CA1312730C - Thermal recording material - Google Patents
Thermal recording materialInfo
- Publication number
- CA1312730C CA1312730C CA000587318A CA587318A CA1312730C CA 1312730 C CA1312730 C CA 1312730C CA 000587318 A CA000587318 A CA 000587318A CA 587318 A CA587318 A CA 587318A CA 1312730 C CA1312730 C CA 1312730C
- Authority
- CA
- Canada
- Prior art keywords
- thermal recording
- methyl
- hydroxy
- recording material
- butane
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
- B41M5/00—Duplicating or marking methods; Sheet materials for use therein
- B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
- B41M5/30—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using chemical colour formers
- B41M5/337—Additives; Binders
- B41M5/3375—Non-macromolecular compounds
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Heat Sensitive Colour Forming Recording (AREA)
Abstract
THERMAL RECORDING MATERIAL
ABSTRACT OF THE DISCLOSURE:
A thermal recording material having a thermal record-ing layer that utilizes a color forming reaction between at least one basic dye and a color developing agent capable of forming color in contact with said basic dye, said thermal recording layer containing a dihydroxydiphenyl ether of the formula:
ABSTRACT OF THE DISCLOSURE:
A thermal recording material having a thermal record-ing layer that utilizes a color forming reaction between at least one basic dye and a color developing agent capable of forming color in contact with said basic dye, said thermal recording layer containing a dihydroxydiphenyl ether of the formula:
Description
~312~3~
THERMAL RECORDING MATERIAL
The present invention relates to a thermal recording material. More particularly, the present invention relates to a -thermal recording material that is improved in color forming ability and other recording characteristics and which features a high degree of brightness and better image stability.
Various types of thermal recording materials have been proposed that utllize the thermal color-~orming reac-tion be~ween at least one colorless or pale-colored basic dye and color developing agents such as phenols and organic acids (see Japanese Patent Publication No. 45-1~039) and some of them are in extensive cvmmercial use. Applications of these thermal recording materials cover a wide range including recorders for measurements, terminal printers o~
computers and information communications systems, facsimiles and automatic ticket vending machines. These recording apparatus have heating elements such as thermal heads and heat pens (styli), which are heated to produce imagewise color -formation. With the recent increase in the versa-tility of the use o-f thermal recording equipment and improvement of their performance, the requirements for the quality of thermal recording paper have become increasingly rigorous. For instance, recording on a sheet of A4-size (210 mm x 297 mm) with modern facsimiles has become possible within one minute, although several minutes were required previously. Under these circumstances, several me~hods including the addition of sensitizers have been proposed as techniques for improving the sensitivlty of thermal record-- ing paper. However, none of the methods so ~ar proposed have successfully attained a balance between the qualities required of thermal recording materials including sensi-tivity to color formation, the stability of color lmage and 35 recording adaptability.
In the thermal recording layer o-f thermal recording paper, both a color-forming material and a phenolic compound are dispersed as fine particles and it is generally held 13:127'~
that upon heating, one or both o~ the components wlll ~use and come in lntimate contact with each other to achieve color formatlon.
As a phenolic compound that is suitable for the purpose of color development, 2,2-bis(4'-hydroxyphenyl) propane (bisphenol A; m.p. 156C) has been extensively used for several reasons including low cost and high stability o-f quality (see. for example, U.S. Patent No. 3,539,375).
However, bisphenol A is slow in response to heat and has not been able to satisfy all of the requirements of the market -for higher sensitivity of thermal recording paper that are adjunct to the recent tendency ~or faster operation or reduction in size of thermal recording equipment. With a view to solving this problem, many sensitizers have been proposed, including waxes (Japanese Patent Public ~isclosure No. 48-19231), phthalic acid esters (Japanese Patent Public Disclosure Nos. 57-116690 and 58-98285), benzylphenyl ethér derivatives (Japanese Patent Public Disclosure No. 59-155096), benzylbiphenyl (Japanese Patent Public Disclosure No. 60-82382), naphtholic derivatives (Japanese Patent Public Disclosure No. 58-87094) and carbonic acid diesters (Japanese Patent Public Disclosure No. 58-136489).
However, combinations of these sensitizers with bisphenol A
have so far been unable to produce satis~actory quality in ~5 such aspects as the degree of brightness, sensitivity for color formation and fog resistance. If one employs low-melting point monophenols such as ~-naphthol (m.p. 95 -96C) and 4-tertiary butylphenol (m.p. 94 - 99C) with a view to improving sensitivity for color -formation, a strong "phenolic" smell results and the commercial acceptance of the recording paper is reduced. Japanese Patent Public Disclosure No. 56-144193 proposes the use of benzyl p-hydroxybenzoate or methylbenzyl p-hydroxybenzoate as a cvlor developing agent for increasing the sensitlvity of a thermal recording sheet. However, a problem with thls idea is that the recording sheet is poor in image stabilit~ since white spots will appear in the image area during storage of the record.
~ 3~273~
As described above, none o~ the prior art thermal recordlng materials have been capable o-f -Eully satlsfying the require~ents of the market for higher performance with regard to such aspects as color-forming characteristics, the degree of brightness and image stability. A need, there-fore, has existed for the development of a thermal recording material that has high sensitivity and high degree of brigh-tness and which features better image stability.
1~ An obJect of the present invention is to provide a thermal recording material which not only has a practlcal level of sensitivity for color -formation that guarantees its use in a wide range of' applications bu-t which also features a high degree of brightness.
Another obJect of the present invention is to provide a thermal recording material which has the added advantage of better lmage stability.
These ob~ects of the present invention can be attained by a thermal recording material that contains in 2~ a thermal recording layer at least one colorless or pale-colored basis dye and a dlhydroxydiphenyl ether represented by the following general ~ormula:
HO OH (I) With a view to eliminating the several problems of the prior art techniques, the present inventors conducted intensive studies by screening a number of phenolic color-developing materials. As a result, the present inventors found that the dihydroxydiphenyl ether represented bY the general formula set forth above is an effective color developing agent that ensures high sensitivity and high degree of brightness and which yet is free ~rom the problem of white spots that has occurred in the use of ben~yl p-hydroxybenzoate. The present inventlon has been accom-plished on the basis of this flnding.
The dihydroxydiphenyl ether having the general 13:L27~
~ormula set ~orth above may be exemplif~ed by 2,2'-dihydroxydiphenyl ether (m.p. 121C), 3,3'-dihydroxydlphenyl ether (m.p. 98C) and 4,4'-dihydroxydiphenyl ether (m.p.
166C).
The reason why the dih~droxydiphenyl ether used in the present invention attains a higher degree o~ brightness and a hlgher sensiti~ity -for color formation than the conventionally used bisphenol A is not completely clear but this would probably be due to the miscibility of this compound with basic dyes or sensitizers that may be used in combination with these compounds.
In the present invention, the dihydroxydiphenyl ether of formula (I) is normally used in an amount of 0.5 - 3 parts by weigh-t, pre~erably 1 - 2 parts by weightt per part by weight of the color-forming basic dye.
By incorporating this amount o~ dihydroxYdiphenY
ether in a thermal recording layer, a thermal recording material having a high degree of brightness and sensitivity for color formation is obtained and this recording material 20 per se is normally suitable for practical use. However, if the thermal paper, after application of heat, is left to stand for 24 hours in a hot atmosphere ~60C x ZO% R.H.) or in a humid atmosphere (40C x 90% R.H.~, the density of the image will decrease and the residual density may sometimes 25 be reduced to 80% and below. In order to avoid this problem, the thermal recording material of the present invention is often required to have better image stability.
To meet this need, the present inventors conducted further studies and found that a thermal recording material 30 that had better image stability without compromising the degree of brightnass and sensitivity could be attained by using a color developing agent made of the dihydro~ydiphenyl ether of the general formula (I):
~ ~ (I) ~10 OH
THERMAL RECORDING MATERIAL
The present invention relates to a thermal recording material. More particularly, the present invention relates to a -thermal recording material that is improved in color forming ability and other recording characteristics and which features a high degree of brightness and better image stability.
Various types of thermal recording materials have been proposed that utllize the thermal color-~orming reac-tion be~ween at least one colorless or pale-colored basic dye and color developing agents such as phenols and organic acids (see Japanese Patent Publication No. 45-1~039) and some of them are in extensive cvmmercial use. Applications of these thermal recording materials cover a wide range including recorders for measurements, terminal printers o~
computers and information communications systems, facsimiles and automatic ticket vending machines. These recording apparatus have heating elements such as thermal heads and heat pens (styli), which are heated to produce imagewise color -formation. With the recent increase in the versa-tility of the use o-f thermal recording equipment and improvement of their performance, the requirements for the quality of thermal recording paper have become increasingly rigorous. For instance, recording on a sheet of A4-size (210 mm x 297 mm) with modern facsimiles has become possible within one minute, although several minutes were required previously. Under these circumstances, several me~hods including the addition of sensitizers have been proposed as techniques for improving the sensitivlty of thermal record-- ing paper. However, none of the methods so ~ar proposed have successfully attained a balance between the qualities required of thermal recording materials including sensi-tivity to color formation, the stability of color lmage and 35 recording adaptability.
In the thermal recording layer o-f thermal recording paper, both a color-forming material and a phenolic compound are dispersed as fine particles and it is generally held 13:127'~
that upon heating, one or both o~ the components wlll ~use and come in lntimate contact with each other to achieve color formatlon.
As a phenolic compound that is suitable for the purpose of color development, 2,2-bis(4'-hydroxyphenyl) propane (bisphenol A; m.p. 156C) has been extensively used for several reasons including low cost and high stability o-f quality (see. for example, U.S. Patent No. 3,539,375).
However, bisphenol A is slow in response to heat and has not been able to satisfy all of the requirements of the market -for higher sensitivity of thermal recording paper that are adjunct to the recent tendency ~or faster operation or reduction in size of thermal recording equipment. With a view to solving this problem, many sensitizers have been proposed, including waxes (Japanese Patent Public ~isclosure No. 48-19231), phthalic acid esters (Japanese Patent Public Disclosure Nos. 57-116690 and 58-98285), benzylphenyl ethér derivatives (Japanese Patent Public Disclosure No. 59-155096), benzylbiphenyl (Japanese Patent Public Disclosure No. 60-82382), naphtholic derivatives (Japanese Patent Public Disclosure No. 58-87094) and carbonic acid diesters (Japanese Patent Public Disclosure No. 58-136489).
However, combinations of these sensitizers with bisphenol A
have so far been unable to produce satis~actory quality in ~5 such aspects as the degree of brightness, sensitivity for color formation and fog resistance. If one employs low-melting point monophenols such as ~-naphthol (m.p. 95 -96C) and 4-tertiary butylphenol (m.p. 94 - 99C) with a view to improving sensitivity for color -formation, a strong "phenolic" smell results and the commercial acceptance of the recording paper is reduced. Japanese Patent Public Disclosure No. 56-144193 proposes the use of benzyl p-hydroxybenzoate or methylbenzyl p-hydroxybenzoate as a cvlor developing agent for increasing the sensitlvity of a thermal recording sheet. However, a problem with thls idea is that the recording sheet is poor in image stabilit~ since white spots will appear in the image area during storage of the record.
~ 3~273~
As described above, none o~ the prior art thermal recordlng materials have been capable o-f -Eully satlsfying the require~ents of the market for higher performance with regard to such aspects as color-forming characteristics, the degree of brightness and image stability. A need, there-fore, has existed for the development of a thermal recording material that has high sensitivity and high degree of brigh-tness and which features better image stability.
1~ An obJect of the present invention is to provide a thermal recording material which not only has a practlcal level of sensitivity for color -formation that guarantees its use in a wide range of' applications bu-t which also features a high degree of brightness.
Another obJect of the present invention is to provide a thermal recording material which has the added advantage of better lmage stability.
These ob~ects of the present invention can be attained by a thermal recording material that contains in 2~ a thermal recording layer at least one colorless or pale-colored basis dye and a dlhydroxydiphenyl ether represented by the following general ~ormula:
HO OH (I) With a view to eliminating the several problems of the prior art techniques, the present inventors conducted intensive studies by screening a number of phenolic color-developing materials. As a result, the present inventors found that the dihydroxydiphenyl ether represented bY the general formula set forth above is an effective color developing agent that ensures high sensitivity and high degree of brightness and which yet is free ~rom the problem of white spots that has occurred in the use of ben~yl p-hydroxybenzoate. The present inventlon has been accom-plished on the basis of this flnding.
The dihydroxydiphenyl ether having the general 13:L27~
~ormula set ~orth above may be exemplif~ed by 2,2'-dihydroxydiphenyl ether (m.p. 121C), 3,3'-dihydroxydlphenyl ether (m.p. 98C) and 4,4'-dihydroxydiphenyl ether (m.p.
166C).
The reason why the dih~droxydiphenyl ether used in the present invention attains a higher degree o~ brightness and a hlgher sensiti~ity -for color formation than the conventionally used bisphenol A is not completely clear but this would probably be due to the miscibility of this compound with basic dyes or sensitizers that may be used in combination with these compounds.
In the present invention, the dihydroxydiphenyl ether of formula (I) is normally used in an amount of 0.5 - 3 parts by weigh-t, pre~erably 1 - 2 parts by weightt per part by weight of the color-forming basic dye.
By incorporating this amount o~ dihydroxYdiphenY
ether in a thermal recording layer, a thermal recording material having a high degree of brightness and sensitivity for color formation is obtained and this recording material 20 per se is normally suitable for practical use. However, if the thermal paper, after application of heat, is left to stand for 24 hours in a hot atmosphere ~60C x ZO% R.H.) or in a humid atmosphere (40C x 90% R.H.~, the density of the image will decrease and the residual density may sometimes 25 be reduced to 80% and below. In order to avoid this problem, the thermal recording material of the present invention is often required to have better image stability.
To meet this need, the present inventors conducted further studies and found that a thermal recording material 30 that had better image stability without compromising the degree of brightnass and sensitivity could be attained by using a color developing agent made of the dihydro~ydiphenyl ether of the general formula (I):
~ ~ (I) ~10 OH
in combina-tion with at least one compound selected -~rom the group consisting of 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 1,1,3-tris(2-methyl-4-hydroxy-5-cyclohexyl)butane, 1,3,5-tris(4-t-butyl-3-hydroxy-2,6-S dimethylbenzyl isocyanuric acid, 1,1-bis(2-methyl-4-hydroxy-5-t-butylphenyl)butane.
Amon~ the compounds that may be used in combination with the dihydroxydiphenyl ether, 1,1,3-tris(2-methyl-4-hydro~y-5-t-butylphenyl)butane is a substance represented by the formula (II):
OH OH
t--B~ t--B~
CH--CH CH--CH ( II ) ~,CH3 t--Bu~
OH
1,1,3-tris(2-methyl-4-hydroxy-5-cyclohexyl)butane ls a substance represented by the formula (III):
CH--CH --CH CH (III) ,l, CH3 OH
1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanuric acid is a substance represented by the formula ~IV):
~3~27~1 OM O ~
t - Bu CH2 o N o CH2 ~
CH2 3 (IV) CH3~CH3 OH
t - Bu 1,1-bis(2-methyl~4-hydroxy-5-t-butylphenyl)butane is a substance represented by the formula (V):
t - Bu t ~ Bu HO~CH3 TH ~O~ OH (V) When these substances are used ln combination with dihydroxydiphenyl ether of formula ~I), the dihydroxy-dlphenyl ether is generally used in an amount o~ 0.5 - 3 parts by weight per part by welght o~ a color-forming basic dye, and one or more of the substances listed above are used in an amount of 0.1 - 20 parts by weight per part by welght of this color developing agent. Preferably, dihydroxy-diphenyl ether is used in an amount of 1 - 2 parts by weight per part by weight of a color--forming basic dYe and one or more of the substances of interest are used in an amount of - 0.2 - 5 parts by weight per part by weight of dihydroxydi-phenyl ether.
15The addition of the substances listed above contri-butes to a marked improvement in image stability and in terms of the residual density of the image, the image stability of a thermal recording material using these substances is 10 - 20% better than in the case where dihydroxydiphenyl ether is employed in the absence of these ~2~3~
substances. This improvement will guarantee the storage of the thermal recording material of the present invention either in a hot or humid a-tmosphere aEter recording has been effected.
The colorless or pale-colored basic dye -for use in the forma~ion of a thermal recor-ding laYer in the present invention may be selected from among those which are commonly employed for this purpose, and representative examples are listed below:
Triarylmethane dyes such as 3,3-bis(p-dimethylaminophenyl)-6-dimethylamillophthalide, 3,3-bis(p-dimethylaminophenyl)phthalide, 3-(p-di~ethylaminophenYl)-3-(1,2-dimethylindol-3-yl)phthalide, 3-(~
dimethylaminophenyl)-3-(2-methylindol-3-yl)phthalide, 3,3-bis(l,Z-dinlethylindol-3-yl)-5-dimethylaminophthalide~
3,3-bis(1,2-dimethylindol-3-yl)-6-dimethylamlnophthalide, 3,3-bis(9-ethylcarbazol-3-yl)-6-dimethylaminophthalide, 3,3-bis(1,~-dime-thylindol-3-yl)-5-dimethylaminophthalide,.
and 3-p-dimethylaminophenyl-3-(1-methyl-pyrrol-3-yl)-6-dimethylaminophthallde; diphenylmethane dyes such as4,4'-bis-dimethylaminobenzhydrylbenzyl ether, N-halophenyl-leucoauramine and N-2,4,5-~richlorophenyl leucoauramine;
thiazine dYes such as benzoyl leucomethylene blue and p-nitroben~oyl leucomethylene blue; spiro dye~ such as 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopYran~
3-phenyl-spiro-dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 3-methyl-naphtho(6'-methoxybenzo~spiropyran and 3-propyl-spiro-dibenzopyran; lactam dyes such a~ rhodamine-B-anilinolactam, rhodamine(p-nitroanillno)lactam and rhodamine-~o-chloroanilino31actam; and fluorans such as 3-dimethylamino-7-methoxy-fluoran, 3-diethylamino-6-methoxyfluoran, 3-diethylamino-7-methoxy-fluoran, 3-diethylamino-7-chlorofluoran, 3-diethylamino-6-methyl-7-chlorofluoran, 3-diethylamino-6,7-dimethylfluoran, 3-(N-ethyl-p-toluidino)-7-methylfluoran, 3-diethylamino-7-N-acetyl-N-methylamino-fluoran, 3-diethylamino-7-N-methylaminofluoran, 3-dlethylamino-7-dibenzylaminofluoran, 3-diethylamino-7-N-methyl-N-benzylaminofluoran, ~ J ~
3-diethyla~nino-7-N-cl~loroet;hyl-~-methylamillof':Luoran, 3-diethyl-amlno-7-N-diethylaminofluoran, 3-(N-ethyl-p-toluidino)-6-met}lyl-7-phenylalllinofluoran, 3-(N-ethyl-p-toluidino~-6-methyl-7-(p--toluidino)-fluoran, 3-die-thylamino-5 6-methyl-7-phenylamino~luoran, 3-dibutyl-amino-6-methyl-7~
phenylamLnofluoran, 3-diethylamino-7-(2-carbomethoxy-phenylamino)fluoran, 3-(N-cyclohexyl-N-methylamino)-6-methyl-7-phenylaminofluoran, 3-pyrrolidino-6-methy1-7-phenylaminofluoran, 3-piperidino-6-methyl-7-10 phenylaminofluoran, 3-dietllylami.no-6-methyl-7-xylindino-~luoran, 3-diethylamino-7-(o-chlorophenylamlno)--fluoran, 3-dibutylamino-7-(o-chlorophenylamirlo)fluoran, 3-pyrrolidino-6-methy:L-7-p-butylphenylamino-fluoran, 3-(N-methyl-N-n-amyl)-amino-6-methyl-7-phenylaminofluoran, 3-(N-15 ethyl-N-n-amyl)amino-6-methyl-7-phenylaminofluoran, 3-(N-ethyl-N-iso-amyl)amlno-6-methyl-7-phenylamino-fluoran, 3-(N-methyl-N-n~hexyl)amino-6-methyl-7-phenyl-aminofluoran, 3-(N-ethyl-N-n-hexyl)amino-6-methyl-7-phenylamino-floran, and 3-(N-ethyl-N-~-ethylhexyl)amino-6-methyl-7-phenylaminofluoran.
Auxiliary substances that are commonly incorporated in thermal recording ma-terials may also be used in combina-tion with the compounds described above. An exemplary additive is a sensiti~er which may be illustrated by 1,1-bis-(4-hydroxy-phenyl)-cyclohexane, parabenzyl biphenyl, 25 dibenzyl terephthalate, phenyl-1-hydroxy-Z-naphthoate, dibenzyl oxalate, di-o-chlorobenzyl adipate, 1,2-di(3-methylphenoxy)ethane and di-p-chlorobenzyl oxalate.
The support on which the thermal recording layer o-f the thermal recording material of the present invention is 30 formed may be made o-~ any sui~able material that is selected from among paper, pigment-coated paper, paper made o~
synthetic fibers, synthetic paper, synthetic resin films, etc. Paper is normally preferred.
In preparing a coating solution from which a thermal 35 color-formin~ layer is to be formed, the baslc dye, dihydroxydiphenyl ether of formula (I) and a substance capable o-f improving image stability are dlspersed in water by means of a grinder such as a ball mill, attritor or a -9- ` ~312~13{~
sand grinder. The resulting coating solution contains 2 -40 wt%, preferably 5 - 25 wt%, of the total sollds content of a binder selected frorn among starches, hydroxyethyl cellulose, methYl cellulose, carboxymethyl cellulose, 5 gelatin, casein, gum arabic, polyvinyl alcohol, styrene, salts of maleic acid copolymers, styrene-butadiene copolymer emulsions, etc. Various auxiliary agents may be incor-porated as required in the coating solution. Illustratlve additives include: dispersants s~uch as sodium dioctylsulfo-lO succinate, sodium dodecylben~enesulfonate, ~odium salt o~laurylalcohol sulfate esters, and metal salts of aliphatic acids; antifoaming agents; fluorescent dyes; and pigment dyestuffs. With a view to reducing the chance of sticking of the thermal recording layer onto the thermal head or 15 residue on the thermal head and in order to -further improve its brightness, an inorganic pi~ment such as kaolin, clay, talc, calcium carbonate, calcined clay, titanium cxide, diatomaceous earth, flIle particulate anhydrous silica or alumlnum silicate may be incorporated in the recording 20 layer. If desired, waxes such as dispersions or emulsions of stearic acid, polyethylene, carnauba wax, paraffin wax, calcium stearate, ~inc stearate, ester waxes, etc. may also be incorporated in appropriate amounts in the coating solution.
The method of forming the recording layer of the thermal recording material of the present invention is not limited in any particular way. For instance, a thermal coating solution may be applied to the support with any suitable coating apparatus such as an air-knife coater or 30 a blade coater.
The coating weight of the thermal color-forming layer is not limited to any particular value but it is generally formed in a dry weight of 1 - 15 g/m2, the range of 3 -8 g/m2 being preferred.
If necessary, a varlety of known modifications, such as the provision of an undercoat, may be applled to the thermal recording material of the present invention.
1 3 l 2 7 ~ ~
In accordance with the present invention, an improved thermal recording material is pr-ovided which not only has a practical level o~ sens~tivi-ty for color formation -that guarantees its use in a wide range of applications but which 5 also features a high degree o-f brightness.
The ~ollowing examples are provided ~or ~he purpose o-f further illustrating the present invention bu-t are ln no way to be taken as limiting. In the following examples and comparative e~ample, all "parts" and "%" are on a weight lO basis.
(1) Preparation of Solution A
3-(N~cyclohexyl-N-methylamino)-6-me-thyl-7-phenyl-aminofluoran 40 parts 10% Aqueous polyvinYl alcohol solution 20 parts Water 20 parts This composition was ground into particles o~ an average size o-f 1 ~m with a sand grinder.
(2) Preparation of Solution B
2,2'-Dihydroxydiphenyl ether 40 parts 10% Aqueous polyvinyl alcohol solution 20 parts Water 20 parts This composition was ground lnto particles of an average size of 1.5 ~m with a sand grinder.
(3) Preparation of Solution C
Parabenzyl blphenyl 40 parts 10% Aqueous polyvinyl alcohol solution 20 parts Water 20 parts This composition was ground into particles o~ an average size o~ 1.5 ~m with a sand grinder.
t4~ Preparatlon of Solu-tion D
1,1,3-Tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane 40 parts 10% Aqueous polyvinyl alcohol solution 20 parts Water 20 parts This composltion was ground into particles o~ an average size of 1.5 ~m with a sand grinder.
lL3~273~
. .
Ten parts of Solution A, 20 parts of Solution B, 20 parts o~ Solution C, 30 parts of a 50% calcium carbonate dispersion, 8 parts of a 30~O zlnc stearate dispersion and 75 5 parts o~ a lO~o aqueous polyvinyl alcohol solutlon were mixed with stlrring to form a coating solution. This coating solution was applied to raw paper (50 g/m2) to give a dry weight o~ 7 g/m2 and subsequently dried to -form a thermal recording sheet.
lO EXAMP~E 2 A thermal recordlng sheet was prepared as in Example 1 except that Solution B had 2,2'-dihydroxydiphenyl ether replaced by the same amount of 4,4'-dihydroxydiphenyl ether.
A ~thermal recording sheet was prepared as in Example 1 except that Solution B had 2,2'-dihydroxydiphenyl ether replaced by the same amount of 3,3'-dihYdroxydiphenyl ether.
Ten parts of Solution A, 20 parts of Solution B, 20 ~o parts of Solution C, 5 parts of Solution D, 30 parts of a 50% calcium carbonate dispersion, 8 parts of a 30% zinc stearate dispersion and 75 parts o~ a 10% aqueous polyvinyl alcohol solution were mixed with stirring to ~orm a coating solution. This coating solution was applled to raw paper (50 g/m2) to give a dry welght o-f 7 g/m2 and subsequently dried to -form a thermal recordin~ sheet.
.
A thermal recording sheet was prepared as in Example 4 e~cept that Solutlon D had 1,1,3-tris(2-methyl-4-hydroxy-30 5-t-butylphenyl)-butane replaced by the same amount of 1,1,3-tris(2-methyl-4-hydroxy-5-cyclohexyl)butane.
A thermal recording sheet was prepared as in Example 4 except that Solution D had 1~1~3-tris(2-methyl-4-hYdr 35 5-t-butylphenyl)-butane replaced by the same amount o~
1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethyl) isocyanuric acid.
~3~2~3~
EXA~LE 7 A thermal recording sheet was prepared as ln Example 4 except that Solution D had 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)-butane replaced by the same amount o-f 1,1-5 bis(2-me-thyl-4-hydroxy-5-t-butylphenyl)butane.
A thermal recordlng sheet was prepared as in Example 1 except that Solution B had 2,2'-dihydroxydiphenyl ether replaced by the same amount of 2,2-bis(4'-lO hydroxyphenyl)propane (bisphenol A).
The eight samples of thermal recording sheet thusprepared were supercalendered and the degree of their brigh-tness was measured with a Hunter brigh-tness meter. After performing thermal recording on these sheets with Model 15 UF-60 of Matsushita Graphic Communication Sys-tems, Inc., the density of the image was measured wlth a densitometer, Model RD lOOR of Macbeth Instrument Corporation.
The samples were thereafter sub~ected to a storage test and the residual density of the image was calculated by 20 the following formula:
Density of the ima e after storage t st x 100 ~%) In the storage test, the record was left to stand for 25 24 hours in either a hot t60oC x 20% R.H.) or humid (40~C x 90~O R.H.) atmosphere to evaluate its resistance to heat or moisture. The results are shown in the following table.
13:~273~
-13~
. ._ ... ..
Hea-tMoisture : Initial resi, 'tanceresl~ ,tance Bright-image Density Residual Density ~esidual ness density densitydensity _ .__ .___ (%~_ (%~_ ..
Ex. 1 1.30 1.02 77 0.96 73 83.2 2 1.32 1.00 76 0.92 70 82.5 3 1.36 1.08 79 1.05 77 81.4 4 1.32 1.28 97 1.25 95 82.8 1.35 1,28 95 1.26 , 93 81.8 6 ~.31 1.24 95 1.23 94 82.0 7 1.30 1.22 94 1.21 93 81.0 Ex. 1 1.2 0.98 32 1.00 83 79.5 As is clear from this -table, the samples of the thermal recording material of the present invention are superior to the sample of Comparative Example 1 in terms o~
recording density. The samples prepared in Examples 4 - 7 are better in image stabilitY than those of Examples 1 - 3.
Amon~ the compounds that may be used in combination with the dihydroxydiphenyl ether, 1,1,3-tris(2-methyl-4-hydro~y-5-t-butylphenyl)butane is a substance represented by the formula (II):
OH OH
t--B~ t--B~
CH--CH CH--CH ( II ) ~,CH3 t--Bu~
OH
1,1,3-tris(2-methyl-4-hydroxy-5-cyclohexyl)butane ls a substance represented by the formula (III):
CH--CH --CH CH (III) ,l, CH3 OH
1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanuric acid is a substance represented by the formula ~IV):
~3~27~1 OM O ~
t - Bu CH2 o N o CH2 ~
CH2 3 (IV) CH3~CH3 OH
t - Bu 1,1-bis(2-methyl~4-hydroxy-5-t-butylphenyl)butane is a substance represented by the formula (V):
t - Bu t ~ Bu HO~CH3 TH ~O~ OH (V) When these substances are used ln combination with dihydroxydiphenyl ether of formula ~I), the dihydroxy-dlphenyl ether is generally used in an amount o~ 0.5 - 3 parts by weight per part by welght o~ a color-forming basic dye, and one or more of the substances listed above are used in an amount of 0.1 - 20 parts by weight per part by welght of this color developing agent. Preferably, dihydroxy-diphenyl ether is used in an amount of 1 - 2 parts by weight per part by weight of a color--forming basic dYe and one or more of the substances of interest are used in an amount of - 0.2 - 5 parts by weight per part by weight of dihydroxydi-phenyl ether.
15The addition of the substances listed above contri-butes to a marked improvement in image stability and in terms of the residual density of the image, the image stability of a thermal recording material using these substances is 10 - 20% better than in the case where dihydroxydiphenyl ether is employed in the absence of these ~2~3~
substances. This improvement will guarantee the storage of the thermal recording material of the present invention either in a hot or humid a-tmosphere aEter recording has been effected.
The colorless or pale-colored basic dye -for use in the forma~ion of a thermal recor-ding laYer in the present invention may be selected from among those which are commonly employed for this purpose, and representative examples are listed below:
Triarylmethane dyes such as 3,3-bis(p-dimethylaminophenyl)-6-dimethylamillophthalide, 3,3-bis(p-dimethylaminophenyl)phthalide, 3-(p-di~ethylaminophenYl)-3-(1,2-dimethylindol-3-yl)phthalide, 3-(~
dimethylaminophenyl)-3-(2-methylindol-3-yl)phthalide, 3,3-bis(l,Z-dinlethylindol-3-yl)-5-dimethylaminophthalide~
3,3-bis(1,2-dimethylindol-3-yl)-6-dimethylamlnophthalide, 3,3-bis(9-ethylcarbazol-3-yl)-6-dimethylaminophthalide, 3,3-bis(1,~-dime-thylindol-3-yl)-5-dimethylaminophthalide,.
and 3-p-dimethylaminophenyl-3-(1-methyl-pyrrol-3-yl)-6-dimethylaminophthallde; diphenylmethane dyes such as4,4'-bis-dimethylaminobenzhydrylbenzyl ether, N-halophenyl-leucoauramine and N-2,4,5-~richlorophenyl leucoauramine;
thiazine dYes such as benzoyl leucomethylene blue and p-nitroben~oyl leucomethylene blue; spiro dye~ such as 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopYran~
3-phenyl-spiro-dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 3-methyl-naphtho(6'-methoxybenzo~spiropyran and 3-propyl-spiro-dibenzopyran; lactam dyes such a~ rhodamine-B-anilinolactam, rhodamine(p-nitroanillno)lactam and rhodamine-~o-chloroanilino31actam; and fluorans such as 3-dimethylamino-7-methoxy-fluoran, 3-diethylamino-6-methoxyfluoran, 3-diethylamino-7-methoxy-fluoran, 3-diethylamino-7-chlorofluoran, 3-diethylamino-6-methyl-7-chlorofluoran, 3-diethylamino-6,7-dimethylfluoran, 3-(N-ethyl-p-toluidino)-7-methylfluoran, 3-diethylamino-7-N-acetyl-N-methylamino-fluoran, 3-diethylamino-7-N-methylaminofluoran, 3-dlethylamino-7-dibenzylaminofluoran, 3-diethylamino-7-N-methyl-N-benzylaminofluoran, ~ J ~
3-diethyla~nino-7-N-cl~loroet;hyl-~-methylamillof':Luoran, 3-diethyl-amlno-7-N-diethylaminofluoran, 3-(N-ethyl-p-toluidino)-6-met}lyl-7-phenylalllinofluoran, 3-(N-ethyl-p-toluidino~-6-methyl-7-(p--toluidino)-fluoran, 3-die-thylamino-5 6-methyl-7-phenylamino~luoran, 3-dibutyl-amino-6-methyl-7~
phenylamLnofluoran, 3-diethylamino-7-(2-carbomethoxy-phenylamino)fluoran, 3-(N-cyclohexyl-N-methylamino)-6-methyl-7-phenylaminofluoran, 3-pyrrolidino-6-methy1-7-phenylaminofluoran, 3-piperidino-6-methyl-7-10 phenylaminofluoran, 3-dietllylami.no-6-methyl-7-xylindino-~luoran, 3-diethylamino-7-(o-chlorophenylamlno)--fluoran, 3-dibutylamino-7-(o-chlorophenylamirlo)fluoran, 3-pyrrolidino-6-methy:L-7-p-butylphenylamino-fluoran, 3-(N-methyl-N-n-amyl)-amino-6-methyl-7-phenylaminofluoran, 3-(N-15 ethyl-N-n-amyl)amino-6-methyl-7-phenylaminofluoran, 3-(N-ethyl-N-iso-amyl)amlno-6-methyl-7-phenylamino-fluoran, 3-(N-methyl-N-n~hexyl)amino-6-methyl-7-phenyl-aminofluoran, 3-(N-ethyl-N-n-hexyl)amino-6-methyl-7-phenylamino-floran, and 3-(N-ethyl-N-~-ethylhexyl)amino-6-methyl-7-phenylaminofluoran.
Auxiliary substances that are commonly incorporated in thermal recording ma-terials may also be used in combina-tion with the compounds described above. An exemplary additive is a sensiti~er which may be illustrated by 1,1-bis-(4-hydroxy-phenyl)-cyclohexane, parabenzyl biphenyl, 25 dibenzyl terephthalate, phenyl-1-hydroxy-Z-naphthoate, dibenzyl oxalate, di-o-chlorobenzyl adipate, 1,2-di(3-methylphenoxy)ethane and di-p-chlorobenzyl oxalate.
The support on which the thermal recording layer o-f the thermal recording material of the present invention is 30 formed may be made o-~ any sui~able material that is selected from among paper, pigment-coated paper, paper made o~
synthetic fibers, synthetic paper, synthetic resin films, etc. Paper is normally preferred.
In preparing a coating solution from which a thermal 35 color-formin~ layer is to be formed, the baslc dye, dihydroxydiphenyl ether of formula (I) and a substance capable o-f improving image stability are dlspersed in water by means of a grinder such as a ball mill, attritor or a -9- ` ~312~13{~
sand grinder. The resulting coating solution contains 2 -40 wt%, preferably 5 - 25 wt%, of the total sollds content of a binder selected frorn among starches, hydroxyethyl cellulose, methYl cellulose, carboxymethyl cellulose, 5 gelatin, casein, gum arabic, polyvinyl alcohol, styrene, salts of maleic acid copolymers, styrene-butadiene copolymer emulsions, etc. Various auxiliary agents may be incor-porated as required in the coating solution. Illustratlve additives include: dispersants s~uch as sodium dioctylsulfo-lO succinate, sodium dodecylben~enesulfonate, ~odium salt o~laurylalcohol sulfate esters, and metal salts of aliphatic acids; antifoaming agents; fluorescent dyes; and pigment dyestuffs. With a view to reducing the chance of sticking of the thermal recording layer onto the thermal head or 15 residue on the thermal head and in order to -further improve its brightness, an inorganic pi~ment such as kaolin, clay, talc, calcium carbonate, calcined clay, titanium cxide, diatomaceous earth, flIle particulate anhydrous silica or alumlnum silicate may be incorporated in the recording 20 layer. If desired, waxes such as dispersions or emulsions of stearic acid, polyethylene, carnauba wax, paraffin wax, calcium stearate, ~inc stearate, ester waxes, etc. may also be incorporated in appropriate amounts in the coating solution.
The method of forming the recording layer of the thermal recording material of the present invention is not limited in any particular way. For instance, a thermal coating solution may be applied to the support with any suitable coating apparatus such as an air-knife coater or 30 a blade coater.
The coating weight of the thermal color-forming layer is not limited to any particular value but it is generally formed in a dry weight of 1 - 15 g/m2, the range of 3 -8 g/m2 being preferred.
If necessary, a varlety of known modifications, such as the provision of an undercoat, may be applled to the thermal recording material of the present invention.
1 3 l 2 7 ~ ~
In accordance with the present invention, an improved thermal recording material is pr-ovided which not only has a practical level o~ sens~tivi-ty for color formation -that guarantees its use in a wide range of applications but which 5 also features a high degree o-f brightness.
The ~ollowing examples are provided ~or ~he purpose o-f further illustrating the present invention bu-t are ln no way to be taken as limiting. In the following examples and comparative e~ample, all "parts" and "%" are on a weight lO basis.
(1) Preparation of Solution A
3-(N~cyclohexyl-N-methylamino)-6-me-thyl-7-phenyl-aminofluoran 40 parts 10% Aqueous polyvinYl alcohol solution 20 parts Water 20 parts This composition was ground into particles o~ an average size o-f 1 ~m with a sand grinder.
(2) Preparation of Solution B
2,2'-Dihydroxydiphenyl ether 40 parts 10% Aqueous polyvinyl alcohol solution 20 parts Water 20 parts This composition was ground lnto particles of an average size of 1.5 ~m with a sand grinder.
(3) Preparation of Solution C
Parabenzyl blphenyl 40 parts 10% Aqueous polyvinyl alcohol solution 20 parts Water 20 parts This composition was ground into particles o~ an average size o~ 1.5 ~m with a sand grinder.
t4~ Preparatlon of Solu-tion D
1,1,3-Tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane 40 parts 10% Aqueous polyvinyl alcohol solution 20 parts Water 20 parts This composltion was ground into particles o~ an average size of 1.5 ~m with a sand grinder.
lL3~273~
. .
Ten parts of Solution A, 20 parts of Solution B, 20 parts o~ Solution C, 30 parts of a 50% calcium carbonate dispersion, 8 parts of a 30~O zlnc stearate dispersion and 75 5 parts o~ a lO~o aqueous polyvinyl alcohol solutlon were mixed with stlrring to form a coating solution. This coating solution was applied to raw paper (50 g/m2) to give a dry weight o~ 7 g/m2 and subsequently dried to -form a thermal recording sheet.
lO EXAMP~E 2 A thermal recordlng sheet was prepared as in Example 1 except that Solution B had 2,2'-dihydroxydiphenyl ether replaced by the same amount of 4,4'-dihydroxydiphenyl ether.
A ~thermal recording sheet was prepared as in Example 1 except that Solution B had 2,2'-dihydroxydiphenyl ether replaced by the same amount of 3,3'-dihYdroxydiphenyl ether.
Ten parts of Solution A, 20 parts of Solution B, 20 ~o parts of Solution C, 5 parts of Solution D, 30 parts of a 50% calcium carbonate dispersion, 8 parts of a 30% zinc stearate dispersion and 75 parts o~ a 10% aqueous polyvinyl alcohol solution were mixed with stirring to ~orm a coating solution. This coating solution was applled to raw paper (50 g/m2) to give a dry welght o-f 7 g/m2 and subsequently dried to -form a thermal recordin~ sheet.
.
A thermal recording sheet was prepared as in Example 4 e~cept that Solutlon D had 1,1,3-tris(2-methyl-4-hydroxy-30 5-t-butylphenyl)-butane replaced by the same amount of 1,1,3-tris(2-methyl-4-hydroxy-5-cyclohexyl)butane.
A thermal recording sheet was prepared as in Example 4 except that Solution D had 1~1~3-tris(2-methyl-4-hYdr 35 5-t-butylphenyl)-butane replaced by the same amount o~
1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethyl) isocyanuric acid.
~3~2~3~
EXA~LE 7 A thermal recording sheet was prepared as ln Example 4 except that Solution D had 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)-butane replaced by the same amount o-f 1,1-5 bis(2-me-thyl-4-hydroxy-5-t-butylphenyl)butane.
A thermal recordlng sheet was prepared as in Example 1 except that Solution B had 2,2'-dihydroxydiphenyl ether replaced by the same amount of 2,2-bis(4'-lO hydroxyphenyl)propane (bisphenol A).
The eight samples of thermal recording sheet thusprepared were supercalendered and the degree of their brigh-tness was measured with a Hunter brigh-tness meter. After performing thermal recording on these sheets with Model 15 UF-60 of Matsushita Graphic Communication Sys-tems, Inc., the density of the image was measured wlth a densitometer, Model RD lOOR of Macbeth Instrument Corporation.
The samples were thereafter sub~ected to a storage test and the residual density of the image was calculated by 20 the following formula:
Density of the ima e after storage t st x 100 ~%) In the storage test, the record was left to stand for 25 24 hours in either a hot t60oC x 20% R.H.) or humid (40~C x 90~O R.H.) atmosphere to evaluate its resistance to heat or moisture. The results are shown in the following table.
13:~273~
-13~
. ._ ... ..
Hea-tMoisture : Initial resi, 'tanceresl~ ,tance Bright-image Density Residual Density ~esidual ness density densitydensity _ .__ .___ (%~_ (%~_ ..
Ex. 1 1.30 1.02 77 0.96 73 83.2 2 1.32 1.00 76 0.92 70 82.5 3 1.36 1.08 79 1.05 77 81.4 4 1.32 1.28 97 1.25 95 82.8 1.35 1,28 95 1.26 , 93 81.8 6 ~.31 1.24 95 1.23 94 82.0 7 1.30 1.22 94 1.21 93 81.0 Ex. 1 1.2 0.98 32 1.00 83 79.5 As is clear from this -table, the samples of the thermal recording material of the present invention are superior to the sample of Comparative Example 1 in terms o~
recording density. The samples prepared in Examples 4 - 7 are better in image stabilitY than those of Examples 1 - 3.
Claims (3)
1. A thermal recording material having a thermal record-ing layer that utilizes a color forming reaction between at least one basic dye and a color developing agent capable of forming color in contact with said basic dye, said thermal recording layer containing a dihydroxydiphenyl ether of the formula:
2. A thermal recording material according to Claim 1 wherein said thermal recording layer further contains at least one compound selected from the group consisting of 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 1,1,3-tris(2-methyl-4-hydroxY-5-t-butylphenyl)butane, 1,1,3-tris(2-methyl-4-hydroxy-5-cyclcohexyl)butane, 1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenæyl)isocyanuric acid and 1,1-bis(2-methyl-4-hydroxy-5-t-butylphenyl)butane.
3. A thermal recording material according to Claim 2 wherein said at least one compound is used in the amount of 0.1 - 20 parts by weight per part by weight of dihydroxy-diphenyl ether.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63004498A JPH01180382A (en) | 1988-01-12 | 1988-01-12 | Thermal recording material |
| JP4498/1988 | 1988-01-12 | ||
| JP63187338A JPH0236990A (en) | 1988-07-27 | 1988-07-27 | Heat-sensitive recording material |
| JP187338/1988 | 1988-07-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1312730C true CA1312730C (en) | 1993-01-19 |
Family
ID=26338284
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000587318A Expired - Fee Related CA1312730C (en) | 1988-01-12 | 1988-12-30 | Thermal recording material |
Country Status (2)
| Country | Link |
|---|---|
| EP (1) | EP0324576A3 (en) |
| CA (1) | CA1312730C (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2944101B2 (en) * | 1989-04-28 | 1999-08-30 | 王子製紙株式会社 | Thermal recording medium |
| JPH06255258A (en) * | 1993-03-01 | 1994-09-13 | New Oji Paper Co Ltd | Thermal recording material |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57133097A (en) * | 1981-02-13 | 1982-08-17 | Mita Ind Co Ltd | Heat sensitive recording body and manufacture thereof |
| JPS60210490A (en) * | 1984-04-04 | 1985-10-22 | Hokuetsu Seishi Kk | Thermal recording sheet |
| DE3534594C2 (en) * | 1984-09-28 | 1995-12-21 | Fuji Photo Film Co Ltd | Heat sensitive recording material |
| JPS625879A (en) * | 1985-07-01 | 1987-01-12 | Fuji Photo Film Co Ltd | Production of thermal recording material |
| GB2184856B (en) * | 1985-11-15 | 1989-10-25 | Fuji Photo Film Co Ltd | Heat-sensitive recording materials |
| DE3723282A1 (en) * | 1986-07-14 | 1988-02-11 | Mitsubishi Paper Mills Ltd | HEAT SENSITIVE RECORDING MATERIAL |
-
1988
- 1988-12-30 CA CA000587318A patent/CA1312730C/en not_active Expired - Fee Related
-
1989
- 1989-01-10 EP EP89300177A patent/EP0324576A3/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| EP0324576A2 (en) | 1989-07-19 |
| EP0324576A3 (en) | 1990-08-16 |
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