JPS615984A - Thermal recording material - Google Patents

Abstract

PURPOSE:To provide a thermal recording material having excellent preservability before thermal recording and a high developed color density and capable of being photo-fixed after thermal recording, wherein a diazo compound is contained in microcapsules, and a coupler having a molecular weight not higher than a specified value is used. CONSTITUTION:A recording layer comprising a diazo compound (e.g., a compound of the formula) contained in microcapsules, a coupler having a molecular weight of not higher than 500, e.g., 2-hydroxy-3-naphthoic anilide, and a basic substance, e.g., 1,2,3-triphenylguanidine, is provided on a base to obtain the objective thermal recording material.

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Application Field" The present invention relates to a heat-sensitive recording material, and particularly to a fixable diazo heat-sensitive recording material. More specifically, the present invention relates to a heat-sensitive recording material that has excellent storage stability before being thermally recorded, has a high color density during thermal recording, and is capable of light fixing after thermal recording.

"Prior Art" A leuco coloring type heat-sensitive recording material is usually used as a recording material used in a heat-sensitive recording method. However, this heat-sensitive recording material has the disadvantage that color develops in unexpected places due to harsh handling or heating after recording or adhesion of solvent, staining the recorded image. In recent years, research has been actively conducted on diazo color-forming heat-sensitive recording materials as heat-sensitive recording materials that do not have these drawbacks. For example, JP-A-17-2
iort issue, m image electronics society journal, u-, JP'('
As disclosed in Riza2), etc., thermal recording is performed on a recording material using a diazo compound, a coupling component, and a basic component (including substances that become basic when heated), and then light irradiation is performed. This is a book that decomposes unreacted diazo compounds to stop color development.

Indeed, according to this method, it is possible to stop color development (hereinafter referred to as fixing) in areas that do not require recording.

However, in this recording material, pre-coupling gradually progresses during storage, and an undesirable single color (haze) may occur. To this end, it has been attempted to prevent contact between the components and prevent pre-coupling by making one of the coloring components exist in the form of discontinuous particles (solid dispersion). storage stability (hereinafter referred to as raw storage stability)
However, it still has the disadvantage that it is not sufficient and the thermal coloring property is reduced. Ru. As another measure, it is known to separate the diazo compound and the coupling component as separate layers in order to minimize contact between the components (for example, the above-mentioned Japanese Patent Application Publication No. Sho, t.
7-123016). Although this method improves raw storage stability, the thermal coloring properties are greatly reduced, and it cannot respond to high-speed recording with short pulse widths, making it impractical. Furthermore, as a method to satisfy both raw storage stability and thermal color development, either the coupling component or the basic substance is mixed with a non-polar waxy substance (JP-A Showa Tough-Ko 4'/Ko 1, JP-A Show Tough-Ko 4'/Ko 1, JP-A Show Tough -7≠263) and hydrophobic polymer substances (JP-A-57
It is known that encapsulation with K-/Takotabiri-go (Takota biri-go) is used to isolate it from other components.

However, these encapsulation methods involve dissolving wax or polymeric substances in their solvents, and dissolving or dispersing coloring components in these solutions to form capsules. This is different from the concept of a normal capsule covered with a shell.

When the coloring component is dissolved and formed for coloring, the coloring component does not become the core material of the capsule, but mixes uniformly with the encapsulating material, and pre-coupling gradually progresses on the outer surface of the capsule wall during storage. The raw storage stability is fully satisfied. In addition, when a color-forming component is dispersed and formed, the color-forming reaction does not occur unless the capsule wall is thermally melted, resulting in a decrease in thermal color-forming properties. Furthermore, there is a manufacturing problem in which the wax or the solvent used to dissolve the polymeric substance must be removed after the capsules are formed, which is not completely satisfactory.

Therefore, in order to solve these problems, a diazo compound is contained in the core material, and a wall is formed around the core material by polymerization to form a microencapsulation method.
IO'13 Specification), an excellent heat-sensitive recording material was discovered.

``Problems to be Solved by the Invention'' However, even in heat-sensitive recording materials produced by this microencapsulation method, the developed color density is sometimes insufficient.

``Object of the Invention'' Therefore, the first object of the present invention is to provide a heat-sensitive recording material that has excellent shelf life and high thermochromic properties.

A first object of the present invention is to provide a heat-sensitive recording material that can be fixed by photodecomposing unreacted diazo compounds after heat recording.

A third object of the present invention is to provide a heat-sensitive recording material with excellent manufacturing suitability.

"Means for Solving the Problems" As a result of intensive research, the present inventors have developed a method for using a diazo compound in a heat-sensitive recording material in which a recording layer containing a diazo compound, a coupler, and a basic substance is provided on a support. The problem was solved by a heat-sensitive recording material which is encapsulated in microcapsules and further has a molecular weight of the coupler of 500 or less.

The microcapsules of the present invention are destroyed by heat or pressure, as used in conventional recording materials, and color is developed by bringing the reactive substance contained in the core of the microcapsule into contact with the reactive substance outside the microcapsule. Rather than causing a reaction, the diazo compound in the core of the microcapsule and a reactive substance such as a coupler present outside are heated to mainly penetrate through the microcapsule wall and react. According to microscopic observation, the color reaction occurs mainly within the capsule.

Therefore, the permeation process is a process in which components such as coupler and alkali outside the capsule are eutectic and diffuse to the capsule wall.
It can be understood to include two diffusion processes: and the process of permeating the capsule wall while being affected by the dissolving action of the core oil. Correspondingly, couplers with large molecular weights are difficult to diffuse, so it is inevitable that the color density will be low. Therefore, in order to obtain a sufficiently high color density, there is necessarily a suitable range for the molecular weight of the coupler.

The coupler used in the present invention has the following chemically reactive surfaces:
It forms a dye by coupling with a diazo compound in a basic atmosphere, and the erodible surface referred to in the present invention includes:
It has a molecular weight of 500 or less.

Concrete 11MJ,! : resorcin, phloroglucin, x, J-,) sodium hydroxynaphthalene-6-sulfonate, /-hydroxy-λ-naphthoic acid morpholinopropylamide, /, terdihydroxynaphthalene, 3-dihydroxynaphthalene, λ, 3 -dihydroxy-t-sulfanylnaphthalene, λ-hydroxy-3-naphthoic acid morpholinopropylamide, λ-hydroxy-3-naphthoic acid anilide, λ-hydroxy-3-naphthoic acid-λ'-methylanilide, λ-hydroxy-3-naphthoic acid ethanol Amide, -monohydroxy-3-naphthoic acid octylamide, λ-hydroxy-3
-Naphthoic acid-N-dodecyl-oxy-propylamide, λ-hydroxy-3-naphthoic acid tetradecylamide, acetanilide, acetoacetanilide, benzoylacetanilide, /-phenyl-3-methyl-terpyrazolone, / (-274t / , 6 / -trichlorophenyl)-3-benzamide-yo-pyrazolone, /-(2', Hiro', 6'-) l) chlorophenyl)-3-72IJ / -j-pyrazolone, l-phenyl-3-phenyl Examples include acetamido-terpyrazolone. Furthermore, by using two or more of these coupling components in combination, it is possible to obtain an image of any color tone.

The diazo compound used in the present invention has the general formula ArN2+
X (wherein Ar represents an aromatic moiety), N2+ represents a diazonium group, and X- represents an acid anion. )
It is a diazonium salt represented by the formula, and is a compound that can develop a color by causing a coupling reaction with a coupling component, and can be decomposed by light.

Specific examples of the diazo compound (diazonium salt) include the following examples.

0C4H0 C4H9 C2H5 t-t-13)s C2H5 C2H5 C4H9 C4H9 oc, t-t,.

0C4H9 As the basic substance of the present invention, a poorly water-soluble or water-insoluble basic substance or a substance that generates el-alkali when heated is used.

Basic substances include inorganic and organic ammonium salts, organic amines, amides, urea and thiourea and their derivatives, thiazoles, pyrroles, pyrimidines, piperazines, guanidines, indoles, imidazoles, imidacillins, and triazoles. Examples include nitrogen-containing compounds such as morpholines, pyridines, amidines, formazines, and pyridines. Specific examples of these are:
For example, ammonium acetate, tricyclohexylamine,
Tribenzylamine, octadecylbenzylamine, stearylamine, allyl urea, thiourea, methylthiourea, allylthiourea, ethylenethiourea, λ-benzylimidazole, Hiro-phenylimidazole, +2-phenyl-≠-methyl-imidazole, Coundesyl imidazoline, co, μ, j-trifuryl λ-imidacilline, /.

λ-diphenyl≠, ≠-dimethyl-coimidazoline, nophenyl-2=imidacilline, /.

λ, 3-triphenylguanidine, /, 2-ditolylguanidine, /, 2-dicyclohexylguanidine, /,
2.3-) IJ cyclohexylguanidine, guanidine trichloroacetate, N,N'-dibenzylpiperazine,
p,p'-dithiomorpholine, morpholinium trichloroacetate, 2-amino-benzothiazole, and λ-penzoylhydrazinopenzothiazole can be used in combination with these basic substances Fi, 2ml.

1fi, the diazo compound contained in the core material of the microcapsule is dissolved in a water-insoluble organic solvent and emulsified, and then the microcapsule wall is formed by polymerization in step 9. A boiling point is preferred. Specifically, phosphoric acid esters, phthalic acid esters, other carboxylic acid esters, fatty acid amides, alkylated diphenyls, alkylated terphenyls, chlorinated paraffins, alkylated naphthalenes, diarylethanes, etc. are used. Specific examples include 11 tricresyl phosphate, trioctyl phosphate, octyldiphenyl phosphate, tricyclohexyl phosphate, digtyl phthalate, dioctyl phthalate, dilauryl phthalate, dicyclohexyl phthalate, phthyl oleate, diethylene glycol dibenzoate, Sel. Dioctyl dinitrate, digtyl sepacate, dioctyl adipate, trioctyl trimellitate, acetyltriethyl citrate, octyl maleate, digtyl maleate, isopropylbiphenyl, inamyl biphenyl, chlorinated nomurafin,
Diimpropylnaphthalene, /, /'-ditolylethane, 2. Examples thereof include v-ditertiarymininophenol, NlN-diptyl-λ-gutoquinol, 1-tertiaryoctyltriline, and the like.

Among these, ester solvents such as digtyl phthalate, tricresyl phosphate, diethyl phthalate, and dibutyl maleate are particularly preferred.

The microcapsules of the present invention are produced by emulsifying a core material containing diazo compound gold and then forming a wall of a polymeric material around the oil droplets. The actant forming the polymeric material is added to the interior of the oil droplet and/or to the exterior of the oil droplet. Specific examples of polymeric substances include polyurethane, polyurea, polyamide, polyester, polycarbonate, urea-formaldehyde resin, melamine resin, polystyrene, styrene methacrylate copolymer, styrene-acrylate copolymer, gelatin, polyvinylpyrrolidone, polyvinyl alcohol, etc. There are many.

Two or more types of polymeric substances can also be used in combination.

Preferred polymeric materials are polyurethane, polyurea, polyamide, polyester, polycarbonate, and more preferred are polyurethane and polyurea.

The microcapsule wall 9 of the present invention is particularly effective when using a microencapsulation method by polymerizing a glue actant from inside an oil droplet. That is, it is possible to obtain capsules, which are desirable as a recording material and have a uniform particle size and excellent storage stability, within a short period of time.

For details on this method and specific examples of compounds, please refer to the US Pat.
,721r,! It is described in the specifications of Ou No. 3, No. 7FA, and No. J62.

For example, when polyurethane is used as a capsule wall material, a polyvalent incyanate and a first substance that reacts with it to form a capsule wall (e.g., a polyol) are mixed into an oily liquid to be encapsulated, and then emulsified into water. By increasing the temperature, a polymer formation reaction occurs at the oil droplet interface, forming a microcapsule wall. In this case, a co-solvent with a low boiling point and strong dissolving power can be used in the oily liquid.In this case, the polyisocyanate used and the polyol and polyamine that react with it are described in US Pat. Nos. 3,211,313 and 37,736-5. , 372
No. 3261, special public Shoμg-≠03u7, same py-ra
IR issue, Tokukai Sho VR-Ni OI issue 1, same number 1-1 μo
r6, and they can also be used.

In addition, in order to promote the urethanization reaction, tin or the like can also be used in combination.

When making microcapsules, water-soluble polymers can be used, and the water-soluble polymers may be any of water-soluble anionic polymers, nonionic polymers, and amphoteric polymers.

As the anionic polymer, both natural and synthetic polymers can be used, for example -coo -1-so-
, groups, and the like. Specific anionic natural polymers include gum arabic and alginic acid, while semi-synthetic products include carboxymethyl cellulose and
Examples include pentatal gelatin, sulfated starch, sulfated cellulose, and lignin sulfonic acid.

Synthetic products include maleic anhydride-based (including hydrolyzed) copolymers, acrylic acid-based (including methacrylic acid-based) polymers and copolymers, vinylbenzenesulfonic acid-based polymers and copolymers, There is a carboxy-modified polyhinyl alcohol.

Examples of nonionic polymers include borihinyl alcohol, hydroxyethyl cellulose, and methyl cellulose.

Examples of amphoteric compounds include gelatin.

These water-soluble polymers are o, oi ~ / o w t f
It is used as an aqueous solution of 6. The particle size of the microcapsules is adjusted to 10 μm or less. Generally, if the particle size exceeds 0μ, the print quality tends to be poor.

In particular, when heating with a thermal head is performed from the coated layer side, it is preferable that the thickness be less than gμ in order to avoid pressure fog.

When making microcapsules, use 0.2v of diazo compound.
(It can be made from an emulsion containing t% or more.

The coupling component and basic substance used in the present invention are:
For 1 part by weight of the diazo compound, the coupling component is o,
It is preferable to use i to 10 parts by weight, and the coloring aid to be used in a proportion of 0.17 to 20 parts by weight. Also, diazo compounds are O5
O evening~evening, 0? /m2 coating is preferred.

The coupling component and basic substance used in the present invention are preferably used after being dispersed in a solid state together with a water-soluble polymer using a sand mill or the like. Preferred water-soluble polymers include water-soluble polymers used when making microcapsules. At this time, the concentration of water-soluble polymer is 2 to 30 wt'
4, and the coupling component and basic substance for this water-soluble polymer solution are
It is invested so that it becomes.

The dispersed particle size is preferably 10 microns or less.

The heat-sensitive recording material of the present invention contains silica, barium sulfate, titanium oxide, aluminum hydroxide, zinc oxide,
Pigments such as calcium carbonate, fine powders such as styrene beads, urea-melamine resin, etc. can be used.

Similarly, metal soaps can also be used to prevent sticking. The amount of these used is 0.
2-7p/71.

Furthermore, a heat-melting substance can be used in the heat-sensitive recording material of the present invention in order to increase the heat-recording density.

The thermofusible substance is a substance that is solid at room temperature and has a melting point of 10 to 0°C and melts when heated by a thermal head, and is a substance that dissolves a diazo compound, a coupling component, or a basic substance. The heat-fusible substance is dispersed in the form of particles of o, i to 10 μm and used in an amount of solid content O1,2 to 72/m 2 . Specific examples of heat-melting substances include fatty acid amides, N-substituted fatty acid amides, ketone compounds, urea compounds, esters, and the like.

The heat-sensitive recording material of the present invention can be coated using a suitable ζ inder.

As a binder, polyhinyl alcohol, methylcellulose, carboxymethylcellulose, hydroxypropylcellulose, gum arabic, gelatin, polyvinylpyrrolidone, casein, styrene-butadiene latex, acrylonitrile-butadiene latex, polyvinyl acetate, polyacrylic acid ester, ethylene-acetic acid Emulsions of vinyl copolymers can be used. The amount used is solid content O0! ~! t/m.

In the present invention, in addition to the above materials, citric acid is used as an acid stabilizer.
Tartaric acid, oxalic acid, boric acid, phosphoric acid, birophosphoric acid can be added.

The heat-sensitive recording material of the present invention is produced by preparing a coating solution containing a diazo compound, a coupling component, a main component of a basic substance, and other additives, and coating it on a support such as paper or a synthetic resin film with a bar. The solid content is reduced by application methods such as grade coating, air knife coating, gravure coating, roll coating, spray coating, and dip coating.
A heat-sensitive layer with a temperature of f/m2 is provided. Another method is to make a coating solution by dispersing the camping component, the main component of the basic substance, and other additives in their entirety, or by dissolving them as an aqueous solution and then mixing them to form a coating solution, which is then coated on a support and dried to form a solid state. A precoat layer with a thickness of λ~ioy/m is provided, and a coating solution prepared by adding a diazo compound as a main component as a core material of microcapsules is applied on top of the precoat layer, and the solid content is dried. It is also possible to use a laminated type with a coating layer.

The laminated type heat-sensitive recording material can be laminated in the reverse order, and the coating method can be sequential coating or simultaneous coating of the laminated layers. This laminated heat-sensitive recording material exhibits particularly excellent performance in long-term storage.

The paper used for the support is heat extracted pHJ sized with a neutral sizing agent such as an alkyl ketene dimer.
- Neutral paper (% described in the 1980-7 Kou 21/issue)
It is advantageous in terms of storage stability over time.

In order to prevent the coating liquid from penetrating into the paper and to improve the contact between the recording heat head and the heat-sensitive recording layer, Japanese Patent Application Laid-Open No.
The paper described in No. TTTY and having a Bekk smoothness of 0 seconds or more is advantageous.

Mafc JP-A-11-/31. Paper with an optical surface roughness of gμ or less and a thickness of ≠θ to 7μ as described in U-Taco, a paper with a density of 0°91/an3 or less and an optical Paper with a contact rate of /j% or more, JP-A-5G-6
Canadian Standard Water Level (JIS Pg) listed in No. 7
/2/) t, toocr: Paper made from the pulp that has been beaten in the above manner to prevent penetration of the coating liquid, JP-A-5R-tit! No. 1, the glossy side of base paper made by a Yankee machine is used as the coating surface to improve the color density and dissolution strength, and the base paper is subjected to corona discharge treatment, as described in Japanese Patent Application No. 172, Kota 1983. Papers and the like which have been subjected to coating to improve their coatability can also be used in the present invention and give good results. In addition to these, any support commonly used in the field of heat-sensitive recording paper can be used as the support of the present invention.

The heat-sensitive recording material of the present invention can be used as printer paper for facsimiles and electronic computers that require high-speed recording, and can be fixed by exposing it to light to decompose unreacted diazo compounds after printing with heat. can. In addition, it can also be used as a heat-developable copying paper.

Examples are shown below, but the present invention is not limited thereto. Note that "part" indicating the amount added represents "1 part of military."

(Example 1) The V part of the following diazo compound and the (J:/) adduct/♂ part of xylylene diinocyanate and trimethylolpronone are tricresyl phosphate? 1 part of trimethylolpronocentrimethacrylate and 1 part of dichloromethane were added to 1 part of the mixed solvent and dissolved. This diazo compound solution was mixed with an aqueous solution containing 5.2 parts of polyvinyl alcohol dissolved in water and emulsified and dispersed at 1.200C.

Add 100 parts of water to the resulting emulsion and stir to
After 2 hours, a capsule liquid containing the diazo compound and having an average particle size of 3 μm was obtained.

(diazo compound) OC4H.

Next, 1Q parts of -1hydroxy-3-naphthoic acid anilide was added to 100 parts of an aqueous solution of tiborihinyl alcohol and dispersed in a sand mill for about 2 hours to obtain a dispersion of the coupling component having an average particle size of 3 .mu.m.

Next, 20 parts of triphenylguanidine was added to 100 parts of a 5% polyhinyl alcohol aqueous solution, and the mixture was milled in a sand mill for about -
2Il was dispersed for one hour to obtain a dispersion of triphenylguanidine with an average particle size of 3μ.

Capsule liquid of diazo compound obtained as above 5
A coating liquid was prepared by adding 30 parts of a dispersion of a coupling component and a fraction of hydriphenylguanidine to 0 parts.

This coating solution was bar coated onto smooth high-quality paper (1017 m2) using coach-in-blonde to a dry weight of /29/m2, and dried at RO 0C for 30 minutes to obtain a heat-sensitive recording material.

(Test method) Gm mode (HIFAX) was applied to the obtained heat-sensitive recording material.
700 (manufactured by Hitachi, Ltd.) for thermal recording, and then the entire surface was exposed to light using Licopea Nose Dry 100 (manufactured by Ricoh ■) and fixed. The glue density of the resulting ratio recorded image was measured using a Macbeth reflection densitometer. The results are shown in Table 7.

On the other hand, when thermal recording was performed again on the fixed portions, no image was recorded on any of them, and it was confirmed that they were fixed.

Next, in order to examine the raw storage properties, the skin density (capri) of the heat-sensitive recording material and the heat-sensitive recording material were stored in a dark place for λ≠ hours under the conditions of 0QC1 relative humidity and RH, and a forced deterioration test was performed. After the treatment, Capri was measured using a Macbeth reflection densitometer to see if Capri's hair had changed. The results are shown in Table 1.

Example 2 A heat-sensitive recording material was prepared in the same manner as in Example 1, except that 72 parts of euhydroxy-3-naphthoic acid aniline IJ in Example 1 was replaced with 10 flJ-hydroxy-3-naphthoic acid-α-naphthylamide. The density was measured by blue density.

λ-Hydroxy-3-naphthoic acid anilide 1 of Example 1
A heat-sensitive recording material was prepared in the same manner as in Example 1, except that 10 parts of Q/-hydroxy-λ-naphthoic acid anilide was used. The density was on the gold side with a magenta density.

Example 4 Thermal reaction was carried out in the same manner as in Example 1 except that 7.2 parts of euhydroxy-3-naphthoic acid ani + J de 10 mt/-phenyl-3-p-chlorobenzoylamino-terpyrazolone was used. Recording material was prepared. The concentration is
The magenta density was measured.

Example 5 2-hydroxy-3-naphthoic acid anilide 1 of Example 1
A heat-sensitive recording material was prepared in the same manner as in Example 1, except that 0m was replaced with p-methoxybenzoylaceto-1'-methoxyj'-methoxycarbonyl-anilide/Hirobe. The density was measured by yellow density.

Example 6 2-Hydroxy-3-naphthoic acid anilide 1 of Example 1
A heat-sensitive recording material was obtained in the same manner as in Example 1, except that 0 part was replaced with l-hydroquine-N-[ψ-(29 μm di-tertiary-amylphenoxy)phenyl]--naphthamide/1 part. The cyan density was measured.

Comparative Example 1 Example 1 11 Hydroxy 3-naphthoic acid anilide 1
0 parts to 1 (2/,μ',6'-trichlorophenyl)-3-C3''-(2''',V'''-di-tertiaryamylphenoxyacetamide)-benzamide coater pyrazolone for 2 nights and 5 parts. A heat-sensitive recording material was obtained by pressing in the same manner as in Example 1 except that the material was changed.The magenta density was measured.

Comparative Example 2 2-Hydroxy-3-naphthoic acid anilide 1 of Example 1
01! A heat-sensitive recording material was obtained in the same manner as in Example 1, except that iIt, benzoylacetamino-hiro-methoxy-(2/,≠'-diteramylphenoxy)-acetanilide 2/part i. The density was measured by yellow density.

(Effects of the Invention) As is clear from Table 1, Examples 1 to 6 of the invention a had high image density and were excellent.

Patent Applicant: Fuji Photo Film Co., Ltd. Procedural Amendment July 1930, U-day

Claims (1)

[Claims] A heat-sensitive recording material comprising a recording layer containing a diazo compound, a coupler and a basic substance on a support, characterized in that the diazo compound is encapsulated in microcapsules, and the coupler has a molecular weight of 500 or less. heat-sensitive recording material.