JPS6251480A - Thermal recording material - Google Patents

Abstract

PURPOSE:To provide the title recording material having good sensitizing effect and forming an image having excellent stability to chemicals, by having at least one kind of a specific heat-meltable compound contained in a thermal color forming layer containing a leuco dye and a developer. CONSTITUTION:A compound represented by formula (wherein R1 and R2 are a 10-30C substituted or unsubstituted alkyl group and R3 is a divalent hydrocarbon group) is contained in a thermal color forming layer. Thermal recording material thus obtained is enhanced in its heat sensitivity as compared with a conventional product and a background is white and image stability is markedly enhanced.

Description

Detailed Description of the Invention [Technical Field] The present invention relates to the improvement of heat-sensitive recording materials containing leuco dyes as color formers. [Prior Art] Heat-sensitive recording materials are generally prepared on a support such as paper, synthetic paper, or plastic film. A thermal head equipped with a thermosensitive coloring layer containing a thermochromic composition as the main component.

Colored images can be obtained by heating with a thermal pen, laser light, etc. Compared to other recording materials, this type of recording material does not require complicated processing such as development and fixing, can produce records in a short time using relatively simple equipment, and generates less noise and pollutes the environment. Due to its advantages such as low cost, it is used not only for copying books and documents, but also as a recording material in a wide range of applications such as electronic computers, facsimile machines, ticket vending machines, labels, and recorders. Thermochromic compositions used in such heat-sensitive recording materials generally consist of a color former and a color developer that causes the color former to develop color when heated. As the color former, for example, a composition having a lactone, lactam or spiropyran ring Colorless or light-colored leuco dyes
Furthermore, various acidic substances such as organic acids and phenolic substances are used as color developers. A recording material made by combining a color forming agent and a color developing agent has a particularly clear color tone and a high background whiteness, and the image (dye image)
It has the advantage of excellent weather resistance and is widely used.

In recent years, heat-sensitive recording materials have replaced other conventional recording methods, and as the demand for them has increased, the demand for improving the quality of the heat-sensitive recording materials used in these heat-sensitive recording methods has also increased. Increasing the speed of processing has become a major issue in thermal recording. Various methods have been proposed to increase the speed of heat-sensitive recording materials, but there is a method to increase the speed by using a thermofusible substance in combination to improve the thermal sensitivity. sexual substances have been proposed.

In this case, it is thought that the thermofusible substance must not only melt at a low melting point but also have physical properties such as melt viscosity and compatibility with color developers and dyes in a short period of time. Furthermore, the thermofusible substance may affect the stability of recorded images, and it is necessary that stable images be maintained for a long period of time. Further, even if the same thermofusible substance is used, the sensitizing effect may differ depending on the type of color developer used in combination. Therefore, it is desired that the thermofusible substance has a good sensitizing effect on a wide variety of color developers.

In addition, it is common to provide a protective layer as a method of stabilizing images against chemicals, but providing a protective layer reduces heat transfer efficiency and reduces recording speed. It is preferable that

〔the purpose〕

An object of the present invention is to provide a heat-sensitive recording material that has a good sensitizing effect that increases the sensitivity of the heat-sensitive recording material and contains a thermofusible substance that is effective in stabilizing images against chemicals. .

〔composition〕

According to the present invention, there is provided a heat-sensitive recording material characterized in that at least one compound represented by the following general formula is contained in a heat-sensitive color forming layer containing a leuco dye and a color developer.

R, NHCONHR3NHCONHR2 (In the formula, R□ and R2 represent a substituted or unsubstituted alkyl group having 10 to 30 carbon atoms, and R3 represents a divalent hydrocarbon group.) The divalent represented by R3 in the above general formula Examples of the hydrocarbon group include alkylene groups, divalent alicyclic groups such as cycloalkylene groups (e.g. cyclohexylene), arylene groups,
General formula -R4Ar R5- or -Ar -R6-Ar
Examples include divalent aromatic groups represented by - (wherein Ar represents an arylene group and R4, R5 and R6 represent lower alkylene groups).

Each of the preceding hydrocarbon groups may further have a substituent.

Specific examples of such urea compounds include R1゜R2
is C12H25 and R3 is -CH2-, bis(dodecylureido)methane, R1 and R2 are C15H4F and R3
is -CH2CH2-, 1,2-bis(pentadecylureido)ethane, R1, R2 force "C2o) R41
1,3-bis(eicosylureido)propane, s(octadecylureido)cyclohexane, R1゜cosylureido)benzene, where 3 is -CH2CH2CH2-,
R1, R2 are Cta Hj and R decylureidomethyl)benzene, R,, R2 are octadecylureidophenyl)methane, R1 and R2 are Ctal (v7 and R3 is -C
Examples include, but are not limited to, 1,6-(octadecylureido)hexane, which is H2(CH2)4CH2-.

The compound is coated on a support together with a leuco dye, a color developer, and the like. In this case, the coating liquid is usually an aqueous dispersion, but may be an organic solvent-based dispersion.

In the present invention, the leuco dyes used as components of the heat-sensitive coloring layer may be applied singly or in a mixture of two or more, but any leuco dye that has been applied to this type of heat-sensitive or pressure-sensitive recording material may be used. For example, triphenylmethane type, fluoran type, phenothiazine type, auramine type.

Leuco compounds of spiropyran-based dyes are preferably used. Specific examples of such leuco dyes include those shown below.

3.3-Bis(P-dimethylaminoenyl)-phthalide.

3.3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (also known as crystal violet lactone).

3.3-bis(p-dimethylaminophenyl)-6-dibutylaminophenyl, 3.3-bis(p-dimethylaminophenyl)-6-chlorophthalide, 3.3-bis(p-dibutylaminophenyl)phthalide, 3-cyclohexylamino-6-chlorofluorane, 3-dimethylamino-5,7-dimethylfluorane, 3
-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane, 3-diethylamino-6
-Methyl-7-chlorofluorane.

3-(N-p-hly-N-ethylamino)-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane.

2-(N-(3'-trifluoromethylphenyl)amino)-6-dinithylaminofluorane, 2-(3,
6-bis(diethylamino)-9-(o-chloroanilino)xantylbenzoic acid lactam), 3-diethylamino-6-methyl-7-(m-trichloromethylanilino)fluoran, 3-diethylamino-7-(o-chloranilino)・Rino) Fluoran, 3-dibutylamino-? -(o-chloroanilino)fluorane, 3-N-methyl-N-amylamino-6-methyl-7-
Anilinofluorane, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-(N,N- diethylamino)-5-methyl-7-(
N.

N-dibenzylamino)fluoran, benzoylleucomethylene blue, 6'-chloro-81-methoxy-benzoindolino-pyrylospirane.

6'-Bromo-3'-methoxy-benzoindolino-pyrylospirane.

3-(2'-Hydroxy-47-dibutylaminophenyl)-3-(2'-methoxy-51-chlorophenyl)phthalide.

3-(2'-Hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-5'-ditrophenyl)phthalide.

3-(2'-hydroxy-4'-diethylaminophenyl)-3-(2'-methoxy-5'-methylphenyl)phthalide.

3-(2'-methoxy-4'-dimethylaminophenyl)-3-(2'-hydroxy-4'-chloro-5'
-methylphenyl)phthalide.

3-morpholino-7-(N-propyl-trifluoromethylanilino)fluorane, 3-pyrrolidino-7-trifluoromethylanilinofluorane, 3-diethylamino-5-chloro-7-(N-benzyl-trifluoro methylanilino) fluorane.

3-pyrrolidino-7-(di-p-chlorophenyl)methylaminofluorane.

3-diethylamino-5-chloro-7-(α-phenylethylamino)fluorane, 3-diethylamino-6-methyl-7-chloropropylaminofluorane 3-(N-ethyl-p-toluidino)-7-(α -phenylethylamino)fluoran.

3-diethylamino-7-(o-methoxycarbonylphenylamino)fluoran, 3-diethylamino-5-methyl-7-(α-phenylethylamino)fluoran, 3-diethylamino-7-piperidinofluorane, 2-
Chloro-3-(N-methyltoluidino)-7-(p-n
-butylanilino)fluorane, 3-(N-benzyl-N-cyclohexylamino)-5
, 6-penzo 7-α-naphthylamino-4'-bromofluorane.

3-diethylamino-6-methyl-7-mesitidino 4
',5'-benzofluorane etc.

In the present invention, the color developer that reacts with the leuco dye to develop color when heated is a color developer.

Various electron-accepting substances are applied, including phenolic substances,
Examples include organic or inorganic acidic substances, metal salts thereof, and aromatic amide compounds, and specific examples thereof are shown below.

Clay, activated clay, activated silica, boric acid, zinc oxide, zinc chloride, aluminum chloride, 4,4'-isopropylidene bisphenol, 4,4'-isopropylidene bis-(0-cresol), 4,4'-isopropylene Redenbis (o-t, ert-butylphenol), 4.4
'-isopropylidene-bis(0-chlorophenol), 4,4'-cyclohexylidenebisphenol,
4.4'-bisphenolsulfone, 4-hydroxy-4'-chloro-diphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone, isopropyl p-hydroxybenzoate, isobutyl p-hydroxybenzoate, p-hydroxybenzoic acid Benzyl acid, P-chlorobenzyl p-hydroxybenzoate, salicylic acid anilide, salicylic acid (0-chloroanilide), salicylic acid (m-trifluoromethylanilide), dimethyl 4-hydroxyphthalate, 2-hydroxy-3-naphthoate Acid, 2-hydroxy-3-naphthoic acid anilide, 2-hydroxy-3-naphthoic acid zinc salt, zinc chloride/antipyrine complex, methylenebis-(oxyethylthio)phenol, 4-hydroxyacetophenone, novolak type phenolic resin, novolak type Phenylphenol resin etc.

In the present invention, in order to bind and support the leuco dye and color developer on the support, various commonly used binders can be used as appropriate. For example, polyvinyl alcohol, starch and its derivatives, methoxy cellulose, hydroxy Cellulose derivatives such as ethyl cellulose, carboxymethyl cellulose, methyl cellulose, and ethyl cellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylic amide/acrylic ester copolymer, acryl amide/acrylic ester/methacrylic acid ternary copolymer, styrene/ Maleic anhydride copolymer alkali salt, isobutylene/maleic anhydride copolymer alkali salt,
In addition to water-soluble polymers such as polyacrylamide, sodium alginate, gelatin, and casein, polyvinyl acetate, polyurethane, styrene/butadiene copolymer, polyacrylic acid, polyacrylic ester, vinyl chloride/vinyl acetate copolymer, and Latex such as butyl methacrylate, ethylene/vinyl acetate copolymer, styrene/butadiene/acrylic copolymer, etc. can be used.

Furthermore, in the present invention, in addition to the leuco dye and color developer, auxiliary additive components commonly used in this type of heat-sensitive recording material, such as fillers, surfactants, lubricants, etc., may be used in combination, if necessary. I can do it.

In this case, fillers include, for example, calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, and surface-treated inorganic fine powders such as calcium and silica. , urea-
Examples include organic fine powders such as formalin resin, starch, styrene/methacrylic acid copolymer, and polystyrene resin. Examples of lubricants include higher fatty acids or their esters, amides or metal salts, higher alcohols or their esters, higher aliphatic amines or amides animal and plant mineral waxes, synthetic waxes, 3,4-epoxy-
Examples include dialkyl hexahydrophthalate and higher ketones.

To produce the heat-sensitive recording material of the present invention, a coating liquid containing the compound of general formula (1), a leuco dye, a color developer, and a binder as main components is applied onto a support such as paper or synthetic paper. and dry it. Here, the amounts of the leuco dye, the color developer, and the heat-fusible substance of the present invention are 5 to 10% of the total weight of the heat-sensitive layer, respectively.
-30% by weight, 30-80% by weight, and 20-50% by weight are suitable.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples. Note that all parts and percentages shown below are based on weight.

Example 1 [Liquid A] 3-(N-methyl-N-cyclohexylamino)-6-
Methyl-7-anirite fluorane 10 parts 10% aqueous solution of hydroxyethyl cellulose 10 parts Water
30 [Liquid B] 4. 4'-isopropylidene bisphenol 30 parts hydroxyethimecellulose 10% aqueous solution 30 Water
90〃
[Liquid C] 1.3-bis(octadecylureidomethyl)benzene 30 parts Hydroxyethyl cellulose lO% aqueous solution 30 Water
90〃[D
Liquid] Calcium carbonate 30 parts Methyl cellulose 5% aqueous solution 30 parts Water
40 The above [Liquid A] to [Liquid D] were each dispersed in a ball mill and mixed in an equal ratio to obtain a heat-sensitive coating liquid.

Next, apply this coating liquid onto high-quality paper with a weight of 50 g/rd.
After coating and drying so that the dry adhesion amount was 5.0 g/rrr, the surface was smoothed to obtain a heat-sensitive recording paper. This was printed using a prototype facsimile printer with an applied energy of 0.
Color was developed at 5 mJ/dot. The results are shown in Table-1. We also examined the storage stability, plasticizer resistance (PVC), and fingerprint resistance of the obtained images, and the results are also shown in Table 1.
Shown below.

Example 2 An experiment was conducted in the same manner as in Example 1, except that the following [Liquid E] was used instead of [Liquid C].

[E liquid]

Bis(p-octadecylureidophenyl)methane
30 parts water
90 The results obtained in this case are shown in Table-1.

Comparative Example 1 An experiment was carried out in the same manner as in Example 1, except that the following [Liquid F] was used instead of [Liquid C].

[F liquid]

Stearic acid amide 30 parts Hydroxyethyl cellulose 10% water 1 part 30# water
90 The results obtained in this case are shown in Table-1.

Comparative Example 2 An experiment was conducted in the same manner as in Example 1 except that [liquid C] was omitted. The results in this case are shown in Table-1.

Table 1 [Effects] As can be seen from the above results, the heat-sensitive recording material of the present invention has improved thermal sensitivity, whiter background, and significantly improved image stability compared to conventional products.

Claims (1)

[Claims] (1) A heat-sensitive recording material characterized in that a heat-sensitive coloring layer containing a leuco dye and a color developer contains at least one compound represented by the following general formula. R_1NHCONHR_3NHCONHR_2 (in the formula,
R_1 and R_2 represent a substituted or unsubstituted alkyl group having 10 to 30 carbon atoms, and R_3 represents a divalent hydrocarbon group. )