JPH0777827B2 - Thermal recording material - Google Patents

Description

TECHNICAL FIELD The present invention relates to a heat-sensitive recording material, and more particularly to a heat-sensitive recording material excellent in color development.

[Prior art]

A general heat-sensitive recording material is a colorless or light-colored coloring dye such as leuco dye as a coloring agent on a support such as paper or film, and a phenolic compound (particularly bisphenol A) as a developer for coloring the coloring when heated. , A color-forming system composed of an acidic substance such as an organic acid, and further provided with a thermosensitive color-developing layer in which a binder, a filler, a sensitivity improver, a lubricant, and other auxiliary agents are dispersed, for example, Japanese Patent Publication No. Japanese Patent Publication No.45-14039,
It was introduced in Japanese Patent Laid-Open No. 48-27736 and is widely put to practical use. This type of heat-sensitive recording sheet obtains a color image by a momentary chemical reaction between a color-developing agent and a color-developing agent during heating (a thermal printer or a Facsimile having a built-in thermal head is used for heating). Therefore, compared to other recording materials, recording can be obtained in a short time with a relatively simple device without performing complicated processing such as development and fixing, there is little noise and environmental pollution, and cost is low. Due to its advantages such as low cost, it is useful for copying books, documents and the like, and is also useful as a recording material for various information and measuring instruments such as electronic calculators, facsimiles, telex and medical measuring instruments.

On the other hand, in recent years, along with the development of society, there has been an increasing demand for high speed recording and high density recording. For this reason, it is strongly desired to develop a recording material capable of coping with the speedup of the recording apparatus itself. The first method is to lower the melting point of the electron-accepting compound as a color developer to a practically acceptable level such as storage stability (for example, 80 to 120 ° C.), and set the melting start temperature with the leuco dye. It is to lower the speed and increase the speed. However, at present, it is difficult to control the melting point of a phenolic compound which is a color developing agent which is widely used in the field of thermal recording materials, and the phenolic compound itself becomes expensive and is not practical. The second method is, for example, JP-A-53-39139 and JP-A-53-26139.
As described in JP-A No. 53-5636, JP-A No. 53-11036, etc., various waxes, fatty acid amides, alkylated biphenyls, substituted biphenyl alkanes, coumarins, etc. in the thermosensitive coloring layer. There is a method of adding a low-melting point heat-melting substance such as diphenylamines as a sensitizer (or melting point depressant). However, it is hard to say that the heat-sensitive recording materials produced by these methods are still sufficient in terms of color density, color sensitivity, background whiteness and the like.

〔Purpose〕

An object of the present invention is to provide a heat-sensitive recording material which has sufficient color density and color sensitivity, is suitable for high-speed recording, and has a high degree of background whiteness and which is extremely practical.

〔Constitution〕

The heat-sensitive recording material of the present invention is a heat-sensitive recording material utilizing a color-forming reaction between a leuco dye and its color developer, and is characterized by using a triphenyl compound represented by the following general formula (I) as an auxiliary component. And

In the formula, R represents an alkyl group, X, Y and Z represent an alkyl group, X, Y and Z may be the same or different, l,
m and n each independently represent an integer of 0 to 3. The triphenyl compound represented by the general formula (I), which is used as an auxiliary component in the present invention, heats a widely used developer (electron-accepting compound) and leuco dye (electron-donating colorless dye). At this time, it has a high ability to dissolve, and by adjusting the melting point of the triphenyl compound used in combination, a heat-sensitive recording material having any sensitivity can be obtained.

The triphenyl compound used in the present invention preferably has a melting point of 40 to 150 ° C., and particularly preferably 50 to 120 ° C., from the viewpoint of storage stability and sensitivity as a thermosensitive recording material. Specific examples of the triphenyl compound of the present invention are shown below, but the present invention is not limited thereto.

The leuco dyes used in the present invention may be used alone or as a mixture of two or more, and as such leuco dyes,
What has been applied to this type of heat-sensitive material is arbitrarily applied, for example, triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, spiropyran-based, indolinophthalide-based dye leuco compounds are preferably used . Specific examples of such leuco dyes include those shown below.

3,3-bis (p-dimethylaminophenyl) -phthalide, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet red lactone), 3,3-bis ( p-Dimethylaminophenyl) -6-diethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide, 3,3-bis (p-dibutylaminophenyl) phthalide, 3-cyclohexyl Amino-6-chlorofluorane, 3-dimethylamino-5,7-dimethylfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benz Fluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3- (Np-tolyl-N-ethylamino) -6-methyl- -Anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 2- {N- (3'-trifluoromethylphenyl) amino} -6-diethylaminofluorane, 2- {3,6 -Bis (diethylamino) -9- (o-chloroanilino) xanthylbenzoic acid lactam}, 3-diethylamino-6-methyl-7- (m-trichloromethylanilino) fluorane, 3-diethylamino-7- (o-chloroanilino) Fluorane, 3-dibutylamino-7- (o-chloroanilino) fluorane, 3-N-methyl-N-isoamylamino-6-methyl-
7-anilinofluorane, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3- (N, N -Diethylamino) -5-methyl-7- (N, N
-Dibenzylamino) fluorane, benzoyl leuco methylene blue, 6'-chloro-8'-methoxy-benzoindolino-pyrrolispirane, 6'-bromo-3'-methoxy-benzoindolino-pyrrolispirane, 3- (2'-hydroxy) -4'-Dimethylaminophenyl) -3- (2'-methoxy-5'-chlorophenyl)
Phthalide, 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy-5'-nitrophenyl)
Phthalide, 3- (2'-hydroxy-4'-diethylaminophenyl) -3- (2'-methoxy-5'-methylphenyl)
Phthalide, 3- (2'-methoxy-4'-dimethylaminophenyl) -3- (2'-hydroxy-4'-chloro-5'-
Methylphenyl) phthalide, 3-morpholino-7- (N-propyl-trifluoromethylanilino) fluorane, 3-pyrrolidino-7-trifluoromethylanilinofluorane, 3-diethylamino-5-chloro-7- (N -Benzyl-trifluoromethylanilino) fluorane, 3-pyrrolidino-7- (di-p-chlorophenyl) methylaminofluorane, 3-diethylamino-5-chloro-7- (α-phenylethylamino) fluorane, 3 -(N-ethyl-p-toluidino) -7- (α-phenylethylamino) fluorane, 3-diethylamino-7- (o-methoxycarbonylphenylamino) fluorane, 3-diethylamino-5-methyl-7- (α -Phenylethylamino) fluorane, 3-diethylamino-7-piperidi Fluoran, 2-chloro-3-(N-Mechirutoruijino)-7-(p
-N-butylanilino) fluorane, 3- (N-benzyl-N-cyclohexylamino)-
5,6-benzo-7-α-naphthylamino-4′-bromofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3-N-ethyl-N- (2-ethoxypropyl) amino -6-Methyl-7-anilinofluorane, 3-N-ethyl-N-tetrahydrofurfurylamino-
6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-mesitidino-
4 ', 5'-benzofluorane and the like.

As the developer used in the present invention, various electron-accepting compounds, for example, phenolic compounds, thiophenolic compounds, thiourea derivatives, organic acids and metal salts thereof, are preferably applied. Here is an example:

4,4'-isopropylidene bisphenol, 4,4'-isopropylidene bis (o-methylphenol), 4,4'-secondary butylidene bisphenol 4,4'-isopropylidene bis (2-tert-butylphenol), 4 4,4'-cyclohexylidene diphenol, 4,4'-isopropylidene bis (2-chlorophenol), 2,2'-methylene bis (4-methyl-6-tert-butylphenol), 2,2'-methylene bis (4 -Ethyl-6-tert-butylphenol), 4,4'-butylidenebis (6-tert-butyl-2methyl)
Phenol, 4,4'-thiobis (6-tertbutyl-2-methyl) phenol, 4,4'-diphenol sulfone, 4,4'-diphenol fluphoxide, isopropyl P-hydroxybenzoate, P-hydroxy Benzyl benzoate, benzyl protocatechuate, stearyl gallate, lauryl gallate, octyl gallate, 1,7-bis (4-hydroxyphenylthio) -3,5-dioxaheptane, 1,5-bis (4-hydroxyphenylthio) -3-oxapentane, 1,3-bis (4-hydroxyphenylthio) -propane, 1,3-bis (4-hydroxyphenylthio) -2-hydroxypropane, N, N ' -Diphenylthiourea, N, N'-di (m-chlorophenyl) thiourea, salicylanilide, 5-chloro-salicylanilide, salicyl-o-chloroanilide 2-hydroxy-3-naphthoic acid, 2-hydroxy-1-naphthoic acid, 1-hydroxy-2-naphthoic acid, metal salts of hydroxynaphthoic acid such as zinc, aluminum and calcium.

In the present invention, in order to bond and support the leuco dye, the color developer and the auxiliary component on the support, various conventional binders can be appropriately used, and examples thereof include polyvinyl alcohol, starch and its derivatives, and methoxy. Cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, ethyl cellulose and other cellulose derivatives, sodium polyacrylate, polyvinylpyrrolidone, acrylic acid amide / acrylic acid ester copolymer, acrylic acid amide / acrylic acid ester / methacrylic acid terpolymer , Styrene / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate,
Water-soluble polymers such as gelatin and casein, polyvinyl acetate, polyurethane, styrene / butadiene copolymer,
Polyacrylic acid, polyacrylic acid ester, vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, ethylene / vinyl acetate copolymer, styrene / butadiene /
Acrylic copolymer latex can be used.

In the present invention, the leuco dye, the color developer, and the auxiliary component may be used, if necessary, in combination with an auxiliary additive component commonly used in this type of heat-sensitive recording material, such as a filler. In this case, as the filler, for example,
Calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay,
Inorganic fine powders such as talc and surface-treated calcium and silica, as well as organic fine powders such as urea-formalin resin, styrene / methacrylic acid copolymer and polystyrene resin can be mentioned.

The heat-sensitive recording material of the present invention is produced, for example, by applying a heat-sensitive layer-forming coating liquid containing the above-mentioned components onto a suitable support such as paper, synthetic paper, or plastic film, and drying. In this case, the leuco dye, the color developer, and the color-sensitivity increasing agent are appropriately used in amounts of 5 to 40% by weight, 20 to 60% by weight and 20 to 60% by weight, respectively.

〔effect〕

The heat-sensitive recording material of the present invention has improved sensitivity, is suitable for high-speed recording, has a high background whiteness, and is extremely highly practical.

〔Example〕

Next, the present invention will be described in more detail with reference to examples. The parts and% shown below are based on weight.

Example 1 [Liquid A] 3- (N-methyl-N-cyclohexylamino) -6-
Methyl-7-anilinofluorane 20 parts 10% aqueous solution of hydroxyethyl cellulose 20 parts Water 60 parts [B solution] Bisphenol A 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts [C solution] Triphenylmethyl methyl ether (Specific compound example No. 1
Compound) 20 parts Polyvinyl alcohol 10% aqueous solution 20 parts Water 60 parts [D solution] Calcium carbonate 20 parts Methylcellulose 5% aqueous solution 20 parts Water 60 parts Next, solution A 10 parts, solution B 30 parts, solution C 30 parts, D 20 parts of the solution and 10 parts of 20% aqueous solution of isobutylene-maleic anhydride copolymer were mixed to obtain a thermosensitive color forming layer forming solution, which had a basis weight of 50
After coating and drying on a quality paper of g / m ^{2 so} that the dry adhesion amount becomes 4 to 5 g / m ² , a thermosensitive coloring layer is provided, and then the surface of the layer is further adjusted so that the surface smoothness becomes 500 to 600 seconds. A thermosensitive recording material (a) was prepared by calendering.

Example 2 A thermosensitive recording material (b) was prepared in the same manner as in Example 1 except that the following solution [E] was used instead of the solution [C] in Example 1.
It was created.

[E] Liquid triphenylmethyl methyl ether (Compound Specific Example No. 2
Compound) 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts water 60 parts Example 3 Thermal recording in the same manner as in Example 1 except that the following [F] solution was used instead of the [C] solution of Example 1. Material (C)
It was created.

[F liquid]

(Diphenyl-p-trimethyl) ethyl ether (compound of compound example No. 5) 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts water 6 parts Example 4 The following [G] instead of the [C] liquid of Example 1 A thermal recording material (d) was prepared in the same manner as in Example 1 except that the liquid was used.

[G liquid]

Tris-p-tolyl-ethoxy-methane (Specific examples of compounds
Compound of No. 6) 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts Comparative Example 1 Example 1 except that water was used instead of the solution [C] of Example 1.
A heat-sensitive recording material (e) was prepared in the same manner as.

Comparative Example 2 A thermosensitive recording material (f) was prepared in the same manner as in Example 1 except that the following [H] solution was used instead of the [C] solution of Example 1.

[H] solution 20 parts of stearic acid amide 20 parts of 5% aqueous solution of methylcellulose 60 parts of water The heat-sensitive recording materials (a) to (f) obtained as described above are
Head thermal power of 0.45W / dot, 1 line recording time 20 in a thermal printing experimental device with a thin film head manufactured by Matsushita Electronic Components Co., Ltd.
The pulse width was printed at 1.6, 2.0, and 2.4 (msec) under the conditions of msec /, scanning line density 8 × 3.85 dots / mm, and the print density was measured with a Macbeth densitometer RD-514 (filter-W-106). . The results are shown in Table-1.

Next, the thermal recording materials (a) to (f) are dried under the conditions of 60 ° C.
A 24-hour storability test was conducted to examine changes in background density. The results are shown in Table-2.

From the above results, it can be seen that the heat-sensitive recording material of the present invention has a high color-developing sensitivity and is suitable for high-speed recording, and also has a high background whiteness and is a highly practical heat-sensitive recording material.

Claims (1)

[Claims] 1. A heat-sensitive recording material utilizing a color-forming reaction between a leuco dye and a color-developing agent thereof, wherein a general formula as an auxiliary component, (In the formula, R represents an alkyl group, X, Y and Z represent an alkyl group, and X, Y and Z may be the same or different,
l, m and n each independently represent an integer of 0 to 3. ) A heat-sensitive recording material characterized by using a triphenyl compound represented by