JPS63301260A - Novel leuco dye - Google Patents

Abstract

NEW MATERIAL:A leuco dye compound of formula I [wherein R1-4 are each a lower alkyl, R5 is alpha- or beta-naphthyl, a group of formula II (wherein R6 is a group of formula III, a halogen or a substituted amino and R9 is H or R1), R7-8 are each R9, and R6 is a group of formula III when both of R7 and R8 are H atoms]. EXAMPLE:A compound of formula IV. USE:A leuco dye useful as a colorant precursor in the form of a white to light yellow crystalline powder which when brought into contact with an electron- accepting compound (color developer) on a molecular level, forms a green to blue heat-sensitive or pressure-sensitive recording colorant of excellent storage stability, excels in stability in air and shows strong absorptions in the near- infrared region at 600-1,000nm. PREPARATION:A compound of formula V (wherein X<-> is an anion such as a halide or perchlorate ion) is reacted with a compound of formula IV by heating in a methanol/acetic acid solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a novel leuco dye for image formation, and particularly to a near-infrared absorbing leuco dye for heat-sensitive recording and pressure-sensitive recording.

[Prior art]

Recording materials using leuco dyes have been known for a long time.
In recent years, it has been widely used as pressure-sensitive recording paper and heat-sensitive recording paper. Commonly used leuco dyes include, for example, triphenylmethane, fluoran, phenothiazine, and auramine dyes. These dyes come in a variety of colors and are used depending on the purpose. However, many of these dyes have been developed for the purpose of absorbing color tones, that is, in the visible region, and have been developed for the purpose of absorbing in the near-infrared region, that is, in the visible region.
At present, very few dyes having absorption in the range of 700 to 1000 nanometers have been developed. In recent years, as semiconductor lasers have become more popular, there has been a movement to read recorded images such as barcodes with semiconductor lasers, and even thermal paper, pressure-sensitive paper, etc.
It is now required to have absorption in the near-infrared region.

Recently, several proposals have been made regarding leuco dyes that absorb in the near-infrared region. For example, JP-A-51-121035
No., JP-A-51-121037, JP-A-51-121
No. 038, JP-A-57-167979 and JP-A-58
These include monovinyl- or divinyl-containing phthalide compounds as seen in Japanese Patent Application Laid-Open No. 157779, fluorene compounds as seen in JP-A-59-199757 and JP-A-60-226871. However, although these compounds have absorption in the near-infrared region, they have drawbacks such as insufficient absorption strength, poor dye stability and easy image discoloration, and high manufacturing costs. have.

In addition, a new near-infrared absorbing leuco dye has been proposed in JP-A No. 60-231766, but although this dye has strong near-infrared absorption, its storage stability is insufficient, and especially It has the disadvantage of poor heat stability. Therefore, the current situation is that a satisfactory near-infrared absorbing dye has not yet been found.

〔the purpose〕

An object of the present invention is to provide a novel leuco dye that has strong absorption in the near-infrared region and has excellent storage stability. To be more specific, from 600 nanometers to 10
It has a wide and strong absorption in the 00 nanometer range, and when used as a leuco dye for heat-sensitive or pressure-sensitive paper, it can be read with light sources from the visible region to the near-infrared region, and the dye image has excellent stability. The purpose is to provide a new leuco dye.

〔composition〕

According to the present invention, a novel leuco dye represented by the following general formula (1) is provided.

+1° In the formula, R,, R,, R, and R4 are lower alkyl groups, and R6 is an α- or β-naphthyl group or -〇-Rg
Yes.

R6 is -NHCOR, a halogen atom or a substituted amino group, and R, R, and R9 are a hydrogen atom or a lower alkyl group. However, when R7 and R1 are both hydrogen atoms, R6 is -NHCOR or a bromine atom.

The leuco dye represented by the general formula (1) of the present invention is a new substance, is a white or pale yellow crystalline powder that is stable in the atmosphere, and has strong absorption in the near-infrared region of 600 to 11,000 nm. Inorganic acids such as acid clay, activated clay,
When contacted at the molecular level with electron-accepting compounds (i.e., color formers) such as organic acids, phenolic compounds, and phenolic resins, a color reaction occurs quickly to form a green or blue pigment, and this colored pigment is an excellent It is useful as a dye precursor because of its long shelf life.

The leuco dye represented by the general formula (1) of the present invention is:
Generally, it can be easily synthesized according to the following reaction formula.

fi.

(I) (X- in the reaction formula represents an anion such as halogen or perchloric acid) This reaction can be carried out simply by heating in a methanol/acetic acid mixed solvent. In addition, regarding the manufacturing method of compound (n) in the reaction formula, 1, for example, Annalen d
er Che++ie, vol. 623, p. 204 (1959
)It is described in.

R1-R4 and R□ to R in the general formula (I) of the present invention
The lower alkyl group of 3 is usually a straight chain or branched alkyl group having 1 to 4 carbon atoms. Moreover, R6 is preferably -NHCORg.

Specific examples of the compound represented by the general formula (1) are as follows.

[Specific examples of compounds of general formula (1)] The leuco dye of the present invention, like conventional leuco dyes, can be used as a coloring agent in recording materials such as pressure-sensitive recording materials, heat-sensitive recording materials, and thermal transfer recording materials. can do.

When the leuco dye of the present invention is used as a pressure-sensitive recording material, it can be produced, for example, by the method described in US Pat. No. 2,800,457. The main physical properties required of the leuco dye in this case include coloring properties with an oil-soluble coloring agent, storage stability of dye images, etc., and the leuco dye is selected in consideration of these physical properties.

When the leuco dye of the present invention is used as a heat-sensitive recording material, it can be produced, for example, by the method described in Japanese Patent Publication No. 14039/1983.

In this case, the main physical properties required of the leuco dye are:
They are thermal coloring properties, background whiteness, storage stability of leuco dyes and their coloring dyes, etc., and are selected in consideration of these physical properties.

In either case, the image of the leuco dye of the present invention is
It is important to make full use of the property of having sufficient absorption properties in the near-infrared region.

When the leuco dye of the present invention is used as a recording material, it can also be used in combination with other leuco dyes. That is, although the color tone of the leuco dye of the present invention is green to blue, it can also be used in combination with other leuco dyes for the purpose of one color tone correction or correction of absorption characteristics. As the leuco dye used in combination in this case, leuco dyes that are generally known for this type of leuco recording material are used, and specific examples of such leuco dyes include those shown below. Can be mentioned.

3.3-bis(p-dimethylaminophenyl)-phthalide, 3.3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, 3.3-bis(p-dimethylaminophenyl)-6 -ethylaminophthalide, 3.3-bis(p-dimethylaminophenyl)-6-chlorophthalide.

3.3-bis(ρ-dibutylaminophenyl)phthalide, 3-cyclohexylamino-6-chlorofluorane,
3-dimethylamino-5,7-dimethylfluorane, 3
-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane, 3-diethylamino-6
-Methyl-7-chlorofluorane, 3-(N-p-tolyl-N-ditylamino)-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 2- (N-(3'-trifluoromethylphenyl)
amino)-6-dinithylaminofluorane, 2-(3
, 6-bis(diethylamino)-9-(o-chloroanilino)xantylbenzoic acid lactam), 3-diethylamino-6-methyl-7-(deuterium-trichloromethylanilino)fluoran, 3-diethylamino-7-(o- chloroanilino)fluoran, 3-dibutylamino-7-(o-chloroanilino)fluoran, 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, benzoylleucomethylene blue.

6'-Chloro-8'-methoxy-benzoindolino-pyrylospirane, 6'-bromo-3'-methoxy-benzoindolino-pyrylospirane, 3-(2'-hydroxy-41-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)fluoran, 3-(N-ethyl-P-toluidino)-7-(α- 3-diethylamino-7-(O-methoxycarbonylphenylamino)fluoran, 3-diethylamino-5-methyl-7-(α-phenylethylamino)fluoran, 3-diethylamino-7-piperidino Fluorane, 2-
Chloro-3-(N-methyltoluidino)-7-(p-n
-butylanilino)fluorane, 3-(N-benzyl-N-cyclohexylamino)-5
, 6-penzo 7-α-naphthylamino-4'-bromofluorane, 3-diethylamino-6-methyl-7-mesitidino 4
',5'-benzofluorane etc.

Further, as the coloring agent used when obtaining a recording material using the leuco dye of the present invention, various electron-accepting compounds or oxidizing agents that cause the leuco dye to develop a special color on contact are used. Such materials are conventionally known, and specific examples thereof include those 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'-isopropylidenediphenol, 4
．． 4'-isopropylidene bis(2-chlorophenol), 4,4'-isopropylidene bis(2,6-dibromophenol), 4,4'-isopropylidene bis(2-chlorophenol)
, 6-dichlorophenol), 4,4'-isopropylidene bis(2-methylphenol), 4,4'-isopropylidene bis(2,6-dimethylphenol), 4,
4'-isopropylidene bis(2-tert-butylphenol), 4,4'-5ec-butylidene diphenyl, 4,4'-cyclohexylidene bisphenol, 4,4'-cyclohexylidene bis(2-methylphenol) ), 4-tart-butylphenol, 4-
phenylphenol, 4-hydroxydiphenoxide,
α-naphthol, β-naphthol, dimethyl 5-hydroxyphthalate, methyl-4-hydroxybenzoate,
4-hydroxyacetophenone, novolac type phenolic resin, 2,2'-thiobis(4,6-dichlorophenol), catechol, resorcinol, hydroquinone, pyrogallol, phloroglycine, phloroglycine carboxylic acid, 4-tert-octylcatechol, 2, 2'-
Methylenebis(4-chlorophenol), 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2'-dihydroxydiphenyl, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, ρ- Butyl hydroxybenzoate, benzyl p-hydroxybenzoate, p-chlorobenzyl p-hydroxybenzoate, 0-chlorobenzyl p-hydroxybenzoate, p-methylbenzyl p-hydroxybenzoate, p
-n-octyl hydroxybenzoate, benzoic acid, zinc salicylate, l-hydroxy-2-naphthoic acid, 2-hydroxy-6-naphthoic acid, zinc 2-hydroxy-6-naphthoate, 4-hydroxydiphenylsulfone, 4 ，
2'-diphenolsulfone, 4-hydroxy-4'
-chlorodiphenylsulfone, 4-hydroxy-4'-
Benzyloxydiphenyl sulfone, 4-hydroxy-4
'-isopropoxydiphenyl sulfone, 4-hydroxy-4'-isobutyloxydiphenyl sulfone, bis(4-hydroxyphenyl) sulfide, 2-hydroxy-p-1-ruylic acid, zinc 3,5-di-tert-butylsalicylate, 3,5-di-tert-butyltin salicylate, tartaric acid, oxalic acid, maleic acid, citric acid, succinic acid, stearic acid, 4-hydroxyphthalic acid, boric acid, biimidazole, hexaphenylbiimidazole,
Carbon tetrabromide, methylenebis-(oxyethylenethio)diphenol, ethylenebis-(oxyethylenethio)diphenol, bis-(4-hydroxyphenylthioethyl)ketone, bis-(4-hydroxyphenylthioethyl)ether, m-xylylene bis(4-hydroxyphenylthio)ether and the like.

To obtain a pressure-sensitive recording material using the leuco dye of the present invention,
First, add 1 to alkylnaphthalene or terphenyl oil.
Microcapsules, usually around 5 μm in size, are prepared by dissolving 4% leuco dye and hardening resin such as gelatin. The microcapsules are coated onto a support such as paper or plastic film using a binder to obtain a color former sheet. Microencapsulation in this case is for example USP
This can be carried out by conventionally known methods such as the method described in No. 2800457. On the other hand, the coloring agent sheet.

It is prepared by dispersing or dissolving a coloring agent in water or an organic solvent using a suitable dispersant, adding a binder if necessary, and coating it on a support such as paper.

To obtain a heat-sensitive recording material using the leuco dye of the present invention,
A leuco dye and a coloring agent are each dispersed in a water-soluble resin or the like, a suitable binder is mixed with the dispersion, and this mixed solution is applied onto a support such as paper. In this case, the particle size of the leuco dye is preferably about 0.5 to 5 μm. Further, the weight ratio of the leuco dye to the coloring agent is suitably about 1:1 to 1:5. Note that the coloring layer may be coated as one layer or divided into two or more layers, or may be coated separately as a leuco dye layer and a coloring agent layer. Further, as is known for heat-sensitive recording materials, an undercoat layer or a protective layer may be provided.

Further, in order to obtain a thermal transfer type recording material using the leuco dye of the present invention, the leuco dye is dispersed or dissolved in water or a solvent and applied to a heat-resistant support such as a polyester film to prepare a transfer sheet. on the other hand.

A coloring agent is dispersed or dissolved in water or a solvent and applied to a support to prepare a receiving sheet.

In order to obtain a heat-sensitive recording material, when a leuco dye and a coloring agent are bonded and supported on a support, various conventional binders can be used as appropriate, and in order to obtain a pressure-sensitive recording material, When supporting an encapsulated leuco dye or a coloring agent on a support, various conventional binders can be used as appropriate. Specific examples of such binders include the following.

Polyvinyl alcohol, starch and its derivatives, cellulose derivatives such as methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, ethylcellulose, sodium polyacrylate,
Polyvinylpyrrolidone, acrylamide/acrylic ester copolymer, acrylamide/acrylic ester/methacrylic acid terpolymer, styrene/maleic anhydride copolymer alkali salt, isobutylene/maleic anhydride copolymer alkali salt, polyacrylamide In addition to water-soluble polymers such as , sodium alginate, gelatin, and casein, polyvinyl acetate, polyurethane, styrene/butadiene copolymer, polyacrylic acid, polyacrylic acid ester, vinyl chloride/vinyl acetate copolymer, and polybutylene Latexes such as methacrylate, ethylene/vinyl acetate copolymer, styrene/butadiene/acrylic copolymer, etc.

Further, if necessary, auxiliary additive components commonly used in this type of pressure-sensitive and heat-sensitive recording materials, such as fillers, surfactants, thermofusible substances, lubricants, pressure coloring inhibitors, etc., can be used in combination. . In this case, examples of fillers include calcium carbonate, silica, zinc Wn oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc,
In addition to surface-treated inorganic fine powders such as calcium and silica, organic fine powders such as urea-formalin resin, styrene/methacrylic acid copolymer, and polystyrene resin can be used.As lubricants, higher fatty acids and metal salts thereof, higher fatty acid amides, higher fatty acid esters, and various animal, vegetable, mineral, or petroleum waxes.

The recording material obtained using the leuco dye of the present invention can be used in various fields like conventional ones, but in particular, it can be used for optical character reading by taking advantage of its excellent near-infrared light absorption properties. It can be used as a recording material for devices, label barcoders, and barcode readers for reading records.

Note that when the recording material obtained using the leuco dye of the present invention is used as a heat-sensitive recording label sheet, a heat-sensitive coloring layer containing the above-mentioned leuco dye and coloring agent is provided on one side of the support. It may have a structure in which a release mount is provided on the other side of the body with an adhesive layer interposed therebetween.

〔effect〕

The novel leuco dye represented by the general formula (1) of the present invention exhibits strong absorption ability in the near-infrared region ranging from 600 to 1100 On. Therefore, the heat-sensitive and pressure-sensitive recording materials obtained using the leuco dye can be read with light sources from the visible region to the near-infrared region, and the dye images have excellent storage stability, especially heat resistance stability. As a result,1.
The image can be sufficiently read by an image reading device using a semiconductor laser or the like as a light source.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 Synthesis of bis(p-dimethylaminostyryl)-α-naphthylsulfonylmethane [Specific Compound Example No. (1)] 2.8 g of bis(p-dimethylaminostyryl)carbeniram perchlorate and 1.9 g of acetic acid were added. In addition to 80 cc of methanol, a solution of 4.1 g of sodium α-naphthylsulfinate in 80 cc of methanol was added dropwise, and the mixture was heated under reflux for 1 hour. The formed precipitate was collected by filtration and recrystallized with a mixed solvent of benzene/hexane to give pale yellow crystals (melting point 178-183°C).
3.1 g was obtained.

Examples 2 to 3 Compound specific examples No. (2) and No. ( Compound 3) was obtained.

Example 4 Bis(P-dimethylaminostyryl) in Example 1
A compound of Compound Specific Example No. (6) was obtained in the same manner as in Example 1, except that bis(p-diethylaminostyryl)carbeniram perchlorate was used instead of carbeniram perchlorate.

Example 5 Bis(P-dimethylaminostyryl) in Example 1
Compound Specific Example No. (9) was prepared in the same manner as in Example 1, except that bis(p-(N-methyl-N-ditylamino)styryl)carbeniram perchlorate was used instead of carbeniram perchlorate. The compound was obtained.

Example 6 Bis(p-dimethylaminostyryl) in Example 1
Compound Example N was prepared in the same manner as in Example 1, except that bis(4-dimethylamino-2-methylstyryl)carbeniram perchlorate was used instead of carbeniram perchlorate.
A compound of o(10) was obtained.

Table 1 shows the color tone and melting point of the compounds obtained in Examples 2 to 6 above.

Application Examples 1 to 6, Comparative Examples 1 to 3 Each mixture having the following composition was dispersed in a ball mill to prepare liquids (A) and CB).

[Liquid A]

Leuco dye in Table 2 10 parts 10% polyvinyl alcohol aqueous solution 10 parts water
3
0 parts [Liquid B] Stearamide 20 parts Calcium carbonate 20 parts 4.4'-diphenolsulfone 30 parts Polyvinyl alcohol 10% aqueous solution 35 parts Water
210 parts [Liquid A] and [Liquid B] obtained as above were mixed at a ratio of 1:1 to prepare a coating solution, and this coating solution was coated on high-quality paper with a dry solid content of the leuco dye. It was coated at a weight of 0.6 g/distance and dried to obtain a heat-sensitive recording material.

This was printed solidly using a commercially available facsimile Rifax 130, and its quality was measured. The measurement results are shown in Table-2.

The concentration was measured using Macbeth Density Meter 914, and the filter was K.
It was measured using odak Wratten NoLO6. pcs
The value was determined by measuring the absorbance with a reflection spectrophotometer (Hitachi 330), converting the absorbance into reflectance using the following formula.

In addition, the heat resistance test results show that the recorded image was placed in a constant temperature bath at 60℃ for 24 hours.
Concentrations after storage for time are shown.

As is clear from Table 2, the recording material using the leuco dye of the present invention can be used in the near-infrared region, that is, 600-1.0O
It can be seen that it exhibits sufficiently strong absorption in the range of Or+m, and that the heat-resistant stability of its colored portion is also excellent, so that it has sufficient quality as a recording material.

(Additional Lambda Procedural Amendment (Spontaneous) August 30, 1988 1, Case Description 1988 Patent Application No. 137340 Address 1-3-6 Nakamagome, Ota-ku, Tokyo Name
(674) Rico Co., Ltd. - (1 person) Representative Hama 1) Hiro 1, Agent 151 Address 1-58-10 Yoyogi, Shibuya-ku, Tokyo -
Nishiwaki Building No. 113 Name (7450) Patent Attorney Toshiaki Ikeura Telephone (370)
) 2533 No. 5, Date of amendment order Voluntary 3, Number of inventions increased by amendment 07, Column 8 of "Detailed description of the invention" of the specification subject to amendment, Contents of amendment Amended as follows in the specification of the present application to hold.

(1) Table 1-2 on page 28 will be corrected as shown in the attached sheet.

Claims (1)

[Claims] (1) General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (In the formula, R_1, R_2, R_3 and R_4 are lower alkyl groups, R_5 is α- or β-naphthyl group or ▲
There are mathematical formulas, chemical formulas, tables, etc. ▼, R_6 is -NHC
OR_9, a halogen atom or a substituted amino group, and R
_7, R_8 and R_9 each represent a hydrogen atom or a lower alkyl group. However, when R_7 and R_8 are both hydrogen atoms, R_6 represents -NHCOR_9 or a bromine atom. ) A novel leuco dye represented by