Record receiver having plural interactive leaves or a colorless – Having a colorless color-former – developer therefor – or... – Identified organic electron acceptor other than phenolic resin
Reexamination Certificate
2000-04-12
2002-05-28
Hess, Bruce H. (Department: 1774)
Record receiver having plural interactive leaves or a colorless
Having a colorless color-former, developer therefor, or...
Identified organic electron acceptor other than phenolic resin
C106S031170, C503S225000
Reexamination Certificate
active
06395680
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a composition comprising aromatic carboxylic acid compounds that is capable of effectively serving as a color developer, and a thermosensitive recording material comprising the above-mentioned composition.
2. Discussion of Background
Generally, a thermosensitive recording material comprises a support and a thermosensitive coloring layer formed thereon, which comprises as the main components a colorless or light colored electron-donating dye precursor, and an electron-accepting color developer. These dye precursor and color developer are caused to react instantaneously upon the application of heat thereto to produce recorded images, for instance, using a thermal head, heat pen or laser beam, as disclosed in Japanese Patent Publications 43-4160 and 45-14039.
A thermosensitive recording material is used in a wide variety of fields, for example, as the recording material for an electronic computer, facsimile machine, ticket vending machine, label printer, and recorder because it has the advantages that recording can be achieved using a relatively simple apparatus, maintenance is simple, and there is no noise development.
The above-mentioned thermosensitive recording material employing such an electron-donating dye precursor and an electron-accepting color developer has excellent characteristics such as good appearance and nice touch and is capable of producing images with high coloring density. On the other hand, such a recording material has the disadvantage that the preservation stability of the recorded images is poor. To be more specific, when image areas formed in the thermosensitive recording material come in contact with plastics such as polyvinyl chloride, the image areas are decolorized by the influence of a plasticizer and other additives contained in the plastics. When the colored image areas come in contact with chemicals contained in foods or cosmetics, such image areas are also easily decolorized or the background area easily causes color development.
To improve the preservation stability of the image recorded in the thermosensitive recording material, various color developers with high reliability are conventionally proposed. For instance, the use of a phenolsulfone compound as the color developer is disclosed in Japanese Laid-Open Patent Applications 58-82788 and 60-13852; and the use of a substituted salicylic acid compound, disclosed in Japanese Laid-Open Patent Application 62-169681. However, even though the aforementioned compounds are used as the color developers, the image area formed in the thermosensitive recording material shows still insufficient fastness to plasticizers.
SUMMARY OF THE INVENTION
It is therefore a first object of the present invention to provide a color developer capable of producing colored image areas with improved preservation stability, particularly, in terms of the plasticizer resistance and the oil resistance of the produced image.
A second object of the present invention is to provide a thermosensitive recording material comprising the above-mentioned color developer.
The first object of the present invention can be achieved by a composition comprising at least two aromatic carboxylic acid compounds selected from the group consisting of aromatic carboxylic acid compounds of formulas (I), (II) and (III):
wherein X represents carbonyl group; sulfonyl group; a bivalent group derived from an aliphatic hydrocarbon; a bivalent group derived from an aliphatic hydrocarbon comprising in the main chain thereof at least one hetero atom, carbonyl group, sulfonyl group, an ester linkage, or an aromatic ring; or a bivalent group derived from an aromatic hydrocarbons compound prepared by connecting two aromatic hydrocarbons via at least one hetero atom, carbonyl group, sulfonyl group, an ester linkage, an alkylene, or an aliphatic hydrocarbon comprising a hetero atom in the main chain thereof.
In the formulas (I) to (III), it is preferable that the bivalent functional group represented by X have the following formula (IV):
wherein R and R′ which may be the same or different are each a hydrogen atom, a halogen atom, an alkyl group having 1 to 8 carbon atoms, an aralkyl group having 1 to 8 carbon atoms, or an aryl group having 1 to 8 carbon atoms; n is an integer of 1 to 4; m is an integer of 0 or 1; and A and B are each carbonyl group, sulfonyl group, a bivalent group derived from an aliphatic hydrocarbon, a bivalent group derived from an aliphatic hydrocarbon comprising in the main chain thereof at least one hetero atom, carbonyl group, sulfonyl group, an ester linkage, or an aromatic ring, or a bivalent group derived from an aromatic hydrocarbon compound prepared by connecting two aromatic hydrocarbons via at least one hetero atom, carbonyl group, sulfonyl group, an ester linkage, an alkylene, or an aliphatic hydrocarbon comprising a hetero atom in the main chain thereof.
Furthermore, it is preferable that the bivalent functional group represented by B in formula (IV) be sulfonyl group.
In addition, it is preferable that the bivalent functional group represented by X in formulas (I) to (III) be derived from a bivalent group selected from the group consisting of an alkylene, oxyalkylene, thioalkylene, sulfinylalkylene, and sulfonylalkylene, each having 1 to 16 carbon atoms.
The above-mentioned second object of the present invention can be achieved by a thermosensitive recording material comprising a support and a thermosensitive coloring layer formed thereon comprising a leuco dye and a color developer capable of inducing color formation in the leuco dye upon application of heat thereto, with the color developer comprising a composition comprising at least two aromatic carboxylic acid compounds selected from the group consisting of aromatic carboxylic acid compounds of the previously mentioned formulas (I), (II) and (III).
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The composition according to the present invention comprises at least two aromatic carboxylic acid compounds selected from the group consisting of aromatic carboxylic acid compounds represented by the aforementioned formulas (I), (II) and (III).
The reasons why the above-mentioned composition of the aromatic carboxylic acid compounds can impart high plasticizer resistance and oil resistance to the colored images formed in the thermosensitive recording material have not yet been clarified, but are considered to be as follows:
(1) The composition of the present invention is provided with excellent color developing capability because the aromatic carboxylic acid compound of formula (I), (II) or (III) contained in the composition is a strong acid having an electron attractive group as the substituent.
(2) The solubility of the aforementioned composition in nonvolatile solvents such as oils and plasticizers can be lowered. This is because the molecular weight of each aromatic carboxylic acid compound is increased by including two or more aromatic carboxylic acids in the molecule thereof.
The composition comprising at least two aromatic carboxylic acid compounds according to the present invention is novel. This composition can be obtained by esterification reaction between a trimellitic acid anhydride and an alcohol compound, for example, in accordance with the following reaction scheme:
More specifically, the composition of the present invention is obtained in the form of a mixture of at least two aromatic carboxylic acid compounds with carboxyl groups being substituted at different positions, that is, isomers, through the above-mentioned reaction. Namely, there can be obtained a composition comprising the aromatic carboxylic acid compounds of formulas (I) and (II); a composition comprising the aromatic carboxylic acid compounds of formulas (II) and (III); a composition comprising the aromatic carboxylic acid compounds of formulas (I) and (III); and a composition comprising the aromatic carboxylic acid compounds of formulas (I), (II) and (III). Any of the above-mentioned compositions can be used a
Hayakawa Kunio
Kameoka Ikuo
Morita Mitsunobu
Yang Xiaonan
Cooper & Dunham LLP
Hess Bruce H.
Ricoh & Company, Ltd.
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