JPS615983A - Thermal recording material - Google Patents

Abstract

PURPOSE:To provide a thermal recording material having excellent preservability and a high developed color density and capable of being photo-fixed, wherein a recording layer comprising a coupling agent and a diazo compound which has a specified solubility in water and is contained in microcapsules formed of a synthetic resin is provided on a base. CONSTITUTION:A coating liquid comprising a diazo compound (e.g., a compound of the formula) having a solubility in water at 25 deg.C of not higher than 0.3g and contained in the synthetic resin microcapsules, a coupling agent (e.g., resorcinol) or the like is applied to the base (e.g., a paper) and is dried by a usual method to provide a thermal recording layer, thereby obtaining the desired thermal recording material. USE:Printer papers for facsimiles or computers, thermal development type copying papers or the like.

Description

Detailed Description of the Invention "Industrial Field of Application J The present invention relates to a heat-sensitive recording material, and in particular to a fixable diazo-based heat-sensitive recording material. The present invention relates to a heat-sensitive recording material that has excellent color density during heat recording, and is capable of light fixing after heat 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, heating, or adhesion of solvents after recording, 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-Shoj7-/, 2
3orb issue, Journal of the Institute of Image Electronics Engineers, ti, x90 (191'
2), the recording material used for the diazo compound, the coupling component, and the basic component (including substances that become basic when heated) is thermally recorded, and then irradiated with light to detect any unreacted components. The diazo compound of '*Light decomposition produces color? It is something that makes it stop.

Indeed, according to this method, it is possible to stop (hereinafter referred to as fixing) the color development in areas that do not require recording. However, this recording material also undergoes gradual pre-coupling during storage, and undesirable coloring (fogging) may occur. For this purpose, it is a method to prevent contact between the components and prevent pre-coupling by making any seven of the coloring components exist in the form of discontinuous particles (solid dispersion). It has the disadvantage that its storage stability (hereinafter referred to as raw storage stability) is not yet sufficient and that its thermochromic properties are reduced. As another measure, it is known to separate the asiazo compound from the coupling component in a separate layer in order to minimize contact between the components (for example, the above-mentioned Japanese Patent Application Laid-Open No. 7-7-230).
(described in issue 16).

Although this method improves raw storage stability, it suffers from a large drop in thermal color development and cannot respond to high-speed writing with a short pulse width, making it impractical. Furthermore, as a method to satisfy both raw storage stability and thermochromic properties, either the coupling component or the base substance may be replaced with a non-polar wax substance (% Ml@j 7-4'
4'/#74t, same j 7-/4A! AJj
It is known that K and other components can be separated by encapsulation with a hydrophobic polymer substance (Tokusho 57-Nota, No. 294). However, these encapsulation methods
Dissolving wax or polymeric substances in those solvents,
A capsule is formed by dissolving or dispersing a coloring component in the solution, which is different from the concept of an energized capsule in which a core material is surrounded by a shell. Therefore, when a coloring component is formed by dissolving, one coloring component does not become the core material of the capsule and mixes uniformly with the encapsulating material, and pre-coupling gradually progresses at the wall interface of the capsule during storage. Raw storage stability is not 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 that the solvent used to dissolve the wax or polymer substance must be removed after the capsules are formed, and this method is not completely satisfactory.

Therefore, in order to solve these problems, there is a method in which at least 1'15r of the components involved in the color reaction is contained in a core material, and a wall is formed around this core material by polymerization to form a microcapsule. An excellent heat-sensitive recording material was discovered by Sho Jr. and Tso Hiroshi (3).

``Problems to be Solved by the Invention'' However, even in heat-sensitive recording materials produced by this microencapsulation method, unexpected fogging often occurs during storage.

``Object of the Invention'' Accordingly, 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 second 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 Problem" As a result of intensive research, the present inventors have found that in a heat-sensitive recording material in which a recording layer containing a diazo compound and a coupling component is provided on a support, the diazo compound is The problem was solved by a heat-sensitive recording material having a solubility in water of less than 0.3 in Cos'C and being encapsulated in synthetic resin microcapsules.

The microcapsules of the present invention are destroyed by heat or pressure, as used in conventional recording materials, and colored 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 reactive substance present in the core and outside of the microcapsule is heated, thereby mainly permeating through the microcapsule wall and causing the reaction.

It is preferable to encapsulate a diazo compound in the microcapsules of the present invention.

However, since diazo compounds are more or less water-soluble, fogging occurs mainly because the traps are not completely encapsulated during encapsulation, but a portion is distributed into the aqueous phase.

In order to avoid this phenomenon, it is important to set the solubility of the encapsulated diazo compound in water to 0.3f or less.

The diazo compound used in the present invention has the general formula ArN2+
It is a diazonilla salt represented by It is a compound that can develop a color and can be decomposed by secondary light.

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

C4H9 C2HIS C4H9) The coupling component used in the present invention is one that forms a pigment by coupling with a diazo compound (diazonium salt) in a basic atmosphere, and examples of JL forms include resorcinol, phloroglucin, and λ.

Sodium 3-dihydroxynaphthalene-6-sulfonate, l-hydroxy-2-naphthoic acid morpholinopropylamide, /, j-dihydroxynaphthalene, co, 3-
Dihydroxynaphthalene, -13-dihydroxy-6-
Sulfanylnaphthalene, -monohydroxy-3-naphthoic acid morpholinopropylamide, -monohydroxy-3-
co-7toic acid anilide, λ-hydroxy-3-naphthoic acid-co'-methylanilide, co-hydroxy-3-naphthoic acid ethanolamide, non-hydroxy-3-naphthoic acid octylamide, co-hydroxy-3-naphthoic acid-
N-dodecyl-oxy-propylamide, euhydroxy-3-naphthoic acid tetradecylamide, acetanilide, acetoacetanilide, benzoylacetanilide, nophenyl-3-methyl-!-pyrazolone, / -
(2',41',1.1-tvp-orophenyl)-3-
Examples include benzamide-j-pyrazolone. Furthermore, by using two or more of these coupling components in combination, an image of any color tone can be obtained.

As the basic substance of the present invention, a poorly water-soluble or water-insoluble basic substance or a substance that generates an 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, lysines, guanidines, indoles, imidazoles, and imidacillins. , triazoles, morpholines, lysines, amidines, formazines, pyridines, and other nitrogen-containing compounds. Specific examples of these are:
For example, ammonium acetate, tricyclohexylamine,
Tribenzylamine, octadecylbenzylamine, stearylamine, allyl urea, thiourea, methylthiourea, allylthiourea, ethylenethiourea, λ-benzylimidazole, p-phenylimidazole, cone uni-4-meth-phenylimidazole, λ-undecyl imidazole Sirin, -1μ,! , -trifuryl-1-imidazoline, l, λ-diphenyl-1.4t-dimethyl-, z-
imidacilline, λ-phenyleucoimidazoline, /.

J, J-4 rifhenylguanidine, 1. -monoditolylguanidine, /,2-dicyclohexylguanidine, 1.
λ13-Tricyclohexylguanidine, guanidine trichloroacetate, N,N'-dibenzylpiperazine, μ
, dithiomorpholine, morpholinium trichloroacetate, co-aminobenzothiazole, and λ-penzoylhydrazinopenzothiazole. These basic substances can also be used in combination of one or more types.

In the present invention, the diazo compound contained in the core material of the microcapsule is dissolved in a water-insoluble organic solvent, and after emulsification, the diazo compound is formed around the microcapsule wall by polymerization. The boiling point is preferably . Specifically, phosphoric acid esters, phthalic acid esters, other carboxylic acid esters, fatty acid amides, alkylated biphenyls, alkylated terphenyls, chlorinated paraffins, alkylated naphthalenes, diarylethanes, and the like are used. Specific examples include tricresyl phosphate, trioctyl phosphate, octyldiphenyl phosphate,
Tricyclohexyl phosphate, dibutyl phthalate, dioctyl phthalate, dilauryl phthalate, dicyclohexyl phthalate, butyl oleate, diethylene glycol dibenzoate, dioctyl sebacate, dibutyl 7/ζ sinate, dioctyl adipate, trioctyl trimellitate, citric acid Acetyl triethyl acid, octyl maleate, dibutyl maleate, isopropylbiphenyl,
Isoamyl biphenyl, chlorinated/e-roughin, diisopropylna-7talene, l, l/-ditolylethane, λ, 4
Examples include L-di-tert-aminophenol, N,N-dibutyl-subtoxy-j-ter-7-yarioctylaniline, 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 a diazo compound and then forming a wall of a polymeric material around the oil droplets. The polymeric substance-forming actant 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. can be mentioned.

More than one type of polymeric substance F'i 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 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, within a short period of time, a capsule ligature which is preferable as a recording material having a uniform particle size and excellent shelf life.

This method and specific examples of compounds are described in US Patent No. 3
．． It is described in the specifications of No. 72A, No. 1044, Nos. 3, 7, and 4t.

For example, when polyurethane is used as a capsule wall material, a polyvalent isocyanate and a first substance (e.g., polyol) that reacts with it to form a capsule wall are mixed into an oily liquid to be encapsulated, emulsified and dispersed in water, and then subjected to temperature control. By rising, a polymer reaction occurs at the oil droplet interface,
Microcapsule wall crabs form. At this time, an auxiliary solvent with a low boiling point and strong dissolving power can be used in the oily liquid.

In this case, regarding the polyincyanate to be used and the polyol and polyamine to be reacted with it, U.S. Pat.
jJ4. R issue, Tokuko Sho<a t-e031A7 issue, same day? --No. 1152, JP-A-Shosan 1-tro Tsuta No. 1, same a
It is disclosed in t-r4coza No. 6, and can also be used there.

In addition, a molecule such as soot salt may be used in combination to accelerate the urethanization reaction.

The diazo compound, which is the main component used in the present invention, the coupling component, and the diazo compound among the basic substances are used as the core material of the microcapsule, but other types may be included in the core material of the microcapsule. , may be outside the microcapsule.

When a diazo compound and one other species are contained in microcapsules, they may be in the same microcapsule or in separate microcapsules.

When containing the other Q2 types in seven microcapsules, it is not possible to contain all three types in the same microcapsule at the same time, but there are various combinations.

Other parts not contained in the core material of the microcapsule are
Used for the heat-sensitive layer outside the microcapsule.

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, and examples thereof include those having a -COO-1-803- group. Specific anionic natural polymers include gum arabic and alginic acid, while semi-synthetic products include carboxymethyl cellulose, heptalated gelatin, sulfated starch, sulfated cell o-, x,
, I) Cuninsulfonic acid and the like are al.

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, Examples include carboxy-modified polyvinyl alcohol. Examples of nonionic polymers include polyvinyl alcohol, hydroxyethyl cellulose, and methyl cellulose.

Examples of amphoteric compounds include gelatin.

Cofl-lano water-soluble polymer 1rl O, 0/-/O
It is used as an aqueous solution of w t eII. The particle size of the microcapsules is adjusted to less than 0μ. Generally, if the particle size exceeds λθμ, both print quality tends to be poor.

In particular, when heating with a thermal head is performed from the wing cloth layer side, the thickness is preferably 1μ or less to avoid pressure fog.

When making microcapsules, the diazo compound tO0λw
It can be made from an emulsion containing t% or more.

The coupling component and basic substance used in the present invention are Q
, /, 10 parts by weight, and the coloring aid is preferably used in a ratio of O0/-20 parts by weight. Also, diazo compounds are 0
．． j-j, it is preferable to apply 097 m2.

The coupling component and the basic substance used in the present invention are preferably used after being dispersed in solid form with a water-soluble polymer using a sand mill or the like. Preferred water-soluble polymers include water-soluble polymers used when making microcapsules. Can be mentioned. At this time, the concentration of each water-soluble -3 polymer is set to 96, and the coupling component is made basic to this aqueous polymer solution.

The dispersed particle size is preferably less than lOμ.

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

Similarly, metal soap or the like can also be used to prevent sticking. These usage amounts are Bo,
The area is between 2 and 797m2.

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

Heat-melting substances include substances that are solid at room temperature and have a melting point of 0C, diazo compounds, coupling components, and basic substances that melt when heated with a boolean head. Specific examples of heat-fusible substances that are dispersed into particles of O17-10μ and used in an amount of solid content O6λ-727m2 include fatty acid amides, N-substituted fatty acid amides, ketone compounds, urea compounds, Examples include esters.

The heat-sensitive recording material of the present invention can be coated with a suitable binder.

Binders include polyvinyl alcohol, methylcellulose, carboxymethylcellulose, hydroxypropylcellulose, gum arabic, gelatin, polyvinylpyrrolidone, casein, styrene-butadiene latex, acrylonitrile-butadiene latex, polyvinyl acetate, polyacrylic acid ester, ethylene-vinyl acetate, etc. Various emulsions of polymers can be used. The amount used is solid content 0. ! ~jff/m2.

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 liquid containing a diazo compound, a coupling component, a basic substance as a main component, and other additives, and coating it on a support such as paper or a synthetic resin film with a blade. Apply by coating methods such as coating, air knife coating, gravure coating, roll coating, spray coating, dip coating, etc. After drying, the solid content λ, j-2
A heat sensitive layer of jf/m2 is provided.

The heat-sensitive recording material of the present invention can be used as printer paper for facsimile machines and electronic computers that require high-speed recording, and can be fixed by exposing it to light after printing by heating to decompose unreacted diazo compounds. . 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. What is the amount added? The "parts" shown represent "parts by weight."

Example 1 20 parts of the following diazo compound Hirobe and the (j:/) adduct of xylylene diisocyanate and trimethylolpropane ligated with dibutyl phthalate are added to a mixed solvent of 1 part of antaerythritol tetraacrylate and 1 part of dichloromethane. Dissolved.

The solution of this diazo compound was mixed with polyvinyl alcohol 3.2
The mixture was mixed with an aqueous solution in which part was dissolved in part sr, and emulsified and dispersed at λO0C.

Add 100 parts of water to the resulting emulsion and stir! 0°
After 2 hours of heating CK, capsule liquid encapsulated in the diazo compound and having an average particle size of 3 μm was obtained.

(Diazo compound) Solubility in water (2t 0C) o, oxsV order K, λ-hydroxy-3-naphthoic acid anilide (17 parts 5 (j%
The mixture was added to 100 parts of a polyvinyl alcohol water FFJ solution and dispersed in a sand mill for about 2≠ hours to obtain a dispersion of the coupling component with an average particle size of 3 μm.

Next, 20 parts of triphenylguanidine was added to 100 parts of a 2s% polyvinyl alcohol aqueous solution, and the mixture was dispersed in a sand mill for about λ time to obtain a dispersion of triphenylguanidine having an average particle size of 3 μm.

Capsule liquid of diazo compound obtained as above 5
To 0 parts, 30 parts of a dispersion of a coupling component and a dispersion of triphenylguanidine/jilk were added to prepare a coating liquid. This coating solution was coated on a smooth high-quality paper (jOr/m2) using a coach-in-blond grape to give lλf/y12 with heavy drying, and was dried at sO''c for 30 minutes to obtain a heat-sensitive recording material.

(Test method) Obtained heat-sensitive recording material KGm mode (Hifax 7
00 ; Hitachi Ltd. All)r was used for thermal recording, and then the entire surface was exposed to light using Ricoh Suno ζ-Dry 100 (manufactured by Ricoh ■) and fixed. The blue density of the obtained recorded image was measured using a Macbeth reflection densitometer. The results are shown in Table 1. On the other hand, when thermal recording was performed again on the fixed portions, it was confirmed that no images were recorded on any of them and that they were fixed.

Next, in order to improve the shelf life of the heat-sensitive recording material, the skin density (
Fog) and heat-sensitive recording material at UO℃ and relative humidity 20℃.
%Rf (), stored in a dark place for λμ time, and after performing a forced deterioration test, measured with a Kabrio Macbeth reflectance meter and observed changes in fog.

The results are shown in Table 7.

Example A heat-sensitive recording material was prepared in the same manner as in Example 1, except that 7 parts of the following diazo compound was used in place of 4c parts of the diazo compound in Example 1.

(Diazo Compound) Example 3 A heat-sensitive recording material was prepared in the same manner as in Example 1, except that 3.6 parts of the following diazo compound was used in place of the diazo compound of Example 1.

(Diazo compound) Solubility in water (2j 'C) Q, 01lfl Example G The procedure was the same as in Example 1 except that the following diazo compound J and part j were used in place of the diazo compound Hirobe of Example 1. A heat-sensitive recording material was prepared.

(Diazo compound) OBu Solubility in water (Jj'C) Comparative example / P3''Same as Example 1 except that the following diazo compound μ part was used instead of the diazo compound μ part in Example 1. A heat-sensitive recording material was thus obtained.

(Diazo Compound) Table 1 "Effects of the Invention" It is clear from Table 7 that Comparative Example 1 has a high skin concentration before and after deterioration, but Example 7~μ is low. It seems that the limit is acceptable.

Procedural amendment (side), indication of the case Showa J year patent application No. 4A9
/ No. 2, Title of the invention Thermal recording material 3, Relationship with the case of the person making the amendment Patent applicant 4, Date of the amendment order 1978 Month 1 5, Subject of the amendment Description 6゜Details of the contents of the amendment I will submit an engraving (with no changes to the contents).

Procedural amendment 1, Indication of the case 1925 patent application No. Tataguta/No. 2, Title of the invention Heat-sensitive recording material 3, Relationship with the case of the person making the amendment Patent applicant address 210 Nakanuma, Minamiashigara City, Kanagawa Prefecture Name (520) To Fuji Photo Film Co., Ltd. method α Part t Target of amendment The description in column 5 of "Detailed explanation of the invention" of the specification and the section of "Detailed explanation of the invention" of the statement of contents of amendment is as follows. Correct the standard.

After "Solved." on page 0, line 77: 1. The heat-sensitive recording material of the present invention can stop the color development of the diazo compound by photodegrading the unreacted diazo compound after it is thermally colored.

It is also possible to first imagewise expose and then uniformly heat the unexposed portions to thermally color them. ” Insert all.

Claims (1)

[Claims] In a heat-sensitive recording material in which a recording layer containing a diazo compound and a coupling component is provided on a support, the diazo compound has a solubility in water of 0.3 g or less at 25°C, and is further contained in synthetic resin microcapsules. A heat-sensitive recording material characterized by being encapsulated in.