JPS62158086A - Thermal recording material - Google Patents

Abstract

PURPOSE:To ensure a favorable printed density and enhance resistance to chemicals, oils and water, sticking resistance and blocking resistance, by providing a thermal recording layer, an intermediate layer and a protective layer, and incorporating a latex and colloidal silica into at least one intermediate layer. CONSTITUTION:A thermal recording layer comprises a dye precursor and a compound capable of performing a color reaction with the dye precursor, and a latex used in an intermediate layer is preferably a styrene-butadiene rubber latex or a vinylidene chloride latex. Colloidal silica is a colloidal solution obtained by dispersing ultrafine particles of silicic anhydride in water used as a dispersant, in which the particle diameter is preferably 10-100mmu, and the specific gravity is preferably 1.1-1.3. The colloidal solution has a pH of about 4-10, and is preferably used in an amount of 1-50wt% (as solid component) based on the amount of the latex. It is particularly preferable to use a cross-linking agent of a dialdehyde such as 4-dioxane in the intermediate layer in an amount of 1-10wt% based on the amount of polymers in the intermediate layer.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to a heat-sensitive recording material. The present invention relates to a heat-sensitive recording material that utilizes the color reaction of a compound (referred to as a chromatic compound).

(Prior art) So-called two-component heat-sensitive recording materials that utilize a color reaction between a colorless or light-colored electron-donating dye precursor and an electron-accepting compound are disclosed in Japanese Patent Publication No. Sho≠J-/4403 and Japanese Patent Publication No. Sho 413-≠
ltO issue, etc. Tokukaisho! It is disclosed in the 0rrt issue.

These two-component color-forming heat-sensitive recording materials are [F]-subordinate color-forming and do not require development; ■The paper quality is similar to that of ordinary paper; ■Easy to handle; ■High color density; ■Various color hues. It has the advantage that it can be easily made into a heat-sensitive recording material, and has great utility value. For this reason, it is most commonly used as a heat-sensitive recording material.

Particularly in recent years, its use has been remarkable not only in the field of facsimiles, recorders, and printers, but also in the field of labels such as PO8.

On the other hand, these heat-sensitive recording materials have the disadvantage that the reaction between the dye precursor and the color-developing compound occurs not only due to heat, but also due to solvents and the like during primary color development.

This is because all of these heat-sensitive recording materials are organic,
This is because they have high solubility in solvents, and therefore reactions occur in the solvents. Therefore, if it comes into contact with stationery containing solvents, such as water-based inks, oil-based inks, fluorescent pens, diazo developers, adhesives, or glues, the white background of the heat-sensitive recording material may develop color or the printed area may fade. This caused a significant loss in product value.

On the other hand, conventionally, on the heat-sensitive coloring layer,
No. 7110, JP-A No. 44R-301737, JP-A-Sho 1
Al-379! Efforts have been made to provide a solvent-resistant protective layer, as disclosed in No. R et al.

However, these methods may not have sufficient resistance to various chemicals, oil, and water, may reduce sensitivity, may have insufficient sticking properties, may cause blocking, or may have a complicated manufacturing process. However, it has disadvantages such as high cost, and overall, it cannot be said to be industrially sufficient.

(Objective of the present invention) The object of the present invention is to provide thermal recording paper which has good print density, resistance to various chemicals, oils, and water, stick/stick resistance, and blocking resistance, and which is industrially advantageous. It is to provide.

(Structure of the Invention) The object of the present invention is to provide a heat-sensitive recording material having a heat-sensitive layer, an intermediate layer, and a protective layer containing a colorless or light-colored dye precursor and a compound that develops a color by reacting with the dye precursor. This is achieved by including latex and colloidal silica in at least one intermediate layer.

The latexes used in the intermediate layer of the present invention include styrene-butadiene rubber latex, vinylidene chloride latex, acryl nitrile-butadiene rubber latex, methyl acrylate-butadiene rubber latex, and vinyl acetate emulsion. -Butadiene rubber latex and vinylidene chloride latex are preferred.

Colloidal silica is manufactured industrially, and Colloidal 7 Lika is a colloidal solution in which ultrafine particles of silicic anhydride are dispersed in water using water as a dispersion medium. The particle size is preferably io-ioomμ, a ratio of /, / to 3. The pH value of the colloidal solution in this case is Hiro ~
The one ranked 10th is preferably used. The amount used is preferably 7 to 30% by weight (solid content) of the latex, more preferably 10 to 30% by weight.

Polymers other than latex may be used in combination in the intermediate layer of the present invention. The amount used in combination is usually preferably 7 to 10% by weight (solid content) of the latex, and the more preferable t is! ~2!
Weight%.

Polymers used in combination in the intermediate layer of the present invention include methylcellulose, carboxymethylcellulose, hydroxymethylcellulose, starches, gelatin, gum arabic, casein, styrene-maleic anhydride copolymer hydrolyzate, styrene-maleic anhydride copolymer Hafestel hydrolyzate, isobutylene-maleic anhydride copolymer hydrolyzate, polyvinyl alcohol, silica-modified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, polyacrylamide derivative, polyvinylpyrrolidone,
Water-soluble polymers such as sodium polystyrene sulfonate and sodium alginate are used.

It is more preferable to use a crosslinking agent in the intermediate layer of the present invention.

Examples of crosslinking agents include polyamines such as polyethyleneimine, dialdehydes such as glutaraldehyde, polymethylol compounds such as methylolmelamine, epoxy compounds,
Ziruniram salts and other inorganic salts can generally be used. In the present invention, glutaralde, glyoxaldimethoxyurea, -23-dihydroxy-79
Particularly preferred are dialdehydes such as μm dioxane.

The amount added is a,/-13% by weight based on the polymer of the intermediate layer.
Preferably it is /-10% by weight.

Furthermore, if necessary, pigments other than colloidal silica, surfactants, etc. may be added to the intermediate layer of the present invention.

Examples of pigments used include zinc oxide, calcium carbonate, ζlium sulfate, titanium oxide, lithopone, talc, waxite, kaolin, aluminum hydroxide, silica, amorphous silica, and the like.

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

The amount of coating for the 7 intermediate layers is usually /~IO? In particular, λ~ot is preferable.

Examples of the colorless to light-colored dye precursor used in the heat-sensitive coloring layer of the present invention include triarylmethane compounds, diphenylmethane compounds, xanthine compounds, thiazine compounds, spiropyran compounds, and diazo compounds. A specific example is Tokukaisho! ! - Ko7ko! Examples include those listed in No. 3, etc. Some examples of these are triarylmethane compounds such as 3゜3-bis(p-dimethylaminophenyl)-4-dimethylaminophthalide (i.e. crystal violet lactone), 3,3-bis(p- Dimethylaminophenyl)phthalide% 3-(p-dimethylaminophenyl)-J
-(/,J-dimethylindol-3-yl)phthalide, 3-(p-dimethylaminophenyl)-J-(J-methylindol-3-yl)phthalide, etc., and diphenylmethane compounds include l , N-bis-dimethylaminobenzhydrin pendyl ether, N-halophenyl-leucoauramine, N-2.

j-)lichlorophenylleucoolamine, etc., and xanthine compounds include rhodamine-B-anilinolactam, a-damine(p-nitrino)lactam, j-
(dibenzylamino)fluorane, λ-phenylamino-6-ethylaminofluorane, 2-(o-chloroanili/)-4-diethylaminofluorane, 2-(
j, μm dichloroanilino)-6-diethylaminofluorane, coanilino-3-methyl-t-piperidinofluorane, -1-phenyl-diethylaminofluoran, etc., and spiro-based compounds include 3-methyl-spiro-dinaphthopyran. , 3-ethyl-spiro-dinaphthopyran, J,! '-dichlorospiro-dinaphthopyran, 3-benzylspiro-dinaphthopyran, 3-methyl-
naphtho-(3-methoxy-benzo)-spiropyran, 3
-propyl-spiro-dibenzopyran and the like. These can be used alone or in combination.

The diazo compound used in the present invention has the general formula A r N
It is a diazonium salt represented by 2" represents a substituted or unsubstituted aromatic moiety, N2+ represents a diazonium group, and X-
represents an acid anion. ) Specific examples of diazonium compounds that form salts include l
-Diazo-/-dimethylaminobenzene, μm diazo-
7-diethylaminobenzene, ≠-diazo/-dipropylaminobenzene, μm diazo-7-methylbenzylaminobenzene, ≠-diazo-no-dibenzylaminobenzene, goudiazo-l-ethylhydroxyethylaminebenzene, goudiazo-l-diethylamino- 3-methoxybenzene, Hiro-diazo-7-dimethylamino-2-
Methylbenzene, a-diazo-l-pensoylaminoco, j-jethoxybenzene, ≠-diazo/-morpholinobenzene, ≠-diazo-l-morpholinoco, j-
Shedogiabenzene, μ-diazo 7-morpholino,! -dibutoxybenzene, dark azo-l-anilinobenzene, μ-diazo/-,)ruylmercabutoe,! -jethoxybenzene, ≠-diazo-7, Hiro-methoxybenzoylamino-2,j-jethoxybenzene, and the like.

Specific examples of acid anions include CnF2n1+-1CO
O- (n represents 3 to ri), CmF2m+1lSC
l5-(J~Jrt-iwasu), <CAP, l +1
Examples include S(J, ) 2C) 1- (l represents 1 to /r), 0R BF -1PF, -, and the like.

The color developing compound used in the thermosensitive color forming layer of the present invention is as follows:
Compounds represented by the following general formulas (1) to CV) are preferred.

, l is an integer from O to 3, 0 and 2 are hydrogen or,
An alkyl group having a carbon number of l to r, or 几 and 几 2 bond to -
A cycloalkyl group consisting of C is valued. Also, R is the number of carbon atoms/-r
represents a straight-chain or branched alkyl group or a halogen atom. ) H (wherein, Y represents hydrogen, -C)13, -(Jl-1, Z Z has 7 to 6 carbon atoms)
represents a straight-chain or branched alkyl group, "s n
(wherein, R4 is a benzyl group, a halogen atom, or a carbon number/
Represents a benzyl group substituted with a straight chain or branched alkyl group of -r, or a straight chain or branched alkyl group of carbon number/-r. ) (In the formula, R6 and R7 represent an alkyl group having carbon number/~t.) (In the formula, "b" represents an alkylene group having 7 to 1 ether bond.) Above (I) to (V) Preferred examples other than the electron-accepting compounds represented by the formula include bis-hydroxycumylbenzene or bis-hydroxycumylbenzene, specific examples of which are l.

≠-bis-p-hydroxycumylbenzene, l.

μm bis-m-hydroxycumylbenzene, /.

3-bis-p-hydroxycumylbenzene, 7° 3-bis-m-hydroxycumylbenzene, l.

Gubis-〇-human axycumylbenzene,'l.

Examples include ≠-bis-p-hydroxy-α-methylbenzylbenzene, l,3-bis-p-hydroxy-α-methylbenzylbenzene, and salicylic acid derivatives include 3. ! -G α-1-p-h benzylsalicylic acid, 3
．． ! - tertiarybutylsalicylic acid, 3-α, α-
Salicylic acids such as dimethylbenzyl salicylic acid or their polyvalent metal salts (zinc and aluminum are preferred as percentages)
etc., p-phenylphenol, 3. !
- Phenols such as diphenylphenol and cumylphenol can be mentioned, but are not limited to these.

It is preferable to use the above-mentioned color developing compound in an amount of 70-1000% by weight of the dye precursor, more preferably 100-1000% by weight of the dye precursor.
400% by weight, and may be used alone or in combination of λ or more types.

When the dye precursor is a diazo compound, the coupling component is one that forms a dye by coupling with a diazo compound (diazonium salt) in a basic atmosphere, and specific examples include resorcin, phloroglucin, λ, 3 -jiζ
Sodium droxynaphthalene-t-sulfonate, l-
ζDroxy-2-naphthoic acid morpholinopropylamide, l.

S-dihydroxynaphthalene, co,3-dihydroxynaphthalene, λ, 3-dihydroxy≦-sulfanylnaphthalene, -monohydroxy-3-s7tanoic acid morpholinopropylamide, 2-dihydroxy-3-naphthoic acid anilide, -1 Hydroxy-3-naphthoic acid-λ'~methylanilide, 2-hydroxy-3-naphthoic acid ethanolamide, cohydroxy-3-naphthoic acid octylamide, -hydroquine-3-naphthoic acid-hetodecyl-oxypropylamide, 2 -Hydroxy-3-naphthoic acid tetradecylamide, acetanilide, acetoacetanilide, benzoylacetanilide, l-phenyl-3-methyl-! -pyrazolone, /-(,?',μ/
, J/-), lichlorophenyl)-3-benzamide-z-biranine, t+ (2/, Reference/, +/-)
(lichlorophenyl)-3-anilino-3-pyrazolone,
/-phenyl-3-phenylacetamide-! -Pyrazolone and the like. Furthermore, by using these coupling components together in amounts of λ or more, an image of any color tone can be obtained.

As the color development aid of the present invention, a poorly water-soluble or water-insoluble basic substance or a substance that generates an alkali when heated is used.

Color development aids include inorganic and organic ammonium salts, organic amines, amides, urea and thiourea and their derivatives, thiazoles, pyrroles, pyrimidines, piperazines,
Nitrogen-containing compounds such as guanidines, indoles, imidazoles, imidacillines, triazoles, morpholines, piperidines, amidines, 7-ormuazines, and pyridines are mentioned.

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.

Specifically, benzyl p-benzyloxybenzoate, β
-Naphthylbenzyl ether, niaric acid amide, palmimic acid amide, N-phenyl niaric acid amide, N-
Stearylurea, β-naphthoic acid phenyl ester, l
-Hydroxy-naphthoic acid phenyl ester, β-
Naphthol (p-chlorobenzyl) ether, β-su7
)-ru (p-methylbenzyl) ether, α-naphthylbenzyl ether, l9μm butanediol-p-methylphenyl ether, t,tI-fronononediol-p-methylphenyl ether, /,μ-phthanediol-p-isopropylphenyl Ether /, Gubuta /
Diol-pt-octylphenyl ether, 2-fe/-? /-p-tolyl-oxy-ethane, /-
Phenoxy--(Hiro-ethylphenoxy)ethane, /
-7 dinoxy 2-(μ-ethylphenoxy)ethane,
l-phenoxy-2-(4cm10lophenoxy)ethane, t, 4! -i tandiol phenyl ether and the like.

The thermofusible substance may be used alone or in combination, and in order to obtain sufficient thermal responsiveness, it is preferably used in an amount of 70 to 20% by weight based on the electron accepting compound. The preferred amount used is co-o-1zo weight percent. In two-component heat-sensitive recording materials using an electron-donating dye precursor and an electron-accepting compound, there is generally a tendency for the recorded images produced to fade due to external influences such as humidity and heat.

In the heat-sensitive recording material according to the present invention, it is preferable to include a compound that prevents color fading in the heat-sensitive color forming layer in order to prevent such color fading and to make the generated image more robust.

Phenol fused derivatives, particularly hindered phenol compounds, are effective as anti-fading agents.

The amount of the phenol compound to be used is preferably 1 l-2002 based on the electron-accepting compound, and more preferably 5 to 10% by weight.

Polymers used as adhesives for the heat-sensitive coloring layer of the present invention include polyvinyl alcohol, carboxy-modified polyvinyl alcohol, silica-modified polyvinyl alcohol, methylcellulose, carboxymethylcellulose, hydroxymethylcellulose, starches, gelatin, gum arabic, casein, styrene-maleic anhydride. Acid copolymer hydrolyzate, styrene-maleic anhydride copolymer Hafestel hydrolyzate, inbutylene-maleic anhydride copolymer hydrolyzate, polyacrylamide derivatives, polyvinylpyrrolidone, polystyrene sodium sulfonate, sodium alginate, etc. Water-soluble polymers and water-insoluble polymers such as styrene-butadiene rubber latex, acrylonidolyl-butadiene rubber latex, methyl acrylate-butadiene rubber latex, and acetic acid e-vinyl emulsion can be used together.

Pigment metal soap, wax, surfactant, etc. may be added to the heat-sensitive coloring layer of the present invention'D, if necessary.

As the pigment, zinc oxide, calcium carbonate, barium sulfate, titanium oxide, lithopone, talc, agate, kaolin, aluminum hydroxide, silica, amorphous silica, etc. are used.

As the metal soap, higher fatty acid metal salts are used, and emulsions of zinc stearate, calcium stearate, aluminum stearate, etc. are used.

As the wax, emulsions such as chisel rough-in wax, microcrystalline wax, carnauba wax, methylol stearamide, polyethylene wax, polystyrene wax, etc. are used.

As the surfactant, a sulfosuccinic acid-based alkali metal salt fluorine-containing surfactant or the like is used.

The crosslinking agent must be selected appropriately depending on the type of polymer, but examples include polyamines such as polyethyleneimine, dialdehydes such as glutaraldehyde, polymethylol compounds such as methyl melamine, epoxy compounds,
Ziruniram salts and other inorganic salts can generally be used. In the present invention, dialdehydes such as glutaraldehyde, glyoxal dimethoxyurea, and λ,3-dihydroxy-7 μm dioxane are particularly preferred.

The amount added is 0.00% relative to the polymer of the thermosensitive coloring layer. /~lj heavy t
H, preferably a weight value of 1 to 10.

The coating amount of the heat-sensitive coloring layer is preferably 7 to 10 f/m2.

Polymers used in the protective layer of the present invention include methylcellulose, carboxymethylcellulose, hydroxymethylcellulose, starches, gelatin, gum arabic, casein, styrene-maleic anhydride copolymer hydrolyzate, styrene-maleic anhydride copolymer Hafestel hydrolyzate, imbutylene-maleic anhydride copolymer hydrolyzate, polyvinyl alcohol, silica-modified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, polyacrylamide derivative, polyvinylpyrrolidone,
Water-soluble polymers such as sodium polystyrene sulfonate and sodium alginate, and water-insoluble polymers such as styrene-butadiene rubber latex, acrylonitrile-butadiene rubber latex, methyl acrylate-butadiene rubber latex, and vinyl acetate esters are used. .

These polymers may be used alone or in combination of two or more.

In the present invention, pigments, gold 4 soap, wax, crosslinking agents, etc. may be added to the protective layer for the purpose of improving the matching property with the thermal head during printing, improving the water resistance of the protective layer, etc.

The amount of the pigment added is preferably o, r to ≠ times the total weight of the polymer, particularly preferably o, r to 3.5 times. If the amount added is less than the above amount, it is ineffective in improving head matching properties, and if the amount added is more than the above amount, the sensitivity will be significantly lowered and the commercial value will be impaired. Pigments include zinc oxide, calcium carbonate,
Barium sulfate, titanium oxide, lithopone, talc, waxite, kaolin, aluminum hydroxide, silica, amorphous silica, colloidal 7-lica, and the like are used.

As the metal soap, higher fatty acid metal salt is used, and emulsions of zinc stearate, calcium stearate, aluminum stearate, etc. are used, and zinc stearate is particularly preferred. The amount added is 0.0% of the total weight of the protective layer.
A ratio of 1 to 20% is preferred, and a ratio of 7 to 70% is particularly preferred. As the wax, emulsions such as rough-in wax, microcrystalline wax, carnauba wax, methylol aeramide, stearic acid amide, polyethylene wax, polystyrene wax, etc. are used, and the amount added is 7 to 20% of the total weight of the protective layer. is preferred, and /-10 shima is particularly preferred.

Further, when coating the protective layer on the thermosensitive coloring layer, a surfactant may be added in order to obtain a uniform protective layer. As surfactants, sulfosuccinic acid alkali metal salts,
A fluorine-containing surfactant or the like is used. Specifically, di(coethylpequinyl)sulfosuccinic acid, di(n
-hexyl) sulfosuccinic acid, sodium salts such as skin, or ammonium salts, but most anionic surfactants are effective.

The coating amount of the protective layer is preferably o, r~IOf/m2, particularly preferably 7~! f/m2.

It would also be possible to provide an undercoat layer and a backcoat layer containing an adhesive (Examples of the Invention) Examples are shown below, but the invention is not limited thereto.

(Example 1) Crystal violet lactone, benzyl norahydroxybenzoate, stearamide, /.

/,! -tris(2-methylghydrox7-!-te
rt-butylphenyl)phthane was dispersed in a ball mill overnight with 700 f of 1% polyvinyl alcohol (10 t) aqueous solution to make the volume average particle size 3 μm or less. The pigment was prepared using rotary sodium hexametaphosphate. It was used after being dispersed with a homogenizer together with 1 tot of j'ir solution. Each dispersion prepared as above is called a crystal violet lactone dispersion! ? , benzyl parahydroxybenzoate dispersion g, IO2, stearamide dispersion! ? ,／,／,! -) Lis(2-methyl-μ
Hydroxy-1-tert-butylphenyl)butane dispersion 2f and pigment dispersion IP were mixed at a ratio of J/%.
Zinc stearate emulsion Jf and ≠ cleft 2,
3-dihydroxy-yo-methyl,/, hidioxane io
A coating liquid obtained by adding a di(2-ethylhexyl)-sulfocono sodium phosphate aqueous solution If of y and xs,
.

The mixture was coated on 17 m2 of high-quality paper using a wire bar so that the dry coating amount was 397 m2, and dried in a TO'C oven to obtain a heat-sensitive coloring layer.

Apply the mixed coating liquid shown below on the heat-sensitive coloring layer obtained by the above method to a dry weight of ≠? /m2 using a wire bar and turning in a to'c oven to obtain an intermediate layer.

On the intermediate layer obtained by the above method, the mixed coating liquid shown below was applied with a wire bar to a dry weight of J97m, and dried in a to 0c oven to obtain a protective layer.

(Example 1) 1t using polyvinylidene chloride instead of 88R latex! In Example 1, heated recording paper was obtained in exactly the same manner as in Example 1.

(Example 3) A thermosensitive recording paper was obtained in exactly the same manner as in Example 3, except that polyvinyl alcohol was not used.

(Example μ) λ,3-dihydroxy! -Thermosensitive recording paper was obtained in exactly the same manner as in Example 1, except that methyl 1 and μ dioxane were not used.

(Comparative Example 1) In Example 1, a thermosensitive recording paper was obtained without providing an intermediate layer.

(Comparative Example 2) A thermal recording paper was obtained in exactly the same manner as in Example except that colloidal silica was not used.

(Comparative Example 3) SBR, polyvinyl alcohol (instead of latex)
A thermosensitive recording paper was obtained in exactly the same manner as in Example 1, except that PVA//7) was used.

(Comparative Example μ) Oxidized starch (manufactured by Nikshoku Co., Ltd.) was used instead of SBR latex.
A thermosensitive recording paper was obtained in exactly the same manner as in Example 1 using MSJroo.

The heat-sensitive recording papers obtained in Examples 1 and 1 and Comparative Examples 3 and 3 were colored using a label printer 'I'EC-HyAo& (manufactured by Tokyo Electric Corporation) to examine their resistance to water, oil, and chemicals.

There was no improvement in either sticking property or blocking resistance.

Claims (1)

[Claims] Usually, in a heat-sensitive recording material that has a heat-sensitive layer containing a colorless or light-colored dye precursor and a compound that develops color by reacting with the dye precursor, an intermediate layer, and a protective layer, at least one intermediate layer contains latex and colloidal silica. A heat-sensitive recording material characterized by containing