JPH06336079A - Multicolor thermal recording material - Google Patents

Abstract

PURPOSE:To obtain excellent image uniformity, in a structure wherein a support having thermoplastic resin layers provided to both surfaces thereof is provided on a substrate composed of a white plastic film, by specifying the density of the white plastic film and the ratio of stiffness to the thickness of the support. CONSTITUTION:In a full-color thermal recording material, a support 1 having thermoplastic resin layers provided to both surfaces thereof by a melt extrusion method is provided on a substrate composed of a white plastic film and a multicolor thermal recording layer is applied to the support 1. That is, a transparent cyan thermal layer 2, a transparent yellow thermal layer 4 and a transparent magenta thermal layer 6 are successively laminated on the support 1 through intermediate layers 2, 5 and a transparent protective layer 7 is provided on the thermal layer 6 to form the multicolor thermal recording layer. In this case, the density of the white plastic film is set to 0.6-1.3g/cm<3> and the E value [=S/T<3> wherein S is the stiffness (gf/cm) of the support 1 prescribed by JIS 8125 and T is the thickness (mm) of the support is set to 400-1600.

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, and more particularly to a support thereof.
The present invention relates to a support for a multicolor heat-sensitive recording material, which is excellent in image uniformity, is excellent in handleability at the time of printing and viewing, and is excellent in flexibility, smoothness, glossiness and curl.

[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. Japanese Examined Sho 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 having a support provided with a thermoplastic resin layer on both sides of a substrate made of a white plastic film by a melt extrusion method. E value density of ^{0.6g / cm 3 ~1.3g / cm 3} , and is defined by the following formula of the support 400 to 1600
It was achieved by coating a multicolor thermosensitive recording layer on a support in the range of.

[0010] However, S represents the stiffness (gf · cm) of the support defined by JIS8125, and T represents the thickness (mm) of the support.

The present invention will be described in detail below. The substrate used for the support of the present invention is a white plastic film, and since a thermoplastic resin is applied by a melt extrusion method, heat resistance is required, and mainly polyester resin, polystyrene resin, and vinyl chloride resin are used. Is desirable. A polyester resin is particularly preferable.

In particular, the surface roughness of the substrate affects the smoothness and glossiness of the support provided with the thermoplastic resin in the melt extrusion method. Therefore, as the surface roughness of the substrate, the center surface average roughness (SRa) defined below is 0.3 μm.
The following is desirable. Particularly preferably 0.2 μm
It is the following.

From the roughness curved surface, a portion having an area SM is extracted on the center plane, the orthogonal coordinate axes, the X axis, and the Y axis are placed on the center plane of the extracted portion, and the axis orthogonal to the center plane is set as the Z axis. At this time, the value given by the following formula is defined as the center surface average roughness (SRa) and expressed in μm.

[0014]

[Equation 1]

However, LX · LY = SM Z = f (X, Y) center plane average roughness is measured by using, for example, a three-dimensional surface roughness measuring instrument (SE = 3AK) manufactured by Kosaka Laboratory Ltd. Radius 2 μm
Cut off with a diamond needle of 0.25 mm or more, horizontal magnification 10 times, height magnification 2
It can be determined by measuring an area of 80 mm ^{2 at} a magnification of 000.

The density of the substrate is 0.6 g / cm ³ to
It should be 1.3 g / cm ³ , and if it is lower than 0.6 g / cm ^3, the support on which the thermoplastic resin is melt-extruded and coated has low rigidity and poor handleability, and cohesive failure of the substrate during development processing and the like. It occurs and is not preferable. When it is higher than 1.3 g / cm ³ , knicks and the like are likely to occur during handling, and it is more rigid than the conventional support obtained by melt-extruding the thermoplastic resin on the base paper, which is not preferable. More preferably 0.
Is ^{8g / cm 3 ~1.2g / cm 3} .

As a specific example of the substrate of the present invention, Japanese Patent Laid-Open No.
No. 3-235338, JP-A-3-76727, a method of forming an void (fine air bubble) by stretching an inorganic white pigment in the polyester and stretching, JP-B-54
The polyester described in No. 29550 may be mixed with another resin such as polystyrene to form a void, but the present invention is not limited thereto.

The electrical resistance of the surface of the white plastic film of the substrate is 1 × 10 in order to prevent electrostatic charge failure such as dust adhesion and coating unevenness during melt extrusion of the thermoplastic resin.
It is preferably ¹⁰ Ω · cm or less. Particularly preferable means for reducing the surface electric resistance, which is 7 × 10 ⁹ Ω · cm or less, is an ionic organic antistatic agent such as an alkali metal salt of a polymerizable carboxylic acid, or an electron conductive antistatic layer such as tin oxide. It is possible to use a generally known technique such as providing The thickness of the substrate is not particularly limited, but is 30
μm to 300 μm, preferably 70 μm to 200 μm
It is about m.

The thermoplastic resin in the thermoplastic resin layer formed by coating on the substrate is preferably a polyolefin resin, and examples thereof include α-olefin homopolymers 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 and can be determined according to the thickness of the polyolefin coating layer of the conventional photographic paper support, but usually 10
μm to 50 μm is preferable.

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 blending amount of the white pigment are known. Can be selected as appropriate. Further, it is possible to add known additives such as a fluorescent whitening agent and an antioxidant.

As the extrusion coating equipment for extrusion coating the polyolefin, an ordinary extruder for polyolefin and a laminator are used. In addition, before the thermoplastic resin layer is extruded and coated on the substrate, it is preferable to pretreat the substrate 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, primer 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.

Further, in order to improve the adhesiveness between the 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.

On the back side of the substrate, a pigment-free thermoplastic resin layer is usually provided by a melt extrusion coating method or the like for the purpose of achieving curl balance. Especially polyethylene is 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 approximate the texture of a conventional support made of base paper, the support having thermoplastic resin layers on both sides of the substrate in the present invention is defined by JIS8125 shown in the following formula. It has been found that it is desirable that the E value of the stiffness of the support divided by the cube of the thickness of the support is in the range of 400 to 1600. However, S represents the stiffness of the support [gf · cm], and T represents the thickness of the support [mm].

When 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.
Further, it is not preferable because it is more rigid than the conventional support in which polyethylene is coated on the base paper by the melt extrusion method.
The range of E value is more preferably 500 to 1500,
More preferably, it is 600-1400.

A multicolor heat-sensitive recording layer is coated on the support of the present invention which has been formed and whitened as described above. in this case,
If necessary, a surface activation treatment such as corona discharge and / or an undercoat layer can be applied prior to coating.

On the polyester coating layer of the support obtained as described above, a heat-sensitive recording layer can be coated as described below to obtain a support excellent in whiteness, glossiness and image uniformity. it can. The thermal recording layer will be described.

FIG. 1 shows a multicolor heat-sensitive material in which a transparent cyan heat-sensitive layer, a transparent yellow heat-sensitive layer and a transparent magenta heat-sensitive layer are sequentially laminated on one surface of a support, and a transparent protective layer is provided thereon. It is a recording material. In this case, the coloring system of at least the magenta heat-sensitive layer and the yellow heat-sensitive layer is a diazo system,
The cyan heat-sensitive layer may or may not be a diazo type. 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 colored magenta 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, a larger amount of heat energy than that used in the above-mentioned thermal recording is applied to cause the second heat-sensitive layer to develop a yellow color, and
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, since cyan, magenta, and yellow can be independently colored, 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 the innermost heat-sensitive layer does not adversely affect the color reproduction even if it is opaque.

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. When two or more developers are used in combination, the solubility increases, which is preferable.

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

[0038]

[Chemical 1]

M = 0 to 2, n = 2 to 11

[0040]

[Chemical 2]

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.

[0042]

[Chemical 3]

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.

[0044]

[Chemical 4]

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 which will be described later called a coupler 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 coloring hue can be easily changed by changing the chemical structure of the diazo compound or the chemical structure of the coupler, and almost any coloring hue can be obtained depending on the combination. .

The photodecomposable diazo compound as used 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 or a diazoamino compound. Hereinafter, a diazonium salt will be mainly described as an example.

It is generally said that the photolysis wavelength of the diazonium salt is its absorption maximum wavelength. It is known that the absorption maximum wavelength of diazonium salt changes from about 200 nm to about 700 nm depending on its chemical structure ("Photolysis and chemical structure of photosensitive diazonium salt" written by Takahiro Tsunoda and Aio Yamaoka, Japan. Journal 29 (4) 197-205 (1965)).

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.

Among 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 etc. 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),

[0054]

[Chemical 5]

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

[0056]

[Chemical 6]

[0057]

[Chemical 7]

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

[0059]

[Chemical 8]

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.

A large number of 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
A benzenediazosulfonate 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 using these diazosulfonate compounds, 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. The diazoamino compound is a compound obtained by coupling the diazo group with dicyandiamide, sarcosine, methyltaurine, N-ethylanthranic acid-5-sulphonic acid, monoethanolamine, diethanolamine, guanidine and the like.

The coupler used in the present invention is a coupler which 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 of any 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 when heated 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.
The coupler is 0.1-10 with respect to 1 part by weight of the diazo compound.
It is preferable to use 0.1 part by weight and 20 parts by weight of the basic substance.

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,
Examples thereof include polyvinyl alcohol. In the present invention, two or more of these polymer substances may be used in combination. In the present invention, among the above polymeric 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 may be prepared 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 to form microcapsules. 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 not destroyed. It can react through the walls of the microcapsules.

In the present invention, it is possible to use a color forming auxiliary agent. 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 coloring aid 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 high boiling point oils. Particularly, it is known as esters and pressure-sensitive oils and has two or more benzene rings and has 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, tritoluylmethane, toluyldiphenylmethane), terphenyl compounds, alkyl compounds (eg, terphenyl), alkylated They are 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.

[0077]

[Chemical 9]

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.

[0079]

[Chemical 10]

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.

[0081]

[Chemical 11]

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), dioctyl tetrahydrophthalate, 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, oxalate ester (dibutyl oxalate, dipentyl oxalate), diethyl malonate, maleate 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,
Examples thereof include 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 surfactant to be contained in the aqueous phase, anionic or nonionic surfactants
A substance that does not cause precipitation or aggregation by acting on the protective colloid can be appropriately selected and used. Preferable surfactants include sodium alkylbenzene sulfonate (for example, sodium lauryl sulfate), dioctyl sodium sulfosuccinate, polyalkylene glycol (for example, polyoxyethylene nonylphenyl 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, etc. 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 μ or less. More preferably 0.1
It is within the range of 5μ.

Alternatively, the ratio of the oil phase to the 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. On the contrary, if it is 0.6 or more, the viscosity of the liquid becomes high, resulting in inconvenience in handling and reduction in transparency.

In the present invention, in addition to the above materials, citric acid, tartaric acid, oxalic acid, boric acid, phosphoric acid, pyrophosphoric acid, etc. 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 rubber, gelatin, polyvinyl pyrrolidone, casein, styrene-butadiene latex, acrylonitrile-butadiene latex, polyvinyl acetate, polyacrylic acid ester, ethylene-vinyl acetate copolymer. It is possible to use various emulsions such as 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 can be seen, 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 ), polyamines (eg ethylenediamine, diethylenetriamine, hexamethylenediamine, etc.) and polyimines are preferable.

Other preferable examples of the intermediate layer 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, polyethyleneimines and the like are preferable.

When the intermediate layer is prepared using these materials, either the water-soluble polyanionic polymer or the polyvalent cation material is used for the heat-sensitive layer adjacent to each other 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. Preferred coating weight of the intermediate layer is ^{0.05g / m 2 ~5g / m 2} , more preferably from ^{0.1g / m 2 ~2g / m 2} . In the heat-sensitive layer in the 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. The term "substantially transparent" as used herein must be 60% or less in terms of haze (%) (measured by integrating sphere method HTR meter manufactured by Nippon Seimitsu Kogyo Co., Ltd.). Preferably 4
It is 0% or less, and more preferably 30% or less. However, the actual transparency of the heat-sensitive layer test sample is greatly affected by light scattering due to fine irregularities on the surface of the heat-sensitive layer. 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, a protective layer is preferably provided to improve scratch resistance and prevent sticking. Two or more protective layers may be laminated. The transparent protective layer that can be used in the present invention comprises at least silicon-modified polyvinyl alcohol and colloidal silica. The silicon-modified polyvinyl alcohol is not particularly limited as long as it contains a silicon atom in the molecule, but usually the silicon atom contained in the molecule is obtained by an ercoxyl group, an acyloxyl group or hydrolysis. It is preferable to use one having a reactive substituent such as a hydroxyl group or an alkali metal salt thereof. Details of such a method for producing a modified polyvinyl alcohol containing a silicon atom in the molecule are described in JP-A-58-58.
It is described in Japanese Patent No. 193189.

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.
3 is preferable. 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 very good. Is. Further, 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 silicon-modified polyvinyl alcohol and colloidal silica in the present invention is 0.5 to 3 parts by weight, more preferably 1 to 1 part by weight of 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,
Hydroxymethyl cellulose, starch, gelatin, gum arabic, casein, styrene-maleic anhydride copolymer hydrolyzate, styrene-maleic anhydride 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, cross-linking 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 metallic soap include emulsions of higher fatty acid metal salts such as zinc stearate, calcium stearate, aluminum stearate, etc. Added in quantity.

Examples of the wax include paraffin wax, microcrystalline wax, carnauba wax, methyl roll stearamide, polyethylene wax, and silicone emulsion, 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 a protective layer in order to form a 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 support and the heat-sensitive layer in order to enhance the adhesion between them. 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 hardeners 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 hardening agents is in the range of 0.20% by weight to 3.0% by weight based on the weight of the undercoat material, and the addition amount is appropriate 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. . It is also possible to add an antistatic agent if necessary. Further, a white pigment may be added to the undercoat layer to make it opaque.

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, it is advantageous to have an exposure zone for photodecomposition, which is advantageous for image storability and multicolor.

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) to give a full-color image 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.

[0133]

The support in the multicolor heat-sensitive recording material of the present invention has the same flexibility and texture as the support in which the polyolefin layer is formed on the conventional base paper by the melt extrusion method, and the conventional base paper. It is excellent in handleability, flatness and glossiness as compared with the support consisting of, and by using this, a multicolor heat-sensitive recording material having particularly excellent image uniformity can be obtained. The present invention will be specifically described with reference to the examples, but the embodiment of the present invention is not limited thereto.

[0134]

Example 1 A polyester resin was made to contain 15% by weight of calcium carbonate having an average particle size of 0.9 μm, biaxially stretched, and adjusted to have a density of 0.9 g / cm ³ and SRa of 0.17 μm 1.
A white polyester film of 00 μm was obtained. 0.3 g / m ^{2 of} solvent-soluble polyester resin in which 50% by weight of tin oxide was kneaded was applied to both surfaces of this white polyester film and dried to obtain a surface electric resistance of 5 × 10 ^{8 to} 5 × 10 ⁹ Ω.
-An antistatic layer having a size of cm was formed.

Corona discharge treatment was applied to both surfaces of this substrate. Then, using a melt extruder, high density polyethylene (density 0.960 g / cm ³ , M1 = 13 g / 10
To form a resin layer composed of a matte surface (this surface is referred to as a back surface). Next, a melt extrusion machine is applied to the surface opposite to the surface on which the resin layer is formed. 15% by weight of anatase titanium dioxide
And low density polyethylene (density 0.923 g / cm ³ , MI = 7 g / min) containing a trace amount of ultramarine blue resin thickness 32
A resin layer consisting of a glossy surface was formed by melt extrusion coating at μm (this surface is referred to as the front surface). The polyethylene resin coating layer surface on the back surface was subjected to corona discharge treatment, and then aluminum oxide (Nissan Chemical Industries Alumina sol-100) / silicon dioxide (Snowtex-0 manufactured by Nissan Chemical Industries) = 1/2 (weight ratio) was dispersed in water and 0.2 g / m ^{2 was} applied by the weight after drying.

[0136]

Example 2 The average particle diameter and the addition amount of calcium carbonate contained in the polyester resin in Example 1 were respectively 0.8 μm and 10% by weight, and the density was 1.1 g / c.
m ³ , SRa 0.15 μm, thickness adjusted to 150 μm,
A white polyester film was obtained. Corona discharge treatment was performed on both surfaces of this substrate, and the same antistatic layer and polyethylene layer as in Example 1 were applied.

[0137]

Example 3 A density of 1.0 g / c was obtained by setting the average particle diameter and the addition amount of calcium carbonate contained in the polyester resin in Example 1 to 1.0 μm and 13% by weight, respectively.
m ³ , SRa 0.16 μm, thickness 188 μm,
A white polyester film was obtained. Corona discharge treatment was performed on both surfaces of this substrate, and the same antistatic layer and polyethylene layer as in Example 1 were applied.

[0138]

Comparative Example 1 In Example 1, silica (average particle diameter 3.0 μm) was used in place of calcium carbonate, the addition amount was set to 25% by weight, and further 25% by weight of polymethylpentene was added to obtain a density. 0.4 g / cm ³ , SRa 0.21
The white polyester film was obtained by adjusting the thickness to 100 μm. Perform corona discharge treatment on both sides of this substrate,
The same polyethylene and antistatic layer as in Example 1 were applied.

[0139]

[Comparative Example 2] The average particle size and the addition amount of calcium carbonate contained in the polyester resin in Example 1 were 1.0 μm and 5% by weight, respectively, and the density was 1.5 g / cm ³ .
SRa was adjusted to 0.14 and the thickness was adjusted to 150 μm to obtain a white polyester film. Corona discharge treatment was performed on both surfaces of this substrate, and the same polyethylene and antistatic layer as in Example 1 were applied.

[0140]

[Comparative Example 3] Wood pulp consisting of 20 parts of LBSP and 80 parts of LBKP was beaten with a disc refiner to a Canadian freeness of 300 cc, 1.0 part of sodium stearate, 0.5 part of anionic polyacrylamide.
Parts, 1.5 parts of aluminum sulfate, 0.5 parts of polyamide polyamine epichlorohydrin, and 0.5 parts of alkyl ketene dimer were all added in an absolute dry weight ratio to wood pulp, and weighed with a Fourdrinier paper machine at 170 g / m ² The paper was made into paper and adjusted to a density of 0.99 g / cm ³ by a calendar. Corona discharge treatment was applied to both sides of this base paper, and the same polyethylene and antistatic layer as in Example 1 were applied.

[0141]

[Comparative Example 4] 10% by weight of barium sulfate having an average particle size of 0.7 μm was added to polyester, and biaxially stretched
A white polyester film having a thickness of 180 μm and a density of 1.4 g / cm ³ was obtained.

The polyethylene surfaces containing titanium oxide of Examples 1 to 3 and Comparative Examples 1 to 3 thus obtained and the white polyester sheet surface of Comparative Example 4 were subjected to corona discharge treatment, and then As described above, a full-color thermosensitive recording layer was 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.

A solution A was prepared by adding 20 parts of a 1/3 adduct of xylylene diisocyanate / trimethylolpropane to the resulting solution and stirring the mixture uniformly.

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

Solution A was added to solution B, and the mixture was emulsified and dispersed using a homogenizer to obtain an emulsion dispersion. To the obtained emulsified dispersion liquid, 68 parts of water was added and mixed to homogenize the mixture, which was then heated to 50 ° C. with stirring to encapsulate the microcapsules to an average particle size of 1.2 μm. The reaction was carried out 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 resulting solution was added 15 parts of an adduct (capsule wall agent) of xyliresin isocyanate / trimethylolpropane 1/3 and uniformly mixed to obtain a solution of the diazo compound.

The resulting solution of the 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. 50 g of a 6% by weight aqueous solution of gelatin was obtained.
And 2 g of 2% by weight sodium dodecyl sulfonate in water
After being added to the mixed aqueous solution, the mixture was 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 was mixed at a weight ratio of 2/3 to obtain a coating liquid.

(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
(Dissolved with light having a wavelength of 3%) was dissolved in 20 parts of ethyl acetate, and alkylnaphthalene 2 as a high-boiling solvent was added thereto.
0 part was added and heated to uniformly mix.

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

The obtained solution of the 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 Emulsion of Coupler Emulsion) 2-chloro-5- (3- (2,4-di-tert-pentyl) phenoxypropylamino) acetoacetanilide 2 parts,
1,2,3-Triphenylguanidine 1 part, tricresyl phosphate 0.3 part and diethyl maleate 0.1
Parts in 10 parts ethyl acetate to give 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 Gelatin (# 750: trade name of Nitta Gelatin Co., Ltd.) Polyacrylic acid (trade name of JULIMER AC-10L: manufactured by Nippon Pure Chemical Co., Ltd.) was added to 10 parts of 15% by weight aqueous solution. ) Of 15
3 parts by weight of a wt% aqueous solution was added and mixed uniformly 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 of the supports of Examples 1 to 4 and Comparative Example, using a slide type hopper type bead coating device, cyan heat sensitivity was sequentially applied on the slide 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, calculated as the solid content after drying, is 6.1 g / m ^{2 for} the cyan thermosensitive recording layer, 1.0 g / m ^{2 for} the intermediate layer, and 7.8 g / m for the magenta thermosensitive recording layer in order from the support side. m
² , the intermediate layer was 1.0 g / m ² , the yellow thermosensitive recording layer was 7.2 g / m ^2, and the protective layer was 2.0 g / m ² so that each coating solution was applied.

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 heat-sensitive recording layer was optically fixed by being exposed 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 power 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 way, 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. For the coated sample, a reflectance of 20 ° -20 ° was obtained with a gloss meter according to JIS-Z-8741 Method 4,
The glossiness (%) was measured.

Regarding the texture, the feelings held by the hands were compared, and those having a feeling similar to that of Comparative Example 3 were evaluated as ◯, and those other than that were evaluated as x. In addition, the image uniformity was judged visually, and
The mark indicates that there is no image unevenness and the image is excellent in uniformity, and the double circle indicates that it is particularly excellent. In addition, the mark “X” indicates that unevenness of the image is observed and the uniformity of the image is poor.

The thickness of the support before coating on the heat-sensitive recording layer and the average of the stiffness in the flow direction and the width direction were determined by the method defined in JIS8125, and the value of E was determined by the following formula.

[0169] Table 1 shows the constitutions of the supports of Examples 1 to 3 and Comparative Examples 1 to 4, and Table 2 shows the evaluation results of the multicolor thermosensitive recording materials using the same.

[0170]

[Table 1]

(1) Cut 0.25 mm or more

[0172]

[Table 2]

From Table 2, the supports used in Examples 1 to 3 of the present invention, when the E value is in the range of 400 to 1600, have excellent texture, small SRa, high gloss, and smoothness. It is clear that it is a heat-sensitive recording support excellent in gloss. A full-color heat-sensitive recording material using the same also had excellent texture and image uniformity.

[Brief description of drawings]

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

[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 (3)

[Claims] 1. A multicolor heat-sensitive recording material having a support in which a thermoplastic resin layer is provided on both sides of a substrate made of a white plastic film by a melt extrusion method, and the density of the white plastic film is 0.6 g / cm ³ to 1. 0.3 g /
cm ³ and E defined by the following formula of the above support
A multicolor thermosensitive recording material comprising a support having a value in the range of 400 to 1600 and a multicolor thermosensitive recording layer coated on the support. However, S represents the stiffness (gf · cm) of the support defined by JIS8125, and T represents the thickness (mm) of the support. 2. The multicolor heat-sensitive recording according to claim 1, wherein the support is one in which a thermoplastic resin layer is provided on both sides of a substrate made of a white plastic film via an antistatic layer by a melt extrusion method. material. 3. The multicolor heat-sensitive recording material according to claim 1 or 2, wherein the white plastic film is composed of a calcium carbonate pigment and polyethylene terephthalate, and the thermoplastic resin layer is composed of polyethylene.