JPS6282070A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a thermal recording material free from the color development on a white background part by a solvent or chemicals and forming a developed color image hardly generating discoloration and fading, by incorporating a specific salicylic acid derivative or a metal salt therein as an electron acceptive compound. CONSTITUTION:In a thermal recording material having a thermal color forming layer containing a colorless or light-colored electron donating dye precursor and an electron accepting compound developing a color upon the reaction with the electron donating dye precursor, as the electron acceptive compound, a salicylic acid derivative represented by general formula (I) (wherein R is a 12-18C alkyl group or a aralkyl group, M is a n-valent metal atom and n is an integer) or a metal salt thereof is contained. From the viewpoint of water-insolubility, a compound with the total number of carbon atoms of 15 or more is especially pref. As the metal atom represented by M, zinc, aluminium, magnesium and calcium are pref. As embodiments of the salicylic acid derivative or the metal salt thereof, there are 4-n-dodecylsalicylic acid, 4-t-dodecylsalicylic acid and 4-dodecylsulfosalicylic acid. As the colorless of light- colored donating dye precursor, a triarymethane compound, a diphenylmethane com pound, a xanthene compound, thiazine compound and a spiropyrane compound etc. are designated.

Description

Detailed Description of the Invention (Field of Application of the Invention) The present invention relates to a heat-sensitive recording material, and more particularly to a heat-sensitive recording material that utilizes a color reaction between a colorless or light-colored electron-donating dye precursor and an electron-accepting compound. Concerning recording materials.

(Prior art) A so-called two-component heat-sensitive recording material that utilizes a color reaction between a colorless or light-colored electron-donating dye precursor and an electron-accepting compound was published in the 4th year of the 19th century. -/G039, Special Public Show 4tj-'
It is disclosed in Letθ et al.

Two-component color-forming heat-sensitive recording materials are produced by dispersing a colorless or light-colored electron-donating dye precursor and an electron-accepting compound in the form of fine particles, and then mixing these with a binder, etc. to bind these two types of heat-reactive compounds. Recording is achieved by coating the support on a support in an isolated manner, and utilizing the coloring reaction that occurs when one or both of them melt and come into contact with each other by heating. These two-component color-forming heat-sensitive recording materials are: ■-subsequent color development and does not require development; ■The paper quality is close to that of ordinary paper;
It has the following advantages: 1) It is easy to handle, 2) It has high color density, and 2) It is easy to produce heat-sensitive recording materials with various color hues, and it has great utility value.・Konodame is most commonly used as a heat-sensitive recording material. In particular, the use of heat-sensitive recording materials in the fields of facsimiles, recorders, and printers has been remarkable in recent years.

With the spread of use in the field of facsimile, the recording speed has been increased, but it is also possible to develop colors with sufficient density even with short ξ lus widths, that is, low thermal energy, even on heat-sensitive recording materials. There was a strong demand for improvement in color development, that is, thermal reactivity, and JP-A-Sho! ! -/J'7393, Japanese Patent Publication No. Shoj9-67
6#3 issue, JP-A-60-! Guto! Various attempts have been made as disclosed in No. y and others.

On the other hand, these heat-sensitive recording materials are primary color-developers, so they have the disadvantage that the electron-donating dye precursor and the electron-accepting compound react not only with heat but also with solvents, and the electron-donating dye precursor The disadvantage is that the color-forming material produced by the thermal reaction between the electron-accepting compound and the electron-accepting compound is subject to discoloration due to oils, fats, chemicals, and the like. Therefore, if the heat-sensitive recording material comes into contact with stationery and office supplies such as water-based ink, oil-based ink, fluorescent ink, ink, adhesive, glue, diazo developer, or cosmetics such as No-Rad cream or milky lotion, the heat-sensitive recording material may The white background part of the paper was colored, and the colored part was discolored, significantly reducing the product value.

On the other hand, conventionally, on the heat-sensitive coloring layer,
-27rrθ No. 4T, f'-30G No. 32, %
Efforts have been made to provide a chemical-resistant protective layer, as disclosed in Kaishogu♂-3/937, etc., but the provision of the protective layer may reduce the color development sensitivity or reduce heat sensitivity. The matching performance with the thermal head of the recording device is insufficient, causing problems such as sticking and noise during recording.
Not only did stationery have poor writability, causing problems such as ink smearing, but it also had many drawbacks, such as complicating the manufacturing process.

Furthermore, as a method for improving the discoloration and fading of colored images, Japanese Patent Publication No. Shoj/-143376 and Japanese Patent Publication No. Sho! 3-773g No. 2, Tokukai Sho! ≦-7.2996 issue, JP-A-69-/9g,! No. 1'9/, British Patent Publication Publication.

074t, 33! Attempts have been made as disclosed in No. A, etc., but all of them are either insufficient in improving the discoloration or fading, or although they are effective, the coloring of the white background (capri) is insufficient.
It has disadvantages such as the occurrence of

(Object of the Invention) An object of the present invention is to obtain a heat-sensitive recording material in which white background areas are not colored by solvents, chemicals, etc., and the generated colored images are resistant to discoloration and fading.

(Structure of the Invention) The object of the present invention is to provide a heat-sensitive recording material having a heat-sensitive coloring layer containing a colorless or light-colored electron-donating dye precursor and an electron-accepting compound that reacts with the electron-donating dye precursor to develop a color. , the electron-accepting compound is represented by the following general formula (I):
This was achieved by containing the salicylic acid derivative represented by or its metal salt.

In the above formula, R represents an alkyl group having 7.2 to 1♂ carbon atoms or an aralkyl group, and may have a substituent.

M represents an n-valent metal atom, and n represents an integer. From the perspective of water insolubility, the total number of carbon atoms/! The above compounds are particularly preferred. The metal atom represented by M is particularly zinc, aluminum,
Magnesium and calcium are preferred.

Specific examples of salicylic acid derivatives and their metal salts include:
a-n-dodecylsalicylic acid, g-t-dodecylsalicylic acid, <t-n--”5-ntadecylsalicylic Lg-n-
Examples include heptadecylsalicylic acid, goo(/,3-diphenylbutyl)-salicylic acid, 9-n-octadecylsalicylic acid, goudodecylsulfonylsalicylic acid, goudodecylsulfosalicylic acid, and the like.

Examples of the colorless to light-colored electron-donating dye precursor used in the present invention include triarylmethane compounds, diphenylmethane compounds, xanthine compounds, thiazine compounds, and spiropyran compounds. A specific example is the special 14th century! ! Examples include those described in No.-27233.

To illustrate some of these, triaryl methane compounds include 3,3-bis(p-dimethylaminophenyl)-dimethylamino7thallide (i.e., crystal violet lactone), -) methylaminophenyl) phthalide, 3 (p-dimethylaminophenyl) -J -(/, 3-dimethylindole-3
-yl) phthalide, 3-(p-dimethylaminophenyl)-3-(2-methylindol-3-yl) phthalide, etc. Diphenylmethane compounds include g,g'-bis-dimethylaminopenzhydrin benzyl ether, N-
Halophenyl-leuco, t-lamin, N-2,4t,
,? -) IJ, chlorophenyl leukoolamine, etc., and xanthine compounds include rhodamine-B-anilinolactam, rhodamine (p-nitrino)lactam, '
(Dibenzylamino)fluoran! -phenylamino-6-dinithylamine-fluorane, 5-(O-chloroanilino)-t-diethylaminofluorane, J-
(3,y-dichloroanilino)-6-diethylaminofluorane, 2-anilino-3-methyl-ot-pi-lysinofluora/,-1phenyl-6-diethylaminofluorane, etc. Thiazine compounds include benzoleuco There are methylene blue, p-nitrobenzylleucomethylene blue, etc., and spiropyran compounds include 3-methyl-spiro-
dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3.3'-cyclolosevirodinaphthopyran, 3-
Benzylspiro-dinaphthopyran, 3-methyl-naphtho-(3-methoxy-benzo)-spiropyran, 5--j
'Robiluspirogipenzopyran, etc. These may be used alone or in combination.

Among these, electron-donating dye precursors such as triarylmethane compounds (eg, crystal violet lactone) and xanthine compounds are preferred because they cause less fog and provide high color density.

More preferred are xanthine compounds represented by the following general formula (If).

(In the formula, R1 and R2 represent an alkyl group or a cycloalkyl group having a carbon number of up to IQ, IL3 represents an aryl group, and X represents an alkyl group having a carbon number of up to 10 or a logen atom.

) In the general formula (II), the alkyl groups represented by R1 and R2 may be linear or branched,
It may further have a substituent. The aryl group represented by R3 preferably has carbon atoms of g to .theta., and is preferably a phenyl group having a phenol group or a substituent. As the substituent for the phenyl group, an alkyl group having 7 to 10 carbon atoms is preferable.

Among the electron-donating dye precursors represented by the general formula (II), particularly preferable ones are represented by the following general formula (III).

(In the formula, R1 and R2 represent an alkyl group having carbon number/~10, R
4 represents a hydrogen atom or an alkyl group with a carbon number of / - (I', and X represents an alkyl group with a carbon number of ~? or a chlorine atom.) In the above general formula (III), an alkyl group represented by R1 and R2 may form a term, and may further have a substituent. In the general formula (III) above, X
Particularly preferred are compounds in which is a methyl group or a chlorine atom. Examples of these colorless to light-colored electron-donating dye precursors include, but are not limited to, the following compounds.

Coanilino 3-methyl-6-dimethylaminofluorane, Coanilino 3-methyl-6-N-methyl-N
-ditylaminofluorane, no-anilino-3-methyl-t-N-methyl-N-(iso-propyl)aminofluorane, 2-anilino-3-methyl-t-N-methyl-N -- < methyl Aminofluorane, no anilino
3-Methyl-t-N-methyl-N-cyclohexylaminofluorane, co-anilino 3-methyl-6-dinithylaminofluorane, 2-anilino-3-chloro-6-
dimethylaminofluorane, noanilino-3-methyl-t-N-ethyl-N-(7amylaminofluorane,
no-anilino-3-methyl-t-N-methyl-N-isoamylaminofluorane, co-anilino-3-chloro-g-diethylaminofluoran, co-anilino-3-chloro-t-N-methyl-N-ethylaminofluoran,
-1anilino3-chloro6-N-methyl-N-(i
30-furovir) aminofluorane, co-anilino 3-chloro-4-N-methyl-N-anthylaminofluorane, -1-anilino 3-chloro-8-N-methyl-
N-cyclohexylaminofluorane, noanilino-
3-Methyl-N-ethyl-N-? tylaminofluorane, λ-anilino-3-chloro-N-ethyl-
N-pentylaminofluorane, '(p-methylanilino)-3-methyl-g-dimethylaminofluorane,'
(p-methylanilino)-3-methyl-6-diethylaminofluorane, 2-(p-methylanilino)-3-methyl-6-N-methyl-N-ethylaminofluorane,
2~(p-methylanilino)-3-methyl-t-N~methyl-N-(iso-ilopyl)aminofluorane, -
1(p-methylanilino)-3-methyl-N-methyl-N-pentylaminofluorane, '(p-methylanilino)-3-methyl-≦-N-methyl-N-cyclohexylaminofluorane, -1( p-methylanilino)
-3-Methyl-t-N-ethyl-N-pentylaminofuranthone,'(p-methylanilino)-3-chloro-6
-dimethylaminofluorane, λ-(p-methylanilino)-3-chloro-g-diethylaminofluorane, -
-(p-methylanilino)-3-chloro-go-N-methyl-N-dithylaminofluorane, λ-(p-methylanilino)-3-chloro-6-N-methyl-N-(i
s o-propyl)aminofluorane, '(p-methylanilino)-3-chloro-t-N-methyl-N-cyclohexylaminofluorane, λ-(p-methylanilino)-3-chloro-t-N-methyl -1'J-<pentylaminofluorane, '(P-methylanilino)-3-chloro-6-N-ethyl-N-pentylaminofluorane,
There are noanilino-3-methyl-, <-N-methyl-N-furylmethylaminofluorane, 2-anilino-3-ethyl-t-N-methyl-N-71J-rumethylaminofluorane, etc., and these can be used alone. However, it is okay to mix two or more types to adjust the color tone and prevent color fading of the colored image, but it is also okay to mix two or more types to adjust the color tone and prevent color fading of the colored image. .

In the heat-sensitive recording material according to the present invention, a heat-fusible substance can be contained in the heat-sensitive coloring layer in order to improve its heat responsiveness.

As an example of a preferable thermofusible substance, the following general formula (IV) is used.
Examples include compounds represented by (IX).

R5NHCONH2 (■) R6CONH-R7 (■) In the formula, R1 to R4 are respectively a phenyl group, a benzyl group,
and a lower alkyl or halogen substituted product thereof, R5 and R6 each represent an alkyl group having 72 to 24 carbon atoms, and R7 represents hydrogen or a phenyl group.

Further, when the phenyl group or benzyl group represented by R1-R4 in general formulas (IV) to (M) is substituted with a lower alkyl group, the number of carbon atoms is / or more! Below, preferably 1
The above is 3 or less. When substituted with a nitrogen atom, preferred is fluorine. Also, the formula (Vl
), R4' represents hydrogen or hydroxyl group.

(■) In the formula, R8 represents a divalent group, preferably an alkylene group, an alkylene group having a carbonyl group, an alkylene group having a halogen atom, an alkylene group having an unsaturated bond, more preferably an alkylene group, an ether bond. Indicates an alkylene group with

MakX, Y, Z, X', Y', Z'
tdjill;temodi;'z may be present, and represents a hydrogen atom, a halogen atom, an alkyloxycarbonyl group, or an aralkyloxycarbonyl group.

The compounds of the general formulas (I'/) to (l have a melting point of 7θ0C
The melting point is preferably ♂θ0C or more/3o0C or less. Specifically, benzyl p-benzyloxybenzoate (mp
, //9 °C), β-naphthylbenzyl ether (
mp,, i 0! 'C), stearic acid amide (
mp, /θ♂QC: ) 1. l! Rutimic acid amide (mp, 103 °C), N-phenylnialine, acid amide (mp, 96 °C), N-stearylurea (mp, /10'C), β-naphthoic acid phenyl ester (mp, 9 .2°C), /-Hydroxyethyl 7toic acid phenyl ester (mp, 9.2°C)
, β-naphthol (p-chlorobenzyl) ether (m
p, /is 0C), β-naphthol (p-methylbenzyl) ether (mp, 9+ °C), α-naphthylbenzyl ether (mp, yt °C), /, goubutanediol-p-methylphenyl ether ( mp,
ri3'C), /, e--! Lonogufudiol-p-methyl phenyl ether (mp, 23°C), /, goubutanediol-p-inpropylphenyl ether (m
p, 2y °C), /l gobutanediol p-t-
Octylnoenyl ether (mp.

99 °C), -phenoquine/-p-tolyl-
Oxy7-ethane (mp, /Qg0C), /-phenoquine-(couethylphenoxy)ethane (mp,
/θt 0C), /-phenoquine-2=(couchlorophenoxy/)ethane (mp, 270C), /l goubutanediol phenylethe/l/ (mp, 9
♂OC), diethylene glycol-bis(coumetquin-phenyl)ether <mp.

1070C), etc.

The thermofusible substance may be used alone or in combination, and in order to obtain sufficient thermal responsiveness, it is preferable to use the thermofusible substance in an amount of /θ to 200% by weight, and further The preferred usage amount is one! θ~/30 weight ratio.

A water-soluble binder is added to the recording layer of the heat-sensitive recording material of the present invention, and these binders include 2r0C
against the water! Compounds that dissolve at least 100% by weight are preferred;
Specifically, methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, starches (including modified starch), gelatin, gum arabic, casein, styrene-maleic anhydride copolymer hydrolyzate, ethylene-maleic anhydride copolymer hydrolyzate substance, imbutylene-
Examples include hydrolysates of maleic anhydride copolymers, polyvinyl alcohol (PVA), carboxy f-type vinyl alcohol, polyacrylamide, and saponified copolymers of vinyl acetate and polyacrylic acid.

Furthermore, if necessary, pigments, water-insoluble binders, metal soaps, waxes, surfactants, etc. may be added to the recording layer of the heat-sensitive recording material of the present invention.

As pigments, zinc oxide, calcium carbonate, barium sulfate, titanium oxide, lithopone, talc, waxite, kaolin, aluminum hydroxide, silica, amorphous silica, etc. are used, but light calcium carbonate, kaolin, surface treatment Amorphous silica and aluminum hydroxide are preferred. Further, it is preferable to mix and disperse zinc oxide when dispersing the zinc salt of the electron-accepting compound according to the present invention, since a higher effect of improving image discoloration and fading can be obtained.

As the water-insoluble binder, synthetic rubber latex or synthetic resin emulsion is generally used, such as styrene-butadiene rubber latex, acrylonitrile-butadiene rubber latex, methyl acrylate-butadiene rubber latex, vinyl acetate emulsion, etc. . In order to prevent capri in heat-sensitive recording materials, the amount of surfactant used in the rubber latex or emulsion should be as small as possible, and a so-called lump-free rubber latex or emulsion is preferred.

As the metal soap, a higher fatty acid metal salt is used, and an emulsion of zinc stearate, calcium stearate, or aluminum stearate is used.

As the wax, emulsions such as paraffin wax, microcrystalline wax, carnauba wax, methylolstearamide, polyethylene wax, and polystyrene wax are used.

As the surfactant, sulfosuccinic acid-based alkali metal salts, fluorine-containing surfactants, etc. are used.

(Examples of the Invention) Examples are shown above, but the present invention is not limited thereto. Weight % unless otherwise specified in the examples
represents.

(Example/~♂) Table 1 shows the materials used for the heat-sensitive coloring layer according to the present invention.

The electron-donating dye precursor, electron-accepting compound, and thermofusible substance were each = θg, and dispersed with 10 gg of 5% HoIJ vinyl alcohol (Cran PVA/θ) in a Pall mill overnight to determine the volume average particle size. The pigment was z
og is the θ of sodium hexametaphosphate,! Ch solution/lOg
It was used after being dispersed with a homogenizer.

Each of the dispersions dispersed as described above was mixed in a ratio of 22g of electron-donating dye precursor dispersion jg, electron-accepting compound dispersion/θg, thermofusible substance dispersion 'g, and pigment dispersion. and 4' g of emulsion of zinc stearate.
2'40 (21st hexyl)-aqueous solution of sodium sulfosuccinate! g was added to obtain a coating liquid. The basis weight of this coating liquid! Coat with a wire bar so that the dry coating amount is 4 g/m2 on high-quality paper of θg/m2, and
It was dried for 1 minute in the open position C, and then subjected to a gear render process to achieve a surface smoothness of 500 seconds (Peck).

(Comparative Examples/--Examples 7-!) Heat-sensitive recording materials were obtained in the same manner as in Examples except that the electron-accepting compounds were changed to the compounds shown in Table 2.

(Table 2) Thermal response is determined by Fujitsu's high-speed facsimile IJFF-200.
0, the Image Electronics Engineers of Japan test chart) = %3 was copied, and its density was measured using a Macbeth RD-De/♂ model densitometer.

On the other hand, chemical resistance includes ethanol, ethyl acetate, polyethylene glycol (I00), castor oil, paraffin oil (I0g seconds), diazo developer (Ricoh Co., Ltd., Ricopy SD
) were impregnated into filter paper and superimposed on the colored surface of the thermosensitive recording paper obtained by the above method, and the degree of color erasure (discoloration) of the capri of the white background and the colored image was very excellent (almost No change), Excellent (some changes observed), Practical (
Evaluation was made on a y-level basis: ``Capri color development or image decolorization occurs, but the image is legible'' and ``impossible'' (capri color development or image decolorization, making it very difficult to decipher the image).

In addition, a 720°C heat pen (pressure! 00 g/cm2
The heat resistance (6θ
0°C, 3o high RH)/humidity resistance (0°C, 90% Rl
-f) The capri density of the white background area and the density of the colored area before and after storage for JQ time under the conditions of Macbeth Co., Ltd. RD-q, r
Measured using a type densitometer. In addition, the storage stability of the density of the colored part is
(Concentration after storage ÷ Concentration immediately after color development) x 10θ (% display)
It was shown in

The results are shown in Table 3. The results shown in the table show that the heat-sensitive recording material according to the present invention has high thermal responsiveness and is not only capable of producing high-density images, but also does not cause Capri color development or decolorization of printed images due to chemicals, and is extremely excellent. It can be seen that it has excellent performance.

1937/Month e1-1 Commissioner of the Patent Office 2., Onion.

1.Display of case Showa toi [, long-awaited 22nd
33 Hiro θ No. 2, Title of the invention Thermal recording material 3, Relationship with the person making the amendment Patent issue, applicant address 210 Nakanuma, Minamiashigara City, Kanagawa Prefecture ゛\,-1'' Contact information 〒10 (i-to! :I, Miyakoko 1zu Nishi 1kyu (II2
1112fi insult: (No. 0'('z;i':'Suj゛ji Ilm Co., Ltd. 7 (Tokyo Honne 1 ton story (I0(i) 25
:l 7 (3゛1□ 1゜47 Date of amendment order--Showa-1111-11-Part--Greeting old tongue day → If 5 Target of amendment Statement of amendment Contents of amendment We will submit an engraving (with no changes to the inner surface).

Claims (1)

[Scope of Claims] A thermosensitive recording material having a thermosensitive coloring layer containing a colorless to light-colored electron-donating dye precursor and an electron-accepting compound that reacts with the electron-donating dye precursor to form a color. A heat-sensitive recording material characterized by containing a salicylic acid derivative represented by the following general formula (I) or a metal salt thereof as a chemical compound. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) (In the formula, R represents an alkyl group having 12 to 18 carbon atoms or an aralkyl group. Also, M represents an n-valent metal atom,
n represents an integer. )