Aqueous ink composition for ball-point pen

Details Aqueous ink composition for ball-point pen Aqueous ink composition for ball-point pen

1999-08-26

2001-08-14

Acquah, Samuel A. (Department: 1711)

Data processing: artificial intelligence

Neural network

Structure

C106S014110, C106S014130, C106S014340, C106S014410, C106S031250, C106S031280, C106S031310, C106S031360, C106S031370, C106S031390, C106S031400, C106S031430, C106S031440, C106S031550, C106S031590, C524S027000, C524S028000, C524S031000, C524S047000, C524S055000, C524S056000, C524S077000, C524S081000, C524S276000

Reexamination Certificate

active

06275816

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an aqueous ink composition for a ball-point pen.
2. Description of the Related Art
Conventionally, an aqueous ink for a ball-point pen has been disclosed in Japanese Patent Laid-Open No. 59-74175 or Japanese Patent Laid-Open No. 59-138281.
The aqueous ink disclosed in Japanese Patent Laid-Open No. 59-74175 contains xanthane gum of between 0.20 to 0.45 wt. %, and the aqueous ink disclosed in Japanese Patent Laid-Open No. 59-138281 contains xanthane gum of between 0.20 to 0.45 wt. % and a permeable dying agent of between 0.5 to 10.0 wt. %, for providing pseudo plasticoviscosity.
However, since xanthane gum is an ionic polysaccharide, when a large amount of xanthane gum is used, it reacts with an ionic component in the ink, preservation stability is impaired, and phenomena such as ink shortage, dripping, or dripping-down occur at an ordinary (e.g., operating) temperature for a half year to one year, resulting in writing failure. To solve these problems, Japanese Patent Laid-Open No. 6-256700, provides aqueous ink for a ball-point pen containing xanthane gum of 02. wt. % or less and a non-ionic polysaccharide of 0.01 to 0.5 wt. %, thereby improving stability over time.
When xanthane gum and non-ionic polysaccharide are mixed together, ink preservation stability is improved. However, because of non-ionic properties of polysaccharide, when the non-ionic polysaccharide is added, lengthy stirring must be performed to disperse the non-ionic polysaccharide. In addition, even after the ink has been prepared, when microscopic observation is performed to confirm the dispersion state of a pigment, there have been observed blocks of any components failing to disperse. This problem leads to writing failures.
SUMMARY OF THE INVENTION
In view of the foregoing and other problems, disadvantages, and drawbacks of the conventional aqueous ink for a ball-point pen, the present invention has been devised, and it is an object of the invention to provide an aqueous ink for a ball-point pen which has high stability over time and high pigment dispersion stability.
The present inventors have conducted extensive research to solve the above problems. As a result, the inventors discovered that the above object could be achieved by mixing a small amount of xanthane gum and an ionic polysaccharide together, and the invention is based on this finding.
That is, the aqueous ink for the ball-point pen of the invention includes a pigment, a water-soluble organic solvent, and water, and is characterized by containing xanthane gum of substantially about 0.01 to about 0.2 wt. % and an ionic polysaccharide of substantially about 0.2 to about 0.6 wt. % other that xanthane gum in a total quantity of the ink.
Xanthane gum of about 0.01 to about 0.2 wt. % is used for the aqueous ink for the ball-point pen of the present invention. If xanthane gum exceeds about 0.2 wt. %, it reacts with an ionic polysaccharide, and the ink preservation stability is impaired over time. Further, if the xanthane gum exceeds about 0.45 wt. %, writing properties of the aqueous ink are impaired, which is not preferable.
Specifically, xanthane gum includes “Kelzan” (Trade Name)(supplied by Kelco Division of Merck & Co., Ltd.) and, “Echo Gum”, “Kertrol” and “Monat Gum” (Trade Names) (supplied by Dainippon Pharmaceutical Co., Ltd.).
As an ionic polysaccharide, sodium alginate is preferable and it mixes well with water. Besides sodium alginate, a natural Arabic gum, casein, gelatin, carrageenan, alginic acid, semi-synthetic carboxymethyl cellulose, sodium carboxymethylstarch, synthetic sodium polyacrylate, and/or polyacrylic acid can be used. Sodium alginate specifically includes “Manucol DMF” and “Manugel GMB” (commercially available from Dainippon Pharmaceutical Co., Ltd.) or the like.
Xanthane gum and an ionic polysaccharide other than xanthane gum are combined together, thereby uniformly dispersing a pigment quickly. Pigment dispersion stability and preservation stability are improved, and further, proper viscosity is achieved, thereby improving writing performance.
If an ionic polysaccharide such as sodium alginate exceeds about 0.6 wt. %, supernatant liquid is produced, which impairs writing performance. In contrast, if an ionic polysaccharide such as sodium alginate is less than about 0.2 wt. %, pigment stability cannot be maintained, and color gradation is produced.
Further, if only sodium alginate is used, without combining xanthane gum, thixotropy properties cannot be obtained. Similarly, when only using xanthane gum of about 0.2 wt. % or less, without combining an ionic polysaccharide, pigment stability cannot be maintained, and color gradation is produced.
However, when xanthane gum of about 0.01 to about 0.2 wt. % and an ionic polysaccharide, such as sodium alginate of about 0.2 to about 0.6 wt. %, are combine together, an ink can be produced having superior stability over time, superior pigment dispersion properties, and proper viscosity. Incidentally, when the content of xanthane gum in the ink is less than about 0.01 wt. %, thixotropy properties cannot be obtained. The relationship of varying combinations of xanthane gum and an ionic polysaccharide, such as sodium alginate, on the quality and properties of the ink is shown in Table 1 below.
TABLE 1
Combination of Components (wt %)
Ink
Large amount of xanthanegum only
Poor writing performance
(more than about 0.45 wt. %)
Only xanthane gum (about 0.2 to
Poor stability over time
0.45 wt. %)
Small amount of xanthane gum only
Pigment stability cannot be maintained
(less than about 0.2 wt. %)
and color gradation isproduced
Xanthane gum (about 0.01 to about 0.2
Poor writing performance and
wt. %) and sodium alginate of more than
supernatant liquid produced
0.6 wt. %
Xanthane gum (about 0.01 to about 0.2
Good stability with an elapse of time,
wt. %) and sodium alginate (about 0.2 to
good pigment dispersion properties and
about 0.6 wt. %)
proper viscosity
Xanthane gum (about 0.01 to about 0.2
Pigment stability cannot be maintained,
wt. %) and sodium alginate (less than
and color gradation is produced
about 0.2 wt. %)
Xanthane gum (less than about 0.01
Thixotropy properties cannot be obtained
wt. %) and sodium alginate
Only sodium alginate
Thixotropy properties cannot be
obtained
As a pigment, there can be used any of inorganic and organic pigments routinely used in conventional aqueous ink compositions without being limited thereto. The inorganic pigment may include titanium oxide, carbon black, metal powder or the like, for example. Further, the organic pigment may include azo-lake insoluble azo-pigment, chelate azo-pigment, phthalocyanine pigment, perylene and perinone pigments, anthraquinone pigment, quinacridone pigment, lake pigment, nitro pigment, nitroso-pigment or the like.
Specifically, there are exemplified Phthalocyanine blue (C. I. 74160), Phthalocyanine Green (C. I. 74260), Hansa Yellow 3G (C. I. 11670), Disazoyellow GR (C. I. 21100), Permanent Red 4R (C. I. 12335), Brilliant Carmin 6B (C. I. 15850), Quinacridone Red (C. I. 46500) or similar colors.
These pigments may be employed singly, or used in any combination. The pigment content of a total amount of the ink is generally substantially within the range of about 4 to about 12 wt. %, and is preferably within the range of about 6 to about 8 wt. %. If pigment content exceeds 12 wt. %, dispersion properties are inferior, which is not preferable.
As a water-soluble organic solvent, there can be used glycerin, diglycerin, ethylene glycol, diethylene glycol, tridiethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, thiodiglycol, 1-3-butylene glycol, 2-pyrrolidone, n-methyl-2-pyrrolidone, dimethylformamide, dimethylimidazolidinone or the like, singly or in combination. If ethylene glycol is used as one of water-soluble organic solvent and a content of ethylene glycol is not less than about 11 wt. %, cap-off property which is a property of retaining writability for a prolonged period of time with the cap removed from the pen,

Affiliated with

Also associated with

Rating

Aqueous ink composition for ball-point pen does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Aqueous ink composition for ball-point pen, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Aqueous ink composition for ball-point pen will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2527586