JPH04338586A - Multicolor thermal recording material for laser recording and image recording method using the same - Google Patents

Abstract

PURPOSE:To provide a thermosensitive recording material for laser recording and a recording method suitable to record a multicoloor recording image by converting laser beam light energy to heat energy in a non-contact thermosensitive recording material. CONSTITUTION:In a thermal recording material wherein a thermal layer containing a substantially colorless color former and a developer is provided on a support, said thermal layer contains two or more kinds of image forming units each composed of a dye converting laser beam to heat energy and becoming colorless upon the absorption of light of a specific wavelength range and is irradiated with laser beam at every image forming unit to perform recording. The thermal recording material for laser recording is irradiated with light of the specific wavelength range on the side of the thermal layer and/or the support to make it possible to make the dye colorless.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact heat-sensitive recording material for recording using laser light, and more particularly to a laser heat-sensitive recording material suitable for multicolor recording and an image recording method using the same.

0002

[Prior Art] A thermal recording method in which a thermal head is closely scanned on the surface of a thermosensitive recording material having a thermosensitive coloring layer provided on a support, and a colored image is recorded by transmitting thermal energy directly to the thermosensitive coloring layer or through a protective layer. is widely known and is applied to facsimiles, printers, etc. However, in such a thermal recording method, since the thermal head is brought into close contact with the thermal recording material for scanning, the thermal head may wear out or components of the thermal recording material may adhere to the surface of the thermal head in the form of debris. As a result, a recorded image may not be obtained correctly, and the thermal head is likely to be destroyed.

[0003] Furthermore, in the thermal recording method using such a thermal head, there are limitations in controlling the heating and cooling of the heating element at high speed and increasing the density of the heating element due to the structural characteristics of the thermal head. The drawback was that there were limits to high-speed recording, high-density, and high-quality recording.

In order to solve the above-mentioned problems of the thermal recording method using a thermal head, a laser beam is used,
It has been proposed to perform non-contact, high-speed, and high-density thermal recording on heat-sensitive recording materials (for example,
No. 23617, JP-A-54-121140, JP-A-5
7-11090, JP 58-56890, JP 58-94494, JP 58-134791, JP 58-145493, JP 59-89192, JP 60- No. 205182, JP-A-62-5619
Publication No. 5).

However, in such a recording method using laser light, the heat-sensitive layer generally has difficulty absorbing light in the visible and near-infrared regions, so the laser output must be considerably increased to produce color. The drawback was that it was difficult to produce a small and inexpensive device because it was difficult to obtain sufficient thermal energy.

[0006] In addition, Japanese Patent Publication No. 50-774 proposes a method in which microcapsules containing ink are coated, and strong light is irradiated to eject the ink in the capsules to record on base paper. The sensitivity is very low and it has not yet been realized.

[0007]

[Problems to be Solved by the Invention] Therefore, many proposals have been made to make the heat-sensitive layer efficiently absorb laser light, and generally, a light-absorbing material that matches the wavelength of the laser light is included in the heat-sensitive layer. is being added.

The mechanism of image recording using laser light is that a light-absorbing substance absorbs the laser light that is imagewise irradiated onto the heat-sensitive layer, converts the energy of the absorbed laser light into thermal energy, and heats the heat-sensitive layer. An image is recorded by reacting the color forming components (color forming agent and color developer) contained in the heat-sensitive layer.

When microcapsules are used, a light-absorbing substance that absorbs laser light is generally added to the microcapsules containing the coloring agent, or a heat-sensitive layer outside the microcapsules, or both. added to. In this case, an image is recorded by heating the microcapsule wall with a laser beam to make the microcapsule wall permeable to substances, thereby bringing the coloring components inside and outside the microcapsule into contact reaction with each other.

Therefore, it is possible to improve the sensitivity of a heat-sensitive recording material by using a light-absorbing substance with good light-absorbing efficiency or by increasing the amount of light-absorbing substance contained in the heat-sensitive layer. In this case, if the light-absorbing substance added is not colorless, the heat-sensitive layer will be colored by the light-absorbing substance.
The background of the recording material is colored, resulting in low contrast, and the colors developed by thermal recording become cloudy due to the coloring of the heat-sensitive layer itself, making it impossible to record clear hues, which is undesirable. Such a drawback is fatal when recording in multiple colors.

Generally, colorless light-absorbing substances are mostly inorganic compounds, but since most of them have low light-absorbing efficiency, it has been desired to develop organic compounds with high light-absorbing efficiency and less coloring. .

In addition, increasing the amount of the light-absorbing substance added can improve the thermal sensitivity of the recording material, but if the added light-absorbing substance is colored, the coloring of the recording material itself will be affected by the light-absorbing substance. Since the amount increases in proportion to the amount added, it is difficult to record good multicolor images as described above.

However, even if a colored light-absorbing material with good laser light absorption efficiency is used, if the coloring of the light-absorbing material can be made colorless after recording with laser light, the light absorption can be improved. It is also possible to increase the content of the substance to improve thermal sensitivity and to obtain multicolor images of good quality.

[0014] Therefore, the present inventors developed a pigment that can convert laser light into thermal energy and becomes colorless by absorbing light in a specific wavelength range (hereinafter referred to as a light absorption decomposition pigment), and When the heat-sensitive layer contains two or more types of image-forming units consisting of a combination of a substantially colorless color former and a color developer that cause a color-forming reaction so as to reproduce different hues, the heat sensitivity of the recording material increases. The present inventors have discovered that it is possible to improve the image quality and record good multicolor images, and have arrived at the present invention.

Accordingly, a first object of the present invention is to provide a multicolor thermosensitive recording material for laser recording that is highly sensitive and capable of high quality multicolor recording. Second aspect of the present invention
The purpose of this invention is to provide an image recording method that can record high-quality multicolor images at high speed using laser light.

[0016]

[Means for Solving the Problems] The above-mentioned objects of the present invention are to provide a substantially colorless color forming agent and a color developer on a support, and a method capable of converting laser light into thermal energy and having a specific wavelength. A heat-sensitive recording material having a heat-sensitive layer containing two or more types of image-forming units made of components of colored pigments that become colorless by absorbing light within a range, wherein the hue of the image formed by each image-forming unit is A recording heat-sensitive recording material for a laser, which is characterized by different characteristics, and a heat-sensitive recording material for a laser, which is image-wise irradiated with laser light of different wavelengths from the heat-sensitive layer side or the support side, and then recorded in a specific wavelength range. This was achieved by an image recording method characterized in that colored dyes are rendered colorless by irradiating light from the heat-sensitive layer side and/or the support side of the laser heat-sensitive recording material.

[0017] The substantially colorless color forming agent and color developer used in the present invention are components that cause a color forming reaction upon contact with substances, and specifically include electron-donating dye precursors (color forming agents).
A combination of and an acidic substance (developer) or a diazo compound (
A combination of a color former) and a coupling compound (color developer) is preferred.

The electron-donating dye precursor used in the present invention is not particularly limited as long as it is substantially colorless, and has the property of donating electrons or accepting protons such as acids to develop color. A compound having a partial skeleton such as a lactone, lactam, sultone, spiropyran, ester, or amide, and whose partial skeleton opens or cleaves upon contact with a color developer is used. Specifically, crystal violet lactone, benzoylleucomethylene blue, malachite green lactone,
Rhodamine B lactam, 1,3,3-trimethyl-6'
-ethyl-8'-butoxyindolinobenzospiropyran and the like.

In the present invention, from the viewpoint of producing a multicolor heat-sensitive recording material, it is preferable to use a yellow precursor, a cyan precursor, and a magenta precursor. A specific example of the yellow color precursor is Reakt Yellow (trade name manufactured by Basf Company).
, Copikem 11 (Copikem 11: trade name manufactured by Hilton Davis Chemical Co., Ltd.), Copikem 14 (
Copikem14 (trade name manufactured by Hilton Davis Chemical Co., Ltd.), and the like.

Specific examples of cyan color precursors include Cyan 8-29663 (experimental compound manufactured by Hilton Davis Chemical Co.), Copikem 10 (Copikem
10: trade name manufactured by Hilton Davis Chemical Co., Ltd.) and the compound described in US Pat. No. 4,322,352.

As a magenta color precursor, Copichem 2
0 (Copikem20: a product name manufactured by Hilton Davis Chemical Co., Ltd.), Pergascript Red (
Pergascript Red (trade name manufactured by Ciba Geigy Co., Ltd.) and the like can be mentioned. In addition to the above, yellow precursors, cyan precursors, magenta precursors, etc., which are described in detail in JP-A-61-24495, can be used.

Color developers for these color formers include:
Acidic substances such as phenol compounds, organic acids or metal salts thereof, and oxybenzoic acid esters are used. A specific example thereof is described in, for example, Japanese Patent Laid-Open No. 61-291183.

The diazo compound used in the present invention reacts with a color developer called a coupling component to be described later to develop a desired hue, and decomposes when exposed to light of a specific wavelength before the reaction. However, it is a photodegradable diazo compound that no longer has color-forming ability even when a coupling component acts on it.

The hue in this coloring system is mainly determined by the diazo dye produced by the reaction between the diazo compound and the coupling component. 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 coupling component, and almost any coloring hue can be obtained depending on the combination. Therefore, in order to obtain a multicolor recording material, various diazo compounds may be contained in one layer, and one type of coupling component and other additives may also be incorporated in the same layer. In this case, each unit color forming group is composed of a different diazo compound and a common coupling component and other additives.

There is also a combination in which separate coupling components are contained in several layers and the same diazo compound and other additives are incorporated in each layer. At this time, each unit coloring group is composed of a different coupling component and a common diazo compound and additive.

In any case, each unit coloring group is composed of one or more diazo compounds, one or more coupling components, and other additives, which are combined so that the coloring hues are different. Of course, it is also possible to create multiple colors by using both a color-forming unit consisting of a combination of an electron-donating dye precursor and a color developer and a color-forming unit consisting of a combination of a diazo compound and a coupler.

The photodegradable diazo compound in the present invention mainly refers to aromatic diazo compounds, and more specifically refers to compounds such as aromatic diazonium salts, diazosulfonate compounds, and diazoamino compounds.

The diazonium salt has the general formula ArN2 +
It is a compound represented by X- (wherein Ar represents a substituted or unsubstituted aromatic moiety, N2 + represents a diazonium group, and X- represents an acid anion).
.

It is generally said that the photodecomposition wavelength of a diazonium salt is its maximum absorption wavelength. It is also known that the maximum absorption wavelength of diazonium salts varies from about 200 nm to about 700 nm depending on its chemical structure ("Photodegradation and chemical structure of photosensitive diazonium salts" by Takahiro Tsunoda and Ao Yamaoka, Nippon Photo) Academic Journal 29(4) 197-2
05 page (1965)). That is, if a diazonium salt is used as a photodegradable compound, it will be decomposed by light of a specific wavelength depending on its chemical structure, and if the chemical structure of the diazonium salt is changed, it will be decomposed by light of a specific wavelength depending on its chemical structure. The hue of the pigment also changes.

A large number of diazosulfonates that can be used in the present invention are known and can be obtained by treating each diazonium salt with a sulfite. Further, other diazo compounds that can be used in the present invention include diazoamino compounds. The diazoamino compound is a compound in which a diazo group is coupled with dicyandiamide, sarcosine, methyltaurine, N-ethylanthranic acid-5-sulfonic acid, monoethanolamine, diethanolamine, guanidine, or the like. Details of these diazo compounds are described, for example, in JP-A-2-136286.

As the light source for photolysis, various light sources that emit light of a desired wavelength can be used, such as various fluorescent lamps, xenon lamps, xenon flash lamps, mercury lamps at various pressures, photographic flashes, Various light sources such as strobes can be used. Further, in order to make the optical fixing zone compact, the light source section and the exposure section may be separated using an optical fiber.

[0032] Coupling components that are coupled with the diazo compound (diazonium salt) used in the present invention to form a dye include, for example, 2-hydroxy-3-naphthoic acid anilide, resorcinol, and other compounds disclosed in JP-A-62 -14
Examples include those described in No. 6678.

Furthermore, by using two or more of these coupling components in combination, an image of any color tone can be obtained. Since the coupling reaction between these diazo compounds and the coupling component is likely to occur in a basic atmosphere, a basic substance may be added to the layer.

As the basic substance, a poorly water-soluble or water-insoluble basic substance or a substance that generates an alkali when heated is used. Examples include inorganic and organic ammonium salts, organic amines, amides, urea and thiourea and their derivatives, thiazoles, pyrroles, pyrimidines,
Piperazines, guanidines, indoles, imidazoles, imidazolines, triazoles, morpholines, piperidines, amidines, formazines,
Examples include nitrogen-containing compounds such as pyridines. Specific examples of these are described, for example, in JP-A-61-291183. Two or more basic substances may be used in combination.

[0035] In the present invention, when two or more combinations of the above-mentioned substantially colorless color forming agent and color developer having different color hues, and the light absorption and decomposition dye are contained in the same heat-sensitive layer, each When a light absorption and decomposition dye is irradiated with a suitable laser beam, only the light absorption and decomposition dye that absorbs laser light of the wavelength selectively absorbs the laser light and converts the energy into thermal energy. Therefore, only the color former and developer of the group to which the light-absorbing and decomposing dye belongs are selectively heated, causing a color reaction.

Next, by irradiating laser light with a wavelength different from that of the previous time, a colored image with a different hue can be obtained. That is, multicolor recording can be performed by changing the wavelength of the irradiated laser light. In this case, from the viewpoint of color separation properties and shelf life (fogging), it is preferable that the color forming agent and the light-absorbing and decomposing dye are used in microcapsule form.

In addition, when producing a full-color multicolor thermal recording material, from the viewpoint of color reproducibility and color separation, cyan, cyan,
It is preferable to provide a heat-sensitive layer (hereinafter referred to as a cyan color-forming layer, etc.) having respective color-forming units that thermally color each hue of magenta and yellow in a layered manner on a support.

The pigment used in the present invention that can convert laser light into thermal energy and becomes colorless by absorbing light in a specific wavelength range (hereinafter referred to as a light absorption decomposition pigment) is not particularly limited. However, from among the known substances that absorb and decompose light, those that have a large extinction coefficient for the wavelength of laser light and that become colorless when irradiated with light in a specific wavelength range are selected as appropriate. used. The light in the specific wavelength range in the present invention is selected from a range that includes infrared rays, visible light, ultraviolet rays, electron beams, and X-rays.

Examples of light-absorbing and decomposing dyes that can be used in the present invention include ionic dye-counterion compounds (JP-A-62-150242, JP-A-1-152450), cationic dye-borate anion complexes ( Unexamined Patent Publication 1986-14
3044), 3-substituted coumarin compounds (JP-A-61-1
14234), bis(diiminosuccinonitrilo) metal complex (Japanese Patent Publication No. 3-10087), and the like. Among these, ionic dye-counterion compounds are preferred, and cationic dye-borate anion complexes are particularly preferred.

The ionic dye-counter ion compound used in the present invention is a compound consisting of an ionic dye ionically bonded to a reactive counter ion, and since it itself has light absorption ability, it cannot be colored. However, when light in a specific wavelength range is irradiated and the ionic dye is excited by absorbing the light, the counter ion donates electrons to the excited ionic dye or removes electrons from the excited ionic dye. It is a compound that generates free radicals and becomes colorless. When such a compound is added to the heat-sensitive layer, the background of the recording material is colored, but it can be made colorless by irradiation with light in a specific wavelength range, making the background of the recording material colorless or white.

In the present invention, among such ionic dye-counter ion compounds, the following general formula (Chemical formula 1), which is a cationic dye-counter ion compound, is used.

[Formula 1] (However, D+ is a cationic dye such as cyanine, carbocyanine, hemicyanine, rhodamine, azomethane, etc., and R1, R2, R3 and R4 are alkyl groups,
An aryl group, an alkaryl group, an allyl group, an aralkyl group, an alkenyl group, an alkenylalkynyl group, an alicyclic group, or a saturated or unsaturated heterocyclic group, which may be the same or different. ) A cationic dye-borate anion complex compound is preferred.

[0042] Specific examples of such compounds are disclosed in JP-A-62-
It is described in detail in Japanese Patent No. 150242. In the present invention, the following (chemical formula 2) having a maximum optical absorption wavelength of 740 nm is used.

A cationic dye-borate anion complex compound represented by the following formula is particularly preferred.

As the anionic dye-counterion compound, the following general formula (Chemical formula 3) is used.

[Formula 3] (However, D- is an anionic dye, R5, R6
are groups consisting of an aromatic nucleus such as a phenyl group or a naphthyl group, and may be the same or different. n is 1 or 2
It is. ) Anionic dye-iodonium ion compounds can be mentioned. Specific examples of such compounds are also described in detail in JP-A-62-150242.

In the present invention, the maximum optical absorption wavelength is 570
The following (Chemical formula 4) having nm

Anionic dye-iodonium ion compounds represented by the following formula are particularly preferred.

The 3-substituted coumarin compound that can be used in the present invention has a light absorption ability in the wavelength range of 390 to 500 nm and is yellow in itself, so when added to the heat-sensitive layer, the background of the recording material is colored yellow. However, when exposed to ultraviolet light, it becomes colorless or white.

Specific examples of such 3-substituted coumarin compounds are described in detail in JP-A-61-114234. The bis(diiminosuccinonitrilo) metal complex that can be used in the present invention has the following general formula (Chemical formula 5):

embedded image (where M represents, for example, nickel, palladium, platinum or cobalt).

The above-mentioned bis(diiminosuccinonitrilo) metal complex has a maximum absorption ability in the wavelength range of 650 to 1150 nm, so it is colored itself, but when irradiated with ultraviolet rays, X-rays, or electron beams, It has the property of becoming colorless when the above-mentioned absorption ability decreases or disappears. Therefore, if such a substance is added to the heat-sensitive layer, the background of the recording material will be colored;
When irradiated with ultraviolet rays or the like, the skin becomes colorless or white. Specific examples and synthesis methods of such bis(diiminosuccinonitrilo) metal complexes are described in detail in Japanese Patent Publication No. 3-1008.

The coloring agent, developer, and coloring dye used in the present invention can be used as a solid dispersion in the heat-sensitive layer by a known method. It is preferable to use it in an encapsulated form from the viewpoint of shelf life (preventing fogging) by preventing contact between the agent and the color developer, and from the viewpoint of controlling color development sensitivity so that color can be developed with a desired laser energy. Particularly from the above-mentioned viewpoint of raw storage stability, it is preferable to use the coloring agent in microcapsule form. The light-absorbing and decomposing dye can be added not only inside or outside the microcapsule, but also both inside and outside.

[0049] Any of the interfacial polymerization method, internal polymerization method, and external polymerization method can be adopted as a method for manufacturing the microcapsules that can be used in the present invention, but in particular, a core material containing a coloring agent is dissolved in water. It is preferable to employ an emulsion polymerization method in which a polymer substance is emulsified in an aqueous solution in which a polymer is dissolved, and then a wall of polymer material is formed around the oil droplets.

[0050] A reactant forming a polymeric substance is added to the interior of the oil droplet and/or to the exterior of the oil droplet. Specific examples of the polymeric material include polyurethane, polyurea, polyamide, polyester, polycarbonate, urea-formaldehyde resin, melamine resin, polystyrene, styrene-methacrylate copolymer, styrene-acrylate copolymer, and the like. Preferred polymeric materials are polyurethanes, polyureas, polyamides, polyesters, polycarbonates, particularly preferred are polyurethanes and polyureas. Two or more types of polymeric substances can also be used in combination.

Specific examples of the water-soluble polymer include gelatin, polyvinylpyrrolidone, polyvinyl alcohol, and the like. For example, when polyurea is used as a capsule wall material, polyisocyanates such as diisocyanates, triisocyanates, tetraisocyanates, and polyisocyanate prepolymers, polyamines such as diamines, triamines, and tetraamines, and two amino groups are used. A microcapsule wall can be easily formed by reacting the prepolymer, piperazine or its derivative, polyol, etc. contained above in an aqueous solvent by an interfacial polymerization method.

[0052] For example, a composite wall made of polyurea and polyamide or a composite wall made of polyurethane and polyamide can be formed by adjusting the pH of the emulsifying medium serving as the reaction solution using, for example, polyisocyanate and acid chloride or polyamine and polyol. It can be prepared by heating. For details on the manufacturing method of these composite walls made of polyurea and polyamide, please refer to JP-A-58-6
It is described in Japanese Patent No. 6948.

Furthermore, a solid sensitizer may be added in order to swell the microcapsule walls during heating with laser light. As the solid sensitizer, those having a melting point of 50° C. or more, preferably 120° C. or less, and solid at room temperature can be selected from among those called plasticizers for the polymer used as the microcapsule wall. For example, when the wall material is made of polyurea or polyurethane, hydroxy compounds, carbamate ester compounds, aromatic alkoxy compounds, organic sulfonamide compounds, aliphatic amide compounds, aryl amide compounds, etc. are preferably used.

In the present invention, when a diazo compound is used as a coloring agent, it is also possible to use a coloring aid. The color development aid that can be used in the present invention is a substance that increases the color density during laser heating printing or lowers the minimum color development temperature, lowers the melting point of coupling components or diazo compounds, etc. This is to create a situation where the diazo compound and the coupling component are likely to react by lowering the softening point of the wall.

Color development aids include phenolic compounds, alcoholic compounds, amide compounds, sulfonamide compounds, etc. Specific examples include p-tert-octylphenol, p-benzyloxyphenol, phenyl p-oxybenzoate, Benzyl carbanylate, phenethyl carbanylate, hydroquinone dihydroxyethyl ether, xylylene diol, N-hydroxyethyl-
Compounds such as methanesulfonic acid amide and N-phenyl-methanesulfonic acid amide can be mentioned. These may be contained in the core material or may be added outside the microcapsules as an emulsified dispersion.

In the present invention, the color forming agent, color developer, or light absorption splitting dye when not microencapsulated is selected from the viewpoint of making the heat-sensitive layer transparent and obtaining a clear multicolor image.
After dissolving it in an organic solvent that is sparingly soluble or insoluble in water, it is mixed with an aqueous phase having a water-soluble polymer containing a surfactant as a protective colloid, and used in the form of an emulsified dispersion. In particular, it is preferable to use the color developer in the form of an emulsified dispersion.

The organic solvent that is sparingly soluble or insoluble in water used in this case can be appropriately selected from high boiling point oils. In addition to esters, preferred oils include dimethylnaphthalene, diethylnaphthalene, diisopropylnaphthalene, dimethylbiphenyl, diethylbiphenyl, diisopropylbiphenyl, diisobutylbiphenyl, and 1-methyl-1-dimethylphenyl-1.
-Phenylmethane, 1-ethyl-1-dimethylphenyl-1-phenylmethane, 1-propyl-1-dimethylphenyl-1-phenylmethane, triallylmethane (e.g. tritolylmethane, tolyldiphenylmethane)
, terphenyl compounds (eg, terphenyl), alkyl compounds (eg, terphenyl), alkylated diphenyl ethers (eg, propyl diphenyl ether), hydrogenated terphenyl (eg, hexahydroterphenyl), diphenyl ether, and the like. Among these, it is particularly preferable to use esters from the viewpoint of emulsion stability of the emulsified dispersion.

Examples of esters include phosphate esters (for example, triphenyl phosphate, tricresyl phosphate, butyl phosphate, octyl phosphate, cresyl diphenyl phosphate), phthalate esters (dibutyl phthalate, 2-ethylhexyl phthalate, phthalate). ethyl, octyl phthalate, butyl benzyl phthalate), dioctyl tetrahydrophthalate, benzoic acid ester (ethyl benzoate, propyl benzoate, butyl benzoate, isopentyl benzoate, benzyl benzoate), abietic acid ester (ethyl abietate, benzyl abietate), dioctyl adipate,
Isodecyl succinate, dioctyl azelaate, oxalate esters (dibutyl oxalate, dipentyl oxalate)
, diethyl malonate, maleate esters (dimethyl maleate, diethyl maleate, dibutyl maleate)
, tributyl citrate, sorbate esters (methyl sorbate, ethyl sorbate, butyl sorbate), sebacate esters (dibutyl sebacate, dioctyl sebacate), ethylene glycol esters (formic acid monoesters 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, propylene carbonate, boric acid esters tributyl acid, tripentyl borate), etc. Among these, when tricresyl phosphate is used alone or in combination, the emulsion dispersion stability of the color developer is particularly good, and therefore it is preferable. It is also possible to use the above oils together or with other oils.

In the present invention, an auxiliary solvent may be added to the above-mentioned organic solvent as a low-boiling solubilizing agent. Particularly preferred examples of such co-solvents include ethyl acetate, isopropyl acetate, butyl acetate and methylene chloride.

The water-soluble polymer to be contained as a protective colloid in the aqueous phase mixed with the oil phase containing these components is as follows:
Although it can be appropriately selected from known anionic polymers, nonionic polymers, and amphoteric polymers, polyvinyl alcohol, gelatin, cellulose derivatives, etc. are particularly preferred.

[0061] The surfactant to be contained in the aqueous phase may be appropriately selected from anionic or nonionic surfactants that do not interact with the protective colloid to cause precipitation or aggregation. can. Preferred surfactants include sodium alkylbenzene sulfonate, sodium alkyl sulfate, dioctyl sodium sulfosuccinate, polyalkylene glycol (eg, polyoxyethylene nonylphenyl ether), and the like.

[0062] The emulsified dispersion in the present invention is produced by combining an oil phase containing the above components and an aqueous phase containing a protective colloid and a surfactant using means commonly used for fine particle emulsification, such as high-speed stirring and ultrasonic dispersion. It can be mixed and dispersed easily.

[0063] The ratio of the oil phase to the aqueous phase (oil phase weight/aqueous phase weight) is preferably 0.02 to 0.6, particularly 0.1.
It is preferable that it is 0.4. If it is less than 0.02, there will be too much water phase and it will be diluted and sufficient color development will not be obtained;
On the contrary, the viscosity of the liquid increases, resulting in inconvenience in handling and a decrease in stability of the coating liquid.

When coating the capsule liquid and emulsion dispersion liquid (hereinafter referred to as heat-sensitive layer liquid) prepared as described above on a support, a known coating method using a water-based or organic solvent-based coating liquid is used. It will be done. In this case, in order to safely and uniformly apply the heat-sensitive layer liquid and maintain the strength of the coating film, in the present invention, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, starches, gelatin, polyvinyl alcohol, carboxy-modified polyvinyl alcohol, Polyacrylamide, polystyrene and copolymers thereof, polyester and copolymers thereof, polyethylene and copolymers thereof, epoxy resins, acrylate and methacrylate resins and copolymers thereof, polyurethane resins, polyamide resins, etc. may be used in combination. can.

The heat-sensitive layer provided on the support in this manner has extremely good transparency. The support used in the present invention may be transparent or opaque. When using a transparent support that does not exhibit large absorption at the wavelength of the irradiated laser beam, does not deform due to heat generated during laser irradiation, and has dimensional stability, It can also be recorded by irradiating it with laser light. The thickness of the support used is 10 μm to 200 μm.

Examples of such transparent supports include:
Polyester films such as polyethylene terephthalate and polybutylene terephthalate, cellulose derivative films such as cellulose triacetate films, polyolefin films such as polystyrene films, polypropylene films, and polyethylene films, polyimide films, polyvinyl chloride films, polyvinylidene chloride films,
Examples include polyacrylic film and polycarbonate film, and these can be used alone or in combination.

On the other hand, examples of the opaque support of the recording material include paper, synthetic paper, an aluminum vapor-deposited base, and the transparent support coated with a pigment or the like. In this case,
In order for laser light to be irradiated from the heat-sensitive layer side and efficiently absorbed by the heat-sensitive layer, it is preferable to use a material that is highly reflective to laser light as the opaque support for the recording material.

The support used in the present invention is particularly preferably a polyester film subjected to heat-resistant treatment and antistatic treatment. In the present invention, in order to prevent the whole heat-sensitive layer from peeling off from the support, it is desirable to provide an undercoat layer on the support before coating the heat-sensitive layer containing microcapsules or the like on the support.

[0069] As the undercoat layer, acrylic ester copolymer, polyvinylidene chloride, SBR, water-based polyester, etc. can be used, and the film thickness is 0.1-0.
5 μm is desirable. The undercoat layer made of these compositions is
Blade coating method, air knife coating method, gravure coating method,
The coating is performed by a known coating method such as a roll coating method, a spray coating method, a dip coating method, or a bar coating method. The coating amount is preferably 1 to 20 g/m2, particularly 3 to 20 g/m2.
It is preferable to set it as 10g/m2.

Further, pigments, waxes, hardeners, etc. may be added to the heat-sensitive layer, if necessary. The heat-sensitive layer is a coloring agent,
The total amount of color developer and light absorption decomposition dye is 0.1 to 10 g/m
2 and the thickness of the layer is 1
It is desirable that the coating be applied to a thickness of ~10 μm.

In the present invention, it is preferable to provide a protective layer on the heat-sensitive layer by a known method in order to prevent deterioration of apparent transparency due to light scattering on the surface of the heat-sensitive layer. Details of the protective layer are described, for example, in "Paper and Pulp Technology Times" (September issue, 1985), pages 2 to 4, and in Japanese Patent Application Laid-open No. 318546/1983.

In order to improve the transparency of the protective layer, a combination of silica-modified polyvinyl alcohol and colloidal silica is particularly preferred. In the present invention, a protective layer containing silicone resin as a main component can be provided together with or in place of the conventionally used protective layers described above. This provides good water resistance without impairing the transparency of the heat-sensitive layer.

[0073] Waxes, metal soaps, etc. may be added to the protective layer for the purpose of improving suitability for a thermal head during thermal printing and improving water resistance of the protective layer. The amount of these used is preferably 0.2 to 7 g/m2.

In the present invention, when heat-sensitive layers are stacked to form a multicolor heat-sensitive recording material, a layer having the same composition as the protective layer is provided as an intermediate layer below the heat-sensitive layer. As the intermediate layer, it is particularly preferable to use a layer formed by gelling a water-soluble polyanionic polymer with polyvalent cations, as disclosed in JP-A-1-3012892.

The laser used in the present invention is not particularly limited, but a known laser that emits laser light at a wavelength at which a light absorption and decomposition dye has a large absorption coefficient can be used. Specific examples include helium-neon laser, argon laser, carbon dioxide laser, YAG
Examples include lasers, semiconductor lasers (GaAs bonding lasers), and the like.

In the multicolor image recording method using the recording material of the present invention, when the support of the heat-sensitive recording material is transparent, the heat-sensitive layer is imagewise irradiated with laser light from the heat-sensitive layer side and/or the support side. After recording an image of a specific hue by a coloring reaction caused by contact between the color forming agent and the color developer contained, further,
By irradiating laser beams of different wavelengths in an imagewise manner, and recording an image with a different hue than the previous color due to a color reaction caused by contact between a color former and a color developer, which develops a different hue from the already developed color, multicolor After repeating such image recording for the number of heat-sensitive layers, the entire surface is exposed from the heat-sensitive layer side and/or the support side with light having a wavelength effective for light absorption, decomposition, and colorless dyeing. . This entire surface exposure renders the light-absorbing and decomposing dye contained in the heat-sensitive layer colorless, so that a clear multicolor image can be obtained.

When the support of the heat-sensitive recording material is opaque, laser beams of different wavelengths are irradiated from the heat-sensitive layer side in an imagewise manner as described above, sequentially or simultaneously to record a multicolor image, and then the heat-sensitive recording material is opaque. By exposing the entire layer side to light, a high-quality multicolor reflection image with a white background can be obtained.

When a diazo compound is used as a coloring agent, the entire surface can be exposed only once by exposing the entire surface to light that includes light that decomposes the photodegradable diazo compound.

In addition, when a multicolor heat-sensitive recording material is prepared by sequentially providing a cyan coloring layer, a magenta coloring layer, and a yellow coloring layer on one side of the support, for example, first of all, the yellow coloring layer contains The yellow layer on the top layer develops color by irradiating it with laser light that is absorbed by the light-absorbing and decomposing dye, and converting the energy of the laser light into thermal energy. Next, the magenta layer is thermally recorded by irradiation with laser light having a wavelength that is absorbed by the light-absorbing and decomposing dye contained in the magenta color-forming layer, thereby causing the magenta layer to develop color. Finally, the cyan layer is colored by irradiation with laser light having a wavelength that is absorbed by the light-absorbing and decomposing dye contained in the lowest cyan coloring layer.

In this case, the wavelength of each laser beam is as follows: yellow coloring layer>magenta coloring layer>cyan coloring layer. After recording in each coloring layer in this way, light having a wavelength that decomposes the light-absorbing and decomposing dye contained in each coloring layer and the diazo compound if a diazo compound is used as a coloring agent is irradiated. This makes the light-absorbing and decomposing dye colorless, making the image clear and at the same time light-fixing it. As a result, it is possible to obtain clear images of each hue of cyan, magenta, and yellow, and at the same time, it is possible to improve the storage stability of the recorded images.

In this case, if a transparent support is used and all the coloring layers are substantially transparent, the resulting image can be viewed as a transmitted image or projected like an OHP. It can also be viewed as a reflective image using an opaque support.

[0082] When the purpose is to reproduce a reflected image, the coloring layer furthest from the side from which the image is viewed may be made opaque. Further, those skilled in the art can easily understand that intermediate colors can be appropriately reproduced by controlling the color development of each unit by appropriately adjusting the irradiation energy of the laser beam.

[0083]

[Effects of the Invention] The heat-sensitive layer of the recording material of the present invention contains two or more color-forming units each consisting of a combination of a substantially colorless color-forming agent and developer having different color hues, and a light-absorbing and decomposing dye. Therefore, multicolor recording can be performed by irradiating laser beams with different wavelengths in an imagewise manner, and by irradiating the entire surface of the recording material with light having a wavelength that can decompose the light-absorbing and decomposing dye, the light-absorbing and decomposing dyes can be Since the decomposed dye is made colorless, the quality of the image obtained is good. Furthermore, since a large amount of light-absorbing and decomposing dye can be used, recording sensitivity is good and high-speed recording using laser light is possible.

[0084]

[Examples] The present invention will be explained in more detail with reference to Examples below.
The present invention is not limited thereby. Note that "parts" indicating the amount added indicate "parts by weight."

Example 1. Preparation of capsule liquid A:
) 3.4 parts of a diazo compound represented by

[C6] 0.5 part of a light absorption and decomposition dye represented by the following (Chemical formula 7),

[C7]

6 parts of tricresyl phosphate, 12 parts of methylene chloride, 18 parts of trimethylolpropane trimethacrylate and Takenate D110N (75% by weight solution of trimethylolpropane 3:1 adduct of m-xylylene diisocyanate in ethyl acetate) : Trade name manufactured by Takeda Pharmaceutical Co., Ltd.) 24 parts were uniformly mixed to prepare an oil phase solution.

On the other hand, 63 parts of an 8% by weight polyvinyl alcohol aqueous solution was added to 100 parts of distilled water to prepare a water-soluble polymer aqueous solution. Next, the oil phase solution was added to the polymer aqueous solution with stirring, and emulsification and dispersion was carried out at 20°C so that the average particle size of the emulsion was about 2 μm. After the dispersion was completed, the stirring was loosened and the temperature was maintained at 40°C. The encapsulation reaction was completed in 3 hours.

After cooling the obtained liquid to 20°C, 100 ml of Urban Light IR-120B (trade name, manufactured by Rohm and Haas Co., Ltd.) was added, and after stirring for 1 hour,
The obtained liquid was filtered to obtain capsule liquid A.

Prepared solution 1 of coupler/base emulsion dispersion A
: 170 parts of a 4% by weight aqueous solution of polyvinyl alcohol. Solution 2: Mix the compositions shown in Table 1 below to prepare Solution 2. adjusted.

[0090]

[Table 1] ──────────────────────────
────────Coupler represented by the following (chemical formula 8)
1.4
Department

[Chemical formula 8] Triphenylguanidine (organic basic compound)
6 parts Coloring aid represented by the following (Chemical formula 9)
14 parts

[Chemical formula 9] Tricresyl phosphate
10 parts ethyl acetate
Part 20────────────────────────
────────The above solution 2 was added to the aqueous solution 1 above, and emulsified and dispersed at 20°C to obtain an emulsified dispersion A.

Preparation of Capsule Solution B The components shown in Table 2 below were mixed and added to an aqueous solution consisting of 100 parts of an 8% by weight aqueous solution of polyvinyl alcohol and 40 parts of distilled water. Emulsification and dispersion was performed so that the average particle size was about 1 μm. Then, after the dispersion was completed, stirring was loosened and the temperature was maintained at 40°C, and the encapsulation reaction was completed in 3 hours to obtain capsule liquid B.

[0092]

[Table 2] ──────────────────────────
──────────Basic colorless dye represented by the following (Chemical formula 10) 14
Department

[Chemical formula 10] (Blue #200: Product name manufactured by Yamada Chemical Co., Ltd.) The light absorption decomposition agent of the following (Chemical formula 11) (maximum absorption wavelength 590n
m) 1 copy

[Chemical formula 11] 1-phenyl-1-xylylethane
55 parts sumi soap 200
Part 2 (
Trade name of ultraviolet absorber manufactured by Sumitomo Chemical Co., Ltd.) Takenate D-110N
60 copies (trade name manufactured by Takeda Pharmaceutical Co., Ltd.) ──────────────────────────
─────────

Preparation of Capsule Liquid C Instead of the diazo compound represented by (Chemical Formula 6) used in Capsule Liquid A, the following diazo compound (Chemical Formula 12) was used.

[Chem.12
] And instead of the light-absorbing and decomposing dye represented by (Chemical formula 7), a light-absorbing and decomposing dye represented by the following (Chemical formula 13)

Capsule liquid C was obtained in exactly the same manner as capsule liquid A except that the following formula was used:

Prepared solution 1 of coupler/base emulsion dispersion B
: 170 parts of a 4% by weight aqueous solution of polyvinyl alcohol. Solution 2: Mix the compositions shown in Table 3 below to prepare Solution 2. adjusted.

[0095]

[Table 3] ──────────────────────────
────────Coupler represented by the following (Chemical formula 14)
1.4 parts

[Chemical formula 14] Triphenylguanidine (organic basic compound)
6 parts Coloring aid shown below (Chemical formula 15)
14 parts

[Chemical formula 15] Tricresyl phosphate
10 parts ethyl acetate
Part 20────────────────────────
────────The above solution 2 was added to the aqueous solution 1 above and emulsified and dispersed at 20°C to obtain an emulsified dispersion B.

Preparation of coating liquid A (cyan) Capsule liquid B5
10 parts of coupler/base emulsion dispersion A and 5 parts of distilled water were stirred and mixed to prepare a coating liquid A.

Preparation of coating liquid B (magenta) Capsule liquid C
Coating liquid B was prepared by stirring and mixing 4.9 parts of a 5% by weight aqueous solution of hydroquinone, 0.2 parts of a 5% by weight aqueous solution of hydroquinone, and 3.7 parts of coupler/base dispersion B.

Preparation of coating liquid C (yellow) Capsule liquid A
Coating liquid C was obtained by stirring and mixing 4.9 parts of a 5% by weight aqueous solution of hydroquinone, 0.2 parts of a 5% by weight aqueous solution of hydroquinone, and 3.7 parts of coupler/base emulsion dispersion A.

Preparation of heat-sensitive recording material Coating solution A was applied to one side of a transparent support of biaxially stretched polyethylene terephthalate film having a thickness of 75 μm which had been subjected to corona discharge treatment, and then the solid content had the composition shown in Table 4 below. The intermediate layer liquid, the coating liquid B, the intermediate layer liquid, and the coating liquid C are sequentially applied so that the dry weight of each of the coating liquids A, B, and C is 12 g/m2, and the dry weight of the intermediate layer liquid is 2 g/m2. After that, a protective layer liquid having the same composition as the above-mentioned intermediate layer liquid was further applied to give a dry weight of 2 g/m 2 to prepare a heat-sensitive recording material. Composition of intermediate layer (protective layer)

[Table 4]

0100 ──────────────────────────
──────────Silica-modified polyvinyl alcohol
Solid content: 1 part (PVA R2105: trade name manufactured by Kuraray Co., Ltd.) Colloidal silica

Solid content: 1.5 parts (Snowtex 30: trade name manufactured by Nissan Chemical Co., Ltd.) Zinc stearate

0.02 part solid content (Hydrin Z-7: trade name manufactured by Chukyo Yushi Co., Ltd.) Paraffin wax

Solid content: 0.02 parts (Hydrin P-7: trade name manufactured by Chukyo Yushi Co., Ltd.)──────────────────
────────────────────

The obtained recording material was imagewise irradiated with GaAs semiconductor laser light having a wavelength of 780 nm from the heat-sensitive layer side to obtain a yellow image. Next, Ar+ laser light with a wavelength of 660 nm was irradiated in the same manner to obtain a magenta image. Furthermore, He--Ne laser light with a wavelength of 560 nm was irradiated in the same manner to obtain a cyan image. The output of the laser beam was adjusted so that the energy was 100 mW at the surface of the heat-sensitive layer of the recording material. Next, when the entire surface of the heat-sensitive layer was exposed to light using a fluorescent lamp, a clear full-color image was obtained.

Claims (2)

[Claims] Claim 1: A substantially colorless color former and color developer, and a colored pigment that can convert laser light into thermal energy and becomes colorless by absorbing light in a specific wavelength range, on a support. A thermosensitive recording material having a thermosensitive layer containing two or more types of image forming units consisting of the following components, wherein the images formed by the respective image forming units have different hues. Recording materials. 2. The heat-sensitive recording material for laser according to claim 1 is recorded by irradiating the heat-sensitive layer side or the support side with laser light of different wavelengths one or more times in an imagewise manner, and then recording with light of a specific wavelength range. An image recording method characterized by irradiating the entire surface of the dye from the heat-sensitive layer side and/or the support side to make the colored dye colorless.