JPH05294977A - Organosilicon compound and heat-sensitive recording material using the same - Google Patents

Abstract

PURPOSE:To provide the subject new compound capable of giving heat-sensitive recording materials excellent in picture image preservability. CONSTITUTION:The objective compound of formula I, which can be obtained by reducing a vat dye (e.g. indigo) through e.g. catalytic hydrogenation followed by reaction a whole day and night while stirring in the presence of a silylating agent (e.g. t-butyldimethylsilyl chloride) and triethylamine etc. The other objective heat-sensitive recording material is comprised of (A) the compound of the formula I, (B) another compound of formula II [Z is alkyl, aralkyl, H, etc.; where, the number of H atom is <=1; X is NR'' (R'' is H or alkyl), S or O; R and R' are each alkyl or halogen; Z' is the same as Z; m is 0-4; n is 0-4; where, when m is >=2, two R's may be mutually bound into a ring], and (C) an electron-accepting compound.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel organic silicon compound and a heat-sensitive recording material using the same, which is excellent in image storability.

[0002]

2. Description of the Related Art A heat-sensitive recording material generally comprises a support and a heat-sensitive recording layer containing an electron-donating, usually colorless or light-colored dye precursor and an electron-accepting developer as main components. By heating with a head, hot pen, laser light, etc.,
A dye precursor and a developer react instantaneously to obtain a recorded image. JP-B-43-4160 and JP-B-45-140.
No. 39, etc. Typical examples of dye precursors will be given here. 2-anilino 3-methyl-6-dibutylaminofluorane and 2-anilino 3-methyl-6-diethylaminofluorane are those that develop black color. Crystal violet lactone is a blue color. 2-Chloro-3-methyl-6-diethylaminofluorane is used as the red-colored one. Such heat-sensitive recording materials have the advantages that they can be recorded with a relatively simple device, are easy to maintain, and do not generate noise.Measurement recorders, facsimiles, printers, computer terminals, labels, etc. , Is used in a wide range of fields such as ticket vending machines. Particularly in the field of facsimiles, the demand for the heat-sensitive system has greatly increased, and along with this, there has been an attempt to increase the speed for reducing the transmission cost, downsize the device, and reduce the price. As a result, the amount of applied energy for image printing has been decreasing in recent years. Therefore, a high-sensitivity heat-sensitive recording material having a high thermal response capable of coping with speeding up and energy saving of such a facsimile has been developed.

However, in high-speed recording, minute thermal energy released from the thermal head in an extremely short time (usually 1 millisecond or less) is efficiently used for the color development reaction, while the image storability is deteriorated. Result. In order to solve this problem, many image preservations such as glycidyl compounds disclosed in JP-A-62-164579, phosphorus compounds disclosed in JP-A-62-90284, and hindered phenols disclosed in JP-A-62-35878. Improvers have been proposed. However, none of them has a problem that they are not suitable for the industrial production of thermal papers because of their insufficient storability improving effect or because of the safety of the compounds themselves and the difficulty of industrial production.
Therefore, thermal paper with satisfactory image storability could not be industrially manufactured so far.

In addition, since sensitizers are usually used in high-sensitivity papers for fax machines and the like, which also cause deterioration of image storability, they will be introduced below. For example, JP-A-57-64593 and JP-A-58-87094 disclose naphthol derivatives and JP-A-57-64592.
No. 57-185187 and 57-191.
089, JP-A-58-110289, JP-A-59-
The naphthoic acid derivative is disclosed in JP-A-58393 / 1983.
-72499, JP-A-58-87088, JP-A-58-87094 and British published patent 2165.
In 953 it is proposed to use ether and ester derivatives of phenolic compounds. The current high-sensitivity thermal papers are manufactured using these, but there is a limit to the improvement of storage stability by blending.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to obtain a heat sensitive recording material having excellent image storability.

[0006]

A thermosensitive recording material containing an electron-accepting compound (developing agent) which normally reacts with a colorless or light-colored dye precursor when heated to develop the dye precursor, By using the organosilicon compound represented by Chemical Formula 2 as a precursor, a heat-sensitive recording material excellent in image storability could be obtained.

In the chemical formula 2, Z represents an alkyl group, an aralkyl group, an aryl group or a hydrogen atom. The substituents represented by Z may be different from each other, but the number of hydrogen atoms is 1 or less. X represents NR ″, S or O. R ″ represents a hydrogen atom or an alkyl group. X may be different from each other. R and R'represent an alkyl group or a halogen atom.
Z ′ represents the same meaning as Z. m represents an integer of 0 or more and 4 or less. n represents an integer of 0 or more and 4 or less. When m is 2 or more, the substituents represented by R'may be different from each other, or two R's may combine to form a ring. n is 2
In the above cases, the substituents represented by R may be different from each other.

A specific example of the substituent represented by SiZ ₃ or SiZ ' ₃ in the general formula of Chemical formula 2 is a trimethylsilyl group,
Tertiary butyldimethylsilyl group, dimethylsilyl group, phenyldimethylsilyl group, phenylmethylsilyl group, benzyldimethylsilyl group, triethylsilyl group,
Examples include octadecyldimethylsilyl group and octyldimethylsilyl group. When the linking group represented by X is NR ″, specific examples of R ″ include a hydrogen atom, tertiary butyl,
Examples include methyl, isopropyl, ethyl and octyl.
Specific examples of R and R'include an alkyl group such as methyl, ethyl, butyl and octyl, and a halogen atom such as fluorine, chlorine and bromine. In addition to these cases, specific examples of the ring formed when two R's are bonded to each other include an aromatic ring such as a benzene ring, a pyridine ring and a pyrazine ring.

The compound represented by the chemical formula 2 can be easily synthesized by reducing a corresponding vat dye such as indigo and reacting it with a corresponding silylating agent in a known manner. The reducing conditions include a method using sodium dithionite and catalytic hydrogenation conditions. When the silylating agent generates an acid by the reaction, a base such as triethylamine or sodium hydroxide is used. Of the compounds of Chemical formula 2, the compound of Chemical formula 1 is novel. Examples of the compounds of the chemical formula 2 other than the chemical formula 1 are listed below.

[0010]

[Chemical 3]

[0011]

[Chemical 4]

[0012]

[Chemical 5]

[0013]

[Chemical 6]

[0014]

[Chemical 7]

[0015]

[Chemical 8]

[0016]

[Chemical 9]

[0017]

[Chemical 10]

[0018]

[Chemical 11]

[0019]

[Chemical 12]

[0020]

[Chemical 13]

Next, a specific method for producing the heat-sensitive recording material according to the present invention will be described. The heat-sensitive recording material according to the present invention generally comprises, on a support, an electron-donating, usually colorless or light-colored dye precursor and an electron-accepting compound as main components, and these are dispersed and coated in a binder to form a heat-sensitive recording layer. By heating with a thermal head, a heating pen, a laser beam or the like, a dye precursor and an electron-accepting compound react instantaneously to obtain a recorded image. JP-B-43-4160 and JP-B-45-
No. 14039 is disclosed. A pigment, a sensitizer, an anti-sticking agent and the like are added to the heat-sensitive recording layer as needed. An existing storability improver may be used in combination.

As the dye precursor used in the heat-sensitive recording material of the present invention, other than the dye precursor of the present invention, any dye generally used for pressure-sensitive recording paper or heat-sensitive recording paper can be used together without any particular limitation.

Specific examples are (1) triarylmethane compound 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (crystal violet lactone), 3,3-bis (p) -Dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl) -3-
(1,2-dimethylindol-3-yl) phthalide,
3- (p-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-phenylindole-
3-yl) phthalide, 3,3-bis (1,2-dimethylindol-3-yl) -5-dimethylaminophthalide, 3,3-bis (1,2-dimethylindole-3-)
Yl) -6-Dimethylaminophthalide, 3,3-bis (9-ethylcarbazol-3-yl) -5-dimethylaminophthalide, 3,3-bis (2-phenylindol-3-yl) -5 -Dimethylaminophthalide, 3-p
-Dimethylaminophenyl-3- (1-methylpyrrol-2-yl) -6-dimethylaminophthalide and the like,

(2) Diphenylmethane compound 4,4'-bis (dimethylaminophenyl) benzhydryl benzyl ether, N-chlorophenyl leuco auramine, N-2,4,5-trichlorophenyl leuco auramine, etc.

(3) Xanthene compound Rhodamine B anilinolactam, rhodamine B-p-chloroanilinolactam, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-7-octylaminofluorane, 3- Diethylamino-7-phenylfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-chloro-7-methylfluorane, 3-diethylamino-7- (3,4-dichloroanilino) fluorane, 3 -Diethylamino-7
-(2-chloroanilino) fluorane, 3-diethylamino-6-methyl-7-anilinofluorane (2-anilino-3-methyl-6-diethylaminofluorane),
3- (N-ethyl-N-tolyl) amino-6-methyl-
7-anilinofluorane, 3-piperidino-6-methyl-7-anilinofluorane, 3- (N-ethyl-N-tolyl) amino-6-methyl-7-phenethylfluorane, 3-diethylamino-7 -(4-nitroanilino)
Fluoran, 3-dibutylamino-6-methyl-7-anilinofluorane (2-anilino-3-methyl-6-dibutylaminofluorane), 3- (N-methyl-N-propyl) amino-6-methyl-7-ani Rinofluorane, 3- (N-ethyl-N-isoamyl) amino-6-
Methyl-7-anilinofluorane, 3- (N-methyl-
N-cyclohexyl) amino-6-methyl-7-anilinofluorane, 3- (N-ethyl-N-tetrahydrofuryl) amino-6-methyl-7-anilinofluorane, etc.

(4) Thiazine-based compound benzoyl leuco methylene blue, p-nitrobenzoyl leuco methylene blue, etc.

(5) Spiro compounds 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3,3'-dichlorospirodinaphthopyran, 3-benzylspirodinaphthopyran, 3-methylnaphtho- (3 -Methoxybenzo) spiropyran, 3-propylspirobenzopyran and the like can be mentioned, and these can be used alone or in combination of two or more.

The developer is not particularly limited as long as it is an acidic substance generally used for thermal paper. For example, a polyvalent metal salt such as a phenol derivative, an aromatic carboxylic acid derivative, an N, N'-diarylthiourea derivative, or a zinc salt of an organic compound can be used. Particularly preferred are phenol derivatives, specifically p-phenylphenol, p-hydroxyacetophenone and 4-hydroxy-.
4'-methyldiphenyl sulfone, 4-hydroxy-
4'-isopropoxydiphenyl sulfone, 4-hydroxy-4'-benzenesulfonyloxydiphenyl sulfone, 1,1-bis (p-hydroxyphenyl) propane, 1,1-bis (p-hydroxyphenyl) pentane, 1,1 -Bis (p-hydroxyphenyl) hexane, 1,1-bis (p-hydroxyphenyl) cyclohexane, 2,2-bis (p-hydroxyphenyl) propane, 2,2-bis (p-hydroxyphenyl) hexane, 1 , 1-bis (p-hydroxyphenyl) -2-ethylhexane, 2,2-bis (3-chloro-4-hydroxyphenyl) propane, 1,1-bis (p-hydroxyphenyl) -1-phenylethane, 1,3-di- [2
-(P-Hydroxyphenyl) -2-propyl] benzene, 1,3-di- [2- (3,4-dihydroxyphenyl) -2-propyl] benzene, 1,4-di- [2-
(P-Hydroxyphenyl) -2-propyl] benzene, 4,4'-dihydroxydiphenyl ether, 4,
4'-dihydroxydiphenyl sulfone, 3,3'-dichloro-4,4'-dihydroxydiphenyl sulfone,
3,3'-diallyl-4,4'-dihydroxydiphenyl sulfone, 3,3'-dichloro-4,4'-dihydroxydiphenyl sulfide, methyl 2,2-bis (4-hydroxyphenyl) acetate, 2,2- Butyl bis (4-hydroxyphenyl) acetate, 4,4'-thiobis (2-
t-butyl-5-methylphenol), benzyl p-hydroxybenzoate, chlorobenzyl p-hydroxybenzoate, dimethyl 4-hydroxyphthalate, benzyl gallate, stearyl gallate, salicylanilide, 5-chlorosalicylanilide and the like. is there. In addition to this, as a special case, salts containing fluorine ions also function as a developer regardless of whether or not they are acidic. Examples are various quaternary ammonium fluorides and the like.

As the binder used in the heat-sensitive recording material, starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, polyacrylic acid soda, acrylic acid amide / acrylic acid ester copolymer. , Acrylic acid amide / acrylic acid ester / methacrylic acid terpolymer, styrene / maleic anhydride copolymer alkali salt, ethylene /
Water-soluble adhesive such as alkali salt or ammonium salt of maleic anhydride copolymer, polyvinyl acetate, polyurethane,
Examples thereof include latex such as polyacrylic acid ester, styrene / butadiene copolymer, acrylonitrile / butadiene copolymer, methyl acrylate / butadiene copolymer, ethylene / vinyl acetate copolymer and the like.

Further, as a sensitizer for improving sensitivity, waxes such as N-hydroxymethylstearic acid amide, stearic acid amide and palmitic acid amide,
Naphthol derivatives such as 2-benzyloxynaphthalene,
Biphenyl derivatives such as p-benzylbiphenyl and 4-allyloxybiphenyl, 1,2-bis (3-methylphenoxy) ethane, 2,2'-bis (4-methoxyphenoxy) diethyl ether, bis (4-methoxyphenyl) A polyether compound such as ether, carbonic acid such as diphenyl carbonate, dibenzyl oxalate, oxalic acid bis (p-methylbenzyl) ester, or an oxalic acid diester derivative can be added in combination.

Examples of the pigment include diatomaceous earth, talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, titanium oxide, zinc oxide, silicon oxide, aluminum hydroxide and urea-formalin resin.

In addition, for the purpose of preventing head wear and sticking, higher fatty acid metal salts such as zinc stearate and calcium stearate, waxes such as paraffin, oxidized paraffin, polyethylene, oxidized polyethylene, stearic acid amide, and castor wax, , Dispersants such as sodium dioctyl sulfosuccinate, UV absorbers such as benzophenone-based and benzotriazole-based,
Furthermore, a surfactant, a fluorescent dye, etc. are added as needed.

Paper is mainly used as the support used in the present invention, but a non-woven fabric, a plastic film, a synthetic paper, a metal foil, or a composite sheet in which these are combined can be optionally used. In addition, an overcoat layer may be provided to protect the thermosensitive recording layer, or an undercoat layer composed of a single layer or a plurality of layers of pigments or resins may be provided between the thermosensitive recording layer and the support to produce a thermosensitive recording material. Various known techniques in the art can be used.

The smear amount of the heat-sensitive recording layer is determined by the amounts of the dye precursor which is a color-forming component and the color developer, and usually, the dye smear amount of 0.
1 to 1.0 g / m ² is suitable.

The amount of the developer is 5 with respect to the dye precursor.
~ 400% by weight, especially 50-300% by weight
Is the preferable addition amount. When a sensitizer is used, 100 to 300% by weight based on the color developer is a preferable addition amount.

[0036]

EXAMPLES Next, the present invention will be described in more detail by way of examples. All parts and% shown below are based on weight.

Example 1 Synthesis of Compound of Chemical Formula 1 Indigo (13.3 g), triethylamine (22.2 g) and tertiary butyldimethylsilyl chloride (18.1 g)
And 0.6 g of 5% palladium on activated carbon were added to N, N-dimethylformamide, and the mixture was placed under a hydrogen atmosphere and stirred overnight. Then, the system was poured into water and the crystalline precipitate was collected by filtration, washed with water, washed with acetone and dried to obtain 16 g of the desired product. The yield was 64%. This was recrystallized with hexane to obtain a pure product. The melting point was 185.9-187.6 degrees Celsius. Remarkable physical properties of this compound include its relatively high solubility in hydrocarbon solvents such as hexane and toluene, and the fact that it develops blue over time on a silica gel thin layer.

Example 2 Preparation of Thermosensitive Recording Material (A) Preparation of Thermosensitive Coating Liquid 30 parts of the compound of the chemical formula 1, which is a dye precursor, was pulverized together with 170 parts of 2.5% polyvinyl alcohol aqueous solution in a paint conditioner to obtain a dye dispersion liquid. Got Then 2,2-
90 parts of bis (p-hydroxyphenyl) propane 2.
It was pulverized with a paint conditioner together with 210 parts of a 5% polyvinyl alcohol aqueous solution to obtain a developer dispersion.

After mixing the above-mentioned two kinds of dispersion liquids, the following components were added with stirring and well mixed to prepare a heat-sensitive coating liquid. Calcium carbonate 50% dispersion 60 parts Zinc stearate 40% dispersion 25 parts 10% Polyvinyl alcohol aqueous solution 160 parts Water 280 parts

(B) Preparation of heat-sensitive coating paper A coating solution having the following composition is applied to a base paper having a basis weight of 40 g / m ^{2 so} as to have a solid content of 9 g / m ² , dried, and heat-sensitive coated. I made a paper. Calcined kaolin 100 parts Styrene-butadiene latex 50% aqueous dispersion 24 parts Water 200 parts

(C) Preparation of heat-sensitive recording material The heat-sensitive coating liquid prepared in (A) was smeared on the surface of the heat-sensitive coated paper prepared in (B) so that the solid content was 3 g / m ² . A thermosensitive recording material was prepared by drying.

Example 3 Instead of 2,2-bis (p-hydroxyphenyl) propane in Example 2, 3,3'-diallyl-4,4 'was used.
A thermal recording material was prepared in the same manner as in Example 2 except that dihydroxydiphenyl sulfone was used.

Comparative Example A thermosensitive recording material was prepared in the same manner as in Example 2 except that 2-anilino-3-methyl-6-dibutylaminofluorane was used in place of the compound of Chemical formula 1 in Example 2.

Evaluation The thermal recording papers obtained in Examples 2 and 3 and Comparative Example were calendered to have a Beck's smoothness of 400 to 500 seconds.

<Evaluation of image storability> A printing test was conducted using a facsimile tester TH-PMD manufactured by Okura Electric. Using a thermal head with a dot density of 8 dots / mm and a head resistance of 185Ω, head voltage 12V, pulse width 1.0
Power is supplied in milliseconds to print, and the optical density of the image is Macbeth R
It was measured with a D-918 reflection densitometer. Next, this image was processed under the condition of 60 ° C. for 24 hours, and the optical density of the processed image was measured. The images of Examples 2 and 3 were all blue, and the images of Comparative Examples were black.

When the optical density of the image portion after the processing is divided by that before the processing to obtain the image residual ratio, it is 100 in Examples 2 and 3.
The image residual rate was a satisfactory value of 100% or more. On the other hand, in the comparative example, a slight decrease of 85% was observed.
In the halftone image, the difference between Example 2 and the comparative example was further widened.

[0047]

As is clear from the examples, by using the compound of the present invention as a dye precursor, a heat-sensitive recording material excellent in image storability can be obtained.

Claims (2)

[Claims] 1. An organosilicon compound represented by the following chemical formula 1 2. A heat-sensitive recording material containing a normally colorless to light-colored dye precursor and an electron-accepting compound that reacts when heated to develop the color of the dye precursor, and the dye precursor is represented by the following chemical formula 2. A heat-sensitive recording material comprising an organic silicon compound. [Chemical 2] (However, Z represents an alkyl group, an aralkyl group, an aryl group or a hydrogen atom. The substituents represented by Z may be different from each other, but the number of hydrogen atoms is 1 or less. X is N
Represents R ″, S or O. R ″ represents a hydrogen atom or an alkyl group. X may be different from each other. R and R'represent an alkyl group or a halogen atom. Z ′ represents the same meaning as Z. m represents an integer of 0 or more and 4 or less. n represents an integer of 0 or more and 4 or less. When m is 2 or more, the substituents represented by R'may be different from each other, or two R's may combine to form a ring. When n is 2 or more, the substituents represented by R may be different from each other.