JPS63189285A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a recording material with superior absorption in a near infrared area of 600-1,000nm or more and further, superior absorption in a near infrared area oven under high-temperature, high-humidity or sun-exposed environments by providing at least a specific compound as one kind of leuco dye and at least a specific nitro zinc benzonate as one kind of color developer. CONSTITUTION:In a thermal recording material using coloring reaction between a leuco dye and a color developer which makes the leuco dye develop a color in contact with the latter, at least one kind of leuco dye is a compound expressed in the formula I, and at least one kind of developer is nitro zinc benzonate expressed by the formula II. The thermal recording material shows a conspicuously improved reading property in a near infrared area by adding a developer of leuco dye in the formula I and nitro zinc benzonate in the formula II. At the same time, an image obtained has a superior absorption in a near infrared area even under high-temperature, high-humidity and long sun-exposed environments.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a recording material for heat-sensitive, pressure-sensitive or laser recording, etc., which also has absorption in the near-infrared region.

[Prior art]

Recording materials using leuco dyes have been known for a long time.
It is used as pressure-sensitive recording paper, heat-sensitive recording paper, etc., and its usage is increasing year by year.

A leuco thermosensitive recording material has a leuco dye and a coloring agent supported on a support, and produces a colored image when an image signal is thermally applied to it by a minute heating resistor element.

Compared to other recording materials, such as electrophotographic and electrostatic recording materials, such thermal recording paper can be used to record in a short time using relatively simple equipment without the need for complicated processes such as development and fixing. It is used in many ways because of the benefits it provides. The main leuco dyes used in such recording materials are:
These include blue dyes represented by crystal violet lactone and leuco crystal violet, and black dyes represented by 7-position anilino-substituted fluoran compounds.

In recent years, optical character reading devices and label barcode reading devices have been developed, and their usage is increasing. However, these devices use a light emitting diode or semiconductor laser as a light source with a light wavelength of 700 nm. The above light sources are commonly used. However, since the above-mentioned blue dye and black dye hardly absorb light in the near-infrared region of 700 nm or more, it is impossible to read the colored image with the above-mentioned reading device. Therefore, the light absorption wavelength of the coloring material is 7
At present, there is a strong demand for the development of new leuco dyes with 0On+i or more.

〔the purpose〕

The present invention provides a recording material that has strong absorption in the near-infrared region of 600 to 11,000 nm or more, and further has good absorption in the near-infrared region even in environments of high temperature, high humidity, or sunlight exposure. The purpose is to

〔composition〕

According to the present invention, in a recording material that utilizes a color-forming reaction between a leuco dye and a color developer that causes the leuco dye to develop color upon contact, at least one of the leuco dyes is represented by the following general formula (1). Provided is a heat-sensitive recording material, wherein at least one of the color developers is zinc nitrobenzoate represented by the following general formula (TI).

(In the formula, R1: alkyl group having 1 to 6 carbon atoms R2, R1:
A straight chain or branched alkyl group having 1 to 6 carbon atoms, a cycloalkyl group, a benzyl group.

However, R2 and R1 may be bonded to each other to form a ring.

BAA or -0R4 R4: Alkyl group having 1 to 6 carbon atoms C: A or hydrogen) The heat-sensitive recording material of the present invention contains a color developer consisting of a leuco dye represented by the general formula (1) and zinc nitrobenzoate. When used in combination, readability in the near-infrared region is dramatically improved, and the resulting images have good readability in the near-infrared region even in environments where the image is exposed to high temperatures, high humidity, and sunlight for long periods of time. It has good absorption.

Specific examples of the basic dye represented by general formula (1) include:
Examples include those shown below.

Examples of the zinc nitrobenzoate compound represented by the general formula (n) include 3-nitrobenzoic acid, zinc 4-nitrobenzoate, and the like.

In the present invention, the leuco dye represented by the above general formula (1) can be used in combination with other leuco dyes, and in this case, the leuco dye used in combination is generally known for this type of leuco recording material. Leuco dyes are used, and for example, leuco compounds of triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, spiropyran-based, and indolinophthalide-based dyes are preferably used.

Specific examples of such leuco dyes include those shown below.

3.3-bis(p-dimethylaminophenyl)-phthalide, 3.3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (also known as crystal violet lactone)% 3.3-bis(p- dimethylaminophenyl)-6-diethylaminophenyl, 3.3-bis(p-dimethylaminophenyl)-6-chlorophthalide, 3.3-bis(p-dibutylaminophenyl)phthalide, 3-cyclohexylamino-6-chlor fluorane,
3-dimethylamino-5,7-dimethylfluorane, 3
-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane.

3-diethylamino-7,8-benzfluorane, 3-
Diethylamino-6-methyl-7-chlorofluoran.

3-(N-P-tolyl-N-dithylamino)-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-(m-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-pyrylospiran, 3-(2'-hydroxy-4'-dimethylaminophenyl)-3- (2'-methoxy-5'-chlorophenyl)
Phthalide, 3-(2'-hydroxy-41-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-)-luidino)-7-(α-phenylethylamino)fluoran, 3-diethylamino-7- (0-Methoxycarbonylphenylamino)fluorane.

3-diethylamino-5-methyl-7-(α-phenylethylamino)fluorane, 3-diethylamino-7-piperidinofluorane, 2-
Chloro-3-(N-methyltoluidino)-7-(p-n
-butylanilino)fluoran, 3- (N-benzyl-N-cyclohexylamino)-
5,6-penzo 7-α-naphthylamino-4'-bromofluorane, 3-diethylamino-6-methyl-7-mesitidino 4
',5'-benzofluorane In the present invention, the above-mentioned color developer is used, but other color developers can be used in combination if necessary. In this case, the color developer used in combination includes: Various electron-accepting compounds that cause the leuco dye to develop color upon contact.

Alternatively, an oxidizing agent or the like is applied. Such substances are conventionally known, and specific examples thereof include inorganic acids, organic acids, phenolic substances, phenolic resins, etc. as shown below.

Bentonite, zeolite, acid clay, activated clay, silica gel, aluminum chloride, salicylic acid.

3-tert-butylsalicylic acid, 3,5-tert
t-Butylsalicylic acid, di1rchlorophenylthiourea, di+++-trifluoromethylphenylthiourea, di-phenylthiourea, salicylanilide, 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'-isopropylidene bis(2-tert-butylphenol)
, 4.4'-5ec-butylidene diphenol, 4-
tert-phthylphenol, 4-phenylphenol, 4-hydroxydiphenoxide, α-naphthol, β
- Naphthol, 3,5-xylenol, thymol, methyl-4-hydroxybenzoate, 4-hydroxyacetophenone, novolac type phenolic resin, 2.2'
-thiobis(4,6-dichlorophenol), catechol, resorcinol, hydroquinone, pyrogallol, phloroglycin, phloroglycin carboxylic acid, 4-tert-
Octylcatechol, 2,2'-methylenebis(4-chlorophenol), 2,2'-methylenebis(4-methyl-6-tart-butylphenol), 2,2'-dihydroxydiphenyl, ethyl p-hydroxybenzoate, Propyl p-hydroxybenzoate, butyl p-hydroxybenzoate, benzyl p-hydroxybenzoate, p
-Hydroxybenzoic acid-ρ-chlorobenzyl, p-hydroxybenzoic acid-0-chlorobenzyl, p-hydroxybenzoic acid-P-methylbenzyl, p-hydroxybenzoic acid-〇-octyl, benzoic acid, 1-hydroxy-2 -naphthoic acid, 2-hydroxy-6-naphthoic acid, 4-hydroxydiphenylsulfone, bis(4-hydroxy-3
-t-butylphenyl)sulfone, 4-hydroxy-4
'-Chlorodiphenylsulfone, bis(4-hydroxyphenyl)sulfide, 2-hydroxy-P-toluic acid, tartaric acid, oxalic acid, maleic acid, citric acid, succinic acid, stearic acid, 4-hydroxyphthalic acid, boric acid,
Biimidazole, hexaphenylbiimidazole.

Carbon tetrabromide etc.

In the present invention, to obtain a heat-sensitive recording material.

When a leuco dye and a color developer are bonded and supported on a support, various conventional binders can be used as appropriate. Here are some specific examples of such binders:

Examples include:

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

In addition, in the present invention, if necessary, auxiliary additive components 1 commonly used in this type of heat-sensitive recording material, such as fillers, surfactants, thermofusible substances, lubricants, pressure coloration inhibitors, etc., may be used in combination. Can be done. In this case, the filler is 1, for example,
In addition to inorganic fine powders such as calcium carbonate, silica, titanium oxide, aluminum hydroxide, barium sulfate, clay, talc, and surface-treated calcium and silica, urea-formalin resin, styrene/methacrylic acid copolymer, and polystyrene resin The thermofusible substances include, for example, higher fatty acids or their esters, amides (including their methylolated products), or metal salts, as well as various waxes and dimethyl terethalate. , condensates of aromatic carboxylic acids and amines, benzoic acid phenyl esters, higher linear glycols, 3,4-epoxy-
Examples include dialkyl hexahydrophthalate, higher ketones, and other heat-fusible organic compounds. If necessary, an undercoat layer consisting of a filler or a water-soluble binder may be added between the support and the heat-sensitive coloring layer. It is also possible to provide

The heat-sensitive recording material of the present invention can be used in various fields like conventional ones, but in particular, it can be used in optical literature readers and label barcoders by taking advantage of its excellent near-infrared light absorption properties. - Can be used as a recording material for reading records with a barcode reader.

When the recording material of the present invention is used as a heat-sensitive recording label sheet, a heat-sensitive color forming layer containing the above-mentioned leuco dye and color developer is provided on one side of the support, and an adhesive is provided on the other side of the support. It is sufficient to have a structure in which a release mount is provided between the layers, and in this case, if necessary, a protective layer such as a water-soluble resin layer may be provided on the surface of the heat-sensitive coloring layer in order to improve image stability. You can also do it.

〔effect〕

The heat-sensitive recording material of the present invention uses a special leuco dye represented by the above general formula (1), so that the colored image has absorption in the near-infrared region, and the image can be read using a general-purpose semiconductor laser. It has the advantage that the image can be read by a device, and is applied to various fields. moreover,
By using zinc nitrobenzoate represented by the above general formula (n) as a color developer, reading in the near-infrared region is dramatically improved, and furthermore, there is less fading of the image and less background fogging. be.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples. Note that all parts and percentages shown below are based on weight.

Example 1 Each liquid mixture having the following composition was dispersed using a sand glider for 2 to 4 hours to prepare [Liquid A] and [Liquid B].

[A liquid]

10% borinivir alcohol aqueous solution 10 parts water

80 parts [Liquid B] Zinc 4-nitrobenzoate 30 sounds 61
0% polyvinyl alcohol 30 parts water

40 parts Next, [Liquid A] and [Liquid B] were mixed and stirred at a weight ratio of 1:1 to prepare a heat-sensitive coating liquid. Apply this coating liquid to a high-quality paper with a basis weight of 52 g/rrr and dry weight of 4 to 5 g.
/rrf', dried, and calendered to give a Bekk smoothness of 500 to 3000 seconds to prepare a heat-sensitive recording material of the present invention.

Example 2 In the [^liquid] of Example 1, 3-(N-(p-dimethylamylphenyl)-N-methylamino)-phenyl-3-(bis(Ll-p-dimethylaminophenyl)ethylene-2 ) phthalide instead of 3-(N-(p-anisoyl)-N-methylamino)-phenyl-3-(bis(1+ 1-p-dimethylaminophenyl)ethylene-2)phthalide (the above specific example (17) It was prepared in the same manner as in Example 1 except that the compound (compound) was used.

Example 3 A liquid was prepared in the same manner as in Example 1 except that zinc 3-nitrobenzoate was used instead of zinc 4-nitrobenzoate in [Liquid B] of Example 1.

Comparative Example [CB solution of Example 2] was prepared in the same manner as in Example 1 except that 2,2-bis(p-hydroxyphenyl)propane was used instead of zinc 4-nitrobenzoate.

Print on the above four types of thermal recording paper using a regular printer,
The PCS value at 50nn+ was measured (a), and further, 4
The PO2 value at 850 nm was measured at 0° C. and 90% l1l (bottom) after being left for 24 hours (b) and after being left exposed to sunlight for 3 days (c). The results are shown in Table 1.

Table 1 As is clear from Table 1, the heat-sensitive recording material of the present invention has higher readability in the near-infrared region and less image fading than the comparative example.

Claims (1)

[Claims] (1) In a heat-sensitive recording material that utilizes a color-forming reaction between a leuco dye and a color developer that causes the leuco dye to develop color upon contact, at least one of the leuco dyes has the following general formula (
A heat-sensitive recording material, which is a compound represented by I), wherein at least one of the color developers is zinc nitrobenzoate represented by the following general formula (II). ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (I) (In the formula, R_1: Alkyl group A with 1 to 6 carbon atoms: ▲ Numerical formulas, chemical formulas, tables, etc. are available ▼ R_2, R_3: Direct groups with 1 to 6 carbon atoms Chain or branched alkyl group, cycloalkyl group, benzyl group.However, R_2 and R
_3 may be bonded to each other to form a ring. B: A or -OR_4 R_4: Alkyl group with 1 to 6 carbon atoms C: A or hydrogen) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (II)