JPS6186285A - Thermal recording material - Google Patents

Abstract

PURPOSE:To enhance preservability of recordability before printing and image stability after printing, by incorporating color forming reaction components, an organic solvent and a releasing agent in microcapsules. CONSTITUTION:A thermal recording layer comprising microcapsules containing a color former and an organic solvent as core material and a color developer is provided on the surface of a base, with a releasing agent contained in the microcapsules. A material impermeable to the color former and the color former and/or the color developer at a recording temperature of a thermal head is used for forming the walls of the microcapsules, thereby preventing the releasing agent from contaminating the head.

Description

Detailed Description of the Invention "Industrial Application Field" The present invention relates to a heat-sensitive recording material, and in particular to a heat-sensitive recording material that has excellent storage performance before printing and stability of recording after printing. Regarding. Furthermore, the present invention relates to a heat-sensitive recording material that has excellent heat coloring properties.

"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 suffers from undesirable decoloring and coloring when subjected to harsh handling after recording or when it comes into contact with adhesive tape or diazo copying paper.

In recent years, research on diazo color-forming heat-sensitive recording materials has been actively conducted as a heat-sensitive recording material that does not have these drawbacks.
Diazo compounds are inherently unstable, and the background often becomes colored with various masterpieces.

JP-A No. 31r discloses a microcapsule containing a photopolymerizable vinyl compound, a photopolymerization initiator, and one component that causes a color-forming reaction, and another component that reacts with the component to form a color. A light- and heat-sensitive recording material has been invented which has the following on the same side of the support.

When this recording material is heated, the coloring component (hereinafter referred to as coloring agent) contained in the core of the microcapsule passes through the capsule wall and comes out, or other components that cause a coloring reaction outside the capsule ( (hereinafter referred to as color developer) passes through the capsule wall and enters the capsule. As a result, color develops in both cases. Therefore, the heated area can be colored by heating, and then the entire surface is exposed to light for 1 time to polymerize the vinyl compound contained in the core, preventing the coloring component from passing through and preventing coloring in the non-colored area. (Also referred to as "fixing j").Also, another method is to use a diazo compound, a coupling component and an alkali as disclosed in JP-A No. 77-/23 ort, JP-A No. 17-121092, etc. A known method is to use a light and heat sensitive recording material made of a generator or a coloring aid to perform thermal recording and then perform black irradiation to completely decompose unreacted diazo compounds and stop color development.However, this recording material cannot be stored. Pre-coupling gradually progresses during the process, resulting in undesirable coloration (
Since this may occur, the patent application for
No. 0113 discloses an invention in which at least one of a diazo compound, a coupling fraction, and a coloring aid is contained in the core of a microcapsule.

The photo-fixable heat-sensitive recording material using microcapsule gold has a simple recording device, and the recording material has good storage stability.
The stability of the image and background area after recording is excellent. However, in such a thermal recording sheet that utilizes the transparency of the microcapsule wall during heating, problems such as sticking do not occur when infrared isotone is used for thermal recording, but when heating recording is performed with a thermal head etc. , sticking may occur and the head may become dirty. If the head becomes dirty, printing will not be clear and only recorded images of poor quality will be obtained.

As a result of a detailed study on the development of head stains, the present inventors found that the walls of microcapsules are involved in head stains, and by selecting a material that does not easily soften when heated for the microcapsule walls, the head stains themselves can be reduced. I found that it can be improved.

However, if the microcapsule walls are made of a material that does not easily soften when heated, the chromophore content decreases.

"Problems to be Solved by the Invention" The first object of the present invention is to provide a heat-sensitive recording material that is excellent in storage performance of recording performance before printing and stability of recording after printing.

A second object of the present invention is to provide a thermosensitive recording material with excellent thermochromic properties. A third object of the present invention is to provide a one-box thermal recording material that does not cause head stains.

[Means for Solving All Problems] As a result of intensive research, the present inventors have developed a thermosensitive recorder containing a color former, an organic solvent, microcapsules contained in a metal core, and a color developer. The walls of the microcapsules are impermeable to both the color former and the color developer at room temperature, but at the temperature of the thermal head during recording, the walls of the microcapsules are impermeable to both the color former and the color developer. Alternatively, in a heat-sensitive recording material that is transparent to at least one side of the color developer and thereby provides a colored image 1, the above-mentioned objective can be achieved by incorporating a release agent into the microcapsules. Achieved invention. The effect is particularly great when the microcapsules have a glass transition point (TG) of the microcapsule wall of to0c or more and 2000C or less.

That is, the combination of a microcapsule wall with a glass transition point of AO'C, 200° and a mold release agent provides a heat-sensitive recording material that has a higher color development speed and color density and does not cause head stains.

In order to instantly make the microcapsule wall transparent by heating, it is preferable that the glass transition point is 2oo0c or less. However, if the glass transition point is too low, fogging will occur.

Therefore, in terms of color development and fogging, the glass transition@degree is to
It is preferable to set it to 'c-, 2oo'c.

The thermal head is instantaneously heated to a temperature above 0°C, and the microcapsules are once heated by heat transfer from the thermal head, but then the temperature is lowered by heat transfer to the support. As described above, when the microcapsule wall is heated above the glass transition point and then cooled, sticking to the thermal head occurs, which is the main cause of head contamination. This phenomenon is especially true for the above-mentioned to 0cm 000C
It is noticeable in the microcapsule wall, which has a glass transition temperature of . This is because microcapsule walls with a glass transition point exceeding 2000 Ct are difficult to form adhesion due to heating, while microcapsule walls with a glass transition point below 0c tend to adhesion due to heating. However, since it does not become brittle when cooled,
This is thought to be because it is difficult to be caught by the head.

Therefore, the effect of the present invention is most effective in a system using microcapsules having a glass transition point of 60''C-2oo°C.

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. It does not cause a reaction, but rather permeates through the microcapsule wall and causes a reaction by heating the reactive substance present in the core and outside of the microcapsule.

It has been found that by dissolving the coloring component in a broadly defined organic solvent, both thermal coloring properties and storage stability are advantageous. However, in order to obtain even more sufficient thermochromic properties, the glass transition R point of the microcapsule wall must be adjusted to
c.

More preferably, the range is 7o'C-tso'C. The capsule wall changes from a glass state to a rubber state by instantaneous heating by the thermal head, and the coloring component diffuses into contact with the capsule wall as described above, and then a reaction occurs. According to microscopic observation, the reactive substance outside the capsule penetrates into the capsule and reacts, causing the inside of the capsule to be colored. The glass transition point of the capsule of the present invention is either the glass transition point itself inherent to the capsule wall, or the glass transition point "as a system" including the effects of various substances outside the capsule. In particular, when the glass transition point controlling agent outside the capsule is heated and melted during thermal printing and comes into close contact with the capsule wall, a drastic drop in the glass transition point is observed.

In order to completely control the glass transition point specific to the capsule wall, it is necessary to change the type of capsule wall forming agent. Polyurea, polyurethane, polyurea/urethane mixed capsule urea-
Particularly preferred are formalin capsules, polyurea/other synthetic resin mixed capsules in which another ready-made synthetic resin is encapsulated in the core material, polyurethane/other synthetic resin mixed capsules, polyester, polyamide, and the like.

The microcapsules used in the heat-sensitive recording material of the present invention are prepared by emulsifying the entire core material and then forming a wall of a polymer 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,
Examples include polyamide, polyester, polycarbonate, urea-formaldehyde resin, melamine resin, polystyrene, styrene methacrylate copolymer, styrene-acrylate copolymer, and the like.

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 capsules, which are desirable as a recording material and have a uniform particle size throughout and have excellent shelf life, within a short period of time.

This method and specific examples of compounds are described in U.S. Pat.
, 7λt, top issue, J, 7F&, t6ri issue.

For example, when polyurea polyurethane is used as a capsule wall material, a polyvalent incyanate and a second substance that reacts with it to form the capsule wall (e.g., polyol, polyamine) are mixed into the aqueous phase or the oily liquid to be encapsulated, and then submerged in water. By emulsifying and dispersing and then increasing the temperature,
A polymer formation reaction is stimulated at the oil droplet interface, and the entire microcapsule wall is formed. At this time, a co-solvent with a low boiling point and strong dissolving power can be used in the oily liquid. The polyurea is viable even without the second additive mentioned above.

In the above cases, regarding the polyisocyanate to be used and the polyol and polyamine to be reacted with it, U.S. Pat. Kosho ar-≠03μ7,
Same≠Tar2≠IJY, Japanese Patent Application Publication No. 1/r-40191,
4cza-tr+or6, and they can also be used.

Further, in order to fully accelerate the urethanization reaction, a tin salt or the like can be used in combination.

Furthermore, the glass transition point of the wall can be greatly changed by appropriately selecting the polyvalent incyanate as the first wall film-forming substance and the polyol or polyamine as the second wall film-forming substance.

The glass transition point “as a system” is particularly important for polyurea, polyurethane capsules, urea compounds, fatty acid amides,
It can be changed by adding a hydroxy compound, a carbamate ester, an aromatic methoxy compound, etc. in a solid dispersion state. In that case, the amount of the glass transition point regulator added is 0.000000000000000000000 with respect to the weight part of the capsule. /-10 parts by weight can be used.

This glass transition point is measured by measuring the capsule wall or the interaction substance (capsule wall/glass transition point regulator outside the capsule) using a Pybron ((DDV-III type), manufactured by Toyo Baldwin ■), and Peak temperature refers to the dynamic loss modulus divided by the storage modulus.

The capsule wall or the interaction product between the capsule wall and other components to be subjected to the measurement of the glass transition point is prepared, for example, as follows.

Xylylene diincyanate as a capsule wall component/
20 parts of trimethylolpropane (J:/adduct) was dissolved in 30 parts of ethyl acetate, coated on a polyethylene sheet, reacted in water≠O to 0C, and then peeled off.
2≠'C, a4t Chi R, H, air dry for 1 day, lo-2
A polyurea film with a thickness of θμ was obtained. This is the sample for measuring the glass transition point of the capsule wall alone. Is there a method for preparing an interaction material between a heat-melting substance and a capsule wall using the above polyurea film? , I) - After immersion in a 2c% methanol solution of -benzyloxyphenol for 30 hours, λ≠0C4
4 (%1.l) for 7 days and used as a sample.

When making microcapsules, a water-soluble polymer can be used as a protective colloid, but water-soluble polymers include water-soluble anionic polymers, nonionic polymers, and amphoteric polymers. Both natural and synthetic polymers can be used, such as -C
Examples include those having a 00-1-SO-; group. Specific examples of anionic natural polymers include gum arabic,
Alginic acid, etc., and semi-synthetic products include carboxymethyl cellulose, phthalated gelatin, sulfated starch,
Examples include 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, vinylbenzenesulfone-based polymers and copolymers, Examples include carboxy-modified polyvinyl alcohol.

/=Only bulky polymers include polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, and the like.

Examples of amphoteric compounds include gelatin.

These water-soluble polymers are used as a 0.07 to 10 wt% aqueous solution.

The mold release agent used in the present invention is a substance that reduces the adhesive force to the thermal head when the microcapsule coated surface is pressed onto a metal thermal head, heated to 20,066 or higher, and then cooled to room temperature.Specific examples thereof As silicone oil, for example polyfluoroethylene.

Fluororesin, fluorinated carbon oxide, fluorinated hydrocarbon disanomy
Fluorine compounds such as John, for example butyl stearate,
Butyl palmitate, methyl hydroxystearate,
Nisdel, a higher saturated fatty acid with a carbon number of 0 or more, such as diethylene glycol monostearate, higher fatty acids such as stearic acid and palmitic acid, fatty acid amides,
Examples include higher alcohols, such as metal soaps such as zinc stearate, aluminum stearate, lithium stearate, and the like. These are contained in the heat-sensitive layer in an amount ranging from 0 cents by weight to 1 cent by weight of the dry coating amount of the heat-sensitive layer. The mold release agent is dissolved or dispersed in an organic solvent and contained in the microcapsules.

By incorporating it into microcapsules, it is more effective with a smaller amount than when simply added to the heat-sensitive layer, and the effect is not lost over time. Further, there is no loss of effect due to migration into the paper support, or adverse effects such as making the paper support transparent. Also, a liquid roximate agent may be used.

In the present invention, either a basic colorless dye or a diazo compound may be used as the coloring agent.

Basic leuco dyes have the property of producing color by donating electrons or accepting protons such as acids, and although not particularly limited, they are usually colorless and include lactones, lactams, sultones, spiropyrans, and esters. ,
A compound containing a partial skeleton such as an amide and whose partial skeleton opens or cleaves upon contact with a color developer is used. Specifically, crystal violet lactone, benzoylleucomethylene blue, malachite green lactone, rhodamine B lactam, /,! , 3-trimethyl-4'-ethyl-1/-f)oxyindolinobenzospirobilane, λ-dimethylamino-7-medoxyfluoran, 3-diethylamino-7-medoxyfluoran,
no-methyl-3-anilino-fu-cyclohexyl-N-
Examples include methylaminofluorane, 2-chloro-3-anilino-7-ethylaminofluorane, and the like.

As the color developer for these color formers, phenol compounds, organic acids or metal salts thereof, oxybenzoic acid esters, etc. are used.

Phenols and organic acids which are sparingly soluble in water and have a melting point of 0 to 500C, particularly preferably 0 to 2000C, are preferred.

Examples of phenolic compounds include Ge, ≠'-isopropylidene diphenol (bisphenol A), P-te
rt-butylphenol, 2. Hiro-dinitrophenol, 3. ≠-cyclophenol/ -l, μ, 3'-methylene-bis(,2, t-di-tert-7'thylphenol), p-phenylphenol, ≠, ≠-cyclohexylidene diphenol, co, 2 ′-methylenebis(
'A-tert-butylphenol), 2,2'-methylenebis(α-phenyl-p-, l>resol)thiodiphenol, ≠, g'-thiobis(A-tert-butyl-m-cresol), sulfonyldi Phenol, /
l-bis(4t-hydroxyphenyl)-n-)"y"
Kan,≠,zigus(Hiro-hydroxyphenyl)-7-
P-tert- of ethyl hanthanate ester
Examples include butylphenol-formalin condensate and p-phenylphenol-formalin bond.

Examples of the organic acid or its metal salt include J-tert-butylsalicylic acid, 3, j-tert-7'tylsalicylic acid, j-α-methylbenzylsalicylic acid, 3,!
-di-alpha-methylbenzylsalicylic acid, 3-tert-
Useful are octylsalicylic acid, j-α, γ-dimethyl-α-phenyl-γ-phenylpropylsalicylic acid, and their zinc, lead, aluminum, magnesium, and nickel salts.

Examples of oxybenzoic acid esters include ethyl p-oxybenzoate, butyl p-oxybenzoate, heptyl p-oxybenzoate, indyl p-oxybenzoate, and the like. These compounds use water-soluble polymers as protective colloids,
It is used after solid dispersion using a sand mill or the like.

The amount of the compound added per unit area (m2) of the leuco dye is o, or to 1. jf? , preferably 0°0j to O6hirof, and the color developer is 0.1. lrf, preferably o, 5-ay.

Further, in the present invention, it is also possible to use a diazo compound as a coloring agent.

A diazo compound is a diazonium salt represented by the general formula A r N 2 + . (In the formula,
Ar1dfft represents an aromatic moiety substituted or unsubstituted, N2+ represents a diazonium group, and X- represents an acid anion. ) Specific examples of diazonium compounds that form salts include ≠
-Diazo-7-dimethylaminobenzene, ≠-diazo/-diethylaminobenzene, terdiazo-1-penzoylaminoco,! -Jethoxybenzene, San-dia/
-/-morpholinobenzene, ≠-diazo/1μm methoxybenzoylaminoco,! -jethoxybenzene and the like.

A specific example of an acid anion is CnF2n+ICOO
- (n is an integer from 3 to F), CmF 2m+ I So
3 (miJ, [number of 4], (CIFzl+l5O
z)2cH' (1 is an integer of /, /I), BF4-1PF6-, etc.

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

The color developer that reacts with these diazonium salts to form a color is one that couples with the diazonium salt in a basic atmosphere to form a dye (coupling agent), and specific examples include resorcinol, phloroglucin, 2, Sodium 3-dihydroxynaphthalene-6-sulfonate, l-
Hydroxy-naphthoic acid morpholinopropylamide, co-hydroxy-3-naphthoic acid-N-dodecyl-oxy-propylamide, λ-hydroxy-3-naphthoic acid tetradecylamide, acetanilide, acetoacetanilide, indiylacetanilide, / (,!
I,≠',4'-)lichlorophenyl)-3-anilino-! -pyrazolone, /-phenyl-3-phenylacetamide-y-pyrazolone, and the like. Furthermore, by using at least IU of these coupling agents in combination, an image of any color tone can be obtained.

In systems using diazonium salts as total color formers, a basic substance is used in combination for the purpose of promoting color development.

As the basic substance, a water pheasant-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, piperazines, guanidines, indoles, imidazoles, imidacillins, and triazoles. Examples include nitrogen-containing compounds such as morpholines, piperidines, amidines, formazines, and pyridines. Specific examples of these are:
For example, ammonium acetate, tricyclohexylamine,
Octadecylbenzylamine, allyl urea, thiourea,
Methylthiourea, -1-indylimidazole, 2-phenyl-≠-methyl-imidazole, 2-undecyl-imidacillin, 2-phenyl-2-imidacillin, /, 2
．． J-) Riphenylguanidine, l,2-ditolylguanidine b'+--dicyclohexylguanidine, guanidine trichloroacetate, N,N'-dibenzylbi syrine, ≠ U/-dithiomorpholine, 2-aminobenzo There is thiazole. These basic substances can also be used in combination with Ji or more.

The coupling agent and basic substance are finely dispersed in the form of particles,
It is preferable to add. It is preferable to use the coupling agent in an amount of 0, i to 100 parts by weight, and the basic substance in an amount of 0.1 to 20 parts by weight per 1 part by weight of the diazo compound. Also, the diazo compound is 0.0j-2,O
It is preferable to apply f/□2.

A basic colorless dye and a diazonium salt used as a coloring agent are dissolved in an organic solvent and microencapsulated.

As the organic solvent used in the present invention, those with a low boiling point are preferably those with Ifo'C or higher since there is evaporation loss during raw storage, and those with no vinyl polymerization ability include phosphoric esters, phthalic esters, Other carboxylic acid esters and fatty acid amides.

Alkylated hypohenyl, alkylated terphenyl, chlorinated paraffin, alkylated naphthalene, diarylethane, etc. are used. Specific examples include tricresyl phosphate, trioctyl phosphate, octyldiphenyl phosphate, tricyclohexyl phosphate, dibutyl phthalate, dioctyl phthalate, dilaurate phthalate, dicyclohexyl phthalate, butyl oleate, diethylene glycol dibenzoate, dioctyl sepacate, Dibutyl sepacate, dioctyl adipate, trioctyl trimellitate, acetyltriethyl citrate, octyl maleate, dibutyl maleate, inpropylbiphenyl, isoamyl bi7enyl, chlorinated paraffin, diisopropylnaphthalene, i,t'-ditolylethane, Co,≠-ditertiaryamylphenol, N,N-dibutyl-λ-
One example of butoxy is tertiary octylaniline.

The coating liquid can be applied using a suitable binder.

Binders include polyvinyl alcohol, methylcellulose, carboxymethylcellulose, hydroxypropylcellulose, gum arabic, gelatin, vinylpyrrolidone, casein, styrene-butadiene latex, acrylonitrile-butadiene latex, polyvinyl acetate, polyacrylic acid ester, ethylene-vinyl acetate. Various emulsions of copolymers can be used. The usage conditions are solid content 0.1-79/@2.

Microcapsules containing a color former and a release agent.

The other component is either solidly dispersed or dissolved as an aqueous solution and then mixed to create a coating solution, which is then coated on a support such as paper or synthetic resin film with a paring machine, blade coating, air knife coating, gravure coating, or roll coating. A heat-sensitive layer having a solid content λ of j-239/m 2 is provided by coating and drying by a coating method such as , spray coating or dip coating.

The paper used for the support is a heat-extracted PHA sized with a neutral sizing agent such as an alkyl ketene dimer.
- Neutral paper (described in JP-A-Sho!j-/≠2t1)
Fully written information is advantageous in terms of storage stability over time.

In addition, in order to prevent the coating liquid from penetrating the paper and to improve the contact between the recording heat head and the heat-sensitive recording layer, Japanese Patent Application Laid-Open No. 77-114
The paper described in No. 617 having (meter basis weight) 2 and Bekk smoothness of 0 seconds or more is advantageous.

Also, a paper with an optical surface roughness of tμ or less and a thickness of 4AO to 73μ, described in JP-A-5R-ist Hiroki No. 2, JP-A-Sho! ? - Paper with a density O0 f/cWL" or less and an optical contact ratio of /Jr% or more as described in No. 1, JP-A-5R-
Canadian standard household water level (JIS P) listed in TYO No. 27
rtco/)T:uOoal: Paper made from the pulp that has been beaten in the above manner to prevent penetration of the coating liquid, making it a good paper, published by JP-A-Sho!
r-474-3, which improves the color density and resolution by coating the entire glossy surface of base paper made with a Yankee machine, JP-A-Shojter 3! Rit! Papers described in the above-mentioned No. 2003-11-11, in which the base paper is subjected to corona discharge treatment to improve coating suitability, can also be used in the present invention and give good results.

In addition to these, any support commonly used in the field of thermal 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 a heat-sensitive recording material that has excellent storage stability, does not cause head staining, and has excellent thermochromic properties.

Further, in a system using a diazonium salt as a coloring agent, fixation can also be achieved by exposing to ultraviolet light after heating printing to disperse unreacted diazonium salt.

Example 1 Capsules were prepared using the following diazo compounds.

Diazo compound 2 parts of diazo compound and toluylene diisocyanate and trimethylolpropane (J:/H1) 6 parts of xylylene diisocyanate and trimethylolpropane (J
: / ) Adduct/f part? It was added to a mixed solvent of 2≠ parts of diptyl 7-dibutyrate and 5 parts of ethyl acetate and dissolved. Add silicone oil Hirobe as a mold release agent to this diazo compound solution, add polyvinyl alcohol 3. ! part, gelatin/, 7
Part, water! is mixed with an aqueous solution dissolved in
'C to obtain an emulsion with an average particle size of 3 μm. Add 100 parts of water to the resulting emulsion, and stir to
After heating at 0 cvc, capsules t* containing a diazo compound and a mold release agent in the core material were obtained after 2 hours.

Next, the mixture was added to 100 parts of 2θ parts ij% of 2-hydroxy-3-naphthoic acid anilide dissolved in polyvinyl alcohol in water and dispersed in a sand mill for about λ≠time to obtain a coupling component dispersion 1 having an average particle size of 3μ.

Next, 20 parts of triphenylguanidine were added to 100 parts of a 1% polyvinyl alcohol aqueous solution and dispersed in a sand mill for about 2≠ hours to obtain a dispersion of triphenylguanidine with an average particle size of 3 μm. Furthermore, p-benzyloxyphenol 20
Department! The mixture was added to 100 parts of a polyvinyl alcohol aqueous solution and dispersed in a sand mill for about 2 hours to obtain a dispersion of p-benzyloxyphenol having an average particle size of 3 μm.

50 parts of the capsule liquid obtained as above, coupled dispersion l! part, triphenylguanidine dispersion lj
Part 1 was added to prepare a coating solution.

Using a coating rod, coat high-quality paper (3017 m") so that the dry weight is lOy/rrL2, and
A heat-sensitive recording material was obtained by drying at 0c for 30 minutes. of the interaction between the capsule wall and p-benzyloxyphenol.
As a system, the glass transition temperature was i3o~14LO0C.

Comparative Example 1 A heat-sensitive recording material was obtained in the same manner as in Example 1 except that μ part of silicone oil was not added to the core material.

Example 2 1 part of 2-methyl-3-anilino-7-cyclohexyl-N-methylaminofluorane, 1 part of λ-chloro-3-anilino-7-dinithylaminofluorane and trimethylol xylylene diisocyanate as color formers A (3:l) adduct of propane was added to and dissolved in a mixed solvent of 1 part, 1 part, 4 parts, 4 parts, ethyl acetate, and 1 part, all diisopropylnaphthalene. Fluorochemical Q- is added to this leuco dye solution.
7j (experimental formula cyclic ether 3 of C3F160 manufactured by jM Company)
3.6 parts of polyvinyl alcohol, gelatin/7 parts%/I Hiro-di(hydroxyethoxy)benzene, mixed into an aqueous solution in which Hirobe is dissolved in 2 parts of water;
The mixture was emulsified and dispersed using COOC to obtain an emulsion with an average particle size of 3 μm.

To the resulting emulsion was added 100 liters of water and heated to 10 liters with stirring, and after 2 hours, a capsule liquid containing leuco dye and fluorochemical Q-73 as the core substance was obtained.

Next, add 20 parts of bisphenol A to 100 parts of an aqueous solution of kJ-% polyhinyl alcohol, and add about 2≠
By time dispersion, a dispersion of bisphenol A having an average particle size of 3μ was obtained.

5 parts of the capsule liquid obtained as described above and 3 parts of bisphenol A dispersion were added to prepare a coating liquid.

Apply this coating solution to smooth high-quality paper (j Of / m 2 )
≠O0C,
, and dried for 10 minutes to obtain a heat-sensitive recording material. The glass transition temperature of the capsule was OoC.

Comparative Example 2 A heat-sensitive recording material was obtained in the same manner as in Example 2 except that fluorochemical Q-73f was not added to the core material.

Example 3 A mixed solution of 72 parts of crystal violet lactate, (J:/) adduct/part of xylylene diisocyanate and trimethylolpropane, 2q parts of trimethylolpropane trimethacrylate, 1 part of dichloromethane, and λ part of dimethoxyphenylacetophenone Butyl stearate 3
This solution was mixed with 3.0 parts of polyvinyl alcohol. ! 2 parts of Shell Ebicure U (aliphatic amine) and 2 parts of water
The mixture was mixed with aqueous solution dissolved in 100 ml of water and emulsified and dispersed at λo'C to obtain an emulsified dispersion having an average particle size of 3 μm. IOO parts of water was added to the obtained emulsion, and the temperature was raised to 60°C, and after 2 hours, capsule liquid gold was obtained.

5 parts of capsule liquid, 3 parts of bisphenol dispersion of Example 2
A coating liquid was prepared by adding the following parts.

This coating liquid was applied to a smooth high-quality paper (soy/m2') so that the dry weight was 4AO0C1.
It was dried for 30 minutes to obtain a heat-sensitive recording material.

The glass transition temperature of the capsule was tj0 to Fj0C.

Comparative Example 3 A heat-sensitive recording material was obtained in the same manner as in Example 3 except that butyl stearate was not used.

Hitachi Hifax 700 is used for these six types of heat-sensitive recording materials.
When thermal printing was performed using the following, clear colored characters were obtained in Example 1, Comparative Example 12, Example 2, and Comparative Example 2 in black, and in Example 3 and Comparative Example 3 in evening color.

Next, the thermal head was observed for stains after 20 copies were made using a λφ plate completely black sheet-tra original. Example 1.
When Samples 2 and 3 were used, no head stains occurred in either case, and characters could be printed continuously. 1
On the other hand, when the samples of Comparative Example/, J, and 3 were used, stains on the head were observed even in case of b deviation. When this head was subsequently used to print all of the characters, some of the characters became blurred and it was impossible to print all of the characters.

Claims (1)

[Claims] A heat-sensitive recording layer containing microcapsules containing at least one component that causes a color reaction and an organic solvent in the core, and another component that develops a color by reacting with the component that causes a color reaction, is provided on the same side of the support. However, at room temperature, the walls of the microcapsules are impermeable to both the component that causes a color reaction and the other component that reacts with the component that causes a color reaction to form a color. At the temperature of the thermal head, it becomes transparent to at least one of the components that cause a color-forming reaction or the other component that reacts with it to form a color, thereby producing a colored image. A heat-sensitive recording material characterized by containing a molding agent.