gel: Nissan polybutene 5N (Nippon Oil & Fats, trade name; MW = 780) 97.5 parts by weight Aerosil # 380 (fine particle silica; Nippon Aerosil trade name; BET surface area 380 / g) 2 {SILWET FZ-21100} The above mixture was kneaded with a three-roll mill to obtain a gel on the tail end side. The ink-side gel and the tail-end gel were used in combination to form an ink follower.

(Comparative Example 1) Same as the ink-side gel of Example 1 (Comparative Example 2) Same as the tail-side gel of Example 1 (Comparative Example 3) Ink-side gel of Example 2 Same as (Comparative Example 4) Same as the tail-side gel in Example 2 (Comparative Example 5) Same as the ink-side gel in Example 3 (Comparative Example 6) Tail-side gel in Example 3 Table 1 shows the viscosities of the base oils used for the gels of the respective Examples and Comparative Examples.

[0040]

[Table 1]

[0041]

[Table 2]

[0042]

As described above, the ink follower for water-based ball-point pens of the present invention, which uses a gel material having a different viscosity in combination, has the ability to follow the ink until the end of the ink, and even when subjected to a strong drop impact. An ink follower that does not cause leakage or drop off balls and has an excellent leakage prevention effect.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating positions of two types of gel-like materials of an ink follower.

FIG. 2 is a sectional view showing an example of an aqueous ballpoint pen using the ink follower of the present invention.

[Explanation of Signs] (a) Interface between ink and gel-like substance (b) Interface between two kinds of gel-like substances (1) Cap (2) Pen tip sealing rubber (3) Pen tip (ballpoint pen tip holder) (4) Ball (5) Joint between pen tip and ink container (6) Ballpoint pen shaft 7 Ink storage tube 8 Ink 9 Ink follower 10 Tail plug

Claims (1)

[Claims] 1. An ink follower for an aqueous ballpoint pen, comprising a base oil having a viscosity at 25 ° C. of 2 Pa · sec or less in an aqueous ballpoint pen having an ink storage tube.