GB2115943A - Heat-sensitive recording sheets containing fluoran dyes - Google Patents
Heat-sensitive recording sheets containing fluoran dyes Download PDFInfo
- Publication number
- GB2115943A GB2115943A GB08300531A GB8300531A GB2115943A GB 2115943 A GB2115943 A GB 2115943A GB 08300531 A GB08300531 A GB 08300531A GB 8300531 A GB8300531 A GB 8300531A GB 2115943 A GB2115943 A GB 2115943A
- Authority
- GB
- United Kingdom
- Prior art keywords
- heat
- sensitive recording
- dye
- recording sheet
- fluoran
- 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.)
- Withdrawn
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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
- B41M5/323—Organic colour formers, e.g. leuco dyes
- B41M5/327—Organic colour formers, e.g. leuco dyes with a lactone or lactam ring
- B41M5/3275—Fluoran 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
A heat-sensitive recording sheet comprises a support, e.g. of paper, bearing a heat-sensitive layer of an almost colorless electron-donating dye and an organic acid capable of forming color when heated in contact with the dye. The dye contains at least two fluoran compounds, and 20-90 wt. % of the dye is a fluoran compound represented by the general formula <IMAGE> wherein R1 and R2 are alkyl, cycloalkyl, aralkyl or aryl but are not both aryl and may together complete a hetero ring, X is halogen and R3 is aryl or alkoxy alkyl. Eight such compounds are named, wherein X is chloro and R1, R2 are ethyl or dibutyl. The organic acid is exemplified as an aromatic carboxylic acid or metal salt thereof or a substituted phenol. The sheet forms good color by scanning in a facsimile machine, and the image has good resistance to moisture and heat (e.g. 50 DEG C and 10% RH or 60 DEG C and 25% RH for 24 hours). <IMAGE>
Description
SPECIFICATION
Heat-sensitive recording sheets containing fluoran dyes
The present invention relates to heat-sensitive recording sheets and, more particularly, to heat-sensitive recording sheets which are greatly improved in color-forming properties and which are characterized by the feature that images or patterns recorded therein do not easily disappear.
Heat-sensitive recording sheets are materials in which images or patterns are formed by utilizing physical and chemical changes of substance brought about by heat energy. A number of processes utilizing such heat-sensitive sheets have been increasingly studied.
These heat-sensitive recording sheets have advantages in that they undergo primary color formation and, therefore, no development is needed. In recent years, heat-sensitive recording sheets have been used as recording sheets for facsimile and computer output due to their characteristics as described above. They are called "dye type recording sheets", and are disclosed in, for example, Japanese Patent Publication Nos 4160/68 (corresponding to U.S. Patent Application No.512,546) and 14039/70 (corresponding to U.S. Patent 3,539,375), and Japanese Patent Application (OPI) No.27253/80 (corresponding to U.S. Patent 4,283,458) (the term "OPI" as used herein refers to a "published unexamined Japanese patent application").
In general, the use of heat-sensitive recording sheets as recording sheets is advantageous because the recording devices can be made light-weight and small-sized. Recently, therefore, they have been increasingly used.
The major requirements for heat-sensitive recording sheets are: (1) they are able to produce high density recorded images or patterns, and (2) the thus-recorded images or patterns do not disappear under the influence of atmospheric conditions such as moisture and heat.
In particular, the disappearance of recorded images or pattens is a serious problem encountered in using the recording sheets. Therefore, various attempts to overcome the problem have been made.
For example, Japanese Patent Publication No.43386/76 (corresponding to U.S. Patent 3,937,864) describes addition of phenol derivatives such as 2,2'-methylenebis(4-methyl-6-tert-butylphenol); Japanese Patent
Application (OPI) No. 17347/78 describes addition of water-insoluble modified phenol resins such as rosin-modified phenol resins; and Japanese Patent Application (OPI) No. 72996/81 discloses addition of terephthalic acid esters such as diethyl phthalate. In addition, Japanese Patent Application (OPI) No.
109454/79 (corresponding to U.S. Patent 4,226,912) describes the use or mixture of two or morefluoran compounds.
However, all of the above-described conventional methods fail to sufficiently improve the image disappearance-inhibiting effect. Furthermore, these methods cause undesired color-formation during the preparation of storage of recording sheet, i.e., so-called "fog". This fog is seriously increased particularly under influences of moisture and heat. Under such conditions, therefore, the product value is seriously reduced.
A primary object of the present invention is to provide heat-sensitive recording sheets which are able to produce high density recorded images or patterns, which are less influenced by moisture and heat, and undergo only limited color-disappearance, and which do not cause the formation of fog.
The objects of the present invention have been attained by producing a heat-sensitive recording sheet comprising an almost colourless electron-donating dye (color former) and an organic acid capable of forming color when brought into contact with the dye. The dye contains at least two kinds of fluoran compounds, onefluoran compound being a compound represented by the general formula (I):
wherein R1 and R2 independently represent an alkyl group (preferably C1 to C8), a cycloalkyl group (preferably cyclohexyl group), an aralkyl group (preferably C7 to C10) or an aryl group, and may combine together to form a heterocyclic ring, provided that R1 and R2 are not aryl groups at the same time; Xis a halogen atom; and Rs is an aryl group or an alkoxyalkyl group (preferably C2to C6). The compound represented by the general formula (I) comprises from 20 to 90% by weight of the dye.
It is known that a mixture of two or more dyes can be used in the preparation of heat-sensitive recording sheets. Unexpectedly, however, it has been found that the use of a fluoran mixture containing a specific proportion of fluoran compound represented by the general formula (I) as described hereinbefore increases color-forming properties and inhibits disappearance of recorded images or patterns.
The amount of the fluoran compound of the general formula (I) being used is, based on the total dye, from 20% by weight to 90% by weight, preferably from 40% by weight to 85% by weight, and more preferably from 50% by weight to 80% by weight. In lesser amounts than 20% by weight or in larger amounts than 90% by weight, color-forming properties are reduced and, at the same time, the image disappearance-inhibiting effect is reduced. The coating amount of the fluoran represented by the general formula (I) is 0.1 to 1.0 g/m2 as a solid content, preferably.
Representative examples of the fluoran compounds represented by the general formula (I) are shown below:
(1) 3-Diethylamino-6-chloro-7-anilinofluoran
(2) 3-Dibutylamino-6-chloro-7-anilinofluoran
(3) 3-Diethylamino-6-chloro-7-p-anisidinofluoran
(4) 3-Diethylamino-6-chloro-7-p-toluidinofluoran
(5) 3-Diethylamino-6-chloro-7--methoxyethylaminofluoran (6) 3-Diethylamino-6-ch loro-7-,13-methoxyethylam inofl uoran (7) 3-Dibutylamino-6-ch loro-7-ss-ethoxyethylaminofluoran (8) 3-Diethylamino-6-chloro-7--butoxyethylaminofluoran In the above-described fluoran compounds, the 3-diethylamino-6-chloro-7-anilinofluoran and 3-diethyl amino-6-chloro-7--ethoxyethylaminofluoran are more preferred.
Anyfluoran compounds can be used in combination with the fluoran compounds represented by the general formula (I). They may be selected from the fluoran compounds represented by the general formula (I) orfluoran compounds other than the fluoran compounds of the general formula (I).
Representative examples of fluoran compounds other than the fluoran compounds of the general formula (I) are shown below: 3-Diethylamino-7-dibenzylaminofluoran, 3-diethylamino-7-octylaminofluoran, 3-diethylamino-7-(2- chloroanilino)fluoran, 3-dibutylamino-7-(2-chloroanilino)fluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-piperidino-6-methyl-7-anilinofluoran, 3-cyclohexylmethylamino-6-methyl-7-anilinofluoran, and 3-(N-ethylp-toluidino)-6-methyi-7-anilinofluoran.
Preferred examples of organic acids as used herein include phenol derivatives and aromatic carboxylic acid derivatives. In particular, bisphenols are preferred.
Examples of phenols include p-octylphenol, p-tert-butylphenol,p-phenylphenol, l,l-bis(p- hydroxyphenyl)propane, 2,2-bis(p-hydroxyphenyl)propane, 1,1 -bis(p-hydroxyphenyl)pentane, 1,1 -bis(p- hydroxyphenyl)-hexane, 2,2-bis(p-hydroxyphenyl)hexane, 1,1 -bis(p-hydroxyphenyl )-2-ethyl-hexane, and 2,2-bis(4-hydroxy-3,5-dichlorophenyl)propane.
Examples of aromatic carboxylic acid derivatives include benzyl p-hydroxybenzoate, ethyl phydroxybenzoate, butyl p-hydroxybenzoate, 3,5-di-tert-butyl-salicylic acid, and 3,5-di-amethylbenzylsalicylic acid. In the case of carboxylic acids, their polyvalent metal salts can also be used.
In preparing coating solutions for the production of heat-sensitive recording sheets, it is necessary to disperse materials as described above in water as a dispersion medium. In this dispersion procedure, it is preferred to use water-soluble polymers such as polyvinyl alcohol, hydroxyethyl cellulose and starch derivatives. For example, from 10 to 50% by weight of electron-donating dye or organic acid is introduced into a dispersion medium containing from 1 to 10% by weight, preferably from 2 to 5% by weight of water-soluble polymer, and the resulting mixture is dispersed by means of a dispersing machine, e.g., a ball mill, a sand mill, an attritor, or a colloid mill.
The thus-prepared dispersions are added, if desired, oil-absorbing pigments, waxes, metallic soaps, etc., to prepare coating solutions for the production of heat-sensitive recording sheets. These coating solutions are coated on supports such as paper or plastics to obtain the desired heat-sensitive recording sheets.
Oil-absorbing pigments include kaolin, calcined kaolin, talc, agalmatolite, diatomaceous earth, calcium carbonate, aluminum hydroxide, magnesium hydroxide, magnesium carbonate, titanium oxide, barium carbonate, urea-formalin fillers, and cellulose fillers.
Waxes include paraffin wax, carnauba wax, microcrystalline wax, polyethylene wax, and further, higher aliphatic acid amides, such as stearic acid amide, ethylenebisstearoamide, and higher aliphatic acid esters.
Metallic soaps include higher aliphatic acid polyvalent metal salts, such as zinc stearate, aluminum stearate, calcium stearate, and zinc oleate.
The following examples are given to illustrate the invention in greater detail.
Example 1
A mixture of 20 g of 3-diethylamino-6-chloro-7-,3-ethoxyethylaminofluoran and 100 g of a 10% aqueous solution of polyvinyl alcohol (degree of saponification: 98%; degree of polymerization: 500) was dispersed
in a 300-mt ball mill for about 24 hours to prepare Dispersion (A). A mixture of 20 g of 3-diethylamino-7-(2chloro-anilino)fluoran and 100 g of a 10% aqueous solution of polyvinyl alcohol was dispersed in a 300 mt ball mill for about 24 hours to prepare Dispersion (B). A mixture of 10 g of 2,2-bis(4-hydroxyphenyl)propane,
10 g of stearic acid amide, and 100 g of a 10% aqueous solution of polyvinyl alcohol was dispersed in a 300-mt ball mill for about 24 hours to prepare Dispersion (D). Dispersion (A) and Dispersion (B) were mixed
in a weight ratio of 70:30 to prepare Mixed Dispersion (C). Mixed Dispersion (C) and Dispersion (D) were
mixed in a weight ratio of 3:20. Fineiy powdered calcium carbonate (50 g) was added to 200 g of the resultant mixture and fully dispersed to prepare a coating solution.
The thus-prepared coating solution was coated on a paper substrate having a basic weight of 50 g/m2 in an amount (as solids) of 6 g/m2 by means of an air knife and dried at 50"C for 2 minutes to produce a heat-sensitive recording sheet.
Example 2
A heat-sensitive recording sheet was prepared in the same manner as in Example 1 except that Mixed
Dispersion (C) was prepared by mixing Dispersion (A) and Dispersion (B) in a weight ratio of 90:10.
Example 3
A heat-sensitive recording sheet was prepared in the same manner as in Example 1 except that Mixed
Dispersion (C) was prepared by mixing Dispersion (A) and Dispersion (B) in a weight ratio of 30:70.
Example 4
A heat-sensitive recording sheet was prepared in the same manner as in Example 1 except that Dispersion (B) was prepared by using 20 g of 3-dibutylamino-7-(2-chloroanilino)fluoran in place of 20 g of 3-diethylamino-7-(2-chloroanilino)fluoran.
Example 5
A heat-sensitive recording sheet was prepared in the same manner as in Example 1 except that Dispersion (B) was prepared by using 20 g of 3-cyclohexylmethylamino-6-methyl-7-anilinofluoran in place of 20 g of 3-diethyl-amino-7-(2-chloroanilino)fluoran.
Example 6
A heat-sensitive recording sheet was prepared in the same manner as in Example 1 except that Dispersion (B) was prepared by using 20 g of 3-diethylamino-6-chloro-7-anilinofluoran in place of 20 g of 3-diethyl-amino-6-ch loro-7.(3.ethoxyethylaminofluoran.
Example 7
A heat-sensitive recording sheet was prepared in the same manner as in Example 1 except that Dispersion (A) was prepared by using 20 g of 3-diethylamino-6-chloro-7-anilinofluoran in place of 20 g of 3-diethyl-amino-6-chloro-7-ss-ethoxyethylaminofluoran, and Dispersion (B) was prepared by using 20 g of 3-diethylamino-6-chloro-7-ss-ethoxyethylaminofluoran in place of 20 g of 3-diethylamino-7-(2chloroanilino)fluoran.
Comparative example 1
A heat-sensitive recording sheet was prepared in the same manner as in Example 1 except that Dispersion (A) was prepared by using 20 g of 3-(N-ethyl-p-toluidino)-6-methyl-7-anilinofluoran in place of 20 g of 3-diethylamino-6-chloro-7-ss-ethoxyethylaminofluoran.
Comparative example 2
A heat-sensitive recording sheet was prepared in the same manner as in Example 1 except that Dispersion (A) (of 3-diethylamino-6-chloro-7-ss-ethoxyethylaminofluoran) and Dispersion (D) were mixed in a weight ratio of 3:20.
Comparative example 3
A heat-sensitive recording sheet was prepared in the same manner as in Example 1 except that Dispersion (B) (of 3-diethylamino-7-(2-chloroanilino)fluoran) and Dispersion (D) were mixed in a weight ratio of 3:20.
Comparative example 4
A heat-sensitive recording sheet was prepared in the same manner as in Example 1 except that Dispersion (A) was prepared by using 20 g of 3-diethylamino-6-chloro-7-anilinofluoran in place of 20 g of 3-diethylamino-6-chloro-7-ss-ethoxylaminofluoran, and Dispersion (A) and Dispersion (D) were mixed in a weight ratio of 3:20.
Comparison test
The heat-sensitive recording sheets prepared in Examples 1 to 7 and Comparative Examples 1 to 4 were tested as follows; "Macbeth" is a registered Trade Mark.
(1) Fog and Color-Forming Properties:
Recording was performed by applying energy of 2 ms/dot and 50 mJ/mm2 onto a recording element at a density of main scanning of 5 dot/mm and sub scanning of 6 dot/mm. Fog (the density of the background before recording) and color density after recording (initial density) were measured using a Macbeth RD-514 refractive densitometer (with a visual filter).
(2) Moisture Resistance:
The colored recording obtained in the color-forming property testing method was allowed to stand in an atmosphere of 50"C and 90% Rh for 24 hours. At the end of the time, the fog (density of background) and the density of colored member were measured.
The residual ratio of the coloration was calculated by the following equation:
(Density after Moisture Resistance
(Initial Density x 100 (%) (3) Heat Resistance:
The colored member was allowed to stand in an atmosphere of 60"C and 25% RH for 24 hours, and thereafter, the fog (density of background) and the colored member density were measured. The residual ratio of coloration was calculated by the following equation:
(Density after Heat Resistance) x 100 (%)
(Initial Density)
The results are shown in Table 1.
TABLE 1
Initial Fog and Moisture
Color-Forming Resistance Heat Resistance
Properties Residual Residual
Sample No. Fog Density Fog Ratio Fog Ratio
(%) (%)
Heat-Sensitive Recording Sheet
of Example 1 0.07 1.10 0.10 82 0.08 93 " of Example 2 0.07 1.02 0.10 70 0.08 80 " of Example3 0.07 0.98 0.10 78 0.08 85 " of Example4 0.07 1.06 0.10 75 0.08 85 " of Example 5 0.08 1.10 0.13 83 0.10 93 " of Example6 0.07 1.08 0.09 78 0.08 90 " of Example7 0.07 1.10 0.10 82 0.09 92 " of Comparative Example 1 0.08 0.88 0.15 70 0.12 82 " of ComparativeExample2 0.07 0.90 0.10 44 0.08 50 " of ComparativeExample3 0.07 0.80 0.09 15 0.08 25 " of ComparativeExample4 0.07 0.86 0.09 40 0.08 45
It can be seen from Table 1 that, compared with the comparative heat-sensitive recording sheets, the heat-sensitive recording sheets of the invention have high color densities, are less subject to colordisappearance due to moisture and heat, and furthermore, are excellent with respect to reducing the amount of fog. Particularly, it can be seen that the heat-sensitive recording sheet of Example 1 has high color density and is less subject to color-disappearance due to moisture and heat as compared with the recording sheets of Comparative Examples 2 and 3 in which each of the two kinds of color formers was used alone.
Accordingly, the above results clearly show that greater color density can be obtained when the electron-donating dye of the invention is used and that undesirable fog density is not increased.
Furthermore, the color images produced using a heat-sensitive recording sheet of the invention have an improved stability residual ratio and improved fastness to light. It is evident that the use of the dyes according to the invention make it possible to produce a heat-sensitive recording sheet which achieves the objects of the present invention.
Claims (9)
1. A heat-sensitive recording sheet comprising a layer of an almost colorless electron-donating dye and an organic acid capable of forming color when brought into contact with the dye when the layer is heated, wherein the dye contains at least two fluoran compounds, one fluoran compound being a compound represented by the general formula (I):
wherein R1 and R2 independently represent an alkyl group, a cycloalkyl group, an aralkyl group or an aryl group, and may combine together to form a heterocyclic ring, provided that R1 and R2 are not aryl groups at the same time; Xis a halogen atom; and R3 is an aryl group or an alkoxyalkyl group, the fluoran compound represented by the general formula (I) comprising from 20 to 90% by weight of the total dye.
2. A heat-sensitive recording sheet as claimed in Claim 1, wherein the fluoran compound represented by the general formula (I) comprises from 40% to 85% by weight of the total dye.
3. A heat-sensitive recording sheet as claimed in Claim 2, wherein the fluoran compound represented by the general formula (I) comprises from 50% to 80% by weight of the total dye.
4. A heat-sensitive recording sheet as claimed in any of Claims 1 to 3, wherein the organic acid is a phenol derivative, an aromatic carboxylic acid derivative or a metal salt of the latter.
5. A heat-sensitive recording sheet as claimed in Claim 4, wherein the organic acid is a bisphenol.
6. A heat-sensitive recording sheet as claimed in any preceding Claim, wherein the layer was produced by coating a dispersion of the organic acid and the electron-donating dye each dispersed in an aqueous solution of a water-soluble polymer.
7. A heat-sensitive recording sheet as claimed in any preceding Claim, wherein the dye (I) is any of the dyes (1) to (8) listed hereinbefore.
8. A heat-sensitive recording sheet as claimed in any preceding Claim, substantially as hereinbefore described in any of Examples 1 to 7.
9. A colored recording made by local heating of a heat-sensitive sheet as claimed in any preceding Claim.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57001619A JPS58119892A (en) | 1982-01-08 | 1982-01-08 | Heat-sensitive recording paper |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8300531D0 GB8300531D0 (en) | 1983-02-09 |
| GB2115943A true GB2115943A (en) | 1983-09-14 |
Family
ID=11506537
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08300531A Withdrawn GB2115943A (en) | 1982-01-08 | 1983-01-10 | Heat-sensitive recording sheets containing fluoran dyes |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPS58119892A (en) |
| DE (1) | DE3300229A1 (en) |
| GB (1) | GB2115943A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5071480A (en) * | 1986-10-31 | 1991-12-10 | Ciba-Geigy Corporation | Fluoran color former mixture and use thereof in recording materials |
| US5149689A (en) * | 1986-10-31 | 1992-09-22 | Ciba-Geigy Corporation | Fluoran color former mixture and use thereof in recording materials |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3440514A1 (en) * | 1984-02-14 | 1985-09-05 | Papierfabrik August Koehler AG, 7602 Oberkirch | Thermal printing system |
| DE3425560C1 (en) * | 1984-07-11 | 1986-01-16 | Pelikan Ag, 3000 Hannover | Correction tape for thermosensitive papers |
| DE3520190C1 (en) * | 1985-06-05 | 1986-10-30 | Pelikan Ag, 3000 Hannover | Tissue tape |
| JPS63122759A (en) * | 1986-10-31 | 1988-05-26 | チバーガイギ アクチエンゲゼルシヤフト | Fluorane coupler mixture and use thereof in recording material |
| JP2009061454A (en) * | 2008-12-19 | 2009-03-26 | Mitsubishi Electric Corp | Washing method and washing object |
-
1982
- 1982-01-08 JP JP57001619A patent/JPS58119892A/en active Pending
-
1983
- 1983-01-05 DE DE19833300229 patent/DE3300229A1/en not_active Withdrawn
- 1983-01-10 GB GB08300531A patent/GB2115943A/en not_active Withdrawn
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5071480A (en) * | 1986-10-31 | 1991-12-10 | Ciba-Geigy Corporation | Fluoran color former mixture and use thereof in recording materials |
| US5149689A (en) * | 1986-10-31 | 1992-09-22 | Ciba-Geigy Corporation | Fluoran color former mixture and use thereof in recording materials |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8300531D0 (en) | 1983-02-09 |
| DE3300229A1 (en) | 1983-07-21 |
| JPS58119892A (en) | 1983-07-16 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |