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
2000-06-09
2003-06-24
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...
C503S208000, C503S216000
Reexamination Certificate
active
06583086
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thermally sensitive recording medium that has an excellent color developing ability, and is superior to the existing one in the preservability of developed color image and the stability of blank part.
2. Description of the Prior Art
Generally, a thermally sensitive recording medium can be obtained by spreading a coating, on a substrate such as paper, synthetic paper or plastic which is prepared by the preparation method mentioned below, and develops color record by instant chemical reaction with heating by a thermal head, a hot stamp, laser beam and others. Namely, a colorless or pale colored dye precursor, which is an electron donating compound, and a color developer, which is an electron accepting compound, are separately ground to fine particles and mixed together, then additives such as a binder, a filler, a sensitizer or a slipping agent are added, and the coating is obtained. The thermally sensitive recording media are widely applied in various fields such as a recorder for measuring equipment, a terminal printer of computer, a facsimile, an automatic ticket vending machine and a bar cord label. Recently, along with the diversity of recording equipments and the progress of high quality machines, the high speed printing and high speed image recording become possible, and more excellent quality is required to the recording sensitivity of thermally recording medium.
As a method to satisfy the said requirement, the method to use a sensitizer with a dye and a color developer is proposed. For example, in a case that the color developers are phenolic compounds represented by bis-phenol A, p-benzyl biphenyl (Japanese Patent Laid open Publication 60-82382), p-benzyl oxybenzoicbenzoate (Japanese Patent Laid open Publication 57-201691) and benzylnaphtyl ether (Japanese Patent Laid open Publication 58-87094) are used as the desirable sensitizers. When a sensitizer is used, at first, the sensitizer is molten by heating and the molten sensitizer dissolves basic dye and color developer and mixes them by molecular size level, and the color developing reaction occurs. Therefore, the kind of sensitizer, basic dye and color developer to be used must be chosen by careful consideration
In Japanese Patent Publication 4-38599, a thermally sensitive recording medium prepared by combining aromatic ether as a sensitizer to a color developer 4-hydroxy-4′-methyldiphenylsulfone is proposed, and also in Japanese Patent Publication 4-38599, a thermally sensitive recording medium prepared by combining 1,4 substituted naphthalene derivatives as a sensitizer to a color developer 4hydroxy-4′-methyldiphenylsulfone is proposed. The thermally sensitive recording media obtained by mentioned combination can achieve a good color developing sensitivity by higher impressive energy, however, when printed by lower impressive energy or by high speed, a sufficient color developing sensitivity can not be obtained, and the application to an equipment by the said printing condition is impossible. Further, in general, when the color developing sensitivity is improved by adding sensitizer, the occurrence of the problem that the heat resistance of blank part deteriorates, is pointed out.
BRIEF SUMMARY OF THE INVENTION
The object of this invention is to provide a thermally sensitive recording medium that has high color developing sensitivity at lower impressive energy printing and whose image preservation of printed part and the stability of background color of blank part (against to humidity and heat) are improved.
The present invention is to provide a thermally sensitive material in which a compound represented by following general formula (1) as a color developer and diphenylsulfone compound represented by following general formula (2) or an aromatic compound possessing aminosulfonyl group (—SO
2
NH
2
) represented by general formula (3) as a sensitizer in a thermally sensitive color developing layer.
R
1
represents a hydrogen atom, a methyl group or a chlorine atom, R
2
and R
3
represent a methyl group, an alkoxy group or an allyloxy group, m and n represent an integer of 1-5, R
4
represents an alkyl group, an alkoxy group of carbon number 1-6 or an electron withdrawing group and o represents an integer of 0-2.
In the present invention, at least one kind of compound represented by general formula (1) is used as a color developer. In a case when R
1
is a methyl group, heat resistance of blank part is improved, and in a case of a hydrogen atom, color developing sensibility is improved. From the view point of preservability, R
1
is desirable to be located at p position to a sulfone group.
Further, in the present invention, at least one kind of compound represented by general formula (2) or general formula (3) is used as a sensitizer. In general formula (2), R
2
and R
3
can be a hydrogen atom or a substituted group that does not spoil the sensitizer effect, and as the concrete example, methyl group, alkoxy group of carbon number 1-6 or allyloxy group can be mentioned. In general formula (3), R
4
can be a substitution group that does not spoil the sensitizer effect, and as the concrete example, alkyl or alkoxy group of carbon number 1-6 such as methyl group, ethyl group or electron withdrawing group such as chlorine atom or nitro group can be mentioned.
As the concrete compounds represented by general formula (2), compounds (2-1)-(2-11) can be mentioned, however, the examples are not limited to them. Among these compounds, a compound of (2-1) is desirably used because when it is used with 4-hydroxy-4′-methyldiphenylsulfone, which is a color developer, the effect becomes better.
The concrete examples of compound represented by general formula (3), compounds (3-1)-(3-30) can be mentioned, however, the examples are not limited to these compounds. Among these compounds, (3-2) and (3-4) can be desirably used, because when compound (1) is used as a color developer, the said two compounds can give a good sensitizing effect.
In the present invention, if the content of the sensitizer represented by general formula (2) or (3) is too small, the sensitizing effect is not enough, and if it is too much, the color developing density becomes poor. In the present invention, the desirable content of the sensitizer represented by general formula (2) or (3) is 0.01-5 parts to 1 part of color developer, and more desirably, 0.01-2 parts.
DETAILED DESCRIPTION OF THE INVENTION
For the preparation of the thermally sensitive recording medium of this invention, well known conventional method can be used. Concretely, following method can be used. Namely, color developer, dye precursor and sensitizer is separately ground to fine particles by means of a grinder such as ball mill, attreiter or sand grinder or by means of an adequate emulsifying apparatus, fillers and other kinds of additive are added, then dispersed in aqueous solution of water soluble binder so as to obtain a coating. The obtained coating is coated over the surface of voluntary substrate using various kinds of coater such as air knife coater, blade coater or roll coater.
As the thermally sensitive recording method utilizing color developing reaction between an electron donating compound and an electron accepting compound in this invention, combination of dye precursor and color developing agent, diazonium salt and coupler, transition element such as iron and chelete compound or aromatic isocyanate compound and imino compound can be mentioned. From the view point of color density and recording sensitivity, the thermally sensitive recording medium that utilize the color developing reaction between dye precursor and color developer is illustrated in detail as follows, because the combination of a dye precursor and a color developer developing gives better result,.
As a dye precursor used in this invention, various kinds of well known compounds can be used. These compounds can be used alone or by mixing two kinds or more, and are selected according to the uses or required c
Nakano Tomoyuki
Ohashi Reiji
Yoneshige Seiki
Hess Bruce H.
Nippon Paper Industries Co. Ltd.
Sherman & Shalloway
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