JPH03230992A - Thermal recording material - Google Patents

Abstract

PURPOSE:To reduce the lowering of whiteness with the elapse of time and to improve the fading due to a fluorescent pen by using a specific dye as a basic dye and using an antipyrine complex of zinc thiocyanate represented by formula (I). CONSTITUTION:2,2-bis{4-[6'-(N-cyclohexyl-N-methylamino)-3'- methylspiro[phthalide-3,9'-xanthene]-2'-ylamino]phenyl}propane is contained in a recording layer as a basic dye and an antipyrine complex of zinc thiocyanate represented by formula [l] is contained as a coupler. As a specific coupler, the antipyrine complex of zinc thiocyanate is used but other coupler can be together used within a range not preventing effect.

Description

Detailed Description of the Invention: "Industrial Application Field" The present invention relates to a heat-sensitive recording medium, and particularly to a heat-sensitive recording medium that does not cause a decrease in whiteness in blank areas and can stably maintain a recorded image. It is.

``Prior Art'' Conventionally, heat-sensitive recording materials utilize a coloring reaction between a colorless or light-colored basic dye and an organic or inorganic coloring agent to obtain a recorded image by bringing both coloring substances into contact with each other using heat. well known.

Along with the remarkable progress of thermal recording methods, its application fields and forms have diversified, and it has become not only a recording medium for thermal facsimiles and thermal printers, but also a POS (POS).
Point of 5ales) Its use in new applications such as labels is rapidly increasing.

However, these heat-sensitive recording materials generally have drawbacks such as fogging due to the influence of solvents and the like, and recorded images changing and discoloring. For example, depending on the type of highlighter used for line marks, the image may fade significantly, and attempts have been made to improve this drawback by using, for example, an antipyrine complex of zinc thiocyanate as a coloring agent. However, when such a coloring agent is used, the brightness of the recording medium decreases over time, and satisfactory results are not always obtained.

``What the invention seeks to solve □ Section BJ The present invention provides a heat-sensitive recording medium that exhibits little reduction in whiteness over time and effectively improves storage stability, especially fading caused by highlighters used for line marks. The purpose is to

``Means for Solving the Problems'' The present inventors have developed a thermosensitive recording medium in which a recording layer containing a colorless or light-colored basic dye and a coloring agent that changes color upon contact with the dye is provided on a support. In the recording layer, 2,2-bis(1-(6'-(N-cyclohexyl-N-methylamino)-3'-methylspiro[phthalide-3°9'-xanthine]) was added as a basic dye. It has been discovered that the above object can be achieved by containing -2'-ylamino]phenyl)propane and an antipyrine complex of zinc thiocyanate represented by the general formula (1) as a coloring agent. It was completed.

"Function" The present invention uses 2,2-bis(4[6'
-(N--cyclohexyl-N-methylamino)-3'
-Methylspiro(phthalide-3,9'xanthine)-2
'-ylaminocophenyl)propane is used, and the above-mentioned antipyrine complex of zinc thiocyanate is used as a coloring agent, which is an important feature.
By using the above-mentioned specific dye as a basic dye, despite using antipyrine complex of zinc thiocyanate, there is little decrease in whiteness over time, and it is used for preservation, especially for line marks. Fading caused by highlighters can be improved very effectively.

As mentioned above, in the present invention, a specific basic dye is used, but other basic dyes can also be used in combination as long as the effects of the present invention are not impaired. Examples of such basic dyes include the following.

3.3-bis(p-dimethylaminophenyl) 6-dimethylaminophthalide, 3.3-bis(P dimethylaminophenyl) phthalide, 3-(p-dimethylaminophenyl)-3-(1',2-dimethyl indole-3-yl)
Phthalide, 3-(p-dimethylaminophenyl)-1-
(2-methylindol-3-yl)phthalide, 3.3
-bis(1,2-dimethylindol-3-yl)5-
Dimethylaminophthalide, 3,3-bis(12-dimethylindol-3-yl)-6-dimethylaminophthalide, 33-bis(9-ethylcarbazol-3-yl)
-6-dimethylaminophthalide, 3.3-bis(2-phenylindol-3-yl)-6-dimethylaminophthalide, 3-p-dimethylaminophenyl-3-(1-
Triallylmethane dyes such as methylpyrrol-3-yl)-6-dimethylaminophthalide, 4,4'bis-dimethylaminobenzhydrylhenzyl ether, N-halophenyl-leucoolamine, N-245-) Diphenylmethane dyes such as chlorophenyl leuco auramine, thiazine dyes such as benzoyl leucomethylene blue and p-nitropensoyl leucomethylene blue, 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-
Dinaphthopyran, 3-phenyl-spirodinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 3-methyl-naphtho-(6'-methoxybenzo)spiropyran, 3
- Spiro dyes such as provil-spirodihenzobilan,
Lactam dyes such as rhodamine B-anilinolactam, rhodamine (p-nitroanilino) lactam, rhodamine (0-chloroanilino) lactam, 3-dimethylamino-7-methoxyfluorane, 3-diethylamino-6
-methoxyfluorane, 3-diethylamino-7-methoxyfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-6,7-dimethylfluorane Oran, 3-(N-ethyl-p-)luidino)-7methylfluorane, 3-diethylamino-7-N-acetyl-N-methylaminofluorane, 3-diethylamino-7
-N-methylaminofluorane, 3-diethylamino-
7-dibenzylaminofluorane, 3-diethylamine-7-N-methyl-N-hensylaminofluorane, 3
-diethylamino-7-N-chloroethyl-N-methylaminofluorane, 3-diethylamino-7-N-diethylaminofluorane, 3-(N-ethyl P-toluidino)-6-methyl-7-phenylaminofluorane, 3 −
(N-ethyl-P-1-luidino)-6-methyl-7-
(p-)luidino)fluoran, 3-diethylamino-
6-Methyl-7phenylaminofluorane, 3-diethylamino-7-(2-carbomethoxy-phenylamino)fluorane, 3-(N-cyclohexyl-N-methylamino)-6-methyl-7-phenylaminofluoran Oran, 3-pyrrolidino-6-methyl-7-phenylaminofluorane, 3-piperidino-6-methyl-7-phenylaminofluorane, 3-diethylamino-6-methyl-7-xylidinofluorane, 3-diethylamino-7 -(0-
chlorophenylamino)fluoran, 3-dibutylamino-7-(o-chlorophenylamino)fluoran, 3
-pyrrolidino-6-methyl-7-T)-butylphenylaminofluorane, 3-diethylamino-7-(o-fluorophenylamino)fluoran, 3-dibutylamino-7-(0-fluorophenylamino)fluoran,
3-dibutylamino-6-methyl-7-phenylaminofluorane, 3-dibentylamino-6-methyl-7-
Phenylaminofluorane, 3-(N-methyl-Nn-
amyl)amino-6-methyl-7-phenylaminofluorane, 3-(N-ethyl-Nnamyl)amino-6
-Methyl-7-phenylaminofluorane, 1-(N-
Ethyl-N-isoamyl)amino-6-methyl-7-phenylaminofluorane, 3-(N-methyl-N-n-
hexyl)amino-6-methyl-phenylaminofluorane, 3-(N-ethyl-Nn-hexyl)amino-6-methyl-7-phenylaminofluorane 1.3
-(N=ethyl-N-β-ethylhexyl)amino-6
-Methyl-7-phenylaminofluorane, 3-(N-
Fluoran dyes such as ethyl-N-tetrahydrofurfuryl)amino-6-methyl-7-phenylaminofluorane, 1-(N-ethyl-N-cyclopentyl)amino-6-methyl-7-phenylaminofluorane, etc. .

Further, in the present invention, an antipyrine complex of zinc thiocyanate is used as a specific coloring agent, but it is also possible to use other coloring agents in combination as long as the effects of the present invention are not impaired. Examples of such coloring agents include the following.

Inorganic acidic substances such as activated clay, acpargite, colloidal silica, aluminum silicate, 4-tertbutylphenol, 4-hydroxydiphenoxide, α-naphthol, β-naphthol, 4-hydroxyacetophenol, 4. tert-octylcatechol, 2.2'
-dihydroxydiphenol, 4.4'-isopropylidene bis(2,= tert-butylphenol), 4
．． 4'-5ec-butylidene diphenol, 4-phenylphenol, 4,4' isopropylidene diphenol, 2,2-bis(4-hydroxyphenyl)-4-methylpenkune, 2,2'-methylenebis(4-chlorophenol) ), hydroquinone, 4.4'-cyclohexylidene diphenol, 4.4'-dihydroxydiphenyl sulfide, hydroquinone monobenzyl ether,
4-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,44'-trihydroxybenzophenone, 2,2'4,4'-tetrahydroxybenzophenone, dimethyl 4-hydroxyphthalate, methyl 4-hydroxybenzoate, 4-hydroxy propyl benzoate,
5ec-butyl 4-hydroxybenzoate, pentyl 4-hydroxybenzoate, 4-hydroxy0 phenyl benzoate, benzyl 4-hydroxybenzoate,
Tolyl 4-hydroxybenzoate, M-chlorophenyl 4-hydroxybenzoate, phenylpropyl 4-hydroxybenzoate, phenethyl 4-hydroxybenzoate, p-chlorobenzyl 4-hydroxybenzoate, p-methoxybenzyl 4-hydroxybenzoate, novolac Phenolic compounds such as type phenolic resins and phenolic polymers, benzoic acid, p-tert-butylbenzoic acid, trichlorobenzoic acid, terephthalic acid, 3-sec-butyl-4-hydroxybenzoic acid, 3-cyclohexyl-4-hydroxybenzoic acid , 35-dimethyl-4-hydroxybenzoic acid, 3-t
ert-butylsalicylic acid, 3-benzylsalicylic acid,
3-(α-methylbenzyl)salicylic acid, 3-chloro-
5-(α-methylbenzyl)salicylic acid, 3,5-di-tert-butylsalicylic acid, 3-phenyl-5-(α
, αdimethylbenzyl)salicylic acid, 3,5-di-αmethylbenzylsalicylic acid, 4-(3-p-)lylsulfonylprobyloxy)salicylic acid, etc., 4,4'-dihydroxydiphenylsulfone, 4 -Hydroxy-4'-isopropyloxydiphenylsulfone, bis(3-allyl-4-hydroxyphenyl)sulfone, 4hydroxy-4'-methyldiphenylsulfone, 3,4-dihydroxydiphenylsulfone, 34-dihydroxy-4'-methyl 4- such as diphenyl sulfone
Hydroxydiphenylsulfone derivative, bis(3-te
rt-butyl-4-hydroxy-6-methylphenyl) sulfide, bis(2-methyl-4-hydroxy-5-t
Sulfide derivatives such as (ert-butylphenyl) sulfide, as well as these phenolic compounds, aromatic carboxylic acids, etc., such as zinc, magnesium, aluminum, etc.
Examples include organic acidic substances such as salts with polyvalent metals such as calcium, titanium, manganese, tin, and nickel.

In the present invention, the ratio of the specific basic dye and the coloring agent represented by the general formula [1] is not particularly limited, but -111Q is used per 100 parts by weight of the specific basic dye of the present invention. The coloring agent is used in an amount of about 100 to 700 parts by weight, preferably about 150 to 400 parts by weight.

Furthermore, a sensitizer can also be used in combination depending on the purpose. Specific examples of sensitizers include caproic acid amide, capric acid amide, palmitic acid amide, stearic acid amide, oleic acid amide, erucic acid amide, linoleic acid amide, linoleic acid amide, N-methylstearic acid amide, and stearic acid. Anilide, N-methyloleic acid amide, benzanilide, linoleic acid anilide, N-ethyl capric acid amide, N-butyl lauric acid amide, N-
Octadecylacetamide, N-oleacetamide, N-oleylbenzamide, N-stearylcyclohexylamide, polyethylene glycol, ■-benzyloxynaphthalene, 2hensyloxynaphthalene, 1-
Hydroxynaphthoic acid phenyl ester, 1,2-diphenoxyethane, 1,4-diphenoxybutane, 1.
2bis(3-methylphenoxy)ethane, 1,23bis(4-methoxyphenoxy)ethane, 1-phenoxy-2-(4-chlorophenoxy)ethane, 1-phenoxy-2-(4-methoxyphenoxy)ethane, ■−(
2-Methylphenoxy12-(4-methoxyphenoxy)ethane, terephthalic acid dibenzyl ester, oxalic acid dibenzyl ester, oxalic acid di(4-methylbenzyl) ester, p-benzyloxybenzoic acid benzyl ester, p-benzylbiphenyl , 1,5-bis(p-methoxyphenoxy)-3-oxa-penkune, 14-bis(2-vinyloxyethoxy)benzene, p-biphenyl-p-)lyl ether, hensyl p-methylthiophenyl ether, etc. Illustrated.

Among these sensitizers, 1,2-diphenoxyethane,
1.2-bis(3-methylphenoxy)ethane, ■-(
2-Methylphenoxy)-2-(4-methoxyphenoxy)ethane, oxalic acid dibenzyl ester, and oxalic acid di(4-methylbenzyl) ester, especially in combination with the specific substance of the present invention, have a high white color. It is more preferably used because it provides a heat-sensitive recording material that not only has excellent image stability but also has excellent recording density.

The amount of these sensitizers used is not particularly limited, but it is generally desirable to adjust the amount to about 4 parts by weight or less per 1 part by weight of the coloring agent.

Preparation of coating liquids containing these generally uses water as a dispersion medium,
ball mill, attritor, vertical or horizontal sand mill,
It is prepared by dispersing the dye, coloring agent, and thermofusible substance together or separately using a stirring/pulverizing machine such as a colloid mill.

Such coating liquids usually contain starches and binders as binders.
Hydroxyethylcellulose, methylcellulose, carboxydimethylcellulose, gelatin, casein, gum arabic, polyvinyl alcohol, styrene/maleic anhydride copolymer salt, styrene/acrylic acid copolymer salt, styrene/butadiene copolymer emulsion, etc. are all solids. It is blended in an amount of 10 to 40% by weight, preferably 15 to 30% by weight.

5 Furthermore, various auxiliary agents can be added to the coating liquid.
For example, dispersants such as dioctyl sulfosuccinate sodium salt, dodecylbenzenesulfonate sodium salt, lauryl alcohol sulfate sodium salt, fatty acid metal salts, ultraviolet absorbers such as triazole type, other antifoaming agents, fluorescent dyes, Examples include colored dyes.

In addition, to prevent sticking of the heat-sensitive recording material due to contact with recording equipment or recording heads, stearate wax, polyethylene wax, carnauba wax, microcrystalline wax, carboxy-modified paraffin wax, zinc stearate, calcium stearate, etc. are dispersed. Liquids, emulsions, etc. can also be added.

In addition, inorganic pigments such as kaolin, clay, talc, calcium carbonate, magnesium carbonate, fired clay, titanium oxide, diatomaceous earth, fine particulate anhydrous silica, activated clay, and styrene microballs are used to improve the adhesion of debris to the recording head. , Nylon Powder 6 Organic pigments such as polyethylene powder, urea/formalin resin filler, and raw starch granules can also be added.

Paper, plastic film, synthetic paper, etc. are used as the support. Further, the amount of coating liquid forming the recording layer applied to the support is not particularly limited, and is usually 2 to 12
g/rtr, preferably adjusted within a range of about 3 to 10 g/rTf.

Note that it is also possible to provide an overcoat layer on the recording layer for the purpose of protecting the recording layer, and it is of course also possible to provide a protective layer on the back side of the support or an undercoat layer on the support. In addition, various known techniques in the field of heat-sensitive recording material production, such as applying an adhesive to the back surface of the support, can be added.

"Example" The present invention will be described in more detail with reference to Examples below, but the present invention is of course not limited to these.

Further, unless otherwise specified, parts and percentages in the examples indicate parts by weight and percentages by weight, respectively.

7 Example 1 Earthenware 1 Natsume double-fired clay (trade name: Ansilex, apparent specific gravity:
0.22 g/afl, manufactured by Engelhard) 100
Styrene-butadiene copolymer latex (solid content: 5
0%) 15 parts polyvinyl alcohol 10% aqueous solution 30 parts water
A coating solution for an intermediate layer was prepared by mixing 200 parts of the above composition.

The obtained coating liquid was applied to high-quality paper at a rate of 50 g/board so that the coating amount after drying was 10 g/rrf, and dried to form an intermediate layer.

, 廿, ゛ of 8.11 ■ AW preparation 2.2-bis+4- (6'-(N-cyclohexyl-N-methylamino)-3'-methylspiro[phthalide-3,9'-xanthine]2'- ylamino]phenyl)propane 10 parts 8 1.2-bis(3-methylphenoxy)ethane

20 parts methylcellulose 5% water soluble? ffl
2nd part water
40 parts of this composition was milled using a horizontal sand mill to reduce the average particle size to μ.
It was ground to m.

■ Preparation of B solution Antipyrine complex of zinc thiocyanate 30 parts Methyl cellulose 5% aqueous solution 40 parts water
20 parts of this composition was ground in a horizontal sand mill until the average particle size was 2 μm.

■ Formation of recording layer 90 parts of liquid A, 90 parts of liquid B, silicon oxide pigment (oil absorption 180 parts)
m1/loog), 20 parts of a 20% zinc stearate dispersion, 150 parts of a 20% oxidized starch aqueous solution, and 28 parts of water were mixed and stirred to prepare a recording layer coating liquid. The resulting coating liquid was applied onto the intermediate layer at a dry weight of 5.0 g/po and dried to obtain a heat-sensitive recording paper.

Examples 2 to 4 In the preparation of Solution A of Example 1, 1-(2-methylphenoxy)-2-(4-methoxyphenoxy)ethane was used instead of 20 parts of 1.2-bis(3-methylphenoxy)ethane. 20 parts (Example 2), 20 parts of oxalic acid dibenzyl ester (Example 3), 10 parts of 1,2-bis(3-methylphenoxy)ethane and 10 parts of oxalic acid di(4-methylhensyl) ester (Example) A thermosensitive recording paper was obtained in the same manner as in Example 1 except that each of 4) was used.

Example 5 In the preparation of Solution B in Example 1, 30 parts of antipyrine complex of zinc thiocyanate and 25 parts of 4-hydroxy-4'-isopropyloxydiphenyl sulfone were used instead of 30 parts of antipyrine complex of zinc thiocyanate. A thermosensitive recording paper was obtained in the same manner as in Example 1.

Comparative Example 1 In preparing liquid A of Example 1, 2,2-bis(4-(6
' -(N-cyclohexyl-N-methyl0 amino)-3'-methylspiro[phthalide-3゜9'-
A thermosensitive recording paper was obtained in the same manner as in Example 1, except that 3-dibutylamino 6-methyl-7-phenylaminofluoran was used instead of xanthinecy-2'-ylamino]phenyl}propane.

Comparative Example 2 In preparing liquid A of Example 3, 2.2-bis(4-[6
' -(N-cyclohexyl-N-methylamino)-3
'-Methylspiro [phthalide-3゜9'-xanthine]
-2'~ylamino]phenyl)propane instead of
3-dibutylamino 7-(o-chlorophenylamino)
A thermosensitive recording paper was obtained in the same manner as in Example 1 except that fluoran was used.

Comparative Example 3 In preparing liquid A of Example 5, 2.2-bis(, l (
6'-(N-cyclohexyl-N-methylamino)-
Same as Example 1 except that 3-dibutylamino 6-methyl-7-phenylaminofluorane was used instead of 3'-methylspiro[phthalido-39'-xanthinecy-2'-ylamino]phenyl)propane. A thermosensitive recording paper was obtained.

Reference Example 1 A thermosensitive recording paper was obtained in the same manner as in Example 1 except that 4,4'-isopropylidene diphenol was used in place of the antipyrine complex of zinc thiocyanate in the preparation of Solution B in Example 1.

The nine types of heat-sensitive recording paper thus obtained were evaluated by the following evaluation method.

[Color density] Kyocera simulator (voltage: 16 V, ha/lz
Cycle: 0 during pulse using 5m 5ec)
．． Recording was performed at 5 m5 ec, and the color density of the resulting recorded image was measured using a Macbeth reflection densitometer (model RD-914, manufactured by Macbeth), and the results are shown in Table 1.

[Whiteness over time]

The change in whiteness of the white paper area over time (-weeks) was measured using a Hunter whiteness meter, and the rate of decrease in whiteness is shown in Table 1.

[Image fading] The recorded area was marked with a zebra highlighter (brown), and the fading state was observed after 24 hours, and the results are also listed in Table 1. The evaluation criteria for the fading state were as follows.

"Evaluation Criteria" ○: No discoloration △: Slight discoloration, but no practical problem ×: Strong discoloration, practical problem "Effect" As is clear from the results in Table 1, the thermal recording material of the present invention has It was an excellent recording material that had excellent stability in the blank area and did not fade due to the fluorescent pen used for in-marking.

No. table

Claims (1)

[Scope of Claims] A thermosensitive recording material in which a recording layer containing a colorless or light-colored basic dye and a coloring agent that develops a color upon contact with the dye is provided on a support, in which the recording layer contains: As a basic dye 2
,2-bis{4-[6'-(N-cyclohexyl-N-
methylamino)-3'-methylspiro[phthalide-3,
9'-xanthene]-2'-ylamino]phenyl}propane, and as a coloring agent, the following general formula [I]
A heat-sensitive recording material characterized by containing an antipyrine complex of zinc thiocyanate represented by: ▲There are mathematical formulas, chemical formulas, tables, etc.▼〔I〕