Coating composition, heat-sensitive recording layer, heat-sensitive recording material, and corresponding uses and methods

Abstract

A coating composition for producing a heat-sensitive recording material and to a corresponding heat-sensitive recording layer. The coating composition includes one or more color developers, one or more dye precursors, one or more specific fatty acid amides, and one or more (additional) specific sensitizers. A heat-sensitive recording material including a carrier substrate and a heat-sensitive recording layer, to the use of specific fatty acid amides in order to increase the grease resistance of a heat-sensitive recording material or a heat-sensitive recording layer, and to a method for producing a heat-sensitive recording material or a heat-sensitive recording layer.

Claims

1. A coating composition for producing a heat-sensitive recording material, comprising: at least one color developer, wherein at least one of the at least one color developer being a compound of formula (I) ##STR00014## wherein the compound of formula (I) is present in a crystalline form which in the IR spectrum has an absorption band at 3401±20 cm.sup.−1, at least one dye precursor; at least one fatty acid amide each having a number of carbon atoms in a range from 16 to 24; a sensitizer comprising at least one compound selected from the group consisting of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether; and a ratio of a total mass of fatty acid amides having a number of carbon atoms in a range from 16 to 24 to a total mass of compounds selected from the group consisting of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether in the coating composition or the heat-sensitive recording layer being in a range from 4:1 to 1.2:1.

2. The coating composition as claimed in claim 1, further comprising at least one constituents from the group consisting of a further sensitizer, a pigment, a dispersant, an antioxidant, a release agent, a defoamer, a light stabilizer, and a brightener.

3. The coating composition as claimed in claim 2, wherein: the at least one fatty acid amide have a number of carbon atoms in a range from 16 to 24 being octadecanamide and/or N-(hydroxymethyl)octadecanamide and/or possessing a melting point which is greater than 103° C.

4. The coating composition as claimed in claim 3, wherein a ratio of the mass of the compound of the formula (I) to a total mass of fatty acid amides having the number of carbon atoms in a range from 16 to 24 in the coating composition or the heat-sensitive recording layer being in a range from 1.2:1 to 4:1 and/or a ratio of the mass of the compound of the formula (I) to the mass of octadecanamide and/or N-(hydroxymethyl)octadecanamide in the coating composition being in a range from 1.2:1 to 4:1.

5. The coating composition as claimed in claim 1, wherein a ratio of a total mass of fatty acid amides having a number of carbon atoms in the range from 16 to 24 to a total mass of compounds selected from the group consisting of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether in the coating composition being in a range from 1.5:1 to 1.2:1.

6. The coating composition as claimed in claim 1, comprising as sensitizer 1,2-diphenoxyethane or a mixture of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether.

7. The coating composition as claimed in claim 1, the at least one fatty acid amides having a number of carbon atoms in a range from 16 to 24 being octadecanamide and/or N-(hydroxymethyl)octadecanamide and/or possessing a melting point which is greater than 103° C.

8. A coating composition for producing a heat-sensitive recording material or heat-sensitive recording layer, comprising at least one color developer, wherein at least one of the at least one color developers being a compound of a formula (I) ##STR00015## wherein the compound of formula (I) is present in a crystalline form which in the IR spectrum has an absorption band at 3401±20 cm.sup.−1, at least one dye precursor; octadecanamide and/or N-(hydroxymethyl)octadecanamide; a sensitizer comprising, 1,2-diphenoxyethane and/or ethylene glycol m-tolyl ether, wherein a ratio of a mass of the compound of the formula (I) to a mass of octadecanamide and/or N-(hydroxymethyl)octadecanamide in the coating composition being in a range from 1.2:1 to 4:1, and a ratio of a total mass of octadecanamide and N-(hydroxymethyl)octadecanamide to the total mass of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether in the coating composition being in a range from 1.5:1 to 1.2:1.

9. A heat-sensitive recording material, comprising: a carrier substrate; and a heat-sensitive recording layer comprising: at least one color developer, wherein at least one of the at least one color developer being a compound of formula (I) ##STR00016## wherein the compound of formula (I) is present in a crystalline form which in the IR spectrum has an absorption band at 3401±20 cm.sup.−1, at least one dye precursor; at least one fatty acid a amide each having a number of carbon atoms in a range from 16 to 24; a sensitizer comprising at least one compound selected from the group consisting of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether; and a ratio of a total mass of fatty acid amides having a number of carbon atoms in a range from 16 to 24 to a total mass of compounds selected from the group consisting of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether in the coating composition or the heat-sensitive recording layer being in a range from 4:1 to 1.2:1.

10. The heat-sensitive recording material as claimed in claim 9, further comprising at least one interlayer disposed between the carrier substrate and the heat-sensitive recording layer and/or wherein no further layer is disposed on a side of the heat-sensitive recording layer that faces away from the carrier substrate and/or wherein the carrier substrate consists of paper, synthetic paper, polymeric film, or an assembly of these materials.

11. A heat sensitive recording material comprising: a carrier substrate; and a heat-sensitive recording layer, comprising: at least one color developer, wherein at least one of the at least one color developer being a compound of formula (I) ##STR00017## wherein the compound of formula (I) is present in a crystalline form which in the IR spectrum has an absorption band at 3401±20 cm.sup.−1, at least one dye precursor; at least one fatty acid amide each having a number of carbon atoms in a range from 16 to 24 and comprising octadecanamide and/or (N-hydroxymethyl)octadecanamide; as a sensitizer, comprising at least one compound selected from the group consisting of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether; and a ratio of a total mass of fatty acid amides having a number of carbon atoms in a range from 16 to 24 to a total mass of compounds selected from the group consisting of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether in the coating composition or the heat-sensitive recording layer being in a range from 4:1 to 1.2:1.

12. A method for producing a heat-sensitive recording material, comprising providing or producing a carrier substrate and also a coating composition comprising: at least one color developer, wherein at least one of the at least one color developers being a compound of formula (I) ##STR00018## wherein the compound of formula (I) is present in a crystalline form which in the IR spectrum has an absorption band at 3401±20 cm.sup.−1, at least one dye precursor; at least one fatty acid amide each having a number of carbon atoms in a range from 16 to 24; a sensitizer comprising at least one compound selected from the group consisting of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether; and a ratio of a total mass of fatty acid amides having a number of carbon atoms in a range from 16 to 24 to a total mass of compounds selected from the group consisting of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether in the coating composition being in a range from 4:1 to 1.2:1; applying the coating composition to the carrier substrate or an interlayer disposed thereon; drying the applied coating composition, to give a heat-sensitive recording layer on the carrier substrate as the heat-sensitive recording material.

13. The method as claimed in claim 12, comprising: providing or producing the carrier substrate with the interlayer disposed thereon applying the coating composition to the interlayer; and drying the applied coating composition, to give a heat-sensitive recording layer on the interlayer which is on the carrier substrate as the heat-sensitive recording material.

14. A method for producing a thermally printed heat-sensitive recording material, comprising: providing a heat-sensitive recording material comprising: a carrier substrate; and a heat-sensitive recording layer comprising: at least one color developer, wherein at least one of the at least one color developer being a compound of formula (I) ##STR00019## wherein the compound of formula (I) is present in a crystalline form which in the IR spectrum has an absorption band at 3401±20 cm.sup.−1, at least one dye precursor; at least one fatty acid amide each having a number of carbon atoms in a range from 16 to 24; a sensitizer comprising at least one compound selected from the group consisting of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether; and a ratio of a total mass of fatty acid amides having a number of carbon atoms in a range from 16 to 24 to a total mass of compounds selected from the group consisting of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether in the heat-sensitive recording layer being in a range from 4:1 to 1.2:1; and heat-treating the heat-sensitive recording material, so that the at least one color developer and the at least one dye precursor reacts so as to develop a coloration.

15. The method as claimed in claim 14, wherein the at least one fatty acid amide remains in the solid state at the location of the heat treating.

16. A heat-sensitive recording material, comprising a carrier substrate and a heat sensitive recording later formed from the coating composition in claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The appended FIGS. 1, 2, 3, and 4 are graphic reproductions (fine drawings) of machine-generated original spectra and machine-generated original diffractograms, respectively.

(2) FIG. 1 is a comparison of IR spectra in the wavenumber range from around 4000 to 2000 cm.sup.−1 of the two crystalline forms of the compound of the formula (I);

(3) FIG. 2 is a comparison of IR spectra in the wavenumber range from around 2400 to 400 cm.sup.−1 of the two crystalline forms of the compound of the formula (I);

(4) FIG. 3 is a comparison of IR spectra of the two crystalline forms of the compound of the formula (I); and

(5) FIG. 4 is a comparison of X-ray powder diffractograms of the two crystalline forms of the compound of the formula (I).

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

(6) FIG. 1 shows a comparison of IR spectra in the wavenumber range from around 4000 to 2000 cm.sup.−1 of the two crystalline forms of the compound of the formula (I). Depicted in the upper part and identified with a) is the IR spectrum of the crystalline form of the compound of the formula (I) used in the invention with a melting point of 175° C. Depicted in the lower part and identified with b) is the IR spectrum of the crystalline form of the compound of the formula (I) having a melting point of around 158° C.

(7) FIG. 2 shows a comparison of IR spectra in the wavenumber range from around 2400 to 400 cm.sup.−1 of the two crystalline forms of the compound of the formula (I). Depicted in the upper part and identified with a) is the IR spectrum of the crystalline form of the compound of the formula (I) used in the invention with a melting point of 175° C. Depicted in the lower part and identified with b) is the IR spectrum of the crystalline form of the compound of the formula (I) having a melting point of around 158° C.

(8) FIG. 3 shows a comparison of IR spectra of the two crystalline forms of the compound of the formula (I). Depicted in the upper part and identified with a) is the IR spectrum of the crystalline form of the compound of the formula (I) used in the invention with a melting point of 175° C. Depicted in the lower part and identified with b) is the IR spectrum of the crystalline form of the compound of the formula (I) having a melting point of around 158° C.

(9) FIG. 4 shows a comparison of X-ray powder diffractograms of the two crystalline forms of the compound of the formula (I). Depicted in the upper part and identified with a) is the X-ray powder diffractogram of the crystalline form of the compound of the formula (I) with a melting point of around 158° C. Depicted in the lower part and identified with b) is the X-ray powder diffractogram of the crystalline form of the compound of the formula (I) used in the invention having a melting point of 175° C.

(10) Selected and preferred aspects of the invention are summarized below:

(11) 1. A coating composition for producing a heat-sensitive recording material or heat-sensitive recording layer, comprising one or plural color developers, said one or at least one of the plural color developers being a compound of the formula (I)

(12) ##STR00011## one or plural dye precursors, one or plural fatty acid amides each having a number of carbon atoms in the range from 16 to 24, as sensitizer, one or more compounds selected from the group consisting of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether.

(13) 2. The coating composition or heat-sensitive recording layer according to aspect 1, further comprising one or plural constituents from the group comprising further sensitizers, pigments, dispersants, antioxidants, release agents, defoamers, light stabilizers,

(14) and brighteners.

(15) 3. The coating composition or heat-sensitive recording layer according to either of aspects 1 and 2, said one or one of the plural fatty acid amides having a number of carbon atoms in the range from 16 to 24

(16) being octadecanamide and/or N-(hydroxymethyl)octadecanamide

(17) and/or

(18) possessing a melting point which is greater than 103° C., preferably greater than 105° C.

(19) 4. The coating composition or heat-sensitive recording layer according to any of the preceding aspects,

(20) the ratio of the total mass of the compound of the formula (I) to the total mass of fatty acid amides having a number of carbon atoms in the range from 16 to 24 in the coating composition or the heat-sensitive recording layer being in the range from 1.2:1 to 4:1

(21) and/or

(22) the ratio of the mass of the compound of the formula (I) to the mass of octadecanamide and/or N-(hydroxymethyl)octadecanamide in the coating composition or the heat-sensitive recording layer being in the range from 1.2:1 to 4:1.

(23) 5. The coating composition or heat-sensitive recording layer according to any of the preceding aspects, the ratio of the total mass of fatty acid amides having a number of carbon atoms in the range from 16 to 24 to the total mass of compounds selected from the group consisting of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether in the coating composition or the heat-sensitive recording layer being in the range from 4:1 to 0.8:1, preferably in the range from 2:1 to 1:1, more preferably in the range from 1.5:1 to 1:1, very preferably in the range from 1.5:1 to 1.2:1.

(24) 6. The coating composition or heat-sensitive recording layer according to any of the preceding aspects, comprising one or plural color developers, said one or at least one of the plural color developers being a compound of the formula (I)

(25) ##STR00012## one or plural dye precursors, octadecanamide and/or N-(hydroxymethyl)octadecanamide, as sensitizer, 1,2-diphenoxyethane and/or ethylene glycol m-tolyl ether,

(26) the ratio of the mass of the compound of the formula (I) to the mass of octadecanamide and/or N-(hydroxymethyl)octadecanamide in the coating composition being in the range from 1.2:1 to 4:1,

(27) and

(28) the ratio of the total mass of octadecanamide and N-(hydroxymethyl)octadecanamide to the total mass of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether

(29) in the coating composition being in the range from 2:1 to 1:1, more preferably in the range from 1.5:1 to 1:1, very preferably in the range from 1.5:1 to 1.2:1.

(30) 7. The coating composition or heat-sensitive recording layer according to any of the preceding aspects, comprising as sensitizer 1,2-diphenoxyethane or a mixture of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether.

(31) 8. A heat-sensitive recording material, comprising a carrier substrate

(32) and a heat-sensitive recording layer according to any of aspects 1 to 7.

(33) 9. The heat-sensitive recording material, wherein one or plural interlayers are disposed between carrier substrate and heat-sensitive recording layer

(34) and/or no further layer is disposed on the side of the heat-sensitive recording layer that faces away from the carrier substrate

(35) and/or the carrier substrate consists of paper, synthetic paper, polymeric film, or an assembly of these materials.

(36) 10. The use of a fatty acid amide having a number of carbon atoms in the range from 16 to 24 or of a mixture of plural fatty acid amides each having a number of carbon atoms in the range of 16 to 24, preferably use of octadecanamide and/or N-(hydroxymethyl)octadecanamide, for increasing the grease resistance of a heat-sensitive recording material or a heat-sensitive recording layer, comprising one or plural color developers, said one or at least one of the plural color developers being a compound of the formula (I)

(37) ##STR00013## one or plural dye precursors,

(38) and as sensitizer, one or more compounds selected from the group consisting of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether.

(39) 11. A method for producing a heat-sensitive recording material according to either of aspects 8 and 9 or a heat-sensitive recording layer, having the following steps: providing or producing a carrier substrate and also a coating composition according to any of aspects 1 to 7, applying the coating composition to the carrier substrate or an interlayer disposed thereon, drying the applied coating composition, to give a heat-sensitive recording layer which is present together with the carrier substrate in a heat-sensitive recording material.

(40) 12. The method according to aspect 11, for producing a heat-sensitive recording material according to either of aspects 8 and 9, having the following steps: providing or producing a carrier substrate with interlayer disposed thereon and also a coating composition according to any of aspects 1 to 7, applying the coating composition to the interlayer, drying the applied coating composition, to give a heat-sensitive recording layer which is present together with the carrier substrate and the interlayer in the heat-sensitive recording material.

(41) 13. A method for producing a thermally printed heat-sensitive recording material, having the following steps: providing a heat-sensitive recording material according to either of aspects 8 and 9 or implementing the method according to either of aspects 11 and 12, to give a heat-sensitive recording material, heat-treating the recording material, so that color developers and dye precursors react so as to develop a coloration.

(42) 14. The method according to aspect 13, wherein the fatty acid amide used having a number of carbon atoms in the range from 16 to 24 or the mixture used of plural fatty acid amides each having a number of carbon atoms in the range from 16 to 24, preferably octadecanamide and/or N-(hydroxymethyl)octadecanamide, remains in the solid state at the location of the heat treatment.

EXAMPLES

(43) Determining the Resistance of Heat-Sensitive Recording Materials to Lanolin:

(44) For metrological capture of the resistance of a thermal printout on the heat-sensitive recording materials of the inventive examples and of the noninventive examples with respect to lanolin, test thermal printouts with a checkered black and white design were produced on each of the heat-sensitive recording materials under test, using an Atlantek Model 400 “Thermal Response Test System” instrument from Global Media Instruments, LLC (USA), employing a thermal head having a resolution of 300 dpi and an energy per unit area of 16 mJ/mm.sup.2.

(45) Following the production of the test thermal printouts with black and white checkering, and after a rest time of more than 5 minutes, a determination of the print density was carried out at three locations on the black-colored areas of the test thermal printouts, by a TECHKON® SpectroDens Advanced spectral densitometer. The mean was formed from the respective measurement values.

(46) The test thermal printout produced on the heat-sensitive recording material under test was then coated with lanolin hand cream. After an exposure time of 5 and 10 minutes, respectively, the lanolin was carefully dabbed off and then the treated thermal paper printout was stored at 23° C. and 50% humidity. After 4 hours and 24 hours, the thermal paper printout was removed, and again a determination of the print density was carried out at three locations on the black-colored areas of the test thermal printouts, by a TECHKON® SpectroDens Advanced spectral densitometer.

(47) The mean was formed from the respective measurement values.

(48) The resistance of the printed image in percent corresponds to the ratio of the mean of the print density of the black-colored areas before and after the treatment with lanolin and subsequent storage at 23° C. and 50% humidity, multiplied by 100.

(49) In-House Studies:

(50) The results of measurement determined in in-house studies show that the print density of inventive examples decreases less than the print density of noninventive examples. The resistance of the printed image to lanolin, i.e., the grease resistance, is therefore higher for inventive examples than for noninventive examples, in which only a fatty acid amide or only 1,2-diphenoxyethane or ethylene glycol m-tolyl ether was used. The combination of stearamide (octadecanamide) or N-(hydroxymethyl)octadecanamide and 1,2-diphenoxyethane or ethylene glycol m-tolyl ether as sensitizer, used in accordance with the invention, therefore has a synergistic effect.

(51) In further in-house studies, preferred mixing ratios were determined for coating compositions comprising stearamide (octadecanamide) and 1,2-diphenoxyethane (DPE) as well. In carrying out these experimental studies, a coating composition was produced which corresponds very largely to the aqueous application suspension of formulation 1 as per DE 10 2014 107 567 B3 (cf. paragraph [0060] therein). The total amount of octadecanamide (stearamide) and DPE in the in-house studies was 40 mass fractions (corresponding to the 40 mass fractions of sensitizer from formulation 1 from DE 10 2014 107 567 B3). Said 40 mass fractions were distributed in the in-house studies between the octadecanamide and DPE constituents, with the mixing ratios being varied. Results of the studies are reported in table 1 below.

(52) TABLE-US-00001 TABLE 1 Mass fractions of sensitizers Octadecanamide: 1,2-diphenoxyethane 20:20 23:17 25:15 27:13 Experimental series I I-1 I-2 I-3 I-4 Print density before 1.16 1.23 1.21 1.13 lanolin exposure Print density after 5 0.70 0.97 0.87 0.67 min lanolin exposure and 4 h exposure time Resistance/% 60.3 78.9 71.9 59.3 Experimental series II II-1 II-2 II-3 II-4 Print density before 1.15 1.24 1.20 1.13 lanolin exposure Print density after 10 0.18 0.32 0.24 0.27 min lanolin exposure and 24 h exposure time Resistance/% 15.7 25.8 20.0 23.9

(53) Outline composition for an inventive coating composition and for an inventive heat-sensitive recording layer:

(54) Table 2 specifies a preferred outline composition for a coating composition of the invention and for a heat-sensitive recording layer of the invention. All of the data relate to measurement on oven-dry material; the actual coating composition or actual heat-sensitive recording layer may comprise liquid (especially water); it was therefore subjected to oven drying before determination of the mass fractions.

(55) TABLE-US-00002 TABLE 2 Mass fraction [%] N-[2-(3-Phenylureido)phenyl]benzene- 8-30 sulfonamide (NKK, color developer) Dye precursor 4-16 Octadecanamide (fatty acid amide) 2.4-34.sup.  1,2-Diphenoxyethane (sensitizer)  2-8.5 Polyvinyl alcohol (PVA, binder) 6-24 Pigments 25-55  Total 100

(56) The percentage mass fractions reported in the right-hand column of table 2 add up to a total of 100%. Thus, while there have shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.