JP2003175671A - Heat-sensitive recording material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-sensitive recording material which has water- resistant blocking property, is excellent in curl balance, of which the sensitivity is favorable, and of which printing property for the rear surface is favorable as well. <P>SOLUTION: On a supporting body, a heat-sensitive coloring layer containing an electron donative dye precursor which is normally colorless or slightly tinted, and a color developer which is an electron accepting compound is provided for this heat-sensitive recording material. Then, the heat-sensitive recording material has a back coat layer on the rear surface. In this case, the Gurley air permeability of the heat-sensitive recording material is set to be 300 seconds or lower. Also, the back coat layer contains (A) an inorganic or organic pigment of which the particulate diameter is 0.1 to 5 μm and (B) an adhesive by a mass blending ratio (A)/(B) in a range of 5/10 to 50/10. Also, the back coat layer contains (A) the inorganic or organic pigment of which the particulate diameter is 0.1 to 5 μm and (C) a water dispersing latex of Tg-30°C or higher by a mass blending ratio (A)/(C) in a range of 5/10 to 50/10. <P>COPYRIGHT: (C)2003,JPO

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 effective for tickets, labels and the like. More specifically, it is excellent in blocking resistance after being wet with water, so-called water blocking resistance, and has a curl balance. And a heat-sensitive recording material having good sensitivity and good printability on the back surface.

[0002]

2. Description of the Related Art In general, a heat-sensitive recording material is provided with a heat-sensitive recording layer containing, on a support, an electron-donating, usually colorless or light-colored dye precursor, and a developer which is an electron-accepting compound as main components. By heating with a thermal head, a heating pen, a laser beam or the like, a dye precursor and a developer react instantaneously to obtain a recorded image. JP-B-43-416
No. 0, 45-14039 and the like. Such a heat-sensitive recording material has the advantages that recording can be obtained with a relatively simple device, that maintenance is easy, and that noise is not generated.Measurement recorders, facsimiles, printers, computer terminals, It is used in a wide range of fields such as labels and ticket vending machines.

Particularly in recent years, in addition to financial recording sheets such as receipts of gas, water, electricity, etc., ATM usage statements of financial institutions, various receipts, etc., ticket sheets such as entrance tickets and voting tickets are also available. Thermal recording materials have come to be used.

As the applications and demands of heat-sensitive recording materials have expanded to a wide variety as described above, high thermal response which is a basic characteristic,
In addition to requiring a sufficient color density, when used for tickets, etc., there is no deterioration of the recorded image even when exposed to wind and rain or when it becomes wet with sweat, etc. in preparation for outdoor use. Needless to say, even after contacting the ticket surfaces with each other in such a wet state, the tickets may stick to each other,
There has been a demand for a thermal recording material having a so-called water-proof blocking property, which is a paper on which recorded information cannot be read.

Further, when used for a ticket application or the like, since the heat-sensitive recording material processed into a winding shape is cut into a certain size and issued as a ticket, it is necessary that curling does not occur in the transportation route at the time of issuing the ticket. Is. In addition, after a lapse of time, often refunds are made with automatic refund machines,
It is desirable to suppress curling to the extent that jamming does not occur in the transport path such as a refund machine even after long-term exposure to a humidity change that normally occurs. Further, in the case of ticket use, there is a possibility that a caution note may be printed on the back side, in which case it is necessary to give printability to the back side, curl balance is good, and a thermal recording material with printability is desired. There is.

As a heat-sensitive recording material imparted with water resistance, the use of N, N'-diarylthiourea derivative as a developer in JP-A-59-190893 does not cause discoloration by water. A heat-sensitive recording material having excellent water-immersion recolorability is disclosed. Also, JP-A-60-245591
The publication discloses a heat-sensitive recording material in which a protective layer contains a water-soluble polymer containing an acetoacetyl group to impart water resistance to a coating film and prevent discoloration during immersion in water. However, these heat-sensitive recording materials all suppress deterioration of the image when the recorded image is flooded.

Further, Japanese Patent Laid-Open No. 11-208108 discloses a heat-sensitive recording material which has good printability and does not peel off in water resistance by defining the dry adhesion amount of the protective layer, the pigment content, and the ratio of the water-proofing agent. However, water-resistant peeling is a problem that occurs during printing, and is not sufficient to satisfy the water-resistant blocking condition that is the object of the present invention.

Further, Japanese Patent Laid-Open No. 2001-27719 discloses a heat-sensitive recording sheet in which the problems of sticking and peeling of the coating layer due to contact with water are improved, and the water-resistant blocking property between heat-sensitive recording surfaces is Although it is described that it greatly improves, in the intended use of the present invention, the recording materials are often used by being overlapped with each other, and not only the recording surface but also the waterproof resistance when the back surface and the recording surface overlap. It is important and not enough to meet that requirement.

[0009]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned problems, that is, a heat-sensitive recording material having excellent water blocking resistance, good curl balance, and good sensitivity and printability on the back surface. To provide the material.

[0010]

As a result of intensive studies, the inventors of the present invention have invented a heat-sensitive recording material having excellent water blocking resistance, good curl balance, and good sensitivity and printability on the back surface. Came to. That is, on a support, a thermosensitive coloring layer containing an electron-donating normally colorless or pale color dye precursor, and a developer that is an electron-accepting compound is provided, and in a thermosensitive recording material having a backcoat layer on the back surface, The thermal recording material is characterized in that the Gurley air permeability of the thermal recording material is 300 seconds or less.

The back coat layer contains (A) an inorganic or organic pigment having a particle size of 0.1 to 5 μm and (B) an adhesive, and the mass mixing ratio (A) / (B) is 5/10 to 50. / 1
The heat-sensitive recording material is characterized in that it is contained in the range of 0.

A heat-sensitive recording material is characterized in that the adhesive is a water-dispersible latex having a Tg of -30 ° C or higher.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The thermal recording material of the present invention will be described in detail below. The heat-sensitive recording material of the present invention comprises, on a support, an electron-donating usually colorless or pale color dye precursor,
And a thermosensitive coloring layer containing a color developer which is an electron-accepting compound, and a back coat layer on the back surface.

The Gurley air permeability in the present invention is defined by JIS
-Measure based on P-8117.

Paper is mainly used as the support in the present invention. Base paper is bleached softwood kraft pulp (NBKP), bleached hardwood kraft pulp (LBK)
P), softwood bleached sulfite pulp (NBSP), hardwood bleached sulfite pulp (LBSP), cotton pulp, and other cellulose fibers are used.

Further, as the internal addition size of the pulp slurry,
The addition of a sulfuric acid band, a cationic polymer, an anionic polymer or the like as a fixing agent such as rosin, alkyl ketene dimer or petroleum resin can suppress the permeation of the aqueous coating liquid into the base paper. Further, as the surface size, a sizing agent can be applied by a size press or the like to manufacture the same. It is also possible to add a wet paper strengthening agent to suppress a decrease in interfiber bonding when wet. In addition, as a filler, raw materials such as calcium carbonate, clay, talc, silica, kaolin, calcined kaolin, zinc oxide, magnesium silicate, synthetic pulp, dye, antistatic agent and the like can be used as required.

In the support used in the present invention, it is necessary to control the air permeability so that the Gurley air permeability of the heat sensitive recording material is 300 seconds or less after the heat sensitive recording layer and the back coat layer are provided. When a coating layer is applied to the support, the air permeability often decreases. Therefore, the Gurley air permeability of the support is preferably 300 seconds or less,
It is more preferable that the time is not more than seconds.

It is important that the Gurley air permeability of the heat-sensitive recording material of the present invention is 300 seconds or less. If the Gurley air permeability is longer than 300 seconds, it becomes difficult for water or steam to pass when the front and back surfaces are combined and loaded after dropping water. Swell the coating layer on the surface of, and promote the sticking of the front and back.

In order to obtain the heat-sensitive recording material of the present invention, it is necessary to give sufficient consideration to the coating liquid used for coating the back coat layer. If an adhesive having a high barrier property is used for the back coat layer, air permeability will decrease. However, even if an adhesive having a high barrier property is used, it is possible to obtain the heat-sensitive recording material of the present invention by controlling the addition rate of the inorganic or organic pigment and imparting suitable air permeability.

The pigment for the back coat layer has a particle size of 0.
Organic or inorganic pigments of 1-5 μm are used. When a pigment having a particle size of less than 0.1 μm is used, it is insufficient to improve the air permeability of the coating film of the back coat layer,
When a pigment having a size larger than μm is used, the smoothness of the coating layer is significantly reduced, and when used for printing or the like, problems such as insufficient printing density cannot be obtained.

Specific examples of the pigment used in the back coat layer include diatomaceous earth, talc, kaolin, calcined kaolin,
Heavy calcium carbonate, precipitated calcium carbonate, magnesium carbonate, zinc oxide, aluminum oxide, aluminum hydroxide, magnesium hydroxide, titanium dioxide, barium sulfate, zinc sulfate, amorphous silica, amorphous calcium silicate, aluminum silicate compound Inorganic pigments such as colloidal silica, melamine resin fillers, urea-formalin resin fillers, polyethylene powders, polypropylene powders, nylon powders, polymethylmethacrylate powders, and other organic pigments can be used. Among them, it is preferable to use amorphous silica.

Examples of the adhesive for the back coat layer include starches, hydroxymethyl cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, sodium alginate, polyvinylpyrrolidone, polyacrylamide, acrylamide / acrylic acid. Ester copolymer, acrylamide / acrylic acid ester / methacrylic acid terpolymer, alkali salt of polyacrylic acid, alkali salt of polymaleic acid, alkali salt of styrene / maleic anhydride copolymer, ethylene /
Alkali salt of maleic anhydride copolymer, isobutylene /
Water-soluble resin such as alkali salt of maleic anhydride copolymer,
And styrene / butadiene copolymer, acrylonitrile / butadiene copolymer, methyl acrylate / butadiene copolymer, acrylonitrile / butadiene / styrene terpolymer, polyvinyl acetate, vinyl acetate / acrylic ester copolymer, ethylene / Vinyl acetate copolymer,
Examples of the water-dispersible resin include polyacrylic acid ester, styrene / acrylic acid ester copolymer, and polyurethane.

Above all, a water-dispersible resin having a Tg of -30 ° C or higher is desirable. When a water-dispersible resin or water-soluble resin having a temperature lower than Tg-30 ° C is used, a dense coating film is likely to be formed, and as a result, the air permeability of the resulting heat-sensitive recording material is low.

The ratio of the pigment to the adhesive in the back coat layer is a mass blending ratio of pigment / adhesive = 5/10 to 50.
/ 10. When the amount of the pigment is less than 5/10, the air permeability is lowered and the water blocking resistance cannot be obtained. Also, 5
When the amount of the pigment is more than 0/10, the smoothness of the coating layer is significantly reduced, and when used for printing or the like, problems such as insufficient printing density cannot be obtained.

The coating amount of the back coat layer is 0.
5 to 3.0 g / m ² is suitable. If the amount is less than 0.5 g / m ² , sufficient curl straightening cannot be performed, and 3.0
Even if it exceeds g / m ² , there is a cost disadvantage.

The electron-donating, usually colorless or light-colored dye precursor constituting the heat-sensitive recording layer of the heat-sensitive recording material of the present invention is generally a pressure-sensitive recording material or a dye precursor used in the heat-sensitive recording material. Although it is represented, it is not particularly limited.

Specific examples of dye precursors include (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-phenylindol-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) -5-dimethylaminophthalide,
3,3-bis (2-phenylindol-3-yl)-
5-dimethylaminophthalide, 3-p-dimethylaminophenyl-3- (1-methylpyrrol-2-yl) -6
-Dimethylaminophthalide, etc.

(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-dibutylamino-7-
(2-chloroanilino) fluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 3-
Dipentylamino-6-methyl-7-anilinofluorane, 3- (N-ethyl-N-tolyl) amino-6-methyl-7-anilinofluorane, 3-piperidino-6-methyl-7-anilino Fluoran, 3- (N-ethyl-N
-Tolyl) amino-6-methyl-7-phenethylfluorane, 3-diethylamino-7- (4-nitroanilino) fluorane, 3- (N-methyl-N-propyl) amino-6-methyl-7-anilinoflu Oran, 3- (N
-Ethyl-N-isoamyl) amino-6-methyl-7-
Anilinofluorane, 3- (N-methyl-N-cyclohexyl) amino-6-methyl-7-anilinofluorane, 3- (N-ethyl-N-tetrahydrofurfuryl)
Amino-6-methyl-7-anilinofluorane, 3-diethylamini-6-methyl-7- (3-trifluoromethylanilino) fluorane, and the like,

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

(5) Spiro compounds: 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran,
Examples thereof include 3,3′-dichlorospirodinaphthopyran, 3-benzylspirodinaphthopyran, 3-methylnaphtho- (3-methoxybenzo) spiropyran, and 3-propylspirobenzopyran. Further, these dye precursors can be used as a mixture of two or more kinds, if necessary.

The electron-accepting compound for coloring the dye precursor constituting the heat-sensitive recording layer of the heat-sensitive recording material of the present invention is generally represented by a pressure-sensitive recording material or an electron-accepting compound used in the heat-sensitive recording material. However, it is not particularly limited. For example, clay substances, phenol derivatives, aromatic carboxylic acids and their derivatives, urea derivatives such as N, N′-diarylthiourea and N-sulfonylurea, and polyvalent metal salts thereof can be used.

Specific examples include clay such as acid clay, activated clay, zeolite, bentonite, kaolin, p-phenylphenol, p-hydroxyacetophenone, 4-hydroxy-4'-methyldiphenyl sulfone, 4-hydroxy. -4'-isopropoxydiphenyl sulfone, 4-hydroxy-4'-n-propoxydiphenyl sulfone, 3-phenylsulfonyl-4-hydroxydiphenyl sulfone, 4-hydroxy-4'-benzenesulfonyloxydiphenyl sulfone, 1,1-
Bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) pentane, 1,1-bis (4-hydroxyphenyl) hexane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1, 1-
Bis (4-hydroxyphenyl) cyclododecane, 2,
2-bis (4-hydroxyphenyl) propane, 2,2
-Bis (4-hydroxyphenyl) hexane, 2,2-
Bis (4-hydroxyphenyl) octane, 1,1-bis (4-hydroxyphenyl) -2-ethylhexane,
2,2-bis (3-chloro-4-hydroxyphenyl)
Propane, 1,1-bis (4-hydroxyphenyl)-
1-phenylethane, 1,3-di- [2- (4-hydroxyphenyl) -2-propyl] benzene, 1,3-di- [2- (3,4-dihydroxyphenyl) -2-propyl] benzene , 1,4-di- [2- (4-hydroxyphenyl) -2-propyl] benzene, 4,4'-dihydroxydiphenyl ether, N- (2-hydroxyphenyl) benzenesulfonamide, N- (2-hydroxyphenyl) ) -P-toluenesulfonamide, N- (4
-Hydroxyphenyl) benzenesulfonamide, N-
(4-hydroxyphenyl) -p-toluenesulfonamide, N- (p-toluenesulfonyl) -N '-(3-
p-toluenesulfonyloxyphenyl) urea, 4,
4'-dihydroxydiphenyl sulfone, 2,4'-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-bis (4- Hydroxyphenyl) butyl acetate, 4,4'-thiobis (2-t-butyl-5-methylphenol), benzyl p-hydroxybenzoate, chlorobenzyl p-hydroxybenzoate, 4
-Dimethyl hydroxyphthalate, benzyl gallate, stearyl gallate, salicylanilide, 5-chlorosalicylanilide, novolac phenol resin, modified terpene phenol resin, 3,5-di-t-butylsalicylic acid, 3,5-di-t -Nonylsalicylic acid, 3,5-didodecylsalicylic acid, 3-methyl-5-t-dodecylsalicylic acid, 5-cyclohexylsalicylic acid, 3,5-bis (α, α-dimethylbenzyl) salicylic acid, 3-methyl-5- ( α-methylbenzyl) salicylic acid, 4-n-
Octyloxycarbonylamino salicylic acid, 4- {2
Examples thereof include-(4-methoxyphenoxy) ethoxy} salicylic acid and their metal salts such as zinc, nickel, aluminum and calcium, but the electron-accepting compound according to the present invention is not limited thereto. ,
If necessary, two or more kinds can be used in combination.

The heat-sensitive recording layer constituting the heat-sensitive recording material of the present invention may contain a heat-fusible substance in order to improve its thermal response. In this case, 60 ℃ ~ 180
Those having a melting point of ℃ are preferred, especially 80 ℃ ~ 140 ℃
Those having a melting point of are more preferably used.

Specific examples include stearic acid amide, N-hydroxymethylstearic acid amide, N-stearyl stearic acid amide, ethylenebisstearic acid amide, N-stearyl urea, benzyl-2-naphthyl ether, and m-tertiary. Phenyl, 4-benzylbiphenyl, 2,2'-bis (4-methoxyphenoxy) diethyl ether, α, α'-diphenoxyxylene, bis (4-methoxyphenyl) ether, diphenyl adipate, dibenzyl oxalate, oxalic acid Di (4-chlorobenzyl) ester, dimethyl terephthalate, dibenzyl terephthalate, phenyl benzene sulfonate,
Bis (4-allyloxyphenyl) sulfone, 1,2-
Known heat-fusible substances such as di (3-methylphenoxy) ethane, 1,2-diphenoxyethane, 4-acetylacetophenone, acetoacetic acid anilides, fatty acid anilides and the like can be mentioned. These compounds may be used alone or in combination of two or more. Further, in order to obtain sufficient thermal response, it is preferable that the heat-fusible substance accounts for 5 to 50% by weight in the total solid content of the thermosensitive recording layer.

In the heat-sensitive recording layer constituting the heat-sensitive recording material of the present invention, each aqueous dispersion obtained by finely pulverizing each color-forming component is mixed with an adhesive, and the mixture is coated on a support and dried. Is obtained by The thermal recording layer may have a single layer structure or a multilayer structure.

As the adhesive used for the heat-sensitive recording layer,
Various adhesives used in ordinary coating can be used.

Specific examples include starches, hydroxymethylcellulose, methylcellulose, ethylcellulose, carboxymethylcellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, sodium alginate, polyvinylpyrrolidone, polyacrylamide, acrylamide / acrylic acid ester copolymerization. Of acrylamide / acrylic acid ester / methacrylic acid terpolymer, alkali salt of polyacrylic acid, alkali salt of polymaleic acid, alkali salt of styrene / maleic anhydride copolymer, ethylene / maleic anhydride copolymer Water-soluble adhesives such as alkali salts, alkali salts of isobutylene / maleic anhydride copolymer, and styrene /
Butadiene copolymer, acrylonitrile / butadiene copolymer, methyl acrylate / butadiene copolymer, acrylonitrile / butadiene / styrene terpolymer, polyvinyl acetate, vinyl acetate / acrylic acid ester copolymer, ethylene / vinyl acetate Examples thereof include water-dispersible adhesives such as copolymers, polyacrylic acid esters, styrene / acrylic acid ester copolymers and polyurethanes, but are not limited thereto.

In the heat-sensitive recording layer, as a pigment, diatomaceous earth, talc, kaolin, calcined kaolin, ground calcium carbonate, precipitated calcium carbonate, magnesium carbonate, zinc oxide, aluminum oxide, aluminum hydroxide, magnesium hydroxide, titanium dioxide. , Barium sulfate, zinc sulfate,
Inorganic pigments such as amorphous silica, amorphous calcium silicate and colloidal silica, and organic pigments such as melamine resin filler, urea-formalin resin filler, polyethylene powder and nylon powder can be used.

Further, the heat-sensitive recording layer has a head wear prevention layer,
For the purpose of preventing sticking, zinc stearate,
Higher fatty acid metal salts such as calcium stearate, higher fatty acid amides such as stearic acid amide, lubricants such as paraffin, polyethylene wax, polyethylene oxide, and cut wax, and anionic and nonionic high molecular weight substances are included as dispersing / wetting agents. Surfactants, fluorescent dyes, defoaming agents and the like are added as necessary.

The coating amount of the heat-sensitive recording layer is usually 0.1 to 2.0 g / m ^{2 in} terms of the coating amount of the dye precursor. 0.1 g / m ²
If the amount is smaller than the above, a sufficient recorded image cannot be obtained,
Further, even if it exceeds 2.0 g / m ² , the thermal responsiveness is not improved, which is disadvantageous in cost.

As long as the Gurley air permeability of the heat-sensitive recording material of the present invention does not exceed 300 seconds, a single layer or a plurality of layers of pigments or adhesives are optionally provided between the support and the heat-sensitive recording layer. One or more undercoat layers can be provided. When the heat-sensitive recording material of the present invention is provided with an undercoat layer, the coating amount of the undercoat layer is 1 to 30 g /
m ² is preferable, and 3 to 20 g / m ² is more preferable.

As the pigment or adhesive used in the undercoat layer, various pigments and adhesives used in ordinary coating can be used. Specific examples thereof include the same as those used for the heat-sensitive recording layer.
Examples of the auxiliary agent contained in the coating liquid for the undercoat layer include known surfactants, coloring dyes, fluorescent dyes, lubricants, ultraviolet absorbers and the like.

As long as the Gurley air permeability of the heat-sensitive recording material of the present invention does not exceed 300 seconds, the heat-sensitive recording layer is formed on the heat-sensitive recording layer in order to further improve the chemical resistance of the recording portion or the recording running property. Can be provided with a protective layer. Such a protective layer is mainly composed of a water-soluble resin or a water-dispersible resin having a film-forming property, and an ultraviolet absorber and an auxiliary agent which can be added to the heat-sensitive recording layer if necessary while the adhesive is dissolved or dispersed. such a protective layer coating solution prepared by adding to a heat-sensitive recording layer on the coating amount after drying of 0.2 to 10 g / m ^2, more preferably so as to be 0.5 to 5 g / m ² approximately It is formed by coating and drying.

The water-soluble resin or water-dispersible resin for the protective layer is appropriately selected from conventionally known water-soluble polymers or water-dispersible resins. That is, as the water-soluble resin, for example, polyvinyl alcohol, modified polyvinyl alcohol, starch or a derivative thereof, cellulose derivative such as hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, polyvinylpyrrolidone, polyacrylamide, acrylamide /
Acrylic ester copolymer, acrylamide / acrylic acid ester / methacrylic acid terpolymer, alkali salt of polyacrylic acid, alkali salt of polymaleic acid, alkali salt of styrene / maleic anhydride copolymer, ethylene /
Alkali salt of maleic anhydride copolymer, isobutylene /
An alkali salt of a maleic anhydride copolymer, sodium alginate, gelatin, casein, and an acid neutralized product of chitosan can be used.

Examples of water-dispersible resins include styrene / butadiene copolymers, acrylonitrile / butadiene copolymers, methyl acrylate / butadiene copolymers, acrylonitrile / butadiene / styrene terpolymers,
Polyvinyl acetate, vinyl acetate / acrylic acid ester copolymer, ethylene / vinyl acetate copolymer, polyacrylic acid ester, styrene / acrylic acid ester copolymer, polyurethane and the like can be used.

Further, the protective layer may contain a pigment for the purpose of improving recording runnability, writability and the like. Specific examples of the pigment include diatomaceous earth, talc, kaolin, calcined kaolin, ground calcium carbonate, precipitated calcium carbonate, magnesium carbonate, zinc oxide, aluminum oxide, aluminum hydroxide, magnesium hydroxide, titanium dioxide, barium sulfate, and sulfuric acid. Inorganic pigments such as zinc, amorphous silica, amorphous calcium silicate, aluminum silicate compound, colloidal silica, melamine resin filler, urea-formalin resin filler, polyethylene powder,
Organic pigments such as nylon powder can be used.

Further, the protective layer has a higher fatty acid metal salt such as zinc stearate and calcium stearate, a higher fatty acid amide such as stearic acid amide, paraffin and polyethylene for the purpose of improving recording runnability such as prevention of head wear and sticking. Lubricants such as wax, polyethylene oxide, and cut wax are added as needed.

The method for forming the heat-sensitive recording layer, the protective layer, or the undercoat layer is not particularly limited, and the heat-sensitive recording layer, the protective layer or the undercoat layer can be formed according to a conventionally known technique. Specific examples include air knife coating, rod blade coating, bar coating,
A coating solution can be applied by a method such as blade coating, gravure coating, curtain coating, and E bar coating, and dried to form a heat-sensitive recording layer, protective layer or undercoat layer.

Further, planographic printing, letterpress printing, flexo printing, gravure printing,
Each layer may be formed by various printing machines such as a screen and a hot melt method.

If necessary, after the undercoat layer is coated, the heat-sensitive recording layer is coated, or the protective layer is coated, a super calendar treatment may be performed to improve the image quality.

Further, in the heat-sensitive recording material of the present invention,
If necessary, the back surface can be an arbitrary information recording layer such as an inkjet recording layer.

[0053]

The present invention will be described in more detail with reference to the following examples. However, it is not limited to these. In addition,
Parts and% in each example are based on mass,
The coating amount is an absolutely dry coating amount.

<1> Preparation of Dispersion Liquids Dispersion Liquids A, B, C, D and Dispersion Liquid 1 were prepared by the following method.
~ 4 were prepared.

(Dispersion A) 200 g of 3-dibutylamino-6-methyl-7-anilinofluorane is dispersed in a mixture of 200 g of a 10% aqueous solution of polyvinyl alcohol and 600 g of water, and the average particle diameter is 1 μm with a bead mill. Crushed until.

(Dispersion B) 400 g of 2-hydroxy-4'-isopropoxydiphenyl sulfone was dispersed in a mixture of 400 g of a 10% aqueous polyvinyl alcohol solution and 200 g of water, and the mixture was pulverized with a bead mill until the average particle diameter became 1 μm.

(Dispersion C) 400 g of benzyl-2-naphthyl ether was added to 40% of a 10% aqueous solution of polyvinyl alcohol.
The mixture was dispersed in a mixture of 0 g and 200 g of water, and pulverized with a bead mill until the average particle size became 1 μm.

(Dispersion D) 200 g of calcium carbonate was mixed with 800 g of 0.5% sodium polyacrylate aqueous solution and dispersed for 10 minutes with a homomixer.

<2> Preparation of heat-sensitive coated paper An undercoat layer-forming coating liquid having the following composition was added to a basis weight of 80 g /
A heat-sensitive coated paper was prepared by coating a high-quality paper having a Gurley air permeability of 80 seconds of m ² to a solid content of 10 g / m ² and drying. Calcined Kaolin 100 parts 50% Styrene-butadiene latex 24 parts Water 200 parts

Example 1 <3> Preparation of Thermosensitive Recording Layer Using the dispersions A to D, the respective materials were mixed in the proportions shown below, and added water was added so that the coating solution concentration became a 15% aqueous solution. In addition, it was sufficiently stirred to prepare a coating liquid for the heat-sensitive recording layer. Dispersion A 20 parts Dispersion B 15 parts Dispersion C 15 parts Dispersion D 25 parts 10% Polyvinyl alcohol 30 parts Water 30 parts

The heat-sensitive recording paper prepared in <2> was coated with the heat-sensitive recording layer coating solution thus prepared in an amount of 3.0 g.
It was coated so as to be / m ² and dried to form a thermosensitive recording paper.

<4> Preparation of Backcoat Layer A coating solution for forming a backcoat having the following composition was prepared in <3>.
Coating amount 1.0g / m ² on the back side of the thermal recording paper
Coating, drying, and treatment with a super calendar to obtain the heat-sensitive recording material of Example 1. Styrene-butadiene-based water-dispersible resin (Tg-15 ° C) 10 parts Amorphous silica (Mizukasil P527 made by Mizusawa Chemical Co., Ltd., particle size 1.7 μm) 10 parts Water 180 parts

Example 2 A thermosensitive recording material was obtained in the same manner as in Example 1 except that the compounding ratio of the coating liquid for the back coat layer in Example 1 was changed to the compounding ratio shown below. Acrylonitrile-butadiene-based water-dispersible resin (Tg -31 ° C) 10 parts Amorphous silica (Mizukasil P527 manufactured by Mizusawa Chemical Co., Ltd.) 10 parts Water 180 parts

Example 3 A thermosensitive recording material was obtained in the same manner as in Example 1 except that the compounding ratio of the coating liquid for the back coat layer in Example 1 was changed to the compounding ratio shown below. Acrylonitrile-butadiene-based water-dispersible resin (Tg -27 ° C) 10 parts Amorphous silica (Mizukasil P527 manufactured by Mizusawa Chemical Co., Ltd.) 10 parts Water 180 parts

Example 4 A thermosensitive recording material was obtained in the same manner as in Example 1 except that the compounding ratio of the coating liquid for the back coat layer in Example 1 was changed to the following compounding ratio. Phosphoric esterified starch 10 parts Amorphous silica (Mizukasil P527 manufactured by Mizusawa Chemical Co., Ltd.) 10 parts Water 180 parts

Example 5 A thermal recording material was obtained in the same manner as in Example 1 except that the compounding ratio of the coating liquid for the back coat layer in Example 1 was changed to the following compounding ratio. Acrylic water-dispersible resin (Tg 98 ° C) 10 parts Colloidal silica (Snowtex ST-XL manufactured by Nissan Chemical) 4 parts Water 126 parts

Example 6 A thermosensitive recording material was obtained in the same manner as in Example 1 except that the compounding ratio of the coating liquid for the back coat layer in Example 1 was changed to the compounding ratio shown below. Acrylic water-dispersible resin (Tg 98 ° C) 10 parts Colloidal silica (Nissan Chemical's Snowtex ST-XL) 10 parts Water 180 parts

Example 7 A thermosensitive recording material was obtained in the same manner as in Example 1 except that the compounding ratio of the coating liquid for the back coat layer in Example 1 was changed to the compounding ratio shown below. Acrylic water-dispersible resin (Tg 98 ° C) 10 parts Colloidal silica (Nissan Chemical's Snowtex ST-XL) 60 parts Water 630 parts

Example 8 A thermosensitive recording material was obtained in the same manner as in Example 1 except that the compounding ratio of the coating liquid for the back coat layer in Example 1 was changed to the compounding ratio shown below. Acrylic water-dispersible resin (Tg 98 ℃) 10 parts Aluminum hydroxide (Showa Denko's Hydilite H42 particle size 1.0 μm) 10 parts Water 180 parts

Example 9 A thermosensitive recording material was obtained in the same manner as in Example 1 except that the compounding ratio of the coating liquid for the back coat layer in Example 1 was changed to the compounding ratio shown below. Acrylic water-dispersible resin (Tg 98 ° C) 10 parts Amorphous silica (Mizukasil P527 manufactured by Mizusawa Chemical Co., Ltd.) 10 parts Water 180 parts

Example 10 A thermosensitive recording material was obtained in the same manner as in Example 1 except that the compounding ratio of the coating liquid for the back coat layer in Example 1 was changed to the compounding ratio shown below. Acrylic water-dispersible resin (Tg 98 ° C.) 10 parts Polymethylmethacrylate (MB20X-5 manufactured by Sekisui Plastics, particle size 5 μm) 10 parts Water 180 parts

Example 11 A thermal recording material was obtained in the same manner as in Example 1 except that the compounding ratio of the coating liquid for the back coat layer in Example 1 was changed to the compounding ratio shown below. Acrylic water-dispersible resin (Tg 98 ° C) 10 parts Polymethylmethacrylate (MBX-8 particle size 8 μm manufactured by Sekisui Plastics Co., Ltd.) 4 parts Water 126 parts

Example 12 A thermosensitive recording material was obtained in the same manner as in Example 1 except that the composition ratio of the coating liquid for the back coat layer in Example 1 was changed to the composition ratio shown below. Acrylic water dispersible resin (Tg 98 ° C) 10 parts Polymethylmethacrylate (MBX-8 particle size 8 μm manufactured by Sekisui Plastics) 10 parts Water 180 parts

Example 13 A thermosensitive recording material was obtained in the same manner as in Example 1 except that the compounding ratio of the coating liquid for the back coat layer in Example 1 was changed to the compounding ratio shown below. Acrylic water dispersible resin (Tg 98 ° C) 10 parts Polymethylmethacrylate (MBX-8 particle size 8 μm manufactured by Sekisui Plastics Co., Ltd.) 60 parts Water 630 parts

Example 14 A thermosensitive recording material was obtained in the same manner as in Example 1 except that the compounding ratio of the coating liquid for the back coat layer in Example 1 was changed to the compounding ratio shown below. Acrylic water-dispersible resin (Tg 98) 10 parts Amorphous silica (Mizukasil P527 manufactured by Mizusawa Chemical Co., Ltd.) 4 parts Water 126 parts

Example 15 A thermosensitive recording material was obtained in the same manner as in Example 1 except that the compounding ratio of the coating liquid for the back coat layer in Example 1 was changed to the compounding ratio shown below. Acrylic water-dispersible resin (Tg 98 ° C) 10 parts Amorphous silica (Mizukasil P527 manufactured by Mizusawa Chemical Co., Ltd.) 5 parts Water 135 parts

Example 16 A thermosensitive recording material was obtained in the same manner as in Example 1 except that the compounding ratio of the coating liquid for the back coat layer in Example 1 was changed to the compounding ratio shown below. Acrylic water-dispersible resin (Tg 98 ° C) 10 parts Amorphous silica (Mizukasil P527 manufactured by Mizusawa Chemical Co., Ltd.) 50 parts Water 540 parts

Example 17 A thermosensitive recording material was obtained in the same manner as in Example 1 except that the compounding ratio of the coating liquid for the back coat layer in Example 1 was changed to the compounding ratio shown below. Acrylic water-dispersible resin (Tg 98 ° C) 10 parts Amorphous silica (Mizukasil P527 manufactured by Mizusawa Chemical Co., Ltd.) 60 parts Water 630 parts

Comparative Example 1 A thermosensitive recording material was obtained in the same manner as in Example 1 except that the composition ratio of the coating liquid for the back coat layer in Example 1 was changed to the composition ratio shown below. Completely saponified PVA 10 parts Amorphous silica (Mizukasil P527 manufactured by Mizusawa Chemical Co., Ltd.) 10 parts Water 180 parts

Comparative Example 2 A thermosensitive recording material was obtained in the same manner as in Example 1 except that the compounding ratio of the coating liquid for the back coat layer in Example 1 was changed to the following compounding ratio. Completely saponified PVA 10 parts Aluminum hydroxide (Higelite H42 manufactured by Showa Denko) 10 parts Water 180 parts

Comparative Example 3 A thermosensitive recording material was obtained in the same manner as in Example 1 except that the composition ratio of the coating liquid for the back coat layer in Example 1 was changed to the composition ratio shown below. Acrylic water dispersible resin (Tg-31 ° C) 20 parts Water 180 parts

Comparative Example 4 A thermosensitive recording material was obtained in the same manner as in Example 1 except that the base paper having Gurley air permeability of 700 seconds was used.

Comparative Example 5 A thermosensitive recording material was obtained in the same manner as in Example 1 except that the back coat layer was not provided.

Comparative Example 6 In Example 1, the back coat layer was not provided, and 0.5 cc of OP varnish ink was printed as a protective layer on the thermosensitive recording layer at 30 rpm with an RI tester to obtain a thermosensitive recording material. .

Comparative Example 7 A thermosensitive recording material was obtained in the same manner as in Example 1 except that the compounding ratio of the coating liquid for the back coat layer in Example 1 was changed to the compounding ratio shown below. Acrylonitrile-butadiene-based water-dispersible resin (Tg-31 ° C) 10 parts Colloidal silica (Nissan Chemical Snowtex ST-XL) 5 parts Water 135 parts

The recording material was subjected to the following test, and the test results are shown in Table 1.

(1) Thermal response A printing test was performed using a facsimile tester TH-PMD manufactured by Okura Electric. A thermal head having a dot density of 8 dots / mm and a head resistance of 1685Ω was used, and the color density was measured by applying current with a head voltage of 21 V and a pulse width of 1.2 msec, and the color density was measured with a Macbeth RD-19i. The larger the number, the better the thermal response, and 1.1 or more is preferable for practical use.

(2) Water blocking resistance 70 mm × 70 mm heat sensitive recording Two heat sensitive recording materials with printing were soaked in water for 30 seconds, the front and back were overlapped, and a load of 50 was applied.
0 g is given and left in an oven at 60 ° C. for 30 minutes to dry the thermosensitive recording material. After that, the recording material was peeled off by hand. 1 When the weight is removed, it adheres, and when peeled off, most of the coating layer peels off. 2 When the weight is removed, it is in close contact, and when it is peeled off, part of the coating layer is peeled off from the support, and part of the heat-sensitive recorded image is peeled off. 3 When the weight was removed, it adhered, and when peeled off, part of the coating layer peeled from the support, but the heat-sensitive recorded image did not peel. 4 It is adhered when the weight is removed, but it can be peeled off without resistance. 5 When the weight is removed, it peels off without problems. For practical use, 3 or more is preferable.

(3) A curl 70 mm × 70 mm heat-sensitive recording material was placed in the environment of 40 ° C. and 90% RH for 24 hours with the front and back facing up, and the heights of the four corners were recorded and the average height was recorded. . The height when the table is turned up is +. The height when the back side is facing up-is recorded in mm. 1 Over +15 mm or over -15 mm. Within 2 +15 to +10 mm or -15 to -10 mm
Within. Within 3 +10 to +5 mm or within -10 to -5 mm. 4 Within +5 to +2 mm or within -5 to -2 mm. Within 5 +2 to -2 mm. For practical use, 3 or more is preferable.

(4) Print density After printing 0.3 cc of UV curable ink with an RI tester at 30 rpm, the density was measured by Macbeth reflection densitometer RD-19.
It was measured at i. Practically, it is preferably 0.6 or more.

[0091]

[Table 1]

As is clear from Table 1 above, Examples 1 to 1
Compared with Comparative Examples 1 to 6, No. 17 has a performance that can be actually used in all of thermal response, water blocking resistance, curl, and print density, and is excellent in balance. It is clear that this is because the Gurley air permeability was set to 300 seconds or less when the back coat layer was provided. In Comparative Example 7, Tg-
Water-dispersible latex below 30 ℃ and particle size 0.1μm
Gurley Air Permeability of 30 due to the combination of less than
As a result of not being able to adjust to 0 seconds or less, it is clear that the water blocking resistance does not reach the actual use range.

Examples 1 to 4, 8 to 10, 15 and 16 are superior to Examples 5 to 7 in water blocking resistance, and superior to Examples 11 to 13 in print density. This depends on the particle size of the pigment particles in the back coat layer. In addition, Examples 1 to 1
4,8 to 10,15,16 are superior in water blocking resistance as compared with Example 14, and are excellent in curl as compared with Examples 7,13,17. This depends on the mass mixing ratio of the adhesive of the back coat layer and the inorganic or organic pigment.

The printing density of Examples 1, 3 and 9 is superior to that of Example 4. This is because the adhesive of the back coat layer is a water-dispersible resin. Moreover, Examples 1, 3, 8-
10, 15, 16 are superior in water blocking resistance as compared with Examples 2, 4. This is because the adhesive of the back coat layer is a water-dispersible resin having Tg of −30 ° C. or higher.

In Comparative Examples 5 and 6, the curl is not within the practically usable range because the back coat layer is not provided. Further, in Example 6, since the OP varnish was printed, the water blocking resistance was good, but as described above, it was difficult to achieve curl balance, and the thermal response was greatly reduced.

[0096]

EFFECT OF THE INVENTION A thermosensitive recording layer having a backcoat layer on the back surface of a support, provided with a thermosensitive coloring layer containing an electron-donating, usually colorless or light-colored dye precursor and a developer which is an electron-accepting compound. In the material, by setting the Gurley air permeability of the thermal recording material to 300 seconds or less, a thermal recording material having water blocking resistance, excellent curl balance, good sensitivity, and good printability on the back surface can be obtained. It is now possible to provide.

Claims (3)

[Claims] 1. A heat-sensitive recording comprising a support, a thermosensitive coloring layer containing an electron-donating, usually colorless or pale-colored dye precursor, and a developer which is an electron-accepting compound, and a backcoat layer on the back surface. The thermal recording material is characterized in that the Gurley air permeability of the thermal recording material is 300 seconds or less. 2. The back coat layer comprises (A) a particle size of 0.1.
2. The heat-sensitive recording according to claim 1, wherein the inorganic or organic pigment having a particle size of 5 .mu.m and the adhesive (B) are contained in a mass mixing ratio (A) / (B) of 5/10 to 50/10. material. 3. The heat-sensitive recording material according to claim 2, wherein the adhesive is a water-dispersible latex having a Tg of −30 ° C. or higher.