JPH04364987A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain excellent coloring sensitivity and reduce ground fog by adding at least 1 kind of dibasic acid diester compound to be expressed by a specific general formula in a thermal coloring layer as a sensitizer. CONSTITUTION:At least 1 kind of dibasic acid diester compound to be expressed by a formula I is included in a thermal coloring layer of a thermal recording material as a sensitizer. In the formula I, X represents bivalent aryl group, alkylene group or alkenylene group, A1 and A2 denote alkylene group with 2-4C, R<1> and R<2> denote alkyl group, alkenyl group, alkoxy group, nitro group or halogen, k, l, m respectively denote an integer of 0-3, and n is an integers of 1-3. This thermal recording material has high coloring density in thermal recording and high coloring sensitivity.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to heat-sensitive recording materials.

0002

[Prior Art] Conventional general heat-sensitive recording materials consist of a colorless or light-colored electron-donating dye precursor (hereinafter abbreviated as colorless dye) and an electron-accepting substance (hereinafter abbreviated as colorless dye) on a support such as paper or film. A two-component coloring system consisting of a coloring agent (abbreviated as a coloring agent) is further provided with a heat-sensitive coloring layer in which binders, sensitizers, lubricants, fillers and other auxiliaries are dispersed.
No. 0, Japanese Patent Publication No. 45-14039, etc.

[0003] This type of two-component color-forming heat-sensitive recording material allows a color image to be easily obtained by heating with a heating element (thermal head, thermal pen, etc.), and has the following advantages. (1). It is a primary color and does not require development or fixing. (2). There is no need to replenish toner, etc., and maintenance of the recording machine is easy. (3). The paper quality is similar to regular paper, so there is no discomfort. (4). High color density and clear images can be obtained. (5). By changing the type of colorless dye, different color tones can be easily obtained.

[0004] Due to these advantages, two-component heat-sensitive recording materials are most commonly used among heat-sensitive recording materials, and in recent years, their use has increased significantly in fields such as facsimiles, printers, measurement records, and labels. . With the recent increase in speed of facsimile communication, the recording speed is increasing, and thermal responsiveness has been strongly improved so that sufficient color density can be obtained with less thermal energy even on thermal recording paper. It is requested.

[0005] Research has been carried out on various coloring sensitivity improvers to improve thermal responsiveness, but improving thermal responsiveness tends to increase background fog, and both coloring sensitivity and background fogging tend to increase. At present, a heat-sensitive recording material that satisfies both of these requirements has not been obtained.

[0006]

[Problem to be solved by the invention] Conventional sensitizers (coloring sensitivity improvers) have the disadvantage of causing uneven printing and insufficient image reproducibility when printed using high-speed facsimiles or energy-saving facsimiles. . Furthermore, if a substance with a low melting point is mixed into the coloring layer, the coloring sensitivity can be improved, but there is a drawback that background fogging occurs.

[0007]

[Means for Solving the Problems] Therefore, an object of the present invention is to provide a heat-sensitive recording material that has high compatibility with colorless dyes, color developers, etc., has good color development sensitivity, and has little background fog. .

[0008] The present invention provides a thermosensitive coloring layer provided on a support with a thermosensitive coloring layer containing as main components a colorless or light-colored electron-donating dye precursor and an electron-accepting substance that develops color by reacting with the dye precursor. In the recording material, the following general formula is contained in the heat-sensitive coloring layer.

[Formula 2] (wherein, X represents a divalent aryl group, alkylene group, or alkenylene group, A1 and A2 represent an alkylene group having 2 to 4 carbon atoms, and R1 and R2 represent an alkyl group, an alkenyl group, or an alkoxyl group. group, nitro group or halogen, k, l and m are integers of 0 to 3, and n is an integer of 1 to 3) Contains at least one dibasic acid diester compound as a sensitizer. This is a heat-sensitive recording material characterized by:

In formula (I),

[Formula 3] is, for example, phthalic acid, isophthalic acid, terephthalic acid, 2
, 3-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, 1,8-naphthalene dicarboxylic acid or homophthalic acid residues, or oxalic acid,
Malonic acid, succinic acid, methylmalonic acid, ethylmalonic acid, glutaric acid, methylsuccinic acid, adipic acid, pimelic acid, methyladipic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid Alternatively, it is preferably a residue of an aliphatic dibasic acid such as glutaconic acid.

A1 and A2 are preferably, for example, an ethylene group, a propylene group, a butylene group, or an isobutylene group, and may be the same or different groups.

R1 and R2 are, for example, a halogen, a nitro group, an optionally branched alkyl group having 1 to 12 carbon atoms, an optionally branched alkenyl group having 2 to 12 carbon atoms,
An alkoxyl group having 1 to 4 carbon atoms is preferred, and the groups may be the same or different.

0012

[Operation] The reason why the compound of formula (I) according to the present invention exhibits a remarkable sensitizing effect when used as a sensitizer is considered to be as follows.

That is, not only the sensitizer itself according to the present invention has a high thermal melting rate, but also the thermal melting diffusion rate and saturation solubility of the colorless dye or color developer in the sensitizer. It is thought that the colorless dye and the color developer quickly form a color-forming composition using the colorless dye as a medium.

Representative examples of the compound of formula (I) are shown below, but the invention is not necessarily limited to these.

[C4]

[C5]

[C6]

[C7]

[Chemical formula 8]

[Chemical formula 9]

[Chemical formula 10]

[Chemical formula 11]

In addition, fatty acid amides such as stearic acid amide, stearic acid methylene bisamide, oleic acid amide, palmitic acid amide, and coconut fatty acid amide, as well as various known compounds, may be added to the extent that the desired effects of the present invention are not impaired. They can also be used together. The colorless dyes and color developers used in the present invention are not particularly limited as long as they are used in general pressure-sensitive recording materials, heat-sensitive recording materials, etc. Examples of colorless dyes include triarylmethane compounds and diphenylmethane compounds. , xanthene compounds, thiazine compounds, spiropyran compounds, etc. Examples of colorless dyes are shown below, but the invention is not limited thereto.

Some examples of colorless dyes include triarylmethane compounds such as 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (that is, crystal violet lactone), 3,3- Bis(p
-dimethylaminophenyl) phthalide, 3-(p-dimethylaminophenyl)-3-(1,3-dimethylindol-3-yl)phthalide, 3-(p-dimethylaminophenyl)-3-(2-methylindole) -3-yl)
phthalide, etc., and diphenylmethane compounds include 4,4'-bis-dimethylaminobenzhydrin benzyl ether, N-halophenyl-leucoolamine,
N-2,4,5-trichlorophenylleucoauramine, etc., and xanthene compounds include rhodamine-
B-anilinolactam, rhodamine (p-nitrino)lactam, 2-(dibenzylamino)fluoran, 2-phenylamino-6-diethylamino-fluoran, 2-
(o-chloroanilino)-6-diethylaminofluorane, 2-(3,4-dichloroanilino)-6-diethylaminofluorane, 2-anilino-3-methyl-6-piperidinofluorane, 2-phenyl-6- Diethylaminofluorane, 2-anilino-3-methyl-6-dimethylaminofluorane, 2-anilino-3-methyl-6-
N-Methyl-N-ethylaminofluorane, 2-anilino-3-methyl-6-N-methyl-N-(isopropyl)aminofluorane, 2-anilino-3-methyl-6-
N-Methyl-N-pentylaminofluorane, 2-anilino-3-methyl-6-N-methyl-N-cyclohexylaminofluorane, 2-anilino-3-methyl-6-
Diethylaminofluorane, 2-anilino-3-chloro-6-dimethylaminofluorane, 2-anilino-3-
Methyl-6-N-ethyl-N-isoamylaminofluorane, 2-anilino-3-methyl-6-N-methyl-N
-isoamylaminofluorane, 2-anilino-3-chloro-6-diethylaminofluorane, 2-anilino-
3-chloro-6-N-methyl-N-ethylaminofluorane, 2-anilino-3-chloro-6-N-methyl-N
-(isopropyl)aminofluorane, 2-anilino-
3-chloro-6-N-methyl-N-pentylaminofluorane, 2-anilino-3-chloro-6-N-methyl N
-cyclohexylaminofluorane, 2-anilino-3
-Methyl-6-N-ethyl-N-pentylaminofluorane, 2-anilino-3-chloro-6-N-ethyl-N
-pentylaminofluorane, 2-(p-methylanilino)-3-methyl-6-dimethylaminofluorane, 2
-(p-methylanilino)-3-methyl-6-diethylaminofluorane, 2-(p-methylanilino)-3-
Methyl-6-N-methyl-N-ethylaminofluorane, 2-(p-methylanilino)-3-methyl-6-N-
Methyl-N-(isopropyl)aminofluorane, 2-
(p-methylanilino)-3-methyl-6-N-methyl-N-pentylaminofluorane, 2-(p-methylanilino)-3-methyl-6-N-methyl-N-cyclohexylaminofluorane, 2- (p-methylanilino)
-3-Methyl-6-N-ethyl-N-pentylaminofluorane, 2-(p-methylanilino)-3-chloro-
6-dimethylaminofluorane, 2-(p-methylanilino)-3-chloro-6-diethylaminofluorane,
2-(p-methylanilino)-3-chloro-6-N-methyl-N-ethylaminofluorane, 2-(p-methylanilino)-3-chloro-6-N-methyl-N-(isopropyl)aminofluoran Orane, 2-(p-methylanilino)-3-chloro-6-N-methyl-N-cyclohexylaminofluorane, 2-(p-methylanilino)-3
-chloro-6-N-methyl-N-pentylaminofluorane, 2-(p-methylanilino)-3-chloro-6-
N-ethyl-N-pentylaminofluorane, 2-anilino-3-methyl-6-N-methyl-N-furylmethylaminofluorane, 2-anilino-3-ethyl-6-N
-Methyl-N-furylmethylaminofluorane, etc. Thiazine compounds include benzoloucomethylene blue, p-nitrobenzylleucomethylene blue, etc. Spiropyran compounds include 3-methyl-spiro-dinaphthopyran, 3- Ethyl-spiro-dinaphthopyran, 3,3'-dichloro-spiro-dinaphthopyran,
3-benzylspiro-dinaphthopyran, 3-methyl-naphtho-(3-methoxy-benzo)-spiropyran, 3-
Examples include propyl-spiro-dibenzopyran.

The content of the colorless dye in the heat-sensitive recording layer is preferably 0.2 to 1.0 g/m2.

[0018] As a color developer for coloring a colorless dye, an organic acidic substance that is solid at room temperature and melts under heat can be used. Examples include phenolic compounds, aromatic carboxylic acid compounds, and novolac type phenolic resins. Can be mentioned. Typical examples thereof include bisphenol derivatives, hydroxybenzoic acid esters, and salicylic acid esters. Additionally, inorganic acids such as clay, activated clay, activated silica, boric acid, and zinc oxide can also be used. The content of this color developer in the heat-sensitive recording layer is 0.2 to 4.0 g/
m2 is preferred.

Among these color developers, phenolic compounds and aromatic carboxylic acid compounds are particularly preferred, examples of which include 2,2-bis(4'-hydroxyphenyl)propane, 2,2-bis(4'- -hydroxyphenyl)pentane, 2,2-bis(4'-hydroxy-3',5'-
dichlorophenyl)propane, 1,1-bis(4'-hydroxyphenyl)cyclohexane, 2,2-bis(4
'-Hydroxyphenyl)hexane, 1,1-bis(4
'-Hydroxyphenyl)propyne, 1,1-bis(4
'-Hydroxyphenyl)butane, 1,1-bis(4'
-hydroxyphenyl)pentane, 1,1-bis(4'
-hydroxyphenyl)hexane, 1,1-bis(4'
-hydroxyphenyl)heptane, 1,1-bis(4'
-hydroxyphenyl)-2-methyl-pentane, 1,
1-bis(4'-hydroxyphenyl)-2-ethyl-
Hexane, 1,1-bis(4'-hydroxyphenyl)
Dodecane, 3,3-bis(4'-hydroxyphenyl)
Pentane, 1,2-bis(4'-hydroxyphenyl)
Ethane, 1,1-bis(4'-hydroxyphenyl)sulfide, 1,1-bis(3'-allyl-4'-hydroxyphenyl)sulfone, 1,1-bis(4'-hydroxyphenyl)sulfone, 4 -Hydroxy-4'-isopropoxydiphenylsulfone, 1,1-bis(4'
-hydroxyphenyl)ether, 2,2-bis(4'
-hydroxy-3',5'-dichlorophenyl)butane, phenyl 2,4-dihydroxybenzoate, phenyl 2,4-dihydroxy-4'-methyl-benzoate, 2,4
-dihydroxy-4'-phenyl chlorobenzoate, 2,
Phenyl 4-dihydroxy-6-methylbenzoate, 2,
Phenyl 4,6-trihydroxybenzoate, phenyl 2,4-dihydroxy-6,4'-dimethylbenzoate, 2
, phenyl 4-dihydroxy-6-methyl-4'-chlorobenzoate, benzyl 2,4-dihydroxybenzoate,
Benzyl 2,4-dihydroxy-4'-methylbenzoate, Benzyl 2,4-dihydroxy-4'-chlorobenzoate, Benzyl 2,4-dihydroxy-6-methylbenzoate, 2,4,6-trihydroxybenzoate benzyl acid, 2
, Benzyl 4-dihydroxy-6,4'-dimethylbenzoate, Benzyl 2,4-dihydroxy-6-methyl-4'-chlorobenzoate, 4-hydroxybenzoic acid ethyl ester, 4-hydroxybenzoic acid propyl ester, 4
-Hydroxybenzoic acid isopropyl ester, 4-hydroxybenzoic acid benzyl ester, 4-hydroxy-4
Examples include compounds such as benzyl '-chlorobenzoate, benzyl 4-hydroxy-4'-methylbenzoate, benzyl 4-hydroxy-4'-ethylbenzoate, but are not particularly limited to these. do not have.

Fillers are preferably used in the present invention. These fillers include inorganic white pigments such as calcium carbonate, clay, calcined clay, silica, zinc oxide, titanium oxide, talc, aluminum hydroxide, magnesium hydroxide, barium sulfate, and surface-treated silica, as well as starch, Examples include organic fine particles such as polystyrene resin and urea-formalin resin.

Binding agents for binding colorless dyes, color developers, white organic pigments, etc. on the support include polyvinyl alcohol and its derivatives, polyvinylpyrrolidone, starch and its derivatives, hydroxyethyl cellulose, ethyl cellulose, methyl cellulose. , cellulose derivatives such as carboxymethyl cellulose, styrene maleic anhydride copolymer alkali salts, isobutylene maleic anhydride copolymer alkali salts, polyacrylic acid alkali salts, alginate alkali salts, polyacrylamide, casein, gelatin, and other water-soluble polymers. In addition, various latexes such as styrene/butadiene copolymer, polyurethane, polyvinyl acetate, and polyacrylic acid can be used.

Furthermore, depending on the application, waxes such as paraffin wax, carnauba wax, polyethylene wax, and methylolstearamide, and lubricants such as zinc stearate and calcium stearate can be added to improve water resistance. In order to do this, a crosslinking agent or the like that crosslinks the binder may be added. For applications requiring good recording stability, it is preferable to incorporate a preservation improver such as a phenolic antioxidant.

[0023] The heat-sensitive paint produced using colorless dyes, color developers, pigments, binders and other auxiliary agents can be provided on a support by conventional methods such as a blade coater, an air knife coater, There are known methods such as roll coater and rod coater. Medications can be similarly adjusted using conventional methods.

Supports used in the present invention include paper,
Synthetic paper, plastic film, nonwoven fabric, resin-impregnated paper, etc. can be used. Further, in order to curl the product after coating, it is preferable to coat a water-soluble polymer, latex, etc. on one or both sides of the support. Furthermore, in order to improve coloring sensitivity and prevent dregs from adhering to thermal elements such as thermal heads, it is preferable to provide an intermediate layer containing the above-mentioned inorganic or organic filler between the support and the thermosensitive coloring layer. .

[0025]

EXAMPLES The present invention will now be explained in more detail with reference to examples.

Next, a formulation example of the dispersion liquid and data on color development sensitivity are shown. In addition, the number of blended parts indicates the number of parts by weight. [Liquid A] 3-n-dibutylamino-6-methyl-7-anilinofluorane 10 parts 10% modified polyvinyl alcohol
Part 10 Water


20 parts [Liquid B] 3-(N-ethyl-N-isoamyl)amino-6-
Methyl-7-ani linofluorane

10 copies 10%
Modified polyvinyl alcohol
10
Part water

20 parts [Liquid C] 3-(N-methyl-N-propyl)amino-6-methyl-7-anilinofluorane

10 parts 10
% modified polyvinyl alcohol
1
0 part water

20 parts [Liquid D] 3-di-n-butylamino-7-(2-chlorophenylamino)fluorane

10 copies
10% modified polyvinyl alcohol

Part 10 Water

20 copies [E
Liquid] 3-(N-cyclohexyl-N-methylamino)-
6-methyl-7-anilinofluorane

10 parts 10% modified polyvinyl alcohol
10 copies
water

20 parts [Liquid P] 1,1'-bis(p-hydroxyphenyl)propane (bisphenol A)

10 copies
10% modified polyvinyl alcohol

Part 10 Water

20 copies [Q
Liquid] 4-hydroxy-4'-isopropoxydiphenyl sulfone 10 parts 10% modified polyvinyl alcohol
10 copies
water

20 parts [R liquid] 4,4'-hydroxy-3,3'-allyl-diphenylsulfone 10 parts 10% modified polyvinyl alcohol
Part 10 Water


20 parts [Liquid X]

[Chemical formula 12]

10 parts 10% modified polyvinyl alcohol
Part 10 Water

20 copies

[0027] Each of the above liquids was processed using a sand grinder until the average particle size was 1 to 2 μm.
A dispersion liquid was prepared by performing wet dispersion until the dispersion amount reached m. As the modified polyvinyl alcohol, sulfonated PVA manufactured by Nippon Synthetic Chemical Industry Co., Ltd. (trade name: Goselan L-3266) was used. Leuco dye dispersions of A, B, C, D, E and P, Q
, R color developer dispersion, X sensitizer dispersion, and 30% calcium carbonate dispersion, respectively, 10 parts, 15 parts, 15 parts.
and 10 parts, and 10 parts of a 10% solution of completely saponified polyvinyl alcohol (average degree of polymerization of about 1,000) was added as a main binder to prepare a heat-sensitive paint. Calcium carbonate is Callite S manufactured by Shiraishi Kogyo.
A was used.

A high-quality paper of 45 g/m2 was used as the support, and the intermediate layer and the heat-sensitive paint each had a dry weight of 9.
-10 g/m2 and 4-5 g/m2 were applied to obtain heat-sensitive recording materials. For the aforementioned intermediate layer, an inorganic filler layer mainly composed of calcined clay is used, and the ratio of the inorganic filler to the binder is 10.
The ratio was 0:10 (dry weight ratio). Styrene-butadiene latex was used as the binder.

The dispersions A, B, C, D, E, P, Q, R, and X were combined to form Examples 1 to 7 as shown in Table 1.
Samples of Comparative Examples 1 to 5 were obtained. The dispersion liquid of X was not blended into the samples of Comparative Examples 1 to 5. These samples are supercalendar with Bekk smoothness of 400 ~
After adjusting the time to 600 seconds, the color development sensitivity was measured using a thermal head printing device manufactured by Okura Electric.

The color density was measured using a Macbeth densitometer (Mac
Using RD-514 (manufactured by Beth), the applied power was 0.4
The test was carried out using W/dot, pulse period of 4.0 ms, and thermal head resistance value of 1191 Ω, and the results shown in Table 1 were obtained as the level of color development sensitivity.

[0031] ◎...Particularly excellent. ×...Inferior.

As is clear from the results in Table 1, the heat-sensitive recording material of the present invention exhibited excellent color development sensitivity compared to the comparative example.

[0033]

As explained in detail above, the heat-sensitive recording material of the present invention has high color density and high color sensitivity during heat-sensitive recording, and is therefore extremely useful industrially.

Although the above embodiments have been described with reference to specific examples and numerical values of the present invention, it is of course possible to make various changes and modifications without departing from the broad spirit and scope of the present invention.

Claims (1)

[Claims] 1. A heat-sensitive recording material comprising a heat-sensitive color-forming layer on a support, the heat-sensitive coloring layer containing as main components a colorless or light-colored electron-donating dye precursor and an electron-accepting substance that develops color by reacting with the dye precursor. In the heat-sensitive coloring layer, the following general formula [
Chemical formula 1] (wherein, , represents a nitro group or a halogen, k, l and m represent an integer of 0 to 3, and n represents an integer of 1 to 3) as a sensitizer. A heat-sensitive recording material characterized by: