JPH0645264B2 - Thermal recording - Google Patents

Description

The present invention relates to a thermosensitive recording medium having excellent characteristics for an optical character (or mark) reader having a reading wavelength range in the infrared region. is there.

"Prior Art" Conventionally, a color reaction between a colorless or light-colored basic dye and an organic or inorganic electron-accepting substance has been used to apply pressure, heat,
Various methods have been proposed as a method of recording information transmitted through energy media such as electricity and light. For example, Kondo, Iwasaki Shimbun Gijutsu Vol. 30, 411-421.
Page, pages 463-470 (1976), a pressure-sensitive copying sheet, a heat-sensitive recording sheet, an electric heat-sensitive recording sheet,
Ultrasonic recording sheets, electron beam recording sheets, electrostatic recording sheets, photosensitive recording sheets, as well as photosensitive printing materials, type ribbons, ballpoint pen inks, crayons, stamp inks and the like have been proposed.

On the other hand, in recent years, in combination with the rationalization of office work, the number of cases in which a recorded image of a recording medium is read by an optical character reading device (including mark reading) has increased remarkably, and particularly, the reading wavelength is in the infrared region. In many cases, an optical character reader is used. For example, in the distribution industry, the POS system is drawing attention as a powerful tool in order to quickly respond to the needs of consumers, and the price tag printed with OCR characters or bar codes is processed by a computer at the same time as the checkout process. Although the management efficiency has been improved, a small and inexpensive device having a reading wavelength in the infrared region is used for this reading device.

However, the recorded image (black color image,
Blue color image, red color image, green color image, etc. are in the visible region (40
(0 to 700 nm) is a color that can be read as a lead color for an optical character reader that has a reading wavelength range, and is a color for an optical character reader that has a reading wavelength range in the infrared range (700 to 900 nm). It could not be applied because it works as a dropout color regardless of the color tone.

Therefore, as a basic dye used in various recording materials, a dye suitable for an optical character reader utilizing light in the near infrared region is being developed. For example, a divinyl group-containing phthalide (Japanese Patent Publication No. 5940) has been proposed.

However, thermal recording materials using these phthalide derivatives are brown due to the influence of external environmental conditions such as humidity and heat, and background fogging also occurs. Therefore, light absorption in the near-infrared region between the recorded image and the background area is caused. The difference becomes small, and as a result, it becomes difficult to perform processing in an optical character reader having a reading wavelength range in the near infrared region.

"Problems to be Solved by the Invention" The present invention can be read by an optical character reader having a reading wavelength range in the infrared region, and is excellent in stability of recorded images, particularly humidity and heat. There is one that provides a recording material having a property.

"Means for Solving Problems" The present invention relates to a thermosensitive recording medium containing at least one phthalide derivative represented by the general formula [I] as a colorless or light-colored basic dye, and further comprises a general formula [II]. A heat-sensitive recording material containing at least one compound represented by

[Wherein, R _{1 to} R ₁₀ are each a hydrogen atom; an alkoxyl group; or an amino group. (R ₁₂ and R ₁₃ each represent a saturated alkyl group, but can form a heterocycle with each other), R
₁₁ represents a hydrogen atom. However, R ₃ and R ₈ do not represent an amino group at the same time. a, b, c and d represent carbon atoms to which a halogen atom is bonded. ] Wherein _indicates the R _{14, R 15} are each optionally substituted with an alkyl group of _C 1 _{~ 4} aryl groups. [Operation] In the thermosensitive recording medium of the present invention, the specific phthalide derivative is used as the basic dye as described above, and the specific p-phenylenediamine derivative is used in combination with the basic phthalide derivative. And the moisture resistance are improved significantly, and as a result, the recorded image does not brown even when exposed to high temperature and high temperature conditions for a long time, and the light absorption in the infrared region of 700 to 900 nm is stably maintained. The one who has the body.

Specific examples of the phthalide derivative represented by the above general formula [I] used in the present invention include the following compounds.

3,3-bis [1- (4-ethoxyphenyl) -1-
(2-Dimethylaminophenyl) ethylene-2-yl]
-4,5,6,7-Tetrabromophthalide, 3,3-bis [1- (4-isopropoxyphenyl) -1- (4-
Piperazinophenyl) ethylene-2-yl] -4,5,
6,7-Tetrachlorophthalide, 3,3-bis [1-4
(-Methoxyphenyl) -1- (4-dimethylaminophenyl) ethylene-2-yl] -4,5,6,7-tetrachlorophthalide, 3,3-bis [1- (4-ethoxyphenyl)- 1- (4-dimethylaminophenyl) ethylene-2-yl] -4,5,6,7-tetrachlorophthalide, 3,3-bis [1- (4-methoxyphenyl)-
1- (4-pyrrolidinophenyl) ethylene-2-yl]
-4,5,6,7-Tetrachlorophthalide, 3,3-bis [1- (4-ethoxyphenyl) -1- (4-diethylaminophenyl) ethylene-2-yl] -4,5,
6,7-Tetrachlorophthalide, 3,3-bis [1-
(4-butoxyphenyl) -1- (4-piperidinophenyl) ethylene-2-yl] -4,5,6,7-tetrachlorophthalide and the like.

In addition, these phthalide derivatives can be used alone or as a mixture.

In the present invention, the following compounds are specifically exemplified as the specific p-phenylenediamine derivative represented by the general formula [II] used in combination with these phthalide derivatives.

N, N'-di-β-naphthyl-p-phenylenediamine, N, N'-di-o-tolyl-p-phenylenediamine and the like.

The p-phenylenediamine derivative as described above can be used alone or in combination. Further, among these various p-phenylenediamine derivatives, particularly N, N '
-Di-β-naphthyl-p-phenylenediamine is particularly preferably used because it has no coloring or discoloration and is excellent in desired effects of the present invention.

The specific p-phenylenediamine derivative used in the present invention, when used in combination with the phthalide derivative having the above characteristics of the present invention, also exerts an effect of improving plasticity after recording (stability to a plasticizer). Became clear.

In the heat-sensitive recording material of the present invention, the specific phthalide derivative and the p-phenylenediamine derivative as described above are used in combination, but if necessary, various basic dyes as exemplified below are used in combination. You can also do it.

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-azaphthalide, 3,3
-Triarylmethanelactones such as 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-isopentylamino) -6-methyl-7. -Anilinofluoran, 3- (N
-Ethyl-N-tetrahydrofurfurylamino) -6-
Methyl-7-anilinofluorane, 3- (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-7-o-fluoroanilinofluorane, 3- (N-cyclopentyl-N-ethylamino) -6-methyl-7-anilino Fluorane, 3-chloro-6-p-phenylaminophenylamino) fluorane, 2-methyl-3-chloro-6- (p-phenylaminophenylamino) fluorane, 6- (p-phenylaminophenylamino) -1 , Fluoranes such as 2-benzofluorane, spiropyrans such as di-β-naphthospiropyran and 3-methyl-di-β-naphthospiropyran,
Diphenylmethanes such as 4,4′-bis-dimethylaminobenzhydrylbenzyl ether and 4,4′-bis-dimethylaminobenzhydryl-p-toluenesulfinic acid ester, 3,7-bis (dimethylamino) -10
-Azines such as benzoylphenothiazine and 3,7-bis (diethylamino) -10-benzoylphenoxazine, triarylmethanes such as N-butyl-3- [bis (4- (N-methylanilino) phenyl) methyl] carbazole etc.

In the heat-sensitive recording material of the present invention, as the electron-accepting substance used in combination with the basic dye as described above, a substance acting as a Bronsted acid or a Lewis acid is preferably used. Specifically, for example, acid clay, activated clay, attapulgite, bentonite, colloidal silica, silicon aluminum, silicon magnesium, zinc silicate,
Inorganic developer such as tin silicate, calcined kaolin and talc, aliphatic carboxylic acid such as oxalic acid, maleic acid, tartaric acid, citric acid, succinic acid and stearic acid, benzoic acid, p-tert-
Butylbenzoic acid, phthalic acid, gallic acid, salicylic acid, 3
-Isopropyl salicylic acid, 3-phenyl salicylic acid,
3-cyclohexylsalicylic acid, 3,5-di-tert-butylsalicylic acid, 3-methyl-5-benzylsalicylic acid, 3-phenyl-5- (α, α-dimethylbenzyl)
Aromatic carboxylic acids such as salicylic acid, 3,5-di- (α-methylbenzyl) salicylic acid, 2-hydroxy-1-benzyl-3-naphthoic acid and tetrachlorophthalic acid monoethyl ether, 4,4′-isopropylidene Tendiphenyl, 4,4'-isopropylidene bis (2-chlorophenol), 4,4'-isopropylidene bis (2,6-
Dichlorophenol), 4,4'-isopropylidene bis (2,6-dibromophenol), 4,4'-isopropylidene bis (2-methylphenol), 4,4'-
Isopropylidene bis (2,6-dimethylphenol), 4,4'-isopropylidene bis (2-tert-butylphenol), 4,4'-sec-butylidene diphenol, 4,4'-cyclohexylidene bisphenol, 4 , 4'-Cyclohexylidenebis (2-methylphenol), 4-tert-butylphenol, 4-phenylphenol, 4-hydroxyphenoxide, α-naphthol, β-naphthol, methyl-4-hydroxybenzoate, benzyl-4- Hydroxybenzoate,
2,2'-thiobis (4,6-dichlorophenol),
4-tert-octylcatechol, 2,2'-methylenebis (4-chlorophenol), 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 2,
Phenolic compounds such as 2'-dihydroxydiphenyl, 4-hydroxydiphenyl sulfone, 4-hydroxy-4'-methyl-diphenyl sulfone, p-phenylphenol-formalin resin, p-butylphenol-
Organic color developers such as phenolic resins such as acetylene resins, and further with these organic color developers such as zinc, magnesium, aluminum, calcium, titanium, manganese,
Salts with polyvalent metals such as tin and nickel, 1,3-diphenyl-2-thiourea, 1,3-dichlorophenyl-2-
Examples thereof include thiourea compounds such as thiourea.

The heat-sensitive recording material of the present invention will be described in more detail below. Examples of the heat-sensitive recording material include, for example, JP-B-44-3.
No. 680, No. 44-27880, No. 45-14039.
No. 48-43830, 49-69, 49-
70, 52-20142, etc., there are various forms. The present invention can be applied to these various forms of heat-sensitive recording materials, and can provide a heat-sensitive recording material that exhibits a recorded image having the above-mentioned excellent properties.

Generally, a phthalide derivative represented by the general formula [I], a compound represented by the general formula [II], and fine particles of a developer are dispersed in a medium in which a binder is dissolved or dispersed. The heat-sensitive recording material of the present invention is produced by applying the resulting coating liquid onto a suitable support such as paper, plastic film, synthetic paper, woven fabric sheet and molded product.

The use ratio of the basic dye and the color developer in the recording layer is not particularly limited, but is generally 1 to 50 with respect to 1 part by weight of the dye.
Part by weight, preferably 2 to 10 parts by weight of developer is used.

The use ratio of the compound represented by the general formula [II] is not particularly limited, but is preferably 0.05 to 10 parts by weight, preferably 1 to 10 parts by weight of the phthalide derivative represented by the general formula [I]. Is preferably adjusted in the range of about 0.1 to 3 parts by weight.

Inorganic metal compounds such as polyvalent metal oxides, hydroxides, and carbonates and inorganic pigments are generally added to 1 weight of the color developer for the purpose of improving the coloring ability, delustering the surface of the recording layer, and improving the writability. 0.1 to 5 parts by weight, preferably 0.2 to 2 parts by weight, can be used in combination, and various auxiliaries such as a dispersant, an ultraviolet absorber, a heat-fusible substance, a defoaming agent, a fluorescent dye, a coloring dye, etc. It can be used together if necessary.

As described above, the thermosensitive recording medium of the present invention is generally produced by applying a coating liquid in which fine particles of a basic dye and a developer are dispersed to a support. Two kinds of coating liquids which are separately dispersed and 0 may be coated on a support, and it is of course possible to manufacture by impregnation and papermaking. The method for preparing the coating liquid and the coating method are not particularly limited, and the coating amount is generally about ² to 12 g / m ² in terms of dry weight.

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 publicly known techniques in the heat sensitive recording material manufacturing field are appropriately added. It is possible.

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 and the like are appropriately selected and used.

When both the dye and the developer do not melt in a preferable temperature range of 70 to 120 ° C., the sensitivity to Joule heat can be adjusted by using an appropriate heat-fusible substance together.

"Examples" Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto as long as the gist of the present invention is not exceeded. Further, parts and% in the examples represent parts by weight and% by weight, respectively, unless otherwise specified.

Example 1 Preparation of solution A 3,3-bis [1- (4-methoxyphenyl) -1-
(4-Pyrrolidinophenyl) ethylene-2-yl]-
4,5,6,7-Tetraclophthalide 10 parts Methylcellulose 5% aqueous solution 5 parts Water 40 parts This composition was pulverized with a sand grinder to an average particle diameter of 3 μm.

Liquid B Preparation 4,4-Cyclohexylidenebisphenol 20 parts Methylcellulose 5% aqueous solution 5 parts Water 55 parts This composition was ground to an average particle diameter of 3 μm with a sand grinder.

Preparation of liquid C Stearic acid amide 20 parts N, N′-diphenyl-p-phenylenediamine 1 part Methylcellulose 5% aqueous solution 5 parts Water 55 parts This composition was pulverized with a sand grinder to an average particle diameter of 3 μm.

Formation of Recording Layer 55 parts of A solution, 80 parts of B solution, 81 parts of C solution, 15 parts of silicon oxide pigment (oil absorbing agent 180 ml / 100 g), 50 parts of 20% oxidized starch aqueous solution, and 10 parts of water are mixed and stirred. The obtained coating solution was applied to a base paper of 100 g / m ^{2 in} a dry weight of 5 g / m ²
It was applied and dried to obtain a heat-sensitive recording paper.

Example 2 In the same manner as in Example 1 except that 1 part of N, N′-di-β-naphthyl-p-phenylenediamine was used instead of 1 part of N, N′-diphenyl-p-phenylenediamine. A thermosensitive recording paper was obtained.

Example 3 Thermal recording was conducted in the same manner as in Example 1 except that 1 part of N, N'-di-tolyl-p-phenylenediamine was used instead of 1 part of N, N'-diphenyl-p-phenylenediamine. Got the paper.

Example 4 3,3-bis [1- (4-methoxyphenyl) -1-
(4-Pyrrolidinophenyl) ethylene-2-yl]-
Instead of 10 parts of 4,5,6,7-tetrachlorophthalide, 3,3-bis [1- (4-methoxyphenyl) -1
A thermosensitive recording paper was obtained in the same manner as in Example 2 except that 10 parts of-(4-dimethylaminophenyl) ethylene-2-yl] 4,5,6,7-tetrachlorophthalide was used.

Example 5 3,3-bis [1- (4-methoxyphenyl) -1-
(4-Pyrrolidinophenyl) ethylene-2-yl]-
Instead of 10 parts of 4,5,6,7-tetrachlorophthalide, 3,3-bis [1- (4-methoxyphenyl) -1
-(4-Pyrrolidinophenyl) ethylene-2-yl]-
A thermal recording paper was obtained in the same manner as in Example 2 except that 10 parts of 4,5,6,7-tetrabromophthalide was used.

Example 6 In the same manner as in Example 1 except that 3 parts of N, N′-di-β-naphthyl-p-phenylenediamine was used instead of 1 part of N, N′-diphenyl-p-phenylenediamine. A thermosensitive recording paper was obtained.

Example 7 Preparation of liquid D 3- (N-methyl-N-cyclohexyl) amino-6-
Methyl-7-anilinofluorane 10 parts Methylcellulose 5% aqueous solution 5 parts Water 40 parts This composition was ground to an average particle size of 3 μm with a sand grinder.

Formation of recording layer A solution 18.3 parts, B solution 80 parts, C solution 81 parts, D solution 55 parts, silicon oxide pigment (oil absorption 180 ml / 100 g) 15 parts, 20%
50 parts of the oxidized starch aqueous solution and 10 parts of water are mixed and stirred. The resulting coating liquid was applied to a base paper of 100 g / m ^{2 so} that the dry weight was 5 g / m ^2, and dried to obtain a thermosensitive recording paper.

Example 8 In the same manner as in Example 7 except that 1 part of N, N′-di-β-naphthyl-p-phenylenediamine was used instead of 1 part of N, N′-diphenyl-p-phenylenediamine. A thermosensitive recording paper was obtained.

Comparative Example 1 A thermal recording paper was obtained in the same manner as in Example 1 except that 1 part of N, N'-diphenyl-p-phenylenediamine was not used.

Comparative Example 2 A thermosensitive recording paper was obtained in the same manner as in Example 7 except that 1 part of N, N'-diphenyl-p-phenylenediamine was not used.

The following 10 quality tests were conducted on the 10 kinds of thermal recording papers thus obtained, and the results are shown in Table 1.

[Coloring property in the near infrared region]

Heat at 120 ℃ Press the recording paper for 5 seconds (4kg / cm ² )
Then, the reflectance (%) of the obtained recorded image and the background portion is set to a wavelength of 83
The PCS value was calculated by measuring with a spectrophotometer at 0 nm.

The PCS value is described above as one of the indexes indicating the recording density of the recorded image. The PCS value is calculated by the following formula.

The PCS value required for a recorded image cannot be unconditionally determined because it depends on the type of optical character reader used, but it is generally in the range of 0.7 to 1.0, preferably 0.75 to 1.0 in the reading wavelength range. is there.

[Moisture resistance in the near infrared region]

The recording paper obtained by the color development test is 40 ℃, 90%
After standing for 24 hours under the condition of RH, the PCS value was calculated in the same manner as above.

[Moisture resistance in the near infrared region]

The recording papers obtained in the color development test were each left under the condition of 60 ° C. for 24 hours, and then the PCS value similar to the above was calculated.

"Effects" As is clear from the results of the respective examples, the thermosensitive recording medium of the present invention can be sufficiently applied to any optical character reader having a reading wavelength range in the infrared region, and the obtained recordings can be obtained. The image was excellent in moisture resistance and temperature resistance, did not turn brown due to external environmental conditions such as humidity and heat, and was a very high commercial value recording material having excellent storage stability.

Claims (2)

[Claims] 1. A heat-sensitive recording material containing at least one phthalide derivative represented by the general formula [I] as a colorless to light-colored basic dye, and further containing at least one compound represented by the general formula [II]. A heat-sensitive recording material characterized by being hardened. [Wherein, R _{1 to} R ₁₀ are each a hydrogen atom; an alkoxyl group; or an amino group. (R ₁₂ and R ₁₃ each represent a saturated alkyl group, but can form a heterocycle with each other), R
₁₁ represents a hydrogen atom. However, R ₃ and R ₈ do not represent an amino group at the same time. a, b, c and d represent carbon atoms to which a halogen atom is bonded. ] Wherein _indicates the R _{14, R 15} are each optionally substituted with an alkyl group of _C 1 _{~ 4} aryl groups. ] 2. A compound represented by the general formula [II] is N, N '.
The thermosensitive recording medium according to claim 1, which is -di-β-naphthyl-p-phenylenediamine.