JP2003246153A - Ink sheet for laser thermal transfer recording - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink sheet wherein the lowering of the density of a coloring material due to thermal decomposition under a high temperature in laser recording hardly occurs, of which the coloring material is decomposed little in the final image when it is used under an indoor fluorescent lamp or natural light or in long-time storage and which attains an image of high accuracy of which the lowering of the density and a change in the hue are little. <P>SOLUTION: In the ink sheet for laser thermal transfer recording having at least a photothermal conversion layer and an ink layer on a substrate, the ink layer contains a quinacridon compound expressed by general formula (1), an anthraquinone compound expressed by general formula (2), or a perylene compound expressed by general formula (3). <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink sheet for forming an image by laser irradiation, and more specifically, by laser irradiation based on a digital image signal, transfer type high-definition image or color proof (DDC) in the field of printing.
P: direct digital color proof).

[0002]

2. Description of the Related Art With the spread of image forming technology from digital images, the need for DDCP is increasing especially in the field of printing. In printing, color reproduction and stable reproduction of the printed matter are required, and output is also required with the paper type and paper thickness used for actual printing.

Conventionally, a thermal transfer recording system using a heating device such as a thermal head or an energizing head has been used.
The resolution is limited by the arrangement density of the head heating elements,
Further, it is difficult to control the heat generation temperature of the heat generating element at high speed because of the characteristics of the heat generating element, and it is difficult to obtain an image with higher resolution.

However, in recent years, a laser thermal transfer recording method using a high-output light source such as a laser has attracted attention and has been proposed as an image recording method in fields requiring high-resolution output, such as medical and printing fields. .

The laser thermal transfer recording system converts a laser beam, including laser ablation transfer, laser melting thermal transfer, and laser die transfer, into heat, and uses the thermal energy to generate a coloring material (in the case of a dye only, a dye and a binder are used). When it is included, it may be formed with a pigment and a binder) and the like) is transferred to an image receiving sheet to form an image on the image receiving sheet.

In image transfer using a photothermal conversion type ink sheet, an ink layer, that is, an image forming layer is transferred from the ink sheet to the image receiving sheet, and, if necessary, the final image transfer medium (paper or the like) from the image receiving sheet. The final image is obtained by transferring the image forming layer of the image receiving sheet to. This final image is used as a color proof.

In the image forming system using such a laser recording technique, since the focus beam diameter of the laser beam having relatively high energy is focused to about 10 μm and used, it is photothermally converted with high efficiency and used for thermal recording. Extremely higher thermal energy can be obtained than a heating device such as a thermal head used. Therefore, the temperature of the area irradiated by the laser is
There is a case where the temperature reaches an extremely high temperature locally and the coloring material (pigment) contained in the ink layer in the irradiation region is thermally decomposed. When the coloring material is thermally decomposed, it loses its hue and the image density of the image transferred onto the image receiving layer is lowered.

Even when direct thermal decomposition due to laser irradiation does not occur, if it is used under a room fluorescent lamp, natural light, or stored for a long time during the period when it is used as a color proof, it will be recorded at a high temperature by laser recording. There is a case where the decomposition of the coloring material of the final image progresses due to the influence of exposure to. When the color material is decomposed, a hue difference and a density difference occur as compared with immediately after the image formation, and the color proof function is lost.

Therefore, there is a demand for a laser thermal transfer ink sheet which is not easily decomposed by heat as described above even at a high temperature due to high power laser recording, and has good light resistance and storability of the final image.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to prevent a decrease in concentration due to thermal decomposition of a coloring material even at a high temperature during laser recording. An object of the present invention is to provide an ink sheet for obtaining a high-definition image in which the decomposition of a coloring material is small in the final image when used in an indoor fluorescent lamp, under natural light, or when stored for a long period of time, and a decrease in density and a hue change are small.

[0011]

The above objects of the present invention have been achieved by the following constitutions.

1) A laser thermal transfer ink sheet having at least a photothermal conversion layer and an ink layer on a support, wherein the ink layer contains a quinacridone compound represented by the general formula (1). Ink sheet.

In place of the above quinacridone compound,
2) An anthraquinone compound represented by the general formula (2),
3) The same effect can be obtained by using the perylene-based compound represented by the general formula (3).

In the general formula (1), 4) R ₁ and R ₂
Are both methyl groups, m = n = 1, and R ₃ is a hydrogen atom, 5) R ₁ and R ₂ are both chlorine atoms, and m
= N = 1 and R ₃ is a hydrogen atom, 6).
R ₁ and R ₂ are both hydrogen atoms, m = n = 1, R ₃ is an oxo group, and k = 2; 7) R ₄ , R _6, and R _{6 in the} general formula (2) above. Both R ₇ are hydrogen atoms, and p = 1
And R ₅ is an amino group, R ₈ is a structure (a), 8) In the general formula (3), R ₉ and R ₁₀ are both methyl groups, 9) R ₉ and R ₁₀ are both 4-ethoxyphenyl groups, 10) R ₉ and R ₁₀ are both 3,
A 5-dimethylphenyl group is a preferred embodiment.

11) The photothermal conversion layer contains carbon black, a metal oxide or at least one infrared absorbing dye having an absorption maximum at 700 to 850 nm, and the absorbance at the absorption maximum wavelength is 0.3 to 1. 5. The ink sheet for laser thermal transfer recording according to any one of 5 above.

12) The ink layer contains at least one compound selected from the compounds represented by the general formulas (1), (2) and (3), and the melting point, softening point or glass transition temperature. The laser according to any one of the above, wherein the polymer contains 20 to 80% by mass of 20 to 150 ° C. and 80 to 20% by mass of the polymer compound, respectively, and the thickness of the ink layer is 0.2 to 1.5 μm. Ink sheet for thermal transfer recording.

Hereinafter, the ink sheet of the present invention and the image receiving sheet for receiving an image of the ink sheet will be described in more detail.

<Ink Sheet> The ink sheet of the present invention has, on one surface of a support, at least a photothermal conversion layer having a photothermal conversion function and an ink layer having a coloring material transfer function, and the ink layer has the above-mentioned general composition. It is characterized by containing at least one compound selected from compounds represented by formula (1), general formula (2) and general formula (3) (hereinafter, also referred to as "compound of the present invention"). .

An embodiment of the present invention is a film having a photothermal conversion function and a color material transfer function on a support,
At least the photothermal conversion layer and the ink layer are provided on one surface of the support, but it is also possible to impart both functions to the same layer. If necessary, a cushion layer or an easily adhesive layer, a peeling layer, or the like may be provided between these layers and the support.
It is possible to have a backcoat layer on the surface opposite these layers.

<Coloring Material> The compound of the present invention functions as a coloring material in the image forming layer, and may be formed by using a room fluorescent lamp, natural light, or decomposition of the coloring material after long-term storage after forming the final recorded image. The decrease in image density can be reduced. As a result, the ink sheet of the present invention is capable of forming a high-definition image with little reduction in image density and hue variation due to light and long-term storage.

First, the compound of the present invention will be described. In the general formula (1), R ₁ and R ₂ are each a hydrogen atom,
Halogen atom represents an alkyl group or an alkoxy group having 1 to 5 carbon atoms. The alkyl group may be linear or branched. For example, methyl, ethyl, propyl, i
Each group such as -propyl and butyl is mentioned, and among them, a methyl group is preferable. Examples of the halogen atom include chlorine, bromine and iodine atoms, and among them, chlorine atom is preferable. The alkyl portion of the alkoxy group may be linear or branched. Examples of the alkoxy group include groups such as methoxy and ethoxy.

R ₃ is a hydrogen atom, each of which has 1 to 10 carbon atoms.
5 represents an alkyl group, an alkoxy group or an oxo group. The alkyl group may be linear or branched. Examples thereof include groups such as methyl, ethyl, propyl, i-propyl, and butyl, with a hydrogen atom or an oxo group being preferred.

M and n represent an integer of 1 to 4, but 1 or 2
Is preferred. k represents an integer of 1 to 2, but 2 is preferable.

Among the compounds represented by the general formula (1),
R ₁ and R ₂ are methyl groups and R ₃ is a hydrogen atom; R ₁ and R ₂
Is a chlorine atom, R ₃ is a hydrogen atom; R ₁ and R ₂ are hydrogen atoms, and R ₃ is an oxo group, and these compounds are preferable in terms of concentration reduction and hue variation during long-term storage.

In the general formula (2), R _{4 to} R ₈ are each a hydrogen atom, a halogen atom, a hydroxyl group, an amino group, an alkyl group having 1 to 5 carbon atoms, an alkoxy group or the structure (a). Represent The alkyl group may be linear or branched, for example, methyl, ethyl, propyl,
Each group such as i-propyl and butyl can be mentioned. Examples of the halogen atom include chlorine, bromine and iodine atoms. The alkyl part of the alkoxy group may be linear or branched, and examples thereof include groups such as methoxy and ethoxy. Among the compounds represented by the general formula (2), R ₄ and R ₆
Compounds in which R ₇ and R ₇ are hydrogen atoms, and R ₅ and R ₈ are amino groups or the structure (a) are preferable in that the concentration decreases and the hue changes during long-term storage are small.

In the general formula (3), R ₉ and R ₁₀ are each a hydrogen atom, a halogen atom, a hydroxyl group, an amino group, an alkyl group having 1 to 5 carbon atoms, an alkoxy group or an alkyl group or an alkoxy group. Represents a substituted phenyl group. The alkyl group may be linear or branched, and examples thereof include methyl, ethyl, propyl, i-propyl and butyl groups. Examples of the halogen atom include chlorine, bromine and iodine atoms. The alkyl part of the alkoxy group may be linear or branched, and examples thereof include groups such as methoxy and ethoxy.

Among the compounds represented by the general formula (3),
A compound in which R ₉ and R ₁₀ are methyl groups, a compound in which a phenyl group substituted with an alkyl group or an alkoxy group (particularly 4-ethoxyphenyl, 3,5-dimethylphenyl) is used, the concentration decreases and the hue changes during long-term storage. Is preferable because it is less.

Among the compounds represented by the general formula (3),
The compound in which R ₉ and R ₁₀ are 3,5-dimethylphenyl is the most preferable in that the concentration decrease and the hue variation during the long-term storage are small.

Specific examples of the compound represented by formula (1), (2) or (3) are shown below, but the invention is not limited thereto.

[0030]

[Chemical 5]

[0031]

[Chemical 6]

These compounds can be synthesized by a general method described in, for example, Handbook of Pigments.

In the present invention, one kind selected from compounds represented by the general formulas (1), (2) and (3) may be used alone, or two or more kinds may be used in combination. .

The ink layer may contain other coloring material together with the compound of the present invention. In particular, the compound of the present invention is preferably contained in the magenta color forming ink layer together with another magenta coloring material.

As a colorant which can be used in combination, a magenta pigment is preferable. Examples of the inorganic pigment include cadmium red, red shell, silver vermilion, red lead, antimony vermilion, etc., and the organic pigment is an azo lake type azo pigment. , Insoluble azo pigments (monoazo, disazo, condensed azo pigments), condensed azo pigments, thioindigo pigments which are condensed polycyclic pigments, and perinone pigments.

The above azo lake azo pigments include
Brilliant Carmin 6B (pigment R
ed 57: 1), lake red (pigment R)
ed53: 1), Permanent Red F5R (pigm
ent Red 48), Resole Red (pigme
nt Red 49), Persian Orange (pigme
nt Orange 17), Black Sea Orange (pi)
gment Orange 18), Helio Orange T
D (pigment Orange 19), pigment scarlet (pigment Red 60:
1), Brilliant Scarlet G (pigment)
64: 1), Heliored RMT (pigment R)
ed 51), Bordeaux 10B (pigment Re)
d 63), Helio Bordeaux BL (pigment R)
ed 54) and the like.

Examples of the insoluble azo (monoazo, disazo, condensed azo) pigment include, for example, para red (pigme).
nt Red 1), Rake Red 4R (pigmen)
tRed 3), Permanent Orange (pigmen)
t Orange 5), Permanent Red FR2
(Pigment Red 2), permanent red FRLL (pigment Red 9), permanent red FGR (pigment Red 112),
Brilliant Carmine BS (pigmentRed 1
14), permanent carmin FB (pigment)
Red5), P.I. V. Carmine HR (pigment
Red 150), Permanent Carmine FBB (pi
gment Red 146), Nova Palm Red F3
RK-F5RK (pigment Red 170),
Nova Palm Red HFG (pigment Orange)
e 38), Nova Palm Red HF4B (pigmen)
t Red 187), Nova Palm Orange HL. HL
-70 (pigment Orange 36), P.I.
V. Carmine HF4C (pigmentRed18
5), Hosta Verm Brown HFR (pigment)
Brown25), Balkan orange (pigment)
Orange 16), pyrazolone orange (pig
ment Orange 13), pyrazolone red (pigment Red 38) and the like.

The coloring material in the ink layer is represented by the general formula (1),
It contains at least one compound selected from the compounds represented by (2) and (2), and is preferably contained in an amount of 20 to 80% by mass, more preferably 20 to 40% by mass. When a magenta pigment other than the present invention is used as the magenta coloring material and is used in combination with the compound of the present invention, the total content of the magenta pigment and the compound of the present invention in the ink layer should be within the above range.

The average particle size of the compound of the present invention and the coloring material used in combination, if desired, is preferably 0.03 to 1 μm, more preferably 0.05 to 0.5 μm. If the particle size is less than 0.03 μm, the dispersion cost may increase or the dispersion may cause gelation, while if it exceeds 1 μm, coarse particles in the color material may cause the ink layer and the image receiving layer of the image receiving sheet. May interfere with the adhesion to.

<Binder> The ink layer is mainly composed of a coloring material and a thermoplastic binder. The ink layer is a layer that is meltable or softened when heated and is capable of being transferred for each layer containing a coloring material, a binder and the like, but it is not necessary to transfer in a completely molten state.

As the binder of the ink layer, it is preferable to use an amorphous and transparent thermoplastic resin. As the thermoplastic resin, a resin having a melting point, a softening point or a glass transition temperature (Tg) within the range of 20 to 200 ° C. is used. By having an appropriate thermoplasticity, it becomes possible to perform thermal transfer to a transfer target during exposure and heating.

In the present invention, it is preferable to contain a thermoplastic resin having a melting point, a softening point or Tg of 20 to 150 ° C. Specifically, ethylene copolymers, polyamide resins, polyester resins, styrene resins, polyurethane resins, polyolefin resins, acrylic resins, vinyl chloride resins, cellulose resins, rosin resins, polyvinyl alcohol resins. Examples thereof include resins, polyvinyl acetal resins, ionomer resins, petroleum resins, and resins for ink layer binders described in JP-A-6-312583.

In addition to the above-mentioned thermoplastic resins, elastomers such as natural rubber, styrene-butadiene rubber, isoprene rubber, chloroprene rubber and diene copolymers;
It is also possible to use ester gum, rosin maleic acid resin, rosin phenol resin, rosin derivative such as hydrogenated rosin; and polymer compounds such as phenol resin, terpene resin, cyclopentadiene resin, aromatic hydrocarbon resin and waxes. it can.

By using a binder having a high thermal decomposability, it is possible to form an image by ablation transfer. Such binders include polymeric substances that undergo rapid acid-catalyzed partial decomposition, desirably at temperatures below 200 ° C., when measured under equilibrium conditions, and specifically include nitrocelluloses, polycarbonates and J.S. M. J. Frechet, F.F. Bouchard, J.M. M. Houlihan, B.H. Kryzuku
ke) and E. Eichler; Imaging Science (Imaging Science)
ce), 30 (2), pages 59-64 (1986), and polymers, and polyurethanes,
Included are polyesters, polyorthoesters, and polyacetals, and copolymers thereof. Further, these polymers, together with their decomposition mechanism, are described in detail in the above-mentioned report of Holyhan et al.

The binder content may be adjusted so as to obtain a desired concentration at a desired coating film thickness, and the binder content is preferably 20 to 80% by mass.
The thickness of the ink layer is preferably 0.2 to 1.5 μm. More preferably, it is 0.2 to 0.8 μm.

<Photothermal Conversion Layer> The photothermal conversion layer is a layer having a photothermal conversion function. The light-heat conversion layer is preferably provided between the support and the ink layer, more preferably between the support or the cushion layer or the easily adhesive layer and the ink layer. The light-heat converting layer basically contains a binder and a light-heat converting substance.

As the binder in the photothermal conversion layer,
Resins with high Tg and high thermal conductivity, such as polymethylmethacrylate, polycarbonate, polystyrene, ethylcellulose, nitrocellulose, polyvinyl alcohol,
General heat resistant resins such as polyvinyl chloride, polyamide, polyamic acid, polyimide, polyetherimide, polysulfone, polyethersulfone, aramid, etc., polythiophenes, polyanilines, polyacetylenes, polyphenylenes, polyphenylene sulfides, polypyrrole Polymeric compounds consisting of classes and derivatives thereof, or mixtures thereof can be used.

Water-soluble polymers can also be used. The water-soluble polymer also has good releasability from the ink layer,
It is also preferable in that it has good heat resistance during laser irradiation and has little scattering even when it is heated excessively.

From the viewpoint of heat resistance, JP-A-8-2679 is used.
As a photothermal conversion layer binder having high heat resistance as shown in No. 16, in a thermal decomposition measurement by TGA (thermogravimetric analysis), a mass reduction rate of 50% was obtained in a nitrogen stream at a temperature rising rate of 10 ° C./min. The temperature at which it becomes (TGA ₅₀ ) is 360
It is preferable to use a binder having a temperature of ℃ or more. As such a binder, a part of polyvinyl alcohol and polyamic acid among various engineering plastics have good solubility in a general-purpose solvent and are suitable for coating.

Further, by incorporating various releasing agents into the photothermal conversion layer, the peelability between the photothermal conversion layer and the ink layer can be improved and the sensitivity can be improved. Examples of the release agent include silicone-based release agents (polyoxyalkylene-modified silicone oil, alcohol-modified silicone oil, etc.), fluorine-based surfactants (perfluorophosphate ester-based surfactants, etc.), and various other surfactants. Is effective.

When a photothermal conversion substance is used, it varies depending on the light source, but a substance that absorbs light and efficiently converts it into heat is preferable. For example, when a semiconductor laser is used as a light source, a substance having an absorption band in the near infrared region. Is preferred. As the near-infrared light absorber, for example, carbon black or cyanine-based, polymethine-based, azurenium-based, squalium-based,
Organic compounds such as thiopyrylium-based, naphthoquinone-based and anthraquinone-based dyes, phthalocyanine-based, azo-based and thioamide-based organometallic complexes are preferably used, and specifically, JP-A-63-139191 and 64-33547.
Nos. 1,160,683 and 1,280,750.
No. 1, No. 1-293342, No. 2-2074, No. 3-
26593, 3-30991, 3-34891.
No. 3, No. 3-36093, No. 3-36094, No. 3-
36095, 3-42281, 3-97589.
No. 3,103,476 and the like. Among these, dyes having an absorption maximum at 700 to 850 nm are preferable. Further, it is desirable that the absorbance at the laser wavelength used be within the range of 0.3 to 1.5. These can be used alone or in combination of two or more.

Further, a metal oxide having an absorption band in the near infrared region can also be used, and the following ones can be mentioned.

Iron oxide (Fe ₂ O ₃ ), lead oxide (Pb ₃ O ₄ ),
Yellow lead (PbCrO ₄ ), silver vermilion (HgS), ultramarine blue (Na ₆ A
l ₆ Si ₆ O ₂₄ S ₄ ), cobalt oxide (CoO or Co ₃ O)
₄ ), titanium dioxide (TiO ₂ ), titanium dioxide coated mica (TiO ₂ / K ₂ O / 3Al ₂ O ₃ / 6SiO ₂ / 2H
₂ O), strontium chromate (SrCrO ₄ ), titanium yellow (nickel yellow, chrome yellow), iron black (Fe ₃ O ₄ ), molybdenum red (PbCrO ₄ ).
・ NPbMoO ₄・ mPbSO ₄・ xAl (OH) ₃ ),
Molybdenum white (ZnMoO ₄ · ZnO or CaZ
nMoO ₄ · CaCO ₃ ), lithopone (BaSO ₄ + Zn)
S), cadmium red (CdS · nCdSe), bronze powder (alloy of copper and zinc), aluminum powder.

The thickness of the photothermal conversion layer is preferably 0.05 to 3 μm, more preferably 0.1 to 1.0 μm. The content of the photothermal conversion substance in the photothermal conversion layer is usually determined so that the absorption at the wavelength of the light source used for image recording is 0.3 to 3.0, more preferably 0.7 to 2.5. it can. When carbon black is used as the light-heat conversion layer, if the thickness of the light-heat conversion layer exceeds 1 μm, the sensitivity tends to decrease instead of the occurrence of focusing due to overheating of the ink layer. It may be appropriately selected because it changes depending on the absorbance of the photothermal conversion layer.

<Support> As a support for the ink sheet, a support having rigidity, good dimensional stability, excellent smoothness, transmitting laser light used for recording, and enduring heat during image formation is used. Any type of paper, such as paper, coated paper, synthetic paper (polypropylene, polystyrene, or composite material obtained by laminating them with paper), vinyl chloride resin sheet, ABS resin sheet, polyethylene Terephthalate (PET) film, polybutylene terephthalate film, polyethylene naphthalate (PE
N) film, polyacrylate film, polycarbonate (PC) film, polyetherketone film, polysulfone film, polyethersulfone film, polyetherimide film, polyimide film, polyethylene (PE) film, polypropylene (PP) film, polystyrene (PS) ) A single layer such as a film, a syndiotactic polystyrene (SPS) film, a stretched nylon film, a polyacetate film, a polymethylmethacrylate (PMMA) film, or various plastic films or sheets in which two or more layers thereof are laminated, and various metals. Formed film or sheet, film or sheet formed of various ceramics, and further metal plate of aluminum, stainless steel, chrome, nickel, etc. That a metal thin film to the paper was resin coated and laminated or deposited it can be mentioned.

These supports may be subjected to various processes such as dimensional stabilization and antistatic. Examples of the antistatic agent include cationic, anionic, and nonionic surfactants, polymeric antistatic agents, conductive fine particles, and "1129".
The chemical compounds described in “Chemical products of No. 0”, Kagaku Kogyo Nipposha, pages 875-876, etc. are widely used.

Further, these supports may be subjected to a conventionally known surface modification treatment. Examples of these surface modification treatments include flame radiation treatment, sulfuric acid treatment, corona discharge treatment, plasma treatment, glow discharge treatment and the like. Further, an adhesive layer may be provided on the support so that each of the layers described below can be well coated on the support.

As the adhesive layer, conventionally known materials can be used without particular limitation. Examples of the method for providing the adhesive layer include water-based resin coating, solvent-based resin coating, water-based latex coating, hot melt coating and the like. Generally, it is advantageous to provide an adhesive layer at the time of manufacturing the support from the viewpoints of cost and stability. From this point, for example, acrylic resin, polystyrene resin, polyester resin, urethane resin, polyethylene / vinyl acetate resin A method of coating a latex such as a styrene resin is preferable, but the method is not particularly limited thereto. Such a base film with an adhesive layer is sold by each company, and these can be preferably used.

If an image is formed by irradiating a laser beam from the ink sheet side, it is desirable that the support of the ink sheet is transparent.

The thickness of the support of the ink sheet is preferably thinner than that of the image receiving sheet, and is preferably about 30 to 150 μm, and more preferably 50 to 100 μm, for easy superposition.

<Backcoat layer> A backcoat layer is preferably provided on the side of the ink sheet opposite to the photothermal conversion layer and the ink layer. The binder used in this backcoat layer is gelatin, polyvinyl alcohol, or the like.
Methyl cellulose, nitrocellulose, acetyl cellulose, aromatic polyamide resin, silicone resin, epoxy resin, alkyd resin, phenol resin, melamine resin, fluorine resin, polyimide resin, urethane resin, acrylic resin, urethane modified silicone resin, polyethylene resin, polypropylene resin General-purpose polymers such as polyester resin, Teflon (R) resin, polyvinyl butyral resin, vinyl chloride resin, polyvinyl acetate, polycarbonate, organic boron compound, aromatic esters, fluorinated polyurethane, and polyether sulfone can be used. .

The use of a water-soluble crosslinkable binder as the binder of the back coat layer and cross-linking are effective in preventing the matting material from falling off and improving the scratch resistance of the back coat. It is also effective in blocking during storage.
As the cross-linking means, any one of heat, actinic rays and pressure or a combination thereof can be adopted without any particular limitation, depending on the characteristics of the cross-linking agent used.

In some cases, an optional adhesive layer may be provided on the side of the support on which the backcoat layer is provided in order to impart adhesiveness to the support.

The back coat layer preferably contains a matting material. As the matting material preferably added, organic or inorganic fine particles can be used. Examples of the organic matting material include fine particles of PMMA, PS, PE, PP and other radical polymerization type polymers, and fine particles of condensation polymers such as polyester and polycarbonate.

The back coat layer is preferably provided in an amount of about 0.5 to 5 g / m ² . If it is less than 0.5 g / m ² , the coating property is unstable and problems such as powder drop of the mat material are likely to occur. Further, when it is applied over 5 g / m ² , the suitable particle diameter of the matting material becomes very large and the back coat causes embossing of the ink layer surface,
In particular, thermal transfer in which a thin ink layer is transferred tends to cause missing or unevenness in a recorded image.

The matting material preferably has a number average particle size larger than the film thickness of only the binder of the back coat layer by 1 to 20 μm. Among the mat materials, particles having a particle size of 2 μm or more are required to be 1 mg / m ² or more, preferably 2 to 6
It is 00 mg / m ² . This improves especially foreign matter failures.

A narrow particle size distribution is used such that the value σ / rn (= coefficient of variation of particle size distribution) obtained by dividing the standard deviation of the particle size distribution by the number average particle size is 0.3 or less. As a result, defects generated by particles having an abnormally large particle size can be improved, and desired performance can be obtained with a smaller addition amount.
The coefficient of variation is more preferably 0.15 or less.

In order to prevent foreign matter from adhering to the back coat layer due to frictional electrification with the conveying roll during sheet feeding,
It is preferable to add an antistatic agent. As the antistatic agent, a cationic surfactant, an anionic surfactant,
In addition to nonionic surfactants, polymeric antistatic agents, conductive fine particles, "11290 chemical products" (supra), 875-875
The compounds described on page 876 etc. are widely used. Among the above substances, metal oxides such as carbon black, zinc oxide, titanium oxide and tin oxide, and conductive fine particles such as organic semiconductors are preferably used as the antistatic agent that can be added. In particular, it is preferable to use the conductive fine particles because the antistatic agent is not dissociated from the backcoat layer and a stable antistatic effect is obtained regardless of the environment.

It is also possible to add various activators, a release agent such as silicone oil, a fluorine-based resin, etc. to the back coat layer in order to impart coatability and releasability. The back coat layer is a TMA (T
thermomechanical Analysis)
It is particularly preferable when the softening point measured by the method is 70 ° C. or lower. The TMA softening point is obtained by observing the phase of an object to be measured at a constant rate of temperature increase while applying a constant load to the object. In the present invention, the temperature at which the phase of the measurement object begins to change is defined as the TMA softening point.
The measurement of the softening point by TMA can be performed by Therm
It can be performed using a device such as oflex.

<Cushion Layer> A cushion layer is provided between the support and the light-heat conversion layer in order to enhance the adhesion between the ink sheet and the image-receiving sheet during exposure, or a support having a cushioning property is used. preferable. This cushion layer is a layer having a heat softening property or elasticity, and a material that can be sufficiently softened and deformed by heating, or a material having a low elastic modulus or a material having rubber elasticity may be used. The cushion layer is a layer having a cushioning property, and the elastic modulus and the penetration can be used as a guideline indicating the cushioning property here. For example, the elastic modulus at 25 ° C. is 1 to 25
0 kg / mm ² or JIS K2530-19
It has been confirmed that a layer having a penetration of 15 to 500, more preferably about 30 to 300, as defined in No. 76, has a cushioning property suitable for forming a color proof image for color proofing. The degree to be performed varies depending on the intended use of the image, and may be appropriately selected.

The cushion layer has a TMA softening point of preferably 70 ° C. or lower, more preferably 60 ° C. or lower. Although the preferable characteristics of the cushion layer cannot necessarily be specified only by the type of material, the preferable characteristics of the material itself include polyolefin resin and ethylene-
Vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, polybutadiene resin, styrene-butadiene copolymer (SBR), styrene-ethylene-butene-styrene copolymer (SEBS), acrylonitrile-butadiene copolymer (NBR) , Polyisoprene resin (I
R), styrene-isoprene copolymer (SIS), acrylic ester copolymer, polyester resin, vinyl chloride vinyl acetate resin, polyurethane resin, acrylic resin, butyl rubber,
Examples thereof include polynorbornene. Among these, those having a relatively low molecular weight are likely to satisfy the requirements of the present invention, but they are not necessarily limited in relation to the material.

The cushion layer can be provided by solvent coating, but it can also be coated and formed in the state of an aqueous dispersion such as latex or emulsion. In addition to this, a water-soluble resin can also be used. These resins can be used alone or as a mixture, if necessary.

In addition, materials other than those described above can be added with various additives to impart preferable characteristics to the cushion layer. Examples of such additives include low melting point substances such as wax and plasticizers. Specific examples thereof include phthalic acid ester, adipic acid ester, glycol ester, fatty acid ester, phosphoric acid ester and chlorinated paraffin. Further, for example, various additives described in "Practical Handbook of Additives for Plastics and Rubbers", Kagaku Kogyo Co., Ltd. (published in 1970) and the like can be added. The amount of these additives to be added may be selected in such an amount as to bring out preferable physical properties in combination with the cushion layer material serving as a base, and is not particularly limited, but generally 10% of the total amount of the cushion layer material is used. It is preferably not more than 5% by mass, more preferably not more than 5% by mass.

As a method for forming the cushion layer, a material obtained by dissolving the above materials in a solvent or dispersing them in a latex form is applied by a blade coater, a roll coater, a bar coater, a curtain coater, a gravure coater or the like, and extrusion lamination by hot melt. Laws can be applied.
Further, as the special cushion layer, it is also possible to use a resin layer having a void structure obtained by foaming a thermosoftening or thermoplastic resin.

The thickness of the cushion layer is preferably 0.5 to 10 μm, more preferably 1 to 7 μm.

<Peeling Layer> In addition, a peeling layer or the like may be provided between the photothermal conversion layer and the ink layer. As the release layer, methyl cellulose, carboxymethyl cellulose,
Cellulose such as hydroxyethyl cellulose and nitrocellulose, vinyl resins such as polyvinyl alcohol, polyvinyl acetal and polyvinyl butyral, and water-soluble resins such as gelatin can be used. Of these, gelatin is particularly preferable.

The thickness of the peeling layer is preferably as thin as possible in order not to reduce the sensitivity, and is 0.01 to 0.5 μm.
Is good.

<Image Receiving Sheet> Next, an image receiving sheet used together with the ink sheet of the present invention will be described.

The image-receiving sheet is for receiving the ink layer peeled imagewise from the ink sheet to form an image. Usually, it has a support and an image receiving layer, but it may be formed only from the support. A cushion layer may be provided to improve the adhesion with the ink sheet.

Since the ink layer melted by heat is transferred to the image-receiving sheet, it is desirable that it has appropriate heat resistance and excellent dimensional stability so that an image is properly formed. The image-receiving layer formed on the support comprises a binder and various additives and a matting material which are added as necessary. Further, in some cases, it is formed only by the binder.

<Binder> As the binder for the image-receiving layer having a good image-receiving property, a polyvinyl acetate emulsion adhesive, a chloroprene adhesive, an adhesive such as an epoxy resin adhesive, a natural rubber, a chloroprene rubber, a butyl rubber, Polyacrylic ester type, nitrile rubber type, polysulfide type, silicon rubber type, rosin type, vinyl chloride type, petroleum type resin and ionomer resin adhesives,
Examples thereof include recycled rubber, SBR, polyisoprene, polyvinyl ether and the like.

When the image formed on the image receiving layer is retransferred to another recording medium by further heating and / or pressing, a resin having a relatively small polarity (small SP value) is used as the image receiving layer. Is particularly preferred. For example polyethylene,
Examples thereof include polypropylene, ethylene-vinyl chloride copolymer, polybutadiene resin, ethylene-acrylic copolymer, vinyl chloride resin, various modified olefins and the like.

The film thickness of the image receiving layer is usually 1 to 10 μm, but it is not limited to this when the cushion layer is used as the image receiving layer. As the cushion layer, it is preferable to provide the material described for the ink sheet in the range of 15 to 30 μm.

As the support of the image-receiving sheet, the same support as described for the ink sheet can be used, but the thickness is preferably 30 to 200 μm, more preferably 50 to 1
It is 25 μm.

In addition, if necessary, a peeling layer may be provided between the image receiving layer and the support, more preferably between the image receiving layer and the cushion layer, and a back coat layer, an antistatic layer or the like may be provided on the surface of the support opposite to the image receiving layer. Can be provided.

An image forming method using the ink sheet of the present invention and the image receiving sheet is described in JP-A-2001-13.
See 8640, paragraphs “0069”-“0073”.

[0087]

The present invention will be described below with reference to examples, but the embodiments of the present invention are not limited thereto. Unless otherwise specified, "part" in the examples means "part by mass" of the effective solid content, and "%" means "% by mass".

Example 1 <Preparation of Ink Sheet> Ink sheets 1 to 1 were prepared as follows.
10 was produced.

<Ink sheet 1> A 75 μm thick polyethylene terephthalate (PET) film (T100 manufactured by Mitsubishi Kagaku Polyester Co., Ltd.) was coated with the photothermal conversion layer coating solution 1 having the following composition and dried, and the absorbance at 808 nm was about 1. Two
The photothermal conversion layer of was formed. The thickness of the photothermal conversion layer after drying was about 0.3 μm. Then, an intermediate layer coating liquid 1 having the following composition was applied onto the photothermal conversion layer by a wire bar and dried to form an intermediate layer having a thickness of about 0.1 μm, and this coated product was wound up.

After storing the above-mentioned wound product at 60 ° C. for 3 days, the ink layer coating solution 1 having the following composition was applied onto the intermediate layer by a wire bar and dried, and the thickness after drying was 0.5 μm.
The ink layer of No. 1 was formed to prepare an ink sheet 1. This ink layer had a Macbeth TD-904 green filter density of 0.69. (Photothermal conversion layer coating liquid 1) Polyvinyl butyral (Denka Butyral # 3000-4: manufactured by Denki Kagaku Kogyo Co., Ltd.) 8 parts Infrared absorbing dye (IR-1: absorption maximum 825 nm) 2 parts Isocyanate compound (Sumijour N3300: Sumitomo Bayer Urethane) 0.8 parts Methyl ethyl ketone (MEK) 60 parts Cyclohexanone 30 parts

[0091]

[Chemical 7]

(Intermediate layer coating liquid 1) Gelatin 2.0 parts Surfactant (FT-251: manufactured by Neos) 1.2 parts Water 77.2 parts i-Propyl alcohol 19.6 parts (Ink layer coating liquid 1) ) Coloring material (Ex. 1-1) 2.79% Binder (Dianal BR-105: Mitsubishi Rayon Co., Tg: 55 ° C) 5.69% Thermoplasticizer (Rikemar HT-10: Riken Vitamin Co.) 0 0.75% Sliding agent (Rikestar EW-90: Riken Vitamin Co., Ltd.) 0.75% Surfactant (MegaFac F-178K: Dainippon Ink and Chemicals Co., Ltd.) 30% MEK / Terpen solution 0.09% Methyl ethyl ketone 26.93% Cyclohexanone 63% <Ink sheet 2> An ink sheet was prepared in the same manner except that the color material of the ink layer coating liquid 1 in the ink sheet 1 was changed to the compound 1-2. 2 was produced.

<Ink Sheet 3> Ink sheet 3 was prepared in the same manner except that the color material of ink layer coating liquid 1 in ink sheet 1 was changed to compound 1-3.

<Ink Sheet 4> Ink sheet 4 was prepared in the same manner except that the color material of ink layer coating liquid 1 in ink sheet 1 was changed to compound 1-4.

<Ink Sheet 5> Ink Sheet 5 was prepared in the same manner except that the color material of Ink Layer Coating Liquid 1 in Ink Sheet 1 was changed to Compound 1-5.

<Ink Sheet 6> An ink sheet 6 was prepared in the same manner except that the color material of the ink layer coating liquid 1 in the ink sheet 1 was changed to the compound 2-1.

<Ink sheet 7> Ink sheet 7 was prepared in the same manner except that the color material of ink layer coating liquid 1 in ink sheet 1 was changed to compound 3-1.

<Ink Sheet 8> Ink Sheet 8 was prepared in the same manner except that the color material of Ink Layer Coating Liquid 1 in Ink Sheet 1 was changed to Compound 3-2.

<Ink sheet 9> Ink sheet 9 was prepared in the same manner except that the color material of ink layer coating liquid 1 in ink sheet 1 was changed to compound 3-3.

<Ink Sheet C> The color material of the ink layer coating liquid 1 in the ink sheet 1 is C.I. I. PigmentR
Ink sheet C (comparative example) was prepared in the same manner except that the ed ratio was changed to 57: 1.

<Preparation of Ink Sheet 10> Thickness 75 μm
A back coat layer having the following composition was applied to the PET film (above: T100) of (1) by a wire bar and dried. The coating amount of the back coat layer was 0.7 g / m ² .

On the surface opposite to the back coat layer, a cushion layer coating solution having the following composition was applied by a reverse roll coater and dried to form a cushion layer having a thickness after drying of 7 μm. The light-to-heat conversion layer coating liquid 2 having the following composition is applied by a wire bar and dried to give 808n.
A photothermal conversion layer having an absorbance of m of about 0.7 was formed. The dry coating weight of the photothermal conversion layer was 0.67 g / m ² .

Next, the following ink layer coating liquid 2 was applied onto the photothermal conversion layer with a wire bar and dried to form an ink layer having a film thickness of 0.6 μm. This ink layer has a Macbeth TD-904 green filter density of 0.6.
It was 9. (Backcoat layer coating liquid) Polyester resin (Byron 200: manufactured by Toyobo Co., Ltd.) 8.64 parts Polymethylmethacrylate resin particles (MX-500H: manufactured by Soken Chemical Industry Co., Ltd.) 0.36 parts Methyl ethyl ketone 54.6 parts Toluene 27.3 Parts Cyclohexanone 9.1 parts (cushion layer coating liquid) Styrene / isoprene copolymer (Clayton D-1117: Shell Chemical Co., Ltd.) 4.0 parts Methyl ethyl ketone 57.0 parts Toluene 38.0 parts (photothermal conversion layer coating liquid 2 ) Polyvinyl alcohol (EG-30: manufactured by Nippon Synthetic Chemical Industry) 6 parts Carbon black dispersion (SD-9020: manufactured by Dainippon Ink and Chemicals, concentration 40%) 4 parts Fluorine-based surfactant (FT-251: supra). 0.05 part Water 490 parts (ink layer coating liquid 2) Color material (Example 1-1) 2.60% Dispersant (Solspar) 24000: manufactured by ICI Co., Ltd. 0.78% Binder 1 (Haimer ST-95: manufactured by Sanyo Kasei Co., Tg: 42 ° C, softening point: 95 ° C) 6.10% Binder 2 (Dianal BR-102: Mitsubishi Rayon Co., Ltd.) Manufactured by Tg: 20 ° C.) 0.50% Surfactant (MegaFac F-178K: aforesaid) 30% MEK / Terpen solution 0.07% Methyl ethyl ketone (MEK) 26.95% Cyclohexanone 63% <Image formation and Evaluation> A magenta image was formed on an image receiving sheet (Konica Corporation image receiving sheet for color decision 2 CD2-1R) using each of the ink sheets thus produced. That is, an exposure device (TC-P4000) is applied to the ink sheet.
Using a resolution of 2400 dpi (dpi = dot number / 2.54 cm) and an exposure energy of 300 mJ / cm ^2.
The image formed on the ink layer was transferred to the image receiving sheet by imagewise exposure with the laser light of.

The following evaluations were carried out for the laser wavelength absorbance of the ink sheet, the reflection density reduction rate during exposure, and the fine line reproducibility of the transferred image. For the measurement of absorbance, a self-recording spectrophotometer U
-3000 (manufactured by Hitachi, Ltd.) and Macbeth D-196 (manufactured by Macbeth) were used for measuring the reflection density.

<< Density Reduction Rate at Exposure >> Ink layer transferred to image receiving sheet by thermal lamination method (comparative)
Then, the reflection density on the image-receiving sheet of 100% solid exposure (laser exposure) under the above conditions was measured, and the difference was defined as the density reduction rate during exposure.

<< Reproducibility of Fine Lines >> The reproducibility of fine lines in the main and sub-scanning directions at 2400 dpi was visually observed and evaluated in four levels.

⊚: No transfer failure: Faint, but usable as proof ×: Faint and unusable as proof XX: No transfer <Preparation and evaluation of retransfer image> Was secondarily transferred to Tokubishi Art Paper (manufactured by Mitsubishi Paper Mills) with a laminator (T-P400) to obtain a retransfer image. Immediately after that, the image was stored for 7 days under a white fluorescent lamp of 8000 lux, and the density difference and the color difference were determined and used as an index of light resistance.

<Density Reduction Rate> The density immediately after the secondary transfer of the solid portion of the retransfer image and the density after storage for 7 days under a white fluorescent lamp of 8000 lux were measured to obtain the density reduction rate.

<< Color Difference >> The image hue immediately after the secondary transfer and the hue after 7 days under a white fluorescent lamp were measured by a colorimeter (Macbeth SPM1
00-II), and the color difference (ΔE) was calculated from the following formula.

ΔE = [(L ₀ ^* -L ₁ ^* ) ^0.5 + (a ₀ ^* -a ₁
^* ) ^0.5 + (b ₀ ^* -b ₁ ^* ) ^0.5 ] ² where 0 and 1 are ² in the (CIE, L ^* a ^* b ^* ) standard.
The image hue immediately after the next transfer and the image hues L ^* , a ^* , and b ^* after 7 days under a white fluorescent lamp are shown.

The results are also shown in Table 1.

[0112]

[Table 1]

As is clear from this result, the image obtained from the ink sheet of the present invention is superior in all evaluations to the image obtained from the comparative ink sheet.

[0114]

According to the ink sheet of the present invention, the density of the coloring material is less likely to decrease due to the thermal decomposition of the coloring material even at a high temperature during laser recording, and the decomposition of the coloring material is small when the final image is stored for a long time. It is possible to obtain a high-definition image with less density reduction and hue variation.

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2H111 AA04 AA26 AA27 AA35 BA03                       BA04 BA32 BA38 BA41 BA71                       BA76

Claims (12)

[Claims] 1. A laser thermal transfer ink sheet having at least a photothermal conversion layer and an ink layer on a support, wherein the ink layer contains a quinacridone compound represented by the following general formula (1). Ink sheet for laser thermal transfer recording. [Chemical 1] [In the formula, R ₁ and R ₂ are each a hydrogen atom, a halogen atom,
It represents an alkyl group having 1 to 5 carbon atoms or an alkoxy group having 1 to 5 carbon atoms, and R ₃ is a hydrogen atom or 1 carbon atom.
Represents an alkyl group having 5 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or an oxo group. m and n each represent an integer of 1 to 4, and k represents an integer of 1 to 2. When m or n is 2 or more,
A plurality of R ₁ or R ₂ may be the same or different. ] 2. A laser thermal transfer recording ink sheet having at least a photothermal conversion layer and an ink layer on a support, wherein the ink layer contains an anthraquinone compound represented by the following general formula (2). Characteristic laser thermal transfer recording ink sheet. [Chemical 2] [In the formula, R ₄ , R ₅ , R ₆ , R ₇ and R ₈ are each a hydrogen atom, a halogen atom, a hydroxyl group, an amino group, an alkyl group having 1 to 5 carbon atoms, and an alkyl group having 1 to 5 carbon atoms. It represents an alkoxy group or the following structure (a). p represents an integer of 1 to 4, and when p is 2 or more, a plurality of R ₄ may be the same or different. ] [Chemical 3] 3. A laser thermal transfer recording ink sheet having at least a photothermal conversion layer and an ink layer on a support, wherein the ink layer contains a perylene compound represented by the following general formula (3). Characteristic laser thermal transfer recording ink sheet. [Chemical 4] [In the formula, R ₉ and R ₁₀ are each a hydrogen atom, a halogen atom, a hydroxyl group, an amino group, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an alkyl group or an alkoxy group. Represents a substituted phenyl group. ] 4. The R ₁ and R ₂ in the general formula (1) are both methyl groups, m = n = 1, and R ₃ is a hydrogen atom. Ink sheet for laser thermal transfer recording. 5. The method according to claim 1, wherein R ₁ and R ₂ in the general formula (1) are both chlorine atoms, m = n = 1, and R ₃ is a hydrogen atom. Ink sheet for laser thermal transfer recording. 6. R ₁ and R ₂ in the general formula (1) are both hydrogen atoms, m = n = 1, and R ₃ is an oxo group, and k = 2. The laser thermal transfer recording ink sheet according to claim 1. 7. R ₄ , R ₆ and R _{7 in the} general formula (2).
Are both hydrogen atoms, p = 1, R ₅ is an amino group, and R ₈ is a structure (a).
The ink sheet for laser thermal transfer recording described. 8. The ink sheet for laser thermal transfer recording according to claim 3, wherein R ₉ and R ₁₀ in the general formula (3) are both methyl groups. 9. The ink sheet for laser thermal transfer recording according to claim 3, wherein R ₉ and R ₁₀ in the general formula (3) are both 4-ethoxyphenyl groups. 10. The ink sheet for laser thermal transfer recording according to claim 3, wherein R ₉ and R ₁₀ in the general formula (3) are both 3,5-dimethylphenyl groups. 11. The photothermal conversion layer contains at least one of carbon black, a metal oxide, and an infrared absorbing dye having an absorption maximum at 700 to 850 nm, and the absorbance at the absorption maximum wavelength is 0.3 to 1. 5. The ink sheet for laser thermal transfer recording according to claim 1, wherein the ink sheet is 5. 12. The ink layer comprises at least one compound selected from the compounds represented by the general formulas (1), (2) and (3), and a melting point, a softening point or a glass transition temperature. 2. 20 to 80% by mass and 80 to 20% by mass of a polymer compound having a temperature of 20 to 150 ° C., respectively, and an ink layer thickness of 0.2 to 1.5 μm. 11. An ink sheet for laser thermal transfer recording according to any one of items 1 to 11.