Record receiver having plural interactive leaves or a colorless – Having a colorless color-former – developer therefor – or... – Having nonchromogenic liquid spread-control or...
Reexamination Certificate
1999-10-15
2002-08-27
Hess, Bruce H. (Department: 1774)
Record receiver having plural interactive leaves or a colorless
Having a colorless color-former, developer therefor, or...
Having nonchromogenic liquid spread-control or...
C503S226000
Reexamination Certificate
active
06440897
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a thermally sensitive recording medium which uses benzoxazinone compound as an ultraviolet ray absorbing agent.
DESCRIPTION OF THE PRIOR ART
Generally, in a thermally sensitive recording method, a recording image is obtained by following procedure. A thermally sensitive layer mainly composed by colorless or pale colored dye precursor which is ordinarily an electron donating compound and a color developer which is an electron accepting compound is prepared on a substrate, and a recording image is developed by an instantaneous chemical reaction caused by heating said layer using a thermal head, a thermal pen or a laser beam. And these techniques are disclosed in Japanese Patent Publication 43-4160 and in Japanese Patent Publication 45-14039. These thermally sensitive recording media do not need procedures for development and fixing, and very clear image can be obtained by a simple apparatus. And, the apparatus is not only relatively cheap and compact, but also has merits of easy maintenance and does not generate noise, and, therefore, is widely used to a measuring recorder, a thermal printer of computer, a facsimile, an automatic ticket vendor or a bar cord labeler.
As an use of this thermally sensitive recording media, recently the use for an indication media such as an indicating label or a poster is becoming more popular. However, this kind of thermally sensitive recording media does not have good stability against light and heat. Therefore, when the thermally sensitive recording media is exposed to indoor light or sun light, or kept at higher temperature for long term, the ground color changes to yellowish color and the appearance is deteriorated, further the stability of the recorded medium is spoiled. Consequently the qualitative image of the thermally sensitive recording medium is affected.
To prevent the ground color from changing into yellowish color, various methods which add fine ground particles of an ultra violet ray absorbing agent to a color developing layer or to a protecting layer are published (for example, Japanese Patent Laid Open Publication 50-104650, Japanese Patent Laid Open Publication 55-55891, Japanese Patent Laid Open Publication 55-93492 and Japanese Patent Laid Open Publication 58-87093). However, in a case of this method which obtains sufficient light resistance by adding fine ground particles of an ultra violet ray absorbing agent to the thermally sensitive recording layer, it is necessary to add large amount of fine ground particles of an ultra violet ray absorbing agent, because the ultra violet ray absorbing efficiency of and the shading efficiency of it are poor. When this kind of thermally sensitive recording medium is kept under the high temperature condition, the new problems such as a background fogging or deterioration of recorded density is caused, and the property as the thermally sensitive recording medium is spoiled.
Further, when fine ground particles of ultra violet ray absorbing agent is contained in a protecting layer, and if the ultra violet ray absorbing agents are conventional type, these agents have low melting point and can be easily molten by the heat of the thermal head, and cause the problem of fine refuse or sticking which spoil the thermal head by long term printing. Furthermore, the ultra violet ray absorbing agent is extracted from the protecting layer by the effect of plasticizer or oil, and consequently, the preserving ability of the recorded image is deteriorated.
In Japanese Patent 61-57198, a method to add an ultra violet ray absorbing agent which is made water soluble by introducing sodium sulfonate group to the thermally sensitive recording layer and/or protecting layer is proposed. However, this method not only has a problem affecting pH or fluidity of solution at the production, but also causes problems of ground color developing and the thermal head spoiling. This method can not be said as a practical method.
Further, the method to obtain a thermally sensitive recording medium which has good preserving stability and light resistance by containing micro capsules of ultra violet ray absorbing agent is disclosed in Japanese Patent Laid Open Publication 5-155134. However, in this method, the preparation of micro capsule in which fine particles of ultra violet ray absorbing agent are immobilized is necessary, and to improve the absorbing efficiency of ultra violet ray, it is necessary to make the size of micro capsule smaller, however, the size of micro capsule is restricted by the preparation method. Therefore, for the generation of sufficient light resistance, the necessary amount of the micro capsules that contain ultra violet ray absorber is increased and the cost of the thermally sensitive recording raises. Further, since the micro capsule in which ultra violet absorbing agent is immobilized is necessary to be stabilized to heat and pressure, the wall thickness of micro capsule must be thicker, and it is a ground of cost raising.
Recently, a thermally sensitive recording medium which uses an ultra violet absorbing agent prepared by polymerization of benzotriazol molecule or benzophenone molecule which has an ultra violet ray absorbing ability, is proposed in Japanese Patent Laid Open Publication 7-314894, Japanese Patent Laid Open Publication 9-221487, Japanese Patent Laid Open Publication 9-268183, Japanese Patent Laid Open Publication 9-314496, Japanese Patent Laid Open Publication 10-71770 and Japanese Patent Laid Open Publication 10-36371. But, the improvement effect for refuse and sticking by use of the compounds disclosed in these documents is not sufficient.
As mentioned above, the method to provide a light resistance to a thermally sensitive recording medium by an ultra violet absorbing agent has been carried out for long time, however, a sufficient method is not yet developed.
BRIEF SUMMARY OF THE INVENTION
The object of the invention is to provide a thermally sensitive recording medium which has a good light resistance at the recording part and the ground part, a good runnability, further, which is good at image preservation ability concretely resistance to plasticizer, oil or solvent, without spoiling basic property of thermally sensitive recording medium.
The inventors of the present invention have conducted an intensive study and have found that the thermally sensitive recording medium which has a good resistance to light of recording part and a good resistance to yellowish color change of ground part can be obtained by using benzoxazinone compound represented by following general formula (1) as an ultra violet ray absorbing agent to a thermally sensitive recording medium which applies color developing reaction between electron donating compound and electron accepting compound.
In the formula, R represents hydrogen atom, hydroxyl group, alkyl group of carbon number 1-8, alkoxy group of carbon number 1-6, acyl group of carbon number 1-6, acyloxy group of carbon number 1-6, alkoxy carbonyl group of carbon number 1-6, carboxyl group, halogen atom or nitro group. Especially, hydrogen atom, hydroxyl group, alkyl group of carbon number 1-4, alkoxy group of carbon number 1-4, acyl group of carbon number 1-4, alkoxy carbonyl group of carbon number 1-4 or halogen atom are desirable. X represents a divalent group or a direct bond, and desirably is an aromatic hydro carbon of carbon number 6-12.
Additionally, the inventors of this invention have found that the following problems which occur when conventional ultra violet ray absorbing agent is used can be prevented by use of benzoxadinone compound of this invention. That is, the ground color imperfection when blended in the recording layer, the deterioration of running recording ability by the generation of refuse and sticking when blended in the protecting layer and the deterioration of resistance to plasticizer or oil can be prevented.
The benzoxadinone compound of this invention is not easily molten by heating with a thermal sensitive head, because the compound has a high melting point. There
Date Takashi
Ohashi Reiji
Ryu Yukiko
Hess Bruce H.
Nippon Paper Industries Co Ltd
Sherman & Shalloway
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