JPH0459287A - Diazo heat sensitive recording material - Google Patents

Abstract

PURPOSE:To improve preservability before recording by incorporating specific compound as diazo compound in a heat sensitive recording medium having a heat sensitive recording layer containing diazo compound, coupling content, base and binder on a support. CONSTITUTION:In diazo compound represented by a formula (I), R1, R2, R3 are alkyl group, aralkyl group, aryl group, substituted alkyl group, substituted aralkyl group, substituted aryl group, and may be the same or different. However, it is desirable that the total number of carbons of the R1, R2, R3 is 12 or more, and more desirably 14 or more. The diazo compound is desirably used to be contained in a microcapsule so as to prevent precoupling, but since it is used by dissolving in suitable solvent (e.g. tricresyl phosphate) when the microcapsule is formed, it is desirable to have suitable solubility in the solvents. It is desirable to use the diazo compound in a range of 0.01-3g/m<2> in the recording layer, but in view of coloring density, it is used in a range of 0.1-2g/m<2>.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a diazo thermosensitive recording material. For more details,
This invention relates to a diazo thermosensitive recording material that forms a colored image consisting of a diazo compound, a coupling component, and a base.

(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 one of the leuco dye and the acidic substance dispersed in the heat-sensitive recording layer is melted by thermal energy, causing a coloring reaction. It is something.

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. 57-7λ30za4, Journal of the Image Electronics Engineers of Japan, l/, 2tyo (/91λ), etc. describe diazo compounds, coupling components, and basic components (including substances that become basic when heated). According to this recording material, an image is formed on the recording material by heating, and then the recording material is irradiated with light to remove unreacted components. It can decompose a diazo compound and stop (fix) color development.

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

Various improvements have been made to eliminate this coloration (capri). 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 (Japanese Unexamined Patent Publication No. 1983/JJort). ). This is intended to prevent contact between the components and prevent the progress of pre-coupling. However, in either case, although the storage stability (so-called raw storage stability) is improved satisfactorily, the thermal response (meltability to heat), which is one of the important performances, tends to decrease.

Furthermore, we developed a non-polar waxy material (Japanese Patent Application Laid-Open No. 7-4
44/G No. 1 Publication, JP-A-Sho, t7-/! It is known to encapsulate one of the color-forming components and isolate it from the other components using a hydrophobic polymeric substance (Japanese Patent Laid-Open Publication No. 1983/Takota≠μ).

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. For this purpose, 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 on the outer surface of the capsule wall. 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, there is a manufacturing problem in that the solvent used to dissolve the wax-like substance or polymeric substance must be removed after the capsules are formed, and this method is not completely satisfactory.

Therefore, as a rounding method to solve these problems, at least one pole 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 J day tqorr
Publication No. t, Japanese Unexamined Patent Publication No. Sho tO-44#J), etc. have also been proposed.

By the way, when conventional diazo thermosensitive recording materials are left in a high-temperature place for a long period of time and then subjected to color recording, the image density is often lower than the initial color image density. Improvements were desired.

One of the causes of the decrease in color image density is that the diazo compound contained in the color recording layer is decomposed and reduced by heat.

Diazo compounds are generally known as unstable compounds. Furthermore, the stability differs depending on whether it is in a crystalline state or in a solution state.

Known methods for increasing the thermal stability of diazo compounds include solvating with water, forming double salts, using strong acid anions, and adding acidic compounds.

However, when using a high purity diazo compound,
Therefore, when trying to obtain a diazo compound with high purity,
Purification operations such as recrystallization may be added, but in this case, stabilization by solvation or additives cannot be expected.

Furthermore, depending on the purpose of use, stabilization by solvation can be expected, and it may be used after being dissolved in an organic solvent.

For these purposes, it is necessary to further improve the thermal stability of diazo compounds.

Currently, the method of increasing stability by adding an acidic compound cannot necessarily be said to be effective when the base according to the present invention is also made to coexist.

In order to meet such demands, the present inventors conducted extensive research and found that a compound having four specific diazonium ion structures exhibits excellent thermal stability. (% Application No. 3≠θ Publication)
By using the compound disclosed in the publication, it is possible to obtain a recording material that has excellent preservability before recording (hereinafter referred to as raw preservability).

However, when performing the fixing operation (decomposing and deactivating unnecessary diazonium salts remaining on the thermal recording edge with light), which is a characteristic of diazo thermosensitive recording materials, the compound disclosed in Japanese Patent Application No. 23931-00 is used. The commonly used 4
A light source having a peak near tJOnm has the disadvantage that sufficient fixing cannot be achieved.

(Problems to be Solved by the Invention) The present invention provides a diazo thermosensitive recording material that has storage stability before recording (
The purpose of the present invention is to provide a diazo thermosensitive recording material with improved storage stability.

(Means for Solving the Problems) The present invention provides a heat-sensitive recording material having on a support a heat-sensitive recording layer comprising a diazo compound, a coupling component, a base, and a binder. This was achieved by a diazo thermosensitive recording material characterized by containing.

In formula (I), R1, R2, and R3 represent an alkyl group, an aralkyl group, an aryl group, a substituted alkyl group, a substituted aralkyl group, and a substituted aryl group, and R11R2 and R3 may be the same or different, respectively. However, s R1s R2
The total number of carbon atoms in R3 and R3 is preferably 72 or more, more preferably 1 or more.

Rls R2, R3 substituents include alkyl group, aryl group, hydroxy group, alkyloxy group, aryloxy group, alkylthio group, allylthio group, acyl group,
Examples include an alkoxycarbonyl group, an acyloxy group, a carbamoyl group, an acylamino group, a halogen atom, and a cyan group.

X represents a counter anion.

As a result of further research, the inventors found that the above-mentioned diazo compound is less likely to decompose due to heat and is widely used4.
It was discovered that fixing can be easily performed with a light source having a peak near LJOnm, and it was discovered that the conventional drawbacks could be solved by providing a heat-sensitive recording material using this, resulting in the present invention.

The diazo compound represented by the above general formula (I) has a melting point of 3
0°C or 000C is preferable, but from the point of view of handling! The range of 00C to /j00C is more preferable.

Furthermore, it is more preferable to use the diazo compound of the present invention by encapsulating it in microcapsules for the purpose of preventing precobbing, but when forming microcapsules, these compounds are used after being dissolved in an appropriate solvent (for example, tricresyl phosphate). It is desirable to have suitable solubility in the solvent. For this purpose, the compounds of the invention may be used in j%
It is preferable that the solubility is higher than that. Further, the water solubility is preferably 7% or less.

In addition, these diazo compounds are contained in the heat-sensitive recording layer in the range of 0°02 to
It is preferable to use it in the range of 3 g/m2, but
0. from the point of color density. It is more preferable to use it within the range of /-2 g/m2.

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

l) 0(n-C4Hg) C2H3 IO) //) No) 2H5 0(n-C+kita) le) The above diazo compound according to the present invention may be used alone, or may be used in combination with rice or more. .

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 is one that undergoes a coupling reaction with the above-mentioned diazo compound to develop color in a basic atmosphere, and can be selected depending on the desired hue. Specific examples of these include resorcin, phloroglucin, sodium -13-hydroxynaphthalene t-sulfonate, sodium co-hydroxy-3-naphthalene sulfonate, euhydroxy-3-naphthalene sulfonic acid anilide, -hydroxy-3-naphthalene Sulfonic acid morpholinoamide, cohydroxy-3-naphthalenesulfonic acid morpholinopropylamide, --hydroxy-3-naphthalenesulfonic acid coethylhexyloxypropylamide, λ-hydroxy-3
-Naphthalenesulfonic acid coethylhexylamide, l
-Hydroxy t-acetylaminonaphthalene-3,z-
Sodium disulfonate, l-hydroxy-t-acetylaminonaphthalene-3,6-disulfonic acid dianilide, l-hydroxyconaphthoic acid morpholinopropylamide, /, j-dihydroxynaphthalene, co, 3-dihydroxynaphthalene, 2゜3 -dihydroxy-t-naphthalenesulfonic acid anilide, non-hydroxy-3-naphthoic acid morpholinopropylamide, co-hydroxy-
3-S7-naphthoic acid anilide, co-hydroxy-3-naphthoic acid J/-methylanilide, co-hydroxy-3-naphthoic acid ethanolamide, 2-hydroxy-3-naphthoic acid octylamide, co-hydroxy-3-naphthoic acid morpholinoethylamide, code Hydroxynaphthoic acid piperidinoprobilamide, cohydroxynaphthoic acid piperidinoethylamide, cohydroxynaphthoic acid 3-naphthoic acid-
N-dodecyl-oxy-propylamide, cohydroxy-3-naphthoic acid tetradecylamide, t-methoxy-
, 2-hydroxy-3-naphthoic acid anilide, t-ethoxy-1-hydroxy-3-naphthoic acid anilide, 2-methoxy-λ-hydroxy-3-naphthoic acid morpholinopropylamide, t-methoxy-2-hydroxy-3-naphthoic acid anilide Acid co-hydroxyethylamide, acetanilide, acetoacetanilide, co-chloro 3-(21μ
mdi-t-7 milk enoxypropylaminocarbonyl)-piparoylacetanilide, benzoylacetanilide, /-phenyl-3-methyl-! -Hirazolone, /
-(ko/ , 4t/ , 4/ -trichlorophenyl) -j--<Nsamido! -Hirazolone, /-(2
',μ/,t,l-trichlorophenyl)3-anilino-! -Hirazolone, l-phenyl-3-phenylacetamide-! -Pyrazolones, etc. can be mentioned.

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

The basic substance for forming the basic atmosphere used in the present invention can generally be arbitrarily selected from organic basic substances and substances that generate alkali upon heating. Specific examples of these include ammonium acetate, tricyclohexylamine, tribenzylamine, octadecyl indylamine, stearylamine,
Cobenzylimidazole, μm phenylimidazole, cophenylu≠-methyl-imidazole, colandecyl-imidazoline, co, μ,! - trifuryl-co-imidazoline % / l cordiphenyl-a, a-dimethyl-co-imidazoline, 2-phenyl-co-imidazoline % / l λ, 3-triphenylguanidine, l
,2-ditolylguanidine,l,2-,)cyclohexylguanidine,/,J.

3-Tricyclohexylguanidine, quanidine trichloroacetate, N,N'-dinidine, Radin, Hiro, i
Examples include -dithiomorpholine, morpholinium IJ chloroacetate, coaminobenzothiazole, and λ-penzoylhydrazinopenzothiazole. 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, polyvinyl acetate, Mention may be made of polyacrylic esters and ethylene-vinyl acetate copolymers, and these compounds are used in the form of various emulsions.

The amount of binder used ranges from 0.1 to 7 g 7 m 2 solids.

The heat-sensitive recording layer is prepared by mixing and dispersing a diazo compound, a coupling component, a basic substance, and a binder with an appropriate solvent using an attritor, sand mill, etc. to prepare a coating solution, and then applying this coating solution onto a support. It can be formed by applying and drying using a coating method such as par coating, blade coating, air knife coating, gravito 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 diazo 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.

It is more preferable that the diazo compound of the present invention used for this purpose has appropriate solubility in an organic solvent.

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 reactant for forming the polymeric material is added to the oily liquid and/or the aqueous medium.

The polymer material forming the capsule wall is impermeable at room temperature and needs to become permeable when heated, and it is particularly preferable that the polymer material has a glass transition temperature of to-00c.

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 of capsule formation methods and specific series of reactants, see US Pat. No. 3.71t, t.

It is described in the specifications of No. μ, No. 3, No. 7, and No. 4J9. 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 droplet 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 the water bathing polymer compound include water-soluble anionic polymer compounds, nonionic polymer compounds, and amphoteric polymer compounds.

These water-soluble polymer compounds are contained in an amount of 0.07 to 70% by weight.
It is used as an aqueous solution.

A substance for further improving the thermal recording density can be added to the binder solution when forming the thermal recording layer. Specifically, the melting point! 0-/! The temperature range is 0'C(7), preferably 900C, /30'C, and the temperature is selected from compounds having good compatibility with diazo compounds, coupling components, or basic substances. Examples include fatty acid amides, ketone compounds, ether compounds, urea compounds, and esters. These compounds are usually l~i
.

It is dispersed into micrometer particles and used at a solid content of 2 to 7 g/m2.

In addition, pigments such as kaolin, talc, silica, barium sulfate, titanium dioxide, aluminum hydroxide, zinc oxide, and calcium carbonate are used to prevent sticking to hot heads and to improve writing properties.・Melamine M fat S.

Fine powder can be added. Similarly, metal soaps can also be used to prevent sticking. The amount of these additives added is usually o, 2 to 7 g/m2
is within the range of

In addition to the above additives, stabilizers such as citric acid, tartaric acid, oxalic acid, boric acid, and phosphorus may also be added.

The recording layer is usually provided with a solid content in the range of J-Jg/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 pHJ-9 neutral paper sized with a neutral sizing agent such as an alkyl ketene dimer (described in Japanese Patent Application Laid-open No. Shoj!-/4LJ!II) has good shelf life. This is preferable in this respect. Other examples include JP-A-7
-/IAAJ'7 Publication, JP-A-Sho! I-/3tμ Octopus Publication, JP-A-Sho! Publication number l-4909/, Japanese Patent Application Publication No. Shoj♂-A
jA9j publication and JP-A-Sho! Tar32r9r! It is possible to use the paper described in the above publication.

Synthesis examples, examples, and comparative examples of the present invention are described below. However, each of these aspects does not limit the invention. In each of the following, "parts" means "parts by weight" unless otherwise specified.

(Synthesis example) 4'-(p-toluylthio)-co,! 51 parts of -diphthoxybenzenediazonium hexafluorophosphate (i)-2,t-dibutoxy-Hiro-chloronitrobencef was added to 170 parts of methanol and warmed to 0.0C. This is followed by p-thiocresolco/.

j part sodium methylate, r part methanol (j
Part) The solution was added dropwise over about 7 hours to react. After the dropwise addition was completed, the reaction was continued under reflux for 1 hour. After the reaction is complete, add water to the reaction solution! 1 part was added to precipitate crystals, which were collected in r. Recrystallized from methanol and obtained jt.

Part j of 44-)lylthio,j-dibutoxynitrobenzene was obtained (melting point a≠~+t'C).

(ii) 4'-tolylthioko,! - 1.1 parts of dibutoxynitrobenzene, 1 part of reduced iron, and 1 part of ammonium chloride! , μ-bu, Mizuko! 1 part of isopropanol was gradually added to the mixture of 1 part of isopropanol under reflux conditions for reduction. Perform post-processing according to conventional methods! -) 53 parts of IJ Lucioco, j-dibutoxy-aniline were obtained.

(iii) 4 is monotolylthioko, j-dibutoxyaniline! 3 parts of methanol (too much) containing 100 parts of concentrated hydrochloric acid.
), and the whole was cooled to -100C.

A solution of 3 parts of sodium nitrite and 17 parts of water was added dropwise to this, being careful not to allow the internal temperature to exceed o'C.
Diazotized.

Then KPF6 zθ portion was added. Furthermore, the internal temperature of the reaction solution is 2! After raising to ~300C''!, 70 parts of water were added.

After adding water, the mixture was cooled with ice water to extract ten crystals and collect P.

Recrystallization from an ethyl acetate-methanol mixture gave the tr portion of l-tolylthioko, j-dibutoxybenzenediazonium hexafluorophosphate (melting point tia-
iit'c).

(Example) Example 1 (i) Hiro-) Lil Chioco! - Mix 3 parts of dibutoxybenzenediazonium hexafluorophosphate, 1 part of tricresyl phosphate, 5 parts of ethyl acetate, 10 parts of trimethylolpropane trimethacrylate, and 1 part of Takenate D-110N (manufactured by Takeda Pharmaceutical Company Ltd.) , dissolve the core substance solution! ! It was torn apart.

This solution was added to a polyvinyl alcohol aqueous solution (lr weight % solution) At part and emulsified and dispersed at 200C to obtain an emulsion having an average particle diameter of 2 μm. This emulsion was reacted at to 0c for 2 hours to obtain a microcapsule liquid.

(ii)) Riphenylguanidine! 6 parts were added to 730 parts of an aqueous polyvinyl alcohol solution (wt% solution) to prepare a basic substance dispersion having an average particle diameter of 3 μm using Dyno Mill (manufactured by Bouillier Paco 7 En AG).

(iii) 2-hydroxy-3-7toic acid anilide j
Part t is a polyvinyl alcohol aqueous solution (4 is a solution by weight)
/3 is added to the part and Dyno Mill (Bouilia Bacofuen/
(manufactured by AG) to prepare a coupling component dispersion having an average particle size of 3 μm.

(1■) 70 parts of microcapsule liquid, basic substance dispersion! 7 parts of the coupling component dispersion liquid and 71 parts of the calcium carbonate dispersion liquid (≠O weight % liquid) were mixed to prepare a coating liquid.

(V) Apply this coating liquid to a smooth surface of high quality 11 (30 parts/m2).
) and dried at a temperature of ao 0c for 30 minutes to prepare a heat-sensitive recording sheet having a heat-sensitive recording layer having a dry weight of io part m2.

Comparative Example 1 As a diazo compound,! A thermosensitive recording sheet was produced in the same manner as in Example except that -dibutyloxyl-morpholino-benzenediazonium hexafluorophosphate was used.

Comparative Example Coethoxy a-Cμ′-(co(x,<<-di-t-amylphenoxy)butyroyl) as a codiazo compound
A heat-sensitive recording sheet was produced in the same manner as in Example except that benzenediazonium hexafluorophosphate was used.

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

Next, a comparative test was conducted on the storage stability of the obtained heat-sensitive recording sheets.

A comparison test of raw storage stability was carried out using heat-sensitive recording sheets stored at room temperature,
A comparison was made based on the difference in color density between thermal recording sheets that were forcibly stored at 1.0'C and JO%RH for 72 hours using a hot plate. 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, Table 7, and Table 2, the heat-sensitive recording material obtained using the diazo compound according to the present invention has excellent storage stability and can be easily stored using the widely used 4A 20 nm light source. It is clear that it can be established.

Patent applicant: Fuji Photo Film Co., Ltd.Fixing speed was also compared using Copiart 1OO (manufactured by Fuji Film ■). (The time taken until the color stopped developing by reheating was measured) The results are shown in Table 2.

Claims (2)

[Claims] (1) In a diazo thermosensitive recording material having a thermosensitive recording layer containing a diazo compound, a coupling component, a base, and a binder on a support, the diazo compound is expressed by the following general formula (
A diazo thermosensitive recording material comprising at least one of the compounds represented by I). General formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ In the general formula (I), R_1, R_2, and R_3 represent an alkyl group, an aralkyl group, an aryl group, a substituted alkyl group, a substituted aralkyl group, and a substituted aryl group. . R_1
, R_2, and R_3 may be the same or different. (2) The diazo thermosensitive recording material according to claim 1, wherein the compound represented by general formula (I) is encapsulated in microcapsules.