JPH02147285A - Diazo thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a diazo thermal recording material enhanced in the preservability of a recording image and, especially, in a light fastness by providing a thermal recording layer consisting of a diazo compound, a coupling component and a binder on a support and containing a specific diazo compound in the thermal recording layer. CONSTITUTION:In a diazo thermal recording material, a thermal recording layer containing a diazo compound, a coupling component and a binder is provided on a support and a diazo compound represented by general formula (I) (wherein R1-R4 are a hydrogen atom, a substituted or non-substituted alkyloxy group or a substituted or non-substituted aryloxy group and may be same or different. X<-> is an acid anion and R5 and R6 are a substituted or non-substituted lower alkylene group) is contained in the thermal recording layer. The diazo compound represented by the general formula (I) pref. has an m.p. of 50-200 deg.C from the aspect of handling and is used within a range of 0.02-3g/m<2> in the thermal recording layer and more pref. used within a range of 0.1-2g/m<2> from the aspect of developed color density. The diazo compound can be used in a microencapsulated state.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a heat-sensitive recording material, and more particularly to a diazo heat-sensitive recording material with improved storage stability of recorded images.

(Prior Art) As a recording material used in a heat-sensitive recording method, a leuco color-forming heat-sensitive recording material is usually used. In this heat-sensitive recording material, an image is formed on the recording material by utilizing the fact that either the leuco dye or the acidic substance dispersed in the heat-sensitive recording layer is melted (by thermal energy) to cause a coloring reaction. It is something that will be done.

Since this recording material has low fixability for recorded images, it has the disadvantage that color develops in unexpected places due to harsh handling or heating after recording, staining the recorded image.

In recent years, research on diazo coloring type heat-sensitive recording materials has been actively conducted as a heat-sensitive recording material free from such drawbacks. For example, Japanese Patent Application Laid-Open No. 7-23016, Journal of the Image Electronics Engineers of Japan, //, Kota0 (/ritJ), etc., describe diazo compounds,
This document describes a recording material having a recording layer containing a color-forming component consisting of a coupling component and a basic component (including substances that become basic when heated). An image is formed on the recording material, the pressure is released, and the recording material is irradiated with light to decompose the unreacted diazo compound and stop color development (fixing).

However, even in recording materials that use diazo compounds,
Pre-coupling (coloring reaction) progresses gradually during the storage stage before recording, and unwanted coloring (fogging) tends to occur.

Various improvements have been made to eliminate this coloring (fogging). For example, one of the components involved in color development may be present in the form of discontinuous particles (solid dispersion), or one of the components involved in color development may be separated as a separate layer (%Kaikai17-/CoJOIt・No. Public notices) are being established. This is intended to prevent the progress of pre-coupling by preventing vibration between the K and C components. However, in both cases, although the shelf life (so-called raw shelf life) is improved considerably, the thermal responsiveness (meltability to heat), which is one of the important performances, tends to decrease.

Furthermore, as a technique for simultaneously improving both raw storage stability and thermal response, we have developed a method using non-polar waxy substances (% open l@17-Kosan IUI, JP-A-17-2434) or hydrophobic substances. It is known to encapsulate one of the color-developing components using a polymeric substance (Kokai No. 17-15' Ko 21) to isolate it from the other components.

These encapsulation methods involve dissolving a wax-like substance or a polymeric substance in a suitable solvent, and dissolving or dispersing a coloring component in this solution to form a capsule. This is different from the concept of a normal capsule covered with a shell. For this reason, when a capsule is formed by dissolving a color-forming component, the color-forming component does not necessarily become the core material of the capsule, but rather mixes uniformly with the encapsulating material, and pre-coupling gradually progresses at the wall interface of the capsule. In addition, when the coloring component is dispersed to form capsules, the coloring reaction does not occur unless the walls of the capsule are melted by heat, leading to problems such as a decrease in thermal responsiveness. Furthermore, the manufacturing problem of having to remove the solvent used to dissolve the waxy material or polymeric material after forming the capsules has not been fully satisfied.

Therefore, as a method to solve these problems, at least one of the components involved in the coloring reaction is contained in a core material, and a wall is formed around this core material by polymerization to form a microcapsule. Kaisho jter 1porr
Publication No. t, Japanese Unexamined Patent Publication No. Sho tO-44'PJ), etc. have also been proposed.

The diazo heat-sensitive recording material conventionally used in Toniro has the disadvantage that if left in a bright room or exposed to sunlight for a long time, the azo dye in the image area will decompose and fade, making the record difficult to read. Kuta.

In order to improve this drawback, methods of adding ultraviolet absorbers and anti-fading agents to the recording area have been studied, but it has rarely been possible to obtain sufficient effects.

It has been desired to improve the light resistance of the image area for the purpose of long-term storage, long-term outdoor use, and making multiple copies of recorded images as manuscripts.

(Line Layer to be Solved by the Invention) An object of the present invention is to provide a diazo thermosensitive recording material in which the storage stability of recorded images, particularly the light resistance, is improved.

(Means for Solving the Problem) The present invention provides a heat-sensitive recording material having on a support a heat-sensitive recording layer comprising a diano compound, a coupling component, and a binder, in which the heat-sensitive recording layer has the following general formula (1). ), where R-R4 is a hydrogen atom or a substitution or device! represents an alkyloxy or aryloxy group, and R-
R4 may be the same or different. X- represents an acid anion.

R6 and R6 each represent a substituted or unsubstituted lower alkylene group.

As a result of intensive research on diazo thermosensitive recording materials, the present inventor found that by using a diazo compound represented by the above general formula, the recorded image formed would be less likely to fade due to the source, and thus arrived at the present invention. be.

The heat-sensitive recording material of the present invention basically has a structure consisting of a support and a heat-sensitive recording layer provided thereon.

The heat-sensitive recording layer can be formed on the support, for example, by the method described below.

The heat-sensitive recording layer is a layer containing a diano compound represented by the general formula (1) and a coupling component in a dispersed state in a binder.

In the general formula (1), R1, R2, R3, R4,
Examples of substituents for R5 and R6 include alkyl groups, aryl groups, hydrocarbon groups, alkyloxy groups, aryloxy groups, alkylthio groups, arylthio groups, ester groups, amide groups, halogen atoms, and cyano groups.

The diazo compound represented by the above general formula (1) has a melting point J (
70C to λj00c is preferable, but from the viewpoint of handling etc., one in the range of jooc to λooQc is more preferable.

In addition, these diazo compounds have a temperature of 0°0λ to 0°0λ in the heat-sensitive recording layer.
It is preferable to use it in the range of sp/m2, but it is more preferable to use it in the range of 0, /-25E/m2 from the point of view of color development density, etc.

Specific examples are shown below, but it goes without saying that the present invention is not limited to these compounds.

l)/, goobis(2,j-dibutyloxy-hiro-diazophenyl)piperazine hexafluphorophos2neatco,)/, goobis(λ,!-dioctyloxy-
Di-diazophenylperazine hexafluorophosphate J)/, 4I-bis(J-butyloxy-Hiro-diazophenyl)piperazine hexafluorophosphate 4t)/, Gubis(J-C ethylhexyloxy)-Koichidiazophenyl) pienzine hexafluorophosphate J) /-(co,j-dibutyloxy-diazophenyl)-≠-(λ, r-dioctyloxy-≠-diazophenyl)giperazine hexafluorophosphate j)/, goobis (λ, !-dibutyloxy≠-diazophenyl)-/, 44-diazacyclohebutane hexafluorophosphate The above diazo compounds according to the present invention may be used alone, or λ or more types may be used in combination.

Furthermore, the diazo compound according to the present invention and known diazo compounds can be used together depending on the purpose such as hue adjustment.

The coupling component used in the present invention can be selected depending on the desired hue, including those that undergo a coupling reaction with the above-mentioned diazo compound and develop a color in a basic atmosphere. Specific examples of these! : For example, resorcinol, phloroglucin, λ, 3-hydroxynaphthalene sodium t-sulfonate, 2-hydroxy-3-
Sodium naphthalene sulfonate, λ-hydroxy-3
-Naphthalene K fonic acid anilide, λ-hydroxy-3-7talenesulfonic acid morpholinoamide, λ-hydroxy-3-7talenesulfonic acid morpholinopropylamide, seahydroxy-3-7talenesulfonic acid λ
-Ethylhexyloxypropylamide, λ-hydroxy-3-naphthalenesulfonic acid λ-ethylhexylamide, /-hydroxy-t-acetylaminonaphthalene-
3,6-disulfo/acid sodium,/-hydroxy-l
-Acetylaminonaphthalene-J, 4-disulfonic acid dianilide, 7-hydroxy-λ-7-esteric acid morpholinopropylamide, /, j-dihydroxyna 7-talene, 2
．． J-dihydroxynaphthalene, Co.

J-dihydroxy-t-7toic acid anilide, seahydroxy-3-7toic acid morpholinopropylamide, seahydroxy-3-7toic acid anilide, seahydroxy-3-7toic acid-λ' -methylanilide, -monohydroxy-J-7toic acid ethanolamide,
-monohydroxy-3-naphthoic acid octylamide, -monohydroxynaphthoic acid heptalpholinoethylamide, sea-hydroxynaphthoic acid piperidinopropylamide, sea-hydroxynaphthoic acid pi-lysinoetheramide, sea-hydroxy-3-naphthoic acid -N-Dodecyl-oxy-propylamide, C-hydroxy-3-naphthoic acid tetradecylamide, t-methoxy-C-hydroxy-3-su7
Toic acid anilide, t-ethyl ci-hydroxy-3-
7toic acid anilide, t-methoxy-1-hydroxy-
3-su7toic acid morpholinopropyl abad, 6-medoxy 2-hydroxy-J-7toic acid cohydroxyethyl abad, acetanilide, acetoacetanilide,
Pe/diylacetanilide, /-phenyl-3-methyl-! -Hirazolone, / -(2', Hiro1.al
),lichlorophenyl)-3-benzamide-yo-pyrazolone,/-(,2'p1.41)lichlorophenyl)-J-7nilino7-pi5''/ron,l-phenyl-3-phenylacetamide-j -Pyrazolones, etc. can be mentioned.

These coupling components may be used alone or
It is also possible to use nine or more types in combination. These coupling components are usually used in the range of 0.0j to zP/m2.

The round basic substance forming the basic atmosphere used in the present invention can generally be arbitrarily selected from organic basic substances and substances that generate dialkali upon heating. Specific examples of these include ammonium acetate, tricyclohexylamine, tripendylamine, octadecylbenzylamine, and stearylamine.
, 2-benzylimidazole, Hiro-phenylimidazole 1.2-phenyl-gumethyl-imidazole, undecyl-imidazoline, co-undecyl-imidazoline, j-)9furyl-co-imidazoline% / 9λ-cyphenyl-l, dimethyl-1-1 imidazoline, -monophenylcyimidazoline, /, 2. J-triphenylguanidine, /
,,2-ditolylguanidine,/,Sisicyclohexylguanidine,/,J.

3-Tricyclohexylguanidine, guanidine trichloroacetate, N,N'-dibenzyl p-Z-radine, p,
Examples include l-dithiomorpholine, morpholinium trichloroacetate, λ-aminobenzothiazole, λ-penzoylhydrazinopenzotheazole, and the like. These compounds may be used alone or in combination of two or more depending on the purpose.

Examples of binders used in the heat-sensitive recording layer include polyvinyl alcohol, methylcellulose, carboxymethylcellulose, hydroxypropylcellulose, gum arabic, gelatin, polyvinylpyrrolidone, casein, styrene-butadiene latex, acrylonitrile-butadiene latex, and polyvinyl acetate. , polyacrylic esters and ethylene-vinyl acetate copolymers, and these compounds are used in the form of various emulsions.

The amount of binder used is in the range of solids o, z-zy7m2.

For the heat-sensitive recording layer, a coating solution is prepared by mixing and dispersing a diazo compound, a coupling component, a basic substance, and a binder with an appropriate solvent using a 7 triter, a sand mill, etc., and then this coating solution is applied onto a support. A multilayer coating can be formed by coating and drying by a coating method such as par coating, blade coating, air knife coating, gravure coating, roll coating, spray coating, or dip coating.

Further, the diazo compound of the present invention can also be used in microcapsule form.

The method for forming microcapsules can be carried out using already known methods. It will be briefly described below.

First, the above-mentioned diano compound is dissolved or dispersed in a suitable organic solvent, and then this solution or dispersion (oil-based liquid) is emulsified and dispersed in an aqueous medium.

Examples of organic solvents include phosphoric acid esters, heptalic acid esters, carboxylic acid esters, fatty acid amides, alkylated biphenyls, alkylated terphenyls, chlorinated paraffins,
Alkylated naphthalenes, carbonic esters, diarylethanes, etc. are used.

Next, a wall made of a polymer material is formed around the emulsified and dispersed oil droplets. The adhesive actant is added to an oil-based liquid and/or an aqueous medium to form the polymeric material.

The polymeric material forming the capsule wall is impermeable at room temperature, but needs to become permeable when heated. Particularly preferred is one having a glass transition temperature of t0 to 0c.

Examples of these are polyurethane, polyurea, polyamide, polyester, urea/formaldehyde resin,
Examples include melamine resin, polystyrene, styrene/methacrylate copolymer, styrene/acrylate copolymer, and mixtures thereof.

As the microcapsule forming method, interfacial polymerization method and internal polymerization method are suitable.

For details on capsule formation methods and specific examples of reactants, see U.S. Pat.
, 724. It is stated in each specification of the Butri issue. For example, when polyurea polyurethane is used as a capsule wall material, a polyisocyanate and a second substance (e.g., polyol, polyamine) that reacts with it to form the capsule wall are mixed into an aqueous medium or an oily liquid to be encapsulated; By emulsifying and dispersing these in water and then heating them, a polymer formation reaction occurs at the oil part interface and a microcapsule wall is formed.

Incidentally, an auxiliary solvent having a low boiling point and strong dissolving power may be added to the oily liquid. Polyurea is produced even if the addition of the second substance is omitted.

Furthermore, when forming microcapsules, a water-soluble polymer compound can be used as a protective colloid. Examples of water-soluble polymer compounds include water-soluble anionic polymer compounds, nonionic polymer compounds, and amphoteric polymer compounds. can be mentioned.

These water-soluble polymer compounds contain 0.01-10% by weight
It is used as an aqueous solution.

A substance can be added to the heat-sensitive recording material to further improve the heat-recording density. Specifically, it is selected from compounds having a melting point of jO to /j00C (D range, preferably a temperature range of hyo oC to t3o'C) and having good compatibility with a diazo compound, a coupling component, or a basic substance. Examples include fatty acid amides, keto/compounds, ether compounds, urea compounds, and esters. These compounds are usually 7
Dispersed in particles of ~10 μm, solid content O2λ ~7 y
/ m” is used.

In addition, pigments such as kaolin, talc, silica, barium sulfate, titanium dioxide, aluminum hydroxide, zinc oxide, and calcium carbonate; and styrene beads, for the purpose of preventing sticking to heat heads and improving writing properties.
Fine powder of urea, melamine resin, etc. can be added. Similarly, metal soaps can also be used to prevent sticking. The amount of these additives added is usually in the range of 0.2 to 7 y/m.

In addition to the above-mentioned acetic acid additive, citric acid, tartaric acid, oxalic acid, boric acid, phosphoric acid, etc. can also be added as a stabilizer.

The recording layer is usually provided with a solid content in the range of j-ujf/m2.

The support used in the present invention can be arbitrarily selected from materials known as supports for heat-sensitive recording materials, such as high-quality paper, synthetic paper, and synthetic resin film, depending on the purpose. For example, as a paper support, heat-extracted pH-neutral paper (described in Japanese Patent Application Laid-Open No. 7-7II-7), which has been pushed with a neutral sizing agent such as an alkyl ketene dimer, has excellent storage stability over time. It is preferable. Other examples include JP-A-5
7-iit6r7, JP-A-Sho Jr-/36-Miri-No. 2, JP-A-Sho rr-+ri0ri No. 7, JP-A-Sho! t-A
j otsu? Papers such as those described in Japanese Patent Publication No. J and Japanese Patent Application Laid-Open No. 31-15 can be used.

Synthesis examples, examples, and comparative examples of the present invention are described below. However, these six examples do not limit the present invention. In addition, in the following six examples, "1 part" means "part by weight" unless otherwise specified.

(Synthesis example) /, 4I-bis(2,!-dibutyloxy-Hiro-diazophenyl)piperazine Synthesis of hexafluorophosphate (1) 4'-pibe2dinoco,! -Synthesis of dibutyloxynitrobenzene! -dibutyloxy-chlornitrobenzene 4
Parts of anhydrous piperazine≠3 parts, parts of anhydrous potassium carbonate λ, and 50 parts of N,N-dimethyl acedohydride were placed in a flask, and reacted for t hours at O~Rj'C after leaving a steam bath. .

After completion of the reaction, water was added to the reaction solution to dissolve inorganic substances, and the precipitated solid content was collected by F and purified to obtain 3 parts of ≠-piverazinoco, j-dibutyloxynitrobenzene. (Melting point 4P~?/0C) (2)/, 4cm screw (,2,j-
Synthesis of dibutyloxy-nitrophenyl) piperazine, j-dibutyloxynitrobenzene, co,! -Dibutyloxy-Hiro-Chlornitrobenzene≠! 1 part of anhydrous potassium carbonate and 50 parts of N,N-dimethylacetamide were placed in a Mitsuro flask and allowed to react on an oil bath at 10 to 20"C for 700 hours. After completion, the reaction solution was added to water to remove the precipitated solid. Acetone was added to the solid content to remove the soluble content, and /, $-bis(co,
! -dibutyloxy-nitrophenyl)pi is 297
Obtained 33 copies. (Melting point 133~1! Reference 0C) (3)/
, 4cm bis(2,j-dibutyloxy-≠-diazophenyl)pi is radine Synthesis of hexafluorophosphate 2 parts of reduced iron, 3 parts of ammonium chloride, 11 parts of water and 70 parts of inpropyl alcohol were placed in a three-piece flask. and refluxed. Among these /, $-bis(J,j-dibutyloxy-nidrophenyl)piperazine,
6 parts were added little by little.

Reflux f: Good for 3 hours. During the reaction, the reduced diamine compound precipitated and became viscous, so 50 parts of methanol was added to loosen it, and the diamine compound and excess reduced iron were combined and collected. The nine solids obtained were dissolved in N,N-dimethylformamide to remove reduced iron. Water was added to the furnace solution to precipitate the diamine compound. Recrystallization from N,N-dimethylformamide-acetone gave 11.7 parts of 1,Hiro-bis(co,!-dibutyloxy-aminophenyl)piperazine. (Melting point/44~76f'
C) This diamine compound l! , 3 parts to 100 parts of methanol,
It was added to 71 parts of water and 35 parts of concentrated hydrochloric acid.

Even worse? After adding 10.1 parts of potassium fluorophosphate, the whole was cooled to -100C'.

To this, add 1 part of sodium nitrite J and an aqueous solution to the internal temperature/
Add at a speed that does not exceed 00. After adding 9 minutes, stir 1 ft.
Crystals that showed time digits were collected by P. Recrystallization from acetone-ethyl acetate gave a yellow powder J, Part J.9. (Melting point/J7~ri'c) (Example) Example 1゜(1)'*''-bis(co,!-dibutyloxy-diazophenyl)piperazine Hexafluorophosphate J, J part, Tricle A core substance solution was prepared by mixing and dissolving 4 parts of ethyl phosphate, 1 part of ethyl acetate, 70 parts of trimethylolpropane trimethacrylate, and Bamboo D-ttoN (manufactured by Ota Pharmaceutical Co., Ltd.) for 1rst.

To this solution, 4jsK of a polyvinyl alcohol aqueous solution (l'fIL solution) was added, and the mixture was emulsified and dispersed with CO'C to obtain an emulsion having an average particle diameter of λμm. This emulsion was reacted with TOOC for 2 hours to obtain a microcapsule liquid.

(II)) Add 730 parts of Riphenylguanidine jt to 730 parts of polyvinyl alcohol aqueous solution <tin% solution) and add Dynomil (manufactured by Bouillier Pacofen AG).
to prepare a basic substance dispersion having an average particle size of 3 μm.

(lit), 54 parts of z-hydroxy-3-naphthoic acid anilide was added to 3 parts of a polyvinyl alcohol aqueous solution (1% by weight solution) and dispersed using a Dynomill (manufactured by V-Leaf Bacofuen AG) to obtain an average particle size. Diameter 3μ
A coupling component dispersion of m was prepared.

GV) 70 parts of microcapsule liquid, basic substance dispersion j
1 part, 6.7 parts of the coupling component dispersion liquid, and 11 parts of the calcium carbonate dispersion liquid (Hiro OX liquid) were mixed to prepare a coating liquid.

(V) Apply this coating solution to smooth high-quality paper (jo part/-L
) and dried at a temperature of ≠o'C for 30 minutes to produce a heat-sensitive recording sheet having a heat-sensitive recording layer of IQ parts/m 2 per dry layer.

Example λ.

Thermal reaction was carried out in the same manner as in Example 1, except that Hiro-bis(J-(J-ethylhexyloxy)-+-diazophenyl)piperazine (melting point: 70-/7≠07 parts) was used as the diazo compound. A record 7-t was produced.

Comparative example/.

A thermosensitive recording sheet was produced in the same manner as in Example 1 except that λ,j-dibutyloxy-l-morpholino-benzenediazonium hexafluorophosphate was used as the diano compound.

Comparative example λ.

A thermosensitive recording sheet #1 was produced in the same manner as in Example 1 using λ-octyloxy-l-morpholino-benzenediazonium hexafluorophosphate (melting point: //j-//4°C) as the diazo compound.

Next, the obtained thermosensitive recording sheet was colored using a hot plate. In both cases, clear blue images were obtained.

The obtained sample with a good image was irradiated with light for 7 hours using a fade meter. Changes in color density were measured using a Macbeth reflection densitometer (manufactured by Macbeth ■). The results are shown in Table 1.

As is clear from Table 1, it is clear that the recorded images obtained using the diazo compound according to the present invention are resistant to photofading.

Claims (2)

[Claims] (1) A heat-sensitive recording material having on a support a heat-sensitive recording layer containing a diazo compound, a coupling component, and a binder, characterized in that the heat-sensitive recording layer contains a diazo compound represented by the following general formula (I). A diazo thermosensitive recording material. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) R_1 to R_4 represent hydrogen atoms, substituted or unsubstituted alkyloxy, and aryloxy groups;
may be the same or different. X^- represents an acid anion. R_5 and R_6 each represent a substituted or unsubstituted lower alkylene group. (2) The diazo thermosensitive recording material according to claim 1, wherein the diazo compound represented by the general formula (I) is encapsulated in microcapsules.