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
2000-10-31
2002-06-18
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...
C503S216000, C503S221000
Reexamination Certificate
active
06407036
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thermal recording material that has good color developing sensitivity, good resistance to heat and good ground color and not generate powder, further has an excellent image retention.
2. Description of the Prior Art
In general, a thermal recording material having a thermally sensitive color developing layer mainly composed of colorless or pale colored dye precursor and color developing agent that develops color by reacting with said dye precursor when heated is disclosed in Japanese patent publication 45-14039 and widely used in commercial scale. A thermal printer in which a thermal head is installed is used for the recording method of said thermal recording material. Since this kind of thermal recording method superiors to the conventional recording method from the view point of noiseless at recording process, does not need developing and fixing processes, maintenance free, equipment is relatively cheap and compact and the obtained image is very clear, therefore, this method is widely applied in the field of facsimile or computer, various kinds of measuring instrument and for a labeling machine along with the growth of an information industry. The recording devices attached to these instruments are becoming more diversified and more high-performance, and the required quality to the thermal recording material is becoming more severe. Along with the miniaturization of an instrument and requirement for higher recording speed, it becomes necessary to obtain deep and clear color developing image.
For the purpose to meet the requirement, for example, in the Japanese Patent Laid open Publication 56-169087, a method to improve the color developing sensitivity by adding a thermo fusion substance to a thermally sensitive layer is disclosed, and in the Japanese Patent Laid Open Publication 56-144193, a method to improve the color developing sensitivity by using new color developing agent which has high color developing ability is disclosed. However, these methods can not be said to have a sufficient quality, because these methods have defects such as deterioration of ground color by heat, powder generation by aging and dropping of color density after preserved for long time (reprinting ability). Further, the method to use dye, color developing agent together with adequate sensitizer can be used. For example, in a case that the color developing agent is a phenol type compound represented by bisphenol A, p-benzylbiphenyl (Japanese Patent Laid Open Publication 60-82382), p-benzyloxybenzoicbenzyl(Japanese Patent Laid Open Publication 57-201691) or benzylnaphthyleter (Japanese Patent Laid Open Publication 58-87094) can be used as an adequate sensitizer. When a sensitizer is used, the sensitizer is fused in the first place and the fused sensitizer dissolves dye and color developing agent and are mixed by molecular size level so as to cause the color developing reaction, therefore, the selection of the kind of sensitizer, dye and color developing agent is very important.
Dihydroxydiphenylsulfone compound, which is used as an organic color developing agent is a well-known conventional compound, however, the color developing ability of it is too poor to meet the current requirement for high sensitivity. As the method to improve the color developing sensitivity, in Japanese Patent Laid Open Publication 4-69283, a method to add di(p-methylbenzyl)oxalate is disclosed and in Japanese Patent Laid Open Publication 8-67070, a method to add solid solution composed of two types of oxalic acid ester derivatives is disclosed. By said methods, the color developing sensitivity can be improved more or less, however, from the view points of powder generation and image preservation by aging, these methods can not be said as a sufficient ones. As mentioned above, by the conventional thermal sensitive recording medium, it is difficult to meet the current requirement to improve color developing sensitivity, further, is also difficult to meet the other requirements for quality such as to have good heat resistance of ground color, and excellent image preservative stability.
DISCLOSURE OF THE INVENTION
The object of this invention is to provide a thermal recording material which has good color developing sensitivity, strong heat resistance, excellent ground color and does not generate powder, further has excellent image retention.
The inventors of this invention have conduced an intensive study and have found that in a thermal recording material which possesses a thermally sensitive color developing layer containing colorless or pale colored basic dye and an organic color developing agent as main components, the thermal recording material which contains at least one kind of dihydroxydiphenylsulfone type compound represented by following general formula (1) as an organic color developing agent and containing at least one kind of saturated fatty acid monoamide represented by following general formula (2) can solve the above mentioned problems, and accomplished the present invention.
(in this formula, R
1
and R
2
is an alkyl group or an alkyl group of carbon number 1-8, or a halogen atom and a and b is an integer number of 0-3)
R
3
—CONH
2
(2)
(in this formula, R
3
is an alkyl group of carbon number 11-21)
In general, it is concerned that the velocity of dissolution and diffusion or solubility of the dye into the melted color developing agent give the important effects to the color developing sensitivity of thermal recording material. To improve said effects, the method to add various kinds of material as a sensitizer is carried out. It is concerned that the addition of sensitizer causes several effects such as falling down of melting point, falling down of activated energy, change of polarity, improvement of solubility between each materials, and the velocity for fusing, dissolving and diffusion and saturated solubility are improved. Thus the color developing sensitivity of the thermal recording material can be improved.
In general, waxes containing saturated fatty acid monoamide are widely known as the sensitizer. However, this invention has been accomplished by finding out that the thermal recording material whose color developing sensitivity is improved, has a strong heat resistance and does not generate powder, further has an excellent image retention can be obtained by containing dihydroxydiphenylsulfone compound as an organic color developing agent and containing saturated fatty acid monoamide by the specific limit, that is, 1.5-5 parts to 1 part of dihydroxydiphenylsulfone compound.
Generally, if waxes or a sensitizer are used by large amount to improve the color developing sensitivity, the color developing sensitivity can be improved, however, other problems such as deterioration of heat resistance of ground color or generation of powder occurs. Therefore, the amount of sensitizer is usually 1 part to 1 part of color developing agent. In the meanwhile, the inventors of this invention have found that the use of saturated fatty acid monoamide as a sensitizer can solve said problem. Namely, in this case, even if the amount of saturated fatty acid monoamide to dihydroxydiphenylsulfone compound is bigger than usual, the heat resistance or powder generation are not deteriorated, and high color developing sensitivity can be obtained. The reason why is not clear, however, it is concerned that by the use of saturated fatty acid monoamide the mutual solubility between dye, color developing agent and sensitizer becomes good and color developing sensitivity is improved, and since the remarkable falling down of melting point does not occur, the deterioration of heat resistance is very small. Further, since the saturated fatty acid monoamide is not a sublimate substance, the developed image formed by the reacted product by dye, color developing agent and sensitizer can be stably preserved.
When diphenylsulfone derivatives represented by following general formula (3) is added besides dihydroxydiphenylsulfone compound as a
Hamada Kaoru
Kimura Yoshihide
Midorikawa Yoshimi
Sekine Tomoniri
Sumikawa Naomi
Hess Bruce H.
Nippon Paper Industries Co. Ltd
Sherman & Shalloway
LandOfFree
Thermal recording material does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Thermal recording material, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thermal recording material will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2905023