JP2001047743A - Method and apparatus for thermal transfer recording - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for recording having excellent similarity to the product by a real printer by shortening a required output time of a recording material by thermal transfer recording using a laser beam. SOLUTION: Thermal transfer recording is conducted by bringing a transfer sheet 1 obtained by sequentially laminating a photothermal conversion layer 11 containing at least a near infrared absorbing material and a binder resin as main bodies and a thermal transfer ink layer 12 in this order on a base material 10 into contact with an image receiving sheet 2 by opposing a thermal transfer ink layer 12 to an image receiving surface of the sheet 2, preheating it, then laser exposing it, transferring the layer 12 to the receiving surface in an image-like state, and further retransferring the layer 12 on a transfer medium 9 by heating. Accordingly, a required output time of a recorded material is shortened by preheating, then preheating the sheet 1 and the sheet 2 so that the layer 12 can be easily transferred to the sheet 2, and then laser recording it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for the field of direct digital color proof used for print proof printing, etc.
The present invention relates to a recording method and a recording apparatus used for heat transfer of a heat mode laser system excellent in similarity to a printed matter by an actual printing machine.

[0002]

2. Description of the Related Art Conventionally, a large amount of color printing has been performed by offset printing, gravure printing, and the like. In such color printing, an original is directly or another original,
Characters, symbols, etc. are combined and color-separated to produce four-color plates of cyan, magenta, yellow, and black, and the hue, pattern, and the like are reproduced with each printing ink. Prior to mass color printing, the color tone, layout,
It is necessary to check in advance whether characters, symbols, and the like match exactly. For this purpose, a step of proof printing is conventionally performed. This proof print hardly coincides with the original from the beginning, and the printing plate is corrected each time at a different point, and this step is repeated to sufficiently match the original with the printed matter. Further, the same operation is repeated even when the original document is incomplete, thereby responding to the request of the customer.

[0003] In addition to the above-mentioned proof printing, thermal transfer recording is performed by using an ink ribbon using a sublimable dye and an image receiving sheet excellent in the receptivity of the dye for high quality applications required for printed matter. Much has been done. However, due to the difference between the sublimable dye and the pigment used in the printing ink, hue matching is not perfect. Then, instead of using the above-described sublimable dye as the thermal transfer ink, a heat-meltable ink using a pigment as a coloring agent is used. Due to the limitations of high-speed control of heating and cooling of heating elements and increasing the density of heating elements, there are limits to achieving high-speed recording, high-density recording, and high-quality recording. It has begun to perform non-contact, high-speed, high-density thermal recording on thermal transfer recording materials.

A thermal transfer recording material using the laser beam is provided on a substrate with a light-to-heat conversion layer comprising a near-infrared absorbing material and a binder, a transfer sheet having a thermal transfer ink layer provided on the light-to-heat conversion layer, An image receiving sheet on which a cushion layer, a release layer, and an image receiving layer are formed in this order, the thermal transfer ink layer and the image receiving layer are superimposed, and a laser beam is irradiated to transfer and form an image on the image receiving layer. The transferred image receiving layer is re-transferred to a transfer-receiving body (paper or the like) to obtain a target recorded matter.

[0005]

However, in the above-mentioned thermal transfer recording using a laser beam, the laser output level as the recording means is increased to the limit and the speed is increased. However, at present, about A2 size full color output is required. It takes 20 minutes / sheet. A thermal transfer recording material using laser light has excellent image quality, but has a problem in that the required output time is very long. Therefore, the present invention solves the above problems, and provides a recording method and a recording apparatus in which the time required for outputting a recorded matter is reduced by thermal transfer recording using a laser beam, and the approximation with a printed matter by an actual printing machine is excellent. The purpose is to:

[0006]

In order to achieve the above object, a thermal transfer recording method according to the present invention comprises a method of forming a light-to-heat conversion layer and a thermal transfer ink layer mainly comprising at least a near-infrared absorbing material and a binder resin on a substrate. The transfer sheet and the image receiving sheet laminated in this order are brought into close contact with the thermal transfer ink layer and the image receiving surface of the image receiving sheet facing each other, pre-heated, and then subjected to laser exposure, and the thermal transfer ink layer is placed on the image receiving surface. The image is transferred in the form of an image, and the thermal transfer ink layer on which the image has been transferred is further transferred to the transfer target by heating to record the thermal transfer. As a result, the time required to obtain one printed matter in thermal transfer image formation is reduced. Further, in the thermal transfer recording method of the present invention, the preheating can be at least one of irradiation of electromagnetic waves, irradiation of infrared rays, and heating by a heat roll, and the effect of the preheating can be enhanced.

[0007] The thermal transfer recording apparatus of the present invention comprises a transfer sheet and an image receiving sheet in which at least a photothermal conversion layer and a thermal transfer ink layer mainly composed of a near-infrared absorbing material and a binder resin are laminated in this order on a substrate. A device having a preheating means, a means for performing laser exposure, and a heating means for transferring the image-transferred thermal transfer ink layer to a transfer-receiving body, with the thermal transfer ink layer and the image receiving surface of the image receiving sheet facing each other and in close contact with each other; It is. The preheating means is preferably at least one of an electromagnetic wave irradiation means, an infrared irradiation means, and a heating means using a heat roller.

The operation of the present invention is as follows. In the present invention, on a substrate, at least a light-heat conversion layer mainly composed of a near-infrared absorbing material and a binder resin, a thermal transfer ink layer, a transfer sheet laminated in this order, and an image receiving sheet,
With the image receiving surface of the image receiving sheet facing the thermal transfer ink layer,
Adhesion, pre-heating, laser exposure, transfer of the thermal transfer ink layer to the image receiving surface in an image form, and transfer of the image-transferred thermal transfer ink layer to the transfer object by heating to record thermal transfer I do. Therefore, with thermal transfer recording using laser light, without performing laser recording from the beginning, preheating is performed, the transfer sheet and the image receiving sheet are pre-heated, and the thermal transfer ink layer is easily transferred to the image receiving sheet, By performing the laser recording, the time required for outputting the recorded matter is shortened, and a printed matter excellent in approximation to the printed matter by an actual printing machine is obtained.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the thermal transfer recording method and the thermal transfer recording apparatus of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic view showing one embodiment of the thermal transfer recording apparatus of the present invention. As shown in FIG.
The transfer sheet 1 in which the light-to-heat conversion layer 11 and the thermal transfer ink layer 12 are laminated in this order, and the image receiving sheet 2 are brought into close contact with the rotating drum 3 with the thermal transfer ink layer 12 and the image receiving surface of the image receiving sheet 2 facing each other. , A heating chamber 4 for housing these members
Is provided with a waveguide 5, an antenna is inserted into the waveguide 5 (not shown), a magnetron 6 is fixed, and microwaves are irradiated from the magnetron 6 so that the transfer sheet 1 and the The image receiving sheet 2 is preheated. The microwave irradiation causes moisture to evaporate from the transfer sheet or the image receiving sheet to generate water vapor, and a small gap can be provided in the heating chamber to take the water vapor out of the heating chamber. . Further, a fan can be attached to the heating chamber to make the temperature in the heating chamber uniform.

Next, as shown in FIG. 1B, the transfer sheet 1 and the image receiving sheet 2 which are brought into close contact with the rotating drum 3 are
When the rotating drum 3 rotates, the laser exposure unit 7
After that, laser recording is performed on the back side of the transfer sheet 1 to transfer the thermal transfer ink layer 12 onto the image receiving sheet 2 in an image form. Although not shown, when the thermal transfer ink layer has been transferred onto the image receiving sheet, the transfer sheet is wound up.
Further, it is necessary to transfer the thermal transfer ink layers of each color such as yellow, magenta, and cyan to the image receiving sheet with good positional accuracy, and a suction hole is formed in the rotating drum (not shown). It is preferable that the transfer sheet is brought into close contact with and held on the rotary drum by the transfer sheet by pressing with a nip roll or the like. However, the nip roll needs to be detachable from the rotating drum and needs to be mounted at a position not in contact with the laser beam from the laser exposure unit, but the number of rolls to be mounted is not limited.

Thereafter, as shown in FIG. 1C, the image receiving sheet 2 adhered on the rotating drum 3 is
Is rotated to bring the thermal transfer ink layer 12 transferred onto the image receiving surface of the image receiving sheet 2 into contact with the transfer-receiving body 9,
The thermal transfer ink layer 12 is transferred to the transfer object 9 by the heating means of the heat roll 8, and thermal transfer recording is performed on the transfer object 9. In the thermal transfer recording apparatus shown in FIG. 1, an electromagnetic wave is irradiated for 60 seconds to perform preheating, and then yellow, magenta,
To transfer cyan and black thermal transfer ink layers,
When the laser recording was performed, the processing time for image formation when the conventional preheating was not performed was changed from 20 minutes / sheet (A2 size) to about 15 minutes / sheet (A2 size). The required time was shortened.

(Preliminary Heating Means) In the thermal transfer recording method and recording apparatus of the present invention, the thermal transfer ink layer and the image receiving surface of the image receiving sheet are opposed to each other and brought into close contact with each other. And preheating. Electromagnetic waves have various wavelengths and frequencies, and can be arbitrarily selected.
It is preferable to use a microwave (high frequency) whose wavelength is typically about 12.24 cm. Electromagnetic waves are generated from high frequency sources (magnetrons and waveguides) as described above,
In the heating chamber, the transfer sheet and the image receiving sheet are irradiated in a state of close contact. It is preferable to adjust the irradiation time as appropriate according to the number of microwave outputs. For example, it is preferable to heat the thermal transfer ink layer of the transfer sheet at 40 to 60 ° C. In the present invention, at least one of an electromagnetic wave irradiation unit, an infrared irradiation unit, and a heating unit using a heat roller can be used as the preheating unit. In the present invention, it is preferable to use a conventionally known heating means such as an infrared irradiation means or a heating means using a heat roller in combination with the electromagnetic wave irradiation means to further enhance the effect of preheating.

(Laser exposure means) As the laser light source used in the present invention, for example, a semiconductor laser, LE
D, a helium neon laser, a YAG laser, a carbon dioxide laser, or the like can be used. These laser light sources are preferably those that can easily condense by an optical system, have a large output energy, and can generate wavelength light that can be easily converted into heat. The laser beam used in the present invention is usually 680 to 11
Semiconductor laser light that oscillates near-infrared light of
Scanning exposure is preferably performed using a beam spot condensed to a diameter of 100 μm. The transfer sheet may be directly irradiated with light from such a laser light source, or the transfer sheet may be irradiated with light through a condenser lens or a reflecting mirror.

(Heating means) It is necessary to provide a means for transferring the thermal transfer ink layer having the image transferred on the image receiving sheet to a transfer-receiving body. The means is a heating means. FIG. 1 (c)
As shown in (1), the surface of the image receiving sheet on which the image is formed and the object to be transferred are superimposed and pressed by a hot roll, heated by a thermal head, or irradiated with infrared rays to form a thermal transfer ink layer on the image receiving sheet. Is transferred to the transfer object.

(Transfer Sheet) In the thermal transfer recording method and thermal transfer recording apparatus of the present invention, the transfer sheet to be used comprises at least a photothermal conversion layer and a thermal transfer ink layer mainly composed of a near infrared absorbing material and a binder resin on a base material. The layers are stacked in this order. (Substrate) As the substrate, the same substrate as that used in the conventional thermal transfer recording material can be used as it is, and other substrates can be used. When irradiating from the transfer sheet side, it is preferable to use a substrate having high transparency, and it is particularly preferable that the transmittance of the wavelength of the laser beam to be used is 60% or more.

Specific examples of preferred substrates include, for example,
Polyester such as polyethylene terephthalate, polypropylene, cellophane, polycarbonate, cellulose acetate, triacetyl cellulose, polyethylene, polyvinyl chloride, polystyrene, nylon, polyimide, polyvinylidene chloride, polyvinyl alcohol, fluororesin, chlorinated rubber, ionomer, etc. Paper with good thermal resistance, such as plastic, condenser paper, paraffin paper, etc.
There are nonwoven fabrics and the like, and a substrate obtained by combining these may be used. The thickness of the substrate can be appropriately changed depending on the material so that its strength and thermal conductivity are appropriate, but the thickness is preferably, for example, 2 to 180 μm.
In the case where an adsorption drum is used as the material holding means, 50 to 125 μm is preferable because a sufficient printing pressure can be obtained.

(Light-to-Heat Conversion Layer) The light-to-heat conversion layer is a layer that is provided on a substrate and converts laser light, which is applied to a transfer sheet for recording, into heat. The light-to-heat conversion layer mainly includes a near-infrared absorbing material, which is a light-to-heat conversion material, and a binder resin. Examples of the near-infrared absorbing material include pigments (organic compounds) such as carbon black, cyanine-based, polymethine-based, azurenium-based, squalium-based, thiopyrylium-based, naphthoquinone-based, and anthraquinone-based, phthalocyanine-based, azo-based, and thioamide-based materials. Examples thereof include an organic metal complex and the like, and one or more of these can be used in combination.

As the binder resin for the light-to-heat conversion layer, a resin having a high glass transition temperature and a high thermal conductivity, such as polymethyl methacrylate, polycarbonate, polystyrene, ethyl cellulose, nitrocellulose, polyvinyl alcohol, polyvinyl acetal, polyvinyl butyral, and polyvinyl General heat-resistant resins such as formal, polyester, chlorinated polypropylene, chlorinated polyethylene, polyvinyl chloride, polyamide, polyimide, polyetherimide, polysulfone, polyethersulfone, and aramid can be used. Further, as the binder in the light-heat conversion layer, a water-soluble polymer can also be used. The water-soluble polymer is preferable in that it has good releasability from the thermal transfer ink layer, has good heat resistance during light irradiation, and has little so-called scattering even with excessive heating. When a water-soluble polymer is used, it is desirable that the photothermal conversion substance be modified to be water-soluble (by introducing a sulfone group or the like) or dispersed in an aqueous system.

Further, by incorporating various release agents into the light-to-heat conversion layer, the releasability between the light-to-heat conversion layer and the thermal transfer ink layer can be increased, and the sensitivity can be improved. As a release agent,
Silicone release agents (polyoxyalkylene-modified silicone oil, alcohol-modified silicone oil, etc.), fluorine-based surfactants (perfluorophosphate ester-based surfactants), and various other surfactants with hydrophilic properties In the present invention, in particular, in the preheating, when the microwave is irradiated, the light-to-heat conversion layer of the transfer sheet retains moisture so that heat is effectively conducted to the transfer sheet and the transfer sheet is wrinkled. This is important to prevent large deformations such as the above.

The light-to-heat conversion layer is formed by adding a near-infrared absorbing material, a binder resin, and an additive as described above, and further mixing and adjusting a solvent component such as water and an organic solvent as necessary. The coating liquid for forming a layer can be applied and dried by a conventionally known method such as gravure direct coating, gravure reverse coating, knife coating, air coating, and roll coating. However, it is preferable to use water as the solvent of the coating liquid for forming a light-to-heat conversion layer in order to retain moisture in the light-to-heat conversion layer of the transfer sheet. The thickness of the light-to-heat conversion layer is preferably from 0.1 to 3 μm when dried, and the content of the near-infrared absorbing material in the light-to-heat conversion layer is usually such that the absorbance at the wavelength of the light source used for image recording is from 0.3 to 3. It can be determined to be zero. Generally, the absorbance is 0.4 ~
About 1.5 is sufficient.

(Thermal Transfer Ink Layer) The thermal transfer ink layer is composed mainly of a coloring material and a binder resin, and the adhesive force with the image receiving sheet becomes stronger than the adhesive force with the transfer sheet side by heating during printing. The image is transferred to the image receiving sheet side. Examples of the coloring material include pigments such as inorganic pigments and organic pigments, and dyes. Examples of the inorganic pigment include titanium dioxide, carbon black, zinc oxide, Prussian blue, cadmium sulfide, iron oxide, and chromates of lead, zinc, barium, and calcium. Examples of the organic pigment include azo-based, thioindigo-based, anthraquinone-based, anthranthrone-based, and triphenedioxazine-based pigments, vat dye pigments, phthalocyanine pigments (eg, copper phthalocyanine) and derivatives thereof, and quinacridone pigments.

The above-mentioned coloring material has good properties as a recording material, for example, has a sufficient coloring density,
Those which do not discolor by heat, temperature, etc. are preferred. Also,
According to the required color tone, an appropriate one can be selected from carbon black, organic pigments and inorganic pigments. The content of the coloring material in the thermal transfer ink layer is not particularly limited, but is usually in the range of 5 to 70% by weight, preferably 10 to 60% by weight. The binder of the thermal transfer ink layer is preferably composed mainly of a resin, and specific examples of the resin include an acrylic resin, a cellulose resin, a melamine resin, a polyester resin, a polyamide resin, a polyolefin resin, and an acrylic resin. And thermoplastic elastomers such as styrene resin, polyamide, ethylene-vinyl acetate copolymer, vinyl chloride-vinyl acetate copolymer, and styrene-butadiene rubber. Particularly, those having a relatively low softening point conventionally used as a heat-sensitive adhesive, for example, a softening point of 50 to 150 ° C are preferable.

In addition, if necessary, wax components can be mixed and used to such an extent that heat resistance and the like are not impaired. Examples of the wax include microcrystalline wax, carnauba wax, and paraffin wax. Furthermore, various types such as Fischer-Tropsch wax, various low molecular weight polyethylenes, wood wax, beeswax, spermaceti, Ibota wax, wool wax, shellac wax, candelilla wax, petrolactam, polyester wax, partially modified wax, fatty acid ester, fatty acid amide, etc. Wax. Among them, particularly, the melting point is 50
What is -85 degreeC is preferable. When the temperature is 50 ° C. or less,
A problem arises in storage stability, and if the temperature is higher than 85 ° C., the printing sensitivity becomes insufficient.

The thermal transfer ink layer is formed by adding the colorant component and the binder component as described above, and various additives such as a dispersant and an antistatic agent as required, and further adding water and A coating solution for forming a thermal transfer ink layer prepared by mixing and adjusting a solvent component such as an organic solvent, by a conventionally known method such as hot melt coating, hot lacquer coating, gravure direct coating, gravure reverse coating, knife coating, air coating, and roll coating. , Dry thickness of 0.
It is provided with a thickness of from 0.5 to 5 μm, preferably from 0.2 to 1.5 μm. When the thickness of the dried coating film is less than 0.05 μm, a uniform ink layer cannot be obtained due to the problem of film forming properties, which causes a reduction in the abrasion of printed matter. Also, when the thickness exceeds 5 μm, high energy is required at the time of print transfer,
Insufficient printing sensitivity.

However, the thermal transfer ink layer described above also
It is desirable to retain moisture as described in the light-to-heat conversion layer. Addition of various hydrophilic surfactants or the like, or using water as a solvent for the coating liquid, in preheating, when irradiating with microwaves, by holding moisture in the thermal transfer ink layer of the transfer sheet, This is important in that heat is effectively conducted to the transfer sheet and that the transfer sheet is not significantly deformed such as wrinkles.

(Primer Layer) When the adhesion between the substrate and the light-to-heat conversion layer is weak, the transfer sheet may be provided with a primer layer between the substrate and the light-to-heat conversion layer to provide a light-to-heat conversion layer. Adhesion can be strengthened. As the resin used for the primer layer, for example, alkyd resin, polyester resin,
Polyvinyl acetate resin, vinyl chloride-vinyl acetate copolymer resin, NBR resin, SBR resin, polyurethane resin, acrylic resin, polyamide, and the like are used alone, as a mixture, or as a modified product. The modified product is, for example, a product obtained by copolymerizing or grafting a monomer containing a hydroxyl group, a carboxylic acid, or a quaternary ammonium salt to increase the adhesiveness and hydrophilicity.

In order to improve the adhesion of the primer layer and the strength of the coating film, the above resin may be crosslinked with various curing agents, for example, epoxy resin, melamine resin, isocyanate and the like. The method for forming the primer layer can be selected from the same methods as those for forming the light-to-heat conversion layer described above, and the thickness of the primer layer when dried is 0.01 to 50 μm, preferably 0.1 to 50 μm.
The thickness is preferably 1 to 10 μm.

(Cushion Layer) The transfer sheet may have a cushion layer between the substrate and the light-to-heat conversion layer.
At the time of printing by laser light irradiation, the adhesion between the transfer sheet and the transfer medium that can be used repeatedly can be improved. In order to provide this cushioning property, a material having a low elastic modulus or a material having rubber elasticity may be used. Specifically, natural rubber, acrylate rubber, butyl rubber, nitrile rubber, butadiene rubber, isoprene rubber, styrene-butadiene rubber, chloroprene rubber, urethane rubber, silicone rubber, acrylic rubber, fluorine rubber, neoprene rubber, chlorosulfonated polyethylene,
Epichlorohydrin, ethylene-propylene-diene rubber, elastomers such as urethane elastomers, polyethylene, polypropylene, polybutadiene, polybutene,
Impact-resistant ABS resin, polyurethane, ABS resin, acetate, cellulose acetate, amide resin, polytetrafluoroethylene, nitrocellulose, polystyrene, epoxy resin, phenol-formaldehyde resin, polyester, impact-resistant acrylic resin, styrene-
Butadiene copolymer, ethylene-vinyl acetate copolymer,
Acrylonitrile-butadiene copolymer, vinyl chloride-
Examples of the resin include a resin having a small elastic modulus, such as a vinyl acetate copolymer, polyvinyl acetate, a vinyl chloride resin containing a plasticizer, a vinylidene chloride resin, polyvinyl chloride, and polyvinylidene chloride.

Examples of the shape memory resin usable as the cushion layer include polynorbornene and a styrene-based hybrid polymer in which a polybutadiene unit and a polystyrene unit are combined. Also,
These materials can be applied to the substrate to give the substrate itself cushioning properties. Although the thickness of the cushion layer varies depending on various factors such as the type of resin or elastomer used and the use of a mat material, it cannot be unconditionally determined, but is usually in the range of 5 to 100 μm. As a method for forming the cushion layer, a solution obtained by dissolving or dispersing the above material in a solvent or in the form of a latex, a blade coater, a roll coater, a bar coater, a curtain coater, a coating method such as a gravure coater, an extrusion lamination method with a hot melt, A method of laminating a cushion layer film or the like can be applied.

(Release Layer) In the present invention, a release layer may be formed between the light-to-heat conversion layer and the thermal transfer ink layer so that the thermal transfer ink layer is released from the light-to-heat conversion layer and easily transferred by laser light irradiation. it can. The release layer can be composed of wax alone, but is preferably composed of wax and / or a binder resin of a thermoplastic resin. Wax has a melting point or softening point of 50 ° C to 100 ° C
Natural waxes such as beeswax, spermaceti, wood wax, rice bran wax, carnauba wax, candelilla wax, montan wax; synthetic waxes such as paraffin wax, microcrystalline wax, oxidized wax, ozokerite, ceresin, ester wax, polyethylene wax; margarine Higher saturated fatty acids such as acids, lauric acid, myristic acid, palmitic acid, stearic acid, freunic acid and behenic acid; higher saturated monohydric alcohols such as stearyl alcohol and behenyl alcohol; higher esters such as fatty acid esters of sorbitan; And higher fatty acid amides such as oleic acid amide.

As the thermoplastic resin in the release layer, for example, an ethylene copolymer such as an ethylene-vinyl acetate resin, a polyamide resin, a polyester resin, a polyurethane resin, a polyolefin resin, an acrylic resin,
Cellulose resin, vinyl chloride resin, rosin resin,
Resins such as petroleum resins, ionomer resins, elastomers such as natural rubber, styrene-butadiene rubber, isoprene rubber, chloroprene rubber, ester gums, rosin maleic acid resins, rosin phenol resins, rosin derivatives such as hydrogenated rosins, phenol resins , Terpene resins, cyclopentadiene resins, aromatic resins and the like can also be used.

The release layer is formed by the above-mentioned wax,
Thermoplastic resins, other waxes such as higher fatty acids, higher alcohols, higher fatty acid esters, amides, higher amines, silicone oils, solid waxes such as polyethylene wax, fluorine-based or phosphate-based surfactants, etc. The coating liquid for forming a release layer to which the release agent is added is dried in a dry state by a conventionally known method such as hot melt coating, hot lacquer coating, gravure direct coating, gravure reverse coating, knife coating, air coating, or roll coating. The thickness is about 0.10 to 4 μm. When the thickness of the dried coating film is less than 0.10 μm, the adhesion between the light-to-heat conversion layer and the thermal transfer ink layer is improved, and a good peeling effect cannot be obtained. When the thickness exceeds 4 μm,
This is not preferable because the transfer sensitivity during printing decreases.

(Adhesive Layer) In the transfer sheet used in the present invention, an adhesive layer is formed on the thermal transfer ink layer to improve the adhesiveness between the image receiving sheet and the transferred ink layer. The adhesive layer can be mainly composed of a thermoplastic resin and / or waxes, amides, esters and salts of higher fatty acids, which are softened by heating by a laser beam irradiation means to exhibit adhesiveness. Further, an anti-blocking agent such as a powder of a fluororesin or an inorganic substance can be contained.

As the thermoplastic resin, for example, ethylene-
Vinyl acetate copolymer, ethylene-acrylate copolymer, polyester resin, polyethylene, polystyrene, polypropylene, polybutene, petroleum resin, vinyl chloride resin, vinyl chloride-vinyl acetate copolymer, vinylidene chloride resin, methacrylic resin, polyamide , Polycarbonate, polyvinyl formal, polyvinyl butyral, polyvinyl acetate, polyisobutylene, polyacetal, natural rubber, acrylate rubber, butyl rubber, nitrile rubber, butadiene rubber, isoprene rubber, styrene-butadiene rubber, chloroprene rubber, urethane rubber,
Elastomers such as silicone rubber, acrylic rubber, fluorine rubber, neoprene rubber, chlorosulfonated polyethylene, epichlorohydrin, ethylene-propylene-diene rubber, urethane elastomer, etc., and the like. Particularly, a relatively low softening point conventionally used as a heat-sensitive adhesive. For example, those having a softening point of 50 to 150 ° C are preferable.

The adhesive layer is formed by hot-melt coating of the above-mentioned materials and additives or a coating solution for forming an adhesive layer in which an appropriate organic solvent or water is dissolved or dispersed in a conventionally known hot-melt coat or hot-lacquer coat. , A gravure direct coat, a gravure reverse coat, a knife coat, an air coat, a roll coat, etc., to provide a thickness of 0.10 to 5 μm in a dry state. If the thickness of the dried coating film is less than 0.10 μm, the adhesiveness between the image receiving sheet and the thermal transfer ink layer is poor, resulting in poor transfer during printing. On the other hand, if the thickness exceeds 5 μm, the transfer sensitivity at the time of printing decreases, and satisfactory printing quality cannot be obtained.

(Back Layer) The transfer sheet may be provided with a back layer on the side opposite to the surface on which the light-to-heat conversion layer and the thermal transfer ink layer of the base material are provided. The back surface layer can be provided as a lubricating layer for improving the mechanical transportability of the transfer sheet and preventing curling, and as an antistatic layer for preventing static charge and the like, and as a blocking preventing layer. A lubricating layer can be provided on the side of the lubricating layer substrate opposite to the surface on which the light-to-heat conversion layer and the thermal transfer ink layer are provided, for the purpose of improving the transferability of the transfer sheet and preventing curling. As the lubricating layer having such a function, a layer obtained by adding an organic filler such as a fluorine resin or a polyamide resin to an acrylic resin or the like can be used. For example, it is preferable to use an acrylic polyol or an organic filler. Examples of the acrylic polyol include polymers such as ethylene glycol methacrylate and propylene glycol methacrylate. In addition, the ethylene glycol moiety
Trimethylene glycol, butanediol, pentanediol, hexanediol, cyclopentanediol,
Those such as cyclohexanediol and glycerin can also be used. These acrylic polyols not only contribute to curl prevention, but also easily retain additives such as organic and inorganic fillers, and have good adhesion to a substrate.

As the lubricating layer, an acrylic polyol cured with a curing agent can be used. As the curing agent, generally known curing agents can be used, and among them, isocyanate compounds are preferable. Acrylic polyol reacts with an isocyanate compound to form a urethane bond to be cured and three-dimensionally, thereby improving heat-resistant storage stability and solvent resistance, and further improving adhesion to a substrate. The amount of the curing agent to be added is preferably 1 to 2 with respect to one reactive group equivalent of the resin. Further, it is preferable to add an organic filler to the lubricating layer. By the action of the filler, the transferability of the transfer sheet in a laser printer or the like is improved, and the storage property of the transfer sheet is also improved, such as prevention of blocking. Examples of the organic filler include an acrylic filler, a polyamide filler, a fluorine filler, and a polyethylene wax.

The lubricating layer is prepared by adding the above-mentioned resin and organic filler arbitrarily and kneading the mixture sufficiently with a solvent, diluent or the like to produce a coating liquid, In the same manner as the receiving layer forming means, a slip layer is formed by applying and drying by forming means such as a gravure printing method, a screen printing method, and a reverse roll coating method using a gravure plate. The thickness of the lubricating layer is 0.01 to 3.0.
It is about μm.

An antistatic layer containing the following antistatic agent can be provided on the back surface of the transfer sheet in order to prevent the transfer sheet from being contaminated by dust and to stabilize the transfer in a printer. As the antistatic agent, any of conventionally known cations, anions, zwitterions and nonionics can be used. Examples thereof include cationic antistatic agents such as quaternary ammonium salts and polyamine derivatives, anionic antistatic agents such as alkyl phosphates, and nonionic antistatic agents such as fatty acid esters. The antistatic layer may be added with the above antistatic agent and a lubricant such as an organic or inorganic filler, and a compounded solution obtained by dissolving or dispersing them in a solvent by a known method, that is, gravure coating, gravure reverse coating. It is formed by applying and drying by a method such as roll coating. The thickness of the antistatic layer is 0.0
It is about 01 to 0.1 μm.

Anti- blocking layer The anti- blocking layer can be mainly composed of particles and a binder resin. As the particle material, inorganic particles such as silica, calcium carbonate, and clay, MMA, styrene,
Organic particles such as benzoguanamine are used. The particle size is
Usually, it is 1.0 to 50 μm, preferably 5 to 30 μm. The binder resin is preferably a thermoplastic resin having a Tg of 50 ° C. or higher. In particular, polyester resins, urethane resins, acrylic resins, and the like are preferable because they have high adhesiveness to the base material. The amount of the particles to be added is about 0.1 to 30 parts by weight, preferably 1 to 5 parts by weight, based on 100 parts by weight of the binder resin. If the number of particles is smaller than this, the effect of preventing blocking is reduced. On the other hand, if the number of particles is larger, transparency is reduced and heat conversion efficiency is reduced. The thickness of the anti-blocking layer is usually 0.2 to 20 μm, preferably 0.5 to 10 μm.

(Image-Receiving Sheet) The image-receiving sheet used in the present invention receives the thermal transfer ink layer peeled off from the transfer sheet to form an image. Usually, an image receiving layer is provided on a base material, and the base material may be constituted by itself. The base material of the image receiving sheet holds the image receiving layer, heats during laser beam irradiation thermal transfer, and handling under preheating conditions.
Those having mechanical strength to the extent that they do not hinder are preferable.
The material of such a base material is not particularly limited, and known materials can be used.

Specific examples of the binder for the image receiving layer include adhesives such as a polyvinyl acetate emulsion adhesive, a chloroprene adhesive, an epoxy resin adhesive, a natural rubber, a chloroprene rubber, a butyl rubber, and a polyacrylate. , Nitrile rubber, polysulfide, silicon rubber, petroleum resin and other adhesives, recycled rubber, vinyl chloride resin, SBR, polybutadiene resin, polyisoprene, polyvinyl butyral resin, polyvinyl ether, ionomer resin, SIS, SEBS , Acrylic resin, ethylene-vinyl chloride copolymer, ethylene-acryl copolymer, ethylene-vinyl acetate resin (EVA), PVC-grafted EVA resin, EVA-grafted PVC resin, vinyl chloride resin, various modified olefins, polyvinyl butyral, polyester Resins, styrene-acrylic resins,
Urethane resin, etc., and has a relatively low softening point, for example, 5
Those having a softening point of 0 to 150 ° C are preferred.

The image receiving layer preferably contains a mat material. As the mat material, inorganic particles such as silica, calcium carbonate, and clay, and organic particles such as MMA, styrene, and benzoguanamine are used. The particle size is usually 1.0 to 5
It is 0 μm and preferably 5 to 30 μm. The image receiving layer is composed of a binder and a mat material, and various additives that are added as necessary. The method of forming the image receiving layer is a coating solution for forming an image receiving layer dissolved or dispersed in an appropriate organic solvent or water, which is conventionally known. A thickness of about 0.1 to 20 μm is provided on a substrate in a dry state by a method such as gravure direct coating, gravure reverse coating, knife coating, air coating, and roll coating.

Further, since the image-receiving sheet on which the image is formed is re-transferred to another transfer-receiving member, the substrate is made of a resin film, such as a polypropylene or polyethylene terephthalate, which has microvoids inside the cushioning and heat insulating properties. Resin film is preferable, and between the base material and the image receiving layer, a cushion layer as described in the transfer sheet,
It is also preferable to provide a release layer.

(Repeatable Transfer Medium) In the thermal transfer recording method and thermal transfer recording apparatus of the present invention, the description has been made mainly of transferring the thermal transfer ink layer of the transfer sheet to the image receiving sheet, but the thermal transfer ink layer is repeatedly used. It is also possible to perform thermal transfer recording by transferring an image-transferred thermal transfer ink layer to a transfer medium by heating, and then transferring the image-transferred thermal transfer ink layer from the transfer medium to an object to be transferred.

The transfer sheet and the image receiving sheet are superposed on the thermal transfer ink layer and the image receiving surface, irradiated with a laser beam to transfer and form an image on the image receiving surface, and further transferred onto the image formed thermal transfer ink layer. Although the image is transferred to the body, a portion of the image receiving sheet that is not transferred to the transfer receiving body, such as the base material, is discarded, and the material and manufacturing cost are extremely high. On the other hand, it is possible to eliminate the discarded member of the image receiving sheet and to provide the transfer medium that can be used repeatedly with the function of the image receiving sheet. Further, at least an image receiving layer may be provided on the surface of a transfer medium that can be used repeatedly, so that the thermal transfer ink layer from the transfer sheet can be easily transferred.

[0047]

As described above, in the present invention, on the base material,
A transfer sheet in which at least a near-infrared absorbing material and a light-to-heat conversion layer mainly composed of a binder resin and a thermal transfer ink layer are laminated in this order, and an image-receiving sheet, and the thermal transfer ink layer and the image-receiving surface of the image-receiving sheet are opposed to each other. Preheating, followed by laser exposure, transferring the thermal transfer ink layer imagewise onto the image receiving surface, and then transferring the image-transferred thermal transfer ink layer to the transfer target by heating to record the thermal transfer. went. Therefore, with thermal transfer recording using laser light, without performing laser recording from the beginning, preheating is performed, the transfer sheet and the image receiving sheet are pre-heated, and the thermal transfer ink layer is easily transferred to the image receiving sheet, By performing laser recording, the required output time of the recorded material is reduced, and the applied energy of laser recording is reduced,
Transfer sensitivity can also be improved. And what was excellent in the similarity with the printed matter by the actual printing machine was obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one embodiment of a thermal transfer recording apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transfer sheet 2 Image receiving sheet 3 Rotating drum 4 Heating chamber 5 Waveguide 6 Magnetron 7 Laser exposure part 8 Heat roll 9 Transfer object 10 Base material 11 Light-to-heat conversion layer 12 Thermal transfer ink layer

Claims (4)

[Claims] 1. A transfer sheet in which at least a light-to-heat conversion layer mainly composed of a near-infrared absorbing material and a binder resin and a thermal transfer ink layer are laminated on a substrate in this order, and an image receiving sheet. The image receiving surface of the sheet is opposed to and brought into close contact with the sheet, preheating is performed, then laser exposure is performed, the thermal transfer ink layer is image-transferred onto the image receiving surface, and the image-transferred thermal transfer ink layer is further transferred onto the transfer target. A thermal transfer recording method, wherein thermal transfer recording is performed by transferring by heating. 2. The method according to claim 1, wherein the preheating includes at least one of electromagnetic wave irradiation, infrared irradiation, and heating by a heat roll.
2. The thermal transfer recording method according to claim 1, wherein the thermal transfer recording method is performed. 3. A transfer sheet in which at least a photothermal conversion layer mainly composed of a near-infrared absorbing material and a binder resin and a thermal transfer ink layer are laminated on a base material in this order, and an image receiving sheet. Thermal transfer recording, comprising: a preheating means, a means for performing laser exposure, and a heating means for transferring an image-transferred thermal transfer ink layer to an object to be transferred, with the image receiving surface of the sheet opposed to and in close contact with the image receiving surface. apparatus. 4. The thermal transfer recording apparatus according to claim 3, wherein said preliminary heating means is at least one of an electromagnetic wave irradiation means, an infrared irradiation means, and a heating means using a heat roller.