THERMOSENSITIVE RECORDING MATERIAL

Abstract

The present invention relates to a thermosensitive recording material and, specifically, to a thermosensitive recording material comprising: a colorless or light-colored leuco dye; a compound of chemical formula (1) containing a non-phenolic sulfonyl urea group as a developer; at least one of general formulas II-1, II-2, and II-3 as a sensitizer; a binder; and other fillers. The thermosensitive recording material of the present invention improves the background blurring of a color-developed image by using a non-phenolic developer and exhibits excellent effects in view of color development sensitivity, water resistance, oil resistance, plasticizer resistance, and the like.

Claims

1. A thermosensitive recording material, comprising: a leuco dye; a developer containing a compound represented by Formula (I); and a sensitizer containing at least one selected from groups represented by Formulae (II-1), (II-2) and (II-3): ##STR00010## wherein R.sub.1 is a hydrogen atom or methyl; R.sub.2 is a hydrogen atom, methyl or ethyl; A is a C1-C8 alkyl, cycloalkyl or aromatic group, or an aromatic group substituted by methyl or a halogen atom; ##STR00011## wherein R.sub.3 is a hydrogen atom or methyl, ##STR00012## wherein R.sub.4 is a hydrogen atom, methoxy or diallyloxy, ##STR00013##

2. The material according to claim 1, wherein the compound represented by Formula (I) above is included in an amount of 80 to 100% by weight (wt. %) to a total amount of developer.

3. The material according to claim 1, wherein the compound represented by Formula (I) above is at least one selected from compounds represented by Formulae (I-1), (I-2) and (I-3) below: ##STR00014##

4. The material according to claim 1, wherein, as the sensitizer, at least one selected from 1,2-di-(3-methylphenoxy)ethane, 1,2-di-phenoxyethane, diphenylsulfone, 4,4-diallyloxydiphenylsulfone and -benzyloxynaphthalene is included.

5. The material according to claim 1, wherein the leuco dye is at least one selected from 3-diethylamino-6-methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3-(N-ethyl-N-isopentylamino)-6-methyl-7-anilinofgluoran, 3-(N-methyl-N-propylamino)-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-(p-chloroanilino)fluoran and 3-diethylamino-6-methyl-7-(o-chloroanilino)fluoran.

6. The material according to claim 1, wherein the developer is included in an amount of 0.5 to 3 parts by weight (wt. parts) to 1 wt. part of leuco dye.

7. The material according to claim 1, wherein the sensitizer is included in an amount of 0.5 to 3 wt. parts to 1 wt. part of leuco dye.

8. The material according to claim 1, further including at least one selected from binders, pigments, lubricants and additives.

9. The material according to claim 8, wherein, as the additives, at least one selected from dispersants, defoamers and fluorescent dyes is included in an amount of 0.01 to 10 wt. parts to 1 wt. part of leuco dye.

10. The material according to claim 1, wherein the thermosensitive recoding material is formed to be carried on a support.

Description

PREFERRED EMBODIMENT FOR EMBODYING THE INVENTION

[0045] Hereinafter, the present invention will be concretely described by means of embodiments. However, the scope of the present invention is duly not limited thereto.

<Synthesis Example 1> Synthesis of Compound I-1

[0046] To a 200 ml three-neck flask equipped with a condenser and a dropping funnel, 10.7 g of p-toluidine and 100 ml of toluene were introduced and fully dissolved. Next, 19.7 g of p-toluene sulfonyl isocyanate was placed in the dropping funnel. The p-toluene sulfonyl isocyanate in the dropping funnel was gently dropped into the flask at room temperature while preventing an internal temperature from exceeding 60 C. After completing dropping, the solution was agitated for 1 hour and then the reaction was terminated. The reacted solution was cooled to room temperature, followed by filtering and drying the separated crystals. After drying, 27.2 g of 99.1% purity (HPLC) compound I-1 was obtained. A structure of the product was determined by NMR.

[0047] .sup.1H-NMR spectrum (300 MHz, DMSO-d.sub.6)

[0048] 10.5 ppm (1H, s), 8.5 ppm (1H, s), 7.80 ppm (2H, d), 7.30 ppm (2H, d), 7.14 ppm (2H, d),

[0049] 6.95 ppm (2H, d), 2.37 ppm (3H, s), 2.18 ppm (3H, s)

<Synthesis Example 2> Synthesis of Compound I-2

[0050] The same procedures as described in Synthesis Example 1 were executed except that 10.6 g of N-methyl aniline was used as a raw material instead of p-toluidine. 25.7 g of 98.6% purity (HPLC) compound I-2 was obtained.

[0051] .sup.1H-NMR spectrum (300 MHz, DMSO-d.sub.6)

[0052] 10.5 ppm (1H, s), 7.79 ppm (2H, d), 7.34 ppm (2H, d), 7.13 ppm (2H, d),

[0053] 7.05 ppm (2H, d), 6.8 ppm (1H, t), 2.71 ppm (3H, s), 2.37 ppm (3H, s)

<Synthesis Example 3> Synthesis of Compound I-3

[0054] The same procedures as described in Synthesis Example 1 were executed except that 10.0 g of cyclohexylamine was used as a raw material instead of p-toluidine. 26.7 g of 99.2% purity (HPLC) compound I-3 was obtained.

[0055] .sup.1H-NMR spectrum (300 MHz, DMSO-d.sub.6)

[0056] 10.5 ppm (1H, s), 5.8 ppm (1H, s), 7.80 ppm (2H, d), 7.14 ppm (2H, d),

[0057] 3.40 ppm (1H, m), 1.53-1.76 ppm (4H, m), 1.40-1.49 ppm (6H, m)

<Example 1> Preparation of Thermosensitive Recording Material

[0058] The following A to D solutions were wet-ground by means of a sand grinder until each of the components had an average particle size of 0.5 m. Herein, the average particle size refers to an average diameter in volume-based distribution, and is determined by a laser diffraction/scattering device for measuring particle size distribution. Herein, parts means parts by weight (wt. parts).

TABLE-US-00001 TABLE 1 Preparation of A solution Compound I-1 5.0 parts Polyvinyl alcohol (10% aqueous 18.8 parts solution) Water 12.2 parts

TABLE-US-00002 TABLE 2 Preparation of B solution 3-dibutylamino-6-methyl-7- 1.3 parts anilinofluoran Polyvinyl alcohol (10% aqueous 4.6 parts solution) Water 3.1 parts

TABLE-US-00003 TABLE 3 Preparation of C solution Compound II-1-1 (R.sub.3 is methyl) 5.0 parts Polyvinyl alcohol (10% aqueous 18.8 parts solution) Water 12.2 parts

TABLE-US-00004 TABLE 4 Preparation of D solution Compound I-1 4.5 parts Compound I-3 0.5 part Polyvinyl alcohol 18.8 parts (10% aqueous solution) Water 12.2 parts

[0059] Preparation of Coating Solution for Thermosensitive Recording Layer

[0060] Mixing the above solutions in the following mixing ratios resulted in a coating solution for a thermosensitive recording layer.

TABLE-US-00005 TABLE 5 A solution 36 parts B solution 18 parts C solution 36 parts Silica (Mitsusawa, P537 25% 60 parts water dispersion) Polyvinyl alcohol (10% aqueous 25 parts solution)

[0061] The coating solution was applied to a substrate sheet having a standard weight of 50 g/m.sup.2 by means of a bar coater No. 10. A coating amount of the solution was 5 g/m.sup.2 in dry weight. After drying, supercalendering was conducted to produce a thermosensitive recording material.

Example 2

[0062] The same procedures as described in Example 1 were executed except that compound II-1-1 was replaced by compound II-2-1 (R.sub.4 is hydrogen).

Example 3

[0063] The same procedures as described in Example 1 were executed except that compound II-1-1 was replaced by compound II-3.

Example 4

[0064] The same procedures as described in Example 1 were executed except that compound I-1 was replaced by compound I-2.

Example 5

[0065] The same procedures as described in Example 4 were executed except that compound II-1-1 was replaced by compound II-2-1 (R.sub.4 is hydrogen).

Example 6

[0066] The same procedures as described in Example 4 were executed except that compound II-1-1 was replaced by compound II-3.

Example 7

[0067] The same procedures as described in Example 1 were executed except that A solution was replaced by D solution.

Example 8

[0068] The same procedures as described in Example 7 were executed except that compound II-1-1 was replaced by compound II-2-1 (R.sub.4 is hydrogen).

Example 9

[0069] The same procedures as described in Example 7 were executed except that compound II-1-1 was replaced by compound II-3.

Comparative Example 1

[0070] The same procedures as described in Example 1 were executed except that compound I-1 was replaced by BPA (bisphenol A).

Comparative Example 2

[0071] The same procedures as described in Example 1 were executed except that compound I-1 was replaced by N-(p-toluenesulfonyl)-N-(3-p-toluenesulfonyloxyphenyl)urea.

[0072] <Color Development Sensitivity>

[0073] Using a thermosensitive printer (TH-PMD) of OHKURA Electric Co., a gradation pattern was dot-printed. Image concentrations and background concentrations at applied energy of 0.26 mJ/dot and 0.35 mJ/dot, respectively, were measured by a Macbeth densitometer (using Invar filter). Measurement results are shown in Table 6.

[0074] <Background Fog>

[0075] The thermosensitive recording material was dot-printed at applied energy of 0.35 mJ/dot, and then, left at 60 C. for 24 hours. The background concentration was measured by a Macbeth densitometer and results thereof are shown in Table 7.

[0076] <Heat Resistance>

[0077] The thermosensitive recording material was dot-printed at applied energy of 0.35 mJ/dot, and then, left at 60 C. for 24 hours. The image concentration was measured by a Macbeth densitometer and Table 8 shows the image concentration and the image retention rate calculated by the following equation.

Image retention rate (%)=100(image concentration after test/image concentration before test)

[0078] As image retention rate increases, dot-printability and stability of the thermosensitive recording material are improved.

[0079] <Plasticizer Resistance>

[0080] The thermosensitive recording material was dot-printed at applied energy of 0.35 mJ/dot, followed by bringing a vinyl chloride wrap into contact with the surface of the material and leaving the same at 23 C. for 2 hours. The image concentration and background concentration were measured by a Macbeth densitometer and Table 8 shows the image retention rate.

[0081] <Oil Resistance>

[0082] The thermosensitive recording material was dot-printed at applied energy of 0.35 mJ/dot, followed by applying diesel oil to the surface of the material and keeping the same in a hot blower at 60 C. for 3 hours. The image concentration was measured by a Macbeth densitometer and Table 8 shows the image retention rate.

[0083] <Moisture Resistance>

[0084] The thermosensitive recording material was dot-printed at applied energy of 0.35 mJ/dot, and then, left at 40 C. under 90% humidity for 24 hours. The image concentration was measured by a Macbeth densitometer and Table 8 shows the image retention rate.

[0085] <Water Resistance>

[0086] The thermosensitive recording material was dot-printed at applied energy of 0.35 mJ/dot, and then immersed in tap water at 20 C. and left for 24 hours. The image concentration was measured by a Macbeth densitometer. Table 8 shows the image retention rate.

TABLE-US-00006 TABLE 6 Background Image concentration concentration 0.26 mJ/dot 0.35 mJ/dot Example 1 0.06 1.26 1.38 Example 2 0.06 1.24 1.39 Example 3 0.06 1.27 1.34 Example 4 0.06 1.21 1.30 Example 5 0.06 1.24 1.34 Example 6 0.06 1.20 1.36 Example 7 0.07 1.29 1.43 Example 8 0.06 1.30 1.40 Example 9 0.06 1.31 1.39 Comparative 0.07 1.24 1.36 Example 1 Comparative 0.06 1.07 1.28 Example 2 * The numerical value of the measured image concentration is proportional to color development sensitivity.

TABLE-US-00007 TABLE 7 Before test After test Background Image Background concentration concentration concentration Example 1 0.06 1.38 0.12 Example 2 0.06 1.39 0.12 Example 3 0.06 1.34 0.13 Example 4 0.06 1.30 0.12 Example 5 0.06 1.34 0.11 Example 6 0.06 1.36 0.15 Example 7 0.07 1.43 0.15 Example 8 0.06 1.40 0.14 Example 9 0.06 1.39 0.15 Comparative 0.07 1.36 0.24 Example 1 Comparative 0.06 1.28 0.13 Example 2 * The lower the background concentrations before and after test, the better the background fogging phenomenon.

TABLE-US-00008 TABLE 8 Before test Image retention rate (%) Background Image Heat Plasticizer Oil Moisture Water concentration concentration resistance resistance resistance resistance resistance Example 1 0.06 1.38 98 90 92 93 76 Example 2 0.06 1.39 96 92 93 91 75 Example 3 0.06 1.34 95 89 93 91 79 Example 4 0.06 1.30 93 89 91 91 81 Example 5 0.06 1.34 90 91 92 92 84 Example 6 0.06 1.36 94 87 90 89 79 Example 7 0.07 1.43 102 90 93 93 82 Example 8 0.06 1.40 98 91 94 92 78 Example 9 0.06 1.39 100 88 92 93 83 Comparative 0.07 1.36 85 74 82 81 16 Example 1 Comparative 0.06 1.28 95 87 93 92 78 Example 2 * Image retention rate is proportional to stability of the recorded image.

[0087] Referring to Table 6, it could be seen that the color development sensitivity in Example 1 to Example 9, respectively, was much higher than that in a case where N-(p-toluenesulfonyl)-N-(3-p-toluenesulfonyloxylphenyl)urea is used as in Comparative Example 2. Further, compared to results obtained using bisphenol A in Comparative Example 1, superior or substantially equal results were demonstrated.

[0088] From results of a performance test with regard to the background fog in Table 7 and results of the image retention rate with regard to different physical properties in Table 8, it could be seen that the results in Example 1 to Example 9 of the present invention were superior to the results obtained using bisphenol A in Comparative Example 1 in terms of background fog and, especially, plasticizer resistance and water resistance. Further, compared to Comparative Example 2, substantially equal results were achieved.

[0089] Consequently, the results in the above tables show that the thermosensitive recoding compositions prepared in Example 1 to Example 9 of the present invention have greatly improved background fog and reduction in stability of recorded image caused by bisphenol A as a conventional developer. Simultaneously, it could be understood that a drawback of N-(p-toluenesulfonyl)-N-(3-p-toluenesulfonyloxyphenyl), that is, poor color development sensitivity, may also be improved.

INDUSTRIAL APPLICABILITY

[0090] The thermosensitive recording material of the present invention may be used in a thermosensitive recording method, which is often adopted in the fields of facsimiles and computers, various measuring instruments, label blanks, receipt sheets, etc.