Compositions: coating or plastic – Coating or plastic compositions – Marking
Reexamination Certificate
2000-04-27
2001-07-17
Klemanski, Helene (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Marking
C106S031580, C106S031680, C106S031860, C106S031690, C106S031370
Reexamination Certificate
active
06261351
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a water based ink for a ball point pen.
BACKGROUND ART
Water based inks have so far had the problem that if moisture thereof is evaporated, for example, dissolved substances and dispersed components contained in the inks are concentrated, deposited, dried and solidified to bring about clogging at the tips of the writing instruments and to increase a viscosity of the inks, thereby causing troubles in writing.
In this connection, it is proposed to add to a water based ink for a ball point pen, scarcely volatile dye-solubilizing agents or dye-dissolving aids such as urea, thiourea, polyhydric alcohols or derivatives thereof, tetrahydrofurfuryl alcohol, 4-methoxy-4-methylpentane-2-one, ethylene oxide adducts of p-toluenesulfonamide and thiodiethanolalkynolamine.
However, these urea, thiourea and polyhydric alcohols have not been able to provide satisfactory water based inks because of the reasons that they have an insufficient drying prevention effect or they have toxicity and are unsuitable for additives and that they allow a viscosity of the ink to grow large to bring about inferior follow-up of the ink.
Proposed in Japanese Patent Application NO. 9-181391 by the present applicant was a pseudoplastic water based ink for a ball point pen comprising a colorant, water, a water-soluble organic solvent and a viscosity-controlling agent and reducing dextrin or reducing maltodextrin. These inks using a water-soluble organic solvent such as glycols, glycerin and glycol ethers are increased in feathering of the drawn lines. Further, they do not provide sufficient lubricity, so that a ball point pen using them is increased in frictional resistance between the ball and the ball housing to abrade the ball housing and therefore has the defect that the writing property is notably reduced, such that the ball sinks and the ink is discharged unevenly.
Further, proposed in Japanese Patent Application Laid-Open No. 8-12916 is an ink comprising titanium oxide, a thickening water-soluble resin, a binder, a sugar alcohol and water, wherein a viscosity value is 6,000 to 50,000 mPa·s, and a viscosity index obtained according to a difference in a revolution of a viscometer is 2 or more. However, even an ink having such a high viscosity index does not solve the problems of a follow-up property in quick writing and splitting of the drawn lines. Further, it contains only a white pigment as a colorant and has the problem that a marking ability is inferior.
Further, it is proposed in Japanese Patent Application Laid-Open No. 5-186730 to add an alkylene oxide adduct of polyglycerin in order to improve feathering. However, though the adding of the alkylene oxide adduct of polyglycerin improves the feathering resistance and the writing feeling, the drying prevention effect at a pen tip is not provided. Accordingly, there remains unsolved the problem that when the pen is left standing with the cap off, moisture is vaporized from the pen tip and the pen tip is dried, so that the writing property is reduced.
An object of the present invention is to solve the problems described above, that is, to provide a water based ink for a ball point pen which is good in feathering resistance and writing feeling and has high discharge stability of the ink and which is excellent in a drying prevention effect at a pen tip.
DISCLOSURE OF THE INVENTION
Intensive researches continued by the present inventors in order to solve the problems described above have resulted in finding that the part of the preventing of drying at a pen tip which has so far been an action exerted by water-soluble organic solvents is allotted to at least one selected from the group consisting of a reducing sugar comprising maltitol as a principal component, a reducing sugar comprising sorbitol as a principal component, reducing dextrin, reducing maltodextrin, &agr;-cyclodextrin, &bgr;-cyclodextrin and maltosylcyclodextrin without using water-soluble organic solvents such as glycols, glycerin and glycol ethers which have so far been used for a water based ink for a ball point pen, and the parts of actions to inhibit feathering of the drawn lines, to improve a discharge stability of the ink and to maintain the lubricity are allotted to at least one selected from the group consisting of an alkylene oxide adduct of polyglycerin, an alkylene oxide adduct of glycerin and an alkylene oxide adduct of trimethylolpropane, whereby the respective effects are improved more markedly than ever, and a synergistic effect of raising the stability with the passage of time is produced.
BEST MODE FOR CARRYING OUT THE INVENTION
A reducing sugar comprising maltitol as a principal component, a reducing sugar comprising sorbitol as a principal component, reducing dextrin, reducing maltodextrin, &agr;-cyclodextrin, &bgr;-cyclodextrin and maltosylcyclodextrin which are used in the present invention are sugars which are generally used as edible sweetenings and which are non-toxic and safe and have the characteristics that they have high solubility in water and very excellent water retention.
Further, a water based ink for a writing instrument containing these compositions is safe and not varied in a viscosity and a pH with the passage of time and makes it possible to improve the writing feeling and the drying resistance. Further, they do not exert an adverse effect on ink composition materials generally used and do not change a hydrogen ion concentration in the ink, so that they do not exert an adverse effect as well on anionic and cationic materials and therefore have the advantage that a colorant can be optionally selected from all water based dyes and organic or inorganic pigments.
With respect to a content of a reducing sugar comprising maltitol as a principal component, a reducing sugar comprising sorbitol as a principal component, reducing dextrin, reducing maltodextrin, &agr;-cyclodextrin, &bgr;-cyclodextrin and maltosylcyclodextrin in the ink in the present invention, at least one of them is added in an amount of 0.5 to 20% by weight based on the total amount of the ink. If the content is smaller than 0.5% by weight, the effect of the drying resistance is reduced, and if it is more than 20% by weight, the spinnability is intensified to reduce the writing feeling.
On the other hand, at least one selected from the group consisting of an alkylene oxide adduct of polyglycerin, an alkylene oxide adduct of glycerin and an alkylene oxide adduct of trimethylolpropane, and a mixture thereof have a purpose to elevate the feathering resistance and the lubricity and to improve the discharge stability of the ink, and the combination of blending with the reducing sugar and the reducing dextrin described above produces a synergistic effect of raising the drying resistance at a pen tip (hereinafter referred to as a non-drying property) and the stability with the passage of time. A content thereof is 0.5 to 40% by weight, more preferably 5 to 20% by weight based on the whole composition.
There can be used as the colorant all dyes which are soluble or dispersed in water, and all pigments such as titanium oxide, publicly known inorganic and organic pigments, pseudo-pigments obtained by coloring resin emulsions with dyes, and white plastic pigments.
Specific examples thereof include acid dyes such as Eosine, Phloxine, Water Yellow #6-C, acid red, Water Blue #105, Brilliant Blue FCF and Nigrosine NB, direct dyes such as Direct Black 154, Direct Sky Blue 5B and Violet BB, and basic dyes such as Rhodamine and Methyl Violet.
Inorganic pigments include, for example, carbon black and metal powders.
Organic pigments include, for example, azo lake, insoluble azo pigments, chelate azo pigments, phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dye lakes, nitro pigments and nitroso pigments.
To be specific, included are inorganic pigments such as carbon black, titanium black, zinc oxide, red iron oxide, chromium oxide, black iron oxide, cobalt blue, yellow iron oxide, viridian, zinc sulfide, lith
Miyamoto Masaru
Miyazaki Shigeru
Takeuchi Yoji
Darby & Darby
Faison Veronica F.
Klemanski Helene
Mitsubishi Pencil Kabushiki Kaisha
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