Record receiver having plural interactive leaves or a colorless – Having a colorless color-former – developer therefor – or... – Method of use – kit – or combined with marking instrument or...
Reexamination Certificate
1999-04-06
2002-01-01
Hess, Bruce H. (Department: 1774)
Record receiver having plural interactive leaves or a colorless
Having a colorless color-former, developer therefor, or...
Method of use, kit, or combined with marking instrument or...
C503S200000, C503S216000, C503S226000
Reexamination Certificate
active
06335306
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a thermosensitive recording material of heat fixing type. In particular, the present invention relates to a thermosensitive recording material which, after the thermal printing, is heated to reduce the coloring capability of the unprinted part, so that the contrast between the printed parts and the unprinted parts is kept even when the recording material is then heated at a high temperature, thereby making the reading of the printed images possible.
Conventional thermosensitive recording materials comprise a substrate such as a paper sheet, synthetic paper sheet, or plastic film and a thermosensitive color image-forming layer formed on the surface of the substrate and mainly comprising a coloring substance such as an electron-donative leuco dye, and a color developing substance such as an organic acidic substance, e. g., an electron-accepting phenolic compound. A recording image can be formed by melting and reacting the coloring components by the thermal energy. These thermosensitive recording materials are disclosed in Japanese Patent Publication for Opposition Purpose (hereinafter referred to as “J. P. KOKOKU) Nos. Sho 43-4160, 45-14039 and 48-27736, and are widely employed in practice.
Since the thermosensitive recording materials are advantageous in that the recording apparatus is of compact size, has a relatively low price, and can be easily maintained, they are widely used as information-recording materials for recording outputs of printers used with, for example, computers, facsimile machines, automatic ticket-vending machines, scientific measurement recorders and CRT medical measurement recorders.
However, the thermosensitive recording materials have two serious defects. One of them is that in the conventional dye-forming type thermosensitive recording material in which the thermosensitive color image-forming layer comprises a coloring dye, a color-developing agent and a binder and is formed on a support by coating, the printed images fade or disappear when the printed thermosensitive recording material is kept for a long period of time because the coloring reaction is essentially reversible. This is a problem of the reliability of the printed images. This fading of the printed images is accelerated by exposure to light, high humidity and high temperature atmosphere (no resistance to the environments), and is specifically promoted by contact with chemical substances of the common use such as plasticizers and oils, to such an extent that the faded images cannot be recognized.
Various techniques were developed for the purpose of overcoming this defect. As a technique connected with the present invention, a process wherein a sulfonylurea developer is used as disclosed in Japanese Patent Unexamined Published Application (hereinafter referred to as “J. P. KOKAI”) Nos. Hei 5-147357, 5-148220, 5-32061, etc. is particularly effective. The effects of this compound are widely recognized, and the compound is used for thermosensitive recording materials of which a high print legibility is requested.
Another defect of the thermosensitive recording materials is that after recording information, the unprinted parts of the thermosensitive recording materials can be still color image-forming by heating or, in other words, the unprinted parts are not yet fixed. Therefore, even when the reliability and storability of the printed images are improved as described above, the unprinted parts on the white papers are colored to make the recognition of the printed images impossible. A term “reheating” herein indicates an unwilling heating conducted after the recording, and a term “re-coloring” indicates the coloring of the white part of the paper by the reheating.
The reheating might be caused in the daily life by ironing or heating with a microwave oven, or it may be caused by mistake with fires of cigarettes, matches or lighters. The application of the thermal energy to form the printed images with a thermosensitive recording machine intentionally or by mistake is also included by the reheating.
The process for preventing the re-coloring is usually called “fixing”. Also in the present invention, the term “fixing” indicates a process conducted for the purpose of preventing the re-coloring.
The fixing is considerably difficult because of the nature of the coloring reaction. The techniques proposed so far regarding this act were as follows: It was tried at first to use an azo compound for the coloring (J. P. Kokai Nos. Sho 61-40192, Sho 63-128981 and Hei 7-88356). In this technique, the fixing is conducted by irradiation with light, taking advantage of a phenomenon that the azo compound is decomposed by the irradiation with light to lose its coupling function. Although this method is advantageous in that the re-coloring of the white paper can be almost completely inhibited after the fixing, considerable care should be taken to prepare the micro capsules the azo compound because azo compound is basically easily decomposed. Further, there is another defect in that the coloring of the azo compound, in particular, the black coloring, of the azo compound tends to be insufficient so that it tends to make the contrast of the printed images vague. Still other defects are that since a photo-fixing method is employed in this system, an UV curable ink cannot be used for the printing and that considerable care should be taken to protect the paper from light before printing. Further, a light source of a very high illuminance is necessitated for the photo-fixing method and, as a result, it becomes difficult to achieve the characteristics of the thermosensitive system such as the reduction in size of the apparatus and freeness from the maintenance. Another problem is that since the thermal fixing method takes a considerable period of time, the total printing speed cannot be easily increased.
In a recently disclosed technique, a combination of an imino compound and an isocyanate compound is used as a base for the coloring, or a combination of an amino compound and an aromatic isocyanate compound is used therefor, and the isocyanate compound in the unprinted parts of the paper is inactivated by heating (J. P. KOKAI Nos. Hei 7-214900 and 8-80668).
These methods are epochal in that the fixing is conducted by heating after the printing. However, according to the contents disclosed therein, the thermosensitive paper must be kept at a high temperature of 100° C. or above for at least several minutes to cause a defect that the total printing velocity is very low. In addition, when the combination of the imino compound and the isocyanate compound is used, the tone of color is limited, and it is thus difficult to color and to fix printed images of various colors.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a thermosensitive recording material of heat fixing type, which has an excellent fixing property and particularly an excellent legibility of colored images after the reheating and which can be fixed by an easy method by solving the above-described problems.
The present inventors have made intensive studies in order to solve the above problems, and have found that, by using the specific color developer in the thermosensitive color image-forming layer and a color developability reducing substance in the subbing layer, the above problems can be solved. The present invention has been completed based on this finding.
Therefore, the present invention relates to a thermosensitive recording material comprising, on a sheet substrate, a subbing layer and a thermosensitive color image-forming layer in this order, said thermosensitive color image-forming layer comprising a colorless or light-colored dye precursor and a color-developer which reacts with said dye precursor to color said precursor when said color-developer is heated, said color-developer is selected such that the color image formed has a high solvent resistance after the coloring, and said subbing layer comprising a color developability reducing substance capable of reducing
Segawa Takako
Takahashi Yoshiyuki
Hess Bruce H.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Oji Paper Co. Ltd.
LandOfFree
Thermosensitive recording material of heat fixing type and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Thermosensitive recording material of heat fixing type and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thermosensitive recording material of heat fixing type and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2875592