JP2556329B2 - 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 developing sensitivity and image stability.

[Prior art]

A general thermosensitive recording material is a colorless or pale-colored dye such as a leuco dye as a color former on a support such as paper or a film, and a phenolic compound (particularly, bisphenol A) as a color developer for coloring the same when heated. Binders, fillers, sensitivity improvers, as well as color forming systems composed of acidic substances such as organic acids,
Lubricant, provided with a thermosensitive coloring layer in which other auxiliaries are dispersed, for example, JP-B-43-4160, JP-B-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-developed image by an instantaneous chemical reaction between a color-developing agent and a color-developing agent during heating (a thermal printer or a facsimile having a thermal head is used for heating). Therefore, compared to other recording materials, it is possible to obtain recording in a short time with a relatively simple device without performing complicated processing such as development and fixing, low noise and environmental pollution, and low cost. Because of its advantages, it is useful not only for copying books and documents, but also as a recording material for various information such as electronic calculators, facsimile machines, telex machines, medical measuring machines, and measuring instruments.

Further, conventionally, in order to improve the head matching property and reliability, a protective layer is usually provided on the thermosensitive coloring layer. That is, by providing an aqueous polymer emulsion or a protective layer containing a water-soluble polymer and a filler as a main component on the thermosensitive coloring layer, while preventing sticking and dust adhesion, and preventing coloring due to pressure such as scratching, Protects the color-developed part even when it comes into contact with oils and fats, so that fading or discoloration does not occur easily, and even if it is stored for a long period of time, slight color development of the background does not occur easily. However, when the protective layer is provided, the thermosensitive coloring layer comes into contact with the thermal head through the protective layer during printing, which impedes heat conduction and reduces the coloring sensitivity. There is. The degree of this sensitivity decrease is also affected by the material used for the protective layer, but at the same time it greatly changes depending on the protective layer thickness, and if the protective layer is formed thick,
Although characteristics such as head matching and oil and fat resistance of the image are improved, the color development sensitivity is lowered. On the other hand, in recent years, with the development of society, demands for higher speed and higher recording density have been increasing. For this reason, it is strongly desired not only to increase the speed of the recording apparatus itself but also to develop a recording material that can cope with this. 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 to set the melting onset temperature with the leuco dye. It is to lower and speed up. However, it is difficult to control the melting point of a phenolic compound, which is a color developing agent that is widely used in the field of thermal recording materials, and the phenolic compound itself is expensive and is not practical. The second method is, for example, JP-A-53-39139, JP-A-53-26139, and JP-A-53-53.
As described in JP-A-5636, JP-A-53-11036, JP-A-60-82382, etc., various waxes, fatty acid amides, alkylated biphenyls, substituted biphenylalkanes, coumarins are used in the thermosensitive coloring layer. , Diphenylamines, p-
A method of adding a heat-melting substance having a low melting point such as benzyl biphenyl as a sensitizer (or melting point depressant) has also been proposed. 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, image reliability, head matching property and the like.

〔Purpose〕

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

〔Constitution〕

According to the present invention, in a thermosensitive recording material having a thermosensitive coloring layer containing a leuco dye and a developer as a main component on a support,
The thermosensitive coloring layer contains at least one vinyl ether compound represented by the following general formula, and a protective layer containing an aqueous polymer emulsion or a water-soluble polymer as a main component is provided on the thermosensitive coloring layer. A featured thermal recording material is provided.

_{CH 2 = CHOCH 2 CH 2 O} -Ar-OCH 2 CH 2 OCH = CH 2 In the formula, Ar represents a benzene ring or a naphthalene ring, said ring optionally substituted by a halogen atom, an alkyl group or an aralkyl group Good.

Since the heat-sensitive recording material of the present invention is excellent in color density and color sensitivity as compared with the conventional heat-sensitive recording material by containing the vinyl ether compound in the heat-sensitive color developing layer and providing the protective layer, high-speed recording is possible. It is suitable for use, has a high degree of background whiteness, and does not cause image erasing due to contact with fingerprints.

Thermal recording using low-melting substances such as various waxes, fatty acid amides, alkylated biphenyls, substituted biphenylalkanes, coumarins, diphenylamine, p-benzylbiphenyl, etc. which are conventionally known as sensitizers (or melting point depressants). Although it cannot be said that the material is sufficient in terms of color density, color sensitivity, background whiteness, etc., the thermosensitive recording material of the present invention is said to be very excellent without such drawbacks. be able to.

Specific examples of the vinyl ether compound used in the present invention are shown below, but the present invention is not limited thereto.

(1) 1,4-bis (2-vinyloxyethoxy) benzene (2) 1,3-bis (2-vinyloxyethoxy) benzene (3) 1,4-bis (2-vinyloxyethoxy) naphthalene (4) ) 1,5-bis (2-vinyloxyethoxy) naphthalene (5) 1,7-bis (2-vinyloxyethoxy) naphthalene (6) 2,3-bis (2-vinyloxyethoxy) naphthalene (7) 2 , 7-Bis (2-vinyloxyethoxy) naphthalene (8) 1,4-bis (2-vinyloxyethoxy) -2-
Methylbenzene (9) 1,4-bis (2-vinyloxyethoxy) -2-
Chlorobenzene (10) 1,3-bis (2-vinyloxyethoxy) -4-
Methylbenzene (11) 1,3-bis (2-vinyloxyethoxy) -4-
Chlorobenzene (12) 1,3-bis (2-vinyloxyethoxy) -4-
Ethylbenzene (13) 1,3-bis (2-vinyloxyethoxy) -4-
Benzylbenzene (14) 1,3-bis (2-vinyloxyethoxy) -4-
Phenethylbenzene (15) 1,3-bis (2-vinyloxyethoxy) -4-
t-Butylbenzene In the present invention, an aqueous emulsion or a protective layer containing a water-soluble polymer as a main component is provided on the thermosensitive coloring layer. The aqueous polymer emulsion and water-soluble polymer used here are conventionally known. The following are used, for example. Polyvinyl alcohol, methyl cellulose, hydroxyethyl cellulose, starch, starch derivative, styrene / maleic anhydride copolymer, isobutylene / maleic anhydride copolymer, polyamide, styrene / butadiene copolymer latex, styrene / acrylic acid ester copolymer Combined emulsion, polyvinyl acetate emulsion, etc.

A conventionally known filler can be used in combination in the protective layer of the present invention. As such a filler,
For example, calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate,
In addition to inorganic fine powders such as clay, talc, and surface-treated calcium and silica, organic fine powders such as urea-formalin resin, styrene / methacrylic acid copolymer, and polystyrene resin can be given.

Further, a surfactant, a heat-fusible substance or the like may be added to the protective layer, if necessary. Examples of the heat-fusible substance in this case include higher fatty acids or their esters, amides or metal salts, as well as various waxes, condensates of aromatic carboxylic acids and amines, phenyl benzoate esters, and higher linear glycols. , 3,4-epoxy-dialkyl hexahydrophthalate, higher ketones, and other heat-fusible organic compounds having a melting point of about 50 to 200 ° C.

The leuco dye used in the present invention is applied alone or as a mixture of two or more kinds. As such a leuco dye, those applied to this kind of heat-sensitive material are arbitrarily applied, for example, triphenyl dye. Leuco compounds of dyes such as methane, fluoran, phenothiazine, auramine, spiropyran and indolinophthalide are preferably used. Specific examples of such leuco dyes include, for example, 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-cyclohexylamino-6-chloro Fluoran, 3-dimethylamino-5,7-dimethylfluoran, 3-diethylamino-7-chlorofluoran, 3-diethylamino-7-methylfluoran, 3-diethylamino-7,8-benzfluoran, 3- Diethylamino-6-methyl-7-chlorofluoran, 3- (Np-tolyl-N-ethylamino) -6-methyl- -Anilinofluoran, 3-pyrrolidino-6-methyl-7-anilinofluoran, 2- {N- (3'-trifluoromethylphenyl) amino} -6-diethylaminofluoran, 2- {3.6 -Bis (diethylamino) -9- (o-chloroanilino) xanthyl lactam benzoate}, 3-diethylamino-6-methyl-7- (m-trichloromethylanilino) fluoran, 3-diethylamino-7- (o-chloroanilino) Fluoran, 3-dibutylamino-7- (o-chloroanilino) fluoran, 3-N-methyl-N-isoamylamino-6-methyl-
7-anilinofluoran, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3- (N, N -Diethylamino) -5-methyl-7- (N, N
-Dibenzylamino) fluoran, benzoyl leucomethylene blue, 6'-chloro-8'-methoxy-benzoindolino-pyrrospirane, 6'-bromo-3'-methoxy-benzoindolino-pyrrospirane, 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, 3,6-bis (dimethylamino) fluorene spiro (9,
3 ')-6'-Dimethylaminophthalide, 3- (N-ethyl-N-isoamilo) amino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-isopropyl) amino-6 -Methyl-7-anilinofluorane, 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-phenylethyl) Amino) fluorane, 3- (N-ethyl-p-toluidino) -7- (α-phenylethylamino) fluorane, 3-diethyla No-7- (o-methoxycarbonylphenylamino) fluorane, 3-diethylamino-5-methyl-7- (α-phenylethylamino) fluorane, 3-diethylamino-7-piperidinofluorane, 2-chloro-3 -(N-methyltoluidino) -7- (p
-N-butylanilino) fluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 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.

Further, in the present invention, as the developer used, various compounds having an electron accepting property which develops the leuco dye upon contact, for example, a phenolic compound, a thiophenolic compound, a thiourea derivative, an organic acid and a metal salt thereof. Etc. are preferably applied, and specific examples thereof include the following.

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-4-tert-butylphenol), 4,4'-butylidenebis (6-tert-butyl-2methyl)
Phenol, 4,4'-thiobis (6-tertbutyl-2-methyl) phenol, 4,4'-diphenol sulfone, 4-isopropoxy-4'-hydroxydiphenyl sulfone, 4-benzyloxy-4'-hydroxydiphenyl Sulfone, 4,4'-diphenol sulfoxide, isopropyl P-hydroxybenzoate, 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, 2,2'-methylenebis (4-ethyl-6) -Tert-butylphenol), 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 vinyl ether compound on a support,
Various commonly used binders can be appropriately used. For example, polyvinyl alcohol, starch and its derivatives, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, cellulose derivatives such as ethylcellulose, sodium polyacrylate,
Polyvinylpyrrolidone, acrylamide / acrylic acid ester copolymer, acrylamide / acrylic acid ester / methacrylic acid terpolymer, styrene / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, polyacrylamide , Water-soluble polymers such as sodium alginate, gelatin, and casein, polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylic acid ester, vinyl chloride / vinyl acetate copolymer,
Examples thereof include emulsions such as polybutyl methacrylate and ethylene / vinyl acetate copolymers, and latexes such as styrene / butadiene copolymers and styrene / butadiene / acrylic copolymers.

Further, in the present invention, together with the leuco dye, the color developer and the vinyl ether compound, if necessary, further, an auxiliary additive component commonly used in this type of heat-sensitive recording material, for example, a filler, a surfactant, or a heat-fusible agent. Substance (or lubricant)
Can be used in combination. In this case, specific examples of the filler and the heat-fusible substance are the same as those exemplified for the protective layer.

In the present invention, a layer containing a filler, a binder, a heat-fusible substance or the like may be provided as an undercoat layer between the support and the thermosensitive color developing layer, if necessary. In this case, specific examples of the filler, the binder, and the heat-fusible substance include the same as those exemplified in the protective layer or the thermosensitive coloring layer.

〔effect〕

The heat-sensitive recording material of the present invention has improved sensitivity,
It is suitable for high-speed recording, has a high background whiteness, is excellent in storage stability, and is extremely useful.

〔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 The following mixture was ground in a magnetic ball mill for 2 hours to prepare [solution A], [solution B], [solution C], [solution D] and [solution E].

[Liquid A]

3- (N-methyl-N-cyclohexyl) 20 parts Amino-6-methyl-7-anilinofluorane Polyvinyl alcohol 10% aqueous solution 20 parts Water 60 parts [B solution] Bisphenol A 20 parts Hydroxyethyl cellulose 10% aqueous solution 20 parts Water 60 parts [C liquid] 1,4-bis (2-vinyloxyethoxy) benzene 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts [D liquid] calcium carbonate 20 parts 5% aqueous solution of methyl cellulose 20 parts Water 60 parts [Solution E] Calcium carbonate 4 parts 10% aqueous solution of polyvinyl alcohol 50 parts Zinc stearate 1 part Water 45 parts Next, [Solution A] 10 parts, [Solution B] 30 parts, [Solution C] 30 parts,
[D liquid] 20 parts and 10 parts of a 20% aqueous solution of an isobutylene / maleic anhydride copolymer in an alkaline solution are mixed to prepare a thermosensitive color forming layer-forming liquid, which is attached to a fine paper having a basis weight of 50 g / m ² after drying. After coating and drying so that the amount becomes 0.5 g / m ² , a thermosensitive coloring layer is provided, and then [E liquid] is dried thereon, and the adhesion amount is 1.0 g / m ²
Was applied to form a protective layer, and the surface of the layer was calendered so that the surface smoothness was 1000 to 1500 seconds to prepare a heat-sensitive recording material.

Example 2 A thermosensitive recording material was prepared in the same manner as in Example 1 except that the following [F liquid] was used instead of the [C liquid] of Example 1.

[F liquid]

1,3-bis (2-vinyloxyethoxy) benzene 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts water 60 parts Comparative Example Except that the following [solution G] was used instead of [solution C] in Example 1. A thermal recording material was prepared in the same manner as in Example 1.

[G liquid]

p-Benzylbiphenyl 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts The thermal recording material obtained as described above was used in a thermal printing experimental device having a thin film head manufactured by Matsushita Electronic Parts Co., Ltd. to obtain a head power of 0.45 W. / Dot, 1 line recording time 20 msec /, scanning line density 8 x 3.85 dots / mm, pulse width 1.6, 2.
Printed at 0 and 2.4 msec, and printed density is Macbeth densitometer
It was measured with RD-514 (filter W-106). The results are shown in Table-1.

Next, the heat-sensitive recording material is subjected to a storage stability test under dry conditions at 60 ° C for 24 hours to check the change in background density, and a fingerprint is imprinted on the image area for 24 hours at 40 ° C and 90% humidity. The storage test was conducted to examine the change in the image area. The results are shown in Table-2.

From Table 1 and Table 2, it can be seen that the heat-sensitive recording material of the present invention is an extremely useful heat-sensitive recording material excellent in color development during high-speed recording, excellent in storage stability of the background, and further excellent in image stability. I understand.

Claims (1)

(57) [Claims] 1. A thermosensitive recording material having a thermosensitive coloring layer containing a leuco dye and a color developer as a main component on a support, wherein the thermosensitive coloring layer contains at least one vinyl ether compound represented by the following general formula. And a protective layer containing an aqueous polymer emulsion or a water-soluble polymer as a main component on the thermosensitive coloring layer. CH ₂ = CHOCH ₂ CH ₂ O-Ar-OCH ₂ CH ₂ OCH = CH ₂ (In the formula, Ar represents a benzene ring or a naphthalene ring, and the ring may be substituted with a halogen atom, an alkyl group or an aralkyl group. Good.)