Coating implements with material supply – Including floating follower in reservoir – Fluid follower
Reexamination Certificate
1999-12-10
2001-03-13
Walczak, David J. (Department: 3751)
Coating implements with material supply
Including floating follower in reservoir
Fluid follower
C106S031130, C523S161000
Reexamination Certificate
active
06200053
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an ink follower composition for a ballpoint pen and a ballpoint pen using the same. In particular, in a ballpoint pen having a ball point tip and an open-ended ink container containing middle- to high-viscosity or shear-thinning ink, the present invention relates to an ink follower composition for ballpoint pen which is applied to the end of ink in the open-ended ink container.
BACKGROUND OF THE INVENTION
In ballpoint pens using high-viscosity oil-base ink, a mixture of a mineral oil and a metallic soap (i.e., grease) has been used as an ink follower composition also called “liquid stopper” or “a back flow preventing composition”.
When applied to ballpoint pens using middle-viscosity oil-base ink or shear-thinning aqueous ink, the ink follower applicable to the high-viscosity oil-base ink does not follow the ink satisfactorily or fails to prevent the ink from flowing backward because of its large viscosity change with temperature. Hence, various gelatinous polybutene-based ink followers comprising a hardly volatile organic liquid, typically exemplified by liquid polybutene, and a thickener have been proposed and put to practical use broadly in ballpoint pens using the aforementioned ink.
Conventional thickeners include dibenzylidene sorbitol, tribenzylidene sorbitol (see JP-B-1-10554), N-acylamino acid derivatives (see JP-A-57-200472), clay having been surface-treated with an onium compound having a long-chain alkyl group (see JP-B-7-17872 corresponding to U.S. Pat. No. 4,671,691), and silica having been surface-treated with a hydrophobic group (see JP-B-6-33025). The terms “JP-A” and “JP-B” as used herein mean an “unexamined published Japanese patent application” and an “examined Japanese patent publication”, respectively.
The ink follower comprising the hardly volatile liquid and the conventional thickener is used to plug the end of ink contained in a transparent or semitransparent ink tube so as to prevent ink from evaporating and from flowing backward even when the ballpoint pen is left to stand for a long period of time with its tip upward or when a shock is given to the ballpoint pen by, for example, dropping. However, when the ink follower follows the ink with the ink consumption, it moves with the ink adhering to the inner wall of the ink container. As a result, a certain amount of the ink remains on the inner wall uselessly so that the writing length is shorter than what should have been expected from the amount of the ink in the container. Besides, the ink staining the inner wall not only makes the remainder of the ink invisible but deteriorates the appearance.
SUMMARY OF THE INVENTION
An object of the present invention is to eliminate the above-mentioned disadvantages of conventional ink followers for ballpoint pens. That is, an object of the invention is to provide an ink follower composition for a ballpoint pen which leaves no ink behind as adhered to the inner wall of the ink container and thereby provides a ballpoint pen that secures a writing length as expected and has visibility for confirming the residual amount of the ink and good appearance.
As a result of extensive investigations, the present inventors have found that an ink follower composition accomplishing the above object can be obtained by adding synthetic mica to a hardly volatile liquid.
The invention provides an ink follower composition for a ballpoint pen which comprises a hardly volatile liquid and expansible synthetic mica having a quaternary ammonium ion introduced therein and an ink follower composition for a ballpoint pen which comprises a hardly volatile liquid, a thickener, and synthetic mica.
The invention embraces an ink follower composition for a ballpoint pen in which the synthetic mica is present in an amount of 0.2 to 30% by weight based on the total composition; an ink follower composition for a ballpoint pen in which the hardly volatile liquid is polybutene, an &agr;-olefin cooligomer or a mixture thereof; an ink follower composition for a ballpoint pen in which the hardly volatile liquid is dimethyl silicone oil, methylphenyl silicone oil, alkyl-modified silicone oil or a mixture thereof; an ink follower composition for a ballpoint pen which further comprises atactic polypropylene; and an ink follower composition for a ballpoint pen in which the composition has a 1-minute value of from 25 to 50 mm as measured with a spreadmeter at 20° C.
The invention also provides a ballpoint pen comprising a middle- to high-viscosity ink or shear-thinning ink, a ball, a tip for holding said ball at the top end thereof and for discharging the ink from the top end thereof, an ink container for containing the ink and for supplying the ink to the tip, the ink container communicating with the rear of the tip either directly or via a connecting member, and the above-described ink follower composition which is applied to the rear end of the ink and follows the ink with ink consumption.
The ink follower composition according to the invention follows ink as ink is consumed without leaving the ink behind on the inner wall of the ink container. Therefore, a user can confirm the residual amount of ink, and the ballpoint pen using the ink follower secures the expected writing length with stable ink feed on use. The ink follower composition of the invention has little temperature dependence of viscosity in a practical temperature range and is excellent in stability with time and impact resistance. Therefore it performs its function, keeping the interface with ink without undergoing liquid separation or causing back flow of ink.
REFERENCES:
patent: 3656857 (1972-04-01), Seregely
patent: 5874488 (1999-02-01), Wang et al.
patent: 0 792 759 A2 (1997-09-01), None
patent: 57-200472 (1982-12-01), None
patent: 64-10554 (1989-02-01), None
patent: 6-33025 (1994-05-01), None
patent: 7-17872 (1995-03-01), None
Asami Hideaki
Yokotani Toshiji
Sughrue Mion Zinn Macpeak & Seas, PLLC
The Pilot Ink Co., Ltd.
Walczak David J.
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