JPH0930121A - Multicolor thermal recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multicolor thermal recording material having a support excellent in touch and excellent in image quality uniformity. SOLUTION: In a multicolor thermal recording material wherein two or more thermal recording layers are provided on a support, the support has the thermoplastic resin layer provided on the surface on the side opposite to the surface provided with at least a thermal recording layer of a sheet like substrate wherein a plastic film is laminated to the surface of the thermal recording layer of raw paper through an adhesive by melt extrusion. More desirably, a thermal resin layer is provided between the sheet like substrate and the thermal recording layer of the plastic film by melt extrusion. The raw paper and the plastic film are bonded by dry lamination, solventless dry lamination, dry lamination using electron beam or ultraviolet curable resin or hot melt lamination.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multicolor heat-sensitive recording material, particularly to a support thereof, and more specifically, it has excellent image uniformity and excellent handleability during printing and viewing. , Flexibility, smoothness, glossiness,
The present invention relates to a support for a multicolor heat-sensitive recording material having excellent curling property.

[0002]

2. Description of the Related Art In image recording of a full-color heat-sensitive recording material, a thermal head directly makes contact with the surface of the recording material to perform thermal recording. Therefore, when the surface of the recording material has irregularities, image unevenness occurs. It has been found that the flatness of the recording material largely depends on the flatness of the support used.

Conventionally, as a support, a polyethylene-coated paper in which a polyethylene layer obtained by kneading a white pigment and the like is provided on a base paper manufactured from pulp is usefully used. However, when polyethylene-coated paper is used as a support, the uneven surface of the adjacent base paper results in a rough, rippled, glossy surface, which considerably impairs the uniformity of the image.

As a method for solving the above-mentioned drawbacks, some methods have been proposed in which a base paper is not used for a support and only a thermoplastic resin film is used. JP-A-49-114921
Japanese Patent Publication No. 55-5104 discloses a method of filling a polystyrene resin film with a white pigment. Further, British Patent Nos. 1,563,591 and 1,563,592 disclose a method of adding barium sulfate to polyester and stretching. Tokiko 56
No. -4901 discloses a technique of using barium sulfate and titanium oxide as a thermoplastic resin. JP-A-61-1
No. 18746, polyester has an average particle size of 0.1 to 0.1
A technique of adding 0.5 μm surface-treated titanium oxide is disclosed. Since they are hard and brittle, they tend to have knicks and the like during handling, and they have the drawbacks of making them feel as rigid as plastics and having a greatly different texture compared to those obtained by melting and extruding a polyolefin resin on the base paper.

Further, Japanese Patent Application Laid-Open No. 49-12815 discloses a technique for forming a polyolefin layer containing a white inorganic filler on one side of a synthetic paper or a plastic film having writability. It is impossible to adjust the curl after coating.

Further, Japanese Patent Application Laid-Open No. 3-91740 discloses a type of support in which a paper, synthetic paper or film substrate is coated with a polyolefin resin composition containing a specific titanium oxide. The support has a smooth surface. However, it is not easy to handle.

Japanese Unexamined Patent Publication (Kokai) No. 2-230236 discloses a technique of laminating a polyolefin resin on the surface of a thermoplastic resin such as a vinyl chloride resin which is suitable for embossing for ID cards and cashing cards. Compared with a product obtained by melt-extruding a polyolefin resin, it has a drawback that it feels as rigid as a plastic sheet, the texture is greatly different, and the smoothness is insufficient.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks, and it is flexible and has an excellent handleability similar to the texture of a conventional support using a base paper. Another object of the present invention is to provide a multicolor heat-sensitive recording material excellent in image uniformity using a support having high smoothness and high gloss.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a multicolor thermosensitive recording material in which two or more thermosensitive recording layers are provided on a support, wherein the support has a surface on which the thermosensitive recording layer of the base paper is provided. A multi-colored sheet having a thermoplastic resin layer extruded on at least the surface opposite to the surface on which the heat-sensitive recording layer is provided Achieved by a thermosensitive recording material. Further, the multicolor heat-sensitive recording material of the present invention is preferably one in which a melt-extruded thermoplastic resin layer is provided between the plastic film of the sheet-shaped substrate and the heat-sensitive recording layer.

The base paper used for the support for the multicolor heat-sensitive recording material according to the present invention is selected from commonly used materials. That is, a natural pulp selected from softwood, hardwood, etc. is used as a main raw material, and if necessary, a filler such as clay, talc, calcium carbonate, urea resin fine particles, rosin, alkyl ketene dimer, higher fatty acid, epoxidized fatty acid amide, paraffin wax. A sizing agent such as alkenyl succinic acid, a starch, a paper-strengthening agent such as polyamide polyamine epichlorohydrin or polyacrylamide, a sulfuric acid band, a fixing agent such as a cationic polymer, and the like are used. Further, a softening agent such as an epoxidized fatty acid amide or a surfactant may be added. Further, synthetic pulp may be used in place of the above natural pulp, or natural pulp and synthetic pulp may be mixed in an arbitrary ratio.

Although the type and thickness of the base paper are not particularly limited, the basis weight is 50 g / m ² to 250.
Since g / m ² is desirable, and a multicolor heat-sensitive recording material is desired to have as high flatness as possible, it is desirable that it has excellent surface smoothness and flatness. Surface treatment is preferably performed by applying heat and pressure. The support for a multicolor heat-sensitive recording material of the present invention is one in which a surface sizing agent is applied to both sides of a base paper.

The surface size liquid is an aqueous solution of polyvinyl alcohol and / or its modified products.
High molecular compounds such as starch, carboxymethyl cellulose, hydroxyethyl cellulose, sodium alginate, cellulose sulfate, gelatin, casein, metal salts such as calcium chloride, sodium chloride and sodium sulfate, hygroscopic substances such as glycerin and polyethylene glycol, dyes, fluorescent A coloring agent such as a whitening agent, a whitening substance, a pH controlling agent such as caustic soda, aqueous ammonia, hydrochloric acid, sulfuric acid, sodium carbonate and the like may be added. Further, a softening agent such as an epoxidized fatty acid amide or a surfactant may be added. Further, a pigment or the like can be added if necessary. As a method for impregnating the base paper, it is preferable to impregnate and apply with a size press, a tab size or a gate roll coaster.

The plastic film used in the present invention includes polyethylene film (high density or low density), polypropylene film, acetate film,
It can be appropriately selected from known films such as polyvinyl chloride film, polyvinylidene chloride film, polystyrene film, polyester film, polycarbonate film, nylon film, polypropylene film, polyurethane film and acrylic film. The thickness of these plastic films is 5-10
Preferably, it is 0 μm.

Regarding the film forming processing of these plastic films, the casting method, extrusion method, calendering method, stretching method, etc. described in "Plastic Film-Processing and Application", Plastic Film Research Council (Gihodo), etc. Any of the above methods can be used.

Further, the plastic film may be filled with a white pigment. Examples of white pigments to be filled include titanium dioxide, barium sulfate, barium carbonate, calcium carbonate, lithopone, white alumina, zinc oxide, silica antimony trioxide, and titanium phosphate. These can be used alone or as a mixture. Among these, titanium dioxide and zinc oxide are particularly preferable from the viewpoint of whiteness, dispersibility and stability.

Titanium dioxide may be of the rutile type or of the anatase type, and they may be used alone or in combination. Further, it may be made by the sulfuric acid method or the chlorine method. Titanium dioxide includes hydrated alumina treatment, hydrated silicon dioxide-based treatment, zinc oxide treatment or other surface coating treatment with an inorganic substance, trimethylolmethane, trimethylolethane, trimethylolpropane, 2,4-dihydroxy-2-methyl. It is possible to appropriately use a material whose surface is coated with an organic substance such as pentane or a material which is treated with siloxane such as polydimethylsiloxane. The filling amount of the white pigment in the plastic film varies depending on the white pigment used and the thickness of the plastic film, but is usually selected to be between 5% and 20%.

The electrical resistance of the plastic film surface is 1 × 10 ¹⁰ Ω · cm in order to prevent charging failure such as dust adhesion and coating unevenness during melt extrusion of the thermoplastic resin.
The following may be used. In this case, 7 × 10 is particularly preferable.
⁹ Ω · cm or less. As a means for lowering the surface electric resistance, it is possible to use a generally known technique such as providing an ionic organic antistatic agent such as an alkali metal salt of a polymerizable carboxylic acid or an electron transfer antistatic layer such as tin oxide. It is possible.

In the present invention, as a method for laminating the base paper and the plastic film, for example, a known lamination method as described in "New Laminating Manual" edited by Processing Technology Research Group can be appropriately selected and employed. However, it is desirable to adopt so-called dry lamination, solventless dry lamination, dry lamination using electron beam or UV curable resin or hot melt lamination, and more preferably dry lamination, solventless dry lamination, electron beam or It is desirable to adopt dry lamination using an ultraviolet curable resin. In the present invention, when the film and the base paper are bonded together by the above-mentioned methods, it is desirable to bond them at the lowest possible temperature so as not to impair the high smoothness of the base paper and the plastic film. Specifically, the temperature range at the time of pressure-bonding by dry lamination is preferably 110 ° C. or lower, more preferably 80 ° C. or lower. Since the support of the present invention produced as described above has mild temperature conditions in the production process, the smoothness of the base paper and the plastic film can be maximized.

The dry lamination is a method in which an adhesive is applied to a plastic film, dried, and then heat-pressed. The adhesive in this case is a solvent type vinyl resin, acrylic resin, polyamide resin. , Epoxy resin, rubber resin, urethane resin, etc.
Used at a rate of g / ml.

Solventless dry lamination is a plastic film containing 0.8 to 0.8 parts of a reaction curable adhesive such as a one-component moisture-curable urethane adhesive or a two-component urethane adhesive.
2.0 g / ml is applied and bonded to the base paper, and then the adhesive is reacted and cured by aging to complete the adhesion between the plastic film and the base paper.

The above-mentioned method of applying the adhesive includes gravure roll coating, wire bar coating, doctor blade coating, reverse roll coating, dip coating, air knife coating, calendar coating, kiss coating, squeeze coating, fan ten coating and the like. It can be appropriately selected and adopted from known methods.

The hot melt lamination is a method in which a 100% non-volatile thermoplastic resin is used, and the molten resin is directly applied to the adherend in a molten state and bonded to another substrate. In this case, as the adhesive agent, EVA, polyester, styrene elastomer, or polyamide based polymer is used.

As a method for applying the hot-melt adhesive that has been heated and melted to the substrate, a method similar to the method for applying the adhesive in dry lamination can be selected and adopted. An extrusion method may also be used in which a substrate and a film are pressure-bonded and laminated between a cooling roll and a nip roll via an adhesive melted and extruded in a film shape from an extruder and a T-die. In the present invention, it is desirable to provide the thermoplastic resin layer on the surface on which the plastic film is bonded by the melt extrusion method. Depending on the type of the plastic film, the adhesion to the multicolor thermosensitive recording layer may be low even if the plastic film surface is subjected to pretreatment or anchor treatment.

The thermoplastic resin in the thermoplastic resin layer formed by coating on the substrate is preferably a polyolefin resin, and examples thereof include homopolymers of α-olefins such as polyethylene and polypropylene, and mixtures of these various polymers. You can Particularly preferred polyolefins are high density polyethylene, low density polyethylene and mixtures thereof. These polyolefins are usually coated on both sides of the base paper by an extrusion coating method, so that the molecular weight thereof is not particularly limited as long as it can be extrusion coated, but the molecular weight is usually 10 or less.
A polyolefin in the range of ⁴ to 10 ⁶ is used.

The thickness of the polyolefin coating layer is not particularly limited, but usually 10 μm to 80 μm is suitable.

It is preferable that the front surface, that is, the polyolefin coating layer on the side on which the heat-sensitive recording layer is coated, contains a white pigment, and the kind and the amount of the white pigment are known. Can be selected as appropriate. Further, known additives such as a fluorescent whitening agent and an antioxidant can be added.

As the extrusion coating equipment for extrusion coating the polyolefin, an ordinary extruder for polyolefin and a laminator are used.

Before the thermoplastic resin layer is extruded onto the substrate and coated, the substrate is preferably pretreated in order to strengthen the adhesion between the substrate and the resin coating layer. As the pretreatment of the substrate, there are acid etching treatment with a mixed solution of chromic acid sulfate, flame treatment with a gas flame, ultraviolet irradiation treatment, corona discharge treatment, glow discharge treatment, anchor coat treatment with alkyl titanate and the like, which can be freely selected. From the viewpoint of simplicity, corona treatment is convenient. In the case of corona treatment, it is necessary to treat so that the contact angle with water is 70 ° or less.

As the anchor coating agent, organic titanium type, isocyanate type (urethane type) polyethyleneimine type, polybutadiene type and the like are known. Specifically, as organic titanium-based materials, alkyl titanates such as tetraisopropyl titanate, tetrabutyl titanate and tetrastearyl titanate, titanium acylates such as butoxytitanium stearate, titanium chelates such as titanium acetylacetonate are known. . Further, as the isocyanate type (urethane type), toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HMDI), xylylene diisocyanate (XD) is used.
I), isophorone diisocyanate (IPDI) and the like are known.

In order to improve the adhesiveness between this polyolefin coating layer and the heat-sensitive recording layer coated thereon,
The surface may be subjected to surface treatment such as corona discharge treatment,
Alternatively, an undercoat layer mainly containing gelatin may be provided after the surface is subjected to corona discharge treatment.

In the present invention, a thermoplastic resin layer is provided on the back side of the substrate by an extrusion method for the purpose of achieving curl balance. If the curl balance of the support is poor, the curl after coating the heat-sensitive recording layer is also affected, which adversely affects the paper feeding property and running property of the printer. As the thermoplastic resin, a polyolefin resin is desirable, and polyethylene is particularly preferably used. The polyethylene layer on the back side is usually formed using high density polyethylene or a blend of high density polyethylene and low density polyethylene. The polyethylene layer on the back side is usually a matte surface. It is possible to provide an antistatic layer containing an ionic organic antistatic agent such as an alkali metal salt of a polymerizable carboxylic acid, colloidal silica or the like on the polyethylene layer on the back surface thereof, if necessary.

In order to improve the uniformity of the image, it is necessary that the support for a multicolor thermosensitive recording material produced by the above method has a high smoothness, and a multicolor thermosensitive recording layer is coated. Center surface average roughness (SRa) of the surface on the side to be treated is 0.5 μm
It is desirable that the thickness is less than or equal to 0.2 μm.

The center surface roughness (SRa) is defined by extracting a portion having an area SM on the center surface from the curved surface and placing the orthogonal coordinate axes, X axis and Y axis on the center surface of the extracted portion. When the axis orthogonal to the surface is set as the Z axis, the value given by the following mathematical expression is defined as the center surface average roughness (SRa),
It is expressed in μm.

[0034]

[Equation 1]

However, the LX · LY = SM Z = f (X, Y) center plane average roughness is, for example, a radius of 2 μm using a three-dimensional surface shape measuring instrument (Surfcom 575A-3DF) manufactured by Tokyo Seimitsu Co., Ltd. It can be determined by measuring an area of 400 mm ² under the condition that the cut-off is cut by 2 mm or more and 0.4 mm or less by the diamond needle.

In order to approximate the texture of a conventional support made of base paper, the support in the present invention has the stiffness of the support defined by JIS8125 shown in the following formula as the thickness of the support. E value divided by the power of 3 is 40
It is preferably in the range of 0 to 1600.

[0037] However, S represents the stiffness of the support [gf · cm], and T represents the thickness of the support [mm].

If the E value is lower than 400, the rigidity is low and the softness is poor, so that the handleability is deteriorated, which is not preferable. If it is higher than 1600, it is hard and a knick easily occurs during handling.
The range of E value is more preferably 500 to 1500,
More preferably, it is 600-1400.

On the support of the present invention molded as described above,
A multicolor thermosensitive recording layer is coated. In this case, if necessary, prior to coating, surface activation treatment such as corona discharge and / or
Alternatively, an undercoat layer can be applied.

A support having excellent image uniformity can be obtained by coating a heat-sensitive recording layer on the support thus obtained as described later. The thermal recording layer will be described.

In FIG. 1, a transparent cyan heat-sensitive layer 2, an intermediate layer 3, a transparent yellow heat-sensitive layer 4 and an intermediate layer 5 are provided on one surface of a support 1.
And a transparent magenta heat-sensitive layer 6 are sequentially laminated, and a transparent protective layer 7 is provided on the layer, and this is a multicolor heat-sensitive recording material.
In this case, at least the magenta heat-sensitive layer and the yellow heat-sensitive layer have a color-developing system that is a diazo system, and the cyan heat-sensitive layer may or may not be a diazo system. In this case, the diazo compound is selected so that its decomposition wavelength range is longer as it is used for the outer heat-sensitive layer.

For recording, first, the outermost heat-sensitive layer is magenta-colored with low heat energy, and then the diazo compound contained in the outermost heat-sensitive layer is decomposed by irradiating light in the decomposition wavelength range from the upper surface. To fix the recorded image on the outermost heat-sensitive layer.

Next, heat energy larger than that at the time of the above-mentioned thermal recording is applied to cause the second heat-sensitive layer to develop yellow, and the second heat-sensitive layer is developed.
The recorded image of the second layer is fixed by irradiating light in the decomposition wavelength range of the diazo compound contained in the layer. Further, heat energy higher than that applied to the second layer is applied to cause the innermost heat-sensitive layer to develop cyan. If the innermost heat-sensitive layer also uses the diazo color development system, it is possible to irradiate light in the decomposition wavelength range to fix the recorded image in the innermost layer as well to prevent the occurrence of scumming over time. It is possible to do so, which is preferable.

As described above, cyan, magenta, and yellow can be independently colored, and as a result, cyan, magenta, yellow, cyan + magenta (blue), magenta + yellow (red ), Cyan + yellow (green), and cyan + magenta + yellow (black), a total of seven basic colors are realized with good color separation. In this case, those skilled in the art can easily understand that even if the innermost heat-sensitive layer is opaque, it does not adversely affect color reproduction.

If the outermost heat-sensitive layer has sufficient scratch resistance and sticking resistance, it goes without saying that the transparent protective layer may not be provided. Further, those skilled in the art can easily understand that the number of colors that can be realized by color mixing can be synergistically increased by controlling the color development of each unit by appropriately adjusting the applied heat energy. .

As described above, in the present invention, the coloring system of the innermost heat-sensitive layer may not be the diazo system. In this case, it is preferable to use a combination of an electron-donating dye precursor and a developer (leuco system) as a color-developing system other than the diazo system from the viewpoint of heat sensitivity and color density.

Next, the materials used for the multicolor thermosensitive recording material of the present invention will be described in detail. The electron-donating dye precursor in the present invention has a property of developing a color by donating an electron or accepting a proton such as an acid, and is not particularly limited, but it is usually substantially colorless and a lactone. Compounds having partial skeletons such as lactam, sultone, spiropyran, ester, amide, etc., and these partial skeletons are ring-opened or cleaved upon contact with a color developer are used. Specifically, crystal violet lactone, benzoyl leuco methylene blue, malachite green lactone,
Rhodamine B lactam, 1,3,3-trimethyl-6 '
-Ethyl-8'-butoxyindolinobenzospiropyran and the like.

The color developer for these color formers can be appropriately selected and used from known ones. For example, the developer for the leuco dye includes a phenol compound, a sulfur-containing phenol compound, a carboxylic acid compound, a sulfone compound, a urea compound or a thiourea compound, and the details thereof are, for example, Paper Pulp Technology Times. (1
985) 49-54 and 65-70. Among these, those having a melting point of 50 ° C. to 250 ° C. are particularly preferable, and among them, phenol and organic acids having poor solubility in water of 60 ° C. to 200 ° C. are preferable. It is preferable to use two or more developers in combination, since solubility increases.

Among the color developers used in the present invention, particularly preferable ones are represented by the following general formulas (1) to (4).

General formula (1)

[0051]

Embedded image

M = 0 to 2, n = 2 to 11

General formula (2)

[0054]

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R ⁷ is an alkyl group, an aryl group, an aryloxyalkyl group or an aralkyl group, and a methyl group and a butyl group are particularly preferable.

General formula (3)

[0057]

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R ⁸ is an alkyl group, especially a butyl group,
Pentyl, heptyl and octyl groups are preferred. R
⁹ is a hydrogen atom or a methyl group, and n is 0-2.

General formula (4)

[0060]

Embedded image

R ¹⁰ is an alkyl group, an aralkyl group or an aryloxyalkyl group.

In the present invention, 0.3 to 160 parts by weight of a color developing agent is added to 1 part by weight of the electron-donating dye precursor.
It is preferable to use 0.3 to 80 parts by weight.

The other diazo compound of the color-forming material of the multicolor heat-sensitive recording material of the present invention is a compound which reacts with a developer called a coupler described later to develop a desired hue, and before reaction. When it receives light of a specific wavelength, it decomposes and after that the coupler no longer has the ability to develop color. The hue in this color-developing system is mainly determined by the diazo dye produced by the reaction between the diazo compound and the coupler. Therefore, as is well known, the color hue can be easily changed by changing the chemical structure of the diazo compound or the chemical structure of the coupler, and almost any color hue can be obtained depending on the combination. .

The photodecomposable diazo compound in the present invention mainly refers to an aromatic diazo compound, and more specifically, a compound such as an aromatic diazonium salt, a diazosulfonate compound, a diazoamino compound or the like. Hereinafter, a diazonium salt will be mainly described as an example.

It is generally said that the photolysis wavelength of a diazonium salt is its absorption maximum wavelength. The absorption maximum wavelength of the diazonium salt is 200n depending on its chemical structure.
It is known to change from the m-position to the 700-nm position ("Photolysis and chemical structure of photosensitive diazonium salts" by Takahiro Tsunoda and Ao Yamaoka, Journal of the Photographic Society of Japan 29 (4) 197-1.
05 (1965)). Further, by changing the chemical structure of the diazonium salt, the hue of the dye produced by the coupling reaction can be changed even when the coupling reaction with the same coupler is performed.

The diazonium salt is a compound represented by the general formula ArN ₂ ⁺ X ⁻ . In the formula, Ar represents a substituted or unsubstituted aromatic moiety, N ₂ ⁺ represents a diazonium group, and X ⁻ represents an acid anion.

Of these, compounds having a photolytic wavelength near 400 nm include 4-diazo-1-dimethylaminobenzene, 4-diazo-1-diethylaminobenzene, 4-diazo-1-dipropylaminobenzene and 4-diazo-1-diethylaminobenzene.
Diazo-1-methylbenzylaminobenzene, 4-diazo-1-dibenzylaminobenzene, 4-diazo-1-
Ethylhydroxyethylaminobenzene, 4-diazo-
1-diethylamino-3-methoxybenzene, 4-diazo-1-dimethylamino-2-methylbenzene, 4-diazo-1-benzoylamino-2,5-diethoxybenzene, 4-diazo-1-morpholinobenzene, 4 -Diazo-1-morpholino-2,5-dibutoxybenzene, 4
-Diazo-1-anilinobenzene, 4-diazo-1-toluylmercapto-2,5-diethoxybenzene, 4-
Diazo-1,4-methoxybenzoylamino-2,5-
Diethoxybenzene and the like can be mentioned. 300 ~
As a compound having a photolytic wavelength at 370 nm, 1-
Diazo-4- (N, N-dioctylcarbamoyl) benzene, 1-diazo-2-octadecyloxybenzene,
1-diazo-4- (4-tert-octylphenoxy) benzene, 1-diazo-4- (2,4-di-ter)
t-amylphenoxy) benzene, 1-diazo-2-
(4-tert-octylphenoxy) benzene, 1-
Diazo-5-chloro-2- (4-tert-octylphenoxy) benzene, 1-diazo-2,5-bis-octadecyloxybenzene, 1-diazo-2,4-bis-
Octadecyloxybenzene, 1-diazo-4- (N-
Octyl theuroyl amino) benzene etc. can be mentioned. The aromatic diazonium compounds represented by the above-mentioned examples can widely change the photolysis wavelength by arbitrarily changing the substituents.

Specific examples of the acid anion include C _n F _{2n + 1}
COO ⁻ (n represents 3 to 9), C _m F _{2m + 1} SO ₃ ⁻
(M represents 2 to 8), (ClF _{2i + 1} SO ₂ ) ₂ CH
^- (I represents 1 to 18),

[0069]

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Specific examples of the diazo compound (diazonium salt) include the followings.

[0071]

[Chemical 6]

[0072]

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The diazosulfonate compound that can be used in the present invention has the general formula

[0074]

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It is a compound represented by: In the formula, R ₁ is an alkali metal or ammonium compound, R ₂ , R ₃ , R ₅
And R ₆ is hydrogen, halogen, an alkyl group, or an alkoxy group, and R ₄ is hydrogen, a halogen, an alkyl group, an amino group, a benzoylamide group, a morpholino group, a trimercapto group, or a pyrrolidino group.

Many such diazosulfonates are known, and they can be obtained by treating each diazonium salt with sulfite.

Among these compounds, preferred compounds are 2-methoxy, 2-phenoxy and 2-methoxy-
4-phenoxy, 2,4-dimethoxy, 2-methyl-4
Benzenediazosulfonic acid salt having a substituent such as -methoxy, 2,4-dimethyl, 2,4,6-trimethyl, 4-phenyl, 4-phenoxy, 4-acetamide, or 4- (N-ethyl, N-benzylamino), 4-
(N, N-Dimethylamino), 4- (N, N-diethylamino), 4- (N, N-diethylamino) -3-chloro, 4-pyridinino-3-chloro, 4-morpholino-2
-Methoxy, 4- (4'-methoxybenzoylamino)
-2,5-dibutoxy, 4- (4'-trimercapto)
It is a benzenediazosulfonate having a substituent such as -2,5-dimethoxy. When these diazosulfonate compounds are used, it is desirable to perform light irradiation for activating the diazosulfonate before printing.

As another diazo compound which can be used in the present invention, a diazoamino compound can be mentioned. As the diazoamino compound, a diazo group having a dicyandiamide, sarcosine, methyltaurine, N-ethylanthranic acid-5-sulphonic acid,
It is a compound coupled with monoethanolamine, diethanolamine, guanidine and the like.

The coupler used in the present invention forms a dye by coupling with a diazo compound (diazonium salt), and specific examples thereof include resorcin, phloroglucin and sodium 2,3-hydroxynaphthalene-6-sulfonate. , 1-hydroxy-2-naphthoic acid morpholinopropylamide, 1,5-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,3-dihydroxy-6-sulfanylnaphthalene, 2-hydroxy-3-naphthoic acid morpholinopropylamide, 2-Hydroxy-3-naphthoic acid-2'-methylamide, 2-hydroxy-3-naphthoic acid ethanolamide, 2-hydroxy-3-naphthoic acid octylamide, 2-hydroxy-3-naphthoic acid-N-dodecyl-oxy -Propylamide, 2-hydroxy Ci-3-naphthoic acid tetradodecylamide, acetanilide, acetoacetalinide, benzoylacetanilide, 1-phenyl-3-methyl-
5-pyrazolone, 2,4-bis (benzoylacetamino) toluene, 1,3-bis (bivaloylacetaminomethyl) benzene, 1- (2 ', 4', 6'-trichlorophenyl) -3-benzamide- 5-pyrazolone, 1
Examples thereof include-(2 ', 4', 6'-trichlorophenyl) -3-anilino-5-pyrazolone and 1-phenyl-3-phenylacetamido-5-pyrazolone.

Further, by using two or more of these couplers in combination, an image having an arbitrary color tone can be obtained. Since the coupling reaction between these diazo compound and the coupler easily occurs in a basic atmosphere, a basic substance may be added in the layer.

As the basic substance, a hardly water-soluble or water-insoluble basic substance or a substance which generates an alkali upon heating is used. Examples thereof are inorganic and organic ammonium salts, organic amines, amides, urea and thiourea and their derivatives, thiazoles, pyrroles, pyrimidines, piperazines, guanidines, indoles, imidazoles, imidazolines and triazoles. , Nitrogen-containing compounds such as morpholines, piperidines, amidines, formazines and pyridines. Specific examples of these are described, for example, in Japanese Patent Application No. 60-132990. Two or more basic substances may be used in combination.

It is preferable to use 0.1 to 10 parts by weight of the coupler and 0.1 to 20 parts by weight of the basic substance with respect to 1 part by weight of the diazo compound.

The materials which cause the above-mentioned color-forming reaction are made from the viewpoint of improving the transparency of the heat-sensitive layer, the viewpoint of raw storability such as preventing contact between the color-developing agent and the color-developing agent at room temperature (prevention of fog), and the desired applied heat. From the viewpoint of controlling the color development sensitivity such that energy is used for color development, it is preferable to encapsulate some of the components essential for color development.

The type of microcapsules used in this case is not particularly limited, but the microcapsules particularly preferred in the present invention prevent contact between substances inside and outside the capsules at room temperature due to the substance separating action of the microcapsule walls. The permeation of a substance increases only while it is heated above a certain temperature, and the permeation initiation temperature can be freely controlled by appropriately selecting the capsule wall material, the capsule core substance, and the additive. It is a thing.
The permeation initiation temperature in this case corresponds to the glass transition temperature of the capsule wall (eg, JP-A-59-91438).
Japanese Patent Application No. 59-190886, Japanese Patent Application No. 59-994.
No. 90).

In order to control the glass transition point specific to the capsule wall, it is necessary to change the type of capsule wall forming agent. As the wall material of the microcapsule, polyurethane, polyurea, polyester, polycarbonate, urea-formaldehyde resin, melamine resin, polystyrene, styrene methacrylate copolymer, styrene-acrylate copolymer, gelatin, polyvinylpyrrolidone,
Polyvinyl alcohol and the like. In the present invention, two or more of these polymer substances can be used in combination. In the present invention, among the above polymer substances, polyurethane, polyurea, polyamide, polyester, polycarbonate and the like are preferable, and polyurethane and polyurea are particularly preferable.

The microcapsules used in the present invention can be microencapsulated by emulsifying a core substance containing a reactive substance such as a color former and then forming a wall of a polymer substance around the oil droplets. Preferably, in this case the reactant forming the polymeric substance is added inside the oil droplet and / or outside the oil droplet. Details of the microcapsules that can be preferably used in the present invention, such as the preferred method for producing the microcapsules, are described in, for example, JP-A-59-222716.

Here, the organic solvent for forming the oil droplets can be appropriately selected from high boiling point oils in general, and particularly, an organic solvent suitable for dissolving the developer or coupler described later. The use of is preferred because it has excellent solubility in a color former and can increase the color density and color development rate in thermal printing or reduce fog. When making microcapsules, it can be made from an emulsion containing 0.2% by weight or more of the components to be microencapsulated.

The preferred microcapsules produced as described above are not destroyed by heat or pressure as used in conventional recording materials, and the reactive substances contained in the core and outside of the microcapsules are It can react through the walls of the microcapsules.

In the present invention, it is also possible to use a coloring aid. The color-forming aid that can be used in the present invention is a substance that increases the color-developing density during heating printing or lowers the minimum color-forming temperature, such as a coupler, a basic substance, a color-developing agent, a developer or a diazo compound. The effect is to lower the melting point of or to lower the softening point of the capsule wall, thereby creating a situation in which diazo, a basic substance, a coupler, a color developing agent, a color developing agent and the like are likely to react.

Examples of the color-forming assistant include phenol compounds, alcoholic compounds, amide compounds, sulfonamide compounds, and the like. Specific examples are p-tert-octylphenol, p-benzyloxyphenol, phenyl p-oxybenzoate, Benzyl carbanylate, phenethyl carbanylate, hydroquinone dihydroxyethyl ether, xylylenediol, N-hydroxyethyl-
Examples thereof include compounds such as methanesulfonic acid amide and N-phenyl-methanesulfonic acid amide. These may be contained in the core substance, or may be added outside the microcapsules as an emulsified dispersion.

In the present invention, in order to obtain a substantially transparent thermosensitive color developing layer, the developer for the electron-donating dye precursor or the coupler for the diazo compound is dissolved in a water-insoluble or insoluble organic solvent. After that, this is mixed with an aqueous phase containing a surfactant and having a water-soluble polymer as a protective colloid, and used in the form of an emulsion-dispersed dispersion.

The organic solvent that dissolves the color developer or coupler can be appropriately selected from oils having a high boiling point, and particularly known as esters and pressure-sensitive oils having two or more benzene rings and having a hetero atom. It is preferable that the number of oils is less than the specified number. Such oils include compounds represented by the following general formulas (5) to (7) and triallylmethane (eg, tritolylmethane, toluyldiphenylmethane), terphenyl compounds, alkyl compounds (eg, terphenyl), alkylated Diphenyl ether (for example, propyl diphenyl ether), hydrogenated terphenyl (for example, hexahydroterfel), and diphenyl ether. Above all, it is preferable to use the esters from the viewpoint of the emulsion stability of the emulsified dispersion of the color developer or the coupler.

General formula (5)

[0094]

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In the formula, R ¹ represents hydrogen or an alkyl group having 1 to 18 carbon atoms, and R ² represents an alkyl group having 1 to 18 carbon atoms. p ¹ and q ¹ represent an integer of ¹ to 4, and the total sum of alkyl groups is 4 or less. The alkyl group of R ¹ and R ² is preferably an alkyl group having 1 to 8 carbon atoms.

General formula (6)

[0097]

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In the formula, R ³ represents hydrogen or an alkyl group having 1 to 12 carbon atoms, and R ⁴ represents an alkyl group having 1 to 12 carbon atoms. n represents 1 or 2. p ² and q ² represent an integer of 1 to 4. When n = 1, the total number of alkyl groups is 4 or less, and when n = 2, the total number of alkyl groups is 6 or less.

General formula (7)

[0100]

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In the formula, R ⁵ and R ⁶ are hydrogen atoms or have 1 carbon atom.
~ 18 same or different alkyl groups are represented. m represents an integer of 1 to 13. p ³ and q ³ represent integers of 1 to 3, and the total sum of alkyl groups is 3 or less. still,
The alkyl group of R ⁵ and R ⁶ is particularly preferably an alkyl group having 2 to 4 carbon atoms.

Examples of the compound represented by the formula (5) include dimethylnaphthalene, diethylnaphthalene and diisopropylnaphthalene.

Examples of the compound represented by the formula (6) include dimethylbiphenyl, diethylbiphenyl, diisopropylbiphenyl and diisobutylbiphenyl.

Examples of the compound represented by the formula (7) include 1
-Methyl-1-dimethylphenyl-1-phenylmethane, 1-ethyl-1-dimethylphenyl-1-phenylmethane, 1-propyl-1-dimethylphenyl-1-phenylmethane.

Examples of the esters include phosphoric acid esters (eg, triphenyl phosphate, tricresyl phosphate, butyl phosphate, octyl phosphate, cresyl diphenyl phosphate), phthalic acid esters (dibutyl phthalate, 2-ethylhexyl phthalate, phthalic acid). Ethyl, octyl phthalate, butylbenzyl phthalate), tetrahydrophthalate dioctyl, benzoic acid ester (ethyl benzoate, propyl benzoate, butyl benzoate, isopentyl benzoate, benzyl benzoate), abietic acid ester (abietic acid) Ethyl, benzyl abietic acid), dioctyl adipate, isodecyl succinate, dioctyl azelate, oxalic acid ester (dibutyl oxalate, dipentyl oxalate), diethyl malonate, maleic acid ester (dimethyl maleate, maleic acid) Diethyl acid, dibutyl maleate), tributyl citrate, sorbate (methyl sorbate, ethyl sorbate, butyl sorbate), sebacate (dibutyl sebacate, dioctyl sebacate), ethylene glycol esters (formic acid monoester) And diesters, butyric acid monoesters and diesters, lauric acid monoesters and diesters, palmitic acid monoesters and diesters, stearic acid monoesters and diesters, oleic acid monoesters and diesters), triacetin, diethyl carbonate, diphenyl carbonate, ethylene carbonate, carbonic acid propylene,
Boric acid esters (tributyl borate, tripentyl borate) and the like.

The above oils can be used together or with other oils.

In the present invention, an auxiliary solvent may be added to the above organic solvent as a dissolution aid having a low boiling point. As such an auxiliary solvent, for example, ethyl acetate, isopropyl acetate, butyl acetate, methylene chloride and the like can be mentioned as particularly preferable ones.

The water-soluble polymer to be contained as a protective colloid in the aqueous phase mixed with the oil phase in which the color developer or coupler is dissolved is a known anionic polymer, nonionic polymer,
Although it can be appropriately selected from the amphoteric polymers, polyvinyl alcohol, gelatin, cellulose derivatives and the like are preferable.

As the surface active agent to be contained in the aqueous phase, an anionic or nonionic surface active agent which does not cause precipitation or aggregation by acting on the protective colloid is appropriately selected and used. be able to. Preferred surfactants include sodium alkylbenzenesulfonate (eg, sodium lauryl sulfate), dioctyl sodium sulfosuccinate, polyalkylene glycol (eg, polyoxyethylene nonyl phenyl ether), and the like.

The emulsified dispersion of the developer or coupler in the present invention is usually prepared by subjecting an oil phase containing the developer or coupler and an aqueous phase containing a protective colloid and a surfactant to high-speed stirring, ultrasonic dispersion or the like. It can be easily obtained by mixing and dispersing using the means used for fine particle emulsification.

At this time, the oil droplet size (diameter) of the emulsified dispersion
Is 7 to obtain a transparent heat-sensitive phase having a haze of 60% or less.
It is preferably equal to or less than μ. More preferably 0.1 to
It is within the range of 5μ.

Or the ratio of oil phase to water phase (oil phase weight /
The water phase weight) is preferably 0.02 to 0.6, and more preferably 0.1 to 0.4. If it is 0.02 or less, the amount of the aqueous phase is too large to be diluted, and sufficient color developability cannot be obtained.

In the present invention, in addition to the above materials, citric acid, tartaric acid, oxalic acid, boric acid, phosphoric acid, pyrophosphoric acid and the like can be added as an acid stabilizer.

The heat-sensitive material of the present invention can be coated using a suitable binder. As the binder, polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, hydroxypropyl cellulose, arabic gum, gelatin, polyvinyl pyrrolidone, casein, styrene-butadiene latex, acrylonitrile-butadiene latex, polyvinyl acetate, polyacrylate, ethylene-vinyl acetate copolymer And other various emulsions can be used. The amount used is 0.5 to 5 g / m ² in terms of solid content.

The coating amount of the heat sensitive layer is 3 g / m ^{2 to} 20.
g / m ^2, it is preferable that particularly is between ^{5g / m 2 ~15g / m 2} . If it is 3 g / m ² or less, sufficient sensitivity cannot be obtained, and even if it is coated at 20 g / m ² or more, no improvement in quality is observed, which is disadvantageous in terms of cost. In the present invention, it is preferable to provide an intermediate layer between the heat-sensitive layer and the heat-sensitive layer from the viewpoints of raw storability of the heat-sensitive recording material, recorded image storability and improvement of color separation. It is preferable to use a layer in which the polymer is gelled with a polyvalent cation.

The water-soluble polyanionic polymer is preferably a polymer having a carboxyl group, a sulfonic acid group or a phosphoric acid group, and a water-soluble polyanionic polymer having a carboxyl group is particularly preferable. Examples of preferred water-soluble polyanionic polymers include natural or synthetic polysaccharide gums (such as alkali metal alginate,
Gua gum, gum arabic, carrageenan, pectin, tragacanth gum, xanthene gum, etc.), polymers of acrylic acid or methacrylic acid and copolymers thereof, polymers of maleic acid or phthalic acid and copolymers thereof, and cellulose derivatives such as carboxymethyl cellulose. , Gelatin, agar, etc., among which alkali metal alginate is preferable. The water-soluble polyanionic polymer has a molecular weight of 5,000.
0 to 10,000 is preferable, and particularly 10,000 from the viewpoints of barrier properties and production suitability aimed at in the present invention.
-40,000 is preferable. Examples of the polyvalent cation include salts of alkaline earth metals and other polyvalent metals (for example, CaC).
l ₂ , BaCl ₂ , Al ₂ (SO ₄ ) ₃ , ZnSO ₄
Etc.), polyamines (for example, ethylenediamine, diethylenetriamine, hexamethylenediamine, etc.) and polyimines are preferable.

Examples of other preferable intermediate layers in the present invention include an ion complex of a water-soluble polyanionic polymer and a water-soluble polycationic polymer. In this case, the various water-soluble polyanion polymers described above can be used as the water-soluble polyanion polymer.

As the water-soluble polycationic polymer, proteins having a plurality of reactive nitrogen-containing cationic groups, polypeptides such as polylysine, polyvinylamines, polyethyleneamines and polyethyleneimines are preferable.

When the intermediate layer is prepared using these materials, either the water-soluble polyanionic polymer or the polyvalent cation is used to form the intermediate layer in order to prevent rapid gelation during coating. It is preferable to apply by incorporating it into one of the heat-sensitive layers, but the temperature should be p
It is also possible to adjust H or to include the one material in the adjacent heat-sensitive layer.

The preferable coating amount of the intermediate layer is 0.05 g / m.
^{2 to 5} g / m ² , more preferably 0.1 g / m
^{2 to 2} g / m ² .

In the heat-sensitive layer of the present invention, at least the outermost heat-sensitive layer and the second heat-sensitive layer are required to be substantially transparent in order to improve color separation. Substantially transparent as used herein means haze (%) (manufactured by Nippon Seimitsu Kogyo Co., Ltd., integrating sphere method H).
It must be 60% or less if expressed by a TR meter). It is preferably 40% or less, more preferably 30% or less. However, light scattering based on fine irregularities on the surface of the heat-sensitive layer has a great effect on the transparency of the actual heat-sensitive layer test sample. Therefore, the transparency peculiar to the heat-sensitive layer to be a problem in the present invention, that is, when the transparency inside the heat-sensitive layer is measured by a haze meter, a transparent adhesive tape is attached onto the heat-sensitive layer as a simple method, Evaluation is performed by the value measured with surface scattering almost excluded.

The transparency as described above can be easily achieved by using a color developer or a coupler in the form of the emulsified dispersion.

On the outermost heat-sensitive layer of the heat-sensitive recording material of the present invention, it is preferable to substantially provide a protective layer for improving scratch resistance and preventing sticking. Two or more protective layers may be stacked. The transparent protective layer that can be used in the present invention comprises at least silicon-modified polyvinyl alcohol and colloidal silica.

The above silicon-modified polyvinyl alcohol is
It is not particularly limited as long as it contains a silicon atom in the molecule, but usually a silicon atom contained in the molecule is an ercoxyl group, an acyloxyl group or a hydroxyl group or its alkali metal salt obtained by hydrolysis or the like. It is preferable to use those having a reactive substituent of.
Details of such a method for producing a modified polyvinyl alcohol containing a silicon atom in the molecule are described in JP-A-58-193189.
No., published in Japanese Unexamined Patent Publication No.

The colloidal silica used in the present invention is used as a colloidal solution in which ultrafine particles of silicic acid anhydride are dispersed in water using water as a dispersion medium. The particles of colloidal silica have a size of 10 mμ to 100 mμ and a specific gravity of 1.1 to 1.
Three are preferred. In this case, a colloidal solution having a pH value of about 4 to about 10 is preferably used.

When the protective layer is provided on the surface of the heat-sensitive recording material, the surface scattering phenomenon is suppressed as in the case where the transparent adhesive tape is applied, and surprisingly the transparency of the protective layer is extremely good. Is. Moreover, since the mechanical strength of the surface of the heat-sensitive layer is improved, the transparency of the whole heat-sensitive material can be further improved.

A suitable blending ratio of the silicon-modified polyvinyl alcohol and the colloidal silica in the present invention is 0.5 to 3 parts by weight, more preferably 1 to 1 part by weight of the silicon-modified polyvinyl alcohol.
2 parts by weight. If the amount of colloidal silica used is less than 0.5 parts by weight, the effect of improving transparency is small, and if it is used in an amount of 3 parts by weight or more, the protective layer film is cracked and the transparency is rather lowered.

The transparent protective layer may further contain one or more polymers. Specific examples of the polymer that can be used in combination include methyl cellulose, carboxymethyl cellulose,
Hydroxymethylcellulose, starch, gelatin, gum arabic, casein, styrene-maleic anhydride copolymer hydrolyzate, styrene-maleic anhydride copolymer half ester hydrolyzate, polyvinyl alcohol, carboxy-modified polyvinyl alcohol, polyacrylamide derivative , Water-soluble polymers such as polyvinylpyrrolidone, sodium polystyrene sulfonate and sodium alginate, and styrene-butadiene rubber latex, acrylonitrile-butadiene rubber latex, methyl acrylate-
Examples thereof include water-insoluble polymers such as butadiene rubber latex and polyvinyl acetate emulsion. The amount used in combination is preferably 0.01 to 0.5 parts by weight with respect to 1 part by weight of silicon-modified polyvinyl alcohol.

Pigments, metal soaps, waxes, crosslinking agents and the like are added to the protective layer for the purpose of improving matching with the thermal head during thermal printing and improving water resistance of the protective layer.

The pigment has a refractive index of 1.4 to 1.55 and a particle size of 1 μm.
The following pigments are preferred. Specific examples thereof include calcium carbonate, talc, sekiseki, kaolin, aluminum hydroxide, and amorphous silica, and the addition amount thereof is 0.05 to 0.5 times the total weight of the polymer, particularly preferably 0.1. ~ 0.3 times the amount. When the amount is 0.05 times or less, it is ineffective for improving the matching property with the head, and when the amount is 0.5 times or more, the transparency and sensitivity of the heat-sensitive recording material are remarkably deteriorated and the commercial value thereof is impaired.

Examples of the metal soap include emulsions of higher fatty acid metal salts such as zinc stearate, calcium stearate and aluminum stearate, which are contained in an amount of 0.5 to 20% by weight, preferably 1 to 10% by weight based on the total weight of the protective layer. Added in quantity.

Examples of waxes include emulsions such as paraffin wax, microcrystalline wax, carnauba wax, methyl roll stearamide, polyethylene wax, and silicone, and the total weight of the protective layer is 0.5 to 40.
%, Preferably 1 to 20% by weight.

A surfactant is added to the coating solution for forming the protective layer in order to form the protective layer uniformly on the heat-sensitive layer. Surfactants include sulfosuccinic acid-based alkali metal salts, fluorine-containing surfactants, and the like.
Examples include sodium salts or ammonium salts of (2-ethylhexyl) sulfosuccinic acid, di- (n-hexyl) sulfosuccinic acid, and the like. Further, in the protective layer, a surfactant, a polymer electrolyte or the like for preventing the heat-sensitive recording material from being charged may be added.

The solid content of the protective layer is usually 0.2 to 5 g.
/ M ² is preferable, and more preferably 1 to 3 g / m ² .

In the present invention, an undercoat layer may be provided between the two layers in order to enhance the adhesion between the support and the heat sensitive layer. As a material for the undercoat layer, gelatin, synthetic polymer latex, nitrocellulose, or the like is used. The coating amount of the undercoat layer is preferably in the range of ^{0.1g / m 2 ~2.0g / m 2} , preferably in the range particularly ^{0.2g / m 2 ~1.0g / m 2} . If the amount is less than 0.1 g / m ² , the adhesion between the support and the heat-sensitive layer is not sufficient, and even if the amount exceeds 2.0 g / m ² , the adhesion between the support and the heat-sensitive layer reaches saturation. Therefore, there is a cost disadvantage.

When the heat-sensitive layer is coated on the undercoat layer, the image quality recorded on the heat-sensitive layer may be deteriorated if the water contained in the coating solution swells the undercoat layer. It is desirable to cure with a hardener. The following hardening agents can be used in the present invention.

(1) Divinisulfone-N, N'-ethylenebis (vinylsulfonylacetamide), 1,3-bis (vinylsulfonyl) -2-propanol, methylene bismaleimide, 5-acetyl-1,3-di Acryloyl-hexahydro-s-triazine, 1,3,5-triacryloyl-hexahydro-s-triazine, 1,3,3
Active vinyl compounds such as 5-trivinylsulfonyl-hexahydro-s-triazine.

(2) 2,4-dichloro-6-hydroxy-s-triazine sodium salt, 2,4-dichloro-
6-methoxy-s-triazine, 2,4-dichloro-6
-(4-sulfoanilino) -s-triazine sodium salt, 2,4-dichloro-6- (2-sulfoethylamino) -s-triazine, N-N'-bis (2-chloroethylcarbamyl) piperazine Active halogen compounds such as.

(3) Bis (2,3-epoxypropyl)
Methylpropylammonium p-toluenesulfonate, 1,4-bis (2 ′, 3′-epoxypropyloxy) butane, 1,3,5-triglycidyl isocyanurate, 1,3-diglycidyl-5- (γ -Acetoxy-
Epoxy compounds such as β-oxypropyl) isocyanurate.

(4) Ethyleneimino compounds such as 2,4,6-triethylene-s-triazine, 1,6-hexamethylene-NN′-bisethyleneurea and bis-β-ethyleneiminoethylthioether.

(5) Methanesulfonic acid ester compounds such as 1,2-di (methanesulfonoxy) ethane, 1,4-di (methanesulfonoxy) butane and 1,5-di (methanesulfonoxy) pentane.

(6) dicyclohexylcarbodiimide,
1-cyclohexyl-3- (3-trimethylaminopropyl) carbodiimide-p-toluenesulfonate, 1
Carbodiimide compounds such as ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride.

(7) Isoxazoles such as 2,5-dimethylisoxazole perchlorate, 2-ethyl-5-phenylisoxazole-3'-sulfonate and 5,5 '-(paraphenylene) bisisoxazole Compounds.

(8) Chromium Inorganic compounds such as alum and chromium acetate.

(9) Dehydration condensation type peptide reagents such as N-carbethoxy-2-isopropoxy-1,2-dihydroquinoline and N- (1-morpholinocarboxy) -4-methylpyridinium chloride; N, N'- Active ester compounds such as adipoyldioxydisuccinimide and N, N'-terephthaloyldioxydisuccinimide.

(10) Isocyanates such as toluene-2,4-diisocyanate and 1,6-hexamethylene diisocyanate.

(11) Glutaraldehyde, glyoxal, dimethoxyurea, 2,3-hydroxy-1,4-
Dialdehydes such as dioxane.

Of these, glutaraldehyde,
Dialdehydes such as 2,3-dihydroxy-1,4-dioxane and boric acid are preferred.

The addition amount of these hardeners is in the range of 0.20% to 3.0% by weight, based on the weight of the undercoat material, and is an appropriate addition amount according to the coating method and the desired degree of curing. You can choose. If the added amount is less than 0.20% by weight, the degree of curing will be insufficient no matter how much the material is aged and the undercoat layer will swell when the heat-sensitive layer is applied. On the other hand, if the amount is more than 3.0% by weight, the degree of curing will be too advanced and the adhesion between the undercoat layer and the support will be rather deteriorated, and the undercoat layer will become a film and peel off from the support. . Depending on the curing agent used, if necessary, caustic soda or the like may be further added to bring the pH of the solution to the alkaline side, or the pH of the solution may be brought to the acidic side with citric acid or the like.

It is also possible to add an antifoaming agent to eliminate bubbles generated during coating, or to add an activator to improve the leveling of the liquid and prevent the generation of coating streaks. . Further, an antistatic agent can be added if necessary. Further, the undercoat layer may be made opaque by adding a white pigment.

Before applying the undercoat layer, it is desirable to activate the surface of the support by a known method. As the activation method, etching treatment with acid, flame treatment with a gas burner, corona discharge treatment, glow discharge treatment, or the like is used, but from the viewpoint of cost or simplicity, US Pat. No. 075, No. 2, 8
No. 46,727, No. 3,549,406, No. 3,
The corona discharge treatment described in, for example, No. 590,107 is most preferably used.

The coating solution according to the present invention is generally well known, for example, dip coating method, air knife coating method, curtain coating method, roller coating method, doctor coating method, wire bar coating method, slide coating method, Gravure coating method or US Pat. No. 2,681,
It can be applied by an extrusion coating method using a hopper described in Japanese Patent No. 294. As required, US Pat. Nos. 2,761,791 and 3,3
508, 947, 2,941, 898, and 3,526, 528, and the method described in Yuji Harasaki, "Coating Engineering", page 253 (published by Asakura Shoten in 1973). It is also possible to divide the coating into two or more layers and simultaneously coat them, and an appropriate method can be selected according to the coating amount, coating speed and the like.

It is necessary to appropriately add a pigment dispersant, a thickener, a flow modifier, an antifoaming agent, a foam suppressor, a release agent, and a colorant to the coating liquid used in the present invention, if necessary. It doesn't matter as long as it doesn't hurt.

The multicolor heat-sensitive recording material of the present invention can be used as a multicolor sheet for a printer of a facsimile or an electronic computer which requires high speed recording. In this case, in the case of the present invention in which a diazo compound is used as a color-forming component, providing an exposure zone for photodecomposition is particularly advantageous for preservation of images and multicoloring.

The arrangement of the print head and the exposure zone is roughly classified into two types. First, after printing once, light irradiation for photolysis is performed, and before and after this light irradiation, the recording material feeding mechanism puts the recording material in a print standby state so that it can be printed again at the place where it was once printed. Returning, then printing again, the recording material returns to its original position, so-called 1
It is a head multi-scan method. Another method is a so-called multi-head one-scan method in which recording heads are provided for the number of colors to be recorded and light irradiation zones are provided between them, and both methods may be combined as necessary.
Further, as the light source for photolysis, various light sources that emit light of a desired wavelength can be used, for example, various fluorescent lamps, xenon lamps, xenon flash lamps, mercury lamps of various pressures, photographic flashes, strobes, etc. Various light sources can be used. Further, in order to make the optical fixing zone compact, the light source section and the exposure section may be separated by using an optical fiber.

In the multicolor heat-sensitive recording material of the present invention, each heat-sensitive layer is caused to develop any one of the hues of Y (yellow), M (cyan) and C (cyan), so that a full-color image is obtained as a whole. However, the order of C, Y, M or C, M, Y from the support side is preferable from the viewpoint of color reproducibility.

The present invention will be specifically described with reference to the examples, but the embodiment of the present invention is not limited thereto. Unless otherwise specified, “parts” means “parts by weight”.

[0158]

Example 1 Anatase-type titanium dioxide was added to low-density polyethylene 10 times.
A polyethylene film having a thickness of 50 μm containing 50% by weight was prepared and used as a plastic film on the side to which the multicolor thermosensitive recording layer was applied.

Next, wood pulp consisting of 40 parts of LBSP and 60 parts of LBKP was beaten with a disc refiner to a Canadian freeness of 300 cc, and 0.5 parts of epoxidized behenic acid amide and 1.
0 part, aluminum sulfate 1.0 part, polyamide polyamine epichlorohydrin 0.1 part, and cationic polyacrylamide 0.5 part were all added in an absolute dry weight ratio to pulp, and a base paper having a basis weight of 100 g / m ^{2 was} obtained using a Fourdrinier paper machine. Was made. The density was adjusted to 1.0 by a calendering process.

Next, a polyurethane two-pack type adhesive having the following composition was applied to one side of the polyethylene film at 3 g / m.
^It was applied so as to be ² and dried at 100 ° C. for 2 minutes, and the above base paper was combined and thermocompression bonded at a pressure of 20 kg / cm at 40 ° C.

Adhesive 100 parts of Polybond AY-651A (manufactured by Sanyo Chemical Industry Co., Ltd.) 15 parts of Polybond AY-651C (manufactured by Sanyo Chemical Industry Co., Ltd.)

Corona discharge treatment was performed on the side of the substrate prepared as described above opposite to the surface on which the plastic film was adhered. Then, using a melt extruder, high density polyethylene was coated to a resin thickness of 30 μm to form a resin layer composed of a matte surface (this surface is referred to as a back surface).
After corona discharge treatment on the polyethylene resin coated surface of the back side, aluminum oxide (Alumina sol 100 manufactured by Nissan Chemical Industries) / silicon dioxide (Snowtex 0 manufactured by Nissan Chemical Industries) = 1/2 (weight ratio) as water is used as an antistatic agent. And was applied to 0.2 g / m ² by the weight after drying.

Example 2 A polyethylene terephthalate film having a thickness of 12 μm was melt-extruded and adjusted by a biaxial stretching method to prepare a plastic film for coating a multicolor heat-sensitive recording layer. This plastic film was used in the same procedure as in Example 1. It was adhered to the base paper produced in step 1 by the same procedure.

Next, after corona discharge treatment was applied to the side opposite to the side of the substrate on which the plastic film was adhered, high density polyethylene was coated using a melt extruder to a resin thickness of 30 μm, and a resin consisting of a matte surface was formed. A layer was formed (this side is called the back side).

Corona discharge treatment was applied to the surface to which the plastic film was adhered, and a low density polyethylene containing 10% by weight of anatase type titanium dioxide and a trace amount of ultramarine was used to obtain a resin thickness of 30 μm using a melt extruder. Melt extrusion coating was performed to form a resin layer having a glossy surface (this surface is referred to as a front surface).

Thereafter, the back surface was subjected to corona treatment in the same manner as in Example 1, and then an antistatic agent was applied to obtain a sample.

Example 3 The conditions under which the surface of the base paper on which the heat-sensitive recording layer was applied and the plastic film were adhered were a temperature of 80 ° C. and a pressure of 20 kg / c.
A sample was prepared in the same manner as in Example 2 except that the condition for heating and pressure bonding was changed to m.

Example 4 A sample was prepared in the same manner as in Example 2 except that the method of adhering the surface of the base paper on which the heat-sensitive recording layer was applied to the plastic film was changed to the method of adhering with molten high-density polyethylene.

Specifically, a high-density polyethylene was melt extruded at 220 ° C. while continuously drawing a 12 μm-thick polyethylene terephthalate film prepared by the melt extrusion biaxial stretching method and the base paper, and a multicolor heat-sensitive recording layer of the base paper was obtained. The polyethylene terephthalate film was adhered to the surface on the side to be coated with a nip roll and a cooling roll.

Example 5 A sample was prepared in the same manner as in Example 2 except that polyethylene was not melt-extruded and coated on the surface of the plastic film.

Comparative Example 1 Wood pulp consisting of 40 parts of LBSP and 60 parts of LBKP was made into Canadian Freeness 3 by a disc refiner.
Beat to 00cc and epoxidize behenamide 0.5
Parts, 1.0 part of anionic polyacrylamide, 1.0 part of aluminum sulfate, 0.1 part of polyamide polyamine epichlorohydrin, and 0.5 part of cationic polyacrylamide were all added at an absolute dry weight ratio to the pulp, and the area was measured by a Fourdrinier paper machine. A base paper having an amount of 100 g / m ² was produced. Moreover, the density was adjusted to 1.0 by a calendering process.

Next, both sides of the base paper were subjected to corona discharge treatment, and then high density polyethylene was coated to a resin thickness of 30 μm using a melt extruder to form a resin layer consisting of a matte surface (this surface Called the face).

Next, low-density polyethylene containing 10% by weight of anatase type titanium dioxide and a trace amount of ultramarine blue was melted to a resin of 30 μm on the side opposite to the surface on which the resin layer was formed, using a melt extruder. A resin layer composed of a glossy surface was formed by extrusion coating (this surface is called a front surface).

After the corona discharge treatment was applied to the polyethylene resin coated surface on the back side, aluminum oxide (Alumina sol 100 manufactured by Nissan Chemical Industries) / silicon dioxide (Snowtex 0 manufactured by Nissan Chemical Industries) as an antistatic agent = 1/2 (weight ratio ) Was dispersed in water and the weight after drying was applied at 0.2 g / m ² .

Comparative Example 2 A sample was prepared in the same manner as in Comparative Example 1 except that the resin thickness on the front and back surfaces formed by melt extrusion was 50 μm.

Comparative Example 3 A sample was prepared in the same manner as in Example 2 except that the resin coating on the front and back surfaces by melt extrusion was not performed.

Comparative Example 4 A 135 μm-thick polyethylene terephthalate film containing 10% by weight of anatase-type titanium dioxide was prepared by melt-extrusion biaxial stretching method and used as a support.

Corona discharge was applied to the supports of Examples 1 to 5 and Comparative Examples 1 to 4 thus obtained, and then the following full-color thermosensitive recording layers were provided. An example of producing a full-color thermosensitive recording material will be shown below. (1) Preparation of cyan thermal recording layer liquid (preparation of capsule liquid containing an electron-donating dye precursor) Solution A 3- (o-methyl-p-dimethylaminophenyl) -3
-(1'-Ethyl-2'-methylindol-3-yl) phthalide (electron donating dye precursor) was added to ethyl acetate 2
After dissolving in 0 part, 20 parts of alkylnaphthalene (high boiling point solvent) was added thereto, and heated to uniformly mix.

To the obtained solution, 20 parts of a 1/3 adduct of xylylene diisocyanate / trimethylolpropane was added and uniformly stirred to prepare a solution A.

2. Solution B Liquid B was prepared by adding 2 parts by weight of a 2% by weight aqueous solution of sodium dodecyl sulfonate to 54 parts of a 6% by weight aqueous solution of phthalated gelatin.

Solution A was added to solution B, and the mixture was emulsified and dispersed using a homogenizer to obtain an emulsion dispersion. 68 parts of water is added to the obtained emulsified dispersion, mixed and homogenized, and then the mixture is heated to 50 ° C. while stirring to encapsulate the microcapsules so that the average particle size of the microcapsules becomes 1.2 μm. The reaction was performed for 3 hours to obtain a capsule liquid.

(Preparation of color developer emulsion dispersion) 1,1- (p
5 parts of -hydroxyphenyl) -2-ethylhexane (developing agent), 0.3 parts of tricresyl phosphate and 0.1 part of diethyl maleate were dissolved in 10 parts of ethyl acetate. The obtained solution was used as a 6% by weight gelatin aqueous solution 50
g and 2 g of a 2 wt% sodium dodecyl sulfonate aqueous solution were added to a mixed solution, and the mixture was emulsified for 10 minutes using a homogenizer to obtain an emulsified dispersion.

(Preparation of coating liquid) The weight ratio of the capsule liquid containing the electron-donating dye precursor to the color developer emulsion dispersion is 1 /.
A coating solution was obtained by mixing so as to obtain 4.

(2) Preparation of magenta thermosensitive recording layer liquid (preparation of capsule liquid containing diazo compound) 4-N-
2.0 parts of (2- (2,4-di-tert-amylphenoxy) butyryl) piperazinobenzenediazonium hexafluorophosphate (diazo compound: decomposed by light having a wavelength of 365 nm) 2.0 parts were dissolved in 20 parts of ethyl acetate. After that, 20 parts of alkylnaphthalene was further added and heated to uniformly mix. To the obtained solution, 15 parts of an adduct (capsule wall material) of xylidine isocyanate / trimethylolpropane 1/3 was added and uniformly mixed to obtain a diazo compound solution.

The solution of the obtained diazo compound was added to a mixed solution of 54 parts of a 6% by weight aqueous solution of phthalated gelatin and 2 parts of a 2% by weight aqueous solution of sodium dodecylsulfonate, and the mixture was emulsified and dispersed using a homogenizer. .

68 parts of water was added to the obtained emulsified dispersion liquid and mixed uniformly, and the mixture was heated to 40 ° C. with stirring to carry out an encapsulation reaction for 3 hours so that the average particle diameter of the capsules became 1.2 μm. Then, a capsule solution was obtained.

(Preparation of Coupler Emulsion Dispersion) 1- (2 '
-Octylphenyl) -3-methyl-5-pyrazolone (coupler) 2 parts, 1,2,3-triphenylguanidine 2 parts, tricresyl phosphate 0.3 parts and diethyl maleate 0.1 part and ethyl acetate 10. Dissolved in parts. The obtained solution was mixed with 50 g of a 6% by weight aqueous solution of gelatin.
And 2 g of a 2% by weight aqueous solution of sodium dodecyl sulfonate
Was added to the mixed aqueous solution, and then emulsified for 10 minutes using a homogenizer to obtain an emulsified dispersion.

(Preparation of Coating Solution) A capsule solution containing a diazo compound / a coupler emulsion was mixed at a weight ratio of 2/3 to obtain a coating solution.

(3) Preparation of Yellow Thermosensitive Recording Layer Liquid (Preparation of Capsule Liquid Containing Diazo Compound) 2,5-
Dibutoxy-4-tolylthiobenzene diazonium hexafluorophosphate (diazo compound: 420 nm
3.0 parts were dissolved in 20 parts of ethyl acetate, and alkylnaphthalene 2 was added as a high boiling point solvent.
0 parts were added and mixed by heating.

To the resulting solution was added 1 part of xylylene diisocyanate / trimethylol propane as a capsule wall agent.
15 parts of the / 3 adduct was added and mixed uniformly to obtain a diazo compound solution.

The solution of the obtained diazo compound was added to a mixed solution of 54 parts of a 6% by weight aqueous solution of phthalated gelatin and 2 parts of an aqueous solution of sodium dodecylsulfonate, and the mixture was emulsified and dispersed using a homogenizer.

68 parts of water was added to the obtained emulsified dispersion, and the homogeneously mixed solution was heated to 40 ° C. with further stirring,
The encapsulation reaction was carried out for 3 hours so that the average particle size of the capsules became 1.3 μm to obtain a capsule solution.

(Preparation of coupler emulsion dispersion) 2-chloro-5- (3- (2,4-di-tert-pentyl) phenoxypropylamino) acetoacetanilide 2 parts,
1 part of 1,2,3-triphenylguanidine, 0.3 part of tricresyl phosphate and 0.1 part of diethyl maleate
Parts in 10 parts of ethyl acetate, 6% by weight of gelatin
50 g of the aqueous solution and 2 g of a 2% by weight aqueous solution of sodium dodecyl sulfonate were added to the mixed solution and emulsified for 10 minutes using a homogenizer to obtain an emulsified dispersion.

(Preparation of Coating Liquid) A capsule liquid containing a diazo compound / a coupler emulsion dispersion was mixed at a weight ratio of 2/3 to obtain a coating liquid.

(4) Preparation of Intermediate Layer Liquid Polyacrylic acid (trade name JULIMER AC-10L: manufactured by Nippon Pure Chemical Co., Ltd.) was added to 10 parts of 15% by weight aqueous solution of gelatin (# 750: trade name of Nitta Gelatin Co., Ltd.). ) Of 15
A 3% by weight aqueous solution was added and uniformly mixed to obtain an intermediate layer liquid.

(5) Preparation of protective layer liquid Itaconic acid-modified polyvinyl alcohol (KL-318:
100 g of 6 wt% aqueous solution of Kuraray Co., Ltd.)
40 wt% zinc stearate dispersion (Hydrin Z: manufactured by Chukyo Yushi Co., Ltd.) was mixed with 10 g of a 30 wt% dispersion of epoxy-modified polyamide (FL-71: trade name of Toho Kagaku Co., Ltd.). (Trade name) 15 g was added to obtain a protective layer liquid.

(6) Preparation of Thermosensitive Recording Material On the polymer layer of each support of Examples 1 to 5 and Comparative Example, using a slide type hopper type bead coating device, cyan heat sensitivity was sequentially applied to the support from the support. A multi-layered thermal recording material was obtained by applying multi-layer multilayer coating so as to form a recording layer liquid, an intermediate layer liquid, a magenta thermosensitive recording layer liquid, an intermediate layer liquid, a yellow thermosensitive recording layer liquid and a protective layer liquid.

The coating amount is 6.1 g / m ^{2 for} the cyan heat-sensitive recording layer, 1.0 g / m ^{2 for} the intermediate layer and 7.8 g / m for the magenta heat-sensitive recording layer in terms of solid content after drying, from the support side. m
^2. Each coating solution was applied such that the intermediate layer became 1.0 g / m ² , the yellow heat-sensitive recording layer became 7.2 g / m ^2, and the protective layer became 2.0 g / m ² .

A recording material obtained by using a thermal head KST type (trade name, manufactured by Kyocera Corporation) and adjusting the applied power and the pulse width so that the recording energy per unit area was 34 mJ / mm ^2. A yellow image was recorded on.

Then, the yellow thermosensitive recording layer was optically fixed by exposing it to an ultraviolet lamp having an emission center wavelength of 420 nm and an output of 40 W for 10 seconds, and then the applied energy and pulse width were adjusted so that the recording energy of the thermal head became 68 mJ / mm ^2. Was adjusted to record a magenta image.

Further, the emission center wavelength is 365 nm and the output is 4
After exposing the magenta thermosensitive recording layer to light for 15 seconds by exposing it to a 0 W ultraviolet lamp, a cyan image was recorded by adjusting the applied power and the pulse width so that the recording energy of the thermal head was 102 mJ / mm ² .

In this manner, in addition to the yellow, magenta, and cyan color-developed images, the image portion where the yellow and magenta recordings overlap is red, the image portion where the magenta and cyan recordings overlap is blue, and the yellow The portion where the recordings of cyan and cyan overlap was colored green, and the portion of the image where the recordings of yellow, magenta, and cyan overlap were colored black. The textures were compared by comparing the feels held in the hands, and those with a certain degree of waist but suppleness were marked with a circle, and those without a waist and lacking flexibility were marked with a cross. In addition, the image uniformity was visually evaluated, and the symbol “◯” indicates that there is no image unevenness and the image uniformity is excellent, and the symbol “x” indicates that the image unevenness is observed and the image uniformity is poor. The symbol Δ indicates that the image uniformity is at a level intermediate between those of the symbols ○ and Δ.

The adhesion between the support and the multicolor thermosensitive recording layer was evaluated as follows. A tape was attached to the recording layer surface of the multicolor thermosensitive recording material at a constant pressure, and the degree of peeling of the thermosensitive layer when the tape was peeled off was visually evaluated. Those that did not peel at all were marked with ◯, those that peeled slightly were marked with Δ, and those with a large degree of peeling were marked with X.

The curl was evaluated as follows. A circular support with a diameter of 10 cm was punched out at 20 ° C 6
After adjusting the humidity in an atmosphere of 5%, the warp height of the end face from the bottom face of the support was measured. If you want to curl with the surface (front surface) on which the thermal recording layer is applied facing inward, add curl,
When curling with the front surface facing outward, the curl value was obtained by adding a sign to the amount of warp as a negative curl. The curl value of the support is preferably -10 mm to ± 0 mm.

Table 1 shows the support constitutions of Examples 1 to 5 and Comparative Examples 1 to 4 and the evaluation results of the multicolor heat-sensitive recording materials using this support.

[0206]

[Table 1]

Examples 1 to 5 of the present invention are sheet-like substrates obtained by laminating a plastic film on a base paper by dry lamination or hot melt lamination, and are excellent in feeling and in uniformity of image quality. On the other hand, Comparative Examples 1 and 2 have good texture because they are adhered to the base paper by the melt extrusion coating of the plastic film, but the image quality is inferior, and Comparative Example 3 is opposite to the surface on which the plastic film is bonded. Since the resin layer is not provided on the side by the melt extrusion method, the curl balance is inferior. In Comparative Example 4, the plastic film itself constitutes the substrate, so the image quality is excellent, but the texture is good. Inferior.

[0208]

The support in the multicolor heat-sensitive recording material of the present invention has the same flexibility and texture as a support in which a polyolefin layer is formed on a conventional base paper by a melt extrusion method, and is flat and glossy. It is excellent in heat resistance, and by using this, a multicolor heat-sensitive recording material having particularly excellent image uniformity can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view for explaining a heat-sensitive recording material of the present invention.

[Explanation of symbols]

1 is a support, 2 is a transparent cyan coloring layer, 3 is an intermediate layer, 4
Is a transparent yellow coloring layer, 5 is an intermediate layer, 6 is a transparent magenta coloring layer, and 7 is a transparent protective layer.

Claims (2)

[Claims] 1. A multicolor heat-sensitive recording material comprising two or more heat-sensitive recording layers provided on a support, wherein the support comprises a plastic film on the side of the base paper on which the heat-sensitive recording layer is provided via an adhesive. A multicolor thermosensitive recording material, comprising a melt-extruded thermoplastic resin layer on at least the surface of the laminated sheet-like substrate opposite to the surface on which the thermosensitive recording layer is provided. 2. The multicolor thermosensitive recording material according to claim 1, wherein a melt-extruded thermoplastic resin layer is provided between the plastic film of the sheet-shaped substrate and the thermosensitive recording layer.