JPH0159917B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to the improvement of a color-forming layer of a heat-sensitive recording material containing a colorless or light-colored color-forming dye and an organic acidic substance that causes the dye to develop color when heated. The object of the present invention is to provide a heat-sensitive recording material with excellent heat-sensitive performance and having a color-developing layer with a high temperature. That is, the present invention provides a heat-sensitive recording material having a heat-sensitive color-forming layer containing a colorless or light-colored color-forming dye and an organic acidic substance, in which the color-forming layer contains 4-benzoyloxy-2,2,6,6
-tetramethylpiperidine or/and bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate It is a heat-sensitive recording material characterized in that it also contains. A heat-sensitive recording material, especially a color-forming dye that is colorless or light in color (hereinafter referred to as a "color-forming dye") that develops color upon contact with an electron-accepting substance, and an electron-accepting substance (a color developer) that develops the color. ) has recently been widely used in facsimile machines, and as facsimile speeds have increased, thermal recording paper has developed a coloring layer that produces rich colors at relatively low temperatures in order to improve the thermal performance of thermosensitive recording paper. There is a strong demand for the development of For this reason, higher fatty acid amides have conventionally been widely used as sensitizers for such color-forming systems, and dimethyl terephthalate has also begun to be used as a sensitizer. The antioxidant bis(3-tert-butyl-5-ethyl-2-hydroxyphenyl)methane is also attracting attention as a substance with sensitizing effects, but these have not yet fully met the above requirements. It's not a thing. The present inventors discovered that 4-benzoyloxy-2, which has been reduced as a compound for preventing photodeterioration of synthetic resins,
The present invention was completed by discovering that 2,6,6-tetramethylpiperidine and bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate exhibit extremely excellent sensitizing effects in the above coloring system. This is what I did. That is, when these piperidine compounds are added to the above-mentioned coloring system, it is possible to increase the density of saturated coloring by heating and lower the temperature at which saturated coloring occurs. Another major feature of these two types of piperidine compounds used in the present invention is that they only need to be added in smaller amounts to the coloring system than known sensitizing substances. In other words, known sensitizing substances require addition of approximately the same amount as the color-forming dye used in the color-forming system, but the piperidine compound of the present invention is added in an amount of 0.5 part or 0.2 part to 1 part of the color-forming dye. The following additions are sufficient. This is not only economically advantageous, but also greatly helps in preventing the phenomenon of "staking" (peeling of the coating film) caused by the thermal head of a thermal printer. 4-benzoyloxy-2 used in the present invention,
2,6,6-tetramethylpiperidine (hereinafter referred to as "BTMP") and bis(2,2,6,
Higher fatty acid amide (sensitizer A), bis(3-tertiary butyl-5- Ethyl-2
-Hydroxyphenyl)methane (sensitizer B) or dimethyl terephthalate (sensitizer C) is shown in the table below. Table 1 shows the coated surface of heat-sensitive recording paper manufactured by coating and drying a coating solution containing a combination of benzyl-4-hydroxybenzoate, an organic acid substance, and the color-forming dye listed in the table, with various sensitizers added. 90℃,
Table 2 shows a comparison of color density at each temperature of 100°C and 110°C, and Table 2 shows the case where bis(p-hydroxyphenyl)dimethylmethane (bisphenol A) was used as the organic acidic substance.
These two types of organic acidic substances are most commonly used as color developers for thermal recording paper. The measured values in Table 1 are Examples 1 to 4 and Comparative Example 1.
Table 2 shows the color density obtained by the experiment described in Table 2, and the measured values in Table 2 are those of Example 5.
and 6, which show the experimentally developed color density of Comparative Examples 3 and 4, and the larger the numerical value, the darker the color is. The filters used during the measurement were experiment numbers No. 1 to 13 and No. 20 to 29.
(These colors are black) is Ratten #106, experiment numbers No. 14-19 and No. 30-
32 (these colors are dark green) and Experiment Nos. 33 to 35 (these colors are blue) is Ratten #25.

【table】

【table】

【table】

[Table] Color-forming dye: Crystal violet lactone
33BTMP 0.2 1.17 1.27 1.27
34 TMPS 0.2 1.18 1.30 1.30
35 Sensitizer A 1.0 1.14 1.20 1.20
The measured values in these tables show that when the piperidine compound of the present invention is used as a sensitizer, color development at a relatively low temperature of 90° to 110°C and almost saturated color density can be obtained, and the density is higher than that of other sensitizers. It is clearly shown that the value is significantly higher than that obtained by the agent. It is also clear from these tables that it is sufficient to use a smaller amount than other sensitizers.
Experiment No. 24 shows that when the amount of other sensitizers, such as sensitizer A, is reduced to the same level as these piperidine compounds, the color density is extremely low. The usage ratio of the piperidine compound in the present invention is 0.05 to 1 part of the color-forming dye used in the color-forming system.
The amount is preferably 0.3 part, and although it is possible to use a larger amount, it is uneconomical since there is hardly any increase in the sensitizing effect associated with it, and when less than 0.02 part is used, almost no sensitizing effect is observed. These piperidine compounds can be used singly or in combination, and when used, they can be pulverized alone and combined with a color-forming dye and an organic acidic substance that have also been pulverized. Alternatively, it may be pulverized together with a color-forming dye or an organic acidic substance. Note that these piperidine compounds can also be used in combination with other types of sensitizers. The finely pulverized piperidine compound organic acid substance and color-forming dye are dispersed and mixed in an aqueous solution of a water-soluble binder to form a suspension, which is then applied to paper or a suitable support and dried. A heat-sensitive recording material can be produced by. In addition to the above-mentioned benzyl-4-hydroxybenzoate and bisphenol A, for example, the following compounds can be used as the organic acidic substance in the present invention, but the invention is not limited to these. 4-phenylphenol, 2-
Bromo-4-phenylphenol, 4-cyclohexylphenol, 2-cyclohexylphenol, 4,4'-biphenol, 4-hydroxydiphenoxide, methyl-4-hydroxybenzoate, butyl-4-hydroxybenzoate, pentyl-4- Hydroxybenzoate, phenyl-
4-Hydroxybenzoate, nuclear substituted benzyl-
4-hydroxybenzoate, phenyl gallic acid ester, monobenzyl terephthalate, monobenzyl isophthalate, 4-hydroxyacetopheno, 4-hydroxypropiophenone, 4-hydroxybenzophenone, 2,4-dihydroxybenzophenone, salicylic acid Anilide, 2,2'-
Dihydroxydiphenyl, 4,4'-cyclohexylidenephenol, 4,4'-pentylidenephenol, 4,4'-cyclohexylidene-bis(2-
isopropylphenol), 4-tertiary octylcatechol, 2,2'-methylene-bis(4-chlorophenol), 1,1'-methylene-bis(2-
naphthol), 4,4'-sec-butylidene diphenol, α-naphthol, β-naphthol, bis(4-hydroxyphenyl) sulfide, 2,
2'-bis(4-halofenol) sulfide,
2,2'-bis(4-halofenol) sulfoxide, 2,2'-bis(4-halofenol) sulfone, 2,4-bis(4-halo-2-hydroxyphenyl)-4-methylpentane, Novolac type phenolic resin. As the color-forming dye, for example, the following compounds can be used, but the invention is not limited to these. That is, examples of fluoran dyes include 3-N-methylcyclohexylamino-6-methyl-7-phenylaminofluoran, 3-pyrrolidino-6-methyl-7-phenylaminofluoran, and 3-piperidino-6-methyl- 7-phenylaminofluorane, 3-(N-ethyl-p-methylphenylamino)-6-methyl-7-phenylaminofluorane, 3-(N-ethyl-p-methylphenylamino)- 6-Methyl-7-p-methylphenylaminofluorane, 3-diethylamino-6-methyl-7-phenylaminofluorane, 3-diethylamino-6-methyl-7-chlorophenylaminofluorane, 3-diethylamino -7-dibenzylaminofluorane, 3-diethylamino-5-methyl-7-dibenzylaminofluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-methyl-7
-Chlorofluorane, 3-cyclohexylamino-6-chlorofluorane, 3-pyrrolidino-7-
Dibenzylaminofluorane, 3-pyrrolidino-
7-phenylaminofluoran, etc. Lactam dyes include 3,6-bis(diethylamino)fluoran.
N-phenyllactam, 3,6-bis(diethylamino)fluoran-N-chlorophenyllactam, etc. Triarylmethane dyes include 3,3-bis(p-dimethylaminophenyl)
-6-dimethylaminophthalide (crystal violet lactone), 3-(p-dimethylaminophenyl)-3-(1,2-dimethylindole-3
Diphenylmethane dyes include 4,4'-bis-diethylaminobenzhydrylbenzyl ether and N-halophenylleucoauramine; spiro dyes include 3-methyl-spiro-dinaphthopyran and 3-yl) phthalide; Examples include propyl-spiro-dibenzopyran. Of course, these color-forming dyes can be used alone or in combination of two or more. Examples of water-soluble binders include polyvinyl alcohol, hydroxyethyl cellulose, carboxymethyl cellulose, styrene-maleic anhydride copolymer salt, styrene-butadiene emulsion,
Vinyl acetate-maleic anhydride emulsion, polyacrylate, polyacrylamide, starches, casein, gum arabic, etc. can be used, but are not limited to these. The above suspension may further contain dispersants (e.g., sodium dioctylsuccinate, sodium dodecylbenzenesulfonate, sodium salts of lauryl alcohol sulfate, fatty acid metal salts, etc.), sensitizers (e.g., bis(tertiary butylphenol)-based compounds], desensitizers (e.g. aliphatic higher alcohols, solid polyhydric alcohols, polyethylene, glycols, guanidine derivatives, etc.), anti-stinging agents (e.g. stearic acid, zinc stearate,
Calcium stearate, carnauba wax,
paraffin wax, ester wax, etc.)
Fillers (e.g. clay, talc, kaolin, satin white, titanium oxide, calcium carbonate, magnesium carbonate, barium sulfate, magnesium silicate,
(aluminum silicate, etc.), antifoaming agents, polymeric light stabilizers, fluorescent brighteners, and the like. The above suspension is not only used in heat-sensitive recording materials, but also by coating it on a conductive layer supported on a support, as in, for example, Japanese Patent Publications No. 51-16154 or 1971-16155. By drying, an electrically conductive heat-sensitive recording material can be obtained. Example 1 An aqueous suspension of an organic acidic substance (liquid A), an aqueous suspension of a color-forming dye (liquid B), an aqueous suspension of a sensitizer (liquid C), and an aqueous suspension of a filler (liquid D) Four types of suspensions were prepared in the following manner. Solution A: Benzyl-4-hydroxybenzoate
10.5 g, 41.5 g of a 15% aqueous solution of polyvinyl alcohol (Kuraray Co., Ltd., "Kuraray-105"), 8.0 g of clay (Engelhard Co., Ltd., "UW-90"), and 40.0 g of pure water, together with 100 g of glass beads, 250 ml of polyethylene. Put it in a bottle, seal it tightly and attach it to the Red Devil paint conditioner, and use it 630 times/
After shaking for 8 hours at a vibration frequency of 1 minute, the glass beads were removed to obtain an aqueous suspension of benzyl-4-hydroxybenzoate with a particle size of 2-3 microns. Solution B: 3-N-methylcyclohexylamino-
6-Methyl-7-phenylaminofluorane 7.0
g, 15% of polyvinyl alcohol (same as above)
41.5g of an aqueous solution of
The mixture was placed in a polyethylene bottle, tightly capped, and shaken with a paint conditioner at a frequency of 630 vibrations/min for 5 hours, and the glass beads were removed to obtain an aqueous suspension of the fluoran compound (particle size 2 to 3μ). . Liquid C: 4-benzoyloxy-2,2,6,6
-Tetramethyl-piperidine (BTMP) 7.0g,
Put 41.5 g of a 15% aqueous solution of polyvinyl alcohol (same as above), 11.5 g of clay (same as above), and 40.0 g of pure water together with 100 g of glass beads into a 250 ml polyethylene bottle, seal the bottle, and use a paint conditioner 630 times/min. After shaking at a vibration frequency of 5 hours, the glass beads were removed to obtain an aqueous suspension of BTMP. Solution D: polyvinyl alcohol (same as above)
41.5g of 15% aqueous solution, 18.5g of clay (same as above)
and 40.0g of pure water with 100g of glass beads at 250
The mixture was placed in a ml polyethylene bottle, tightly stoppered, and shaken with a paint conditioner at a vibration frequency of 630 times/min for 5 hours, and the glass beads were removed to obtain an aqueous clay suspension. A liquid 10g, B liquid 5.0g, C liquid 0.5g and D liquid 4.5g
g were mixed and stirred for 20 minutes to prepare a coating solution.
This coating solution was applied to white base paper using wire rod No. 21, and dried at a temperature of 60° C. for 2 minutes to produce heat-sensitive recording paper. Further, a thermosensitive recording paper was produced in the same manner using 1.0 g of liquid C and 4.0 g of liquid D instead of 0.5 g of liquid C and 4.5 g of liquid D. These thermal recording papers were heated at 90°C, 100°C and
Both sides were heated for 5 seconds at a temperature of 110°C to develop color (black). The color density of the coloring surface was measured using a Macbeth reflection densitometer model RD-514. The results are shown in Table 1 as Experiment No. 1 and No. 2. Example 2 The same organic acidic substances and color-forming dyes as in Example 1 were used, and bis(2,2,6,
An experiment was conducted in the same manner as in Example 1 using 6-tetramethyl-4-piperidine) sebacate (TMPS). The results are shown in Table 1 for experiment numbers No. 3 and No. 4.
It was shown as Comparative Example 1 The same organic acidic substances and color-forming dyes as in Example 1 were used, and as sensitizers higher fatty acid amide (Nippon Kasei Co., Ltd., "Amide AP-1") (sensitizer A), bis(3 -tertiary butyl-5-ethyl-
An experiment similar to Example 1 was conducted using 2-hydroxyphenylmethane (sensitizer B) or dimethyl terephthalate (sensitizer C). The results are shown in Table 1 as Experiment No. 5, No. 6, and No. 7. In these experiments, 5.0 g of Solution C (aqueous suspension of sensitizer) was used, and Solution D (aqueous suspension of filler) was not used. Example 3 The organic acidic substance and sensitizer were benzyl-4-hydroxybenzoate and sensitizer as in Example 1.
An experiment similar to Example 1 was conducted using BTMP and 3-diethylamino-6-methyl-7-phenylaminofluoran as the color-forming dye.
The results are shown in Table 1 as Experiment No. 8 and No. 9. Also, as a coloring dye, 3-diethylamino-5
The results of a similar experiment using -methyl-7-dibenzylaminofluorane are shown in Table 1 as experiment numbers No. 14 and No. 15. Example 4 Example 3 was carried out using TMPS as the sensitizer and two chromogenic dyes as in Example 3.
conducted a similar experiment. The results are shown in Table 1 as experiment numbers No. 10, No. 11, No. 16, and No. 17. Comparative Example 2 An experiment similar to Example 3 was conducted using the same organic acidic substance and color-forming dye as in Example 3, and using Sensitizer B and Sensitizer C as sensitizers. In these experiments, 5.0 g of liquid C was used.
Solution D was not used. These results are shown in Table 1 as experiment numbers No. 12, No. 13, No. 18, and No. 19. Example 5 Example using bisphenol A as the organic acidic substance, 3-N-methylcyclohexylamino-6-methyl-7-phenylaminofluoran as the color-forming dye, and BTMP as the sensitizer. An experiment similar to 1 was conducted. The results are shown in Table 2 as experiment numbers No. 20 and No. 21. In addition, the results of experiments conducted in the same manner using TMPS as a sensitizer are shown in Experiment No. 22 and No. 23.
It was shown as Comparative Example 3 Using Sensitizer A and Sensitizer B as sensitizers, the results of an experiment similar to Example 5 are shown in Table 2 as experiment numbers No. 24, No. 25, and No. 26. Ta.
At this time, in experiment number No. 24, 1.0 g of liquid C and liquid D
Use 4.0g, and use liquid C for No.25 and No.26.
5.0g was used, and Solution D was not used. Example 6 Example 1 was carried out using bisphenol A as the organic acidic substance, 3-diethylamino-6-methyl-7-phenylaminofluoran as the color-forming dye, and BTMP or TMPS as the sensitizer. The results of similar experiments are shown in Table 2 with experiment numbers.
Shown as No. 27 and No. 28. Also, as a coloring dye, 3-diethylamino-5
Table 2 shows the results of a similar experiment using methyl-7-dibenzylaminofluorane and BTMP or TMPS as a sensitizer.
Shown as No. 30 and No. 31. In addition, the results of experiments conducted in the same manner as above using crystal violet lactone and two types of sensitizers are shown as experiment numbers No. 33 and No. 34. Comparative Example 4 Bisphenol A was used as the organic acidic substance, Sensitizer A was used as the sensitizer, and 3-diethylamino-6-methyl-7-phenylaminofluoran and 3-diethylamino-5- were used as the color-forming dyes. The results of an experiment similar to Example 1 using methyl-7-dibenzylaminofluorane or crystal violet lactone are shown in Table 2 with experiment numbers.
Shown as No. 29, No. 32 and No. 35. For these experiments, 5.0 g of an aqueous suspension of sensitizer A was used.
Solution D was not used.

Claims (1)

[Claims] 1. A heat-sensitive recording material having a heat-sensitive color-forming layer containing a colorless or light-colored color-forming dye and an organic acidic substance, in which the color-forming layer contains 4-benzoyloxy-2,
2,6,6-tetramethylpiperidine or/and bis(2,2,6,6-tetramethyl-4-
A heat-sensitive recording material characterized in that it also contains (piperidyl) sebacate.