Erasable ink compositions

Details Erasable ink compositions Erasable ink compositions

1989-10-26

1992-06-09

Dixon, Jr., William R.

Compositions: coating or plastic

Coating or plastic compositions

Metal-depositing composition or substrate-sensitizing...

106499, 106500, 523161, 523160, 523205, 524560, 524561, 524562, 524563, 524575, 524577, C09D 1110

Patent

active

051203596

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to ink compositions and more particularly to ink compositions erasable with a rubber eraser after writing.


PRIOR ART AND ITS PROBLEMS

Ink compositions erasable with a rubber eraser after writing (hereinafter referred to as "erasable ink") are known. For example, Japanese Unexamined Patent Publication No.59-223,769 discloses an "ink composition characterized in that it is prepared by uniformly dispersing a pigment selected from carbon black and aniline black in an aqueous medium having dissolved therein polyethylene oxide in the presence of a surfactant containing polyoxyethylene groups". However, the disclosed erasable ink is poor in stability, unsatisfactory in erasability, and difficult to erase in a long period after writing. Other erasable inks of various compositions heretofore proposed are insufficient in at least one of shelf life, erasability, fluidity and the like required of erasable inks, and thus all of them fail to achieve the desired results.


MEANS FOR RESOLVING THE PROBLEMS

In view of the foregoing present situation of the prior art, we conducted extensive research and found that the compositions which contain a resin having a specific minimum film-forming temperature or glass transition point (hereinafter referred to merely as "film-forming temperature") can alleviate the problems of conventional erasable inks to a great extent. According to the present invention, there is provided the following erasable ink:
(1) an ink composition erasable with a rubber eraser, the composition comprising 1 to 50% of a pigment, 3 to 50% of a resin having a film-forming temperature of 40.degree. C or higher, 0.5 to 50% of an organic solvent and 7 to 60% of water, based on the weight of the ink composition (hereinafter referred to as "composition I").
Our research revealed that the ink compositions which contain pigment particles coated with a resin having a specific film-forming temperature can also sufficiently mitigate the problems of conventional erasable inks. According to the present invention, there are also provided the following ink compositions:
(2) an ink composition erasable with a rubber eraser, the composition comprising 2 to 90% of a pigment coated with a resin having a film-forming temperature of 40.degree. C or higher, 0.5 to 30% of an organic solvent and 0.5 to 30% of water, based on the weight of the ink composition (hereinafter referred to as "composition II"), and
(3) an ink composition erasable with a rubber eraser, the composition comprising 2 to 90% of a pigment coated with a resin having a film-forming temperature of 0.degree. C or higher, 1.5 to 55% of an emulsion (calculated as solids), 0.5 to 30% of an organic solvent and 4.0 to 60% of water, based on the weight of the ink composition (hereinafter referred to as "composition III").
The term "minimum film-forming temperature" (or "MFT") used herein refers to a minimum temperature for forming a coating film from an emulsion, namely a threshold temperature above which a film can be formed but below which a film can not be formed.
The compositions I, II and III will be described below in detail.
1. Composition I
Pigments useful for the erasable composition I of the invention are not specifically limited. Pigments commonly employed for writing inks are usable singly or at least two of them can be used in mixture. Examples of usable pigments are shown below according to the color index (C.I.) number.


Inorganic pigment



Organic pigment

The resin component for the erasable ink composition I of the invention is selected for use from acrylic resins, acryl-styrene copolymer resins, ethylene-vinyl acetate-vinyl chloride copolymer resins, acryl-vinyl acetate copolymer resins, carboxylated butadiene-styrene rubber, styrene resins and the like which have a film-forming temperature of 40.degree. C. or higher. Preferred resins have a film-forming temperature of 50.degree. C. or higher. The resins with a film-forming temperature of lower than 40.degree. C. partially form a resin film even at room temperature

REFERENCES:
patent: 3458804 (1969-07-01), Wolf et al.
patent: 3925094 (1975-12-01), Papenfuss et al.
patent: 3925096 (1975-12-01), Karkov
patent: 4014844 (1977-03-01), Vidal et al.
patent: 4036652 (1977-07-01), Rothmayer
patent: 4235768 (1980-11-01), Ritter et al.
patent: 4365035 (1982-12-01), Zabiak
patent: 4525216 (1985-06-01), Nakanishi
patent: 4530961 (1985-07-01), Nguyen et al.
patent: 4636258 (1987-01-01), Hayashi et al.
patent: 4665107 (1987-05-01), Micale
patent: 4680058 (1987-07-01), Shimizu et al.
patent: 4687789 (1987-08-01), Gonnett et al.
patent: 4713411 (1987-12-01), Kanou et al.
patent: 4833197 (1989-05-01), Schelhaas et al.

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