JPH0386581A - Image forming method - Google Patents

Abstract

PURPOSE:To realize the miniaturization and cost reduction of an apparatus by providing a carbon black-containing light absorbing layer on a support to form a light absorbing sheet and providing a transparent thermal color forming layer on a transparent synthetic polymer support and irradiating the same with laser beam to obtain a recording image corresponding to irradiation quantity. CONSTITUTION:A light absorbing layer is applied so as to set carbon black to 0.1 - 10g/m<2>. Not only a manuscript drawn by a usual black pencil and a manuscript written by a black felt pen or marker but also a recording image are contained over a wide range. As a transparent synthetic polymer film, for example, a polyethylene terephthalate film or a polybutylene terephthalate film is designated. As a transparent thermal recording material, for example, a substantially transparent thermal color forming layer being a recording material forming an azo dye by utilizing the reaction of a diazonium salt with a coupler is designated. A coating solution containing a microcapsule including a color former, a main component of a dispersion wherein at least a coupler is emulsified and dispersed and other additive such as a binder is prepared and applied to the transparent synthetic polymer support and dried to provide a thermal layer with solid content of 2.5 - 25g/m<2>.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an image forming method using a laser beam, and more particularly to a non-contact thermal recording method that utilizes laser beam energy as thermal energy.

(Prior art) For heat-sensitive recording materials in which a heat-sensitive coloring layer is provided on a support,
Thermal recording method, in which a thermal head is closely scanned over the surface of the recording material 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 used in facsimiles, printers, etc. ing. However, in such a thermal recording method, since the thermal head is scanned in close contact with the thermal recording material, the thermal head may wear out, and components of the thermal recording material may adhere as residue to the surface of the thermal head. This tends to cause problems such as not being able to properly record images or damaging the thermal head.

In addition, thermal recording methods using such thermal heads have limitations in high-speed control of heating and cooling of heating elements and in increasing the density of heating elements due to the structural characteristics of the thermal heads. There are difficulties in realizing high-density, high-quality recording.

On the other hand, in order to solve the problems of the thermal recording method using a thermal head as described above, a laser beam is used to
It has been proposed to perform high-speed, high-density thermal recording on heat-sensitive recording materials in a non-contact manner. For example, Unexamined Japanese Patent Publication No. 50-
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, etc. However, in such a recording method using a laser beam, the heat-sensitive coloring layer generally has difficulty absorbing light in the visible and near-infrared regions, so unless the laser output is considerably increased, the thermal energy required for coloring must be increased. Therefore, it is extremely difficult to create a small and inexpensive device. In addition, many proposals have been made to make the heat-sensitive coloring layer efficiently absorb laser light, and the common practice is to add a light-absorbing substance that matches the wavelength of the laser beam into the heat-sensitive coloring layer. . In this case, if the light-absorbing substance added is not white, the background of the recording material will be colored, resulting in low contrast and poor quality recording, which is not preferable. In general, many white light-absorbing substances are inorganic compounds, but most of them have low light absorption efficiency, and organic compounds with high light absorption efficiency and little coloring have not yet been developed.

<Object of the invention> The object of the present invention is to solve the problems seen in the prior art,
Furthermore, by using a transparent heat-sensitive recording material, rich gradation reproducibility and high contrast can be obtained, and by using a laser beam, high-speed, high-definition recording is possible without contact with the heat-sensitive recording material. It is an object of the present invention to provide an image forming method that can realize miniaturization and cost reduction of the apparatus.

<Structure of the Invention> According to the present invention, a transparent sheet comprising a light-absorbing sheet having a light-absorbing layer containing carbon black on a support and a transparent heat-sensitive coloring layer on a transparent synthetic polymer support is provided. An image forming method is provided in which the light absorption layer is irradiated with a laser beam while being in close contact with a heat-sensitive recording material, and a recorded image is obtained in a heat-sensitive coloring layer in contact with the light-absorption layer in accordance with the amount of irradiation.

At this time, it is preferable to irradiate the light absorption layer with a laser beam through the heat-sensitive recording material support and the heat-sensitive coloring layer.

The support used for providing the light absorption layer of the present invention is:
Whether it is a paper support or a synthetic polymer support,
Supports in which they are bonded to each other are also advantageously used.

The light-absorbing material used in the light-absorbing layer may be any material as long as it exhibits absorption of the laser beam used, such as copper sulfate described in JP-A-58-94495, JP-A-58-9
Cyanine dyes described in No. 4494, JP-A-57-110
In addition to the benzenedithiol-based nickel complexes described in No. 90, the benzenethiol nickel complex layer described in JP-A-54-121140, and the inorganic metal salts described in JP-A-58-145493, conventionally known metal oxides. , hydroxides, silicates, sulfates, carbonates, nitrates, complex compounds, cyanines, polyenes, etc., but their light absorption efficiency is extremely low, so the output of the laser used The light-absorbing material of the present invention is Carbon black is the most suitable.

Carbon black having an average particle diameter of 0.1 to 100 mμ is preferably used. In order to provide a light absorption layer containing carbon black on a transparent synthetic polymer film, a known water-based coating or organic solvent-based coating method is used.

At this time, in order to apply the light absorption layer stably and uniformly and to maintain the strength of the coating film, the following compounds can be used in combination with carbon black in the present invention. They include methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, starches, gelatin, polyvinyl alcohol, carboxy-modified polyvinylfluor, polyacrylic 7amide, polystyrene and its copolymers, polyester and its copolymers, polyethylene and its copolymers. These include polymers, epoxy resins, acrylate and methacrylate resins and their copolymers, silicone resins, polypropylene and their copolymers, polyurethane resins, and polyamide resins. Carbon black and the above compound are mixed in a weight ratio of 0.01 to 10.

Furthermore, in order to maintain a stable mixture of carbon black and the coating film forming agent, a known surfactant may be used as necessary. They include 7-ionic surfactants such as alkali metal salts of sulfosuccinic acid and alkali metal salts of polystyrene sulfonic acid, nonionic surfactants such as polyoxyethylene alkyl ethers, and cationic surfactants such as long-chain furkyltrimethylammonium salts. These include surfactants.

The light absorption layer is preferably coated with carbon black in an amount of 0.1 to 109/bo.

The light-absorbing sheet of the present invention can be used for originals written with a regular black pencil, originals written with a black felt-tip pen or marker, as well as electrophotographic images and recorded images created by thermal transfer printing. This includes a wide range of recorded images that are formed by materials that absorb the laser beam.

The transparent synthetic polymer film used in the transparent heat-sensitive recording material of the present invention is, for example, a polyester film such as polyethylene terephthalate or polybutylene terephthalate, a cellulose dielectric film such as cellulose triacetate film, a polystyrene film, a polypropylene film, Examples include polyolefin films such as polyethylene, polyimide films, polyvinyl chloride films, polyvinylidene chloride films, polyacrylic films, polycarbonate films, and these can be used alone or in combination. The transparent synthetic polymer support used in the present invention preferably has high transparency, exhibits no absorption at the wavelength of the irradiated laser beam, and has dimensional stability without being deformed by heat generated during laser irradiation. . The thickness of the support used is 10μ to 200μ.

In the transparent heat-sensitive recording material of the present invention, an electron-donating colorless dye precursor and an electron-accepting compound are brought into contact with each other by heating.
Examples include recording materials that utilize the ability to develop color by reaction and are devised to constitute a substantially transparent heat-sensitive coloring layer. The types of electron-donating dye precursors and electron-accepting compounds used in this recording material, as well as the materials that are allowed to coexist, are described in detail in, for example, JP-A-62-64592. In addition, the transparent heat-sensitive recording material used in the present invention is a recording material that forms a 7zo dye by utilizing the reaction between a diazonium salt and a coupler, and incorporates a device that has a substantially transparent heat-sensitive coloring layer. Also included are recording materials. Examples of compounds such as diazonium salts, couplers, and bases used in this recording material include, for example, JP-A-59-1
No. 90886.

The transparent heat-sensitive recording material used in the present invention can be produced, for example, by the following method.

Microcapsules containing the colorless electron-donating dye precursor described in the specification of JP-A-62-64592 as the color former and the electron-accepting compound described in the specification as the color developer are hardly soluble in water. Or prepare a coating solution consisting of an emulsified dispersion that is dissolved in an insoluble organic solvent and then emulsified and dispersed,
It can then be prepared by coating on a support and drying.

As the electron-donating dye precursor used at this time, a colorless dye precursor is appropriately selected from known compounds that develop color by donating electrons or accepting protons such as acids. Such compounds have partial skeletons such as lactones, lactams, sultones, spiropyrans, esters, and amides, and these partial skeletons are ring-opened or cleaved upon contact with a color developer. Preferred compounds include Examples include tri7lylmethane compounds, diphenylmethane compounds, xanthine compounds, thiazine compounds, and spiropyran compounds.

In the present invention, by encapsulating the above-mentioned coloring agent in microcapsules, it is possible to prevent fogging during the production of heat-sensitive recording materials, and at the same time, to improve the raw and record storage properties of the heat-sensitive recording materials. can. In this case, by selecting the wall material and manufacturing method of the microcapsules, it is possible to increase the image density during recording. The amount of coloring agent used is preferably O,OS to 5.09/nf.

Examples of the wall material of the microcapsule include polyurethane, polyurea, polyester, polycarbonate, urea-formaldehyde resin, melamine resin, polystyrene, styrene-methacrylate copolymer, styrene-acrylate copolymer, gelatin, polyvinylpyrrolidone, polyvinylfurcoll, etc. It will be done. In the present invention, two or more of these polymeric substances can be used in combination. In the present invention, among the above-mentioned polymeric substances, polyurethane, polyurea, polyamide, polyester, polycarbonate, etc. are preferred.

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

An organic solvent used to encapsulate color formers in microcapsules, dissolve monomers, and carry out encapsulation reactions, and dissolve color developers to emulsify and disperse them, or form oil droplets. The solvent can be selected depending on the properties of the compound to be dissolved, and preferably it can be selected from the compounds shown below.

In addition to ester compounds such as phosphoric esters, phthalic esters, benzoic esters, divinic esters, oxalic esters, acetic esters, and carbonic esters, naphthalene compounds such as dimethylnaphthalene, diethylnaphthalene, and diisopropylnaphthalene. , dimethylbiphenyl, diethylbiphenyl, diisopropylbiphenyl,
Biphenyl compounds such as diisobutylbiphenyl, 1-methyl-1-dimethylphenyl-1-phenylmethane, 1
- Phenylmethane compounds such as ethyl-1-dimethylphenyl-1-phenylmethane and 1-propyl-1-dimethylphenyl-1-phenylmethane, tri7lylmethane compounds such as tritolylmethane and tolyldiphenylmethane, butyl diphenyl ether, etc. diphenyl ether compounds, terphenyl compounds, etc. These organic solvents can be used alone or in combination with other organic solvents.

In the present invention, in addition to the above-mentioned organic solvents, auxiliary solvents such as ethyl acetate, isopropyl acetate, butyl acetate, methylene chloride, and chloroform can also be added as low-boiling point dissolution aids.

As the surfactant to be contained in the aqueous phase, a surfactant that does not interact with the protective colloid to cause precipitation or aggregation can be appropriately selected from anionic or nonionic surfactants. Preferred surfactants include:
Examples include sodium alkylbenzenesulfonate such as sodium dodecylbenzenesulfonate, sodium furkylsulfate such as sodium lauryl sulfate, dioctyl sodium sulfosuccinate, polyoxyethylene nonylphenyl ether, and the like.

The emulsified dispersion of a color developer in the present invention is produced by mixing an oil phase containing a color developer and an aqueous phase containing a protective colloid and a surfactant using conventional means used for fine particle emulsification, such as high-speed stirring and ultrasonic dispersion. It can be easily obtained by mixing and dispersing.

The recording material of the present invention can be coated using a binder as described below. As a binder, polyvinyl alcohol, methylcellulose, carboxymethylcellulose, human O-oxypropylcellulose, 7-rabiya gum, gelatin, polyvinylpyrrolidone, casein, styrene-butadiene latex, acrylonitrile-butadiene latex, polyvinyl acetate, polyacrylic acid ester, ethylene - Various emulsions such as vinyl acetate copolymers can be used. The amount used is 0.5 to 59/- as solid content.

The recording material of the present invention is produced by preparing a coating liquid containing microcapsules encapsulating a color former, main components of a dispersion in which at least a color developer is emulsified and dispersed, and other additives such as a binder. It is coated on a support by a coating method such as bar coating, blade coating, F-knife coating, gravure coating, roll coating, spray coating, dip coating, curtain coating, etc. and dried to form a heat-sensitive material with a solid content of 2°5 to 259/-. Manufactured by layering.

The laser beam used in the present invention has a wavelength range in the visible, near-infrared, and infrared regions, and includes helium-neon laser, argon laser, carbon dioxide laser, YAG laser, semiconductor laser, and the like.

In the present invention, during laser beam irradiation, it is necessary that the light absorption layer and the heat-sensitive recording material are in sufficient contact with each other in order to transfer the thermal energy generated in the light absorption layer by laser irradiation to the heat-sensitive recording material without waste. Therefore, in addition to improving the smoothness of the surfaces of both coating films, it is preferable to irradiate them with a laser while applying a load to bring them into close contact.

<Effects of the Invention> In order to carry out the recording method of the present invention, a light absorption layer containing carbon black provided on a support in advance and a transparent heat-sensitive recording layer provided on a transparent synthetic polymer support are combined. While keeping them in close contact, a laser beam is irradiated through the synthetic polymer support and the heat-sensitive recording layer. As a result, the light absorption layer generates heat, and the heat is transmitted to the heat-sensitive recording layer that is in close contact with the light absorption layer to develop color and perform necessary recording. After irradiation, the light-absorbing sheet and the heat-sensitive recording material may be separated. This method solves the problems that conventionally occurred due to close scanning between the thermal recording material and the thermal head, such as thermal head wear, debris adhesion, head destruction, and the difficulty of high-speed, high-quality recording. It is possible to do so.

<Example> A solution obtained by dissolving 70 parts of methyl ethyl ketone, 10 parts of chlorinated polyethylene, and 3 parts of carbon black in 30 parts of tetrahydrofuran was mixed, and the coating solution was well dispersed with a paint shaker and applied as a solid content onto a polyethylene terephthalate film. The light absorbing sheet of the present invention was prepared by applying the coating to a ratio of 1.09/-. On the other hand, JP-A-63-26
A transparent heat-sensitive recording material was prepared according to the method described in the Examples of Specification No. 5682. While keeping the coated surface of this heat-sensitive recording material and the coated surface of the light-absorbing sheet in close contact,
A colored image was obtained by irradiation with semiconductor laser light (G a A a junction laser). The output of the laser beam was adjusted so that 40 mJ/m- of energy was applied to the surface of the thermosensitive recording paper in 1 ms.

When the transmitted density of the colored part is measured using a Macbeth densitometer,
It was 1.05. When a similar experiment was conducted without using a light-absorbing sheet, the color density value was 021, and almost no color was observed.

Claims (2)

[Claims] (1) While bringing a light-absorbing sheet, which has a light-absorbing layer containing carbon black on a support, into close contact with a transparent heat-sensitive recording material, which has a transparent heat-sensitive coloring layer on a transparent synthetic polymer support, An image forming method in which the light absorption layer is irradiated with a laser beam to obtain a recorded image in a thermosensitive coloring layer in contact with the light absorption layer in accordance with the amount of irradiation. (2) The image forming method according to claim 1, wherein the light absorption layer is irradiated with a laser beam through the heat-sensitive recording material support and the heat-sensitive coloring layer.