JPH0775910B2 - Thermal recording material, phthalide derivative, production method thereof and recording material using the derivative - Google Patents

Description

TECHNICAL FIELD The present invention relates to a recording material using a phthalide derivative useful as a color-forming substance used in a thermal recording material.

“Conventional Technology” Conventionally, information transmitted by energy mediation of pressure, heat, electricity, light, etc. is utilized by utilizing a color reaction between a colorless or light basic dye and an organic or inorganic electron accepting substance. Various methods have been proposed for recording, for example, Kondo, Iwasaki, and Paper and Paper Cooperative Journal, Vol. 30, pp. 411-421, 46.
As described on pages 3 to 470 (1976), pressure-sensitive copying sheet, heat-sensitive recording sheet, energization heat-sensitive recording sheet, ultrasonic recording sheet,
A great many methods have been proposed for application to electron beam recording sheets, electrostatic recording sheets, photosensitive recording sheets, photosensitive printing materials, type ribbons, ballpoint pen inks, crayons, stamp inks and the like.

In these recording materials, crystal violet lactone is most commonly used as a colorless to pale basic dye that develops blue. When this dye comes into contact with an electron-accepting substance and instantly exhibits a vivid blue-purple color, the recorded image (color image) obtained is lost in a short time due to the ultraviolet rays of sunlight because the fastness to sunlight is extremely poor. It has the drawback that it will end up. In recent years, the number of cases in which a recorded image on a recording medium is read by an optical character reader has increased remarkably in combination with the rationalization of paperwork. However, the recorded image obtained by this dye has a light absorption of 700 to 700. Since it is not in the infrared region of 900 nm, it could not be applied to such applications at all.

As a dye suitable for such use, the present inventors have proposed a phthalide derivative having a specific divinyl group as disclosed in JP-A-58-1577.
Proposed as No. 9. The recorded image obtained by contacting this phthalide derivative with an electron-accepting substance exhibits a high concentration of blue-green or green and has a light-absorbing property in the infrared region of 700 to 900 nm, and therefore is processed by an optical character reader. Is possible.

However, recording materials using these phthalide derivatives having a divinyl group, especially thermosensitive recording materials, tend to develop color spontaneously in high humidity and cause background fog, which reduces the difference in light absorption between the colored image and the near infrared region. As a result, the processing by the optical character reader becomes difficult. Further, when the recorded image is exposed to light, the light absorption property in the near infrared region is likely to disappear, and similarly the processing by the optical character reading device becomes impossible.

"Problems to be Solved by the Invention" The present invention provides a thermosensitive recording medium using a novel phthalide derivative which forms a color image readable by an optical character reader without the above-mentioned defects.

"Means for Solving Problems" The present invention is a thermosensitive recording medium containing at least one phthalide derivative represented by the following general formula [I] as a color-forming substance.

[In formula, n represents the integer of 1-3. [Operation] The phthalide derivative of the present invention represented by the above general formula [I] is a colorless or light-colored compound, and exhibits a vivid color tone of high concentration of blue-green or green which comes into contact with an electron accepting substance. A recording material using this substance as a coloring substance is stable even in high humidity, and the initial color tone and light absorption in the infrared region of 700 to 900 nm are maintained even when the recorded image is exposed to sunlight for a long time. It has excellent properties.

Thus, the phthalide derivative represented by the general formula [I] of the present invention having the above-mentioned excellent properties is mainly produced by the following typical synthetic method.

That is, by a method of reacting the phthalic anhydride derivative represented by the following general formula [II] and the ethylene derivative represented by the general formula [III] at 50 to 200 ° C. for several tens of minutes to several hours using a dehydration condensation agent. is there.

[In formula, n represents the integer of 1-3. As the dehydration condensing agent used in the reaction of the above phthalic anhydride derivative and ethylene derivative, for example, acetic anhydride serving as a solvent, lower fatty acid anhydride such as propionic anhydride, phosphorus oxychloride, phosphorus trichloride, Inorganic acids such as sulfuric acid and polyphosphoric acid are preferably used, but various other Friedel-Crafts catalysts may be used, and these may be used alone or in combination of two or more.

The thus-obtained phthalide derivative represented by the general formula [I] of the present invention is a colorless to light-colored basic dye having excellent properties as described above, and is an electron-accepting substance (hereinafter abbreviated as a developer). It is used for various recording materials that utilize the color reaction with) and exhibits an extremely excellent effect.

In such a recording material, at least one kind of the phthalide derivative of the present invention is contained as a color-developing substance, but if necessary, various basic dyes exemplified below can be used in combination. 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3-
(P-Dibenzylaminophenyl) -3- (1,2-dimethylindol-3-yl) -7-azaphthalide, 3-
(4-Diethylamino-2-ethoxyphenyl) -3-
(1-Ethyl-2-methylindol-3-yl) -7
-Triarylmethanelactones such as azaphthalide, 3,3-bis (1-ethyl-2-methylindol-3-yl) phthalide, 3-diethylamino-6-methylfluorane, 3-diethylamino-6-methyl-7 -Chlorofluorane, 3- (N-ethyl-N-p-tolylamino)
-7-Methylfluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3- (N-ethyl-N)
-I-pentylamino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-N-tetrahydrofurfurylamino) -6-methyl-7-anilinofluorane,
N-cyclohexyl-N-methylamino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-Np)
-Tolylamino) -6-methyl-7-anilinofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3-dibutylamino-7-o-chloroanilinofluorane, 3-butylamino- Fluoranes such as 7-o-fluoroanilinofluorane, spiropyrans such as di-β-naphthospiropyran and 3-methyl-di-β-naphthospiropyran, 4,4′-bis-dimethylaminobenzhydrylbenzyl ether , 4,4′-Bis-dimethylaminobenzhydryl-p-toluenesulfinic acid ester and other diphenylfutanes, 3,7-bis (dimethylamino) -10-benzoylphenothiazine, 3,7-bis (diethylamino) Azines such as -10-benzoylphenoxazine, N-butyl-3- [bis {4- (N-methylanilino) phenyl} me Le] triarylmethane such as carbazole like.

As described above, the phthalide derivative of the present invention exhibits extremely excellent effects when used in a thermosensitive recording medium that utilizes a color reaction with a color developing agent. White clay, activated clay, attapulgite, bentonite, colloidal silica, aluminum silicate, magnesium silicate, zinc silicate, tin silicate, calcined kaolin, inorganic developer such as talc, oxalic acid, maleic acid, tartaric acid, citric acid, succinic acid, stearin Acids such as aliphatic carboxylic acids, benzoic acid, paratertiarybutylbenzoic acid, phthalic acid, gallic acid, salicylic acid, 3-isopropylsalicylic acid, 3-phenylsalicylic acid, 3-cyclohexylsalicylic acid, 3,5-di-tertiarybutyl Salicylic acid, 3-
Methyl-5-benzylsalicylic acid, 3-phenyl-5-
(Α, α-Dimethylbenzyl) salicylic acid, 3,5-di-
(Α-Methylbenzyl) salicylic acid, 2-hydroxy-
1-benzyl-. -Aromatic carboxylic acids such as naphthoic acid, 4,4'-isopropylidene diphenol, 4,4'-isopropylidene bis (2-chlorophenol), 4,4 '
-Isopropylidene bis (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'-isopropylidenebis (2-tertiarybutylphenol), 4,4'-secondary butylidene diphenol, 4,4'-cyclohexylidenebisphenol, 4,4'-cyclohexylidenebis ( 2-methylphenol), 4-tertiarybutylphenol, 4-phenylphenol, 4-hydroxydiphenoxide, α-naphthol, β-naphthol, methyl-4-hydroxybenzoate, benzyl-4-hydroxybenzoate, 2,2 ′. -Thiobis (4,6-dichlorophenol), 4-tert-aryoctylcatechol, 2,
2'-methylenebis (4-chlorophenol), 2,2'-
Methylenebis (4-methyl-6-tert-butylphenol), 2,2'-dihydroxydiphenol), 4-
Hydroxydiphenyl sulfone, 4-hydroxy-4 '
-Phenolic compounds such as methyl-diphenylsulfone, organic developers such as phenol resins such as para-phenylphenol-formalin resin and para-butylphenol-acetylene resin, and further organic developers such as zinc, magnesium and aluminum. ,calcium,
Examples thereof include salts with polyvalent metals such as titanium, manganese, tin and nickel.

Thermosensitive recording materials include, for example, Japanese Patent Publications Nos. 44-3680 and 44-27880.
No. 45, No. 14039, No. 48-43830, No. 49-69, No. 49
No. 70, No. 52-20142, etc., there are various forms, and the phthalide derivative of the present invention can be applied to thermal recording materials of these various forms, and moreover, simply the phthalide derivative of the present invention. As described above, a heat-sensitive recording material having a recorded image having excellent properties can be obtained only by using as a dye.

Generally, a coating solution obtained by dispersing the phthalide derivative of the present invention and fine particles of a developer in a medium in which a binder is dissolved or dispersed is used for paper, plastic film, synthetic paper, woven fabric sheet, molded products, etc. The thermal recording material of the present invention is produced by coating it on a suitable support. The use ratio of the basic dye containing the phthalide derivative and the developer in the recording layer is not particularly limited, but generally 1 to 50 parts by weight, preferably 2 to 10 parts by weight of the developer per 1 part by weight of the dye. A coloring agent is used.

For the purpose of improving the coloring ability, delustering the surface of the recording layer, and improving the writability, an inorganic metal compound such as a polyvalent metal oxide, hydroxide or carbonate, or an inorganic pigment is generally used in an amount of 1 weight of the developer. 0.1 to 5 parts by weight, preferably 0.2 to 2 parts by weight, can be used in combination, and further various additives such as a dispersant, an ultraviolet absorber, a heat-fusible material, an antifoaming agent, a fluorescent dye, a coloring dye and the like can be used. The agents can be appropriately used in combination as necessary.

As described above, the thermosensitive recording pair of the present invention is generally produced by coating a support with a coating liquid in which a basic dye containing a phthalide derivative and fine particles of the developer are dispersed. Each is separately dispersed 2
The seed coating solution may be overcoated on the support, and it is of course possible to produce the coating solution by impregnation and papermaking.

There is no particular limitation on the method for preparing the coating liquid, the coating method, etc., and the coating amount is generally 2 to 2 by dry weight.
About 12g / m ^{2 is} applied.

Further, it is of course possible to provide an overcoat layer on the recording layer for the purpose of protecting the recording layer, or to provide an undercoat layer on the support, and various known techniques in the field of heat-sensitive recording material addition may be appropriately added. I will get it.

Examples of the binder include starches, celluloses, proteins, gum arabic, polyvinyl alcohol, styrene-maleic anhydride copolymer salt, styrene-
Butadiene copolymer emulsion, vinyl acetate-maleic anhydride copolymer salt, polyacrylic acid salt, etc. are appropriately selected and used.

[Examples] The present invention will be described in more detail with reference to the following examples, but the invention is not limited thereto unless it exceeds the gist of the invention. Further, parts and% in the examples represent parts by weight and% by weight, respectively, unless otherwise specified.

Production Example of Phthalide Derivative Production Example 1 4,5-dichloro-3,6-dibromo-phthalic anhydride 8.3 g and 1,
12.8 g of 1-bis (4-pyrrolidinophenyl) ethylene was added to 30 g of acetic anhydride and reacted at 80 ° C for 1 hour. After the reaction was completed, the reaction product was poured into water, neutralized with an aqueous ammonia solution to decompose acetic anhydride, and the obtained precipitate was collected by filtration. The obtained solid was dried and recrystallized from o-dichlorobenzene to give 3,3-bis [1,1-bis (4
-Pyrrolidinophenyl) ethylene-2-yl] -5,6-
Dichloro-4,7-dibromophthalide as pale yellow crystals 1
5.9 g was obtained. This phthalide derivative developed a green color on silica gel.

Production Example 2 3,6-dichloro-4,5-dibromo-phthalic anhydride instead of 8.6 g of 4,5-dichloro-3,6-dibromo-phthalic anhydride 8.
A decomposition temperature of 21 g was obtained in the same manner as in Production Example 1 except that 3 g was used.
14.8 g of 3,3-bis [1,1-bis (4-pyrrolidinophenyl) ethylene-2-yl] -4,7-dichloro-5,6-dibromophthalide at 4-220 ° C as pale yellow crystals Obtained. This phthalide derivative developed a green color on silica gel.

Production Example 3 4-Chloro-3,5,6-tribromo-phthalic anhydride instead of 8.3 g of 4,5-dichloro-3,6-dibromo-phthalic anhydride
The decomposition temperature was the same as in Production Example 1 except that 9.2 g was used.
183-190 ° C 3,3-bis [1,1-bis (4-pyrrolidinophenyl) ethylene-2-yl] -5-chloro-4,6,7-
Tribromophthalide and 3,3-bis [1,1-bis (4-pyrrolidinophenyl) ethylene-2-yl] -6-chloro-
Light yellow crystals of a mixture of 4,5,7-tribromophthalide 17.
2g was obtained. This phthalide derivative developed a green color on silica gel.

Example 1 The 3,3-bis [1,1-bis (4-pyrrolidinophenyl) ethylene-2-yl] -5,6-dichloro-4,7-dibromophthalide obtained in Production Example 1 was used. A thermal recording paper was manufactured by the following method.

Preparation of Solution A 10 parts of phthalide derivative of Production Example 1 5% aqueous solution of methylcellulose 5 parts Water 40 parts This composition was ground to an average particle size of 3 μm with a sand grinder.

Preparation of solution B 4,4'-isopropylidenediphenol 20 parts 5% aqueous solution of methylcellulose 5 parts water 55 parts This composition was pulverized with a sand grinder to an average particle size of 3 µm.

Preparation of Solution C Stearic acid amide 20 parts 5% aqueous solution of methylcellulose 5 parts Water 55 parts This composition was ground with a sand grinder to an average particle size of 3 μm.

Recording layer formation 55 parts A solution, 80 parts B solution, 80 parts C solution, silicon oxide pigment (oil absorption
180 ml / 100 g) 15 parts, 20% oxidized starch aqueous solution 50 parts, water 10 parts are mixed and stirred. The resulting coating liquid was coated on a base paper of 50 g / m ² so that the dry coating amount was 6 g / m ² , to obtain a thermal recording paper.

Example 2 Obtained in Preparation Example 2 instead of 3,3-bis [1,1-bis (4-pyrrolidinophenyl) ethylene-2-yl] -5,6-dichloro-4,7-dibromophthalide. 3,3-bis [1,1-bis (4-pyrrolidinophenyl (ethylene-2-yl]-
A thermal recording paper was obtained in the same manner as in Example 1 except that 4,7-dichloro-5,6-dibromophthalide was used.

Comparative Example 1 3,3-bis [1,1-bis (4-pyrrolidinophenyl) ethylene-2-yl] -5,6-dichloro-4,7-dibromophthalide was replaced by 3,3-bis [ A thermal recording paper was obtained in the same manner as in Example 1 except that 1,1-bis (4-pyrrolidinophenyl) ethylene-2-yl] -4,5,6,7-tetrachlorophthalide was used.

The three types of thermal recording papers thus obtained were subjected to the following quality comparison tests, and the results are shown in Table 1.

Background fogging in the near infrared region The optical density of the recording layer surface before recording was measured with a spectrophotometer at a wavelength of 830 nm.

Moisture resistance in the near infrared region After leaving the recording paper for 24 hours at 50 ° C. and 90% RH, the optical density (moisture resistance) of the recording layer surface before recording was similarly measured.

Coloring property in the near infrared region The recording paper was pressed (4 kg / cm ² ) on a hot plate of 120 ° C. for 5 seconds, and the optical density of the obtained green color image was measured in the same manner.

Light resistance in the near infrared region The color image obtained by the color development test was exposed to direct sunlight for 5 hours, and then the optical density (light resistance) was similarly measured. Further, the fading rate was calculated by the following general formula.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuru Kondo 1-11, Motoko-cho, Jōkoji, Amagasaki City, Hyogo Prefecture Kanzaki Paper Co., Ltd. Kanzaki Mill (56) Reference JP-A-58-157779 (JP, A)

Claims (1)

[Claims] 1. A thermosensitive recording medium containing at least one phthalide derivative represented by the following general formula [I] as a color-forming substance. [In formula, n represents the integer of 1-3. ]