JPS62292478A - Recording material - Google Patents

Abstract

PURPOSE:To obtain a thermal recording material having sufficient developed color density and color forming sensitivity and excellent stability with time, by using at least one electron-donative colorless dye, at least one electron- acceptive compound and at least one specified flux. CONSTITUTION:The purpose is accomplished by a recording material using at least one electron-donative colorless dye, at least one electron-acceptive compound and at least one flux of the formula, wherein each of Ar1, Ar2, Ar3 and Ar4 is an aromatic ring and R is a 1-10C bivalent group. The colorless dye may be a triarylmethane compound, a diphenylmethane compound or the like. The electron-acceptive compound may be a phenol compound, an organic acid or a metallic salt thereof, a hydroxybenzoic acid ester, an inorganic acid or the like. The flux is used by dispersing it in a dispersant to a particle diameter of 5mum or below by a grinder, a dispersing machine or the like.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention (Field of Application of the Invention) The present invention relates to a recording material, and particularly to a heat-sensitive recording material with improved stability over time and color development.

<Prior Art> A heat-sensitive recording material using an electron-donating colorless dye and an electron-accepting compound is disclosed in British Patent No. 2,140,449.

The properties that a heat-sensitive recording material should have are (11) sufficient color density, (2) no color development during storage before use, and (3) sufficient fastness of the color body after color development. Although there are certain things, we cannot currently find anything that fully satisfies these.

In particular, with the increase in speed of thermal recording systems in recent years, the above Tl)
Research is being carried out intensively.

The method is to lower the melting point of the electron-accepting compound itself to 12
0°C or below, using an organic acid and a phenolic compound together as an electron-accepting substance, or using a polyvalent metal salt of a compound having an alcoholic hydroxyl group.
Using a copolymer of hydroxyethylcellulose and maleic anhydride, adding waxes, thioacetanilide, phthalonitrile, acetamide, di-β
-naphthyl-p-phenylenediamine, fatty acid amide,
Nitrogen-containing organic compounds such as acetoacetanilide, diphenylamine, henzamide, carbazole, etc.
．． Addition of thermofusible substances such as 3-di-m-) butane, 4.4''-dimethylbiphenyl, or carboxylic acid esters such as dimethyl phthalate, diphenyl phthalate, dimethyl terephthalate, etc. as sensitizers, hindered Attempts have been made to add phenols.

However, heat-sensitive recording materials produced using these methods are insufficient in terms of color density and color development sensitivity, or have insufficient image storage stability over time.

<Object of the Invention> Accordingly, an object of the present invention is to provide a heat-sensitive recording material which has sufficient color density and color development sensitivity and is excellent in stability over time.

<Structure of the Invention> The object of the present invention is to use one or more of each of an electron-donating colorless dye, an electron-accepting compound, and a heat-fusifying agent represented by the following general formulas (1) and (II). Achieved through recording materials.

Art OR-OArt (1) Arm
S R5Arz (It) where Ar, , Ar, , Ar3 and Ar4 represent an aromatic ring, and R represents a divalent group having 1 to 10 carbon atoms.

More specifically, Arl, Arz, Arx, and Ar.

represents a substituted or unsubstituted 5- or 6-membered aromatic ring consisting of a monocyclic ring or a condensed ring. It may contain oxygen atoms, nitrogen atoms, sulfur atoms, etc. in addition to carbon atoms.

From the viewpoint of raw material availability and handling, benzene rings and naphthalene rings are most advantageous.

When having a substituent, a cyano group, thioalkoxy group, acyl group, alkyl group, aryloxy group, alkoxy group, acylamino group, halogen atom, alkyloxycarbonyl group, aralkyl group or 7-alkyloxycarbonyl group, alkenyl group, cycloalkenyl group, oxy group, thioalkoxy group, alkanesulfonyl group, carbonato group, sulfo group, sulfonato group, aryl group, and the like.

Among these, groups having 15 or less carbon atoms, preferably 4 or less carbon atoms, have excellent performance.

For example, methyl group, ethyl group, isopropyl group, methoxy group, ethoxy group, allyl group, chlorine atom, fluorine atom,
Acetyl group, propionyl group, butoxy group, oxy group,
Examples include thiomethoxy group, methoxycarbonyl group, and chloromethyl group. R is 2 with 1 to 10 carbon atoms
Particularly preferred among the valent groups are linear or branched alkylene, oxaalkylene, thiaalkylene, or alkenylene. Among them, straight-chain alkylenes having 6 or less carbon atoms, oxaalkylenes, polyoxaalkylenes, thiaalkylenes, and the like are excellent in terms of ease of synthesis and ease of product purification.

Furthermore, those which are lipophilic, have high whiteness, and have a melting point of 60°C to 180°C, particularly 85°C to 145°C, are preferable.
Those having a melting point of 0°C are preferred. Compounds of the invention,
The heat-sensitive recording material containing this material has sufficient color density and inventive sensitivity, and also shows less deterioration in color sensitivity over time and less fog (
The fastness of the colored image after coloring is also sufficient.

Specific examples will be shown next, but the present invention is not limited thereto.

Examples of compounds represented by general formula (1) 1) 1,2-bisphenoxyethane 2) 1,2-bis-p-tolyloxyethane 3) 1
．． 2-bis-p-chlorophenoxyethane 4) 1
．． 2-bis-p-methoxyphenoxyethane 5) 1.3-bis-p-tolyloxypropane 6
) 1.3-bis-p-chlorophenoxyprotuman 7) 1.4-bis-phenoxybutane 8) 1.4-bis-p-tolyloxybutane 9)
1.4-bis-p-chlorophenoxybutane 10) l, 4-bis-α-naphthyloxybutane 11)
1.6-bis-phenoxyhexane 12) 1.3-bisphenoxy-2-benzyloxypropane 13) Bis-(2-p-tolyloxyethyl) ether 14) Bis-(β-3,5-dimethylphenoxyethyl ) Ether 15) Bis-(β-4-benzyloxycarbonylphenoxyethyl) ether 16) 1-phenoxy-2-p-ethylphenoxyethane 17) Bis-(2-β-naphthyloxyethyl) ether 18) 1.2 -bis(2-(p-tolyloxy)ethoxy)ethane19)l, 2-bis(2-(3,5-dimethylphenoxy)ethoxy)ethane20)l-phenoxy-2-p-chlorophenyloxyethane21)1 .2-Bis(2-β-naphthyloxyethoxy)ethane 22) Bis(2-p-1lyloxyethoxy)methane 23) Bis(2-(2,4,6-1-dimethylphenoxy)ethoxy)methane 24 ) 1-phenoxy-2-β-naphthyloxyethane 25) Bis(2-β-naphthyloxyethoxy)methane 2G) Bisphenoxymethyl sulfide 27) Bis(2
-phenoxyethyl) sulfide 28) 1,3-bisphenoxymethylbenzene 29) 1,2-bisphenoxymethylbenzene 30) bisphenoxymethyl ether 31) 1-phenoxy-2-p-ethylphenoxyethane 32) 1.3. 5-Trisphenoxyethoxyhenzene 33) 1-phenoxy-2-p-tolyloxyethane 34) 1-phenoxy-2-β-naphthyloxypropane 35) 1-p-tolyloxy-2-p-chlorophenoxyethane 36) 1.3-diphenoxy-2-propertool 37)
Examples of compounds represented by general formula (II) such as 4-(2-phenoxyethoxy)benzoic acid methyl ester 1) 1.2-bis(phenylthio)ethane 2) 1.2-bis(4-methoxyphenylthio)ethane 3) 1.2-bis(3-methoxyphenylthio)ethane 4) 1.2-bis(4-methylphenylthio)ethane 5) 1.2-bis(2-methylphenylthio)ethane 6) 1.2 -Bis(4-methylphenylthio)propane? ) 1-(4-methylphenylthio)-2-(4
-Methoxyphenylthio)ethane 8) 1,4-bis(4-methoxyphenylthio)butane 9) 1,6-bis(4-methylphenylthio)hexane 10) Bis(2-(4-methoxyphenylthio)ethyl) [Sulfide 11) Bis(2-(4-methylphenylthio)ethyl]
Ether 12) 2.2'-bis[2-(phenylthio)-ethyl]diethyl sulfide 13) 1.2-bis(2-naphthylthio)ethane, etc. One or more of these may be used as a mixture.

Regarding the usage ratio of the heat-fusifying agent represented by the general formula (1) and the general formula (If), it is preferable that either one of the components is used in an amount of 10% or more, particularly preferably 20% or more.

Further, these thermofusifying agents may be used in combination with other thermofusifying agents.

When Arl and Ar= are the same, compatibility increases and stability over time improves.

In particular, the melting start temperature of the mixture used in combination is 70℃~12℃.
A temperature of 5°C is particularly preferred.

Examples of the electron-donating colorless dye used in the present invention include triarylmethane compounds, diphenylmethane compounds,
Xanthine compounds, thiazine compounds, spiropyran compounds, etc. are used. To illustrate some of these, triarylmethane compounds include 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide and 3,3-bis(p-dimethylaminophenyl)phthalide. , 3-(p-dimethylaminophenyl)-
3-(1,3-dimethylindol-3-yl)phthalide, 3-(p-,diferaminophe;7,l)-3-
(2-methylindol-3-yl)phthalide, etc., and diphenylmethane compounds include 4,4°-
Bis-dimethylaminobenzhydrin benzyl ether, N-halophenyl-leucoolamine, N-2,4,
5-trichlorophenylleucoolamine, etc., and xanthine compounds include rhodamine-B-anilinolactam, rhodamine (p-nitroanilino)lactam, rhodamine B (p-chloroanilino)lactam, 2
-dibenzylamino-6-diethylaminofluorane,
2-anilino-6-diethylaminofluorane, 2-7
Nilino 3-methyl-6-diethylaminofluorane,
2-anilino-3-methyl-6-cyclohexylmethylaminofluorane, 2 o-chloroanilino-6-diethylaminofluorane, 2-m-chloroanilino-6
-diethylaminofluorane, 2- (3,4-dichloroanilino)-6-diethylaminofluorane, 2-octyl 7minor 6-diethylaminofluorane, 2-dihexylamino-6-diethylaminofluorane, 2-
m-Trifluoromethylanilino-6-diethylaminofluorane, 2-butylamino-3-chloro-6-diethylaminofluorane, 2-ethoxyethylamino-3-
Chloro-6-diethylaminofluorane, 2-p-chloroanilino-3-methyl-6-sibutylaminofluorane, 2-anilino-3-methyl-6-sioctylaminofluorane, 2-anilino-3-chloro- 6-diethylaminofluorane, 2-diphenylamino-6-diethylaminofluorane, 2-anilino-3-methyl-6-
Siphenylaminofluorane, 2-phenyl-6-diethylaminofluorane, 2-anilino-3-methyl-6
-N-ethyl-N-isoamylaminofluorane, 2-
Anilino-3-methyl-5-chloro-6-diethylaminofluorane, 2-anilino-3-methyl-6-dinithylamino-7-methylfluoran, 2-anilino-3-
Methoxy-6-sibutylaminofluorane, 2-o-chloroanilino-6-sibutylaminofluorane, 2-p
-chloroanilino-3-ethoxy-6-N-isoamylaminofluorane, 2-o-chloroanilino-6-p-
Butylanilinofluorane, 2-anilino-3-pentadecyl-6-diethylaminofluorane, 2-anilino-3-ethyl-6-sibutylaminofluorane, 2-anilino-3-ethyl-6-N-ethyl- 6-N-ethyl-N-isoamylaminofluorane, 2-anilino-3
-Methyl-6-N-ethyl-N-r-methoxypropylaminofluorane, 2-anilino-3-chloro-6-N
-Ethyl-N-isoamylaminofluorane, etc. Thiazine compounds include benzoylleucomethylene blue, p-nitrobenzylleucomethylene blue, etc. Spiro compounds include 3-methyl-spiro-dinaphthopyran, 3-ethyl- spiro-dinaphthopyran,
3.3'-Cyclolosespirodinaphthopyran, 3-
Examples include pendylsuvirodinaf, tobiran, 3-methyl-naphtho-(3-methoxyhenzo)spiropyran, and 3-propyl-spirodibenzupyran. These may be used alone or in combination, and it is preferable that two types exhibiting 11 prefecture hues are used in combination.

Further, examples of electron-accepting compounds include phenolic compounds, organic acids or metal salts thereof, oxybenzoic acid esters, and inorganic acids. Phenol compounds are particularly preferred because they can be used in a small amount. Examples include 2-(4-hydroxyphenyl)-2-(3-isopropyl4-hydroxyphenyl)propane, 2-(4-hydroxyphenyl)2-(3-allyl-4-hydroxyphenyl)propane, 2-( 4-hydroxyphenyl) -2-(3-methyl-4-hydroxyphenyl)propane, α-isopropyl-β-naphthol, methyl-4-hydroxybenzoate, monomethylated dihydroxybiphenyl, 2
．． 2-bis(4-hydroxyphenyl)propane (bisphenol A), 4.4゛-isopropylidene bis(
2-methylphenol), 11-bis-(3-chloro-
4-hydroxyphenyl)cyclohexane, 1.1-bis-(3-chloro-4-hydroxyphenyl)-2-ethylbutane, 4.4”-isobutylidene diphenol,
4-Hydroxybenzoic acid benzyl ester, 4-hydroxybenzoic acid M-m-chlorobenzyl ester, 4-hydroxybenzoic acid β-phenethyl ester, 4-hydroxy-2°, 4°-dimethyldiphenylsulfone, 1-t
-Butyl-4-p-hydroxyphenylsulfonyloxybenzene, 4-N-benzylsulfamoylphenol, 2,4-dihydroxybenzoic acid-p-methylbenzene ester, 2,4-dihydroxybenzoic acid-β-phenoxyethyl ester , 2,4-dihydroxydi-6-methylbenzoic acid benzyl ester, zinc chloride or zinc rotane.

The heat-fusifying agent used in the present invention is dispersed in a dispersion medium to a particle size of 5 μm or less using a pulverizer or a dispersion machine. Alternatively, the electron-donating colorless dye and/or electron-accepting compound may be added and dispersed at the same time when the electron-donating colorless dye and/or electron-accepting compound is dispersed in the dispersion medium using a ball mill, sand mill, or the like.

Particularly, if the colorless dye is dispersed at the same time as the colorless dye, there is an advantage that the obtained dispersion is less colored.

Furthermore, there is an advantage that sensitivity can be easily increased if the electron-accepting compound is dispersed at the same time.

The electron-donating colorless dye and electron-accepting compound used in the present invention are pulverized and dispersed in a dispersion medium to a particle size of 3 μm or less, preferably 2 μm or less. As a dispersion medium, a water-soluble polymer aqueous solution with a concentration of about 0.2 to 5% is generally used, and dispersion is carried out using a ball mill, sand mill, attritor,
This is done using a colloid mill or the like.

The ratio of the electron-donating colorless dye to the electron-accepting compound used is preferably between 1:10 and 1:1 by weight, and particularly preferably between 1:5 and 2:3. Further, the specific compound of the present invention is added in a weight ratio of 20% or more and 300% or less, particularly 40% or more and 1
50% or less is preferable.

If the amount added is less than 20%, the sensitivity improvement effect aimed at by the present invention will not be sufficient, and if the amount added is 300% or more,
On the contrary, it causes a decrease in sensitivity.

Additives are further added to the coating liquid thus obtained in order to meet various requirements.

Examples of additives include dispersing oil-absorbing substances such as inorganic pigments in order to prevent the recording head from becoming dirty during recording, and fatty acids and metal stones to improve the releasability of the head. Ken etc. are added. Therefore, in general, in addition to color formers and color developers that directly contribute to color development, pigments,
Wax, antistatic agents, surfactants, additives, etc. are coated onto the support to form a heat-sensitive recording material.

Specifically, the pigments include kaolin, calcined kaolin, talc, waxite, diatomaceous, calcium carbonate, aluminum hydroxide, magfcium hydroxide, magnesium carbonate,
titanium oxide, barium carbonate, barium sulfate, calcined gypsum,
Selected from urea-formalin filler, gypsum, cellulose filler, etc. Examples of waxes include paraffin wax, carnauba wax, microcrystalline wax, polyethylene wax, and higher fatty acid esters.

Examples of metal soaps include fatty acid metal salts, such as zinc stearate, aluminum stearate, calcium stearate, and zinc oleate.

Other additives that can be added include anti-fading agents, conductive agents, optical brighteners, foam suppressants, and the like. As the anti-discoloration agent, a hindered phenol derivative is preferable, and a phenol derivative in which at least one of the 2 or 6 positions is substituted with a branched alkyl group is particularly preferable. Moreover, those having a plurality of phenol groups in the molecule are preferable, especially 2 to 3.
Those having phenol groups are preferred. As a specific example, 1,1-bis(2-methyl-4-hydroxy-5-
t-butylphenyl)butane, 1.1.3-tris(3
-methyl-4-hydroxy-5-t-butylphenyl)
Butane, bis(2-hydroxy-3-t-butyl-5-
Methylphenyl)methane, bis(2-methyl-4-hydroxy-5-butylphenyl)sulfide, and the like.

The amount added is 20% or more relative to the electron-accepting compound.
Added at a weight ratio of 0% or less, especially 40% or more and 150%
The following are preferred.

These are dispersed and applied in a binder.

Water-soluble binders are generally used, such as polyvinyl alcohol, hydroxyethyl cellulose, hydroxypropyl cellulose, ethylene-maleic anhydride copolymer ammonium salt, styrene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer Polyacrylic acid, polyacrylic acid, acrylamide copolymer, modified polyacrylic acid amide, starch derivative, casein, gelatin, etc. In addition, in order to impart water resistance to these binders, water-resistant agents (gelling agents, cross-linking agents) are added, or emulsions of hydrophobic polymers, specifically styrene-butadiene rubber latex, acrylic resin emulsions, etc. It can also be used.

Furthermore, a protective layer made of polyvinyl alcohol, methylol acrylamide copolymer, etc., methylol melamine, boric acid, etc. can be added.

The coatings are most commonly coated and calendered onto a smooth 5μ to 250μ support, preferably neutral paper. It may also be applied onto cardboard that has been primed with a pigment or the like.

Common application methods include air knife coating, blade coating, and curtain coating.

First of all, the coating amount is 2 to 10 g/m2 in terms of solid content, the lower limit being determined by the concentration during color development by heating, and the upper limit being determined mainly by economic constraints.

<Examples of the Invention> Examples are shown below, but the present invention is not limited only to these examples.

Example (1) Preparation of sample 2-anilino-3-chloro- which is an electron-donating colorless dye
2.0 g of 6-diethylaminofluorane, 3.5 g of 2-anilino-3-methyl-6-N-methyl-N-isoamylaminofluorane, and the heat-melting agent Log shown in Table 1 were mixed with 5% polyvinyl alcohol ( The mixture was dispersed in a sand mill with 35 g of an aqueous solution (Sapon number: 99%, polymerization degree: 1000). On the other hand, 10 g of bisphenol A, which is an electron-accepting compound, is similarly dispersed with 100 g of a 5% polyvinyl alcohol aqueous solution using a sand mill.

After these dispersions were mixed, 20 g of kaolin (Jossia kaolin) was added to ensure good dispersion, and 3.5 g of a 50% paraffin wax emulsion dispersion (Middle East Cellosol #428) was added to prepare a coating liquid.

In Example 3, when dispersing the heat-fusifying agent, 5 g of 1°■-bis12-methyl-4-hydroxy-5-t-butylphenylbutane was also dispersed.

The coating solution was applied onto neutral paper with a basis weight of 50 g/m2 to a solid content of 5.8 g/m2, and heated at 60°C.
After drying for 1 minute, a recording material was obtained by applying a super calender at a cotton pressure of 68 kgW/cm.

Recording material is heated by facsimile with energy of 35 m
Color was developed by heating using J 7 mm2, and the color density was determined.

The printing density was 8 doL/mm x 6 dots/mm with a pulse width of 1 mS.

The results are shown in Table 1.

- The colored coated paper was stored at room temperature in an atmosphere of 40 to 60% RH for 6 months, and the color density was determined. The results are shown in Table 1.

(2) Preparation of Comparative Sample A similar test was conducted using the exact same formulation as that used to prepare the sample, but using one of the thermofusible agents instead of the thermofusible agent of the present invention.

The results are also shown in Table 1.

It can be seen from Table 1 that the recording material according to the present invention clearly has high sensitivity and excellent storage stability over time.

Claims (1)

[Scope of Claims] A recording material characterized in that it uses one or more of each of an electron-donating colorless dye, an electron-accepting compound, and a heat-fusifying agent represented by the following general formulas (I) and (II). Ar_1-O-R-O-Ar_2(I) Ar_S-R-SAr_4(II)) However, here Ar_1, Ar_2, Ar_3 and Ar
_4 represents an aromatic ring, and R represents a divalent group having 1 to 10 carbon atoms.