JPS58224787A - Heat-sensitive recording material - Google Patents

Abstract

PURPOSE:To produce a heat-sensitive recording material having a high resistance to fading of recorded images even under low-temperature conditions and also having a high-speed recording adaptability, by providing a recording layer containing a basic dye, hydroquinone monobenzyl ether, and a specific compound on a support. CONSTITUTION:A recording layer containing a colorless or light-color basic dye (e.g., a triarylmethane dye), hydroquinone monobenzyl ether, and one or more of the compounds of formula I [wherein R1 and R2 are each a C1-C8 alkyl, phenyl substituted with Cl, OH, and a C1-C8 alkoxyl, or benzyl having the same substituent as that of phenyl] or formula II (wherein R5, R6, and R7 are each H, Cl, OH, a C1-C12 alkoxyl, phenoxy, or benzyloxy) is provided on a support to obtain an objective recording material. As the compounds of formulas I and II, dimethyl 4-hydroxy phthalate and 2,4-dihydroxybenzophenone are preferably cited.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-sensitive recording medium, particularly having high-speed recording suitability,
The present invention also relates to a heat-sensitive recording material in which a recorded image is resistant to fading.

Conventionally, a color reaction between a colorless or light-colored basic dye and an organic or inorganic coloring agent is used to produce both full-color gtI by heat.
A thermosensitive recording material in which a recorded image is obtained by contacting J-quality materials is well known.

Recently, with the remarkable progress in thermal recording methods, thermal faxes, thermal printers, etc. that use thermal paper have become faster.A thermal fax machine can print an A4 size paper in 20 seconds, and a thermal printer can print 120 characters/sec or more. Recording speed is possible. As the speed of the hardware field increases, the thermal recording media used also have excellent recording sensitivity (dynamic recording characteristics) and there is no static recording in the low temperature range (60 to 70 degrees Celsius). In addition, characteristics such as no recording breakage (billing) due to adhesion of dust are required.

As a conventionally known highly sensitive heat-sensitive recording medium, there is one in which a dye, a phenol compound such as bisphenol A, and a sensitizer such as stearic acid amide are combined. In such a highly sensitive heat-sensitive recording medium, the recording layer usually contains one part dye to one part sensitizer or phenol compound. However, as the recording sensitivity of such conventional heat-sensitive recording media increases (as the recording sensitivity increases, it conversely decreases in the low-temperature range (60 to 60℃).
There is also the disadvantage that a so-called static recording appears at a temperature of 70°C. Furthermore, since the amount of sensitizer is large, piling is also poor. Under these circumstances, there is currently a need for the development of a quality-balanced thermal recording medium suitable for high-speed recording.

Therefore, in order to obtain a heat-sensitive recording medium that can be passed through high-speed recording hardware, the present inventors extensively investigated the field of coloring agents, and found that hydroquinone monobenzyl (3) ether is suitable for high-speed recording. It was discovered that

Although it is not possible to accurately understand the reason why hydroquinone monobenzyl ether is suitable for high-speed recording,
Since this substance itself has good crystallinity, it exhibits sharp dissolution coloring properties, and in addition, it is thought that the low melting point of around 120° C. is the reason for its high sensitivity coloring.

Since hydroquinone monobenzyl ether has such physical properties, a sensitizer is not required when using it as a coloring agent for a heat-sensitive recording medium. Therefore, the amount of melting during recording is This means that less amount is required, which is naturally effective in terms of piling.

However, hydroquinone monobenzyl ether, which has such characteristics, also exhibits color-forming and decolorizing reactions when it interacts with dyes in relation to temperature, so it is suitable for thermal recording materials. It is difficult to immediately put it into practical use as a coloring agent for commercial use.

(4) Therefore, the present inventors solved the decolorization of recorded images by combining hydroquinone monobenzyl ether with a colorless or light-colored basic dye, and demonstrated the physical properties of this coloring agent. As a result of research on the development of a water-repellent thermosensitive recording medium, we found that in addition to the combination of hydroquinone monobenzyl ether and a colorless or light-colored basic dye, the following general formula (1
) or (n), the inventors have found that this object can be achieved by using at least one of the compounds represented by (n) in combination.

〇〇 (In the formula, Rr and Rz each represent a hydroxyl group or a flucoxyl group at C!~2 to the flukichlorine atom of 01 to 2.) (5) [In the formula, Rr, R4, and R7 each represent a hydrogen atom or a chlorine atom. Although it is not clear why the thermochromic properties of hydroquinone-monobenzyl ether are eliminated by the combined use of this compound (representing a hydroxyl group, an alkoxyl group of 07 to a phenoxy group or a benzyloxy group), It is thought that the cause of the discoloration is that the coloring reaction caused by melting due to heating recrystallizes as the temperature decreases, and it is thought that the combination of the above compounds may have the effect of preventing recrystallization. It will be done.

Various kinds of colorless or light-colored basic dyes are known to form the recording layer of the heat-sensitive recording medium according to the present invention, and the following are exemplified.

3.3-bis(p-dimethylaminophenyl)=6-dimethylaminophthalide, 3.3-bis(p(6)=dimethylaminophenyl)phthalide, 3-(p-dimethylaminophenyl)-3- (1,2-dimethylindol-3-yl)phthalide, 3-(p-dimethylaminophenyl)-3-(2-methylindol-3-yl)
Phthalide, 3.3-bis(l,2-dimethylindol-3-yl)-5-dimethylaminophthalide, 3.3.
-bis(1゜2-dimethylindol-3-yl)-6
-dimethylaminophthalide, 3.3-bis(9-ethylcarbazol-3-yl)-6-dimethylaminophthalide, 3.3-bis(2-phenylindol-3-yl)-6-dimethylaminophthalide 3-p-dimethylaminophenyl-3-(l-methylvirol-3-yl)
-Triallylmethane dyes such as 6-dimethylaminophthalide, 4,4'-bis-dimethylaminobenzhydrylbenzyl ether, N-herophenyl leucoauramine, N-2,4,5-Trsu' Diphenylmethane dyes such as 70-lophenylleucoauramine, thiazine dyes such as benzoylleucomethylene blue, p-nitropenzoyluro(7) and icomethylene blue, 3-methyl-
Spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3-phenyl-spiro-dinaphthopyran, 3
- Spiro dyes such as benzyl-spiro-dinaphthopyran, 3-methyl-naphtho(6'-methoxybenzo)spiropyran, 3-propyl-spiro-dibenzobilane, rhodamine-B-anilinolactam, rhodamine(p-nitroanilino)lactam , lactam dyes such as rhodamine (0-chloroanilino)lactam, 3-dimethylamino-7-methoxyfluoran, 3-diethylamino-6-
Methoxyfluorane, 3-diethylamino-7-methoxyfluorane, 3-diethylamino-7-lyrolofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-6,7-dimethylfluorane, 3-(N-ethyl-P-)luidino)-7-methylfluorane, 3-diethylamino-7-N-acetyl-N-methylaminofluorane, 3-diethylamino-? -N-methylaminofluorane (8), 3-diethylamino-7-sibenzylaminofluorane, 3-diethylamino-? -N-methyl-N-benzylaminofluorane, 3-diethylamino-? -N-
Chloroethyl-N-methylaminofluorane, 3-diethylamino-? -N-diethyl minofluorane, 3-
(N-ethyl-p-1luidino)-6-methyl-7-phenylaminofluorane, 3-(N-ethyl-p-toluidino)-6-methyl-1-<p-toluidino)fluorane, 3-diethylamino 6-methyl-phenylaminofluorane, 3-diethylamino-7-(2-carbomethoxy-phenylamino)fluora-7,3-(
N-cyclohexyl-N-methylamino)-6-methyl-7-phenylaminofluorane, 3-pyrrolidino-6
-Methyl-7-phenylaminofluorane, 3-piperidino-6-methyl-7-phenylaminofluorane, 3
-diethylamino-6-methyl-7-xylidinofluorane, 3-diethylamino-7-(o-chlorophenylamino)fluorane, 3-dibutyl(9) amino-? Fluoran dyes such as -(0-chlorophenylamino)fluoran, 3-pyrrolidino-6-methyl-7-p-butylphenylaminofluoran, etc.

The heat-sensitive recording material of the present invention comprises a basic dye as described above, hydroquinone monobenzyl ether as a coloring agent, and a compound represented by the following general formula or (M) [where R1 and RJ are (10) In formula C, R5, R6 and R7 are each a hydrogen atom, a chlorine atom, a hydroxyl group, or an alkoxyl group of Ct~/2, respectively. , represents a phenoxy group or a benzyloxy group! ! ! It has an important feature in that it is provided with a recording layer containing such a general formula] or (
Among the compounds represented by n), more preferably used compounds include the following general formula (I[+3 or (IV
)・Compounds represented by:

[In the formula, Rθ and R<? each represents an alkyl group of Cl-3.] [In the formula, Rto represents a hydroxyl group, an alkoxyl group of Cl-/2, a phenoxy group, or a benzyloxy group, R/1(1
1) and Rr2 are each hydrogen atom, chlorine atom, hydroxyl group or C? -tz alkoxyl group) Furthermore, among the compounds represented by the general formula (I) or (IV), particularly preferably used compounds are specifically exemplified as follows: 4-hydroxydimethylphthalate IP, 110
°C4-hydroxydiethyl phthalate at, 65
℃4-Hydroxydimethylisophthalate 1.98℃4
-Hydroxydiethylisophthalate-p, 55°C2.
4-dimethoxybenzophenone 145℃2.4
．． 4'-) Lihydroxybenzophenone mp-200℃ 2.2',4.4'-Tetrahydroxybenzophenone Town, 195℃2-
Hydroxy-4-methoxybenzophenone + sp-65
°C 2-Hydroxy-4-methoxy-4'-chlorobenzophenone -p-114 °C2.
2'-dihydroxy-4-methoxybenzophenone
5p-70℃(12) 2.2'~dihydroxy-4,4'-dimethoxybenzophenone 1.130℃2-hydroxy-4-n-octoxybenzophenone
mp-49℃2-hydroxy-4
-n-dodecyloxybenzophenone
Sodium P-52℃ 2-Hydroxy-4-benzyloxybenzopheno 7
Examples include 5p-115°C.

In the present invention, hydroquinone mixed in the recording layer
The ratio of monobenzyl ether is i00 to 700 parts by weight, preferably 150 parts by weight, per 100 parts by weight of the basic dye.
~400 parts by weight is blended.

Also ~ the general formula (1), (11), (it3 or [■
] The amount of at least one compound represented by the following formula is generally 1 to 200 parts by weight, preferably 10 parts by weight, per 100 parts by weight of hydroquinone monobenzyl ether.
- It is desirable that ~200 parts by weight be blended.

(13) To prepare coating liquids containing these basic dyes, hydroquinone monobenzyl ether, and the compound represented by the above general formula, water is generally used as a dispersion medium, and a stirring/pulverizing machine such as a pormill, attritor, or sand grinder is used. It is prepared as a coating liquid by dispersing dyes, coloring agents, etc.

Such coating fluids contain starches and other suitable binders.
Hydroxyethylcellulose, methylcellulose, carboxymethylcellulose, gelatin, casein, gum arabic, polyvinyl alcohol, styrene-maleic anhydride copolymer salt, styrene-acrylic acid copolymer salt,
A styrene-butadiene copolymer emulsion or the like is used in an amount of 10 to 40% by weight, preferably 15 to 30% by weight of the total solid content. Furthermore, various auxiliary agents can be added to the coating liquid.

For example, dispersants such as sodium dioctyl sulfosuccinate, sodium dotecylbenzenesulfonate, sodium lauryl alcohol sulfate, fatty acid metal salts, (14) ultraviolet absorbers such as triazoles, other antifoaming agents, and fireflies. Examples include light dyes and colored dyes. In addition, to prevent sticking when the heat-sensitive recording material comes into contact with a recording device or recording head, a dispersion or a dispersion of stearic acid, polyethylene, carnauba wax, paraffin wax, zinc stearate, calcium stearate, ester wax, etc. is added to the paint. Emulsions and the like can also be added. Kaolin, clay, talc,
Inorganic pigments such as calcium carbonate, calcined clay, titanium oxide, diatomaceous earth, fine particulate anhydrous silica, and activated clay can also be added.

If necessary, stearic acid amide, stearic acid methylene bisamide, oleic acid amide, palmitic acid amide, matcha oleic acid amide, coconut fatty acid amide, etc. can also be added as a sensitizer.

Furthermore, it is also possible to add a common coloring agent such as a phenol type to the extent that it does not impede the effects of the present invention.

(15) As the support, paper, plastic film, synthetic paper, etc. can be used, but paper is most preferably used in terms of cost, coatability, etc. The amount of the coating liquid forming the recording layer to be applied to the support is not particularly limited, but is usually 2 to 12 g/m' in terms of dry weight, preferably 3 to 10 g/J.
is within the range of

The heat-sensitive recording material of the present invention thus obtained has suitability for high-speed recording, can eliminate the tendency of the recorded image to fade even when the temperature decreases, and has excellent properties in terms of dregs adhesion to the recording needle (piling). have.

The present invention will be described in more detail with reference to Examples below, but it is of course not limited thereto.

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

Example 1 ■ Preparation of liquid A 3-(N-cyclohexyl-N-methylamino)-6-
Methyl-7-phenylaminofluorane
10 parts (16) 5% methylcellulose aqueous solution 20 parts water
10 parts of this composition was ground with a sand grinder until the average particle size was 3 μm.

■ Preparation of B solution Hydroquinone monobenzyl ether 20 parts 4-hydroxydimethyl phthalate 15 parts Methyl cellulose 5%
Aqueous solution 70 parts water
30 parts of this composition was ground with a sand grinder until the average particle size was 3 μm.

■ Formation of recording layer 40 parts of liquid A, 135 parts of liquid B, silicon oxide pigment (oil absorption 18
0ra! /100g), 100 parts of 2°9S oxidized starch aqueous solution, and 70 parts of water were mixed and stirred. The obtained coating liquid was applied to a base paper of 50 g/n (2 g/n) and dried to give a coating amount of 7 glof after drying to obtain thermal recording paper A.

Example 2 ■ Liquid A Sekisei (17) 3-(N-ethyl-p-)luidino)-6=methyl-7
-Phenylaminofluoride 210 parts Methylcellulose 5% aqueous solution 20 parts Water
10 parts of this composition was ground with a sand grinder to an average particle size of 3 μm.

■ Preparation of liquid B: 20 parts of hydroquinone monobenzyl ether, 20 parts of 2,4-dihydroxybenzophenone, and 5% of methylcellulose.
Aqueous solution 80 parts water
30 parts of this composition was ground with a sand grinder so that the average particle size was 3 μm.

■ Formation of recording layer 40 parts of liquid A, 150 parts of liquid B, silicon oxide pigment (oil absorption 18
0m&/100g) 30 parts, 20% oxidized starch aqueous solution 10
0 parts and 100 parts of water are mixed and stirred. The obtained coating liquid was applied in the same manner as in Example 1 to obtain a heat-sensitive recording paper.

(18) Example 3 Same as Example 2 except that 10 parts each of 2,4-dihydroxybenzophenone and 4-hydroxydimethyl phthalate were used instead of 20 parts of 2,4-dihydroxybenzophenone in the preparation of Solution B. A thermosensitive recording paper was obtained in exactly the same manner.

Example 4 In the preparation of Solution B, 10 parts each of 2.4-dihydroxybenzophenone and 2-hydroxy-4-benzyloxybenzophenone were used instead of 20 parts of 2.4-dihydroxybenzophenone. A thermosensitive recording paper was obtained in exactly the same manner as in Example 2.

Comparative Example I A thermosensitive recording paper was obtained in exactly the same manner as in Example 1 except that 4-hydroxydimethyl phthalate was not used in the preparation of liquid B.

Comparative Example 2 A thermosensitive recording paper was obtained in the same manner as in Example 2 except that 2,4-dihydroxyben(19)siphenon was not used in the preparation of liquid B.

The six types of thermal recording paper thus obtained were recorded using a 5J thermal facsimile (Hitachi HIFAX-700 model).
Macbeth density needle (RD-1)
The results are shown in Table 1.

Furthermore, after this recording, the thermal paper was left at a high temperature for 24 hours, and then the color density (D) was measured again using a Macbeth density needle. And, color density residual rate (%) = <Dz/Dl)xto.

The results are listed in Table 1.

(20) Table 1 As is clear from the results shown in Table 1, the heat-sensitive recording material of the present invention was a recording material that had excellent recording sensitivity, improved print decoloration phenomenon, and excellent high-speed recording suitability.

Patent applicant: Kanzaki Paper Co., Ltd. (21)

Claims (1)

[Claims] (1) A support is provided with a recording layer containing a colorless or light-colored basic dye, hydroquinone monobenzyl ether, and at least one of the compounds represented by the following general formula (1) or [i). A thermosensitive recording material characterized in that: [In the formula, R7 and R2 each represent a C1-5 atom, a chlorine atom, a hydroxyl group, or a Cr-tr alkoxyl group.] (1) [In the formula, Rs, R6 and R7 are each a hydrogen atom,
Chlorine atom, hydroxyl group, Ct-tz alkoxyl group, °
Indicates a phenoxy group or a benzyloxy group, ]