JPH0825331B2 - Recording material - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement in a recording material using a leuco dye as a color former, and more particularly to an improvement in heat-sensitive and pressure-sensitive recording.

[Prior art]

A recording material using a leuco dye has been known for a long time as shown in Japanese Patent Publication No. 45-14039, and it is used as a pressure-sensitive recording paper, a heat-sensitive recording paper, etc., and the amount thereof is increasing year by year. The pressure-sensitive recording material generally utilizes a chemical reaction between a substantially colorless koiro dye and a color developing agent capable of forming a colored image by coloring the koiro dye. Specifically, a coloring agent sheet coated with a microencapsulated organic solvent solution of a coil dye and a coloring agent sheet coated with a coloring agent together with a binder are superposed on each other's surface, and from the back side. The pressure capsule is destroyed by writing pressure or the like to cause a color reaction.

On the other hand, the leuco thermal recording material is a support in which a coil dye and a coloring agent are supported on a support, and gives a colored image when an image signal is thermally applied by a minute heating resistor element.

Compared to other recording materials such as electrophotography and electrostatic recording materials, such pressure-sensitive and heat-sensitive recording paper does not require complicated processing such as development and fixing, and can be performed with a relatively simple device for a short time. It is used in various fields because it can obtain records. As a leuco dye of such a recording material, a blue dye typified by crystal violet lactone, leuco crystal violet, a black dye typified by a fluoran compound substituted by 7-anilino, and the like are mainly used. In recent years, optical character readers and label bar code readers have been developed and their use rate is increasing. In these devices, the light wavelength using an emitting diode or a semiconductor laser is 700 mm as the light source. The above light sources are generally used. However, since the blue dye and the black dye have almost no light absorption in the near infrared region of 700 mm or more, the color reading cannot be performed by the reading device. Therefore, under the present circumstances, there is a strong demand for new development of a leuco dye having a light-absorbing wavelength of 700 mm or more in a color former.

Heretofore, some proposals have been made for leuco dyes having long-wavelength absorption, for example, JP-A-51-121035, JP-A-51-121037, JP-A-51-121038, and JP-A-57-1679.
No. 79, JP-A-59-199757, JP-A-60-226871 discloses, these dyes have an absorption power of 700 nm or more, but weak absorption power, or difficult to synthesize, There were drawbacks such as poor water resistance, high production cost, poor color development characteristics and poor coating solution stability.

〔Purpose〕

INDUSTRIAL APPLICABILITY The present invention has light absorption in the near infrared region of 700 nm or more, particularly 800 to 1000 nm, and is excellent in light resistance, and can be read by an optical character reader or a bar code reader using a semiconductor laser. The purpose is to provide a recording material.

〔Constitution〕

According to the present invention, in a recording material utilizing a color-forming reaction between a leuco dye and a color-developing agent that causes the leuco dye to develop color upon contact, at least one of the leuco dyes is represented by the following general formula (I). There is provided a recording material characterized by being a compound.

(In the formula, R ₁ and R ₂ represent an alkyl group.) The leuco dye represented by the above-mentioned general formula used in the present invention is usually pale yellow, and the color tone is green-blue, so that the contrast is sufficient even by itself. Although obtained, other leuco dyes may be used in combination to prepare a color tone to be used.

Specific examples of the general compounds include those shown below.

The compound of the general formula (I) can be usually obtained by dissolving or dispersing a phthalic anhydride derivative and an ethylene derivative in a suitable solvent, adding a condensing agent and heating. As the condensing agent, acetic anhydride, aluminum chloride, hydrochloric acid, zinc chloride or the like is used.

In the present invention, the leuco dye represented by the above general formula can be used in combination with other leuco closing agents, but the leuco dye used in this case is generally known in this type of leuco recording material. A leuco dye is used, and for example, a leuco compound such as a triphenylmethane dye, a fluorane dye, a phenothiazine dye, an auramine dye, and a spiropyran dye is 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 letolactone), 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 ) Fluoran, 3-dibutylamino-7- (o-chloroanilino) fluorane, 3-N-methyl-N-amylamino-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-
Pyrirospirane, 6'-bromo-3'-methoxy-benzoindolino-
Pyrirospirane, 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-
(Pn-butylanilino) fluoran, 3- (N-benzyl-N-cyclohexylamino)-
5,6-benzo-7-α-naphthylamino-4′-bromofluorane, 3-diethylamino-6-methyl-7-mesitidino-
4 ', 5'-benzofluorane and the like.

Further, as the coloring agent used in combination with the above-mentioned leuco dye in the present invention, various electron-accepting compounds which cause the above-mentioned leuco dye to develop color upon contact, or an oxidizing agent, etc. are applied.
Such substances are conventionally known, and specific examples thereof include inorganic acids, organic acids, phenolic substances, phenol resins and the like as shown below.

Bentonite, zeolite, acid clay, activated clay, silica gel, zinc oxide, zinc chloride, zinc bromide, aluminum chloride, salicylic acid, 3-tert-butylsalicylic acid, 3,
5-di-tert-butylsalicylic acid, di-m-chlorophenylthiourea, di-m-trifluoromethylphenylthiourea, di-phenylthiourea, salicylanilide, 4,
4'-isopropylidene diphenol, 4,4'-isopropylidenebis (2-chlorophenol), 4,4'-isopropylidenebis (2,6-dibromophenol), 4,4 '
-Isopropylidene bis (2,6-dichlorophenol), 4,4'-isopropylidene bis (2-methylphenol), 4,4'-isopropylidene bis (2,6-dimethylphenol), 4,4'- Isopropylidene bis (2-t
ert-butylphenol), 4,4'-sec-butylidene dipheceal, 4,4'-cyclohexylidenebisphenol, 4,4'-cyclohexylidenebis (2-methylphenol), 4-tert-butyl Phenol, 4-phenylphenol, 4-hydroxydiphenoxide, α-naphthol, β-naphthol, 3,5-xylenol, thymol, methyl-4-hydroxybenzoate, 4-hydroxyacetophenone, novolak type phenol resin, 2,
2'-thiobis (4,6-dichlorophenol), catechol, resorcin, hydroquinone, pyrogallol, phloroglysin, phloroglysincarboxylic acid, 4-tert-octylcatechol, 2,2'-methylenebis (4-chlorophenol) 2, 2'-methylenebis (4-methyl-6-ter
t-butylphenol), 2,2'-dihydroxydiphenyl, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, butyl p-hydroxybenzoate, p-
Hydroxybenzyl benzoate, p-hydroxybenzoic acid-p-chlorobenzyl, p-hydroxybenzoic acid-o-
Chlorbenzyl, p-hydroxybenzoic acid-p-methylbenzyl, p-hydroxybenzoic acid-n-octyl, benzoic acid, zinc salicylate, 1-hydroxy-2-naphthoic acid, 2-hydroxy-6-naphthoic acid, 2- Zinc hydroxy-6-naphthoate, 4-hydroxyphenyl sulfone, 4-hydroxy-4'-chlorodiphenyl sulfone, bis (4-hydroxyphenyl) sulfide, 2-
Hydroxy-p-toluic acid, zinc 3,5-di-tert-butylsalicylate, tin 3,5-di-tert-butylsalicylate, tartaric acid, oxalic acid, maleic acid, citric acid, succinic acid, stearic acid, 4- Hydroxyphthalic acid, boric acid,
Biimidazole, hexaphenylbiimidazole, carbon bromide and the like.

In the present invention, when a leuco dye and a color former are bound and supported on a support to obtain a heat-sensitive recording material, various conventional binders can be appropriately used. In order to obtain a pressure-sensitive recording material, when an encapsulated leuco dye is supported on a support or a color developing agent is supported on a support, similarly various conventional binders can be appropriately used. Specific examples of such a binder include the followings.

Polyvinyl alcohol, starch and its derivatives, cellulose derivatives such as methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylic acid amide / acrylic acid ester copolymer, acrylic acid amide / acrylic acid Other than water-soluble polymers such as ester / methacrylic acid terpolymer, styrene / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, and casein, Polyvinyl acetate, polyurethane, styrene / butadiene copolymer, polyacrylic acid, polyacrylic acid ester, vinyl chloride / vinyl acetate copolymer, polybutylmethacrylate, ethylene / Vinyl acetate copolymer, styrene / butadiene / acrylic copolymer latex such as such.

Further, in the present invention, if necessary, an auxiliary additive component commonly used in this type of pressure-sensitive and heat-sensitive recording material, for example,
A filler, a surfactant, a heat-fusible substance, a lubricant, a pressure color-developing preventing agent, etc. can be used in combination. In this case, as 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, surface-treated calcium and silica, fine organic powders such as urea-formalin resin, styrene / methacrylic acid copolymer, and polystyrene resin can be used. Examples thereof include higher fatty acids and metal salts thereof, higher fatty acid amides, higher fatty acid esters, various waxes of animal, vegetable, mineral or petroleum type.

In the present invention, when the pressure-sensitive recording material is prepared, the color developing agent sheet is prepared by dispersing or dissolving the color developing agent in water or an organic solvent, adding a binder if necessary, and adding paper or the like. On the other hand, the color-developing agent sheet is prepared by dispersing the microencapsulated leuco dye with a suitable dispersant and coating it on a support such as paper. The microencapsulation in this case can be carried out by a conventionally known method such as the method described in USP 2800457.

On the other hand, when preparing a heat-sensitive recording material, a dispersion liquid of a leuco dye and a color developing agent, which are separately dispersed, is mixed with an appropriate binder, and this mixed liquid is applied onto a support such as paper.

In this case, the color-developing layer may be coated in one layer or two or more layers, or may be separately coated in a leuco dye layer and a developer layer. Further, an undercoat layer or a protective layer may be provided as is known in the heat-sensitive recording material.

According to the present invention, there is also provided a thermal transfer type heat-sensitive recording material in which a leuco dye and a color former are supported on different supports, but to prepare this, the leuco dye is dispersed or dissolved in water or a solvent. Then, a heat resistant sheet, for example, a polyester film is applied to a support to form a transfer sheet, while a color developing agent is dispersed or dissolved in water or a solvent and applied to the support to form a receiving sheet. .

The recording material of the present invention is used in various fields similar to the conventional ones, and in particular, by utilizing its excellent near-infrared light absorption property, for an optical character reader, a label bar coder, It can be used as a recording fee for reading records by a barcode reader.

When the recording material of the present invention is used as a thermosensitive recording label sheet, a thermosensitive coloring layer containing the above-mentioned leuco dye and a coloring agent is provided on one surface of the support, and an adhesive is provided on the other surface of the support. It may have a structure in which a release mount is provided via layers.

〔effect〕

By using the leuco dye of the general formula (I), the recording material of the present invention has a strong absorbing ability over a color image of 700 to 1,000 nm, and has a general-purpose OCR (optical character reader) and a light emitting diode. The image can be sufficiently read by an image reading device using a semiconductor laser or a semiconductor laser as a light source, and it has an effect of expanding the field of use.

〔Example〕

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

Reference Example 1 [Synthesis of Compound Specific Example No. 1 (1)] 7.8 g of phthalic anhydride, 22.3 g of 1-P-dimethylaminophenyl-1-phenylethylene and 50 ml of acetic anhydride are heated and stirred for 1 hour. After cooling, the reaction product is poured into water, neutralized with aqueous ammonia, and the resulting precipitate is filtered. The precipitate was purified by a silica gel column and recrystallized from toluene / hexane to give pale yellow crystals. Yield 11.5g.

 This compound showed strong absorption at 82 nm in acetic acid.

Reference Example 2 [Synthesis of Compound Specific Example No (2)] Compound No (2) was synthesized in the same manner as in Reference Example 1.

Reference Example 3 [Synthesis of Compound Specific Example No (3)] Compound No (3) was synthesized in the same manner as in Reference Example 1.

Examples 1 to 3 and Comparative Examples 1 to 2 Each mixture having the following composition was dispersed by a ball mill to prepare liquids [A] to [D].

[Liquid A]

Leuco dyes in Table-1 20 parts Hydroxyethyl cellulose 10% aqueous solution 20〃 Water 60〃 [solution B] p-Methoxycarbonyloctadecyl carbamoylbenzene 20 parts Methylcellulose 5% aqueous solution 20〃 Water 60〃 [solution C] Calcium carbonate 30 parts Methylcellulose 5% aqueous solution 30〃 water 40〃 [solution D] Bisphenol S 15 parts Urea-formalin resin filler 5〃 polyvinyl alcohol 10% aqueous solution 10〃 water 70〃 [solution A], [solution B] , [C
0 dry coverage of the fine paper having a basis weight of 50 g / m ² thermal coating liquid obtained by mixing at a ratio of 3 with a dye: liquid] and [Liquid D], 1: 1: 1.
The heat-sensitive recording material was obtained by coating and drying so as to obtain 40 g / m ² .

Next, the color density of the thermal recording material thus obtained is measured to measure the color density, and the background density is measured,
In addition, the absorption region (wavelength) of the color image was measured.

The color density was measured using a thermal printing simulator (manufactured by Matsushita Electronic Components Co., Ltd.), applied power 0.45w / dot, energization time 1.89msec, 1 line recording time 20msec, sub-scanning density.
3.85 lines / mm. In the absorption region of the color image, the PCS value at the maximum absorption wavelength of 700 to 1000 nm was calculated by the following formula.

As a result of the test, the recording materials of Examples 1 to 3 exhibited a color tone of blue to turquoise, a color density of 1.3 or more and a PCS value of 85% or more, while Comparative Examples 1 and 2 The recording material had a PCS value of 20% or less. From the above, it is understood that the product of the present invention is a recording material that can be read in the near infrared region of 700 nm or more.

Claims (1)

[Claims] 1. A recording material utilizing a color-forming reaction between a leuco dye and a color-developing agent which causes the leuco dye to develop color upon contact, wherein at least one of the leuco dyes is represented by the following general formula (I). A recording material characterized by being a compound. (In the formula, represents R ₁ and R ₂ alkyl groups.)