JPH02217288A - Heat sensitive recording material - Google Patents

Abstract

PURPOSE:To improve coloring properties and preservation stability by employing novel near infrared absorption leuco dye as electron donative colorant and employing specific phenol compound as electron acceptive substance. CONSTITUTION:In a heat sensitive recoding material containing normally achromatic or pale electron donative colorant and electron acceptive substance as coloring components, the colorant is a compound represented by a general formula (I). As the electron acceptive substance at least one type of compounds represented by general formulae (II), (III) is employed. Thus, reading in a bar code reader using a semiconductor laser is performed, and excellent coloring and image preservation area provided. In the formulae, R1-R8 are lower alkyl group, Y is R9-SO2, NH-, R10-Z-CONH-, etc., Z is a ring represented by a formula (I'), R9, R10 and H, lower alkyl group or halogen atom, R14 is 1-18C aralkyl group, R16 is 12-22C aryl group or aralkyl group, R15 is 12-22C alkyl group or aralkyl group.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a two-component coloring type heat-sensitive recording material, and more specifically, a novel near-infrared absorbing leuco dye is used as an electron-donating coloring agent, and a specific phenolic compound is used as an electron-accepting coloring material. It relates to a heat-sensitive recording material used as a substance. [Prior Art] A heat-sensitive recording material generally has a heat-sensitive recording layer on a support, the main components of which are an electron-donating, usually colorless or light-colored leuco dye, and an electron-accepting color developer. By heating with a thermal pen, laser light, etc., the leuco dye and the color developer react instantaneously and a recorded image is obtained. ing. Such heat-sensitive recording materials have the advantages of being able to record with a relatively simple device, being easy to maintain, and not generating noise.
Fax machines, printers, computer terminals,
It is used in a wide range of fields such as labels, ticket vending machines, etc. Especially thermal recording labels are POS (point of sale information management)
It is used for applications that require pasting after printing, such as system barcode labels, price display labels, and shipping/shipping labels. POS systems are becoming particularly popular in large-scale mass retailers such as supermarkets and department stores, chain specialty stores, and restaurants. Its purpose is to aggregate and analyze product sales information in order to clearly understand consumer needs and formulate rational management strategies. Currently, methods of optically reading codes and OCR characters using scanners are rapidly growing. Therefore, various printing methods are currently being tried, and among them, the thermal recording method can be said to be the most excellent. This is because the printing method is a method of recording images using chemical or physical changes in substances due to heating, and does not require development and fixing, nor does it require replenishment of printing ink. That is, it has many features such as being able to downsize and simplify the machine and speed up recording, and there is no need to worry about ink staining hands or products or ink fading. Furthermore, although He--Ne laser light with red light having a wavelength of 633 nm has traditionally been used to read colored images such as bar codes, semiconductor lasers have recently come into use. It can be directly modulated by electric current, can be miniaturized, is easy to use, and is low cost.Also, since the oscillation wavelength is in the near-infrared range of 700 to 1500 nm, there are fewer malfunctions caused by dirt, and it is widely used. It is becoming popular. Therefore, it is desired to obtain colored images that can be read with a semiconductor laser even on heat-sensitive recording labels. However, in the conventional two-component heat-sensitive recording material consisting of a leuco dye and a color developer,
Even in the black coloring system, the absorption wavelength of the colored image is 5 on the long wavelength side.
Because it has a wavelength of 50 to 620 nm, it can be read with a HeφNe laser beam, but it could not be read with a semiconductor laser having a near-infrared wavelength. Dyes and pigments that absorb in the near-infrared region have been known for a long time, such as phthalocyanine, quinacridone, and other chelate compounds of various metals, but these also have large absorption in the M range. Therefore, it cannot be used as a dye for thermal recording using normal methods. In order to be used for this purpose, it is necessary to form a so-called leuco substance, which is colorless or light-colored in itself, but can give a coloring structure when it comes into contact with an electron-accepting substance. Conventionally, several proposals have been made regarding leuco dyes having absorption in the near-infrared wavelength region. For example, JP-A-51-121035, JP-A-51-121037
No., JP-A-51-121038, JP-A-51-167
No. 979, JP-A No. 58-157779 and JP-A No. 6
1-165380 discloses divinyl-containing phthalide compounds, and JP-A-59-199757, JP-A-60-226871, JP-A-61-22076, and JP-A-62-104872 disclose divinyl-containing phthalide compounds. disclosed a spirofluorene phthalide compound, and further disclosed JP-A-57
Fluoran compounds are disclosed in Japanese Patent Laid-open No. 169484 and Japanese Patent Application Laid-open No. 196177/1983. [Problems to be Solved by the Invention] However, the compounds proposed in each of the above-mentioned publications have the following drawbacks, and the current situation is that no satisfactory color former has yet been obtained. For example, the divinyl-containing phthalide compound has the disadvantage that the compound itself is strongly colored yellow, and is difficult to synthesize and expensive. It has the disadvantage that near-infrared absorption is weaker than that of other materials. The present invention utilizes a novel leuco dye that, although colorless in itself, has a strong absorption band in the near-infrared region once it develops a color when it comes into contact with an electron-accepting substance. The purpose is to provide excellent heat-sensitive recording materials. [Means for Solving the Problems] According to the present invention, in a heat-sensitive recording material containing a normally colorless or light-colored electron-donating color former and an electron-accepting substance as color-forming components, the electron-donating color former contains the following: - Monna [in the formula, R3, R2, R1, R4, R5, R6, R7,
R8 is a lower alkyl group, and Y is R. , R9 and RIG are hydrogen atoms, lower alkyl groups or halogen atoms, R11 and R82 are hydrogen atoms (except when both are hydrogen atoms), cyano group or -CORI 3, R is an alkyl group , alkoxy group,
represents an optionally substituted phenyl group or an optionally substituted naphthyl group, respectively], and the electron-accepting substance is a compound represented by the following formula: represents an alkyl group, aryl group or aralkyl group having 1 to 18 carbon atoms]+10 [wherein R, represents an alkyl group or aralkyl group having 12 to 22 carbon atoms] A heat-sensitive recording material is provided. In the above, examples of lower alkyl groups include methyl, ethyl, propyl, butyl, pentyl and hexyl groups, and examples of lower alkoxy groups include methoxy, ethoxy, propoxy, butoxy and pentoxy groups. Examples of the halogen atom include chlorine, bromine, and iodine. That is, the heat-sensitive recording material of the present invention uses the leuco dye represented by the above-mentioned -Momona (1) as an electron-donating coloring agent, and the above-mentioned -Momona (II) as an electron-accepting substance that causes the leuco dye to develop color when heated. ) and (n[), which makes it possible to read it with a barcode reader using a semiconductor laser and has excellent color development and image storage stability. becomes. The leuco dye represented by the above-mentioned pattern (1) used in the present invention is a colorless to light-colored crystal and has no absorption in the near-infrared region, but it turns blue or dark blue when it reacts with a color developer. The system develops color, and the colored image has strong absorption in the near-infrared region. The leuco dye represented by the above-mentioned pattern (I) can provide sufficient contrast even when colored alone, but
It is also possible to use other leuco dyes in combination to adjust the color tone. Specific examples of the compound represented by the above-mentioned symbol (1) include those shown below, but the present invention is not limited thereto. 1.1,5.5-tetrakis-(p-dimethylaminophenyl)-1,4-pentadiene-3-p-toluenesulfonamide, 1.1,5.5-tetrakis-(p-dimethylaminophenyl)- 1,4-pentadiene-30-toluenesulfonamide, 1.1.5.5-tetrakis-(p-dimethylaminophenyl)-1,4-pentadiene-3-benzenesulfonamide, 1.1,5.5- Tetrakis-(p-diethylaminophenyl)-1,4-pentadiene-3-p-toluenesulfonamide, 1.1.5.5-Tetrakis-(p-diethylaminophenyl)-1,4-pentadiene-3-. -toluenesulfonamide, 1.1,5.5-tetrakis-(p-diethylaminophenyl)-1,4-pentadiene-3-benzenesulfonamide, 1.1,5.5-tetrakis-(p-dimethylaminophenyl )-1,4-pentadiene-3-p-chlorobenzenesulfonamide, 1,1,5,5-tetrakis-(
p-dimethylaminophenyl)-1,4-pentadiene-3-〇-aminobenzenesulfonamide, 1.1,5
．． 5-tetrakis-(p-dimethylaminophenyl)-
1,4-pentadiene-3-p-aminobenzenesulfonamide, 1,1,5,5-tetrakis-(p-dimethylaminophenyl)-1,4-pentadiene-3-p-
Dimethylaminobenzenesulfonamide, 1.1,5.
5-tetrakis-(p-dimethylaminophenyl)-1
,4-pentadiene-3-α-naphthalenesulfonamide, 1.1,5,5-tetrakis=(p-dimethylaminophenyl)-1,4-pentadiene-3-β-naphthalenesulfonamide, 1.1,5 .5-tetrakis-(p-diethylaminophenyl)-1,4-pentadiene-3-α-naphthalenesulfonamide, 1.1,5.5-tetrakis-(p-diethylaminophenyl)-1,4-pentadiene-3 -4-naphthalenesulfonamide, 1.1,5.5-tetrakis-(p-dimethylaminophenyl)-1,4-pentadiene-3-benzamide, 1.1,5.5-tetrakis-(p-diethylaminophenyl )-1,4-pentadiene-3=benzamide, 1.1,5.5-tetrakis-(p-dimethylaminophenyl)-1,4-pentadiene-3-p-methylbenzamide, 1.1,5.5 -tetrakis-(p-diethylaminophenyl)-1,4-pentadiene-3-p-methylbenzamide, 1.1,5.5-tetrakis-(p-dimethylaminophenyl)-1,4-pentadiene-3-p -Chlorbenzamide, 1.1,5.5-tetrakis-(p-diethylaminophenyl)-1,4-pentadiene-3-p-chlorobenzamide, 1.1,5. ra-tetrakis-(p-dimethylaminophenyl)-1,4-pentadiene-3-p-trifluoromethylbenzamide, 1.1.5.5-tetrakis-(p-jethylaminophenyl)-1,4- Pentadiene-3-p-trifluoromethylbenzamide, 1.1
, 5.5-tetrakis-(p-dimethylaminophenyl)-1,4-pentadiene-3-p-hydroxybenzamide, 1.1,5.5-tetrakis-(p-dimethylaminophenyl)-1,4- Pentadiene-3-p-aminobenzamide, 1.1.5.5-tetrakis-(p-dimethylaminophenyl)-1,4-pentadiene-3-p-nitrobenzamide, 1.1,5.5-tetrakis- (p-dimethylaminophenyl)-1,4-pentadiene-3-p-dimethylaminobenzamide, 1.1,5.5-tetrakis-(p-dimethylaminophenyl)-1,4-pentadiene-3-〇- Methylbenzamide, 1.1,5.5-tetrakis-(p-dimethylaminophenyl)-1,4-pentadiene-3-〇-chlorobenzamide, 1.1,5.5-tetrakis-(p-dimethylaminophenyl) )-1,4-pentadiene-3-p-amidobenzamide, 1.1.5.5-tetrakis-(p-dimethylaminophenyl)-1,4-pentadiene-3-α-naphthamide, 1.1.5 .5-tetrakis-(p-dimethylaminophenyl)-1,4-pentadiene-3-β-naphthamide, 1.1.5.5-tetrakis-(p-diethylaminophenyl)-1,4-pentadiene-3- α-naphthamide, 1.1.5.5-tetrakis-(p-diethylaminophenyl)-1,4-pentadiene-3-β-naphthamide, 1.1,5.5-tetrakis-(p-dimethylaminophenyl) -1,4-pentadiene-3-malononitrile, 1.1,5.5-tetrakis-(p-dimethylaminophenyl)-1,4-pentadiene-3-acetophenone, 1.1,5.5-tetrakis- (p-dimethylaminophenyl)-1,4-pentadiene-3-β-acetylnaphthalene, 1.1.5.5-tetrakis-(p-dimethylaminophenyl)-1,4-pentadiene-3-acetylacetone, 1 .1,5.5-tetrakis-(p-dimethylaminophenyl)-1,4-pentadiene-3=dibenzoylmethane, 1.1,5.5-tetrakis-(p-dimethylaminophenyl)-1,4 -Pentadiene-3-malonic acid dimethyl ester, 1.1,5.5-tetrakis-(p-diethylaminophenyl)-1,4-pentadiene-3-malonic acid dimethyl ester, 1.1,5.5-tetrakis- (p-dimethylaminophenyl)-1,4-pentadiene-3-malonic acid diethyl ester, 1.1.5.5-tetrakis-(p-dimethylaminophenyl)-1,4-pentadiene-3-malonic acid diethyl ester -n
-butyl esters, etc. In the present invention, at least IPJ of the phenolic compounds represented by the general formulas (n) and (m) is used as the electron-accepting substance that causes the leuco dye to develop color by heating. By doing so, it is possible to obtain a heat-sensitive recording material that satisfies both color development and image storage properties. Specific examples of the compounds represented by the general formulas (■) and (III) include those shown below, but the present invention is not limited thereto. Specific examples of compounds of general formula (II) methyl-3,4-dihydroxybenzoate, ethyl-
3,4-dihydroxybenzoate, n-propyl-3
, 4-dihydroxybenzoate, n-butyl-3,4-dihydroxybenzoate, n-octyl-3,4-dihydroxybenzoate, n-dodecyl-3,4-dihydroxybenzoate, n-hexadecyl-3,4-dihydroxybenzoate, n-octadecyl-3,4-dihydroxybenzoate, phenyl-3,4-dihydroxybenzoate, naphthyl-3,4-dihydroxybenzoate, benzyl-3
, 4-dihydroxybenzoate, 2'-methylbenzyl-3,4-dihydroxybenzoate, 4'-methylbenzyl-3,4-dihydroxybenzoate, 2'-chlorobenzyl-3,4-dihydroxybenzoate, 4'-chlorobenzyl -3,4-dihydroxybenzoate, α-naphthylmethyl-3,4-dihydroxybenzoate, 2″-methyl-α-naphthylmethyl-3,4-dihydroxybenzoate, etc. Specific examples of compounds of general formula (III) Gallic acid -n-dodecyl ester, gallic acid-n-hexadecyl ester, gallic acid-n-
Octadecyl ester gallic acid-n-tocosyl ester, gallic acid benzyl ester, gallic acid-4'-methylbenzyl ester, gallic acid-
4'Chlorbenzyl ester, gallic acid-2',4''-
Dichlorobenzyl ester, gallic acid-2-monochlorobenzyl ester, gallic acid phenethyl ester, gallic acid-4゛-methyl phenethyl ester, gallic acid-α-naphthyl methyl ester, gallic acid-2゛-methyl-α-naphthyl ester methyl ester etc. In the present invention, the phenolic compound is preferably added in an amount of 0.1 to 6 parts by weight per 1 part by weight of the leuco dye. When bonding the leuco dye and phenolic compound onto a support in order to produce the heat-sensitive recording material of the present invention, various commonly used binders can be used as appropriate, and specific examples thereof include, for example, These include: Polyvinyl alcohol, starch and its derivatives, cellulose derivatives such as methoxycellulose, hydroxycellulose, carboxymethylcellulose, methylcellulose, ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide/acrylic acid ester copolymer, acrylamide/acrylic acid ester/methacrylic acid Water-soluble polymers such as ternary copolymers, styrene/maleic anhydride copolymer alkali salts, isobutylene/maleic anhydride copolymer alkali salts, polyacrylamide, sodium alginate, gelatin, and casein, as well as polyvinyl acetate , polyurethane, polyacrylic acid ester, polymethacrylic acid ester, emulsions such as vinyl chloride/vinyl acetate copolymer, ethylene/vinyl acetate copolymer, and latex such as styrene/butadiene/acrylic copolymer. In addition to the above-mentioned leuco dye and phenolic compound, in the present invention, if necessary, auxiliary additive components commonly used in this type of heat-sensitive recording material, such as fillers, dispersants, color image stabilizers, antioxidants, etc. A light stabilizer, a fluorescent whitening agent, a surfactant, a thermofusible substance (or a lubricant), etc. can be used in combination. In this case, fillers include, for example, calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay talc, surface-treated inorganic fine powders such as calcium and silica, etc. Examples include organic fine powders such as urea-formalin resin, styrene/methacrylic acid copolymer, and polystyrene resin. Examples of thermofusible substances include fatty acids such as stearic acid and behenic acid, fatty acid amides such as stearic acid amide and palmitic acid amide, zinc stearate,
aluminum stearate, calcium stearate,
Fatty acid metal salts such as zinc palmitate and zinc behenate,
p-benzylbiphenyl, terphenyl, triphenylmethane, benzyl p-benzyloxybenzoate, β-benzyloxynaphthalene, β-naphthoic acid phenyl ester, 1-hydroxy-2-naphthoic acid phenyl ester, 1-hydroxy-2- naphthoic acid methyl ester,
Diphenyl carbonate, dibenzyl terephthalate, dimethyl terephthalate, 1,4-dimethoxynaphthalene, 1,4-jethoxynaphthalene, 1.
4-dibenzyloxynaphthalene, 1,2-bis(phenoxy)ethane, 1,2-bis(3-methylphenoxy)ethane, 1,2-bis(4-methylphenoxy)ethane, 1,4-bis(phenoxy) ) Butane, 1,4-bis(phenoxy)-2-butene, dibenzoylmethane, 1
, 4-bis(phenylthio)butane, 1,4-bis(phenylthio)2-butene, 1,3-bis(2-vinyloxyethoxybenzene, 1.4-bis(2-vinyloxyethoxy)benzene, p- (2-vinyloxyethoxy)biphenyl, p-aryloxybiphenyl, p-
Propargyloxybiphenyl, dibenzoyloxymethane, 1.3-dibenzoyloxypropane, dibenzyl sulfide, 1.1-diphenylethanol, 1.1-
Diphenylbrobanol, p-(benzyloxy)benzyl alcohol, 1,3-diphenoxy-2-propatol, N-octadecylcarbamoyl-p-methoxycarbonylbenzene, N-octadecylcarbamoylbenzene, and the like. Paper is mainly used as the support for the heat-sensitive recording material of the present invention, but various nonwoven fabrics, plastic films, synthetic papers, metal foils, etc., or composite sheets made of a combination of these can also be used as desired. The heat-sensitive recording material of the present invention is generally used in ordinary facsimiles,
In addition to being used in printers, it is also used for special purposes that detect near-infrared light. When a high preservability of a colored image is desired depending on the application, for example when used for a label, a protective layer may be laminated on the heat-sensitive recording layer to protect the uncolored area and the colored image area from the external environment. in this case,
As the main component of the protective layer, various water-soluble resins, latex, and photocurable resins are used. Further, fillers, water-resistant agents, water repellents, antifoaming agents, ultraviolet absorbers, etc. can be added as necessary. Further, for use as a label, an adhesive layer may be provided on the back surface so that after printing, the label can be attached to a container on another solid surface. In this case, a release paper is provided on the adhesive layer. (Example) Next, the present invention will be explained in more detail with reference to Examples. Note that all percentages shown below are based on weight. Example 1 [Liquid A] to [Liquid C] were prepared by dispersing each mixture having the following composition using a ball mill. [Liquid A] 1.1.5.5-tetrakis-(p-dimethylaminophenyl)-1,4-pentadiene-3-malonic acid dimethyl ester hydroxyethyl cellulose 10% aqueous solution 10 parts water
55 parts The volume average particle diameter of the dispersed particles of the leuco dye was 2.16 μm. [Liquid B] Calcium carbonate 30 parts Methyl cellulose 5% aqueous solution 30 parts Powder
2 parts water
60 parts [Liquid C] Gallic acid stearyl ester 40 parts Polyvinyl alcohol 10% aqueous solution 20 parts Water
140 parts [Liquid A] and cBB11cLiquid C] obtained as above were mixed in a ratio of 1:4:
3 to create a coating liquid, and this coating liquid has a basis weight of 50.
g/rrr dry adhesion amount on high quality paper is 0.4 with dye alone
It was coated at a concentration of 5 g/rrr and dried to obtain heat-sensitive recording paper. The thermal recording paper thus obtained was tested at 130°C for 1 second (applied pressure: 2°0 kg/c) using a thermal gradient tester.
d) to develop color. The color density at this time was 0.95 when measured with a black filter of a Macbeth RD-918 densitometer, and the background density was 0.08. Further, the coloring tone is blue, the background part is white, and the absorption region of the coloring part is about 500 to 900 nm, and has a fairly strong absorption. The reflection spectrum is shown in FIG. Example 2 Each mixture having the following composition was dispersed in a ball mill and [
Solution A] to [Solution E] were prepared. [Liquid A] 1.1.5.5-Tetrakis-(p-dimethylaminophenyl)-1,4-pentadiene-3-malonic acid dimethyl ester 10 parts Hydroxyethylcellulose 10
% aqueous solution 10 parts water
55 parts The volume average diameter of the dispersed particles of leuco dye is 2.
It was 16 μm. [Liquid B] Calcium carbonate 30 parts Methyl cellulose 5% aqueous solution 30 parts Powder
2 parts water
60 parts [Liquid C] Gallic acid stearyl ester 40 parts ■υ 10% polyvinyl alcohol aqueous solution 20 parts water
140 copies [
Solution D] PSD-150 (manufactured by Nippon Soda Co., Ltd.) 10 parts hydroxyethyl cellulose 10% aqueous solution 10 parts water
55 parts The volume average particle diameter of the leuco dye was 2.5 μm. [Liquid E] Zinc stearate 1-0 parts Polyvinyl alcohol 10% aqueous solution 10 parts Water
30 copies obtained as above

[Liquid B]

Calcium carbonate 30 parts Methyl cellulose 5% aqueous solution 30 parts Powder
2 parts water
60 parts cC solution] Gallic acid stearyl ester 40 parts polyvinyl alcohol 10% aqueous solution 20 parts water
140 parts ED liquid] PSD-150 [manufactured by Nihon Kuchitatsu] 10 parts hydroxyethyl cellulose 10% aqueous solution 10 parts water
55 parts The dispersed particles of leuco dye have a volume particle diameter of 2
．． It was 5 μ-. [Liquid E] Stearin M zinc 10 parts polyvinyl alcohol 10% aqueous solution 10 parts water
30 parts [Liquid I], [Liquid B, ECC12ED] obtained as above
Prepare a coating liquid by mixing [liquid] and [liquid E] in a ratio of 1:4:3:1:1, and apply this coating liquid to a paper with a basis weight of 5 Gg/*' with a dry adhesion amount of rH liquid] 0.45g/s for dye alone
The thermal recording paper thus obtained was tested at 130°C for 1 second (applied pressure: 2.0 kg/am2) using a thermal gradient tester.
) to develop color. The color density at this time is Macbeth I?
When measured with a black filter of a D-918 type densitometer, it was 48 l, and the background density was 0.09. Further, the color tone is black, the background area is white, and the absorption range of the coloring area is from about 300 to 900 nm, which is a fairly strong absorption. The reflection spectrum is shown in FIG. The results of the storage stability test of the obtained thermal recording paper are shown in the following table. note,! ) Image area survival rate Image area survival rate - to Z Nagisa 2 = z; 2) Fogging on the skin ○... There is almost no fogging Δ... There is fogging without any practical problems) ×... Fogging 3) Stored in a dry state at 80°C for 16 hours 4) At 40°C, Store at 90% humidity for 16 hours5) 5000
From the table of storage under Lux light for 16 hours, it can be seen that the recording paper of the present invention shows no change in both the image area and the background area after storage compared to before storage, and is particularly excellent in the image area. Furthermore, the background color tone immediately after printing is white and excellent. Example 5 Each mixture having the following composition was dispersed in a ball mill and [
L solution], [B solution] and

[Liquid C] was prepared. [I liquid]

1.1,5.5-tetrakis-(p-dimethylaminophenyl)-1,4-pentadiene-3-P-)luenesulfonamide 10% aqueous solution of hydroxyethyl cellulose 10 parts water
55 parts The dispersed particles of the leuco dye had a volume average particle diameter of 3.14 .mu.m. [Liquid B] Calcium carbonate 30 parts Methyl cellulose 5% aqueous solution 30 parts Powder
2 parts water
60 parts [Liquid C] Galic acid stearyl ester +10 +10 10% polyvinyl alcohol aqueous solution 20 parts water
140 parts cI solution obtained as above], [Solution B], [Solution C]
Prepare a coating liquid by mixing them in a ratio of 1:423, and apply this coating liquid on a high-quality paper with a size of 50 g/w' so that the dry weight of the dye alone is 0.45 g/m'. The mixture was dried to obtain heat-sensitive recording paper. The thermal recording paper thus obtained was tested at 130°C for 1 second using a thermal gradient tester (applied pressure 2.0 kg/c plate 2).
Colored with. The color density at this time is Macbeth RD-
When measured with the black filter of the 9111 type densitometer, it was 1.
．． 19, and the background density was 0.08. Further, the color tone is deep blue, the background part is almost white, and the absorption range of the coloring part is about 500 to 900n dust, which is a fairly strong absorption. The reflection spectrum is shown in FIG. Example 6 Each mixture having the following composition was dispersed in a ball mill and [
[Liquid I], [Liquid B], [Liquid C], [Liquid D], and [Liquid E] were prepared. [Liquid I] 1.1,5.5-tetrakis-(p-dimethylaminophenyl)-1,4-pentadiene-3-P-)luenesulfonamide 10 parts hydroxyethyl cellulose l (1% aqueous solution 10 parts water
55 parts The volume average particle diameter of the dispersed particles of the leuco dye was 8.14 μm. cB Solution J Calcium carbonate 30 parts Methylcellulose 5% aqueous solution 30 parts Powder
2 parts water
60 parts cC liquid] Gallic acid stearyl ester 40 parts polyvinyl alcohol 10% aqueous solution 20 parts water
140 parts [Liquid D] PSD-150 [manufactured by Nippon Soda ■ 1 10 parts hydroxyethyl cellulose 10% aqueous solution 10 parts water
55 parts The dispersed particles of leuco dye have a volume particle diameter of 2.
It was 5μ■. [Liquid E] Zinc stearate 10 parts Polyvinyl alcohol 10% aqueous solution 10 parts Water
30 parts [1 solution], cB solution], [C solution], cD solution] obtained as above,
Create a coating liquid by mixing [Liquid E] in a ratio of 1:4:3:1:1, and apply this coating liquid onto high-quality paper with a basis weight of 5Qg/■2 so that the dry adhesion amount is only [Liquid I] dye. 0.45 g/s'' and dried to obtain thermal recording paper.The thermal recording paper thus obtained was tested using a thermal gradient tester at 1°C for 1 second (applied pressure 2.0kg/cm'
) to develop color. The color density at this time is Macbeth R
When measured with a black filter of a D-918 type densitometer, it was 1.50, and the background density was 0.09. Further, the color tone is black, the background portion is almost white, and the absorption range of the coloring portion is about 300 to 900 ni, which is a fairly strong absorption. The reflection spectrum is shown in FIG. The results of the storage stability test of the obtained thermal recording paper are shown in the following table. Table 3 Note: 1ull image area residual rate 2) Fog on the background 0... There is almost no fog... There is some fog without any practical problems) ×... There is some fog 3) Dry at 60℃ 4) Store at 40℃ and 90% humidity for 16 hours 5) 5000
From the table of storage under LL11 light for 16 hours, it can be seen that the recording paper of the present invention shows no change in both the image area and the background area after storage compared to before storage, and is particularly excellent in the image area. Furthermore, the background color tone immediately after printing is white and excellent. [Effects of the Invention]' The heat-sensitive recording material according to the present invention using at least one of the leuco dye represented by the above-mentioned -Kaburi (1) and the phenolic compound represented by the above-mentioned -Kaburi (II) and (II-ri), The advantage is that the colored image has a strong absorption capacity of about 400 to 900 rv, and can be fully read by a general-purpose OCR (optical character reader), an image reading device using a light emitting diode, or a semiconductor laser as a light source. In addition, it has a high color density and the color image has excellent storage stability (heat resistance, water resistance, light resistance, etc.).

[Brief explanation of the drawing]

FIG. 1 is a graph showing the reflection spectrum of the colored part of the thermal recording paper obtained in Example 1, and FIG. 2 is the same graph obtained in Example 2.
Figure 3 is the same graph obtained in Comparative Example 1, Figure 4 is the same graph obtained in Comparative Example 2, Figure 5 is the same graph obtained in Example 3, and Figure 6 is the same graph obtained in Comparative Example 2.
The figure shows the same graph obtained in Example 4, FIG. 7 shows the same graph obtained in Example 5, and FIG. 8 shows the same graph obtained in Example 6. ζυ

Claims (1)

[Claims] (1) In a heat-sensitive recording material containing a normally colorless or light-colored electron-donating color former and an electron-accepting substance as coloring components, the electron-donating color former has the following general formula (I) ▲Mathematical formula, chemical formula, table, etc. ▼(I) [In the formula, R_1, R_2, R_3, R_4, R_5, R
_6, R_7, R_8 are lower alkyl groups, Y is R_9
-Z-SO_2NH-, R_1_0-Z-CONH- or ▲There are mathematical formulas, chemical formulas, tables, etc.▼, Z is ▲There are mathematical formulas, chemical formulas, tables, etc.▼ or ▲There are mathematical formulas, chemical formulas, tables, etc.▼, R_9 and R_1_0 are hydrogen atoms, lower alkyl groups or halogen atoms; R_1_1 and R_1_2 are hydrogen atoms (except when both are hydrogen atoms), cyano groups or -COR_1_3; R_1_3 is alkyl groups, alkoxy groups, substituted each represents an optionally substituted phenyl group or an optionally substituted naphthyl group], and the electron-accepting substance is a compound represented by the following general formula (II) or (III) ▲ Numerical formula, chemical formula, table, etc. ▼(II) [In the formula, R_1_4 represents an alkyl group, aryl group, or aralkyl group having 1 to 18 carbon atoms] ▲There are numerical formulas, chemical formulas, tables, etc.▼(III) [In the formula, R_1_5 represents the number of carbon atoms 12-22 alkyl group or aralkyl group]
A heat-sensitive recording material characterized by being a seed compound.