JPH0648036A - Thermosensitive recording medium - Google Patents

Abstract

PURPOSE:To provide a thermosensitive recording medium with a high sensitivity in which a recording layer containing a colorless or slightly colored basic dye and a color coupler is formed and which has a high processability for calendering conducted after the formation of the recording layer and hardly brings about residue sticking on a thermosensitive thermal head. CONSTITUTION:In a thermosensitive recording medium equipped with a recording layer containing a colorless or slightly colored basic dye and a color coupler, the recording layer contains paraffin wax and polyvinyl alcohol with a degree of polymerization of 800 or more and a saponification value of 90 or less in the amount of 5wt.% or more of its total solid content.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material, and more particularly to a high-sensitivity heat-sensitive recording material with less dust attached to a heat-sensitive head.

[0002]

2. Description of the Related Art A thermosensitive recording medium is known in which a color or color reaction between a colorless or pale basic dye and an organic or inorganic coloring agent is used to bring a recording image by contacting both coloring substances with heat. Has been. In recent years, recording speeds of devices such as facsimiles and printers using such thermal recording media have been rapidly increased. Therefore, the thermosensitive recording medium used is required to have higher sensitivity.

In order to increase the recording sensitivity of a thermosensitive recording medium, a sensitizing method is known in which a recording layer contains a heat-soluble substance which rapidly melts with a basic dye or a color developing agent in a certain temperature range. . However, a heat-soluble substance having a higher sensitizing effect is more likely to cause a recording failure due to dust attached to the thermal head during recording. When paraffin wax is further added to the recording layer as a heat-soluble substance in order to prevent the residue from adhering to the thermal head, it is possible to prevent the dust from being added during the super calendering process to enhance the recording sensitivity after forming the recording layer. There is a problem that dust is generated on the render roll and desired recording sensitivity cannot be obtained.

[0004]

DISCLOSURE OF THE INVENTION The object of the present invention is, in a thermal recording medium provided with a recording layer containing a colorless or light-colored basic dye and a coloring agent, suitability for super calendering performed after formation of the recording layer. The present invention provides a high-sensitivity heat-sensitive recording material which is excellent in heat resistance and has less dust attached to the heat-sensitive head.

[0005]

DISCLOSURE OF THE INVENTION The present inventors have proposed a thermosensitive recording medium having a recording layer containing a colorless or light-colored basic dye and a coloring agent on a support, and a paraffin in the recording layer. By containing wax and polyvinyl alcohol having a degree of polymerization of 800 or more and a degree of saponification of 90 or less with respect to the total solid amount in the recording layer in an amount of 5% by weight or more, the super calendering processability after the formation of the recording layer is improved. Excellent,
Moreover, they have found that a high-sensitivity heat-sensitive recording material with less dust attached to the heat-sensitive head can be obtained, and completed the present invention.

[0006]

In the combination of the paraffin wax and the specific polyvinyl alcohol used in the present invention, the melting point may be 40 ° C or higher, preferably 60 ° C or higher. The higher the melting point of the paraffin wax, the less dust adheres to the calender rolls during super calendering, which is performed to increase the recording sensitivity after the recording layer is formed. The recording sensitivity of the recording body is increased.

The amount of paraffin wax used in the recording layer is 5 to 200% by weight, preferably 10 to 100% by weight, based on the color-forming component consisting of the basic dye and the coloring agent.
Is. In addition to the paraffin wax, other waxes may be used in combination, and specific examples thereof include polyethylene wax, higher fatty acid amide, montan wax, carnavalox wax and the like.

In the present invention, polyvinyl alcohol having a degree of polymerization of 800 or more and a degree of saponification of 90 or less is used as an adhesive for the recording layer in an amount of 5% by weight or more based on the total solid amount in the recording layer. When the degree of polymerization of polyvinyl alcohol is less than 800, dust adheres to the thermal head due to insufficient adhesive strength during recording. If the degree of saponification exceeds 90 and the amount used is less than 5% by weight based on the total solid content in the recording layer, the adhesiveness to paraffin wax is significantly deteriorated. Dust adheres to the calendar roll during the calendar process. As a result, the smoothness of the surface of the recording layer is lowered, and the desired recording sensitivity cannot be obtained. The preferable amount of the specific polyvinyl alcohol used is in the range of about 8 to 15% by weight based on the total solid amount in the recording layer.

Specific examples of adhesives that can be used in combination with other than specific polyvinyl alcohol include, for example, oxidized starch, etherified starch, hydroxyethyl cellulose, carboxymethylcellulos, casein, silicon modified polyvinyl alcohol, acetoacetyl group modified polyvinyl alcohol, and carboxyl. Group-modified polyvinyl alcohol, styrene / maleic anhydride copolymer salt, ethylene / maleic anhydride copolymer salt, water-soluble silicone modified acrylic resin, styrene / butadiene copolymer emulsion, methyl acrylate / butadiene copolymer emulsion Etc.
Of course, it is not limited to these, and two or more kinds can be used in combination as required.

In the present invention, various types of basic dyes which are colorless or light-colored and constitute the recording layer of the thermosensitive recording medium are known, and the following are exemplified. 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) phthalide, 3- (4-dimethylaminophenyl)-
3- (4-diethylamino-2-methylphenyl) -6
-Dimethylaminophthalide, 3- (p-dimethylaminophenyl) -3- (1,2-dimethylindole-3-
Yl) phthalide, 3- (p-dimethylaminophenyl)
-3- (2-methylindol-3-yl) phthalide,
3,3-bis (1,2-dimethylindol-3-yl) -5-dimethylaminophthalide, 3,3-bis (1,2-dimethylindol-3-yl) -6-dimethylaminophthalide, 3,3-bis (9-ethylcarbazol-3-yl) -6-dimethylaminophthalide,
3,3-bis (2-phenylindol-3-yl)-
6-Dimethylaminophthalide, 3-p-dimethylaminophenyl-3- (1-methylpyrrol-3-yl) -6
-Triarylmethane dyes such as dimethylaminophthalide, 3,3-bis [1,1-bis (4-pyrrolidinophenyl) ethylene-2-yl] -4,5,6,7-tetrabromophthalide , 3,3-bis [1- (4-methoxyphenyl) -1- (4-dimethylaminophenyl) ethylene-2-yl] -4,5,6,7-tetrachlorophthalide, 3,3-bis [1- (4-methoxyphenyl) -1
-(4-Pyrrolidinophenyl) ethylene-2-yl]-
Divinylphthalide dyes such as 4,5,6,7-tetrachlorophthalide, 3-dimethylamino-7-methoxyfluorane, 3-diethylamino-6-methoxyfluorane, 3-diethylamino-7-methoxyfluorane Three
-Diethylamino-7-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-6,7-dimethylfluorane, 3- (N
-Ethyl-p-toluidino) -7-methylfluorane,
3-Dimethylamino-7- (N-acetyl-N-methylamino) fluorane, 3-diethylamino-7-N-methylaminofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-7-
(N-methyl-N-benzylamino) fluorane, 3-
Diethylamino-7- (N-chloroethyl-N-methylamino) fluorane, 3-diethylamino-7-diethylaminofluorane, 4-benzylamino-8-diethylamino-benzo [a] fluorane, 3- [4- (4-
Dimethylaminoanilino) anilino] -7-chloro-6
-Methylfluorane, 3- [4- (4-phenylanilino) anilino] -7-chloro-6-methylfluorane,
8- [4- (4-dimethylaminoanilino) anilino]
-Benzo [a] fluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7-phenylaminofluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7- (p -Toluidino) fluorane, 3-diethylamino-6-methyl-7-phenylaminofluorane, 3
-Di-n-butylamino-6-methyl-7-phenylaminofluorane, 3-di-n-pentylamino-6-methyl-7-phenylaminofluorane, 3-diethylamino-7- (2-carbomethoxy -Phenylamino) fluorane, 3- (N-ethyl-N-isoamylamino)
-6-Methyl-7-phenylaminofluorane, 3-
(N-cyclohexyl-N-methylamino) -6-methyl-7-phenylaminofluorane,

3-Pyrrolidino-6-methyl-7-phenylaminofluorane, 3-piperidino-6-methyl-7
-Phenylaminofluorane, 3-diethylamino-6
-Methyl-7-xylidinofluorane, 3-diethylamino-7- (o-chlorophenylamino) fluorane,
3-di-n-butylamino-7- (o-chlorophenylamino) fluorane, 3- (N-ethyl-N-tetrahydrofurfuryl) amino-6-methyl-7-phenylaminofluorane, 3- (N- Methyl-Nn-propylamino) -6-methyl-7-phenylaminofluorane, 3-pyrrolidino-6-methyl-7-p-butylphenylaminofluorane, 3- (N-methyl-Nn-) Propyl) amino-6-methyl-7-phenylaminofluorane, 3- (N-ethyl-N-isobutylamino)-
6-methyl-7-phenylaminofluorane, 3- (N
-Methyl-N-n-hexylamino) -6-methyl-7
-Phenylaminofluorane, 3- (N-ethyl-N-
n-hexylamino) -6-methyl-7-phenylaminofluorane, 3- (N-ethyl-N-cyclopentylamino) -6-methyl-7-phenylaminofluorane, 3- [N- (3-ethoxy) Propyl) -N-methylamino] -6-methyl-7-phenylaminofluorane, 3- [N-ethyl-N- (3-ethoxypropyl)
Amino] -6-methyl-7-phenylaminofluorane, 3-diethylamino-7- [m- (trifluoromethyl) phenylamino] fluorane, 3-diethylamino-7- (o-fluorophenylamino) fluorane,
3-di-n-butylamino-7- (o-fluorophenylamino) fluorane, 3-diethylamino-6-chloro-7-phenylaminofluorane, 3- (N-ethyl-N-isoamylamino) -7- Fluorane dyes such as (o-chlorophenylamino) fluorane and 3- (N-ethyl-Nn-hexylamino) -7- (o-chlorophenylamino) fluorane, 3,6-bis (dimethylamino) fluorene-9 -Spiro-3 '-(6'-dimethylamino) phthalide, 3-diethylamino-6- (N
-Allyl-N-methylamino) fluorene-9-spiro-3 '-(6'-dimethylamino) phthalide, 3,6-
Bis (dimethylamino) -spiro [fluorene-9,
6'-6'H-chromeno (4,3-b) indole],
3,6-bis (dimethylamino) -3'-methyl-spiro [fluorene-9,6'-6H-chromeno (4,3-
b) indole], 3,6-bis (diethylamino)-
3'-methyl-spiro [fluorene-9,6'-6H-
Chromene (4,3-b) indole] and the like. Of course, the dyes are not limited to these dyes, and two or more dyes may be used in combination as required.

Various materials are known as a colorant used in combination with the basic dye as described above, for example, activated clay, attapulgite, colloidal silica, inorganic acid substances such as aluminum silicate, 4,4'- Isopropylidene diphenol, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 4,4'-dihydroxydiphenyl sulfide, hydroquinone monobenzyl ether, benzyl 4-hydroxybenzoate, 4,4 '
-Dihydroxydiphenyl sulfone, 2,4'-dihydroxydiphenyl sulfone, 4-hydroxy-4'-isopropoxydiphenyl sulfone, bis (3-allyl-
4-hydroxyphenyl) sulfone, 4-hydroxy-
4'-methyldiphenyl sulfone, bis (4-hydroxyphenylthioethoxy) methane, 1,5-di (4-hydroxyphenylthio) -3-oxapentane, bis (p-hydroxyphenyl) butyl acetate, bis (p- Hydroxyphenyl) methyl acetate, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1,4-bis [α-methyl-α- (4′-hydroxyphenyl) ethyl] benzene, 1,3- Bis [α-methyl-α-
Phenolic compounds such as (4'-hydroxyphenyl) ethyl] benzene, di (4-hydroxy-3-methylphenyl) sulfin, 4- [2- (p-methoxyphenoxy) ethyloxy] salicylic acid, 4- {3- ( p-
Tolylsulfonyl) propyloxy] salicylic acid, 5-
Aromatic carboxylic acids such as [p- (2-p-methoxyphenoxyethoxy) cumyl] salicylic acid, and zinc, magnesium, aluminum of these aromatic carboxylic acids,
Examples thereof include salts with polyvalent metals such as calcium, titanium, manganese, tin and nickel, and organic acid substances such as antipyrine complex of zinc thiocyanate.

The use ratio of the basic dye and the color developing agent is not particularly limited, but generally 100 to 700% by weight, preferably 150 to 400% by weight with respect to the basic dye.
% By weight of coloring agent is used.

In the heat-sensitive recording material of the present invention, a recording sensitivity improving agent may be added to the recording layer for the purpose of obtaining high speed recording suitability. Examples of the recording sensitivity improving agent include the following compounds. Caproic acid amide, capric acid amide, palmitic acid amide, stearic acid amide, oleic acid amide, erucic acid amide, linoleic acid amide, linolenic acid amide, N-methylstearic acid amide, stearic acid anilide, N-methyloleic acid amide, Benzanilide, linoleic acid anilide, N-ethylcapric acid amide, N-butyllauric acid amide, N-
Octadecylacetamide, N-oleinacetamide, N-oleylbenzamide, N-stearylcyclohexylamide, polyethylene glycol, 1-benzyloxynaphthalene, 2-benzyloxynaphthalene,
1-Hydroxynaphthoic acid phenyl ester, 1,2-
Diphenoxyethane, 1,4-diphenoxybutane,
1,2-bis (3-methylphenoxy) ethane, 1,2
-Bis (4-methoxyphenoxy) ethane, 1-phenoxy-2- (4-chlorophenoxy) ethane, 1-phenoxy-2- (4-methoxyphenoxy) ethane, 1-
(2-Methylphenoxy) -2- (4-methoxyphenoxy) ethane, terephthalic acid dibenzyl ester, oxalic acid dibenzyl ester, oxalic acid di (4-methylbenzyl) ester, p-benzyloxybenzoic acid benzyl ester, p -Benzylbiphenyl, 1,5-bis (p
-Methoxyphenoxy) -3-oxa-pentane, 1,
4-bis (2-vinyloxyethoxy) benzene, p-
Biphenyl-p-tolyl ether, benzyl-p-methylthiophenyl ether, 2- (2'-hydroxy-
5'-methylphenyl) benzotriazole, 2-hydroxy-4-benzyloxybenzophenone and the like. In addition,
The amount of the recording sensitivity improver used is not particularly limited, but is generally 50 to 1000 relative to the basic dye.
It is desirable to adjust the content in the range of 100% by weight, preferably 100 to 500% by weight.

A coating liquid containing these is generally dispersed with water as a dispersion medium, together with or separately from a basic dye, a coloring agent, and the like by a stirring and crushing machine such as a ball mill, an attritor, a vertical type or a horizontal type sand mill. It is prepared, for example. Various auxiliaries can be added to the coating solution, for example, sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate / dispersant such as fatty acid metal salt, and other defoaming agents. , Fluorescent dyes, coloring dyes and the like.

Further, in order to improve the adhesion of dust to the recording head, it is possible to add an inorganic pigment such as kaolin, clay, talc, calcined clay, titanium oxide, diatomaceous earth, fine anhydrous silica, activated clay and the like. It is also possible to add a dispersion or emulsion of stearic acid, polyethylene, carnauba wax, zinc stearate, calcium stearate, ester wax or the like so that sticking does not occur due to contact with the recording head.

The method for forming the recording layer is not particularly limited, and the recording layer can be formed according to a conventionally known and commonly used technique. For example, the coating liquid for the recording layer is an air knife coater, a blade coater, a bar coater, or a gravure. It is formed by a method such as coating on a support using an appropriate coating device such as a coater or a curtain coater. Further, the coating amount is also not particularly limited, and is generally about 1 to 12 g / m ² , preferably ² to 10 g in dry weight.
It is adjusted in the range of about / m ² . As the support, paper,
A plastic film, synthetic paper or the like is appropriately selected and used. The present invention performs super calendering after forming the recording layer, and after super calendering,
Further, a protective layer may be provided on the recording layer for the purpose of protecting the recording layer, or an intermediate layer may be provided between the support and the recording layer. Further, various publicly known techniques in the field of heat-sensitive recording materials, such as a protective layer provided on the back surface of the support and an adhesive treatment on the back surface of the recording material, can be appropriately added.

[0018]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In the examples, parts and% are parts by weight and% by weight, respectively, unless otherwise specified. Example 1 Solution A Preparation 10 parts of 3-di-n-butylamino-6-methyl-7-phenylaminofluorane, 25 parts of 1,2-bis (3-methylphenoxy) ethane, 5 parts of a 5% aqueous solution of methylcellulose. , And 50 parts of water were pulverized with a horizontal sand mill until the average particle diameter became 1.0 μm. Solution B Preparation A composition consisting of 30 parts of 4-hydroxy-4′-isopropoxydiphenyl sulfone, 5 parts of a 5% aqueous solution of methylcellulose, and 55 parts of water was added to a horizontal sand mill until the average particle diameter became 1.5 μm. Crushed. Formation of Recording Layer Liquid A 90 parts, liquid B 80 parts, silicon oxide pigment (oil absorption: 18
0 ml / 100 g) 7 parts, magnesium carbonate 7 parts, saponification degree 88-polymerization degree 1000, polyvinyl alcohol [trade name: PVA-210, Kuraray Co., Ltd.] 10% aqueous solution 12
0 parts, 20 parts of paraffin wax 30% dispersion having a melting point of 68 ° C. [trade name: Hydrin D-337], 10 parts of 30% zinc stearate aqueous dispersion, and 10 parts of water are mixed and stirred to form a coating liquid. Obtained. After coating and drying as the coating amount after drying the resulting coating solution to the base paper 45 g / m ² is 3 g / m ^2,
Super calendering was performed to obtain a thermosensitive recording paper.

Example 2 In the formation of the recording layer of Example 1, polyvinyl alcohol having a saponification degree of 88 and a polymerization degree of 1000 [trade name: PVA-2
Instead of 120 parts of 10% aqueous solution of Kuraray Co., Ltd., 70 parts of 10% aqueous solution of polyvinyl alcohol [trade name: PVA-217, manufactured by Kuraray Co., Ltd.] having a saponification degree of 88-1700, and silicon-modified polyvinyl alcohol. Of 1
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 50 parts of a 0% aqueous solution was used.

Example 3 In the formation of the recording layer of Example 1, 20 parts of a 30% dispersion of paraffin wax having a melting point of 68 ° C. [trade name: Hydrin D-337], 30% aqueous dispersion of zinc stearate. A thermosensitive recording paper was obtained in the same manner as in Example 1 except that 30 parts of a 30% dispersion of paraffin wax having a melting point of 55 ° C. [trade name: Hydrin P-7] was used instead of 10 parts.

Example 4 In the formation of the recording layer of Example 1, a 30% dispersion of paraffin wax having a melting point of 68 ° C. [trade name: Hydrin D
337] 20 parts, 30 parts of 30% dispersion of zinc stearate in water, 30% dispersion of paraffin wax having a melting point of 75 ° C. [trade name: Hydrin E-139] 30
A thermal recording paper was obtained in the same manner as in Example 1 except that parts were used.

Comparative Example 1 In the formation of the recording layer of Example 1, polyvinyl alcohol having a saponification degree of 88 and a polymerization degree of 1000 [trade name: PVA-2
10, 120 parts of a 10% aqueous solution of Kuraray Co., Ltd. was used instead of 120 parts of a 10% aqueous solution of polyvinyl alcohol having a saponification degree of 99 and a polymerization degree of 1000 [trade name: PVA-110, manufactured by Kuraray Co., Ltd.]. A thermal recording paper was obtained in the same manner as in Example 1.

Comparative Example 2 In the formation of the recording layer of Example 1, polyvinyl alcohol having a saponification degree of 88 and a polymerization degree of 1100 [trade name: PVA-2
10, 120 parts of a 10% aqueous solution of Kuraray Co., Ltd. was replaced with 120 parts of a 10% aqueous solution of polyvinyl alcohol [trade name: PVA-205, manufactured by Kuraray Co., Ltd.] having a saponification degree of 88 and a polymerization degree of 500. A thermal recording paper was obtained in the same manner as in Example 1.

Comparative Example 3 In the formation of the recording layer of Example 1, polyvinyl alcohol having a saponification degree of 88 and a polymerization degree of 1000 [trade name: PVA-2
Instead of 120 parts of a 10% aqueous solution of Kuraray Co., Ltd., 30 parts of a 10% aqueous solution of polyvinyl alcohol [trade name: PVA-217, manufactured by Kuraray Co.] having a saponification degree of 88-1700 and a saponification degree of 99- A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 90 parts of a 10% aqueous solution of polyvinyl alcohol (trade name: PVA-110, manufactured by Kuraray Co., Ltd.) having a degree of polymerization of 1000 was used.

The seven types of thermal recording papers thus obtained were evaluated as follows, and the results are shown in Table 1. [Coloring property] Heat-sensitive evaluation machine [Product name: TH-PMD, manufactured by Okura Electric Co., Ltd.] Applied energy 0.17 mJ / dot, period 5.0 ms / li
Recording was carried out with ne, and the color density of the obtained image was measured with a Macbeth densitometer (Model RD-100R manufactured by Macbeth Co.).

[Debris Adhesion to Thermal Head] After recording five sheets of A4 size with a facsimile [Panafax 5E] manufactured by Matsushita Electric Co., the state of debris adhesion to the thermal head was visually judged. ◎ No debris adhered to the head. ○ 〃 Trace amount. △ 〃 Somewhat large.

[Suitability for Super-Calendar Processing] When the thermal recording medium after recording layer formation was subjected to a super-calendar processing, dust adhering to the calender roll was visually judged. ◎ No dust adheres to the super calender. ○ 〃 Trace amount. ○ ′ 〃 Small amount △ 〃 Somewhat large. × There are many.

[0028]

[Table 1]

[0029]

As is clear from the results of [Table 1], the thermosensitive recording medium according to the present invention is a high-sensitivity thermal recording medium which is excellent in super calendering processability and has less dust adhered to the thermal head. It was

Claims (2)

[Claims] 1. A thermosensitive recording medium comprising a support and a recording layer containing a colorless or light-colored basic dye and a coloring agent, wherein a paraffin wax and a degree of polymerization of 800 or more are saponified in the recording layer. A thermosensitive recording medium comprising polyvinyl alcohol having a degree of 90 or less in an amount of 5% by weight or more based on the total solid amount in the recording layer. 2. The thermosensitive recording medium according to claim 1, wherein the melting point of paraffin wax is 60 ° C. or higher.